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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
    md.c : Multiple Devices driver for Linux
      Copyright (C) 1998, 1999, 2000 Ingo Molnar
 
      completely rewritten, based on the MD driver code from Marc Zyngier
 
    Changes:
 
    - RAID-1/RAID-5 extensions by Miguel de Icaza, Gadi Oxman, Ingo Molnar
    - RAID-6 extensions by H. Peter Anvin <hpa@zytor.com>
    - boot support for linear and striped mode by Harald Hoyer <HarryH@Royal.Net>
    - kerneld support by Boris Tobotras <boris@xtalk.msk.su>
    - kmod support by: Cyrus Durgin
    - RAID0 bugfixes: Mark Anthony Lisher <markal@iname.com>
    - Devfs support by Richard Gooch <rgooch@atnf.csiro.au>
 
    - lots of fixes and improvements to the RAID1/RAID5 and generic
      RAID code (such as request based resynchronization):
 
      Neil Brown <neilb@cse.unsw.edu.au>.
 
    - persistent bitmap code
      Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
 
 
    Errors, Warnings, etc.
    Please use:
      pr_crit() for error conditions that risk data loss
      pr_err() for error conditions that are unexpected, like an IO error
          or internal inconsistency
      pr_warn() for error conditions that could have been predicated, like
          adding a device to an array when it has incompatible metadata
      pr_info() for every interesting, very rare events, like an array starting
          or stopping, or resync starting or stopping
      pr_debug() for everything else.
 
 */
 
 #include <linux/sched/mm.h>
 #include <linux/sched/signal.h>
 #include <linux/kthread.h>
 #include <linux/blkdev.h>
 #include <linux/blk-integrity.h>
 #include <linux/badblocks.h>
 #include <linux/sysctl.h>
 #include <linux/seq_file.h>
 #include <linux/fs.h>
 #include <linux/poll.h>
 #include <linux/ctype.h>
 #include <linux/string.h>
 #include <linux/hdreg.h>
 #include <linux/proc_fs.h>
 #include <linux/random.h>
 #include <linux/major.h>
 #include <linux/module.h>
 #include <linux/reboot.h>
 #include <linux/file.h>
 #include <linux/compat.h>
 #include <linux/delay.h>
 #include <linux/raid/md_p.h>
 #include <linux/raid/md_u.h>
 #include <linux/raid/detect.h>
 #include <linux/slab.h>
 #include <linux/percpu-refcount.h>
 #include <linux/part_stat.h>
 
 #include <trace/events/block.h>
 #include "md.h"
 #include "md-bitmap.h"
 #include "md-cluster.h"
 
 /* pers_list is a list of registered personalities protected
  * by pers_lock.
  * pers_lock does extra service to protect accesses to
  * mddev->thread when the mutex cannot be held.
  */
 static LIST_HEAD(pers_list);
 static DEFINE_SPINLOCK(pers_lock);
 
 static struct kobj_type md_ktype;
 
 struct md_cluster_operations *md_cluster_ops;
 EXPORT_SYMBOL(md_cluster_ops);
 static struct module *md_cluster_mod;
 
 static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
 static struct workqueue_struct *md_wq;
 static struct workqueue_struct *md_misc_wq;
 static struct workqueue_struct *md_rdev_misc_wq;
 
 static int remove_and_add_spares(struct mddev *mddev,
                  struct md_rdev *this);
 static void mddev_detach(struct mddev *mddev);
 
 /*
  * Default number of read corrections we'll attempt on an rdev
  * before ejecting it from the array. We divide the read error
  * count by 2 for every hour elapsed between read errors.
  */
 #define MD_DEFAULT_MAX_CORRECTED_READ_ERRORS 20
 /* Default safemode delay: 200 msec */
 #define DEFAULT_SAFEMODE_DELAY ((200 * HZ)/1000 +1)
 /*
  * Current RAID-1,4,5 parallel reconstruction 'guaranteed speed limit'
  * is 1000 KB/sec, so the extra system load does not show up that much.
  * Increase it if you want to have more _guaranteed_ speed. Note that
  * the RAID driver will use the maximum available bandwidth if the IO
  * subsystem is idle. There is also an 'absolute maximum' reconstruction
  * speed limit - in case reconstruction slows down your system despite
  * idle IO detection.
  *
  * you can change it via /proc/sys/dev/raid/speed_limit_min and _max.
  * or /sys/block/mdX/md/sync_speed_{min,max}
  */
 
 static int sysctl_speed_limit_min = 1000;
 static int sysctl_speed_limit_max = 200000;
 static inline int speed_min(struct mddev *mddev)
 {
     return mddev->sync_speed_min ?
         mddev->sync_speed_min : sysctl_speed_limit_min;
 }
 
 static inline int speed_max(struct mddev *mddev)
 {
     return mddev->sync_speed_max ?
         mddev->sync_speed_max : sysctl_speed_limit_max;
 }
 
 static void rdev_uninit_serial(struct md_rdev *rdev)
 {
     if (!test_and_clear_bit(CollisionCheck, &rdev->flags))
         return;
 
     kvfree(rdev->serial);
     rdev->serial = NULL;
 }
 
 static void rdevs_uninit_serial(struct mddev *mddev)
 {
     struct md_rdev *rdev;
 
     rdev_for_each(rdev, mddev)
         rdev_uninit_serial(rdev);
 }
 
 static int rdev_init_serial(struct md_rdev *rdev)
 {
     /* serial_nums equals with BARRIER_BUCKETS_NR */
     int i, serial_nums = 1 << ((PAGE_SHIFT - ilog2(sizeof(atomic_t))));
     struct serial_in_rdev *serial = NULL;
 
     if (test_bit(CollisionCheck, &rdev->flags))
         return 0;
 
     serial = kvmalloc(sizeof(struct serial_in_rdev) * serial_nums,
               GFP_KERNEL);
     if (!serial)
         return -ENOMEM;
 
     for (i = 0; i < serial_nums; i++) {
         struct serial_in_rdev *serial_tmp = &serial[i];
 
         spin_lock_init(&serial_tmp->serial_lock);
         serial_tmp->serial_rb = RB_ROOT_CACHED;
         init_waitqueue_head(&serial_tmp->serial_io_wait);
     }
 
     rdev->serial = serial;
     set_bit(CollisionCheck, &rdev->flags);
 
     return 0;
 }
 
 static int rdevs_init_serial(struct mddev *mddev)
 {
     struct md_rdev *rdev;
     int ret = 0;
 
     rdev_for_each(rdev, mddev) {
         ret = rdev_init_serial(rdev);
         if (ret)
             break;
     }
 
     /* Free all resources if pool is not existed */
     if (ret && !mddev->serial_info_pool)
         rdevs_uninit_serial(mddev);
 
     return ret;
 }
 
 /*
  * rdev needs to enable serial stuffs if it meets the conditions:
  * 1. it is multi-queue device flaged with writemostly.
  * 2. the write-behind mode is enabled.
  */
 static int rdev_need_serial(struct md_rdev *rdev)
 {
     return (rdev && rdev->mddev->bitmap_info.max_write_behind > 0 &&
         rdev->bdev->bd_disk->queue->nr_hw_queues != 1 &&
         test_bit(WriteMostly, &rdev->flags));
 }
 
 /*
  * Init resource for rdev(s), then create serial_info_pool if:
  * 1. rdev is the first device which return true from rdev_enable_serial.
  * 2. rdev is NULL, means we want to enable serialization for all rdevs.
  */
 void mddev_create_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
                   bool is_suspend)
 {
     int ret = 0;
 
     if (rdev && !rdev_need_serial(rdev) &&
         !test_bit(CollisionCheck, &rdev->flags))
         return;
 
     if (!is_suspend)
         mddev_suspend(mddev);
 
     if (!rdev)
         ret = rdevs_init_serial(mddev);
     else
         ret = rdev_init_serial(rdev);
     if (ret)
         goto abort;
 
     if (mddev->serial_info_pool == NULL) {
         /*
          * already in memalloc noio context by
          * mddev_suspend()
          */
         mddev->serial_info_pool =
             mempool_create_kmalloc_pool(NR_SERIAL_INFOS,
                         sizeof(struct serial_info));
         if (!mddev->serial_info_pool) {
             rdevs_uninit_serial(mddev);
             pr_err("can't alloc memory pool for serialization\n");
         }
     }
 
 abort:
     if (!is_suspend)
         mddev_resume(mddev);
 }
 
 /*
  * Free resource from rdev(s), and destroy serial_info_pool under conditions:
  * 1. rdev is the last device flaged with CollisionCheck.
  * 2. when bitmap is destroyed while policy is not enabled.
  * 3. for disable policy, the pool is destroyed only when no rdev needs it.
  */
 void mddev_destroy_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
                    bool is_suspend)
 {
     if (rdev && !test_bit(CollisionCheck, &rdev->flags))
         return;
 
     if (mddev->serial_info_pool) {
         struct md_rdev *temp;
         int num = 0; /* used to track if other rdevs need the pool */
 
         if (!is_suspend)
             mddev_suspend(mddev);
         rdev_for_each(temp, mddev) {
             if (!rdev) {
                 if (!mddev->serialize_policy ||
                     !rdev_need_serial(temp))
                     rdev_uninit_serial(temp);
                 else
                     num++;
             } else if (temp != rdev &&
                    test_bit(CollisionCheck, &temp->flags))
                 num++;
         }
 
         if (rdev)
             rdev_uninit_serial(rdev);
 
         if (num)
             pr_info("The mempool could be used by other devices\n");
         else {
             mempool_destroy(mddev->serial_info_pool);
             mddev->serial_info_pool = NULL;
         }
         if (!is_suspend)
             mddev_resume(mddev);
     }
 }
 
 static struct ctl_table_header *raid_table_header;
 
 static struct ctl_table raid_table[] = {
     {
         .procname   = "speed_limit_min",
         .data       = &sysctl_speed_limit_min,
         .maxlen     = sizeof(int),
         .mode       = S_IRUGO|S_IWUSR,
         .proc_handler   = proc_dointvec,
     },
     {
         .procname   = "speed_limit_max",
         .data       = &sysctl_speed_limit_max,
         .maxlen     = sizeof(int),
         .mode       = S_IRUGO|S_IWUSR,
         .proc_handler   = proc_dointvec,
     },
     { }
 };
 
 static struct ctl_table raid_dir_table[] = {
     {
         .procname   = "raid",
         .maxlen     = 0,
         .mode       = S_IRUGO|S_IXUGO,
         .child      = raid_table,
     },
     { }
 };
 
 static struct ctl_table raid_root_table[] = {
     {
         .procname   = "dev",
         .maxlen     = 0,
         .mode       = 0555,
         .child      = raid_dir_table,
     },
     {  }
 };
 
 static int start_readonly;
 
 /*
  * The original mechanism for creating an md device is to create
  * a device node in /dev and to open it.  This causes races with device-close.
  * The preferred method is to write to the "new_array" module parameter.
  * This can avoid races.
  * Setting create_on_open to false disables the original mechanism
  * so all the races disappear.
  */
 static bool create_on_open = true;
 
 /*
  * We have a system wide 'event count' that is incremented
  * on any 'interesting' event, and readers of /proc/mdstat
  * can use 'poll' or 'select' to find out when the event
  * count increases.
  *
  * Events are:
  *  start array, stop array, error, add device, remove device,
  *  start build, activate spare
  */
 static DECLARE_WAIT_QUEUE_HEAD(md_event_waiters);
 static atomic_t md_event_count;
 void md_new_event(void)
 {
     atomic_inc(&md_event_count);
     wake_up(&md_event_waiters);
 }
 EXPORT_SYMBOL_GPL(md_new_event);
 
 /*
  * Enables to iterate over all existing md arrays
  * all_mddevs_lock protects this list.
  */
 static LIST_HEAD(all_mddevs);
 static DEFINE_SPINLOCK(all_mddevs_lock);
 
 /* Rather than calling directly into the personality make_request function,
  * IO requests come here first so that we can check if the device is
  * being suspended pending a reconfiguration.
  * We hold a refcount over the call to ->make_request.  By the time that
  * call has finished, the bio has been linked into some internal structure
  * and so is visible to ->quiesce(), so we don't need the refcount any more.
  */
 static bool is_suspended(struct mddev *mddev, struct bio *bio)
 {
     if (mddev->suspended)
         return true;
     if (bio_data_dir(bio) != WRITE)
         return false;
     if (mddev->suspend_lo >= mddev->suspend_hi)
         return false;
     if (bio->bi_iter.bi_sector >= mddev->suspend_hi)
         return false;
     if (bio_end_sector(bio) < mddev->suspend_lo)
         return false;
     return true;
 }
 
 void md_handle_request(struct mddev *mddev, struct bio *bio)
 {
 check_suspended:
     rcu_read_lock();
     if (is_suspended(mddev, bio)) {
         DEFINE_WAIT(__wait);
         /* Bail out if REQ_NOWAIT is set for the bio */
         if (bio->bi_opf & REQ_NOWAIT) {
             rcu_read_unlock();
             bio_wouldblock_error(bio);
             return;
         }
         for (;;) {
             prepare_to_wait(&mddev->sb_wait, &__wait,
                     TASK_UNINTERRUPTIBLE);
             if (!is_suspended(mddev, bio))
                 break;
             rcu_read_unlock();
             schedule();
             rcu_read_lock();
         }
         finish_wait(&mddev->sb_wait, &__wait);
     }
     atomic_inc(&mddev->active_io);
     rcu_read_unlock();
 
     if (!mddev->pers->make_request(mddev, bio)) {
         atomic_dec(&mddev->active_io);
         wake_up(&mddev->sb_wait);
         goto check_suspended;
     }
 
     if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
         wake_up(&mddev->sb_wait);
 }
 EXPORT_SYMBOL(md_handle_request);
 
 static void md_submit_bio(struct bio *bio)
 {
     const int rw = bio_data_dir(bio);
     struct mddev *mddev = bio->bi_bdev->bd_disk->private_data;
 
     if (mddev == NULL || mddev->pers == NULL) {
         bio_io_error(bio);
         return;
     }
 
     if (unlikely(test_bit(MD_BROKEN, &mddev->flags)) && (rw == WRITE)) {
         bio_io_error(bio);
         return;
     }
 
     bio = bio_split_to_limits(bio);
 
     if (mddev->ro == 1 && unlikely(rw == WRITE)) {
         if (bio_sectors(bio) != 0)
             bio->bi_status = BLK_STS_IOERR;
         bio_endio(bio);
         return;
     }
 
     /* bio could be mergeable after passing to underlayer */
     bio->bi_opf &= ~REQ_NOMERGE;
 
     md_handle_request(mddev, bio);
 }
 
 /* mddev_suspend makes sure no new requests are submitted
  * to the device, and that any requests that have been submitted
  * are completely handled.
  * Once mddev_detach() is called and completes, the module will be
  * completely unused.
  */
 void mddev_suspend(struct mddev *mddev)
 {
     WARN_ON_ONCE(mddev->thread && current == mddev->thread->tsk);
     lockdep_assert_held(&mddev->reconfig_mutex);
     if (mddev->suspended++)
         return;
     synchronize_rcu();
     wake_up(&mddev->sb_wait);
     set_bit(MD_ALLOW_SB_UPDATE, &mddev->flags);
     smp_mb__after_atomic();
     wait_event(mddev->sb_wait, atomic_read(&mddev->active_io) == 0);
     mddev->pers->quiesce(mddev, 1);
     clear_bit_unlock(MD_ALLOW_SB_UPDATE, &mddev->flags);
     wait_event(mddev->sb_wait, !test_bit(MD_UPDATING_SB, &mddev->flags));
 
     del_timer_sync(&mddev->safemode_timer);
     /* restrict memory reclaim I/O during raid array is suspend */
     mddev->noio_flag = memalloc_noio_save();
 }
 EXPORT_SYMBOL_GPL(mddev_suspend);
 
 void mddev_resume(struct mddev *mddev)
 {
     /* entred the memalloc scope from mddev_suspend() */
     memalloc_noio_restore(mddev->noio_flag);
     lockdep_assert_held(&mddev->reconfig_mutex);
     if (--mddev->suspended)
         return;
     wake_up(&mddev->sb_wait);
     mddev->pers->quiesce(mddev, 0);
 
     set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
     md_wakeup_thread(mddev->thread);
     md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
 }
 EXPORT_SYMBOL_GPL(mddev_resume);
 
 /*
  * Generic flush handling for md
  */
 
 static void md_end_flush(struct bio *bio)
 {
     struct md_rdev *rdev = bio->bi_private;
     struct mddev *mddev = rdev->mddev;
 
     rdev_dec_pending(rdev, mddev);
 
     if (atomic_dec_and_test(&mddev->flush_pending)) {
         /* The pre-request flush has finished */
         queue_work(md_wq, &mddev->flush_work);
     }
     bio_put(bio);
 }
 
 static void md_submit_flush_data(struct work_struct *ws);
 
 static void submit_flushes(struct work_struct *ws)
 {
     struct mddev *mddev = container_of(ws, struct mddev, flush_work);
     struct md_rdev *rdev;
 
     mddev->start_flush = ktime_get_boottime();
     INIT_WORK(&mddev->flush_work, md_submit_flush_data);
     atomic_set(&mddev->flush_pending, 1);
     rcu_read_lock();
     rdev_for_each_rcu(rdev, mddev)
         if (rdev->raid_disk >= 0 &&
             !test_bit(Faulty, &rdev->flags)) {
             /* Take two references, one is dropped
              * when request finishes, one after
              * we reclaim rcu_read_lock
              */
             struct bio *bi;
             atomic_inc(&rdev->nr_pending);
             atomic_inc(&rdev->nr_pending);
             rcu_read_unlock();
             bi = bio_alloc_bioset(rdev->bdev, 0,
                           REQ_OP_WRITE | REQ_PREFLUSH,
                           GFP_NOIO, &mddev->bio_set);
             bi->bi_end_io = md_end_flush;
             bi->bi_private = rdev;
             atomic_inc(&mddev->flush_pending);
             submit_bio(bi);
             rcu_read_lock();
             rdev_dec_pending(rdev, mddev);
         }
     rcu_read_unlock();
     if (atomic_dec_and_test(&mddev->flush_pending))
         queue_work(md_wq, &mddev->flush_work);
 }
 
 static void md_submit_flush_data(struct work_struct *ws)
 {
     struct mddev *mddev = container_of(ws, struct mddev, flush_work);
     struct bio *bio = mddev->flush_bio;
 
     /*
      * must reset flush_bio before calling into md_handle_request to avoid a
      * deadlock, because other bios passed md_handle_request suspend check
      * could wait for this and below md_handle_request could wait for those
      * bios because of suspend check
      */
     spin_lock_irq(&mddev->lock);
     mddev->prev_flush_start = mddev->start_flush;
     mddev->flush_bio = NULL;
     spin_unlock_irq(&mddev->lock);
     wake_up(&mddev->sb_wait);
 
     if (bio->bi_iter.bi_size == 0) {
         /* an empty barrier - all done */
         bio_endio(bio);
     } else {
         bio->bi_opf &= ~REQ_PREFLUSH;
         md_handle_request(mddev, bio);
     }
 }
 
 /*
  * Manages consolidation of flushes and submitting any flushes needed for
  * a bio with REQ_PREFLUSH.  Returns true if the bio is finished or is
  * being finished in another context.  Returns false if the flushing is
  * complete but still needs the I/O portion of the bio to be processed.
  */
 bool md_flush_request(struct mddev *mddev, struct bio *bio)
 {
     ktime_t req_start = ktime_get_boottime();
     spin_lock_irq(&mddev->lock);
     /* flush requests wait until ongoing flush completes,
      * hence coalescing all the pending requests.
      */
     wait_event_lock_irq(mddev->sb_wait,
                 !mddev->flush_bio ||
                 ktime_before(req_start, mddev->prev_flush_start),
                 mddev->lock);
     /* new request after previous flush is completed */
     if (ktime_after(req_start, mddev->prev_flush_start)) {
         WARN_ON(mddev->flush_bio);
         mddev->flush_bio = bio;
         bio = NULL;
     }
     spin_unlock_irq(&mddev->lock);
 
     if (!bio) {
         INIT_WORK(&mddev->flush_work, submit_flushes);
         queue_work(md_wq, &mddev->flush_work);
     } else {
         /* flush was performed for some other bio while we waited. */
         if (bio->bi_iter.bi_size == 0)
             /* an empty barrier - all done */
             bio_endio(bio);
         else {
             bio->bi_opf &= ~REQ_PREFLUSH;
             return false;
         }
     }
     return true;
 }
 EXPORT_SYMBOL(md_flush_request);
 
 static inline struct mddev *mddev_get(struct mddev *mddev)
 {
     lockdep_assert_held(&all_mddevs_lock);
 
     if (test_bit(MD_DELETED, &mddev->flags))
         return NULL;
     atomic_inc(&mddev->active);
     return mddev;
 }
 
 static void mddev_delayed_delete(struct work_struct *ws);
 
 void mddev_put(struct mddev *mddev)
 {
     if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
         return;
     if (!mddev->raid_disks && list_empty(&mddev->disks) &&
         mddev->ctime == 0 && !mddev->hold_active) {
         /* Array is not configured at all, and not held active,
          * so destroy it */
         set_bit(MD_DELETED, &mddev->flags);
 
         /*
          * Call queue_work inside the spinlock so that
          * flush_workqueue() after mddev_find will succeed in waiting
          * for the work to be done.
          */
         INIT_WORK(&mddev->del_work, mddev_delayed_delete);
         queue_work(md_misc_wq, &mddev->del_work);
     }
     spin_unlock(&all_mddevs_lock);
 }
 
 static void md_safemode_timeout(struct timer_list *t);
 
 void mddev_init(struct mddev *mddev)
 {
     mutex_init(&mddev->open_mutex);
     mutex_init(&mddev->reconfig_mutex);
     mutex_init(&mddev->bitmap_info.mutex);
     INIT_LIST_HEAD(&mddev->disks);
     INIT_LIST_HEAD(&mddev->all_mddevs);
     timer_setup(&mddev->safemode_timer, md_safemode_timeout, 0);
     atomic_set(&mddev->active, 1);
     atomic_set(&mddev->openers, 0);
     atomic_set(&mddev->active_io, 0);
     spin_lock_init(&mddev->lock);
     atomic_set(&mddev->flush_pending, 0);
     init_waitqueue_head(&mddev->sb_wait);
     init_waitqueue_head(&mddev->recovery_wait);
     mddev->reshape_position = MaxSector;
     mddev->reshape_backwards = 0;
     mddev->last_sync_action = "none";
     mddev->resync_min = 0;
     mddev->resync_max = MaxSector;
     mddev->level = LEVEL_NONE;
 }
 EXPORT_SYMBOL_GPL(mddev_init);
 
 static struct mddev *mddev_find_locked(dev_t unit)
 {
     struct mddev *mddev;
 
     list_for_each_entry(mddev, &all_mddevs, all_mddevs)
         if (mddev->unit == unit)
             return mddev;
 
     return NULL;
 }
 
 /* find an unused unit number */
 static dev_t mddev_alloc_unit(void)
 {
     static int next_minor = 512;
     int start = next_minor;
     bool is_free = 0;
     dev_t dev = 0;
 
     while (!is_free) {
         dev = MKDEV(MD_MAJOR, next_minor);
         next_minor++;
         if (next_minor > MINORMASK)
             next_minor = 0;
         if (next_minor == start)
             return 0;       /* Oh dear, all in use. */
         is_free = !mddev_find_locked(dev);
     }
 
     return dev;
 }
 
 static struct mddev *mddev_alloc(dev_t unit)
 {
     struct mddev *new;
     int error;
 
     if (unit && MAJOR(unit) != MD_MAJOR)
         unit &= ~((1 << MdpMinorShift) - 1);
 
     new = kzalloc(sizeof(*new), GFP_KERNEL);
     if (!new)
         return ERR_PTR(-ENOMEM);
     mddev_init(new);
 
     spin_lock(&all_mddevs_lock);
     if (unit) {
         error = -EEXIST;
         if (mddev_find_locked(unit))
             goto out_free_new;
         new->unit = unit;
         if (MAJOR(unit) == MD_MAJOR)
             new->md_minor = MINOR(unit);
         else
             new->md_minor = MINOR(unit) >> MdpMinorShift;
         new->hold_active = UNTIL_IOCTL;
     } else {
         error = -ENODEV;
         new->unit = mddev_alloc_unit();
         if (!new->unit)
             goto out_free_new;
         new->md_minor = MINOR(new->unit);
         new->hold_active = UNTIL_STOP;
     }
 
     list_add(&new->all_mddevs, &all_mddevs);
     spin_unlock(&all_mddevs_lock);
     return new;
 out_free_new:
     spin_unlock(&all_mddevs_lock);
     kfree(new);
     return ERR_PTR(error);
 }
 
 static void mddev_free(struct mddev *mddev)
 {
     spin_lock(&all_mddevs_lock);
     list_del(&mddev->all_mddevs);
     spin_unlock(&all_mddevs_lock);
 
     kfree(mddev);
 }
 
 static const struct attribute_group md_redundancy_group;
 
 void mddev_unlock(struct mddev *mddev)
 {
     if (mddev->to_remove) {
         /* These cannot be removed under reconfig_mutex as
          * an access to the files will try to take reconfig_mutex
          * while holding the file unremovable, which leads to
          * a deadlock.
          * So hold set sysfs_active while the remove in happeing,
          * and anything else which might set ->to_remove or my
          * otherwise change the sysfs namespace will fail with
          * -EBUSY if sysfs_active is still set.
          * We set sysfs_active under reconfig_mutex and elsewhere
          * test it under the same mutex to ensure its correct value
          * is seen.
          */
         const struct attribute_group *to_remove = mddev->to_remove;
         mddev->to_remove = NULL;
         mddev->sysfs_active = 1;
         mutex_unlock(&mddev->reconfig_mutex);
 
         if (mddev->kobj.sd) {
             if (to_remove != &md_redundancy_group)
                 sysfs_remove_group(&mddev->kobj, to_remove);
             if (mddev->pers == NULL ||
                 mddev->pers->sync_request == NULL) {
                 sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
                 if (mddev->sysfs_action)
                     sysfs_put(mddev->sysfs_action);
                 if (mddev->sysfs_completed)
                     sysfs_put(mddev->sysfs_completed);
                 if (mddev->sysfs_degraded)
                     sysfs_put(mddev->sysfs_degraded);
                 mddev->sysfs_action = NULL;
                 mddev->sysfs_completed = NULL;
                 mddev->sysfs_degraded = NULL;
             }
         }
         mddev->sysfs_active = 0;
     } else
         mutex_unlock(&mddev->reconfig_mutex);
 
     /* As we've dropped the mutex we need a spinlock to
      * make sure the thread doesn't disappear
      */
     spin_lock(&pers_lock);
     md_wakeup_thread(mddev->thread);
     wake_up(&mddev->sb_wait);
     spin_unlock(&pers_lock);
 }
 EXPORT_SYMBOL_GPL(mddev_unlock);
 
 struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr)
 {
     struct md_rdev *rdev;
 
     rdev_for_each_rcu(rdev, mddev)
         if (rdev->desc_nr == nr)
             return rdev;
 
     return NULL;
 }
 EXPORT_SYMBOL_GPL(md_find_rdev_nr_rcu);
 
 static struct md_rdev *find_rdev(struct mddev *mddev, dev_t dev)
 {
     struct md_rdev *rdev;
 
     rdev_for_each(rdev, mddev)
         if (rdev->bdev->bd_dev == dev)
             return rdev;
 
     return NULL;
 }
 
 struct md_rdev *md_find_rdev_rcu(struct mddev *mddev, dev_t dev)
 {
     struct md_rdev *rdev;
 
     rdev_for_each_rcu(rdev, mddev)
         if (rdev->bdev->bd_dev == dev)
             return rdev;
 
     return NULL;
 }
 EXPORT_SYMBOL_GPL(md_find_rdev_rcu);
 
 static struct md_personality *find_pers(int level, char *clevel)
 {
     struct md_personality *pers;
     list_for_each_entry(pers, &pers_list, list) {
         if (level != LEVEL_NONE && pers->level == level)
             return pers;
         if (strcmp(pers->name, clevel)==0)
             return pers;
     }
     return NULL;
 }
 
 /* return the offset of the super block in 512byte sectors */
 static inline sector_t calc_dev_sboffset(struct md_rdev *rdev)
 {
     return MD_NEW_SIZE_SECTORS(bdev_nr_sectors(rdev->bdev));
 }
 
 static int alloc_disk_sb(struct md_rdev *rdev)
 {
     rdev->sb_page = alloc_page(GFP_KERNEL);
     if (!rdev->sb_page)
         return -ENOMEM;
     return 0;
 }
 
 void md_rdev_clear(struct md_rdev *rdev)
 {
     if (rdev->sb_page) {
         put_page(rdev->sb_page);
         rdev->sb_loaded = 0;
         rdev->sb_page = NULL;
         rdev->sb_start = 0;
         rdev->sectors = 0;
     }
     if (rdev->bb_page) {
         put_page(rdev->bb_page);
         rdev->bb_page = NULL;
     }
     badblocks_exit(&rdev->badblocks);
 }
 EXPORT_SYMBOL_GPL(md_rdev_clear);
 
 static void super_written(struct bio *bio)
 {
     struct md_rdev *rdev = bio->bi_private;
     struct mddev *mddev = rdev->mddev;
 
     if (bio->bi_status) {
         pr_err("md: %s gets error=%d\n", __func__,
                blk_status_to_errno(bio->bi_status));
         md_error(mddev, rdev);
         if (!test_bit(Faulty, &rdev->flags)
             && (bio->bi_opf & MD_FAILFAST)) {
             set_bit(MD_SB_NEED_REWRITE, &mddev->sb_flags);
             set_bit(LastDev, &rdev->flags);
         }
     } else
         clear_bit(LastDev, &rdev->flags);
 
     if (atomic_dec_and_test(&mddev->pending_writes))
         wake_up(&mddev->sb_wait);
     rdev_dec_pending(rdev, mddev);
     bio_put(bio);
 }
 
 void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
            sector_t sector, int size, struct page *page)
 {
     /* write first size bytes of page to sector of rdev
      * Increment mddev->pending_writes before returning
      * and decrement it on completion, waking up sb_wait
      * if zero is reached.
      * If an error occurred, call md_error
      */
     struct bio *bio;
 
     if (!page)
         return;
 
     if (test_bit(Faulty, &rdev->flags))
         return;
 
     bio = bio_alloc_bioset(rdev->meta_bdev ? rdev->meta_bdev : rdev->bdev,
                    1,
                    REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH | REQ_FUA,
                    GFP_NOIO, &mddev->sync_set);
 
     atomic_inc(&rdev->nr_pending);
 
     bio->bi_iter.bi_sector = sector;
     bio_add_page(bio, page, size, 0);
     bio->bi_private = rdev;
     bio->bi_end_io = super_written;
 
     if (test_bit(MD_FAILFAST_SUPPORTED, &mddev->flags) &&
         test_bit(FailFast, &rdev->flags) &&
         !test_bit(LastDev, &rdev->flags))
         bio->bi_opf |= MD_FAILFAST;
 
     atomic_inc(&mddev->pending_writes);
     submit_bio(bio);
 }
 
 int md_super_wait(struct mddev *mddev)
 {
     /* wait for all superblock writes that were scheduled to complete */
     wait_event(mddev->sb_wait, atomic_read(&mddev->pending_writes)==0);
     if (test_and_clear_bit(MD_SB_NEED_REWRITE, &mddev->sb_flags))
         return -EAGAIN;
     return 0;
 }
 
 int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
          struct page *page, blk_opf_t opf, bool metadata_op)
 {
     struct bio bio;
     struct bio_vec bvec;
 
     if (metadata_op && rdev->meta_bdev)
         bio_init(&bio, rdev->meta_bdev, &bvec, 1, opf);
     else
         bio_init(&bio, rdev->bdev, &bvec, 1, opf);
 
     if (metadata_op)
         bio.bi_iter.bi_sector = sector + rdev->sb_start;
     else if (rdev->mddev->reshape_position != MaxSector &&
          (rdev->mddev->reshape_backwards ==
           (sector >= rdev->mddev->reshape_position)))
         bio.bi_iter.bi_sector = sector + rdev->new_data_offset;
     else
         bio.bi_iter.bi_sector = sector + rdev->data_offset;
     bio_add_page(&bio, page, size, 0);
 
     submit_bio_wait(&bio);
 
     return !bio.bi_status;
 }
 EXPORT_SYMBOL_GPL(sync_page_io);
 
 static int read_disk_sb(struct md_rdev *rdev, int size)
 {
     if (rdev->sb_loaded)
         return 0;
 
     if (!sync_page_io(rdev, 0, size, rdev->sb_page, REQ_OP_READ, true))
         goto fail;
     rdev->sb_loaded = 1;
     return 0;
 
 fail:
     pr_err("md: disabled device %pg, could not read superblock.\n",
            rdev->bdev);
     return -EINVAL;
 }
 
 static int md_uuid_equal(mdp_super_t *sb1, mdp_super_t *sb2)
 {
     return  sb1->set_uuid0 == sb2->set_uuid0 &&
         sb1->set_uuid1 == sb2->set_uuid1 &&
         sb1->set_uuid2 == sb2->set_uuid2 &&
         sb1->set_uuid3 == sb2->set_uuid3;
 }
 
 static int md_sb_equal(mdp_super_t *sb1, mdp_super_t *sb2)
 {
     int ret;
     mdp_super_t *tmp1, *tmp2;
 
     tmp1 = kmalloc(sizeof(*tmp1),GFP_KERNEL);
     tmp2 = kmalloc(sizeof(*tmp2),GFP_KERNEL);
 
     if (!tmp1 || !tmp2) {
         ret = 0;
         goto abort;
     }
 
     *tmp1 = *sb1;
     *tmp2 = *sb2;
 
     /*
      * nr_disks is not constant
      */
     tmp1->nr_disks = 0;
     tmp2->nr_disks = 0;
 
     ret = (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4) == 0);
 abort:
     kfree(tmp1);
     kfree(tmp2);
     return ret;
 }
 
 static u32 md_csum_fold(u32 csum)
 {
     csum = (csum & 0xffff) + (csum >> 16);
     return (csum & 0xffff) + (csum >> 16);
 }
 
 static unsigned int calc_sb_csum(mdp_super_t *sb)
 {
     u64 newcsum = 0;
     u32 *sb32 = (u32*)sb;
     int i;
     unsigned int disk_csum, csum;
 
     disk_csum = sb->sb_csum;
     sb->sb_csum = 0;
 
     for (i = 0; i < MD_SB_BYTES/4 ; i++)
         newcsum += sb32[i];
     csum = (newcsum & 0xffffffff) + (newcsum>>32);
 
 #ifdef CONFIG_ALPHA
     /* This used to use csum_partial, which was wrong for several
      * reasons including that different results are returned on
      * different architectures.  It isn't critical that we get exactly
      * the same return value as before (we always csum_fold before
      * testing, and that removes any differences).  However as we
      * know that csum_partial always returned a 16bit value on
      * alphas, do a fold to maximise conformity to previous behaviour.
      */
     sb->sb_csum = md_csum_fold(disk_csum);
 #else
     sb->sb_csum = disk_csum;
 #endif
     return csum;
 }
 
 /*
  * Handle superblock details.
  * We want to be able to handle multiple superblock formats
  * so we have a common interface to them all, and an array of
  * different handlers.
  * We rely on user-space to write the initial superblock, and support
  * reading and updating of superblocks.
  * Interface methods are:
  *   int load_super(struct md_rdev *dev, struct md_rdev *refdev, int minor_version)
  *      loads and validates a superblock on dev.
  *      if refdev != NULL, compare superblocks on both devices
  *    Return:
  *      0 - dev has a superblock that is compatible with refdev
  *      1 - dev has a superblock that is compatible and newer than refdev
  *          so dev should be used as the refdev in future
  *     -EINVAL superblock incompatible or invalid
  *     -othererror e.g. -EIO
  *
  *   int validate_super(struct mddev *mddev, struct md_rdev *dev)
  *      Verify that dev is acceptable into mddev.
  *       The first time, mddev->raid_disks will be 0, and data from
  *       dev should be merged in.  Subsequent calls check that dev
  *       is new enough.  Return 0 or -EINVAL
  *
  *   void sync_super(struct mddev *mddev, struct md_rdev *dev)
  *     Update the superblock for rdev with data in mddev
  *     This does not write to disc.
  *
  */
 
 struct super_type  {
     char            *name;
     struct module       *owner;
     int         (*load_super)(struct md_rdev *rdev,
                       struct md_rdev *refdev,
                       int minor_version);
     int         (*validate_super)(struct mddev *mddev,
                           struct md_rdev *rdev);
     void            (*sync_super)(struct mddev *mddev,
                       struct md_rdev *rdev);
     unsigned long long  (*rdev_size_change)(struct md_rdev *rdev,
                         sector_t num_sectors);
     int         (*allow_new_offset)(struct md_rdev *rdev,
                         unsigned long long new_offset);
 };
 
 /*
  * Check that the given mddev has no bitmap.
  *
  * This function is called from the run method of all personalities that do not
  * support bitmaps. It prints an error message and returns non-zero if mddev
  * has a bitmap. Otherwise, it returns 0.
  *
  */
 int md_check_no_bitmap(struct mddev *mddev)
 {
     if (!mddev->bitmap_info.file && !mddev->bitmap_info.offset)
         return 0;
     pr_warn("%s: bitmaps are not supported for %s\n",
         mdname(mddev), mddev->pers->name);
     return 1;
 }
 EXPORT_SYMBOL(md_check_no_bitmap);
 
 /*
  * load_super for 0.90.0
  */
 static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
 {
     mdp_super_t *sb;
     int ret;
     bool spare_disk = true;
 
     /*
      * Calculate the position of the superblock (512byte sectors),
      * it's at the end of the disk.
      *
      * It also happens to be a multiple of 4Kb.
      */
     rdev->sb_start = calc_dev_sboffset(rdev);
 
     ret = read_disk_sb(rdev, MD_SB_BYTES);
     if (ret)
         return ret;
 
     ret = -EINVAL;
 
     sb = page_address(rdev->sb_page);
 
     if (sb->md_magic != MD_SB_MAGIC) {
         pr_warn("md: invalid raid superblock magic on %pg\n",
             rdev->bdev);
         goto abort;
     }
 
     if (sb->major_version != 0 ||
         sb->minor_version < 90 ||
         sb->minor_version > 91) {
         pr_warn("Bad version number %d.%d on %pg\n",
             sb->major_version, sb->minor_version, rdev->bdev);
         goto abort;
     }
 
     if (sb->raid_disks <= 0)
         goto abort;
 
     if (md_csum_fold(calc_sb_csum(sb)) != md_csum_fold(sb->sb_csum)) {
         pr_warn("md: invalid superblock checksum on %pg\n", rdev->bdev);
         goto abort;
     }
 
     rdev->preferred_minor = sb->md_minor;
     rdev->data_offset = 0;
     rdev->new_data_offset = 0;
     rdev->sb_size = MD_SB_BYTES;
     rdev->badblocks.shift = -1;
 
     if (sb->level == LEVEL_MULTIPATH)
         rdev->desc_nr = -1;
     else
         rdev->desc_nr = sb->this_disk.number;
 
     /* not spare disk, or LEVEL_MULTIPATH */
     if (sb->level == LEVEL_MULTIPATH ||
         (rdev->desc_nr >= 0 &&
          rdev->desc_nr < MD_SB_DISKS &&
          sb->disks[rdev->desc_nr].state &
          ((1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE))))
         spare_disk = false;
 
     if (!refdev) {
         if (!spare_disk)
             ret = 1;
         else
             ret = 0;
     } else {
         __u64 ev1, ev2;
         mdp_super_t *refsb = page_address(refdev->sb_page);
         if (!md_uuid_equal(refsb, sb)) {
             pr_warn("md: %pg has different UUID to %pg\n",
                 rdev->bdev, refdev->bdev);
             goto abort;
         }
         if (!md_sb_equal(refsb, sb)) {
             pr_warn("md: %pg has same UUID but different superblock to %pg\n",
                 rdev->bdev, refdev->bdev);
             goto abort;
         }
         ev1 = md_event(sb);
         ev2 = md_event(refsb);
 
         if (!spare_disk && ev1 > ev2)
             ret = 1;
         else
             ret = 0;
     }
     rdev->sectors = rdev->sb_start;
     /* Limit to 4TB as metadata cannot record more than that.
      * (not needed for Linear and RAID0 as metadata doesn't
      * record this size)
      */
     if ((u64)rdev->sectors >= (2ULL << 32) && sb->level >= 1)
         rdev->sectors = (sector_t)(2ULL << 32) - 2;
 
     if (rdev->sectors < ((sector_t)sb->size) * 2 && sb->level >= 1)
         /* "this cannot possibly happen" ... */
         ret = -EINVAL;
 
  abort:
     return ret;
 }
 
 /*
  * validate_super for 0.90.0
  */
 static int super_90_validate(struct mddev *mddev, struct md_rdev *rdev)
 {
     mdp_disk_t *desc;
     mdp_super_t *sb = page_address(rdev->sb_page);
     __u64 ev1 = md_event(sb);
 
     rdev->raid_disk = -1;
     clear_bit(Faulty, &rdev->flags);
     clear_bit(In_sync, &rdev->flags);
     clear_bit(Bitmap_sync, &rdev->flags);
     clear_bit(WriteMostly, &rdev->flags);
 
     if (mddev->raid_disks == 0) {
         mddev->major_version = 0;
         mddev->minor_version = sb->minor_version;
         mddev->patch_version = sb->patch_version;
         mddev->external = 0;
         mddev->chunk_sectors = sb->chunk_size >> 9;
         mddev->ctime = sb->ctime;
         mddev->utime = sb->utime;
         mddev->level = sb->level;
         mddev->clevel[0] = 0;
         mddev->layout = sb->layout;
         mddev->raid_disks = sb->raid_disks;
         mddev->dev_sectors = ((sector_t)sb->size) * 2;
         mddev->events = ev1;
         mddev->bitmap_info.offset = 0;
         mddev->bitmap_info.space = 0;
         /* bitmap can use 60 K after the 4K superblocks */
         mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
         mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
         mddev->reshape_backwards = 0;
 
         if (mddev->minor_version >= 91) {
             mddev->reshape_position = sb->reshape_position;
             mddev->delta_disks = sb->delta_disks;
             mddev->new_level = sb->new_level;
             mddev->new_layout = sb->new_layout;
             mddev->new_chunk_sectors = sb->new_chunk >> 9;
             if (mddev->delta_disks < 0)
                 mddev->reshape_backwards = 1;
         } else {
             mddev->reshape_position = MaxSector;
             mddev->delta_disks = 0;
             mddev->new_level = mddev->level;
             mddev->new_layout = mddev->layout;
             mddev->new_chunk_sectors = mddev->chunk_sectors;
         }
         if (mddev->level == 0)
             mddev->layout = -1;
 
         if (sb->state & (1<<MD_SB_CLEAN))
             mddev->recovery_cp = MaxSector;
         else {
             if (sb->events_hi == sb->cp_events_hi &&
                 sb->events_lo == sb->cp_events_lo) {
                 mddev->recovery_cp = sb->recovery_cp;
             } else
                 mddev->recovery_cp = 0;
         }
 
         memcpy(mddev->uuid+0, &sb->set_uuid0, 4);
         memcpy(mddev->uuid+4, &sb->set_uuid1, 4);
         memcpy(mddev->uuid+8, &sb->set_uuid2, 4);
         memcpy(mddev->uuid+12,&sb->set_uuid3, 4);
 
         mddev->max_disks = MD_SB_DISKS;
 
         if (sb->state & (1<<MD_SB_BITMAP_PRESENT) &&
             mddev->bitmap_info.file == NULL) {
             mddev->bitmap_info.offset =
                 mddev->bitmap_info.default_offset;
             mddev->bitmap_info.space =
                 mddev->bitmap_info.default_space;
         }
 
     } else if (mddev->pers == NULL) {
         /* Insist on good event counter while assembling, except
          * for spares (which don't need an event count) */
         ++ev1;
         if (sb->disks[rdev->desc_nr].state & (
                 (1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)))
             if (ev1 < mddev->events)
                 return -EINVAL;
     } else if (mddev->bitmap) {
         /* if adding to array with a bitmap, then we can accept an
          * older device ... but not too old.
          */
         if (ev1 < mddev->bitmap->events_cleared)
             return 0;
         if (ev1 < mddev->events)
             set_bit(Bitmap_sync, &rdev->flags);
     } else {
         if (ev1 < mddev->events)
             /* just a hot-add of a new device, leave raid_disk at -1 */
             return 0;
     }
 
     if (mddev->level != LEVEL_MULTIPATH) {
         desc = sb->disks + rdev->desc_nr;
 
         if (desc->state & (1<<MD_DISK_FAULTY))
             set_bit(Faulty, &rdev->flags);
         else if (desc->state & (1<<MD_DISK_SYNC) /* &&
                 desc->raid_disk < mddev->raid_disks */) {
             set_bit(In_sync, &rdev->flags);
             rdev->raid_disk = desc->raid_disk;
             rdev->saved_raid_disk = desc->raid_disk;
         } else if (desc->state & (1<<MD_DISK_ACTIVE)) {
             /* active but not in sync implies recovery up to
              * reshape position.  We don't know exactly where
              * that is, so set to zero for now */
             if (mddev->minor_version >= 91) {
                 rdev->recovery_offset = 0;
                 rdev->raid_disk = desc->raid_disk;
             }
         }
         if (desc->state & (1<<MD_DISK_WRITEMOSTLY))
             set_bit(WriteMostly, &rdev->flags);
         if (desc->state & (1<<MD_DISK_FAILFAST))
             set_bit(FailFast, &rdev->flags);
     } else /* MULTIPATH are always insync */
         set_bit(In_sync, &rdev->flags);
     return 0;
 }
 
 /*
  * sync_super for 0.90.0
  */
 static void super_90_sync(struct mddev *mddev, struct md_rdev *rdev)
 {
     mdp_super_t *sb;
     struct md_rdev *rdev2;
     int next_spare = mddev->raid_disks;
 
     /* make rdev->sb match mddev data..
      *
      * 1/ zero out disks
      * 2/ Add info for each disk, keeping track of highest desc_nr (next_spare);
      * 3/ any empty disks < next_spare become removed
      *
      * disks[0] gets initialised to REMOVED because
      * we cannot be sure from other fields if it has
      * been initialised or not.
      */
     int i;
     int active=0, working=0,failed=0,spare=0,nr_disks=0;
 
     rdev->sb_size = MD_SB_BYTES;
 
     sb = page_address(rdev->sb_page);
 
     memset(sb, 0, sizeof(*sb));
 
     sb->md_magic = MD_SB_MAGIC;
     sb->major_version = mddev->major_version;
     sb->patch_version = mddev->patch_version;
     sb->gvalid_words  = 0; /* ignored */
     memcpy(&sb->set_uuid0, mddev->uuid+0, 4);
     memcpy(&sb->set_uuid1, mddev->uuid+4, 4);
     memcpy(&sb->set_uuid2, mddev->uuid+8, 4);
     memcpy(&sb->set_uuid3, mddev->uuid+12,4);
 
     sb->ctime = clamp_t(time64_t, mddev->ctime, 0, U32_MAX);
     sb->level = mddev->level;
     sb->size = mddev->dev_sectors / 2;
     sb->raid_disks = mddev->raid_disks;
     sb->md_minor = mddev->md_minor;
     sb->not_persistent = 0;
     sb->utime = clamp_t(time64_t, mddev->utime, 0, U32_MAX);
     sb->state = 0;
     sb->events_hi = (mddev->events>>32);
     sb->events_lo = (u32)mddev->events;
 
     if (mddev->reshape_position == MaxSector)
         sb->minor_version = 90;
     else {
         sb->minor_version = 91;
         sb->reshape_position = mddev->reshape_position;
         sb->new_level = mddev->new_level;
         sb->delta_disks = mddev->delta_disks;
         sb->new_layout = mddev->new_layout;
         sb->new_chunk = mddev->new_chunk_sectors << 9;
     }
     mddev->minor_version = sb->minor_version;
     if (mddev->in_sync)
     {
         sb->recovery_cp = mddev->recovery_cp;
         sb->cp_events_hi = (mddev->events>>32);
         sb->cp_events_lo = (u32)mddev->events;
         if (mddev->recovery_cp == MaxSector)
             sb->state = (1<< MD_SB_CLEAN);
     } else
         sb->recovery_cp = 0;
 
     sb->layout = mddev->layout;
     sb->chunk_size = mddev->chunk_sectors << 9;
 
     if (mddev->bitmap && mddev->bitmap_info.file == NULL)
         sb->state |= (1<<MD_SB_BITMAP_PRESENT);
 
     sb->disks[0].state = (1<<MD_DISK_REMOVED);
     rdev_for_each(rdev2, mddev) {
         mdp_disk_t *d;
         int desc_nr;
         int is_active = test_bit(In_sync, &rdev2->flags);
 
         if (rdev2->raid_disk >= 0 &&
             sb->minor_version >= 91)
             /* we have nowhere to store the recovery_offset,
              * but if it is not below the reshape_position,
              * we can piggy-back on that.
              */
             is_active = 1;
         if (rdev2->raid_disk < 0 ||
             test_bit(Faulty, &rdev2->flags))
             is_active = 0;
         if (is_active)
             desc_nr = rdev2->raid_disk;
         else
             desc_nr = next_spare++;
         rdev2->desc_nr = desc_nr;
         d = &sb->disks[rdev2->desc_nr];
         nr_disks++;
         d->number = rdev2->desc_nr;
         d->major = MAJOR(rdev2->bdev->bd_dev);
         d->minor = MINOR(rdev2->bdev->bd_dev);
         if (is_active)
             d->raid_disk = rdev2->raid_disk;
         else
             d->raid_disk = rdev2->desc_nr; /* compatibility */
         if (test_bit(Faulty, &rdev2->flags))
             d->state = (1<<MD_DISK_FAULTY);
         else if (is_active) {
             d->state = (1<<MD_DISK_ACTIVE);
             if (test_bit(In_sync, &rdev2->flags))
                 d->state |= (1<<MD_DISK_SYNC);
             active++;
             working++;
         } else {
             d->state = 0;
             spare++;
             working++;
         }
         if (test_bit(WriteMostly, &rdev2->flags))
             d->state |= (1<<MD_DISK_WRITEMOSTLY);
         if (test_bit(FailFast, &rdev2->flags))
             d->state |= (1<<MD_DISK_FAILFAST);
     }
     /* now set the "removed" and "faulty" bits on any missing devices */
     for (i=0 ; i < mddev->raid_disks ; i++) {
         mdp_disk_t *d = &sb->disks[i];
         if (d->state == 0 && d->number == 0) {
             d->number = i;
             d->raid_disk = i;
             d->state = (1<<MD_DISK_REMOVED);
             d->state |= (1<<MD_DISK_FAULTY);
             failed++;
         }
     }
     sb->nr_disks = nr_disks;
     sb->active_disks = active;
     sb->working_disks = working;
     sb->failed_disks = failed;
     sb->spare_disks = spare;
 
     sb->this_disk = sb->disks[rdev->desc_nr];
     sb->sb_csum = calc_sb_csum(sb);
 }
 
 /*
  * rdev_size_change for 0.90.0
  */
 static unsigned long long
 super_90_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
 {
     if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
         return 0; /* component must fit device */
     if (rdev->mddev->bitmap_info.offset)
         return 0; /* can't move bitmap */
     rdev->sb_start = calc_dev_sboffset(rdev);
     if (!num_sectors || num_sectors > rdev->sb_start)
         num_sectors = rdev->sb_start;
     /* Limit to 4TB as metadata cannot record more than that.
      * 4TB == 2^32 KB, or 2*2^32 sectors.
      */
     if ((u64)num_sectors >= (2ULL << 32) && rdev->mddev->level >= 1)
         num_sectors = (sector_t)(2ULL << 32) - 2;
     do {
         md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
                rdev->sb_page);
     } while (md_super_wait(rdev->mddev) < 0);
     return num_sectors;
 }
 
 static int
 super_90_allow_new_offset(struct md_rdev *rdev, unsigned long long new_offset)
 {
     /* non-zero offset changes not possible with v0.90 */
     return new_offset == 0;
 }
 
 /*
  * version 1 superblock
  */
 
 static __le32 calc_sb_1_csum(struct mdp_superblock_1 *sb)
 {
     __le32 disk_csum;
     u32 csum;
     unsigned long long newcsum;
     int size = 256 + le32_to_cpu(sb->max_dev)*2;
     __le32 *isuper = (__le32*)sb;
 
     disk_csum = sb->sb_csum;
     sb->sb_csum = 0;
     newcsum = 0;
     for (; size >= 4; size -= 4)
         newcsum += le32_to_cpu(*isuper++);
 
     if (size == 2)
         newcsum += le16_to_cpu(*(__le16*) isuper);
 
     csum = (newcsum & 0xffffffff) + (newcsum >> 32);
     sb->sb_csum = disk_csum;
     return cpu_to_le32(csum);
 }
 
 static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
 {
     struct mdp_superblock_1 *sb;
     int ret;
     sector_t sb_start;
     sector_t sectors;
     int bmask;
     bool spare_disk = true;
 
     /*
      * Calculate the position of the superblock in 512byte sectors.
      * It is always aligned to a 4K boundary and
      * depeding on minor_version, it can be:
      * 0: At least 8K, but less than 12K, from end of device
      * 1: At start of device
      * 2: 4K from start of device.
      */
     switch(minor_version) {
     case 0:
         sb_start = bdev_nr_sectors(rdev->bdev) - 8 * 2;
         sb_start &= ~(sector_t)(4*2-1);
         break;
     case 1:
         sb_start = 0;
         break;
     case 2:
         sb_start = 8;
         break;
     default:
         return -EINVAL;
     }
     rdev->sb_start = sb_start;
 
     /* superblock is rarely larger than 1K, but it can be larger,
      * and it is safe to read 4k, so we do that
      */
     ret = read_disk_sb(rdev, 4096);
     if (ret) return ret;
 
     sb = page_address(rdev->sb_page);
 
     if (sb->magic != cpu_to_le32(MD_SB_MAGIC) ||
         sb->major_version != cpu_to_le32(1) ||
         le32_to_cpu(sb->max_dev) > (4096-256)/2 ||
         le64_to_cpu(sb->super_offset) != rdev->sb_start ||
         (le32_to_cpu(sb->feature_map) & ~MD_FEATURE_ALL) != 0)
         return -EINVAL;
 
     if (calc_sb_1_csum(sb) != sb->sb_csum) {
         pr_warn("md: invalid superblock checksum on %pg\n",
             rdev->bdev);
         return -EINVAL;
     }
     if (le64_to_cpu(sb->data_size) < 10) {
         pr_warn("md: data_size too small on %pg\n",
             rdev->bdev);
         return -EINVAL;
     }
     if (sb->pad0 ||
         sb->pad3[0] ||
         memcmp(sb->pad3, sb->pad3+1, sizeof(sb->pad3) - sizeof(sb->pad3[1])))
         /* Some padding is non-zero, might be a new feature */
         return -EINVAL;
 
     rdev->preferred_minor = 0xffff;
     rdev->data_offset = le64_to_cpu(sb->data_offset);
     rdev->new_data_offset = rdev->data_offset;
     if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE) &&
         (le32_to_cpu(sb->feature_map) & MD_FEATURE_NEW_OFFSET))
         rdev->new_data_offset += (s32)le32_to_cpu(sb->new_offset);
     atomic_set(&rdev->corrected_errors, le32_to_cpu(sb->cnt_corrected_read));
 
     rdev->sb_size = le32_to_cpu(sb->max_dev) * 2 + 256;
     bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
     if (rdev->sb_size & bmask)
         rdev->sb_size = (rdev->sb_size | bmask) + 1;
 
     if (minor_version
         && rdev->data_offset < sb_start + (rdev->sb_size/512))
         return -EINVAL;
     if (minor_version
         && rdev->new_data_offset < sb_start + (rdev->sb_size/512))
         return -EINVAL;
 
     if (sb->level == cpu_to_le32(LEVEL_MULTIPATH))
         rdev->desc_nr = -1;
     else
         rdev->desc_nr = le32_to_cpu(sb->dev_number);
 
     if (!rdev->bb_page) {
         rdev->bb_page = alloc_page(GFP_KERNEL);
         if (!rdev->bb_page)
             return -ENOMEM;
     }
     if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BAD_BLOCKS) &&
         rdev->badblocks.count == 0) {
         /* need to load the bad block list.
          * Currently we limit it to one page.
          */
         s32 offset;
         sector_t bb_sector;
         __le64 *bbp;
         int i;
         int sectors = le16_to_cpu(sb->bblog_size);
         if (sectors > (PAGE_SIZE / 512))
             return -EINVAL;
         offset = le32_to_cpu(sb->bblog_offset);
         if (offset == 0)
             return -EINVAL;
         bb_sector = (long long)offset;
         if (!sync_page_io(rdev, bb_sector, sectors << 9,
                   rdev->bb_page, REQ_OP_READ, true))
             return -EIO;
         bbp = (__le64 *)page_address(rdev->bb_page);
         rdev->badblocks.shift = sb->bblog_shift;
         for (i = 0 ; i < (sectors << (9-3)) ; i++, bbp++) {
             u64 bb = le64_to_cpu(*bbp);
             int count = bb & (0x3ff);
             u64 sector = bb >> 10;
             sector <<= sb->bblog_shift;
             count <<= sb->bblog_shift;
             if (bb + 1 == 0)
                 break;
             if (badblocks_set(&rdev->badblocks, sector, count, 1))
                 return -EINVAL;
         }
     } else if (sb->bblog_offset != 0)
         rdev->badblocks.shift = 0;
 
     if ((le32_to_cpu(sb->feature_map) &
         (MD_FEATURE_PPL | MD_FEATURE_MULTIPLE_PPLS))) {
         rdev->ppl.offset = (__s16)le16_to_cpu(sb->ppl.offset);
         rdev->ppl.size = le16_to_cpu(sb->ppl.size);
         rdev->ppl.sector = rdev->sb_start + rdev->ppl.offset;
     }
 
     if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RAID0_LAYOUT) &&
         sb->level != 0)
         return -EINVAL;
 
     /* not spare disk, or LEVEL_MULTIPATH */
     if (sb->level == cpu_to_le32(LEVEL_MULTIPATH) ||
         (rdev->desc_nr >= 0 &&
         rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
         (le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < MD_DISK_ROLE_MAX ||
          le16_to_cpu(sb->dev_roles[rdev->desc_nr]) == MD_DISK_ROLE_JOURNAL)))
         spare_disk = false;
 
     if (!refdev) {
         if (!spare_disk)
             ret = 1;
         else
             ret = 0;
     } else {
         __u64 ev1, ev2;
         struct mdp_superblock_1 *refsb = page_address(refdev->sb_page);
 
         if (memcmp(sb->set_uuid, refsb->set_uuid, 16) != 0 ||
             sb->level != refsb->level ||
             sb->layout != refsb->layout ||
             sb->chunksize != refsb->chunksize) {
             pr_warn("md: %pg has strangely different superblock to %pg\n",
                 rdev->bdev,
                 refdev->bdev);
             return -EINVAL;
         }
         ev1 = le64_to_cpu(sb->events);
         ev2 = le64_to_cpu(refsb->events);
 
         if (!spare_disk && ev1 > ev2)
             ret = 1;
         else
             ret = 0;
     }
     if (minor_version)
         sectors = bdev_nr_sectors(rdev->bdev) - rdev->data_offset;
     else
         sectors = rdev->sb_start;
     if (sectors < le64_to_cpu(sb->data_size))
         return -EINVAL;
     rdev->sectors = le64_to_cpu(sb->data_size);
     return ret;
 }
 
 static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)
 {
     struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
     __u64 ev1 = le64_to_cpu(sb->events);
 
     rdev->raid_disk = -1;
     clear_bit(Faulty, &rdev->flags);
     clear_bit(In_sync, &rdev->flags);
     clear_bit(Bitmap_sync, &rdev->flags);
     clear_bit(WriteMostly, &rdev->flags);
 
     if (mddev->raid_disks == 0) {
         mddev->major_version = 1;
         mddev->patch_version = 0;
         mddev->external = 0;
         mddev->chunk_sectors = le32_to_cpu(sb->chunksize);
         mddev->ctime = le64_to_cpu(sb->ctime);
         mddev->utime = le64_to_cpu(sb->utime);
         mddev->level = le32_to_cpu(sb->level);
         mddev->clevel[0] = 0;
         mddev->layout = le32_to_cpu(sb->layout);
         mddev->raid_disks = le32_to_cpu(sb->raid_disks);
         mddev->dev_sectors = le64_to_cpu(sb->size);
         mddev->events = ev1;
         mddev->bitmap_info.offset = 0;
         mddev->bitmap_info.space = 0;
         /* Default location for bitmap is 1K after superblock
          * using 3K - total of 4K
          */
         mddev->bitmap_info.default_offset = 1024 >> 9;
         mddev->bitmap_info.default_space = (4096-1024) >> 9;
         mddev->reshape_backwards = 0;
 
         mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
         memcpy(mddev->uuid, sb->set_uuid, 16);
 
         mddev->max_disks =  (4096-256)/2;
 
         if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BITMAP_OFFSET) &&
             mddev->bitmap_info.file == NULL) {
             mddev->bitmap_info.offset =
                 (__s32)le32_to_cpu(sb->bitmap_offset);
             /* Metadata doesn't record how much space is available.
              * For 1.0, we assume we can use up to the superblock
              * if before, else to 4K beyond superblock.
              * For others, assume no change is possible.
              */
             if (mddev->minor_version > 0)
                 mddev->bitmap_info.space = 0;
             else if (mddev->bitmap_info.offset > 0)
                 mddev->bitmap_info.space =
                     8 - mddev->bitmap_info.offset;
             else
                 mddev->bitmap_info.space =
                     -mddev->bitmap_info.offset;
         }
 
         if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
             mddev->reshape_position = le64_to_cpu(sb->reshape_position);
             mddev->delta_disks = le32_to_cpu(sb->delta_disks);
             mddev->new_level = le32_to_cpu(sb->new_level);
             mddev->new_layout = le32_to_cpu(sb->new_layout);
             mddev->new_chunk_sectors = le32_to_cpu(sb->new_chunk);
             if (mddev->delta_disks < 0 ||
                 (mddev->delta_disks == 0 &&
                  (le32_to_cpu(sb->feature_map)
                   & MD_FEATURE_RESHAPE_BACKWARDS)))
                 mddev->reshape_backwards = 1;
         } else {
             mddev->reshape_position = MaxSector;
             mddev->delta_disks = 0;
             mddev->new_level = mddev->level;
             mddev->new_layout = mddev->layout;
             mddev->new_chunk_sectors = mddev->chunk_sectors;
         }
 
         if (mddev->level == 0 &&
             !(le32_to_cpu(sb->feature_map) & MD_FEATURE_RAID0_LAYOUT))
             mddev->layout = -1;
 
         if (le32_to_cpu(sb->feature_map) & MD_FEATURE_JOURNAL)
             set_bit(MD_HAS_JOURNAL, &mddev->flags);
 
         if (le32_to_cpu(sb->feature_map) &
             (MD_FEATURE_PPL | MD_FEATURE_MULTIPLE_PPLS)) {
             if (le32_to_cpu(sb->feature_map) &
                 (MD_FEATURE_BITMAP_OFFSET | MD_FEATURE_JOURNAL))
                 return -EINVAL;
             if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_PPL) &&
                 (le32_to_cpu(sb->feature_map) &
                         MD_FEATURE_MULTIPLE_PPLS))
                 return -EINVAL;
             set_bit(MD_HAS_PPL, &mddev->flags);
         }
     } else if (mddev->pers == NULL) {
         /* Insist of good event counter while assembling, except for
          * spares (which don't need an event count) */
         ++ev1;
         if (rdev->desc_nr >= 0 &&
             rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
             (le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < MD_DISK_ROLE_MAX ||
              le16_to_cpu(sb->dev_roles[rdev->desc_nr]) == MD_DISK_ROLE_JOURNAL))
             if (ev1 < mddev->events)
                 return -EINVAL;
     } else if (mddev->bitmap) {
         /* If adding to array with a bitmap, then we can accept an
          * older device, but not too old.
          */
         if (ev1 < mddev->bitmap->events_cleared)
             return 0;
         if (ev1 < mddev->events)
             set_bit(Bitmap_sync, &rdev->flags);
     } else {
         if (ev1 < mddev->events)
             /* just a hot-add of a new device, leave raid_disk at -1 */
             return 0;
     }
     if (mddev->level != LEVEL_MULTIPATH) {
         int role;
         if (rdev->desc_nr < 0 ||
             rdev->desc_nr >= le32_to_cpu(sb->max_dev)) {
             role = MD_DISK_ROLE_SPARE;
             rdev->desc_nr = -1;
         } else
             role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
         switch(role) {
         case MD_DISK_ROLE_SPARE: /* spare */
             break;
         case MD_DISK_ROLE_FAULTY: /* faulty */
             set_bit(Faulty, &rdev->flags);
             break;
         case MD_DISK_ROLE_JOURNAL: /* journal device */
             if (!(le32_to_cpu(sb->feature_map) & MD_FEATURE_JOURNAL)) {
                 /* journal device without journal feature */
                 pr_warn("md: journal device provided without journal feature, ignoring the device\n");
                 return -EINVAL;
             }
             set_bit(Journal, &rdev->flags);
             rdev->journal_tail = le64_to_cpu(sb->journal_tail);
             rdev->raid_disk = 0;
             break;
         default:
             rdev->saved_raid_disk = role;
             if ((le32_to_cpu(sb->feature_map) &
                  MD_FEATURE_RECOVERY_OFFSET)) {
                 rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
                 if (!(le32_to_cpu(sb->feature_map) &
                       MD_FEATURE_RECOVERY_BITMAP))
                     rdev->saved_raid_disk = -1;
             } else {
                 /*
                  * If the array is FROZEN, then the device can't
                  * be in_sync with rest of array.
                  */
                 if (!test_bit(MD_RECOVERY_FROZEN,
                           &mddev->recovery))
                     set_bit(In_sync, &rdev->flags);
             }
             rdev->raid_disk = role;
             break;
         }
         if (sb->devflags & WriteMostly1)
             set_bit(WriteMostly, &rdev->flags);
         if (sb->devflags & FailFast1)
             set_bit(FailFast, &rdev->flags);
         if (le32_to_cpu(sb->feature_map) & MD_FEATURE_REPLACEMENT)
             set_bit(Replacement, &rdev->flags);
     } else /* MULTIPATH are always insync */
         set_bit(In_sync, &rdev->flags);
 
     return 0;
 }
 
 static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
 {
     struct mdp_superblock_1 *sb;
     struct md_rdev *rdev2;
     int max_dev, i;
     /* make rdev->sb match mddev and rdev data. */
 
     sb = page_address(rdev->sb_page);
 
     sb->feature_map = 0;
     sb->pad0 = 0;
     sb->recovery_offset = cpu_to_le64(0);
     memset(sb->pad3, 0, sizeof(sb->pad3));
 
     sb->utime = cpu_to_le64((__u64)mddev->utime);
     sb->events = cpu_to_le64(mddev->events);
     if (mddev->in_sync)
         sb->resync_offset = cpu_to_le64(mddev->recovery_cp);
     else if (test_bit(MD_JOURNAL_CLEAN, &mddev->flags))
         sb->resync_offset = cpu_to_le64(MaxSector);
     else
         sb->resync_offset = cpu_to_le64(0);
 
     sb->cnt_corrected_read = cpu_to_le32(atomic_read(&rdev->corrected_errors));
 
     sb->raid_disks = cpu_to_le32(mddev->raid_disks);
     sb->size = cpu_to_le64(mddev->dev_sectors);
     sb->chunksize = cpu_to_le32(mddev->chunk_sectors);
     sb->level = cpu_to_le32(mddev->level);
     sb->layout = cpu_to_le32(mddev->layout);
     if (test_bit(FailFast, &rdev->flags))
         sb->devflags |= FailFast1;
     else
         sb->devflags &= ~FailFast1;
 
     if (test_bit(WriteMostly, &rdev->flags))
         sb->devflags |= WriteMostly1;
     else
         sb->devflags &= ~WriteMostly1;
     sb->data_offset = cpu_to_le64(rdev->data_offset);
     sb->data_size = cpu_to_le64(rdev->sectors);
 
     if (mddev->bitmap && mddev->bitmap_info.file == NULL) {
         sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_info.offset);
         sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
     }
 
     if (rdev->raid_disk >= 0 && !test_bit(Journal, &rdev->flags) &&
         !test_bit(In_sync, &rdev->flags)) {
         sb->feature_map |=
             cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET);
         sb->recovery_offset =
             cpu_to_le64(rdev->recovery_offset);
         if (rdev->saved_raid_disk >= 0 && mddev->bitmap)
             sb->feature_map |=
                 cpu_to_le32(MD_FEATURE_RECOVERY_BITMAP);
     }
     /* Note: recovery_offset and journal_tail share space  */
     if (test_bit(Journal, &rdev->flags))
         sb->journal_tail = cpu_to_le64(rdev->journal_tail);
     if (test_bit(Replacement, &rdev->flags))
         sb->feature_map |=
             cpu_to_le32(MD_FEATURE_REPLACEMENT);
 
     if (mddev->reshape_position != MaxSector) {
         sb->feature_map |= cpu_to_le32(MD_FEATURE_RESHAPE_ACTIVE);
         sb->reshape_position = cpu_to_le64(mddev->reshape_position);
         sb->new_layout = cpu_to_le32(mddev->new_layout);
         sb->delta_disks = cpu_to_le32(mddev->delta_disks);
         sb->new_level = cpu_to_le32(mddev->new_level);
         sb->new_chunk = cpu_to_le32(mddev->new_chunk_sectors);
         if (mddev->delta_disks == 0 &&
             mddev->reshape_backwards)
             sb->feature_map
                 |= cpu_to_le32(MD_FEATURE_RESHAPE_BACKWARDS);
         if (rdev->new_data_offset != rdev->data_offset) {
             sb->feature_map
                 |= cpu_to_le32(MD_FEATURE_NEW_OFFSET);
             sb->new_offset = cpu_to_le32((__u32)(rdev->new_data_offset
                                  - rdev->data_offset));
         }
     }
 
     if (mddev_is_clustered(mddev))
         sb->feature_map |= cpu_to_le32(MD_FEATURE_CLUSTERED);
 
     if (rdev->badblocks.count == 0)
         /* Nothing to do for bad blocks*/ ;
     else if (sb->bblog_offset == 0)
         /* Cannot record bad blocks on this device */
         md_error(mddev, rdev);
     else {
         struct badblocks *bb = &rdev->badblocks;
         __le64 *bbp = (__le64 *)page_address(rdev->bb_page);
         u64 *p = bb->page;
         sb->feature_map |= cpu_to_le32(MD_FEATURE_BAD_BLOCKS);
         if (bb->changed) {
             unsigned seq;
 
 retry:
             seq = read_seqbegin(&bb->lock);
 
             memset(bbp, 0xff, PAGE_SIZE);
 
             for (i = 0 ; i < bb->count ; i++) {
                 u64 internal_bb = p[i];
                 u64 store_bb = ((BB_OFFSET(internal_bb) << 10)
                         | BB_LEN(internal_bb));
                 bbp[i] = cpu_to_le64(store_bb);
             }
             bb->changed = 0;
             if (read_seqretry(&bb->lock, seq))
                 goto retry;
 
             bb->sector = (rdev->sb_start +
                       (int)le32_to_cpu(sb->bblog_offset));
             bb->size = le16_to_cpu(sb->bblog_size);
         }
     }
 
     max_dev = 0;
     rdev_for_each(rdev2, mddev)
         if (rdev2->desc_nr+1 > max_dev)
             max_dev = rdev2->desc_nr+1;
 
     if (max_dev > le32_to_cpu(sb->max_dev)) {
         int bmask;
         sb->max_dev = cpu_to_le32(max_dev);
         rdev->sb_size = max_dev * 2 + 256;
         bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
         if (rdev->sb_size & bmask)
             rdev->sb_size = (rdev->sb_size | bmask) + 1;
     } else
         max_dev = le32_to_cpu(sb->max_dev);
 
     for (i=0; i<max_dev;i++)
         sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_SPARE);
 
     if (test_bit(MD_HAS_JOURNAL, &mddev->flags))
         sb->feature_map |= cpu_to_le32(MD_FEATURE_JOURNAL);
 
     if (test_bit(MD_HAS_PPL, &mddev->flags)) {
         if (test_bit(MD_HAS_MULTIPLE_PPLS, &mddev->flags))
             sb->feature_map |=
                 cpu_to_le32(MD_FEATURE_MULTIPLE_PPLS);
         else
             sb->feature_map |= cpu_to_le32(MD_FEATURE_PPL);
         sb->ppl.offset = cpu_to_le16(rdev->ppl.offset);
         sb->ppl.size = cpu_to_le16(rdev->ppl.size);
     }
 
     rdev_for_each(rdev2, mddev) {
         i = rdev2->desc_nr;
         if (test_bit(Faulty, &rdev2->flags))
             sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_FAULTY);
         else if (test_bit(In_sync, &rdev2->flags))
             sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
         else if (test_bit(Journal, &rdev2->flags))
             sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_JOURNAL);
         else if (rdev2->raid_disk >= 0)
             sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
         else
             sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_SPARE);
     }
 
     sb->sb_csum = calc_sb_1_csum(sb);
 }
 
 static sector_t super_1_choose_bm_space(sector_t dev_size)
 {
     sector_t bm_space;
 
     /* if the device is bigger than 8Gig, save 64k for bitmap
      * usage, if bigger than 200Gig, save 128k
      */
     if (dev_size < 64*2)
         bm_space = 0;
     else if (dev_size - 64*2 >= 200*1024*1024*2)
         bm_space = 128*2;
     else if (dev_size - 4*2 > 8*1024*1024*2)
         bm_space = 64*2;
     else
         bm_space = 4*2;
     return bm_space;
 }
 
 static unsigned long long
 super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
 {
     struct mdp_superblock_1 *sb;
     sector_t max_sectors;
     if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
         return 0; /* component must fit device */
     if (rdev->data_offset != rdev->new_data_offset)
         return 0; /* too confusing */
     if (rdev->sb_start < rdev->data_offset) {
         /* minor versions 1 and 2; superblock before data */
         max_sectors = bdev_nr_sectors(rdev->bdev) - rdev->data_offset;
         if (!num_sectors || num_sectors > max_sectors)
             num_sectors = max_sectors;
     } else if (rdev->mddev->bitmap_info.offset) {
         /* minor version 0 with bitmap we can't move */
         return 0;
     } else {
         /* minor version 0; superblock after data */
         sector_t sb_start, bm_space;
         sector_t dev_size = bdev_nr_sectors(rdev->bdev);
 
         /* 8K is for superblock */
         sb_start = dev_size - 8*2;
         sb_start &= ~(sector_t)(4*2 - 1);
 
         bm_space = super_1_choose_bm_space(dev_size);
 
         /* Space that can be used to store date needs to decrease
          * superblock bitmap space and bad block space(4K)
          */
         max_sectors = sb_start - bm_space - 4*2;
 
         if (!num_sectors || num_sectors > max_sectors)
             num_sectors = max_sectors;
         rdev->sb_start = sb_start;
     }
     sb = page_address(rdev->sb_page);
     sb->data_size = cpu_to_le64(num_sectors);
     sb->super_offset = cpu_to_le64(rdev->sb_start);
     sb->sb_csum = calc_sb_1_csum(sb);
     do {
         md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
                    rdev->sb_page);
     } while (md_super_wait(rdev->mddev) < 0);
     return num_sectors;
 
 }
 
 static int
 super_1_allow_new_offset(struct md_rdev *rdev,
              unsigned long long new_offset)
 {
     /* All necessary checks on new >= old have been done */
     struct bitmap *bitmap;
     if (new_offset >= rdev->data_offset)
         return 1;
 
     /* with 1.0 metadata, there is no metadata to tread on
      * so we can always move back */
     if (rdev->mddev->minor_version == 0)
         return 1;
 
     /* otherwise we must be sure not to step on
      * any metadata, so stay:
      * 36K beyond start of superblock
      * beyond end of badblocks
      * beyond write-intent bitmap
      */
     if (rdev->sb_start + (32+4)*2 > new_offset)
         return 0;
     bitmap = rdev->mddev->bitmap;
     if (bitmap && !rdev->mddev->bitmap_info.file &&
         rdev->sb_start + rdev->mddev->bitmap_info.offset +
         bitmap->storage.file_pages * (PAGE_SIZE>>9) > new_offset)
         return 0;
     if (rdev->badblocks.sector + rdev->badblocks.size > new_offset)
         return 0;
 
     return 1;
 }
 
 static struct super_type super_types[] = {
     [0] = {
         .name   = "0.90.0",
         .owner  = THIS_MODULE,
         .load_super     = super_90_load,
         .validate_super     = super_90_validate,
         .sync_super     = super_90_sync,
         .rdev_size_change   = super_90_rdev_size_change,
         .allow_new_offset   = super_90_allow_new_offset,
     },
     [1] = {
         .name   = "md-1",
         .owner  = THIS_MODULE,
         .load_super     = super_1_load,
         .validate_super     = super_1_validate,
         .sync_super     = super_1_sync,
         .rdev_size_change   = super_1_rdev_size_change,
         .allow_new_offset   = super_1_allow_new_offset,
     },
 };
 
 static void sync_super(struct mddev *mddev, struct md_rdev *rdev)
 {
     if (mddev->sync_super) {
         mddev->sync_super(mddev, rdev);
         return;
     }
 
     BUG_ON(mddev->major_version >= ARRAY_SIZE(super_types));
 
     super_types[mddev->major_version].sync_super(mddev, rdev);
 }
 
 static int match_mddev_units(struct mddev *mddev1, struct mddev *mddev2)
 {
     struct md_rdev *rdev, *rdev2;
 
     rcu_read_lock();
     rdev_for_each_rcu(rdev, mddev1) {
         if (test_bit(Faulty, &rdev->flags) ||
             test_bit(Journal, &rdev->flags) ||
             rdev->raid_disk == -1)
             continue;
         rdev_for_each_rcu(rdev2, mddev2) {
             if (test_bit(Faulty, &rdev2->flags) ||
                 test_bit(Journal, &rdev2->flags) ||
                 rdev2->raid_disk == -1)
                 continue;
             if (rdev->bdev->bd_disk == rdev2->bdev->bd_disk) {
                 rcu_read_unlock();
                 return 1;
             }
         }
     }
     rcu_read_unlock();
     return 0;
 }
 
 static LIST_HEAD(pending_raid_disks);
 
 /*
  * Try to register data integrity profile for an mddev
  *
  * This is called when an array is started and after a disk has been kicked
  * from the array. It only succeeds if all working and active component devices
  * are integrity capable with matching profiles.
  */
 int md_integrity_register(struct mddev *mddev)
 {
     struct md_rdev *rdev, *reference = NULL;
 
     if (list_empty(&mddev->disks))
         return 0; /* nothing to do */
     if (!mddev->gendisk || blk_get_integrity(mddev->gendisk))
         return 0; /* shouldn't register, or already is */
     rdev_for_each(rdev, mddev) {
         /* skip spares and non-functional disks */
         if (test_bit(Faulty, &rdev->flags))
             continue;
         if (rdev->raid_disk < 0)
             continue;
         if (!reference) {
             /* Use the first rdev as the reference */
             reference = rdev;
             continue;
         }
         /* does this rdev's profile match the reference profile? */
         if (blk_integrity_compare(reference->bdev->bd_disk,
                 rdev->bdev->bd_disk) < 0)
             return -EINVAL;
     }
     if (!reference || !bdev_get_integrity(reference->bdev))
         return 0;
     /*
      * All component devices are integrity capable and have matching
      * profiles, register the common profile for the md device.
      */
     blk_integrity_register(mddev->gendisk,
                    bdev_get_integrity(reference->bdev));
 
     pr_debug("md: data integrity enabled on %s\n", mdname(mddev));
     if (bioset_integrity_create(&mddev->bio_set, BIO_POOL_SIZE) ||
         (mddev->level != 1 && mddev->level != 10 &&
          bioset_integrity_create(&mddev->io_acct_set, BIO_POOL_SIZE))) {
         /*
          * No need to handle the failure of bioset_integrity_create,
          * because the function is called by md_run() -> pers->run(),
          * md_run calls bioset_exit -> bioset_integrity_free in case
          * of failure case.
          */
         pr_err("md: failed to create integrity pool for %s\n",
                mdname(mddev));
         return -EINVAL;
     }
     return 0;
 }
 EXPORT_SYMBOL(md_integrity_register);
 
 /*
  * Attempt to add an rdev, but only if it is consistent with the current
  * integrity profile
  */
 int md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev)
 {
     struct blk_integrity *bi_mddev;
 
     if (!mddev->gendisk)
         return 0;
 
     bi_mddev = blk_get_integrity(mddev->gendisk);
 
     if (!bi_mddev) /* nothing to do */
         return 0;
 
     if (blk_integrity_compare(mddev->gendisk, rdev->bdev->bd_disk) != 0) {
         pr_err("%s: incompatible integrity profile for %pg\n",
                mdname(mddev), rdev->bdev);
         return -ENXIO;
     }
 
     return 0;
 }
 EXPORT_SYMBOL(md_integrity_add_rdev);
 
 static bool rdev_read_only(struct md_rdev *rdev)
 {
     return bdev_read_only(rdev->bdev) ||
         (rdev->meta_bdev && bdev_read_only(rdev->meta_bdev));
 }
 
 static int bind_rdev_to_array(struct md_rdev *rdev, struct mddev *mddev)
 {
     char b[BDEVNAME_SIZE];
     int err;
 
     /* prevent duplicates */
     if (find_rdev(mddev, rdev->bdev->bd_dev))
         return -EEXIST;
 
     if (rdev_read_only(rdev) && mddev->pers)
         return -EROFS;
 
     /* make sure rdev->sectors exceeds mddev->dev_sectors */
     if (!test_bit(Journal, &rdev->flags) &&
         rdev->sectors &&
         (mddev->dev_sectors == 0 || rdev->sectors < mddev->dev_sectors)) {
         if (mddev->pers) {
             /* Cannot change size, so fail
              * If mddev->level <= 0, then we don't care
              * about aligning sizes (e.g. linear)
              */
             if (mddev->level > 0)
                 return -ENOSPC;
         } else
             mddev->dev_sectors = rdev->sectors;
     }
 
     /* Verify rdev->desc_nr is unique.
      * If it is -1, assign a free number, else
      * check number is not in use
      */
     rcu_read_lock();
     if (rdev->desc_nr < 0) {
         int choice = 0;
         if (mddev->pers)
             choice = mddev->raid_disks;
         while (md_find_rdev_nr_rcu(mddev, choice))
             choice++;
         rdev->desc_nr = choice;
     } else {
         if (md_find_rdev_nr_rcu(mddev, rdev->desc_nr)) {
             rcu_read_unlock();
             return -EBUSY;
         }
     }
     rcu_read_unlock();
     if (!test_bit(Journal, &rdev->flags) &&
         mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {
         pr_warn("md: %s: array is limited to %d devices\n",
             mdname(mddev), mddev->max_disks);
         return -EBUSY;
     }
     snprintf(b, sizeof(b), "%pg", rdev->bdev);
     strreplace(b, '/', '!');
 
     rdev->mddev = mddev;
     pr_debug("md: bind<%s>\n", b);
 
     if (mddev->raid_disks)
         mddev_create_serial_pool(mddev, rdev, false);
 
     if ((err = kobject_add(&rdev->kobj, &mddev->kobj, "dev-%s", b)))
         goto fail;
 
     /* failure here is OK */
     err = sysfs_create_link(&rdev->kobj, bdev_kobj(rdev->bdev), "block");
     rdev->sysfs_state = sysfs_get_dirent_safe(rdev->kobj.sd, "state");
     rdev->sysfs_unack_badblocks =
         sysfs_get_dirent_safe(rdev->kobj.sd, "unacknowledged_bad_blocks");
     rdev->sysfs_badblocks =
         sysfs_get_dirent_safe(rdev->kobj.sd, "bad_blocks");
 
     list_add_rcu(&rdev->same_set, &mddev->disks);
     bd_link_disk_holder(rdev->bdev, mddev->gendisk);
 
     /* May as well allow recovery to be retried once */
     mddev->recovery_disabled++;
 
     return 0;
 
  fail:
     pr_warn("md: failed to register dev-%s for %s\n",
         b, mdname(mddev));
     return err;
 }
 
 static void rdev_delayed_delete(struct work_struct *ws)
 {
     struct md_rdev *rdev = container_of(ws, struct md_rdev, del_work);
     kobject_del(&rdev->kobj);
     kobject_put(&rdev->kobj);
 }
 
 static void unbind_rdev_from_array(struct md_rdev *rdev)
 {
     bd_unlink_disk_holder(rdev->bdev, rdev->mddev->gendisk);
     list_del_rcu(&rdev->same_set);
     pr_debug("md: unbind<%pg>\n", rdev->bdev);
     mddev_destroy_serial_pool(rdev->mddev, rdev, false);
     rdev->mddev = NULL;
     sysfs_remove_link(&rdev->kobj, "block");
     sysfs_put(rdev->sysfs_state);
     sysfs_put(rdev->sysfs_unack_badblocks);
     sysfs_put(rdev->sysfs_badblocks);
     rdev->sysfs_state = NULL;
     rdev->sysfs_unack_badblocks = NULL;
     rdev->sysfs_badblocks = NULL;
     rdev->badblocks.count = 0;
     /* We need to delay this, otherwise we can deadlock when
      * writing to 'remove' to "dev/state".  We also need
      * to delay it due to rcu usage.
      */
     synchronize_rcu();
     INIT_WORK(&rdev->del_work, rdev_delayed_delete);
     kobject_get(&rdev->kobj);
     queue_work(md_rdev_misc_wq, &rdev->del_work);
 }
 
 /*
  * prevent the device from being mounted, repartitioned or
  * otherwise reused by a RAID array (or any other kernel
  * subsystem), by bd_claiming the device.
  */
 static int lock_rdev(struct md_rdev *rdev, dev_t dev, int shared)
 {
     int err = 0;
     struct block_device *bdev;
 
     bdev = blkdev_get_by_dev(dev, FMODE_READ|FMODE_WRITE|FMODE_EXCL,
                  shared ? (struct md_rdev *)lock_rdev : rdev);
     if (IS_ERR(bdev)) {
         pr_warn("md: could not open device unknown-block(%u,%u).\n",
             MAJOR(dev), MINOR(dev));
         return PTR_ERR(bdev);
     }
     rdev->bdev = bdev;
     return err;
 }
 
 static void unlock_rdev(struct md_rdev *rdev)
 {
     struct block_device *bdev = rdev->bdev;
     rdev->bdev = NULL;
     blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
 }
 
 void md_autodetect_dev(dev_t dev);
 
 static void export_rdev(struct md_rdev *rdev)
 {
     pr_debug("md: export_rdev(%pg)\n", rdev->bdev);
     md_rdev_clear(rdev);
 #ifndef MODULE
     if (test_bit(AutoDetected, &rdev->flags))
         md_autodetect_dev(rdev->bdev->bd_dev);
 #endif
     unlock_rdev(rdev);
     kobject_put(&rdev->kobj);
 }
 
 void md_kick_rdev_from_array(struct md_rdev *rdev)
 {
     unbind_rdev_from_array(rdev);
     export_rdev(rdev);
 }
 EXPORT_SYMBOL_GPL(md_kick_rdev_from_array);
 
 static void export_array(struct mddev *mddev)
 {
     struct md_rdev *rdev;
 
     while (!list_empty(&mddev->disks)) {
         rdev = list_first_entry(&mddev->disks, struct md_rdev,
                     same_set);
         md_kick_rdev_from_array(rdev);
     }
     mddev->raid_disks = 0;
     mddev->major_version = 0;
 }
 
 static bool set_in_sync(struct mddev *mddev)
 {
     lockdep_assert_held(&mddev->lock);
     if (!mddev->in_sync) {
         mddev->sync_checkers++;
         spin_unlock(&mddev->lock);
         percpu_ref_switch_to_atomic_sync(&mddev->writes_pending);
         spin_lock(&mddev->lock);
         if (!mddev->in_sync &&
             percpu_ref_is_zero(&mddev->writes_pending)) {
             mddev->in_sync = 1;
             /*
              * Ensure ->in_sync is visible before we clear
              * ->sync_checkers.
              */
             smp_mb();
             set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
             sysfs_notify_dirent_safe(mddev->sysfs_state);
         }
         if (--mddev->sync_checkers == 0)
             percpu_ref_switch_to_percpu(&mddev->writes_pending);
     }
     if (mddev->safemode == 1)
         mddev->safemode = 0;
     return mddev->in_sync;
 }
 
 static void sync_sbs(struct mddev *mddev, int nospares)
 {
     /* Update each superblock (in-memory image), but
      * if we are allowed to, skip spares which already
      * have the right event counter, or have one earlier
      * (which would mean they aren't being marked as dirty
      * with the rest of the array)
      */
     struct md_rdev *rdev;
     rdev_for_each(rdev, mddev) {
         if (rdev->sb_events == mddev->events ||
             (nospares &&
              rdev->raid_disk < 0 &&
              rdev->sb_events+1 == mddev->events)) {
             /* Don't update this superblock */
             rdev->sb_loaded = 2;
         } else {
             sync_super(mddev, rdev);
             rdev->sb_loaded = 1;
         }
     }
 }
 
 static bool does_sb_need_changing(struct mddev *mddev)
 {
     struct md_rdev *rdev = NULL, *iter;
     struct mdp_superblock_1 *sb;
     int role;
 
     /* Find a good rdev */
     rdev_for_each(iter, mddev)
         if ((iter->raid_disk >= 0) && !test_bit(Faulty, &iter->flags)) {
             rdev = iter;
             break;
         }
 
     /* No good device found. */
     if (!rdev)
         return false;
 
     sb = page_address(rdev->sb_page);
     /* Check if a device has become faulty or a spare become active */
     rdev_for_each(rdev, mddev) {
         role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
         /* Device activated? */
         if (role == MD_DISK_ROLE_SPARE && rdev->raid_disk >= 0 &&
             !test_bit(Faulty, &rdev->flags))
             return true;
         /* Device turned faulty? */
         if (test_bit(Faulty, &rdev->flags) && (role < MD_DISK_ROLE_MAX))
             return true;
     }
 
     /* Check if any mddev parameters have changed */
     if ((mddev->dev_sectors != le64_to_cpu(sb->size)) ||
         (mddev->reshape_position != le64_to_cpu(sb->reshape_position)) ||
         (mddev->layout != le32_to_cpu(sb->layout)) ||
         (mddev->raid_disks != le32_to_cpu(sb->raid_disks)) ||
         (mddev->chunk_sectors != le32_to_cpu(sb->chunksize)))
         return true;
 
     return false;
 }
 
 void md_update_sb(struct mddev *mddev, int force_change)
 {
     struct md_rdev *rdev;
     int sync_req;
     int nospares = 0;
     int any_badblocks_changed = 0;
     int ret = -1;
 
     if (mddev->ro) {
         if (force_change)
             set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
         return;
     }
 
 repeat:
     if (mddev_is_clustered(mddev)) {
         if (test_and_clear_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags))
             force_change = 1;
         if (test_and_clear_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags))
             nospares = 1;
         ret = md_cluster_ops->metadata_update_start(mddev);
         /* Has someone else has updated the sb */
         if (!does_sb_need_changing(mddev)) {
             if (ret == 0)
                 md_cluster_ops->metadata_update_cancel(mddev);
             bit_clear_unless(&mddev->sb_flags, BIT(MD_SB_CHANGE_PENDING),
                              BIT(MD_SB_CHANGE_DEVS) |
                              BIT(MD_SB_CHANGE_CLEAN));
             return;
         }
     }
 
     /*
      * First make sure individual recovery_offsets are correct
      * curr_resync_completed can only be used during recovery.
      * During reshape/resync it might use array-addresses rather
      * that device addresses.
      */
     rdev_for_each(rdev, mddev) {
         if (rdev->raid_disk >= 0 &&
             mddev->delta_disks >= 0 &&
             test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
             test_bit(MD_RECOVERY_RECOVER, &mddev->recovery) &&
             !test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
             !test_bit(Journal, &rdev->flags) &&
             !test_bit(In_sync, &rdev->flags) &&
             mddev->curr_resync_completed > rdev->recovery_offset)
                 rdev->recovery_offset = mddev->curr_resync_completed;
 
     }
     if (!mddev->persistent) {
         clear_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
         clear_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
         if (!mddev->external) {
             clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
             rdev_for_each(rdev, mddev) {
                 if (rdev->badblocks.changed) {
                     rdev->badblocks.changed = 0;
                     ack_all_badblocks(&rdev->badblocks);
                     md_error(mddev, rdev);
                 }
                 clear_bit(Blocked, &rdev->flags);
                 clear_bit(BlockedBadBlocks, &rdev->flags);
                 wake_up(&rdev->blocked_wait);
             }
         }
         wake_up(&mddev->sb_wait);
         return;
     }
 
     spin_lock(&mddev->lock);
 
     mddev->utime = ktime_get_real_seconds();
 
     if (test_and_clear_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags))
         force_change = 1;
     if (test_and_clear_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags))
         /* just a clean<-> dirty transition, possibly leave spares alone,
          * though if events isn't the right even/odd, we will have to do
          * spares after all
          */
         nospares = 1;
     if (force_change)
         nospares = 0;
     if (mddev->degraded)
         /* If the array is degraded, then skipping spares is both
          * dangerous and fairly pointless.
          * Dangerous because a device that was removed from the array
          * might have a event_count that still looks up-to-date,
          * so it can be re-added without a resync.
          * Pointless because if there are any spares to skip,
          * then a recovery will happen and soon that array won't
          * be degraded any more and the spare can go back to sleep then.
          */
         nospares = 0;
 
     sync_req = mddev->in_sync;
 
     /* If this is just a dirty<->clean transition, and the array is clean
      * and 'events' is odd, we can roll back to the previous clean state */
     if (nospares
         && (mddev->in_sync && mddev->recovery_cp == MaxSector)
         && mddev->can_decrease_events
         && mddev->events != 1) {
         mddev->events--;
         mddev->can_decrease_events = 0;
     } else {
         /* otherwise we have to go forward and ... */
         mddev->events ++;
         mddev->can_decrease_events = nospares;
     }
 
     /*
      * This 64-bit counter should never wrap.
      * Either we are in around ~1 trillion A.C., assuming
      * 1 reboot per second, or we have a bug...
      */
     WARN_ON(mddev->events == 0);
 
     rdev_for_each(rdev, mddev) {
         if (rdev->badblocks.changed)
             any_badblocks_changed++;
         if (test_bit(Faulty, &rdev->flags))
             set_bit(FaultRecorded, &rdev->flags);
     }
 
     sync_sbs(mddev, nospares);
     spin_unlock(&mddev->lock);
 
     pr_debug("md: updating %s RAID superblock on device (in sync %d)\n",
          mdname(mddev), mddev->in_sync);
 
     if (mddev->queue)
         blk_add_trace_msg(mddev->queue, "md md_update_sb");
 rewrite:
     md_bitmap_update_sb(mddev->bitmap);
     rdev_for_each(rdev, mddev) {
         if (rdev->sb_loaded != 1)
             continue; /* no noise on spare devices */
 
         if (!test_bit(Faulty, &rdev->flags)) {
             md_super_write(mddev,rdev,
                        rdev->sb_start, rdev->sb_size,
                        rdev->sb_page);
             pr_debug("md: (write) %pg's sb offset: %llu\n",
                  rdev->bdev,
                  (unsigned long long)rdev->sb_start);
             rdev->sb_events = mddev->events;
             if (rdev->badblocks.size) {
                 md_super_write(mddev, rdev,
                            rdev->badblocks.sector,
                            rdev->badblocks.size << 9,
                            rdev->bb_page);
                 rdev->badblocks.size = 0;
             }
 
         } else
             pr_debug("md: %pg (skipping faulty)\n",
                  rdev->bdev);
 
         if (mddev->level == LEVEL_MULTIPATH)
             /* only need to write one superblock... */
             break;
     }
     if (md_super_wait(mddev) < 0)
         goto rewrite;
     /* if there was a failure, MD_SB_CHANGE_DEVS was set, and we re-write super */
 
     if (mddev_is_clustered(mddev) && ret == 0)
         md_cluster_ops->metadata_update_finish(mddev);
 
     if (mddev->in_sync != sync_req ||
         !bit_clear_unless(&mddev->sb_flags, BIT(MD_SB_CHANGE_PENDING),
                    BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_CLEAN)))
         /* have to write it out again */
         goto repeat;
     wake_up(&mddev->sb_wait);
     if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
         sysfs_notify_dirent_safe(mddev->sysfs_completed);
 
     rdev_for_each(rdev, mddev) {
         if (test_and_clear_bit(FaultRecorded, &rdev->flags))
             clear_bit(Blocked, &rdev->flags);
 
         if (any_badblocks_changed)
             ack_all_badblocks(&rdev->badblocks);
         clear_bit(BlockedBadBlocks, &rdev->flags);
         wake_up(&rdev->blocked_wait);
     }
 }
 EXPORT_SYMBOL(md_update_sb);
 
 static int add_bound_rdev(struct md_rdev *rdev)
 {
     struct mddev *mddev = rdev->mddev;
     int err = 0;
     bool add_journal = test_bit(Journal, &rdev->flags);
 
     if (!mddev->pers->hot_remove_disk || add_journal) {
         /* If there is hot_add_disk but no hot_remove_disk
          * then added disks for geometry changes,
          * and should be added immediately.
          */
         super_types[mddev->major_version].
             validate_super(mddev, rdev);
         if (add_journal)
             mddev_suspend(mddev);
         err = mddev->pers->hot_add_disk(mddev, rdev);
         if (add_journal)
             mddev_resume(mddev);
         if (err) {
             md_kick_rdev_from_array(rdev);
             return err;
         }
     }
     sysfs_notify_dirent_safe(rdev->sysfs_state);
 
     set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
     if (mddev->degraded)
         set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
     set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
     md_new_event();
     md_wakeup_thread(mddev->thread);
     return 0;
 }
 
 /* words written to sysfs files may, or may not, be \n terminated.
  * We want to accept with case. For this we use cmd_match.
  */
 static int cmd_match(const char *cmd, const char *str)
 {
     /* See if cmd, written into a sysfs file, matches
      * str.  They must either be the same, or cmd can
      * have a trailing newline
      */
     while (*cmd && *str && *cmd == *str) {
         cmd++;
         str++;
     }
     if (*cmd == '\n')
         cmd++;
     if (*str || *cmd)
         return 0;
     return 1;
 }
 
 struct rdev_sysfs_entry {
     struct attribute attr;
     ssize_t (*show)(struct md_rdev *, char *);
     ssize_t (*store)(struct md_rdev *, const char *, size_t);
 };
 
 static ssize_t
 state_show(struct md_rdev *rdev, char *page)
 {
     char *sep = ",";
     size_t len = 0;
     unsigned long flags = READ_ONCE(rdev->flags);
 
     if (test_bit(Faulty, &flags) ||
         (!test_bit(ExternalBbl, &flags) &&
         rdev->badblocks.unacked_exist))
         len += sprintf(page+len, "faulty%s", sep);
     if (test_bit(In_sync, &flags))
         len += sprintf(page+len, "in_sync%s", sep);
     if (test_bit(Journal, &flags))
         len += sprintf(page+len, "journal%s", sep);
     if (test_bit(WriteMostly, &flags))
         len += sprintf(page+len, "write_mostly%s", sep);
     if (test_bit(Blocked, &flags) ||
         (rdev->badblocks.unacked_exist
          && !test_bit(Faulty, &flags)))
         len += sprintf(page+len, "blocked%s", sep);
     if (!test_bit(Faulty, &flags) &&
         !test_bit(Journal, &flags) &&
         !test_bit(In_sync, &flags))
         len += sprintf(page+len, "spare%s", sep);
     if (test_bit(WriteErrorSeen, &flags))
         len += sprintf(page+len, "write_error%s", sep);
     if (test_bit(WantReplacement, &flags))
         len += sprintf(page+len, "want_replacement%s", sep);
     if (test_bit(Replacement, &flags))
         len += sprintf(page+len, "replacement%s", sep);
     if (test_bit(ExternalBbl, &flags))
         len += sprintf(page+len, "external_bbl%s", sep);
     if (test_bit(FailFast, &flags))
         len += sprintf(page+len, "failfast%s", sep);
 
     if (len)
         len -= strlen(sep);
 
     return len+sprintf(page+len, "\n");
 }
 
 static ssize_t
 state_store(struct md_rdev *rdev, const char *buf, size_t len)
 {
     /* can write
      *  faulty  - simulates an error
      *  remove  - disconnects the device
      *  writemostly - sets write_mostly
      *  -writemostly - clears write_mostly
      *  blocked - sets the Blocked flags
      *  -blocked - clears the Blocked and possibly simulates an error
      *  insync - sets Insync providing device isn't active
      *  -insync - clear Insync for a device with a slot assigned,
      *            so that it gets rebuilt based on bitmap
      *  write_error - sets WriteErrorSeen
      *  -write_error - clears WriteErrorSeen
      *  {,-}failfast - set/clear FailFast
      */
 
     struct mddev *mddev = rdev->mddev;
     int err = -EINVAL;
     bool need_update_sb = false;
 
     if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
         md_error(rdev->mddev, rdev);
 
         if (test_bit(MD_BROKEN, &rdev->mddev->flags))
             err = -EBUSY;
         else
             err = 0;
     } else if (cmd_match(buf, "remove")) {
         if (rdev->mddev->pers) {
             clear_bit(Blocked, &rdev->flags);
             remove_and_add_spares(rdev->mddev, rdev);
         }
         if (rdev->raid_disk >= 0)
             err = -EBUSY;
         else {
             err = 0;
             if (mddev_is_clustered(mddev))
                 err = md_cluster_ops->remove_disk(mddev, rdev);
 
             if (err == 0) {
                 md_kick_rdev_from_array(rdev);
                 if (mddev->pers) {
                     set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
                     md_wakeup_thread(mddev->thread);
                 }
                 md_new_event();
             }
         }
     } else if (cmd_match(buf, "writemostly")) {
         set_bit(WriteMostly, &rdev->flags);
         mddev_create_serial_pool(rdev->mddev, rdev, false);
         need_update_sb = true;
         err = 0;
     } else if (cmd_match(buf, "-writemostly")) {
         mddev_destroy_serial_pool(rdev->mddev, rdev, false);
         clear_bit(WriteMostly, &rdev->flags);
         need_update_sb = true;
         err = 0;
     } else if (cmd_match(buf, "blocked")) {
         set_bit(Blocked, &rdev->flags);
         err = 0;
     } else if (cmd_match(buf, "-blocked")) {
         if (!test_bit(Faulty, &rdev->flags) &&
             !test_bit(ExternalBbl, &rdev->flags) &&
             rdev->badblocks.unacked_exist) {
             /* metadata handler doesn't understand badblocks,
              * so we need to fail the device
              */
             md_error(rdev->mddev, rdev);
         }
         clear_bit(Blocked, &rdev->flags);
         clear_bit(BlockedBadBlocks, &rdev->flags);
         wake_up(&rdev->blocked_wait);
         set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
         md_wakeup_thread(rdev->mddev->thread);
 
         err = 0;
     } else if (cmd_match(buf, "insync") && rdev->raid_disk == -1) {
         set_bit(In_sync, &rdev->flags);
         err = 0;
     } else if (cmd_match(buf, "failfast")) {
         set_bit(FailFast, &rdev->flags);
         need_update_sb = true;
         err = 0;
     } else if (cmd_match(buf, "-failfast")) {
         clear_bit(FailFast, &rdev->flags);
         need_update_sb = true;
         err = 0;
     } else if (cmd_match(buf, "-insync") && rdev->raid_disk >= 0 &&
            !test_bit(Journal, &rdev->flags)) {
         if (rdev->mddev->pers == NULL) {
             clear_bit(In_sync, &rdev->flags);
             rdev->saved_raid_disk = rdev->raid_disk;
             rdev->raid_disk = -1;
             err = 0;
         }
     } else if (cmd_match(buf, "write_error")) {
         set_bit(WriteErrorSeen, &rdev->flags);
         err = 0;
     } else if (cmd_match(buf, "-write_error")) {
         clear_bit(WriteErrorSeen, &rdev->flags);
         err = 0;
     } else if (cmd_match(buf, "want_replacement")) {
         /* Any non-spare device that is not a replacement can
          * become want_replacement at any time, but we then need to
          * check if recovery is needed.
          */
         if (rdev->raid_disk >= 0 &&
             !test_bit(Journal, &rdev->flags) &&
             !test_bit(Replacement, &rdev->flags))
             set_bit(WantReplacement, &rdev->flags);
         set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
         md_wakeup_thread(rdev->mddev->thread);
         err = 0;
     } else if (cmd_match(buf, "-want_replacement")) {
         /* Clearing 'want_replacement' is always allowed.
          * Once replacements starts it is too late though.
          */
         err = 0;
         clear_bit(WantReplacement, &rdev->flags);
     } else if (cmd_match(buf, "replacement")) {
         /* Can only set a device as a replacement when array has not
          * yet been started.  Once running, replacement is automatic
          * from spares, or by assigning 'slot'.
          */
         if (rdev->mddev->pers)
             err = -EBUSY;
         else {
             set_bit(Replacement, &rdev->flags);
             err = 0;
         }
     } else if (cmd_match(buf, "-replacement")) {
         /* Similarly, can only clear Replacement before start */
         if (rdev->mddev->pers)
             err = -EBUSY;
         else {
             clear_bit(Replacement, &rdev->flags);
             err = 0;
         }
     } else if (cmd_match(buf, "re-add")) {
         if (!rdev->mddev->pers)
             err = -EINVAL;
         else if (test_bit(Faulty, &rdev->flags) && (rdev->raid_disk == -1) &&
                 rdev->saved_raid_disk >= 0) {
             /* clear_bit is performed _after_ all the devices
              * have their local Faulty bit cleared. If any writes
              * happen in the meantime in the local node, they
              * will land in the local bitmap, which will be synced
              * by this node eventually
              */
             if (!mddev_is_clustered(rdev->mddev) ||
                 (err = md_cluster_ops->gather_bitmaps(rdev)) == 0) {
                 clear_bit(Faulty, &rdev->flags);
                 err = add_bound_rdev(rdev);
             }
         } else
             err = -EBUSY;
     } else if (cmd_match(buf, "external_bbl") && (rdev->mddev->external)) {
         set_bit(ExternalBbl, &rdev->flags);
         rdev->badblocks.shift = 0;
         err = 0;
     } else if (cmd_match(buf, "-external_bbl") && (rdev->mddev->external)) {
         clear_bit(ExternalBbl, &rdev->flags);
         err = 0;
     }
     if (need_update_sb)
         md_update_sb(mddev, 1);
     if (!err)
         sysfs_notify_dirent_safe(rdev->sysfs_state);
     return err ? err : len;
 }
 static struct rdev_sysfs_entry rdev_state =
 __ATTR_PREALLOC(state, S_IRUGO|S_IWUSR, state_show, state_store);
 
 static ssize_t
 errors_show(struct md_rdev *rdev, char *page)
 {
     return sprintf(page, "%d\n", atomic_read(&rdev->corrected_errors));
 }
 
 static ssize_t
 errors_store(struct md_rdev *rdev, const char *buf, size_t len)
 {
     unsigned int n;
     int rv;
 
     rv = kstrtouint(buf, 10, &n);
     if (rv < 0)
         return rv;
     atomic_set(&rdev->corrected_errors, n);
     return len;
 }
 static struct rdev_sysfs_entry rdev_errors =
 __ATTR(errors, S_IRUGO|S_IWUSR, errors_show, errors_store);
 
 static ssize_t
 slot_show(struct md_rdev *rdev, char *page)
 {
     if (test_bit(Journal, &rdev->flags))
         return sprintf(page, "journal\n");
     else if (rdev->raid_disk < 0)
         return sprintf(page, "none\n");
     else
         return sprintf(page, "%d\n", rdev->raid_disk);
 }
 
 static ssize_t
 slot_store(struct md_rdev *rdev, const char *buf, size_t len)
 {
     int slot;
     int err;
 
     if (test_bit(Journal, &rdev->flags))
         return -EBUSY;
     if (strncmp(buf, "none", 4)==0)
         slot = -1;
     else {
         err = kstrtouint(buf, 10, (unsigned int *)&slot);
         if (err < 0)
             return err;
     }
     if (rdev->mddev->pers && slot == -1) {
         /* Setting 'slot' on an active array requires also
          * updating the 'rd%d' link, and communicating
          * with the personality with ->hot_*_disk.
          * For now we only support removing
          * failed/spare devices.  This normally happens automatically,
          * but not when the metadata is externally managed.
          */
         if (rdev->raid_disk == -1)
             return -EEXIST;
         /* personality does all needed checks */
         if (rdev->mddev->pers->hot_remove_disk == NULL)
             return -EINVAL;
         clear_bit(Blocked, &rdev->flags);
         remove_and_add_spares(rdev->mddev, rdev);
         if (rdev->raid_disk >= 0)
             return -EBUSY;
         set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
         md_wakeup_thread(rdev->mddev->thread);
     } else if (rdev->mddev->pers) {
         /* Activating a spare .. or possibly reactivating
          * if we ever get bitmaps working here.
          */
         int err;
 
         if (rdev->raid_disk != -1)
             return -EBUSY;
 
         if (test_bit(MD_RECOVERY_RUNNING, &rdev->mddev->recovery))
             return -EBUSY;
 
         if (rdev->mddev->pers->hot_add_disk == NULL)
             return -EINVAL;
 
         if (slot >= rdev->mddev->raid_disks &&
             slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
             return -ENOSPC;
 
         rdev->raid_disk = slot;
         if (test_bit(In_sync, &rdev->flags))
             rdev->saved_raid_disk = slot;
         else
             rdev->saved_raid_disk = -1;
         clear_bit(In_sync, &rdev->flags);
         clear_bit(Bitmap_sync, &rdev->flags);
         err = rdev->mddev->pers->hot_add_disk(rdev->mddev, rdev);
         if (err) {
             rdev->raid_disk = -1;
             return err;
         } else
             sysfs_notify_dirent_safe(rdev->sysfs_state);
         /* failure here is OK */;
         sysfs_link_rdev(rdev->mddev, rdev);
         /* don't wakeup anyone, leave that to userspace. */
     } else {
         if (slot >= rdev->mddev->raid_disks &&
             slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
             return -ENOSPC;
         rdev->raid_disk = slot;
         /* assume it is working */
         clear_bit(Faulty, &rdev->flags);
         clear_bit(WriteMostly, &rdev->flags);
         set_bit(In_sync, &rdev->flags);
         sysfs_notify_dirent_safe(rdev->sysfs_state);
     }
     return len;
 }
 
 static struct rdev_sysfs_entry rdev_slot =
 __ATTR(slot, S_IRUGO|S_IWUSR, slot_show, slot_store);
 
 static ssize_t
 offset_show(struct md_rdev *rdev, char *page)
 {
     return sprintf(page, "%llu\n", (unsigned long long)rdev->data_offset);
 }
 
 static ssize_t
 offset_store(struct md_rdev *rdev, const char *buf, size_t len)
 {
     unsigned long long offset;
     if (kstrtoull(buf, 10, &offset) < 0)
         return -EINVAL;
     if (rdev->mddev->pers && rdev->raid_disk >= 0)
         return -EBUSY;
     if (rdev->sectors && rdev->mddev->external)
         /* Must set offset before size, so overlap checks
          * can be sane */
         return -EBUSY;
     rdev->data_offset = offset;
     rdev->new_data_offset = offset;
     return len;
 }
 
 static struct rdev_sysfs_entry rdev_offset =
 __ATTR(offset, S_IRUGO|S_IWUSR, offset_show, offset_store);
 
 static ssize_t new_offset_show(struct md_rdev *rdev, char *page)
 {
     return sprintf(page, "%llu\n",
                (unsigned long long)rdev->new_data_offset);
 }
 
 static ssize_t new_offset_store(struct md_rdev *rdev,
                 const char *buf, size_t len)
 {
     unsigned long long new_offset;
     struct mddev *mddev = rdev->mddev;
 
     if (kstrtoull(buf, 10, &new_offset) < 0)
         return -EINVAL;
 
     if (mddev->sync_thread ||
         test_bit(MD_RECOVERY_RUNNING,&mddev->recovery))
         return -EBUSY;
     if (new_offset == rdev->data_offset)
         /* reset is always permitted */
         ;
     else if (new_offset > rdev->data_offset) {
         /* must not push array size beyond rdev_sectors */
         if (new_offset - rdev->data_offset
             + mddev->dev_sectors > rdev->sectors)
                 return -E2BIG;
     }
     /* Metadata worries about other space details. */
 
     /* decreasing the offset is inconsistent with a backwards
      * reshape.
      */
     if (new_offset < rdev->data_offset &&
         mddev->reshape_backwards)
         return -EINVAL;
     /* Increasing offset is inconsistent with forwards
      * reshape.  reshape_direction should be set to
      * 'backwards' first.
      */
     if (new_offset > rdev->data_offset &&
         !mddev->reshape_backwards)
         return -EINVAL;
 
     if (mddev->pers && mddev->persistent &&
         !super_types[mddev->major_version]
         .allow_new_offset(rdev, new_offset))
         return -E2BIG;
     rdev->new_data_offset = new_offset;
     if (new_offset > rdev->data_offset)
         mddev->reshape_backwards = 1;
     else if (new_offset < rdev->data_offset)
         mddev->reshape_backwards = 0;
 
     return len;
 }
 static struct rdev_sysfs_entry rdev_new_offset =
 __ATTR(new_offset, S_IRUGO|S_IWUSR, new_offset_show, new_offset_store);
 
 static ssize_t
 rdev_size_show(struct md_rdev *rdev, char *page)
 {
     return sprintf(page, "%llu\n", (unsigned long long)rdev->sectors / 2);
 }
 
 static int md_rdevs_overlap(struct md_rdev *a, struct md_rdev *b)
 {
     /* check if two start/length pairs overlap */
     if (a->data_offset + a->sectors <= b->data_offset)
         return false;
     if (b->data_offset + b->sectors <= a->data_offset)
         return false;
     return true;
 }
 
 static bool md_rdev_overlaps(struct md_rdev *rdev)
 {
     struct mddev *mddev;
     struct md_rdev *rdev2;
 
     spin_lock(&all_mddevs_lock);
     list_for_each_entry(mddev, &all_mddevs, all_mddevs) {
         if (test_bit(MD_DELETED, &mddev->flags))
             continue;
         rdev_for_each(rdev2, mddev) {
             if (rdev != rdev2 && rdev->bdev == rdev2->bdev &&
                 md_rdevs_overlap(rdev, rdev2)) {
                 spin_unlock(&all_mddevs_lock);
                 return true;
             }
         }
     }
     spin_unlock(&all_mddevs_lock);
     return false;
 }
 
 static int strict_blocks_to_sectors(const char *buf, sector_t *sectors)
 {
     unsigned long long blocks;
     sector_t new;
 
     if (kstrtoull(buf, 10, &blocks) < 0)
         return -EINVAL;
 
     if (blocks & 1ULL << (8 * sizeof(blocks) - 1))
         return -EINVAL; /* sector conversion overflow */
 
     new = blocks * 2;
     if (new != blocks * 2)
         return -EINVAL; /* unsigned long long to sector_t overflow */
 
     *sectors = new;
     return 0;
 }
 
 static ssize_t
 rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len)
 {
     struct mddev *my_mddev = rdev->mddev;
     sector_t oldsectors = rdev->sectors;
     sector_t sectors;
 
     if (test_bit(Journal, &rdev->flags))
         return -EBUSY;
     if (strict_blocks_to_sectors(buf, &sectors) < 0)
         return -EINVAL;
     if (rdev->data_offset != rdev->new_data_offset)
         return -EINVAL; /* too confusing */
     if (my_mddev->pers && rdev->raid_disk >= 0) {
         if (my_mddev->persistent) {
             sectors = super_types[my_mddev->major_version].
                 rdev_size_change(rdev, sectors);
             if (!sectors)
                 return -EBUSY;
         } else if (!sectors)
             sectors = bdev_nr_sectors(rdev->bdev) -
                 rdev->data_offset;
         if (!my_mddev->pers->resize)
             /* Cannot change size for RAID0 or Linear etc */
             return -EINVAL;
     }
     if (sectors < my_mddev->dev_sectors)
         return -EINVAL; /* component must fit device */
 
     rdev->sectors = sectors;
 
     /*
      * Check that all other rdevs with the same bdev do not overlap.  This
      * check does not provide a hard guarantee, it just helps avoid
      * dangerous mistakes.
      */
     if (sectors > oldsectors && my_mddev->external &&
         md_rdev_overlaps(rdev)) {
         /*
          * Someone else could have slipped in a size change here, but
          * doing so is just silly.  We put oldsectors back because we
          * know it is safe, and trust userspace not to race with itself.
          */
         rdev->sectors = oldsectors;
         return -EBUSY;
     }
     return len;
 }
 
 static struct rdev_sysfs_entry rdev_size =
 __ATTR(size, S_IRUGO|S_IWUSR, rdev_size_show, rdev_size_store);
 
 static ssize_t recovery_start_show(struct md_rdev *rdev, char *page)
 {
     unsigned long long recovery_start = rdev->recovery_offset;
 
     if (test_bit(In_sync, &rdev->flags) ||
         recovery_start == MaxSector)
         return sprintf(page, "none\n");
 
     return sprintf(page, "%llu\n", recovery_start);
 }
 
 static ssize_t recovery_start_store(struct md_rdev *rdev, const char *buf, size_t len)
 {
     unsigned long long recovery_start;
 
     if (cmd_match(buf, "none"))
         recovery_start = MaxSector;
     else if (kstrtoull(buf, 10, &recovery_start))
         return -EINVAL;
 
     if (rdev->mddev->pers &&
         rdev->raid_disk >= 0)
         return -EBUSY;
 
     rdev->recovery_offset = recovery_start;
     if (recovery_start == MaxSector)
         set_bit(In_sync, &rdev->flags);
     else
         clear_bit(In_sync, &rdev->flags);
     return len;
 }
 
 static struct rdev_sysfs_entry rdev_recovery_start =
 __ATTR(recovery_start, S_IRUGO|S_IWUSR, recovery_start_show, recovery_start_store);
 
 /* sysfs access to bad-blocks list.
  * We present two files.
  * 'bad-blocks' lists sector numbers and lengths of ranges that
  *    are recorded as bad.  The list is truncated to fit within
  *    the one-page limit of sysfs.
  *    Writing "sector length" to this file adds an acknowledged
  *    bad block list.
  * 'unacknowledged-bad-blocks' lists bad blocks that have not yet
  *    been acknowledged.  Writing to this file adds bad blocks
  *    without acknowledging them.  This is largely for testing.
  */
 static ssize_t bb_show(struct md_rdev *rdev, char *page)
 {
     return badblocks_show(&rdev->badblocks, page, 0);
 }
 static ssize_t bb_store(struct md_rdev *rdev, const char *page, size_t len)
 {
     int rv = badblocks_store(&rdev->badblocks, page, len, 0);
     /* Maybe that ack was all we needed */
     if (test_and_clear_bit(BlockedBadBlocks, &rdev->flags))
         wake_up(&rdev->blocked_wait);
     return rv;
 }
 static struct rdev_sysfs_entry rdev_bad_blocks =
 __ATTR(bad_blocks, S_IRUGO|S_IWUSR, bb_show, bb_store);
 
 static ssize_t ubb_show(struct md_rdev *rdev, char *page)
 {
     return badblocks_show(&rdev->badblocks, page, 1);
 }
 static ssize_t ubb_store(struct md_rdev *rdev, const char *page, size_t len)
 {
     return badblocks_store(&rdev->badblocks, page, len, 1);
 }
 static struct rdev_sysfs_entry rdev_unack_bad_blocks =
 __ATTR(unacknowledged_bad_blocks, S_IRUGO|S_IWUSR, ubb_show, ubb_store);
 
 static ssize_t
 ppl_sector_show(struct md_rdev *rdev, char *page)
 {
     return sprintf(page, "%llu\n", (unsigned long long)rdev->ppl.sector);
 }
 
 static ssize_t
 ppl_sector_store(struct md_rdev *rdev, const char *buf, size_t len)
 {
     unsigned long long sector;
 
     if (kstrtoull(buf, 10, &sector) < 0)
         return -EINVAL;
     if (sector != (sector_t)sector)
         return -EINVAL;
 
     if (rdev->mddev->pers && test_bit(MD_HAS_PPL, &rdev->mddev->flags) &&
         rdev->raid_disk >= 0)
         return -EBUSY;
 
     if (rdev->mddev->persistent) {
         if (rdev->mddev->major_version == 0)
             return -EINVAL;
         if ((sector > rdev->sb_start &&
              sector - rdev->sb_start > S16_MAX) ||
             (sector < rdev->sb_start &&
              rdev->sb_start - sector > -S16_MIN))
             return -EINVAL;
         rdev->ppl.offset = sector - rdev->sb_start;
     } else if (!rdev->mddev->external) {
         return -EBUSY;
     }
     rdev->ppl.sector = sector;
     return len;
 }
 
 static struct rdev_sysfs_entry rdev_ppl_sector =
 __ATTR(ppl_sector, S_IRUGO|S_IWUSR, ppl_sector_show, ppl_sector_store);
 
 static ssize_t
 ppl_size_show(struct md_rdev *rdev, char *page)
 {
     return sprintf(page, "%u\n", rdev->ppl.size);
 }
 
 static ssize_t
 ppl_size_store(struct md_rdev *rdev, const char *buf, size_t len)
 {
     unsigned int size;
 
     if (kstrtouint(buf, 10, &size) < 0)
         return -EINVAL;
 
     if (rdev->mddev->pers && test_bit(MD_HAS_PPL, &rdev->mddev->flags) &&
         rdev->raid_disk >= 0)
         return -EBUSY;
 
     if (rdev->mddev->persistent) {
         if (rdev->mddev->major_version == 0)
             return -EINVAL;
         if (size > U16_MAX)
             return -EINVAL;
     } else if (!rdev->mddev->external) {
         return -EBUSY;
     }
     rdev->ppl.size = size;
     return len;
 }
 
 static struct rdev_sysfs_entry rdev_ppl_size =
 __ATTR(ppl_size, S_IRUGO|S_IWUSR, ppl_size_show, ppl_size_store);
 
 static struct attribute *rdev_default_attrs[] = {
     &rdev_state.attr,
     &rdev_errors.attr,
     &rdev_slot.attr,
     &rdev_offset.attr,
     &rdev_new_offset.attr,
     &rdev_size.attr,
     &rdev_recovery_start.attr,
     &rdev_bad_blocks.attr,
     &rdev_unack_bad_blocks.attr,
     &rdev_ppl_sector.attr,
     &rdev_ppl_size.attr,
     NULL,
 };
 ATTRIBUTE_GROUPS(rdev_default);
 static ssize_t
 rdev_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 {
     struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
     struct md_rdev *rdev = container_of(kobj, struct md_rdev, kobj);
 
     if (!entry->show)
         return -EIO;
     if (!rdev->mddev)
         return -ENODEV;
     return entry->show(rdev, page);
 }
 
 static ssize_t
 rdev_attr_store(struct kobject *kobj, struct attribute *attr,
           const char *page, size_t length)
 {
     struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
     struct md_rdev *rdev = container_of(kobj, struct md_rdev, kobj);
     ssize_t rv;
     struct mddev *mddev = rdev->mddev;
 
     if (!entry->store)
         return -EIO;
     if (!capable(CAP_SYS_ADMIN))
         return -EACCES;
     rv = mddev ? mddev_lock(mddev) : -ENODEV;
     if (!rv) {
         if (rdev->mddev == NULL)
             rv = -ENODEV;
         else
             rv = entry->store(rdev, page, length);
         mddev_unlock(mddev);
     }
     return rv;
 }
 
 static void rdev_free(struct kobject *ko)
 {
     struct md_rdev *rdev = container_of(ko, struct md_rdev, kobj);
     kfree(rdev);
 }
 static const struct sysfs_ops rdev_sysfs_ops = {
     .show       = rdev_attr_show,
     .store      = rdev_attr_store,
 };
 static struct kobj_type rdev_ktype = {
     .release    = rdev_free,
     .sysfs_ops  = &rdev_sysfs_ops,
     .default_groups = rdev_default_groups,
 };
 
 int md_rdev_init(struct md_rdev *rdev)
 {
     rdev->desc_nr = -1;
     rdev->saved_raid_disk = -1;
     rdev->raid_disk = -1;
     rdev->flags = 0;
     rdev->data_offset = 0;
     rdev->new_data_offset = 0;
     rdev->sb_events = 0;
     rdev->last_read_error = 0;
     rdev->sb_loaded = 0;
     rdev->bb_page = NULL;
     atomic_set(&rdev->nr_pending, 0);
     atomic_set(&rdev->read_errors, 0);
     atomic_set(&rdev->corrected_errors, 0);
 
     INIT_LIST_HEAD(&rdev->same_set);
     init_waitqueue_head(&rdev->blocked_wait);
 
     /* Add space to store bad block list.
      * This reserves the space even on arrays where it cannot
      * be used - I wonder if that matters
      */
     return badblocks_init(&rdev->badblocks, 0);
 }
 EXPORT_SYMBOL_GPL(md_rdev_init);
 /*
  * Import a device. If 'super_format' >= 0, then sanity check the superblock
  *
  * mark the device faulty if:
  *
  *   - the device is nonexistent (zero size)
  *   - the device has no valid superblock
  *
  * a faulty rdev _never_ has rdev->sb set.
  */
 static struct md_rdev *md_import_device(dev_t newdev, int super_format, int super_minor)
 {
     int err;
     struct md_rdev *rdev;
     sector_t size;
 
     rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
     if (!rdev)
         return ERR_PTR(-ENOMEM);
 
     err = md_rdev_init(rdev);
     if (err)
         goto abort_free;
     err = alloc_disk_sb(rdev);
     if (err)
         goto abort_free;
 
     err = lock_rdev(rdev, newdev, super_format == -2);
     if (err)
         goto abort_free;
 
     kobject_init(&rdev->kobj, &rdev_ktype);
 
     size = bdev_nr_bytes(rdev->bdev) >> BLOCK_SIZE_BITS;
     if (!size) {
         pr_warn("md: %pg has zero or unknown size, marking faulty!\n",
             rdev->bdev);
         err = -EINVAL;
         goto abort_free;
     }
 
     if (super_format >= 0) {
         err = super_types[super_format].
             load_super(rdev, NULL, super_minor);
         if (err == -EINVAL) {
             pr_warn("md: %pg does not have a valid v%d.%d superblock, not importing!\n",
                 rdev->bdev,
                 super_format, super_minor);
             goto abort_free;
         }
         if (err < 0) {
             pr_warn("md: could not read %pg's sb, not importing!\n",
                 rdev->bdev);
             goto abort_free;
         }
     }
 
     return rdev;
 
 abort_free:
     if (rdev->bdev)
         unlock_rdev(rdev);
     md_rdev_clear(rdev);
     kfree(rdev);
     return ERR_PTR(err);
 }
 
 /*
  * Check a full RAID array for plausibility
  */
 
 static int analyze_sbs(struct mddev *mddev)
 {
     int i;
     struct md_rdev *rdev, *freshest, *tmp;
 
     freshest = NULL;
     rdev_for_each_safe(rdev, tmp, mddev)
         switch (super_types[mddev->major_version].
             load_super(rdev, freshest, mddev->minor_version)) {
         case 1:
             freshest = rdev;
             break;
         case 0:
             break;
         default:
             pr_warn("md: fatal superblock inconsistency in %pg -- removing from array\n",
                 rdev->bdev);
             md_kick_rdev_from_array(rdev);
         }
 
     /* Cannot find a valid fresh disk */
     if (!freshest) {
         pr_warn("md: cannot find a valid disk\n");
         return -EINVAL;
     }
 
     super_types[mddev->major_version].
         validate_super(mddev, freshest);
 
     i = 0;
     rdev_for_each_safe(rdev, tmp, mddev) {
         if (mddev->max_disks &&
             (rdev->desc_nr >= mddev->max_disks ||
              i > mddev->max_disks)) {
             pr_warn("md: %s: %pg: only %d devices permitted\n",
                 mdname(mddev), rdev->bdev,
                 mddev->max_disks);
             md_kick_rdev_from_array(rdev);
             continue;
         }
         if (rdev != freshest) {
             if (super_types[mddev->major_version].
                 validate_super(mddev, rdev)) {
                 pr_warn("md: kicking non-fresh %pg from array!\n",
                     rdev->bdev);
                 md_kick_rdev_from_array(rdev);
                 continue;
             }
         }
         if (mddev->level == LEVEL_MULTIPATH) {
             rdev->desc_nr = i++;
             rdev->raid_disk = rdev->desc_nr;
             set_bit(In_sync, &rdev->flags);
         } else if (rdev->raid_disk >=
                 (mddev->raid_disks - min(0, mddev->delta_disks)) &&
                !test_bit(Journal, &rdev->flags)) {
             rdev->raid_disk = -1;
             clear_bit(In_sync, &rdev->flags);
         }
     }
 
     return 0;
 }
 
 /* Read a fixed-point number.
  * Numbers in sysfs attributes should be in "standard" units where
  * possible, so time should be in seconds.
  * However we internally use a a much smaller unit such as
  * milliseconds or jiffies.
  * This function takes a decimal number with a possible fractional
  * component, and produces an integer which is the result of
  * multiplying that number by 10^'scale'.
  * all without any floating-point arithmetic.
  */
 int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale)
 {
     unsigned long result = 0;
     long decimals = -1;
     while (isdigit(*cp) || (*cp == '.' && decimals < 0)) {
         if (*cp == '.')
             decimals = 0;
         else if (decimals < scale) {
             unsigned int value;
             value = *cp - '0';
             result = result * 10 + value;
             if (decimals >= 0)
                 decimals++;
         }
         cp++;
     }
     if (*cp == '\n')
         cp++;
     if (*cp)
         return -EINVAL;
     if (decimals < 0)
         decimals = 0;
     *res = result * int_pow(10, scale - decimals);
     return 0;
 }
 
 static ssize_t
 safe_delay_show(struct mddev *mddev, char *page)
 {
     int msec = (mddev->safemode_delay*1000)/HZ;
     return sprintf(page, "%d.%03d\n", msec/1000, msec%1000);
 }
 static ssize_t
 safe_delay_store(struct mddev *mddev, const char *cbuf, size_t len)
 {
     unsigned long msec;
 
     if (mddev_is_clustered(mddev)) {
         pr_warn("md: Safemode is disabled for clustered mode\n");
         return -EINVAL;
     }
 
     if (strict_strtoul_scaled(cbuf, &msec, 3) < 0)
         return -EINVAL;
     if (msec == 0)
         mddev->safemode_delay = 0;
     else {
         unsigned long old_delay = mddev->safemode_delay;
         unsigned long new_delay = (msec*HZ)/1000;
 
         if (new_delay == 0)
             new_delay = 1;
         mddev->safemode_delay = new_delay;
         if (new_delay < old_delay || old_delay == 0)
             mod_timer(&mddev->safemode_timer, jiffies+1);
     }
     return len;
 }
 static struct md_sysfs_entry md_safe_delay =
 __ATTR(safe_mode_delay, S_IRUGO|S_IWUSR,safe_delay_show, safe_delay_store);
 
 static ssize_t
 level_show(struct mddev *mddev, char *page)
 {
     struct md_personality *p;
     int ret;
     spin_lock(&mddev->lock);
     p = mddev->pers;
     if (p)
         ret = sprintf(page, "%s\n", p->name);
     else if (mddev->clevel[0])
         ret = sprintf(page, "%s\n", mddev->clevel);
     else if (mddev->level != LEVEL_NONE)
         ret = sprintf(page, "%d\n", mddev->level);
     else
         ret = 0;
     spin_unlock(&mddev->lock);
     return ret;
 }
 
 static ssize_t
 level_store(struct mddev *mddev, const char *buf, size_t len)
 {
     char clevel[16];
     ssize_t rv;
     size_t slen = len;
     struct md_personality *pers, *oldpers;
     long level;
     void *priv, *oldpriv;
     struct md_rdev *rdev;
 
     if (slen == 0 || slen >= sizeof(clevel))
         return -EINVAL;
 
     rv = mddev_lock(mddev);
     if (rv)
         return rv;
 
     if (mddev->pers == NULL) {
         strncpy(mddev->clevel, buf, slen);
         if (mddev->clevel[slen-1] == '\n')
             slen--;
         mddev->clevel[slen] = 0;
         mddev->level = LEVEL_NONE;
         rv = len;
         goto out_unlock;
     }
     rv = -EROFS;
     if (mddev->ro)
         goto out_unlock;
 
     /* request to change the personality.  Need to ensure:
      *  - array is not engaged in resync/recovery/reshape
      *  - old personality can be suspended
      *  - new personality will access other array.
      */
 
     rv = -EBUSY;
     if (mddev->sync_thread ||
         test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
         mddev->reshape_position != MaxSector ||
         mddev->sysfs_active)
         goto out_unlock;
 
     rv = -EINVAL;
     if (!mddev->pers->quiesce) {
         pr_warn("md: %s: %s does not support online personality change\n",
             mdname(mddev), mddev->pers->name);
         goto out_unlock;
     }
 
     /* Now find the new personality */
     strncpy(clevel, buf, slen);
     if (clevel[slen-1] == '\n')
         slen--;
     clevel[slen] = 0;
     if (kstrtol(clevel, 10, &level))
         level = LEVEL_NONE;
 
     if (request_module("md-%s", clevel) != 0)
         request_module("md-level-%s", clevel);
     spin_lock(&pers_lock);
     pers = find_pers(level, clevel);
     if (!pers || !try_module_get(pers->owner)) {
         spin_unlock(&pers_lock);
         pr_warn("md: personality %s not loaded\n", clevel);
         rv = -EINVAL;
         goto out_unlock;
     }
     spin_unlock(&pers_lock);
 
     if (pers == mddev->pers) {
         /* Nothing to do! */
         module_put(pers->owner);
         rv = len;
         goto out_unlock;
     }
     if (!pers->takeover) {
         module_put(pers->owner);
         pr_warn("md: %s: %s does not support personality takeover\n",
             mdname(mddev), clevel);
         rv = -EINVAL;
         goto out_unlock;
     }
 
     rdev_for_each(rdev, mddev)
         rdev->new_raid_disk = rdev->raid_disk;
 
     /* ->takeover must set new_* and/or delta_disks
      * if it succeeds, and may set them when it fails.
      */
     priv = pers->takeover(mddev);
     if (IS_ERR(priv)) {
         mddev->new_level = mddev->level;
         mddev->new_layout = mddev->layout;
         mddev->new_chunk_sectors = mddev->chunk_sectors;
         mddev->raid_disks -= mddev->delta_disks;
         mddev->delta_disks = 0;
         mddev->reshape_backwards = 0;
         module_put(pers->owner);
         pr_warn("md: %s: %s would not accept array\n",
             mdname(mddev), clevel);
         rv = PTR_ERR(priv);
         goto out_unlock;
     }
 
     /* Looks like we have a winner */
     mddev_suspend(mddev);
     mddev_detach(mddev);
 
     spin_lock(&mddev->lock);
     oldpers = mddev->pers;
     oldpriv = mddev->private;
     mddev->pers = pers;
     mddev->private = priv;
     strscpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
     mddev->level = mddev->new_level;
     mddev->layout = mddev->new_layout;
     mddev->chunk_sectors = mddev->new_chunk_sectors;
     mddev->delta_disks = 0;
     mddev->reshape_backwards = 0;
     mddev->degraded = 0;
     spin_unlock(&mddev->lock);
 
     if (oldpers->sync_request == NULL &&
         mddev->external) {
         /* We are converting from a no-redundancy array
          * to a redundancy array and metadata is managed
          * externally so we need to be sure that writes
          * won't block due to a need to transition
          *      clean->dirty
          * until external management is started.
          */
         mddev->in_sync = 0;
         mddev->safemode_delay = 0;
         mddev->safemode = 0;
     }
 
     oldpers->free(mddev, oldpriv);
 
     if (oldpers->sync_request == NULL &&
         pers->sync_request != NULL) {
         /* need to add the md_redundancy_group */
         if (sysfs_create_group(&mddev->kobj, &md_redundancy_group))
             pr_warn("md: cannot register extra attributes for %s\n",
                 mdname(mddev));
         mddev->sysfs_action = sysfs_get_dirent(mddev->kobj.sd, "sync_action");
         mddev->sysfs_completed = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_completed");
         mddev->sysfs_degraded = sysfs_get_dirent_safe(mddev->kobj.sd, "degraded");
     }
     if (oldpers->sync_request != NULL &&
         pers->sync_request == NULL) {
         /* need to remove the md_redundancy_group */
         if (mddev->to_remove == NULL)
             mddev->to_remove = &md_redundancy_group;
     }
 
     module_put(oldpers->owner);
 
     rdev_for_each(rdev, mddev) {
         if (rdev->raid_disk < 0)
             continue;
         if (rdev->new_raid_disk >= mddev->raid_disks)
             rdev->new_raid_disk = -1;
         if (rdev->new_raid_disk == rdev->raid_disk)
             continue;
         sysfs_unlink_rdev(mddev, rdev);
     }
     rdev_for_each(rdev, mddev) {
         if (rdev->raid_disk < 0)
             continue;
         if (rdev->new_raid_disk == rdev->raid_disk)
             continue;
         rdev->raid_disk = rdev->new_raid_disk;
         if (rdev->raid_disk < 0)
             clear_bit(In_sync, &rdev->flags);
         else {
             if (sysfs_link_rdev(mddev, rdev))
                 pr_warn("md: cannot register rd%d for %s after level change\n",
                     rdev->raid_disk, mdname(mddev));
         }
     }
 
     if (pers->sync_request == NULL) {
         /* this is now an array without redundancy, so
          * it must always be in_sync
          */
         mddev->in_sync = 1;
         del_timer_sync(&mddev->safemode_timer);
     }
     blk_set_stacking_limits(&mddev->queue->limits);
     pers->run(mddev);
     set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
     mddev_resume(mddev);
     if (!mddev->thread)
         md_update_sb(mddev, 1);
     sysfs_notify_dirent_safe(mddev->sysfs_level);
     md_new_event();
     rv = len;
 out_unlock:
     mddev_unlock(mddev);
     return rv;
 }
 
 static struct md_sysfs_entry md_level =
 __ATTR(level, S_IRUGO|S_IWUSR, level_show, level_store);
 
 static ssize_t
 layout_show(struct mddev *mddev, char *page)
 {
     /* just a number, not meaningful for all levels */
     if (mddev->reshape_position != MaxSector &&
         mddev->layout != mddev->new_layout)
         return sprintf(page, "%d (%d)\n",
                    mddev->new_layout, mddev->layout);
     return sprintf(page, "%d\n", mddev->layout);
 }
 
 static ssize_t
 layout_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned int n;
     int err;
 
     err = kstrtouint(buf, 10, &n);
     if (err < 0)
         return err;
     err = mddev_lock(mddev);
     if (err)
         return err;
 
     if (mddev->pers) {
         if (mddev->pers->check_reshape == NULL)
             err = -EBUSY;
         else if (mddev->ro)
             err = -EROFS;
         else {
             mddev->new_layout = n;
             err = mddev->pers->check_reshape(mddev);
             if (err)
                 mddev->new_layout = mddev->layout;
         }
     } else {
         mddev->new_layout = n;
         if (mddev->reshape_position == MaxSector)
             mddev->layout = n;
     }
     mddev_unlock(mddev);
     return err ?: len;
 }
 static struct md_sysfs_entry md_layout =
 __ATTR(layout, S_IRUGO|S_IWUSR, layout_show, layout_store);
 
 static ssize_t
 raid_disks_show(struct mddev *mddev, char *page)
 {
     if (mddev->raid_disks == 0)
         return 0;
     if (mddev->reshape_position != MaxSector &&
         mddev->delta_disks != 0)
         return sprintf(page, "%d (%d)\n", mddev->raid_disks,
                    mddev->raid_disks - mddev->delta_disks);
     return sprintf(page, "%d\n", mddev->raid_disks);
 }
 
 static int update_raid_disks(struct mddev *mddev, int raid_disks);
 
 static ssize_t
 raid_disks_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned int n;
     int err;
 
     err = kstrtouint(buf, 10, &n);
     if (err < 0)
         return err;
 
     err = mddev_lock(mddev);
     if (err)
         return err;
     if (mddev->pers)
         err = update_raid_disks(mddev, n);
     else if (mddev->reshape_position != MaxSector) {
         struct md_rdev *rdev;
         int olddisks = mddev->raid_disks - mddev->delta_disks;
 
         err = -EINVAL;
         rdev_for_each(rdev, mddev) {
             if (olddisks < n &&
                 rdev->data_offset < rdev->new_data_offset)
                 goto out_unlock;
             if (olddisks > n &&
                 rdev->data_offset > rdev->new_data_offset)
                 goto out_unlock;
         }
         err = 0;
         mddev->delta_disks = n - olddisks;
         mddev->raid_disks = n;
         mddev->reshape_backwards = (mddev->delta_disks < 0);
     } else
         mddev->raid_disks = n;
 out_unlock:
     mddev_unlock(mddev);
     return err ? err : len;
 }
 static struct md_sysfs_entry md_raid_disks =
 __ATTR(raid_disks, S_IRUGO|S_IWUSR, raid_disks_show, raid_disks_store);
 
 static ssize_t
 uuid_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%pU\n", mddev->uuid);
 }
 static struct md_sysfs_entry md_uuid =
 __ATTR(uuid, S_IRUGO, uuid_show, NULL);
 
 static ssize_t
 chunk_size_show(struct mddev *mddev, char *page)
 {
     if (mddev->reshape_position != MaxSector &&
         mddev->chunk_sectors != mddev->new_chunk_sectors)
         return sprintf(page, "%d (%d)\n",
                    mddev->new_chunk_sectors << 9,
                    mddev->chunk_sectors << 9);
     return sprintf(page, "%d\n", mddev->chunk_sectors << 9);
 }
 
 static ssize_t
 chunk_size_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned long n;
     int err;
 
     err = kstrtoul(buf, 10, &n);
     if (err < 0)
         return err;
 
     err = mddev_lock(mddev);
     if (err)
         return err;
     if (mddev->pers) {
         if (mddev->pers->check_reshape == NULL)
             err = -EBUSY;
         else if (mddev->ro)
             err = -EROFS;
         else {
             mddev->new_chunk_sectors = n >> 9;
             err = mddev->pers->check_reshape(mddev);
             if (err)
                 mddev->new_chunk_sectors = mddev->chunk_sectors;
         }
     } else {
         mddev->new_chunk_sectors = n >> 9;
         if (mddev->reshape_position == MaxSector)
             mddev->chunk_sectors = n >> 9;
     }
     mddev_unlock(mddev);
     return err ?: len;
 }
 static struct md_sysfs_entry md_chunk_size =
 __ATTR(chunk_size, S_IRUGO|S_IWUSR, chunk_size_show, chunk_size_store);
 
 static ssize_t
 resync_start_show(struct mddev *mddev, char *page)
 {
     if (mddev->recovery_cp == MaxSector)
         return sprintf(page, "none\n");
     return sprintf(page, "%llu\n", (unsigned long long)mddev->recovery_cp);
 }
 
 static ssize_t
 resync_start_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned long long n;
     int err;
 
     if (cmd_match(buf, "none"))
         n = MaxSector;
     else {
         err = kstrtoull(buf, 10, &n);
         if (err < 0)
             return err;
         if (n != (sector_t)n)
             return -EINVAL;
     }
 
     err = mddev_lock(mddev);
     if (err)
         return err;
     if (mddev->pers && !test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
         err = -EBUSY;
 
     if (!err) {
         mddev->recovery_cp = n;
         if (mddev->pers)
             set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
     }
     mddev_unlock(mddev);
     return err ?: len;
 }
 static struct md_sysfs_entry md_resync_start =
 __ATTR_PREALLOC(resync_start, S_IRUGO|S_IWUSR,
         resync_start_show, resync_start_store);
 
 /*
  * The array state can be:
  *
  * clear
  *     No devices, no size, no level
  *     Equivalent to STOP_ARRAY ioctl
  * inactive
  *     May have some settings, but array is not active
  *        all IO results in error
  *     When written, doesn't tear down array, but just stops it
  * suspended (not supported yet)
  *     All IO requests will block. The array can be reconfigured.
  *     Writing this, if accepted, will block until array is quiescent
  * readonly
  *     no resync can happen.  no superblocks get written.
  *     write requests fail
  * read-auto
  *     like readonly, but behaves like 'clean' on a write request.
  *
  * clean - no pending writes, but otherwise active.
  *     When written to inactive array, starts without resync
  *     If a write request arrives then
  *       if metadata is known, mark 'dirty' and switch to 'active'.
  *       if not known, block and switch to write-pending
  *     If written to an active array that has pending writes, then fails.
  * active
  *     fully active: IO and resync can be happening.
  *     When written to inactive array, starts with resync
  *
  * write-pending
  *     clean, but writes are blocked waiting for 'active' to be written.
  *
  * active-idle
  *     like active, but no writes have been seen for a while (100msec).
  *
  * broken
 *     Array is failed. It's useful because mounted-arrays aren't stopped
 *     when array is failed, so this state will at least alert the user that
 *     something is wrong.
  */
 enum array_state { clear, inactive, suspended, readonly, read_auto, clean, active,
            write_pending, active_idle, broken, bad_word};
 static char *array_states[] = {
     "clear", "inactive", "suspended", "readonly", "read-auto", "clean", "active",
     "write-pending", "active-idle", "broken", NULL };
 
 static int match_word(const char *word, char **list)
 {
     int n;
     for (n=0; list[n]; n++)
         if (cmd_match(word, list[n]))
             break;
     return n;
 }
 
 static ssize_t
 array_state_show(struct mddev *mddev, char *page)
 {
     enum array_state st = inactive;
 
     if (mddev->pers && !test_bit(MD_NOT_READY, &mddev->flags)) {
         switch(mddev->ro) {
         case 1:
             st = readonly;
             break;
         case 2:
             st = read_auto;
             break;
         case 0:
             spin_lock(&mddev->lock);
             if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags))
                 st = write_pending;
             else if (mddev->in_sync)
                 st = clean;
             else if (mddev->safemode)
                 st = active_idle;
             else
                 st = active;
             spin_unlock(&mddev->lock);
         }
 
         if (test_bit(MD_BROKEN, &mddev->flags) && st == clean)
             st = broken;
     } else {
         if (list_empty(&mddev->disks) &&
             mddev->raid_disks == 0 &&
             mddev->dev_sectors == 0)
             st = clear;
         else
             st = inactive;
     }
     return sprintf(page, "%s\n", array_states[st]);
 }
 
 static int do_md_stop(struct mddev *mddev, int ro, struct block_device *bdev);
 static int md_set_readonly(struct mddev *mddev, struct block_device *bdev);
 static int restart_array(struct mddev *mddev);
 
 static ssize_t
 array_state_store(struct mddev *mddev, const char *buf, size_t len)
 {
     int err = 0;
     enum array_state st = match_word(buf, array_states);
 
     if (mddev->pers && (st == active || st == clean) && mddev->ro != 1) {
         /* don't take reconfig_mutex when toggling between
          * clean and active
          */
         spin_lock(&mddev->lock);
         if (st == active) {
             restart_array(mddev);
             clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
             md_wakeup_thread(mddev->thread);
             wake_up(&mddev->sb_wait);
         } else /* st == clean */ {
             restart_array(mddev);
             if (!set_in_sync(mddev))
                 err = -EBUSY;
         }
         if (!err)
             sysfs_notify_dirent_safe(mddev->sysfs_state);
         spin_unlock(&mddev->lock);
         return err ?: len;
     }
     err = mddev_lock(mddev);
     if (err)
         return err;
     err = -EINVAL;
     switch(st) {
     case bad_word:
         break;
     case clear:
         /* stopping an active array */
         err = do_md_stop(mddev, 0, NULL);
         break;
     case inactive:
         /* stopping an active array */
         if (mddev->pers)
             err = do_md_stop(mddev, 2, NULL);
         else
             err = 0; /* already inactive */
         break;
     case suspended:
         break; /* not supported yet */
     case readonly:
         if (mddev->pers)
             err = md_set_readonly(mddev, NULL);
         else {
             mddev->ro = 1;
             set_disk_ro(mddev->gendisk, 1);
             err = do_md_run(mddev);
         }
         break;
     case read_auto:
         if (mddev->pers) {
             if (mddev->ro == 0)
                 err = md_set_readonly(mddev, NULL);
             else if (mddev->ro == 1)
                 err = restart_array(mddev);
             if (err == 0) {
                 mddev->ro = 2;
                 set_disk_ro(mddev->gendisk, 0);
             }
         } else {
             mddev->ro = 2;
             err = do_md_run(mddev);
         }
         break;
     case clean:
         if (mddev->pers) {
             err = restart_array(mddev);
             if (err)
                 break;
             spin_lock(&mddev->lock);
             if (!set_in_sync(mddev))
                 err = -EBUSY;
             spin_unlock(&mddev->lock);
         } else
             err = -EINVAL;
         break;
     case active:
         if (mddev->pers) {
             err = restart_array(mddev);
             if (err)
                 break;
             clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
             wake_up(&mddev->sb_wait);
             err = 0;
         } else {
             mddev->ro = 0;
             set_disk_ro(mddev->gendisk, 0);
             err = do_md_run(mddev);
         }
         break;
     case write_pending:
     case active_idle:
     case broken:
         /* these cannot be set */
         break;
     }
 
     if (!err) {
         if (mddev->hold_active == UNTIL_IOCTL)
             mddev->hold_active = 0;
         sysfs_notify_dirent_safe(mddev->sysfs_state);
     }
     mddev_unlock(mddev);
     return err ?: len;
 }
 static struct md_sysfs_entry md_array_state =
 __ATTR_PREALLOC(array_state, S_IRUGO|S_IWUSR, array_state_show, array_state_store);
 
 static ssize_t
 max_corrected_read_errors_show(struct mddev *mddev, char *page) {
     return sprintf(page, "%d\n",
                atomic_read(&mddev->max_corr_read_errors));
 }
 
 static ssize_t
 max_corrected_read_errors_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned int n;
     int rv;
 
     rv = kstrtouint(buf, 10, &n);
     if (rv < 0)
         return rv;
     atomic_set(&mddev->max_corr_read_errors, n);
     return len;
 }
 
 static struct md_sysfs_entry max_corr_read_errors =
 __ATTR(max_read_errors, S_IRUGO|S_IWUSR, max_corrected_read_errors_show,
     max_corrected_read_errors_store);
 
 static ssize_t
 null_show(struct mddev *mddev, char *page)
 {
     return -EINVAL;
 }
 
 /* need to ensure rdev_delayed_delete() has completed */
 static void flush_rdev_wq(struct mddev *mddev)
 {
     struct md_rdev *rdev;
 
     rcu_read_lock();
     rdev_for_each_rcu(rdev, mddev)
         if (work_pending(&rdev->del_work)) {
             flush_workqueue(md_rdev_misc_wq);
             break;
         }
     rcu_read_unlock();
 }
 
 static ssize_t
 new_dev_store(struct mddev *mddev, const char *buf, size_t len)
 {
     /* buf must be %d:%d\n? giving major and minor numbers */
     /* The new device is added to the array.
      * If the array has a persistent superblock, we read the
      * superblock to initialise info and check validity.
      * Otherwise, only checking done is that in bind_rdev_to_array,
      * which mainly checks size.
      */
     char *e;
     int major = simple_strtoul(buf, &e, 10);
     int minor;
     dev_t dev;
     struct md_rdev *rdev;
     int err;
 
     if (!*buf || *e != ':' || !e[1] || e[1] == '\n')
         return -EINVAL;
     minor = simple_strtoul(e+1, &e, 10);
     if (*e && *e != '\n')
         return -EINVAL;
     dev = MKDEV(major, minor);
     if (major != MAJOR(dev) ||
         minor != MINOR(dev))
         return -EOVERFLOW;
 
     flush_rdev_wq(mddev);
     err = mddev_lock(mddev);
     if (err)
         return err;
     if (mddev->persistent) {
         rdev = md_import_device(dev, mddev->major_version,
                     mddev->minor_version);
         if (!IS_ERR(rdev) && !list_empty(&mddev->disks)) {
             struct md_rdev *rdev0
                 = list_entry(mddev->disks.next,
                          struct md_rdev, same_set);
             err = super_types[mddev->major_version]
                 .load_super(rdev, rdev0, mddev->minor_version);
             if (err < 0)
                 goto out;
         }
     } else if (mddev->external)
         rdev = md_import_device(dev, -2, -1);
     else
         rdev = md_import_device(dev, -1, -1);
 
     if (IS_ERR(rdev)) {
         mddev_unlock(mddev);
         return PTR_ERR(rdev);
     }
     err = bind_rdev_to_array(rdev, mddev);
  out:
     if (err)
         export_rdev(rdev);
     mddev_unlock(mddev);
     if (!err)
         md_new_event();
     return err ? err : len;
 }
 
 static struct md_sysfs_entry md_new_device =
 __ATTR(new_dev, S_IWUSR, null_show, new_dev_store);
 
 static ssize_t
 bitmap_store(struct mddev *mddev, const char *buf, size_t len)
 {
     char *end;
     unsigned long chunk, end_chunk;
     int err;
 
     err = mddev_lock(mddev);
     if (err)
         return err;
     if (!mddev->bitmap)
         goto out;
     /* buf should be <chunk> <chunk> ... or <chunk>-<chunk> ... (range) */
     while (*buf) {
         chunk = end_chunk = simple_strtoul(buf, &end, 0);
         if (buf == end) break;
         if (*end == '-') { /* range */
             buf = end + 1;
             end_chunk = simple_strtoul(buf, &end, 0);
             if (buf == end) break;
         }
         if (*end && !isspace(*end)) break;
         md_bitmap_dirty_bits(mddev->bitmap, chunk, end_chunk);
         buf = skip_spaces(end);
     }
     md_bitmap_unplug(mddev->bitmap); /* flush the bits to disk */
 out:
     mddev_unlock(mddev);
     return len;
 }
 
 static struct md_sysfs_entry md_bitmap =
 __ATTR(bitmap_set_bits, S_IWUSR, null_show, bitmap_store);
 
 static ssize_t
 size_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%llu\n",
         (unsigned long long)mddev->dev_sectors / 2);
 }
 
 static int update_size(struct mddev *mddev, sector_t num_sectors);
 
 static ssize_t
 size_store(struct mddev *mddev, const char *buf, size_t len)
 {
     /* If array is inactive, we can reduce the component size, but
      * not increase it (except from 0).
      * If array is active, we can try an on-line resize
      */
     sector_t sectors;
     int err = strict_blocks_to_sectors(buf, &sectors);
 
     if (err < 0)
         return err;
     err = mddev_lock(mddev);
     if (err)
         return err;
     if (mddev->pers) {
         err = update_size(mddev, sectors);
         if (err == 0)
             md_update_sb(mddev, 1);
     } else {
         if (mddev->dev_sectors == 0 ||
             mddev->dev_sectors > sectors)
             mddev->dev_sectors = sectors;
         else
             err = -ENOSPC;
     }
     mddev_unlock(mddev);
     return err ? err : len;
 }
 
 static struct md_sysfs_entry md_size =
 __ATTR(component_size, S_IRUGO|S_IWUSR, size_show, size_store);
 
 /* Metadata version.
  * This is one of
  *   'none' for arrays with no metadata (good luck...)
  *   'external' for arrays with externally managed metadata,
  * or N.M for internally known formats
  */
 static ssize_t
 metadata_show(struct mddev *mddev, char *page)
 {
     if (mddev->persistent)
         return sprintf(page, "%d.%d\n",
                    mddev->major_version, mddev->minor_version);
     else if (mddev->external)
         return sprintf(page, "external:%s\n", mddev->metadata_type);
     else
         return sprintf(page, "none\n");
 }
 
 static ssize_t
 metadata_store(struct mddev *mddev, const char *buf, size_t len)
 {
     int major, minor;
     char *e;
     int err;
     /* Changing the details of 'external' metadata is
      * always permitted.  Otherwise there must be
      * no devices attached to the array.
      */
 
     err = mddev_lock(mddev);
     if (err)
         return err;
     err = -EBUSY;
     if (mddev->external && strncmp(buf, "external:", 9) == 0)
         ;
     else if (!list_empty(&mddev->disks))
         goto out_unlock;
 
     err = 0;
     if (cmd_match(buf, "none")) {
         mddev->persistent = 0;
         mddev->external = 0;
         mddev->major_version = 0;
         mddev->minor_version = 90;
         goto out_unlock;
     }
     if (strncmp(buf, "external:", 9) == 0) {
         size_t namelen = len-9;
         if (namelen >= sizeof(mddev->metadata_type))
             namelen = sizeof(mddev->metadata_type)-1;
         strncpy(mddev->metadata_type, buf+9, namelen);
         mddev->metadata_type[namelen] = 0;
         if (namelen && mddev->metadata_type[namelen-1] == '\n')
             mddev->metadata_type[--namelen] = 0;
         mddev->persistent = 0;
         mddev->external = 1;
         mddev->major_version = 0;
         mddev->minor_version = 90;
         goto out_unlock;
     }
     major = simple_strtoul(buf, &e, 10);
     err = -EINVAL;
     if (e==buf || *e != '.')
         goto out_unlock;
     buf = e+1;
     minor = simple_strtoul(buf, &e, 10);
     if (e==buf || (*e && *e != '\n') )
         goto out_unlock;
     err = -ENOENT;
     if (major >= ARRAY_SIZE(super_types) || super_types[major].name == NULL)
         goto out_unlock;
     mddev->major_version = major;
     mddev->minor_version = minor;
     mddev->persistent = 1;
     mddev->external = 0;
     err = 0;
 out_unlock:
     mddev_unlock(mddev);
     return err ?: len;
 }
 
 static struct md_sysfs_entry md_metadata =
 __ATTR_PREALLOC(metadata_version, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
 
 static ssize_t
 action_show(struct mddev *mddev, char *page)
 {
     char *type = "idle";
     unsigned long recovery = mddev->recovery;
     if (test_bit(MD_RECOVERY_FROZEN, &recovery))
         type = "frozen";
     else if (test_bit(MD_RECOVERY_RUNNING, &recovery) ||
         (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &recovery))) {
         if (test_bit(MD_RECOVERY_RESHAPE, &recovery))
             type = "reshape";
         else if (test_bit(MD_RECOVERY_SYNC, &recovery)) {
             if (!test_bit(MD_RECOVERY_REQUESTED, &recovery))
                 type = "resync";
             else if (test_bit(MD_RECOVERY_CHECK, &recovery))
                 type = "check";
             else
                 type = "repair";
         } else if (test_bit(MD_RECOVERY_RECOVER, &recovery))
             type = "recover";
         else if (mddev->reshape_position != MaxSector)
             type = "reshape";
     }
     return sprintf(page, "%s\n", type);
 }
 
 static ssize_t
 action_store(struct mddev *mddev, const char *page, size_t len)
 {
     if (!mddev->pers || !mddev->pers->sync_request)
         return -EINVAL;
 
 
     if (cmd_match(page, "idle") || cmd_match(page, "frozen")) {
         if (cmd_match(page, "frozen"))
             set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
         else
             clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
             mddev_lock(mddev) == 0) {
             if (work_pending(&mddev->del_work))
                 flush_workqueue(md_misc_wq);
             if (mddev->sync_thread) {
                 sector_t save_rp = mddev->reshape_position;
 
                 mddev_unlock(mddev);
                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                 md_unregister_thread(&mddev->sync_thread);
                 mddev_lock_nointr(mddev);
                 /*
                  * set RECOVERY_INTR again and restore reshape
                  * position in case others changed them after
                  * got lock, eg, reshape_position_store and
                  * md_check_recovery.
                  */
                 mddev->reshape_position = save_rp;
                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                 md_reap_sync_thread(mddev);
             }
             mddev_unlock(mddev);
         }
     } else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
         return -EBUSY;
     else if (cmd_match(page, "resync"))
         clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
     else if (cmd_match(page, "recover")) {
         clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
         set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
     } else if (cmd_match(page, "reshape")) {
         int err;
         if (mddev->pers->start_reshape == NULL)
             return -EINVAL;
         err = mddev_lock(mddev);
         if (!err) {
             if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                 err =  -EBUSY;
             else {
                 clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                 err = mddev->pers->start_reshape(mddev);
             }
             mddev_unlock(mddev);
         }
         if (err)
             return err;
         sysfs_notify_dirent_safe(mddev->sysfs_degraded);
     } else {
         if (cmd_match(page, "check"))
             set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
         else if (!cmd_match(page, "repair"))
             return -EINVAL;
         clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
         set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
         set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
     }
     if (mddev->ro == 2) {
         /* A write to sync_action is enough to justify
          * canceling read-auto mode
          */
         mddev->ro = 0;
         md_wakeup_thread(mddev->sync_thread);
     }
     set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
     md_wakeup_thread(mddev->thread);
     sysfs_notify_dirent_safe(mddev->sysfs_action);
     return len;
 }
 
 static struct md_sysfs_entry md_scan_mode =
 __ATTR_PREALLOC(sync_action, S_IRUGO|S_IWUSR, action_show, action_store);
 
 static ssize_t
 last_sync_action_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%s\n", mddev->last_sync_action);
 }
 
 static struct md_sysfs_entry md_last_scan_mode = __ATTR_RO(last_sync_action);
 
 static ssize_t
 mismatch_cnt_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%llu\n",
                (unsigned long long)
                atomic64_read(&mddev->resync_mismatches));
 }
 
 static struct md_sysfs_entry md_mismatches = __ATTR_RO(mismatch_cnt);
 
 static ssize_t
 sync_min_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%d (%s)\n", speed_min(mddev),
                mddev->sync_speed_min ? "local": "system");
 }
 
 static ssize_t
 sync_min_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned int min;
     int rv;
 
     if (strncmp(buf, "system", 6)==0) {
         min = 0;
     } else {
         rv = kstrtouint(buf, 10, &min);
         if (rv < 0)
             return rv;
         if (min == 0)
             return -EINVAL;
     }
     mddev->sync_speed_min = min;
     return len;
 }
 
 static struct md_sysfs_entry md_sync_min =
 __ATTR(sync_speed_min, S_IRUGO|S_IWUSR, sync_min_show, sync_min_store);
 
 static ssize_t
 sync_max_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%d (%s)\n", speed_max(mddev),
                mddev->sync_speed_max ? "local": "system");
 }
 
 static ssize_t
 sync_max_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned int max;
     int rv;
 
     if (strncmp(buf, "system", 6)==0) {
         max = 0;
     } else {
         rv = kstrtouint(buf, 10, &max);
         if (rv < 0)
             return rv;
         if (max == 0)
             return -EINVAL;
     }
     mddev->sync_speed_max = max;
     return len;
 }
 
 static struct md_sysfs_entry md_sync_max =
 __ATTR(sync_speed_max, S_IRUGO|S_IWUSR, sync_max_show, sync_max_store);
 
 static ssize_t
 degraded_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%d\n", mddev->degraded);
 }
 static struct md_sysfs_entry md_degraded = __ATTR_RO(degraded);
 
 static ssize_t
 sync_force_parallel_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%d\n", mddev->parallel_resync);
 }
 
 static ssize_t
 sync_force_parallel_store(struct mddev *mddev, const char *buf, size_t len)
 {
     long n;
 
     if (kstrtol(buf, 10, &n))
         return -EINVAL;
 
     if (n != 0 && n != 1)
         return -EINVAL;
 
     mddev->parallel_resync = n;
 
     if (mddev->sync_thread)
         wake_up(&resync_wait);
 
     return len;
 }
 
 /* force parallel resync, even with shared block devices */
 static struct md_sysfs_entry md_sync_force_parallel =
 __ATTR(sync_force_parallel, S_IRUGO|S_IWUSR,
        sync_force_parallel_show, sync_force_parallel_store);
 
 static ssize_t
 sync_speed_show(struct mddev *mddev, char *page)
 {
     unsigned long resync, dt, db;
     if (mddev->curr_resync == MD_RESYNC_NONE)
         return sprintf(page, "none\n");
     resync = mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active);
     dt = (jiffies - mddev->resync_mark) / HZ;
     if (!dt) dt++;
     db = resync - mddev->resync_mark_cnt;
     return sprintf(page, "%lu\n", db/dt/2); /* K/sec */
 }
 
 static struct md_sysfs_entry md_sync_speed = __ATTR_RO(sync_speed);
 
 static ssize_t
 sync_completed_show(struct mddev *mddev, char *page)
 {
     unsigned long long max_sectors, resync;
 
     if (!test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
         return sprintf(page, "none\n");
 
     if (mddev->curr_resync == MD_RESYNC_YIELDED ||
         mddev->curr_resync == MD_RESYNC_DELAYED)
         return sprintf(page, "delayed\n");
 
     if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
         test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
         max_sectors = mddev->resync_max_sectors;
     else
         max_sectors = mddev->dev_sectors;
 
     resync = mddev->curr_resync_completed;
     return sprintf(page, "%llu / %llu\n", resync, max_sectors);
 }
 
 static struct md_sysfs_entry md_sync_completed =
     __ATTR_PREALLOC(sync_completed, S_IRUGO, sync_completed_show, NULL);
 
 static ssize_t
 min_sync_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%llu\n",
                (unsigned long long)mddev->resync_min);
 }
 static ssize_t
 min_sync_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned long long min;
     int err;
 
     if (kstrtoull(buf, 10, &min))
         return -EINVAL;
 
     spin_lock(&mddev->lock);
     err = -EINVAL;
     if (min > mddev->resync_max)
         goto out_unlock;
 
     err = -EBUSY;
     if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
         goto out_unlock;
 
     /* Round down to multiple of 4K for safety */
     mddev->resync_min = round_down(min, 8);
     err = 0;
 
 out_unlock:
     spin_unlock(&mddev->lock);
     return err ?: len;
 }
 
 static struct md_sysfs_entry md_min_sync =
 __ATTR(sync_min, S_IRUGO|S_IWUSR, min_sync_show, min_sync_store);
 
 static ssize_t
 max_sync_show(struct mddev *mddev, char *page)
 {
     if (mddev->resync_max == MaxSector)
         return sprintf(page, "max\n");
     else
         return sprintf(page, "%llu\n",
                    (unsigned long long)mddev->resync_max);
 }
 static ssize_t
 max_sync_store(struct mddev *mddev, const char *buf, size_t len)
 {
     int err;
     spin_lock(&mddev->lock);
     if (strncmp(buf, "max", 3) == 0)
         mddev->resync_max = MaxSector;
     else {
         unsigned long long max;
         int chunk;
 
         err = -EINVAL;
         if (kstrtoull(buf, 10, &max))
             goto out_unlock;
         if (max < mddev->resync_min)
             goto out_unlock;
 
         err = -EBUSY;
         if (max < mddev->resync_max &&
             mddev->ro == 0 &&
             test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
             goto out_unlock;
 
         /* Must be a multiple of chunk_size */
         chunk = mddev->chunk_sectors;
         if (chunk) {
             sector_t temp = max;
 
             err = -EINVAL;
             if (sector_div(temp, chunk))
                 goto out_unlock;
         }
         mddev->resync_max = max;
     }
     wake_up(&mddev->recovery_wait);
     err = 0;
 out_unlock:
     spin_unlock(&mddev->lock);
     return err ?: len;
 }
 
 static struct md_sysfs_entry md_max_sync =
 __ATTR(sync_max, S_IRUGO|S_IWUSR, max_sync_show, max_sync_store);
 
 static ssize_t
 suspend_lo_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_lo);
 }
 
 static ssize_t
 suspend_lo_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned long long new;
     int err;
 
     err = kstrtoull(buf, 10, &new);
     if (err < 0)
         return err;
     if (new != (sector_t)new)
         return -EINVAL;
 
     err = mddev_lock(mddev);
     if (err)
         return err;
     err = -EINVAL;
     if (mddev->pers == NULL ||
         mddev->pers->quiesce == NULL)
         goto unlock;
     mddev_suspend(mddev);
     mddev->suspend_lo = new;
     mddev_resume(mddev);
 
     err = 0;
 unlock:
     mddev_unlock(mddev);
     return err ?: len;
 }
 static struct md_sysfs_entry md_suspend_lo =
 __ATTR(suspend_lo, S_IRUGO|S_IWUSR, suspend_lo_show, suspend_lo_store);
 
 static ssize_t
 suspend_hi_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_hi);
 }
 
 static ssize_t
 suspend_hi_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned long long new;
     int err;
 
     err = kstrtoull(buf, 10, &new);
     if (err < 0)
         return err;
     if (new != (sector_t)new)
         return -EINVAL;
 
     err = mddev_lock(mddev);
     if (err)
         return err;
     err = -EINVAL;
     if (mddev->pers == NULL)
         goto unlock;
 
     mddev_suspend(mddev);
     mddev->suspend_hi = new;
     mddev_resume(mddev);
 
     err = 0;
 unlock:
     mddev_unlock(mddev);
     return err ?: len;
 }
 static struct md_sysfs_entry md_suspend_hi =
 __ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);
 
 static ssize_t
 reshape_position_show(struct mddev *mddev, char *page)
 {
     if (mddev->reshape_position != MaxSector)
         return sprintf(page, "%llu\n",
                    (unsigned long long)mddev->reshape_position);
     strcpy(page, "none\n");
     return 5;
 }
 
 static ssize_t
 reshape_position_store(struct mddev *mddev, const char *buf, size_t len)
 {
     struct md_rdev *rdev;
     unsigned long long new;
     int err;
 
     err = kstrtoull(buf, 10, &new);
     if (err < 0)
         return err;
     if (new != (sector_t)new)
         return -EINVAL;
     err = mddev_lock(mddev);
     if (err)
         return err;
     err = -EBUSY;
     if (mddev->pers)
         goto unlock;
     mddev->reshape_position = new;
     mddev->delta_disks = 0;
     mddev->reshape_backwards = 0;
     mddev->new_level = mddev->level;
     mddev->new_layout = mddev->layout;
     mddev->new_chunk_sectors = mddev->chunk_sectors;
     rdev_for_each(rdev, mddev)
         rdev->new_data_offset = rdev->data_offset;
     err = 0;
 unlock:
     mddev_unlock(mddev);
     return err ?: len;
 }
 
 static struct md_sysfs_entry md_reshape_position =
 __ATTR(reshape_position, S_IRUGO|S_IWUSR, reshape_position_show,
        reshape_position_store);
 
 static ssize_t
 reshape_direction_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%s\n",
                mddev->reshape_backwards ? "backwards" : "forwards");
 }
 
 static ssize_t
 reshape_direction_store(struct mddev *mddev, const char *buf, size_t len)
 {
     int backwards = 0;
     int err;
 
     if (cmd_match(buf, "forwards"))
         backwards = 0;
     else if (cmd_match(buf, "backwards"))
         backwards = 1;
     else
         return -EINVAL;
     if (mddev->reshape_backwards == backwards)
         return len;
 
     err = mddev_lock(mddev);
     if (err)
         return err;
     /* check if we are allowed to change */
     if (mddev->delta_disks)
         err = -EBUSY;
     else if (mddev->persistent &&
         mddev->major_version == 0)
         err =  -EINVAL;
     else
         mddev->reshape_backwards = backwards;
     mddev_unlock(mddev);
     return err ?: len;
 }
 
 static struct md_sysfs_entry md_reshape_direction =
 __ATTR(reshape_direction, S_IRUGO|S_IWUSR, reshape_direction_show,
        reshape_direction_store);
 
 static ssize_t
 array_size_show(struct mddev *mddev, char *page)
 {
     if (mddev->external_size)
         return sprintf(page, "%llu\n",
                    (unsigned long long)mddev->array_sectors/2);
     else
         return sprintf(page, "default\n");
 }
 
 static ssize_t
 array_size_store(struct mddev *mddev, const char *buf, size_t len)
 {
     sector_t sectors;
     int err;
 
     err = mddev_lock(mddev);
     if (err)
         return err;
 
     /* cluster raid doesn't support change array_sectors */
     if (mddev_is_clustered(mddev)) {
         mddev_unlock(mddev);
         return -EINVAL;
     }
 
     if (strncmp(buf, "default", 7) == 0) {
         if (mddev->pers)
             sectors = mddev->pers->size(mddev, 0, 0);
         else
             sectors = mddev->array_sectors;
 
         mddev->external_size = 0;
     } else {
         if (strict_blocks_to_sectors(buf, &sectors) < 0)
             err = -EINVAL;
         else if (mddev->pers && mddev->pers->size(mddev, 0, 0) < sectors)
             err = -E2BIG;
         else
             mddev->external_size = 1;
     }
 
     if (!err) {
         mddev->array_sectors = sectors;
         if (mddev->pers)
             set_capacity_and_notify(mddev->gendisk,
                         mddev->array_sectors);
     }
     mddev_unlock(mddev);
     return err ?: len;
 }
 
 static struct md_sysfs_entry md_array_size =
 __ATTR(array_size, S_IRUGO|S_IWUSR, array_size_show,
        array_size_store);
 
 static ssize_t
 consistency_policy_show(struct mddev *mddev, char *page)
 {
     int ret;
 
     if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
         ret = sprintf(page, "journal\n");
     } else if (test_bit(MD_HAS_PPL, &mddev->flags)) {
         ret = sprintf(page, "ppl\n");
     } else if (mddev->bitmap) {
         ret = sprintf(page, "bitmap\n");
     } else if (mddev->pers) {
         if (mddev->pers->sync_request)
             ret = sprintf(page, "resync\n");
         else
             ret = sprintf(page, "none\n");
     } else {
         ret = sprintf(page, "unknown\n");
     }
 
     return ret;
 }
 
 static ssize_t
 consistency_policy_store(struct mddev *mddev, const char *buf, size_t len)
 {
     int err = 0;
 
     if (mddev->pers) {
         if (mddev->pers->change_consistency_policy)
             err = mddev->pers->change_consistency_policy(mddev, buf);
         else
             err = -EBUSY;
     } else if (mddev->external && strncmp(buf, "ppl", 3) == 0) {
         set_bit(MD_HAS_PPL, &mddev->flags);
     } else {
         err = -EINVAL;
     }
 
     return err ? err : len;
 }
 
 static struct md_sysfs_entry md_consistency_policy =
 __ATTR(consistency_policy, S_IRUGO | S_IWUSR, consistency_policy_show,
        consistency_policy_store);
 
 static ssize_t fail_last_dev_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%d\n", mddev->fail_last_dev);
 }
 
 /*
  * Setting fail_last_dev to true to allow last device to be forcibly removed
  * from RAID1/RAID10.
  */
 static ssize_t
 fail_last_dev_store(struct mddev *mddev, const char *buf, size_t len)
 {
     int ret;
     bool value;
 
     ret = kstrtobool(buf, &value);
     if (ret)
         return ret;
 
     if (value != mddev->fail_last_dev)
         mddev->fail_last_dev = value;
 
     return len;
 }
 static struct md_sysfs_entry md_fail_last_dev =
 __ATTR(fail_last_dev, S_IRUGO | S_IWUSR, fail_last_dev_show,
        fail_last_dev_store);
 
 static ssize_t serialize_policy_show(struct mddev *mddev, char *page)
 {
     if (mddev->pers == NULL || (mddev->pers->level != 1))
         return sprintf(page, "n/a\n");
     else
         return sprintf(page, "%d\n", mddev->serialize_policy);
 }
 
 /*
  * Setting serialize_policy to true to enforce write IO is not reordered
  * for raid1.
  */
 static ssize_t
 serialize_policy_store(struct mddev *mddev, const char *buf, size_t len)
 {
     int err;
     bool value;
 
     err = kstrtobool(buf, &value);
     if (err)
         return err;
 
     if (value == mddev->serialize_policy)
         return len;
 
     err = mddev_lock(mddev);
     if (err)
         return err;
     if (mddev->pers == NULL || (mddev->pers->level != 1)) {
         pr_err("md: serialize_policy is only effective for raid1\n");
         err = -EINVAL;
         goto unlock;
     }
 
     mddev_suspend(mddev);
     if (value)
         mddev_create_serial_pool(mddev, NULL, true);
     else
         mddev_destroy_serial_pool(mddev, NULL, true);
     mddev->serialize_policy = value;
     mddev_resume(mddev);
 unlock:
     mddev_unlock(mddev);
     return err ?: len;
 }
 
 static struct md_sysfs_entry md_serialize_policy =
 __ATTR(serialize_policy, S_IRUGO | S_IWUSR, serialize_policy_show,
        serialize_policy_store);
 
 
 static struct attribute *md_default_attrs[] = {
     &md_level.attr,
     &md_layout.attr,
     &md_raid_disks.attr,
     &md_uuid.attr,
     &md_chunk_size.attr,
     &md_size.attr,
     &md_resync_start.attr,
     &md_metadata.attr,
     &md_new_device.attr,
     &md_safe_delay.attr,
     &md_array_state.attr,
     &md_reshape_position.attr,
     &md_reshape_direction.attr,
     &md_array_size.attr,
     &max_corr_read_errors.attr,
     &md_consistency_policy.attr,
     &md_fail_last_dev.attr,
     &md_serialize_policy.attr,
     NULL,
 };
 
 static const struct attribute_group md_default_group = {
     .attrs = md_default_attrs,
 };
 
 static struct attribute *md_redundancy_attrs[] = {
     &md_scan_mode.attr,
     &md_last_scan_mode.attr,
     &md_mismatches.attr,
     &md_sync_min.attr,
     &md_sync_max.attr,
     &md_sync_speed.attr,
     &md_sync_force_parallel.attr,
     &md_sync_completed.attr,
     &md_min_sync.attr,
     &md_max_sync.attr,
     &md_suspend_lo.attr,
     &md_suspend_hi.attr,
     &md_bitmap.attr,
     &md_degraded.attr,
     NULL,
 };
 static const struct attribute_group md_redundancy_group = {
     .name = NULL,
     .attrs = md_redundancy_attrs,
 };
 
 static const struct attribute_group *md_attr_groups[] = {
     &md_default_group,
     &md_bitmap_group,
     NULL,
 };
 
 static ssize_t
 md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 {
     struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
     struct mddev *mddev = container_of(kobj, struct mddev, kobj);
     ssize_t rv;
 
     if (!entry->show)
         return -EIO;
     spin_lock(&all_mddevs_lock);
     if (!mddev_get(mddev)) {
         spin_unlock(&all_mddevs_lock);
         return -EBUSY;
     }
     spin_unlock(&all_mddevs_lock);
 
     rv = entry->show(mddev, page);
     mddev_put(mddev);
     return rv;
 }
 
 static ssize_t
 md_attr_store(struct kobject *kobj, struct attribute *attr,
           const char *page, size_t length)
 {
     struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
     struct mddev *mddev = container_of(kobj, struct mddev, kobj);
     ssize_t rv;
 
     if (!entry->store)
         return -EIO;
     if (!capable(CAP_SYS_ADMIN))
         return -EACCES;
     spin_lock(&all_mddevs_lock);
     if (!mddev_get(mddev)) {
         spin_unlock(&all_mddevs_lock);
         return -EBUSY;
     }
     spin_unlock(&all_mddevs_lock);
     rv = entry->store(mddev, page, length);
     mddev_put(mddev);
     return rv;
 }
 
 static void md_kobj_release(struct kobject *ko)
 {
     struct mddev *mddev = container_of(ko, struct mddev, kobj);
 
     if (mddev->sysfs_state)
         sysfs_put(mddev->sysfs_state);
     if (mddev->sysfs_level)
         sysfs_put(mddev->sysfs_level);
 
     del_gendisk(mddev->gendisk);
     put_disk(mddev->gendisk);
 }
 
 static const struct sysfs_ops md_sysfs_ops = {
     .show   = md_attr_show,
     .store  = md_attr_store,
 };
 static struct kobj_type md_ktype = {
     .release    = md_kobj_release,
     .sysfs_ops  = &md_sysfs_ops,
     .default_groups = md_attr_groups,
 };
 
 int mdp_major = 0;
 
 static void mddev_delayed_delete(struct work_struct *ws)
 {
     struct mddev *mddev = container_of(ws, struct mddev, del_work);
 
     kobject_put(&mddev->kobj);
 }
 
 static void no_op(struct percpu_ref *r) {}
 
 int mddev_init_writes_pending(struct mddev *mddev)
 {
     if (mddev->writes_pending.percpu_count_ptr)
         return 0;
     if (percpu_ref_init(&mddev->writes_pending, no_op,
                 PERCPU_REF_ALLOW_REINIT, GFP_KERNEL) < 0)
         return -ENOMEM;
     /* We want to start with the refcount at zero */
     percpu_ref_put(&mddev->writes_pending);
     return 0;
 }
 EXPORT_SYMBOL_GPL(mddev_init_writes_pending);
 
 struct mddev *md_alloc(dev_t dev, char *name)
 {
     /*
      * If dev is zero, name is the name of a device to allocate with
      * an arbitrary minor number.  It will be "md_???"
      * If dev is non-zero it must be a device number with a MAJOR of
      * MD_MAJOR or mdp_major.  In this case, if "name" is NULL, then
      * the device is being created by opening a node in /dev.
      * If "name" is not NULL, the device is being created by
      * writing to /sys/module/md_mod/parameters/new_array.
      */
     static DEFINE_MUTEX(disks_mutex);
     struct mddev *mddev;
     struct gendisk *disk;
     int partitioned;
     int shift;
     int unit;
     int error ;
 
     /*
      * Wait for any previous instance of this device to be completely
      * removed (mddev_delayed_delete).
      */
     flush_workqueue(md_misc_wq);
     flush_workqueue(md_rdev_misc_wq);
 
     mutex_lock(&disks_mutex);
     mddev = mddev_alloc(dev);
     if (IS_ERR(mddev)) {
         error = PTR_ERR(mddev);
         goto out_unlock;
     }
 
     partitioned = (MAJOR(mddev->unit) != MD_MAJOR);
     shift = partitioned ? MdpMinorShift : 0;
     unit = MINOR(mddev->unit) >> shift;
 
     if (name && !dev) {
         /* Need to ensure that 'name' is not a duplicate.
          */
         struct mddev *mddev2;
         spin_lock(&all_mddevs_lock);
 
         list_for_each_entry(mddev2, &all_mddevs, all_mddevs)
             if (mddev2->gendisk &&
                 strcmp(mddev2->gendisk->disk_name, name) == 0) {
                 spin_unlock(&all_mddevs_lock);
                 error = -EEXIST;
                 goto out_free_mddev;
             }
         spin_unlock(&all_mddevs_lock);
     }
     if (name && dev)
         /*
          * Creating /dev/mdNNN via "newarray", so adjust hold_active.
          */
         mddev->hold_active = UNTIL_STOP;
 
     error = -ENOMEM;
     disk = blk_alloc_disk(NUMA_NO_NODE);
     if (!disk)
         goto out_free_mddev;
 
     disk->major = MAJOR(mddev->unit);
     disk->first_minor = unit << shift;
     disk->minors = 1 << shift;
     if (name)
         strcpy(disk->disk_name, name);
     else if (partitioned)
         sprintf(disk->disk_name, "md_d%d", unit);
     else
         sprintf(disk->disk_name, "md%d", unit);
     disk->fops = &md_fops;
     disk->private_data = mddev;
 
     mddev->queue = disk->queue;
     blk_set_stacking_limits(&mddev->queue->limits);
     blk_queue_write_cache(mddev->queue, true, true);
     disk->events |= DISK_EVENT_MEDIA_CHANGE;
     mddev->gendisk = disk;
     error = add_disk(disk);
     if (error)
         goto out_put_disk;
 
     kobject_init(&mddev->kobj, &md_ktype);
     error = kobject_add(&mddev->kobj, &disk_to_dev(disk)->kobj, "%s", "md");
     if (error) {
         /*
          * The disk is already live at this point.  Clear the hold flag
          * and let mddev_put take care of the deletion, as it isn't any
          * different from a normal close on last release now.
          */
         mddev->hold_active = 0;
         mutex_unlock(&disks_mutex);
         mddev_put(mddev);
         return ERR_PTR(error);
     }
 
     kobject_uevent(&mddev->kobj, KOBJ_ADD);
     mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
     mddev->sysfs_level = sysfs_get_dirent_safe(mddev->kobj.sd, "level");
     mutex_unlock(&disks_mutex);
     return mddev;
 
 out_put_disk:
     put_disk(disk);
 out_free_mddev:
     mddev_free(mddev);
 out_unlock:
     mutex_unlock(&disks_mutex);
     return ERR_PTR(error);
 }
 
 static int md_alloc_and_put(dev_t dev, char *name)
 {
     struct mddev *mddev = md_alloc(dev, name);
 
     if (IS_ERR(mddev))
         return PTR_ERR(mddev);
     mddev_put(mddev);
     return 0;
 }
 
 static void md_probe(dev_t dev)
 {
     if (MAJOR(dev) == MD_MAJOR && MINOR(dev) >= 512)
         return;
     if (create_on_open)
         md_alloc_and_put(dev, NULL);
 }
 
 static int add_named_array(const char *val, const struct kernel_param *kp)
 {
     /*
      * val must be "md_*" or "mdNNN".
      * For "md_*" we allocate an array with a large free minor number, and
      * set the name to val.  val must not already be an active name.
      * For "mdNNN" we allocate an array with the minor number NNN
      * which must not already be in use.
      */
     int len = strlen(val);
     char buf[DISK_NAME_LEN];
     unsigned long devnum;
 
     while (len && val[len-1] == '\n')
         len--;
     if (len >= DISK_NAME_LEN)
         return -E2BIG;
     strscpy(buf, val, len+1);
     if (strncmp(buf, "md_", 3) == 0)
         return md_alloc_and_put(0, buf);
     if (strncmp(buf, "md", 2) == 0 &&
         isdigit(buf[2]) &&
         kstrtoul(buf+2, 10, &devnum) == 0 &&
         devnum <= MINORMASK)
         return md_alloc_and_put(MKDEV(MD_MAJOR, devnum), NULL);
 
     return -EINVAL;
 }
 
 static void md_safemode_timeout(struct timer_list *t)
 {
     struct mddev *mddev = from_timer(mddev, t, safemode_timer);
 
     mddev->safemode = 1;
     if (mddev->external)
         sysfs_notify_dirent_safe(mddev->sysfs_state);
 
     md_wakeup_thread(mddev->thread);
 }
 
 static int start_dirty_degraded;
 
 int md_run(struct mddev *mddev)
 {
     int err;
     struct md_rdev *rdev;
     struct md_personality *pers;
     bool nowait = true;
 
     if (list_empty(&mddev->disks))
         /* cannot run an array with no devices.. */
         return -EINVAL;
 
     if (mddev->pers)
         return -EBUSY;
     /* Cannot run until previous stop completes properly */
     if (mddev->sysfs_active)
         return -EBUSY;
 
     /*
      * Analyze all RAID superblock(s)
      */
     if (!mddev->raid_disks) {
         if (!mddev->persistent)
             return -EINVAL;
         err = analyze_sbs(mddev);
         if (err)
             return -EINVAL;
     }
 
     if (mddev->level != LEVEL_NONE)
         request_module("md-level-%d", mddev->level);
     else if (mddev->clevel[0])
         request_module("md-%s", mddev->clevel);
 
     /*
      * Drop all container device buffers, from now on
      * the only valid external interface is through the md
      * device.
      */
     mddev->has_superblocks = false;
     rdev_for_each(rdev, mddev) {
         if (test_bit(Faulty, &rdev->flags))
             continue;
         sync_blockdev(rdev->bdev);
         invalidate_bdev(rdev->bdev);
         if (mddev->ro != 1 && rdev_read_only(rdev)) {
             mddev->ro = 1;
             if (mddev->gendisk)
                 set_disk_ro(mddev->gendisk, 1);
         }
 
         if (rdev->sb_page)
             mddev->has_superblocks = true;
 
         /* perform some consistency tests on the device.
          * We don't want the data to overlap the metadata,
          * Internal Bitmap issues have been handled elsewhere.
          */
         if (rdev->meta_bdev) {
             /* Nothing to check */;
         } else if (rdev->data_offset < rdev->sb_start) {
             if (mddev->dev_sectors &&
                 rdev->data_offset + mddev->dev_sectors
                 > rdev->sb_start) {
                 pr_warn("md: %s: data overlaps metadata\n",
                     mdname(mddev));
                 return -EINVAL;
             }
         } else {
             if (rdev->sb_start + rdev->sb_size/512
                 > rdev->data_offset) {
                 pr_warn("md: %s: metadata overlaps data\n",
                     mdname(mddev));
                 return -EINVAL;
             }
         }
         sysfs_notify_dirent_safe(rdev->sysfs_state);
         nowait = nowait && blk_queue_nowait(bdev_get_queue(rdev->bdev));
     }
 
     if (!bioset_initialized(&mddev->bio_set)) {
         err = bioset_init(&mddev->bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
         if (err)
             return err;
     }
     if (!bioset_initialized(&mddev->sync_set)) {
         err = bioset_init(&mddev->sync_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
         if (err)
             goto exit_bio_set;
     }
 
     spin_lock(&pers_lock);
     pers = find_pers(mddev->level, mddev->clevel);
     if (!pers || !try_module_get(pers->owner)) {
         spin_unlock(&pers_lock);
         if (mddev->level != LEVEL_NONE)
             pr_warn("md: personality for level %d is not loaded!\n",
                 mddev->level);
         else
             pr_warn("md: personality for level %s is not loaded!\n",
                 mddev->clevel);
         err = -EINVAL;
         goto abort;
     }
     spin_unlock(&pers_lock);
     if (mddev->level != pers->level) {
         mddev->level = pers->level;
         mddev->new_level = pers->level;
     }
     strscpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
 
     if (mddev->reshape_position != MaxSector &&
         pers->start_reshape == NULL) {
         /* This personality cannot handle reshaping... */
         module_put(pers->owner);
         err = -EINVAL;
         goto abort;
     }
 
     if (pers->sync_request) {
         /* Warn if this is a potentially silly
          * configuration.
          */
         struct md_rdev *rdev2;
         int warned = 0;
 
         rdev_for_each(rdev, mddev)
             rdev_for_each(rdev2, mddev) {
                 if (rdev < rdev2 &&
                     rdev->bdev->bd_disk ==
                     rdev2->bdev->bd_disk) {
                     pr_warn("%s: WARNING: %pg appears to be on the same physical disk as %pg.\n",
                         mdname(mddev),
                         rdev->bdev,
                         rdev2->bdev);
                     warned = 1;
                 }
             }
 
         if (warned)
             pr_warn("True protection against single-disk failure might be compromised.\n");
     }
 
     mddev->recovery = 0;
     /* may be over-ridden by personality */
     mddev->resync_max_sectors = mddev->dev_sectors;
 
     mddev->ok_start_degraded = start_dirty_degraded;
 
     if (start_readonly && mddev->ro == 0)
         mddev->ro = 2; /* read-only, but switch on first write */
 
     err = pers->run(mddev);
     if (err)
         pr_warn("md: pers->run() failed ...\n");
     else if (pers->size(mddev, 0, 0) < mddev->array_sectors) {
         WARN_ONCE(!mddev->external_size,
               "%s: default size too small, but 'external_size' not in effect?\n",
               __func__);
         pr_warn("md: invalid array_size %llu > default size %llu\n",
             (unsigned long long)mddev->array_sectors / 2,
             (unsigned long long)pers->size(mddev, 0, 0) / 2);
         err = -EINVAL;
     }
     if (err == 0 && pers->sync_request &&
         (mddev->bitmap_info.file || mddev->bitmap_info.offset)) {
         struct bitmap *bitmap;
 
         bitmap = md_bitmap_create(mddev, -1);
         if (IS_ERR(bitmap)) {
             err = PTR_ERR(bitmap);
             pr_warn("%s: failed to create bitmap (%d)\n",
                 mdname(mddev), err);
         } else
             mddev->bitmap = bitmap;
 
     }
     if (err)
         goto bitmap_abort;
 
     if (mddev->bitmap_info.max_write_behind > 0) {
         bool create_pool = false;
 
         rdev_for_each(rdev, mddev) {
             if (test_bit(WriteMostly, &rdev->flags) &&
                 rdev_init_serial(rdev))
                 create_pool = true;
         }
         if (create_pool && mddev->serial_info_pool == NULL) {
             mddev->serial_info_pool =
                 mempool_create_kmalloc_pool(NR_SERIAL_INFOS,
                             sizeof(struct serial_info));
             if (!mddev->serial_info_pool) {
                 err = -ENOMEM;
                 goto bitmap_abort;
             }
         }
     }
 
     if (mddev->queue) {
         bool nonrot = true;
 
         rdev_for_each(rdev, mddev) {
             if (rdev->raid_disk >= 0 && !bdev_nonrot(rdev->bdev)) {
                 nonrot = false;
                 break;
             }
         }
         if (mddev->degraded)
             nonrot = false;
         if (nonrot)
             blk_queue_flag_set(QUEUE_FLAG_NONROT, mddev->queue);
         else
             blk_queue_flag_clear(QUEUE_FLAG_NONROT, mddev->queue);
         blk_queue_flag_set(QUEUE_FLAG_IO_STAT, mddev->queue);
 
         /* Set the NOWAIT flags if all underlying devices support it */
         if (nowait)
             blk_queue_flag_set(QUEUE_FLAG_NOWAIT, mddev->queue);
     }
     if (pers->sync_request) {
         if (mddev->kobj.sd &&
             sysfs_create_group(&mddev->kobj, &md_redundancy_group))
             pr_warn("md: cannot register extra attributes for %s\n",
                 mdname(mddev));
         mddev->sysfs_action = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_action");
         mddev->sysfs_completed = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_completed");
         mddev->sysfs_degraded = sysfs_get_dirent_safe(mddev->kobj.sd, "degraded");
     } else if (mddev->ro == 2) /* auto-readonly not meaningful */
         mddev->ro = 0;
 
     atomic_set(&mddev->max_corr_read_errors,
            MD_DEFAULT_MAX_CORRECTED_READ_ERRORS);
     mddev->safemode = 0;
     if (mddev_is_clustered(mddev))
         mddev->safemode_delay = 0;
     else
         mddev->safemode_delay = DEFAULT_SAFEMODE_DELAY;
     mddev->in_sync = 1;
     smp_wmb();
     spin_lock(&mddev->lock);
     mddev->pers = pers;
     spin_unlock(&mddev->lock);
     rdev_for_each(rdev, mddev)
         if (rdev->raid_disk >= 0)
             sysfs_link_rdev(mddev, rdev); /* failure here is OK */
 
     if (mddev->degraded && !mddev->ro)
         /* This ensures that recovering status is reported immediately
          * via sysfs - until a lack of spares is confirmed.
          */
         set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
     set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 
     if (mddev->sb_flags)
         md_update_sb(mddev, 0);
 
     md_new_event();
     return 0;
 
 bitmap_abort:
     mddev_detach(mddev);
     if (mddev->private)
         pers->free(mddev, mddev->private);
     mddev->private = NULL;
     module_put(pers->owner);
     md_bitmap_destroy(mddev);
 abort:
     bioset_exit(&mddev->sync_set);
 exit_bio_set:
     bioset_exit(&mddev->bio_set);
     return err;
 }
 EXPORT_SYMBOL_GPL(md_run);
 
 int do_md_run(struct mddev *mddev)
 {
     int err;
 
     set_bit(MD_NOT_READY, &mddev->flags);
     err = md_run(mddev);
     if (err)
         goto out;
     err = md_bitmap_load(mddev);
     if (err) {
         md_bitmap_destroy(mddev);
         goto out;
     }
 
     if (mddev_is_clustered(mddev))
         md_allow_write(mddev);
 
     /* run start up tasks that require md_thread */
     md_start(mddev);
 
     md_wakeup_thread(mddev->thread);
     md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
 
     set_capacity_and_notify(mddev->gendisk, mddev->array_sectors);
     clear_bit(MD_NOT_READY, &mddev->flags);
     mddev->changed = 1;
     kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
     sysfs_notify_dirent_safe(mddev->sysfs_state);
     sysfs_notify_dirent_safe(mddev->sysfs_action);
     sysfs_notify_dirent_safe(mddev->sysfs_degraded);
 out:
     clear_bit(MD_NOT_READY, &mddev->flags);
     return err;
 }
 
 int md_start(struct mddev *mddev)
 {
     int ret = 0;
 
     if (mddev->pers->start) {
         set_bit(MD_RECOVERY_WAIT, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
         ret = mddev->pers->start(mddev);
         clear_bit(MD_RECOVERY_WAIT, &mddev->recovery);
         md_wakeup_thread(mddev->sync_thread);
     }
     return ret;
 }
 EXPORT_SYMBOL_GPL(md_start);
 
 static int restart_array(struct mddev *mddev)
 {
     struct gendisk *disk = mddev->gendisk;
     struct md_rdev *rdev;
     bool has_journal = false;
     bool has_readonly = false;
 
     /* Complain if it has no devices */
     if (list_empty(&mddev->disks))
         return -ENXIO;
     if (!mddev->pers)
         return -EINVAL;
     if (!mddev->ro)
         return -EBUSY;
 
     rcu_read_lock();
     rdev_for_each_rcu(rdev, mddev) {
         if (test_bit(Journal, &rdev->flags) &&
             !test_bit(Faulty, &rdev->flags))
             has_journal = true;
         if (rdev_read_only(rdev))
             has_readonly = true;
     }
     rcu_read_unlock();
     if (test_bit(MD_HAS_JOURNAL, &mddev->flags) && !has_journal)
         /* Don't restart rw with journal missing/faulty */
             return -EINVAL;
     if (has_readonly)
         return -EROFS;
 
     mddev->safemode = 0;
     mddev->ro = 0;
     set_disk_ro(disk, 0);
     pr_debug("md: %s switched to read-write mode.\n", mdname(mddev));
     /* Kick recovery or resync if necessary */
     set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
     md_wakeup_thread(mddev->thread);
     md_wakeup_thread(mddev->sync_thread);
     sysfs_notify_dirent_safe(mddev->sysfs_state);
     return 0;
 }
 
 static void md_clean(struct mddev *mddev)
 {
     mddev->array_sectors = 0;
     mddev->external_size = 0;
     mddev->dev_sectors = 0;
     mddev->raid_disks = 0;
     mddev->recovery_cp = 0;
     mddev->resync_min = 0;
     mddev->resync_max = MaxSector;
     mddev->reshape_position = MaxSector;
     mddev->external = 0;
     mddev->persistent = 0;
     mddev->level = LEVEL_NONE;
     mddev->clevel[0] = 0;
     mddev->flags = 0;
     mddev->sb_flags = 0;
     mddev->ro = 0;
     mddev->metadata_type[0] = 0;
     mddev->chunk_sectors = 0;
     mddev->ctime = mddev->utime = 0;
     mddev->layout = 0;
     mddev->max_disks = 0;
     mddev->events = 0;
     mddev->can_decrease_events = 0;
     mddev->delta_disks = 0;
     mddev->reshape_backwards = 0;
     mddev->new_level = LEVEL_NONE;
     mddev->new_layout = 0;
     mddev->new_chunk_sectors = 0;
     mddev->curr_resync = 0;
     atomic64_set(&mddev->resync_mismatches, 0);
     mddev->suspend_lo = mddev->suspend_hi = 0;
     mddev->sync_speed_min = mddev->sync_speed_max = 0;
     mddev->recovery = 0;
     mddev->in_sync = 0;
     mddev->changed = 0;
     mddev->degraded = 0;
     mddev->safemode = 0;
     mddev->private = NULL;
     mddev->cluster_info = NULL;
     mddev->bitmap_info.offset = 0;
     mddev->bitmap_info.default_offset = 0;
     mddev->bitmap_info.default_space = 0;
     mddev->bitmap_info.chunksize = 0;
     mddev->bitmap_info.daemon_sleep = 0;
     mddev->bitmap_info.max_write_behind = 0;
     mddev->bitmap_info.nodes = 0;
 }
 
 static void __md_stop_writes(struct mddev *mddev)
 {
     set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
     if (work_pending(&mddev->del_work))
         flush_workqueue(md_misc_wq);
     if (mddev->sync_thread) {
         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
         md_unregister_thread(&mddev->sync_thread);
         md_reap_sync_thread(mddev);
     }
 
     del_timer_sync(&mddev->safemode_timer);
 
     if (mddev->pers && mddev->pers->quiesce) {
         mddev->pers->quiesce(mddev, 1);
         mddev->pers->quiesce(mddev, 0);
     }
     md_bitmap_flush(mddev);
 
     if (mddev->ro == 0 &&
         ((!mddev->in_sync && !mddev_is_clustered(mddev)) ||
          mddev->sb_flags)) {
         /* mark array as shutdown cleanly */
         if (!mddev_is_clustered(mddev))
             mddev->in_sync = 1;
         md_update_sb(mddev, 1);
     }
     /* disable policy to guarantee rdevs free resources for serialization */
     mddev->serialize_policy = 0;
     mddev_destroy_serial_pool(mddev, NULL, true);
 }
 
 void md_stop_writes(struct mddev *mddev)
 {
     mddev_lock_nointr(mddev);
     __md_stop_writes(mddev);
     mddev_unlock(mddev);
 }
 EXPORT_SYMBOL_GPL(md_stop_writes);
 
 static void mddev_detach(struct mddev *mddev)
 {
     md_bitmap_wait_behind_writes(mddev);
     if (mddev->pers && mddev->pers->quiesce && !mddev->suspended) {
         mddev->pers->quiesce(mddev, 1);
         mddev->pers->quiesce(mddev, 0);
     }
     md_unregister_thread(&mddev->thread);
     if (mddev->queue)
         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
 }
 
 static void __md_stop(struct mddev *mddev)
 {
     struct md_personality *pers = mddev->pers;
     md_bitmap_destroy(mddev);
     mddev_detach(mddev);
     /* Ensure ->event_work is done */
     if (mddev->event_work.func)
         flush_workqueue(md_misc_wq);
     spin_lock(&mddev->lock);
     mddev->pers = NULL;
     spin_unlock(&mddev->lock);
     if (mddev->private)
         pers->free(mddev, mddev->private);
     mddev->private = NULL;
     if (pers->sync_request && mddev->to_remove == NULL)
         mddev->to_remove = &md_redundancy_group;
     module_put(pers->owner);
     clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 }
 
 void md_stop(struct mddev *mddev)
 {
     /* stop the array and free an attached data structures.
      * This is called from dm-raid
      */
     __md_stop_writes(mddev);
     __md_stop(mddev);
     bioset_exit(&mddev->bio_set);
     bioset_exit(&mddev->sync_set);
 }
 
 EXPORT_SYMBOL_GPL(md_stop);
 
 static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
 {
     int err = 0;
     int did_freeze = 0;
 
     if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
         did_freeze = 1;
         set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
     }
     if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
     if (mddev->sync_thread)
         /* Thread might be blocked waiting for metadata update
          * which will now never happen */
         wake_up_process(mddev->sync_thread->tsk);
 
     if (mddev->external && test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags))
         return -EBUSY;
     mddev_unlock(mddev);
     wait_event(resync_wait, !test_bit(MD_RECOVERY_RUNNING,
                       &mddev->recovery));
     wait_event(mddev->sb_wait,
            !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags));
     mddev_lock_nointr(mddev);
 
     mutex_lock(&mddev->open_mutex);
     if ((mddev->pers && atomic_read(&mddev->openers) > !!bdev) ||
         mddev->sync_thread ||
         test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
         pr_warn("md: %s still in use.\n",mdname(mddev));
         if (did_freeze) {
             clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
             set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
             md_wakeup_thread(mddev->thread);
         }
         err = -EBUSY;
         goto out;
     }
     if (mddev->pers) {
         __md_stop_writes(mddev);
 
         err  = -ENXIO;
         if (mddev->ro==1)
             goto out;
         mddev->ro = 1;
         set_disk_ro(mddev->gendisk, 1);
         clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
         sysfs_notify_dirent_safe(mddev->sysfs_state);
         err = 0;
     }
 out:
     mutex_unlock(&mddev->open_mutex);
     return err;
 }
 
 /* mode:
  *   0 - completely stop and dis-assemble array
  *   2 - stop but do not disassemble array
  */
 static int do_md_stop(struct mddev *mddev, int mode,
               struct block_device *bdev)
 {
     struct gendisk *disk = mddev->gendisk;
     struct md_rdev *rdev;
     int did_freeze = 0;
 
     if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
         did_freeze = 1;
         set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
     }
     if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
     if (mddev->sync_thread)
         /* Thread might be blocked waiting for metadata update
          * which will now never happen */
         wake_up_process(mddev->sync_thread->tsk);
 
     mddev_unlock(mddev);
     wait_event(resync_wait, (mddev->sync_thread == NULL &&
                  !test_bit(MD_RECOVERY_RUNNING,
                        &mddev->recovery)));
     mddev_lock_nointr(mddev);
 
     mutex_lock(&mddev->open_mutex);
     if ((mddev->pers && atomic_read(&mddev->openers) > !!bdev) ||
         mddev->sysfs_active ||
         mddev->sync_thread ||
         test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
         pr_warn("md: %s still in use.\n",mdname(mddev));
         mutex_unlock(&mddev->open_mutex);
         if (did_freeze) {
             clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
             set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
             md_wakeup_thread(mddev->thread);
         }
         return -EBUSY;
     }
     if (mddev->pers) {
         if (mddev->ro)
             set_disk_ro(disk, 0);
 
         __md_stop_writes(mddev);
         __md_stop(mddev);
 
         /* tell userspace to handle 'inactive' */
         sysfs_notify_dirent_safe(mddev->sysfs_state);
 
         rdev_for_each(rdev, mddev)
             if (rdev->raid_disk >= 0)
                 sysfs_unlink_rdev(mddev, rdev);
 
         set_capacity_and_notify(disk, 0);
         mutex_unlock(&mddev->open_mutex);
         mddev->changed = 1;
 
         if (mddev->ro)
             mddev->ro = 0;
     } else
         mutex_unlock(&mddev->open_mutex);
     /*
      * Free resources if final stop
      */
     if (mode == 0) {
         pr_info("md: %s stopped.\n", mdname(mddev));
 
         if (mddev->bitmap_info.file) {
             struct file *f = mddev->bitmap_info.file;
             spin_lock(&mddev->lock);
             mddev->bitmap_info.file = NULL;
             spin_unlock(&mddev->lock);
             fput(f);
         }
         mddev->bitmap_info.offset = 0;
 
         export_array(mddev);
 
         md_clean(mddev);
         if (mddev->hold_active == UNTIL_STOP)
             mddev->hold_active = 0;
     }
     md_new_event();
     sysfs_notify_dirent_safe(mddev->sysfs_state);
     return 0;
 }
 
 #ifndef MODULE
 static void autorun_array(struct mddev *mddev)
 {
     struct md_rdev *rdev;
     int err;
 
     if (list_empty(&mddev->disks))
         return;
 
     pr_info("md: running: ");
 
     rdev_for_each(rdev, mddev) {
         pr_cont("<%pg>", rdev->bdev);
     }
     pr_cont("\n");
 
     err = do_md_run(mddev);
     if (err) {
         pr_warn("md: do_md_run() returned %d\n", err);
         do_md_stop(mddev, 0, NULL);
     }
 }
 
 /*
  * lets try to run arrays based on all disks that have arrived
  * until now. (those are in pending_raid_disks)
  *
  * the method: pick the first pending disk, collect all disks with
  * the same UUID, remove all from the pending list and put them into
  * the 'same_array' list. Then order this list based on superblock
  * update time (freshest comes first), kick out 'old' disks and
  * compare superblocks. If everything's fine then run it.
  *
  * If "unit" is allocated, then bump its reference count
  */
 static void autorun_devices(int part)
 {
     struct md_rdev *rdev0, *rdev, *tmp;
     struct mddev *mddev;
 
     pr_info("md: autorun ...\n");
     while (!list_empty(&pending_raid_disks)) {
         int unit;
         dev_t dev;
         LIST_HEAD(candidates);
         rdev0 = list_entry(pending_raid_disks.next,
                      struct md_rdev, same_set);
 
         pr_debug("md: considering %pg ...\n", rdev0->bdev);
         INIT_LIST_HEAD(&candidates);
         rdev_for_each_list(rdev, tmp, &pending_raid_disks)
             if (super_90_load(rdev, rdev0, 0) >= 0) {
                 pr_debug("md:  adding %pg ...\n",
                      rdev->bdev);
                 list_move(&rdev->same_set, &candidates);
             }
         /*
          * now we have a set of devices, with all of them having
          * mostly sane superblocks. It's time to allocate the
          * mddev.
          */
         if (part) {
             dev = MKDEV(mdp_major,
                     rdev0->preferred_minor << MdpMinorShift);
             unit = MINOR(dev) >> MdpMinorShift;
         } else {
             dev = MKDEV(MD_MAJOR, rdev0->preferred_minor);
             unit = MINOR(dev);
         }
         if (rdev0->preferred_minor != unit) {
             pr_warn("md: unit number in %pg is bad: %d\n",
                 rdev0->bdev, rdev0->preferred_minor);
             break;
         }
 
         mddev = md_alloc(dev, NULL);
         if (IS_ERR(mddev))
             break;
 
         if (mddev_lock(mddev))
             pr_warn("md: %s locked, cannot run\n", mdname(mddev));
         else if (mddev->raid_disks || mddev->major_version
              || !list_empty(&mddev->disks)) {
             pr_warn("md: %s already running, cannot run %pg\n",
                 mdname(mddev), rdev0->bdev);
             mddev_unlock(mddev);
         } else {
             pr_debug("md: created %s\n", mdname(mddev));
             mddev->persistent = 1;
             rdev_for_each_list(rdev, tmp, &candidates) {
                 list_del_init(&rdev->same_set);
                 if (bind_rdev_to_array(rdev, mddev))
                     export_rdev(rdev);
             }
             autorun_array(mddev);
             mddev_unlock(mddev);
         }
         /* on success, candidates will be empty, on error
          * it won't...
          */
         rdev_for_each_list(rdev, tmp, &candidates) {
             list_del_init(&rdev->same_set);
             export_rdev(rdev);
         }
         mddev_put(mddev);
     }
     pr_info("md: ... autorun DONE.\n");
 }
 #endif /* !MODULE */
 
 static int get_version(void __user *arg)
 {
     mdu_version_t ver;
 
     ver.major = MD_MAJOR_VERSION;
     ver.minor = MD_MINOR_VERSION;
     ver.patchlevel = MD_PATCHLEVEL_VERSION;
 
     if (copy_to_user(arg, &ver, sizeof(ver)))
         return -EFAULT;
 
     return 0;
 }
 
 static int get_array_info(struct mddev *mddev, void __user *arg)
 {
     mdu_array_info_t info;
     int nr,working,insync,failed,spare;
     struct md_rdev *rdev;
 
     nr = working = insync = failed = spare = 0;
     rcu_read_lock();
     rdev_for_each_rcu(rdev, mddev) {
         nr++;
         if (test_bit(Faulty, &rdev->flags))
             failed++;
         else {
             working++;
             if (test_bit(In_sync, &rdev->flags))
                 insync++;
             else if (test_bit(Journal, &rdev->flags))
                 /* TODO: add journal count to md_u.h */
                 ;
             else
                 spare++;
         }
     }
     rcu_read_unlock();
 
     info.major_version = mddev->major_version;
     info.minor_version = mddev->minor_version;
     info.patch_version = MD_PATCHLEVEL_VERSION;
     info.ctime         = clamp_t(time64_t, mddev->ctime, 0, U32_MAX);
     info.level         = mddev->level;
     info.size          = mddev->dev_sectors / 2;
     if (info.size != mddev->dev_sectors / 2) /* overflow */
         info.size = -1;
     info.nr_disks      = nr;
     info.raid_disks    = mddev->raid_disks;
     info.md_minor      = mddev->md_minor;
     info.not_persistent= !mddev->persistent;
 
     info.utime         = clamp_t(time64_t, mddev->utime, 0, U32_MAX);
     info.state         = 0;
     if (mddev->in_sync)
         info.state = (1<<MD_SB_CLEAN);
     if (mddev->bitmap && mddev->bitmap_info.offset)
         info.state |= (1<<MD_SB_BITMAP_PRESENT);
     if (mddev_is_clustered(mddev))
         info.state |= (1<<MD_SB_CLUSTERED);
     info.active_disks  = insync;
     info.working_disks = working;
     info.failed_disks  = failed;
     info.spare_disks   = spare;
 
     info.layout        = mddev->layout;
     info.chunk_size    = mddev->chunk_sectors << 9;
 
     if (copy_to_user(arg, &info, sizeof(info)))
         return -EFAULT;
 
     return 0;
 }
 
 static int get_bitmap_file(struct mddev *mddev, void __user * arg)
 {
     mdu_bitmap_file_t *file = NULL; /* too big for stack allocation */
     char *ptr;
     int err;
 
     file = kzalloc(sizeof(*file), GFP_NOIO);
     if (!file)
         return -ENOMEM;
 
     err = 0;
     spin_lock(&mddev->lock);
     /* bitmap enabled */
     if (mddev->bitmap_info.file) {
         ptr = file_path(mddev->bitmap_info.file, file->pathname,
                 sizeof(file->pathname));
         if (IS_ERR(ptr))
             err = PTR_ERR(ptr);
         else
             memmove(file->pathname, ptr,
                 sizeof(file->pathname)-(ptr-file->pathname));
     }
     spin_unlock(&mddev->lock);
 
     if (err == 0 &&
         copy_to_user(arg, file, sizeof(*file)))
         err = -EFAULT;
 
     kfree(file);
     return err;
 }
 
 static int get_disk_info(struct mddev *mddev, void __user * arg)
 {
     mdu_disk_info_t info;
     struct md_rdev *rdev;
 
     if (copy_from_user(&info, arg, sizeof(info)))
         return -EFAULT;
 
     rcu_read_lock();
     rdev = md_find_rdev_nr_rcu(mddev, info.number);
     if (rdev) {
         info.major = MAJOR(rdev->bdev->bd_dev);
         info.minor = MINOR(rdev->bdev->bd_dev);
         info.raid_disk = rdev->raid_disk;
         info.state = 0;
         if (test_bit(Faulty, &rdev->flags))
             info.state |= (1<<MD_DISK_FAULTY);
         else if (test_bit(In_sync, &rdev->flags)) {
             info.state |= (1<<MD_DISK_ACTIVE);
             info.state |= (1<<MD_DISK_SYNC);
         }
         if (test_bit(Journal, &rdev->flags))
             info.state |= (1<<MD_DISK_JOURNAL);
         if (test_bit(WriteMostly, &rdev->flags))
             info.state |= (1<<MD_DISK_WRITEMOSTLY);
         if (test_bit(FailFast, &rdev->flags))
             info.state |= (1<<MD_DISK_FAILFAST);
     } else {
         info.major = info.minor = 0;
         info.raid_disk = -1;
         info.state = (1<<MD_DISK_REMOVED);
     }
     rcu_read_unlock();
 
     if (copy_to_user(arg, &info, sizeof(info)))
         return -EFAULT;
 
     return 0;
 }
 
 int md_add_new_disk(struct mddev *mddev, struct mdu_disk_info_s *info)
 {
     struct md_rdev *rdev;
     dev_t dev = MKDEV(info->major,info->minor);
 
     if (mddev_is_clustered(mddev) &&
         !(info->state & ((1 << MD_DISK_CLUSTER_ADD) | (1 << MD_DISK_CANDIDATE)))) {
         pr_warn("%s: Cannot add to clustered mddev.\n",
             mdname(mddev));
         return -EINVAL;
     }
 
     if (info->major != MAJOR(dev) || info->minor != MINOR(dev))
         return -EOVERFLOW;
 
     if (!mddev->raid_disks) {
         int err;
         /* expecting a device which has a superblock */
         rdev = md_import_device(dev, mddev->major_version, mddev->minor_version);
         if (IS_ERR(rdev)) {
             pr_warn("md: md_import_device returned %ld\n",
                 PTR_ERR(rdev));
             return PTR_ERR(rdev);
         }
         if (!list_empty(&mddev->disks)) {
             struct md_rdev *rdev0
                 = list_entry(mddev->disks.next,
                          struct md_rdev, same_set);
             err = super_types[mddev->major_version]
                 .load_super(rdev, rdev0, mddev->minor_version);
             if (err < 0) {
                 pr_warn("md: %pg has different UUID to %pg\n",
                     rdev->bdev,
                     rdev0->bdev);
                 export_rdev(rdev);
                 return -EINVAL;
             }
         }
         err = bind_rdev_to_array(rdev, mddev);
         if (err)
             export_rdev(rdev);
         return err;
     }
 
     /*
      * md_add_new_disk can be used once the array is assembled
      * to add "hot spares".  They must already have a superblock
      * written
      */
     if (mddev->pers) {
         int err;
         if (!mddev->pers->hot_add_disk) {
             pr_warn("%s: personality does not support diskops!\n",
                 mdname(mddev));
             return -EINVAL;
         }
         if (mddev->persistent)
             rdev = md_import_device(dev, mddev->major_version,
                         mddev->minor_version);
         else
             rdev = md_import_device(dev, -1, -1);
         if (IS_ERR(rdev)) {
             pr_warn("md: md_import_device returned %ld\n",
                 PTR_ERR(rdev));
             return PTR_ERR(rdev);
         }
         /* set saved_raid_disk if appropriate */
         if (!mddev->persistent) {
             if (info->state & (1<<MD_DISK_SYNC)  &&
                 info->raid_disk < mddev->raid_disks) {
                 rdev->raid_disk = info->raid_disk;
                 set_bit(In_sync, &rdev->flags);
                 clear_bit(Bitmap_sync, &rdev->flags);
             } else
                 rdev->raid_disk = -1;
             rdev->saved_raid_disk = rdev->raid_disk;
         } else
             super_types[mddev->major_version].
                 validate_super(mddev, rdev);
         if ((info->state & (1<<MD_DISK_SYNC)) &&
              rdev->raid_disk != info->raid_disk) {
             /* This was a hot-add request, but events doesn't
              * match, so reject it.
              */
             export_rdev(rdev);
             return -EINVAL;
         }
 
         clear_bit(In_sync, &rdev->flags); /* just to be sure */
         if (info->state & (1<<MD_DISK_WRITEMOSTLY))
             set_bit(WriteMostly, &rdev->flags);
         else
             clear_bit(WriteMostly, &rdev->flags);
         if (info->state & (1<<MD_DISK_FAILFAST))
             set_bit(FailFast, &rdev->flags);
         else
             clear_bit(FailFast, &rdev->flags);
 
         if (info->state & (1<<MD_DISK_JOURNAL)) {
             struct md_rdev *rdev2;
             bool has_journal = false;
 
             /* make sure no existing journal disk */
             rdev_for_each(rdev2, mddev) {
                 if (test_bit(Journal, &rdev2->flags)) {
                     has_journal = true;
                     break;
                 }
             }
             if (has_journal || mddev->bitmap) {
                 export_rdev(rdev);
                 return -EBUSY;
             }
             set_bit(Journal, &rdev->flags);
         }
         /*
          * check whether the device shows up in other nodes
          */
         if (mddev_is_clustered(mddev)) {
             if (info->state & (1 << MD_DISK_CANDIDATE))
                 set_bit(Candidate, &rdev->flags);
             else if (info->state & (1 << MD_DISK_CLUSTER_ADD)) {
                 /* --add initiated by this node */
                 err = md_cluster_ops->add_new_disk(mddev, rdev);
                 if (err) {
                     export_rdev(rdev);
                     return err;
                 }
             }
         }
 
         rdev->raid_disk = -1;
         err = bind_rdev_to_array(rdev, mddev);
 
         if (err)
             export_rdev(rdev);
 
         if (mddev_is_clustered(mddev)) {
             if (info->state & (1 << MD_DISK_CANDIDATE)) {
                 if (!err) {
                     err = md_cluster_ops->new_disk_ack(mddev,
                         err == 0);
                     if (err)
                         md_kick_rdev_from_array(rdev);
                 }
             } else {
                 if (err)
                     md_cluster_ops->add_new_disk_cancel(mddev);
                 else
                     err = add_bound_rdev(rdev);
             }
 
         } else if (!err)
             err = add_bound_rdev(rdev);
 
         return err;
     }
 
     /* otherwise, md_add_new_disk is only allowed
      * for major_version==0 superblocks
      */
     if (mddev->major_version != 0) {
         pr_warn("%s: ADD_NEW_DISK not supported\n", mdname(mddev));
         return -EINVAL;
     }
 
     if (!(info->state & (1<<MD_DISK_FAULTY))) {
         int err;
         rdev = md_import_device(dev, -1, 0);
         if (IS_ERR(rdev)) {
             pr_warn("md: error, md_import_device() returned %ld\n",
                 PTR_ERR(rdev));
             return PTR_ERR(rdev);
         }
         rdev->desc_nr = info->number;
         if (info->raid_disk < mddev->raid_disks)
             rdev->raid_disk = info->raid_disk;
         else
             rdev->raid_disk = -1;
 
         if (rdev->raid_disk < mddev->raid_disks)
             if (info->state & (1<<MD_DISK_SYNC))
                 set_bit(In_sync, &rdev->flags);
 
         if (info->state & (1<<MD_DISK_WRITEMOSTLY))
             set_bit(WriteMostly, &rdev->flags);
         if (info->state & (1<<MD_DISK_FAILFAST))
             set_bit(FailFast, &rdev->flags);
 
         if (!mddev->persistent) {
             pr_debug("md: nonpersistent superblock ...\n");
             rdev->sb_start = bdev_nr_sectors(rdev->bdev);
         } else
             rdev->sb_start = calc_dev_sboffset(rdev);
         rdev->sectors = rdev->sb_start;
 
         err = bind_rdev_to_array(rdev, mddev);
         if (err) {
             export_rdev(rdev);
             return err;
         }
     }
 
     return 0;
 }
 
 static int hot_remove_disk(struct mddev *mddev, dev_t dev)
 {
     struct md_rdev *rdev;
 
     if (!mddev->pers)
         return -ENODEV;
 
     rdev = find_rdev(mddev, dev);
     if (!rdev)
         return -ENXIO;
 
     if (rdev->raid_disk < 0)
         goto kick_rdev;
 
     clear_bit(Blocked, &rdev->flags);
     remove_and_add_spares(mddev, rdev);
 
     if (rdev->raid_disk >= 0)
         goto busy;
 
 kick_rdev:
     if (mddev_is_clustered(mddev)) {
         if (md_cluster_ops->remove_disk(mddev, rdev))
             goto busy;
     }
 
     md_kick_rdev_from_array(rdev);
     set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
     if (mddev->thread)
         md_wakeup_thread(mddev->thread);
     else
         md_update_sb(mddev, 1);
     md_new_event();
 
     return 0;
 busy:
     pr_debug("md: cannot remove active disk %pg from %s ...\n",
          rdev->bdev, mdname(mddev));
     return -EBUSY;
 }
 
 static int hot_add_disk(struct mddev *mddev, dev_t dev)
 {
     int err;
     struct md_rdev *rdev;
 
     if (!mddev->pers)
         return -ENODEV;
 
     if (mddev->major_version != 0) {
         pr_warn("%s: HOT_ADD may only be used with version-0 superblocks.\n",
             mdname(mddev));
         return -EINVAL;
     }
     if (!mddev->pers->hot_add_disk) {
         pr_warn("%s: personality does not support diskops!\n",
             mdname(mddev));
         return -EINVAL;
     }
 
     rdev = md_import_device(dev, -1, 0);
     if (IS_ERR(rdev)) {
         pr_warn("md: error, md_import_device() returned %ld\n",
             PTR_ERR(rdev));
         return -EINVAL;
     }
 
     if (mddev->persistent)
         rdev->sb_start = calc_dev_sboffset(rdev);
     else
         rdev->sb_start = bdev_nr_sectors(rdev->bdev);
 
     rdev->sectors = rdev->sb_start;
 
     if (test_bit(Faulty, &rdev->flags)) {
         pr_warn("md: can not hot-add faulty %pg disk to %s!\n",
             rdev->bdev, mdname(mddev));
         err = -EINVAL;
         goto abort_export;
     }
 
     clear_bit(In_sync, &rdev->flags);
     rdev->desc_nr = -1;
     rdev->saved_raid_disk = -1;
     err = bind_rdev_to_array(rdev, mddev);
     if (err)
         goto abort_export;
 
     /*
      * The rest should better be atomic, we can have disk failures
      * noticed in interrupt contexts ...
      */
 
     rdev->raid_disk = -1;
 
     set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
     if (!mddev->thread)
         md_update_sb(mddev, 1);
     /*
      * If the new disk does not support REQ_NOWAIT,
      * disable on the whole MD.
      */
     if (!blk_queue_nowait(bdev_get_queue(rdev->bdev))) {
         pr_info("%s: Disabling nowait because %pg does not support nowait\n",
             mdname(mddev), rdev->bdev);
         blk_queue_flag_clear(QUEUE_FLAG_NOWAIT, mddev->queue);
     }
     /*
      * Kick recovery, maybe this spare has to be added to the
      * array immediately.
      */
     set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
     md_wakeup_thread(mddev->thread);
     md_new_event();
     return 0;
 
 abort_export:
     export_rdev(rdev);
     return err;
 }
 
 static int set_bitmap_file(struct mddev *mddev, int fd)
 {
     int err = 0;
 
     if (mddev->pers) {
         if (!mddev->pers->quiesce || !mddev->thread)
             return -EBUSY;
         if (mddev->recovery || mddev->sync_thread)
             return -EBUSY;
         /* we should be able to change the bitmap.. */
     }
 
     if (fd >= 0) {
         struct inode *inode;
         struct file *f;
 
         if (mddev->bitmap || mddev->bitmap_info.file)
             return -EEXIST; /* cannot add when bitmap is present */
         f = fget(fd);
 
         if (f == NULL) {
             pr_warn("%s: error: failed to get bitmap file\n",
                 mdname(mddev));
             return -EBADF;
         }
 
         inode = f->f_mapping->host;
         if (!S_ISREG(inode->i_mode)) {
             pr_warn("%s: error: bitmap file must be a regular file\n",
                 mdname(mddev));
             err = -EBADF;
         } else if (!(f->f_mode & FMODE_WRITE)) {
             pr_warn("%s: error: bitmap file must open for write\n",
                 mdname(mddev));
             err = -EBADF;
         } else if (atomic_read(&inode->i_writecount) != 1) {
             pr_warn("%s: error: bitmap file is already in use\n",
                 mdname(mddev));
             err = -EBUSY;
         }
         if (err) {
             fput(f);
             return err;
         }
         mddev->bitmap_info.file = f;
         mddev->bitmap_info.offset = 0; /* file overrides offset */
     } else if (mddev->bitmap == NULL)
         return -ENOENT; /* cannot remove what isn't there */
     err = 0;
     if (mddev->pers) {
         if (fd >= 0) {
             struct bitmap *bitmap;
 
             bitmap = md_bitmap_create(mddev, -1);
             mddev_suspend(mddev);
             if (!IS_ERR(bitmap)) {
                 mddev->bitmap = bitmap;
                 err = md_bitmap_load(mddev);
             } else
                 err = PTR_ERR(bitmap);
             if (err) {
                 md_bitmap_destroy(mddev);
                 fd = -1;
             }
             mddev_resume(mddev);
         } else if (fd < 0) {
             mddev_suspend(mddev);
             md_bitmap_destroy(mddev);
             mddev_resume(mddev);
         }
     }
     if (fd < 0) {
         struct file *f = mddev->bitmap_info.file;
         if (f) {
             spin_lock(&mddev->lock);
             mddev->bitmap_info.file = NULL;
             spin_unlock(&mddev->lock);
             fput(f);
         }
     }
 
     return err;
 }
 
 /*
  * md_set_array_info is used two different ways
  * The original usage is when creating a new array.
  * In this usage, raid_disks is > 0 and it together with
  *  level, size, not_persistent,layout,chunksize determine the
  *  shape of the array.
  *  This will always create an array with a type-0.90.0 superblock.
  * The newer usage is when assembling an array.
  *  In this case raid_disks will be 0, and the major_version field is
  *  use to determine which style super-blocks are to be found on the devices.
  *  The minor and patch _version numbers are also kept incase the
  *  super_block handler wishes to interpret them.
  */
 int md_set_array_info(struct mddev *mddev, struct mdu_array_info_s *info)
 {
     if (info->raid_disks == 0) {
         /* just setting version number for superblock loading */
         if (info->major_version < 0 ||
             info->major_version >= ARRAY_SIZE(super_types) ||
             super_types[info->major_version].name == NULL) {
             /* maybe try to auto-load a module? */
             pr_warn("md: superblock version %d not known\n",
                 info->major_version);
             return -EINVAL;
         }
         mddev->major_version = info->major_version;
         mddev->minor_version = info->minor_version;
         mddev->patch_version = info->patch_version;
         mddev->persistent = !info->not_persistent;
         /* ensure mddev_put doesn't delete this now that there
          * is some minimal configuration.
          */
         mddev->ctime         = ktime_get_real_seconds();
         return 0;
     }
     mddev->major_version = MD_MAJOR_VERSION;
     mddev->minor_version = MD_MINOR_VERSION;
     mddev->patch_version = MD_PATCHLEVEL_VERSION;
     mddev->ctime         = ktime_get_real_seconds();
 
     mddev->level         = info->level;
     mddev->clevel[0]     = 0;
     mddev->dev_sectors   = 2 * (sector_t)info->size;
     mddev->raid_disks    = info->raid_disks;
     /* don't set md_minor, it is determined by which /dev/md* was
      * openned
      */
     if (info->state & (1<<MD_SB_CLEAN))
         mddev->recovery_cp = MaxSector;
     else
         mddev->recovery_cp = 0;
     mddev->persistent    = ! info->not_persistent;
     mddev->external      = 0;
 
     mddev->layout        = info->layout;
     if (mddev->level == 0)
         /* Cannot trust RAID0 layout info here */
         mddev->layout = -1;
     mddev->chunk_sectors = info->chunk_size >> 9;
 
     if (mddev->persistent) {
         mddev->max_disks = MD_SB_DISKS;
         mddev->flags = 0;
         mddev->sb_flags = 0;
     }
     set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
 
     mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
     mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
     mddev->bitmap_info.offset = 0;
 
     mddev->reshape_position = MaxSector;
 
     /*
      * Generate a 128 bit UUID
      */
     get_random_bytes(mddev->uuid, 16);
 
     mddev->new_level = mddev->level;
     mddev->new_chunk_sectors = mddev->chunk_sectors;
     mddev->new_layout = mddev->layout;
     mddev->delta_disks = 0;
     mddev->reshape_backwards = 0;
 
     return 0;
 }
 
 void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors)
 {
     lockdep_assert_held(&mddev->reconfig_mutex);
 
     if (mddev->external_size)
         return;
 
     mddev->array_sectors = array_sectors;
 }
 EXPORT_SYMBOL(md_set_array_sectors);
 
 static int update_size(struct mddev *mddev, sector_t num_sectors)
 {
     struct md_rdev *rdev;
     int rv;
     int fit = (num_sectors == 0);
     sector_t old_dev_sectors = mddev->dev_sectors;
 
     if (mddev->pers->resize == NULL)
         return -EINVAL;
     /* The "num_sectors" is the number of sectors of each device that
      * is used.  This can only make sense for arrays with redundancy.
      * linear and raid0 always use whatever space is available. We can only
      * consider changing this number if no resync or reconstruction is
      * happening, and if the new size is acceptable. It must fit before the
      * sb_start or, if that is <data_offset, it must fit before the size
      * of each device.  If num_sectors is zero, we find the largest size
      * that fits.
      */
     if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
         mddev->sync_thread)
         return -EBUSY;
     if (mddev->ro)
         return -EROFS;
 
     rdev_for_each(rdev, mddev) {
         sector_t avail = rdev->sectors;
 
         if (fit && (num_sectors == 0 || num_sectors > avail))
             num_sectors = avail;
         if (avail < num_sectors)
             return -ENOSPC;
     }
     rv = mddev->pers->resize(mddev, num_sectors);
     if (!rv) {
         if (mddev_is_clustered(mddev))
             md_cluster_ops->update_size(mddev, old_dev_sectors);
         else if (mddev->queue) {
             set_capacity_and_notify(mddev->gendisk,
                         mddev->array_sectors);
         }
     }
     return rv;
 }
 
 static int update_raid_disks(struct mddev *mddev, int raid_disks)
 {
     int rv;
     struct md_rdev *rdev;
     /* change the number of raid disks */
     if (mddev->pers->check_reshape == NULL)
         return -EINVAL;
     if (mddev->ro)
         return -EROFS;
     if (raid_disks <= 0 ||
         (mddev->max_disks && raid_disks >= mddev->max_disks))
         return -EINVAL;
     if (mddev->sync_thread ||
         test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
         test_bit(MD_RESYNCING_REMOTE, &mddev->recovery) ||
         mddev->reshape_position != MaxSector)
         return -EBUSY;
 
     rdev_for_each(rdev, mddev) {
         if (mddev->raid_disks < raid_disks &&
             rdev->data_offset < rdev->new_data_offset)
             return -EINVAL;
         if (mddev->raid_disks > raid_disks &&
             rdev->data_offset > rdev->new_data_offset)
             return -EINVAL;
     }
 
     mddev->delta_disks = raid_disks - mddev->raid_disks;
     if (mddev->delta_disks < 0)
         mddev->reshape_backwards = 1;
     else if (mddev->delta_disks > 0)
         mddev->reshape_backwards = 0;
 
     rv = mddev->pers->check_reshape(mddev);
     if (rv < 0) {
         mddev->delta_disks = 0;
         mddev->reshape_backwards = 0;
     }
     return rv;
 }
 
 /*
  * update_array_info is used to change the configuration of an
  * on-line array.
  * The version, ctime,level,size,raid_disks,not_persistent, layout,chunk_size
  * fields in the info are checked against the array.
  * Any differences that cannot be handled will cause an error.
  * Normally, only one change can be managed at a time.
  */
 static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
 {
     int rv = 0;
     int cnt = 0;
     int state = 0;
 
     /* calculate expected state,ignoring low bits */
     if (mddev->bitmap && mddev->bitmap_info.offset)
         state |= (1 << MD_SB_BITMAP_PRESENT);
 
     if (mddev->major_version != info->major_version ||
         mddev->minor_version != info->minor_version ||
 /*      mddev->patch_version != info->patch_version || */
         mddev->ctime         != info->ctime         ||
         mddev->level         != info->level         ||
 /*      mddev->layout        != info->layout        || */
         mddev->persistent    != !info->not_persistent ||
         mddev->chunk_sectors != info->chunk_size >> 9 ||
         /* ignore bottom 8 bits of state, and allow SB_BITMAP_PRESENT to change */
         ((state^info->state) & 0xfffffe00)
         )
         return -EINVAL;
     /* Check there is only one change */
     if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
         cnt++;
     if (mddev->raid_disks != info->raid_disks)
         cnt++;
     if (mddev->layout != info->layout)
         cnt++;
     if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT))
         cnt++;
     if (cnt == 0)
         return 0;
     if (cnt > 1)
         return -EINVAL;
 
     if (mddev->layout != info->layout) {
         /* Change layout
          * we don't need to do anything at the md level, the
          * personality will take care of it all.
          */
         if (mddev->pers->check_reshape == NULL)
             return -EINVAL;
         else {
             mddev->new_layout = info->layout;
             rv = mddev->pers->check_reshape(mddev);
             if (rv)
                 mddev->new_layout = mddev->layout;
             return rv;
         }
     }
     if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
         rv = update_size(mddev, (sector_t)info->size * 2);
 
     if (mddev->raid_disks    != info->raid_disks)
         rv = update_raid_disks(mddev, info->raid_disks);
 
     if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT)) {
         if (mddev->pers->quiesce == NULL || mddev->thread == NULL) {
             rv = -EINVAL;
             goto err;
         }
         if (mddev->recovery || mddev->sync_thread) {
             rv = -EBUSY;
             goto err;
         }
         if (info->state & (1<<MD_SB_BITMAP_PRESENT)) {
             struct bitmap *bitmap;
             /* add the bitmap */
             if (mddev->bitmap) {
                 rv = -EEXIST;
                 goto err;
             }
             if (mddev->bitmap_info.default_offset == 0) {
                 rv = -EINVAL;
                 goto err;
             }
             mddev->bitmap_info.offset =
                 mddev->bitmap_info.default_offset;
             mddev->bitmap_info.space =
                 mddev->bitmap_info.default_space;
             bitmap = md_bitmap_create(mddev, -1);
             mddev_suspend(mddev);
             if (!IS_ERR(bitmap)) {
                 mddev->bitmap = bitmap;
                 rv = md_bitmap_load(mddev);
             } else
                 rv = PTR_ERR(bitmap);
             if (rv)
                 md_bitmap_destroy(mddev);
             mddev_resume(mddev);
         } else {
             /* remove the bitmap */
             if (!mddev->bitmap) {
                 rv = -ENOENT;
                 goto err;
             }
             if (mddev->bitmap->storage.file) {
                 rv = -EINVAL;
                 goto err;
             }
             if (mddev->bitmap_info.nodes) {
                 /* hold PW on all the bitmap lock */
                 if (md_cluster_ops->lock_all_bitmaps(mddev) <= 0) {
                     pr_warn("md: can't change bitmap to none since the array is in use by more than one node\n");
                     rv = -EPERM;
                     md_cluster_ops->unlock_all_bitmaps(mddev);
                     goto err;
                 }
 
                 mddev->bitmap_info.nodes = 0;
                 md_cluster_ops->leave(mddev);
                 module_put(md_cluster_mod);
                 mddev->safemode_delay = DEFAULT_SAFEMODE_DELAY;
             }
             mddev_suspend(mddev);
             md_bitmap_destroy(mddev);
             mddev_resume(mddev);
             mddev->bitmap_info.offset = 0;
         }
     }
     md_update_sb(mddev, 1);
     return rv;
 err:
     return rv;
 }
 
 static int set_disk_faulty(struct mddev *mddev, dev_t dev)
 {
     struct md_rdev *rdev;
     int err = 0;
 
     if (mddev->pers == NULL)
         return -ENODEV;
 
     rcu_read_lock();
     rdev = md_find_rdev_rcu(mddev, dev);
     if (!rdev)
         err =  -ENODEV;
     else {
         md_error(mddev, rdev);
         if (test_bit(MD_BROKEN, &mddev->flags))
             err = -EBUSY;
     }
     rcu_read_unlock();
     return err;
 }
 
 /*
  * We have a problem here : there is no easy way to give a CHS
  * virtual geometry. We currently pretend that we have a 2 heads
  * 4 sectors (with a BIG number of cylinders...). This drives
  * dosfs just mad... ;-)
  */
 static int md_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {
     struct mddev *mddev = bdev->bd_disk->private_data;
 
     geo->heads = 2;
     geo->sectors = 4;
     geo->cylinders = mddev->array_sectors / 8;
     return 0;
 }
 
 static inline bool md_ioctl_valid(unsigned int cmd)
 {
     switch (cmd) {
     case ADD_NEW_DISK:
     case GET_ARRAY_INFO:
     case GET_BITMAP_FILE:
     case GET_DISK_INFO:
     case HOT_ADD_DISK:
     case HOT_REMOVE_DISK:
     case RAID_VERSION:
     case RESTART_ARRAY_RW:
     case RUN_ARRAY:
     case SET_ARRAY_INFO:
     case SET_BITMAP_FILE:
     case SET_DISK_FAULTY:
     case STOP_ARRAY:
     case STOP_ARRAY_RO:
     case CLUSTERED_DISK_NACK:
         return true;
     default:
         return false;
     }
 }
 
 static int md_ioctl(struct block_device *bdev, fmode_t mode,
             unsigned int cmd, unsigned long arg)
 {
     int err = 0;
     void __user *argp = (void __user *)arg;
     struct mddev *mddev = NULL;
     bool did_set_md_closing = false;
 
     if (!md_ioctl_valid(cmd))
         return -ENOTTY;
 
     switch (cmd) {
     case RAID_VERSION:
     case GET_ARRAY_INFO:
     case GET_DISK_INFO:
         break;
     default:
         if (!capable(CAP_SYS_ADMIN))
             return -EACCES;
     }
 
     /*
      * Commands dealing with the RAID driver but not any
      * particular array:
      */
     switch (cmd) {
     case RAID_VERSION:
         err = get_version(argp);
         goto out;
     default:;
     }
 
     /*
      * Commands creating/starting a new array:
      */
 
     mddev = bdev->bd_disk->private_data;
 
     if (!mddev) {
         BUG();
         goto out;
     }
 
     /* Some actions do not requires the mutex */
     switch (cmd) {
     case GET_ARRAY_INFO:
         if (!mddev->raid_disks && !mddev->external)
             err = -ENODEV;
         else
             err = get_array_info(mddev, argp);
         goto out;
 
     case GET_DISK_INFO:
         if (!mddev->raid_disks && !mddev->external)
             err = -ENODEV;
         else
             err = get_disk_info(mddev, argp);
         goto out;
 
     case SET_DISK_FAULTY:
         err = set_disk_faulty(mddev, new_decode_dev(arg));
         goto out;
 
     case GET_BITMAP_FILE:
         err = get_bitmap_file(mddev, argp);
         goto out;
 
     }
 
     if (cmd == ADD_NEW_DISK || cmd == HOT_ADD_DISK)
         flush_rdev_wq(mddev);
 
     if (cmd == HOT_REMOVE_DISK)
         /* need to ensure recovery thread has run */
         wait_event_interruptible_timeout(mddev->sb_wait,
                          !test_bit(MD_RECOVERY_NEEDED,
                                &mddev->recovery),
                          msecs_to_jiffies(5000));
     if (cmd == STOP_ARRAY || cmd == STOP_ARRAY_RO) {
         /* Need to flush page cache, and ensure no-one else opens
          * and writes
          */
         mutex_lock(&mddev->open_mutex);
         if (mddev->pers && atomic_read(&mddev->openers) > 1) {
             mutex_unlock(&mddev->open_mutex);
             err = -EBUSY;
             goto out;
         }
         if (test_and_set_bit(MD_CLOSING, &mddev->flags)) {
             mutex_unlock(&mddev->open_mutex);
             err = -EBUSY;
             goto out;
         }
         did_set_md_closing = true;
         mutex_unlock(&mddev->open_mutex);
         sync_blockdev(bdev);
     }
     err = mddev_lock(mddev);
     if (err) {
         pr_debug("md: ioctl lock interrupted, reason %d, cmd %d\n",
              err, cmd);
         goto out;
     }
 
     if (cmd == SET_ARRAY_INFO) {
         mdu_array_info_t info;
         if (!arg)
             memset(&info, 0, sizeof(info));
         else if (copy_from_user(&info, argp, sizeof(info))) {
             err = -EFAULT;
             goto unlock;
         }
         if (mddev->pers) {
             err = update_array_info(mddev, &info);
             if (err) {
                 pr_warn("md: couldn't update array info. %d\n", err);
                 goto unlock;
             }
             goto unlock;
         }
         if (!list_empty(&mddev->disks)) {
             pr_warn("md: array %s already has disks!\n", mdname(mddev));
             err = -EBUSY;
             goto unlock;
         }
         if (mddev->raid_disks) {
             pr_warn("md: array %s already initialised!\n", mdname(mddev));
             err = -EBUSY;
             goto unlock;
         }
         err = md_set_array_info(mddev, &info);
         if (err) {
             pr_warn("md: couldn't set array info. %d\n", err);
             goto unlock;
         }
         goto unlock;
     }
 
     /*
      * Commands querying/configuring an existing array:
      */
     /* if we are not initialised yet, only ADD_NEW_DISK, STOP_ARRAY,
      * RUN_ARRAY, and GET_ and SET_BITMAP_FILE are allowed */
     if ((!mddev->raid_disks && !mddev->external)
         && cmd != ADD_NEW_DISK && cmd != STOP_ARRAY
         && cmd != RUN_ARRAY && cmd != SET_BITMAP_FILE
         && cmd != GET_BITMAP_FILE) {
         err = -ENODEV;
         goto unlock;
     }
 
     /*
      * Commands even a read-only array can execute:
      */
     switch (cmd) {
     case RESTART_ARRAY_RW:
         err = restart_array(mddev);
         goto unlock;
 
     case STOP_ARRAY:
         err = do_md_stop(mddev, 0, bdev);
         goto unlock;
 
     case STOP_ARRAY_RO:
         err = md_set_readonly(mddev, bdev);
         goto unlock;
 
     case HOT_REMOVE_DISK:
         err = hot_remove_disk(mddev, new_decode_dev(arg));
         goto unlock;
 
     case ADD_NEW_DISK:
         /* We can support ADD_NEW_DISK on read-only arrays
          * only if we are re-adding a preexisting device.
          * So require mddev->pers and MD_DISK_SYNC.
          */
         if (mddev->pers) {
             mdu_disk_info_t info;
             if (copy_from_user(&info, argp, sizeof(info)))
                 err = -EFAULT;
             else if (!(info.state & (1<<MD_DISK_SYNC)))
                 /* Need to clear read-only for this */
                 break;
             else
                 err = md_add_new_disk(mddev, &info);
             goto unlock;
         }
         break;
     }
 
     /*
      * The remaining ioctls are changing the state of the
      * superblock, so we do not allow them on read-only arrays.
      */
     if (mddev->ro && mddev->pers) {
         if (mddev->ro == 2) {
             mddev->ro = 0;
             sysfs_notify_dirent_safe(mddev->sysfs_state);
             set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
             /* mddev_unlock will wake thread */
             /* If a device failed while we were read-only, we
              * need to make sure the metadata is updated now.
              */
             if (test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)) {
                 mddev_unlock(mddev);
                 wait_event(mddev->sb_wait,
                        !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags) &&
                        !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags));
                 mddev_lock_nointr(mddev);
             }
         } else {
             err = -EROFS;
             goto unlock;
         }
     }
 
     switch (cmd) {
     case ADD_NEW_DISK:
     {
         mdu_disk_info_t info;
         if (copy_from_user(&info, argp, sizeof(info)))
             err = -EFAULT;
         else
             err = md_add_new_disk(mddev, &info);
         goto unlock;
     }
 
     case CLUSTERED_DISK_NACK:
         if (mddev_is_clustered(mddev))
             md_cluster_ops->new_disk_ack(mddev, false);
         else
             err = -EINVAL;
         goto unlock;
 
     case HOT_ADD_DISK:
         err = hot_add_disk(mddev, new_decode_dev(arg));
         goto unlock;
 
     case RUN_ARRAY:
         err = do_md_run(mddev);
         goto unlock;
 
     case SET_BITMAP_FILE:
         err = set_bitmap_file(mddev, (int)arg);
         goto unlock;
 
     default:
         err = -EINVAL;
         goto unlock;
     }
 
 unlock:
     if (mddev->hold_active == UNTIL_IOCTL &&
         err != -EINVAL)
         mddev->hold_active = 0;
     mddev_unlock(mddev);
 out:
     if(did_set_md_closing)
         clear_bit(MD_CLOSING, &mddev->flags);
     return err;
 }
 #ifdef CONFIG_COMPAT
 static int md_compat_ioctl(struct block_device *bdev, fmode_t mode,
             unsigned int cmd, unsigned long arg)
 {
     switch (cmd) {
     case HOT_REMOVE_DISK:
     case HOT_ADD_DISK:
     case SET_DISK_FAULTY:
     case SET_BITMAP_FILE:
         /* These take in integer arg, do not convert */
         break;
     default:
         arg = (unsigned long)compat_ptr(arg);
         break;
     }
 
     return md_ioctl(bdev, mode, cmd, arg);
 }
 #endif /* CONFIG_COMPAT */
 
 static int md_set_read_only(struct block_device *bdev, bool ro)
 {
     struct mddev *mddev = bdev->bd_disk->private_data;
     int err;
 
     err = mddev_lock(mddev);
     if (err)
         return err;
 
     if (!mddev->raid_disks && !mddev->external) {
         err = -ENODEV;
         goto out_unlock;
     }
 
     /*
      * Transitioning to read-auto need only happen for arrays that call
      * md_write_start and which are not ready for writes yet.
      */
     if (!ro && mddev->ro == 1 && mddev->pers) {
         err = restart_array(mddev);
         if (err)
             goto out_unlock;
         mddev->ro = 2;
     }
 
 out_unlock:
     mddev_unlock(mddev);
     return err;
 }
 
 static int md_open(struct block_device *bdev, fmode_t mode)
 {
     struct mddev *mddev;
     int err;
 
     spin_lock(&all_mddevs_lock);
     mddev = mddev_get(bdev->bd_disk->private_data);
     spin_unlock(&all_mddevs_lock);
     if (!mddev)
         return -ENODEV;
 
     err = mutex_lock_interruptible(&mddev->open_mutex);
     if (err)
         goto out;
 
     err = -ENODEV;
     if (test_bit(MD_CLOSING, &mddev->flags))
         goto out_unlock;
 
     atomic_inc(&mddev->openers);
     mutex_unlock(&mddev->open_mutex);
 
     bdev_check_media_change(bdev);
     return 0;
 
 out_unlock:
     mutex_unlock(&mddev->open_mutex);
 out:
     mddev_put(mddev);
     return err;
 }
 
 static void md_release(struct gendisk *disk, fmode_t mode)
 {
     struct mddev *mddev = disk->private_data;
 
     BUG_ON(!mddev);
     atomic_dec(&mddev->openers);
     mddev_put(mddev);
 }
 
 static unsigned int md_check_events(struct gendisk *disk, unsigned int clearing)
 {
     struct mddev *mddev = disk->private_data;
     unsigned int ret = 0;
 
     if (mddev->changed)
         ret = DISK_EVENT_MEDIA_CHANGE;
     mddev->changed = 0;
     return ret;
 }
 
 static void md_free_disk(struct gendisk *disk)
 {
     struct mddev *mddev = disk->private_data;
 
     percpu_ref_exit(&mddev->writes_pending);
     bioset_exit(&mddev->bio_set);
     bioset_exit(&mddev->sync_set);
 
     mddev_free(mddev);
 }
 
 const struct block_device_operations md_fops =
 {
     .owner      = THIS_MODULE,
     .submit_bio = md_submit_bio,
     .open       = md_open,
     .release    = md_release,
     .ioctl      = md_ioctl,
 #ifdef CONFIG_COMPAT
     .compat_ioctl   = md_compat_ioctl,
 #endif
     .getgeo     = md_getgeo,
     .check_events   = md_check_events,
     .set_read_only  = md_set_read_only,
     .free_disk  = md_free_disk,
 };
 
 static int md_thread(void *arg)
 {
     struct md_thread *thread = arg;
 
     /*
      * md_thread is a 'system-thread', it's priority should be very
      * high. We avoid resource deadlocks individually in each
      * raid personality. (RAID5 does preallocation) We also use RR and
      * the very same RT priority as kswapd, thus we will never get
      * into a priority inversion deadlock.
      *
      * we definitely have to have equal or higher priority than
      * bdflush, otherwise bdflush will deadlock if there are too
      * many dirty RAID5 blocks.
      */
 
     allow_signal(SIGKILL);
     while (!kthread_should_stop()) {
 
         /* We need to wait INTERRUPTIBLE so that
          * we don't add to the load-average.
          * That means we need to be sure no signals are
          * pending
          */
         if (signal_pending(current))
             flush_signals(current);
 
         wait_event_interruptible_timeout
             (thread->wqueue,
              test_bit(THREAD_WAKEUP, &thread->flags)
              || kthread_should_stop() || kthread_should_park(),
              thread->timeout);
 
         clear_bit(THREAD_WAKEUP, &thread->flags);
         if (kthread_should_park())
             kthread_parkme();
         if (!kthread_should_stop())
             thread->run(thread);
     }
 
     return 0;
 }
 
 void md_wakeup_thread(struct md_thread *thread)
 {
     if (thread) {
         pr_debug("md: waking up MD thread %s.\n", thread->tsk->comm);
         set_bit(THREAD_WAKEUP, &thread->flags);
         wake_up(&thread->wqueue);
     }
 }
 EXPORT_SYMBOL(md_wakeup_thread);
 
 struct md_thread *md_register_thread(void (*run) (struct md_thread *),
         struct mddev *mddev, const char *name)
 {
     struct md_thread *thread;
 
     thread = kzalloc(sizeof(struct md_thread), GFP_KERNEL);
     if (!thread)
         return NULL;
 
     init_waitqueue_head(&thread->wqueue);
 
     thread->run = run;
     thread->mddev = mddev;
     thread->timeout = MAX_SCHEDULE_TIMEOUT;
     thread->tsk = kthread_run(md_thread, thread,
                   "%s_%s",
                   mdname(thread->mddev),
                   name);
     if (IS_ERR(thread->tsk)) {
         kfree(thread);
         return NULL;
     }
     return thread;
 }
 EXPORT_SYMBOL(md_register_thread);
 
 void md_unregister_thread(struct md_thread **threadp)
 {
     struct md_thread *thread;
 
     /*
      * Locking ensures that mddev_unlock does not wake_up a
      * non-existent thread
      */
     spin_lock(&pers_lock);
     thread = *threadp;
     if (!thread) {
         spin_unlock(&pers_lock);
         return;
     }
     *threadp = NULL;
     spin_unlock(&pers_lock);
 
     pr_debug("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk));
     kthread_stop(thread->tsk);
     kfree(thread);
 }
 EXPORT_SYMBOL(md_unregister_thread);
 
 void md_error(struct mddev *mddev, struct md_rdev *rdev)
 {
     if (!rdev || test_bit(Faulty, &rdev->flags))
         return;
 
     if (!mddev->pers || !mddev->pers->error_handler)
         return;
     mddev->pers->error_handler(mddev, rdev);
 
     if (mddev->degraded && !test_bit(MD_BROKEN, &mddev->flags))
         set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
     sysfs_notify_dirent_safe(rdev->sysfs_state);
     set_bit(MD_RECOVERY_INTR, &mddev->recovery);
     if (!test_bit(MD_BROKEN, &mddev->flags)) {
         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
     }
     if (mddev->event_work.func)
         queue_work(md_misc_wq, &mddev->event_work);
     md_new_event();
 }
 EXPORT_SYMBOL(md_error);
 
 /* seq_file implementation /proc/mdstat */
 
 static void status_unused(struct seq_file *seq)
 {
     int i = 0;
     struct md_rdev *rdev;
 
     seq_printf(seq, "unused devices: ");
 
     list_for_each_entry(rdev, &pending_raid_disks, same_set) {
         i++;
         seq_printf(seq, "%pg ", rdev->bdev);
     }
     if (!i)
         seq_printf(seq, "<none>");
 
     seq_printf(seq, "\n");
 }
 
 static int status_resync(struct seq_file *seq, struct mddev *mddev)
 {
     sector_t max_sectors, resync, res;
     unsigned long dt, db = 0;
     sector_t rt, curr_mark_cnt, resync_mark_cnt;
     int scale, recovery_active;
     unsigned int per_milli;
 
     if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
         test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
         max_sectors = mddev->resync_max_sectors;
     else
         max_sectors = mddev->dev_sectors;
 
     resync = mddev->curr_resync;
     if (resync < MD_RESYNC_ACTIVE) {
         if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
             /* Still cleaning up */
             resync = max_sectors;
     } else if (resync > max_sectors) {
         resync = max_sectors;
     } else {
         resync -= atomic_read(&mddev->recovery_active);
         if (resync < MD_RESYNC_ACTIVE) {
             /*
              * Resync has started, but the subtraction has
              * yielded one of the special values. Force it
              * to active to ensure the status reports an
              * active resync.
              */
             resync = MD_RESYNC_ACTIVE;
         }
     }
 
     if (resync == MD_RESYNC_NONE) {
         if (test_bit(MD_RESYNCING_REMOTE, &mddev->recovery)) {
             struct md_rdev *rdev;
 
             rdev_for_each(rdev, mddev)
                 if (rdev->raid_disk >= 0 &&
                     !test_bit(Faulty, &rdev->flags) &&
                     rdev->recovery_offset != MaxSector &&
                     rdev->recovery_offset) {
                     seq_printf(seq, "\trecover=REMOTE");
                     return 1;
                 }
             if (mddev->reshape_position != MaxSector)
                 seq_printf(seq, "\treshape=REMOTE");
             else
                 seq_printf(seq, "\tresync=REMOTE");
             return 1;
         }
         if (mddev->recovery_cp < MaxSector) {
             seq_printf(seq, "\tresync=PENDING");
             return 1;
         }
         return 0;
     }
     if (resync < MD_RESYNC_ACTIVE) {
         seq_printf(seq, "\tresync=DELAYED");
         return 1;
     }
 
     WARN_ON(max_sectors == 0);
     /* Pick 'scale' such that (resync>>scale)*1000 will fit
      * in a sector_t, and (max_sectors>>scale) will fit in a
      * u32, as those are the requirements for sector_div.
      * Thus 'scale' must be at least 10
      */
     scale = 10;
     if (sizeof(sector_t) > sizeof(unsigned long)) {
         while ( max_sectors/2 > (1ULL<<(scale+32)))
             scale++;
     }
     res = (resync>>scale)*1000;
     sector_div(res, (u32)((max_sectors>>scale)+1));
 
     per_milli = res;
     {
         int i, x = per_milli/50, y = 20-x;
         seq_printf(seq, "[");
         for (i = 0; i < x; i++)
             seq_printf(seq, "=");
         seq_printf(seq, ">");
         for (i = 0; i < y; i++)
             seq_printf(seq, ".");
         seq_printf(seq, "] ");
     }
     seq_printf(seq, " %s =%3u.%u%% (%llu/%llu)",
            (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)?
             "reshape" :
             (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)?
              "check" :
              (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ?
               "resync" : "recovery"))),
            per_milli/10, per_milli % 10,
            (unsigned long long) resync/2,
            (unsigned long long) max_sectors/2);
 
     /*
      * dt: time from mark until now
      * db: blocks written from mark until now
      * rt: remaining time
      *
      * rt is a sector_t, which is always 64bit now. We are keeping
      * the original algorithm, but it is not really necessary.
      *
      * Original algorithm:
      *   So we divide before multiply in case it is 32bit and close
      *   to the limit.
      *   We scale the divisor (db) by 32 to avoid losing precision
      *   near the end of resync when the number of remaining sectors
      *   is close to 'db'.
      *   We then divide rt by 32 after multiplying by db to compensate.
      *   The '+1' avoids division by zero if db is very small.
      */
     dt = ((jiffies - mddev->resync_mark) / HZ);
     if (!dt) dt++;
 
     curr_mark_cnt = mddev->curr_mark_cnt;
     recovery_active = atomic_read(&mddev->recovery_active);
     resync_mark_cnt = mddev->resync_mark_cnt;
 
     if (curr_mark_cnt >= (recovery_active + resync_mark_cnt))
         db = curr_mark_cnt - (recovery_active + resync_mark_cnt);
 
     rt = max_sectors - resync;    /* number of remaining sectors */
     rt = div64_u64(rt, db/32+1);
     rt *= dt;
     rt >>= 5;
 
     seq_printf(seq, " finish=%lu.%lumin", (unsigned long)rt / 60,
            ((unsigned long)rt % 60)/6);
 
     seq_printf(seq, " speed=%ldK/sec", db/2/dt);
     return 1;
 }
 
 static void *md_seq_start(struct seq_file *seq, loff_t *pos)
 {
     struct list_head *tmp;
     loff_t l = *pos;
     struct mddev *mddev;
 
     if (l == 0x10000) {
         ++*pos;
         return (void *)2;
     }
     if (l > 0x10000)
         return NULL;
     if (!l--)
         /* header */
         return (void*)1;
 
     spin_lock(&all_mddevs_lock);
     list_for_each(tmp,&all_mddevs)
         if (!l--) {
             mddev = list_entry(tmp, struct mddev, all_mddevs);
             mddev_get(mddev);
             if (!mddev_get(mddev))
                 continue;
             spin_unlock(&all_mddevs_lock);
             return mddev;
         }
     spin_unlock(&all_mddevs_lock);
     if (!l--)
         return (void*)2;/* tail */
     return NULL;
 }
 
 static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
     struct list_head *tmp;
     struct mddev *next_mddev, *mddev = v;
     struct mddev *to_put = NULL;
 
     ++*pos;
     if (v == (void*)2)
         return NULL;
 
     spin_lock(&all_mddevs_lock);
     if (v == (void*)1) {
         tmp = all_mddevs.next;
     } else {
         to_put = mddev;
         tmp = mddev->all_mddevs.next;
     }
 
     for (;;) {
         if (tmp == &all_mddevs) {
             next_mddev = (void*)2;
             *pos = 0x10000;
             break;
         }
         next_mddev = list_entry(tmp, struct mddev, all_mddevs);
         if (mddev_get(next_mddev))
             break;
         mddev = next_mddev;
         tmp = mddev->all_mddevs.next;
     }
     spin_unlock(&all_mddevs_lock);
 
     if (to_put)
         mddev_put(mddev);
     return next_mddev;
 
 }
 
 static void md_seq_stop(struct seq_file *seq, void *v)
 {
     struct mddev *mddev = v;
 
     if (mddev && v != (void*)1 && v != (void*)2)
         mddev_put(mddev);
 }
 
 static int md_seq_show(struct seq_file *seq, void *v)
 {
     struct mddev *mddev = v;
     sector_t sectors;
     struct md_rdev *rdev;
 
     if (v == (void*)1) {
         struct md_personality *pers;
         seq_printf(seq, "Personalities : ");
         spin_lock(&pers_lock);
         list_for_each_entry(pers, &pers_list, list)
             seq_printf(seq, "[%s] ", pers->name);
 
         spin_unlock(&pers_lock);
         seq_printf(seq, "\n");
         seq->poll_event = atomic_read(&md_event_count);
         return 0;
     }
     if (v == (void*)2) {
         status_unused(seq);
         return 0;
     }
 
     spin_lock(&mddev->lock);
     if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {
         seq_printf(seq, "%s : %sactive", mdname(mddev),
                         mddev->pers ? "" : "in");
         if (mddev->pers) {
             if (mddev->ro==1)
                 seq_printf(seq, " (read-only)");
             if (mddev->ro==2)
                 seq_printf(seq, " (auto-read-only)");
             seq_printf(seq, " %s", mddev->pers->name);
         }
 
         sectors = 0;
         rcu_read_lock();
         rdev_for_each_rcu(rdev, mddev) {
             seq_printf(seq, " %pg[%d]", rdev->bdev, rdev->desc_nr);
 
             if (test_bit(WriteMostly, &rdev->flags))
                 seq_printf(seq, "(W)");
             if (test_bit(Journal, &rdev->flags))
                 seq_printf(seq, "(J)");
             if (test_bit(Faulty, &rdev->flags)) {
                 seq_printf(seq, "(F)");
                 continue;
             }
             if (rdev->raid_disk < 0)
                 seq_printf(seq, "(S)"); /* spare */
             if (test_bit(Replacement, &rdev->flags))
                 seq_printf(seq, "(R)");
             sectors += rdev->sectors;
         }
         rcu_read_unlock();
 
         if (!list_empty(&mddev->disks)) {
             if (mddev->pers)
                 seq_printf(seq, "\n      %llu blocks",
                        (unsigned long long)
                        mddev->array_sectors / 2);
             else
                 seq_printf(seq, "\n      %llu blocks",
                        (unsigned long long)sectors / 2);
         }
         if (mddev->persistent) {
             if (mddev->major_version != 0 ||
                 mddev->minor_version != 90) {
                 seq_printf(seq," super %d.%d",
                        mddev->major_version,
                        mddev->minor_version);
             }
         } else if (mddev->external)
             seq_printf(seq, " super external:%s",
                    mddev->metadata_type);
         else
             seq_printf(seq, " super non-persistent");
 
         if (mddev->pers) {
             mddev->pers->status(seq, mddev);
             seq_printf(seq, "\n      ");
             if (mddev->pers->sync_request) {
                 if (status_resync(seq, mddev))
                     seq_printf(seq, "\n      ");
             }
         } else
             seq_printf(seq, "\n       ");
 
         md_bitmap_status(seq, mddev->bitmap);
 
         seq_printf(seq, "\n");
     }
     spin_unlock(&mddev->lock);
 
     return 0;
 }
 
 static const struct seq_operations md_seq_ops = {
     .start  = md_seq_start,
     .next   = md_seq_next,
     .stop   = md_seq_stop,
     .show   = md_seq_show,
 };
 
 static int md_seq_open(struct inode *inode, struct file *file)
 {
     struct seq_file *seq;
     int error;
 
     error = seq_open(file, &md_seq_ops);
     if (error)
         return error;
 
     seq = file->private_data;
     seq->poll_event = atomic_read(&md_event_count);
     return error;
 }
 
 static int md_unloading;
 static __poll_t mdstat_poll(struct file *filp, poll_table *wait)
 {
     struct seq_file *seq = filp->private_data;
     __poll_t mask;
 
     if (md_unloading)
         return EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI;
     poll_wait(filp, &md_event_waiters, wait);
 
     /* always allow read */
     mask = EPOLLIN | EPOLLRDNORM;
 
     if (seq->poll_event != atomic_read(&md_event_count))
         mask |= EPOLLERR | EPOLLPRI;
     return mask;
 }
 
 static const struct proc_ops mdstat_proc_ops = {
     .proc_open  = md_seq_open,
     .proc_read  = seq_read,
     .proc_lseek = seq_lseek,
     .proc_release   = seq_release,
     .proc_poll  = mdstat_poll,
 };
 
 int register_md_personality(struct md_personality *p)
 {
     pr_debug("md: %s personality registered for level %d\n",
          p->name, p->level);
     spin_lock(&pers_lock);
     list_add_tail(&p->list, &pers_list);
     spin_unlock(&pers_lock);
     return 0;
 }
 EXPORT_SYMBOL(register_md_personality);
 
 int unregister_md_personality(struct md_personality *p)
 {
     pr_debug("md: %s personality unregistered\n", p->name);
     spin_lock(&pers_lock);
     list_del_init(&p->list);
     spin_unlock(&pers_lock);
     return 0;
 }
 EXPORT_SYMBOL(unregister_md_personality);
 
 int register_md_cluster_operations(struct md_cluster_operations *ops,
                    struct module *module)
 {
     int ret = 0;
     spin_lock(&pers_lock);
     if (md_cluster_ops != NULL)
         ret = -EALREADY;
     else {
         md_cluster_ops = ops;
         md_cluster_mod = module;
     }
     spin_unlock(&pers_lock);
     return ret;
 }
 EXPORT_SYMBOL(register_md_cluster_operations);
 
 int unregister_md_cluster_operations(void)
 {
     spin_lock(&pers_lock);
     md_cluster_ops = NULL;
     spin_unlock(&pers_lock);
     return 0;
 }
 EXPORT_SYMBOL(unregister_md_cluster_operations);
 
 int md_setup_cluster(struct mddev *mddev, int nodes)
 {
     int ret;
     if (!md_cluster_ops)
         request_module("md-cluster");
     spin_lock(&pers_lock);
     /* ensure module won't be unloaded */
     if (!md_cluster_ops || !try_module_get(md_cluster_mod)) {
         pr_warn("can't find md-cluster module or get its reference.\n");
         spin_unlock(&pers_lock);
         return -ENOENT;
     }
     spin_unlock(&pers_lock);
 
     ret = md_cluster_ops->join(mddev, nodes);
     if (!ret)
         mddev->safemode_delay = 0;
     return ret;
 }
 
 void md_cluster_stop(struct mddev *mddev)
 {
     if (!md_cluster_ops)
         return;
     md_cluster_ops->leave(mddev);
     module_put(md_cluster_mod);
 }
 
 static int is_mddev_idle(struct mddev *mddev, int init)
 {
     struct md_rdev *rdev;
     int idle;
     int curr_events;
 
     idle = 1;
     rcu_read_lock();
     rdev_for_each_rcu(rdev, mddev) {
         struct gendisk *disk = rdev->bdev->bd_disk;
         curr_events = (int)part_stat_read_accum(disk->part0, sectors) -
                   atomic_read(&disk->sync_io);
         /* sync IO will cause sync_io to increase before the disk_stats
          * as sync_io is counted when a request starts, and
          * disk_stats is counted when it completes.
          * So resync activity will cause curr_events to be smaller than
          * when there was no such activity.
          * non-sync IO will cause disk_stat to increase without
          * increasing sync_io so curr_events will (eventually)
          * be larger than it was before.  Once it becomes
          * substantially larger, the test below will cause
          * the array to appear non-idle, and resync will slow
          * down.
          * If there is a lot of outstanding resync activity when
          * we set last_event to curr_events, then all that activity
          * completing might cause the array to appear non-idle
          * and resync will be slowed down even though there might
          * not have been non-resync activity.  This will only
          * happen once though.  'last_events' will soon reflect
          * the state where there is little or no outstanding
          * resync requests, and further resync activity will
          * always make curr_events less than last_events.
          *
          */
         if (init || curr_events - rdev->last_events > 64) {
             rdev->last_events = curr_events;
             idle = 0;
         }
     }
     rcu_read_unlock();
     return idle;
 }
 
 void md_done_sync(struct mddev *mddev, int blocks, int ok)
 {
     /* another "blocks" (512byte) blocks have been synced */
     atomic_sub(blocks, &mddev->recovery_active);
     wake_up(&mddev->recovery_wait);
     if (!ok) {
         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
         set_bit(MD_RECOVERY_ERROR, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
         // stop recovery, signal do_sync ....
     }
 }
 EXPORT_SYMBOL(md_done_sync);
 
 /* md_write_start(mddev, bi)
  * If we need to update some array metadata (e.g. 'active' flag
  * in superblock) before writing, schedule a superblock update
  * and wait for it to complete.
  * A return value of 'false' means that the write wasn't recorded
  * and cannot proceed as the array is being suspend.
  */
 bool md_write_start(struct mddev *mddev, struct bio *bi)
 {
     int did_change = 0;
 
     if (bio_data_dir(bi) != WRITE)
         return true;
 
     BUG_ON(mddev->ro == 1);
     if (mddev->ro == 2) {
         /* need to switch to read/write */
         mddev->ro = 0;
         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
         md_wakeup_thread(mddev->sync_thread);
         did_change = 1;
     }
     rcu_read_lock();
     percpu_ref_get(&mddev->writes_pending);
     smp_mb(); /* Match smp_mb in set_in_sync() */
     if (mddev->safemode == 1)
         mddev->safemode = 0;
     /* sync_checkers is always 0 when writes_pending is in per-cpu mode */
     if (mddev->in_sync || mddev->sync_checkers) {
         spin_lock(&mddev->lock);
         if (mddev->in_sync) {
             mddev->in_sync = 0;
             set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
             set_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
             md_wakeup_thread(mddev->thread);
             did_change = 1;
         }
         spin_unlock(&mddev->lock);
     }
     rcu_read_unlock();
     if (did_change)
         sysfs_notify_dirent_safe(mddev->sysfs_state);
     if (!mddev->has_superblocks)
         return true;
     wait_event(mddev->sb_wait,
            !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) ||
            mddev->suspended);
     if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
         percpu_ref_put(&mddev->writes_pending);
         return false;
     }
     return true;
 }
 EXPORT_SYMBOL(md_write_start);
 
 /* md_write_inc can only be called when md_write_start() has
  * already been called at least once of the current request.
  * It increments the counter and is useful when a single request
  * is split into several parts.  Each part causes an increment and
  * so needs a matching md_write_end().
  * Unlike md_write_start(), it is safe to call md_write_inc() inside
  * a spinlocked region.
  */
 void md_write_inc(struct mddev *mddev, struct bio *bi)
 {
     if (bio_data_dir(bi) != WRITE)
         return;
     WARN_ON_ONCE(mddev->in_sync || mddev->ro);
     percpu_ref_get(&mddev->writes_pending);
 }
 EXPORT_SYMBOL(md_write_inc);
 
 void md_write_end(struct mddev *mddev)
 {
     percpu_ref_put(&mddev->writes_pending);
 
     if (mddev->safemode == 2)
         md_wakeup_thread(mddev->thread);
     else if (mddev->safemode_delay)
         /* The roundup() ensures this only performs locking once
          * every ->safemode_delay jiffies
          */
         mod_timer(&mddev->safemode_timer,
               roundup(jiffies, mddev->safemode_delay) +
               mddev->safemode_delay);
 }
 
 EXPORT_SYMBOL(md_write_end);
 
 /* This is used by raid0 and raid10 */
 void md_submit_discard_bio(struct mddev *mddev, struct md_rdev *rdev,
             struct bio *bio, sector_t start, sector_t size)
 {
     struct bio *discard_bio = NULL;
 
     if (__blkdev_issue_discard(rdev->bdev, start, size, GFP_NOIO,
             &discard_bio) || !discard_bio)
         return;
 
     bio_chain(discard_bio, bio);
     bio_clone_blkg_association(discard_bio, bio);
     if (mddev->gendisk)
         trace_block_bio_remap(discard_bio,
                 disk_devt(mddev->gendisk),
                 bio->bi_iter.bi_sector);
     submit_bio_noacct(discard_bio);
 }
 EXPORT_SYMBOL_GPL(md_submit_discard_bio);
 
 int acct_bioset_init(struct mddev *mddev)
 {
     int err = 0;
 
     if (!bioset_initialized(&mddev->io_acct_set))
         err = bioset_init(&mddev->io_acct_set, BIO_POOL_SIZE,
             offsetof(struct md_io_acct, bio_clone), 0);
     return err;
 }
 EXPORT_SYMBOL_GPL(acct_bioset_init);
 
 void acct_bioset_exit(struct mddev *mddev)
 {
     bioset_exit(&mddev->io_acct_set);
 }
 EXPORT_SYMBOL_GPL(acct_bioset_exit);
 
 static void md_end_io_acct(struct bio *bio)
 {
     struct md_io_acct *md_io_acct = bio->bi_private;
     struct bio *orig_bio = md_io_acct->orig_bio;
 
     orig_bio->bi_status = bio->bi_status;
 
     bio_end_io_acct(orig_bio, md_io_acct->start_time);
     bio_put(bio);
     bio_endio(orig_bio);
 }
 
 /*
  * Used by personalities that don't already clone the bio and thus can't
  * easily add the timestamp to their extended bio structure.
  */
 void md_account_bio(struct mddev *mddev, struct bio **bio)
 {
     struct block_device *bdev = (*bio)->bi_bdev;
     struct md_io_acct *md_io_acct;
     struct bio *clone;
 
     if (!blk_queue_io_stat(bdev->bd_disk->queue))
         return;
 
     clone = bio_alloc_clone(bdev, *bio, GFP_NOIO, &mddev->io_acct_set);
     md_io_acct = container_of(clone, struct md_io_acct, bio_clone);
     md_io_acct->orig_bio = *bio;
     md_io_acct->start_time = bio_start_io_acct(*bio);
 
     clone->bi_end_io = md_end_io_acct;
     clone->bi_private = md_io_acct;
     *bio = clone;
 }
 EXPORT_SYMBOL_GPL(md_account_bio);
 
 /* md_allow_write(mddev)
  * Calling this ensures that the array is marked 'active' so that writes
  * may proceed without blocking.  It is important to call this before
  * attempting a GFP_KERNEL allocation while holding the mddev lock.
  * Must be called with mddev_lock held.
  */
 void md_allow_write(struct mddev *mddev)
 {
     if (!mddev->pers)
         return;
     if (mddev->ro)
         return;
     if (!mddev->pers->sync_request)
         return;
 
     spin_lock(&mddev->lock);
     if (mddev->in_sync) {
         mddev->in_sync = 0;
         set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
         set_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
         if (mddev->safemode_delay &&
             mddev->safemode == 0)
             mddev->safemode = 1;
         spin_unlock(&mddev->lock);
         md_update_sb(mddev, 0);
         sysfs_notify_dirent_safe(mddev->sysfs_state);
         /* wait for the dirty state to be recorded in the metadata */
         wait_event(mddev->sb_wait,
                !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags));
     } else
         spin_unlock(&mddev->lock);
 }
 EXPORT_SYMBOL_GPL(md_allow_write);
 
 #define SYNC_MARKS  10
 #define SYNC_MARK_STEP  (3*HZ)
 #define UPDATE_FREQUENCY (5*60*HZ)
 void md_do_sync(struct md_thread *thread)
 {
     struct mddev *mddev = thread->mddev;
     struct mddev *mddev2;
     unsigned int currspeed = 0, window;
     sector_t max_sectors,j, io_sectors, recovery_done;
     unsigned long mark[SYNC_MARKS];
     unsigned long update_time;
     sector_t mark_cnt[SYNC_MARKS];
     int last_mark,m;
     sector_t last_check;
     int skipped = 0;
     struct md_rdev *rdev;
     char *desc, *action = NULL;
     struct blk_plug plug;
     int ret;
 
     /* just incase thread restarts... */
     if (test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
         test_bit(MD_RECOVERY_WAIT, &mddev->recovery))
         return;
     if (mddev->ro) {/* never try to sync a read-only array */
         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
         return;
     }
 
     if (mddev_is_clustered(mddev)) {
         ret = md_cluster_ops->resync_start(mddev);
         if (ret)
             goto skip;
 
         set_bit(MD_CLUSTER_RESYNC_LOCKED, &mddev->flags);
         if (!(test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
             test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) ||
             test_bit(MD_RECOVERY_RECOVER, &mddev->recovery))
              && ((unsigned long long)mddev->curr_resync_completed
              < (unsigned long long)mddev->resync_max_sectors))
             goto skip;
     }
 
     if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
         if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)) {
             desc = "data-check";
             action = "check";
         } else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
             desc = "requested-resync";
             action = "repair";
         } else
             desc = "resync";
     } else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
         desc = "reshape";
     else
         desc = "recovery";
 
     mddev->last_sync_action = action ?: desc;
 
     /*
      * Before starting a resync we must have set curr_resync to
      * 2, and then checked that every "conflicting" array has curr_resync
      * less than ours.  When we find one that is the same or higher
      * we wait on resync_wait.  To avoid deadlock, we reduce curr_resync
      * to 1 if we choose to yield (based arbitrarily on address of mddev structure).
      * This will mean we have to start checking from the beginning again.
      *
      */
 
     do {
         int mddev2_minor = -1;
         mddev->curr_resync = MD_RESYNC_DELAYED;
 
     try_again:
         if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
             goto skip;
         spin_lock(&all_mddevs_lock);
         list_for_each_entry(mddev2, &all_mddevs, all_mddevs) {
             if (test_bit(MD_DELETED, &mddev2->flags))
                 continue;
             if (mddev2 == mddev)
                 continue;
             if (!mddev->parallel_resync
             &&  mddev2->curr_resync
             &&  match_mddev_units(mddev, mddev2)) {
                 DEFINE_WAIT(wq);
                 if (mddev < mddev2 &&
                     mddev->curr_resync == MD_RESYNC_DELAYED) {
                     /* arbitrarily yield */
                     mddev->curr_resync = MD_RESYNC_YIELDED;
                     wake_up(&resync_wait);
                 }
                 if (mddev > mddev2 &&
                     mddev->curr_resync == MD_RESYNC_YIELDED)
                     /* no need to wait here, we can wait the next
                      * time 'round when curr_resync == 2
                      */
                     continue;
                 /* We need to wait 'interruptible' so as not to
                  * contribute to the load average, and not to
                  * be caught by 'softlockup'
                  */
                 prepare_to_wait(&resync_wait, &wq, TASK_INTERRUPTIBLE);
                 if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
                     mddev2->curr_resync >= mddev->curr_resync) {
                     if (mddev2_minor != mddev2->md_minor) {
                         mddev2_minor = mddev2->md_minor;
                         pr_info("md: delaying %s of %s until %s has finished (they share one or more physical units)\n",
                             desc, mdname(mddev),
                             mdname(mddev2));
                     }
                     spin_unlock(&all_mddevs_lock);
 
                     if (signal_pending(current))
                         flush_signals(current);
                     schedule();
                     finish_wait(&resync_wait, &wq);
                     goto try_again;
                 }
                 finish_wait(&resync_wait, &wq);
             }
         }
         spin_unlock(&all_mddevs_lock);
     } while (mddev->curr_resync < MD_RESYNC_DELAYED);
 
     j = 0;
     if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
         /* resync follows the size requested by the personality,
          * which defaults to physical size, but can be virtual size
          */
         max_sectors = mddev->resync_max_sectors;
         atomic64_set(&mddev->resync_mismatches, 0);
         /* we don't use the checkpoint if there's a bitmap */
         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
             j = mddev->resync_min;
         else if (!mddev->bitmap)
             j = mddev->recovery_cp;
 
     } else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
         max_sectors = mddev->resync_max_sectors;
         /*
          * If the original node aborts reshaping then we continue the
          * reshaping, so set j again to avoid restart reshape from the
          * first beginning
          */
         if (mddev_is_clustered(mddev) &&
             mddev->reshape_position != MaxSector)
             j = mddev->reshape_position;
     } else {
         /* recovery follows the physical size of devices */
         max_sectors = mddev->dev_sectors;
         j = MaxSector;
         rcu_read_lock();
         rdev_for_each_rcu(rdev, mddev)
             if (rdev->raid_disk >= 0 &&
                 !test_bit(Journal, &rdev->flags) &&
                 !test_bit(Faulty, &rdev->flags) &&
                 !test_bit(In_sync, &rdev->flags) &&
                 rdev->recovery_offset < j)
                 j = rdev->recovery_offset;
         rcu_read_unlock();
 
         /* If there is a bitmap, we need to make sure all
          * writes that started before we added a spare
          * complete before we start doing a recovery.
          * Otherwise the write might complete and (via
          * bitmap_endwrite) set a bit in the bitmap after the
          * recovery has checked that bit and skipped that
          * region.
          */
         if (mddev->bitmap) {
             mddev->pers->quiesce(mddev, 1);
             mddev->pers->quiesce(mddev, 0);
         }
     }
 
     pr_info("md: %s of RAID array %s\n", desc, mdname(mddev));
     pr_debug("md: minimum _guaranteed_  speed: %d KB/sec/disk.\n", speed_min(mddev));
     pr_debug("md: using maximum available idle IO bandwidth (but not more than %d KB/sec) for %s.\n",
          speed_max(mddev), desc);
 
     is_mddev_idle(mddev, 1); /* this initializes IO event counters */
 
     io_sectors = 0;
     for (m = 0; m < SYNC_MARKS; m++) {
         mark[m] = jiffies;
         mark_cnt[m] = io_sectors;
     }
     last_mark = 0;
     mddev->resync_mark = mark[last_mark];
     mddev->resync_mark_cnt = mark_cnt[last_mark];
 
     /*
      * Tune reconstruction:
      */
     window = 32 * (PAGE_SIZE / 512);
     pr_debug("md: using %dk window, over a total of %lluk.\n",
          window/2, (unsigned long long)max_sectors/2);
 
     atomic_set(&mddev->recovery_active, 0);
     last_check = 0;
 
     if (j>2) {
         pr_debug("md: resuming %s of %s from checkpoint.\n",
              desc, mdname(mddev));
         mddev->curr_resync = j;
     } else
         mddev->curr_resync = MD_RESYNC_ACTIVE; /* no longer delayed */
     mddev->curr_resync_completed = j;
     sysfs_notify_dirent_safe(mddev->sysfs_completed);
     md_new_event();
     update_time = jiffies;
 
     blk_start_plug(&plug);
     while (j < max_sectors) {
         sector_t sectors;
 
         skipped = 0;
 
         if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
             ((mddev->curr_resync > mddev->curr_resync_completed &&
               (mddev->curr_resync - mddev->curr_resync_completed)
               > (max_sectors >> 4)) ||
              time_after_eq(jiffies, update_time + UPDATE_FREQUENCY) ||
              (j - mddev->curr_resync_completed)*2
              >= mddev->resync_max - mddev->curr_resync_completed ||
              mddev->curr_resync_completed > mddev->resync_max
                 )) {
             /* time to update curr_resync_completed */
             wait_event(mddev->recovery_wait,
                    atomic_read(&mddev->recovery_active) == 0);
             mddev->curr_resync_completed = j;
             if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) &&
                 j > mddev->recovery_cp)
                 mddev->recovery_cp = j;
             update_time = jiffies;
             set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
             sysfs_notify_dirent_safe(mddev->sysfs_completed);
         }
 
         while (j >= mddev->resync_max &&
                !test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
             /* As this condition is controlled by user-space,
              * we can block indefinitely, so use '_interruptible'
              * to avoid triggering warnings.
              */
             flush_signals(current); /* just in case */
             wait_event_interruptible(mddev->recovery_wait,
                          mddev->resync_max > j
                          || test_bit(MD_RECOVERY_INTR,
                                  &mddev->recovery));
         }
 
         if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
             break;
 
         sectors = mddev->pers->sync_request(mddev, j, &skipped);
         if (sectors == 0) {
             set_bit(MD_RECOVERY_INTR, &mddev->recovery);
             break;
         }
 
         if (!skipped) { /* actual IO requested */
             io_sectors += sectors;
             atomic_add(sectors, &mddev->recovery_active);
         }
 
         if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
             break;
 
         j += sectors;
         if (j > max_sectors)
             /* when skipping, extra large numbers can be returned. */
             j = max_sectors;
         if (j > 2)
             mddev->curr_resync = j;
         mddev->curr_mark_cnt = io_sectors;
         if (last_check == 0)
             /* this is the earliest that rebuild will be
              * visible in /proc/mdstat
              */
             md_new_event();
 
         if (last_check + window > io_sectors || j == max_sectors)
             continue;
 
         last_check = io_sectors;
     repeat:
         if (time_after_eq(jiffies, mark[last_mark] + SYNC_MARK_STEP )) {
             /* step marks */
             int next = (last_mark+1) % SYNC_MARKS;
 
             mddev->resync_mark = mark[next];
             mddev->resync_mark_cnt = mark_cnt[next];
             mark[next] = jiffies;
             mark_cnt[next] = io_sectors - atomic_read(&mddev->recovery_active);
             last_mark = next;
         }
 
         if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
             break;
 
         /*
          * this loop exits only if either when we are slower than
          * the 'hard' speed limit, or the system was IO-idle for
          * a jiffy.
          * the system might be non-idle CPU-wise, but we only care
          * about not overloading the IO subsystem. (things like an
          * e2fsck being done on the RAID array should execute fast)
          */
         cond_resched();
 
         recovery_done = io_sectors - atomic_read(&mddev->recovery_active);
         currspeed = ((unsigned long)(recovery_done - mddev->resync_mark_cnt))/2
             /((jiffies-mddev->resync_mark)/HZ +1) +1;
 
         if (currspeed > speed_min(mddev)) {
             if (currspeed > speed_max(mddev)) {
                 msleep(500);
                 goto repeat;
             }
             if (!is_mddev_idle(mddev, 0)) {
                 /*
                  * Give other IO more of a chance.
                  * The faster the devices, the less we wait.
                  */
                 wait_event(mddev->recovery_wait,
                        !atomic_read(&mddev->recovery_active));
             }
         }
     }
     pr_info("md: %s: %s %s.\n",mdname(mddev), desc,
         test_bit(MD_RECOVERY_INTR, &mddev->recovery)
         ? "interrupted" : "done");
     /*
      * this also signals 'finished resyncing' to md_stop
      */
     blk_finish_plug(&plug);
     wait_event(mddev->recovery_wait, !atomic_read(&mddev->recovery_active));
 
     if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
         !test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
         mddev->curr_resync >= MD_RESYNC_ACTIVE) {
         mddev->curr_resync_completed = mddev->curr_resync;
         sysfs_notify_dirent_safe(mddev->sysfs_completed);
     }
     mddev->pers->sync_request(mddev, max_sectors, &skipped);
 
     if (!test_bit(MD_RECOVERY_CHECK, &mddev->recovery) &&
         mddev->curr_resync >= MD_RESYNC_ACTIVE) {
         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
             if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
                 if (mddev->curr_resync >= mddev->recovery_cp) {
                     pr_debug("md: checkpointing %s of %s.\n",
                          desc, mdname(mddev));
                     if (test_bit(MD_RECOVERY_ERROR,
                         &mddev->recovery))
                         mddev->recovery_cp =
                             mddev->curr_resync_completed;
                     else
                         mddev->recovery_cp =
                             mddev->curr_resync;
                 }
             } else
                 mddev->recovery_cp = MaxSector;
         } else {
             if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
                 mddev->curr_resync = MaxSector;
             if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
                 test_bit(MD_RECOVERY_RECOVER, &mddev->recovery)) {
                 rcu_read_lock();
                 rdev_for_each_rcu(rdev, mddev)
                     if (rdev->raid_disk >= 0 &&
                         mddev->delta_disks >= 0 &&
                         !test_bit(Journal, &rdev->flags) &&
                         !test_bit(Faulty, &rdev->flags) &&
                         !test_bit(In_sync, &rdev->flags) &&
                         rdev->recovery_offset < mddev->curr_resync)
                         rdev->recovery_offset = mddev->curr_resync;
                 rcu_read_unlock();
             }
         }
     }
  skip:
     /* set CHANGE_PENDING here since maybe another update is needed,
      * so other nodes are informed. It should be harmless for normal
      * raid */
     set_mask_bits(&mddev->sb_flags, 0,
               BIT(MD_SB_CHANGE_PENDING) | BIT(MD_SB_CHANGE_DEVS));
 
     if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
             !test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
             mddev->delta_disks > 0 &&
             mddev->pers->finish_reshape &&
             mddev->pers->size &&
             mddev->queue) {
         mddev_lock_nointr(mddev);
         md_set_array_sectors(mddev, mddev->pers->size(mddev, 0, 0));
         mddev_unlock(mddev);
         if (!mddev_is_clustered(mddev))
             set_capacity_and_notify(mddev->gendisk,
                         mddev->array_sectors);
     }
 
     spin_lock(&mddev->lock);
     if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
         /* We completed so min/max setting can be forgotten if used. */
         if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
             mddev->resync_min = 0;
         mddev->resync_max = MaxSector;
     } else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
         mddev->resync_min = mddev->curr_resync_completed;
     set_bit(MD_RECOVERY_DONE, &mddev->recovery);
     mddev->curr_resync = MD_RESYNC_NONE;
     spin_unlock(&mddev->lock);
 
     wake_up(&resync_wait);
     md_wakeup_thread(mddev->thread);
     return;
 }
 EXPORT_SYMBOL_GPL(md_do_sync);
 
 static int remove_and_add_spares(struct mddev *mddev,
                  struct md_rdev *this)
 {
     struct md_rdev *rdev;
     int spares = 0;
     int removed = 0;
     bool remove_some = false;
 
     if (this && test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
         /* Mustn't remove devices when resync thread is running */
         return 0;
 
     rdev_for_each(rdev, mddev) {
         if ((this == NULL || rdev == this) &&
             rdev->raid_disk >= 0 &&
             !test_bit(Blocked, &rdev->flags) &&
             test_bit(Faulty, &rdev->flags) &&
             atomic_read(&rdev->nr_pending)==0) {
             /* Faulty non-Blocked devices with nr_pending == 0
              * never get nr_pending incremented,
              * never get Faulty cleared, and never get Blocked set.
              * So we can synchronize_rcu now rather than once per device
              */
             remove_some = true;
             set_bit(RemoveSynchronized, &rdev->flags);
         }
     }
 
     if (remove_some)
         synchronize_rcu();
     rdev_for_each(rdev, mddev) {
         if ((this == NULL || rdev == this) &&
             rdev->raid_disk >= 0 &&
             !test_bit(Blocked, &rdev->flags) &&
             ((test_bit(RemoveSynchronized, &rdev->flags) ||
              (!test_bit(In_sync, &rdev->flags) &&
               !test_bit(Journal, &rdev->flags))) &&
             atomic_read(&rdev->nr_pending)==0)) {
             if (mddev->pers->hot_remove_disk(
                     mddev, rdev) == 0) {
                 sysfs_unlink_rdev(mddev, rdev);
                 rdev->saved_raid_disk = rdev->raid_disk;
                 rdev->raid_disk = -1;
                 removed++;
             }
         }
         if (remove_some && test_bit(RemoveSynchronized, &rdev->flags))
             clear_bit(RemoveSynchronized, &rdev->flags);
     }
 
     if (removed && mddev->kobj.sd)
         sysfs_notify_dirent_safe(mddev->sysfs_degraded);
 
     if (this && removed)
         goto no_add;
 
     rdev_for_each(rdev, mddev) {
         if (this && this != rdev)
             continue;
         if (test_bit(Candidate, &rdev->flags))
             continue;
         if (rdev->raid_disk >= 0 &&
             !test_bit(In_sync, &rdev->flags) &&
             !test_bit(Journal, &rdev->flags) &&
             !test_bit(Faulty, &rdev->flags))
             spares++;
         if (rdev->raid_disk >= 0)
             continue;
         if (test_bit(Faulty, &rdev->flags))
             continue;
         if (!test_bit(Journal, &rdev->flags)) {
             if (mddev->ro &&
                 ! (rdev->saved_raid_disk >= 0 &&
                    !test_bit(Bitmap_sync, &rdev->flags)))
                 continue;
 
             rdev->recovery_offset = 0;
         }
         if (mddev->pers->hot_add_disk(mddev, rdev) == 0) {
             /* failure here is OK */
             sysfs_link_rdev(mddev, rdev);
             if (!test_bit(Journal, &rdev->flags))
                 spares++;
             md_new_event();
             set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
         }
     }
 no_add:
     if (removed)
         set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
     return spares;
 }
 
 static void md_start_sync(struct work_struct *ws)
 {
     struct mddev *mddev = container_of(ws, struct mddev, del_work);
 
     mddev->sync_thread = md_register_thread(md_do_sync,
                         mddev,
                         "resync");
     if (!mddev->sync_thread) {
         pr_warn("%s: could not start resync thread...\n",
             mdname(mddev));
         /* leave the spares where they are, it shouldn't hurt */
         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
         clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
         clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
         clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
         wake_up(&resync_wait);
         if (test_and_clear_bit(MD_RECOVERY_RECOVER,
                        &mddev->recovery))
             if (mddev->sysfs_action)
                 sysfs_notify_dirent_safe(mddev->sysfs_action);
     } else
         md_wakeup_thread(mddev->sync_thread);
     sysfs_notify_dirent_safe(mddev->sysfs_action);
     md_new_event();
 }
 
 /*
  * This routine is regularly called by all per-raid-array threads to
  * deal with generic issues like resync and super-block update.
  * Raid personalities that don't have a thread (linear/raid0) do not
  * need this as they never do any recovery or update the superblock.
  *
  * It does not do any resync itself, but rather "forks" off other threads
  * to do that as needed.
  * When it is determined that resync is needed, we set MD_RECOVERY_RUNNING in
  * "->recovery" and create a thread at ->sync_thread.
  * When the thread finishes it sets MD_RECOVERY_DONE
  * and wakeups up this thread which will reap the thread and finish up.
  * This thread also removes any faulty devices (with nr_pending == 0).
  *
  * The overall approach is:
  *  1/ if the superblock needs updating, update it.
  *  2/ If a recovery thread is running, don't do anything else.
  *  3/ If recovery has finished, clean up, possibly marking spares active.
  *  4/ If there are any faulty devices, remove them.
  *  5/ If array is degraded, try to add spares devices
  *  6/ If array has spares or is not in-sync, start a resync thread.
  */
 void md_check_recovery(struct mddev *mddev)
 {
     if (test_bit(MD_ALLOW_SB_UPDATE, &mddev->flags) && mddev->sb_flags) {
         /* Write superblock - thread that called mddev_suspend()
          * holds reconfig_mutex for us.
          */
         set_bit(MD_UPDATING_SB, &mddev->flags);
         smp_mb__after_atomic();
         if (test_bit(MD_ALLOW_SB_UPDATE, &mddev->flags))
             md_update_sb(mddev, 0);
         clear_bit_unlock(MD_UPDATING_SB, &mddev->flags);
         wake_up(&mddev->sb_wait);
     }
 
     if (mddev->suspended)
         return;
 
     if (mddev->bitmap)
         md_bitmap_daemon_work(mddev);
 
     if (signal_pending(current)) {
         if (mddev->pers->sync_request && !mddev->external) {
             pr_debug("md: %s in immediate safe mode\n",
                  mdname(mddev));
             mddev->safemode = 2;
         }
         flush_signals(current);
     }
 
     if (mddev->ro && !test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
         return;
     if ( ! (
         (mddev->sb_flags & ~ (1<<MD_SB_CHANGE_PENDING)) ||
         test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
         test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
         (mddev->external == 0 && mddev->safemode == 1) ||
         (mddev->safemode == 2
          && !mddev->in_sync && mddev->recovery_cp == MaxSector)
         ))
         return;
 
     if (mddev_trylock(mddev)) {
         int spares = 0;
         bool try_set_sync = mddev->safemode != 0;
 
         if (!mddev->external && mddev->safemode == 1)
             mddev->safemode = 0;
 
         if (mddev->ro) {
             struct md_rdev *rdev;
             if (!mddev->external && mddev->in_sync)
                 /* 'Blocked' flag not needed as failed devices
                  * will be recorded if array switched to read/write.
                  * Leaving it set will prevent the device
                  * from being removed.
                  */
                 rdev_for_each(rdev, mddev)
                     clear_bit(Blocked, &rdev->flags);
             /* On a read-only array we can:
              * - remove failed devices
              * - add already-in_sync devices if the array itself
              *   is in-sync.
              * As we only add devices that are already in-sync,
              * we can activate the spares immediately.
              */
             remove_and_add_spares(mddev, NULL);
             /* There is no thread, but we need to call
              * ->spare_active and clear saved_raid_disk
              */
             set_bit(MD_RECOVERY_INTR, &mddev->recovery);
             md_unregister_thread(&mddev->sync_thread);
             md_reap_sync_thread(mddev);
             clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
             clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
             clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
             goto unlock;
         }
 
         if (mddev_is_clustered(mddev)) {
             struct md_rdev *rdev, *tmp;
             /* kick the device if another node issued a
              * remove disk.
              */
             rdev_for_each_safe(rdev, tmp, mddev) {
                 if (test_and_clear_bit(ClusterRemove, &rdev->flags) &&
                         rdev->raid_disk < 0)
                     md_kick_rdev_from_array(rdev);
             }
         }
 
         if (try_set_sync && !mddev->external && !mddev->in_sync) {
             spin_lock(&mddev->lock);
             set_in_sync(mddev);
             spin_unlock(&mddev->lock);
         }
 
         if (mddev->sb_flags)
             md_update_sb(mddev, 0);
 
         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
             !test_bit(MD_RECOVERY_DONE, &mddev->recovery)) {
             /* resync/recovery still happening */
             clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
             goto unlock;
         }
         if (mddev->sync_thread) {
             md_unregister_thread(&mddev->sync_thread);
             md_reap_sync_thread(mddev);
             goto unlock;
         }
         /* Set RUNNING before clearing NEEDED to avoid
          * any transients in the value of "sync_action".
          */
         mddev->curr_resync_completed = 0;
         spin_lock(&mddev->lock);
         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
         spin_unlock(&mddev->lock);
         /* Clear some bits that don't mean anything, but
          * might be left set
          */
         clear_bit(MD_RECOVERY_INTR, &mddev->recovery);
         clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
 
         if (!test_and_clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
             test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
             goto not_running;
         /* no recovery is running.
          * remove any failed drives, then
          * add spares if possible.
          * Spares are also removed and re-added, to allow
          * the personality to fail the re-add.
          */
 
         if (mddev->reshape_position != MaxSector) {
             if (mddev->pers->check_reshape == NULL ||
                 mddev->pers->check_reshape(mddev) != 0)
                 /* Cannot proceed */
                 goto not_running;
             set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
             clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
         } else if ((spares = remove_and_add_spares(mddev, NULL))) {
             clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
             clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
             clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
             set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
         } else if (mddev->recovery_cp < MaxSector) {
             set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
             clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
         } else if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
             /* nothing to be done ... */
             goto not_running;
 
         if (mddev->pers->sync_request) {
             if (spares) {
                 /* We are adding a device or devices to an array
                  * which has the bitmap stored on all devices.
                  * So make sure all bitmap pages get written
                  */
                 md_bitmap_write_all(mddev->bitmap);
             }
             INIT_WORK(&mddev->del_work, md_start_sync);
             queue_work(md_misc_wq, &mddev->del_work);
             goto unlock;
         }
     not_running:
         if (!mddev->sync_thread) {
             clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
             wake_up(&resync_wait);
             if (test_and_clear_bit(MD_RECOVERY_RECOVER,
                            &mddev->recovery))
                 if (mddev->sysfs_action)
                     sysfs_notify_dirent_safe(mddev->sysfs_action);
         }
     unlock:
         wake_up(&mddev->sb_wait);
         mddev_unlock(mddev);
     }
 }
 EXPORT_SYMBOL(md_check_recovery);
 
 void md_reap_sync_thread(struct mddev *mddev)
 {
     struct md_rdev *rdev;
     sector_t old_dev_sectors = mddev->dev_sectors;
     bool is_reshaped = false;
 
     /* sync_thread should be unregistered, collect result */
     if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
         !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
         mddev->degraded != mddev->raid_disks) {
         /* success...*/
         /* activate any spares */
         if (mddev->pers->spare_active(mddev)) {
             sysfs_notify_dirent_safe(mddev->sysfs_degraded);
             set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
         }
     }
     if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
         mddev->pers->finish_reshape) {
         mddev->pers->finish_reshape(mddev);
         if (mddev_is_clustered(mddev))
             is_reshaped = true;
     }
 
     /* If array is no-longer degraded, then any saved_raid_disk
      * information must be scrapped.
      */
     if (!mddev->degraded)
         rdev_for_each(rdev, mddev)
             rdev->saved_raid_disk = -1;
 
     md_update_sb(mddev, 1);
     /* MD_SB_CHANGE_PENDING should be cleared by md_update_sb, so we can
      * call resync_finish here if MD_CLUSTER_RESYNC_LOCKED is set by
      * clustered raid */
     if (test_and_clear_bit(MD_CLUSTER_RESYNC_LOCKED, &mddev->flags))
         md_cluster_ops->resync_finish(mddev);
     clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
     clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
     clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
     clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
     clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
     clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
     /*
      * We call md_cluster_ops->update_size here because sync_size could
      * be changed by md_update_sb, and MD_RECOVERY_RESHAPE is cleared,
      * so it is time to update size across cluster.
      */
     if (mddev_is_clustered(mddev) && is_reshaped
                       && !test_bit(MD_CLOSING, &mddev->flags))
         md_cluster_ops->update_size(mddev, old_dev_sectors);
     wake_up(&resync_wait);
     /* flag recovery needed just to double check */
     set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
     sysfs_notify_dirent_safe(mddev->sysfs_completed);
     sysfs_notify_dirent_safe(mddev->sysfs_action);
     md_new_event();
     if (mddev->event_work.func)
         queue_work(md_misc_wq, &mddev->event_work);
 }
 EXPORT_SYMBOL(md_reap_sync_thread);
 
 void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev)
 {
     sysfs_notify_dirent_safe(rdev->sysfs_state);
     wait_event_timeout(rdev->blocked_wait,
                !test_bit(Blocked, &rdev->flags) &&
                !test_bit(BlockedBadBlocks, &rdev->flags),
                msecs_to_jiffies(5000));
     rdev_dec_pending(rdev, mddev);
 }
 EXPORT_SYMBOL(md_wait_for_blocked_rdev);
 
 void md_finish_reshape(struct mddev *mddev)
 {
     /* called be personality module when reshape completes. */
     struct md_rdev *rdev;
 
     rdev_for_each(rdev, mddev) {
         if (rdev->data_offset > rdev->new_data_offset)
             rdev->sectors += rdev->data_offset - rdev->new_data_offset;
         else
             rdev->sectors -= rdev->new_data_offset - rdev->data_offset;
         rdev->data_offset = rdev->new_data_offset;
     }
 }
 EXPORT_SYMBOL(md_finish_reshape);
 
 /* Bad block management */
 
 /* Returns 1 on success, 0 on failure */
 int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
                int is_new)
 {
     struct mddev *mddev = rdev->mddev;
     int rv;
     if (is_new)
         s += rdev->new_data_offset;
     else
         s += rdev->data_offset;
     rv = badblocks_set(&rdev->badblocks, s, sectors, 0);
     if (rv == 0) {
         /* Make sure they get written out promptly */
         if (test_bit(ExternalBbl, &rdev->flags))
             sysfs_notify_dirent_safe(rdev->sysfs_unack_badblocks);
         sysfs_notify_dirent_safe(rdev->sysfs_state);
         set_mask_bits(&mddev->sb_flags, 0,
                   BIT(MD_SB_CHANGE_CLEAN) | BIT(MD_SB_CHANGE_PENDING));
         md_wakeup_thread(rdev->mddev->thread);
         return 1;
     } else
         return 0;
 }
 EXPORT_SYMBOL_GPL(rdev_set_badblocks);
 
 int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
              int is_new)
 {
     int rv;
     if (is_new)
         s += rdev->new_data_offset;
     else
         s += rdev->data_offset;
     rv = badblocks_clear(&rdev->badblocks, s, sectors);
     if ((rv == 0) && test_bit(ExternalBbl, &rdev->flags))
         sysfs_notify_dirent_safe(rdev->sysfs_badblocks);
     return rv;
 }
 EXPORT_SYMBOL_GPL(rdev_clear_badblocks);
 
 static int md_notify_reboot(struct notifier_block *this,
                 unsigned long code, void *x)
 {
     struct mddev *mddev, *n;
     int need_delay = 0;
 
     spin_lock(&all_mddevs_lock);
     list_for_each_entry_safe(mddev, n, &all_mddevs, all_mddevs) {
         if (!mddev_get(mddev))
             continue;
         spin_unlock(&all_mddevs_lock);
         if (mddev_trylock(mddev)) {
             if (mddev->pers)
                 __md_stop_writes(mddev);
             if (mddev->persistent)
                 mddev->safemode = 2;
             mddev_unlock(mddev);
         }
         need_delay = 1;
         mddev_put(mddev);
         spin_lock(&all_mddevs_lock);
     }
     spin_unlock(&all_mddevs_lock);
 
     /*
      * certain more exotic SCSI devices are known to be
      * volatile wrt too early system reboots. While the
      * right place to handle this issue is the given
      * driver, we do want to have a safe RAID driver ...
      */
     if (need_delay)
         msleep(1000);
 
     return NOTIFY_DONE;
 }
 
 static struct notifier_block md_notifier = {
     .notifier_call  = md_notify_reboot,
     .next       = NULL,
     .priority   = INT_MAX, /* before any real devices */
 };
 
 static void md_geninit(void)
 {
     pr_debug("md: sizeof(mdp_super_t) = %d\n", (int)sizeof(mdp_super_t));
 
     proc_create("mdstat", S_IRUGO, NULL, &mdstat_proc_ops);
 }
 
 static int __init md_init(void)
 {
     int ret = -ENOMEM;
 
     md_wq = alloc_workqueue("md", WQ_MEM_RECLAIM, 0);
     if (!md_wq)
         goto err_wq;
 
     md_misc_wq = alloc_workqueue("md_misc", 0, 0);
     if (!md_misc_wq)
         goto err_misc_wq;
 
     md_rdev_misc_wq = alloc_workqueue("md_rdev_misc", 0, 0);
     if (!md_rdev_misc_wq)
         goto err_rdev_misc_wq;
 
     ret = __register_blkdev(MD_MAJOR, "md", md_probe);
     if (ret < 0)
         goto err_md;
 
     ret = __register_blkdev(0, "mdp", md_probe);
     if (ret < 0)
         goto err_mdp;
     mdp_major = ret;
 
     register_reboot_notifier(&md_notifier);
     raid_table_header = register_sysctl_table(raid_root_table);
 
     md_geninit();
     return 0;
 
 err_mdp:
     unregister_blkdev(MD_MAJOR, "md");
 err_md:
     destroy_workqueue(md_rdev_misc_wq);
 err_rdev_misc_wq:
     destroy_workqueue(md_misc_wq);
 err_misc_wq:
     destroy_workqueue(md_wq);
 err_wq:
     return ret;
 }
 
 static void check_sb_changes(struct mddev *mddev, struct md_rdev *rdev)
 {
     struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
     struct md_rdev *rdev2, *tmp;
     int role, ret;
 
     /*
      * If size is changed in another node then we need to
      * do resize as well.
      */
     if (mddev->dev_sectors != le64_to_cpu(sb->size)) {
         ret = mddev->pers->resize(mddev, le64_to_cpu(sb->size));
         if (ret)
             pr_info("md-cluster: resize failed\n");
         else
             md_bitmap_update_sb(mddev->bitmap);
     }
 
     /* Check for change of roles in the active devices */
     rdev_for_each_safe(rdev2, tmp, mddev) {
         if (test_bit(Faulty, &rdev2->flags))
             continue;
 
         /* Check if the roles changed */
         role = le16_to_cpu(sb->dev_roles[rdev2->desc_nr]);
 
         if (test_bit(Candidate, &rdev2->flags)) {
             if (role == MD_DISK_ROLE_FAULTY) {
                 pr_info("md: Removing Candidate device %pg because add failed\n",
                     rdev2->bdev);
                 md_kick_rdev_from_array(rdev2);
                 continue;
             }
             else
                 clear_bit(Candidate, &rdev2->flags);
         }
 
         if (role != rdev2->raid_disk) {
             /*
              * got activated except reshape is happening.
              */
             if (rdev2->raid_disk == -1 && role != MD_DISK_ROLE_SPARE &&
                 !(le32_to_cpu(sb->feature_map) &
                   MD_FEATURE_RESHAPE_ACTIVE)) {
                 rdev2->saved_raid_disk = role;
                 ret = remove_and_add_spares(mddev, rdev2);
                 pr_info("Activated spare: %pg\n",
                     rdev2->bdev);
                 /* wakeup mddev->thread here, so array could
                  * perform resync with the new activated disk */
                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                 md_wakeup_thread(mddev->thread);
             }
             /* device faulty
              * We just want to do the minimum to mark the disk
              * as faulty. The recovery is performed by the
              * one who initiated the error.
              */
             if (role == MD_DISK_ROLE_FAULTY ||
                 role == MD_DISK_ROLE_JOURNAL) {
                 md_error(mddev, rdev2);
                 clear_bit(Blocked, &rdev2->flags);
             }
         }
     }
 
     if (mddev->raid_disks != le32_to_cpu(sb->raid_disks)) {
         ret = update_raid_disks(mddev, le32_to_cpu(sb->raid_disks));
         if (ret)
             pr_warn("md: updating array disks failed. %d\n", ret);
     }
 
     /*
      * Since mddev->delta_disks has already updated in update_raid_disks,
      * so it is time to check reshape.
      */
     if (test_bit(MD_RESYNCING_REMOTE, &mddev->recovery) &&
         (le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
         /*
          * reshape is happening in the remote node, we need to
          * update reshape_position and call start_reshape.
          */
         mddev->reshape_position = le64_to_cpu(sb->reshape_position);
         if (mddev->pers->update_reshape_pos)
             mddev->pers->update_reshape_pos(mddev);
         if (mddev->pers->start_reshape)
             mddev->pers->start_reshape(mddev);
     } else if (test_bit(MD_RESYNCING_REMOTE, &mddev->recovery) &&
            mddev->reshape_position != MaxSector &&
            !(le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
         /* reshape is just done in another node. */
         mddev->reshape_position = MaxSector;
         if (mddev->pers->update_reshape_pos)
             mddev->pers->update_reshape_pos(mddev);
     }
 
     /* Finally set the event to be up to date */
     mddev->events = le64_to_cpu(sb->events);
 }
 
 static int read_rdev(struct mddev *mddev, struct md_rdev *rdev)
 {
     int err;
     struct page *swapout = rdev->sb_page;
     struct mdp_superblock_1 *sb;
 
     /* Store the sb page of the rdev in the swapout temporary
      * variable in case we err in the future
      */
     rdev->sb_page = NULL;
     err = alloc_disk_sb(rdev);
     if (err == 0) {
         ClearPageUptodate(rdev->sb_page);
         rdev->sb_loaded = 0;
         err = super_types[mddev->major_version].
             load_super(rdev, NULL, mddev->minor_version);
     }
     if (err < 0) {
         pr_warn("%s: %d Could not reload rdev(%d) err: %d. Restoring old values\n",
                 __func__, __LINE__, rdev->desc_nr, err);
         if (rdev->sb_page)
             put_page(rdev->sb_page);
         rdev->sb_page = swapout;
         rdev->sb_loaded = 1;
         return err;
     }
 
     sb = page_address(rdev->sb_page);
     /* Read the offset unconditionally, even if MD_FEATURE_RECOVERY_OFFSET
      * is not set
      */
 
     if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RECOVERY_OFFSET))
         rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
 
     /* The other node finished recovery, call spare_active to set
      * device In_sync and mddev->degraded
      */
     if (rdev->recovery_offset == MaxSector &&
         !test_bit(In_sync, &rdev->flags) &&
         mddev->pers->spare_active(mddev))
         sysfs_notify_dirent_safe(mddev->sysfs_degraded);
 
     put_page(swapout);
     return 0;
 }
 
 void md_reload_sb(struct mddev *mddev, int nr)
 {
     struct md_rdev *rdev = NULL, *iter;
     int err;
 
     /* Find the rdev */
     rdev_for_each_rcu(iter, mddev) {
         if (iter->desc_nr == nr) {
             rdev = iter;
             break;
         }
     }
 
     if (!rdev) {
         pr_warn("%s: %d Could not find rdev with nr %d\n", __func__, __LINE__, nr);
         return;
     }
 
     err = read_rdev(mddev, rdev);
     if (err < 0)
         return;
 
     check_sb_changes(mddev, rdev);
 
     /* Read all rdev's to update recovery_offset */
     rdev_for_each_rcu(rdev, mddev) {
         if (!test_bit(Faulty, &rdev->flags))
             read_rdev(mddev, rdev);
     }
 }
 EXPORT_SYMBOL(md_reload_sb);
 
 #ifndef MODULE
 
 /*
  * Searches all registered partitions for autorun RAID arrays
  * at boot time.
  */
 
 static DEFINE_MUTEX(detected_devices_mutex);
 static LIST_HEAD(all_detected_devices);
 struct detected_devices_node {
     struct list_head list;
     dev_t dev;
 };
 
 void md_autodetect_dev(dev_t dev)
 {
     struct detected_devices_node *node_detected_dev;
 
     node_detected_dev = kzalloc(sizeof(*node_detected_dev), GFP_KERNEL);
     if (node_detected_dev) {
         node_detected_dev->dev = dev;
         mutex_lock(&detected_devices_mutex);
         list_add_tail(&node_detected_dev->list, &all_detected_devices);
         mutex_unlock(&detected_devices_mutex);
     }
 }
 
 void md_autostart_arrays(int part)
 {
     struct md_rdev *rdev;
     struct detected_devices_node *node_detected_dev;
     dev_t dev;
     int i_scanned, i_passed;
 
     i_scanned = 0;
     i_passed = 0;
 
     pr_info("md: Autodetecting RAID arrays.\n");
 
     mutex_lock(&detected_devices_mutex);
     while (!list_empty(&all_detected_devices) && i_scanned < INT_MAX) {
         i_scanned++;
         node_detected_dev = list_entry(all_detected_devices.next,
                     struct detected_devices_node, list);
         list_del(&node_detected_dev->list);
         dev = node_detected_dev->dev;
         kfree(node_detected_dev);
         mutex_unlock(&detected_devices_mutex);
         rdev = md_import_device(dev,0, 90);
         mutex_lock(&detected_devices_mutex);
         if (IS_ERR(rdev))
             continue;
 
         if (test_bit(Faulty, &rdev->flags))
             continue;
 
         set_bit(AutoDetected, &rdev->flags);
         list_add(&rdev->same_set, &pending_raid_disks);
         i_passed++;
     }
     mutex_unlock(&detected_devices_mutex);
 
     pr_debug("md: Scanned %d and added %d devices.\n", i_scanned, i_passed);
 
     autorun_devices(part);
 }
 
 #endif /* !MODULE */
 
 static __exit void md_exit(void)
 {
     struct mddev *mddev, *n;
     int delay = 1;
 
     unregister_blkdev(MD_MAJOR,"md");
     unregister_blkdev(mdp_major, "mdp");
     unregister_reboot_notifier(&md_notifier);
     unregister_sysctl_table(raid_table_header);
 
     /* We cannot unload the modules while some process is
      * waiting for us in select() or poll() - wake them up
      */
     md_unloading = 1;
     while (waitqueue_active(&md_event_waiters)) {
         /* not safe to leave yet */
         wake_up(&md_event_waiters);
         msleep(delay);
         delay += delay;
     }
     remove_proc_entry("mdstat", NULL);
 
     spin_lock(&all_mddevs_lock);
     list_for_each_entry_safe(mddev, n, &all_mddevs, all_mddevs) {
         if (!mddev_get(mddev))
             continue;
         spin_unlock(&all_mddevs_lock);
         export_array(mddev);
         mddev->ctime = 0;
         mddev->hold_active = 0;
         /*
          * As the mddev is now fully clear, mddev_put will schedule
          * the mddev for destruction by a workqueue, and the
          * destroy_workqueue() below will wait for that to complete.
          */
         mddev_put(mddev);
         spin_lock(&all_mddevs_lock);
     }
     spin_unlock(&all_mddevs_lock);
 
     destroy_workqueue(md_rdev_misc_wq);
     destroy_workqueue(md_misc_wq);
     destroy_workqueue(md_wq);
 }
 
 subsys_initcall(md_init);
 module_exit(md_exit)
 
 static int get_ro(char *buffer, const struct kernel_param *kp)
 {
     return sprintf(buffer, "%d\n", start_readonly);
 }
 static int set_ro(const char *val, const struct kernel_param *kp)
 {
     return kstrtouint(val, 10, (unsigned int *)&start_readonly);
 }
 
 module_param_call(start_ro, set_ro, get_ro, NULL, S_IRUSR|S_IWUSR);
 module_param(start_dirty_degraded, int, S_IRUGO|S_IWUSR);
 module_param_call(new_array, add_named_array, NULL, NULL, S_IWUSR);
 module_param(create_on_open, bool, S_IRUSR|S_IWUSR);
 
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("MD RAID framework");
 MODULE_ALIAS("md");
 MODULE_ALIAS_BLOCKDEV_MAJOR(MD_MAJOR);