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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-only
 /*
  * bitmap.c two-level bitmap (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
  *
  * bitmap_create  - sets up the bitmap structure
  * bitmap_destroy - destroys the bitmap structure
  *
  * additions, Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.:
  * - added disk storage for bitmap
  * - changes to allow various bitmap chunk sizes
  */
 
 /*
  * Still to do:
  *
  * flush after percent set rather than just time based. (maybe both).
  */
 
 #include <linux/blkdev.h>
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/timer.h>
 #include <linux/sched.h>
 #include <linux/list.h>
 #include <linux/file.h>
 #include <linux/mount.h>
 #include <linux/buffer_head.h>
 #include <linux/seq_file.h>
 #include <trace/events/block.h>
 #include "md.h"
 #include "md-bitmap.h"
 
 static inline char *bmname(struct bitmap *bitmap)
 {
     return bitmap->mddev ? mdname(bitmap->mddev) : "mdX";
 }
 
 /*
  * check a page and, if necessary, allocate it (or hijack it if the alloc fails)
  *
  * 1) check to see if this page is allocated, if it's not then try to alloc
  * 2) if the alloc fails, set the page's hijacked flag so we'll use the
  *    page pointer directly as a counter
  *
  * if we find our page, we increment the page's refcount so that it stays
  * allocated while we're using it
  */
 static int md_bitmap_checkpage(struct bitmap_counts *bitmap,
                    unsigned long page, int create, int no_hijack)
 __releases(bitmap->lock)
 __acquires(bitmap->lock)
 {
     unsigned char *mappage;
 
     if (page >= bitmap->pages) {
         /* This can happen if bitmap_start_sync goes beyond
          * End-of-device while looking for a whole page.
          * It is harmless.
          */
         return -EINVAL;
     }
 
     if (bitmap->bp[page].hijacked) /* it's hijacked, don't try to alloc */
         return 0;
 
     if (bitmap->bp[page].map) /* page is already allocated, just return */
         return 0;
 
     if (!create)
         return -ENOENT;
 
     /* this page has not been allocated yet */
 
     spin_unlock_irq(&bitmap->lock);
     /* It is possible that this is being called inside a
      * prepare_to_wait/finish_wait loop from raid5c:make_request().
      * In general it is not permitted to sleep in that context as it
      * can cause the loop to spin freely.
      * That doesn't apply here as we can only reach this point
      * once with any loop.
      * When this function completes, either bp[page].map or
      * bp[page].hijacked.  In either case, this function will
      * abort before getting to this point again.  So there is
      * no risk of a free-spin, and so it is safe to assert
      * that sleeping here is allowed.
      */
     sched_annotate_sleep();
     mappage = kzalloc(PAGE_SIZE, GFP_NOIO);
     spin_lock_irq(&bitmap->lock);
 
     if (mappage == NULL) {
         pr_debug("md/bitmap: map page allocation failed, hijacking\n");
         /* We don't support hijack for cluster raid */
         if (no_hijack)
             return -ENOMEM;
         /* failed - set the hijacked flag so that we can use the
          * pointer as a counter */
         if (!bitmap->bp[page].map)
             bitmap->bp[page].hijacked = 1;
     } else if (bitmap->bp[page].map ||
            bitmap->bp[page].hijacked) {
         /* somebody beat us to getting the page */
         kfree(mappage);
     } else {
 
         /* no page was in place and we have one, so install it */
 
         bitmap->bp[page].map = mappage;
         bitmap->missing_pages--;
     }
     return 0;
 }
 
 /* if page is completely empty, put it back on the free list, or dealloc it */
 /* if page was hijacked, unmark the flag so it might get alloced next time */
 /* Note: lock should be held when calling this */
 static void md_bitmap_checkfree(struct bitmap_counts *bitmap, unsigned long page)
 {
     char *ptr;
 
     if (bitmap->bp[page].count) /* page is still busy */
         return;
 
     /* page is no longer in use, it can be released */
 
     if (bitmap->bp[page].hijacked) { /* page was hijacked, undo this now */
         bitmap->bp[page].hijacked = 0;
         bitmap->bp[page].map = NULL;
     } else {
         /* normal case, free the page */
         ptr = bitmap->bp[page].map;
         bitmap->bp[page].map = NULL;
         bitmap->missing_pages++;
         kfree(ptr);
     }
 }
 
 /*
  * bitmap file handling - read and write the bitmap file and its superblock
  */
 
 /*
  * basic page I/O operations
  */
 
 /* IO operations when bitmap is stored near all superblocks */
 static int read_sb_page(struct mddev *mddev, loff_t offset,
             struct page *page,
             unsigned long index, int size)
 {
     /* choose a good rdev and read the page from there */
 
     struct md_rdev *rdev;
     sector_t target;
 
     rdev_for_each(rdev, mddev) {
         if (! test_bit(In_sync, &rdev->flags)
             || test_bit(Faulty, &rdev->flags)
             || test_bit(Bitmap_sync, &rdev->flags))
             continue;
 
         target = offset + index * (PAGE_SIZE/512);
 
         if (sync_page_io(rdev, target,
                  roundup(size, bdev_logical_block_size(rdev->bdev)),
                  page, REQ_OP_READ, true)) {
             page->index = index;
             return 0;
         }
     }
     return -EIO;
 }
 
 static struct md_rdev *next_active_rdev(struct md_rdev *rdev, struct mddev *mddev)
 {
     /* Iterate the disks of an mddev, using rcu to protect access to the
      * linked list, and raising the refcount of devices we return to ensure
      * they don't disappear while in use.
      * As devices are only added or removed when raid_disk is < 0 and
      * nr_pending is 0 and In_sync is clear, the entries we return will
      * still be in the same position on the list when we re-enter
      * list_for_each_entry_continue_rcu.
      *
      * Note that if entered with 'rdev == NULL' to start at the
      * beginning, we temporarily assign 'rdev' to an address which
      * isn't really an rdev, but which can be used by
      * list_for_each_entry_continue_rcu() to find the first entry.
      */
     rcu_read_lock();
     if (rdev == NULL)
         /* start at the beginning */
         rdev = list_entry(&mddev->disks, struct md_rdev, same_set);
     else {
         /* release the previous rdev and start from there. */
         rdev_dec_pending(rdev, mddev);
     }
     list_for_each_entry_continue_rcu(rdev, &mddev->disks, same_set) {
         if (rdev->raid_disk >= 0 &&
             !test_bit(Faulty, &rdev->flags)) {
             /* this is a usable devices */
             atomic_inc(&rdev->nr_pending);
             rcu_read_unlock();
             return rdev;
         }
     }
     rcu_read_unlock();
     return NULL;
 }
 
 static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
 {
     struct md_rdev *rdev;
     struct block_device *bdev;
     struct mddev *mddev = bitmap->mddev;
     struct bitmap_storage *store = &bitmap->storage;
 
 restart:
     rdev = NULL;
     while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {
         int size = PAGE_SIZE;
         loff_t offset = mddev->bitmap_info.offset;
 
         bdev = (rdev->meta_bdev) ? rdev->meta_bdev : rdev->bdev;
 
         if (page->index == store->file_pages-1) {
             int last_page_size = store->bytes & (PAGE_SIZE-1);
             if (last_page_size == 0)
                 last_page_size = PAGE_SIZE;
             size = roundup(last_page_size,
                        bdev_logical_block_size(bdev));
         }
         /* Just make sure we aren't corrupting data or
          * metadata
          */
         if (mddev->external) {
             /* Bitmap could be anywhere. */
             if (rdev->sb_start + offset + (page->index
                                * (PAGE_SIZE/512))
                 > rdev->data_offset
                 &&
                 rdev->sb_start + offset
                 < (rdev->data_offset + mddev->dev_sectors
                  + (PAGE_SIZE/512)))
                 goto bad_alignment;
         } else if (offset < 0) {
             /* DATA  BITMAP METADATA  */
             if (offset
                 + (long)(page->index * (PAGE_SIZE/512))
                 + size/512 > 0)
                 /* bitmap runs in to metadata */
                 goto bad_alignment;
             if (rdev->data_offset + mddev->dev_sectors
                 > rdev->sb_start + offset)
                 /* data runs in to bitmap */
                 goto bad_alignment;
         } else if (rdev->sb_start < rdev->data_offset) {
             /* METADATA BITMAP DATA */
             if (rdev->sb_start
                 + offset
                 + page->index*(PAGE_SIZE/512) + size/512
                 > rdev->data_offset)
                 /* bitmap runs in to data */
                 goto bad_alignment;
         } else {
             /* DATA METADATA BITMAP - no problems */
         }
         md_super_write(mddev, rdev,
                    rdev->sb_start + offset
                    + page->index * (PAGE_SIZE/512),
                    size,
                    page);
     }
 
     if (wait && md_super_wait(mddev) < 0)
         goto restart;
     return 0;
 
  bad_alignment:
     return -EINVAL;
 }
 
 static void md_bitmap_file_kick(struct bitmap *bitmap);
 /*
  * write out a page to a file
  */
 static void write_page(struct bitmap *bitmap, struct page *page, int wait)
 {
     struct buffer_head *bh;
 
     if (bitmap->storage.file == NULL) {
         switch (write_sb_page(bitmap, page, wait)) {
         case -EINVAL:
             set_bit(BITMAP_WRITE_ERROR, &bitmap->flags);
         }
     } else {
 
         bh = page_buffers(page);
 
         while (bh && bh->b_blocknr) {
             atomic_inc(&bitmap->pending_writes);
             set_buffer_locked(bh);
             set_buffer_mapped(bh);
             submit_bh(REQ_OP_WRITE | REQ_SYNC, bh);
             bh = bh->b_this_page;
         }
 
         if (wait)
             wait_event(bitmap->write_wait,
                    atomic_read(&bitmap->pending_writes)==0);
     }
     if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
         md_bitmap_file_kick(bitmap);
 }
 
 static void end_bitmap_write(struct buffer_head *bh, int uptodate)
 {
     struct bitmap *bitmap = bh->b_private;
 
     if (!uptodate)
         set_bit(BITMAP_WRITE_ERROR, &bitmap->flags);
     if (atomic_dec_and_test(&bitmap->pending_writes))
         wake_up(&bitmap->write_wait);
 }
 
 static void free_buffers(struct page *page)
 {
     struct buffer_head *bh;
 
     if (!PagePrivate(page))
         return;
 
     bh = page_buffers(page);
     while (bh) {
         struct buffer_head *next = bh->b_this_page;
         free_buffer_head(bh);
         bh = next;
     }
     detach_page_private(page);
     put_page(page);
 }
 
 /* read a page from a file.
  * We both read the page, and attach buffers to the page to record the
  * address of each block (using bmap).  These addresses will be used
  * to write the block later, completely bypassing the filesystem.
  * This usage is similar to how swap files are handled, and allows us
  * to write to a file with no concerns of memory allocation failing.
  */
 static int read_page(struct file *file, unsigned long index,
              struct bitmap *bitmap,
              unsigned long count,
              struct page *page)
 {
     int ret = 0;
     struct inode *inode = file_inode(file);
     struct buffer_head *bh;
     sector_t block, blk_cur;
     unsigned long blocksize = i_blocksize(inode);
 
     pr_debug("read bitmap file (%dB @ %llu)\n", (int)PAGE_SIZE,
          (unsigned long long)index << PAGE_SHIFT);
 
     bh = alloc_page_buffers(page, blocksize, false);
     if (!bh) {
         ret = -ENOMEM;
         goto out;
     }
     attach_page_private(page, bh);
     blk_cur = index << (PAGE_SHIFT - inode->i_blkbits);
     while (bh) {
         block = blk_cur;
 
         if (count == 0)
             bh->b_blocknr = 0;
         else {
             ret = bmap(inode, &block);
             if (ret || !block) {
                 ret = -EINVAL;
                 bh->b_blocknr = 0;
                 goto out;
             }
 
             bh->b_blocknr = block;
             bh->b_bdev = inode->i_sb->s_bdev;
             if (count < blocksize)
                 count = 0;
             else
                 count -= blocksize;
 
             bh->b_end_io = end_bitmap_write;
             bh->b_private = bitmap;
             atomic_inc(&bitmap->pending_writes);
             set_buffer_locked(bh);
             set_buffer_mapped(bh);
             submit_bh(REQ_OP_READ, bh);
         }
         blk_cur++;
         bh = bh->b_this_page;
     }
     page->index = index;
 
     wait_event(bitmap->write_wait,
            atomic_read(&bitmap->pending_writes)==0);
     if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
         ret = -EIO;
 out:
     if (ret)
         pr_err("md: bitmap read error: (%dB @ %llu): %d\n",
                (int)PAGE_SIZE,
                (unsigned long long)index << PAGE_SHIFT,
                ret);
     return ret;
 }
 
 /*
  * bitmap file superblock operations
  */
 
 /*
  * md_bitmap_wait_writes() should be called before writing any bitmap
  * blocks, to ensure previous writes, particularly from
  * md_bitmap_daemon_work(), have completed.
  */
 static void md_bitmap_wait_writes(struct bitmap *bitmap)
 {
     if (bitmap->storage.file)
         wait_event(bitmap->write_wait,
                atomic_read(&bitmap->pending_writes)==0);
     else
         /* Note that we ignore the return value.  The writes
          * might have failed, but that would just mean that
          * some bits which should be cleared haven't been,
          * which is safe.  The relevant bitmap blocks will
          * probably get written again, but there is no great
          * loss if they aren't.
          */
         md_super_wait(bitmap->mddev);
 }
 
 
 /* update the event counter and sync the superblock to disk */
 void md_bitmap_update_sb(struct bitmap *bitmap)
 {
     bitmap_super_t *sb;
 
     if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
         return;
     if (bitmap->mddev->bitmap_info.external)
         return;
     if (!bitmap->storage.sb_page) /* no superblock */
         return;
     sb = kmap_atomic(bitmap->storage.sb_page);
     sb->events = cpu_to_le64(bitmap->mddev->events);
     if (bitmap->mddev->events < bitmap->events_cleared)
         /* rocking back to read-only */
         bitmap->events_cleared = bitmap->mddev->events;
     sb->events_cleared = cpu_to_le64(bitmap->events_cleared);
     /*
      * clear BITMAP_WRITE_ERROR bit to protect against the case that
      * a bitmap write error occurred but the later writes succeeded.
      */
     sb->state = cpu_to_le32(bitmap->flags & ~BIT(BITMAP_WRITE_ERROR));
     /* Just in case these have been changed via sysfs: */
     sb->daemon_sleep = cpu_to_le32(bitmap->mddev->bitmap_info.daemon_sleep/HZ);
     sb->write_behind = cpu_to_le32(bitmap->mddev->bitmap_info.max_write_behind);
     /* This might have been changed by a reshape */
     sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
     sb->chunksize = cpu_to_le32(bitmap->mddev->bitmap_info.chunksize);
     sb->nodes = cpu_to_le32(bitmap->mddev->bitmap_info.nodes);
     sb->sectors_reserved = cpu_to_le32(bitmap->mddev->
                        bitmap_info.space);
     kunmap_atomic(sb);
     write_page(bitmap, bitmap->storage.sb_page, 1);
 }
 EXPORT_SYMBOL(md_bitmap_update_sb);
 
 /* print out the bitmap file superblock */
 void md_bitmap_print_sb(struct bitmap *bitmap)
 {
     bitmap_super_t *sb;
 
     if (!bitmap || !bitmap->storage.sb_page)
         return;
     sb = kmap_atomic(bitmap->storage.sb_page);
     pr_debug("%s: bitmap file superblock:\n", bmname(bitmap));
     pr_debug("         magic: %08x\n", le32_to_cpu(sb->magic));
     pr_debug("       version: %d\n", le32_to_cpu(sb->version));
     pr_debug("          uuid: %08x.%08x.%08x.%08x\n",
          le32_to_cpu(*(__le32 *)(sb->uuid+0)),
          le32_to_cpu(*(__le32 *)(sb->uuid+4)),
          le32_to_cpu(*(__le32 *)(sb->uuid+8)),
          le32_to_cpu(*(__le32 *)(sb->uuid+12)));
     pr_debug("        events: %llu\n",
          (unsigned long long) le64_to_cpu(sb->events));
     pr_debug("events cleared: %llu\n",
          (unsigned long long) le64_to_cpu(sb->events_cleared));
     pr_debug("         state: %08x\n", le32_to_cpu(sb->state));
     pr_debug("     chunksize: %d B\n", le32_to_cpu(sb->chunksize));
     pr_debug("  daemon sleep: %ds\n", le32_to_cpu(sb->daemon_sleep));
     pr_debug("     sync size: %llu KB\n",
          (unsigned long long)le64_to_cpu(sb->sync_size)/2);
     pr_debug("max write behind: %d\n", le32_to_cpu(sb->write_behind));
     kunmap_atomic(sb);
 }
 
 /*
  * bitmap_new_disk_sb
  * @bitmap
  *
  * This function is somewhat the reverse of bitmap_read_sb.  bitmap_read_sb
  * reads and verifies the on-disk bitmap superblock and populates bitmap_info.
  * This function verifies 'bitmap_info' and populates the on-disk bitmap
  * structure, which is to be written to disk.
  *
  * Returns: 0 on success, -Exxx on error
  */
 static int md_bitmap_new_disk_sb(struct bitmap *bitmap)
 {
     bitmap_super_t *sb;
     unsigned long chunksize, daemon_sleep, write_behind;
 
     bitmap->storage.sb_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
     if (bitmap->storage.sb_page == NULL)
         return -ENOMEM;
     bitmap->storage.sb_page->index = 0;
 
     sb = kmap_atomic(bitmap->storage.sb_page);
 
     sb->magic = cpu_to_le32(BITMAP_MAGIC);
     sb->version = cpu_to_le32(BITMAP_MAJOR_HI);
 
     chunksize = bitmap->mddev->bitmap_info.chunksize;
     BUG_ON(!chunksize);
     if (!is_power_of_2(chunksize)) {
         kunmap_atomic(sb);
         pr_warn("bitmap chunksize not a power of 2\n");
         return -EINVAL;
     }
     sb->chunksize = cpu_to_le32(chunksize);
 
     daemon_sleep = bitmap->mddev->bitmap_info.daemon_sleep;
     if (!daemon_sleep || (daemon_sleep > MAX_SCHEDULE_TIMEOUT)) {
         pr_debug("Choosing daemon_sleep default (5 sec)\n");
         daemon_sleep = 5 * HZ;
     }
     sb->daemon_sleep = cpu_to_le32(daemon_sleep);
     bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
 
     /*
      * FIXME: write_behind for RAID1.  If not specified, what
      * is a good choice?  We choose COUNTER_MAX / 2 arbitrarily.
      */
     write_behind = bitmap->mddev->bitmap_info.max_write_behind;
     if (write_behind > COUNTER_MAX)
         write_behind = COUNTER_MAX / 2;
     sb->write_behind = cpu_to_le32(write_behind);
     bitmap->mddev->bitmap_info.max_write_behind = write_behind;
 
     /* keep the array size field of the bitmap superblock up to date */
     sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
 
     memcpy(sb->uuid, bitmap->mddev->uuid, 16);
 
     set_bit(BITMAP_STALE, &bitmap->flags);
     sb->state = cpu_to_le32(bitmap->flags);
     bitmap->events_cleared = bitmap->mddev->events;
     sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
     bitmap->mddev->bitmap_info.nodes = 0;
 
     kunmap_atomic(sb);
 
     return 0;
 }
 
 /* read the superblock from the bitmap file and initialize some bitmap fields */
 static int md_bitmap_read_sb(struct bitmap *bitmap)
 {
     char *reason = NULL;
     bitmap_super_t *sb;
     unsigned long chunksize, daemon_sleep, write_behind;
     unsigned long long events;
     int nodes = 0;
     unsigned long sectors_reserved = 0;
     int err = -EINVAL;
     struct page *sb_page;
     loff_t offset = bitmap->mddev->bitmap_info.offset;
 
     if (!bitmap->storage.file && !bitmap->mddev->bitmap_info.offset) {
         chunksize = 128 * 1024 * 1024;
         daemon_sleep = 5 * HZ;
         write_behind = 0;
         set_bit(BITMAP_STALE, &bitmap->flags);
         err = 0;
         goto out_no_sb;
     }
     /* page 0 is the superblock, read it... */
     sb_page = alloc_page(GFP_KERNEL);
     if (!sb_page)
         return -ENOMEM;
     bitmap->storage.sb_page = sb_page;
 
 re_read:
     /* If cluster_slot is set, the cluster is setup */
     if (bitmap->cluster_slot >= 0) {
         sector_t bm_blocks = bitmap->mddev->resync_max_sectors;
 
         bm_blocks = DIV_ROUND_UP_SECTOR_T(bm_blocks,
                (bitmap->mddev->bitmap_info.chunksize >> 9));
         /* bits to bytes */
         bm_blocks = ((bm_blocks+7) >> 3) + sizeof(bitmap_super_t);
         /* to 4k blocks */
         bm_blocks = DIV_ROUND_UP_SECTOR_T(bm_blocks, 4096);
         offset = bitmap->mddev->bitmap_info.offset + (bitmap->cluster_slot * (bm_blocks << 3));
         pr_debug("%s:%d bm slot: %d offset: %llu\n", __func__, __LINE__,
             bitmap->cluster_slot, offset);
     }
 
     if (bitmap->storage.file) {
         loff_t isize = i_size_read(bitmap->storage.file->f_mapping->host);
         int bytes = isize > PAGE_SIZE ? PAGE_SIZE : isize;
 
         err = read_page(bitmap->storage.file, 0,
                 bitmap, bytes, sb_page);
     } else {
         err = read_sb_page(bitmap->mddev,
                    offset,
                    sb_page,
                    0, sizeof(bitmap_super_t));
     }
     if (err)
         return err;
 
     err = -EINVAL;
     sb = kmap_atomic(sb_page);
 
     chunksize = le32_to_cpu(sb->chunksize);
     daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
     write_behind = le32_to_cpu(sb->write_behind);
     sectors_reserved = le32_to_cpu(sb->sectors_reserved);
 
     /* verify that the bitmap-specific fields are valid */
     if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
         reason = "bad magic";
     else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
          le32_to_cpu(sb->version) > BITMAP_MAJOR_CLUSTERED)
         reason = "unrecognized superblock version";
     else if (chunksize < 512)
         reason = "bitmap chunksize too small";
     else if (!is_power_of_2(chunksize))
         reason = "bitmap chunksize not a power of 2";
     else if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT)
         reason = "daemon sleep period out of range";
     else if (write_behind > COUNTER_MAX)
         reason = "write-behind limit out of range (0 - 16383)";
     if (reason) {
         pr_warn("%s: invalid bitmap file superblock: %s\n",
             bmname(bitmap), reason);
         goto out;
     }
 
     /*
      * Setup nodes/clustername only if bitmap version is
      * cluster-compatible
      */
     if (sb->version == cpu_to_le32(BITMAP_MAJOR_CLUSTERED)) {
         nodes = le32_to_cpu(sb->nodes);
         strscpy(bitmap->mddev->bitmap_info.cluster_name,
                 sb->cluster_name, 64);
     }
 
     /* keep the array size field of the bitmap superblock up to date */
     sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
 
     if (bitmap->mddev->persistent) {
         /*
          * We have a persistent array superblock, so compare the
          * bitmap's UUID and event counter to the mddev's
          */
         if (memcmp(sb->uuid, bitmap->mddev->uuid, 16)) {
             pr_warn("%s: bitmap superblock UUID mismatch\n",
                 bmname(bitmap));
             goto out;
         }
         events = le64_to_cpu(sb->events);
         if (!nodes && (events < bitmap->mddev->events)) {
             pr_warn("%s: bitmap file is out of date (%llu < %llu) -- forcing full recovery\n",
                 bmname(bitmap), events,
                 (unsigned long long) bitmap->mddev->events);
             set_bit(BITMAP_STALE, &bitmap->flags);
         }
     }
 
     /* assign fields using values from superblock */
     bitmap->flags |= le32_to_cpu(sb->state);
     if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
         set_bit(BITMAP_HOSTENDIAN, &bitmap->flags);
     bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
     err = 0;
 
 out:
     kunmap_atomic(sb);
     if (err == 0 && nodes && (bitmap->cluster_slot < 0)) {
         /* Assigning chunksize is required for "re_read" */
         bitmap->mddev->bitmap_info.chunksize = chunksize;
         err = md_setup_cluster(bitmap->mddev, nodes);
         if (err) {
             pr_warn("%s: Could not setup cluster service (%d)\n",
                 bmname(bitmap), err);
             goto out_no_sb;
         }
         bitmap->cluster_slot = md_cluster_ops->slot_number(bitmap->mddev);
         goto re_read;
     }
 
 out_no_sb:
     if (err == 0) {
         if (test_bit(BITMAP_STALE, &bitmap->flags))
             bitmap->events_cleared = bitmap->mddev->events;
         bitmap->mddev->bitmap_info.chunksize = chunksize;
         bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
         bitmap->mddev->bitmap_info.max_write_behind = write_behind;
         bitmap->mddev->bitmap_info.nodes = nodes;
         if (bitmap->mddev->bitmap_info.space == 0 ||
             bitmap->mddev->bitmap_info.space > sectors_reserved)
             bitmap->mddev->bitmap_info.space = sectors_reserved;
     } else {
         md_bitmap_print_sb(bitmap);
         if (bitmap->cluster_slot < 0)
             md_cluster_stop(bitmap->mddev);
     }
     return err;
 }
 
 /*
  * general bitmap file operations
  */
 
 /*
  * on-disk bitmap:
  *
  * Use one bit per "chunk" (block set). We do the disk I/O on the bitmap
  * file a page at a time. There's a superblock at the start of the file.
  */
 /* calculate the index of the page that contains this bit */
 static inline unsigned long file_page_index(struct bitmap_storage *store,
                         unsigned long chunk)
 {
     if (store->sb_page)
         chunk += sizeof(bitmap_super_t) << 3;
     return chunk >> PAGE_BIT_SHIFT;
 }
 
 /* calculate the (bit) offset of this bit within a page */
 static inline unsigned long file_page_offset(struct bitmap_storage *store,
                          unsigned long chunk)
 {
     if (store->sb_page)
         chunk += sizeof(bitmap_super_t) << 3;
     return chunk & (PAGE_BITS - 1);
 }
 
 /*
  * return a pointer to the page in the filemap that contains the given bit
  *
  */
 static inline struct page *filemap_get_page(struct bitmap_storage *store,
                         unsigned long chunk)
 {
     if (file_page_index(store, chunk) >= store->file_pages)
         return NULL;
     return store->filemap[file_page_index(store, chunk)];
 }
 
 static int md_bitmap_storage_alloc(struct bitmap_storage *store,
                    unsigned long chunks, int with_super,
                    int slot_number)
 {
     int pnum, offset = 0;
     unsigned long num_pages;
     unsigned long bytes;
 
     bytes = DIV_ROUND_UP(chunks, 8);
     if (with_super)
         bytes += sizeof(bitmap_super_t);
 
     num_pages = DIV_ROUND_UP(bytes, PAGE_SIZE);
     offset = slot_number * num_pages;
 
     store->filemap = kmalloc_array(num_pages, sizeof(struct page *),
                        GFP_KERNEL);
     if (!store->filemap)
         return -ENOMEM;
 
     if (with_super && !store->sb_page) {
         store->sb_page = alloc_page(GFP_KERNEL|__GFP_ZERO);
         if (store->sb_page == NULL)
             return -ENOMEM;
     }
 
     pnum = 0;
     if (store->sb_page) {
         store->filemap[0] = store->sb_page;
         pnum = 1;
         store->sb_page->index = offset;
     }
 
     for ( ; pnum < num_pages; pnum++) {
         store->filemap[pnum] = alloc_page(GFP_KERNEL|__GFP_ZERO);
         if (!store->filemap[pnum]) {
             store->file_pages = pnum;
             return -ENOMEM;
         }
         store->filemap[pnum]->index = pnum + offset;
     }
     store->file_pages = pnum;
 
     /* We need 4 bits per page, rounded up to a multiple
      * of sizeof(unsigned long) */
     store->filemap_attr = kzalloc(
         roundup(DIV_ROUND_UP(num_pages*4, 8), sizeof(unsigned long)),
         GFP_KERNEL);
     if (!store->filemap_attr)
         return -ENOMEM;
 
     store->bytes = bytes;
 
     return 0;
 }
 
 static void md_bitmap_file_unmap(struct bitmap_storage *store)
 {
     struct page **map, *sb_page;
     int pages;
     struct file *file;
 
     file = store->file;
     map = store->filemap;
     pages = store->file_pages;
     sb_page = store->sb_page;
 
     while (pages--)
         if (map[pages] != sb_page) /* 0 is sb_page, release it below */
             free_buffers(map[pages]);
     kfree(map);
     kfree(store->filemap_attr);
 
     if (sb_page)
         free_buffers(sb_page);
 
     if (file) {
         struct inode *inode = file_inode(file);
         invalidate_mapping_pages(inode->i_mapping, 0, -1);
         fput(file);
     }
 }
 
 /*
  * bitmap_file_kick - if an error occurs while manipulating the bitmap file
  * then it is no longer reliable, so we stop using it and we mark the file
  * as failed in the superblock
  */
 static void md_bitmap_file_kick(struct bitmap *bitmap)
 {
     char *path, *ptr = NULL;
 
     if (!test_and_set_bit(BITMAP_STALE, &bitmap->flags)) {
         md_bitmap_update_sb(bitmap);
 
         if (bitmap->storage.file) {
             path = kmalloc(PAGE_SIZE, GFP_KERNEL);
             if (path)
                 ptr = file_path(bitmap->storage.file,
                          path, PAGE_SIZE);
 
             pr_warn("%s: kicking failed bitmap file %s from array!\n",
                 bmname(bitmap), IS_ERR(ptr) ? "" : ptr);
 
             kfree(path);
         } else
             pr_warn("%s: disabling internal bitmap due to errors\n",
                 bmname(bitmap));
     }
 }
 
 enum bitmap_page_attr {
     BITMAP_PAGE_DIRTY = 0,     /* there are set bits that need to be synced */
     BITMAP_PAGE_PENDING = 1,   /* there are bits that are being cleaned.
                     * i.e. counter is 1 or 2. */
     BITMAP_PAGE_NEEDWRITE = 2, /* there are cleared bits that need to be synced */
 };
 
 static inline void set_page_attr(struct bitmap *bitmap, int pnum,
                  enum bitmap_page_attr attr)
 {
     set_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
 }
 
 static inline void clear_page_attr(struct bitmap *bitmap, int pnum,
                    enum bitmap_page_attr attr)
 {
     clear_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
 }
 
 static inline int test_page_attr(struct bitmap *bitmap, int pnum,
                  enum bitmap_page_attr attr)
 {
     return test_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
 }
 
 static inline int test_and_clear_page_attr(struct bitmap *bitmap, int pnum,
                        enum bitmap_page_attr attr)
 {
     return test_and_clear_bit((pnum<<2) + attr,
                   bitmap->storage.filemap_attr);
 }
 /*
  * bitmap_file_set_bit -- called before performing a write to the md device
  * to set (and eventually sync) a particular bit in the bitmap file
  *
  * we set the bit immediately, then we record the page number so that
  * when an unplug occurs, we can flush the dirty pages out to disk
  */
 static void md_bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
 {
     unsigned long bit;
     struct page *page;
     void *kaddr;
     unsigned long chunk = block >> bitmap->counts.chunkshift;
     struct bitmap_storage *store = &bitmap->storage;
     unsigned long node_offset = 0;
 
     if (mddev_is_clustered(bitmap->mddev))
         node_offset = bitmap->cluster_slot * store->file_pages;
 
     page = filemap_get_page(&bitmap->storage, chunk);
     if (!page)
         return;
     bit = file_page_offset(&bitmap->storage, chunk);
 
     /* set the bit */
     kaddr = kmap_atomic(page);
     if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
         set_bit(bit, kaddr);
     else
         set_bit_le(bit, kaddr);
     kunmap_atomic(kaddr);
     pr_debug("set file bit %lu page %lu\n", bit, page->index);
     /* record page number so it gets flushed to disk when unplug occurs */
     set_page_attr(bitmap, page->index - node_offset, BITMAP_PAGE_DIRTY);
 }
 
 static void md_bitmap_file_clear_bit(struct bitmap *bitmap, sector_t block)
 {
     unsigned long bit;
     struct page *page;
     void *paddr;
     unsigned long chunk = block >> bitmap->counts.chunkshift;
     struct bitmap_storage *store = &bitmap->storage;
     unsigned long node_offset = 0;
 
     if (mddev_is_clustered(bitmap->mddev))
         node_offset = bitmap->cluster_slot * store->file_pages;
 
     page = filemap_get_page(&bitmap->storage, chunk);
     if (!page)
         return;
     bit = file_page_offset(&bitmap->storage, chunk);
     paddr = kmap_atomic(page);
     if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
         clear_bit(bit, paddr);
     else
         clear_bit_le(bit, paddr);
     kunmap_atomic(paddr);
     if (!test_page_attr(bitmap, page->index - node_offset, BITMAP_PAGE_NEEDWRITE)) {
         set_page_attr(bitmap, page->index - node_offset, BITMAP_PAGE_PENDING);
         bitmap->allclean = 0;
     }
 }
 
 static int md_bitmap_file_test_bit(struct bitmap *bitmap, sector_t block)
 {
     unsigned long bit;
     struct page *page;
     void *paddr;
     unsigned long chunk = block >> bitmap->counts.chunkshift;
     int set = 0;
 
     page = filemap_get_page(&bitmap->storage, chunk);
     if (!page)
         return -EINVAL;
     bit = file_page_offset(&bitmap->storage, chunk);
     paddr = kmap_atomic(page);
     if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
         set = test_bit(bit, paddr);
     else
         set = test_bit_le(bit, paddr);
     kunmap_atomic(paddr);
     return set;
 }
 
 
 /* this gets called when the md device is ready to unplug its underlying
  * (slave) device queues -- before we let any writes go down, we need to
  * sync the dirty pages of the bitmap file to disk */
 void md_bitmap_unplug(struct bitmap *bitmap)
 {
     unsigned long i;
     int dirty, need_write;
     int writing = 0;
 
     if (!bitmap || !bitmap->storage.filemap ||
         test_bit(BITMAP_STALE, &bitmap->flags))
         return;
 
     /* look at each page to see if there are any set bits that need to be
      * flushed out to disk */
     for (i = 0; i < bitmap->storage.file_pages; i++) {
         dirty = test_and_clear_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
         need_write = test_and_clear_page_attr(bitmap, i,
                               BITMAP_PAGE_NEEDWRITE);
         if (dirty || need_write) {
             if (!writing) {
                 md_bitmap_wait_writes(bitmap);
                 if (bitmap->mddev->queue)
                     blk_add_trace_msg(bitmap->mddev->queue,
                               "md bitmap_unplug");
             }
             clear_page_attr(bitmap, i, BITMAP_PAGE_PENDING);
             write_page(bitmap, bitmap->storage.filemap[i], 0);
             writing = 1;
         }
     }
     if (writing)
         md_bitmap_wait_writes(bitmap);
 
     if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
         md_bitmap_file_kick(bitmap);
 }
 EXPORT_SYMBOL(md_bitmap_unplug);
 
 static void md_bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed);
 /* * bitmap_init_from_disk -- called at bitmap_create time to initialize
  * the in-memory bitmap from the on-disk bitmap -- also, sets up the
  * memory mapping of the bitmap file
  * Special cases:
  *   if there's no bitmap file, or if the bitmap file had been
  *   previously kicked from the array, we mark all the bits as
  *   1's in order to cause a full resync.
  *
  * We ignore all bits for sectors that end earlier than 'start'.
  * This is used when reading an out-of-date bitmap...
  */
 static int md_bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 {
     unsigned long i, chunks, index, oldindex, bit, node_offset = 0;
     struct page *page = NULL;
     unsigned long bit_cnt = 0;
     struct file *file;
     unsigned long offset;
     int outofdate;
     int ret = -ENOSPC;
     void *paddr;
     struct bitmap_storage *store = &bitmap->storage;
 
     chunks = bitmap->counts.chunks;
     file = store->file;
 
     if (!file && !bitmap->mddev->bitmap_info.offset) {
         /* No permanent bitmap - fill with '1s'. */
         store->filemap = NULL;
         store->file_pages = 0;
         for (i = 0; i < chunks ; i++) {
             /* if the disk bit is set, set the memory bit */
             int needed = ((sector_t)(i+1) << (bitmap->counts.chunkshift)
                       >= start);
             md_bitmap_set_memory_bits(bitmap,
                           (sector_t)i << bitmap->counts.chunkshift,
                           needed);
         }
         return 0;
     }
 
     outofdate = test_bit(BITMAP_STALE, &bitmap->flags);
     if (outofdate)
         pr_warn("%s: bitmap file is out of date, doing full recovery\n", bmname(bitmap));
 
     if (file && i_size_read(file->f_mapping->host) < store->bytes) {
         pr_warn("%s: bitmap file too short %lu < %lu\n",
             bmname(bitmap),
             (unsigned long) i_size_read(file->f_mapping->host),
             store->bytes);
         goto err;
     }
 
     oldindex = ~0L;
     offset = 0;
     if (!bitmap->mddev->bitmap_info.external)
         offset = sizeof(bitmap_super_t);
 
     if (mddev_is_clustered(bitmap->mddev))
         node_offset = bitmap->cluster_slot * (DIV_ROUND_UP(store->bytes, PAGE_SIZE));
 
     for (i = 0; i < chunks; i++) {
         int b;
         index = file_page_index(&bitmap->storage, i);
         bit = file_page_offset(&bitmap->storage, i);
         if (index != oldindex) { /* this is a new page, read it in */
             int count;
             /* unmap the old page, we're done with it */
             if (index == store->file_pages-1)
                 count = store->bytes - index * PAGE_SIZE;
             else
                 count = PAGE_SIZE;
             page = store->filemap[index];
             if (file)
                 ret = read_page(file, index, bitmap,
                         count, page);
             else
                 ret = read_sb_page(
                     bitmap->mddev,
                     bitmap->mddev->bitmap_info.offset,
                     page,
                     index + node_offset, count);
 
             if (ret)
                 goto err;
 
             oldindex = index;
 
             if (outofdate) {
                 /*
                  * if bitmap is out of date, dirty the
                  * whole page and write it out
                  */
                 paddr = kmap_atomic(page);
                 memset(paddr + offset, 0xff,
                        PAGE_SIZE - offset);
                 kunmap_atomic(paddr);
                 write_page(bitmap, page, 1);
 
                 ret = -EIO;
                 if (test_bit(BITMAP_WRITE_ERROR,
                          &bitmap->flags))
                     goto err;
             }
         }
         paddr = kmap_atomic(page);
         if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
             b = test_bit(bit, paddr);
         else
             b = test_bit_le(bit, paddr);
         kunmap_atomic(paddr);
         if (b) {
             /* if the disk bit is set, set the memory bit */
             int needed = ((sector_t)(i+1) << bitmap->counts.chunkshift
                       >= start);
             md_bitmap_set_memory_bits(bitmap,
                           (sector_t)i << bitmap->counts.chunkshift,
                           needed);
             bit_cnt++;
         }
         offset = 0;
     }
 
     pr_debug("%s: bitmap initialized from disk: read %lu pages, set %lu of %lu bits\n",
          bmname(bitmap), store->file_pages,
          bit_cnt, chunks);
 
     return 0;
 
  err:
     pr_warn("%s: bitmap initialisation failed: %d\n",
         bmname(bitmap), ret);
     return ret;
 }
 
 void md_bitmap_write_all(struct bitmap *bitmap)
 {
     /* We don't actually write all bitmap blocks here,
      * just flag them as needing to be written
      */
     int i;
 
     if (!bitmap || !bitmap->storage.filemap)
         return;
     if (bitmap->storage.file)
         /* Only one copy, so nothing needed */
         return;
 
     for (i = 0; i < bitmap->storage.file_pages; i++)
         set_page_attr(bitmap, i,
                   BITMAP_PAGE_NEEDWRITE);
     bitmap->allclean = 0;
 }
 
 static void md_bitmap_count_page(struct bitmap_counts *bitmap,
                  sector_t offset, int inc)
 {
     sector_t chunk = offset >> bitmap->chunkshift;
     unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
     bitmap->bp[page].count += inc;
     md_bitmap_checkfree(bitmap, page);
 }
 
 static void md_bitmap_set_pending(struct bitmap_counts *bitmap, sector_t offset)
 {
     sector_t chunk = offset >> bitmap->chunkshift;
     unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
     struct bitmap_page *bp = &bitmap->bp[page];
 
     if (!bp->pending)
         bp->pending = 1;
 }
 
 static bitmap_counter_t *md_bitmap_get_counter(struct bitmap_counts *bitmap,
                            sector_t offset, sector_t *blocks,
                            int create);
 
 /*
  * bitmap daemon -- periodically wakes up to clean bits and flush pages
  *          out to disk
  */
 
 void md_bitmap_daemon_work(struct mddev *mddev)
 {
     struct bitmap *bitmap;
     unsigned long j;
     unsigned long nextpage;
     sector_t blocks;
     struct bitmap_counts *counts;
 
     /* Use a mutex to guard daemon_work against
      * bitmap_destroy.
      */
     mutex_lock(&mddev->bitmap_info.mutex);
     bitmap = mddev->bitmap;
     if (bitmap == NULL) {
         mutex_unlock(&mddev->bitmap_info.mutex);
         return;
     }
     if (time_before(jiffies, bitmap->daemon_lastrun
             + mddev->bitmap_info.daemon_sleep))
         goto done;
 
     bitmap->daemon_lastrun = jiffies;
     if (bitmap->allclean) {
         mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
         goto done;
     }
     bitmap->allclean = 1;
 
     if (bitmap->mddev->queue)
         blk_add_trace_msg(bitmap->mddev->queue,
                   "md bitmap_daemon_work");
 
     /* Any file-page which is PENDING now needs to be written.
      * So set NEEDWRITE now, then after we make any last-minute changes
      * we will write it.
      */
     for (j = 0; j < bitmap->storage.file_pages; j++)
         if (test_and_clear_page_attr(bitmap, j,
                          BITMAP_PAGE_PENDING))
             set_page_attr(bitmap, j,
                       BITMAP_PAGE_NEEDWRITE);
 
     if (bitmap->need_sync &&
         mddev->bitmap_info.external == 0) {
         /* Arrange for superblock update as well as
          * other changes */
         bitmap_super_t *sb;
         bitmap->need_sync = 0;
         if (bitmap->storage.filemap) {
             sb = kmap_atomic(bitmap->storage.sb_page);
             sb->events_cleared =
                 cpu_to_le64(bitmap->events_cleared);
             kunmap_atomic(sb);
             set_page_attr(bitmap, 0,
                       BITMAP_PAGE_NEEDWRITE);
         }
     }
     /* Now look at the bitmap counters and if any are '2' or '1',
      * decrement and handle accordingly.
      */
     counts = &bitmap->counts;
     spin_lock_irq(&counts->lock);
     nextpage = 0;
     for (j = 0; j < counts->chunks; j++) {
         bitmap_counter_t *bmc;
         sector_t  block = (sector_t)j << counts->chunkshift;
 
         if (j == nextpage) {
             nextpage += PAGE_COUNTER_RATIO;
             if (!counts->bp[j >> PAGE_COUNTER_SHIFT].pending) {
                 j |= PAGE_COUNTER_MASK;
                 continue;
             }
             counts->bp[j >> PAGE_COUNTER_SHIFT].pending = 0;
         }
 
         bmc = md_bitmap_get_counter(counts, block, &blocks, 0);
         if (!bmc) {
             j |= PAGE_COUNTER_MASK;
             continue;
         }
         if (*bmc == 1 && !bitmap->need_sync) {
             /* We can clear the bit */
             *bmc = 0;
             md_bitmap_count_page(counts, block, -1);
             md_bitmap_file_clear_bit(bitmap, block);
         } else if (*bmc && *bmc <= 2) {
             *bmc = 1;
             md_bitmap_set_pending(counts, block);
             bitmap->allclean = 0;
         }
     }
     spin_unlock_irq(&counts->lock);
 
     md_bitmap_wait_writes(bitmap);
     /* Now start writeout on any page in NEEDWRITE that isn't DIRTY.
      * DIRTY pages need to be written by bitmap_unplug so it can wait
      * for them.
      * If we find any DIRTY page we stop there and let bitmap_unplug
      * handle all the rest.  This is important in the case where
      * the first blocking holds the superblock and it has been updated.
      * We mustn't write any other blocks before the superblock.
      */
     for (j = 0;
          j < bitmap->storage.file_pages
              && !test_bit(BITMAP_STALE, &bitmap->flags);
          j++) {
         if (test_page_attr(bitmap, j,
                    BITMAP_PAGE_DIRTY))
             /* bitmap_unplug will handle the rest */
             break;
         if (bitmap->storage.filemap &&
             test_and_clear_page_attr(bitmap, j,
                          BITMAP_PAGE_NEEDWRITE)) {
             write_page(bitmap, bitmap->storage.filemap[j], 0);
         }
     }
 
  done:
     if (bitmap->allclean == 0)
         mddev->thread->timeout =
             mddev->bitmap_info.daemon_sleep;
     mutex_unlock(&mddev->bitmap_info.mutex);
 }
 
 static bitmap_counter_t *md_bitmap_get_counter(struct bitmap_counts *bitmap,
                            sector_t offset, sector_t *blocks,
                            int create)
 __releases(bitmap->lock)
 __acquires(bitmap->lock)
 {
     /* If 'create', we might release the lock and reclaim it.
      * The lock must have been taken with interrupts enabled.
      * If !create, we don't release the lock.
      */
     sector_t chunk = offset >> bitmap->chunkshift;
     unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
     unsigned long pageoff = (chunk & PAGE_COUNTER_MASK) << COUNTER_BYTE_SHIFT;
     sector_t csize;
     int err;
 
     err = md_bitmap_checkpage(bitmap, page, create, 0);
 
     if (bitmap->bp[page].hijacked ||
         bitmap->bp[page].map == NULL)
         csize = ((sector_t)1) << (bitmap->chunkshift +
                       PAGE_COUNTER_SHIFT);
     else
         csize = ((sector_t)1) << bitmap->chunkshift;
     *blocks = csize - (offset & (csize - 1));
 
     if (err < 0)
         return NULL;
 
     /* now locked ... */
 
     if (bitmap->bp[page].hijacked) { /* hijacked pointer */
         /* should we use the first or second counter field
          * of the hijacked pointer? */
         int hi = (pageoff > PAGE_COUNTER_MASK);
         return  &((bitmap_counter_t *)
               &bitmap->bp[page].map)[hi];
     } else /* page is allocated */
         return (bitmap_counter_t *)
             &(bitmap->bp[page].map[pageoff]);
 }
 
 int md_bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, int behind)
 {
     if (!bitmap)
         return 0;
 
     if (behind) {
         int bw;
         atomic_inc(&bitmap->behind_writes);
         bw = atomic_read(&bitmap->behind_writes);
         if (bw > bitmap->behind_writes_used)
             bitmap->behind_writes_used = bw;
 
         pr_debug("inc write-behind count %d/%lu\n",
              bw, bitmap->mddev->bitmap_info.max_write_behind);
     }
 
     while (sectors) {
         sector_t blocks;
         bitmap_counter_t *bmc;
 
         spin_lock_irq(&bitmap->counts.lock);
         bmc = md_bitmap_get_counter(&bitmap->counts, offset, &blocks, 1);
         if (!bmc) {
             spin_unlock_irq(&bitmap->counts.lock);
             return 0;
         }
 
         if (unlikely(COUNTER(*bmc) == COUNTER_MAX)) {
             DEFINE_WAIT(__wait);
             /* note that it is safe to do the prepare_to_wait
              * after the test as long as we do it before dropping
              * the spinlock.
              */
             prepare_to_wait(&bitmap->overflow_wait, &__wait,
                     TASK_UNINTERRUPTIBLE);
             spin_unlock_irq(&bitmap->counts.lock);
             schedule();
             finish_wait(&bitmap->overflow_wait, &__wait);
             continue;
         }
 
         switch (*bmc) {
         case 0:
             md_bitmap_file_set_bit(bitmap, offset);
             md_bitmap_count_page(&bitmap->counts, offset, 1);
             fallthrough;
         case 1:
             *bmc = 2;
         }
 
         (*bmc)++;
 
         spin_unlock_irq(&bitmap->counts.lock);
 
         offset += blocks;
         if (sectors > blocks)
             sectors -= blocks;
         else
             sectors = 0;
     }
     return 0;
 }
 EXPORT_SYMBOL(md_bitmap_startwrite);
 
 void md_bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
             unsigned long sectors, int success, int behind)
 {
     if (!bitmap)
         return;
     if (behind) {
         if (atomic_dec_and_test(&bitmap->behind_writes))
             wake_up(&bitmap->behind_wait);
         pr_debug("dec write-behind count %d/%lu\n",
              atomic_read(&bitmap->behind_writes),
              bitmap->mddev->bitmap_info.max_write_behind);
     }
 
     while (sectors) {
         sector_t blocks;
         unsigned long flags;
         bitmap_counter_t *bmc;
 
         spin_lock_irqsave(&bitmap->counts.lock, flags);
         bmc = md_bitmap_get_counter(&bitmap->counts, offset, &blocks, 0);
         if (!bmc) {
             spin_unlock_irqrestore(&bitmap->counts.lock, flags);
             return;
         }
 
         if (success && !bitmap->mddev->degraded &&
             bitmap->events_cleared < bitmap->mddev->events) {
             bitmap->events_cleared = bitmap->mddev->events;
             bitmap->need_sync = 1;
             sysfs_notify_dirent_safe(bitmap->sysfs_can_clear);
         }
 
         if (!success && !NEEDED(*bmc))
             *bmc |= NEEDED_MASK;
 
         if (COUNTER(*bmc) == COUNTER_MAX)
             wake_up(&bitmap->overflow_wait);
 
         (*bmc)--;
         if (*bmc <= 2) {
             md_bitmap_set_pending(&bitmap->counts, offset);
             bitmap->allclean = 0;
         }
         spin_unlock_irqrestore(&bitmap->counts.lock, flags);
         offset += blocks;
         if (sectors > blocks)
             sectors -= blocks;
         else
             sectors = 0;
     }
 }
 EXPORT_SYMBOL(md_bitmap_endwrite);
 
 static int __bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks,
                    int degraded)
 {
     bitmap_counter_t *bmc;
     int rv;
     if (bitmap == NULL) {/* FIXME or bitmap set as 'failed' */
         *blocks = 1024;
         return 1; /* always resync if no bitmap */
     }
     spin_lock_irq(&bitmap->counts.lock);
     bmc = md_bitmap_get_counter(&bitmap->counts, offset, blocks, 0);
     rv = 0;
     if (bmc) {
         /* locked */
         if (RESYNC(*bmc))
             rv = 1;
         else if (NEEDED(*bmc)) {
             rv = 1;
             if (!degraded) { /* don't set/clear bits if degraded */
                 *bmc |= RESYNC_MASK;
                 *bmc &= ~NEEDED_MASK;
             }
         }
     }
     spin_unlock_irq(&bitmap->counts.lock);
     return rv;
 }
 
 int md_bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks,
              int degraded)
 {
     /* bitmap_start_sync must always report on multiples of whole
      * pages, otherwise resync (which is very PAGE_SIZE based) will
      * get confused.
      * So call __bitmap_start_sync repeatedly (if needed) until
      * At least PAGE_SIZE>>9 blocks are covered.
      * Return the 'or' of the result.
      */
     int rv = 0;
     sector_t blocks1;
 
     *blocks = 0;
     while (*blocks < (PAGE_SIZE>>9)) {
         rv |= __bitmap_start_sync(bitmap, offset,
                       &blocks1, degraded);
         offset += blocks1;
         *blocks += blocks1;
     }
     return rv;
 }
 EXPORT_SYMBOL(md_bitmap_start_sync);
 
 void md_bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted)
 {
     bitmap_counter_t *bmc;
     unsigned long flags;
 
     if (bitmap == NULL) {
         *blocks = 1024;
         return;
     }
     spin_lock_irqsave(&bitmap->counts.lock, flags);
     bmc = md_bitmap_get_counter(&bitmap->counts, offset, blocks, 0);
     if (bmc == NULL)
         goto unlock;
     /* locked */
     if (RESYNC(*bmc)) {
         *bmc &= ~RESYNC_MASK;
 
         if (!NEEDED(*bmc) && aborted)
             *bmc |= NEEDED_MASK;
         else {
             if (*bmc <= 2) {
                 md_bitmap_set_pending(&bitmap->counts, offset);
                 bitmap->allclean = 0;
             }
         }
     }
  unlock:
     spin_unlock_irqrestore(&bitmap->counts.lock, flags);
 }
 EXPORT_SYMBOL(md_bitmap_end_sync);
 
 void md_bitmap_close_sync(struct bitmap *bitmap)
 {
     /* Sync has finished, and any bitmap chunks that weren't synced
      * properly have been aborted.  It remains to us to clear the
      * RESYNC bit wherever it is still on
      */
     sector_t sector = 0;
     sector_t blocks;
     if (!bitmap)
         return;
     while (sector < bitmap->mddev->resync_max_sectors) {
         md_bitmap_end_sync(bitmap, sector, &blocks, 0);
         sector += blocks;
     }
 }
 EXPORT_SYMBOL(md_bitmap_close_sync);
 
 void md_bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector, bool force)
 {
     sector_t s = 0;
     sector_t blocks;
 
     if (!bitmap)
         return;
     if (sector == 0) {
         bitmap->last_end_sync = jiffies;
         return;
     }
     if (!force && time_before(jiffies, (bitmap->last_end_sync
                   + bitmap->mddev->bitmap_info.daemon_sleep)))
         return;
     wait_event(bitmap->mddev->recovery_wait,
            atomic_read(&bitmap->mddev->recovery_active) == 0);
 
     bitmap->mddev->curr_resync_completed = sector;
     set_bit(MD_SB_CHANGE_CLEAN, &bitmap->mddev->sb_flags);
     sector &= ~((1ULL << bitmap->counts.chunkshift) - 1);
     s = 0;
     while (s < sector && s < bitmap->mddev->resync_max_sectors) {
         md_bitmap_end_sync(bitmap, s, &blocks, 0);
         s += blocks;
     }
     bitmap->last_end_sync = jiffies;
     sysfs_notify_dirent_safe(bitmap->mddev->sysfs_completed);
 }
 EXPORT_SYMBOL(md_bitmap_cond_end_sync);
 
 void md_bitmap_sync_with_cluster(struct mddev *mddev,
                   sector_t old_lo, sector_t old_hi,
                   sector_t new_lo, sector_t new_hi)
 {
     struct bitmap *bitmap = mddev->bitmap;
     sector_t sector, blocks = 0;
 
     for (sector = old_lo; sector < new_lo; ) {
         md_bitmap_end_sync(bitmap, sector, &blocks, 0);
         sector += blocks;
     }
     WARN((blocks > new_lo) && old_lo, "alignment is not correct for lo\n");
 
     for (sector = old_hi; sector < new_hi; ) {
         md_bitmap_start_sync(bitmap, sector, &blocks, 0);
         sector += blocks;
     }
     WARN((blocks > new_hi) && old_hi, "alignment is not correct for hi\n");
 }
 EXPORT_SYMBOL(md_bitmap_sync_with_cluster);
 
 static void md_bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed)
 {
     /* For each chunk covered by any of these sectors, set the
      * counter to 2 and possibly set resync_needed.  They should all
      * be 0 at this point
      */
 
     sector_t secs;
     bitmap_counter_t *bmc;
     spin_lock_irq(&bitmap->counts.lock);
     bmc = md_bitmap_get_counter(&bitmap->counts, offset, &secs, 1);
     if (!bmc) {
         spin_unlock_irq(&bitmap->counts.lock);
         return;
     }
     if (!*bmc) {
         *bmc = 2;
         md_bitmap_count_page(&bitmap->counts, offset, 1);
         md_bitmap_set_pending(&bitmap->counts, offset);
         bitmap->allclean = 0;
     }
     if (needed)
         *bmc |= NEEDED_MASK;
     spin_unlock_irq(&bitmap->counts.lock);
 }
 
 /* dirty the memory and file bits for bitmap chunks "s" to "e" */
 void md_bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e)
 {
     unsigned long chunk;
 
     for (chunk = s; chunk <= e; chunk++) {
         sector_t sec = (sector_t)chunk << bitmap->counts.chunkshift;
         md_bitmap_set_memory_bits(bitmap, sec, 1);
         md_bitmap_file_set_bit(bitmap, sec);
         if (sec < bitmap->mddev->recovery_cp)
             /* We are asserting that the array is dirty,
              * so move the recovery_cp address back so
              * that it is obvious that it is dirty
              */
             bitmap->mddev->recovery_cp = sec;
     }
 }
 
 /*
  * flush out any pending updates
  */
 void md_bitmap_flush(struct mddev *mddev)
 {
     struct bitmap *bitmap = mddev->bitmap;
     long sleep;
 
     if (!bitmap) /* there was no bitmap */
         return;
 
     /* run the daemon_work three time to ensure everything is flushed
      * that can be
      */
     sleep = mddev->bitmap_info.daemon_sleep * 2;
     bitmap->daemon_lastrun -= sleep;
     md_bitmap_daemon_work(mddev);
     bitmap->daemon_lastrun -= sleep;
     md_bitmap_daemon_work(mddev);
     bitmap->daemon_lastrun -= sleep;
     md_bitmap_daemon_work(mddev);
     if (mddev->bitmap_info.external)
         md_super_wait(mddev);
     md_bitmap_update_sb(bitmap);
 }
 
 /*
  * free memory that was allocated
  */
 void md_bitmap_free(struct bitmap *bitmap)
 {
     unsigned long k, pages;
     struct bitmap_page *bp;
 
     if (!bitmap) /* there was no bitmap */
         return;
 
     if (bitmap->sysfs_can_clear)
         sysfs_put(bitmap->sysfs_can_clear);
 
     if (mddev_is_clustered(bitmap->mddev) && bitmap->mddev->cluster_info &&
         bitmap->cluster_slot == md_cluster_ops->slot_number(bitmap->mddev))
         md_cluster_stop(bitmap->mddev);
 
     /* Shouldn't be needed - but just in case.... */
     wait_event(bitmap->write_wait,
            atomic_read(&bitmap->pending_writes) == 0);
 
     /* release the bitmap file  */
     md_bitmap_file_unmap(&bitmap->storage);
 
     bp = bitmap->counts.bp;
     pages = bitmap->counts.pages;
 
     /* free all allocated memory */
 
     if (bp) /* deallocate the page memory */
         for (k = 0; k < pages; k++)
             if (bp[k].map && !bp[k].hijacked)
                 kfree(bp[k].map);
     kfree(bp);
     kfree(bitmap);
 }
 EXPORT_SYMBOL(md_bitmap_free);
 
 void md_bitmap_wait_behind_writes(struct mddev *mddev)
 {
     struct bitmap *bitmap = mddev->bitmap;
 
     /* wait for behind writes to complete */
     if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
         pr_debug("md:%s: behind writes in progress - waiting to stop.\n",
              mdname(mddev));
         /* need to kick something here to make sure I/O goes? */
         wait_event(bitmap->behind_wait,
                atomic_read(&bitmap->behind_writes) == 0);
     }
 }
 
 void md_bitmap_destroy(struct mddev *mddev)
 {
     struct bitmap *bitmap = mddev->bitmap;
 
     if (!bitmap) /* there was no bitmap */
         return;
 
     md_bitmap_wait_behind_writes(mddev);
     if (!mddev->serialize_policy)
         mddev_destroy_serial_pool(mddev, NULL, true);
 
     mutex_lock(&mddev->bitmap_info.mutex);
     spin_lock(&mddev->lock);
     mddev->bitmap = NULL; /* disconnect from the md device */
     spin_unlock(&mddev->lock);
     mutex_unlock(&mddev->bitmap_info.mutex);
     if (mddev->thread)
         mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
 
     md_bitmap_free(bitmap);
 }
 
 /*
  * initialize the bitmap structure
  * if this returns an error, bitmap_destroy must be called to do clean up
  * once mddev->bitmap is set
  */
 struct bitmap *md_bitmap_create(struct mddev *mddev, int slot)
 {
     struct bitmap *bitmap;
     sector_t blocks = mddev->resync_max_sectors;
     struct file *file = mddev->bitmap_info.file;
     int err;
     struct kernfs_node *bm = NULL;
 
     BUILD_BUG_ON(sizeof(bitmap_super_t) != 256);
 
     BUG_ON(file && mddev->bitmap_info.offset);
 
     if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
         pr_notice("md/raid:%s: array with journal cannot have bitmap\n",
               mdname(mddev));
         return ERR_PTR(-EBUSY);
     }
 
     bitmap = kzalloc(sizeof(*bitmap), GFP_KERNEL);
     if (!bitmap)
         return ERR_PTR(-ENOMEM);
 
     spin_lock_init(&bitmap->counts.lock);
     atomic_set(&bitmap->pending_writes, 0);
     init_waitqueue_head(&bitmap->write_wait);
     init_waitqueue_head(&bitmap->overflow_wait);
     init_waitqueue_head(&bitmap->behind_wait);
 
     bitmap->mddev = mddev;
     bitmap->cluster_slot = slot;
 
     if (mddev->kobj.sd)
         bm = sysfs_get_dirent(mddev->kobj.sd, "bitmap");
     if (bm) {
         bitmap->sysfs_can_clear = sysfs_get_dirent(bm, "can_clear");
         sysfs_put(bm);
     } else
         bitmap->sysfs_can_clear = NULL;
 
     bitmap->storage.file = file;
     if (file) {
         get_file(file);
         /* As future accesses to this file will use bmap,
          * and bypass the page cache, we must sync the file
          * first.
          */
         vfs_fsync(file, 1);
     }
     /* read superblock from bitmap file (this sets mddev->bitmap_info.chunksize) */
     if (!mddev->bitmap_info.external) {
         /*
          * If 'MD_ARRAY_FIRST_USE' is set, then device-mapper is
          * instructing us to create a new on-disk bitmap instance.
          */
         if (test_and_clear_bit(MD_ARRAY_FIRST_USE, &mddev->flags))
             err = md_bitmap_new_disk_sb(bitmap);
         else
             err = md_bitmap_read_sb(bitmap);
     } else {
         err = 0;
         if (mddev->bitmap_info.chunksize == 0 ||
             mddev->bitmap_info.daemon_sleep == 0)
             /* chunksize and time_base need to be
              * set first. */
             err = -EINVAL;
     }
     if (err)
         goto error;
 
     bitmap->daemon_lastrun = jiffies;
     err = md_bitmap_resize(bitmap, blocks, mddev->bitmap_info.chunksize, 1);
     if (err)
         goto error;
 
     pr_debug("created bitmap (%lu pages) for device %s\n",
          bitmap->counts.pages, bmname(bitmap));
 
     err = test_bit(BITMAP_WRITE_ERROR, &bitmap->flags) ? -EIO : 0;
     if (err)
         goto error;
 
     return bitmap;
  error:
     md_bitmap_free(bitmap);
     return ERR_PTR(err);
 }
 
 int md_bitmap_load(struct mddev *mddev)
 {
     int err = 0;
     sector_t start = 0;
     sector_t sector = 0;
     struct bitmap *bitmap = mddev->bitmap;
     struct md_rdev *rdev;
 
     if (!bitmap)
         goto out;
 
     rdev_for_each(rdev, mddev)
         mddev_create_serial_pool(mddev, rdev, true);
 
     if (mddev_is_clustered(mddev))
         md_cluster_ops->load_bitmaps(mddev, mddev->bitmap_info.nodes);
 
     /* Clear out old bitmap info first:  Either there is none, or we
      * are resuming after someone else has possibly changed things,
      * so we should forget old cached info.
      * All chunks should be clean, but some might need_sync.
      */
     while (sector < mddev->resync_max_sectors) {
         sector_t blocks;
         md_bitmap_start_sync(bitmap, sector, &blocks, 0);
         sector += blocks;
     }
     md_bitmap_close_sync(bitmap);
 
     if (mddev->degraded == 0
         || bitmap->events_cleared == mddev->events)
         /* no need to keep dirty bits to optimise a
          * re-add of a missing device */
         start = mddev->recovery_cp;
 
     mutex_lock(&mddev->bitmap_info.mutex);
     err = md_bitmap_init_from_disk(bitmap, start);
     mutex_unlock(&mddev->bitmap_info.mutex);
 
     if (err)
         goto out;
     clear_bit(BITMAP_STALE, &bitmap->flags);
 
     /* Kick recovery in case any bits were set */
     set_bit(MD_RECOVERY_NEEDED, &bitmap->mddev->recovery);
 
     mddev->thread->timeout = mddev->bitmap_info.daemon_sleep;
     md_wakeup_thread(mddev->thread);
 
     md_bitmap_update_sb(bitmap);
 
     if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
         err = -EIO;
 out:
     return err;
 }
 EXPORT_SYMBOL_GPL(md_bitmap_load);
 
 /* caller need to free returned bitmap with md_bitmap_free() */
 struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot)
 {
     int rv = 0;
     struct bitmap *bitmap;
 
     bitmap = md_bitmap_create(mddev, slot);
     if (IS_ERR(bitmap)) {
         rv = PTR_ERR(bitmap);
         return ERR_PTR(rv);
     }
 
     rv = md_bitmap_init_from_disk(bitmap, 0);
     if (rv) {
         md_bitmap_free(bitmap);
         return ERR_PTR(rv);
     }
 
     return bitmap;
 }
 EXPORT_SYMBOL(get_bitmap_from_slot);
 
 /* Loads the bitmap associated with slot and copies the resync information
  * to our bitmap
  */
 int md_bitmap_copy_from_slot(struct mddev *mddev, int slot,
         sector_t *low, sector_t *high, bool clear_bits)
 {
     int rv = 0, i, j;
     sector_t block, lo = 0, hi = 0;
     struct bitmap_counts *counts;
     struct bitmap *bitmap;
 
     bitmap = get_bitmap_from_slot(mddev, slot);
     if (IS_ERR(bitmap)) {
         pr_err("%s can't get bitmap from slot %d\n", __func__, slot);
         return -1;
     }
 
     counts = &bitmap->counts;
     for (j = 0; j < counts->chunks; j++) {
         block = (sector_t)j << counts->chunkshift;
         if (md_bitmap_file_test_bit(bitmap, block)) {
             if (!lo)
                 lo = block;
             hi = block;
             md_bitmap_file_clear_bit(bitmap, block);
             md_bitmap_set_memory_bits(mddev->bitmap, block, 1);
             md_bitmap_file_set_bit(mddev->bitmap, block);
         }
     }
 
     if (clear_bits) {
         md_bitmap_update_sb(bitmap);
         /* BITMAP_PAGE_PENDING is set, but bitmap_unplug needs
          * BITMAP_PAGE_DIRTY or _NEEDWRITE to write ... */
         for (i = 0; i < bitmap->storage.file_pages; i++)
             if (test_page_attr(bitmap, i, BITMAP_PAGE_PENDING))
                 set_page_attr(bitmap, i, BITMAP_PAGE_NEEDWRITE);
         md_bitmap_unplug(bitmap);
     }
     md_bitmap_unplug(mddev->bitmap);
     *low = lo;
     *high = hi;
     md_bitmap_free(bitmap);
 
     return rv;
 }
 EXPORT_SYMBOL_GPL(md_bitmap_copy_from_slot);
 
 
 void md_bitmap_status(struct seq_file *seq, struct bitmap *bitmap)
 {
     unsigned long chunk_kb;
     struct bitmap_counts *counts;
 
     if (!bitmap)
         return;
 
     counts = &bitmap->counts;
 
     chunk_kb = bitmap->mddev->bitmap_info.chunksize >> 10;
     seq_printf(seq, "bitmap: %lu/%lu pages [%luKB], "
            "%lu%s chunk",
            counts->pages - counts->missing_pages,
            counts->pages,
            (counts->pages - counts->missing_pages)
            << (PAGE_SHIFT - 10),
            chunk_kb ? chunk_kb : bitmap->mddev->bitmap_info.chunksize,
            chunk_kb ? "KB" : "B");
     if (bitmap->storage.file) {
         seq_printf(seq, ", file: ");
         seq_file_path(seq, bitmap->storage.file, " \t\n");
     }
 
     seq_printf(seq, "\n");
 }
 
 int md_bitmap_resize(struct bitmap *bitmap, sector_t blocks,
           int chunksize, int init)
 {
     /* If chunk_size is 0, choose an appropriate chunk size.
      * Then possibly allocate new storage space.
      * Then quiesce, copy bits, replace bitmap, and re-start
      *
      * This function is called both to set up the initial bitmap
      * and to resize the bitmap while the array is active.
      * If this happens as a result of the array being resized,
      * chunksize will be zero, and we need to choose a suitable
      * chunksize, otherwise we use what we are given.
      */
     struct bitmap_storage store;
     struct bitmap_counts old_counts;
     unsigned long chunks;
     sector_t block;
     sector_t old_blocks, new_blocks;
     int chunkshift;
     int ret = 0;
     long pages;
     struct bitmap_page *new_bp;
 
     if (bitmap->storage.file && !init) {
         pr_info("md: cannot resize file-based bitmap\n");
         return -EINVAL;
     }
 
     if (chunksize == 0) {
         /* If there is enough space, leave the chunk size unchanged,
          * else increase by factor of two until there is enough space.
          */
         long bytes;
         long space = bitmap->mddev->bitmap_info.space;
 
         if (space == 0) {
             /* We don't know how much space there is, so limit
              * to current size - in sectors.
              */
             bytes = DIV_ROUND_UP(bitmap->counts.chunks, 8);
             if (!bitmap->mddev->bitmap_info.external)
                 bytes += sizeof(bitmap_super_t);
             space = DIV_ROUND_UP(bytes, 512);
             bitmap->mddev->bitmap_info.space = space;
         }
         chunkshift = bitmap->counts.chunkshift;
         chunkshift--;
         do {
             /* 'chunkshift' is shift from block size to chunk size */
             chunkshift++;
             chunks = DIV_ROUND_UP_SECTOR_T(blocks, 1 << chunkshift);
             bytes = DIV_ROUND_UP(chunks, 8);
             if (!bitmap->mddev->bitmap_info.external)
                 bytes += sizeof(bitmap_super_t);
         } while (bytes > (space << 9));
     } else
         chunkshift = ffz(~chunksize) - BITMAP_BLOCK_SHIFT;
 
     chunks = DIV_ROUND_UP_SECTOR_T(blocks, 1 << chunkshift);
     memset(&store, 0, sizeof(store));
     if (bitmap->mddev->bitmap_info.offset || bitmap->mddev->bitmap_info.file)
         ret = md_bitmap_storage_alloc(&store, chunks,
                           !bitmap->mddev->bitmap_info.external,
                           mddev_is_clustered(bitmap->mddev)
                           ? bitmap->cluster_slot : 0);
     if (ret) {
         md_bitmap_file_unmap(&store);
         goto err;
     }
 
     pages = DIV_ROUND_UP(chunks, PAGE_COUNTER_RATIO);
 
     new_bp = kcalloc(pages, sizeof(*new_bp), GFP_KERNEL);
     ret = -ENOMEM;
     if (!new_bp) {
         md_bitmap_file_unmap(&store);
         goto err;
     }
 
     if (!init)
         bitmap->mddev->pers->quiesce(bitmap->mddev, 1);
 
     store.file = bitmap->storage.file;
     bitmap->storage.file = NULL;
 
     if (store.sb_page && bitmap->storage.sb_page)
         memcpy(page_address(store.sb_page),
                page_address(bitmap->storage.sb_page),
                sizeof(bitmap_super_t));
     spin_lock_irq(&bitmap->counts.lock);
     md_bitmap_file_unmap(&bitmap->storage);
     bitmap->storage = store;
 
     old_counts = bitmap->counts;
     bitmap->counts.bp = new_bp;
     bitmap->counts.pages = pages;
     bitmap->counts.missing_pages = pages;
     bitmap->counts.chunkshift = chunkshift;
     bitmap->counts.chunks = chunks;
     bitmap->mddev->bitmap_info.chunksize = 1 << (chunkshift +
                              BITMAP_BLOCK_SHIFT);
 
     blocks = min(old_counts.chunks << old_counts.chunkshift,
              chunks << chunkshift);
 
     /* For cluster raid, need to pre-allocate bitmap */
     if (mddev_is_clustered(bitmap->mddev)) {
         unsigned long page;
         for (page = 0; page < pages; page++) {
             ret = md_bitmap_checkpage(&bitmap->counts, page, 1, 1);
             if (ret) {
                 unsigned long k;
 
                 /* deallocate the page memory */
                 for (k = 0; k < page; k++) {
                     kfree(new_bp[k].map);
                 }
                 kfree(new_bp);
 
                 /* restore some fields from old_counts */
                 bitmap->counts.bp = old_counts.bp;
                 bitmap->counts.pages = old_counts.pages;
                 bitmap->counts.missing_pages = old_counts.pages;
                 bitmap->counts.chunkshift = old_counts.chunkshift;
                 bitmap->counts.chunks = old_counts.chunks;
                 bitmap->mddev->bitmap_info.chunksize = 1 << (old_counts.chunkshift +
                                          BITMAP_BLOCK_SHIFT);
                 blocks = old_counts.chunks << old_counts.chunkshift;
                 pr_warn("Could not pre-allocate in-memory bitmap for cluster raid\n");
                 break;
             } else
                 bitmap->counts.bp[page].count += 1;
         }
     }
 
     for (block = 0; block < blocks; ) {
         bitmap_counter_t *bmc_old, *bmc_new;
         int set;
 
         bmc_old = md_bitmap_get_counter(&old_counts, block, &old_blocks, 0);
         set = bmc_old && NEEDED(*bmc_old);
 
         if (set) {
             bmc_new = md_bitmap_get_counter(&bitmap->counts, block, &new_blocks, 1);
             if (*bmc_new == 0) {
                 /* need to set on-disk bits too. */
                 sector_t end = block + new_blocks;
                 sector_t start = block >> chunkshift;
                 start <<= chunkshift;
                 while (start < end) {
                     md_bitmap_file_set_bit(bitmap, block);
                     start += 1 << chunkshift;
                 }
                 *bmc_new = 2;
                 md_bitmap_count_page(&bitmap->counts, block, 1);
                 md_bitmap_set_pending(&bitmap->counts, block);
             }
             *bmc_new |= NEEDED_MASK;
             if (new_blocks < old_blocks)
                 old_blocks = new_blocks;
         }
         block += old_blocks;
     }
 
     if (bitmap->counts.bp != old_counts.bp) {
         unsigned long k;
         for (k = 0; k < old_counts.pages; k++)
             if (!old_counts.bp[k].hijacked)
                 kfree(old_counts.bp[k].map);
         kfree(old_counts.bp);
     }
 
     if (!init) {
         int i;
         while (block < (chunks << chunkshift)) {
             bitmap_counter_t *bmc;
             bmc = md_bitmap_get_counter(&bitmap->counts, block, &new_blocks, 1);
             if (bmc) {
                 /* new space.  It needs to be resynced, so
                  * we set NEEDED_MASK.
                  */
                 if (*bmc == 0) {
                     *bmc = NEEDED_MASK | 2;
                     md_bitmap_count_page(&bitmap->counts, block, 1);
                     md_bitmap_set_pending(&bitmap->counts, block);
                 }
             }
             block += new_blocks;
         }
         for (i = 0; i < bitmap->storage.file_pages; i++)
             set_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
     }
     spin_unlock_irq(&bitmap->counts.lock);
 
     if (!init) {
         md_bitmap_unplug(bitmap);
         bitmap->mddev->pers->quiesce(bitmap->mddev, 0);
     }
     ret = 0;
 err:
     return ret;
 }
 EXPORT_SYMBOL_GPL(md_bitmap_resize);
 
 static ssize_t
 location_show(struct mddev *mddev, char *page)
 {
     ssize_t len;
     if (mddev->bitmap_info.file)
         len = sprintf(page, "file");
     else if (mddev->bitmap_info.offset)
         len = sprintf(page, "%+lld", (long long)mddev->bitmap_info.offset);
     else
         len = sprintf(page, "none");
     len += sprintf(page+len, "\n");
     return len;
 }
 
 static ssize_t
 location_store(struct mddev *mddev, const char *buf, size_t len)
 {
     int rv;
 
     rv = mddev_lock(mddev);
     if (rv)
         return rv;
     if (mddev->pers) {
         if (!mddev->pers->quiesce) {
             rv = -EBUSY;
             goto out;
         }
         if (mddev->recovery || mddev->sync_thread) {
             rv = -EBUSY;
             goto out;
         }
     }
 
     if (mddev->bitmap || mddev->bitmap_info.file ||
         mddev->bitmap_info.offset) {
         /* bitmap already configured.  Only option is to clear it */
         if (strncmp(buf, "none", 4) != 0) {
             rv = -EBUSY;
             goto out;
         }
         if (mddev->pers) {
             mddev_suspend(mddev);
             md_bitmap_destroy(mddev);
             mddev_resume(mddev);
         }
         mddev->bitmap_info.offset = 0;
         if (mddev->bitmap_info.file) {
             struct file *f = mddev->bitmap_info.file;
             mddev->bitmap_info.file = NULL;
             fput(f);
         }
     } else {
         /* No bitmap, OK to set a location */
         long long offset;
         if (strncmp(buf, "none", 4) == 0)
             /* nothing to be done */;
         else if (strncmp(buf, "file:", 5) == 0) {
             /* Not supported yet */
             rv = -EINVAL;
             goto out;
         } else {
             if (buf[0] == '+')
                 rv = kstrtoll(buf+1, 10, &offset);
             else
                 rv = kstrtoll(buf, 10, &offset);
             if (rv)
                 goto out;
             if (offset == 0) {
                 rv = -EINVAL;
                 goto out;
             }
             if (mddev->bitmap_info.external == 0 &&
                 mddev->major_version == 0 &&
                 offset != mddev->bitmap_info.default_offset) {
                 rv = -EINVAL;
                 goto out;
             }
             mddev->bitmap_info.offset = offset;
             if (mddev->pers) {
                 struct bitmap *bitmap;
                 bitmap = md_bitmap_create(mddev, -1);
                 mddev_suspend(mddev);
                 if (IS_ERR(bitmap))
                     rv = PTR_ERR(bitmap);
                 else {
                     mddev->bitmap = bitmap;
                     rv = md_bitmap_load(mddev);
                     if (rv)
                         mddev->bitmap_info.offset = 0;
                 }
                 if (rv) {
                     md_bitmap_destroy(mddev);
                     mddev_resume(mddev);
                     goto out;
                 }
                 mddev_resume(mddev);
             }
         }
     }
     if (!mddev->external) {
         /* Ensure new bitmap info is stored in
          * metadata promptly.
          */
         set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
         md_wakeup_thread(mddev->thread);
     }
     rv = 0;
 out:
     mddev_unlock(mddev);
     if (rv)
         return rv;
     return len;
 }
 
 static struct md_sysfs_entry bitmap_location =
 __ATTR(location, S_IRUGO|S_IWUSR, location_show, location_store);
 
 /* 'bitmap/space' is the space available at 'location' for the
  * bitmap.  This allows the kernel to know when it is safe to
  * resize the bitmap to match a resized array.
  */
 static ssize_t
 space_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%lu\n", mddev->bitmap_info.space);
 }
 
 static ssize_t
 space_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned long sectors;
     int rv;
 
     rv = kstrtoul(buf, 10, &sectors);
     if (rv)
         return rv;
 
     if (sectors == 0)
         return -EINVAL;
 
     if (mddev->bitmap &&
         sectors < (mddev->bitmap->storage.bytes + 511) >> 9)
         return -EFBIG; /* Bitmap is too big for this small space */
 
     /* could make sure it isn't too big, but that isn't really
      * needed - user-space should be careful.
      */
     mddev->bitmap_info.space = sectors;
     return len;
 }
 
 static struct md_sysfs_entry bitmap_space =
 __ATTR(space, S_IRUGO|S_IWUSR, space_show, space_store);
 
 static ssize_t
 timeout_show(struct mddev *mddev, char *page)
 {
     ssize_t len;
     unsigned long secs = mddev->bitmap_info.daemon_sleep / HZ;
     unsigned long jifs = mddev->bitmap_info.daemon_sleep % HZ;
 
     len = sprintf(page, "%lu", secs);
     if (jifs)
         len += sprintf(page+len, ".%03u", jiffies_to_msecs(jifs));
     len += sprintf(page+len, "\n");
     return len;
 }
 
 static ssize_t
 timeout_store(struct mddev *mddev, const char *buf, size_t len)
 {
     /* timeout can be set at any time */
     unsigned long timeout;
     int rv = strict_strtoul_scaled(buf, &timeout, 4);
     if (rv)
         return rv;
 
     /* just to make sure we don't overflow... */
     if (timeout >= LONG_MAX / HZ)
         return -EINVAL;
 
     timeout = timeout * HZ / 10000;
 
     if (timeout >= MAX_SCHEDULE_TIMEOUT)
         timeout = MAX_SCHEDULE_TIMEOUT-1;
     if (timeout < 1)
         timeout = 1;
     mddev->bitmap_info.daemon_sleep = timeout;
     if (mddev->thread) {
         /* if thread->timeout is MAX_SCHEDULE_TIMEOUT, then
          * the bitmap is all clean and we don't need to
          * adjust the timeout right now
          */
         if (mddev->thread->timeout < MAX_SCHEDULE_TIMEOUT) {
             mddev->thread->timeout = timeout;
             md_wakeup_thread(mddev->thread);
         }
     }
     return len;
 }
 
 static struct md_sysfs_entry bitmap_timeout =
 __ATTR(time_base, S_IRUGO|S_IWUSR, timeout_show, timeout_store);
 
 static ssize_t
 backlog_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%lu\n", mddev->bitmap_info.max_write_behind);
 }
 
 static ssize_t
 backlog_store(struct mddev *mddev, const char *buf, size_t len)
 {
     unsigned long backlog;
     unsigned long old_mwb = mddev->bitmap_info.max_write_behind;
     struct md_rdev *rdev;
     bool has_write_mostly = false;
     int rv = kstrtoul(buf, 10, &backlog);
     if (rv)
         return rv;
     if (backlog > COUNTER_MAX)
         return -EINVAL;
 
     /*
      * Without write mostly device, it doesn't make sense to set
      * backlog for max_write_behind.
      */
     rdev_for_each(rdev, mddev) {
         if (test_bit(WriteMostly, &rdev->flags)) {
             has_write_mostly = true;
             break;
         }
     }
     if (!has_write_mostly) {
         pr_warn_ratelimited("%s: can't set backlog, no write mostly device available\n",
                     mdname(mddev));
         return -EINVAL;
     }
 
     mddev->bitmap_info.max_write_behind = backlog;
     if (!backlog && mddev->serial_info_pool) {
         /* serial_info_pool is not needed if backlog is zero */
         if (!mddev->serialize_policy)
             mddev_destroy_serial_pool(mddev, NULL, false);
     } else if (backlog && !mddev->serial_info_pool) {
         /* serial_info_pool is needed since backlog is not zero */
         struct md_rdev *rdev;
 
         rdev_for_each(rdev, mddev)
             mddev_create_serial_pool(mddev, rdev, false);
     }
     if (old_mwb != backlog)
         md_bitmap_update_sb(mddev->bitmap);
     return len;
 }
 
 static struct md_sysfs_entry bitmap_backlog =
 __ATTR(backlog, S_IRUGO|S_IWUSR, backlog_show, backlog_store);
 
 static ssize_t
 chunksize_show(struct mddev *mddev, char *page)
 {
     return sprintf(page, "%lu\n", mddev->bitmap_info.chunksize);
 }
 
 static ssize_t
 chunksize_store(struct mddev *mddev, const char *buf, size_t len)
 {
     /* Can only be changed when no bitmap is active */
     int rv;
     unsigned long csize;
     if (mddev->bitmap)
         return -EBUSY;
     rv = kstrtoul(buf, 10, &csize);
     if (rv)
         return rv;
     if (csize < 512 ||
         !is_power_of_2(csize))
         return -EINVAL;
     mddev->bitmap_info.chunksize = csize;
     return len;
 }
 
 static struct md_sysfs_entry bitmap_chunksize =
 __ATTR(chunksize, S_IRUGO|S_IWUSR, chunksize_show, chunksize_store);
 
 static ssize_t metadata_show(struct mddev *mddev, char *page)
 {
     if (mddev_is_clustered(mddev))
         return sprintf(page, "clustered\n");
     return sprintf(page, "%s\n", (mddev->bitmap_info.external
                       ? "external" : "internal"));
 }
 
 static ssize_t metadata_store(struct mddev *mddev, const char *buf, size_t len)
 {
     if (mddev->bitmap ||
         mddev->bitmap_info.file ||
         mddev->bitmap_info.offset)
         return -EBUSY;
     if (strncmp(buf, "external", 8) == 0)
         mddev->bitmap_info.external = 1;
     else if ((strncmp(buf, "internal", 8) == 0) ||
             (strncmp(buf, "clustered", 9) == 0))
         mddev->bitmap_info.external = 0;
     else
         return -EINVAL;
     return len;
 }
 
 static struct md_sysfs_entry bitmap_metadata =
 __ATTR(metadata, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
 
 static ssize_t can_clear_show(struct mddev *mddev, char *page)
 {
     int len;
     spin_lock(&mddev->lock);
     if (mddev->bitmap)
         len = sprintf(page, "%s\n", (mddev->bitmap->need_sync ?
                          "false" : "true"));
     else
         len = sprintf(page, "\n");
     spin_unlock(&mddev->lock);
     return len;
 }
 
 static ssize_t can_clear_store(struct mddev *mddev, const char *buf, size_t len)
 {
     if (mddev->bitmap == NULL)
         return -ENOENT;
     if (strncmp(buf, "false", 5) == 0)
         mddev->bitmap->need_sync = 1;
     else if (strncmp(buf, "true", 4) == 0) {
         if (mddev->degraded)
             return -EBUSY;
         mddev->bitmap->need_sync = 0;
     } else
         return -EINVAL;
     return len;
 }
 
 static struct md_sysfs_entry bitmap_can_clear =
 __ATTR(can_clear, S_IRUGO|S_IWUSR, can_clear_show, can_clear_store);
 
 static ssize_t
 behind_writes_used_show(struct mddev *mddev, char *page)
 {
     ssize_t ret;
     spin_lock(&mddev->lock);
     if (mddev->bitmap == NULL)
         ret = sprintf(page, "0\n");
     else
         ret = sprintf(page, "%lu\n",
                   mddev->bitmap->behind_writes_used);
     spin_unlock(&mddev->lock);
     return ret;
 }
 
 static ssize_t
 behind_writes_used_reset(struct mddev *mddev, const char *buf, size_t len)
 {
     if (mddev->bitmap)
         mddev->bitmap->behind_writes_used = 0;
     return len;
 }
 
 static struct md_sysfs_entry max_backlog_used =
 __ATTR(max_backlog_used, S_IRUGO | S_IWUSR,
        behind_writes_used_show, behind_writes_used_reset);
 
 static struct attribute *md_bitmap_attrs[] = {
     &bitmap_location.attr,
     &bitmap_space.attr,
     &bitmap_timeout.attr,
     &bitmap_backlog.attr,
     &bitmap_chunksize.attr,
     &bitmap_metadata.attr,
     &bitmap_can_clear.attr,
     &max_backlog_used.attr,
     NULL
 };
 const struct attribute_group md_bitmap_group = {
     .name = "bitmap",
     .attrs = md_bitmap_attrs,
 };