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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
 /*
  * Partial Parity Log for closing the RAID5 write hole
  * Copyright (c) 2017, Intel Corporation.
  */
 
 #include <linux/kernel.h>
 #include <linux/blkdev.h>
 #include <linux/slab.h>
 #include <linux/crc32c.h>
 #include <linux/async_tx.h>
 #include <linux/raid/md_p.h>
 #include "md.h"
 #include "raid5.h"
 #include "raid5-log.h"
 
 /*
  * PPL consists of a 4KB header (struct ppl_header) and at least 128KB for
  * partial parity data. The header contains an array of entries
  * (struct ppl_header_entry) which describe the logged write requests.
  * Partial parity for the entries comes after the header, written in the same
  * sequence as the entries:
  *
  * Header
  *   entry0
  *   ...
  *   entryN
  * PP data
  *   PP for entry0
  *   ...
  *   PP for entryN
  *
  * An entry describes one or more consecutive stripe_heads, up to a full
  * stripe. The modifed raid data chunks form an m-by-n matrix, where m is the
  * number of stripe_heads in the entry and n is the number of modified data
  * disks. Every stripe_head in the entry must write to the same data disks.
  * An example of a valid case described by a single entry (writes to the first
  * stripe of a 4 disk array, 16k chunk size):
  *
  * sh->sector   dd0   dd1   dd2    ppl
  *            +-----+-----+-----+
  * 0          | --- | --- | --- | +----+
  * 8          | -W- | -W- | --- | | pp |   data_sector = 8
  * 16         | -W- | -W- | --- | | pp |   data_size = 3 * 2 * 4k
  * 24         | -W- | -W- | --- | | pp |   pp_size = 3 * 4k
  *            +-----+-----+-----+ +----+
  *
  * data_sector is the first raid sector of the modified data, data_size is the
  * total size of modified data and pp_size is the size of partial parity for
  * this entry. Entries for full stripe writes contain no partial parity
  * (pp_size = 0), they only mark the stripes for which parity should be
  * recalculated after an unclean shutdown. Every entry holds a checksum of its
  * partial parity, the header also has a checksum of the header itself.
  *
  * A write request is always logged to the PPL instance stored on the parity
  * disk of the corresponding stripe. For each member disk there is one ppl_log
  * used to handle logging for this disk, independently from others. They are
  * grouped in child_logs array in struct ppl_conf, which is assigned to
  * r5conf->log_private.
  *
  * ppl_io_unit represents a full PPL write, header_page contains the ppl_header.
  * PPL entries for logged stripes are added in ppl_log_stripe(). A stripe_head
  * can be appended to the last entry if it meets the conditions for a valid
  * entry described above, otherwise a new entry is added. Checksums of entries
  * are calculated incrementally as stripes containing partial parity are being
  * added. ppl_submit_iounit() calculates the checksum of the header and submits
  * a bio containing the header page and partial parity pages (sh->ppl_page) for
  * all stripes of the io_unit. When the PPL write completes, the stripes
  * associated with the io_unit are released and raid5d starts writing their data
  * and parity. When all stripes are written, the io_unit is freed and the next
  * can be submitted.
  *
  * An io_unit is used to gather stripes until it is submitted or becomes full
  * (if the maximum number of entries or size of PPL is reached). Another io_unit
  * can't be submitted until the previous has completed (PPL and stripe
  * data+parity is written). The log->io_list tracks all io_units of a log
  * (for a single member disk). New io_units are added to the end of the list
  * and the first io_unit is submitted, if it is not submitted already.
  * The current io_unit accepting new stripes is always at the end of the list.
  *
  * If write-back cache is enabled for any of the disks in the array, its data
  * must be flushed before next io_unit is submitted.
  */
 
 #define PPL_SPACE_SIZE (128 * 1024)
 
 struct ppl_conf {
     struct mddev *mddev;
 
     /* array of child logs, one for each raid disk */
     struct ppl_log *child_logs;
     int count;
 
     int block_size;     /* the logical block size used for data_sector
                  * in ppl_header_entry */
     u32 signature;      /* raid array identifier */
     atomic64_t seq;     /* current log write sequence number */
 
     struct kmem_cache *io_kc;
     mempool_t io_pool;
     struct bio_set bs;
     struct bio_set flush_bs;
 
     /* used only for recovery */
     int recovered_entries;
     int mismatch_count;
 
     /* stripes to retry if failed to allocate io_unit */
     struct list_head no_mem_stripes;
     spinlock_t no_mem_stripes_lock;
 
     unsigned short write_hint;
 };
 
 struct ppl_log {
     struct ppl_conf *ppl_conf;  /* shared between all log instances */
 
     struct md_rdev *rdev;       /* array member disk associated with
                      * this log instance */
     struct mutex io_mutex;
     struct ppl_io_unit *current_io; /* current io_unit accepting new data
                      * always at the end of io_list */
     spinlock_t io_list_lock;
     struct list_head io_list;   /* all io_units of this log */
 
     sector_t next_io_sector;
     unsigned int entry_space;
     bool use_multippl;
     bool wb_cache_on;
     unsigned long disk_flush_bitmap;
 };
 
 #define PPL_IO_INLINE_BVECS 32
 
 struct ppl_io_unit {
     struct ppl_log *log;
 
     struct page *header_page;   /* for ppl_header */
 
     unsigned int entries_count; /* number of entries in ppl_header */
     unsigned int pp_size;       /* total size current of partial parity */
 
     u64 seq;            /* sequence number of this log write */
     struct list_head log_sibling;   /* log->io_list */
 
     struct list_head stripe_list;   /* stripes added to the io_unit */
     atomic_t pending_stripes;   /* how many stripes not written to raid */
     atomic_t pending_flushes;   /* how many disk flushes are in progress */
 
     bool submitted;         /* true if write to log started */
 
     /* inline bio and its biovec for submitting the iounit */
     struct bio bio;
     struct bio_vec biovec[PPL_IO_INLINE_BVECS];
 };
 
 struct dma_async_tx_descriptor *
 ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
                struct dma_async_tx_descriptor *tx)
 {
     int disks = sh->disks;
     struct page **srcs = percpu->scribble;
     int count = 0, pd_idx = sh->pd_idx, i;
     struct async_submit_ctl submit;
 
     pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
 
     /*
      * Partial parity is the XOR of stripe data chunks that are not changed
      * during the write request. Depending on available data
      * (read-modify-write vs. reconstruct-write case) we calculate it
      * differently.
      */
     if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
         /*
          * rmw: xor old data and parity from updated disks
          * This is calculated earlier by ops_run_prexor5() so just copy
          * the parity dev page.
          */
         srcs[count++] = sh->dev[pd_idx].page;
     } else if (sh->reconstruct_state == reconstruct_state_drain_run) {
         /* rcw: xor data from all not updated disks */
         for (i = disks; i--;) {
             struct r5dev *dev = &sh->dev[i];
             if (test_bit(R5_UPTODATE, &dev->flags))
                 srcs[count++] = dev->page;
         }
     } else {
         return tx;
     }
 
     init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, tx,
               NULL, sh, (void *) (srcs + sh->disks + 2));
 
     if (count == 1)
         tx = async_memcpy(sh->ppl_page, srcs[0], 0, 0, PAGE_SIZE,
                   &submit);
     else
         tx = async_xor(sh->ppl_page, srcs, 0, count, PAGE_SIZE,
                    &submit);
 
     return tx;
 }
 
 static void *ppl_io_pool_alloc(gfp_t gfp_mask, void *pool_data)
 {
     struct kmem_cache *kc = pool_data;
     struct ppl_io_unit *io;
 
     io = kmem_cache_alloc(kc, gfp_mask);
     if (!io)
         return NULL;
 
     io->header_page = alloc_page(gfp_mask);
     if (!io->header_page) {
         kmem_cache_free(kc, io);
         return NULL;
     }
 
     return io;
 }
 
 static void ppl_io_pool_free(void *element, void *pool_data)
 {
     struct kmem_cache *kc = pool_data;
     struct ppl_io_unit *io = element;
 
     __free_page(io->header_page);
     kmem_cache_free(kc, io);
 }
 
 static struct ppl_io_unit *ppl_new_iounit(struct ppl_log *log,
                       struct stripe_head *sh)
 {
     struct ppl_conf *ppl_conf = log->ppl_conf;
     struct ppl_io_unit *io;
     struct ppl_header *pplhdr;
     struct page *header_page;
 
     io = mempool_alloc(&ppl_conf->io_pool, GFP_NOWAIT);
     if (!io)
         return NULL;
 
     header_page = io->header_page;
     memset(io, 0, sizeof(*io));
     io->header_page = header_page;
 
     io->log = log;
     INIT_LIST_HEAD(&io->log_sibling);
     INIT_LIST_HEAD(&io->stripe_list);
     atomic_set(&io->pending_stripes, 0);
     atomic_set(&io->pending_flushes, 0);
     bio_init(&io->bio, log->rdev->bdev, io->biovec, PPL_IO_INLINE_BVECS,
          REQ_OP_WRITE | REQ_FUA);
 
     pplhdr = page_address(io->header_page);
     clear_page(pplhdr);
     memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
     pplhdr->signature = cpu_to_le32(ppl_conf->signature);
 
     io->seq = atomic64_add_return(1, &ppl_conf->seq);
     pplhdr->generation = cpu_to_le64(io->seq);
 
     return io;
 }
 
 static int ppl_log_stripe(struct ppl_log *log, struct stripe_head *sh)
 {
     struct ppl_io_unit *io = log->current_io;
     struct ppl_header_entry *e = NULL;
     struct ppl_header *pplhdr;
     int i;
     sector_t data_sector = 0;
     int data_disks = 0;
     struct r5conf *conf = sh->raid_conf;
 
     pr_debug("%s: stripe: %llu\n", __func__, (unsigned long long)sh->sector);
 
     /* check if current io_unit is full */
     if (io && (io->pp_size == log->entry_space ||
            io->entries_count == PPL_HDR_MAX_ENTRIES)) {
         pr_debug("%s: add io_unit blocked by seq: %llu\n",
              __func__, io->seq);
         io = NULL;
     }
 
     /* add a new unit if there is none or the current is full */
     if (!io) {
         io = ppl_new_iounit(log, sh);
         if (!io)
             return -ENOMEM;
         spin_lock_irq(&log->io_list_lock);
         list_add_tail(&io->log_sibling, &log->io_list);
         spin_unlock_irq(&log->io_list_lock);
 
         log->current_io = io;
     }
 
     for (i = 0; i < sh->disks; i++) {
         struct r5dev *dev = &sh->dev[i];
 
         if (i != sh->pd_idx && test_bit(R5_Wantwrite, &dev->flags)) {
             if (!data_disks || dev->sector < data_sector)
                 data_sector = dev->sector;
             data_disks++;
         }
     }
     BUG_ON(!data_disks);
 
     pr_debug("%s: seq: %llu data_sector: %llu data_disks: %d\n", __func__,
          io->seq, (unsigned long long)data_sector, data_disks);
 
     pplhdr = page_address(io->header_page);
 
     if (io->entries_count > 0) {
         struct ppl_header_entry *last =
                 &pplhdr->entries[io->entries_count - 1];
         struct stripe_head *sh_last = list_last_entry(
                 &io->stripe_list, struct stripe_head, log_list);
         u64 data_sector_last = le64_to_cpu(last->data_sector);
         u32 data_size_last = le32_to_cpu(last->data_size);
 
         /*
          * Check if we can append the stripe to the last entry. It must
          * be just after the last logged stripe and write to the same
          * disks. Use bit shift and logarithm to avoid 64-bit division.
          */
         if ((sh->sector == sh_last->sector + RAID5_STRIPE_SECTORS(conf)) &&
             (data_sector >> ilog2(conf->chunk_sectors) ==
              data_sector_last >> ilog2(conf->chunk_sectors)) &&
             ((data_sector - data_sector_last) * data_disks ==
              data_size_last >> 9))
             e = last;
     }
 
     if (!e) {
         e = &pplhdr->entries[io->entries_count++];
         e->data_sector = cpu_to_le64(data_sector);
         e->parity_disk = cpu_to_le32(sh->pd_idx);
         e->checksum = cpu_to_le32(~0);
     }
 
     le32_add_cpu(&e->data_size, data_disks << PAGE_SHIFT);
 
     /* don't write any PP if full stripe write */
     if (!test_bit(STRIPE_FULL_WRITE, &sh->state)) {
         le32_add_cpu(&e->pp_size, PAGE_SIZE);
         io->pp_size += PAGE_SIZE;
         e->checksum = cpu_to_le32(crc32c_le(le32_to_cpu(e->checksum),
                             page_address(sh->ppl_page),
                             PAGE_SIZE));
     }
 
     list_add_tail(&sh->log_list, &io->stripe_list);
     atomic_inc(&io->pending_stripes);
     sh->ppl_io = io;
 
     return 0;
 }
 
 int ppl_write_stripe(struct r5conf *conf, struct stripe_head *sh)
 {
     struct ppl_conf *ppl_conf = conf->log_private;
     struct ppl_io_unit *io = sh->ppl_io;
     struct ppl_log *log;
 
     if (io || test_bit(STRIPE_SYNCING, &sh->state) || !sh->ppl_page ||
         !test_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags) ||
         !test_bit(R5_Insync, &sh->dev[sh->pd_idx].flags)) {
         clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
         return -EAGAIN;
     }
 
     log = &ppl_conf->child_logs[sh->pd_idx];
 
     mutex_lock(&log->io_mutex);
 
     if (!log->rdev || test_bit(Faulty, &log->rdev->flags)) {
         mutex_unlock(&log->io_mutex);
         return -EAGAIN;
     }
 
     set_bit(STRIPE_LOG_TRAPPED, &sh->state);
     clear_bit(STRIPE_DELAYED, &sh->state);
     atomic_inc(&sh->count);
 
     if (ppl_log_stripe(log, sh)) {
         spin_lock_irq(&ppl_conf->no_mem_stripes_lock);
         list_add_tail(&sh->log_list, &ppl_conf->no_mem_stripes);
         spin_unlock_irq(&ppl_conf->no_mem_stripes_lock);
     }
 
     mutex_unlock(&log->io_mutex);
 
     return 0;
 }
 
 static void ppl_log_endio(struct bio *bio)
 {
     struct ppl_io_unit *io = bio->bi_private;
     struct ppl_log *log = io->log;
     struct ppl_conf *ppl_conf = log->ppl_conf;
     struct stripe_head *sh, *next;
 
     pr_debug("%s: seq: %llu\n", __func__, io->seq);
 
     if (bio->bi_status)
         md_error(ppl_conf->mddev, log->rdev);
 
     list_for_each_entry_safe(sh, next, &io->stripe_list, log_list) {
         list_del_init(&sh->log_list);
 
         set_bit(STRIPE_HANDLE, &sh->state);
         raid5_release_stripe(sh);
     }
 }
 
 static void ppl_submit_iounit_bio(struct ppl_io_unit *io, struct bio *bio)
 {
     pr_debug("%s: seq: %llu size: %u sector: %llu dev: %pg\n",
          __func__, io->seq, bio->bi_iter.bi_size,
          (unsigned long long)bio->bi_iter.bi_sector,
          bio->bi_bdev);
 
     submit_bio(bio);
 }
 
 static void ppl_submit_iounit(struct ppl_io_unit *io)
 {
     struct ppl_log *log = io->log;
     struct ppl_conf *ppl_conf = log->ppl_conf;
     struct ppl_header *pplhdr = page_address(io->header_page);
     struct bio *bio = &io->bio;
     struct stripe_head *sh;
     int i;
 
     bio->bi_private = io;
 
     if (!log->rdev || test_bit(Faulty, &log->rdev->flags)) {
         ppl_log_endio(bio);
         return;
     }
 
     for (i = 0; i < io->entries_count; i++) {
         struct ppl_header_entry *e = &pplhdr->entries[i];
 
         pr_debug("%s: seq: %llu entry: %d data_sector: %llu pp_size: %u data_size: %u\n",
              __func__, io->seq, i, le64_to_cpu(e->data_sector),
              le32_to_cpu(e->pp_size), le32_to_cpu(e->data_size));
 
         e->data_sector = cpu_to_le64(le64_to_cpu(e->data_sector) >>
                          ilog2(ppl_conf->block_size >> 9));
         e->checksum = cpu_to_le32(~le32_to_cpu(e->checksum));
     }
 
     pplhdr->entries_count = cpu_to_le32(io->entries_count);
     pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PPL_HEADER_SIZE));
 
     /* Rewind the buffer if current PPL is larger then remaining space */
     if (log->use_multippl &&
         log->rdev->ppl.sector + log->rdev->ppl.size - log->next_io_sector <
         (PPL_HEADER_SIZE + io->pp_size) >> 9)
         log->next_io_sector = log->rdev->ppl.sector;
 
 
     bio->bi_end_io = ppl_log_endio;
     bio->bi_iter.bi_sector = log->next_io_sector;
     bio_add_page(bio, io->header_page, PAGE_SIZE, 0);
 
     pr_debug("%s: log->current_io_sector: %llu\n", __func__,
         (unsigned long long)log->next_io_sector);
 
     if (log->use_multippl)
         log->next_io_sector += (PPL_HEADER_SIZE + io->pp_size) >> 9;
 
     WARN_ON(log->disk_flush_bitmap != 0);
 
     list_for_each_entry(sh, &io->stripe_list, log_list) {
         for (i = 0; i < sh->disks; i++) {
             struct r5dev *dev = &sh->dev[i];
 
             if ((ppl_conf->child_logs[i].wb_cache_on) &&
                 (test_bit(R5_Wantwrite, &dev->flags))) {
                 set_bit(i, &log->disk_flush_bitmap);
             }
         }
 
         /* entries for full stripe writes have no partial parity */
         if (test_bit(STRIPE_FULL_WRITE, &sh->state))
             continue;
 
         if (!bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0)) {
             struct bio *prev = bio;
 
             bio = bio_alloc_bioset(prev->bi_bdev, BIO_MAX_VECS,
                            prev->bi_opf, GFP_NOIO,
                            &ppl_conf->bs);
             bio->bi_iter.bi_sector = bio_end_sector(prev);
             bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0);
 
             bio_chain(bio, prev);
             ppl_submit_iounit_bio(io, prev);
         }
     }
 
     ppl_submit_iounit_bio(io, bio);
 }
 
 static void ppl_submit_current_io(struct ppl_log *log)
 {
     struct ppl_io_unit *io;
 
     spin_lock_irq(&log->io_list_lock);
 
     io = list_first_entry_or_null(&log->io_list, struct ppl_io_unit,
                       log_sibling);
     if (io && io->submitted)
         io = NULL;
 
     spin_unlock_irq(&log->io_list_lock);
 
     if (io) {
         io->submitted = true;
 
         if (io == log->current_io)
             log->current_io = NULL;
 
         ppl_submit_iounit(io);
     }
 }
 
 void ppl_write_stripe_run(struct r5conf *conf)
 {
     struct ppl_conf *ppl_conf = conf->log_private;
     struct ppl_log *log;
     int i;
 
     for (i = 0; i < ppl_conf->count; i++) {
         log = &ppl_conf->child_logs[i];
 
         mutex_lock(&log->io_mutex);
         ppl_submit_current_io(log);
         mutex_unlock(&log->io_mutex);
     }
 }
 
 static void ppl_io_unit_finished(struct ppl_io_unit *io)
 {
     struct ppl_log *log = io->log;
     struct ppl_conf *ppl_conf = log->ppl_conf;
     struct r5conf *conf = ppl_conf->mddev->private;
     unsigned long flags;
 
     pr_debug("%s: seq: %llu\n", __func__, io->seq);
 
     local_irq_save(flags);
 
     spin_lock(&log->io_list_lock);
     list_del(&io->log_sibling);
     spin_unlock(&log->io_list_lock);
 
     mempool_free(io, &ppl_conf->io_pool);
 
     spin_lock(&ppl_conf->no_mem_stripes_lock);
     if (!list_empty(&ppl_conf->no_mem_stripes)) {
         struct stripe_head *sh;
 
         sh = list_first_entry(&ppl_conf->no_mem_stripes,
                       struct stripe_head, log_list);
         list_del_init(&sh->log_list);
         set_bit(STRIPE_HANDLE, &sh->state);
         raid5_release_stripe(sh);
     }
     spin_unlock(&ppl_conf->no_mem_stripes_lock);
 
     local_irq_restore(flags);
 
     wake_up(&conf->wait_for_quiescent);
 }
 
 static void ppl_flush_endio(struct bio *bio)
 {
     struct ppl_io_unit *io = bio->bi_private;
     struct ppl_log *log = io->log;
     struct ppl_conf *ppl_conf = log->ppl_conf;
     struct r5conf *conf = ppl_conf->mddev->private;
 
     pr_debug("%s: dev: %pg\n", __func__, bio->bi_bdev);
 
     if (bio->bi_status) {
         struct md_rdev *rdev;
 
         rcu_read_lock();
         rdev = md_find_rdev_rcu(conf->mddev, bio_dev(bio));
         if (rdev)
             md_error(rdev->mddev, rdev);
         rcu_read_unlock();
     }
 
     bio_put(bio);
 
     if (atomic_dec_and_test(&io->pending_flushes)) {
         ppl_io_unit_finished(io);
         md_wakeup_thread(conf->mddev->thread);
     }
 }
 
 static void ppl_do_flush(struct ppl_io_unit *io)
 {
     struct ppl_log *log = io->log;
     struct ppl_conf *ppl_conf = log->ppl_conf;
     struct r5conf *conf = ppl_conf->mddev->private;
     int raid_disks = conf->raid_disks;
     int flushed_disks = 0;
     int i;
 
     atomic_set(&io->pending_flushes, raid_disks);
 
     for_each_set_bit(i, &log->disk_flush_bitmap, raid_disks) {
         struct md_rdev *rdev;
         struct block_device *bdev = NULL;
 
         rcu_read_lock();
         rdev = rcu_dereference(conf->disks[i].rdev);
         if (rdev && !test_bit(Faulty, &rdev->flags))
             bdev = rdev->bdev;
         rcu_read_unlock();
 
         if (bdev) {
             struct bio *bio;
 
             bio = bio_alloc_bioset(bdev, 0,
                            REQ_OP_WRITE | REQ_PREFLUSH,
                            GFP_NOIO, &ppl_conf->flush_bs);
             bio->bi_private = io;
             bio->bi_end_io = ppl_flush_endio;
 
             pr_debug("%s: dev: %ps\n", __func__, bio->bi_bdev);
 
             submit_bio(bio);
             flushed_disks++;
         }
     }
 
     log->disk_flush_bitmap = 0;
 
     for (i = flushed_disks ; i < raid_disks; i++) {
         if (atomic_dec_and_test(&io->pending_flushes))
             ppl_io_unit_finished(io);
     }
 }
 
 static inline bool ppl_no_io_unit_submitted(struct r5conf *conf,
                         struct ppl_log *log)
 {
     struct ppl_io_unit *io;
 
     io = list_first_entry_or_null(&log->io_list, struct ppl_io_unit,
                       log_sibling);
 
     return !io || !io->submitted;
 }
 
 void ppl_quiesce(struct r5conf *conf, int quiesce)
 {
     struct ppl_conf *ppl_conf = conf->log_private;
     int i;
 
     if (quiesce) {
         for (i = 0; i < ppl_conf->count; i++) {
             struct ppl_log *log = &ppl_conf->child_logs[i];
 
             spin_lock_irq(&log->io_list_lock);
             wait_event_lock_irq(conf->wait_for_quiescent,
                         ppl_no_io_unit_submitted(conf, log),
                         log->io_list_lock);
             spin_unlock_irq(&log->io_list_lock);
         }
     }
 }
 
 int ppl_handle_flush_request(struct bio *bio)
 {
     if (bio->bi_iter.bi_size == 0) {
         bio_endio(bio);
         return 0;
     }
     bio->bi_opf &= ~REQ_PREFLUSH;
     return -EAGAIN;
 }
 
 void ppl_stripe_write_finished(struct stripe_head *sh)
 {
     struct ppl_io_unit *io;
 
     io = sh->ppl_io;
     sh->ppl_io = NULL;
 
     if (io && atomic_dec_and_test(&io->pending_stripes)) {
         if (io->log->disk_flush_bitmap)
             ppl_do_flush(io);
         else
             ppl_io_unit_finished(io);
     }
 }
 
 static void ppl_xor(int size, struct page *page1, struct page *page2)
 {
     struct async_submit_ctl submit;
     struct dma_async_tx_descriptor *tx;
     struct page *xor_srcs[] = { page1, page2 };
 
     init_async_submit(&submit, ASYNC_TX_ACK|ASYNC_TX_XOR_DROP_DST,
               NULL, NULL, NULL, NULL);
     tx = async_xor(page1, xor_srcs, 0, 2, size, &submit);
 
     async_tx_quiesce(&tx);
 }
 
 /*
  * PPL recovery strategy: xor partial parity and data from all modified data
  * disks within a stripe and write the result as the new stripe parity. If all
  * stripe data disks are modified (full stripe write), no partial parity is
  * available, so just xor the data disks.
  *
  * Recovery of a PPL entry shall occur only if all modified data disks are
  * available and read from all of them succeeds.
  *
  * A PPL entry applies to a stripe, partial parity size for an entry is at most
  * the size of the chunk. Examples of possible cases for a single entry:
  *
  * case 0: single data disk write:
  *   data0    data1    data2     ppl        parity
  * +--------+--------+--------+           +--------------------+
  * | ------ | ------ | ------ | +----+    | (no change)        |
  * | ------ | -data- | ------ | | pp | -> | data1 ^ pp         |
  * | ------ | -data- | ------ | | pp | -> | data1 ^ pp         |
  * | ------ | ------ | ------ | +----+    | (no change)        |
  * +--------+--------+--------+           +--------------------+
  * pp_size = data_size
  *
  * case 1: more than one data disk write:
  *   data0    data1    data2     ppl        parity
  * +--------+--------+--------+           +--------------------+
  * | ------ | ------ | ------ | +----+    | (no change)        |
  * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
  * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
  * | ------ | ------ | ------ | +----+    | (no change)        |
  * +--------+--------+--------+           +--------------------+
  * pp_size = data_size / modified_data_disks
  *
  * case 2: write to all data disks (also full stripe write):
  *   data0    data1    data2                parity
  * +--------+--------+--------+           +--------------------+
  * | ------ | ------ | ------ |           | (no change)        |
  * | -data- | -data- | -data- | --------> | xor all data       |
  * | ------ | ------ | ------ | --------> | (no change)        |
  * | ------ | ------ | ------ |           | (no change)        |
  * +--------+--------+--------+           +--------------------+
  * pp_size = 0
  *
  * The following cases are possible only in other implementations. The recovery
  * code can handle them, but they are not generated at runtime because they can
  * be reduced to cases 0, 1 and 2:
  *
  * case 3:
  *   data0    data1    data2     ppl        parity
  * +--------+--------+--------+ +----+    +--------------------+
  * | ------ | -data- | -data- | | pp |    | data1 ^ data2 ^ pp |
  * | ------ | -data- | -data- | | pp | -> | data1 ^ data2 ^ pp |
  * | -data- | -data- | -data- | | -- | -> | xor all data       |
  * | -data- | -data- | ------ | | pp |    | data0 ^ data1 ^ pp |
  * +--------+--------+--------+ +----+    +--------------------+
  * pp_size = chunk_size
  *
  * case 4:
  *   data0    data1    data2     ppl        parity
  * +--------+--------+--------+ +----+    +--------------------+
  * | ------ | -data- | ------ | | pp |    | data1 ^ pp         |
  * | ------ | ------ | ------ | | -- | -> | (no change)        |
  * | ------ | ------ | ------ | | -- | -> | (no change)        |
  * | -data- | ------ | ------ | | pp |    | data0 ^ pp         |
  * +--------+--------+--------+ +----+    +--------------------+
  * pp_size = chunk_size
  */
 static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e,
                  sector_t ppl_sector)
 {
     struct ppl_conf *ppl_conf = log->ppl_conf;
     struct mddev *mddev = ppl_conf->mddev;
     struct r5conf *conf = mddev->private;
     int block_size = ppl_conf->block_size;
     struct page *page1;
     struct page *page2;
     sector_t r_sector_first;
     sector_t r_sector_last;
     int strip_sectors;
     int data_disks;
     int i;
     int ret = 0;
     unsigned int pp_size = le32_to_cpu(e->pp_size);
     unsigned int data_size = le32_to_cpu(e->data_size);
 
     page1 = alloc_page(GFP_KERNEL);
     page2 = alloc_page(GFP_KERNEL);
 
     if (!page1 || !page2) {
         ret = -ENOMEM;
         goto out;
     }
 
     r_sector_first = le64_to_cpu(e->data_sector) * (block_size >> 9);
 
     if ((pp_size >> 9) < conf->chunk_sectors) {
         if (pp_size > 0) {
             data_disks = data_size / pp_size;
             strip_sectors = pp_size >> 9;
         } else {
             data_disks = conf->raid_disks - conf->max_degraded;
             strip_sectors = (data_size >> 9) / data_disks;
         }
         r_sector_last = r_sector_first +
                 (data_disks - 1) * conf->chunk_sectors +
                 strip_sectors;
     } else {
         data_disks = conf->raid_disks - conf->max_degraded;
         strip_sectors = conf->chunk_sectors;
         r_sector_last = r_sector_first + (data_size >> 9);
     }
 
     pr_debug("%s: array sector first: %llu last: %llu\n", __func__,
          (unsigned long long)r_sector_first,
          (unsigned long long)r_sector_last);
 
     /* if start and end is 4k aligned, use a 4k block */
     if (block_size == 512 &&
         (r_sector_first & (RAID5_STRIPE_SECTORS(conf) - 1)) == 0 &&
         (r_sector_last & (RAID5_STRIPE_SECTORS(conf) - 1)) == 0)
         block_size = RAID5_STRIPE_SIZE(conf);
 
     /* iterate through blocks in strip */
     for (i = 0; i < strip_sectors; i += (block_size >> 9)) {
         bool update_parity = false;
         sector_t parity_sector;
         struct md_rdev *parity_rdev;
         struct stripe_head sh;
         int disk;
         int indent = 0;
 
         pr_debug("%s:%*s iter %d start\n", __func__, indent, "", i);
         indent += 2;
 
         memset(page_address(page1), 0, PAGE_SIZE);
 
         /* iterate through data member disks */
         for (disk = 0; disk < data_disks; disk++) {
             int dd_idx;
             struct md_rdev *rdev;
             sector_t sector;
             sector_t r_sector = r_sector_first + i +
                         (disk * conf->chunk_sectors);
 
             pr_debug("%s:%*s data member disk %d start\n",
                  __func__, indent, "", disk);
             indent += 2;
 
             if (r_sector >= r_sector_last) {
                 pr_debug("%s:%*s array sector %llu doesn't need parity update\n",
                      __func__, indent, "",
                      (unsigned long long)r_sector);
                 indent -= 2;
                 continue;
             }
 
             update_parity = true;
 
             /* map raid sector to member disk */
             sector = raid5_compute_sector(conf, r_sector, 0,
                               &dd_idx, NULL);
             pr_debug("%s:%*s processing array sector %llu => data member disk %d, sector %llu\n",
                  __func__, indent, "",
                  (unsigned long long)r_sector, dd_idx,
                  (unsigned long long)sector);
 
             /* Array has not started so rcu dereference is safe */
             rdev = rcu_dereference_protected(
                     conf->disks[dd_idx].rdev, 1);
             if (!rdev || (!test_bit(In_sync, &rdev->flags) &&
                       sector >= rdev->recovery_offset)) {
                 pr_debug("%s:%*s data member disk %d missing\n",
                      __func__, indent, "", dd_idx);
                 update_parity = false;
                 break;
             }
 
             pr_debug("%s:%*s reading data member disk %pg sector %llu\n",
                  __func__, indent, "", rdev->bdev,
                  (unsigned long long)sector);
             if (!sync_page_io(rdev, sector, block_size, page2,
                     REQ_OP_READ, false)) {
                 md_error(mddev, rdev);
                 pr_debug("%s:%*s read failed!\n", __func__,
                      indent, "");
                 ret = -EIO;
                 goto out;
             }
 
             ppl_xor(block_size, page1, page2);
 
             indent -= 2;
         }
 
         if (!update_parity)
             continue;
 
         if (pp_size > 0) {
             pr_debug("%s:%*s reading pp disk sector %llu\n",
                  __func__, indent, "",
                  (unsigned long long)(ppl_sector + i));
             if (!sync_page_io(log->rdev,
                     ppl_sector - log->rdev->data_offset + i,
                     block_size, page2, REQ_OP_READ,
                     false)) {
                 pr_debug("%s:%*s read failed!\n", __func__,
                      indent, "");
                 md_error(mddev, log->rdev);
                 ret = -EIO;
                 goto out;
             }
 
             ppl_xor(block_size, page1, page2);
         }
 
         /* map raid sector to parity disk */
         parity_sector = raid5_compute_sector(conf, r_sector_first + i,
                 0, &disk, &sh);
         BUG_ON(sh.pd_idx != le32_to_cpu(e->parity_disk));
 
         /* Array has not started so rcu dereference is safe */
         parity_rdev = rcu_dereference_protected(
                     conf->disks[sh.pd_idx].rdev, 1);
 
         BUG_ON(parity_rdev->bdev->bd_dev != log->rdev->bdev->bd_dev);
         pr_debug("%s:%*s write parity at sector %llu, disk %pg\n",
              __func__, indent, "",
              (unsigned long long)parity_sector,
              parity_rdev->bdev);
         if (!sync_page_io(parity_rdev, parity_sector, block_size,
                   page1, REQ_OP_WRITE, false)) {
             pr_debug("%s:%*s parity write error!\n", __func__,
                  indent, "");
             md_error(mddev, parity_rdev);
             ret = -EIO;
             goto out;
         }
     }
 out:
     if (page1)
         __free_page(page1);
     if (page2)
         __free_page(page2);
     return ret;
 }
 
 static int ppl_recover(struct ppl_log *log, struct ppl_header *pplhdr,
                sector_t offset)
 {
     struct ppl_conf *ppl_conf = log->ppl_conf;
     struct md_rdev *rdev = log->rdev;
     struct mddev *mddev = rdev->mddev;
     sector_t ppl_sector = rdev->ppl.sector + offset +
                   (PPL_HEADER_SIZE >> 9);
     struct page *page;
     int i;
     int ret = 0;
 
     page = alloc_page(GFP_KERNEL);
     if (!page)
         return -ENOMEM;
 
     /* iterate through all PPL entries saved */
     for (i = 0; i < le32_to_cpu(pplhdr->entries_count); i++) {
         struct ppl_header_entry *e = &pplhdr->entries[i];
         u32 pp_size = le32_to_cpu(e->pp_size);
         sector_t sector = ppl_sector;
         int ppl_entry_sectors = pp_size >> 9;
         u32 crc, crc_stored;
 
         pr_debug("%s: disk: %d entry: %d ppl_sector: %llu pp_size: %u\n",
              __func__, rdev->raid_disk, i,
              (unsigned long long)ppl_sector, pp_size);
 
         crc = ~0;
         crc_stored = le32_to_cpu(e->checksum);
 
         /* read parial parity for this entry and calculate its checksum */
         while (pp_size) {
             int s = pp_size > PAGE_SIZE ? PAGE_SIZE : pp_size;
 
             if (!sync_page_io(rdev, sector - rdev->data_offset,
                     s, page, REQ_OP_READ, false)) {
                 md_error(mddev, rdev);
                 ret = -EIO;
                 goto out;
             }
 
             crc = crc32c_le(crc, page_address(page), s);
 
             pp_size -= s;
             sector += s >> 9;
         }
 
         crc = ~crc;
 
         if (crc != crc_stored) {
             /*
              * Don't recover this entry if the checksum does not
              * match, but keep going and try to recover other
              * entries.
              */
             pr_debug("%s: ppl entry crc does not match: stored: 0x%x calculated: 0x%x\n",
                  __func__, crc_stored, crc);
             ppl_conf->mismatch_count++;
         } else {
             ret = ppl_recover_entry(log, e, ppl_sector);
             if (ret)
                 goto out;
             ppl_conf->recovered_entries++;
         }
 
         ppl_sector += ppl_entry_sectors;
     }
 
     /* flush the disk cache after recovery if necessary */
     ret = blkdev_issue_flush(rdev->bdev);
 out:
     __free_page(page);
     return ret;
 }
 
 static int ppl_write_empty_header(struct ppl_log *log)
 {
     struct page *page;
     struct ppl_header *pplhdr;
     struct md_rdev *rdev = log->rdev;
     int ret = 0;
 
     pr_debug("%s: disk: %d ppl_sector: %llu\n", __func__,
          rdev->raid_disk, (unsigned long long)rdev->ppl.sector);
 
     page = alloc_page(GFP_NOIO | __GFP_ZERO);
     if (!page)
         return -ENOMEM;
 
     pplhdr = page_address(page);
     /* zero out PPL space to avoid collision with old PPLs */
     blkdev_issue_zeroout(rdev->bdev, rdev->ppl.sector,
                 log->rdev->ppl.size, GFP_NOIO, 0);
     memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
     pplhdr->signature = cpu_to_le32(log->ppl_conf->signature);
     pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PAGE_SIZE));
 
     if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
               PPL_HEADER_SIZE, page, REQ_OP_WRITE | REQ_SYNC |
               REQ_FUA, false)) {
         md_error(rdev->mddev, rdev);
         ret = -EIO;
     }
 
     __free_page(page);
     return ret;
 }
 
 static int ppl_load_distributed(struct ppl_log *log)
 {
     struct ppl_conf *ppl_conf = log->ppl_conf;
     struct md_rdev *rdev = log->rdev;
     struct mddev *mddev = rdev->mddev;
     struct page *page, *page2;
     struct ppl_header *pplhdr = NULL, *prev_pplhdr = NULL;
     u32 crc, crc_stored;
     u32 signature;
     int ret = 0, i;
     sector_t pplhdr_offset = 0, prev_pplhdr_offset = 0;
 
     pr_debug("%s: disk: %d\n", __func__, rdev->raid_disk);
     /* read PPL headers, find the recent one */
     page = alloc_page(GFP_KERNEL);
     if (!page)
         return -ENOMEM;
 
     page2 = alloc_page(GFP_KERNEL);
     if (!page2) {
         __free_page(page);
         return -ENOMEM;
     }
 
     /* searching ppl area for latest ppl */
     while (pplhdr_offset < rdev->ppl.size - (PPL_HEADER_SIZE >> 9)) {
         if (!sync_page_io(rdev,
                   rdev->ppl.sector - rdev->data_offset +
                   pplhdr_offset, PAGE_SIZE, page, REQ_OP_READ,
                   false)) {
             md_error(mddev, rdev);
             ret = -EIO;
             /* if not able to read - don't recover any PPL */
             pplhdr = NULL;
             break;
         }
         pplhdr = page_address(page);
 
         /* check header validity */
         crc_stored = le32_to_cpu(pplhdr->checksum);
         pplhdr->checksum = 0;
         crc = ~crc32c_le(~0, pplhdr, PAGE_SIZE);
 
         if (crc_stored != crc) {
             pr_debug("%s: ppl header crc does not match: stored: 0x%x calculated: 0x%x (offset: %llu)\n",
                  __func__, crc_stored, crc,
                  (unsigned long long)pplhdr_offset);
             pplhdr = prev_pplhdr;
             pplhdr_offset = prev_pplhdr_offset;
             break;
         }
 
         signature = le32_to_cpu(pplhdr->signature);
 
         if (mddev->external) {
             /*
              * For external metadata the header signature is set and
              * validated in userspace.
              */
             ppl_conf->signature = signature;
         } else if (ppl_conf->signature != signature) {
             pr_debug("%s: ppl header signature does not match: stored: 0x%x configured: 0x%x (offset: %llu)\n",
                  __func__, signature, ppl_conf->signature,
                  (unsigned long long)pplhdr_offset);
             pplhdr = prev_pplhdr;
             pplhdr_offset = prev_pplhdr_offset;
             break;
         }
 
         if (prev_pplhdr && le64_to_cpu(prev_pplhdr->generation) >
             le64_to_cpu(pplhdr->generation)) {
             /* previous was newest */
             pplhdr = prev_pplhdr;
             pplhdr_offset = prev_pplhdr_offset;
             break;
         }
 
         prev_pplhdr_offset = pplhdr_offset;
         prev_pplhdr = pplhdr;
 
         swap(page, page2);
 
         /* calculate next potential ppl offset */
         for (i = 0; i < le32_to_cpu(pplhdr->entries_count); i++)
             pplhdr_offset +=
                 le32_to_cpu(pplhdr->entries[i].pp_size) >> 9;
         pplhdr_offset += PPL_HEADER_SIZE >> 9;
     }
 
     /* no valid ppl found */
     if (!pplhdr)
         ppl_conf->mismatch_count++;
     else
         pr_debug("%s: latest PPL found at offset: %llu, with generation: %llu\n",
             __func__, (unsigned long long)pplhdr_offset,
             le64_to_cpu(pplhdr->generation));
 
     /* attempt to recover from log if we are starting a dirty array */
     if (pplhdr && !mddev->pers && mddev->recovery_cp != MaxSector)
         ret = ppl_recover(log, pplhdr, pplhdr_offset);
 
     /* write empty header if we are starting the array */
     if (!ret && !mddev->pers)
         ret = ppl_write_empty_header(log);
 
     __free_page(page);
     __free_page(page2);
 
     pr_debug("%s: return: %d mismatch_count: %d recovered_entries: %d\n",
          __func__, ret, ppl_conf->mismatch_count,
          ppl_conf->recovered_entries);
     return ret;
 }
 
 static int ppl_load(struct ppl_conf *ppl_conf)
 {
     int ret = 0;
     u32 signature = 0;
     bool signature_set = false;
     int i;
 
     for (i = 0; i < ppl_conf->count; i++) {
         struct ppl_log *log = &ppl_conf->child_logs[i];
 
         /* skip missing drive */
         if (!log->rdev)
             continue;
 
         ret = ppl_load_distributed(log);
         if (ret)
             break;
 
         /*
          * For external metadata we can't check if the signature is
          * correct on a single drive, but we can check if it is the same
          * on all drives.
          */
         if (ppl_conf->mddev->external) {
             if (!signature_set) {
                 signature = ppl_conf->signature;
                 signature_set = true;
             } else if (signature != ppl_conf->signature) {
                 pr_warn("md/raid:%s: PPL header signature does not match on all member drives\n",
                     mdname(ppl_conf->mddev));
                 ret = -EINVAL;
                 break;
             }
         }
     }
 
     pr_debug("%s: return: %d mismatch_count: %d recovered_entries: %d\n",
          __func__, ret, ppl_conf->mismatch_count,
          ppl_conf->recovered_entries);
     return ret;
 }
 
 static void __ppl_exit_log(struct ppl_conf *ppl_conf)
 {
     clear_bit(MD_HAS_PPL, &ppl_conf->mddev->flags);
     clear_bit(MD_HAS_MULTIPLE_PPLS, &ppl_conf->mddev->flags);
 
     kfree(ppl_conf->child_logs);
 
     bioset_exit(&ppl_conf->bs);
     bioset_exit(&ppl_conf->flush_bs);
     mempool_exit(&ppl_conf->io_pool);
     kmem_cache_destroy(ppl_conf->io_kc);
 
     kfree(ppl_conf);
 }
 
 void ppl_exit_log(struct r5conf *conf)
 {
     struct ppl_conf *ppl_conf = conf->log_private;
 
     if (ppl_conf) {
         __ppl_exit_log(ppl_conf);
         conf->log_private = NULL;
     }
 }
 
 static int ppl_validate_rdev(struct md_rdev *rdev)
 {
     int ppl_data_sectors;
     int ppl_size_new;
 
     /*
      * The configured PPL size must be enough to store
      * the header and (at the very least) partial parity
      * for one stripe. Round it down to ensure the data
      * space is cleanly divisible by stripe size.
      */
     ppl_data_sectors = rdev->ppl.size - (PPL_HEADER_SIZE >> 9);
 
     if (ppl_data_sectors > 0)
         ppl_data_sectors = rounddown(ppl_data_sectors,
                 RAID5_STRIPE_SECTORS((struct r5conf *)rdev->mddev->private));
 
     if (ppl_data_sectors <= 0) {
         pr_warn("md/raid:%s: PPL space too small on %pg\n",
             mdname(rdev->mddev), rdev->bdev);
         return -ENOSPC;
     }
 
     ppl_size_new = ppl_data_sectors + (PPL_HEADER_SIZE >> 9);
 
     if ((rdev->ppl.sector < rdev->data_offset &&
          rdev->ppl.sector + ppl_size_new > rdev->data_offset) ||
         (rdev->ppl.sector >= rdev->data_offset &&
          rdev->data_offset + rdev->sectors > rdev->ppl.sector)) {
         pr_warn("md/raid:%s: PPL space overlaps with data on %pg\n",
             mdname(rdev->mddev), rdev->bdev);
         return -EINVAL;
     }
 
     if (!rdev->mddev->external &&
         ((rdev->ppl.offset > 0 && rdev->ppl.offset < (rdev->sb_size >> 9)) ||
          (rdev->ppl.offset <= 0 && rdev->ppl.offset + ppl_size_new > 0))) {
         pr_warn("md/raid:%s: PPL space overlaps with superblock on %pg\n",
             mdname(rdev->mddev), rdev->bdev);
         return -EINVAL;
     }
 
     rdev->ppl.size = ppl_size_new;
 
     return 0;
 }
 
 static void ppl_init_child_log(struct ppl_log *log, struct md_rdev *rdev)
 {
     struct request_queue *q;
 
     if ((rdev->ppl.size << 9) >= (PPL_SPACE_SIZE +
                       PPL_HEADER_SIZE) * 2) {
         log->use_multippl = true;
         set_bit(MD_HAS_MULTIPLE_PPLS,
             &log->ppl_conf->mddev->flags);
         log->entry_space = PPL_SPACE_SIZE;
     } else {
         log->use_multippl = false;
         log->entry_space = (log->rdev->ppl.size << 9) -
                    PPL_HEADER_SIZE;
     }
     log->next_io_sector = rdev->ppl.sector;
 
     q = bdev_get_queue(rdev->bdev);
     if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
         log->wb_cache_on = true;
 }
 
 int ppl_init_log(struct r5conf *conf)
 {
     struct ppl_conf *ppl_conf;
     struct mddev *mddev = conf->mddev;
     int ret = 0;
     int max_disks;
     int i;
 
     pr_debug("md/raid:%s: enabling distributed Partial Parity Log\n",
          mdname(conf->mddev));
 
     if (PAGE_SIZE != 4096)
         return -EINVAL;
 
     if (mddev->level != 5) {
         pr_warn("md/raid:%s PPL is not compatible with raid level %d\n",
             mdname(mddev), mddev->level);
         return -EINVAL;
     }
 
     if (mddev->bitmap_info.file || mddev->bitmap_info.offset) {
         pr_warn("md/raid:%s PPL is not compatible with bitmap\n",
             mdname(mddev));
         return -EINVAL;
     }
 
     if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
         pr_warn("md/raid:%s PPL is not compatible with journal\n",
             mdname(mddev));
         return -EINVAL;
     }
 
     max_disks = sizeof_field(struct ppl_log, disk_flush_bitmap) *
         BITS_PER_BYTE;
     if (conf->raid_disks > max_disks) {
         pr_warn("md/raid:%s PPL doesn't support over %d disks in the array\n",
             mdname(mddev), max_disks);
         return -EINVAL;
     }
 
     ppl_conf = kzalloc(sizeof(struct ppl_conf), GFP_KERNEL);
     if (!ppl_conf)
         return -ENOMEM;
 
     ppl_conf->mddev = mddev;
 
     ppl_conf->io_kc = KMEM_CACHE(ppl_io_unit, 0);
     if (!ppl_conf->io_kc) {
         ret = -ENOMEM;
         goto err;
     }
 
     ret = mempool_init(&ppl_conf->io_pool, conf->raid_disks, ppl_io_pool_alloc,
                ppl_io_pool_free, ppl_conf->io_kc);
     if (ret)
         goto err;
 
     ret = bioset_init(&ppl_conf->bs, conf->raid_disks, 0, BIOSET_NEED_BVECS);
     if (ret)
         goto err;
 
     ret = bioset_init(&ppl_conf->flush_bs, conf->raid_disks, 0, 0);
     if (ret)
         goto err;
 
     ppl_conf->count = conf->raid_disks;
     ppl_conf->child_logs = kcalloc(ppl_conf->count, sizeof(struct ppl_log),
                        GFP_KERNEL);
     if (!ppl_conf->child_logs) {
         ret = -ENOMEM;
         goto err;
     }
 
     atomic64_set(&ppl_conf->seq, 0);
     INIT_LIST_HEAD(&ppl_conf->no_mem_stripes);
     spin_lock_init(&ppl_conf->no_mem_stripes_lock);
 
     if (!mddev->external) {
         ppl_conf->signature = ~crc32c_le(~0, mddev->uuid, sizeof(mddev->uuid));
         ppl_conf->block_size = 512;
     } else {
         ppl_conf->block_size = queue_logical_block_size(mddev->queue);
     }
 
     for (i = 0; i < ppl_conf->count; i++) {
         struct ppl_log *log = &ppl_conf->child_logs[i];
         /* Array has not started so rcu dereference is safe */
         struct md_rdev *rdev =
             rcu_dereference_protected(conf->disks[i].rdev, 1);
 
         mutex_init(&log->io_mutex);
         spin_lock_init(&log->io_list_lock);
         INIT_LIST_HEAD(&log->io_list);
 
         log->ppl_conf = ppl_conf;
         log->rdev = rdev;
 
         if (rdev) {
             ret = ppl_validate_rdev(rdev);
             if (ret)
                 goto err;
 
             ppl_init_child_log(log, rdev);
         }
     }
 
     /* load and possibly recover the logs from the member disks */
     ret = ppl_load(ppl_conf);
 
     if (ret) {
         goto err;
     } else if (!mddev->pers && mddev->recovery_cp == 0 &&
            ppl_conf->recovered_entries > 0 &&
            ppl_conf->mismatch_count == 0) {
         /*
          * If we are starting a dirty array and the recovery succeeds
          * without any issues, set the array as clean.
          */
         mddev->recovery_cp = MaxSector;
         set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
     } else if (mddev->pers && ppl_conf->mismatch_count > 0) {
         /* no mismatch allowed when enabling PPL for a running array */
         ret = -EINVAL;
         goto err;
     }
 
     conf->log_private = ppl_conf;
     set_bit(MD_HAS_PPL, &ppl_conf->mddev->flags);
 
     return 0;
 err:
     __ppl_exit_log(ppl_conf);
     return ret;
 }
 
 int ppl_modify_log(struct r5conf *conf, struct md_rdev *rdev, bool add)
 {
     struct ppl_conf *ppl_conf = conf->log_private;
     struct ppl_log *log;
     int ret = 0;
 
     if (!rdev)
         return -EINVAL;
 
     pr_debug("%s: disk: %d operation: %s dev: %pg\n",
          __func__, rdev->raid_disk, add ? "add" : "remove",
          rdev->bdev);
 
     if (rdev->raid_disk < 0)
         return 0;
 
     if (rdev->raid_disk >= ppl_conf->count)
         return -ENODEV;
 
     log = &ppl_conf->child_logs[rdev->raid_disk];
 
     mutex_lock(&log->io_mutex);
     if (add) {
         ret = ppl_validate_rdev(rdev);
         if (!ret) {
             log->rdev = rdev;
             ret = ppl_write_empty_header(log);
             ppl_init_child_log(log, rdev);
         }
     } else {
         log->rdev = NULL;
     }
     mutex_unlock(&log->io_mutex);
 
     return ret;
 }
 
 static ssize_t
 ppl_write_hint_show(struct mddev *mddev, char *buf)
 {
     return sprintf(buf, "%d\n", 0);
 }
 
 static ssize_t
 ppl_write_hint_store(struct mddev *mddev, const char *page, size_t len)
 {
     struct r5conf *conf;
     int err = 0;
     unsigned short new;
 
     if (len >= PAGE_SIZE)
         return -EINVAL;
     if (kstrtou16(page, 10, &new))
         return -EINVAL;
 
     err = mddev_lock(mddev);
     if (err)
         return err;
 
     conf = mddev->private;
     if (!conf)
         err = -ENODEV;
     else if (!raid5_has_ppl(conf) || !conf->log_private)
         err = -EINVAL;
 
     mddev_unlock(mddev);
 
     return err ?: len;
 }
 
 struct md_sysfs_entry
 ppl_write_hint = __ATTR(ppl_write_hint, S_IRUGO | S_IWUSR,
             ppl_write_hint_show,
             ppl_write_hint_store);

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