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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
 /*
  * Copyright (C) 2017 Western Digital Corporation or its affiliates.
  *
  * This file is released under the GPL.
  */
 
 #include "dm-zoned.h"
 
 #include <linux/module.h>
 #include <linux/crc32.h>
 #include <linux/sched/mm.h>
 
 #define DM_MSG_PREFIX       "zoned metadata"
 
 /*
  * Metadata version.
  */
 #define DMZ_META_VER    2
 
 /*
  * On-disk super block magic.
  */
 #define DMZ_MAGIC   ((((unsigned int)('D')) << 24) | \
              (((unsigned int)('Z')) << 16) | \
              (((unsigned int)('B')) <<  8) | \
              ((unsigned int)('D')))
 
 /*
  * On disk super block.
  * This uses only 512 B but uses on disk a full 4KB block. This block is
  * followed on disk by the mapping table of chunks to zones and the bitmap
  * blocks indicating zone block validity.
  * The overall resulting metadata format is:
  *    (1) Super block (1 block)
  *    (2) Chunk mapping table (nr_map_blocks)
  *    (3) Bitmap blocks (nr_bitmap_blocks)
  * All metadata blocks are stored in conventional zones, starting from
  * the first conventional zone found on disk.
  */
 struct dmz_super {
     /* Magic number */
     __le32      magic;          /*   4 */
 
     /* Metadata version number */
     __le32      version;        /*   8 */
 
     /* Generation number */
     __le64      gen;            /*  16 */
 
     /* This block number */
     __le64      sb_block;       /*  24 */
 
     /* The number of metadata blocks, including this super block */
     __le32      nr_meta_blocks;     /*  28 */
 
     /* The number of sequential zones reserved for reclaim */
     __le32      nr_reserved_seq;    /*  32 */
 
     /* The number of entries in the mapping table */
     __le32      nr_chunks;      /*  36 */
 
     /* The number of blocks used for the chunk mapping table */
     __le32      nr_map_blocks;      /*  40 */
 
     /* The number of blocks used for the block bitmaps */
     __le32      nr_bitmap_blocks;   /*  44 */
 
     /* Checksum */
     __le32      crc;            /*  48 */
 
     /* DM-Zoned label */
     u8      dmz_label[32];      /*  80 */
 
     /* DM-Zoned UUID */
     u8      dmz_uuid[16];       /*  96 */
 
     /* Device UUID */
     u8      dev_uuid[16];       /* 112 */
 
     /* Padding to full 512B sector */
     u8      reserved[400];      /* 512 */
 };
 
 /*
  * Chunk mapping entry: entries are indexed by chunk number
  * and give the zone ID (dzone_id) mapping the chunk on disk.
  * This zone may be sequential or random. If it is a sequential
  * zone, a second zone (bzone_id) used as a write buffer may
  * also be specified. This second zone will always be a randomly
  * writeable zone.
  */
 struct dmz_map {
     __le32          dzone_id;
     __le32          bzone_id;
 };
 
 /*
  * Chunk mapping table metadata: 512 8-bytes entries per 4KB block.
  */
 #define DMZ_MAP_ENTRIES     (DMZ_BLOCK_SIZE / sizeof(struct dmz_map))
 #define DMZ_MAP_ENTRIES_SHIFT   (ilog2(DMZ_MAP_ENTRIES))
 #define DMZ_MAP_ENTRIES_MASK    (DMZ_MAP_ENTRIES - 1)
 #define DMZ_MAP_UNMAPPED    UINT_MAX
 
 /*
  * Meta data block descriptor (for cached metadata blocks).
  */
 struct dmz_mblock {
     struct rb_node      node;
     struct list_head    link;
     sector_t        no;
     unsigned int        ref;
     unsigned long       state;
     struct page     *page;
     void            *data;
 };
 
 /*
  * Metadata block state flags.
  */
 enum {
     DMZ_META_DIRTY,
     DMZ_META_READING,
     DMZ_META_WRITING,
     DMZ_META_ERROR,
 };
 
 /*
  * Super block information (one per metadata set).
  */
 struct dmz_sb {
     sector_t        block;
     struct dmz_dev      *dev;
     struct dmz_mblock   *mblk;
     struct dmz_super    *sb;
     struct dm_zone      *zone;
 };
 
 /*
  * In-memory metadata.
  */
 struct dmz_metadata {
     struct dmz_dev      *dev;
     unsigned int        nr_devs;
 
     char            devname[BDEVNAME_SIZE];
     char            label[BDEVNAME_SIZE];
     uuid_t          uuid;
 
     sector_t        zone_bitmap_size;
     unsigned int        zone_nr_bitmap_blocks;
     unsigned int        zone_bits_per_mblk;
 
     sector_t        zone_nr_blocks;
     sector_t        zone_nr_blocks_shift;
 
     sector_t        zone_nr_sectors;
     sector_t        zone_nr_sectors_shift;
 
     unsigned int        nr_bitmap_blocks;
     unsigned int        nr_map_blocks;
 
     unsigned int        nr_zones;
     unsigned int        nr_useable_zones;
     unsigned int        nr_meta_blocks;
     unsigned int        nr_meta_zones;
     unsigned int        nr_data_zones;
     unsigned int        nr_cache_zones;
     unsigned int        nr_rnd_zones;
     unsigned int        nr_reserved_seq;
     unsigned int        nr_chunks;
 
     /* Zone information array */
     struct xarray       zones;
 
     struct dmz_sb       sb[2];
     unsigned int        mblk_primary;
     unsigned int        sb_version;
     u64         sb_gen;
     unsigned int        min_nr_mblks;
     unsigned int        max_nr_mblks;
     atomic_t        nr_mblks;
     struct rw_semaphore mblk_sem;
     struct mutex        mblk_flush_lock;
     spinlock_t      mblk_lock;
     struct rb_root      mblk_rbtree;
     struct list_head    mblk_lru_list;
     struct list_head    mblk_dirty_list;
     struct shrinker     mblk_shrinker;
 
     /* Zone allocation management */
     struct mutex        map_lock;
     struct dmz_mblock   **map_mblk;
 
     unsigned int        nr_cache;
     atomic_t        unmap_nr_cache;
     struct list_head    unmap_cache_list;
     struct list_head    map_cache_list;
 
     atomic_t        nr_reserved_seq_zones;
     struct list_head    reserved_seq_zones_list;
 
     wait_queue_head_t   free_wq;
 };
 
 #define dmz_zmd_info(zmd, format, args...)  \
     DMINFO("(%s): " format, (zmd)->label, ## args)
 
 #define dmz_zmd_err(zmd, format, args...)   \
     DMERR("(%s): " format, (zmd)->label, ## args)
 
 #define dmz_zmd_warn(zmd, format, args...)  \
     DMWARN("(%s): " format, (zmd)->label, ## args)
 
 #define dmz_zmd_debug(zmd, format, args...) \
     DMDEBUG("(%s): " format, (zmd)->label, ## args)
 /*
  * Various accessors
  */
 static unsigned int dmz_dev_zone_id(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
     if (WARN_ON(!zone))
         return 0;
 
     return zone->id - zone->dev->zone_offset;
 }
 
 sector_t dmz_start_sect(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
     unsigned int zone_id = dmz_dev_zone_id(zmd, zone);
 
     return (sector_t)zone_id << zmd->zone_nr_sectors_shift;
 }
 
 sector_t dmz_start_block(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
     unsigned int zone_id = dmz_dev_zone_id(zmd, zone);
 
     return (sector_t)zone_id << zmd->zone_nr_blocks_shift;
 }
 
 unsigned int dmz_zone_nr_blocks(struct dmz_metadata *zmd)
 {
     return zmd->zone_nr_blocks;
 }
 
 unsigned int dmz_zone_nr_blocks_shift(struct dmz_metadata *zmd)
 {
     return zmd->zone_nr_blocks_shift;
 }
 
 unsigned int dmz_zone_nr_sectors(struct dmz_metadata *zmd)
 {
     return zmd->zone_nr_sectors;
 }
 
 unsigned int dmz_zone_nr_sectors_shift(struct dmz_metadata *zmd)
 {
     return zmd->zone_nr_sectors_shift;
 }
 
 unsigned int dmz_nr_zones(struct dmz_metadata *zmd)
 {
     return zmd->nr_zones;
 }
 
 unsigned int dmz_nr_chunks(struct dmz_metadata *zmd)
 {
     return zmd->nr_chunks;
 }
 
 unsigned int dmz_nr_rnd_zones(struct dmz_metadata *zmd, int idx)
 {
     return zmd->dev[idx].nr_rnd;
 }
 
 unsigned int dmz_nr_unmap_rnd_zones(struct dmz_metadata *zmd, int idx)
 {
     return atomic_read(&zmd->dev[idx].unmap_nr_rnd);
 }
 
 unsigned int dmz_nr_cache_zones(struct dmz_metadata *zmd)
 {
     return zmd->nr_cache;
 }
 
 unsigned int dmz_nr_unmap_cache_zones(struct dmz_metadata *zmd)
 {
     return atomic_read(&zmd->unmap_nr_cache);
 }
 
 unsigned int dmz_nr_seq_zones(struct dmz_metadata *zmd, int idx)
 {
     return zmd->dev[idx].nr_seq;
 }
 
 unsigned int dmz_nr_unmap_seq_zones(struct dmz_metadata *zmd, int idx)
 {
     return atomic_read(&zmd->dev[idx].unmap_nr_seq);
 }
 
 static struct dm_zone *dmz_get(struct dmz_metadata *zmd, unsigned int zone_id)
 {
     return xa_load(&zmd->zones, zone_id);
 }
 
 static struct dm_zone *dmz_insert(struct dmz_metadata *zmd,
                   unsigned int zone_id, struct dmz_dev *dev)
 {
     struct dm_zone *zone = kzalloc(sizeof(struct dm_zone), GFP_KERNEL);
 
     if (!zone)
         return ERR_PTR(-ENOMEM);
 
     if (xa_insert(&zmd->zones, zone_id, zone, GFP_KERNEL)) {
         kfree(zone);
         return ERR_PTR(-EBUSY);
     }
 
     INIT_LIST_HEAD(&zone->link);
     atomic_set(&zone->refcount, 0);
     zone->id = zone_id;
     zone->chunk = DMZ_MAP_UNMAPPED;
     zone->dev = dev;
 
     return zone;
 }
 
 const char *dmz_metadata_label(struct dmz_metadata *zmd)
 {
     return (const char *)zmd->label;
 }
 
 bool dmz_check_dev(struct dmz_metadata *zmd)
 {
     unsigned int i;
 
     for (i = 0; i < zmd->nr_devs; i++) {
         if (!dmz_check_bdev(&zmd->dev[i]))
             return false;
     }
     return true;
 }
 
 bool dmz_dev_is_dying(struct dmz_metadata *zmd)
 {
     unsigned int i;
 
     for (i = 0; i < zmd->nr_devs; i++) {
         if (dmz_bdev_is_dying(&zmd->dev[i]))
             return true;
     }
     return false;
 }
 
 /*
  * Lock/unlock mapping table.
  * The map lock also protects all the zone lists.
  */
 void dmz_lock_map(struct dmz_metadata *zmd)
 {
     mutex_lock(&zmd->map_lock);
 }
 
 void dmz_unlock_map(struct dmz_metadata *zmd)
 {
     mutex_unlock(&zmd->map_lock);
 }
 
 /*
  * Lock/unlock metadata access. This is a "read" lock on a semaphore
  * that prevents metadata flush from running while metadata are being
  * modified. The actual metadata write mutual exclusion is achieved with
  * the map lock and zone state management (active and reclaim state are
  * mutually exclusive).
  */
 void dmz_lock_metadata(struct dmz_metadata *zmd)
 {
     down_read(&zmd->mblk_sem);
 }
 
 void dmz_unlock_metadata(struct dmz_metadata *zmd)
 {
     up_read(&zmd->mblk_sem);
 }
 
 /*
  * Lock/unlock flush: prevent concurrent executions
  * of dmz_flush_metadata as well as metadata modification in reclaim
  * while flush is being executed.
  */
 void dmz_lock_flush(struct dmz_metadata *zmd)
 {
     mutex_lock(&zmd->mblk_flush_lock);
 }
 
 void dmz_unlock_flush(struct dmz_metadata *zmd)
 {
     mutex_unlock(&zmd->mblk_flush_lock);
 }
 
 /*
  * Allocate a metadata block.
  */
 static struct dmz_mblock *dmz_alloc_mblock(struct dmz_metadata *zmd,
                        sector_t mblk_no)
 {
     struct dmz_mblock *mblk = NULL;
 
     /* See if we can reuse cached blocks */
     if (zmd->max_nr_mblks && atomic_read(&zmd->nr_mblks) > zmd->max_nr_mblks) {
         spin_lock(&zmd->mblk_lock);
         mblk = list_first_entry_or_null(&zmd->mblk_lru_list,
                         struct dmz_mblock, link);
         if (mblk) {
             list_del_init(&mblk->link);
             rb_erase(&mblk->node, &zmd->mblk_rbtree);
             mblk->no = mblk_no;
         }
         spin_unlock(&zmd->mblk_lock);
         if (mblk)
             return mblk;
     }
 
     /* Allocate a new block */
     mblk = kmalloc(sizeof(struct dmz_mblock), GFP_NOIO);
     if (!mblk)
         return NULL;
 
     mblk->page = alloc_page(GFP_NOIO);
     if (!mblk->page) {
         kfree(mblk);
         return NULL;
     }
 
     RB_CLEAR_NODE(&mblk->node);
     INIT_LIST_HEAD(&mblk->link);
     mblk->ref = 0;
     mblk->state = 0;
     mblk->no = mblk_no;
     mblk->data = page_address(mblk->page);
 
     atomic_inc(&zmd->nr_mblks);
 
     return mblk;
 }
 
 /*
  * Free a metadata block.
  */
 static void dmz_free_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk)
 {
     __free_pages(mblk->page, 0);
     kfree(mblk);
 
     atomic_dec(&zmd->nr_mblks);
 }
 
 /*
  * Insert a metadata block in the rbtree.
  */
 static void dmz_insert_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk)
 {
     struct rb_root *root = &zmd->mblk_rbtree;
     struct rb_node **new = &(root->rb_node), *parent = NULL;
     struct dmz_mblock *b;
 
     /* Figure out where to put the new node */
     while (*new) {
         b = container_of(*new, struct dmz_mblock, node);
         parent = *new;
         new = (b->no < mblk->no) ? &((*new)->rb_left) : &((*new)->rb_right);
     }
 
     /* Add new node and rebalance tree */
     rb_link_node(&mblk->node, parent, new);
     rb_insert_color(&mblk->node, root);
 }
 
 /*
  * Lookup a metadata block in the rbtree. If the block is found, increment
  * its reference count.
  */
 static struct dmz_mblock *dmz_get_mblock_fast(struct dmz_metadata *zmd,
                           sector_t mblk_no)
 {
     struct rb_root *root = &zmd->mblk_rbtree;
     struct rb_node *node = root->rb_node;
     struct dmz_mblock *mblk;
 
     while (node) {
         mblk = container_of(node, struct dmz_mblock, node);
         if (mblk->no == mblk_no) {
             /*
              * If this is the first reference to the block,
              * remove it from the LRU list.
              */
             mblk->ref++;
             if (mblk->ref == 1 &&
                 !test_bit(DMZ_META_DIRTY, &mblk->state))
                 list_del_init(&mblk->link);
             return mblk;
         }
         node = (mblk->no < mblk_no) ? node->rb_left : node->rb_right;
     }
 
     return NULL;
 }
 
 /*
  * Metadata block BIO end callback.
  */
 static void dmz_mblock_bio_end_io(struct bio *bio)
 {
     struct dmz_mblock *mblk = bio->bi_private;
     int flag;
 
     if (bio->bi_status)
         set_bit(DMZ_META_ERROR, &mblk->state);
 
     if (bio_op(bio) == REQ_OP_WRITE)
         flag = DMZ_META_WRITING;
     else
         flag = DMZ_META_READING;
 
     clear_bit_unlock(flag, &mblk->state);
     smp_mb__after_atomic();
     wake_up_bit(&mblk->state, flag);
 
     bio_put(bio);
 }
 
 /*
  * Read an uncached metadata block from disk and add it to the cache.
  */
 static struct dmz_mblock *dmz_get_mblock_slow(struct dmz_metadata *zmd,
                           sector_t mblk_no)
 {
     struct dmz_mblock *mblk, *m;
     sector_t block = zmd->sb[zmd->mblk_primary].block + mblk_no;
     struct dmz_dev *dev = zmd->sb[zmd->mblk_primary].dev;
     struct bio *bio;
 
     if (dmz_bdev_is_dying(dev))
         return ERR_PTR(-EIO);
 
     /* Get a new block and a BIO to read it */
     mblk = dmz_alloc_mblock(zmd, mblk_no);
     if (!mblk)
         return ERR_PTR(-ENOMEM);
 
     bio = bio_alloc(dev->bdev, 1, REQ_OP_READ | REQ_META | REQ_PRIO,
             GFP_NOIO);
 
     spin_lock(&zmd->mblk_lock);
 
     /*
      * Make sure that another context did not start reading
      * the block already.
      */
     m = dmz_get_mblock_fast(zmd, mblk_no);
     if (m) {
         spin_unlock(&zmd->mblk_lock);
         dmz_free_mblock(zmd, mblk);
         bio_put(bio);
         return m;
     }
 
     mblk->ref++;
     set_bit(DMZ_META_READING, &mblk->state);
     dmz_insert_mblock(zmd, mblk);
 
     spin_unlock(&zmd->mblk_lock);
 
     /* Submit read BIO */
     bio->bi_iter.bi_sector = dmz_blk2sect(block);
     bio->bi_private = mblk;
     bio->bi_end_io = dmz_mblock_bio_end_io;
     bio_add_page(bio, mblk->page, DMZ_BLOCK_SIZE, 0);
     submit_bio(bio);
 
     return mblk;
 }
 
 /*
  * Free metadata blocks.
  */
 static unsigned long dmz_shrink_mblock_cache(struct dmz_metadata *zmd,
                          unsigned long limit)
 {
     struct dmz_mblock *mblk;
     unsigned long count = 0;
 
     if (!zmd->max_nr_mblks)
         return 0;
 
     while (!list_empty(&zmd->mblk_lru_list) &&
            atomic_read(&zmd->nr_mblks) > zmd->min_nr_mblks &&
            count < limit) {
         mblk = list_first_entry(&zmd->mblk_lru_list,
                     struct dmz_mblock, link);
         list_del_init(&mblk->link);
         rb_erase(&mblk->node, &zmd->mblk_rbtree);
         dmz_free_mblock(zmd, mblk);
         count++;
     }
 
     return count;
 }
 
 /*
  * For mblock shrinker: get the number of unused metadata blocks in the cache.
  */
 static unsigned long dmz_mblock_shrinker_count(struct shrinker *shrink,
                            struct shrink_control *sc)
 {
     struct dmz_metadata *zmd = container_of(shrink, struct dmz_metadata, mblk_shrinker);
 
     return atomic_read(&zmd->nr_mblks);
 }
 
 /*
  * For mblock shrinker: scan unused metadata blocks and shrink the cache.
  */
 static unsigned long dmz_mblock_shrinker_scan(struct shrinker *shrink,
                           struct shrink_control *sc)
 {
     struct dmz_metadata *zmd = container_of(shrink, struct dmz_metadata, mblk_shrinker);
     unsigned long count;
 
     spin_lock(&zmd->mblk_lock);
     count = dmz_shrink_mblock_cache(zmd, sc->nr_to_scan);
     spin_unlock(&zmd->mblk_lock);
 
     return count ? count : SHRINK_STOP;
 }
 
 /*
  * Release a metadata block.
  */
 static void dmz_release_mblock(struct dmz_metadata *zmd,
                    struct dmz_mblock *mblk)
 {
 
     if (!mblk)
         return;
 
     spin_lock(&zmd->mblk_lock);
 
     mblk->ref--;
     if (mblk->ref == 0) {
         if (test_bit(DMZ_META_ERROR, &mblk->state)) {
             rb_erase(&mblk->node, &zmd->mblk_rbtree);
             dmz_free_mblock(zmd, mblk);
         } else if (!test_bit(DMZ_META_DIRTY, &mblk->state)) {
             list_add_tail(&mblk->link, &zmd->mblk_lru_list);
             dmz_shrink_mblock_cache(zmd, 1);
         }
     }
 
     spin_unlock(&zmd->mblk_lock);
 }
 
 /*
  * Get a metadata block from the rbtree. If the block
  * is not present, read it from disk.
  */
 static struct dmz_mblock *dmz_get_mblock(struct dmz_metadata *zmd,
                      sector_t mblk_no)
 {
     struct dmz_mblock *mblk;
     struct dmz_dev *dev = zmd->sb[zmd->mblk_primary].dev;
 
     /* Check rbtree */
     spin_lock(&zmd->mblk_lock);
     mblk = dmz_get_mblock_fast(zmd, mblk_no);
     spin_unlock(&zmd->mblk_lock);
 
     if (!mblk) {
         /* Cache miss: read the block from disk */
         mblk = dmz_get_mblock_slow(zmd, mblk_no);
         if (IS_ERR(mblk))
             return mblk;
     }
 
     /* Wait for on-going read I/O and check for error */
     wait_on_bit_io(&mblk->state, DMZ_META_READING,
                TASK_UNINTERRUPTIBLE);
     if (test_bit(DMZ_META_ERROR, &mblk->state)) {
         dmz_release_mblock(zmd, mblk);
         dmz_check_bdev(dev);
         return ERR_PTR(-EIO);
     }
 
     return mblk;
 }
 
 /*
  * Mark a metadata block dirty.
  */
 static void dmz_dirty_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk)
 {
     spin_lock(&zmd->mblk_lock);
     if (!test_and_set_bit(DMZ_META_DIRTY, &mblk->state))
         list_add_tail(&mblk->link, &zmd->mblk_dirty_list);
     spin_unlock(&zmd->mblk_lock);
 }
 
 /*
  * Issue a metadata block write BIO.
  */
 static int dmz_write_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk,
                 unsigned int set)
 {
     struct dmz_dev *dev = zmd->sb[set].dev;
     sector_t block = zmd->sb[set].block + mblk->no;
     struct bio *bio;
 
     if (dmz_bdev_is_dying(dev))
         return -EIO;
 
     bio = bio_alloc(dev->bdev, 1, REQ_OP_WRITE | REQ_META | REQ_PRIO,
             GFP_NOIO);
 
     set_bit(DMZ_META_WRITING, &mblk->state);
 
     bio->bi_iter.bi_sector = dmz_blk2sect(block);
     bio->bi_private = mblk;
     bio->bi_end_io = dmz_mblock_bio_end_io;
     bio_add_page(bio, mblk->page, DMZ_BLOCK_SIZE, 0);
     submit_bio(bio);
 
     return 0;
 }
 
 /*
  * Read/write a metadata block.
  */
 static int dmz_rdwr_block(struct dmz_dev *dev, enum req_op op,
               sector_t block, struct page *page)
 {
     struct bio *bio;
     int ret;
 
     if (WARN_ON(!dev))
         return -EIO;
 
     if (dmz_bdev_is_dying(dev))
         return -EIO;
 
     bio = bio_alloc(dev->bdev, 1, op | REQ_SYNC | REQ_META | REQ_PRIO,
             GFP_NOIO);
     bio->bi_iter.bi_sector = dmz_blk2sect(block);
     bio_add_page(bio, page, DMZ_BLOCK_SIZE, 0);
     ret = submit_bio_wait(bio);
     bio_put(bio);
 
     if (ret)
         dmz_check_bdev(dev);
     return ret;
 }
 
 /*
  * Write super block of the specified metadata set.
  */
 static int dmz_write_sb(struct dmz_metadata *zmd, unsigned int set)
 {
     struct dmz_mblock *mblk = zmd->sb[set].mblk;
     struct dmz_super *sb = zmd->sb[set].sb;
     struct dmz_dev *dev = zmd->sb[set].dev;
     sector_t sb_block;
     u64 sb_gen = zmd->sb_gen + 1;
     int ret;
 
     sb->magic = cpu_to_le32(DMZ_MAGIC);
 
     sb->version = cpu_to_le32(zmd->sb_version);
     if (zmd->sb_version > 1) {
         BUILD_BUG_ON(UUID_SIZE != 16);
         export_uuid(sb->dmz_uuid, &zmd->uuid);
         memcpy(sb->dmz_label, zmd->label, BDEVNAME_SIZE);
         export_uuid(sb->dev_uuid, &dev->uuid);
     }
 
     sb->gen = cpu_to_le64(sb_gen);
 
     /*
      * The metadata always references the absolute block address,
      * ie relative to the entire block range, not the per-device
      * block address.
      */
     sb_block = zmd->sb[set].zone->id << zmd->zone_nr_blocks_shift;
     sb->sb_block = cpu_to_le64(sb_block);
     sb->nr_meta_blocks = cpu_to_le32(zmd->nr_meta_blocks);
     sb->nr_reserved_seq = cpu_to_le32(zmd->nr_reserved_seq);
     sb->nr_chunks = cpu_to_le32(zmd->nr_chunks);
 
     sb->nr_map_blocks = cpu_to_le32(zmd->nr_map_blocks);
     sb->nr_bitmap_blocks = cpu_to_le32(zmd->nr_bitmap_blocks);
 
     sb->crc = 0;
     sb->crc = cpu_to_le32(crc32_le(sb_gen, (unsigned char *)sb, DMZ_BLOCK_SIZE));
 
     ret = dmz_rdwr_block(dev, REQ_OP_WRITE, zmd->sb[set].block,
                  mblk->page);
     if (ret == 0)
         ret = blkdev_issue_flush(dev->bdev);
 
     return ret;
 }
 
 /*
  * Write dirty metadata blocks to the specified set.
  */
 static int dmz_write_dirty_mblocks(struct dmz_metadata *zmd,
                    struct list_head *write_list,
                    unsigned int set)
 {
     struct dmz_mblock *mblk;
     struct dmz_dev *dev = zmd->sb[set].dev;
     struct blk_plug plug;
     int ret = 0, nr_mblks_submitted = 0;
 
     /* Issue writes */
     blk_start_plug(&plug);
     list_for_each_entry(mblk, write_list, link) {
         ret = dmz_write_mblock(zmd, mblk, set);
         if (ret)
             break;
         nr_mblks_submitted++;
     }
     blk_finish_plug(&plug);
 
     /* Wait for completion */
     list_for_each_entry(mblk, write_list, link) {
         if (!nr_mblks_submitted)
             break;
         wait_on_bit_io(&mblk->state, DMZ_META_WRITING,
                    TASK_UNINTERRUPTIBLE);
         if (test_bit(DMZ_META_ERROR, &mblk->state)) {
             clear_bit(DMZ_META_ERROR, &mblk->state);
             dmz_check_bdev(dev);
             ret = -EIO;
         }
         nr_mblks_submitted--;
     }
 
     /* Flush drive cache (this will also sync data) */
     if (ret == 0)
         ret = blkdev_issue_flush(dev->bdev);
 
     return ret;
 }
 
 /*
  * Log dirty metadata blocks.
  */
 static int dmz_log_dirty_mblocks(struct dmz_metadata *zmd,
                  struct list_head *write_list)
 {
     unsigned int log_set = zmd->mblk_primary ^ 0x1;
     int ret;
 
     /* Write dirty blocks to the log */
     ret = dmz_write_dirty_mblocks(zmd, write_list, log_set);
     if (ret)
         return ret;
 
     /*
      * No error so far: now validate the log by updating the
      * log index super block generation.
      */
     ret = dmz_write_sb(zmd, log_set);
     if (ret)
         return ret;
 
     return 0;
 }
 
 /*
  * Flush dirty metadata blocks.
  */
 int dmz_flush_metadata(struct dmz_metadata *zmd)
 {
     struct dmz_mblock *mblk;
     struct list_head write_list;
     struct dmz_dev *dev;
     int ret;
 
     if (WARN_ON(!zmd))
         return 0;
 
     INIT_LIST_HEAD(&write_list);
 
     /*
      * Make sure that metadata blocks are stable before logging: take
      * the write lock on the metadata semaphore to prevent target BIOs
      * from modifying metadata.
      */
     down_write(&zmd->mblk_sem);
     dev = zmd->sb[zmd->mblk_primary].dev;
 
     /*
      * This is called from the target flush work and reclaim work.
      * Concurrent execution is not allowed.
      */
     dmz_lock_flush(zmd);
 
     if (dmz_bdev_is_dying(dev)) {
         ret = -EIO;
         goto out;
     }
 
     /* Get dirty blocks */
     spin_lock(&zmd->mblk_lock);
     list_splice_init(&zmd->mblk_dirty_list, &write_list);
     spin_unlock(&zmd->mblk_lock);
 
     /* If there are no dirty metadata blocks, just flush the device cache */
     if (list_empty(&write_list)) {
         ret = blkdev_issue_flush(dev->bdev);
         goto err;
     }
 
     /*
      * The primary metadata set is still clean. Keep it this way until
      * all updates are successful in the secondary set. That is, use
      * the secondary set as a log.
      */
     ret = dmz_log_dirty_mblocks(zmd, &write_list);
     if (ret)
         goto err;
 
     /*
      * The log is on disk. It is now safe to update in place
      * in the primary metadata set.
      */
     ret = dmz_write_dirty_mblocks(zmd, &write_list, zmd->mblk_primary);
     if (ret)
         goto err;
 
     ret = dmz_write_sb(zmd, zmd->mblk_primary);
     if (ret)
         goto err;
 
     while (!list_empty(&write_list)) {
         mblk = list_first_entry(&write_list, struct dmz_mblock, link);
         list_del_init(&mblk->link);
 
         spin_lock(&zmd->mblk_lock);
         clear_bit(DMZ_META_DIRTY, &mblk->state);
         if (mblk->ref == 0)
             list_add_tail(&mblk->link, &zmd->mblk_lru_list);
         spin_unlock(&zmd->mblk_lock);
     }
 
     zmd->sb_gen++;
 out:
     dmz_unlock_flush(zmd);
     up_write(&zmd->mblk_sem);
 
     return ret;
 
 err:
     if (!list_empty(&write_list)) {
         spin_lock(&zmd->mblk_lock);
         list_splice(&write_list, &zmd->mblk_dirty_list);
         spin_unlock(&zmd->mblk_lock);
     }
     if (!dmz_check_bdev(dev))
         ret = -EIO;
     goto out;
 }
 
 /*
  * Check super block.
  */
 static int dmz_check_sb(struct dmz_metadata *zmd, struct dmz_sb *dsb,
             bool tertiary)
 {
     struct dmz_super *sb = dsb->sb;
     struct dmz_dev *dev = dsb->dev;
     unsigned int nr_meta_zones, nr_data_zones;
     u32 crc, stored_crc;
     u64 gen, sb_block;
 
     if (le32_to_cpu(sb->magic) != DMZ_MAGIC) {
         dmz_dev_err(dev, "Invalid meta magic (needed 0x%08x, got 0x%08x)",
                 DMZ_MAGIC, le32_to_cpu(sb->magic));
         return -ENXIO;
     }
 
     zmd->sb_version = le32_to_cpu(sb->version);
     if (zmd->sb_version > DMZ_META_VER) {
         dmz_dev_err(dev, "Invalid meta version (needed %d, got %d)",
                 DMZ_META_VER, zmd->sb_version);
         return -EINVAL;
     }
     if (zmd->sb_version < 2 && tertiary) {
         dmz_dev_err(dev, "Tertiary superblocks are not supported");
         return -EINVAL;
     }
 
     gen = le64_to_cpu(sb->gen);
     stored_crc = le32_to_cpu(sb->crc);
     sb->crc = 0;
     crc = crc32_le(gen, (unsigned char *)sb, DMZ_BLOCK_SIZE);
     if (crc != stored_crc) {
         dmz_dev_err(dev, "Invalid checksum (needed 0x%08x, got 0x%08x)",
                 crc, stored_crc);
         return -ENXIO;
     }
 
     sb_block = le64_to_cpu(sb->sb_block);
     if (sb_block != (u64)dsb->zone->id << zmd->zone_nr_blocks_shift ) {
         dmz_dev_err(dev, "Invalid superblock position "
                 "(is %llu expected %llu)",
                 sb_block,
                 (u64)dsb->zone->id << zmd->zone_nr_blocks_shift);
         return -EINVAL;
     }
     if (zmd->sb_version > 1) {
         uuid_t sb_uuid;
 
         import_uuid(&sb_uuid, sb->dmz_uuid);
         if (uuid_is_null(&sb_uuid)) {
             dmz_dev_err(dev, "NULL DM-Zoned uuid");
             return -ENXIO;
         } else if (uuid_is_null(&zmd->uuid)) {
             uuid_copy(&zmd->uuid, &sb_uuid);
         } else if (!uuid_equal(&zmd->uuid, &sb_uuid)) {
             dmz_dev_err(dev, "mismatching DM-Zoned uuid, "
                     "is %pUl expected %pUl",
                     &sb_uuid, &zmd->uuid);
             return -ENXIO;
         }
         if (!strlen(zmd->label))
             memcpy(zmd->label, sb->dmz_label, BDEVNAME_SIZE);
         else if (memcmp(zmd->label, sb->dmz_label, BDEVNAME_SIZE)) {
             dmz_dev_err(dev, "mismatching DM-Zoned label, "
                     "is %s expected %s",
                     sb->dmz_label, zmd->label);
             return -ENXIO;
         }
         import_uuid(&dev->uuid, sb->dev_uuid);
         if (uuid_is_null(&dev->uuid)) {
             dmz_dev_err(dev, "NULL device uuid");
             return -ENXIO;
         }
 
         if (tertiary) {
             /*
              * Generation number should be 0, but it doesn't
              * really matter if it isn't.
              */
             if (gen != 0)
                 dmz_dev_warn(dev, "Invalid generation %llu",
                         gen);
             return 0;
         }
     }
 
     nr_meta_zones = (le32_to_cpu(sb->nr_meta_blocks) + zmd->zone_nr_blocks - 1)
         >> zmd->zone_nr_blocks_shift;
     if (!nr_meta_zones ||
         (zmd->nr_devs <= 1 && nr_meta_zones >= zmd->nr_rnd_zones) ||
         (zmd->nr_devs > 1 && nr_meta_zones >= zmd->nr_cache_zones)) {
         dmz_dev_err(dev, "Invalid number of metadata blocks");
         return -ENXIO;
     }
 
     if (!le32_to_cpu(sb->nr_reserved_seq) ||
         le32_to_cpu(sb->nr_reserved_seq) >= (zmd->nr_useable_zones - nr_meta_zones)) {
         dmz_dev_err(dev, "Invalid number of reserved sequential zones");
         return -ENXIO;
     }
 
     nr_data_zones = zmd->nr_useable_zones -
         (nr_meta_zones * 2 + le32_to_cpu(sb->nr_reserved_seq));
     if (le32_to_cpu(sb->nr_chunks) > nr_data_zones) {
         dmz_dev_err(dev, "Invalid number of chunks %u / %u",
                 le32_to_cpu(sb->nr_chunks), nr_data_zones);
         return -ENXIO;
     }
 
     /* OK */
     zmd->nr_meta_blocks = le32_to_cpu(sb->nr_meta_blocks);
     zmd->nr_reserved_seq = le32_to_cpu(sb->nr_reserved_seq);
     zmd->nr_chunks = le32_to_cpu(sb->nr_chunks);
     zmd->nr_map_blocks = le32_to_cpu(sb->nr_map_blocks);
     zmd->nr_bitmap_blocks = le32_to_cpu(sb->nr_bitmap_blocks);
     zmd->nr_meta_zones = nr_meta_zones;
     zmd->nr_data_zones = nr_data_zones;
 
     return 0;
 }
 
 /*
  * Read the first or second super block from disk.
  */
 static int dmz_read_sb(struct dmz_metadata *zmd, struct dmz_sb *sb, int set)
 {
     dmz_zmd_debug(zmd, "read superblock set %d dev %pg block %llu",
               set, sb->dev->bdev, sb->block);
 
     return dmz_rdwr_block(sb->dev, REQ_OP_READ,
                   sb->block, sb->mblk->page);
 }
 
 /*
  * Determine the position of the secondary super blocks on disk.
  * This is used only if a corruption of the primary super block
  * is detected.
  */
 static int dmz_lookup_secondary_sb(struct dmz_metadata *zmd)
 {
     unsigned int zone_nr_blocks = zmd->zone_nr_blocks;
     struct dmz_mblock *mblk;
     unsigned int zone_id = zmd->sb[0].zone->id;
     int i;
 
     /* Allocate a block */
     mblk = dmz_alloc_mblock(zmd, 0);
     if (!mblk)
         return -ENOMEM;
 
     zmd->sb[1].mblk = mblk;
     zmd->sb[1].sb = mblk->data;
 
     /* Bad first super block: search for the second one */
     zmd->sb[1].block = zmd->sb[0].block + zone_nr_blocks;
     zmd->sb[1].zone = dmz_get(zmd, zone_id + 1);
     zmd->sb[1].dev = zmd->sb[0].dev;
     for (i = 1; i < zmd->nr_rnd_zones; i++) {
         if (dmz_read_sb(zmd, &zmd->sb[1], 1) != 0)
             break;
         if (le32_to_cpu(zmd->sb[1].sb->magic) == DMZ_MAGIC)
             return 0;
         zmd->sb[1].block += zone_nr_blocks;
         zmd->sb[1].zone = dmz_get(zmd, zone_id + i);
     }
 
     dmz_free_mblock(zmd, mblk);
     zmd->sb[1].mblk = NULL;
     zmd->sb[1].zone = NULL;
     zmd->sb[1].dev = NULL;
 
     return -EIO;
 }
 
 /*
  * Read a super block from disk.
  */
 static int dmz_get_sb(struct dmz_metadata *zmd, struct dmz_sb *sb, int set)
 {
     struct dmz_mblock *mblk;
     int ret;
 
     /* Allocate a block */
     mblk = dmz_alloc_mblock(zmd, 0);
     if (!mblk)
         return -ENOMEM;
 
     sb->mblk = mblk;
     sb->sb = mblk->data;
 
     /* Read super block */
     ret = dmz_read_sb(zmd, sb, set);
     if (ret) {
         dmz_free_mblock(zmd, mblk);
         sb->mblk = NULL;
         return ret;
     }
 
     return 0;
 }
 
 /*
  * Recover a metadata set.
  */
 static int dmz_recover_mblocks(struct dmz_metadata *zmd, unsigned int dst_set)
 {
     unsigned int src_set = dst_set ^ 0x1;
     struct page *page;
     int i, ret;
 
     dmz_dev_warn(zmd->sb[dst_set].dev,
              "Metadata set %u invalid: recovering", dst_set);
 
     if (dst_set == 0)
         zmd->sb[0].block = dmz_start_block(zmd, zmd->sb[0].zone);
     else
         zmd->sb[1].block = dmz_start_block(zmd, zmd->sb[1].zone);
 
     page = alloc_page(GFP_NOIO);
     if (!page)
         return -ENOMEM;
 
     /* Copy metadata blocks */
     for (i = 1; i < zmd->nr_meta_blocks; i++) {
         ret = dmz_rdwr_block(zmd->sb[src_set].dev, REQ_OP_READ,
                      zmd->sb[src_set].block + i, page);
         if (ret)
             goto out;
         ret = dmz_rdwr_block(zmd->sb[dst_set].dev, REQ_OP_WRITE,
                      zmd->sb[dst_set].block + i, page);
         if (ret)
             goto out;
     }
 
     /* Finalize with the super block */
     if (!zmd->sb[dst_set].mblk) {
         zmd->sb[dst_set].mblk = dmz_alloc_mblock(zmd, 0);
         if (!zmd->sb[dst_set].mblk) {
             ret = -ENOMEM;
             goto out;
         }
         zmd->sb[dst_set].sb = zmd->sb[dst_set].mblk->data;
     }
 
     ret = dmz_write_sb(zmd, dst_set);
 out:
     __free_pages(page, 0);
 
     return ret;
 }
 
 /*
  * Get super block from disk.
  */
 static int dmz_load_sb(struct dmz_metadata *zmd)
 {
     bool sb_good[2] = {false, false};
     u64 sb_gen[2] = {0, 0};
     int ret;
 
     if (!zmd->sb[0].zone) {
         dmz_zmd_err(zmd, "Primary super block zone not set");
         return -ENXIO;
     }
 
     /* Read and check the primary super block */
     zmd->sb[0].block = dmz_start_block(zmd, zmd->sb[0].zone);
     zmd->sb[0].dev = zmd->sb[0].zone->dev;
     ret = dmz_get_sb(zmd, &zmd->sb[0], 0);
     if (ret) {
         dmz_dev_err(zmd->sb[0].dev, "Read primary super block failed");
         return ret;
     }
 
     ret = dmz_check_sb(zmd, &zmd->sb[0], false);
 
     /* Read and check secondary super block */
     if (ret == 0) {
         sb_good[0] = true;
         if (!zmd->sb[1].zone) {
             unsigned int zone_id =
                 zmd->sb[0].zone->id + zmd->nr_meta_zones;
 
             zmd->sb[1].zone = dmz_get(zmd, zone_id);
         }
         zmd->sb[1].block = dmz_start_block(zmd, zmd->sb[1].zone);
         zmd->sb[1].dev = zmd->sb[0].dev;
         ret = dmz_get_sb(zmd, &zmd->sb[1], 1);
     } else
         ret = dmz_lookup_secondary_sb(zmd);
 
     if (ret) {
         dmz_dev_err(zmd->sb[1].dev, "Read secondary super block failed");
         return ret;
     }
 
     ret = dmz_check_sb(zmd, &zmd->sb[1], false);
     if (ret == 0)
         sb_good[1] = true;
 
     /* Use highest generation sb first */
     if (!sb_good[0] && !sb_good[1]) {
         dmz_zmd_err(zmd, "No valid super block found");
         return -EIO;
     }
 
     if (sb_good[0])
         sb_gen[0] = le64_to_cpu(zmd->sb[0].sb->gen);
     else {
         ret = dmz_recover_mblocks(zmd, 0);
         if (ret) {
             dmz_dev_err(zmd->sb[0].dev,
                     "Recovery of superblock 0 failed");
             return -EIO;
         }
     }
 
     if (sb_good[1])
         sb_gen[1] = le64_to_cpu(zmd->sb[1].sb->gen);
     else {
         ret = dmz_recover_mblocks(zmd, 1);
 
         if (ret) {
             dmz_dev_err(zmd->sb[1].dev,
                     "Recovery of superblock 1 failed");
             return -EIO;
         }
     }
 
     if (sb_gen[0] >= sb_gen[1]) {
         zmd->sb_gen = sb_gen[0];
         zmd->mblk_primary = 0;
     } else {
         zmd->sb_gen = sb_gen[1];
         zmd->mblk_primary = 1;
     }
 
     dmz_dev_debug(zmd->sb[zmd->mblk_primary].dev,
               "Using super block %u (gen %llu)",
               zmd->mblk_primary, zmd->sb_gen);
 
     if (zmd->sb_version > 1) {
         int i;
         struct dmz_sb *sb;
 
         sb = kzalloc(sizeof(struct dmz_sb), GFP_KERNEL);
         if (!sb)
             return -ENOMEM;
         for (i = 1; i < zmd->nr_devs; i++) {
             sb->block = 0;
             sb->zone = dmz_get(zmd, zmd->dev[i].zone_offset);
             sb->dev = &zmd->dev[i];
             if (!dmz_is_meta(sb->zone)) {
                 dmz_dev_err(sb->dev,
                         "Tertiary super block zone %u not marked as metadata zone",
                         sb->zone->id);
                 ret = -EINVAL;
                 goto out_kfree;
             }
             ret = dmz_get_sb(zmd, sb, i + 1);
             if (ret) {
                 dmz_dev_err(sb->dev,
                         "Read tertiary super block failed");
                 dmz_free_mblock(zmd, sb->mblk);
                 goto out_kfree;
             }
             ret = dmz_check_sb(zmd, sb, true);
             dmz_free_mblock(zmd, sb->mblk);
             if (ret == -EINVAL)
                 goto out_kfree;
         }
     out_kfree:
         kfree(sb);
     }
     return ret;
 }
 
 /*
  * Initialize a zone descriptor.
  */
 static int dmz_init_zone(struct blk_zone *blkz, unsigned int num, void *data)
 {
     struct dmz_dev *dev = data;
     struct dmz_metadata *zmd = dev->metadata;
     int idx = num + dev->zone_offset;
     struct dm_zone *zone;
 
     zone = dmz_insert(zmd, idx, dev);
     if (IS_ERR(zone))
         return PTR_ERR(zone);
 
     if (blkz->len != zmd->zone_nr_sectors) {
         if (zmd->sb_version > 1) {
             /* Ignore the eventual runt (smaller) zone */
             set_bit(DMZ_OFFLINE, &zone->flags);
             return 0;
         } else if (blkz->start + blkz->len == dev->capacity)
             return 0;
         return -ENXIO;
     }
 
     /*
      * Devices that have zones with a capacity smaller than the zone size
      * (e.g. NVMe zoned namespaces) are not supported.
      */
     if (blkz->capacity != blkz->len)
         return -ENXIO;
 
     switch (blkz->type) {
     case BLK_ZONE_TYPE_CONVENTIONAL:
         set_bit(DMZ_RND, &zone->flags);
         break;
     case BLK_ZONE_TYPE_SEQWRITE_REQ:
     case BLK_ZONE_TYPE_SEQWRITE_PREF:
         set_bit(DMZ_SEQ, &zone->flags);
         break;
     default:
         return -ENXIO;
     }
 
     if (dmz_is_rnd(zone))
         zone->wp_block = 0;
     else
         zone->wp_block = dmz_sect2blk(blkz->wp - blkz->start);
 
     if (blkz->cond == BLK_ZONE_COND_OFFLINE)
         set_bit(DMZ_OFFLINE, &zone->flags);
     else if (blkz->cond == BLK_ZONE_COND_READONLY)
         set_bit(DMZ_READ_ONLY, &zone->flags);
     else {
         zmd->nr_useable_zones++;
         if (dmz_is_rnd(zone)) {
             zmd->nr_rnd_zones++;
             if (zmd->nr_devs == 1 && !zmd->sb[0].zone) {
                 /* Primary super block zone */
                 zmd->sb[0].zone = zone;
             }
         }
         if (zmd->nr_devs > 1 && num == 0) {
             /*
              * Tertiary superblock zones are always at the
              * start of the zoned devices, so mark them
              * as metadata zone.
              */
             set_bit(DMZ_META, &zone->flags);
         }
     }
     return 0;
 }
 
 static int dmz_emulate_zones(struct dmz_metadata *zmd, struct dmz_dev *dev)
 {
     int idx;
     sector_t zone_offset = 0;
 
     for(idx = 0; idx < dev->nr_zones; idx++) {
         struct dm_zone *zone;
 
         zone = dmz_insert(zmd, idx, dev);
         if (IS_ERR(zone))
             return PTR_ERR(zone);
         set_bit(DMZ_CACHE, &zone->flags);
         zone->wp_block = 0;
         zmd->nr_cache_zones++;
         zmd->nr_useable_zones++;
         if (dev->capacity - zone_offset < zmd->zone_nr_sectors) {
             /* Disable runt zone */
             set_bit(DMZ_OFFLINE, &zone->flags);
             break;
         }
         zone_offset += zmd->zone_nr_sectors;
     }
     return 0;
 }
 
 /*
  * Free zones descriptors.
  */
 static void dmz_drop_zones(struct dmz_metadata *zmd)
 {
     int idx;
 
     for(idx = 0; idx < zmd->nr_zones; idx++) {
         struct dm_zone *zone = xa_load(&zmd->zones, idx);
 
         kfree(zone);
         xa_erase(&zmd->zones, idx);
     }
     xa_destroy(&zmd->zones);
 }
 
 /*
  * Allocate and initialize zone descriptors using the zone
  * information from disk.
  */
 static int dmz_init_zones(struct dmz_metadata *zmd)
 {
     int i, ret;
     struct dmz_dev *zoned_dev = &zmd->dev[0];
 
     /* Init */
     zmd->zone_nr_sectors = zmd->dev[0].zone_nr_sectors;
     zmd->zone_nr_sectors_shift = ilog2(zmd->zone_nr_sectors);
     zmd->zone_nr_blocks = dmz_sect2blk(zmd->zone_nr_sectors);
     zmd->zone_nr_blocks_shift = ilog2(zmd->zone_nr_blocks);
     zmd->zone_bitmap_size = zmd->zone_nr_blocks >> 3;
     zmd->zone_nr_bitmap_blocks =
         max_t(sector_t, 1, zmd->zone_bitmap_size >> DMZ_BLOCK_SHIFT);
     zmd->zone_bits_per_mblk = min_t(sector_t, zmd->zone_nr_blocks,
                     DMZ_BLOCK_SIZE_BITS);
 
     /* Allocate zone array */
     zmd->nr_zones = 0;
     for (i = 0; i < zmd->nr_devs; i++) {
         struct dmz_dev *dev = &zmd->dev[i];
 
         dev->metadata = zmd;
         zmd->nr_zones += dev->nr_zones;
 
         atomic_set(&dev->unmap_nr_rnd, 0);
         INIT_LIST_HEAD(&dev->unmap_rnd_list);
         INIT_LIST_HEAD(&dev->map_rnd_list);
 
         atomic_set(&dev->unmap_nr_seq, 0);
         INIT_LIST_HEAD(&dev->unmap_seq_list);
         INIT_LIST_HEAD(&dev->map_seq_list);
     }
 
     if (!zmd->nr_zones) {
         DMERR("(%s): No zones found", zmd->devname);
         return -ENXIO;
     }
     xa_init(&zmd->zones);
 
     DMDEBUG("(%s): Using %zu B for zone information",
         zmd->devname, sizeof(struct dm_zone) * zmd->nr_zones);
 
     if (zmd->nr_devs > 1) {
         ret = dmz_emulate_zones(zmd, &zmd->dev[0]);
         if (ret < 0) {
             DMDEBUG("(%s): Failed to emulate zones, error %d",
                 zmd->devname, ret);
             dmz_drop_zones(zmd);
             return ret;
         }
 
         /*
          * Primary superblock zone is always at zone 0 when multiple
          * drives are present.
          */
         zmd->sb[0].zone = dmz_get(zmd, 0);
 
         for (i = 1; i < zmd->nr_devs; i++) {
             zoned_dev = &zmd->dev[i];
 
             ret = blkdev_report_zones(zoned_dev->bdev, 0,
                           BLK_ALL_ZONES,
                           dmz_init_zone, zoned_dev);
             if (ret < 0) {
                 DMDEBUG("(%s): Failed to report zones, error %d",
                     zmd->devname, ret);
                 dmz_drop_zones(zmd);
                 return ret;
             }
         }
         return 0;
     }
 
     /*
      * Get zone information and initialize zone descriptors.  At the same
      * time, determine where the super block should be: first block of the
      * first randomly writable zone.
      */
     ret = blkdev_report_zones(zoned_dev->bdev, 0, BLK_ALL_ZONES,
                   dmz_init_zone, zoned_dev);
     if (ret < 0) {
         DMDEBUG("(%s): Failed to report zones, error %d",
             zmd->devname, ret);
         dmz_drop_zones(zmd);
         return ret;
     }
 
     return 0;
 }
 
 static int dmz_update_zone_cb(struct blk_zone *blkz, unsigned int idx,
                   void *data)
 {
     struct dm_zone *zone = data;
 
     clear_bit(DMZ_OFFLINE, &zone->flags);
     clear_bit(DMZ_READ_ONLY, &zone->flags);
     if (blkz->cond == BLK_ZONE_COND_OFFLINE)
         set_bit(DMZ_OFFLINE, &zone->flags);
     else if (blkz->cond == BLK_ZONE_COND_READONLY)
         set_bit(DMZ_READ_ONLY, &zone->flags);
 
     if (dmz_is_seq(zone))
         zone->wp_block = dmz_sect2blk(blkz->wp - blkz->start);
     else
         zone->wp_block = 0;
     return 0;
 }
 
 /*
  * Update a zone information.
  */
 static int dmz_update_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
     struct dmz_dev *dev = zone->dev;
     unsigned int noio_flag;
     int ret;
 
     if (dev->flags & DMZ_BDEV_REGULAR)
         return 0;
 
     /*
      * Get zone information from disk. Since blkdev_report_zones() uses
      * GFP_KERNEL by default for memory allocations, set the per-task
      * PF_MEMALLOC_NOIO flag so that all allocations are done as if
      * GFP_NOIO was specified.
      */
     noio_flag = memalloc_noio_save();
     ret = blkdev_report_zones(dev->bdev, dmz_start_sect(zmd, zone), 1,
                   dmz_update_zone_cb, zone);
     memalloc_noio_restore(noio_flag);
 
     if (ret == 0)
         ret = -EIO;
     if (ret < 0) {
         dmz_dev_err(dev, "Get zone %u report failed",
                 zone->id);
         dmz_check_bdev(dev);
         return ret;
     }
 
     return 0;
 }
 
 /*
  * Check a zone write pointer position when the zone is marked
  * with the sequential write error flag.
  */
 static int dmz_handle_seq_write_err(struct dmz_metadata *zmd,
                     struct dm_zone *zone)
 {
     struct dmz_dev *dev = zone->dev;
     unsigned int wp = 0;
     int ret;
 
     wp = zone->wp_block;
     ret = dmz_update_zone(zmd, zone);
     if (ret)
         return ret;
 
     dmz_dev_warn(dev, "Processing zone %u write error (zone wp %u/%u)",
              zone->id, zone->wp_block, wp);
 
     if (zone->wp_block < wp) {
         dmz_invalidate_blocks(zmd, zone, zone->wp_block,
                       wp - zone->wp_block);
     }
 
     return 0;
 }
 
 /*
  * Reset a zone write pointer.
  */
 static int dmz_reset_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
     int ret;
 
     /*
      * Ignore offline zones, read only zones,
      * and conventional zones.
      */
     if (dmz_is_offline(zone) ||
         dmz_is_readonly(zone) ||
         dmz_is_rnd(zone))
         return 0;
 
     if (!dmz_is_empty(zone) || dmz_seq_write_err(zone)) {
         struct dmz_dev *dev = zone->dev;
 
         ret = blkdev_zone_mgmt(dev->bdev, REQ_OP_ZONE_RESET,
                        dmz_start_sect(zmd, zone),
                        zmd->zone_nr_sectors, GFP_NOIO);
         if (ret) {
             dmz_dev_err(dev, "Reset zone %u failed %d",
                     zone->id, ret);
             return ret;
         }
     }
 
     /* Clear write error bit and rewind write pointer position */
     clear_bit(DMZ_SEQ_WRITE_ERR, &zone->flags);
     zone->wp_block = 0;
 
     return 0;
 }
 
 static void dmz_get_zone_weight(struct dmz_metadata *zmd, struct dm_zone *zone);
 
 /*
  * Initialize chunk mapping.
  */
 static int dmz_load_mapping(struct dmz_metadata *zmd)
 {
     struct dm_zone *dzone, *bzone;
     struct dmz_mblock *dmap_mblk = NULL;
     struct dmz_map *dmap;
     unsigned int i = 0, e = 0, chunk = 0;
     unsigned int dzone_id;
     unsigned int bzone_id;
 
     /* Metadata block array for the chunk mapping table */
     zmd->map_mblk = kcalloc(zmd->nr_map_blocks,
                 sizeof(struct dmz_mblk *), GFP_KERNEL);
     if (!zmd->map_mblk)
         return -ENOMEM;
 
     /* Get chunk mapping table blocks and initialize zone mapping */
     while (chunk < zmd->nr_chunks) {
         if (!dmap_mblk) {
             /* Get mapping block */
             dmap_mblk = dmz_get_mblock(zmd, i + 1);
             if (IS_ERR(dmap_mblk))
                 return PTR_ERR(dmap_mblk);
             zmd->map_mblk[i] = dmap_mblk;
             dmap = (struct dmz_map *) dmap_mblk->data;
             i++;
             e = 0;
         }
 
         /* Check data zone */
         dzone_id = le32_to_cpu(dmap[e].dzone_id);
         if (dzone_id == DMZ_MAP_UNMAPPED)
             goto next;
 
         if (dzone_id >= zmd->nr_zones) {
             dmz_zmd_err(zmd, "Chunk %u mapping: invalid data zone ID %u",
                     chunk, dzone_id);
             return -EIO;
         }
 
         dzone = dmz_get(zmd, dzone_id);
         if (!dzone) {
             dmz_zmd_err(zmd, "Chunk %u mapping: data zone %u not present",
                     chunk, dzone_id);
             return -EIO;
         }
         set_bit(DMZ_DATA, &dzone->flags);
         dzone->chunk = chunk;
         dmz_get_zone_weight(zmd, dzone);
 
         if (dmz_is_cache(dzone))
             list_add_tail(&dzone->link, &zmd->map_cache_list);
         else if (dmz_is_rnd(dzone))
             list_add_tail(&dzone->link, &dzone->dev->map_rnd_list);
         else
             list_add_tail(&dzone->link, &dzone->dev->map_seq_list);
 
         /* Check buffer zone */
         bzone_id = le32_to_cpu(dmap[e].bzone_id);
         if (bzone_id == DMZ_MAP_UNMAPPED)
             goto next;
 
         if (bzone_id >= zmd->nr_zones) {
             dmz_zmd_err(zmd, "Chunk %u mapping: invalid buffer zone ID %u",
                     chunk, bzone_id);
             return -EIO;
         }
 
         bzone = dmz_get(zmd, bzone_id);
         if (!bzone) {
             dmz_zmd_err(zmd, "Chunk %u mapping: buffer zone %u not present",
                     chunk, bzone_id);
             return -EIO;
         }
         if (!dmz_is_rnd(bzone) && !dmz_is_cache(bzone)) {
             dmz_zmd_err(zmd, "Chunk %u mapping: invalid buffer zone %u",
                     chunk, bzone_id);
             return -EIO;
         }
 
         set_bit(DMZ_DATA, &bzone->flags);
         set_bit(DMZ_BUF, &bzone->flags);
         bzone->chunk = chunk;
         bzone->bzone = dzone;
         dzone->bzone = bzone;
         dmz_get_zone_weight(zmd, bzone);
         if (dmz_is_cache(bzone))
             list_add_tail(&bzone->link, &zmd->map_cache_list);
         else
             list_add_tail(&bzone->link, &bzone->dev->map_rnd_list);
 next:
         chunk++;
         e++;
         if (e >= DMZ_MAP_ENTRIES)
             dmap_mblk = NULL;
     }
 
     /*
      * At this point, only meta zones and mapped data zones were
      * fully initialized. All remaining zones are unmapped data
      * zones. Finish initializing those here.
      */
     for (i = 0; i < zmd->nr_zones; i++) {
         dzone = dmz_get(zmd, i);
         if (!dzone)
             continue;
         if (dmz_is_meta(dzone))
             continue;
         if (dmz_is_offline(dzone))
             continue;
 
         if (dmz_is_cache(dzone))
             zmd->nr_cache++;
         else if (dmz_is_rnd(dzone))
             dzone->dev->nr_rnd++;
         else
             dzone->dev->nr_seq++;
 
         if (dmz_is_data(dzone)) {
             /* Already initialized */
             continue;
         }
 
         /* Unmapped data zone */
         set_bit(DMZ_DATA, &dzone->flags);
         dzone->chunk = DMZ_MAP_UNMAPPED;
         if (dmz_is_cache(dzone)) {
             list_add_tail(&dzone->link, &zmd->unmap_cache_list);
             atomic_inc(&zmd->unmap_nr_cache);
         } else if (dmz_is_rnd(dzone)) {
             list_add_tail(&dzone->link,
                       &dzone->dev->unmap_rnd_list);
             atomic_inc(&dzone->dev->unmap_nr_rnd);
         } else if (atomic_read(&zmd->nr_reserved_seq_zones) < zmd->nr_reserved_seq) {
             list_add_tail(&dzone->link, &zmd->reserved_seq_zones_list);
             set_bit(DMZ_RESERVED, &dzone->flags);
             atomic_inc(&zmd->nr_reserved_seq_zones);
             dzone->dev->nr_seq--;
         } else {
             list_add_tail(&dzone->link,
                       &dzone->dev->unmap_seq_list);
             atomic_inc(&dzone->dev->unmap_nr_seq);
         }
     }
 
     return 0;
 }
 
 /*
  * Set a data chunk mapping.
  */
 static void dmz_set_chunk_mapping(struct dmz_metadata *zmd, unsigned int chunk,
                   unsigned int dzone_id, unsigned int bzone_id)
 {
     struct dmz_mblock *dmap_mblk = zmd->map_mblk[chunk >> DMZ_MAP_ENTRIES_SHIFT];
     struct dmz_map *dmap = (struct dmz_map *) dmap_mblk->data;
     int map_idx = chunk & DMZ_MAP_ENTRIES_MASK;
 
     dmap[map_idx].dzone_id = cpu_to_le32(dzone_id);
     dmap[map_idx].bzone_id = cpu_to_le32(bzone_id);
     dmz_dirty_mblock(zmd, dmap_mblk);
 }
 
 /*
  * The list of mapped zones is maintained in LRU order.
  * This rotates a zone at the end of its map list.
  */
 static void __dmz_lru_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
     if (list_empty(&zone->link))
         return;
 
     list_del_init(&zone->link);
     if (dmz_is_seq(zone)) {
         /* LRU rotate sequential zone */
         list_add_tail(&zone->link, &zone->dev->map_seq_list);
     } else if (dmz_is_cache(zone)) {
         /* LRU rotate cache zone */
         list_add_tail(&zone->link, &zmd->map_cache_list);
     } else {
         /* LRU rotate random zone */
         list_add_tail(&zone->link, &zone->dev->map_rnd_list);
     }
 }
 
 /*
  * The list of mapped random zones is maintained
  * in LRU order. This rotates a zone at the end of the list.
  */
 static void dmz_lru_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
     __dmz_lru_zone(zmd, zone);
     if (zone->bzone)
         __dmz_lru_zone(zmd, zone->bzone);
 }
 
 /*
  * Wait for any zone to be freed.
  */
 static void dmz_wait_for_free_zones(struct dmz_metadata *zmd)
 {
     DEFINE_WAIT(wait);
 
     prepare_to_wait(&zmd->free_wq, &wait, TASK_UNINTERRUPTIBLE);
     dmz_unlock_map(zmd);
     dmz_unlock_metadata(zmd);
 
     io_schedule_timeout(HZ);
 
     dmz_lock_metadata(zmd);
     dmz_lock_map(zmd);
     finish_wait(&zmd->free_wq, &wait);
 }
 
 /*
  * Lock a zone for reclaim (set the zone RECLAIM bit).
  * Returns false if the zone cannot be locked or if it is already locked
  * and 1 otherwise.
  */
 int dmz_lock_zone_reclaim(struct dm_zone *zone)
 {
     /* Active zones cannot be reclaimed */
     if (dmz_is_active(zone))
         return 0;
 
     return !test_and_set_bit(DMZ_RECLAIM, &zone->flags);
 }
 
 /*
  * Clear a zone reclaim flag.
  */
 void dmz_unlock_zone_reclaim(struct dm_zone *zone)
 {
     WARN_ON(dmz_is_active(zone));
     WARN_ON(!dmz_in_reclaim(zone));
 
     clear_bit_unlock(DMZ_RECLAIM, &zone->flags);
     smp_mb__after_atomic();
     wake_up_bit(&zone->flags, DMZ_RECLAIM);
 }
 
 /*
  * Wait for a zone reclaim to complete.
  */
 static void dmz_wait_for_reclaim(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
     dmz_unlock_map(zmd);
     dmz_unlock_metadata(zmd);
     set_bit(DMZ_RECLAIM_TERMINATE, &zone->flags);
     wait_on_bit_timeout(&zone->flags, DMZ_RECLAIM, TASK_UNINTERRUPTIBLE, HZ);
     clear_bit(DMZ_RECLAIM_TERMINATE, &zone->flags);
     dmz_lock_metadata(zmd);
     dmz_lock_map(zmd);
 }
 
 /*
  * Select a cache or random write zone for reclaim.
  */
 static struct dm_zone *dmz_get_rnd_zone_for_reclaim(struct dmz_metadata *zmd,
                             unsigned int idx, bool idle)
 {
     struct dm_zone *dzone = NULL;
     struct dm_zone *zone, *maxw_z = NULL;
     struct list_head *zone_list;
 
     /* If we have cache zones select from the cache zone list */
     if (zmd->nr_cache) {
         zone_list = &zmd->map_cache_list;
         /* Try to relaim random zones, too, when idle */
         if (idle && list_empty(zone_list))
             zone_list = &zmd->dev[idx].map_rnd_list;
     } else
         zone_list = &zmd->dev[idx].map_rnd_list;
 
     /*
      * Find the buffer zone with the heaviest weight or the first (oldest)
      * data zone that can be reclaimed.
      */
     list_for_each_entry(zone, zone_list, link) {
         if (dmz_is_buf(zone)) {
             dzone = zone->bzone;
             if (dmz_is_rnd(dzone) && dzone->dev->dev_idx != idx)
                 continue;
             if (!maxw_z || maxw_z->weight < dzone->weight)
                 maxw_z = dzone;
         } else {
             dzone = zone;
             if (dmz_lock_zone_reclaim(dzone))
                 return dzone;
         }
     }
 
     if (maxw_z && dmz_lock_zone_reclaim(maxw_z))
         return maxw_z;
 
     /*
      * If we come here, none of the zones inspected could be locked for
      * reclaim. Try again, being more aggressive, that is, find the
      * first zone that can be reclaimed regardless of its weitght.
      */
     list_for_each_entry(zone, zone_list, link) {
         if (dmz_is_buf(zone)) {
             dzone = zone->bzone;
             if (dmz_is_rnd(dzone) && dzone->dev->dev_idx != idx)
                 continue;
         } else
             dzone = zone;
         if (dmz_lock_zone_reclaim(dzone))
             return dzone;
     }
 
     return NULL;
 }
 
 /*
  * Select a buffered sequential zone for reclaim.
  */
 static struct dm_zone *dmz_get_seq_zone_for_reclaim(struct dmz_metadata *zmd,
                             unsigned int idx)
 {
     struct dm_zone *zone;
 
     list_for_each_entry(zone, &zmd->dev[idx].map_seq_list, link) {
         if (!zone->bzone)
             continue;
         if (dmz_lock_zone_reclaim(zone))
             return zone;
     }
 
     return NULL;
 }
 
 /*
  * Select a zone for reclaim.
  */
 struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd,
                      unsigned int dev_idx, bool idle)
 {
     struct dm_zone *zone = NULL;
 
     /*
      * Search for a zone candidate to reclaim: 2 cases are possible.
      * (1) There is no free sequential zones. Then a random data zone
      *     cannot be reclaimed. So choose a sequential zone to reclaim so
      *     that afterward a random zone can be reclaimed.
      * (2) At least one free sequential zone is available, then choose
      *     the oldest random zone (data or buffer) that can be locked.
      */
     dmz_lock_map(zmd);
     if (list_empty(&zmd->reserved_seq_zones_list))
         zone = dmz_get_seq_zone_for_reclaim(zmd, dev_idx);
     if (!zone)
         zone = dmz_get_rnd_zone_for_reclaim(zmd, dev_idx, idle);
     dmz_unlock_map(zmd);
 
     return zone;
 }
 
 /*
  * Get the zone mapping a chunk, if the chunk is mapped already.
  * If no mapping exist and the operation is WRITE, a zone is
  * allocated and used to map the chunk.
  * The zone returned will be set to the active state.
  */
 struct dm_zone *dmz_get_chunk_mapping(struct dmz_metadata *zmd,
                       unsigned int chunk, enum req_op op)
 {
     struct dmz_mblock *dmap_mblk = zmd->map_mblk[chunk >> DMZ_MAP_ENTRIES_SHIFT];
     struct dmz_map *dmap = (struct dmz_map *) dmap_mblk->data;
     int dmap_idx = chunk & DMZ_MAP_ENTRIES_MASK;
     unsigned int dzone_id;
     struct dm_zone *dzone = NULL;
     int ret = 0;
     int alloc_flags = zmd->nr_cache ? DMZ_ALLOC_CACHE : DMZ_ALLOC_RND;
 
     dmz_lock_map(zmd);
 again:
     /* Get the chunk mapping */
     dzone_id = le32_to_cpu(dmap[dmap_idx].dzone_id);
     if (dzone_id == DMZ_MAP_UNMAPPED) {
         /*
          * Read or discard in unmapped chunks are fine. But for
          * writes, we need a mapping, so get one.
          */
         if (op != REQ_OP_WRITE)
             goto out;
 
         /* Allocate a random zone */
         dzone = dmz_alloc_zone(zmd, 0, alloc_flags);
         if (!dzone) {
             if (dmz_dev_is_dying(zmd)) {
                 dzone = ERR_PTR(-EIO);
                 goto out;
             }
             dmz_wait_for_free_zones(zmd);
             goto again;
         }
 
         dmz_map_zone(zmd, dzone, chunk);
 
     } else {
         /* The chunk is already mapped: get the mapping zone */
         dzone = dmz_get(zmd, dzone_id);
         if (!dzone) {
             dzone = ERR_PTR(-EIO);
             goto out;
         }
         if (dzone->chunk != chunk) {
             dzone = ERR_PTR(-EIO);
             goto out;
         }
 
         /* Repair write pointer if the sequential dzone has error */
         if (dmz_seq_write_err(dzone)) {
             ret = dmz_handle_seq_write_err(zmd, dzone);
             if (ret) {
                 dzone = ERR_PTR(-EIO);
                 goto out;
             }
             clear_bit(DMZ_SEQ_WRITE_ERR, &dzone->flags);
         }
     }
 
     /*
      * If the zone is being reclaimed, the chunk mapping may change
      * to a different zone. So wait for reclaim and retry. Otherwise,
      * activate the zone (this will prevent reclaim from touching it).
      */
     if (dmz_in_reclaim(dzone)) {
         dmz_wait_for_reclaim(zmd, dzone);
         goto again;
     }
     dmz_activate_zone(dzone);
     dmz_lru_zone(zmd, dzone);
 out:
     dmz_unlock_map(zmd);
 
     return dzone;
 }
 
 /*
  * Write and discard change the block validity of data zones and their buffer
  * zones. Check here that valid blocks are still present. If all blocks are
  * invalid, the zones can be unmapped on the fly without waiting for reclaim
  * to do it.
  */
 void dmz_put_chunk_mapping(struct dmz_metadata *zmd, struct dm_zone *dzone)
 {
     struct dm_zone *bzone;
 
     dmz_lock_map(zmd);
 
     bzone = dzone->bzone;
     if (bzone) {
         if (dmz_weight(bzone))
             dmz_lru_zone(zmd, bzone);
         else {
             /* Empty buffer zone: reclaim it */
             dmz_unmap_zone(zmd, bzone);
             dmz_free_zone(zmd, bzone);
             bzone = NULL;
         }
     }
 
     /* Deactivate the data zone */
     dmz_deactivate_zone(dzone);
     if (dmz_is_active(dzone) || bzone || dmz_weight(dzone))
         dmz_lru_zone(zmd, dzone);
     else {
         /* Unbuffered inactive empty data zone: reclaim it */
         dmz_unmap_zone(zmd, dzone);
         dmz_free_zone(zmd, dzone);
     }
 
     dmz_unlock_map(zmd);
 }
 
 /*
  * Allocate and map a random zone to buffer a chunk
  * already mapped to a sequential zone.
  */
 struct dm_zone *dmz_get_chunk_buffer(struct dmz_metadata *zmd,
                      struct dm_zone *dzone)
 {
     struct dm_zone *bzone;
     int alloc_flags = zmd->nr_cache ? DMZ_ALLOC_CACHE : DMZ_ALLOC_RND;
 
     dmz_lock_map(zmd);
 again:
     bzone = dzone->bzone;
     if (bzone)
         goto out;
 
     /* Allocate a random zone */
     bzone = dmz_alloc_zone(zmd, 0, alloc_flags);
     if (!bzone) {
         if (dmz_dev_is_dying(zmd)) {
             bzone = ERR_PTR(-EIO);
             goto out;
         }
         dmz_wait_for_free_zones(zmd);
         goto again;
     }
 
     /* Update the chunk mapping */
     dmz_set_chunk_mapping(zmd, dzone->chunk, dzone->id, bzone->id);
 
     set_bit(DMZ_BUF, &bzone->flags);
     bzone->chunk = dzone->chunk;
     bzone->bzone = dzone;
     dzone->bzone = bzone;
     if (dmz_is_cache(bzone))
         list_add_tail(&bzone->link, &zmd->map_cache_list);
     else
         list_add_tail(&bzone->link, &bzone->dev->map_rnd_list);
 out:
     dmz_unlock_map(zmd);
 
     return bzone;
 }
 
 /*
  * Get an unmapped (free) zone.
  * This must be called with the mapping lock held.
  */
 struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned int dev_idx,
                    unsigned long flags)
 {
     struct list_head *list;
     struct dm_zone *zone;
     int i;
 
     /* Schedule reclaim to ensure free zones are available */
     if (!(flags & DMZ_ALLOC_RECLAIM)) {
         for (i = 0; i < zmd->nr_devs; i++)
             dmz_schedule_reclaim(zmd->dev[i].reclaim);
     }
 
     i = 0;
 again:
     if (flags & DMZ_ALLOC_CACHE)
         list = &zmd->unmap_cache_list;
     else if (flags & DMZ_ALLOC_RND)
         list = &zmd->dev[dev_idx].unmap_rnd_list;
     else
         list = &zmd->dev[dev_idx].unmap_seq_list;
 
     if (list_empty(list)) {
         /*
          * No free zone: return NULL if this is for not reclaim.
          */
         if (!(flags & DMZ_ALLOC_RECLAIM))
             return NULL;
         /*
          * Try to allocate from other devices
          */
         if (i < zmd->nr_devs) {
             dev_idx = (dev_idx + 1) % zmd->nr_devs;
             i++;
             goto again;
         }
 
         /*
          * Fallback to the reserved sequential zones
          */
         zone = list_first_entry_or_null(&zmd->reserved_seq_zones_list,
                         struct dm_zone, link);
         if (zone) {
             list_del_init(&zone->link);
             atomic_dec(&zmd->nr_reserved_seq_zones);
         }
         return zone;
     }
 
     zone = list_first_entry(list, struct dm_zone, link);
     list_del_init(&zone->link);
 
     if (dmz_is_cache(zone))
         atomic_dec(&zmd->unmap_nr_cache);
     else if (dmz_is_rnd(zone))
         atomic_dec(&zone->dev->unmap_nr_rnd);
     else
         atomic_dec(&zone->dev->unmap_nr_seq);
 
     if (dmz_is_offline(zone)) {
         dmz_zmd_warn(zmd, "Zone %u is offline", zone->id);
         zone = NULL;
         goto again;
     }
     if (dmz_is_meta(zone)) {
         dmz_zmd_warn(zmd, "Zone %u has metadata", zone->id);
         zone = NULL;
         goto again;
     }
     return zone;
 }
 
 /*
  * Free a zone.
  * This must be called with the mapping lock held.
  */
 void dmz_free_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
     /* If this is a sequential zone, reset it */
     if (dmz_is_seq(zone))
         dmz_reset_zone(zmd, zone);
 
     /* Return the zone to its type unmap list */
     if (dmz_is_cache(zone)) {
         list_add_tail(&zone->link, &zmd->unmap_cache_list);
         atomic_inc(&zmd->unmap_nr_cache);
     } else if (dmz_is_rnd(zone)) {
         list_add_tail(&zone->link, &zone->dev->unmap_rnd_list);
         atomic_inc(&zone->dev->unmap_nr_rnd);
     } else if (dmz_is_reserved(zone)) {
         list_add_tail(&zone->link, &zmd->reserved_seq_zones_list);
         atomic_inc(&zmd->nr_reserved_seq_zones);
     } else {
         list_add_tail(&zone->link, &zone->dev->unmap_seq_list);
         atomic_inc(&zone->dev->unmap_nr_seq);
     }
 
     wake_up_all(&zmd->free_wq);
 }
 
 /*
  * Map a chunk to a zone.
  * This must be called with the mapping lock held.
  */
 void dmz_map_zone(struct dmz_metadata *zmd, struct dm_zone *dzone,
           unsigned int chunk)
 {
     /* Set the chunk mapping */
     dmz_set_chunk_mapping(zmd, chunk, dzone->id,
                   DMZ_MAP_UNMAPPED);
     dzone->chunk = chunk;
     if (dmz_is_cache(dzone))
         list_add_tail(&dzone->link, &zmd->map_cache_list);
     else if (dmz_is_rnd(dzone))
         list_add_tail(&dzone->link, &dzone->dev->map_rnd_list);
     else
         list_add_tail(&dzone->link, &dzone->dev->map_seq_list);
 }
 
 /*
  * Unmap a zone.
  * This must be called with the mapping lock held.
  */
 void dmz_unmap_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
     unsigned int chunk = zone->chunk;
     unsigned int dzone_id;
 
     if (chunk == DMZ_MAP_UNMAPPED) {
         /* Already unmapped */
         return;
     }
 
     if (test_and_clear_bit(DMZ_BUF, &zone->flags)) {
         /*
          * Unmapping the chunk buffer zone: clear only
          * the chunk buffer mapping
          */
         dzone_id = zone->bzone->id;
         zone->bzone->bzone = NULL;
         zone->bzone = NULL;
 
     } else {
         /*
          * Unmapping the chunk data zone: the zone must
          * not be buffered.
          */
         if (WARN_ON(zone->bzone)) {
             zone->bzone->bzone = NULL;
             zone->bzone = NULL;
         }
         dzone_id = DMZ_MAP_UNMAPPED;
     }
 
     dmz_set_chunk_mapping(zmd, chunk, dzone_id, DMZ_MAP_UNMAPPED);
 
     zone->chunk = DMZ_MAP_UNMAPPED;
     list_del_init(&zone->link);
 }
 
 /*
  * Set @nr_bits bits in @bitmap starting from @bit.
  * Return the number of bits changed from 0 to 1.
  */
 static unsigned int dmz_set_bits(unsigned long *bitmap,
                  unsigned int bit, unsigned int nr_bits)
 {
     unsigned long *addr;
     unsigned int end = bit + nr_bits;
     unsigned int n = 0;
 
     while (bit < end) {
         if (((bit & (BITS_PER_LONG - 1)) == 0) &&
             ((end - bit) >= BITS_PER_LONG)) {
             /* Try to set the whole word at once */
             addr = bitmap + BIT_WORD(bit);
             if (*addr == 0) {
                 *addr = ULONG_MAX;
                 n += BITS_PER_LONG;
                 bit += BITS_PER_LONG;
                 continue;
             }
         }
 
         if (!test_and_set_bit(bit, bitmap))
             n++;
         bit++;
     }
 
     return n;
 }
 
 /*
  * Get the bitmap block storing the bit for chunk_block in zone.
  */
 static struct dmz_mblock *dmz_get_bitmap(struct dmz_metadata *zmd,
                      struct dm_zone *zone,
                      sector_t chunk_block)
 {
     sector_t bitmap_block = 1 + zmd->nr_map_blocks +
         (sector_t)(zone->id * zmd->zone_nr_bitmap_blocks) +
         (chunk_block >> DMZ_BLOCK_SHIFT_BITS);
 
     return dmz_get_mblock(zmd, bitmap_block);
 }
 
 /*
  * Copy the valid blocks bitmap of from_zone to the bitmap of to_zone.
  */
 int dmz_copy_valid_blocks(struct dmz_metadata *zmd, struct dm_zone *from_zone,
               struct dm_zone *to_zone)
 {
     struct dmz_mblock *from_mblk, *to_mblk;
     sector_t chunk_block = 0;
 
     /* Get the zones bitmap blocks */
     while (chunk_block < zmd->zone_nr_blocks) {
         from_mblk = dmz_get_bitmap(zmd, from_zone, chunk_block);
         if (IS_ERR(from_mblk))
             return PTR_ERR(from_mblk);
         to_mblk = dmz_get_bitmap(zmd, to_zone, chunk_block);
         if (IS_ERR(to_mblk)) {
             dmz_release_mblock(zmd, from_mblk);
             return PTR_ERR(to_mblk);
         }
 
         memcpy(to_mblk->data, from_mblk->data, DMZ_BLOCK_SIZE);
         dmz_dirty_mblock(zmd, to_mblk);
 
         dmz_release_mblock(zmd, to_mblk);
         dmz_release_mblock(zmd, from_mblk);
 
         chunk_block += zmd->zone_bits_per_mblk;
     }
 
     to_zone->weight = from_zone->weight;
 
     return 0;
 }
 
 /*
  * Merge the valid blocks bitmap of from_zone into the bitmap of to_zone,
  * starting from chunk_block.
  */
 int dmz_merge_valid_blocks(struct dmz_metadata *zmd, struct dm_zone *from_zone,
                struct dm_zone *to_zone, sector_t chunk_block)
 {
     unsigned int nr_blocks;
     int ret;
 
     /* Get the zones bitmap blocks */
     while (chunk_block < zmd->zone_nr_blocks) {
         /* Get a valid region from the source zone */
         ret = dmz_first_valid_block(zmd, from_zone, &chunk_block);
         if (ret <= 0)
             return ret;
 
         nr_blocks = ret;
         ret = dmz_validate_blocks(zmd, to_zone, chunk_block, nr_blocks);
         if (ret)
             return ret;
 
         chunk_block += nr_blocks;
     }
 
     return 0;
 }
 
 /*
  * Validate all the blocks in the range [block..block+nr_blocks-1].
  */
 int dmz_validate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
             sector_t chunk_block, unsigned int nr_blocks)
 {
     unsigned int count, bit, nr_bits;
     unsigned int zone_nr_blocks = zmd->zone_nr_blocks;
     struct dmz_mblock *mblk;
     unsigned int n = 0;
 
     dmz_zmd_debug(zmd, "=> VALIDATE zone %u, block %llu, %u blocks",
               zone->id, (unsigned long long)chunk_block,
               nr_blocks);
 
     WARN_ON(chunk_block + nr_blocks > zone_nr_blocks);
 
     while (nr_blocks) {
         /* Get bitmap block */
         mblk = dmz_get_bitmap(zmd, zone, chunk_block);
         if (IS_ERR(mblk))
             return PTR_ERR(mblk);
 
         /* Set bits */
         bit = chunk_block & DMZ_BLOCK_MASK_BITS;
         nr_bits = min(nr_blocks, zmd->zone_bits_per_mblk - bit);
 
         count = dmz_set_bits((unsigned long *)mblk->data, bit, nr_bits);
         if (count) {
             dmz_dirty_mblock(zmd, mblk);
             n += count;
         }
         dmz_release_mblock(zmd, mblk);
 
         nr_blocks -= nr_bits;
         chunk_block += nr_bits;
     }
 
     if (likely(zone->weight + n <= zone_nr_blocks))
         zone->weight += n;
     else {
         dmz_zmd_warn(zmd, "Zone %u: weight %u should be <= %u",
                  zone->id, zone->weight,
                  zone_nr_blocks - n);
         zone->weight = zone_nr_blocks;
     }
 
     return 0;
 }
 
 /*
  * Clear nr_bits bits in bitmap starting from bit.
  * Return the number of bits cleared.
  */
 static int dmz_clear_bits(unsigned long *bitmap, int bit, int nr_bits)
 {
     unsigned long *addr;
     int end = bit + nr_bits;
     int n = 0;
 
     while (bit < end) {
         if (((bit & (BITS_PER_LONG - 1)) == 0) &&
             ((end - bit) >= BITS_PER_LONG)) {
             /* Try to clear whole word at once */
             addr = bitmap + BIT_WORD(bit);
             if (*addr == ULONG_MAX) {
                 *addr = 0;
                 n += BITS_PER_LONG;
                 bit += BITS_PER_LONG;
                 continue;
             }
         }
 
         if (test_and_clear_bit(bit, bitmap))
             n++;
         bit++;
     }
 
     return n;
 }
 
 /*
  * Invalidate all the blocks in the range [block..block+nr_blocks-1].
  */
 int dmz_invalidate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
               sector_t chunk_block, unsigned int nr_blocks)
 {
     unsigned int count, bit, nr_bits;
     struct dmz_mblock *mblk;
     unsigned int n = 0;
 
     dmz_zmd_debug(zmd, "=> INVALIDATE zone %u, block %llu, %u blocks",
               zone->id, (u64)chunk_block, nr_blocks);
 
     WARN_ON(chunk_block + nr_blocks > zmd->zone_nr_blocks);
 
     while (nr_blocks) {
         /* Get bitmap block */
         mblk = dmz_get_bitmap(zmd, zone, chunk_block);
         if (IS_ERR(mblk))
             return PTR_ERR(mblk);
 
         /* Clear bits */
         bit = chunk_block & DMZ_BLOCK_MASK_BITS;
         nr_bits = min(nr_blocks, zmd->zone_bits_per_mblk - bit);
 
         count = dmz_clear_bits((unsigned long *)mblk->data,
                        bit, nr_bits);
         if (count) {
             dmz_dirty_mblock(zmd, mblk);
             n += count;
         }
         dmz_release_mblock(zmd, mblk);
 
         nr_blocks -= nr_bits;
         chunk_block += nr_bits;
     }
 
     if (zone->weight >= n)
         zone->weight -= n;
     else {
         dmz_zmd_warn(zmd, "Zone %u: weight %u should be >= %u",
                  zone->id, zone->weight, n);
         zone->weight = 0;
     }
 
     return 0;
 }
 
 /*
  * Get a block bit value.
  */
 static int dmz_test_block(struct dmz_metadata *zmd, struct dm_zone *zone,
               sector_t chunk_block)
 {
     struct dmz_mblock *mblk;
     int ret;
 
     WARN_ON(chunk_block >= zmd->zone_nr_blocks);
 
     /* Get bitmap block */
     mblk = dmz_get_bitmap(zmd, zone, chunk_block);
     if (IS_ERR(mblk))
         return PTR_ERR(mblk);
 
     /* Get offset */
     ret = test_bit(chunk_block & DMZ_BLOCK_MASK_BITS,
                (unsigned long *) mblk->data) != 0;
 
     dmz_release_mblock(zmd, mblk);
 
     return ret;
 }
 
 /*
  * Return the number of blocks from chunk_block to the first block with a bit
  * value specified by set. Search at most nr_blocks blocks from chunk_block.
  */
 static int dmz_to_next_set_block(struct dmz_metadata *zmd, struct dm_zone *zone,
                  sector_t chunk_block, unsigned int nr_blocks,
                  int set)
 {
     struct dmz_mblock *mblk;
     unsigned int bit, set_bit, nr_bits;
     unsigned int zone_bits = zmd->zone_bits_per_mblk;
     unsigned long *bitmap;
     int n = 0;
 
     WARN_ON(chunk_block + nr_blocks > zmd->zone_nr_blocks);
 
     while (nr_blocks) {
         /* Get bitmap block */
         mblk = dmz_get_bitmap(zmd, zone, chunk_block);
         if (IS_ERR(mblk))
             return PTR_ERR(mblk);
 
         /* Get offset */
         bitmap = (unsigned long *) mblk->data;
         bit = chunk_block & DMZ_BLOCK_MASK_BITS;
         nr_bits = min(nr_blocks, zone_bits - bit);
         if (set)
             set_bit = find_next_bit(bitmap, zone_bits, bit);
         else
             set_bit = find_next_zero_bit(bitmap, zone_bits, bit);
         dmz_release_mblock(zmd, mblk);
 
         n += set_bit - bit;
         if (set_bit < zone_bits)
             break;
 
         nr_blocks -= nr_bits;
         chunk_block += nr_bits;
     }
 
     return n;
 }
 
 /*
  * Test if chunk_block is valid. If it is, the number of consecutive
  * valid blocks from chunk_block will be returned.
  */
 int dmz_block_valid(struct dmz_metadata *zmd, struct dm_zone *zone,
             sector_t chunk_block)
 {
     int valid;
 
     valid = dmz_test_block(zmd, zone, chunk_block);
     if (valid <= 0)
         return valid;
 
     /* The block is valid: get the number of valid blocks from block */
     return dmz_to_next_set_block(zmd, zone, chunk_block,
                      zmd->zone_nr_blocks - chunk_block, 0);
 }
 
 /*
  * Find the first valid block from @chunk_block in @zone.
  * If such a block is found, its number is returned using
  * @chunk_block and the total number of valid blocks from @chunk_block
  * is returned.
  */
 int dmz_first_valid_block(struct dmz_metadata *zmd, struct dm_zone *zone,
               sector_t *chunk_block)
 {
     sector_t start_block = *chunk_block;
     int ret;
 
     ret = dmz_to_next_set_block(zmd, zone, start_block,
                     zmd->zone_nr_blocks - start_block, 1);
     if (ret < 0)
         return ret;
 
     start_block += ret;
     *chunk_block = start_block;
 
     return dmz_to_next_set_block(zmd, zone, start_block,
                      zmd->zone_nr_blocks - start_block, 0);
 }
 
 /*
  * Count the number of bits set starting from bit up to bit + nr_bits - 1.
  */
 static int dmz_count_bits(void *bitmap, int bit, int nr_bits)
 {
     unsigned long *addr;
     int end = bit + nr_bits;
     int n = 0;
 
     while (bit < end) {
         if (((bit & (BITS_PER_LONG - 1)) == 0) &&
             ((end - bit) >= BITS_PER_LONG)) {
             addr = (unsigned long *)bitmap + BIT_WORD(bit);
             if (*addr == ULONG_MAX) {
                 n += BITS_PER_LONG;
                 bit += BITS_PER_LONG;
                 continue;
             }
         }
 
         if (test_bit(bit, bitmap))
             n++;
         bit++;
     }
 
     return n;
 }
 
 /*
  * Get a zone weight.
  */
 static void dmz_get_zone_weight(struct dmz_metadata *zmd, struct dm_zone *zone)
 {
     struct dmz_mblock *mblk;
     sector_t chunk_block = 0;
     unsigned int bit, nr_bits;
     unsigned int nr_blocks = zmd->zone_nr_blocks;
     void *bitmap;
     int n = 0;
 
     while (nr_blocks) {
         /* Get bitmap block */
         mblk = dmz_get_bitmap(zmd, zone, chunk_block);
         if (IS_ERR(mblk)) {
             n = 0;
             break;
         }
 
         /* Count bits in this block */
         bitmap = mblk->data;
         bit = chunk_block & DMZ_BLOCK_MASK_BITS;
         nr_bits = min(nr_blocks, zmd->zone_bits_per_mblk - bit);
         n += dmz_count_bits(bitmap, bit, nr_bits);
 
         dmz_release_mblock(zmd, mblk);
 
         nr_blocks -= nr_bits;
         chunk_block += nr_bits;
     }
 
     zone->weight = n;
 }
 
 /*
  * Cleanup the zoned metadata resources.
  */
 static void dmz_cleanup_metadata(struct dmz_metadata *zmd)
 {
     struct rb_root *root;
     struct dmz_mblock *mblk, *next;
     int i;
 
     /* Release zone mapping resources */
     if (zmd->map_mblk) {
         for (i = 0; i < zmd->nr_map_blocks; i++)
             dmz_release_mblock(zmd, zmd->map_mblk[i]);
         kfree(zmd->map_mblk);
         zmd->map_mblk = NULL;
     }
 
     /* Release super blocks */
     for (i = 0; i < 2; i++) {
         if (zmd->sb[i].mblk) {
             dmz_free_mblock(zmd, zmd->sb[i].mblk);
             zmd->sb[i].mblk = NULL;
         }
     }
 
     /* Free cached blocks */
     while (!list_empty(&zmd->mblk_dirty_list)) {
         mblk = list_first_entry(&zmd->mblk_dirty_list,
                     struct dmz_mblock, link);
         dmz_zmd_warn(zmd, "mblock %llu still in dirty list (ref %u)",
                  (u64)mblk->no, mblk->ref);
         list_del_init(&mblk->link);
         rb_erase(&mblk->node, &zmd->mblk_rbtree);
         dmz_free_mblock(zmd, mblk);
     }
 
     while (!list_empty(&zmd->mblk_lru_list)) {
         mblk = list_first_entry(&zmd->mblk_lru_list,
                     struct dmz_mblock, link);
         list_del_init(&mblk->link);
         rb_erase(&mblk->node, &zmd->mblk_rbtree);
         dmz_free_mblock(zmd, mblk);
     }
 
     /* Sanity checks: the mblock rbtree should now be empty */
     root = &zmd->mblk_rbtree;
     rbtree_postorder_for_each_entry_safe(mblk, next, root, node) {
         dmz_zmd_warn(zmd, "mblock %llu ref %u still in rbtree",
                  (u64)mblk->no, mblk->ref);
         mblk->ref = 0;
         dmz_free_mblock(zmd, mblk);
     }
 
     /* Free the zone descriptors */
     dmz_drop_zones(zmd);
 
     mutex_destroy(&zmd->mblk_flush_lock);
     mutex_destroy(&zmd->map_lock);
 }
 
 static void dmz_print_dev(struct dmz_metadata *zmd, int num)
 {
     struct dmz_dev *dev = &zmd->dev[num];
 
     if (bdev_zoned_model(dev->bdev) == BLK_ZONED_NONE)
         dmz_dev_info(dev, "Regular block device");
     else
         dmz_dev_info(dev, "Host-%s zoned block device",
                  bdev_zoned_model(dev->bdev) == BLK_ZONED_HA ?
                  "aware" : "managed");
     if (zmd->sb_version > 1) {
         sector_t sector_offset =
             dev->zone_offset << zmd->zone_nr_sectors_shift;
 
         dmz_dev_info(dev, "  %llu 512-byte logical sectors (offset %llu)",
                  (u64)dev->capacity, (u64)sector_offset);
         dmz_dev_info(dev, "  %u zones of %llu 512-byte logical sectors (offset %llu)",
                  dev->nr_zones, (u64)zmd->zone_nr_sectors,
                  (u64)dev->zone_offset);
     } else {
         dmz_dev_info(dev, "  %llu 512-byte logical sectors",
                  (u64)dev->capacity);
         dmz_dev_info(dev, "  %u zones of %llu 512-byte logical sectors",
                  dev->nr_zones, (u64)zmd->zone_nr_sectors);
     }
 }
 
 /*
  * Initialize the zoned metadata.
  */
 int dmz_ctr_metadata(struct dmz_dev *dev, int num_dev,
              struct dmz_metadata **metadata,
              const char *devname)
 {
     struct dmz_metadata *zmd;
     unsigned int i;
     struct dm_zone *zone;
     int ret;
 
     zmd = kzalloc(sizeof(struct dmz_metadata), GFP_KERNEL);
     if (!zmd)
         return -ENOMEM;
 
     strcpy(zmd->devname, devname);
     zmd->dev = dev;
     zmd->nr_devs = num_dev;
     zmd->mblk_rbtree = RB_ROOT;
     init_rwsem(&zmd->mblk_sem);
     mutex_init(&zmd->mblk_flush_lock);
     spin_lock_init(&zmd->mblk_lock);
     INIT_LIST_HEAD(&zmd->mblk_lru_list);
     INIT_LIST_HEAD(&zmd->mblk_dirty_list);
 
     mutex_init(&zmd->map_lock);
 
     atomic_set(&zmd->unmap_nr_cache, 0);
     INIT_LIST_HEAD(&zmd->unmap_cache_list);
     INIT_LIST_HEAD(&zmd->map_cache_list);
 
     atomic_set(&zmd->nr_reserved_seq_zones, 0);
     INIT_LIST_HEAD(&zmd->reserved_seq_zones_list);
 
     init_waitqueue_head(&zmd->free_wq);
 
     /* Initialize zone descriptors */
     ret = dmz_init_zones(zmd);
     if (ret)
         goto err;
 
     /* Get super block */
     ret = dmz_load_sb(zmd);
     if (ret)
         goto err;
 
     /* Set metadata zones starting from sb_zone */
     for (i = 0; i < zmd->nr_meta_zones << 1; i++) {
         zone = dmz_get(zmd, zmd->sb[0].zone->id + i);
         if (!zone) {
             dmz_zmd_err(zmd,
                     "metadata zone %u not present", i);
             ret = -ENXIO;
             goto err;
         }
         if (!dmz_is_rnd(zone) && !dmz_is_cache(zone)) {
             dmz_zmd_err(zmd,
                     "metadata zone %d is not random", i);
             ret = -ENXIO;
             goto err;
         }
         set_bit(DMZ_META, &zone->flags);
     }
     /* Load mapping table */
     ret = dmz_load_mapping(zmd);
     if (ret)
         goto err;
 
     /*
      * Cache size boundaries: allow at least 2 super blocks, the chunk map
      * blocks and enough blocks to be able to cache the bitmap blocks of
      * up to 16 zones when idle (min_nr_mblks). Otherwise, if busy, allow
      * the cache to add 512 more metadata blocks.
      */
     zmd->min_nr_mblks = 2 + zmd->nr_map_blocks + zmd->zone_nr_bitmap_blocks * 16;
     zmd->max_nr_mblks = zmd->min_nr_mblks + 512;
     zmd->mblk_shrinker.count_objects = dmz_mblock_shrinker_count;
     zmd->mblk_shrinker.scan_objects = dmz_mblock_shrinker_scan;
     zmd->mblk_shrinker.seeks = DEFAULT_SEEKS;
 
     /* Metadata cache shrinker */
     ret = register_shrinker(&zmd->mblk_shrinker, "md-meta:(%u:%u)",
                 MAJOR(dev->bdev->bd_dev),
                 MINOR(dev->bdev->bd_dev));
     if (ret) {
         dmz_zmd_err(zmd, "Register metadata cache shrinker failed");
         goto err;
     }
 
     dmz_zmd_info(zmd, "DM-Zoned metadata version %d", zmd->sb_version);
     for (i = 0; i < zmd->nr_devs; i++)
         dmz_print_dev(zmd, i);
 
     dmz_zmd_info(zmd, "  %u zones of %llu 512-byte logical sectors",
              zmd->nr_zones, (u64)zmd->zone_nr_sectors);
     dmz_zmd_debug(zmd, "  %u metadata zones",
               zmd->nr_meta_zones * 2);
     dmz_zmd_debug(zmd, "  %u data zones for %u chunks",
               zmd->nr_data_zones, zmd->nr_chunks);
     dmz_zmd_debug(zmd, "    %u cache zones (%u unmapped)",
               zmd->nr_cache, atomic_read(&zmd->unmap_nr_cache));
     for (i = 0; i < zmd->nr_devs; i++) {
         dmz_zmd_debug(zmd, "    %u random zones (%u unmapped)",
                   dmz_nr_rnd_zones(zmd, i),
                   dmz_nr_unmap_rnd_zones(zmd, i));
         dmz_zmd_debug(zmd, "    %u sequential zones (%u unmapped)",
                   dmz_nr_seq_zones(zmd, i),
                   dmz_nr_unmap_seq_zones(zmd, i));
     }
     dmz_zmd_debug(zmd, "  %u reserved sequential data zones",
               zmd->nr_reserved_seq);
     dmz_zmd_debug(zmd, "Format:");
     dmz_zmd_debug(zmd, "%u metadata blocks per set (%u max cache)",
               zmd->nr_meta_blocks, zmd->max_nr_mblks);
     dmz_zmd_debug(zmd, "  %u data zone mapping blocks",
               zmd->nr_map_blocks);
     dmz_zmd_debug(zmd, "  %u bitmap blocks",
               zmd->nr_bitmap_blocks);
 
     *metadata = zmd;
 
     return 0;
 err:
     dmz_cleanup_metadata(zmd);
     kfree(zmd);
     *metadata = NULL;
 
     return ret;
 }
 
 /*
  * Cleanup the zoned metadata resources.
  */
 void dmz_dtr_metadata(struct dmz_metadata *zmd)
 {
     unregister_shrinker(&zmd->mblk_shrinker);
     dmz_cleanup_metadata(zmd);
     kfree(zmd);
 }
 
 /*
  * Check zone information on resume.
  */
 int dmz_resume_metadata(struct dmz_metadata *zmd)
 {
     struct dm_zone *zone;
     sector_t wp_block;
     unsigned int i;
     int ret;
 
     /* Check zones */
     for (i = 0; i < zmd->nr_zones; i++) {
         zone = dmz_get(zmd, i);
         if (!zone) {
             dmz_zmd_err(zmd, "Unable to get zone %u", i);
             return -EIO;
         }
         wp_block = zone->wp_block;
 
         ret = dmz_update_zone(zmd, zone);
         if (ret) {
             dmz_zmd_err(zmd, "Broken zone %u", i);
             return ret;
         }
 
         if (dmz_is_offline(zone)) {
             dmz_zmd_warn(zmd, "Zone %u is offline", i);
             continue;
         }
 
         /* Check write pointer */
         if (!dmz_is_seq(zone))
             zone->wp_block = 0;
         else if (zone->wp_block != wp_block) {
             dmz_zmd_err(zmd, "Zone %u: Invalid wp (%llu / %llu)",
                     i, (u64)zone->wp_block, (u64)wp_block);
             zone->wp_block = wp_block;
             dmz_invalidate_blocks(zmd, zone, zone->wp_block,
                           zmd->zone_nr_blocks - zone->wp_block);
         }
     }
 
     return 0;
 }