text: // 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, int 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, int 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);
  	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;
  }
  