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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

 /*
  * Copyright (C) 2011-2012 Red Hat, Inc.
  *
  * This file is released under the GPL.
  */
 
 #include "dm-thin-metadata.h"
 #include "persistent-data/dm-btree.h"
 #include "persistent-data/dm-space-map.h"
 #include "persistent-data/dm-space-map-disk.h"
 #include "persistent-data/dm-transaction-manager.h"
 
 #include <linux/list.h>
 #include <linux/device-mapper.h>
 #include <linux/workqueue.h>
 
 /*--------------------------------------------------------------------------
  * As far as the metadata goes, there is:
  *
  * - A superblock in block zero, taking up fewer than 512 bytes for
  *   atomic writes.
  *
  * - A space map managing the metadata blocks.
  *
  * - A space map managing the data blocks.
  *
  * - A btree mapping our internal thin dev ids onto struct disk_device_details.
  *
  * - A hierarchical btree, with 2 levels which effectively maps (thin
  *   dev id, virtual block) -> block_time.  Block time is a 64-bit
  *   field holding the time in the low 24 bits, and block in the top 40
  *   bits.
  *
  * BTrees consist solely of btree_nodes, that fill a block.  Some are
  * internal nodes, as such their values are a __le64 pointing to other
  * nodes.  Leaf nodes can store data of any reasonable size (ie. much
  * smaller than the block size).  The nodes consist of the header,
  * followed by an array of keys, followed by an array of values.  We have
  * to binary search on the keys so they're all held together to help the
  * cpu cache.
  *
  * Space maps have 2 btrees:
  *
  * - One maps a uint64_t onto a struct index_entry.  Which points to a
  *   bitmap block, and has some details about how many free entries there
  *   are etc.
  *
  * - The bitmap blocks have a header (for the checksum).  Then the rest
  *   of the block is pairs of bits.  With the meaning being:
  *
  *   0 - ref count is 0
  *   1 - ref count is 1
  *   2 - ref count is 2
  *   3 - ref count is higher than 2
  *
  * - If the count is higher than 2 then the ref count is entered in a
  *   second btree that directly maps the block_address to a uint32_t ref
  *   count.
  *
  * The space map metadata variant doesn't have a bitmaps btree.  Instead
  * it has one single blocks worth of index_entries.  This avoids
  * recursive issues with the bitmap btree needing to allocate space in
  * order to insert.  With a small data block size such as 64k the
  * metadata support data devices that are hundreds of terrabytes.
  *
  * The space maps allocate space linearly from front to back.  Space that
  * is freed in a transaction is never recycled within that transaction.
  * To try and avoid fragmenting _free_ space the allocator always goes
  * back and fills in gaps.
  *
  * All metadata io is in THIN_METADATA_BLOCK_SIZE sized/aligned chunks
  * from the block manager.
  *--------------------------------------------------------------------------*/
 
 #define DM_MSG_PREFIX   "thin metadata"
 
 #define THIN_SUPERBLOCK_MAGIC 27022010
 #define THIN_SUPERBLOCK_LOCATION 0
 #define THIN_VERSION 2
 #define SECTOR_TO_BLOCK_SHIFT 3
 
 /*
  * For btree insert:
  *  3 for btree insert +
  *  2 for btree lookup used within space map
  * For btree remove:
  *  2 for shadow spine +
  *  4 for rebalance 3 child node
  */
 #define THIN_MAX_CONCURRENT_LOCKS 6
 
 /* This should be plenty */
 #define SPACE_MAP_ROOT_SIZE 128
 
 /*
  * Little endian on-disk superblock and device details.
  */
 struct thin_disk_superblock {
     __le32 csum;    /* Checksum of superblock except for this field. */
     __le32 flags;
     __le64 blocknr; /* This block number, dm_block_t. */
 
     __u8 uuid[16];
     __le64 magic;
     __le32 version;
     __le32 time;
 
     __le64 trans_id;
 
     /*
      * Root held by userspace transactions.
      */
     __le64 held_root;
 
     __u8 data_space_map_root[SPACE_MAP_ROOT_SIZE];
     __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 
     /*
      * 2-level btree mapping (dev_id, (dev block, time)) -> data block
      */
     __le64 data_mapping_root;
 
     /*
      * Device detail root mapping dev_id -> device_details
      */
     __le64 device_details_root;
 
     __le32 data_block_size;     /* In 512-byte sectors. */
 
     __le32 metadata_block_size; /* In 512-byte sectors. */
     __le64 metadata_nr_blocks;
 
     __le32 compat_flags;
     __le32 compat_ro_flags;
     __le32 incompat_flags;
 } __packed;
 
 struct disk_device_details {
     __le64 mapped_blocks;
     __le64 transaction_id;      /* When created. */
     __le32 creation_time;
     __le32 snapshotted_time;
 } __packed;
 
 struct dm_pool_metadata {
     struct hlist_node hash;
 
     struct block_device *bdev;
     struct dm_block_manager *bm;
     struct dm_space_map *metadata_sm;
     struct dm_space_map *data_sm;
     struct dm_transaction_manager *tm;
     struct dm_transaction_manager *nb_tm;
 
     /*
      * Two-level btree.
      * First level holds thin_dev_t.
      * Second level holds mappings.
      */
     struct dm_btree_info info;
 
     /*
      * Non-blocking version of the above.
      */
     struct dm_btree_info nb_info;
 
     /*
      * Just the top level for deleting whole devices.
      */
     struct dm_btree_info tl_info;
 
     /*
      * Just the bottom level for creating new devices.
      */
     struct dm_btree_info bl_info;
 
     /*
      * Describes the device details btree.
      */
     struct dm_btree_info details_info;
 
     struct rw_semaphore root_lock;
     uint32_t time;
     dm_block_t root;
     dm_block_t details_root;
     struct list_head thin_devices;
     uint64_t trans_id;
     unsigned long flags;
     sector_t data_block_size;
 
     /*
      * Pre-commit callback.
      *
      * This allows the thin provisioning target to run a callback before
      * the metadata are committed.
      */
     dm_pool_pre_commit_fn pre_commit_fn;
     void *pre_commit_context;
 
     /*
      * We reserve a section of the metadata for commit overhead.
      * All reported space does *not* include this.
      */
     dm_block_t metadata_reserve;
 
     /*
      * Set if a transaction has to be aborted but the attempt to roll back
      * to the previous (good) transaction failed.  The only pool metadata
      * operation possible in this state is the closing of the device.
      */
     bool fail_io:1;
 
     /*
      * Set once a thin-pool has been accessed through one of the interfaces
      * that imply the pool is in-service (e.g. thin devices created/deleted,
      * thin-pool message, metadata snapshots, etc).
      */
     bool in_service:1;
 
     /*
      * Reading the space map roots can fail, so we read it into these
      * buffers before the superblock is locked and updated.
      */
     __u8 data_space_map_root[SPACE_MAP_ROOT_SIZE];
     __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 };
 
 struct dm_thin_device {
     struct list_head list;
     struct dm_pool_metadata *pmd;
     dm_thin_id id;
 
     int open_count;
     bool changed:1;
     bool aborted_with_changes:1;
     uint64_t mapped_blocks;
     uint64_t transaction_id;
     uint32_t creation_time;
     uint32_t snapshotted_time;
 };
 
 /*----------------------------------------------------------------
  * superblock validator
  *--------------------------------------------------------------*/
 
 #define SUPERBLOCK_CSUM_XOR 160774
 
 static void sb_prepare_for_write(struct dm_block_validator *v,
                  struct dm_block *b,
                  size_t block_size)
 {
     struct thin_disk_superblock *disk_super = dm_block_data(b);
 
     disk_super->blocknr = cpu_to_le64(dm_block_location(b));
     disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
                               block_size - sizeof(__le32),
                               SUPERBLOCK_CSUM_XOR));
 }
 
 static int sb_check(struct dm_block_validator *v,
             struct dm_block *b,
             size_t block_size)
 {
     struct thin_disk_superblock *disk_super = dm_block_data(b);
     __le32 csum_le;
 
     if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
         DMERR("sb_check failed: blocknr %llu: "
               "wanted %llu", le64_to_cpu(disk_super->blocknr),
               (unsigned long long)dm_block_location(b));
         return -ENOTBLK;
     }
 
     if (le64_to_cpu(disk_super->magic) != THIN_SUPERBLOCK_MAGIC) {
         DMERR("sb_check failed: magic %llu: "
               "wanted %llu", le64_to_cpu(disk_super->magic),
               (unsigned long long)THIN_SUPERBLOCK_MAGIC);
         return -EILSEQ;
     }
 
     csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
                          block_size - sizeof(__le32),
                          SUPERBLOCK_CSUM_XOR));
     if (csum_le != disk_super->csum) {
         DMERR("sb_check failed: csum %u: wanted %u",
               le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
         return -EILSEQ;
     }
 
     return 0;
 }
 
 static struct dm_block_validator sb_validator = {
     .name = "superblock",
     .prepare_for_write = sb_prepare_for_write,
     .check = sb_check
 };
 
 /*----------------------------------------------------------------
  * Methods for the btree value types
  *--------------------------------------------------------------*/
 
 static uint64_t pack_block_time(dm_block_t b, uint32_t t)
 {
     return (b << 24) | t;
 }
 
 static void unpack_block_time(uint64_t v, dm_block_t *b, uint32_t *t)
 {
     *b = v >> 24;
     *t = v & ((1 << 24) - 1);
 }
 
 /*
  * It's more efficient to call dm_sm_{inc,dec}_blocks as few times as
  * possible.  'with_runs' reads contiguous runs of blocks, and calls the
  * given sm function.
  */
 typedef int (*run_fn)(struct dm_space_map *, dm_block_t, dm_block_t);
 
 static void with_runs(struct dm_space_map *sm, const __le64 *value_le, unsigned count, run_fn fn)
 {
     uint64_t b, begin, end;
     uint32_t t;
     bool in_run = false;
     unsigned i;
 
     for (i = 0; i < count; i++, value_le++) {
         /* We know value_le is 8 byte aligned */
         unpack_block_time(le64_to_cpu(*value_le), &b, &t);
 
         if (in_run) {
             if (b == end) {
                 end++;
             } else {
                 fn(sm, begin, end);
                 begin = b;
                 end = b + 1;
             }
         } else {
             in_run = true;
             begin = b;
             end = b + 1;
         }
     }
 
     if (in_run)
         fn(sm, begin, end);
 }
 
 static void data_block_inc(void *context, const void *value_le, unsigned count)
 {
     with_runs((struct dm_space_map *) context,
           (const __le64 *) value_le, count, dm_sm_inc_blocks);
 }
 
 static void data_block_dec(void *context, const void *value_le, unsigned count)
 {
     with_runs((struct dm_space_map *) context,
           (const __le64 *) value_le, count, dm_sm_dec_blocks);
 }
 
 static int data_block_equal(void *context, const void *value1_le, const void *value2_le)
 {
     __le64 v1_le, v2_le;
     uint64_t b1, b2;
     uint32_t t;
 
     memcpy(&v1_le, value1_le, sizeof(v1_le));
     memcpy(&v2_le, value2_le, sizeof(v2_le));
     unpack_block_time(le64_to_cpu(v1_le), &b1, &t);
     unpack_block_time(le64_to_cpu(v2_le), &b2, &t);
 
     return b1 == b2;
 }
 
 static void subtree_inc(void *context, const void *value, unsigned count)
 {
     struct dm_btree_info *info = context;
     const __le64 *root_le = value;
     unsigned i;
 
     for (i = 0; i < count; i++, root_le++)
         dm_tm_inc(info->tm, le64_to_cpu(*root_le));
 }
 
 static void subtree_dec(void *context, const void *value, unsigned count)
 {
     struct dm_btree_info *info = context;
     const __le64 *root_le = value;
     unsigned i;
 
     for (i = 0; i < count; i++, root_le++)
         if (dm_btree_del(info, le64_to_cpu(*root_le)))
             DMERR("btree delete failed");
 }
 
 static int subtree_equal(void *context, const void *value1_le, const void *value2_le)
 {
     __le64 v1_le, v2_le;
     memcpy(&v1_le, value1_le, sizeof(v1_le));
     memcpy(&v2_le, value2_le, sizeof(v2_le));
 
     return v1_le == v2_le;
 }
 
 /*----------------------------------------------------------------*/
 
 /*
  * Variant that is used for in-core only changes or code that
  * shouldn't put the pool in service on its own (e.g. commit).
  */
 static inline void pmd_write_lock_in_core(struct dm_pool_metadata *pmd)
     __acquires(pmd->root_lock)
 {
     down_write(&pmd->root_lock);
 }
 
 static inline void pmd_write_lock(struct dm_pool_metadata *pmd)
 {
     pmd_write_lock_in_core(pmd);
     if (unlikely(!pmd->in_service))
         pmd->in_service = true;
 }
 
 static inline void pmd_write_unlock(struct dm_pool_metadata *pmd)
     __releases(pmd->root_lock)
 {
     up_write(&pmd->root_lock);
 }
 
 /*----------------------------------------------------------------*/
 
 static int superblock_lock_zero(struct dm_pool_metadata *pmd,
                 struct dm_block **sblock)
 {
     return dm_bm_write_lock_zero(pmd->bm, THIN_SUPERBLOCK_LOCATION,
                      &sb_validator, sblock);
 }
 
 static int superblock_lock(struct dm_pool_metadata *pmd,
                struct dm_block **sblock)
 {
     return dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
                 &sb_validator, sblock);
 }
 
 static int __superblock_all_zeroes(struct dm_block_manager *bm, int *result)
 {
     int r;
     unsigned i;
     struct dm_block *b;
     __le64 *data_le, zero = cpu_to_le64(0);
     unsigned block_size = dm_bm_block_size(bm) / sizeof(__le64);
 
     /*
      * We can't use a validator here - it may be all zeroes.
      */
     r = dm_bm_read_lock(bm, THIN_SUPERBLOCK_LOCATION, NULL, &b);
     if (r)
         return r;
 
     data_le = dm_block_data(b);
     *result = 1;
     for (i = 0; i < block_size; i++) {
         if (data_le[i] != zero) {
             *result = 0;
             break;
         }
     }
 
     dm_bm_unlock(b);
 
     return 0;
 }
 
 static void __setup_btree_details(struct dm_pool_metadata *pmd)
 {
     pmd->info.tm = pmd->tm;
     pmd->info.levels = 2;
     pmd->info.value_type.context = pmd->data_sm;
     pmd->info.value_type.size = sizeof(__le64);
     pmd->info.value_type.inc = data_block_inc;
     pmd->info.value_type.dec = data_block_dec;
     pmd->info.value_type.equal = data_block_equal;
 
     memcpy(&pmd->nb_info, &pmd->info, sizeof(pmd->nb_info));
     pmd->nb_info.tm = pmd->nb_tm;
 
     pmd->tl_info.tm = pmd->tm;
     pmd->tl_info.levels = 1;
     pmd->tl_info.value_type.context = &pmd->bl_info;
     pmd->tl_info.value_type.size = sizeof(__le64);
     pmd->tl_info.value_type.inc = subtree_inc;
     pmd->tl_info.value_type.dec = subtree_dec;
     pmd->tl_info.value_type.equal = subtree_equal;
 
     pmd->bl_info.tm = pmd->tm;
     pmd->bl_info.levels = 1;
     pmd->bl_info.value_type.context = pmd->data_sm;
     pmd->bl_info.value_type.size = sizeof(__le64);
     pmd->bl_info.value_type.inc = data_block_inc;
     pmd->bl_info.value_type.dec = data_block_dec;
     pmd->bl_info.value_type.equal = data_block_equal;
 
     pmd->details_info.tm = pmd->tm;
     pmd->details_info.levels = 1;
     pmd->details_info.value_type.context = NULL;
     pmd->details_info.value_type.size = sizeof(struct disk_device_details);
     pmd->details_info.value_type.inc = NULL;
     pmd->details_info.value_type.dec = NULL;
     pmd->details_info.value_type.equal = NULL;
 }
 
 static int save_sm_roots(struct dm_pool_metadata *pmd)
 {
     int r;
     size_t len;
 
     r = dm_sm_root_size(pmd->metadata_sm, &len);
     if (r < 0)
         return r;
 
     r = dm_sm_copy_root(pmd->metadata_sm, &pmd->metadata_space_map_root, len);
     if (r < 0)
         return r;
 
     r = dm_sm_root_size(pmd->data_sm, &len);
     if (r < 0)
         return r;
 
     return dm_sm_copy_root(pmd->data_sm, &pmd->data_space_map_root, len);
 }
 
 static void copy_sm_roots(struct dm_pool_metadata *pmd,
               struct thin_disk_superblock *disk)
 {
     memcpy(&disk->metadata_space_map_root,
            &pmd->metadata_space_map_root,
            sizeof(pmd->metadata_space_map_root));
 
     memcpy(&disk->data_space_map_root,
            &pmd->data_space_map_root,
            sizeof(pmd->data_space_map_root));
 }
 
 static int __write_initial_superblock(struct dm_pool_metadata *pmd)
 {
     int r;
     struct dm_block *sblock;
     struct thin_disk_superblock *disk_super;
     sector_t bdev_size = bdev_nr_sectors(pmd->bdev);
 
     if (bdev_size > THIN_METADATA_MAX_SECTORS)
         bdev_size = THIN_METADATA_MAX_SECTORS;
 
     r = dm_sm_commit(pmd->data_sm);
     if (r < 0)
         return r;
 
     r = dm_tm_pre_commit(pmd->tm);
     if (r < 0)
         return r;
 
     r = save_sm_roots(pmd);
     if (r < 0)
         return r;
 
     r = superblock_lock_zero(pmd, &sblock);
     if (r)
         return r;
 
     disk_super = dm_block_data(sblock);
     disk_super->flags = 0;
     memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
     disk_super->magic = cpu_to_le64(THIN_SUPERBLOCK_MAGIC);
     disk_super->version = cpu_to_le32(THIN_VERSION);
     disk_super->time = 0;
     disk_super->trans_id = 0;
     disk_super->held_root = 0;
 
     copy_sm_roots(pmd, disk_super);
 
     disk_super->data_mapping_root = cpu_to_le64(pmd->root);
     disk_super->device_details_root = cpu_to_le64(pmd->details_root);
     disk_super->metadata_block_size = cpu_to_le32(THIN_METADATA_BLOCK_SIZE);
     disk_super->metadata_nr_blocks = cpu_to_le64(bdev_size >> SECTOR_TO_BLOCK_SHIFT);
     disk_super->data_block_size = cpu_to_le32(pmd->data_block_size);
 
     return dm_tm_commit(pmd->tm, sblock);
 }
 
 static int __format_metadata(struct dm_pool_metadata *pmd)
 {
     int r;
 
     r = dm_tm_create_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
                  &pmd->tm, &pmd->metadata_sm);
     if (r < 0) {
         DMERR("tm_create_with_sm failed");
         return r;
     }
 
     pmd->data_sm = dm_sm_disk_create(pmd->tm, 0);
     if (IS_ERR(pmd->data_sm)) {
         DMERR("sm_disk_create failed");
         r = PTR_ERR(pmd->data_sm);
         goto bad_cleanup_tm;
     }
 
     pmd->nb_tm = dm_tm_create_non_blocking_clone(pmd->tm);
     if (!pmd->nb_tm) {
         DMERR("could not create non-blocking clone tm");
         r = -ENOMEM;
         goto bad_cleanup_data_sm;
     }
 
     __setup_btree_details(pmd);
 
     r = dm_btree_empty(&pmd->info, &pmd->root);
     if (r < 0)
         goto bad_cleanup_nb_tm;
 
     r = dm_btree_empty(&pmd->details_info, &pmd->details_root);
     if (r < 0) {
         DMERR("couldn't create devices root");
         goto bad_cleanup_nb_tm;
     }
 
     r = __write_initial_superblock(pmd);
     if (r)
         goto bad_cleanup_nb_tm;
 
     return 0;
 
 bad_cleanup_nb_tm:
     dm_tm_destroy(pmd->nb_tm);
 bad_cleanup_data_sm:
     dm_sm_destroy(pmd->data_sm);
 bad_cleanup_tm:
     dm_tm_destroy(pmd->tm);
     dm_sm_destroy(pmd->metadata_sm);
 
     return r;
 }
 
 static int __check_incompat_features(struct thin_disk_superblock *disk_super,
                      struct dm_pool_metadata *pmd)
 {
     uint32_t features;
 
     features = le32_to_cpu(disk_super->incompat_flags) & ~THIN_FEATURE_INCOMPAT_SUPP;
     if (features) {
         DMERR("could not access metadata due to unsupported optional features (%lx).",
               (unsigned long)features);
         return -EINVAL;
     }
 
     /*
      * Check for read-only metadata to skip the following RDWR checks.
      */
     if (bdev_read_only(pmd->bdev))
         return 0;
 
     features = le32_to_cpu(disk_super->compat_ro_flags) & ~THIN_FEATURE_COMPAT_RO_SUPP;
     if (features) {
         DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
               (unsigned long)features);
         return -EINVAL;
     }
 
     return 0;
 }
 
 static int __open_metadata(struct dm_pool_metadata *pmd)
 {
     int r;
     struct dm_block *sblock;
     struct thin_disk_superblock *disk_super;
 
     r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
                 &sb_validator, &sblock);
     if (r < 0) {
         DMERR("couldn't read superblock");
         return r;
     }
 
     disk_super = dm_block_data(sblock);
 
     /* Verify the data block size hasn't changed */
     if (le32_to_cpu(disk_super->data_block_size) != pmd->data_block_size) {
         DMERR("changing the data block size (from %u to %llu) is not supported",
               le32_to_cpu(disk_super->data_block_size),
               (unsigned long long)pmd->data_block_size);
         r = -EINVAL;
         goto bad_unlock_sblock;
     }
 
     r = __check_incompat_features(disk_super, pmd);
     if (r < 0)
         goto bad_unlock_sblock;
 
     r = dm_tm_open_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
                    disk_super->metadata_space_map_root,
                    sizeof(disk_super->metadata_space_map_root),
                    &pmd->tm, &pmd->metadata_sm);
     if (r < 0) {
         DMERR("tm_open_with_sm failed");
         goto bad_unlock_sblock;
     }
 
     pmd->data_sm = dm_sm_disk_open(pmd->tm, disk_super->data_space_map_root,
                        sizeof(disk_super->data_space_map_root));
     if (IS_ERR(pmd->data_sm)) {
         DMERR("sm_disk_open failed");
         r = PTR_ERR(pmd->data_sm);
         goto bad_cleanup_tm;
     }
 
     pmd->nb_tm = dm_tm_create_non_blocking_clone(pmd->tm);
     if (!pmd->nb_tm) {
         DMERR("could not create non-blocking clone tm");
         r = -ENOMEM;
         goto bad_cleanup_data_sm;
     }
 
     __setup_btree_details(pmd);
     dm_bm_unlock(sblock);
 
     return 0;
 
 bad_cleanup_data_sm:
     dm_sm_destroy(pmd->data_sm);
 bad_cleanup_tm:
     dm_tm_destroy(pmd->tm);
     dm_sm_destroy(pmd->metadata_sm);
 bad_unlock_sblock:
     dm_bm_unlock(sblock);
 
     return r;
 }
 
 static int __open_or_format_metadata(struct dm_pool_metadata *pmd, bool format_device)
 {
     int r, unformatted;
 
     r = __superblock_all_zeroes(pmd->bm, &unformatted);
     if (r)
         return r;
 
     if (unformatted)
         return format_device ? __format_metadata(pmd) : -EPERM;
 
     return __open_metadata(pmd);
 }
 
 static int __create_persistent_data_objects(struct dm_pool_metadata *pmd, bool format_device)
 {
     int r;
 
     pmd->bm = dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
                       THIN_MAX_CONCURRENT_LOCKS);
     if (IS_ERR(pmd->bm)) {
         DMERR("could not create block manager");
         r = PTR_ERR(pmd->bm);
         pmd->bm = NULL;
         return r;
     }
 
     r = __open_or_format_metadata(pmd, format_device);
     if (r) {
         dm_block_manager_destroy(pmd->bm);
         pmd->bm = NULL;
     }
 
     return r;
 }
 
 static void __destroy_persistent_data_objects(struct dm_pool_metadata *pmd)
 {
     dm_sm_destroy(pmd->data_sm);
     dm_sm_destroy(pmd->metadata_sm);
     dm_tm_destroy(pmd->nb_tm);
     dm_tm_destroy(pmd->tm);
     dm_block_manager_destroy(pmd->bm);
 }
 
 static int __begin_transaction(struct dm_pool_metadata *pmd)
 {
     int r;
     struct thin_disk_superblock *disk_super;
     struct dm_block *sblock;
 
     /*
      * We re-read the superblock every time.  Shouldn't need to do this
      * really.
      */
     r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
                 &sb_validator, &sblock);
     if (r)
         return r;
 
     disk_super = dm_block_data(sblock);
     pmd->time = le32_to_cpu(disk_super->time);
     pmd->root = le64_to_cpu(disk_super->data_mapping_root);
     pmd->details_root = le64_to_cpu(disk_super->device_details_root);
     pmd->trans_id = le64_to_cpu(disk_super->trans_id);
     pmd->flags = le32_to_cpu(disk_super->flags);
     pmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 
     dm_bm_unlock(sblock);
     return 0;
 }
 
 static int __write_changed_details(struct dm_pool_metadata *pmd)
 {
     int r;
     struct dm_thin_device *td, *tmp;
     struct disk_device_details details;
     uint64_t key;
 
     list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
         if (!td->changed)
             continue;
 
         key = td->id;
 
         details.mapped_blocks = cpu_to_le64(td->mapped_blocks);
         details.transaction_id = cpu_to_le64(td->transaction_id);
         details.creation_time = cpu_to_le32(td->creation_time);
         details.snapshotted_time = cpu_to_le32(td->snapshotted_time);
         __dm_bless_for_disk(&details);
 
         r = dm_btree_insert(&pmd->details_info, pmd->details_root,
                     &key, &details, &pmd->details_root);
         if (r)
             return r;
 
         if (td->open_count)
             td->changed = false;
         else {
             list_del(&td->list);
             kfree(td);
         }
     }
 
     return 0;
 }
 
 static int __commit_transaction(struct dm_pool_metadata *pmd)
 {
     int r;
     struct thin_disk_superblock *disk_super;
     struct dm_block *sblock;
 
     /*
      * We need to know if the thin_disk_superblock exceeds a 512-byte sector.
      */
     BUILD_BUG_ON(sizeof(struct thin_disk_superblock) > 512);
     BUG_ON(!rwsem_is_locked(&pmd->root_lock));
 
     if (unlikely(!pmd->in_service))
         return 0;
 
     if (pmd->pre_commit_fn) {
         r = pmd->pre_commit_fn(pmd->pre_commit_context);
         if (r < 0) {
             DMERR("pre-commit callback failed");
             return r;
         }
     }
 
     r = __write_changed_details(pmd);
     if (r < 0)
         return r;
 
     r = dm_sm_commit(pmd->data_sm);
     if (r < 0)
         return r;
 
     r = dm_tm_pre_commit(pmd->tm);
     if (r < 0)
         return r;
 
     r = save_sm_roots(pmd);
     if (r < 0)
         return r;
 
     r = superblock_lock(pmd, &sblock);
     if (r)
         return r;
 
     disk_super = dm_block_data(sblock);
     disk_super->time = cpu_to_le32(pmd->time);
     disk_super->data_mapping_root = cpu_to_le64(pmd->root);
     disk_super->device_details_root = cpu_to_le64(pmd->details_root);
     disk_super->trans_id = cpu_to_le64(pmd->trans_id);
     disk_super->flags = cpu_to_le32(pmd->flags);
 
     copy_sm_roots(pmd, disk_super);
 
     return dm_tm_commit(pmd->tm, sblock);
 }
 
 static void __set_metadata_reserve(struct dm_pool_metadata *pmd)
 {
     int r;
     dm_block_t total;
     dm_block_t max_blocks = 4096; /* 16M */
 
     r = dm_sm_get_nr_blocks(pmd->metadata_sm, &total);
     if (r) {
         DMERR("could not get size of metadata device");
         pmd->metadata_reserve = max_blocks;
     } else
         pmd->metadata_reserve = min(max_blocks, div_u64(total, 10));
 }
 
 struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
                            sector_t data_block_size,
                            bool format_device)
 {
     int r;
     struct dm_pool_metadata *pmd;
 
     pmd = kmalloc(sizeof(*pmd), GFP_KERNEL);
     if (!pmd) {
         DMERR("could not allocate metadata struct");
         return ERR_PTR(-ENOMEM);
     }
 
     init_rwsem(&pmd->root_lock);
     pmd->time = 0;
     INIT_LIST_HEAD(&pmd->thin_devices);
     pmd->fail_io = false;
     pmd->in_service = false;
     pmd->bdev = bdev;
     pmd->data_block_size = data_block_size;
     pmd->pre_commit_fn = NULL;
     pmd->pre_commit_context = NULL;
 
     r = __create_persistent_data_objects(pmd, format_device);
     if (r) {
         kfree(pmd);
         return ERR_PTR(r);
     }
 
     r = __begin_transaction(pmd);
     if (r < 0) {
         if (dm_pool_metadata_close(pmd) < 0)
             DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
         return ERR_PTR(r);
     }
 
     __set_metadata_reserve(pmd);
 
     return pmd;
 }
 
 int dm_pool_metadata_close(struct dm_pool_metadata *pmd)
 {
     int r;
     unsigned open_devices = 0;
     struct dm_thin_device *td, *tmp;
 
     down_read(&pmd->root_lock);
     list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
         if (td->open_count)
             open_devices++;
         else {
             list_del(&td->list);
             kfree(td);
         }
     }
     up_read(&pmd->root_lock);
 
     if (open_devices) {
         DMERR("attempt to close pmd when %u device(s) are still open",
                open_devices);
         return -EBUSY;
     }
 
     pmd_write_lock_in_core(pmd);
     if (!pmd->fail_io && !dm_bm_is_read_only(pmd->bm)) {
         r = __commit_transaction(pmd);
         if (r < 0)
             DMWARN("%s: __commit_transaction() failed, error = %d",
                    __func__, r);
     }
     pmd_write_unlock(pmd);
     if (!pmd->fail_io)
         __destroy_persistent_data_objects(pmd);
 
     kfree(pmd);
     return 0;
 }
 
 /*
  * __open_device: Returns @td corresponding to device with id @dev,
  * creating it if @create is set and incrementing @td->open_count.
  * On failure, @td is undefined.
  */
 static int __open_device(struct dm_pool_metadata *pmd,
              dm_thin_id dev, int create,
              struct dm_thin_device **td)
 {
     int r, changed = 0;
     struct dm_thin_device *td2;
     uint64_t key = dev;
     struct disk_device_details details_le;
 
     /*
      * If the device is already open, return it.
      */
     list_for_each_entry(td2, &pmd->thin_devices, list)
         if (td2->id == dev) {
             /*
              * May not create an already-open device.
              */
             if (create)
                 return -EEXIST;
 
             td2->open_count++;
             *td = td2;
             return 0;
         }
 
     /*
      * Check the device exists.
      */
     r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
                 &key, &details_le);
     if (r) {
         if (r != -ENODATA || !create)
             return r;
 
         /*
          * Create new device.
          */
         changed = 1;
         details_le.mapped_blocks = 0;
         details_le.transaction_id = cpu_to_le64(pmd->trans_id);
         details_le.creation_time = cpu_to_le32(pmd->time);
         details_le.snapshotted_time = cpu_to_le32(pmd->time);
     }
 
     *td = kmalloc(sizeof(**td), GFP_NOIO);
     if (!*td)
         return -ENOMEM;
 
     (*td)->pmd = pmd;
     (*td)->id = dev;
     (*td)->open_count = 1;
     (*td)->changed = changed;
     (*td)->aborted_with_changes = false;
     (*td)->mapped_blocks = le64_to_cpu(details_le.mapped_blocks);
     (*td)->transaction_id = le64_to_cpu(details_le.transaction_id);
     (*td)->creation_time = le32_to_cpu(details_le.creation_time);
     (*td)->snapshotted_time = le32_to_cpu(details_le.snapshotted_time);
 
     list_add(&(*td)->list, &pmd->thin_devices);
 
     return 0;
 }
 
 static void __close_device(struct dm_thin_device *td)
 {
     --td->open_count;
 }
 
 static int __create_thin(struct dm_pool_metadata *pmd,
              dm_thin_id dev)
 {
     int r;
     dm_block_t dev_root;
     uint64_t key = dev;
     struct dm_thin_device *td;
     __le64 value;
 
     r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
                 &key, NULL);
     if (!r)
         return -EEXIST;
 
     /*
      * Create an empty btree for the mappings.
      */
     r = dm_btree_empty(&pmd->bl_info, &dev_root);
     if (r)
         return r;
 
     /*
      * Insert it into the main mapping tree.
      */
     value = cpu_to_le64(dev_root);
     __dm_bless_for_disk(&value);
     r = dm_btree_insert(&pmd->tl_info, pmd->root, &key, &value, &pmd->root);
     if (r) {
         dm_btree_del(&pmd->bl_info, dev_root);
         return r;
     }
 
     r = __open_device(pmd, dev, 1, &td);
     if (r) {
         dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
         dm_btree_del(&pmd->bl_info, dev_root);
         return r;
     }
     __close_device(td);
 
     return r;
 }
 
 int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev)
 {
     int r = -EINVAL;
 
     pmd_write_lock(pmd);
     if (!pmd->fail_io)
         r = __create_thin(pmd, dev);
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 static int __set_snapshot_details(struct dm_pool_metadata *pmd,
                   struct dm_thin_device *snap,
                   dm_thin_id origin, uint32_t time)
 {
     int r;
     struct dm_thin_device *td;
 
     r = __open_device(pmd, origin, 0, &td);
     if (r)
         return r;
 
     td->changed = true;
     td->snapshotted_time = time;
 
     snap->mapped_blocks = td->mapped_blocks;
     snap->snapshotted_time = time;
     __close_device(td);
 
     return 0;
 }
 
 static int __create_snap(struct dm_pool_metadata *pmd,
              dm_thin_id dev, dm_thin_id origin)
 {
     int r;
     dm_block_t origin_root;
     uint64_t key = origin, dev_key = dev;
     struct dm_thin_device *td;
     __le64 value;
 
     /* check this device is unused */
     r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
                 &dev_key, NULL);
     if (!r)
         return -EEXIST;
 
     /* find the mapping tree for the origin */
     r = dm_btree_lookup(&pmd->tl_info, pmd->root, &key, &value);
     if (r)
         return r;
     origin_root = le64_to_cpu(value);
 
     /* clone the origin, an inc will do */
     dm_tm_inc(pmd->tm, origin_root);
 
     /* insert into the main mapping tree */
     value = cpu_to_le64(origin_root);
     __dm_bless_for_disk(&value);
     key = dev;
     r = dm_btree_insert(&pmd->tl_info, pmd->root, &key, &value, &pmd->root);
     if (r) {
         dm_tm_dec(pmd->tm, origin_root);
         return r;
     }
 
     pmd->time++;
 
     r = __open_device(pmd, dev, 1, &td);
     if (r)
         goto bad;
 
     r = __set_snapshot_details(pmd, td, origin, pmd->time);
     __close_device(td);
 
     if (r)
         goto bad;
 
     return 0;
 
 bad:
     dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
     dm_btree_remove(&pmd->details_info, pmd->details_root,
             &key, &pmd->details_root);
     return r;
 }
 
 int dm_pool_create_snap(struct dm_pool_metadata *pmd,
                  dm_thin_id dev,
                  dm_thin_id origin)
 {
     int r = -EINVAL;
 
     pmd_write_lock(pmd);
     if (!pmd->fail_io)
         r = __create_snap(pmd, dev, origin);
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 static int __delete_device(struct dm_pool_metadata *pmd, dm_thin_id dev)
 {
     int r;
     uint64_t key = dev;
     struct dm_thin_device *td;
 
     /* TODO: failure should mark the transaction invalid */
     r = __open_device(pmd, dev, 0, &td);
     if (r)
         return r;
 
     if (td->open_count > 1) {
         __close_device(td);
         return -EBUSY;
     }
 
     list_del(&td->list);
     kfree(td);
     r = dm_btree_remove(&pmd->details_info, pmd->details_root,
                 &key, &pmd->details_root);
     if (r)
         return r;
 
     r = dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
     if (r)
         return r;
 
     return 0;
 }
 
 int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
                    dm_thin_id dev)
 {
     int r = -EINVAL;
 
     pmd_write_lock(pmd);
     if (!pmd->fail_io)
         r = __delete_device(pmd, dev);
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
                     uint64_t current_id,
                     uint64_t new_id)
 {
     int r = -EINVAL;
 
     pmd_write_lock(pmd);
 
     if (pmd->fail_io)
         goto out;
 
     if (pmd->trans_id != current_id) {
         DMERR("mismatched transaction id");
         goto out;
     }
 
     pmd->trans_id = new_id;
     r = 0;
 
 out:
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
                     uint64_t *result)
 {
     int r = -EINVAL;
 
     down_read(&pmd->root_lock);
     if (!pmd->fail_io) {
         *result = pmd->trans_id;
         r = 0;
     }
     up_read(&pmd->root_lock);
 
     return r;
 }
 
 static int __reserve_metadata_snap(struct dm_pool_metadata *pmd)
 {
     int r, inc;
     struct thin_disk_superblock *disk_super;
     struct dm_block *copy, *sblock;
     dm_block_t held_root;
 
     /*
      * We commit to ensure the btree roots which we increment in a
      * moment are up to date.
      */
     r = __commit_transaction(pmd);
     if (r < 0) {
         DMWARN("%s: __commit_transaction() failed, error = %d",
                __func__, r);
         return r;
     }
 
     /*
      * Copy the superblock.
      */
     dm_sm_inc_block(pmd->metadata_sm, THIN_SUPERBLOCK_LOCATION);
     r = dm_tm_shadow_block(pmd->tm, THIN_SUPERBLOCK_LOCATION,
                    &sb_validator, &copy, &inc);
     if (r)
         return r;
 
     BUG_ON(!inc);
 
     held_root = dm_block_location(copy);
     disk_super = dm_block_data(copy);
 
     if (le64_to_cpu(disk_super->held_root)) {
         DMWARN("Pool metadata snapshot already exists: release this before taking another.");
 
         dm_tm_dec(pmd->tm, held_root);
         dm_tm_unlock(pmd->tm, copy);
         return -EBUSY;
     }
 
     /*
      * Wipe the spacemap since we're not publishing this.
      */
     memset(&disk_super->data_space_map_root, 0,
            sizeof(disk_super->data_space_map_root));
     memset(&disk_super->metadata_space_map_root, 0,
            sizeof(disk_super->metadata_space_map_root));
 
     /*
      * Increment the data structures that need to be preserved.
      */
     dm_tm_inc(pmd->tm, le64_to_cpu(disk_super->data_mapping_root));
     dm_tm_inc(pmd->tm, le64_to_cpu(disk_super->device_details_root));
     dm_tm_unlock(pmd->tm, copy);
 
     /*
      * Write the held root into the superblock.
      */
     r = superblock_lock(pmd, &sblock);
     if (r) {
         dm_tm_dec(pmd->tm, held_root);
         return r;
     }
 
     disk_super = dm_block_data(sblock);
     disk_super->held_root = cpu_to_le64(held_root);
     dm_bm_unlock(sblock);
     return 0;
 }
 
 int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd)
 {
     int r = -EINVAL;
 
     pmd_write_lock(pmd);
     if (!pmd->fail_io)
         r = __reserve_metadata_snap(pmd);
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 static int __release_metadata_snap(struct dm_pool_metadata *pmd)
 {
     int r;
     struct thin_disk_superblock *disk_super;
     struct dm_block *sblock, *copy;
     dm_block_t held_root;
 
     r = superblock_lock(pmd, &sblock);
     if (r)
         return r;
 
     disk_super = dm_block_data(sblock);
     held_root = le64_to_cpu(disk_super->held_root);
     disk_super->held_root = cpu_to_le64(0);
 
     dm_bm_unlock(sblock);
 
     if (!held_root) {
         DMWARN("No pool metadata snapshot found: nothing to release.");
         return -EINVAL;
     }
 
     r = dm_tm_read_lock(pmd->tm, held_root, &sb_validator, &copy);
     if (r)
         return r;
 
     disk_super = dm_block_data(copy);
     dm_btree_del(&pmd->info, le64_to_cpu(disk_super->data_mapping_root));
     dm_btree_del(&pmd->details_info, le64_to_cpu(disk_super->device_details_root));
     dm_sm_dec_block(pmd->metadata_sm, held_root);
 
     dm_tm_unlock(pmd->tm, copy);
 
     return 0;
 }
 
 int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd)
 {
     int r = -EINVAL;
 
     pmd_write_lock(pmd);
     if (!pmd->fail_io)
         r = __release_metadata_snap(pmd);
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 static int __get_metadata_snap(struct dm_pool_metadata *pmd,
                    dm_block_t *result)
 {
     int r;
     struct thin_disk_superblock *disk_super;
     struct dm_block *sblock;
 
     r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
                 &sb_validator, &sblock);
     if (r)
         return r;
 
     disk_super = dm_block_data(sblock);
     *result = le64_to_cpu(disk_super->held_root);
 
     dm_bm_unlock(sblock);
 
     return 0;
 }
 
 int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
                   dm_block_t *result)
 {
     int r = -EINVAL;
 
     down_read(&pmd->root_lock);
     if (!pmd->fail_io)
         r = __get_metadata_snap(pmd, result);
     up_read(&pmd->root_lock);
 
     return r;
 }
 
 int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
                  struct dm_thin_device **td)
 {
     int r = -EINVAL;
 
     pmd_write_lock_in_core(pmd);
     if (!pmd->fail_io)
         r = __open_device(pmd, dev, 0, td);
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 int dm_pool_close_thin_device(struct dm_thin_device *td)
 {
     pmd_write_lock_in_core(td->pmd);
     __close_device(td);
     pmd_write_unlock(td->pmd);
 
     return 0;
 }
 
 dm_thin_id dm_thin_dev_id(struct dm_thin_device *td)
 {
     return td->id;
 }
 
 /*
  * Check whether @time (of block creation) is older than @td's last snapshot.
  * If so then the associated block is shared with the last snapshot device.
  * Any block on a device created *after* the device last got snapshotted is
  * necessarily not shared.
  */
 static bool __snapshotted_since(struct dm_thin_device *td, uint32_t time)
 {
     return td->snapshotted_time > time;
 }
 
 static void unpack_lookup_result(struct dm_thin_device *td, __le64 value,
                  struct dm_thin_lookup_result *result)
 {
     uint64_t block_time = 0;
     dm_block_t exception_block;
     uint32_t exception_time;
 
     block_time = le64_to_cpu(value);
     unpack_block_time(block_time, &exception_block, &exception_time);
     result->block = exception_block;
     result->shared = __snapshotted_since(td, exception_time);
 }
 
 static int __find_block(struct dm_thin_device *td, dm_block_t block,
             int can_issue_io, struct dm_thin_lookup_result *result)
 {
     int r;
     __le64 value;
     struct dm_pool_metadata *pmd = td->pmd;
     dm_block_t keys[2] = { td->id, block };
     struct dm_btree_info *info;
 
     if (can_issue_io) {
         info = &pmd->info;
     } else
         info = &pmd->nb_info;
 
     r = dm_btree_lookup(info, pmd->root, keys, &value);
     if (!r)
         unpack_lookup_result(td, value, result);
 
     return r;
 }
 
 int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
                int can_issue_io, struct dm_thin_lookup_result *result)
 {
     int r;
     struct dm_pool_metadata *pmd = td->pmd;
 
     down_read(&pmd->root_lock);
     if (pmd->fail_io) {
         up_read(&pmd->root_lock);
         return -EINVAL;
     }
 
     r = __find_block(td, block, can_issue_io, result);
 
     up_read(&pmd->root_lock);
     return r;
 }
 
 static int __find_next_mapped_block(struct dm_thin_device *td, dm_block_t block,
                       dm_block_t *vblock,
                       struct dm_thin_lookup_result *result)
 {
     int r;
     __le64 value;
     struct dm_pool_metadata *pmd = td->pmd;
     dm_block_t keys[2] = { td->id, block };
 
     r = dm_btree_lookup_next(&pmd->info, pmd->root, keys, vblock, &value);
     if (!r)
         unpack_lookup_result(td, value, result);
 
     return r;
 }
 
 static int __find_mapped_range(struct dm_thin_device *td,
                    dm_block_t begin, dm_block_t end,
                    dm_block_t *thin_begin, dm_block_t *thin_end,
                    dm_block_t *pool_begin, bool *maybe_shared)
 {
     int r;
     dm_block_t pool_end;
     struct dm_thin_lookup_result lookup;
 
     if (end < begin)
         return -ENODATA;
 
     r = __find_next_mapped_block(td, begin, &begin, &lookup);
     if (r)
         return r;
 
     if (begin >= end)
         return -ENODATA;
 
     *thin_begin = begin;
     *pool_begin = lookup.block;
     *maybe_shared = lookup.shared;
 
     begin++;
     pool_end = *pool_begin + 1;
     while (begin != end) {
         r = __find_block(td, begin, true, &lookup);
         if (r) {
             if (r == -ENODATA)
                 break;
             else
                 return r;
         }
 
         if ((lookup.block != pool_end) ||
             (lookup.shared != *maybe_shared))
             break;
 
         pool_end++;
         begin++;
     }
 
     *thin_end = begin;
     return 0;
 }
 
 int dm_thin_find_mapped_range(struct dm_thin_device *td,
                   dm_block_t begin, dm_block_t end,
                   dm_block_t *thin_begin, dm_block_t *thin_end,
                   dm_block_t *pool_begin, bool *maybe_shared)
 {
     int r = -EINVAL;
     struct dm_pool_metadata *pmd = td->pmd;
 
     down_read(&pmd->root_lock);
     if (!pmd->fail_io) {
         r = __find_mapped_range(td, begin, end, thin_begin, thin_end,
                     pool_begin, maybe_shared);
     }
     up_read(&pmd->root_lock);
 
     return r;
 }
 
 static int __insert(struct dm_thin_device *td, dm_block_t block,
             dm_block_t data_block)
 {
     int r, inserted;
     __le64 value;
     struct dm_pool_metadata *pmd = td->pmd;
     dm_block_t keys[2] = { td->id, block };
 
     value = cpu_to_le64(pack_block_time(data_block, pmd->time));
     __dm_bless_for_disk(&value);
 
     r = dm_btree_insert_notify(&pmd->info, pmd->root, keys, &value,
                    &pmd->root, &inserted);
     if (r)
         return r;
 
     td->changed = true;
     if (inserted)
         td->mapped_blocks++;
 
     return 0;
 }
 
 int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
              dm_block_t data_block)
 {
     int r = -EINVAL;
 
     pmd_write_lock(td->pmd);
     if (!td->pmd->fail_io)
         r = __insert(td, block, data_block);
     pmd_write_unlock(td->pmd);
 
     return r;
 }
 
 static int __remove_range(struct dm_thin_device *td, dm_block_t begin, dm_block_t end)
 {
     int r;
     unsigned count, total_count = 0;
     struct dm_pool_metadata *pmd = td->pmd;
     dm_block_t keys[1] = { td->id };
     __le64 value;
     dm_block_t mapping_root;
 
     /*
      * Find the mapping tree
      */
     r = dm_btree_lookup(&pmd->tl_info, pmd->root, keys, &value);
     if (r)
         return r;
 
     /*
      * Remove from the mapping tree, taking care to inc the
      * ref count so it doesn't get deleted.
      */
     mapping_root = le64_to_cpu(value);
     dm_tm_inc(pmd->tm, mapping_root);
     r = dm_btree_remove(&pmd->tl_info, pmd->root, keys, &pmd->root);
     if (r)
         return r;
 
     /*
      * Remove leaves stops at the first unmapped entry, so we have to
      * loop round finding mapped ranges.
      */
     while (begin < end) {
         r = dm_btree_lookup_next(&pmd->bl_info, mapping_root, &begin, &begin, &value);
         if (r == -ENODATA)
             break;
 
         if (r)
             return r;
 
         if (begin >= end)
             break;
 
         r = dm_btree_remove_leaves(&pmd->bl_info, mapping_root, &begin, end, &mapping_root, &count);
         if (r)
             return r;
 
         total_count += count;
     }
 
     td->mapped_blocks -= total_count;
     td->changed = true;
 
     /*
      * Reinsert the mapping tree.
      */
     value = cpu_to_le64(mapping_root);
     __dm_bless_for_disk(&value);
     return dm_btree_insert(&pmd->tl_info, pmd->root, keys, &value, &pmd->root);
 }
 
 int dm_thin_remove_range(struct dm_thin_device *td,
              dm_block_t begin, dm_block_t end)
 {
     int r = -EINVAL;
 
     pmd_write_lock(td->pmd);
     if (!td->pmd->fail_io)
         r = __remove_range(td, begin, end);
     pmd_write_unlock(td->pmd);
 
     return r;
 }
 
 int dm_pool_block_is_shared(struct dm_pool_metadata *pmd, dm_block_t b, bool *result)
 {
     int r;
     uint32_t ref_count;
 
     down_read(&pmd->root_lock);
     r = dm_sm_get_count(pmd->data_sm, b, &ref_count);
     if (!r)
         *result = (ref_count > 1);
     up_read(&pmd->root_lock);
 
     return r;
 }
 
 int dm_pool_inc_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e)
 {
     int r = 0;
 
     pmd_write_lock(pmd);
     r = dm_sm_inc_blocks(pmd->data_sm, b, e);
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 int dm_pool_dec_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e)
 {
     int r = 0;
 
     pmd_write_lock(pmd);
     r = dm_sm_dec_blocks(pmd->data_sm, b, e);
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 bool dm_thin_changed_this_transaction(struct dm_thin_device *td)
 {
     int r;
 
     down_read(&td->pmd->root_lock);
     r = td->changed;
     up_read(&td->pmd->root_lock);
 
     return r;
 }
 
 bool dm_pool_changed_this_transaction(struct dm_pool_metadata *pmd)
 {
     bool r = false;
     struct dm_thin_device *td, *tmp;
 
     down_read(&pmd->root_lock);
     list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
         if (td->changed) {
             r = td->changed;
             break;
         }
     }
     up_read(&pmd->root_lock);
 
     return r;
 }
 
 bool dm_thin_aborted_changes(struct dm_thin_device *td)
 {
     bool r;
 
     down_read(&td->pmd->root_lock);
     r = td->aborted_with_changes;
     up_read(&td->pmd->root_lock);
 
     return r;
 }
 
 int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result)
 {
     int r = -EINVAL;
 
     pmd_write_lock(pmd);
     if (!pmd->fail_io)
         r = dm_sm_new_block(pmd->data_sm, result);
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 int dm_pool_commit_metadata(struct dm_pool_metadata *pmd)
 {
     int r = -EINVAL;
 
     /*
      * Care is taken to not have commit be what
      * triggers putting the thin-pool in-service.
      */
     pmd_write_lock_in_core(pmd);
     if (pmd->fail_io)
         goto out;
 
     r = __commit_transaction(pmd);
     if (r < 0)
         goto out;
 
     /*
      * Open the next transaction.
      */
     r = __begin_transaction(pmd);
 out:
     pmd_write_unlock(pmd);
     return r;
 }
 
 static void __set_abort_with_changes_flags(struct dm_pool_metadata *pmd)
 {
     struct dm_thin_device *td;
 
     list_for_each_entry(td, &pmd->thin_devices, list)
         td->aborted_with_changes = td->changed;
 }
 
 int dm_pool_abort_metadata(struct dm_pool_metadata *pmd)
 {
     int r = -EINVAL;
 
     pmd_write_lock(pmd);
     if (pmd->fail_io)
         goto out;
 
     __set_abort_with_changes_flags(pmd);
     __destroy_persistent_data_objects(pmd);
     r = __create_persistent_data_objects(pmd, false);
     if (r)
         pmd->fail_io = true;
 
 out:
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd, dm_block_t *result)
 {
     int r = -EINVAL;
 
     down_read(&pmd->root_lock);
     if (!pmd->fail_io)
         r = dm_sm_get_nr_free(pmd->data_sm, result);
     up_read(&pmd->root_lock);
 
     return r;
 }
 
 int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
                       dm_block_t *result)
 {
     int r = -EINVAL;
 
     down_read(&pmd->root_lock);
     if (!pmd->fail_io)
         r = dm_sm_get_nr_free(pmd->metadata_sm, result);
 
     if (!r) {
         if (*result < pmd->metadata_reserve)
             *result = 0;
         else
             *result -= pmd->metadata_reserve;
     }
     up_read(&pmd->root_lock);
 
     return r;
 }
 
 int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
                   dm_block_t *result)
 {
     int r = -EINVAL;
 
     down_read(&pmd->root_lock);
     if (!pmd->fail_io)
         r = dm_sm_get_nr_blocks(pmd->metadata_sm, result);
     up_read(&pmd->root_lock);
 
     return r;
 }
 
 int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result)
 {
     int r = -EINVAL;
 
     down_read(&pmd->root_lock);
     if (!pmd->fail_io)
         r = dm_sm_get_nr_blocks(pmd->data_sm, result);
     up_read(&pmd->root_lock);
 
     return r;
 }
 
 int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result)
 {
     int r = -EINVAL;
     struct dm_pool_metadata *pmd = td->pmd;
 
     down_read(&pmd->root_lock);
     if (!pmd->fail_io) {
         *result = td->mapped_blocks;
         r = 0;
     }
     up_read(&pmd->root_lock);
 
     return r;
 }
 
 static int __highest_block(struct dm_thin_device *td, dm_block_t *result)
 {
     int r;
     __le64 value_le;
     dm_block_t thin_root;
     struct dm_pool_metadata *pmd = td->pmd;
 
     r = dm_btree_lookup(&pmd->tl_info, pmd->root, &td->id, &value_le);
     if (r)
         return r;
 
     thin_root = le64_to_cpu(value_le);
 
     return dm_btree_find_highest_key(&pmd->bl_info, thin_root, result);
 }
 
 int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
                      dm_block_t *result)
 {
     int r = -EINVAL;
     struct dm_pool_metadata *pmd = td->pmd;
 
     down_read(&pmd->root_lock);
     if (!pmd->fail_io)
         r = __highest_block(td, result);
     up_read(&pmd->root_lock);
 
     return r;
 }
 
 static int __resize_space_map(struct dm_space_map *sm, dm_block_t new_count)
 {
     int r;
     dm_block_t old_count;
 
     r = dm_sm_get_nr_blocks(sm, &old_count);
     if (r)
         return r;
 
     if (new_count == old_count)
         return 0;
 
     if (new_count < old_count) {
         DMERR("cannot reduce size of space map");
         return -EINVAL;
     }
 
     return dm_sm_extend(sm, new_count - old_count);
 }
 
 int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
 {
     int r = -EINVAL;
 
     pmd_write_lock(pmd);
     if (!pmd->fail_io)
         r = __resize_space_map(pmd->data_sm, new_count);
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
 {
     int r = -EINVAL;
 
     pmd_write_lock(pmd);
     if (!pmd->fail_io) {
         r = __resize_space_map(pmd->metadata_sm, new_count);
         if (!r)
             __set_metadata_reserve(pmd);
     }
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd)
 {
     pmd_write_lock_in_core(pmd);
     dm_bm_set_read_only(pmd->bm);
     pmd_write_unlock(pmd);
 }
 
 void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd)
 {
     pmd_write_lock_in_core(pmd);
     dm_bm_set_read_write(pmd->bm);
     pmd_write_unlock(pmd);
 }
 
 int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
                     dm_block_t threshold,
                     dm_sm_threshold_fn fn,
                     void *context)
 {
     int r = -EINVAL;
 
     pmd_write_lock_in_core(pmd);
     if (!pmd->fail_io) {
         r = dm_sm_register_threshold_callback(pmd->metadata_sm,
                               threshold, fn, context);
     }
     pmd_write_unlock(pmd);
 
     return r;
 }
 
 void dm_pool_register_pre_commit_callback(struct dm_pool_metadata *pmd,
                       dm_pool_pre_commit_fn fn,
                       void *context)
 {
     pmd_write_lock_in_core(pmd);
     pmd->pre_commit_fn = fn;
     pmd->pre_commit_context = context;
     pmd_write_unlock(pmd);
 }
 
 int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd)
 {
     int r = -EINVAL;
     struct dm_block *sblock;
     struct thin_disk_superblock *disk_super;
 
     pmd_write_lock(pmd);
     if (pmd->fail_io)
         goto out;
 
     pmd->flags |= THIN_METADATA_NEEDS_CHECK_FLAG;
 
     r = superblock_lock(pmd, &sblock);
     if (r) {
         DMERR("couldn't lock superblock");
         goto out;
     }
 
     disk_super = dm_block_data(sblock);
     disk_super->flags = cpu_to_le32(pmd->flags);
 
     dm_bm_unlock(sblock);
 out:
     pmd_write_unlock(pmd);
     return r;
 }
 
 bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd)
 {
     bool needs_check;
 
     down_read(&pmd->root_lock);
     needs_check = pmd->flags & THIN_METADATA_NEEDS_CHECK_FLAG;
     up_read(&pmd->root_lock);
 
     return needs_check;
 }
 
 void dm_pool_issue_prefetches(struct dm_pool_metadata *pmd)
 {
     down_read(&pmd->root_lock);
     if (!pmd->fail_io)
         dm_tm_issue_prefetches(pmd->tm);
     up_read(&pmd->root_lock);
 }

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