dm cache metadata: add "metadata2" feature

If "metadata2" is provided as a table argument when creating/loading a
cache target a more compact metadata format, with separate dirty bits,
is used.  "metadata2" improves speed of shutting down a cache target.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt
index 785eab87aa71dc68aceeb970676a614c9c2c6381..f228604ddbcd6890c1db0ef2778422a499cbd480 100644 (file)
--- a/Documentation/device-mapper/cache.txt
+++ b/Documentation/device-mapper/cache.txt
@@ -207,6 +207,10 @@ Optional feature arguments are:
                   block, then the cache block is invalidated.
                   To enable passthrough mode the cache must be clean.
 
+   metadata2   : use version 2 of the metadata.  This stores the dirty bits
+                  in a separate btree, which improves speed of shutting
+                 down the cache.
+
 A policy called 'default' is always registered.  This is an alias for
 the policy we currently think is giving best all round performance.
 

diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 9364a02e1646f38f7df07e2c257d7118a7788e42..0610be7846dc4d5da545fe4cd1a979ecd0794d8d 100644 (file)
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -25,7 +25,7 @@
  * defines a range of metadata versions that this module can handle.
  */
 #define MIN_CACHE_VERSION 1
-#define MAX_CACHE_VERSION 1
+#define MAX_CACHE_VERSION 2
 
 #define CACHE_METADATA_CACHE_SIZE 64
 
@@ -55,6 +55,7 @@ enum mapping_bits {
 
        /*
         * The data on the cache is different from that on the origin.
+        * This flag is only used by metadata format 1.
         */
        M_DIRTY = 2
 };
@@ -93,12 +94,18 @@ struct cache_disk_superblock {
        __le32 write_misses;
 
        __le32 policy_version[CACHE_POLICY_VERSION_SIZE];
+
+       /*
+        * Metadata format 2 fields.
+        */
+       __le64 dirty_root;
 } __packed;
 
 struct dm_cache_metadata {
        atomic_t ref_count;
        struct list_head list;
 
+       unsigned version;
        struct block_device *bdev;
        struct dm_block_manager *bm;
        struct dm_space_map *metadata_sm;
@@ -141,12 +148,19 @@ struct dm_cache_metadata {
         */
        bool fail_io:1;
 
+       /*
+        * Metadata format 2 fields.
+        */
+       dm_block_t dirty_root;
+       struct dm_disk_bitset dirty_info;
+
        /*
         * These structures are used when loading metadata.  They're too
         * big to put on the stack.
         */
        struct dm_array_cursor mapping_cursor;
        struct dm_array_cursor hint_cursor;
+       struct dm_bitset_cursor dirty_cursor;
 };
 
 /*-------------------------------------------------------------------
@@ -170,6 +184,7 @@ static void sb_prepare_for_write(struct dm_block_validator *v,
 static int check_metadata_version(struct cache_disk_superblock *disk_super)
 {
        uint32_t metadata_version = le32_to_cpu(disk_super->version);
+
        if (metadata_version < MIN_CACHE_VERSION || metadata_version > MAX_CACHE_VERSION) {
                DMERR("Cache metadata version %u found, but only versions between %u and %u supported.",
                      metadata_version, MIN_CACHE_VERSION, MAX_CACHE_VERSION);
@@ -310,6 +325,11 @@ static void __copy_sm_root(struct dm_cache_metadata *cmd,
               sizeof(cmd->metadata_space_map_root));
 }
 
+static bool separate_dirty_bits(struct dm_cache_metadata *cmd)
+{
+       return cmd->version >= 2;
+}
+
 static int __write_initial_superblock(struct dm_cache_metadata *cmd)
 {
        int r;
@@ -341,7 +361,7 @@ static int __write_initial_superblock(struct dm_cache_metadata *cmd)
        disk_super->flags = 0;
        memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
        disk_super->magic = cpu_to_le64(CACHE_SUPERBLOCK_MAGIC);
-       disk_super->version = cpu_to_le32(MAX_CACHE_VERSION);
+       disk_super->version = cpu_to_le32(cmd->version);
        memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
        memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version));
        disk_super->policy_hint_size = 0;
@@ -362,6 +382,9 @@ static int __write_initial_superblock(struct dm_cache_metadata *cmd)
        disk_super->write_hits = cpu_to_le32(0);
        disk_super->write_misses = cpu_to_le32(0);
 
+       if (separate_dirty_bits(cmd))
+               disk_super->dirty_root = cpu_to_le64(cmd->dirty_root);
+
        return dm_tm_commit(cmd->tm, sblock);
 }
 
@@ -382,6 +405,13 @@ static int __format_metadata(struct dm_cache_metadata *cmd)
        if (r < 0)
                goto bad;
 
+       if (separate_dirty_bits(cmd)) {
+               dm_disk_bitset_init(cmd->tm, &cmd->dirty_info);
+               r = dm_bitset_empty(&cmd->dirty_info, &cmd->dirty_root);
+               if (r < 0)
+                       goto bad;
+       }
+
        dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
        r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root);
        if (r < 0)
@@ -407,9 +437,10 @@ bad:
 static int __check_incompat_features(struct cache_disk_superblock *disk_super,
                                     struct dm_cache_metadata *cmd)
 {
-       uint32_t features;
+       uint32_t incompat_flags, features;
 
-       features = le32_to_cpu(disk_super->incompat_flags) & ~DM_CACHE_FEATURE_INCOMPAT_SUPP;
+       incompat_flags = le32_to_cpu(disk_super->incompat_flags);
+       features = incompat_flags & ~DM_CACHE_FEATURE_INCOMPAT_SUPP;
        if (features) {
                DMERR("could not access metadata due to unsupported optional features (%lx).",
                      (unsigned long)features);
@@ -470,6 +501,7 @@ static int __open_metadata(struct dm_cache_metadata *cmd)
        }
 
        __setup_mapping_info(cmd);
+       dm_disk_bitset_init(cmd->tm, &cmd->dirty_info);
        dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
        sb_flags = le32_to_cpu(disk_super->flags);
        cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
@@ -548,6 +580,7 @@ static unsigned long clear_clean_shutdown(unsigned long flags)
 static void read_superblock_fields(struct dm_cache_metadata *cmd,
                                   struct cache_disk_superblock *disk_super)
 {
+       cmd->version = le32_to_cpu(disk_super->version);
        cmd->flags = le32_to_cpu(disk_super->flags);
        cmd->root = le64_to_cpu(disk_super->mapping_root);
        cmd->hint_root = le64_to_cpu(disk_super->hint_root);
@@ -567,6 +600,9 @@ static void read_superblock_fields(struct dm_cache_metadata *cmd,
        cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
        cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
 
+       if (separate_dirty_bits(cmd))
+               cmd->dirty_root = le64_to_cpu(disk_super->dirty_root);
+
        cmd->changed = false;
 }
 
@@ -625,6 +661,13 @@ static int __commit_transaction(struct dm_cache_metadata *cmd,
         */
        BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
 
+       if (separate_dirty_bits(cmd)) {
+               r = dm_bitset_flush(&cmd->dirty_info, cmd->dirty_root,
+                                   &cmd->dirty_root);
+               if (r)
+                       return r;
+       }
+
        r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
                            &cmd->discard_root);
        if (r)
@@ -649,6 +692,8 @@ static int __commit_transaction(struct dm_cache_metadata *cmd,
                update_flags(disk_super, mutator);
 
        disk_super->mapping_root = cpu_to_le64(cmd->root);
+       if (separate_dirty_bits(cmd))
+               disk_super->dirty_root = cpu_to_le64(cmd->dirty_root);
        disk_super->hint_root = cpu_to_le64(cmd->hint_root);
        disk_super->discard_root = cpu_to_le64(cmd->discard_root);
        disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
@@ -698,7 +743,8 @@ static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
 static struct dm_cache_metadata *metadata_open(struct block_device *bdev,
                                               sector_t data_block_size,
                                               bool may_format_device,
-                                              size_t policy_hint_size)
+                                              size_t policy_hint_size,
+                                              unsigned metadata_version)
 {
        int r;
        struct dm_cache_metadata *cmd;
@@ -709,6 +755,7 @@ static struct dm_cache_metadata *metadata_open(struct block_device *bdev,
                return ERR_PTR(-ENOMEM);
        }
 
+       cmd->version = metadata_version;
        atomic_set(&cmd->ref_count, 1);
        init_rwsem(&cmd->root_lock);
        cmd->bdev = bdev;
@@ -757,7 +804,8 @@ static struct dm_cache_metadata *lookup(struct block_device *bdev)
 static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev,
                                                sector_t data_block_size,
                                                bool may_format_device,
-                                               size_t policy_hint_size)
+                                               size_t policy_hint_size,
+                                               unsigned metadata_version)
 {
        struct dm_cache_metadata *cmd, *cmd2;
 
@@ -768,7 +816,8 @@ static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev,
        if (cmd)
                return cmd;
 
-       cmd = metadata_open(bdev, data_block_size, may_format_device, policy_hint_size);
+       cmd = metadata_open(bdev, data_block_size, may_format_device,
+                           policy_hint_size, metadata_version);
        if (!IS_ERR(cmd)) {
                mutex_lock(&table_lock);
                cmd2 = lookup(bdev);
@@ -800,10 +849,11 @@ static bool same_params(struct dm_cache_metadata *cmd, sector_t data_block_size)
 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
                                                 sector_t data_block_size,
                                                 bool may_format_device,
-                                                size_t policy_hint_size)
+                                                size_t policy_hint_size,
+                                                unsigned metadata_version)
 {
-       struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size,
-                                                      may_format_device, policy_hint_size);
+       struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size, may_format_device,
+                                                      policy_hint_size, metadata_version);
 
        if (!IS_ERR(cmd) && !same_params(cmd, data_block_size)) {
                dm_cache_metadata_close(cmd);
@@ -829,8 +879,8 @@ void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
 /*
  * Checks that the given cache block is either unmapped or clean.
  */
-static int block_unmapped_or_clean(struct dm_cache_metadata *cmd, dm_cblock_t b,
-                                  bool *result)
+static int block_clean_combined_dirty(struct dm_cache_metadata *cmd, dm_cblock_t b,
+                                     bool *result)
 {
        int r;
        __le64 value;
@@ -838,10 +888,8 @@ static int block_unmapped_or_clean(struct dm_cache_metadata *cmd, dm_cblock_t b,
        unsigned flags;
 
        r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
-       if (r) {
-               DMERR("block_unmapped_or_clean failed");
+       if (r)
                return r;
-       }
 
        unpack_value(value, &ob, &flags);
        *result = !((flags & M_VALID) && (flags & M_DIRTY));
@@ -849,17 +897,19 @@ static int block_unmapped_or_clean(struct dm_cache_metadata *cmd, dm_cblock_t b,
        return 0;
 }
 
-static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
-                                       dm_cblock_t begin, dm_cblock_t end,
-                                       bool *result)
+static int blocks_are_clean_combined_dirty(struct dm_cache_metadata *cmd,
+                                          dm_cblock_t begin, dm_cblock_t end,
+                                          bool *result)
 {
        int r;
        *result = true;
 
        while (begin != end) {
-               r = block_unmapped_or_clean(cmd, begin, result);
-               if (r)
+               r = block_clean_combined_dirty(cmd, begin, result);
+               if (r) {
+                       DMERR("block_clean_combined_dirty failed");
                        return r;
+               }
 
                if (!*result) {
                        DMERR("cache block %llu is dirty",
@@ -873,6 +923,48 @@ static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
        return 0;
 }
 
+static int blocks_are_clean_separate_dirty(struct dm_cache_metadata *cmd,
+                                          dm_cblock_t begin, dm_cblock_t end,
+                                          bool *result)
+{
+       int r;
+       bool dirty_flag;
+       *result = true;
+
+       // FIXME: use a cursor so we can benefit from preloading metadata.
+       while (begin != end) {
+               /*
+                * We assume that unmapped blocks have their dirty bit
+                * cleared.
+                */
+               r = dm_bitset_test_bit(&cmd->dirty_info, cmd->dirty_root,
+                                      from_cblock(begin), &cmd->dirty_root, &dirty_flag);
+               if (r)
+                       return r;
+
+               if (dirty_flag) {
+                       DMERR("cache block %llu is dirty",
+                             (unsigned long long) from_cblock(begin));
+                       *result = false;
+                       return 0;
+               }
+
+               begin = to_cblock(from_cblock(begin) + 1);
+       }
+
+       return 0;
+}
+
+static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
+                                       dm_cblock_t begin, dm_cblock_t end,
+                                       bool *result)
+{
+       if (separate_dirty_bits(cmd))
+               return blocks_are_clean_separate_dirty(cmd, begin, end, result);
+       else
+               return blocks_are_clean_combined_dirty(cmd, begin, end, result);
+}
+
 static bool cmd_write_lock(struct dm_cache_metadata *cmd)
 {
        down_write(&cmd->root_lock);
@@ -950,8 +1042,18 @@ int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
        r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
                            from_cblock(new_cache_size),
                            &null_mapping, &cmd->root);
-       if (!r)
-               cmd->cache_blocks = new_cache_size;
+       if (r)
+               goto out;
+
+       if (separate_dirty_bits(cmd)) {
+               r = dm_bitset_resize(&cmd->dirty_info, cmd->dirty_root,
+                                    from_cblock(cmd->cache_blocks), from_cblock(new_cache_size),
+                                    false, &cmd->dirty_root);
+               if (r)
+                       goto out;
+       }
+
+       cmd->cache_blocks = new_cache_size;
        cmd->changed = true;
 
 out:
@@ -1185,11 +1287,11 @@ static bool hints_array_available(struct dm_cache_metadata *cmd,
                hints_array_initialized(cmd);
 }
 
-static int __load_mapping(struct dm_cache_metadata *cmd,
-                         uint64_t cb, bool hints_valid,
-                         struct dm_array_cursor *mapping_cursor,
-                         struct dm_array_cursor *hint_cursor,
-                         load_mapping_fn fn, void *context)
+static int __load_mapping_v1(struct dm_cache_metadata *cmd,
+                            uint64_t cb, bool hints_valid,
+                            struct dm_array_cursor *mapping_cursor,
+                            struct dm_array_cursor *hint_cursor,
+                            load_mapping_fn fn, void *context)
 {
        int r = 0;
 
@@ -1221,6 +1323,45 @@ static int __load_mapping(struct dm_cache_metadata *cmd,
        return r;
 }
 
+static int __load_mapping_v2(struct dm_cache_metadata *cmd,
+                            uint64_t cb, bool hints_valid,
+                            struct dm_array_cursor *mapping_cursor,
+                            struct dm_array_cursor *hint_cursor,
+                            struct dm_bitset_cursor *dirty_cursor,
+                            load_mapping_fn fn, void *context)
+{
+       int r = 0;
+
+       __le64 mapping;
+       __le32 hint = 0;
+
+       __le64 *mapping_value_le;
+       __le32 *hint_value_le;
+
+       dm_oblock_t oblock;
+       unsigned flags;
+       bool dirty;
+
+       dm_array_cursor_get_value(mapping_cursor, (void **) &mapping_value_le);
+       memcpy(&mapping, mapping_value_le, sizeof(mapping));
+       unpack_value(mapping, &oblock, &flags);
+
+       if (flags & M_VALID) {
+               if (hints_valid) {
+                       dm_array_cursor_get_value(hint_cursor, (void **) &hint_value_le);
+                       memcpy(&hint, hint_value_le, sizeof(hint));
+               }
+
+               dirty = dm_bitset_cursor_get_value(dirty_cursor);
+               r = fn(context, oblock, to_cblock(cb), dirty,
+                      le32_to_cpu(hint), hints_valid);
+               if (r)
+                       DMERR("policy couldn't load cblock");
+       }
+
+       return r;
+}
+
 static int __load_mappings(struct dm_cache_metadata *cmd,
                           struct dm_cache_policy *policy,
                           load_mapping_fn fn, void *context)
@@ -1246,10 +1387,28 @@ static int __load_mappings(struct dm_cache_metadata *cmd,
                }
        }
 
+       if (separate_dirty_bits(cmd)) {
+               r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
+                                          from_cblock(cmd->cache_blocks),
+                                          &cmd->dirty_cursor);
+               if (r) {
+                       dm_array_cursor_end(&cmd->hint_cursor);
+                       dm_array_cursor_end(&cmd->mapping_cursor);
+                       return r;
+               }
+       }
+
        for (cb = 0; ; cb++) {
-               r = __load_mapping(cmd, cb, hints_valid,
-                                  &cmd->mapping_cursor, &cmd->hint_cursor,
-                                  fn, context);
+               if (separate_dirty_bits(cmd))
+                       r = __load_mapping_v2(cmd, cb, hints_valid,
+                                             &cmd->mapping_cursor,
+                                             &cmd->hint_cursor,
+                                             &cmd->dirty_cursor,
+                                             fn, context);
+               else
+                       r = __load_mapping_v1(cmd, cb, hints_valid,
+                                             &cmd->mapping_cursor, &cmd->hint_cursor,
+                                             fn, context);
                if (r)
                        goto out;
 
@@ -1272,12 +1431,23 @@ static int __load_mappings(struct dm_cache_metadata *cmd,
                                goto out;
                        }
                }
+
+               if (separate_dirty_bits(cmd)) {
+                       r = dm_bitset_cursor_next(&cmd->dirty_cursor);
+                       if (r) {
+                               DMERR("dm_bitset_cursor_next for dirty failed");
+                               goto out;
+                       }
+               }
        }
 out:
        dm_array_cursor_end(&cmd->mapping_cursor);
        if (hints_valid)
                dm_array_cursor_end(&cmd->hint_cursor);
 
+       if (separate_dirty_bits(cmd))
+               dm_bitset_cursor_end(&cmd->dirty_cursor);
+
        return r;
 }
 
@@ -1360,13 +1530,55 @@ static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty
 
 }
 
-int dm_cache_set_dirty(struct dm_cache_metadata *cmd,
-                      dm_cblock_t cblock, bool dirty)
+static int __set_dirty_bits_v1(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
+{
+       int r;
+       unsigned i;
+       for (i = 0; i < nr_bits; i++) {
+               r = __dirty(cmd, to_cblock(i), test_bit(i, bits));
+               if (r)
+                       return r;
+       }
+
+       return 0;
+}
+
+static int __set_dirty_bits_v2(struct dm_cache_metadata *cmd, unsigned nr_bits, unsigned long *bits)
+{
+       int r = 0;
+       unsigned i;
+
+       /* nr_bits is really just a sanity check */
+       if (nr_bits != from_cblock(cmd->cache_blocks)) {
+               DMERR("dirty bitset is wrong size");
+               return -EINVAL;
+       }
+
+       for (i = 0; i < nr_bits; i++) {
+               if (test_bit(i, bits))
+                       r = dm_bitset_set_bit(&cmd->dirty_info, cmd->dirty_root, i, &cmd->dirty_root);
+               else
+                       r = dm_bitset_clear_bit(&cmd->dirty_info, cmd->dirty_root, i, &cmd->dirty_root);
+
+               if (r)
+                       return r;
+       }
+
+       cmd->changed = true;
+       return dm_bitset_flush(&cmd->dirty_info, cmd->dirty_root, &cmd->dirty_root);
+}
+
+int dm_cache_set_dirty_bits(struct dm_cache_metadata *cmd,
+                           unsigned nr_bits,
+                           unsigned long *bits)
 {
        int r;
 
        WRITE_LOCK(cmd);
-       r = __dirty(cmd, cblock, dirty);
+       if (separate_dirty_bits(cmd))
+               r = __set_dirty_bits_v2(cmd, nr_bits, bits);
+       else
+               r = __set_dirty_bits_v1(cmd, nr_bits, bits);
        WRITE_UNLOCK(cmd);
 
        return r;

diff --git a/drivers/md/dm-cache-metadata.h b/drivers/md/dm-cache-metadata.h
index 8528744195e53aeecbbe52688b8ae40d2200c339..4f07c08cf1070ca0872348283f33da58c80d53e9 100644 (file)
--- a/drivers/md/dm-cache-metadata.h
+++ b/drivers/md/dm-cache-metadata.h
@@ -45,18 +45,20 @@
  * As these various flags are defined they should be added to the
  * following masks.
  */
+
 #define DM_CACHE_FEATURE_COMPAT_SUPP     0UL
 #define DM_CACHE_FEATURE_COMPAT_RO_SUPP          0UL
 #define DM_CACHE_FEATURE_INCOMPAT_SUPP   0UL
 
 /*
- * Reopens or creates a new, empty metadata volume.
- * Returns an ERR_PTR on failure.
+ * Reopens or creates a new, empty metadata volume.  Returns an ERR_PTR on
+ * failure.  If reopening then features must match.
  */
 struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
                                                 sector_t data_block_size,
                                                 bool may_format_device,
-                                                size_t policy_hint_size);
+                                                size_t policy_hint_size,
+                                                unsigned metadata_version);
 
 void dm_cache_metadata_close(struct dm_cache_metadata *cmd);
 
@@ -91,7 +93,8 @@ int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
                           load_mapping_fn fn,
                           void *context);
 
-int dm_cache_set_dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty);
+int dm_cache_set_dirty_bits(struct dm_cache_metadata *cmd,
+                           unsigned nr_bits, unsigned long *bits);
 
 struct dm_cache_statistics {
        uint32_t read_hits;

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 897dc72f07c90eaedebcc377b2dac10c568761e6..5813d2a7eefe4f1121a3b5509eeca232785974f8 100644 (file)
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -179,6 +179,7 @@ enum cache_io_mode {
 struct cache_features {
        enum cache_metadata_mode mode;
        enum cache_io_mode io_mode;
+       unsigned metadata_version;
 };
 
 struct cache_stats {
@@ -2541,13 +2542,14 @@ static void init_features(struct cache_features *cf)
 {
        cf->mode = CM_WRITE;
        cf->io_mode = CM_IO_WRITEBACK;
+       cf->metadata_version = 1;
 }
 
 static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
                          char **error)
 {
        static struct dm_arg _args[] = {
-               {0, 1, "Invalid number of cache feature arguments"},
+               {0, 2, "Invalid number of cache feature arguments"},
        };
 
        int r;
@@ -2573,6 +2575,9 @@ static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
                else if (!strcasecmp(arg, "passthrough"))
                        cf->io_mode = CM_IO_PASSTHROUGH;
 
+               else if (!strcasecmp(arg, "metadata2"))
+                       cf->metadata_version = 2;
+
                else {
                        *error = "Unrecognised cache feature requested";
                        return -EINVAL;
@@ -2827,7 +2832,8 @@ static int cache_create(struct cache_args *ca, struct cache **result)
 
        cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
                                     ca->block_size, may_format,
-                                    dm_cache_policy_get_hint_size(cache->policy));
+                                    dm_cache_policy_get_hint_size(cache->policy),
+                                    ca->features.metadata_version);
        if (IS_ERR(cmd)) {
                *error = "Error creating metadata object";
                r = PTR_ERR(cmd);
@@ -3172,21 +3178,16 @@ static int cache_end_io(struct dm_target *ti, struct bio *bio, int error)
 
 static int write_dirty_bitset(struct cache *cache)
 {
-       unsigned i, r;
+       int r;
 
        if (get_cache_mode(cache) >= CM_READ_ONLY)
                return -EINVAL;
 
-       for (i = 0; i < from_cblock(cache->cache_size); i++) {
-               r = dm_cache_set_dirty(cache->cmd, to_cblock(i),
-                                      is_dirty(cache, to_cblock(i)));
-               if (r) {
-                       metadata_operation_failed(cache, "dm_cache_set_dirty", r);
-                       return r;
-               }
-       }
+       r = dm_cache_set_dirty_bits(cache->cmd, from_cblock(cache->cache_size), cache->dirty_bitset);
+       if (r)
+               metadata_operation_failed(cache, "dm_cache_set_dirty_bits", r);
 
-       return 0;
+       return r;
 }
 
 static int write_discard_bitset(struct cache *cache)
@@ -3562,14 +3563,19 @@ static void cache_status(struct dm_target *ti, status_type_t type,
                       (unsigned) atomic_read(&cache->stats.promotion),
                       (unsigned long) atomic_read(&cache->nr_dirty));
 
+               if (cache->features.metadata_version == 2)
+                       DMEMIT("2 metadata2 ");
+               else
+                       DMEMIT("1 ");
+
                if (writethrough_mode(&cache->features))
-                       DMEMIT("1 writethrough ");
+                       DMEMIT("writethrough ");
 
                else if (passthrough_mode(&cache->features))
-                       DMEMIT("1 passthrough ");
+                       DMEMIT("passthrough ");
 
                else if (writeback_mode(&cache->features))
-                       DMEMIT("1 writeback ");
+                       DMEMIT("writeback ");
 
                else {
                        DMERR("%s: internal error: unknown io mode: %d",
@@ -3817,7 +3823,7 @@ static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
 
 static struct target_type cache_target = {
        .name = "cache",
-       .version = {1, 9, 0},
+       .version = {1, 10, 0},
        .module = THIS_MODULE,
        .ctr = cache_ctr,
        .dtr = cache_dtr,