1 files changed, 233 insertions, 80 deletions

diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index fbd3625f274..d2899e7eb3a 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -20,7 +20,13 @@
 
 #define CACHE_SUPERBLOCK_MAGIC 06142003
 #define CACHE_SUPERBLOCK_LOCATION 0
-#define CACHE_VERSION 1
+
+/*
+ * defines a range of metadata versions that this module can handle.
+ */
+#define MIN_CACHE_VERSION 1
+#define MAX_CACHE_VERSION 1
+
 #define CACHE_METADATA_CACHE_SIZE 64
 
 /*
@@ -83,6 +89,8 @@ struct cache_disk_superblock {
 	__le32 read_misses;
 	__le32 write_hits;
 	__le32 write_misses;
+
+	__le32 policy_version[CACHE_POLICY_VERSION_SIZE];
 } __packed;
 
 struct dm_cache_metadata {
@@ -101,7 +109,7 @@ struct dm_cache_metadata {
 	dm_block_t discard_root;
 
 	sector_t discard_block_size;
-	dm_dblock_t discard_nr_blocks;
+	dm_oblock_t discard_nr_blocks;
 
 	sector_t data_block_size;
 	dm_cblock_t cache_blocks;
@@ -109,8 +117,15 @@ struct dm_cache_metadata {
 	bool clean_when_opened:1;
 
 	char policy_name[CACHE_POLICY_NAME_SIZE];
+	unsigned policy_version[CACHE_POLICY_VERSION_SIZE];
 	size_t policy_hint_size;
 	struct dm_cache_statistics stats;
+
+	/*
+	 * Reading the space map root can fail, so we read it into this
+	 * buffer before the superblock is locked and updated.
+	 */
+	__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
 };
 
 /*-------------------------------------------------------------------
@@ -131,6 +146,18 @@ static void sb_prepare_for_write(struct dm_block_validator *v,
 						      SUPERBLOCK_CSUM_XOR));
 }
 
+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);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int sb_check(struct dm_block_validator *v,
 		    struct dm_block *b,
 		    size_t sb_block_size)
@@ -161,7 +188,7 @@ static int sb_check(struct dm_block_validator *v,
 		return -EILSEQ;
 	}
 
-	return 0;
+	return check_metadata_version(disk_super);
 }
 
 static struct dm_block_validator sb_validator = {
@@ -195,7 +222,7 @@ static int superblock_lock(struct dm_cache_metadata *cmd,
 
 /*----------------------------------------------------------------*/
 
-static int __superblock_all_zeroes(struct dm_block_manager *bm, int *result)
+static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
 {
 	int r;
 	unsigned i;
@@ -211,10 +238,10 @@ static int __superblock_all_zeroes(struct dm_block_manager *bm, int *result)
 		return r;
 
 	data_le = dm_block_data(b);
-	*result = 1;
+	*result = true;
 	for (i = 0; i < sb_block_size; i++) {
 		if (data_le[i] != zero) {
-			*result = 0;
+			*result = false;
 			break;
 		}
 	}
@@ -239,11 +266,31 @@ static void __setup_mapping_info(struct dm_cache_metadata *cmd)
 	}
 }
 
+static int __save_sm_root(struct dm_cache_metadata *cmd)
+{
+	int r;
+	size_t metadata_len;
+
+	r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
+	if (r < 0)
+		return r;
+
+	return dm_sm_copy_root(cmd->metadata_sm, &cmd->metadata_space_map_root,
+			       metadata_len);
+}
+
+static void __copy_sm_root(struct dm_cache_metadata *cmd,
+			   struct cache_disk_superblock *disk_super)
+{
+	memcpy(&disk_super->metadata_space_map_root,
+	       &cmd->metadata_space_map_root,
+	       sizeof(cmd->metadata_space_map_root));
+}
+
 static int __write_initial_superblock(struct dm_cache_metadata *cmd)
 {
 	int r;
 	struct dm_block *sblock;
-	size_t metadata_len;
 	struct cache_disk_superblock *disk_super;
 	sector_t bdev_size = i_size_read(cmd->bdev->bd_inode) >> SECTOR_SHIFT;
 
@@ -251,12 +298,16 @@ static int __write_initial_superblock(struct dm_cache_metadata *cmd)
 	if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS)
 		bdev_size = DM_CACHE_METADATA_MAX_SECTORS;
 
-	r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
+	r = dm_tm_pre_commit(cmd->tm);
 	if (r < 0)
 		return r;
 
-	r = dm_tm_pre_commit(cmd->tm);
-	if (r < 0)
+	/*
+	 * dm_sm_copy_root() can fail.  So we need to do it before we start
+	 * updating the superblock.
+	 */
+	r = __save_sm_root(cmd);
+	if (r)
 		return r;
 
 	r = superblock_lock_zero(cmd, &sblock);
@@ -267,24 +318,21 @@ 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(CACHE_VERSION);
-	memset(disk_super->policy_name, 0, CACHE_POLICY_NAME_SIZE);
+	disk_super->version = cpu_to_le32(MAX_CACHE_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;
 
-	r = dm_sm_copy_root(cmd->metadata_sm, &disk_super->metadata_space_map_root,
-			    metadata_len);
-	if (r < 0)
-		goto bad_locked;
+	__copy_sm_root(cmd, disk_super);
 
 	disk_super->mapping_root = cpu_to_le64(cmd->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);
-	disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
+	disk_super->discard_nr_blocks = cpu_to_le64(from_oblock(cmd->discard_nr_blocks));
 	disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
 	disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
 	disk_super->cache_blocks = cpu_to_le32(0);
-	memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
 
 	disk_super->read_hits = cpu_to_le32(0);
 	disk_super->read_misses = cpu_to_le32(0);
@@ -292,10 +340,6 @@ static int __write_initial_superblock(struct dm_cache_metadata *cmd)
 	disk_super->write_misses = cpu_to_le32(0);
 
 	return dm_tm_commit(cmd->tm, sblock);
-
-bad_locked:
-	dm_bm_unlock(sblock);
-	return r;
 }
 
 static int __format_metadata(struct dm_cache_metadata *cmd)
@@ -381,6 +425,15 @@ static int __open_metadata(struct dm_cache_metadata *cmd)
 
 	disk_super = dm_block_data(sblock);
 
+	/* Verify the data block size hasn't changed */
+	if (le32_to_cpu(disk_super->data_block_size) != cmd->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)cmd->data_block_size);
+		r = -EINVAL;
+		goto bad;
+	}
+
 	r = __check_incompat_features(disk_super, cmd);
 	if (r < 0)
 		goto bad;
@@ -408,7 +461,8 @@ bad:
 static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
 				     bool format_device)
 {
-	int r, unformatted;
+	int r;
+	bool unformatted = false;
 
 	r = __superblock_all_zeroes(cmd->bm, &unformatted);
 	if (r)
@@ -474,10 +528,13 @@ static void read_superblock_fields(struct dm_cache_metadata *cmd,
 	cmd->hint_root = le64_to_cpu(disk_super->hint_root);
 	cmd->discard_root = le64_to_cpu(disk_super->discard_root);
 	cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
-	cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks));
+	cmd->discard_nr_blocks = to_oblock(le64_to_cpu(disk_super->discard_nr_blocks));
 	cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
 	cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
 	strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
+	cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
+	cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
+	cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
 	cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
 
 	cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
@@ -505,8 +562,9 @@ static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
 	disk_super = dm_block_data(sblock);
 	update_flags(disk_super, mutator);
 	read_superblock_fields(cmd, disk_super);
+	dm_bm_unlock(sblock);
 
-	return dm_bm_flush_and_unlock(cmd->bm, sblock);
+	return dm_bm_flush(cmd->bm);
 }
 
 static int __begin_transaction(struct dm_cache_metadata *cmd)
@@ -534,7 +592,6 @@ static int __commit_transaction(struct dm_cache_metadata *cmd,
 				flags_mutator mutator)
 {
 	int r;
-	size_t metadata_len;
 	struct cache_disk_superblock *disk_super;
 	struct dm_block *sblock;
 
@@ -552,8 +609,8 @@ static int __commit_transaction(struct dm_cache_metadata *cmd,
 	if (r < 0)
 		return r;
 
-	r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
-	if (r < 0)
+	r = __save_sm_root(cmd);
+	if (r)
 		return r;
 
 	r = superblock_lock(cmd, &sblock);
@@ -569,21 +626,18 @@ static int __commit_transaction(struct dm_cache_metadata *cmd,
 	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);
-	disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
+	disk_super->discard_nr_blocks = cpu_to_le64(from_oblock(cmd->discard_nr_blocks));
 	disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
 	strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
+	disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
+	disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
+	disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
 
 	disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
 	disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
 	disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
 	disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
-
-	r = dm_sm_copy_root(cmd->metadata_sm, &disk_super->metadata_space_map_root,
-			    metadata_len);
-	if (r < 0) {
-		dm_bm_unlock(sblock);
-		return r;
-	}
+	__copy_sm_root(cmd, disk_super);
 
 	return dm_tm_commit(cmd->tm, sblock);
 }
@@ -657,19 +711,85 @@ void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
 	kfree(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)
+{
+	int r;
+	__le64 value;
+	dm_oblock_t ob;
+	unsigned flags;
+
+	r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
+	if (r) {
+		DMERR("block_unmapped_or_clean failed");
+		return r;
+	}
+
+	unpack_value(value, &ob, &flags);
+	*result = !((flags & M_VALID) && (flags & M_DIRTY));
+
+	return 0;
+}
+
+static int blocks_are_unmapped_or_clean(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)
+			return r;
+
+		if (!*result) {
+			DMERR("cache block %llu is dirty",
+			      (unsigned long long) from_cblock(begin));
+			return 0;
+		}
+
+		begin = to_cblock(from_cblock(begin) + 1);
+	}
+
+	return 0;
+}
+
 int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
 {
 	int r;
+	bool clean;
 	__le64 null_mapping = pack_value(0, 0);
 
 	down_write(&cmd->root_lock);
 	__dm_bless_for_disk(&null_mapping);
+
+	if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
+		r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
+		if (r) {
+			__dm_unbless_for_disk(&null_mapping);
+			goto out;
+		}
+
+		if (!clean) {
+			DMERR("unable to shrink cache due to dirty blocks");
+			r = -EINVAL;
+			__dm_unbless_for_disk(&null_mapping);
+			goto out;
+		}
+	}
+
 	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;
 	cmd->changed = true;
+
+out:
 	up_write(&cmd->root_lock);
 
 	return r;
@@ -677,15 +797,15 @@ int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
 
 int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
 				   sector_t discard_block_size,
-				   dm_dblock_t new_nr_entries)
+				   dm_oblock_t new_nr_entries)
 {
 	int r;
 
 	down_write(&cmd->root_lock);
 	r = dm_bitset_resize(&cmd->discard_info,
 			     cmd->discard_root,
-			     from_dblock(cmd->discard_nr_blocks),
-			     from_dblock(new_nr_entries),
+			     from_oblock(cmd->discard_nr_blocks),
+			     from_oblock(new_nr_entries),
 			     false, &cmd->discard_root);
 	if (!r) {
 		cmd->discard_block_size = discard_block_size;
@@ -698,28 +818,28 @@ int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
 	return r;
 }
 
-static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
+static int __set_discard(struct dm_cache_metadata *cmd, dm_oblock_t b)
 {
 	return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
-				 from_dblock(b), &cmd->discard_root);
+				 from_oblock(b), &cmd->discard_root);
 }
 
-static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
+static int __clear_discard(struct dm_cache_metadata *cmd, dm_oblock_t b)
 {
 	return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
-				   from_dblock(b), &cmd->discard_root);
+				   from_oblock(b), &cmd->discard_root);
 }
 
-static int __is_discarded(struct dm_cache_metadata *cmd, dm_dblock_t b,
+static int __is_discarded(struct dm_cache_metadata *cmd, dm_oblock_t b,
 			  bool *is_discarded)
 {
 	return dm_bitset_test_bit(&cmd->discard_info, cmd->discard_root,
-				  from_dblock(b), &cmd->discard_root,
+				  from_oblock(b), &cmd->discard_root,
 				  is_discarded);
 }
 
 static int __discard(struct dm_cache_metadata *cmd,
-		     dm_dblock_t dblock, bool discard)
+		     dm_oblock_t dblock, bool discard)
 {
 	int r;
 
@@ -732,7 +852,7 @@ static int __discard(struct dm_cache_metadata *cmd,
 }
 
 int dm_cache_set_discard(struct dm_cache_metadata *cmd,
-			 dm_dblock_t dblock, bool discard)
+			 dm_oblock_t dblock, bool discard)
 {
 	int r;
 
@@ -750,8 +870,8 @@ static int __load_discards(struct dm_cache_metadata *cmd,
 	dm_block_t b;
 	bool discard;
 
-	for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
-		dm_dblock_t dblock = to_dblock(b);
+	for (b = 0; b < from_oblock(cmd->discard_nr_blocks); b++) {
+		dm_oblock_t dblock = to_oblock(b);
 
 		if (cmd->clean_when_opened) {
 			r = __is_discarded(cmd, dblock, &discard);
@@ -854,18 +974,43 @@ struct thunk {
 	bool hints_valid;
 };
 
+static bool policy_unchanged(struct dm_cache_metadata *cmd,
+			     struct dm_cache_policy *policy)
+{
+	const char *policy_name = dm_cache_policy_get_name(policy);
+	const unsigned *policy_version = dm_cache_policy_get_version(policy);
+	size_t policy_hint_size = dm_cache_policy_get_hint_size(policy);
+
+	/*
+	 * Ensure policy names match.
+	 */
+	if (strncmp(cmd->policy_name, policy_name, sizeof(cmd->policy_name)))
+		return false;
+
+	/*
+	 * Ensure policy major versions match.
+	 */
+	if (cmd->policy_version[0] != policy_version[0])
+		return false;
+
+	/*
+	 * Ensure policy hint sizes match.
+	 */
+	if (cmd->policy_hint_size != policy_hint_size)
+		return false;
+
+	return true;
+}
+
 static bool hints_array_initialized(struct dm_cache_metadata *cmd)
 {
 	return cmd->hint_root && cmd->policy_hint_size;
 }
 
 static bool hints_array_available(struct dm_cache_metadata *cmd,
-				  const char *policy_name)
+				  struct dm_cache_policy *policy)
 {
-	bool policy_names_match = !strncmp(cmd->policy_name, policy_name,
-					   sizeof(cmd->policy_name));
-
-	return cmd->clean_when_opened && policy_names_match &&
+	return cmd->clean_when_opened && policy_unchanged(cmd, policy) &&
 		hints_array_initialized(cmd);
 }
 
@@ -899,7 +1044,8 @@ static int __load_mapping(void *context, uint64_t cblock, void *leaf)
 	return r;
 }
 
-static int __load_mappings(struct dm_cache_metadata *cmd, const char *policy_name,
+static int __load_mappings(struct dm_cache_metadata *cmd,
+			   struct dm_cache_policy *policy,
 			   load_mapping_fn fn, void *context)
 {
 	struct thunk thunk;
@@ -909,18 +1055,19 @@ static int __load_mappings(struct dm_cache_metadata *cmd, const char *policy_nam
 
 	thunk.cmd = cmd;
 	thunk.respect_dirty_flags = cmd->clean_when_opened;
-	thunk.hints_valid = hints_array_available(cmd, policy_name);
+	thunk.hints_valid = hints_array_available(cmd, policy);
 
 	return dm_array_walk(&cmd->info, cmd->root, __load_mapping, &thunk);
 }
 
-int dm_cache_load_mappings(struct dm_cache_metadata *cmd, const char *policy_name,
+int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
+			   struct dm_cache_policy *policy,
 			   load_mapping_fn fn, void *context)
 {
 	int r;
 
 	down_read(&cmd->root_lock);
-	r = __load_mappings(cmd, policy_name, fn, context);
+	r = __load_mappings(cmd, policy, fn, context);
 	up_read(&cmd->root_lock);
 
 	return r;
@@ -979,7 +1126,7 @@ static int __dirty(struct dm_cache_metadata *cmd, dm_cblock_t cblock, bool dirty
 		/* nothing to be done */
 		return 0;
 
-	value = pack_value(oblock, flags | (dirty ? M_DIRTY : 0));
+	value = pack_value(oblock, (flags & ~M_DIRTY) | (dirty ? M_DIRTY : 0));
 	__dm_bless_for_disk(&value);
 
 	r = dm_array_set_value(&cmd->info, cmd->root, from_cblock(cblock),
@@ -1008,7 +1155,7 @@ void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
 				 struct dm_cache_statistics *stats)
 {
 	down_read(&cmd->root_lock);
-	memcpy(stats, &cmd->stats, sizeof(*stats));
+	*stats = cmd->stats;
 	up_read(&cmd->root_lock);
 }
 
@@ -1016,7 +1163,7 @@ void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
 				 struct dm_cache_statistics *stats)
 {
 	down_write(&cmd->root_lock);
-	memcpy(&cmd->stats, stats, sizeof(*stats));
+	cmd->stats = *stats;
 	up_write(&cmd->root_lock);
 }
 
@@ -1070,13 +1217,15 @@ static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *po
 	__le32 value;
 	size_t hint_size;
 	const char *policy_name = dm_cache_policy_get_name(policy);
+	const unsigned *policy_version = dm_cache_policy_get_version(policy);
 
 	if (!policy_name[0] ||
 	    (strlen(policy_name) > sizeof(cmd->policy_name) - 1))
 		return -EINVAL;
 
-	if (strcmp(cmd->policy_name, policy_name)) {
+	if (!policy_unchanged(cmd, policy)) {
 		strncpy(cmd->policy_name, policy_name, sizeof(cmd->policy_name));
+		memcpy(cmd->policy_version, policy_version, sizeof(cmd->policy_version));
 
 		hint_size = dm_cache_policy_get_hint_size(policy);
 		if (!hint_size)
@@ -1105,22 +1254,12 @@ static int begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *po
 	return 0;
 }
 
-int dm_cache_begin_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
+static int save_hint(void *context, dm_cblock_t cblock, dm_oblock_t oblock, uint32_t hint)
 {
+	struct dm_cache_metadata *cmd = context;
+	__le32 value = cpu_to_le32(hint);
 	int r;
 
-	down_write(&cmd->root_lock);
-	r = begin_hints(cmd, policy);
-	up_write(&cmd->root_lock);
-
-	return r;
-}
-
-static int save_hint(struct dm_cache_metadata *cmd, dm_cblock_t cblock,
-		     uint32_t hint)
-{
-	int r;
-	__le32 value = cpu_to_le32(hint);
 	__dm_bless_for_disk(&value);
 
 	r = dm_array_set_value(&cmd->hint_info, cmd->hint_root,
@@ -1130,17 +1269,31 @@ static int save_hint(struct dm_cache_metadata *cmd, dm_cblock_t cblock,
 	return r;
 }
 
-int dm_cache_save_hint(struct dm_cache_metadata *cmd, dm_cblock_t cblock,
-		       uint32_t hint)
+static int write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
 {
 	int r;
 
-	if (!hints_array_initialized(cmd))
-		return 0;
+	r = begin_hints(cmd, policy);
+	if (r) {
+		DMERR("begin_hints failed");
+		return r;
+	}
+
+	return policy_walk_mappings(policy, save_hint, cmd);
+}
+
+int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *policy)
+{
+	int r;
 
 	down_write(&cmd->root_lock);
-	r = save_hint(cmd, cblock, hint);
+	r = write_hints(cmd, policy);
 	up_write(&cmd->root_lock);
 
 	return r;
 }
+
+int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result)
+{
+	return blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result);
+}