From: Mike Snitzer Separate dm cache policy version string into 3 unsigned numbers corresponding to major, minor and patchlevel and store them at the end of the on-disk metadata so we know which version of the policy generated the hints in case a future version wants to use them differently. Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- drivers/md/dm-cache-metadata.c | 15 +++++++++++++-- drivers/md/dm-cache-policy-cleaner.c | 7 +++++-- drivers/md/dm-cache-policy-internal.h | 2 ++ drivers/md/dm-cache-policy-mq.c | 8 ++++++-- drivers/md/dm-cache-policy.c | 8 ++++++++ drivers/md/dm-cache-policy.h | 2 ++ 6 files changed, 36 insertions(+), 6 deletions(-) Index: linux/drivers/md/dm-cache-metadata.c =================================================================== --- linux.orig/drivers/md/dm-cache-metadata.c +++ linux/drivers/md/dm-cache-metadata.c @@ -83,6 +83,8 @@ 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 { @@ -109,6 +111,7 @@ 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; }; @@ -268,7 +271,8 @@ static int __write_initial_superblock(st 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); + 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, @@ -284,7 +288,6 @@ static int __write_initial_superblock(st 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); @@ -478,6 +481,9 @@ static void read_superblock_fields(struc 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); @@ -572,6 +578,9 @@ static int __commit_transaction(struct d disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(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); @@ -1070,6 +1079,7 @@ static int begin_hints(struct dm_cache_m __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)) @@ -1077,6 +1087,7 @@ static int begin_hints(struct dm_cache_m if (strcmp(cmd->policy_name, policy_name)) { 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) Index: linux/drivers/md/dm-cache-policy-cleaner.c =================================================================== --- linux.orig/drivers/md/dm-cache-policy-cleaner.c +++ linux/drivers/md/dm-cache-policy-cleaner.c @@ -17,7 +17,6 @@ /*----------------------------------------------------------------*/ #define DM_MSG_PREFIX "cache cleaner" -#define CLEANER_VERSION "1.0.0" /* Cache entry struct. */ struct wb_cache_entry { @@ -434,6 +433,7 @@ static struct dm_cache_policy *wb_create static struct dm_cache_policy_type wb_policy_type = { .name = "cleaner", + .version = {1, 0, 0}, .hint_size = 0, .owner = THIS_MODULE, .create = wb_create @@ -446,7 +446,10 @@ static int __init wb_init(void) if (r < 0) DMERR("register failed %d", r); else - DMINFO("version " CLEANER_VERSION " loaded"); + DMINFO("version %u.%u.%u loaded", + wb_policy_type.version[0], + wb_policy_type.version[1], + wb_policy_type.version[2]); return r; } Index: linux/drivers/md/dm-cache-policy-internal.h =================================================================== --- linux.orig/drivers/md/dm-cache-policy-internal.h +++ linux/drivers/md/dm-cache-policy-internal.h @@ -117,6 +117,8 @@ void dm_cache_policy_destroy(struct dm_c */ const char *dm_cache_policy_get_name(struct dm_cache_policy *p); +const unsigned *dm_cache_policy_get_version(struct dm_cache_policy *p); + size_t dm_cache_policy_get_hint_size(struct dm_cache_policy *p); /*----------------------------------------------------------------*/ Index: linux/drivers/md/dm-cache-policy-mq.c =================================================================== --- linux.orig/drivers/md/dm-cache-policy-mq.c +++ linux/drivers/md/dm-cache-policy-mq.c @@ -14,7 +14,6 @@ #include #define DM_MSG_PREFIX "cache-policy-mq" -#define MQ_VERSION "1.0.0" static struct kmem_cache *mq_entry_cache; @@ -1133,6 +1132,7 @@ bad_cache_alloc: static struct dm_cache_policy_type mq_policy_type = { .name = "mq", + .version = {1, 0, 0}, .hint_size = 4, .owner = THIS_MODULE, .create = mq_create @@ -1140,6 +1140,7 @@ static struct dm_cache_policy_type mq_po static struct dm_cache_policy_type default_policy_type = { .name = "default", + .version = {1, 0, 0}, .hint_size = 4, .owner = THIS_MODULE, .create = mq_create @@ -1164,7 +1165,10 @@ static int __init mq_init(void) r = dm_cache_policy_register(&default_policy_type); if (!r) { - DMINFO("version " MQ_VERSION " loaded"); + DMINFO("version %u.%u.%u loaded", + mq_policy_type.version[0], + mq_policy_type.version[1], + mq_policy_type.version[2]); return 0; } Index: linux/drivers/md/dm-cache-policy.c =================================================================== --- linux.orig/drivers/md/dm-cache-policy.c +++ linux/drivers/md/dm-cache-policy.c @@ -150,6 +150,14 @@ const char *dm_cache_policy_get_name(str } EXPORT_SYMBOL_GPL(dm_cache_policy_get_name); +const unsigned *dm_cache_policy_get_version(struct dm_cache_policy *p) +{ + struct dm_cache_policy_type *t = p->private; + + return t->version; +} +EXPORT_SYMBOL_GPL(dm_cache_policy_get_version); + size_t dm_cache_policy_get_hint_size(struct dm_cache_policy *p) { struct dm_cache_policy_type *t = p->private; Index: linux/drivers/md/dm-cache-policy.h =================================================================== --- linux.orig/drivers/md/dm-cache-policy.h +++ linux/drivers/md/dm-cache-policy.h @@ -196,6 +196,7 @@ struct dm_cache_policy { * We maintain a little register of the different policy types. */ #define CACHE_POLICY_NAME_SIZE 16 +#define CACHE_POLICY_VERSION_SIZE 3 struct dm_cache_policy_type { /* For use by the register code only. */ @@ -206,6 +207,7 @@ struct dm_cache_policy_type { * what gets passed on the target line to select your policy. */ char name[CACHE_POLICY_NAME_SIZE]; + unsigned version[CACHE_POLICY_VERSION_SIZE]; /* * Policies may store a hint for each each cache block.