Merge tag 'dm-3.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm

Pull device-mapper fixes from Alasdair G Kergon:
 "Fix reported data loss with discards and thin snapshots; avoid a
  deadlock observed in dm verity; fix a race in the new dm cache code
  along with some other minor bugs; store the cache policy version on
  disk to make the stored hints format future-proof."

* tag 'dm-3.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm:
  dm cache: policy ignore hints if generated by different version
  dm cache: policy change version from string to integer set
  dm cache: fix race in writethrough implementation
  dm cache: metadata clear dirty bits on clean shutdown
  dm cache: avoid calling policy destructor twice on error
  dm cache: detect cache_create failure
  dm cache: avoid 64 bit division on 32 bit
  dm verity: avoid deadlock
  dm thin: fix non power of two discard granularity calc
  dm thin: fix discard corruption

12 files changed, 252 insertions, 108 deletions

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 3c955e10a618..c6083132c4b8 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -1025,6 +1025,8 @@ void dm_bufio_prefetch(struct dm_bufio_client *c,
 {
         struct blk_plug plug;
 
+        BUG_ON(dm_bufio_in_request());
+
         blk_start_plug(&plug);
         dm_bufio_lock(c);
 
diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index fbd3625f2748..83e995fece88 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/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(struct dm_cache_metadata *cmd)
         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(struct dm_cache_metadata *cmd)
         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(struct dm_cache_metadata *cmd,
         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 dm_cache_metadata *cmd,
         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);
@@ -854,18 +863,43 @@ 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 +933,8 @@ 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 +944,19 @@ 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 +1015,7 @@ 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),
@@ -1070,13 +1106,15 @@ 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)
diff --git a/drivers/md/dm-cache-metadata.h b/drivers/md/dm-cache-metadata.h
index 135864ea0eee..f45cef21f3d0 100644
--- a/drivers/md/dm-cache-metadata.h
+++ b/drivers/md/dm-cache-metadata.h
@@ -89,7 +89,7 @@ typedef int (*load_mapping_fn)(void *context, dm_oblock_t oblock,
                                dm_cblock_t cblock, bool dirty,
                                uint32_t hint, bool hint_valid);
 int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
-                           const char *policy_name,
+                           struct dm_cache_policy *policy,
                            load_mapping_fn fn,
                            void *context);
 
diff --git a/drivers/md/dm-cache-policy-cleaner.c b/drivers/md/dm-cache-policy-cleaner.c
index cc05d70b3cb8..b04d1f904d07 100644
--- a/drivers/md/dm-cache-policy-cleaner.c
+++ b/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(dm_cblock_t cache_size,
 
 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;
 }
diff --git a/drivers/md/dm-cache-policy-internal.h b/drivers/md/dm-cache-policy-internal.h
index 52a75beeced5..0928abdc49f0 100644
--- a/drivers/md/dm-cache-policy-internal.h
+++ b/drivers/md/dm-cache-policy-internal.h
@@ -117,6 +117,8 @@ void dm_cache_policy_destroy(struct dm_cache_policy *p);
  */
 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);
 
 /*----------------------------------------------------------------*/
diff --git a/drivers/md/dm-cache-policy-mq.c b/drivers/md/dm-cache-policy-mq.c
index 964153255076..dc112a7137fe 100644
--- a/drivers/md/dm-cache-policy-mq.c
+++ b/drivers/md/dm-cache-policy-mq.c
@@ -14,7 +14,6 @@
 #include <linux/vmalloc.h>
 
 #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_policy_type = {
 
 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;
         }
 
diff --git a/drivers/md/dm-cache-policy.c b/drivers/md/dm-cache-policy.c
index 2cbf5fdaac52..21c03c570c06 100644
--- a/drivers/md/dm-cache-policy.c
+++ b/drivers/md/dm-cache-policy.c
@@ -150,6 +150,14 @@ const char *dm_cache_policy_get_name(struct dm_cache_policy *p)
 }
 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;
diff --git a/drivers/md/dm-cache-policy.h b/drivers/md/dm-cache-policy.h
index f0f51b260544..558bdfdabf5f 100644
--- a/drivers/md/dm-cache-policy.h
+++ b/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.
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 0f4e84b15c30..66120bd46d15 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -142,6 +142,7 @@ struct cache {
         spinlock_t lock;
         struct bio_list deferred_bios;
         struct bio_list deferred_flush_bios;
+        struct bio_list deferred_writethrough_bios;
         struct list_head quiesced_migrations;
         struct list_head completed_migrations;
         struct list_head need_commit_migrations;
@@ -158,7 +159,7 @@ struct cache {
         /*
          * origin_blocks entries, discarded if set.
          */
-        sector_t discard_block_size; /* a power of 2 times sectors per block */
+        uint32_t discard_block_size; /* a power of 2 times sectors per block */
         dm_dblock_t discard_nr_blocks;
         unsigned long *discard_bitset;
 
@@ -199,6 +200,11 @@ struct per_bio_data {
         bool tick:1;
         unsigned req_nr:2;
         struct dm_deferred_entry *all_io_entry;
+
+        /* writethrough fields */
+        struct cache *cache;
+        dm_cblock_t cblock;
+        bio_end_io_t *saved_bi_end_io;
 };
 
 struct dm_cache_migration {
@@ -412,17 +418,24 @@ static bool block_size_is_power_of_two(struct cache *cache)
         return cache->sectors_per_block_shift >= 0;
 }
 
+static dm_block_t block_div(dm_block_t b, uint32_t n)
+{
+        do_div(b, n);
+
+        return b;
+}
+
 static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
 {
-        sector_t discard_blocks = cache->discard_block_size;
+        uint32_t discard_blocks = cache->discard_block_size;
         dm_block_t b = from_oblock(oblock);
 
         if (!block_size_is_power_of_two(cache))
-                (void) sector_div(discard_blocks, cache->sectors_per_block);
+                discard_blocks = discard_blocks / cache->sectors_per_block;
         else
                 discard_blocks >>= cache->sectors_per_block_shift;
 
-        (void) sector_div(b, discard_blocks);
+        b = block_div(b, discard_blocks);
 
         return to_dblock(b);
 }
@@ -609,6 +622,56 @@ static void issue(struct cache *cache, struct bio *bio)
         spin_unlock_irqrestore(&cache->lock, flags);
 }
 
+static void defer_writethrough_bio(struct cache *cache, struct bio *bio)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&cache->lock, flags);
+        bio_list_add(&cache->deferred_writethrough_bios, bio);
+        spin_unlock_irqrestore(&cache->lock, flags);
+
+        wake_worker(cache);
+}
+
+static void writethrough_endio(struct bio *bio, int err)
+{
+        struct per_bio_data *pb = get_per_bio_data(bio);
+        bio->bi_end_io = pb->saved_bi_end_io;
+
+        if (err) {
+                bio_endio(bio, err);
+                return;
+        }
+
+        remap_to_cache(pb->cache, bio, pb->cblock);
+
+        /*
+         * We can't issue this bio directly, since we're in interrupt
+         * context.  So it get's put on a bio list for processing by the
+         * worker thread.
+         */
+        defer_writethrough_bio(pb->cache, bio);
+}
+
+/*
+ * When running in writethrough mode we need to send writes to clean blocks
+ * to both the cache and origin devices.  In future we'd like to clone the
+ * bio and send them in parallel, but for now we're doing them in
+ * series as this is easier.
+ */
+static void remap_to_origin_then_cache(struct cache *cache, struct bio *bio,
+                                       dm_oblock_t oblock, dm_cblock_t cblock)
+{
+        struct per_bio_data *pb = get_per_bio_data(bio);
+
+        pb->cache = cache;
+        pb->cblock = cblock;
+        pb->saved_bi_end_io = bio->bi_end_io;
+        bio->bi_end_io = writethrough_endio;
+
+        remap_to_origin_clear_discard(pb->cache, bio, oblock);
+}
+
 /*----------------------------------------------------------------
  * Migration processing
  *
@@ -1002,7 +1065,7 @@ static void process_discard_bio(struct cache *cache, struct bio *bio)
         dm_block_t end_block = bio->bi_sector + bio_sectors(bio);
         dm_block_t b;
 
-        (void) sector_div(end_block, cache->discard_block_size);
+        end_block = block_div(end_block, cache->discard_block_size);
 
         for (b = start_block; b < end_block; b++)
                 set_discard(cache, to_dblock(b));
@@ -1070,14 +1133,9 @@ static void process_bio(struct cache *cache, struct prealloc *structs,
                 inc_hit_counter(cache, bio);
                 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
 
-                if (is_writethrough_io(cache, bio, lookup_result.cblock)) {
-                        /*
-                         * No need to mark anything dirty in write through mode.
-                         */
-                        pb->req_nr == 0 ?
-                                remap_to_cache(cache, bio, lookup_result.cblock) :
-                                remap_to_origin_clear_discard(cache, bio, block);
-                } else
+                if (is_writethrough_io(cache, bio, lookup_result.cblock))
+                        remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
+                else
                         remap_to_cache_dirty(cache, bio, block, lookup_result.cblock);
 
                 issue(cache, bio);
@@ -1086,17 +1144,8 @@ static void process_bio(struct cache *cache, struct prealloc *structs,
         case POLICY_MISS:
                 inc_miss_counter(cache, bio);
                 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
-
-                if (pb->req_nr != 0) {
-                        /*
-                         * This is a duplicate writethrough io that is no
-                         * longer needed because the block has been demoted.
-                         */
-                        bio_endio(bio, 0);
-                } else {
-                        remap_to_origin_clear_discard(cache, bio, block);
-                        issue(cache, bio);
-                }
+                remap_to_origin_clear_discard(cache, bio, block);
+                issue(cache, bio);
                 break;
 
         case POLICY_NEW:
@@ -1217,6 +1266,23 @@ static void process_deferred_flush_bios(struct cache *cache, bool submit_bios)
                 submit_bios ? generic_make_request(bio) : bio_io_error(bio);
 }
 
+static void process_deferred_writethrough_bios(struct cache *cache)
+{
+        unsigned long flags;
+        struct bio_list bios;
+        struct bio *bio;
+
+        bio_list_init(&bios);
+
+        spin_lock_irqsave(&cache->lock, flags);
+        bio_list_merge(&bios, &cache->deferred_writethrough_bios);
+        bio_list_init(&cache->deferred_writethrough_bios);
+        spin_unlock_irqrestore(&cache->lock, flags);
+
+        while ((bio = bio_list_pop(&bios)))
+                generic_make_request(bio);
+}
+
 static void writeback_some_dirty_blocks(struct cache *cache)
 {
         int r = 0;
@@ -1313,6 +1379,7 @@ static int more_work(struct cache *cache)
         else
                 return !bio_list_empty(&cache->deferred_bios) ||
                         !bio_list_empty(&cache->deferred_flush_bios) ||
+                        !bio_list_empty(&cache->deferred_writethrough_bios) ||
                         !list_empty(&cache->quiesced_migrations) ||
                         !list_empty(&cache->completed_migrations) ||
                         !list_empty(&cache->need_commit_migrations);
@@ -1331,6 +1398,8 @@ static void do_worker(struct work_struct *ws)
 
                 writeback_some_dirty_blocks(cache);
 
+                process_deferred_writethrough_bios(cache);
+
                 if (commit_if_needed(cache)) {
                         process_deferred_flush_bios(cache, false);
 
@@ -1756,8 +1825,11 @@ static int create_cache_policy(struct cache *cache, struct cache_args *ca,
         }
 
         r = set_config_values(cache->policy, ca->policy_argc, ca->policy_argv);
-        if (r)
+        if (r) {
+                *error = "Error setting cache policy's config values";
                 dm_cache_policy_destroy(cache->policy);
+                cache->policy = NULL;
+        }
 
         return r;
 }
@@ -1793,8 +1865,6 @@ static sector_t calculate_discard_block_size(sector_t cache_block_size,
 
 #define DEFAULT_MIGRATION_THRESHOLD (2048 * 100)
 
-static unsigned cache_num_write_bios(struct dm_target *ti, struct bio *bio);
-
 static int cache_create(struct cache_args *ca, struct cache **result)
 {
         int r = 0;
@@ -1821,9 +1891,6 @@ static int cache_create(struct cache_args *ca, struct cache **result)
 
         memcpy(&cache->features, &ca->features, sizeof(cache->features));
 
-        if (cache->features.write_through)
-                ti->num_write_bios = cache_num_write_bios;
-
         cache->callbacks.congested_fn = cache_is_congested;
         dm_table_add_target_callbacks(ti->table, &cache->callbacks);
 
@@ -1835,7 +1902,7 @@ static int cache_create(struct cache_args *ca, struct cache **result)
 
         /* FIXME: factor out this whole section */
         origin_blocks = cache->origin_sectors = ca->origin_sectors;
-        (void) sector_div(origin_blocks, ca->block_size);
+        origin_blocks = block_div(origin_blocks, ca->block_size);
         cache->origin_blocks = to_oblock(origin_blocks);
 
         cache->sectors_per_block = ca->block_size;
@@ -1848,7 +1915,7 @@ static int cache_create(struct cache_args *ca, struct cache **result)
                 dm_block_t cache_size = ca->cache_sectors;
 
                 cache->sectors_per_block_shift = -1;
-                (void) sector_div(cache_size, ca->block_size);
+                cache_size = block_div(cache_size, ca->block_size);
                 cache->cache_size = to_cblock(cache_size);
         } else {
                 cache->sectors_per_block_shift = __ffs(ca->block_size);
@@ -1873,6 +1940,7 @@ static int cache_create(struct cache_args *ca, struct cache **result)
         spin_lock_init(&cache->lock);
         bio_list_init(&cache->deferred_bios);
         bio_list_init(&cache->deferred_flush_bios);
+        bio_list_init(&cache->deferred_writethrough_bios);
         INIT_LIST_HEAD(&cache->quiesced_migrations);
         INIT_LIST_HEAD(&cache->completed_migrations);
         INIT_LIST_HEAD(&cache->need_commit_migrations);
@@ -2002,6 +2070,8 @@ static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
                 goto out;
 
         r = cache_create(ca, &cache);
+        if (r)
+                goto out;
 
         r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
         if (r) {
@@ -2016,20 +2086,6 @@ out:
         return r;
 }
 
-static unsigned cache_num_write_bios(struct dm_target *ti, struct bio *bio)
-{
-        int r;
-        struct cache *cache = ti->private;
-        dm_oblock_t block = get_bio_block(cache, bio);
-        dm_cblock_t cblock;
-
-        r = policy_lookup(cache->policy, block, &cblock);
-        if (r < 0)
-                return 2;       /* assume the worst */
-
-        return (!r && !is_dirty(cache, cblock)) ? 2 : 1;
-}
-
 static int cache_map(struct dm_target *ti, struct bio *bio)
 {
         struct cache *cache = ti->private;
@@ -2097,18 +2153,12 @@ static int cache_map(struct dm_target *ti, struct bio *bio)
                 inc_hit_counter(cache, bio);
                 pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);
 
-                if (is_writethrough_io(cache, bio, lookup_result.cblock)) {
-                        /*
-                         * No need to mark anything dirty in write through mode.
-                         */
-                        pb->req_nr == 0 ?
-                                remap_to_cache(cache, bio, lookup_result.cblock) :
-                                remap_to_origin_clear_discard(cache, bio, block);
-                        cell_defer(cache, cell, false);
-                } else {
+                if (is_writethrough_io(cache, bio, lookup_result.cblock))
+                        remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);
+                else
                         remap_to_cache_dirty(cache, bio, block, lookup_result.cblock);
-                        cell_defer(cache, cell, false);
-                }
+
+                cell_defer(cache, cell, false);
                 break;
 
         case POLICY_MISS:
@@ -2319,8 +2369,7 @@ static int cache_preresume(struct dm_target *ti)
         }
 
         if (!cache->loaded_mappings) {
-                r = dm_cache_load_mappings(cache->cmd,
-                                           dm_cache_policy_get_name(cache->policy),
+                r = dm_cache_load_mappings(cache->cmd, cache->policy,
                                            load_mapping, cache);
                 if (r) {
                         DMERR("could not load cache mappings");
@@ -2535,7 +2584,7 @@ static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
 
 static struct target_type cache_target = {
         .name = "cache",
-        .version = {1, 0, 0},
+        .version = {1, 1, 0},
         .module = THIS_MODULE,
         .ctr = cache_ctr,
         .dtr = cache_dtr,
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 009339d62828..004ad1652b73 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1577,6 +1577,11 @@ static bool data_dev_supports_discard(struct pool_c *pt)
         return q && blk_queue_discard(q);
 }
 
+static bool is_factor(sector_t block_size, uint32_t n)
+{
+        return !sector_div(block_size, n);
+}
+
 /*
  * If discard_passdown was enabled verify that the data device
  * supports discards.  Disable discard_passdown if not.
@@ -1602,7 +1607,7 @@ static void disable_passdown_if_not_supported(struct pool_c *pt)
         else if (data_limits->discard_granularity > block_size)
                 reason = "discard granularity larger than a block";
 
-        else if (block_size & (data_limits->discard_granularity - 1))
+        else if (!is_factor(block_size, data_limits->discard_granularity))
                 reason = "discard granularity not a factor of block size";
 
         if (reason) {
@@ -2544,7 +2549,7 @@ static struct target_type pool_target = {
         .name = "thin-pool",
         .features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
                     DM_TARGET_IMMUTABLE,
-        .version = {1, 6, 1},
+        .version = {1, 7, 0},
         .module = THIS_MODULE,
         .ctr = pool_ctr,
         .dtr = pool_dtr,
@@ -2831,7 +2836,7 @@ static int thin_iterate_devices(struct dm_target *ti,
 
 static struct target_type thin_target = {
         .name = "thin",
-        .version = {1, 7, 1},
+        .version = {1, 8, 0},
         .module = THIS_MODULE,
         .ctr = thin_ctr,
         .dtr = thin_dtr,
diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c
index 6ad538375c3c..a746f1d21c66 100644
--- a/drivers/md/dm-verity.c
+++ b/drivers/md/dm-verity.c
@@ -93,6 +93,13 @@ struct dm_verity_io {
          */
 };
 
+struct dm_verity_prefetch_work {
+        struct work_struct work;
+        struct dm_verity *v;
+        sector_t block;
+        unsigned n_blocks;
+};
+
 static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io)
 {
         return (struct shash_desc *)(io + 1);
@@ -424,15 +431,18 @@ static void verity_end_io(struct bio *bio, int error)
  * The root buffer is not prefetched, it is assumed that it will be cached
  * all the time.
  */
-static void verity_prefetch_io(struct dm_verity *v, struct dm_verity_io *io)
+static void verity_prefetch_io(struct work_struct *work)
 {
+        struct dm_verity_prefetch_work *pw =
+                container_of(work, struct dm_verity_prefetch_work, work);
+        struct dm_verity *v = pw->v;
         int i;
 
         for (i = v->levels - 2; i >= 0; i--) {
                 sector_t hash_block_start;
                 sector_t hash_block_end;
-                verity_hash_at_level(v, io->block, i, &hash_block_start, NULL);
-                verity_hash_at_level(v, io->block + io->n_blocks - 1, i, &hash_block_end, NULL);
+                verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
+                verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
                 if (!i) {
                         unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
 
@@ -452,6 +462,25 @@ no_prefetch_cluster:
                 dm_bufio_prefetch(v->bufio, hash_block_start,
                                   hash_block_end - hash_block_start + 1);
         }
+
+        kfree(pw);
+}
+
+static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
+{
+        struct dm_verity_prefetch_work *pw;
+
+        pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
+                GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
+
+        if (!pw)
+                return;
+
+        INIT_WORK(&pw->work, verity_prefetch_io);
+        pw->v = v;
+        pw->block = io->block;
+        pw->n_blocks = io->n_blocks;
+        queue_work(v->verify_wq, &pw->work);
 }
 
 /*
@@ -498,7 +527,7 @@ static int verity_map(struct dm_target *ti, struct bio *bio)
         memcpy(io->io_vec, bio_iovec(bio),
                io->io_vec_size * sizeof(struct bio_vec));
 
-        verity_prefetch_io(v, io);
+        verity_submit_prefetch(v, io);
 
         generic_make_request(bio);
 
@@ -858,7 +887,7 @@ bad:
 
 static struct target_type verity_target = {
         .name           = "verity",
-        .version        = {1, 1, 1},
+        .version        = {1, 2, 0},
         .module         = THIS_MODULE,
         .ctr            = verity_ctr,
         .dtr            = verity_dtr,
diff --git a/drivers/md/persistent-data/dm-btree-remove.c b/drivers/md/persistent-data/dm-btree-remove.c
index c4f28133ef82..b88757cd0d1d 100644
--- a/drivers/md/persistent-data/dm-btree-remove.c
+++ b/drivers/md/persistent-data/dm-btree-remove.c
@@ -139,15 +139,8 @@ struct child {
         struct btree_node *n;
 };
 
-static struct dm_btree_value_type le64_type = {
-        .context = NULL,
-        .size = sizeof(__le64),
-        .inc = NULL,
-        .dec = NULL,
-        .equal = NULL
-};
-
-static int init_child(struct dm_btree_info *info, struct btree_node *parent,
+static int init_child(struct dm_btree_info *info, struct dm_btree_value_type *vt,
+                      struct btree_node *parent,
                       unsigned index, struct child *result)
 {
         int r, inc;
@@ -164,7 +157,7 @@ static int init_child(struct dm_btree_info *info, struct btree_node *parent,
         result->n = dm_block_data(result->block);
 
         if (inc)
-                inc_children(info->tm, result->n, &le64_type);
+                inc_children(info->tm, result->n, vt);
 
         *((__le64 *) value_ptr(parent, index)) =
                 cpu_to_le64(dm_block_location(result->block));
@@ -236,7 +229,7 @@ static void __rebalance2(struct dm_btree_info *info, struct btree_node *parent,
 }
 
 static int rebalance2(struct shadow_spine *s, struct dm_btree_info *info,
-                      unsigned left_index)
+                      struct dm_btree_value_type *vt, unsigned left_index)
 {
         int r;
         struct btree_node *parent;
@@ -244,11 +237,11 @@ static int rebalance2(struct shadow_spine *s, struct dm_btree_info *info,
 
         parent = dm_block_data(shadow_current(s));
 
-        r = init_child(info, parent, left_index, &left);
+        r = init_child(info, vt, parent, left_index, &left);
         if (r)
                 return r;
 
-        r = init_child(info, parent, left_index + 1, &right);
+        r = init_child(info, vt, parent, left_index + 1, &right);
         if (r) {
                 exit_child(info, &left);
                 return r;
@@ -368,7 +361,7 @@ static void __rebalance3(struct dm_btree_info *info, struct btree_node *parent,
 }
 
 static int rebalance3(struct shadow_spine *s, struct dm_btree_info *info,
-                      unsigned left_index)
+                      struct dm_btree_value_type *vt, unsigned left_index)
 {
         int r;
         struct btree_node *parent = dm_block_data(shadow_current(s));
@@ -377,17 +370,17 @@ static int rebalance3(struct shadow_spine *s, struct dm_btree_info *info,
         /*
          * FIXME: fill out an array?
          */
-        r = init_child(info, parent, left_index, &left);
+        r = init_child(info, vt, parent, left_index, &left);
         if (r)
                 return r;
 
-        r = init_child(info, parent, left_index + 1, &center);
+        r = init_child(info, vt, parent, left_index + 1, &center);
         if (r) {
                 exit_child(info, &left);
                 return r;
         }
 
-        r = init_child(info, parent, left_index + 2, &right);
+        r = init_child(info, vt, parent, left_index + 2, &right);
         if (r) {
                 exit_child(info, &left);
                 exit_child(info, &center);
@@ -434,7 +427,8 @@ static int get_nr_entries(struct dm_transaction_manager *tm,
 }
 
 static int rebalance_children(struct shadow_spine *s,
-                              struct dm_btree_info *info, uint64_t key)
+                              struct dm_btree_info *info,
+                              struct dm_btree_value_type *vt, uint64_t key)
 {
         int i, r, has_left_sibling, has_right_sibling;
         uint32_t child_entries;
@@ -472,13 +466,13 @@ static int rebalance_children(struct shadow_spine *s,
         has_right_sibling = i < (le32_to_cpu(n->header.nr_entries) - 1);
 
         if (!has_left_sibling)
-                r = rebalance2(s, info, i);
+                r = rebalance2(s, info, vt, i);
 
         else if (!has_right_sibling)
-                r = rebalance2(s, info, i - 1);
+                r = rebalance2(s, info, vt, i - 1);
 
         else
-                r = rebalance3(s, info, i - 1);
+                r = rebalance3(s, info, vt, i - 1);
 
         return r;
 }
@@ -529,7 +523,7 @@ static int remove_raw(struct shadow_spine *s, struct dm_btree_info *info,
                 if (le32_to_cpu(n->header.flags) & LEAF_NODE)
                         return do_leaf(n, key, index);
 
-                r = rebalance_children(s, info, key);
+                r = rebalance_children(s, info, vt, key);
                 if (r)
                         break;
 
@@ -550,6 +544,14 @@ static int remove_raw(struct shadow_spine *s, struct dm_btree_info *info,
         return r;
 }
 
+static struct dm_btree_value_type le64_type = {
+        .context = NULL,
+        .size = sizeof(__le64),
+        .inc = NULL,
+        .dec = NULL,
+        .equal = NULL
+};
+
 int dm_btree_remove(struct dm_btree_info *info, dm_block_t root,
                     uint64_t *keys, dm_block_t *new_root)
 {