16 files changed, 197 insertions, 71 deletions

diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt
index 274752f8bdf9..719320b5ed3f 100644
--- a/Documentation/device-mapper/cache.txt
+++ b/Documentation/device-mapper/cache.txt
@@ -266,10 +266,12 @@ E.g.
 Invalidation is removing an entry from the cache without writing it
 back.  Cache blocks can be invalidated via the invalidate_cblocks
 message, which takes an arbitrary number of cblock ranges.  Each cblock
-must be expressed as a decimal value, in the future a variant message
-that takes cblock ranges expressed in hexidecimal may be needed to
-better support efficient invalidation of larger caches.  The cache must
-be in passthrough mode when invalidate_cblocks is used.
+range's end value is "one past the end", meaning 5-10 expresses a range
+of values from 5 to 9.  Each cblock must be expressed as a decimal
+value, in the future a variant message that takes cblock ranges
+expressed in hexidecimal may be needed to better support efficient
+invalidation of larger caches.  The cache must be in passthrough mode
+when invalidate_cblocks is used.
 
    invalidate_cblocks [<cblock>|<cblock begin>-<cblock end>]*
 
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 173cbb20d104..54bdd923316f 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -1717,6 +1717,11 @@ static int __init dm_bufio_init(void)
 {
         __u64 mem;
 
+        dm_bufio_allocated_kmem_cache = 0;
+        dm_bufio_allocated_get_free_pages = 0;
+        dm_bufio_allocated_vmalloc = 0;
+        dm_bufio_current_allocated = 0;
+
         memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches);
         memset(&dm_bufio_cache_names, 0, sizeof dm_bufio_cache_names);
 
diff --git a/drivers/md/dm-cache-policy-mq.c b/drivers/md/dm-cache-policy-mq.c
index 416b7b752a6e..64780ad73bb0 100644
--- a/drivers/md/dm-cache-policy-mq.c
+++ b/drivers/md/dm-cache-policy-mq.c
@@ -730,15 +730,18 @@ static int pre_cache_entry_found(struct mq_policy *mq, struct entry *e,
         int r = 0;
         bool updated = updated_this_tick(mq, e);
 
-        requeue_and_update_tick(mq, e);
-
         if ((!discarded_oblock && updated) ||
-            !should_promote(mq, e, discarded_oblock, data_dir))
+            !should_promote(mq, e, discarded_oblock, data_dir)) {
+                requeue_and_update_tick(mq, e);
                 result->op = POLICY_MISS;
-        else if (!can_migrate)
+
+        } else if (!can_migrate)
                 r = -EWOULDBLOCK;
-        else
+
+        else {
+                requeue_and_update_tick(mq, e);
                 r = pre_cache_to_cache(mq, e, result);
+        }
 
         return r;
 }
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 9efcf1059b99..1b1469ebe5cb 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -2755,7 +2755,7 @@ static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
 {
         int r;
 
-        r = dm_cache_resize(cache->cmd, cache->cache_size);
+        r = dm_cache_resize(cache->cmd, new_size);
         if (r) {
                 DMERR("could not resize cache metadata");
                 return r;
diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
index 496d5f3646a5..2f91d6d4a2cc 100644
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -20,6 +20,7 @@
 struct delay_c {
         struct timer_list delay_timer;
         struct mutex timer_lock;
+        struct workqueue_struct *kdelayd_wq;
         struct work_struct flush_expired_bios;
         struct list_head delayed_bios;
         atomic_t may_delay;
@@ -45,14 +46,13 @@ struct dm_delay_info {
 
 static DEFINE_MUTEX(delayed_bios_lock);
 
-static struct workqueue_struct *kdelayd_wq;
 static struct kmem_cache *delayed_cache;
 
 static void handle_delayed_timer(unsigned long data)
 {
         struct delay_c *dc = (struct delay_c *)data;
 
-        queue_work(kdelayd_wq, &dc->flush_expired_bios);
+        queue_work(dc->kdelayd_wq, &dc->flush_expired_bios);
 }
 
 static void queue_timeout(struct delay_c *dc, unsigned long expires)
@@ -191,6 +191,12 @@ out:
                 goto bad_dev_write;
         }
 
+        dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
+        if (!dc->kdelayd_wq) {
+                DMERR("Couldn't start kdelayd");
+                goto bad_queue;
+        }
+
         setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc);
 
         INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
@@ -203,6 +209,8 @@ out:
         ti->private = dc;
         return 0;
 
+bad_queue:
+        mempool_destroy(dc->delayed_pool);
 bad_dev_write:
         if (dc->dev_write)
                 dm_put_device(ti, dc->dev_write);
@@ -217,7 +225,7 @@ static void delay_dtr(struct dm_target *ti)
 {
         struct delay_c *dc = ti->private;
 
-        flush_workqueue(kdelayd_wq);
+        destroy_workqueue(dc->kdelayd_wq);
 
         dm_put_device(ti, dc->dev_read);
 
@@ -350,12 +358,6 @@ static int __init dm_delay_init(void)
 {
         int r = -ENOMEM;
 
-        kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
-        if (!kdelayd_wq) {
-                DMERR("Couldn't start kdelayd");
-                goto bad_queue;
-        }
-
         delayed_cache = KMEM_CACHE(dm_delay_info, 0);
         if (!delayed_cache) {
                 DMERR("Couldn't create delayed bio cache.");
@@ -373,8 +375,6 @@ static int __init dm_delay_init(void)
 bad_register:
         kmem_cache_destroy(delayed_cache);
 bad_memcache:
-        destroy_workqueue(kdelayd_wq);
-bad_queue:
         return r;
 }
 
@@ -382,7 +382,6 @@ static void __exit dm_delay_exit(void)
 {
         dm_unregister_target(&delay_target);
         kmem_cache_destroy(delayed_cache);
-        destroy_workqueue(kdelayd_wq);
 }
 
 /* Module hooks */
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index aec57d76db5d..944690bafd93 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -66,6 +66,18 @@ struct dm_snapshot {
 
         atomic_t pending_exceptions_count;
 
+        /* Protected by "lock" */
+        sector_t exception_start_sequence;
+
+        /* Protected by kcopyd single-threaded callback */
+        sector_t exception_complete_sequence;
+
+        /*
+         * A list of pending exceptions that completed out of order.
+         * Protected by kcopyd single-threaded callback.
+         */
+        struct list_head out_of_order_list;
+
         mempool_t *pending_pool;
 
         struct dm_exception_table pending;
@@ -173,6 +185,14 @@ struct dm_snap_pending_exception {
          */
         int started;
 
+        /* There was copying error. */
+        int copy_error;
+
+        /* A sequence number, it is used for in-order completion. */
+        sector_t exception_sequence;
+
+        struct list_head out_of_order_entry;
+
         /*
          * For writing a complete chunk, bypassing the copy.
          */
@@ -1094,6 +1114,9 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         s->valid = 1;
         s->active = 0;
         atomic_set(&s->pending_exceptions_count, 0);
+        s->exception_start_sequence = 0;
+        s->exception_complete_sequence = 0;
+        INIT_LIST_HEAD(&s->out_of_order_list);
         init_rwsem(&s->lock);
         INIT_LIST_HEAD(&s->list);
         spin_lock_init(&s->pe_lock);
@@ -1443,6 +1466,19 @@ static void commit_callback(void *context, int success)
         pending_complete(pe, success);
 }
 
+static void complete_exception(struct dm_snap_pending_exception *pe)
+{
+        struct dm_snapshot *s = pe->snap;
+
+        if (unlikely(pe->copy_error))
+                pending_complete(pe, 0);
+
+        else
+                /* Update the metadata if we are persistent */
+                s->store->type->commit_exception(s->store, &pe->e,
+                                                 commit_callback, pe);
+}
+
 /*
  * Called when the copy I/O has finished.  kcopyd actually runs
  * this code so don't block.
@@ -1452,13 +1488,32 @@ static void copy_callback(int read_err, unsigned long write_err, void *context)
         struct dm_snap_pending_exception *pe = context;
         struct dm_snapshot *s = pe->snap;
 
-        if (read_err || write_err)
-                pending_complete(pe, 0);
+        pe->copy_error = read_err || write_err;
 
-        else
-                /* Update the metadata if we are persistent */
-                s->store->type->commit_exception(s->store, &pe->e,
-                                                 commit_callback, pe);
+        if (pe->exception_sequence == s->exception_complete_sequence) {
+                s->exception_complete_sequence++;
+                complete_exception(pe);
+
+                while (!list_empty(&s->out_of_order_list)) {
+                        pe = list_entry(s->out_of_order_list.next,
+                                        struct dm_snap_pending_exception, out_of_order_entry);
+                        if (pe->exception_sequence != s->exception_complete_sequence)
+                                break;
+                        s->exception_complete_sequence++;
+                        list_del(&pe->out_of_order_entry);
+                        complete_exception(pe);
+                }
+        } else {
+                struct list_head *lh;
+                struct dm_snap_pending_exception *pe2;
+
+                list_for_each_prev(lh, &s->out_of_order_list) {
+                        pe2 = list_entry(lh, struct dm_snap_pending_exception, out_of_order_entry);
+                        if (pe2->exception_sequence < pe->exception_sequence)
+                                break;
+                }
+                list_add(&pe->out_of_order_entry, lh);
+        }
 }
 
 /*
@@ -1553,6 +1608,8 @@ __find_pending_exception(struct dm_snapshot *s,
                 return NULL;
         }
 
+        pe->exception_sequence = s->exception_start_sequence++;
+
         dm_insert_exception(&s->pending, &pe->e);
 
         return pe;
@@ -2192,7 +2249,7 @@ static struct target_type origin_target = {
 
 static struct target_type snapshot_target = {
         .name    = "snapshot",
-        .version = {1, 11, 1},
+        .version = {1, 12, 0},
         .module  = THIS_MODULE,
         .ctr     = snapshot_ctr,
         .dtr     = snapshot_dtr,
diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index 3d404c1371ed..28a90122a5a8 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -964,6 +964,7 @@ int dm_stats_message(struct mapped_device *md, unsigned argc, char **argv,
 
 int __init dm_statistics_init(void)
 {
+        shared_memory_amount = 0;
         dm_stat_need_rcu_barrier = 0;
         return 0;
 }
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 465f08ca62b1..3ba6a3859ce3 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -200,6 +200,11 @@ int dm_table_create(struct dm_table **result, fmode_t mode,
 
         num_targets = dm_round_up(num_targets, KEYS_PER_NODE);
 
+        if (!num_targets) {
+                kfree(t);
+                return -ENOMEM;
+        }
+
         if (alloc_targets(t, num_targets)) {
                 kfree(t);
                 return -ENOMEM;
diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index 60bce435f4fa..8a30ad54bd46 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -1697,6 +1697,14 @@ void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd)
         up_write(&pmd->root_lock);
 }
 
+void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd)
+{
+        down_write(&pmd->root_lock);
+        pmd->read_only = false;
+        dm_bm_set_read_write(pmd->bm);
+        up_write(&pmd->root_lock);
+}
+
 int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
                                         dm_block_t threshold,
                                         dm_sm_threshold_fn fn,
diff --git a/drivers/md/dm-thin-metadata.h b/drivers/md/dm-thin-metadata.h
index 845ebbe589a9..7bcc0e1d6238 100644
--- a/drivers/md/dm-thin-metadata.h
+++ b/drivers/md/dm-thin-metadata.h
@@ -193,6 +193,7 @@ int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_siz
  * that nothing is changing.
  */
 void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);
+void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd);
 
 int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
                                         dm_block_t threshold,
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 2c0cf511ec23..ee29037ffc2e 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -640,7 +640,9 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
          */
         r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block);
         if (r) {
-                DMERR_LIMIT("dm_thin_insert_block() failed");
+                DMERR_LIMIT("%s: dm_thin_insert_block() failed: error = %d",
+                            dm_device_name(pool->pool_md), r);
+                set_pool_mode(pool, PM_READ_ONLY);
                 cell_error(pool, m->cell);
                 goto out;
         }
@@ -881,32 +883,23 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
         }
 }
 
-static int commit(struct pool *pool)
-{
-        int r;
-
-        r = dm_pool_commit_metadata(pool->pmd);
-        if (r)
-                DMERR_LIMIT("%s: commit failed: error = %d",
-                            dm_device_name(pool->pool_md), r);
-
-        return r;
-}
-
 /*
  * A non-zero return indicates read_only or fail_io mode.
  * Many callers don't care about the return value.
  */
-static int commit_or_fallback(struct pool *pool)
+static int commit(struct pool *pool)
 {
         int r;
 
         if (get_pool_mode(pool) != PM_WRITE)
                 return -EINVAL;
 
-        r = commit(pool);
-        if (r)
+        r = dm_pool_commit_metadata(pool->pmd);
+        if (r) {
+                DMERR_LIMIT("%s: dm_pool_commit_metadata failed: error = %d",
+                            dm_device_name(pool->pool_md), r);
                 set_pool_mode(pool, PM_READ_ONLY);
+        }
 
         return r;
 }
@@ -943,7 +936,9 @@ static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
                  * Try to commit to see if that will free up some
                  * more space.
                  */
-                (void) commit_or_fallback(pool);
+                r = commit(pool);
+                if (r)
+                        return r;
 
                 r = dm_pool_get_free_block_count(pool->pmd, &free_blocks);
                 if (r)
@@ -957,7 +952,7 @@ static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
                  * table reload).
                  */
                 if (!free_blocks) {
-                        DMWARN("%s: no free space available.",
+                        DMWARN("%s: no free data space available.",
                                dm_device_name(pool->pool_md));
                         spin_lock_irqsave(&pool->lock, flags);
                         pool->no_free_space = 1;
@@ -967,8 +962,16 @@ static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
         }
 
         r = dm_pool_alloc_data_block(pool->pmd, result);
-        if (r)
+        if (r) {
+                if (r == -ENOSPC &&
+                    !dm_pool_get_free_metadata_block_count(pool->pmd, &free_blocks) &&
+                    !free_blocks) {
+                        DMWARN("%s: no free metadata space available.",
+                               dm_device_name(pool->pool_md));
+                        set_pool_mode(pool, PM_READ_ONLY);
+                }
                 return r;
+        }
 
         return 0;
 }
@@ -1349,7 +1352,7 @@ static void process_deferred_bios(struct pool *pool)
         if (bio_list_empty(&bios) && !need_commit_due_to_time(pool))
                 return;
 
-        if (commit_or_fallback(pool)) {
+        if (commit(pool)) {
                 while ((bio = bio_list_pop(&bios)))
                         bio_io_error(bio);
                 return;
@@ -1397,6 +1400,7 @@ static void set_pool_mode(struct pool *pool, enum pool_mode mode)
         case PM_FAIL:
                 DMERR("%s: switching pool to failure mode",
                       dm_device_name(pool->pool_md));
+                dm_pool_metadata_read_only(pool->pmd);
                 pool->process_bio = process_bio_fail;
                 pool->process_discard = process_bio_fail;
                 pool->process_prepared_mapping = process_prepared_mapping_fail;
@@ -1421,6 +1425,7 @@ static void set_pool_mode(struct pool *pool, enum pool_mode mode)
                 break;
 
         case PM_WRITE:
+                dm_pool_metadata_read_write(pool->pmd);
                 pool->process_bio = process_bio;
                 pool->process_discard = process_discard;
                 pool->process_prepared_mapping = process_prepared_mapping;
@@ -1637,12 +1642,19 @@ static int bind_control_target(struct pool *pool, struct dm_target *ti)
         struct pool_c *pt = ti->private;
 
         /*
-         * We want to make sure that degraded pools are never upgraded.
+         * We want to make sure that a pool in PM_FAIL mode is never upgraded.
          */
         enum pool_mode old_mode = pool->pf.mode;
         enum pool_mode new_mode = pt->adjusted_pf.mode;
 
-        if (old_mode > new_mode)
+        /*
+         * If we were in PM_FAIL mode, rollback of metadata failed.  We're
+         * not going to recover without a thin_repair.  So we never let the
+         * pool move out of the old mode.  On the other hand a PM_READ_ONLY
+         * may have been due to a lack of metadata or data space, and may
+         * now work (ie. if the underlying devices have been resized).
+         */
+        if (old_mode == PM_FAIL)
                 new_mode = old_mode;
 
         pool->ti = ti;
@@ -2266,7 +2278,7 @@ static int pool_preresume(struct dm_target *ti)
                 return r;
 
         if (need_commit1 || need_commit2)
-                (void) commit_or_fallback(pool);
+                (void) commit(pool);
 
         return 0;
 }
@@ -2293,7 +2305,7 @@ static void pool_postsuspend(struct dm_target *ti)
 
         cancel_delayed_work(&pool->waker);
         flush_workqueue(pool->wq);
-        (void) commit_or_fallback(pool);
+        (void) commit(pool);
 }
 
 static int check_arg_count(unsigned argc, unsigned args_required)
@@ -2427,7 +2439,7 @@ static int process_reserve_metadata_snap_mesg(unsigned argc, char **argv, struct
         if (r)
                 return r;
 
-        (void) commit_or_fallback(pool);
+        (void) commit(pool);
 
         r = dm_pool_reserve_metadata_snap(pool->pmd);
         if (r)
@@ -2489,7 +2501,7 @@ static int pool_message(struct dm_target *ti, unsigned argc, char **argv)
                 DMWARN("Unrecognised thin pool target message received: %s", argv[0]);
 
         if (!r)
-                (void) commit_or_fallback(pool);
+                (void) commit(pool);
 
         return r;
 }
@@ -2544,7 +2556,7 @@ static void pool_status(struct dm_target *ti, status_type_t type,
 
                 /* Commit to ensure statistics aren't out-of-date */
                 if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
-                        (void) commit_or_fallback(pool);
+                        (void) commit(pool);
 
                 r = dm_pool_get_metadata_transaction_id(pool->pmd, &transaction_id);
                 if (r) {
diff --git a/drivers/md/persistent-data/dm-array.c b/drivers/md/persistent-data/dm-array.c
index af96e24ec328..1d75b1dc1e2e 100644
--- a/drivers/md/persistent-data/dm-array.c
+++ b/drivers/md/persistent-data/dm-array.c
@@ -317,8 +317,16 @@ static int shadow_ablock(struct dm_array_info *info, dm_block_t *root,
          * The shadow op will often be a noop.  Only insert if it really
          * copied data.
          */
-        if (dm_block_location(*block) != b)
+        if (dm_block_location(*block) != b) {
+                /*
+                 * dm_tm_shadow_block will have already decremented the old
+                 * block, but it is still referenced by the btree.  We
+                 * increment to stop the insert decrementing it below zero
+                 * when overwriting the old value.
+                 */
+                dm_tm_inc(info->btree_info.tm, b);
                 r = insert_ablock(info, index, *block, root);
+        }
 
         return r;
 }
diff --git a/drivers/md/persistent-data/dm-block-manager.c b/drivers/md/persistent-data/dm-block-manager.c
index a7e8bf296388..064a3c271baa 100644
--- a/drivers/md/persistent-data/dm-block-manager.c
+++ b/drivers/md/persistent-data/dm-block-manager.c
@@ -626,6 +626,12 @@ void dm_bm_set_read_only(struct dm_block_manager *bm)
 }
 EXPORT_SYMBOL_GPL(dm_bm_set_read_only);
 
+void dm_bm_set_read_write(struct dm_block_manager *bm)
+{
+        bm->read_only = false;
+}
+EXPORT_SYMBOL_GPL(dm_bm_set_read_write);
+
 u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor)
 {
         return crc32c(~(u32) 0, data, len) ^ init_xor;
diff --git a/drivers/md/persistent-data/dm-block-manager.h b/drivers/md/persistent-data/dm-block-manager.h
index 9a82083a66b6..13cd58e1fe69 100644
--- a/drivers/md/persistent-data/dm-block-manager.h
+++ b/drivers/md/persistent-data/dm-block-manager.h
@@ -108,9 +108,9 @@ int dm_bm_unlock(struct dm_block *b);
 int dm_bm_flush_and_unlock(struct dm_block_manager *bm,
                            struct dm_block *superblock);
 
- /*
-  * Request data be prefetched into the cache.
-  */
+/*
+ * Request data is prefetched into the cache.
+ */
 void dm_bm_prefetch(struct dm_block_manager *bm, dm_block_t b);
 
 /*
@@ -125,6 +125,7 @@ void dm_bm_prefetch(struct dm_block_manager *bm, dm_block_t b);
  * be returned if you do.
  */
 void dm_bm_set_read_only(struct dm_block_manager *bm);
+void dm_bm_set_read_write(struct dm_block_manager *bm);
 
 u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor);
 
diff --git a/drivers/md/persistent-data/dm-space-map-common.c b/drivers/md/persistent-data/dm-space-map-common.c
index 6058569fe86c..466a60bbd716 100644
--- a/drivers/md/persistent-data/dm-space-map-common.c
+++ b/drivers/md/persistent-data/dm-space-map-common.c
@@ -381,7 +381,7 @@ int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
 }
 
 static int sm_ll_mutate(struct ll_disk *ll, dm_block_t b,
-                        uint32_t (*mutator)(void *context, uint32_t old),
+                        int (*mutator)(void *context, uint32_t old, uint32_t *new),
                         void *context, enum allocation_event *ev)
 {
         int r;
@@ -410,11 +410,17 @@ static int sm_ll_mutate(struct ll_disk *ll, dm_block_t b,
 
         if (old > 2) {
                 r = sm_ll_lookup_big_ref_count(ll, b, &old);
-                if (r < 0)
+                if (r < 0) {
+                        dm_tm_unlock(ll->tm, nb);
                         return r;
+                }
         }
 
-        ref_count = mutator(context, old);
+        r = mutator(context, old, &ref_count);
+        if (r) {
+                dm_tm_unlock(ll->tm, nb);
+                return r;
+        }
 
         if (ref_count <= 2) {
                 sm_set_bitmap(bm_le, bit, ref_count);
@@ -465,9 +471,10 @@ static int sm_ll_mutate(struct ll_disk *ll, dm_block_t b,
         return ll->save_ie(ll, index, &ie_disk);
 }
 
-static uint32_t set_ref_count(void *context, uint32_t old)
+static int set_ref_count(void *context, uint32_t old, uint32_t *new)
 {
-        return *((uint32_t *) context);
+        *new = *((uint32_t *) context);
+        return 0;
 }
 
 int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
@@ -476,9 +483,10 @@ int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
         return sm_ll_mutate(ll, b, set_ref_count, &ref_count, ev);
 }
 
-static uint32_t inc_ref_count(void *context, uint32_t old)
+static int inc_ref_count(void *context, uint32_t old, uint32_t *new)
 {
-        return old + 1;
+        *new = old + 1;
+        return 0;
 }
 
 int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
@@ -486,9 +494,15 @@ int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
         return sm_ll_mutate(ll, b, inc_ref_count, NULL, ev);
 }
 
-static uint32_t dec_ref_count(void *context, uint32_t old)
+static int dec_ref_count(void *context, uint32_t old, uint32_t *new)
 {
-        return old - 1;
+        if (!old) {
+                DMERR_LIMIT("unable to decrement a reference count below 0");
+                return -EINVAL;
+        }
+
+        *new = old - 1;
+        return 0;
 }
 
 int sm_ll_dec(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
diff --git a/drivers/md/persistent-data/dm-space-map-metadata.c b/drivers/md/persistent-data/dm-space-map-metadata.c
index 1c959684caef..58fc1eef7499 100644
--- a/drivers/md/persistent-data/dm-space-map-metadata.c
+++ b/drivers/md/persistent-data/dm-space-map-metadata.c
@@ -384,12 +384,16 @@ static int sm_metadata_new_block(struct dm_space_map *sm, dm_block_t *b)
         struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 
         int r = sm_metadata_new_block_(sm, b);
-        if (r)
+        if (r) {
                 DMERR("unable to allocate new metadata block");
+                return r;
+        }
 
         r = sm_metadata_get_nr_free(sm, &count);
-        if (r)
+        if (r) {
                 DMERR("couldn't get free block count");
+                return r;
+        }
 
         check_threshold(&smm->threshold, count);