3 files changed, 152 insertions, 47 deletions

diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 9fc616c2755e..21b156242e42 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -94,6 +94,9 @@ struct cache_disk_superblock {
 } __packed;
 
 struct dm_cache_metadata {
+        atomic_t ref_count;
+        struct list_head list;
+
         struct block_device *bdev;
         struct dm_block_manager *bm;
         struct dm_space_map *metadata_sm;
@@ -669,10 +672,10 @@ static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
 
 /*----------------------------------------------------------------*/
 
-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)
+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)
 {
         int r;
         struct dm_cache_metadata *cmd;
@@ -683,6 +686,7 @@ struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
                 return NULL;
         }
 
+        atomic_set(&cmd->ref_count, 1);
         init_rwsem(&cmd->root_lock);
         cmd->bdev = bdev;
         cmd->data_block_size = data_block_size;
@@ -705,10 +709,95 @@ struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
         return cmd;
 }
 
+/*
+ * We keep a little list of ref counted metadata objects to prevent two
+ * different target instances creating separate bufio instances.  This is
+ * an issue if a table is reloaded before the suspend.
+ */
+static DEFINE_MUTEX(table_lock);
+static LIST_HEAD(table);
+
+static struct dm_cache_metadata *lookup(struct block_device *bdev)
+{
+        struct dm_cache_metadata *cmd;
+
+        list_for_each_entry(cmd, &table, list)
+                if (cmd->bdev == bdev) {
+                        atomic_inc(&cmd->ref_count);
+                        return cmd;
+                }
+
+        return NULL;
+}
+
+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)
+{
+        struct dm_cache_metadata *cmd, *cmd2;
+
+        mutex_lock(&table_lock);
+        cmd = lookup(bdev);
+        mutex_unlock(&table_lock);
+
+        if (cmd)
+                return cmd;
+
+        cmd = metadata_open(bdev, data_block_size, may_format_device, policy_hint_size);
+        if (cmd) {
+                mutex_lock(&table_lock);
+                cmd2 = lookup(bdev);
+                if (cmd2) {
+                        mutex_unlock(&table_lock);
+                        __destroy_persistent_data_objects(cmd);
+                        kfree(cmd);
+                        return cmd2;
+                }
+                list_add(&cmd->list, &table);
+                mutex_unlock(&table_lock);
+        }
+
+        return cmd;
+}
+
+static bool same_params(struct dm_cache_metadata *cmd, sector_t data_block_size)
+{
+        if (cmd->data_block_size != data_block_size) {
+                DMERR("data_block_size (%llu) different from that in metadata (%llu)\n",
+                      (unsigned long long) data_block_size,
+                      (unsigned long long) cmd->data_block_size);
+                return false;
+        }
+
+        return true;
+}
+
+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)
+{
+        struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size,
+                                                       may_format_device, policy_hint_size);
+        if (cmd && !same_params(cmd, data_block_size)) {
+                dm_cache_metadata_close(cmd);
+                return NULL;
+        }
+
+        return cmd;
+}
+
 void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
 {
-        __destroy_persistent_data_objects(cmd);
-        kfree(cmd);
+        if (atomic_dec_and_test(&cmd->ref_count)) {
+                mutex_lock(&table_lock);
+                list_del(&cmd->list);
+                mutex_unlock(&table_lock);
+
+                __destroy_persistent_data_objects(cmd);
+                kfree(cmd);
+        }
 }
 
 /*
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 1e96d7889f51..e1650539cc2f 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -221,7 +221,13 @@ struct cache {
         struct list_head need_commit_migrations;
         sector_t migration_threshold;
         wait_queue_head_t migration_wait;
-        atomic_t nr_migrations;
+        atomic_t nr_allocated_migrations;
+
+        /*
+         * The number of in flight migrations that are performing
+         * background io. eg, promotion, writeback.
+         */
+        atomic_t nr_io_migrations;
 
         wait_queue_head_t quiescing_wait;
         atomic_t quiescing;
@@ -258,7 +264,6 @@ struct cache {
         struct dm_deferred_set *all_io_ds;
 
         mempool_t *migration_pool;
-        struct dm_cache_migration *next_migration;
 
         struct dm_cache_policy *policy;
         unsigned policy_nr_args;
@@ -350,10 +355,31 @@ static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell *cel
         dm_bio_prison_free_cell(cache->prison, cell);
 }
 
+static struct dm_cache_migration *alloc_migration(struct cache *cache)
+{
+        struct dm_cache_migration *mg;
+
+        mg = mempool_alloc(cache->migration_pool, GFP_NOWAIT);
+        if (mg) {
+                mg->cache = cache;
+                atomic_inc(&mg->cache->nr_allocated_migrations);
+        }
+
+        return mg;
+}
+
+static void free_migration(struct dm_cache_migration *mg)
+{
+        if (atomic_dec_and_test(&mg->cache->nr_allocated_migrations))
+                wake_up(&mg->cache->migration_wait);
+
+        mempool_free(mg, mg->cache->migration_pool);
+}
+
 static int prealloc_data_structs(struct cache *cache, struct prealloc *p)
 {
         if (!p->mg) {
-                p->mg = mempool_alloc(cache->migration_pool, GFP_NOWAIT);
+                p->mg = alloc_migration(cache);
                 if (!p->mg)
                         return -ENOMEM;
         }
@@ -382,7 +408,7 @@ static void prealloc_free_structs(struct cache *cache, struct prealloc *p)
                 free_prison_cell(cache, p->cell1);
 
         if (p->mg)
-                mempool_free(p->mg, cache->migration_pool);
+                free_migration(p->mg);
 }
 
 static struct dm_cache_migration *prealloc_get_migration(struct prealloc *p)
@@ -854,24 +880,14 @@ static void remap_to_origin_then_cache(struct cache *cache, struct bio *bio,
  * Migration covers moving data from the origin device to the cache, or
  * vice versa.
  *--------------------------------------------------------------*/
-static void free_migration(struct dm_cache_migration *mg)
-{
-        mempool_free(mg, mg->cache->migration_pool);
-}
-
-static void inc_nr_migrations(struct cache *cache)
+static void inc_io_migrations(struct cache *cache)
 {
-        atomic_inc(&cache->nr_migrations);
+        atomic_inc(&cache->nr_io_migrations);
 }
 
-static void dec_nr_migrations(struct cache *cache)
+static void dec_io_migrations(struct cache *cache)
 {
-        atomic_dec(&cache->nr_migrations);
-
-        /*
-         * Wake the worker in case we're suspending the target.
-         */
-        wake_up(&cache->migration_wait);
+        atomic_dec(&cache->nr_io_migrations);
 }
 
 static void __cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell,
@@ -894,11 +910,10 @@ static void cell_defer(struct cache *cache, struct dm_bio_prison_cell *cell,
         wake_worker(cache);
 }
 
-static void cleanup_migration(struct dm_cache_migration *mg)
+static void free_io_migration(struct dm_cache_migration *mg)
 {
-        struct cache *cache = mg->cache;
+        dec_io_migrations(mg->cache);
         free_migration(mg);
-        dec_nr_migrations(cache);
 }
 
 static void migration_failure(struct dm_cache_migration *mg)
@@ -923,7 +938,7 @@ static void migration_failure(struct dm_cache_migration *mg)
                 cell_defer(cache, mg->new_ocell, true);
         }
 
-        cleanup_migration(mg);
+        free_io_migration(mg);
 }
 
 static void migration_success_pre_commit(struct dm_cache_migration *mg)
@@ -934,7 +949,7 @@ static void migration_success_pre_commit(struct dm_cache_migration *mg)
         if (mg->writeback) {
                 clear_dirty(cache, mg->old_oblock, mg->cblock);
                 cell_defer(cache, mg->old_ocell, false);
-                cleanup_migration(mg);
+                free_io_migration(mg);
                 return;
 
         } else if (mg->demote) {
@@ -944,14 +959,14 @@ static void migration_success_pre_commit(struct dm_cache_migration *mg)
                                              mg->old_oblock);
                         if (mg->promote)
                                 cell_defer(cache, mg->new_ocell, true);
-                        cleanup_migration(mg);
+                        free_io_migration(mg);
                         return;
                 }
         } else {
                 if (dm_cache_insert_mapping(cache->cmd, mg->cblock, mg->new_oblock)) {
                         DMWARN_LIMIT("promotion failed; couldn't update on disk metadata");
                         policy_remove_mapping(cache->policy, mg->new_oblock);
-                        cleanup_migration(mg);
+                        free_io_migration(mg);
                         return;
                 }
         }
@@ -984,7 +999,7 @@ static void migration_success_post_commit(struct dm_cache_migration *mg)
                 } else {
                         if (mg->invalidate)
                                 policy_remove_mapping(cache->policy, mg->old_oblock);
-                        cleanup_migration(mg);
+                        free_io_migration(mg);
                 }
 
         } else {
@@ -999,7 +1014,7 @@ static void migration_success_post_commit(struct dm_cache_migration *mg)
                         bio_endio(mg->new_ocell->holder, 0);
                         cell_defer(cache, mg->new_ocell, false);
                 }
-                cleanup_migration(mg);
+                free_io_migration(mg);
         }
 }
 
@@ -1251,7 +1266,7 @@ static void promote(struct cache *cache, struct prealloc *structs,
         mg->new_ocell = cell;
         mg->start_jiffies = jiffies;
 
-        inc_nr_migrations(cache);
+        inc_io_migrations(cache);
         quiesce_migration(mg);
 }
 
@@ -1275,7 +1290,7 @@ static void writeback(struct cache *cache, struct prealloc *structs,
         mg->new_ocell = NULL;
         mg->start_jiffies = jiffies;
 
-        inc_nr_migrations(cache);
+        inc_io_migrations(cache);
         quiesce_migration(mg);
 }
 
@@ -1302,7 +1317,7 @@ static void demote_then_promote(struct cache *cache, struct prealloc *structs,
         mg->new_ocell = new_ocell;
         mg->start_jiffies = jiffies;
 
-        inc_nr_migrations(cache);
+        inc_io_migrations(cache);
         quiesce_migration(mg);
 }
 
@@ -1330,7 +1345,7 @@ static void invalidate(struct cache *cache, struct prealloc *structs,
         mg->new_ocell = NULL;
         mg->start_jiffies = jiffies;
 
-        inc_nr_migrations(cache);
+        inc_io_migrations(cache);
         quiesce_migration(mg);
 }
 
@@ -1412,7 +1427,7 @@ static void process_discard_bio(struct cache *cache, struct prealloc *structs,
 
 static bool spare_migration_bandwidth(struct cache *cache)
 {
-        sector_t current_volume = (atomic_read(&cache->nr_migrations) + 1) *
+        sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) *
                 cache->sectors_per_block;
         return current_volume < cache->migration_threshold;
 }
@@ -1764,7 +1779,7 @@ static void stop_quiescing(struct cache *cache)
 
 static void wait_for_migrations(struct cache *cache)
 {
-        wait_event(cache->migration_wait, !atomic_read(&cache->nr_migrations));
+        wait_event(cache->migration_wait, !atomic_read(&cache->nr_allocated_migrations));
 }
 
 static void stop_worker(struct cache *cache)
@@ -1876,9 +1891,6 @@ static void destroy(struct cache *cache)
 {
         unsigned i;
 
-        if (cache->next_migration)
-                mempool_free(cache->next_migration, cache->migration_pool);
-
         if (cache->migration_pool)
                 mempool_destroy(cache->migration_pool);
 
@@ -2424,7 +2436,8 @@ static int cache_create(struct cache_args *ca, struct cache **result)
         INIT_LIST_HEAD(&cache->quiesced_migrations);
         INIT_LIST_HEAD(&cache->completed_migrations);
         INIT_LIST_HEAD(&cache->need_commit_migrations);
-        atomic_set(&cache->nr_migrations, 0);
+        atomic_set(&cache->nr_allocated_migrations, 0);
+        atomic_set(&cache->nr_io_migrations, 0);
         init_waitqueue_head(&cache->migration_wait);
 
         init_waitqueue_head(&cache->quiescing_wait);
@@ -2487,8 +2500,6 @@ static int cache_create(struct cache_args *ca, struct cache **result)
                 goto bad;
         }
 
-        cache->next_migration = NULL;
-
         cache->need_tick_bio = true;
         cache->sized = false;
         cache->invalidate = false;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index b98cd9d84435..2caf5b374649 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -206,6 +206,9 @@ struct mapped_device {
         /* zero-length flush that will be cloned and submitted to targets */
         struct bio flush_bio;
 
+        /* the number of internal suspends */
+        unsigned internal_suspend_count;
+
         struct dm_stats stats;
 };
 
@@ -2928,7 +2931,7 @@ static void __dm_internal_suspend(struct mapped_device *md, unsigned suspend_fla
 {
         struct dm_table *map = NULL;
 
-        if (dm_suspended_internally_md(md))
+        if (md->internal_suspend_count++)
                 return; /* nested internal suspend */
 
         if (dm_suspended_md(md)) {
@@ -2953,7 +2956,9 @@ static void __dm_internal_suspend(struct mapped_device *md, unsigned suspend_fla
 
 static void __dm_internal_resume(struct mapped_device *md)
 {
-        if (!dm_suspended_internally_md(md))
+        BUG_ON(!md->internal_suspend_count);
+
+        if (--md->internal_suspend_count)
                 return; /* resume from nested internal suspend */
 
         if (dm_suspended_md(md))