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path: root/drivers/md/dm-cache-metadata.c
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Diffstat (limited to 'drivers/md/dm-cache-metadata.c')
-rw-r--r--drivers/md/dm-cache-metadata.c104
1 files changed, 97 insertions, 7 deletions
diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 9fc616c2755e..c1c010498a21 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;
@@ -680,9 +683,10 @@ struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
if (!cmd) {
DMERR("could not allocate metadata struct");
- return NULL;
+ return ERR_PTR(-ENOMEM);
}
+ atomic_set(&cmd->ref_count, 1);
init_rwsem(&cmd->root_lock);
cmd->bdev = bdev;
cmd->data_block_size = data_block_size;
@@ -705,10 +709,96 @@ 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 (!IS_ERR(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 (!IS_ERR(cmd) && !same_params(cmd, data_block_size)) {
+ dm_cache_metadata_close(cmd);
+ return ERR_PTR(-EINVAL);
+ }
+
+ 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);
+ }
}
/*