dm cache: Fix ABBA deadlock between shrink_slab and dm_cache_metadata_abort
commit 352b837a5541690d4f843819028cf2b8be83d424 upstream.
Same ABBA deadlock pattern fixed in commit 4b60f452ec51 ("dm thin: Fix
ABBA deadlock between shrink_slab and dm_pool_abort_metadata") to
DM-cache's metadata.
Reported-by: Zhihao Cheng <chengzhihao1@huawei.com>
Cc: stable@vger.kernel.org
Fixes: 028ae9f76f29 ("dm cache: add fail io mode and needs_check flag")
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index a9208ab..16925d1 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -522,11 +522,13 @@
return r;
}
-static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd)
+static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd,
+ bool destroy_bm)
{
dm_sm_destroy(cmd->metadata_sm);
dm_tm_destroy(cmd->tm);
- dm_block_manager_destroy(cmd->bm);
+ if (destroy_bm)
+ dm_block_manager_destroy(cmd->bm);
}
typedef unsigned long (*flags_mutator)(unsigned long);
@@ -780,7 +782,7 @@
cmd2 = lookup(bdev);
if (cmd2) {
mutex_unlock(&table_lock);
- __destroy_persistent_data_objects(cmd);
+ __destroy_persistent_data_objects(cmd, true);
kfree(cmd);
return cmd2;
}
@@ -827,7 +829,7 @@
mutex_unlock(&table_lock);
if (!cmd->fail_io)
- __destroy_persistent_data_objects(cmd);
+ __destroy_persistent_data_objects(cmd, true);
kfree(cmd);
}
}
@@ -1551,14 +1553,53 @@
int dm_cache_metadata_abort(struct dm_cache_metadata *cmd)
{
- int r;
+ int r = -EINVAL;
+ struct dm_block_manager *old_bm = NULL, *new_bm = NULL;
+
+ /* fail_io is double-checked with cmd->root_lock held below */
+ if (unlikely(cmd->fail_io))
+ return r;
+
+ /*
+ * Replacement block manager (new_bm) is created and old_bm destroyed outside of
+ * cmd root_lock to avoid ABBA deadlock that would result (due to life-cycle of
+ * shrinker associated with the block manager's bufio client vs cmd root_lock).
+ * - must take shrinker_rwsem without holding cmd->root_lock
+ */
+ new_bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
+ CACHE_METADATA_CACHE_SIZE,
+ CACHE_MAX_CONCURRENT_LOCKS);
WRITE_LOCK(cmd);
- __destroy_persistent_data_objects(cmd);
- r = __create_persistent_data_objects(cmd, false);
+ if (cmd->fail_io) {
+ WRITE_UNLOCK(cmd);
+ goto out;
+ }
+
+ __destroy_persistent_data_objects(cmd, false);
+ old_bm = cmd->bm;
+ if (IS_ERR(new_bm)) {
+ DMERR("could not create block manager during abort");
+ cmd->bm = NULL;
+ r = PTR_ERR(new_bm);
+ goto out_unlock;
+ }
+
+ cmd->bm = new_bm;
+ r = __open_or_format_metadata(cmd, false);
+ if (r) {
+ cmd->bm = NULL;
+ goto out_unlock;
+ }
+ new_bm = NULL;
+out_unlock:
if (r)
cmd->fail_io = true;
WRITE_UNLOCK(cmd);
+ dm_block_manager_destroy(old_bm);
+out:
+ if (new_bm && !IS_ERR(new_bm))
+ dm_block_manager_destroy(new_bm);
return r;
}