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Commit f472bfc9 authored by Mike Snitzer's avatar Mike Snitzer Committed by Greg Kroah-Hartman
Browse files

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: default avatarZhihao Cheng <chengzhihao1@huawei.com>
Cc: stable@vger.kernel.org
Fixes: 028ae9f7 ("dm cache: add fail io mode and needs_check flag")
Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 52ba5b87

drivers/md/dm-cache-metadata.c

+47 −7
Original line number Diff line number Diff line
@@ -551,10 +551,12 @@ static int __create_persistent_data_objects(struct dm_cache_metadata *cmd, 
	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);

	if (destroy_bm)

		dm_block_manager_destroy(cmd->bm);

}
@@ -826,7 +828,7 @@ static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev, 
		cmd2 = lookup(bdev);

		if (cmd2) {

			mutex_unlock(&table_lock);

			__destroy_persistent_data_objects(cmd);

			__destroy_persistent_data_objects(cmd, true);

			kfree(cmd);

			return cmd2;

		}
@@ -874,7 +876,7 @@ void dm_cache_metadata_close(struct dm_cache_metadata *cmd) 
		mutex_unlock(&table_lock);



		if (!cmd->fail_io)

			__destroy_persistent_data_objects(cmd);

			__destroy_persistent_data_objects(cmd, true);

		kfree(cmd);

	}

}
@@ -1808,14 +1810,52 @@ int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result) 


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_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;

}