4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mike Snitzer <snitzer@xxxxxxxxxx> commit 10add84e276432d9dd8044679a1028dd4084117e upstream. Otherwise it is possible to trigger crashes due to the metadata being inaccessible yet these methods don't safely account for that possibility without these checks. Reported-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/md/dm-cache-metadata.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) --- a/drivers/md/dm-cache-metadata.c +++ b/drivers/md/dm-cache-metadata.c @@ -1383,17 +1383,19 @@ void dm_cache_metadata_set_stats(struct int dm_cache_commit(struct dm_cache_metadata *cmd, bool clean_shutdown) { - int r; + int r = -EINVAL; flags_mutator mutator = (clean_shutdown ? set_clean_shutdown : clear_clean_shutdown); WRITE_LOCK(cmd); + if (cmd->fail_io) + goto out; + r = __commit_transaction(cmd, mutator); if (r) goto out; r = __begin_transaction(cmd); - out: WRITE_UNLOCK(cmd); return r; @@ -1405,7 +1407,8 @@ int dm_cache_get_free_metadata_block_cou int r = -EINVAL; READ_LOCK(cmd); - r = dm_sm_get_nr_free(cmd->metadata_sm, result); + if (!cmd->fail_io) + r = dm_sm_get_nr_free(cmd->metadata_sm, result); READ_UNLOCK(cmd); return r; @@ -1417,7 +1420,8 @@ int dm_cache_get_metadata_dev_size(struc int r = -EINVAL; READ_LOCK(cmd); - r = dm_sm_get_nr_blocks(cmd->metadata_sm, result); + if (!cmd->fail_io) + r = dm_sm_get_nr_blocks(cmd->metadata_sm, result); READ_UNLOCK(cmd); return r;