This is a note to let you know that I've just added the patch titled dm cache metadata: fail operations if fail_io mode has been established to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: dm-cache-metadata-fail-operations-if-fail_io-mode-has-been-established.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 10add84e276432d9dd8044679a1028dd4084117e Mon Sep 17 00:00:00 2001 From: Mike Snitzer <snitzer@xxxxxxxxxx> Date: Fri, 5 May 2017 14:40:13 -0400 Subject: dm cache metadata: fail operations if fail_io mode has been established 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 @@ -1326,17 +1326,19 @@ 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; @@ -1348,7 +1350,8 @@ 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; @@ -1360,7 +1363,8 @@ 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; Patches currently in stable-queue which might be from snitzer@xxxxxxxxxx are queue-4.4/dm-btree-fix-for-dm_btree_find_lowest_key.patch queue-4.4/dm-bufio-avoid-a-possible-abba-deadlock.patch queue-4.4/dm-cache-metadata-fail-operations-if-fail_io-mode-has-been-established.patch queue-4.4/dm-raid-select-the-kconfig-option-config_md_raid0.patch queue-4.4/dm-bufio-make-the-parameter-retain_bytes-unsigned-long.patch queue-4.4/dm-space-map-disk-fix-some-book-keeping-in-the-disk-space-map.patch queue-4.4/dm-bufio-check-new-buffer-allocation-watermark-every-30-seconds.patch queue-4.4/dm-thin-metadata-call-precommit-before-saving-the-roots.patch