dm cache metadata: fail operations if fail_io mode has been established

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.

Cc: stable@vger.kernel.org
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 8568dbd50ba402f23e0d5870e6c7d07737e530be..4a4e9c75fc4cddca59c30df2f18ebaa6f0baaa61 100644 (file)
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -1624,17 +1624,19 @@ void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
 
 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;
@@ -1646,7 +1648,8 @@ int dm_cache_get_free_metadata_block_count(struct dm_cache_metadata *cmd,
        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;
@@ -1658,7 +1661,8 @@ int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd,
        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;