dm thin metadata: check if in fail_io mode when setting needs_check

Check if in fail_io mode at start of dm_pool_metadata_set_needs_check(). Otherwise dm_pool_metadata_set_needs_check()'s superblock_lock() can crash in dm_bm_write_lock() while accessing the block manager object that was previously destroyed as part of a failed dm_pool_abort_metadata() that ultimately set fail_io to begin with. Also, update DMERR() message to more accurately describe superblock_lock() failure. Cc: [email protected] Reported-by: Zdenek Kabelac <[email protected]> Signed-off-by: Mike Snitzer <[email protected]>
IreneKnapp · Jul 2, 2019 · 54fa16e · 54fa16e
1 parent 2eba4e6
commit 54fa16e
Showing 1 changed file with 5 additions and 2 deletions.
diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
@@ -2046,16 +2046,19 @@ int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
 
 int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd)
 {
-	int r;
+	int r = -EINVAL;
 	struct dm_block *sblock;
 	struct thin_disk_superblock *disk_super;
 
 	pmd_write_lock(pmd);
+	if (pmd->fail_io)
+		goto out;
+
 	pmd->flags |= THIN_METADATA_NEEDS_CHECK_FLAG;
 
 	r = superblock_lock(pmd, &sblock);
 	if (r) {
-		DMERR("couldn't read superblock");
+		DMERR("couldn't lock superblock");
 		goto out;
 	}