btrfs: verbose error when we find an unexpected item in sys_array

Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -6520,6 +6520,9 @@ int btrfs_read_sys_array(struct btrfs_root *root)
 			if (ret)
 				break;
 		} else {
+			printk(KERN_ERR
+		"BTRFS: unexpected item type %u in sys_array at offset %u\n",
+				(u32)key.type, cur_offset);
 			ret = -EIO;
 			break;
 		}