btrfs-progs: mkfs: error out gracefully for --rootdir

--rootdir option will start a transaction to fill the fs, however if
something goes wrong, from ENOSPC to lack of permission, we won't commit
the transaction and cause BUG_ON triggered by uncommitted transaction:

------
extent buffer leak: start 29392896 len 16384
extent_io.c:579: free_extent_buffer: BUG_ON `eb->flags & EXTENT_DIRTY` triggered, value 1
------

The root fix is to introduce btrfs_abort_transaction() in btrfs-progs,
however in this particular case, we can workaround it by force
committing the transaction.

Since during mkfs, the magic of btrfs is set to an invalid one, without
setting fs_info->finalize_on_close() the fs is never able to be mounted.
So even we force to commit wrong transaction we won't screw up things
worse.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/mkfs/main.c b/mkfs/main.c
index 284dbd7..7d9fa38 100644 (file)
--- a/mkfs/main.c
+++ b/mkfs/main.c
@@ -1073,6 +1073,19 @@ static int make_image(const char *source_dir, struct btrfs_root *root)
                printf("Making image is completed.\n");
        return 0;
 fail:
+       /*
+        * Since we don't have btrfs_abort_transaction() yet, uncommitted trans
+        * will trigger a BUG_ON().
+        *
+        * However before mkfs is fully finished, the magic number is invalid,
+        * so even we commit transaction here, the fs still can't be mounted.
+        *
+        * To do a graceful error out, here we commit transaction as a
+        * workaround.
+        * Since we have already hit some problem, the return value doesn't
+        * matter now.
+        */
+       btrfs_commit_transaction(trans, root);
        while (!list_empty(&dir_head.list)) {
                dir_entry = list_entry(dir_head.list.next,
                                       struct directory_name_entry, list);