btrfs: Explicitly handle btrfs_update_root failure

btrfs_udpate_root can fail and it aborts the transaction, the correct
way to handle an aborted transaction is to explicitly end with
btrfs_end_transaction.  Even now the code is correct since
btrfs_commit_transaction would handle an aborted transaction but this is
more of an implementation detail. So let's be explicit in handling
failure in btrfs_update_root.

Furthermore btrfs_commit_transaction can also fail and by ignoring it's
return value we could have left the in-memory copy of the root item in
an inconsistent state. So capture the error value which allows us to
correctly revert the RO/RW flags in case of commit failure.

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

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index feab6f6..86728e0 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1827,8 +1827,13 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
 
        ret = btrfs_update_root(trans, fs_info->tree_root,
                                &root->root_key, &root->root_item);
+       if (ret < 0) {
+               btrfs_end_transaction(trans);
+               goto out_reset;
+       }
+
+       ret = btrfs_commit_transaction(trans);
 
-       btrfs_commit_transaction(trans);
 out_reset:
        if (ret)
                btrfs_set_root_flags(&root->root_item, root_flags);