btrfs: qgroup: warn about inconsistent qgroups when relation update fails

Calling btrfs_handle_fs_error() after btrfs_run_qgroups() fails to
update the qgroup status is probably not necessary, this would turn the
filesystem to read-only. For the same reason aborting the transaction is
also not a good option.

The state is left inconsistent and can be fixed by rescan, printing a
warning should be sufficient. Return code reflects the status of
adding/deleting the relation and if the transaction was ended properly.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ioctl.c

@@ -3880,8 +3880,9 @@ static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
 	err = btrfs_run_qgroups(trans);
 	mutex_unlock(&fs_info->qgroup_ioctl_lock);
 	if (err < 0)
-		btrfs_handle_fs_error(fs_info, err,
-				      "failed to update qgroup status and info");
+		btrfs_warn(fs_info,
+			   "qgroup status update failed after %s relation, marked as inconsistent",
+			   sa->assign ? "adding" : "deleting");
 	err = btrfs_end_transaction(trans);
 	if (err && !ret)
 		ret = err;