xfs: always update params on small allocation

xfs_alloc_ag_vextent_small() doesn't update the output parameters in
the event of an AGFL allocation. Instead, it updates the
xfs_alloc_arg structure directly to complete the allocation.

Update both args and the output params to provide consistent
behavior for future callers.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_alloc.c

@@ -758,8 +758,8 @@ xfs_alloc_ag_vextent_small(
 		}
 		xfs_trans_binval(args->tp, bp);
 	}
-	args->len = 1;
-	args->agbno = fbno;
+	*fbnop = args->agbno = fbno;
+	*flenp = args->len = 1;
 	XFS_WANT_CORRUPTED_GOTO(args->mp,
 		fbno < be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length),
 		error);