xfs: check resblks before calling xfs_dir_canenter
Move the resblks test out of the xfs_dir_canenter,
and into the caller.
This makes a little more sense on the face of it;
xfs_dir_canenter immediately returns if resblks !=0;
and given some of the comments preceding the calls:
* Check for ability to enter directory entry, if no space reserved.
even more so.
It also facilitates the next patch.
Signed-off-by: Eric Sandeen <sandeen@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>