xfs: kill xfs_qmops

Kill the quota ops function vector and replace it with direct calls or
stubs in the CONFIG_XFS_QUOTA=n case.

Make sure we check XFS_IS_QUOTA_RUNNING in the right spots.  We can remove
the number of those checks because the XFS_TRANS_DQ_DIRTY flag can't be set
otherwise.

This brings us back closer to the way this code worked in IRIX and earlier
Linux versions, but we keep a lot of the more useful factoring of common
code.

Eventually we should also kill xfs_qm_bhv.c, but that's left for a later
patch.

Reduces the size of the source code by about 250 lines and the size of
XFS module by about 1.5 kilobytes with quotas enabled:

   text	   data	    bss	    dec	    hex	filename
 615957	   2960	   3848	 622765	  980ad	fs/xfs/xfs.o
 617231	   3152	   3848	 624231	  98667	fs/xfs/xfs.o.old

Fallout:

 - xfs_qm_dqattach is split into xfs_qm_dqattach_locked which expects
   the inode locked and xfs_qm_dqattach which does the locking around it,
   thus removing XFS_QMOPT_ILOCKED.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
diff --git a/fs/xfs/xfs_rename.c b/fs/xfs/xfs_rename.c
index 58f85e9..b81deea 100644
--- a/fs/xfs/xfs_rename.c
+++ b/fs/xfs/xfs_rename.c
@@ -166,7 +166,8 @@
 	/*
 	 * Attach the dquots to the inodes
 	 */
-	if ((error = XFS_QM_DQVOPRENAME(mp, inodes))) {
+	error = xfs_qm_vop_rename_dqattach(inodes);
+	if (error) {
 		xfs_trans_cancel(tp, cancel_flags);
 		goto std_return;
 	}