xfs: refactor xfs_trans_reserve() interface

With the new xfs_trans_res structure has been introduced, the log
reservation size, log count as well as log flags are pre-initialized
at mount time.  So it's time to refine xfs_trans_reserve() interface
to be more neat.

Also, introduce a new helper M_RES() to return a pointer to the
mp->m_resv structure to simplify the input.

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_dquot.c

@@ -712,10 +712,8 @@ xfs_qm_dqread(
 
 	if (flags & XFS_QMOPT_DQALLOC) {
 		tp = xfs_trans_alloc(mp, XFS_TRANS_QM_DQALLOC);
-		error = xfs_trans_reserve(tp, XFS_QM_DQALLOC_SPACE_RES(mp),
-					  XFS_QM_DQALLOC_LOG_RES(mp), 0,
-					  XFS_TRANS_PERM_LOG_RES,
-					  XFS_WRITE_LOG_COUNT);
+		error = xfs_trans_reserve(tp, &M_RES(mp)->tr_attrsetm,
+					  XFS_QM_DQALLOC_SPACE_RES(mp), 0);
 		if (error)
 			goto error1;
 		cancelflags = XFS_TRANS_RELEASE_LOG_RES;