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>

diff --git a/fs/xfs/xfs_attr.c b/fs/xfs/xfs_attr.c
index 046cf3d..176dbb6 100644
--- a/fs/xfs/xfs_attr.c
+++ b/fs/xfs/xfs_attr.c
@@ -226,13 +226,14 @@
 	int		valuelen,
 	int		flags)
 {
-	xfs_da_args_t	args;
-	xfs_fsblock_t	firstblock;
-	xfs_bmap_free_t flist;
-	int		error, err2, committed;
-	xfs_mount_t	*mp = dp->i_mount;
-	int             rsvd = (flags & ATTR_ROOT) != 0;
-	int		local;
+	xfs_da_args_t		args;
+	xfs_fsblock_t		firstblock;
+	xfs_bmap_free_t		flist;
+	int			error, err2, committed;
+	struct xfs_mount	*mp = dp->i_mount;
+	struct xfs_trans_res	tres;
+	int			rsvd = (flags & ATTR_ROOT) != 0;
+	int			local;
 
 	/*
 	 * Attach the dquots to the inode.
@@ -292,11 +293,11 @@
 	if (rsvd)
 		args.trans->t_flags |= XFS_TRANS_RESERVE;
 
-	error = xfs_trans_reserve(args.trans, args.total,
-				  XFS_ATTRSETM_LOG_RES(mp) +
-				  XFS_ATTRSETRT_LOG_RES(mp) * args.total,
-				  0, XFS_TRANS_PERM_LOG_RES,
-				  XFS_ATTRSET_LOG_COUNT);
+	tres.tr_logres = M_RES(mp)->tr_attrsetm.tr_logres +
+			 M_RES(mp)->tr_attrsetrt.tr_logres * args.total;
+	tres.tr_logcount = XFS_ATTRSET_LOG_COUNT;
+	tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
+	error = xfs_trans_reserve(args.trans, &tres, args.total, 0);
 	if (error) {
 		xfs_trans_cancel(args.trans, 0);
 		return(error);
@@ -516,11 +517,9 @@
 	if (flags & ATTR_ROOT)
 		args.trans->t_flags |= XFS_TRANS_RESERVE;
 
-	if ((error = xfs_trans_reserve(args.trans,
-				      XFS_ATTRRM_SPACE_RES(mp),
-				      XFS_ATTRRM_LOG_RES(mp),
-				      0, XFS_TRANS_PERM_LOG_RES,
-				      XFS_ATTRRM_LOG_COUNT))) {
+	error = xfs_trans_reserve(args.trans, &M_RES(mp)->tr_attrrm,
+				  XFS_ATTRRM_SPACE_RES(mp), 0);
+	if (error) {
 		xfs_trans_cancel(args.trans, 0);
 		return(error);
 	}