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_trans.h b/fs/xfs/xfs_trans.h
index b5dc61e..7eb81cc 100644
--- a/fs/xfs/xfs_trans.h
+++ b/fs/xfs/xfs_trans.h
@@ -34,6 +34,7 @@
 struct xfs_log_item_desc;
 struct xfs_mount;
 struct xfs_trans;
+struct xfs_trans_res;
 struct xfs_dquot_acct;
 struct xfs_busy_extent;
 
@@ -170,7 +171,7 @@
 xfs_trans_t	*xfs_trans_alloc(struct xfs_mount *, uint);
 xfs_trans_t	*_xfs_trans_alloc(struct xfs_mount *, uint, xfs_km_flags_t);
 xfs_trans_t	*xfs_trans_dup(xfs_trans_t *);
-int		xfs_trans_reserve(xfs_trans_t *, uint, uint, uint,
+int		xfs_trans_reserve(struct xfs_trans *, struct xfs_trans_res *,
 				  uint, uint);
 void		xfs_trans_mod_sb(xfs_trans_t *, uint, int64_t);