xfs: split and cleanup xfs_log_reserve

Split the log regrant case out of xfs_log_reserve into a separate function,
and merge xlog_grant_log_space and xlog_regrant_write_log_space into their
respective callers.  Also replace the XFS_LOG_PERM_RESERV flag, which easily
got misused before the previous cleanups with a simple boolean parameter.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 7adcdf1..103b00c 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -681,7 +681,6 @@
 	uint		flags,
 	uint		logcount)
 {
-	int		log_flags;
 	int		error = 0;
 	int		rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0;
 
@@ -707,24 +706,32 @@
 	 * Reserve the log space needed for this transaction.
 	 */
 	if (logspace > 0) {
-		ASSERT((tp->t_log_res == 0) || (tp->t_log_res == logspace));
-		ASSERT((tp->t_log_count == 0) ||
-			(tp->t_log_count == logcount));
+		bool	permanent = false;
+
+		ASSERT(tp->t_log_res == 0 || tp->t_log_res == logspace);
+		ASSERT(tp->t_log_count == 0 || tp->t_log_count == logcount);
+
 		if (flags & XFS_TRANS_PERM_LOG_RES) {
-			log_flags = XFS_LOG_PERM_RESERV;
 			tp->t_flags |= XFS_TRANS_PERM_LOG_RES;
+			permanent = true;
 		} else {
 			ASSERT(tp->t_ticket == NULL);
 			ASSERT(!(tp->t_flags & XFS_TRANS_PERM_LOG_RES));
-			log_flags = 0;
 		}
 
-		error = xfs_log_reserve(tp->t_mountp, logspace, logcount,
-					&tp->t_ticket,
-					XFS_TRANSACTION, log_flags, tp->t_type);
-		if (error) {
-			goto undo_blocks;
+		if (tp->t_ticket != NULL) {
+			ASSERT(flags & XFS_TRANS_PERM_LOG_RES);
+			error = xfs_log_regrant(tp->t_mountp, tp->t_ticket);
+		} else {
+			error = xfs_log_reserve(tp->t_mountp, logspace,
+						logcount, &tp->t_ticket,
+						XFS_TRANSACTION, permanent,
+						tp->t_type);
 		}
+
+		if (error)
+			goto undo_blocks;
+
 		tp->t_log_res = logspace;
 		tp->t_log_count = logcount;
 	}
@@ -752,6 +759,8 @@
 	 */
 undo_log:
 	if (logspace > 0) {
+		int		log_flags;
+
 		if (flags & XFS_TRANS_PERM_LOG_RES) {
 			log_flags = XFS_LOG_REL_PERM_RESERV;
 		} else {