xfs: saner xfs_trans_commit interface

The flags argument to xfs_trans_commit is not useful for most callers, as
a commit of a transaction without a permanent log reservation must pass
0 here, and all callers for a transaction with a permanent log reservation
except for xfs_trans_roll must pass XFS_TRANS_RELEASE_LOG_RES.  So remove
the flags argument from the public xfs_trans_commit interfaces, and
introduce low-level __xfs_trans_commit variant just for xfs_trans_roll
that regrants a log reservation instead of releasing it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 46598b7..0dec858 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -160,7 +160,7 @@
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 	if (flags & XFS_PREALLOC_SYNC)
 		xfs_trans_set_sync(tp);
-	return xfs_trans_commit(tp, 0);
+	return xfs_trans_commit(tp);
 }
 
 /*