From 823f741b15885d5bdaf8dd9daa9a31667ad48cfd Mon Sep 17 00:00:00 2001
From: deraadt <deraadt@openbsd.org>
Date: Thu, 14 Dec 2017 20:20:38 +0000
Subject: [PATCH] Give vflush_vnode() a hint about vnodes we don't need to
 account as "busy". Change mountpoint to RDONLY a little later.  Seems to
 improve the rw->ro transition a bit.

---
 sys/kern/vfs_subr.c      | 14 +++++++++-----
 sys/sys/vnode.h          |  4 ++--
 sys/ufs/ffs/ffs_vfsops.c |  7 +++----
 3 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 088a8f883b7..da17524a115 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_subr.c,v 1.263 2017/12/11 14:11:22 bluhm Exp $	*/
+/*	$OpenBSD: vfs_subr.c,v 1.264 2017/12/14 20:20:38 deraadt Exp $	*/
 /*	$NetBSD: vfs_subr.c,v 1.53 1996/04/22 01:39:13 christos Exp $	*/
 
 /*
@@ -904,11 +904,15 @@ vflush_vnode(struct vnode *vp, void *arg)
 		return (0);
 	}
 
-	if (va->flags & WRITEDEMOTE) {
-		vp->v_op = &dead_vops;
-		vp->v_tag = VT_NON;
+	/*
+	 * If set, this is allowed to ignore vnodes which don't
+	 * have changes pending to disk.
+	 * XXX Might be nice to check per-fs "inode" flags, but
+	 * generally the filesystem is sync'd already, right?
+	 */
+	if ((va->flags & IGNORECLEAN) &&
+	    LIST_EMPTY(&vp->v_dirtyblkhd))
 		return (0);
-	}
 
 #ifdef DEBUG
 	if (busyprt)
diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
index 6578c6d54ff..32a2d96f71c 100644
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vnode.h,v 1.141 2017/12/11 05:27:40 deraadt Exp $	*/
+/*	$OpenBSD: vnode.h,v 1.142 2017/12/14 20:20:38 deraadt Exp $	*/
 /*	$NetBSD: vnode.h,v 1.38 1996/02/29 20:59:05 cgd Exp $	*/
 
 /*
@@ -227,7 +227,7 @@ extern int		vttoif_tab[];
 #define	FORCECLOSE	0x0002		/* vflush: force file closeure */
 #define	WRITECLOSE	0x0004		/* vflush: only close writeable files */
 #define	DOCLOSE		0x0008		/* vclean: close active files */
-#define	WRITEDEMOTE	0x0010		/* vflush: ok if some writes remain */
+#define	IGNORECLEAN	0x0010		/* vflush: ignore clean vnodes */
 #define	V_SAVE		0x0001		/* vinvalbuf: sync file first */
 #define	V_SAVEMETA	0x0002		/* vinvalbuf: leave indirect blocks */
 
diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c
index a04cda2e70f..64af433a272 100644
--- a/sys/ufs/ffs/ffs_vfsops.c
+++ b/sys/ufs/ffs/ffs_vfsops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ffs_vfsops.c,v 1.169 2017/12/14 17:25:39 guenther Exp $	*/
+/*	$OpenBSD: ffs_vfsops.c,v 1.170 2017/12/14 20:20:38 deraadt Exp $	*/
 /*	$NetBSD: ffs_vfsops.c,v 1.19 1996/02/09 22:22:26 christos Exp $	*/
 
 /*
@@ -243,16 +243,14 @@ ffs_mount(struct mount *mp, const char *path, void *data,
 
 		if (ronly == 0 && (mp->mnt_flag & MNT_RDONLY)) {
 			/* Flush any dirty data */
-			mp->mnt_flag &= ~MNT_RDONLY;
 			VFS_SYNC(mp, MNT_WAIT, p->p_ucred, p);
-			mp->mnt_flag |= MNT_RDONLY;
 
 			/*
 			 * Get rid of files open for writing.
 			 */
 			flags = WRITECLOSE;
 			if (args == NULL)
-				flags |= WRITEDEMOTE;
+				flags |= IGNORECLEAN;
 			if (mp->mnt_flag & MNT_FORCE)
 				flags |= FORCECLOSE;
 			if (fs->fs_flags & FS_DOSOFTDEP) {
@@ -260,6 +258,7 @@ ffs_mount(struct mount *mp, const char *path, void *data,
 				mp->mnt_flag &= ~MNT_SOFTDEP;
 			} else
 				error = ffs_flushfiles(mp, flags, p);
+			mp->mnt_flag |= MNT_RDONLY;
 			ronly = 1;
 		}
 
-- 
2.20.1