[src/trunk]: src/sys/kern Suspend file system before unmounting in mount_domo...

[hannken <hannken%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/5a4ebdae74af
branches:  trunk
changeset: 944846:5a4ebdae74af
user:      hannken <hannken%NetBSD.org@localhost>
date:      Tue Oct 13 13:15:39 2020 +0000

description:
Suspend file system before unmounting in mount_domount() error path
to prevent diagnostic assertions from unmount/flush.

Reported-by: syzbot+8d557f49c8b7888182eb%syzkaller.appspotmail.com@localhost
Reported-by: syzbot+e87fe1e769a3426d9bf3%syzkaller.appspotmail.com@localhost
Reported-by: syzbot+9c5b86e651e98c5bf438%syzkaller.appspotmail.com@localhost
Reported-by: syzbot+610b614af0d66179ca78%syzkaller.appspotmail.com@localhost
Reported-by: syzbot+7818ff113a1535ebc724%syzkaller.appspotmail.com@localhost

diffstat:

 sys/kern/vfs_mount.c |  7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diffs (30 lines):

diff -r b41a9799118b -r 5a4ebdae74af sys/kern/vfs_mount.c
--- a/sys/kern/vfs_mount.c      Tue Oct 13 11:28:32 2020 +0000
+++ b/sys/kern/vfs_mount.c      Tue Oct 13 13:15:39 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_mount.c,v 1.83 2020/05/23 23:42:43 ad Exp $        */
+/*     $NetBSD: vfs_mount.c,v 1.84 2020/10/13 13:15:39 hannken Exp $   */
 
 /*-
  * Copyright (c) 1997-2020 The NetBSD Foundation, Inc.
@@ -67,7 +67,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.83 2020/05/23 23:42:43 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.84 2020/10/13 13:15:39 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -832,8 +832,11 @@
        return error;
 
 err_mounted:
+       if (vfs_suspend(mp, 0))
+               panic("Suspending fresh file system failed");
        if (VFS_UNMOUNT(mp, MNT_FORCE) != 0)
                panic("Unmounting fresh file system failed");
+       vfs_resume(mp);
 
 err_unmounted:
        vp->v_mountedhere = NULL;