[src/trunk]: src/sys/fs/union Set IMNT_MPSAFE only if all lower layers have i...

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

details:   https://anonhg.NetBSD.org/src/rev/eb3b95a1ffd2
branches:  trunk
changeset: 373372:eb3b95a1ffd2
user:      hannken <hannken%NetBSD.org@localhost>
date:      Mon Feb 06 10:33:32 2023 +0000

description:
Set IMNT_MPSAFE only if all lower layers have it set.

diffstat:

 sys/fs/union/union_vfsops.c |  13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)

diffs (34 lines):

diff -r 8a5129ee5489 -r eb3b95a1ffd2 sys/fs/union/union_vfsops.c
--- a/sys/fs/union/union_vfsops.c       Mon Feb 06 10:32:58 2023 +0000
+++ b/sys/fs/union/union_vfsops.c       Mon Feb 06 10:33:32 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: union_vfsops.c,v 1.85 2022/11/21 10:37:14 hannken Exp $        */
+/*     $NetBSD: union_vfsops.c,v 1.86 2023/02/06 10:33:32 hannken Exp $        */
 
 /*
  * Copyright (c) 1994 The Regents of the University of California.
@@ -77,7 +77,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: union_vfsops.c,v 1.85 2022/11/21 10:37:14 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: union_vfsops.c,v 1.86 2023/02/06 10:33:32 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -198,7 +198,14 @@
                goto bad;
        }
 
-       mp->mnt_iflag |= IMNT_MPSAFE;
+       /*
+        * This mount is mp-safe if both lower mounts are mp-safe.
+        */
+
+       if (((um->um_lowervp == NULLVP) ||
+           (um->um_lowervp->v_mount->mnt_iflag & IMNT_MPSAFE)) &&
+           (um->um_uppervp->v_mount->mnt_iflag & IMNT_MPSAFE))
+               mp->mnt_iflag |= IMNT_MPSAFE;
 
        /*
         * Unless the mount is readonly, ensure that the top layer