git: dd16a5f53b0b - main - lockf: Do not block in vfs_busy()

The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=dd16a5f53b0b2e967d20d2900f18fc320997679b

commit dd16a5f53b0b2e967d20d2900f18fc320997679b
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2026-09-24 16:14:34 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2026-09-24 16:20:25 +0000

    lockf: Do not block in vfs_busy()
    
    A race is possible otherwise: vfs_busy() may return after an unmounted
    filesystem has been removed from the global mount list.  That is,
    vfs_busy() will block until vfs_mount_destroy() sets MNTK_REFEXPIRE, and
    at that point the mountpoint has been removed from the mountlist, so
    TAILQ_FOREACH can return an invalid value.
    
    Simply do not block if the mountpoint is being unmounted.
    
    Reviewed by:    kib
    Fixes:          eca39864f702 ("Add sysctl KERN_LOCKF")
    MFC after:      1 week
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D59982
---
 sys/kern/kern_lockf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sys/kern/kern_lockf.c b/sys/kern/kern_lockf.c
index a318c26484b4..2cb02b21cd78 100644
--- a/sys/kern/kern_lockf.c
+++ b/sys/kern/kern_lockf.c
@@ -2558,7 +2558,7 @@ sysctl_kern_lockf_run(struct sbuf *sb)
 	error = 0;
 	mtx_lock(&mountlist_mtx);
 	TAILQ_FOREACH(mp, &mountlist, mnt_list) {
-		error = vfs_busy(mp, MBF_MNTLSTLOCK);
+		error = vfs_busy(mp, MBF_MNTLSTLOCK | MBF_NOWAIT);
 		if (error != 0)
 			continue;
 		error = mp->mnt_op->vfs_report_lockf(mp, sb);