git: 40cec659c167 - stable/13 - vfs_remount_ro(): mnt_lockref should be only accessed after vfs_op_enter()

The branch stable/13 has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=40cec659c167d1773826cf44f5ef6394cb0ad8fd

commit 40cec659c167d1773826cf44f5ef6394cb0ad8fd
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2023-09-20 03:42:31 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2023-09-28 09:06:23 +0000

    vfs_remount_ro(): mnt_lockref should be only accessed after vfs_op_enter()
    
    PR:     273953
    
    (cherry picked from commit c584bb9cac16bc200ac45cc8b709e7e7e99e24bb)
---
 sys/kern/vfs_mount.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index d81a42885a79..25c4adeaae62 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -2692,6 +2692,7 @@ vfs_remount_ro(struct mount *mp)
 	struct vnode *vp_covered, *rootvp;
 	int error;
 
+	vfs_op_enter(mp);
 	KASSERT(mp->mnt_lockref > 0,
 	    ("vfs_remount_ro: mp %p is not busied", mp));
 	KASSERT((mp->mnt_kern_flag & MNTK_UNMOUNT) == 0,
@@ -2700,17 +2701,19 @@ vfs_remount_ro(struct mount *mp)
 	rootvp = NULL;
 	vp_covered = mp->mnt_vnodecovered;
 	error = vget(vp_covered, LK_EXCLUSIVE | LK_NOWAIT);
-	if (error != 0)
+	if (error != 0) {
+		vfs_op_exit(mp);
 		return (error);
+	}
 	VI_LOCK(vp_covered);
 	if ((vp_covered->v_iflag & VI_MOUNT) != 0) {
 		VI_UNLOCK(vp_covered);
 		vput(vp_covered);
+		vfs_op_exit(mp);
 		return (EBUSY);
 	}
 	vp_covered->v_iflag |= VI_MOUNT;
 	VI_UNLOCK(vp_covered);
-	vfs_op_enter(mp);
 	vn_seqc_write_begin(vp_covered);
 
 	MNT_ILOCK(mp);