commit 01769e5f5f2822ca0660f55133d2bc1a2dd0f1c8
Author: Mateusz Guzik <mjg@FreeBSD.org>
Date:   Tue Apr 19 11:42:09 2022 +0200

    reclaim
    
    Reviewed by:
    Differential Revision:

diff --git a/sys/fs/nullfs/null_vfsops.c b/sys/fs/nullfs/null_vfsops.c
index fd119afa7f07..4d80ab66da93 100644
--- a/sys/fs/nullfs/null_vfsops.c
+++ b/sys/fs/nullfs/null_vfsops.c
@@ -201,6 +201,7 @@ nullfs_mount(struct mount *mp)
 		    &xmp->notify_node);
 	}
 
+	atomic_store_ptr(&mp->mnt_lowermount, lowerrootvp->v_mount);
 	MNT_ILOCK(mp);
 	if ((xmp->nullm_flags & NULLM_CACHE) != 0) {
 		mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index a495ad86ac46..1059ba0ec8c2 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -688,6 +688,7 @@ vfs_mount_alloc(struct vnode *vp, struct vfsconf *vfsp, const char *fspath,
 		    mp->mnt_vfs_ops);
 	(void) vfs_busy(mp, MBF_NOWAIT);
 	atomic_add_acq_int(&vfsp->vfc_refcount, 1);
+	mp->mnt_lowermount = NULL;
 	mp->mnt_op = vfsp->vfc_vfsops;
 	mp->mnt_vfc = vfsp;
 	mp->mnt_stat.f_type = vfsp->vfc_typenum;
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index a6344e139502..43a1416028a7 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1264,6 +1264,24 @@ SYSCTL_INT(_debug, OID_AUTO, max_vnlru_free, CTLFLAG_RW, &max_vnlru_free,
     0,
     "limit on vnode free requests per call to the vnlru_free routine");
 
+static bool
+vnlru_free_pick(struct vnode *vp, struct vfsops *mnt_op)
+{
+	struct mount *mp, *lmp;
+
+	mp = atomic_load_ptr(&vp->v_mount);
+	if (mp == NULL)
+		return (true);
+	if (mp->mnt_op == mnt_op)
+		return (true);
+	lmp = atomic_load_ptr(&mp->mnt_lowermount);
+	if (lmp == NULL)
+		return (false);
+	if (lmp->mnt_op == mnt_op)
+		return (true);
+	return (false);
+}
+
 /*
  * Attempt to reduce the free list by the requested amount.
  */
@@ -1299,8 +1317,7 @@ vnlru_free_impl(int count, struct vfsops *mnt_op, struct vnode *mvp)
 		 * check does not reach unmapped address even if
 		 * vnode is reclaimed.
 		 */
-		if (mnt_op != NULL && (mp = vp->v_mount) != NULL &&
-		    mp->mnt_op != mnt_op) {
+		if (mnt_op != NULL && !vnlru_free_pick(vp, mnt_op)) {
 			continue;
 		}
 		if (__predict_false(vp->v_type == VBAD || vp->v_type == VNON)) {
diff --git a/sys/sys/mount.h b/sys/sys/mount.h
index 3383bfe8f431..b56e84662960 100644
--- a/sys/sys/mount.h
+++ b/sys/sys/mount.h
@@ -262,6 +262,7 @@ struct mount {
 	STAILQ_ENTRY(mount) mnt_taskqueue_link;	/* (d) our place in deferred unmount list */
 	uint64_t	mnt_taskqueue_flags;	/* (d) unmount flags passed from taskqueue */
 	unsigned int	mnt_unmount_retries;	/* (d) # of failed deferred unmount attempts */
+	struct mount	*mnt_lowermount;
 };
 #endif	/* _WANT_MOUNT || _KERNEL */