In null_reclaim(), assert that reclaimed vnode is fully constructed,

instead of accepting half-constructed vnode. Previous code cannot decide
what to do with such vnode anyway, and although processing it for hash
removal, paniced later when getting rid of nullfs reference on lowervp.

While there, remove initializations from the declaration block.

Tested by:	pho
MFC after:	1 week

1 files changed, 12 insertions, 9 deletions

diff --git a/sys/fs/nullfs/null_vnops.c b/sys/fs/nullfs/null_vnops.c
index e0645bd..b607666 100644
--- a/sys/fs/nullfs/null_vnops.c
+++ b/sys/fs/nullfs/null_vnops.c
@@ -697,12 +697,18 @@ null_inactive(struct vop_inactive_args *ap)
 static int
 null_reclaim(struct vop_reclaim_args *ap)
 {
-	struct vnode *vp = ap->a_vp;
-	struct null_node *xp = VTONULL(vp);
-	struct vnode *lowervp = xp->null_lowervp;
+	struct vnode *vp;
+	struct null_node *xp;
+	struct vnode *lowervp;
+
+	vp = ap->a_vp;
+	xp = VTONULL(vp);
+	lowervp = xp->null_lowervp;
+
+	KASSERT(lowervp != NULL && vp->v_vnlock != &vp->v_lock,
+	    ("Reclaiming inclomplete null vnode %p", vp));
 
-	if (lowervp)
-		null_hashrem(xp);
+	null_hashrem(xp);
 	/*
 	 * Use the interlock to protect the clearing of v_data to
 	 * prevent faults in null_lock().
@@ -713,10 +719,7 @@ null_reclaim(struct vop_reclaim_args *ap)
 	vp->v_object = NULL;
 	vp->v_vnlock = &vp->v_lock;
 	VI_UNLOCK(vp);
-	if (lowervp)
-		vput(lowervp);
-	else
-		panic("null_reclaim: reclaiming a node with no lowervp");
+	vput(lowervp);
 	free(xp, M_NULLFSNODE);
 
 	return (0);