- Use vrefcnt() where it is safe to do so instead of doing direct and

   unlocked accesses to v_usecount.
 - Lock access to the buf lists in the various sync routines.  interlock
   locking could be avoided almost entirely in leaf filesystems if the
   fsync function had a generic helper.

18 files changed, 71 insertions, 60 deletions

diff --git a/sys/fs/fifofs/fifo_vnops.c b/sys/fs/fifofs/fifo_vnops.c
index 7ce50fc..a7d2f3e 100644
--- a/sys/fs/fifofs/fifo_vnops.c
+++ b/sys/fs/fifofs/fifo_vnops.c
@@ -528,7 +528,7 @@ fifo_close(ap)
 		if (fip->fi_writers == 0)
 			socantrcvmore(fip->fi_readsock);
 	}
-	if (vp->v_usecount > 1)
+	if (vrefcnt(vp) > 1)
 		return (0);
 	error1 = soclose(fip->fi_readsock);
 	error2 = soclose(fip->fi_writesock);
diff --git a/sys/fs/hpfs/hpfs_vnops.c b/sys/fs/hpfs/hpfs_vnops.c
index b862bad..c3ddec5 100644
--- a/sys/fs/hpfs/hpfs_vnops.c
+++ b/sys/fs/hpfs/hpfs_vnops.c
@@ -95,11 +95,15 @@ hpfs_fsync(ap)
 	 * Flush all dirty buffers associated with a vnode.
 	 */
 loop:
+	VI_LOCK(vp);
 	s = splbio();
 	for (bp = TAILQ_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
 		nbp = TAILQ_NEXT(bp, b_vnbufs);
-		if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT))
+		VI_UNLOCK(vp);
+		if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
+			VI_LOCK(vp);
 			continue;
+		}
 		if ((bp->b_flags & B_DELWRI) == 0)
 			panic("hpfs_fsync: not dirty");
 		bremfree(bp);
@@ -107,19 +111,18 @@ loop:
 		(void) bwrite(bp);
 		goto loop;
 	}
-	VI_LOCK(vp);
 	while (vp->v_numoutput) {
 		vp->v_iflag |= VI_BWAIT;
 		msleep((caddr_t)&vp->v_numoutput, VI_MTX(vp), PRIBIO + 1,
 		    "hpfsn", 0);
 	}
-	VI_UNLOCK(vp);
 #ifdef DIAGNOSTIC
 	if (!TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
 		vprint("hpfs_fsync: dirty", vp);
 		goto loop;
 	}
 #endif
+	VI_UNLOCK(vp);
 	splx(s);
 
 	/*
@@ -604,7 +607,7 @@ hpfs_inactive(ap)
 			return (error);
 	}
 
-	if (prtactive && vp->v_usecount != 0)
+	if (prtactive && vrefcnt(vp) != 0)
 		vprint("hpfs_inactive: pushing active", vp);
 
 	if (hp->h_flag & H_INVAL) {
diff --git a/sys/fs/msdosfs/msdosfs_denode.c b/sys/fs/msdosfs/msdosfs_denode.c
index 9b12552..6a141bec 100644
--- a/sys/fs/msdosfs/msdosfs_denode.c
+++ b/sys/fs/msdosfs/msdosfs_denode.c
@@ -653,7 +653,7 @@ msdosfs_reclaim(ap)
 	    dep, dep->de_Name, dep->de_refcnt);
 #endif
 
-	if (prtactive && vp->v_usecount != 0)
+	if (prtactive && vrefcnt(vp) != 0)
 		vprint("msdosfs_reclaim(): pushing active", vp);
 	/*
 	 * Remove the denode from its hash chain.
@@ -693,7 +693,7 @@ msdosfs_inactive(ap)
 	printf("msdosfs_inactive(): dep %p, de_Name[0] %x\n", dep, dep->de_Name[0]);
 #endif
 
-	if (prtactive && vp->v_usecount != 0)
+	if (prtactive && vrefcnt(vp) != 0)
 		vprint("msdosfs_inactive(): pushing active", vp);
 
 	/*
@@ -725,8 +725,8 @@ out:
 	 * so that it can be reused immediately.
 	 */
 #ifdef MSDOSFS_DEBUG
-	printf("msdosfs_inactive(): v_usecount %d, de_Name[0] %x\n", vp->v_usecount,
-	       dep->de_Name[0]);
+	printf("msdosfs_inactive(): v_usecount %d, de_Name[0] %x\n",
+	       vrefcnt(vp), dep->de_Name[0]);
 #endif
 	if (dep->de_Name[0] == SLOT_DELETED)
 		vrecycle(vp, NULL, td);
diff --git a/sys/fs/msdosfs/msdosfs_vfsops.c b/sys/fs/msdosfs/msdosfs_vfsops.c
index bd3703d..f7994b6 100644
--- a/sys/fs/msdosfs/msdosfs_vfsops.c
+++ b/sys/fs/msdosfs/msdosfs_vfsops.c
@@ -635,6 +635,7 @@ msdosfs_unmount(mp, mntflags, td)
 	{
 		struct vnode *vp = pmp->pm_devvp;
 
+		VI_LOCK(vp);
 		printf("msdosfs_umount(): just before calling VOP_CLOSE()\n");
 		printf("iflag %08lx, usecount %d, writecount %d, holdcnt %ld\n",
 		    vp->vi_flag, vp->v_usecount, vp->v_writecount,
@@ -652,6 +653,7 @@ msdosfs_unmount(mp, mntflags, td)
 		    vp->v_socket, vp->v_tag,
 		    ((u_int *)vp->v_data)[0],
 		    ((u_int *)vp->v_data)[1]);
+		VI_UNLOCK(vp);
 	}
 #endif
 	error = VOP_CLOSE(pmp->pm_devvp,
@@ -747,13 +749,13 @@ loop:
 		nvp = TAILQ_NEXT(vp, v_nmntvnodes);
 
 		mtx_unlock(&mntvnode_mtx);
-		mtx_lock(&vp->v_interlock);
+		VI_LOCK(vp);
 		dep = VTODE(vp);
 		if (vp->v_type == VNON ||
 		    ((dep->de_flag &
 		    (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0 &&
 		    (TAILQ_EMPTY(&vp->v_dirtyblkhd) || waitfor == MNT_LAZY))) {
-			mtx_unlock(&vp->v_interlock);
+			VI_UNLOCK(vp);
 			mtx_lock(&mntvnode_mtx);
 			continue;
 		}
diff --git a/sys/fs/msdosfs/msdosfs_vnops.c b/sys/fs/msdosfs/msdosfs_vnops.c
index b7d4f7c..b7ef69f 100644
--- a/sys/fs/msdosfs/msdosfs_vnops.c
+++ b/sys/fs/msdosfs/msdosfs_vnops.c
@@ -218,12 +218,12 @@ msdosfs_close(ap)
 	struct denode *dep = VTODE(vp);
 	struct timespec ts;
 
-	mtx_lock(&vp->v_interlock);
+	VI_LOCK(vp);
 	if (vp->v_usecount > 1) {
 		getnanotime(&ts);
 		DETIMES(dep, &ts, &ts, &ts);
 	}
-	mtx_unlock(&vp->v_interlock);
+	VI_UNLOCK(vp);
 	return 0;
 }
 
@@ -818,13 +818,15 @@ loop:
 	VI_LOCK(vp);
 	for (bp = TAILQ_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
 		nbp = TAILQ_NEXT(bp, b_vnbufs);
-		if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT))
+		VI_UNLOCK(vp);
+		if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
+			VI_LOCK(vp);
 			continue;
+		}
 		if ((bp->b_flags & B_DELWRI) == 0)
 			panic("msdosfs_fsync: not dirty");
 		bremfree(bp);
 		splx(s);
-		VI_UNLOCK(vp);
 		/* XXX Could do bawrite */
 		(void) bwrite(bp);
 		goto loop;
@@ -834,13 +836,13 @@ loop:
 		(void) msleep((caddr_t)&vp->v_numoutput, VI_MTX(vp),
 		    PRIBIO + 1, "msdosfsn", 0);
 	}
-	VI_UNLOCK(vp);
 #ifdef DIAGNOSTIC
 	if (!TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
 		vprint("msdosfs_fsync: dirty", vp);
 		goto loop;
 	}
 #endif
+	VI_UNLOCK(vp);
 	splx(s);
 	return (deupdat(VTODE(vp), ap->a_waitfor == MNT_WAIT));
 }
diff --git a/sys/fs/ntfs/ntfs_vfsops.c b/sys/fs/ntfs/ntfs_vfsops.c
index 1f3ba62..e91791a 100644
--- a/sys/fs/ntfs/ntfs_vfsops.c
+++ b/sys/fs/ntfs/ntfs_vfsops.c
@@ -488,7 +488,7 @@ ntfs_unmount(
 	/* Check if only system vnodes are rest */
 	for(i=0;i<NTFS_SYSNODESNUM;i++)
 		 if((ntmp->ntm_sysvn[i]) && 
-		    (ntmp->ntm_sysvn[i]->v_usecount > 1)) return (EBUSY);
+		    (vrefcnt(ntmp->ntm_sysvn[i]) > 1)) return (EBUSY);
 
 	/* Dereference all system vnodes */
 	for(i=0;i<NTFS_SYSNODESNUM;i++)
diff --git a/sys/fs/ntfs/ntfs_vnops.c b/sys/fs/ntfs/ntfs_vnops.c
index fc46617..d46b88b 100644
--- a/sys/fs/ntfs/ntfs_vnops.c
+++ b/sys/fs/ntfs/ntfs_vnops.c
@@ -196,7 +196,7 @@ ntfs_inactive(ap)
 
 	dprintf(("ntfs_inactive: vnode: %p, ntnode: %d\n", vp, ip->i_number));
 
-	if (ntfs_prtactive && vp->v_usecount != 0)
+	if (ntfs_prtactive && vrefcnt(vp) != 0)
 		vprint("ntfs_inactive: pushing active", vp);
 
 	VOP_UNLOCK(vp, 0, ap->a_td);
@@ -223,7 +223,7 @@ ntfs_reclaim(ap)
 
 	dprintf(("ntfs_reclaim: vnode: %p, ntnode: %d\n", vp, ip->i_number));
 
-	if (ntfs_prtactive && vp->v_usecount != 0)
+	if (ntfs_prtactive && vrefcnt(vp) != 0)
 		vprint("ntfs_reclaim: pushing active", vp);
 
 	if ((error = ntfs_ntget(ip)) != 0)
diff --git a/sys/fs/nullfs/null_subr.c b/sys/fs/nullfs/null_subr.c
index fd8d9be..1fdd210 100644
--- a/sys/fs/nullfs/null_subr.c
+++ b/sys/fs/nullfs/null_subr.c
@@ -321,7 +321,7 @@ null_checkvp(vp, fil, lno)
 		while (null_checkvp_barrier) /*WAIT*/ ;
 		panic("null_checkvp");
 	}
-	if (a->null_lowervp->v_usecount < 1) {
+	if (vrefcnt(a->null_lowervp) < 1) {
 		int i; u_long *p;
 		printf("vp = %p, unref'ed lowervp\n", (void *)vp);
 		for (p = (u_long *) a, i = 0; i < 8; i++)
@@ -333,8 +333,8 @@ null_checkvp(vp, fil, lno)
 	};
 #ifdef notyet
 	printf("null %x/%d -> %x/%d [%s, %d]\n",
-	        NULLTOV(a), NULLTOV(a)->v_usecount,
-		a->null_lowervp, a->null_lowervp->v_usecount,
+	        NULLTOV(a), vrefcnt(NULLTOV(a)),
+		a->null_lowervp, vrefcnt(a->null_lowervp),
 		fil, lno);
 #endif
 	return a->null_lowervp;
diff --git a/sys/fs/nwfs/nwfs_node.c b/sys/fs/nwfs/nwfs_node.c
index 7a85d55..1d599fc 100644
--- a/sys/fs/nwfs/nwfs_node.c
+++ b/sys/fs/nwfs/nwfs_node.c
@@ -103,8 +103,8 @@ nwfs_sysctl_vnprint(SYSCTL_HANDLER_ARGS) {
 		LIST_FOREACH(np, nhpp, n_hash) {
 			vp = NWTOV(np);
 			vprint(NULL, vp);
-			printf("%s:%d:%d:%d:%d\n",np->n_name,vp->v_usecount,vp->v_holdcnt,
-			    np->n_fid.f_id, np->n_fid.f_parent);
+			printf("%s:%d:%d:%d:%d\n",np->n_name,vrefcnt(vp),
+			    vp->v_holdcnt,np->n_fid.f_id, np->n_fid.f_parent);
 		}
 	}
 	return 0;
@@ -256,7 +256,7 @@ nwfs_reclaim(ap)
 	struct nwmount *nmp = VTONWFS(vp);
 	struct thread *td = ap->a_td;
 	
-	NCPVNDEBUG("%s,%d\n", np->n_name, vp->v_usecount);
+	NCPVNDEBUG("%s,%d\n", np->n_name, vrefcnt(vp));
 	if (np->n_flag & NREFPARENT) {
 		np->n_flag &= ~NREFPARENT;
 		if (nwfs_lookupnp(nmp, np->n_parent, td, &dnp) == 0) {
@@ -293,7 +293,7 @@ nwfs_inactive(ap)
 	struct nwnode *np = VTONW(vp);
 	int error;
 
-	NCPVNDEBUG("%s: %d\n", VTONW(vp)->n_name, vp->v_usecount);
+	NCPVNDEBUG("%s: %d\n", VTONW(vp)->n_name, vrefcnt(vp));
 	if (np->opened) {
 		error = nwfs_vinvalbuf(vp, V_SAVE, cred, td, 1);
 		error = ncp_close_file(NWFSTOCONN(VTONWFS(vp)), &np->n_fh, td, cred);
diff --git a/sys/fs/nwfs/nwfs_vfsops.c b/sys/fs/nwfs/nwfs_vfsops.c
index 76776d9..f097b3e 100644
--- a/sys/fs/nwfs/nwfs_vfsops.c
+++ b/sys/fs/nwfs/nwfs_vfsops.c
@@ -221,7 +221,7 @@ static int nwfs_mount(struct mount *mp, char *path, caddr_t data,
 	 * Lose the lock but keep the ref.
 	 */
 	VOP_UNLOCK(vp, 0, curthread);
-	NCPVODEBUG("rootvp.vrefcnt=%d\n",vp->v_usecount);
+	NCPVODEBUG("rootvp.vrefcnt=%d\n",vrefcnt(vp));
 	return error;
 bad:
         if (nmp)
@@ -490,10 +490,10 @@ loop:
 			goto loop;
 		nvp = TAILQ_NEXT(vp, v_nmntvnodes);
 		mtx_unlock(&mntvnode_mtx);
-		mtx_lock(&vp->v_interlock);
+		VI_LOCK(vp);
 		if (VOP_ISLOCKED(vp, NULL) || TAILQ_EMPTY(&vp->v_dirtyblkhd) ||
 		    waitfor == MNT_LAZY) {
-			mtx_unlock(&vp->v_interlock);
+			VI_UNLOCK(vp);
 			mtx_lock(&mntvnode_mtx);
 			continue;
 		}
diff --git a/sys/fs/nwfs/nwfs_vnops.c b/sys/fs/nwfs/nwfs_vnops.c
index b62f4f8..d1ecd32 100644
--- a/sys/fs/nwfs/nwfs_vnops.c
+++ b/sys/fs/nwfs/nwfs_vnops.c
@@ -490,7 +490,7 @@ nwfs_remove(ap)
 	struct nwmount *nmp = VTONWFS(vp);
 	int error;
 
-	if (vp->v_type == VDIR || np->opened || vp->v_usecount != 1)
+	if (vp->v_type == VDIR || np->opened || vrefcnt(vp) != 1)
 		return EPERM;
 	cache_purge(vp);
 	error = ncp_DeleteNSEntry(nmp, VTONW(dvp)->n_fid.f_id,
@@ -533,7 +533,7 @@ nwfs_rename(ap)
 		goto out;
 	}
 
-	if (tvp && tvp->v_usecount > 1) {
+	if (tvp && vrefcnt(tvp) > 1) {
 		error = EBUSY;
 		goto out;
 	}
diff --git a/sys/fs/pseudofs/pseudofs_vnops.c b/sys/fs/pseudofs/pseudofs_vnops.c
index 6298fb9..932adc0 100644
--- a/sys/fs/pseudofs/pseudofs_vnops.c
+++ b/sys/fs/pseudofs/pseudofs_vnops.c
@@ -135,7 +135,7 @@ pfs_close(struct vop_close_args *va)
 	 * Do nothing unless this is the last close and the node has a
 	 * last-close handler.
 	 */
-	if (vn->v_usecount > 1 || pn->pn_close == NULL)
+	if (vrefcnt(vn) > 1 || pn->pn_close == NULL)
 		PFS_RETURN (0);
 
 	if (pvd->pvd_pid != NO_PID)
diff --git a/sys/fs/smbfs/smbfs_node.c b/sys/fs/smbfs/smbfs_node.c
index 33055a4..edd62b7 100644
--- a/sys/fs/smbfs/smbfs_node.c
+++ b/sys/fs/smbfs/smbfs_node.c
@@ -298,7 +298,7 @@ smbfs_reclaim(ap)
 	struct smbnode *np = VTOSMB(vp);
 	struct smbmount *smp = VTOSMBFS(vp);
 	
-	SMBVDEBUG("%s,%d\n", np->n_name, vp->v_usecount);
+	SMBVDEBUG("%s,%d\n", np->n_name, vrefcnt(vp));
 
 	smbfs_hash_lock(smp, td);
 
@@ -344,7 +344,7 @@ smbfs_inactive(ap)
 	struct smb_cred scred;
 	int error;
 
-	SMBVDEBUG("%s: %d\n", VTOSMB(vp)->n_name, vp->v_usecount);
+	SMBVDEBUG("%s: %d\n", VTOSMB(vp)->n_name, vrefcnt(vp));
 	if (np->n_opencount) {
 		error = smbfs_vinvalbuf(vp, V_SAVE, cred, td, 1);
 		smb_makescred(&scred, td, cred);
diff --git a/sys/fs/smbfs/smbfs_vfsops.c b/sys/fs/smbfs/smbfs_vfsops.c
index 2c847c3..8dba8c8 100644
--- a/sys/fs/smbfs/smbfs_vfsops.c
+++ b/sys/fs/smbfs/smbfs_vfsops.c
@@ -209,7 +209,7 @@ smbfs_mount(struct mount *mp, char *path, caddr_t data,
 	if (error)
 		goto bad;
 	VOP_UNLOCK(vp, 0, td);
-	SMBVDEBUG("root.v_usecount = %d\n", vp->v_usecount);
+	SMBVDEBUG("root.v_usecount = %d\n", vrefcnt(vp));
 
 #ifdef DIAGNOSTICS
 	SMBERROR("mp=%p\n", mp);
@@ -426,14 +426,17 @@ loop:
 		 */
 		if (vp->v_mount != mp)
 			goto loop;
+		VI_LOCK(vp);
 #ifndef FB_RELENG3
 		if (VOP_ISLOCKED(vp, NULL) || TAILQ_EMPTY(&vp->v_dirtyblkhd) ||
 #else
 		if (VOP_ISLOCKED(vp) || TAILQ_EMPTY(&vp->v_dirtyblkhd) ||
 #endif
-		    waitfor == MNT_LAZY)
+		    waitfor == MNT_LAZY) {
+			VI_UNLOCK(vp);
 			continue;
-		if (vget(vp, LK_EXCLUSIVE, td))
+		}
+		if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, td))
 			goto loop;
 		error = VOP_FSYNC(vp, cred, waitfor, td);
 		if (error)
diff --git a/sys/fs/smbfs/smbfs_vnops.c b/sys/fs/smbfs/smbfs_vnops.c
index 35c7d74..144e3f8 100644
--- a/sys/fs/smbfs/smbfs_vnops.c
+++ b/sys/fs/smbfs/smbfs_vnops.c
@@ -579,7 +579,7 @@ smbfs_remove(ap)
 	struct smb_cred scred;
 	int error;
 
-	if (vp->v_type == VDIR || np->n_opencount || vp->v_usecount != 1)
+	if (vp->v_type == VDIR || np->n_opencount || vrefcnt(vp) != 1)
 		return EPERM;
 	smb_makescred(&scred, cnp->cn_thread, cnp->cn_cred);
 	error = smbfs_smb_delete(np, &scred);
@@ -618,7 +618,7 @@ smbfs_rename(ap)
 		goto out;
 	}
 
-	if (tvp && tvp->v_usecount > 1) {
+	if (tvp && vrefcnt(tvp) > 1) {
 		error = EBUSY;
 		goto out;
 	}
@@ -1183,6 +1183,7 @@ smbfs_lookup(ap)
 		int vpid;
 
 		vp = *vpp;
+		mp_fixme("Unlocked v_id access.");
 		vpid = vp->v_id;
 		if (dvp == vp) {	/* lookup on current */
 			vref(vp);
diff --git a/sys/fs/umapfs/umap_subr.c b/sys/fs/umapfs/umap_subr.c
index 4be0eb1..d3fed34 100644
--- a/sys/fs/umapfs/umap_subr.c
+++ b/sys/fs/umapfs/umap_subr.c
@@ -328,7 +328,7 @@ umap_checkvp(vp, fil, lno)
 		while (umap_checkvp_barrier) /*WAIT*/ ;
 		panic("umap_checkvp");
 	}
-	if (a->umap_lowervp->v_usecount < 1) {
+	if (vrefcnt(a->umap_lowervp) < 1) {
 		int i; u_long *p;
 		printf("vp = %p, unref'ed lowervp\n", (void *)vp);
 		for (p = (u_long *) a, i = 0; i < 8; i++)
diff --git a/sys/fs/unionfs/union_subr.c b/sys/fs/unionfs/union_subr.c
index b17dac8..cc06e77 100644
--- a/sys/fs/unionfs/union_subr.c
+++ b/sys/fs/unionfs/union_subr.c
@@ -486,16 +486,16 @@ loop:
 		 */
 		UDEBUG(("Modify existing un %p vn %p upper %p(refs %d) -> %p(refs %d)\n",
 			un, un->un_vnode, un->un_uppervp, 
-			(un->un_uppervp ? un->un_uppervp->v_usecount : -99),
+			(un->un_uppervp ? vrefcnt(un->un_uppervp) : -99),
 			uppervp,
-			(uppervp ? uppervp->v_usecount : -99)
+			(uppervp ? vrefcnt(uppervp) : -99)
 		));
 
 		if (uppervp != un->un_uppervp) {
-			KASSERT(uppervp == NULL || uppervp->v_usecount > 0, ("union_allocvp: too few refs %d (at least 1 required) on uppervp", uppervp->v_usecount));
+			KASSERT(uppervp == NULL || vrefcnt(uppervp) > 0, ("union_allocvp: too few refs %d (at least 1 required) on uppervp", vrefcnt(uppervp)));
 			union_newupper(un, uppervp);
 		} else if (uppervp) {
-			KASSERT(uppervp->v_usecount > 1, ("union_allocvp: too few refs %d (at least 2 required) on uppervp", uppervp->v_usecount));
+			KASSERT(vrefcnt(uppervp) > 1, ("union_allocvp: too few refs %d (at least 2 required) on uppervp", vrefcnt(uppervp)));
 			vrele(uppervp);
 		}
 
@@ -776,7 +776,7 @@ union_copyup(un, docopy, cred, td)
 
 	lvp = un->un_lowervp;
 
-	KASSERT(uvp->v_usecount > 0, ("copy: uvp refcount 0: %d", uvp->v_usecount));
+	KASSERT(vrefcnt(uvp) > 0, ("copy: uvp refcount 0: %d", vrefcnt(uvp)));
 	if (docopy) {
 		/*
 		 * XX - should not ignore errors
@@ -798,9 +798,9 @@ union_copyup(un, docopy, cred, td)
 	VOP_UNLOCK(uvp, 0, td);
 	vn_finished_write(mp);
 	union_newupper(un, uvp);
-	KASSERT(uvp->v_usecount > 0, ("copy: uvp refcount 0: %d", uvp->v_usecount));
+	KASSERT(vrefcnt(uvp) > 0, ("copy: uvp refcount 0: %d", vrefcnt(uvp)));
 	union_vn_close(uvp, FWRITE, cred, td);
-	KASSERT(uvp->v_usecount > 0, ("copy: uvp refcount 0: %d", uvp->v_usecount));
+	KASSERT(vrefcnt(uvp) > 0, ("copy: uvp refcount 0: %d", vrefcnt(uvp)));
 	/*
 	 * Subsequent IOs will go to the top layer, so
 	 * call close on the lower vnode and open on the
@@ -1279,10 +1279,10 @@ union_dircache(vp, td)
 		goto out;
 
 	/*vn_lock(*vpp, LK_EXCLUSIVE | LK_RETRY, td);*/
-	UDEBUG(("ALLOCVP-3 %p ref %d\n", *vpp, (*vpp ? (*vpp)->v_usecount : -99)));
+	UDEBUG(("ALLOCVP-3 %p ref %d\n", *vpp, (*vpp ? vrefcnt(*vpp) : -99)));
 	VREF(*vpp);
 	error = union_allocvp(&nvp, vp->v_mount, NULLVP, NULLVP, NULL, *vpp, NULLVP, 0);
-	UDEBUG(("ALLOCVP-3B %p ref %d\n", nvp, (*vpp ? (*vpp)->v_usecount : -99)));
+	UDEBUG(("ALLOCVP-3B %p ref %d\n", nvp, (*vpp ? vrefcnt(*vpp) : -99)));
 	if (error)
 		goto out;
 
diff --git a/sys/fs/unionfs/union_vnops.c b/sys/fs/unionfs/union_vnops.c
index 264e39d..3ceb89f 100644
--- a/sys/fs/unionfs/union_vnops.c
+++ b/sys/fs/unionfs/union_vnops.c
@@ -117,7 +117,7 @@ union_lock_upper(struct union_node *un, struct thread *td)
 		VREF(uppervp);
 		vn_lock(uppervp, LK_EXCLUSIVE | LK_CANRECURSE | LK_RETRY, td);
 	}
-	KASSERT((uppervp == NULL || uppervp->v_usecount > 0), ("uppervp usecount is 0"));
+	KASSERT((uppervp == NULL || vrefcnt(uppervp) > 0), ("uppervp usecount is 0"));
 	return(uppervp);
 }
 
@@ -361,10 +361,10 @@ union_lookup(ap)
 		    "uerror %d upperdvp %p %d/%d, uppervp %p ref=%d/lck=%d\n",
 		    uerror,
 		    upperdvp,
-		    upperdvp->v_usecount,
+		    vrefcnt(upperdvp),
 		    VOP_ISLOCKED(upperdvp, NULL),
 		    uppervp,
-		    (uppervp ? uppervp->v_usecount : -99),
+		    (uppervp ? vrefcnt(uppervp) : -99),
 		    (uppervp ? VOP_ISLOCKED(uppervp, NULL) : -99)
 		));
 
@@ -542,7 +542,7 @@ union_lookup(ap)
 	error = union_allocvp(ap->a_vpp, dvp->v_mount, dvp, upperdvp, cnp,
 			      uppervp, lowervp, 1);
 
-	UDEBUG(("Create %p = %p %p refs=%d\n", *ap->a_vpp, uppervp, lowervp, (*ap->a_vpp) ? ((*ap->a_vpp)->v_usecount) : -99));
+	UDEBUG(("Create %p = %p %p refs=%d\n", *ap->a_vpp, uppervp, lowervp, (*ap->a_vpp) ? vrefcnt(*ap->a_vpp) : -99));
 
 	uppervp = NULL;
 	upperdvp = NULL;
@@ -582,7 +582,7 @@ out:
 		cnp->cn_flags &= ~LOCKPARENT;
 
 	UDEBUG(("Out %d vpp %p/%d lower %p upper %p\n", error, *ap->a_vpp,
-		((*ap->a_vpp) ? (*ap->a_vpp)->v_usecount : -99),
+		((*ap->a_vpp) ? vrefcnt(*ap->a_vpp) : -99),
 		lowervp, uppervp));
 
 	/*
@@ -649,10 +649,10 @@ union_create(ap)
 		if (error == 0) {
 			mp = ap->a_dvp->v_mount;
 			VOP_UNLOCK(vp, 0, td);
-			UDEBUG(("ALLOCVP-1 FROM %p REFS %d\n", vp, vp->v_usecount));
+			UDEBUG(("ALLOCVP-1 FROM %p REFS %d\n", vp, vrefcnt(vp)));
 			error = union_allocvp(ap->a_vpp, mp, NULLVP, NULLVP,
 				cnp, vp, NULLVP, 1);
-			UDEBUG(("ALLOCVP-2B FROM %p REFS %d\n", *ap->a_vpp, vp->v_usecount));
+			UDEBUG(("ALLOCVP-2B FROM %p REFS %d\n", *ap->a_vpp, vrefcnt(vp)));
 		}
 		union_unlock_upper(dvp, td);
 	}
@@ -1491,10 +1491,10 @@ union_mkdir(ap)
 
 		if (error == 0) {
 			VOP_UNLOCK(vp, 0, td);
-			UDEBUG(("ALLOCVP-2 FROM %p REFS %d\n", vp, vp->v_usecount));
+			UDEBUG(("ALLOCVP-2 FROM %p REFS %d\n", vp, vrefcnt(vp)));
 			error = union_allocvp(ap->a_vpp, ap->a_dvp->v_mount,
 				ap->a_dvp, NULLVP, cnp, vp, NULLVP, 1);
-			UDEBUG(("ALLOCVP-2B FROM %p REFS %d\n", *ap->a_vpp, vp->v_usecount));
+			UDEBUG(("ALLOCVP-2B FROM %p REFS %d\n", *ap->a_vpp, vrefcnt(vp)));
 		}
 	}
 	return (error);
@@ -1723,7 +1723,7 @@ union_lock(ap)
 		 */
 		if (un->un_uppervp != NULLVP && 
 		    (flags & LK_TYPE_MASK) == LK_EXCLUSIVE) {
-			if ((un->un_flags & UN_ULOCK) == 0 && vp->v_usecount) {
+			if ((un->un_flags & UN_ULOCK) == 0 && vrefcnt(vp)) {
 				error = vn_lock(un->un_uppervp, flags, td);
 				if (error) {
 					struct vop_unlock_args uap = { 0 };
@@ -1760,7 +1760,7 @@ union_unlock(ap)
 	int error;
 
 #if 0
-	KASSERT((un->un_uppervp == NULL || un->un_uppervp->v_usecount > 0), ("uppervp usecount is 0"));
+	KASSERT((un->un_uppervp == NULL || vrefcnt(un->un_uppervp) > 0), ("uppervp usecount is 0"));
 #endif
 
 	error = vop_stdunlock(ap);