- Increment the holdcnt once for each usecount reference. This allows us

   to use only the holdcnt to determine whether a vnode may be recycled,
   simplifying the V* macros as well as vtryrecycle(), etc.

Sponsored by:	Isilon Systems, Inc.

2 files changed, 9 insertions, 12 deletions

diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 97a52e4..8d0d6c2 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -745,7 +745,7 @@ vtryrecycle(struct vnode *vp)
 	 * If someone ref'd the vnode while we were cleaning, we have to
 	 * free it once the last ref is dropped.
 	 */
-	if (vp->v_usecount || vp->v_holdcnt)
+	if (vp->v_holdcnt)
 		error = EBUSY;
 	VI_UNLOCK(vp);
 done:
@@ -1781,6 +1781,7 @@ v_incr_usecount(struct vnode *vp, int delta)
 {
 
 	vp->v_usecount += delta;
+	vp->v_holdcnt += delta;
 	if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 		dev_lock();
 		vp->v_rdev->si_usecount += delta;
@@ -2018,7 +2019,7 @@ vdropl(struct vnode *vp)
 {
 
 	if (vp->v_holdcnt <= 0)
-		panic("vdrop: holdcnt");
+		panic("vdrop: holdcnt %d", vp->v_holdcnt);
 	vp->v_holdcnt--;
 	if (VSHOULDFREE(vp))
 		vfree(vp);
@@ -2326,7 +2327,7 @@ vgonel(struct vnode *vp, struct thread *td)
 	 * incremented first, vgone would (incorrectly) try to
 	 * close the previous instance of the underlying object.
 	 */
-	if (vp->v_usecount == 0 && vp->v_holdcnt == 0 && !doomed) {
+	if (vp->v_holdcnt == 0 && !doomed) {
 		mtx_lock(&vnode_free_list_mtx);
 		if (vp->v_iflag & VI_FREE) {
 			TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
index 19bf36c..b99a766 100644
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -159,7 +159,7 @@ struct vnode {
 	const char *filename;			/* Source file doing locking */
 	int line;				/* Line number doing locking */
 #endif
-	int	v_holdcnt;			/* i page & buffer references */
+	int	v_holdcnt;			/* i prevents recycling. */
 	int	v_usecount;			/* i ref count of users */
 	struct thread *v_vxthread;		/* i thread running vgone. */
 	u_long	v_iflag;			/* i vnode flags (see below) */
@@ -387,20 +387,16 @@ extern void	(*lease_updatetime)(int deltat);
 
 /* Requires interlock. */
 #define	VCANRECYCLE(vp)							\
-	(((vp)->v_iflag & VI_FREE) &&					\
-	 !(vp)->v_holdcnt && !(vp)->v_usecount)
+	(((vp)->v_iflag & VI_FREE) && !(vp)->v_holdcnt)
 
 /* Requires interlock. */
 #define	VSHOULDFREE(vp)							\
-	(!((vp)->v_iflag & VI_FREE) &&					\
-	 !(vp)->v_holdcnt && !(vp)->v_usecount &&			\
-	 (!(vp)->v_object ||						\
-	  !(vp)->v_object->resident_page_count))
+	(!((vp)->v_iflag & VI_FREE) && !(vp)->v_holdcnt &&		\
+	 (!(vp)->v_object || !(vp)->v_object->resident_page_count))
 
 /* Requires interlock. */
 #define	VSHOULDBUSY(vp)							\
-	(((vp)->v_iflag & VI_FREE) &&					\
-	 ((vp)->v_holdcnt || (vp)->v_usecount))
+	(((vp)->v_iflag & VI_FREE) && (vp)->v_holdcnt)
 
 #define	VI_LOCK(vp)	mtx_lock(&(vp)->v_interlock)
 #define	VI_TRYLOCK(vp)	mtx_trylock(&(vp)->v_interlock)