MFC r331666: ZFS vn_rele_async: catch up with the use of refcount(9) for the vnode use count

It's not sufficient nor required to use the vnode interlock when
checking if we are going to drop the last use count as the code in
vputx() uses refcount (atomic) operations for both checking and
decrementing the use code.  Apply the same method to vn_rele_async().
While here, remove vn_rele_inactive(), a wrapper around vrele() that
didn't add any value.

Also, the change required making vfs_refcount_release_if_not_last()
public.  I've made vfs_refcount_acquire_if_not_zero() public as well.
They are in sys/refcount.h now.  While making the move I've dropped the
vfs_ prefix.

Sponsored by:	Panzura

1 files changed, 5 insertions, 36 deletions

diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 8ef878e..b4f9374 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -2389,37 +2389,6 @@ reassignbuf(struct buf *bp)
 	BO_UNLOCK(bo);
 }
 
-/*
- * A temporary hack until refcount_* APIs are sorted out.
- */
-static __inline int
-vfs_refcount_acquire_if_not_zero(volatile u_int *count)
-{
-	u_int old;
-
-	old = *count;
-	for (;;) {
-		if (old == 0)
-			return (0);
-		if (atomic_fcmpset_int(count, &old, old + 1))
-			return (1);
-	}
-}
-
-static __inline int
-vfs_refcount_release_if_not_last(volatile u_int *count)
-{
-	u_int old;
-
-	old = *count;
-	for (;;) {
-		if (old == 1)
-			return (0);
-		if (atomic_fcmpset_int(count, &old, old - 1))
-			return (1);
-	}
-}
-
 static void
 v_init_counters(struct vnode *vp)
 {
@@ -2459,7 +2428,7 @@ v_incr_usecount(struct vnode *vp)
 	CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 
 	if (vp->v_type != VCHR &&
-	    vfs_refcount_acquire_if_not_zero(&vp->v_usecount)) {
+	    refcount_acquire_if_not_zero(&vp->v_usecount)) {
 		VNASSERT((vp->v_iflag & VI_OWEINACT) == 0, vp,
 		    ("vnode with usecount and VI_OWEINACT set"));
 	} else {
@@ -2551,7 +2520,7 @@ vget(struct vnode *vp, int flags, struct thread *td)
 	 * Upgrade our holdcnt to a usecount.
 	 */
 	if (vp->v_type == VCHR ||
-	    !vfs_refcount_acquire_if_not_zero(&vp->v_usecount)) {
+	    !refcount_acquire_if_not_zero(&vp->v_usecount)) {
 		VI_LOCK(vp);
 		if ((vp->v_iflag & VI_OWEINACT) == 0) {
 			oweinact = 0;
@@ -2654,7 +2623,7 @@ vputx(struct vnode *vp, int func)
 	CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 
 	if (vp->v_type != VCHR &&
-	    vfs_refcount_release_if_not_last(&vp->v_usecount)) {
+	    refcount_release_if_not_last(&vp->v_usecount)) {
 		if (func == VPUTX_VPUT)
 			VOP_UNLOCK(vp, 0);
 		vdrop(vp);
@@ -2770,7 +2739,7 @@ _vhold(struct vnode *vp, bool locked)
 		ASSERT_VI_UNLOCKED(vp, __func__);
 	CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 	if (!locked) {
-		if (vfs_refcount_acquire_if_not_zero(&vp->v_holdcnt)) {
+		if (refcount_acquire_if_not_zero(&vp->v_holdcnt)) {
 			VNASSERT((vp->v_iflag & VI_FREE) == 0, vp,
 			    ("_vhold: vnode with holdcnt is free"));
 			return;
@@ -2831,7 +2800,7 @@ _vdrop(struct vnode *vp, bool locked)
 	if ((int)vp->v_holdcnt <= 0)
 		panic("vdrop: holdcnt %d", vp->v_holdcnt);
 	if (!locked) {
-		if (vfs_refcount_release_if_not_last(&vp->v_holdcnt))
+		if (refcount_release_if_not_last(&vp->v_holdcnt))
 			return;
 		VI_LOCK(vp);
 	}