Skip site navigation (1)Skip section navigation (2) 
Date:      Wed, 28 Mar 2018 08:55:31 +0000 (UTC)
From:      Andriy Gapon <avg@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r331666 - in head/sys: cddl/contrib/opensolaris/uts/common/fs kern sys
Message-ID:  <201803280855.w2S8tVxE029241@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help 
Author: avg
Date: Wed Mar 28 08:55:31 2018
New Revision: 331666
URL: https://svnweb.freebsd.org/changeset/base/331666

Log:
  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.
  
  Reviewed by:	mjg
  MFC after:	2 weeks
  Sponsored by:	Panzura
  Differential Revision: https://reviews.freebsd.org/D14869

Modified:
  head/sys/cddl/contrib/opensolaris/uts/common/fs/vnode.c
  head/sys/kern/vfs_subr.c
  head/sys/sys/refcount.h

Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/vnode.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/vnode.c	Wed Mar 28 07:59:16 2018	(r331665)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/vnode.c	Wed Mar 28 08:55:31 2018	(r331666)
@@ -72,12 +72,6 @@ xva_getxoptattr(xvattr_t *xvap)
 	return (xoap);
 }
 
-static void
-vn_rele_inactive(vnode_t *vp)
-{
-	vrele(vp);
-}
-
 /*
  * Like vn_rele() except if we are going to call VOP_INACTIVE() then do it
  * asynchronously using a taskq. This can avoid deadlocks caused by re-entering
@@ -92,13 +86,10 @@ void
 vn_rele_async(vnode_t *vp, taskq_t *taskq)
 {
 	VERIFY(vp->v_count > 0);
-	VI_LOCK(vp);
-	if (vp->v_count == 1 && !(vp->v_iflag & VI_DOINGINACT)) {
-		VI_UNLOCK(vp);
-		VERIFY(taskq_dispatch((taskq_t *)taskq,
-		    (task_func_t *)vn_rele_inactive, vp, TQ_SLEEP) != 0);
+	if (refcount_release_if_not_last(&vp->v_usecount)) {
+		vdrop(vp);
 		return;
 	}
-	refcount_release(&vp->v_usecount);
-	vdropl(vp);
+	VERIFY(taskq_dispatch((taskq_t *)taskq,
+	    (task_func_t *)vrele, vp, TQ_SLEEP) != 0);
 }

Modified: head/sys/kern/vfs_subr.c
==============================================================================
--- head/sys/kern/vfs_subr.c	Wed Mar 28 07:59:16 2018	(r331665)
+++ head/sys/kern/vfs_subr.c	Wed Mar 28 08:55:31 2018	(r331666)
@@ -2455,37 +2455,6 @@ 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)
 {
@@ -2524,7 +2493,7 @@ 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 {
@@ -2616,7 +2585,7 @@ 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;
@@ -2720,7 +2689,7 @@ 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);
@@ -2836,7 +2805,7 @@ _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;
@@ -2907,7 +2876,7 @@ _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);
 	}
@@ -5438,12 +5407,12 @@ mnt_vnode_next_active_relock(struct vnode *mvp, struct
 	 * acquired with vhold(), but that might try to acquire the vnode
 	 * interlock, which would be a LOR with the mount vnode list lock.
 	 */
-	held = vfs_refcount_acquire_if_not_zero(&vp->v_holdcnt);
+	held = refcount_acquire_if_not_zero(&vp->v_holdcnt);
 	mtx_unlock(&mp->mnt_listmtx);
 	if (!held)
 		goto abort;
 	VI_LOCK(vp);
-	if (!vfs_refcount_release_if_not_last(&vp->v_holdcnt)) {
+	if (!refcount_release_if_not_last(&vp->v_holdcnt)) {
 		vdropl(vp);
 		goto abort;
 	}

Modified: head/sys/sys/refcount.h
==============================================================================
--- head/sys/sys/refcount.h	Wed Mar 28 07:59:16 2018	(r331665)
+++ head/sys/sys/refcount.h	Wed Mar 28 08:55:31 2018	(r331666)
@@ -76,4 +76,35 @@ refcount_release(volatile u_int *count)
 	return (1);
 }
 
+/*
+ * A temporary hack until refcount_* APIs are sorted out.
+ */
+static __inline int
+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
+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);
+	}
+}
+
 #endif	/* ! __SYS_REFCOUNT_H__ */

Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201803280855.w2S8tVxE029241>