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Date:      Wed, 24 Nov 2010 12:30:41 +0000 (UTC)
From:      Konstantin Belousov <kib@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r215797 - head/sys/kern
Message-ID:  <201011241230.oAOCUflT070176@svn.freebsd.org>
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Author: kib
Date: Wed Nov 24 12:30:41 2010
New Revision: 215797
URL: http://svn.freebsd.org/changeset/base/215797

Log:
  Allow shared-locked vnode to be passed to vunref(9).
  When shared-locked vnode is supplied as an argument to vunref(9) and
  resulting usecount is 0, set VI_OWEINACT and do not try to upgrade vnode
  lock. The later could cause vnode unlock, allowing the vnode to be
  reclaimed meantime.
  
  Tested by:	pho
  MFC after:	1 week

Modified:
  head/sys/kern/vfs_subr.c

Modified: head/sys/kern/vfs_subr.c
==============================================================================
--- head/sys/kern/vfs_subr.c	Wed Nov 24 12:25:17 2010	(r215796)
+++ head/sys/kern/vfs_subr.c	Wed Nov 24 12:30:41 2010	(r215797)
@@ -2186,7 +2186,7 @@ vputx(struct vnode *vp, int func)
 
 	KASSERT(vp != NULL, ("vputx: null vp"));
 	if (func == VPUTX_VUNREF)
-		ASSERT_VOP_ELOCKED(vp, "vunref");
+		ASSERT_VOP_LOCKED(vp, "vunref");
 	else if (func == VPUTX_VPUT)
 		ASSERT_VOP_LOCKED(vp, "vput");
 	else
@@ -2224,12 +2224,22 @@ vputx(struct vnode *vp, int func)
 	 * as VI_DOINGINACT to avoid recursion.
 	 */
 	vp->v_iflag |= VI_OWEINACT;
-	if (func == VPUTX_VRELE) {
+	switch (func) {
+	case VPUTX_VRELE:
 		error = vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK);
 		VI_LOCK(vp);
-	} else if (func == VPUTX_VPUT && VOP_ISLOCKED(vp) != LK_EXCLUSIVE) {
-		error = VOP_LOCK(vp, LK_UPGRADE | LK_INTERLOCK | LK_NOWAIT);
-		VI_LOCK(vp);
+		break;
+	case VPUTX_VPUT:
+		if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE) {
+			error = VOP_LOCK(vp, LK_UPGRADE | LK_INTERLOCK |
+			    LK_NOWAIT);
+			VI_LOCK(vp);
+		}
+		break;
+	case VPUTX_VUNREF:
+		if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE)
+			error = EBUSY;
+		break;
 	}
 	if (vp->v_usecount > 0)
 		vp->v_iflag &= ~VI_OWEINACT;

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