From owner-svn-src-all@FreeBSD.ORG Tue Aug 31 01:16:46 2010 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 600E210656B0; Tue, 31 Aug 2010 01:16:46 +0000 (UTC) (envelope-from rmacklem@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c]) by mx1.freebsd.org (Postfix) with ESMTP id 34E328FC0A; Tue, 31 Aug 2010 01:16:46 +0000 (UTC) Received: from svn.freebsd.org (localhost [127.0.0.1]) by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id o7V1GkNp013984; Tue, 31 Aug 2010 01:16:46 GMT (envelope-from rmacklem@svn.freebsd.org) Received: (from rmacklem@localhost) by svn.freebsd.org (8.14.3/8.14.3/Submit) id o7V1GkM6013982; Tue, 31 Aug 2010 01:16:46 GMT (envelope-from rmacklem@svn.freebsd.org) Message-Id: <201008310116.o7V1GkM6013982@svn.freebsd.org> From: Rick Macklem Date: Tue, 31 Aug 2010 01:16:46 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Subject: svn commit: r212043 - head/sys/fs/nullfs X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 31 Aug 2010 01:16:46 -0000 Author: rmacklem Date: Tue Aug 31 01:16:45 2010 New Revision: 212043 URL: http://svn.freebsd.org/changeset/base/212043 Log: Add a null_remove() function to nullfs, so that the v_usecount of the lower level vnode is incremented to greater than 1 when the upper level vnode's v_usecount is greater than one. This is necessary for the NFS clients, so that they will do a silly rename of the file instead of actually removing it when the file is still in use. It is "racy", since the v_usecount is incremented in many places in the kernel with minimal synchronization, but an extraneous silly rename is preferred to not doing a silly rename when it is required. The only other file systems that currently check the value of v_usecount in their VOP_REMOVE() functions are nwfs and smbfs. These file systems choose to fail a remove when the v_usecount is greater than 1 and I believe will function more correctly with this patch, as well. Tested by: to.my.trociny at gmail.com Submitted by: to.my.trociny at gmail.com (earlier version) Reviewed by: kib MFC after: 2 weeks Modified: head/sys/fs/nullfs/null_vnops.c Modified: head/sys/fs/nullfs/null_vnops.c ============================================================================== --- head/sys/fs/nullfs/null_vnops.c Tue Aug 31 00:20:10 2010 (r212042) +++ head/sys/fs/nullfs/null_vnops.c Tue Aug 31 01:16:45 2010 (r212043) @@ -499,6 +499,32 @@ null_accessx(struct vop_accessx_args *ap } /* + * Increasing refcount of lower vnode is needed at least for the case + * when lower FS is NFS to do sillyrename if the file is in use. + * Unfortunately v_usecount is incremented in many places in + * the kernel and, as such, there may be races that result in + * the NFS client doing an extraneous silly rename, but that seems + * preferable to not doing a silly rename when it is needed. + */ +static int +null_remove(struct vop_remove_args *ap) +{ + int retval, vreleit; + struct vnode *lvp; + + if (vrefcnt(ap->a_vp) > 1) { + lvp = NULLVPTOLOWERVP(ap->a_vp); + VREF(lvp); + vreleit = 1; + } else + vreleit = 0; + retval = null_bypass(&ap->a_gen); + if (vreleit != 0) + vrele(lvp); + return (retval); +} + +/* * We handle this to eliminate null FS to lower FS * file moving. Don't know why we don't allow this, * possibly we should. @@ -809,6 +835,7 @@ struct vop_vector null_vnodeops = { .vop_open = null_open, .vop_print = null_print, .vop_reclaim = null_reclaim, + .vop_remove = null_remove, .vop_rename = null_rename, .vop_setattr = null_setattr, .vop_strategy = VOP_EOPNOTSUPP,