From patchwork Mon Sep 9 20:46:55 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "J. Bruce Fields" X-Patchwork-Id: 2863101 Return-Path: X-Original-To: patchwork-linux-nfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id D67CE9F495 for ; Mon, 9 Sep 2013 20:47:12 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id EAE642039D for ; Mon, 9 Sep 2013 20:47:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D955E20374 for ; Mon, 9 Sep 2013 20:47:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755381Ab3IIUrJ (ORCPT ); Mon, 9 Sep 2013 16:47:09 -0400 Received: from fieldses.org ([174.143.236.118]:44895 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755325Ab3IIUrI (ORCPT ); Mon, 9 Sep 2013 16:47:08 -0400 Received: from bfields by fieldses.org with local (Exim 4.76) (envelope-from ) id 1VJ8MJ-0002lU-7J; Mon, 09 Sep 2013 16:46:55 -0400 Date: Mon, 9 Sep 2013 16:46:55 -0400 To: Al Viro Cc: "J. Bruce Fields" , linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Christoph Hellwig Subject: Re: [PATCH 4/4] dcache: don't clear DCACHE_DISCONNECTED too early Message-ID: <20130909204655.GA10599@fieldses.org> References: <1378579561-26868-1-git-send-email-bfields@redhat.com> <1378579561-26868-5-git-send-email-bfields@redhat.com> <20130909004647.GK13318@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20130909004647.GK13318@ZenIV.linux.org.uk> User-Agent: Mutt/1.5.21 (2010-09-15) From: "J. Bruce Fields" Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Spam-Status: No, score=-7.8 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Mon, Sep 09, 2013 at 01:46:47AM +0100, Al Viro wrote: > On Sat, Sep 07, 2013 at 02:46:01PM -0400, J. Bruce Fields wrote: > > From: "J. Bruce Fields" > > > > DCACHE_DISCONNECTED should not be cleared until we're sure the dentry is > > connected all the way up to the root of the filesystem. It *shouldn't* > > be cleared as soon as the dentry is connected to a parent. That will > > cause bugs at least on exportable filesystems. > > Then you probably want this > if (!IS_ROOT(pd)) { > /* must have found a connected parent - great */ > spin_lock(&pd->d_lock); > pd->d_flags &= ~DCACHE_DISCONNECTED; > spin_unlock(&pd->d_lock); > noprogress = 0; > to go through all intermediates, clearing DCACHE_DISCONNECTED on all of > them; O(depth^2) can suck when we have a long chain of directories... I'm not sure what you mean--something like the following? Not having seen complaints about filehandle lookup performance I'm inclined to leave it alone, though. --b. --- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c index 5816e19..72ed705 100644 --- a/fs/exportfs/expfs.c +++ b/fs/exportfs/expfs.c @@ -90,6 +90,22 @@ find_disconnected_root(struct dentry *dentry) return dentry; } +static void clear_disconnected(struct dentry *dentry) +{ + dget(dentry); + while (dentry->d_flags & DCACHE_DISCONNECTED) { + struct dentry *parent = dget_parent(dentry); + + spin_lock(&dentry->d_lock); + dentry->d_flags &= ~DCACHE_DISCONNECTED; + spin_unlock(&dentry->d_lock); + + dput(dentry); + dentry = parent; + } + dput(dentry); +} + /* * Make sure target_dir is fully connected to the dentry tree. * @@ -114,15 +130,11 @@ reconnect_path(struct vfsmount *mnt, struct dentry *target_dir, char *nbuf) if (!IS_ROOT(pd)) { /* must have found a connected parent - great */ - spin_lock(&pd->d_lock); - pd->d_flags &= ~DCACHE_DISCONNECTED; - spin_unlock(&pd->d_lock); + clear_disconnected(target_dir); noprogress = 0; } else if (pd == mnt->mnt_sb->s_root) { printk(KERN_ERR "export: Eeek filesystem root is not connected, impossible\n"); - spin_lock(&pd->d_lock); - pd->d_flags &= ~DCACHE_DISCONNECTED; - spin_unlock(&pd->d_lock); + clear_disconnected(target_dir); noprogress = 0; } else { /*