Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757395AbZLJUVB (ORCPT ); Thu, 10 Dec 2009 15:21:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757023AbZLJUU7 (ORCPT ); Thu, 10 Dec 2009 15:20:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35198 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756672AbZLJUU6 (ORCPT ); Thu, 10 Dec 2009 15:20:58 -0500 Date: Thu, 10 Dec 2009 15:20:20 -0500 From: Valerie Aurora To: Erez Zadok Cc: Jan Blunck , Alexander Viro , Christoph Hellwig , Andy Whitcroft , Scott James Remnant , Sandu Popa Marius , Jan Rekorajski , "J. R. Okajima" , Arnd Bergmann , Vladimir Dronnikov , Felix Fietkau , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 01/41] VFS: BUG() if somebody tries to rehash an already hashed dentry Message-ID: <20091210202020.GA10388@shell> References: <1256152779-10054-2-git-send-email-vaurora@redhat.com> <200911300143.nAU1hwav006906@agora.fsl.cs.sunysb.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200911300143.nAU1hwav006906@agora.fsl.cs.sunysb.edu> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1957 Lines: 53 On Sun, Nov 29, 2009 at 08:43:58PM -0500, Erez Zadok wrote: > In message <1256152779-10054-2-git-send-email-vaurora@redhat.com>, Valerie Aurora writes: > > From: Jan Blunck > > > > Break early when somebody tries to rehash an already hashed dentry. > > Otherwise this leads to interesting corruptions in the dcache hash table > > later on. > > > > Signed-off-by: Jan Blunck > > Signed-off-by: Valerie Aurora > > --- > > fs/dcache.c | 1 + > > 1 files changed, 1 insertions(+), 0 deletions(-) > > > > diff --git a/fs/dcache.c b/fs/dcache.c > > index 9e5cd3c..38bf982 100644 > > --- a/fs/dcache.c > > +++ b/fs/dcache.c > > @@ -1550,6 +1550,7 @@ void d_rehash(struct dentry * entry) > > { > > spin_lock(&dcache_lock); > > spin_lock(&entry->d_lock); > > + BUG_ON(!d_unhashed(entry)); > > _d_rehash(entry); > > spin_unlock(&entry->d_lock); > > spin_unlock(&dcache_lock); > > This patch seems unrelated to union mounts. If so, can you get it pushed > upstream sooner? Or is this a debugging patch useful only when developing > union mounts? > > You also said that it can lead to "ineresting corruptions". What kind of > corruptions exactly? Also, would it make more sense to allow _d_rehash() to > hash in an unhashed dentry for the first time? Hi Erez, Thanks for your great review! I am working my way through your comments one by one. This is a trivial patch which happened to be useful during our development and seems like it might be useful for other VFS-related development. I will submit it as part of our VFS patch set and drop it if the maintainers don't want it. I don't have an opinion on _d_rehash(), I'm afraid. -VAL -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/