From: Eric Sandeen Subject: Re: [PATCH] [RFC] remove ext3 inode from orphan list when link and unlink race Date: Fri, 12 Jan 2007 16:35:08 -0600 Message-ID: <45A80D1C.40005@redhat.com> References: <45A7F384.3050303@redhat.com> <45A7FA3C.8030209@redhat.com> <45A80213.5060401@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Alex Tomas , Linux Kernel Mailing List , ext4 development , Al Viro Return-path: Received: from mx1.redhat.com ([66.187.233.31]:52522 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161136AbXALWfU (ORCPT ); Fri, 12 Jan 2007 17:35:20 -0500 To: Eric Sandeen In-Reply-To: <45A80213.5060401@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Eric Sandeen wrote: > Alex Tomas wrote: > >> yes, but it shouldn't allow to re-link such inode back, IMHO. >> a filesystem may start some non-revertable activity in its >> unlink method. >> >> thanks, Alex >> > > I tend to agree, chatting w/ Al I think he does too. :) I'll test > a patch that kicks out ext3_link() with -ENOENT at the top, and resubmit > that if things go well. > Well this seems to fix things up for ext3 (and ext4 by extension): --- Return -ENOENT from ext[34]_link if we've raced with unlink and i_nlink is 0. Doing otherwise has the potential to corrupt the orphan inode list, because we'd wind up with an inode with a non-zero link count on the list, and it will never get properly cleaned up. Signed-off-by: Eric Sandeen Index: linux-2.6.19/fs/ext3/namei.c =================================================================== --- linux-2.6.19.orig/fs/ext3/namei.c +++ linux-2.6.19/fs/ext3/namei.c @@ -2191,6 +2191,8 @@ static int ext3_link (struct dentry * ol if (inode->i_nlink >= EXT3_LINK_MAX) return -EMLINK; + if (inode->i_nlink == 0) + return -ENOENT; retry: handle = ext3_journal_start(dir, EXT3_DATA_TRANS_BLOCKS(dir->i_sb) + Index: linux-2.6.19/fs/ext4/namei.c =================================================================== --- linux-2.6.19.orig/fs/ext4/namei.c +++ linux-2.6.19/fs/ext4/namei.c @@ -2189,6 +2189,8 @@ static int ext4_link (struct dentry * ol if (inode->i_nlink >= EXT4_LINK_MAX) return -EMLINK; + if (inode->i_nlink == 0) + return -ENOENT; retry: handle = ext4_journal_start(dir, EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +