Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755449AbXLSUbk (ORCPT ); Wed, 19 Dec 2007 15:31:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752769AbXLSUb3 (ORCPT ); Wed, 19 Dec 2007 15:31:29 -0500 Received: from e36.co.us.ibm.com ([32.97.110.154]:45130 "EHLO e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751846AbXLSUb2 (ORCPT ); Wed, 19 Dec 2007 15:31:28 -0500 Date: Wed, 19 Dec 2007 14:30:57 -0600 From: "Serge E. Hallyn" To: Pekka J Enberg Cc: "Serge E. Hallyn" , serge@hallyn.com, alan@redhat.com, viro@zeniv.linux.org.uk, hch@infradead.org, peterz@infradead.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [RFC/PATCH 2/8] revoke: inode revoke lock V7 Message-ID: <20071219203057.GA7465@sergelap.austin.ibm.com> References: <20071217222850.GA10076@vino.hallyn.com> <20071219153056.GA7574@sergelap.austin.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2339 Lines: 62 Quoting Pekka J Enberg (penberg@cs.helsinki.fi): > Hi, > > On Wed, 19 Dec 2007, Serge E. Hallyn wrote: > > > I assume you mean S_REVOKE_LOCK and not ->i_mutex, right? > > > > No I did mean the i_mutex since you take the i_mutex when you set > > S_REVOKE_LOCK. So between that and the comment above do_lookup(), > > I assumed you were trying to lock out concurrent do_lookups() returning > > an inode whose revoke is starting at the same time. > > No, I only use ->i_mutex for synchronizing the write to ->i_flags. duh. > On Wed, 19 Dec 2007, Serge E. Hallyn wrote: > > > The caller is supposed to block open(2) with chmod(2)/chattr(2) so while > > > revoke is in progress, you can get references to the _revoked inode_, > > > which is fine (operations on it will fail with EBADFS). The > > > ->i_revoke_wait bits are there to make sure that while we revoke, you > > > can't get a _new reference_ to the inode until we're done. > > > > And a new reference means through iget(), so if revoke starts > > between the IS_REVOKE_LOCKED() check in do_lookup and its return, > > it's ok bc we'll get a reference later on? > > Yes, as soon as we unhash the dentries and the inode, do_lookup() will try > to find a new inode with iget() but we need to wait before writeback on > the revoked inode is finished. Ok, that makes sense. I'll let that sit for a short while and look again :) thanks, -serge > On Wed, 19 Dec 2007, Serge E. Hallyn wrote: > > I'm a little confused but i'll keep looking. > > I don't blame you. The patch is missing the following "minor detail" which > is needed to avoid fs corruption... > > Pekka > > Index: 2.6/fs/revoke.c > =================================================================== > --- 2.6.orig/fs/revoke.c 2007-12-16 19:57:40.000000000 +0200 > +++ 2.6/fs/revoke.c 2007-12-19 18:03:13.000000000 +0200 > @@ -426,6 +426,8 @@ int err = 0; > make_revoked_inode(inode); > remove_inode_hash(inode); > revoke_aliases(inode); > + > + err = write_inode_now(inode, 1); > failed: > revoke_unlock(inode); > wake_up(&inode->i_revoke_wait); -- 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/