From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Kent Subject: Re: [PATCH 1/2] vfs: make real_lookup do dentry revalidation with i_mutex held Date: Wed, 24 Jun 2009 10:28:45 +0800 Message-ID: <4A418F5D.3020906@themaw.net> References: <1237493790-5665-1-git-send-email-sage@newdream.net> <49C85E3E.7030505@themaw.net> <49C85F0A.9030409@themaw.net> <49C9CA5A.5080809@themaw.net> <49CA579B.5080307@themaw.net> <49CAE3DB.3030909@themaw.net> <1238063926.23853.15.camel@zeus.themaw.net> <49D56DD5.80707@themaw.net> <4A4023CF.7040203@themaw.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-fsdevel , Christoph Hellwig , akpm@linux-foundation.org, Al Viro , Yehuda Sadeh , "H. Peter Anvin" To: Sage Weil Return-path: Received: from outbound.icp-qv1-irony-out2.iinet.net.au ([203.59.1.107]:10706 "EHLO outbound.icp-qv1-irony-out2.iinet.net.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751321AbZFXC2q (ORCPT ); Tue, 23 Jun 2009 22:28:46 -0400 In-Reply-To: <4A4023CF.7040203@themaw.net> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Ian Kent wrote: > Sage Weil wrote: >> Hi Ian, >> >> Have you had a chance to look at getting autofs4 lookup/revalidate >> adjusted so that this real_lookup() fix[1] can go in? >> >> Please let me know if there is anything I can do to help here. If you're >> still occupied, I'm happy to spin something up and send it your way... >> just let me know. > > Sorry, I haven't had time to do more on this. > There is also the issue of what to do about removing the autofs module > and renaming autofs4 to autofs, as this will break the autofs module. > > I did start contacting people I think would want to know about this but > haven't gone further than an initial mail. > > The other thing is that this patch was originally written quite a while > ago and, although it appears to work ok, I'm not sure it's quite what we > need. I'm continuing with this now, but there's a deadlock in there somewhere! > > Sorry for delaying you. > >> thanks- >> sage >> >> >> [1] http://marc.info/?l=linux-fsdevel&m=123749395609697&w=2 >> >> >> On Fri, 3 Apr 2009, Ian Kent wrote: >> >>> Sage Weil wrote: >>>>> Latest here works OK. >>>>> >>>>> I haven't finished checking yet but it looks like the patch below works >>>>> OK. I started with a 2.6.29 build with your two patches but it was a >>>>> little broken so I fell back to a Fedora 2.6.27 based kernel without the >>>>> two revalidate pacthes to debug it. So I still need to test the result >>>>> against 2.6.29 again. I also don't have any real way to test for the three >>>>> process race we discussed where the revalidate isn't followed by a >>>>> ->lookup() but with both of your patches applied that shouldn't be a >>>>> problem (as we discussed). >>>>> >>>>> I've not run checkpatch.pl against the patch either at this stage. >>>> That's good news... >>> I'm still working on this too. >>> I have some pressing work so it may be a while before I'm totally happy >>> with the patch. Didn't you say you were expecting a 2.6.31 time frame >>> for this? >>> >>>> >>>>> There is a further issue and that is regarding the autofs module. >>>>> >>>>> I can't see updating autofs for this being practical (although I haven't >>>>> actually looked yet). I suspect quite a bit of work would be needed. The >>>>> fact is that autofs isn't used much any more and it really should be >>>>> replaced with the autofs4 module at some point. But that's a fairly tricky >>>>> exercise and will likely cause some user space breakage. It will require >>>>> an updated module-init-tools to add "alais autofs4 autofs" for modprobe >>>>> backward compatibility and will break for any explicit checks for the >>>>> presence of the "autofs4" module. >>>> Hmm. Well, I assume autofs needs to work properly before this gets >>>> changed, though, right? Should I see what I can do with it? I took a >>>> quick look, and I don't think it will take too much to make it behave. >>>> It looks like the main thing is to make the lookup call to try_fill_dentry >>>> return any existing dentry in place of the one the vfs provides. >>> Yes, or be replaced by what is currently the autofs4 module. The autofs >>> v2 communication protocol surely can't be being used any more and the >>> autofs4 module supports versions 3, 4 and 5. In fact I received a mail >>> from HPA recently suggesting he supports doing this. >>> >>> I had a quick look as well. I think you'll find it isn't quite as simple >>> as that. I'll have a closer look as soon as I get a chance. >>> >>> >>> Ian >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >>> > >