From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753215Ab2GIU0U (ORCPT ); Mon, 9 Jul 2012 16:26:20 -0400 Received: from mail.digidescorp.com ([50.73.98.161]:44992 "EHLO mail.digidescorp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752976Ab2GIU0S (ORCPT ); Mon, 9 Jul 2012 16:26:18 -0400 DomainKey-Signature: a=rsa-sha1; s=MDaemon; d=digidescorp.com; c=simple; q=dns; h=message-id:from; b=JEuiD7Cub7f0PKA7e3kw0FHtzOiaySfEVxtmhG5DkCi/XnUjZBoTAr/MsWO/ rt8/UHhCxFnZzp8TEx8qtF99uWDRVEGuyAUAPahzYptgsI/SF1MSGzq/Z gwPmmDkODgEjSuPURXzi3YhX+COi3BcHKJYFLc+aEygLnakPzpY2o0=; X-Spam-Processed: mail.digidescorp.com, Mon, 09 Jul 2012 15:26:15 -0500 (not processed: message from trusted or authenticated source) X-Authenticated-Sender: steve@digidescorp.com X-Return-Path: prvs=1537d3712a=steve@digidescorp.com X-Envelope-From: steve@digidescorp.com X-MDaemon-Deliver-To: linux-kernel@vger.kernel.org Message-ID: <1341865572.31078.2.camel@iscandar.digidescorp.com> Subject: Re: [PATCH 2/2] fat (exportfs): reconnect file handles to evicted inodes/dentries From: "Steven J. Magnani" To: OGAWA Hirofumi Cc: linux-kernel@vger.kernel.org Date: Mon, 09 Jul 2012 15:26:12 -0500 In-Reply-To: <87bojooinr.fsf@devron.myhome.or.jp> References: <1341342576-15394-1-git-send-email-steve@digidescorp.com> <1341342576-15394-3-git-send-email-steve@digidescorp.com> <87pq8bokcp.fsf@devron.myhome.or.jp> <1341606824.2214.14.camel@iscandar.digidescorp.com> <871ukobntl.fsf@devron.myhome.or.jp> <1341623782.2021.9.camel@iscandar> <87wr2g9kh3.fsf@devron.myhome.or.jp> <1341679286.2435.12.camel@iscandar> <87zk7bo6aq.fsf@devron.myhome.or.jp> <1341835422.2215.6.camel@iscandar.digidescorp.com> <87sjd1nj7s.fsf@devron.myhome.or.jp> <1341845277.2215.10.camel@iscandar.digidescorp.com> <87obnooqz7.fsf@devron.myhome.or.jp> <1341851223.2215.22.camel@iscandar.digidescorp.com> <1341853758.2215.34.camel@iscandar.digidescorp.com> <87bojooinr.fsf@devron.myhome.or.jp> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.3 (3.4.3-1.fc17) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2012-07-10 at 04:10 +0900, OGAWA Hirofumi wrote: > "Steven J. Magnani" writes: > > >> > >> > Interesting idea. I think this, and reformulating the FAT NFS file > >> > >> > handle to include the parent's i_ino, will greatly simplify (and speed > >> > >> > up) the code. > >> > >> > >> > >> Does it work even if the inode was rename()'ed? > >> > > > >> > > AFAICT. I don't see why it wouldn't; on a rename, the inode's i_pos > >> > > changes but its i_ino stays the same, right? > >> > > >> > If the inode is not on cache anymore, is there the possibility that > >> > selects the wrong parent? IIRC, NFS Server can be rebooted at any time > >> > while the client using the same file handle. > >> > >> True, but it's looking like we can just use the default handle > >> constructed by export_encode_fh(), namely (i_ino, i_generation, > >> parent->i_ino, parent->i_generation). None of those components should > >> change in a server reboot. > > > > I think I misunderstood you when I wrote this. I assumed we were talking > > about a restart of nfsd, not the entire machine it was running on. If > > there is a danger of mismapping on a reboot isn't that present in the > > existing mainline code, i.e. fat_fh_to_dentry()? Ideally, the (i_ino, > > i_generation) signature would be different on a reboot, although with > > only 2-second granularity in i_generation I suppose that's less likely > > than we would prefer. Also I would think that many inodes simply > > wouldn't exist in the cache, in which case we would fail the operation > > with ESTALE. > > Ah, i_ino. I was talking about i_pos. Well, so, what happens if the > child was renamed to other parent on NFS server machine (not via nfs > client)? The file handle would be including the old i_ino, and the old > i_ino on file handle is still vaild as old parent. So, it returns the > wrong parent? Yes, but I believe exportfs_decode_fh() handles that case: /* * Now that we've got both a well-connected parent and a * dentry for the inode we're after, make sure that our * inode is actually connected to the parent. */ Really, the FAT NFS code will pretty much parallel that of ext2. ------------------------------------------------------------------------ Steven J. Magnani "I claim this network for MARS! www.digidescorp.com Earthling, return my space modulator!" #include