From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1008BC2B9F4 for ; Mon, 14 Jun 2021 20:04:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DA224600D3 for ; Mon, 14 Jun 2021 20:04:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232975AbhFNUGE (ORCPT ); Mon, 14 Jun 2021 16:06:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45342 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229734AbhFNUGD (ORCPT ); Mon, 14 Jun 2021 16:06:03 -0400 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B9287C061574 for ; Mon, 14 Jun 2021 13:04:00 -0700 (PDT) Received: by fieldses.org (Postfix, from userid 2815) id B4F456210; Mon, 14 Jun 2021 16:03:59 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org B4F456210 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1623701039; bh=Ve6AYJhgxdkLiplD0K+hpIkyn7gnACOdcA17CJmAxKs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QYzZyh7/bjgoBhwDA1vAAKeEQ4er6X8AZ0g4iEoZtRcd3vzvh67MhTmiF+jipX2L3 +Iz7QERuXL1+6ZM2ilHWHQp3dfH8oCt/1EPofxM1nim+y4Msdwoy80Azx/MvwzCrR7 3I9HdQNTSSuZYNFYOQwUIYiu0bwzVAGvoq6kS4UA= Date: Mon, 14 Jun 2021 16:03:59 -0400 From: "bfields@fieldses.org" To: Trond Myklebust Cc: "schumakeranna@gmail.com" , "linux-nfs@vger.kernel.org" , "bfields@redhat.com" , "daire@dneg.com" Subject: Re: [PATCH 3/3] nfs: don't allow reexport reclaims Message-ID: <20210614200359.GC16500@fieldses.org> References: <1623682098-13236-1-git-send-email-bfields@redhat.com> <1623682098-13236-4-git-send-email-bfields@redhat.com> <3189d061c1e862fe305e501226fcc9ebc1fe544d.camel@hammerspace.com> <20210614193409.GA16500@fieldses.org> <7b119b40fd29c424ce4e85fa4703b472bf0d379d.camel@hammerspace.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7b119b40fd29c424ce4e85fa4703b472bf0d379d.camel@hammerspace.com> User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Mon, Jun 14, 2021 at 07:53:52PM +0000, Trond Myklebust wrote: > On Mon, 2021-06-14 at 15:34 -0400, J. Bruce Fields wrote: > > On Mon, Jun 14, 2021 at 02:56:55PM +0000, Trond Myklebust wrote: > > > On Mon, 2021-06-14 at 10:48 -0400, J. Bruce Fields wrote: > > > > From: "J. Bruce Fields" > > > > > > > > In the reexport case, nfsd is currently passing along locks with > > > > the > > > > reclaim bit set.  The client sends a new lock request, which is > > > > granted > > > > if there's currently no conflict--even if it's possible a > > > > conflicting > > > > lock could have been briefly held in the interim. > > > > > > > > We don't currently have any way to safely grant reclaim, so for > > > > now > > > > let's just deny them all. > > > > > > > > I'm doing this by passing the reclaim bit to nfs and letting it > > > > fail > > > > the > > > > call, with the idea that eventually the client might be able to > > > > do > > > > something more forgiving here. > > > > > > > > Signed-off-by: J. Bruce Fields > > > > --- > > > >  fs/nfs/file.c       | 3 +++ > > > >  fs/nfsd/nfs4state.c | 3 +++ > > > >  fs/nfsd/nfsproc.c   | 1 + > > > >  include/linux/fs.h  | 1 + > > > >  4 files changed, 8 insertions(+) > > > > > > > > diff --git a/fs/nfs/file.c b/fs/nfs/file.c > > > > index 1fef107961bc..35a29b440e3e 100644 > > > > --- a/fs/nfs/file.c > > > > +++ b/fs/nfs/file.c > > > > @@ -806,6 +806,9 @@ int nfs_lock(struct file *filp, int cmd, > > > > struct > > > > file_lock *fl) > > > >   > > > >         nfs_inc_stats(inode, NFSIOS_VFSLOCK); > > > >   > > > > +       if (fl->fl_flags & FL_RECLAIM) > > > > +               return -NFSERR_NO_GRACE; > > > > > > NACK. nfs_lock() is required to return a POSIX error. I know that > > > right > > > now, nfsd is the only thing setting FL_RECLAIM, but we can't > > > guarantee > > > that will always be the case. > > > > Setting FL_RECLAIM tells the filesystem that you're prepared to > > handle > > NFSERR_NO_GRACE.  I'm not seeing the risk. > > You are using a function that is exposed to the VFS. On error, that > function is expected to return a value that is a Linux error between -1 > and -4095. Or 1, actually (FILE_LOCK_DEFERRED). > I suggest adding an error value ENOGRACE to include/linux/errno.h. I can live with that, but I'm still curious what exactly you're worried about. --b.