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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 0C1BDC64E7B for ; Tue, 1 Dec 2020 16:44:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A7A3A206B7 for ; Tue, 1 Dec 2020 16:44:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="F/KEM9PO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726147AbgLAQoO (ORCPT ); Tue, 1 Dec 2020 11:44:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:58472 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725885AbgLAQoN (ORCPT ); Tue, 1 Dec 2020 11:44:13 -0500 Received: from tleilax.poochiereds.net (68-20-15-154.lightspeed.rlghnc.sbcglobal.net [68.20.15.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 61F7820758; Tue, 1 Dec 2020 16:43:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606841012; bh=Km+WM9tA4MWrdRukSNY/Rw0La/ntq5vA+VkrebH6SBM=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=F/KEM9POqeRZ9rdRPFnpfkjrZCdRY9z0LNefPBLXBT/D2DUMYK3uIQwOsRbkWwjKB Txy0SPYIh5ZktFPtE1gr5xurIDV3SP1xbuWKSLdwEVKVw7X3M7E5YJytwXWmo1/YBi BuD8g5P9wzeMhst4/vW+16mIg41Vksgen3lTe26c= Message-ID: <01bad6aa8aa05bb9bafd010575866125f89c5f08.camel@kernel.org> Subject: Re: [PATCH 1/5] nfsd: only call inode_query_iversion in the I_VERSION case From: Jeff Layton To: "J. Bruce Fields" , Chuck Lever Cc: linux-nfs@vger.kernel.org, "J. Bruce Fields" Date: Tue, 01 Dec 2020 11:43:31 -0500 In-Reply-To: <1606776378-22381-1-git-send-email-bfields@fieldses.org> References: <1606776378-22381-1-git-send-email-bfields@fieldses.org> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.1 (3.38.1-1.fc33) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Mon, 2020-11-30 at 17:46 -0500, J. Bruce Fields wrote: > From: "J. Bruce Fields" > > inode_query_iversion() can modify i_version. Depending on the exported > filesystem, that may not be safe. For example, if you're re-exporting > NFS, NFS stores the server's change attribute in i_version and does not > expect it to be modified locally. This has been observed causing > unnecessary cache invalidations. > > The way a filesystem indicates that it's OK to call > inode_query_iverson() is by setting SB_I_VERSION. > > So, move the I_VERSION check out of encode_change(), where it's used > only in FATTR responses, to nfsd4_changeattr(), which is also called for > pre- and post- operation attributes. > > (Note we could also pull the NFSEXP_V4ROOT case into > nfsd4_change_attribute as well. That would actually be a no-op, since > pre/post attrs are only used for metadata-modifying operations, and > V4ROOT exports are read-only. But we might make the change in the > future just for simplicity.) > > Reported-by: Daire Byrne > Signed-off-by: J. Bruce Fields > --- >  fs/nfsd/nfs3xdr.c | 5 ++--- >  fs/nfsd/nfs4xdr.c | 6 +----- >  fs/nfsd/nfsfh.h | 14 ++++++++++---- >  3 files changed, 13 insertions(+), 12 deletions(-) > > diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c > index 2277f83da250..dfbf390ff40c 100644 > --- a/fs/nfsd/nfs3xdr.c > +++ b/fs/nfsd/nfs3xdr.c > @@ -291,14 +291,13 @@ void fill_post_wcc(struct svc_fh *fhp) >   printk("nfsd: inode locked twice during operation.\n"); >   > > > >   err = fh_getattr(fhp, &fhp->fh_post_attr); > - fhp->fh_post_change = nfsd4_change_attribute(&fhp->fh_post_attr, > - d_inode(fhp->fh_dentry)); >   if (err) { >   fhp->fh_post_saved = false; > - /* Grab the ctime anyway - set_change_info might use it */ >   fhp->fh_post_attr.ctime = d_inode(fhp->fh_dentry)->i_ctime; >   } else >   fhp->fh_post_saved = true; > + fhp->fh_post_change = nfsd4_change_attribute(&fhp->fh_post_attr, > + d_inode(fhp->fh_dentry)); >  } >   > > > >  /* > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c > index 833a2c64dfe8..56fd5f6d5c44 100644 > --- a/fs/nfsd/nfs4xdr.c > +++ b/fs/nfsd/nfs4xdr.c > @@ -2298,12 +2298,8 @@ static __be32 *encode_change(__be32 *p, struct kstat *stat, struct inode *inode, >   if (exp->ex_flags & NFSEXP_V4ROOT) { >   *p++ = cpu_to_be32(convert_to_wallclock(exp->cd->flush_time)); >   *p++ = 0; > - } else if (IS_I_VERSION(inode)) { > + } else >   p = xdr_encode_hyper(p, nfsd4_change_attribute(stat, inode)); > - } else { > - *p++ = cpu_to_be32(stat->ctime.tv_sec); > - *p++ = cpu_to_be32(stat->ctime.tv_nsec); > - } >   return p; >  } >   > > > > diff --git a/fs/nfsd/nfsfh.h b/fs/nfsd/nfsfh.h > index 56cfbc361561..39d764b129fa 100644 > --- a/fs/nfsd/nfsfh.h > +++ b/fs/nfsd/nfsfh.h > @@ -261,10 +261,16 @@ static inline u64 nfsd4_change_attribute(struct kstat *stat, >  { >   u64 chattr; >   > > > > - chattr = stat->ctime.tv_sec; > - chattr <<= 30; > - chattr += stat->ctime.tv_nsec; > - chattr += inode_query_iversion(inode); > + if (IS_I_VERSION(inode)) { > + chattr = stat->ctime.tv_sec; > + chattr <<= 30; > + chattr += stat->ctime.tv_nsec; > + chattr += inode_query_iversion(inode); > + } else { > + chattr = stat->ctime.tv_sec; > + chattr <<= 32; Might be nice to annotate the shifts above and maybe make them named constants. I'm not sure where those values come from, tbh. > + chattr += stat->ctime.tv_nsec; > + } >   return chattr; >  } >   > > > Other than some very minor nits, the set itself looks great. Are you planning to follow up with the series to add the fetch_iversion op, or have you decided not to do that for now? Reviewed-by: Jeff Layton