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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 D9B4FC6379D for ; Fri, 20 Nov 2020 22:39:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B14CA2242A for ; Fri, 20 Nov 2020 22:39:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728857AbgKTWjX (ORCPT ); Fri, 20 Nov 2020 17:39:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52024 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726640AbgKTWjW (ORCPT ); Fri, 20 Nov 2020 17:39:22 -0500 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 741E7C0613CF for ; Fri, 20 Nov 2020 14:39:22 -0800 (PST) Received: by fieldses.org (Postfix, from userid 2815) id EB0FF449B; Fri, 20 Nov 2020 17:39:21 -0500 (EST) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org EB0FF449B From: "J. Bruce Fields" To: Jeff Layton Cc: Daire Byrne , Trond Myklebust , linux-cachefs , linux-nfs , "J. Bruce Fields" Subject: [PATCH 1/8] nfsd: only call inode_query_iversion in the I_VERSION case Date: Fri, 20 Nov 2020 17:39:13 -0500 Message-Id: <1605911960-12516-1-git-send-email-bfields@redhat.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <20201120223831.GB7705@fieldses.org> References: <20201120223831.GB7705@fieldses.org> Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org 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 unnecssary cache invalidations. The way a filesystem indicates that it's OK to call inode_query_iverson() is by setting SB_I_VERSION. (This may look like a no-op--in the encode_change() case it's just rearranging some code--but note nfsd4_change_attribute() is also called from fill_pre_wcc() and fill_post_wcc().) (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/nfs4xdr.c | 6 +----- fs/nfsd/nfsfh.h | 14 ++++++++++---- 2 files changed, 11 insertions(+), 9 deletions(-) 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..3faf5974fa4e 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 = cpu_to_be32(stat->ctime.tv_sec); + chattr <<= 32; + chattr += cpu_to_be32(stat->ctime.tv_nsec); + } return chattr; } -- 2.28.0