From nobody Mon Apr 6 00:31:19 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B959C54EE9 for ; Tue, 13 Sep 2022 15:22:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236032AbiIMPWg (ORCPT ); Tue, 13 Sep 2022 11:22:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232199AbiIMPWE (ORCPT ); Tue, 13 Sep 2022 11:22:04 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E57AB7B7A0; Tue, 13 Sep 2022 07:36:35 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id DF807B80FA6; Tue, 13 Sep 2022 14:21:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A649C433D6; Tue, 13 Sep 2022 14:21:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663078911; bh=lUDWtF7U9ywnCODZtv5uQR2taTIVyThCDhb0jCdN7jw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a/1AuThe4f+hx/cVTGdhM/4WETS8H98zrHgseZZhQvvH16attJe4QQkhQF1k84HR7 ePWjdPE7fsGOdT8kW2cyZle4aUJpjh3z9P1mmkH1HZrUHx4HragRafY7lhELjK6VYh K1OLsDZZ0YWBZ8G/UJLJfQUqcS0WWIWSYLmao/4A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rick Macklem , Chuck Lever , Michael Kochera Subject: [PATCH 5.10 01/79] NFSD: Fix verifier returned in stable WRITEs Date: Tue, 13 Sep 2022 16:04:06 +0200 Message-Id: <20220913140350.359903417@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220913140350.291927556@linuxfoundation.org> References: <20220913140350.291927556@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Chuck Lever commit f11ad7aa653130b71e2e89bed207f387718216d5 upstream. RFC 8881 explains the purpose of the write verifier this way: > The final portion of the result is the field writeverf. This field > is the write verifier and is a cookie that the client can use to > determine whether a server has changed instance state (e.g., server > restart) between a call to WRITE and a subsequent call to either > WRITE or COMMIT. But then it says: > This cookie MUST be unchanged during a single instance of the > NFSv4.1 server and MUST be unique between instances of the NFSv4.1 > server. If the cookie changes, then the client MUST assume that > any data written with an UNSTABLE4 value for committed and an old > writeverf in the reply has been lost and will need to be > recovered. RFC 1813 has similar language for NFSv3. NFSv2 does not have a write verifier since it doesn't implement the COMMIT procedure. Since commit 19e0663ff9bc ("nfsd: Ensure sampling of the write verifier is atomic with the write"), the Linux NFS server has returned a boot-time-based verifier for UNSTABLE WRITEs, but a zero verifier for FILE_SYNC and DATA_SYNC WRITEs. FILE_SYNC and DATA_SYNC WRITEs are not followed up with a COMMIT, so there's no need for clients to compare verifiers for stable writes. However, by returning a different verifier for stable and unstable writes, the above commit puts the Linux NFS server a step farther out of compliance with the first MUST above. At least one NFS client (FreeBSD) noticed the difference, making this a potential regression. [Removed down_write to fix the conflict in the cherry-pick. The down_write functionality was no longer needed there. Upstream commit 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb titled nfsd: Replace use of rwsem with errseq_t removed those and replace it with new functionality that was more scalable. This commit is already backported onto 5.10 and so removing down_write ensures consistency with that change. Tested by compiling and booting successfully. - kochera] Reported-by: Rick Macklem Link: https://lore.kernel.org/linux-nfs/YQXPR0101MB096857EEACF04A6DF1FC6D9B= DD749@YQXPR0101MB0968.CANPRD01.PROD.OUTLOOK.COM/T/ Fixes: 19e0663ff9bc ("nfsd: Ensure sampling of the write verifier is atomic= with the write") Signed-off-by: Chuck Lever Signed-off-by: Michael Kochera Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/vfs.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1014,6 +1014,10 @@ nfsd_vfs_write(struct svc_rqst *rqstp, s iov_iter_kvec(&iter, WRITE, vec, vlen, *cnt); since =3D READ_ONCE(file->f_wb_err); if (flags & RWF_SYNC) { + if (verf) + nfsd_copy_boot_verifier(verf, + net_generic(SVC_NET(rqstp), + nfsd_net_id)); host_err =3D vfs_iter_write(file, &iter, &pos, flags); if (host_err < 0) nfsd_reset_boot_verifier(net_generic(SVC_NET(rqstp),