From patchwork Fri Sep 30 11:18:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 12995317 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 A75E2C433F5 for ; Fri, 30 Sep 2022 11:27:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231843AbiI3L1Q (ORCPT ); Fri, 30 Sep 2022 07:27:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49832 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230438AbiI3L0a (ORCPT ); Fri, 30 Sep 2022 07:26:30 -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 80D7D10D3; Fri, 30 Sep 2022 04:19:04 -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 3C818B827BA; Fri, 30 Sep 2022 11:19:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D155C43470; Fri, 30 Sep 2022 11:19:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664536742; bh=uSYS665bHJOW0VgPrjPhB+eIdRUg3nkzUm52VZICAu0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=imbcD7d6rpnQgdKAoXWpTwniyU5ehyOAtwQa0fjjF1Zv+C/Up8oaasOc8/vQ/kmjj T26yTA/V8BY0QY16x7AeFuF4wpt8BDpqsyiMe3rMIE1wWyD3nyrljy0gTh/3lzj6b5 TD5biiRLBTzFAubEfD67uUdE7z/Zv9VQvaxicYgMzHJ4Ok81YaNYDaZQwEYQVcU2uw V3kKWaYG6BHZeX28d8LrQZJkRbcIQYxb4vmyGgU4ldNYll813gqZuqyuPUHZ9DIVw3 gLaGZV55F9N2OzXNFYsWJceKPjJ06Irqjkoq1i2VXH4Gi4ewHaCU8b4oypBh16FVSz 0EikFQXuIpMtw== From: Jeff Layton To: tytso@mit.edu, adilger.kernel@dilger.ca, djwong@kernel.org, david@fromorbit.com, trondmy@hammerspace.com, neilb@suse.de, viro@zeniv.linux.org.uk, zohar@linux.ibm.com, xiubli@redhat.com, chuck.lever@oracle.com, lczerner@redhat.com, jack@suse.cz, bfields@fieldses.org, brauner@kernel.org, fweimer@redhat.com Cc: linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org, linux-xfs@vger.kernel.org Subject: [PATCH v6 8/9] vfs: update times after copying data in __generic_file_write_iter Date: Fri, 30 Sep 2022 07:18:39 -0400 Message-Id: <20220930111840.10695-9-jlayton@kernel.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220930111840.10695-1-jlayton@kernel.org> References: <20220930111840.10695-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org The c/mtime and i_version currently get updated before the data is copied (or a DIO write is issued), which is problematic for NFS. READ+GETATTR can race with a write (even a local one) in such a way as to make the client associate the state of the file with the wrong change attribute. That association can persist indefinitely if the file sees no further changes. Move the setting of times to the bottom of the function in __generic_file_write_iter and only update it if something was successfully written. If the time update fails, log a warning once, but don't fail the write. All of the existing callers use update_time functions that don't fail, so we should never trip this. Signed-off-by: Jeff Layton --- mm/filemap.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 15800334147b..72c0ceb75176 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3812,10 +3812,6 @@ ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) if (err) goto out; - err = file_update_time(file); - if (err) - goto out; - if (iocb->ki_flags & IOCB_DIRECT) { loff_t pos, endbyte; @@ -3868,6 +3864,19 @@ ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) iocb->ki_pos += written; } out: + if (written > 0) { + err = file_update_time(file); + /* + * There isn't much we can do at this point if updating the + * times fails after a successful write. The times and i_version + * should still be updated in the inode, and it should still be + * marked dirty, so hopefully the next inode update will catch it. + * Log a warning once so we have a record that something untoward + * has occurred. + */ + WARN_ONCE(err, "Failed to update m/ctime after write: %ld\n", err); + } + current->backing_dev_info = NULL; return written ? written : err; }