From patchwork Wed Mar 8 16:29:33 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 9611679 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id AD738602B4 for ; Wed, 8 Mar 2017 16:55:05 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9BAED28494 for ; Wed, 8 Mar 2017 16:55:05 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8FCC2285EA; Wed, 8 Mar 2017 16:55:05 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4506C28494 for ; Wed, 8 Mar 2017 16:55:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753068AbdCHQzC (ORCPT ); Wed, 8 Mar 2017 11:55:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53332 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750888AbdCHQzB (ORCPT ); Wed, 8 Mar 2017 11:55:01 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 750606198B; Wed, 8 Mar 2017 16:30:20 +0000 (UTC) Received: from tleilax.poochiereds.net (ovpn-120-184.rdu2.redhat.com [10.10.120.184] (may be forged)) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v28GTe9o001630; Wed, 8 Mar 2017 11:30:19 -0500 From: Jeff Layton To: viro@zeniv.linux.org.uk, akpm@linux-foundation.org Cc: konishi.ryusuke@lab.ntt.co.jp, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-nilfs@vger.kernel.org, ross.zwisler@linux.intel.com, jack@suse.cz, neilb@suse.com, openosd@gmail.com, adilger@dilger.ca, James.Bottomley@HansenPartnership.com Subject: [PATCH v2 8/9] mm: don't TestClearPageError in __filemap_fdatawait_range Date: Wed, 8 Mar 2017 11:29:33 -0500 Message-Id: <20170308162934.21989-9-jlayton@redhat.com> In-Reply-To: <20170308162934.21989-1-jlayton@redhat.com> References: <20170308162934.21989-1-jlayton@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Wed, 08 Mar 2017 16:30:21 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The -EIO returned here can end up overriding whatever error is marked in the address space. This means that an -ENOSPC error (AS_ENOSPC) can end up being turned into -EIO if a page gets PG_error set on it during error handling. Read errors are also sometimes tracked on a per-page level using PG_error. Suppose we have a read error on a page, and then that page is subsequently dirtied by overwriting the whole page. Writeback doesn't clear PG_error, so we can then end up successfully writing back that page and still return -EIO on fsync. Worse yet, PG_error is cleared during a sync() syscall, but the -EIO return from this code is silently discarded. Any subsystem that is relying on PG_error to report errors during fsync or close is already broken due to this. All you need is a stray sync() call on the box at the wrong time and you've lost the error. Since the handling of the PG_error flag is somewhat inconsistent across subsystems, let's just rely on marking the address space when there are writeback errors. Change the TestClearPageError call to ClearPageError, and make __filemap_fdatawait_range a void return function. Signed-off-by: Jeff Layton --- mm/filemap.c | 20 +++++--------------- 1 file changed, 5 insertions(+), 15 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index fc123b9833e1..150559e94f8a 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -376,17 +376,16 @@ int filemap_flush(struct address_space *mapping) } EXPORT_SYMBOL(filemap_flush); -static int __filemap_fdatawait_range(struct address_space *mapping, +static void __filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, loff_t end_byte) { pgoff_t index = start_byte >> PAGE_SHIFT; pgoff_t end = end_byte >> PAGE_SHIFT; struct pagevec pvec; int nr_pages; - int ret = 0; if (end_byte < start_byte) - goto out; + return; pagevec_init(&pvec, 0); while ((index <= end) && @@ -403,14 +402,11 @@ static int __filemap_fdatawait_range(struct address_space *mapping, continue; wait_on_page_writeback(page); - if (TestClearPageError(page)) - ret = -EIO; + ClearPageError(page); } pagevec_release(&pvec); cond_resched(); } -out: - return ret; } /** @@ -430,14 +426,8 @@ static int __filemap_fdatawait_range(struct address_space *mapping, int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, loff_t end_byte) { - int ret, ret2; - - ret = __filemap_fdatawait_range(mapping, start_byte, end_byte); - ret2 = filemap_check_errors(mapping); - if (!ret) - ret = ret2; - - return ret; + __filemap_fdatawait_range(mapping, start_byte, end_byte); + return filemap_check_errors(mapping); } EXPORT_SYMBOL(filemap_fdatawait_range);