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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 37178C55178 for ; Tue, 27 Oct 2020 17:13:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E026E20809 for ; Tue, 27 Oct 2020 17:13:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603818820; bh=F9YLbQ7d6XA/72vF+miC17GBj9k7XMq2X/J7Q/+oMjg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=X88MTv/vo6n7IRhL55vpx+snrGJK/EYTAEzxuuG5gFwXp4FFLoClnbSNE74su9igx bw4QDItDfUbHgtS4iKaDqQj9rR/ctZ14EO4fYPCPRFG3ukUv9GYLcXtEuGGSO3V9f6 pHPaM17s6KRFnaYOm0YU3AsuCKagSYen7V7djPMY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1817140AbgJ0RNj (ORCPT ); Tue, 27 Oct 2020 13:13:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:60750 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1784489AbgJ0O7L (ORCPT ); Tue, 27 Oct 2020 10:59:11 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 D3B2722264; Tue, 27 Oct 2020 14:59:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603810750; bh=F9YLbQ7d6XA/72vF+miC17GBj9k7XMq2X/J7Q/+oMjg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=r9cE1H8Sd+jDF7wb2hbPEnjpkuS+50imgy0YSrMN/2waOveN/XkZoAgpaj/4XsUco hzzOhUKlg8HPCyFvYpKhkJyjg1UtzZuN8eAGCu8dROkhJhOyFuJXL1+pLE/alKzVDN AQfndFR20SffAjOnVyXlHdflr7Unx3uzRJ0G6VOc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Matthew Wilcox (Oracle)" , "Darrick J. Wong" , Christoph Hellwig , Sasha Levin Subject: [PATCH 5.8 209/633] iomap: Clear page error before beginning a write Date: Tue, 27 Oct 2020 14:49:12 +0100 Message-Id: <20201027135532.484255852@linuxfoundation.org> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201027135522.655719020@linuxfoundation.org> References: <20201027135522.655719020@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Matthew Wilcox (Oracle) [ Upstream commit e6e7ca92623a43156100306861272e04d46385fc ] If we find a page in write_begin which is !Uptodate, we need to clear any error on the page before starting to read data into it. This matches how filemap_fault(), do_read_cache_page() and generic_file_buffered_read() handle PageError on !Uptodate pages. When calling iomap_set_range_uptodate() in __iomap_write_begin(), blocks were not being marked as uptodate. This was found with generic/127 and a specially modified kernel which would fail (some) readahead I/Os. The test read some bytes in a prior page which caused readahead to extend into page 0x34. There was a subsequent write to page 0x34, followed by a read to page 0x34. Because the blocks were still marked as !Uptodate, the read caused all blocks to be re-read, overwriting the write. With this change, and the next one, the bytes which were written are marked as being Uptodate, so even though the page is still marked as !Uptodate, the blocks containing the written data are not re-read from storage. Fixes: 9dc55f1389f9 ("iomap: add support for sub-pagesize buffered I/O without buffer heads") Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Signed-off-by: Sasha Levin --- fs/iomap/buffered-io.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index bcfc288dba3fb..c95454784df48 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -578,6 +578,7 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags, if (PageUptodate(page)) return 0; + ClearPageError(page); do { iomap_adjust_read_range(inode, iop, &block_start, -- 2.25.1