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=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 9F9B3C48BD1 for ; Sat, 12 Jun 2021 00:11:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 84502613CA for ; Sat, 12 Jun 2021 00:11:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230305AbhFLANm (ORCPT ); Fri, 11 Jun 2021 20:13:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:39490 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230211AbhFLANm (ORCPT ); Fri, 11 Jun 2021 20:13:42 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C2C0C611C9; Sat, 12 Jun 2021 00:11:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1623456703; bh=Tu5a8C+SqP0zJQs3rIaJjHW135ITBA0pKl8xjZ4BBQI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LCHuMNqon0HM1HNFS6XMXUM4LKNlPv+bAtPvkLzHm+stdMFIFUhJbV2hD7iJjvPrN rxqqgd5MAEz7ntHHBHLZbsWnZ74SCPGXbz26c8NKQ0qe6bSOMfvuxC4zDY26BDpYsH kQ1FUR/couJD3vcCfD6XipHOTNYqEr6yU/w8+LkktY0HvoDxn+qr5eGSWsXNuCYPhh JcbRh+86spoYV0Op57kSNPdmhbWs/MZdCaULa0cZVrfnr7PLuhNDqRVPBP7hBe/SUc qGMCQnTr80VSjYuuAnD3CbqnGfWp+DsZwQeSXn6Yv03vya/yVx8jG0WAgZ5ywWmon7 yCv0ukS63LZag== From: Jeff Layton To: ceph-devel@vger.kernel.org Cc: linux-cachefs@redhat.com, pfmeec@rit.edu, willy@infradead.org, dhowells@redhat.com, idryomov@gmail.com, stable@vger.kernel.org, Andrew W Elble Subject: [PATCH v2] ceph: fix write_begin optimization when write is beyond EOF Date: Fri, 11 Jun 2021 20:11:41 -0400 Message-Id: <20210612001141.167797-1-jlayton@kernel.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210611195904.160416-1-jlayton@kernel.org> References: <20210611195904.160416-1-jlayton@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org It's not sufficient to skip reading when the pos is beyond the EOF. There may be data at the head of the page that we need to fill in before the write. Only elide the read if the pos is beyond the last page in the file. Cc: # v5.10+ Fixes: 1cc1699070bd ("ceph: fold ceph_update_writeable_page into ceph_write_begin") Reported-by: Andrew W Elble Signed-off-by: Jeff Layton --- fs/ceph/addr.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) This version fixes the one-off bug that Willy pointed out in v1. Note that v5.13 has been converted to use the new netfs read helper lib,xi so this fix is for v5.10.z through v5.12.z. diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c index 26e66436f005..813ab4256dbb 100644 --- a/fs/ceph/addr.c +++ b/fs/ceph/addr.c @@ -1353,11 +1353,11 @@ static int ceph_write_begin(struct file *file, struct address_space *mapping, /* * In some cases we don't need to read at all: * - full page write - * - write that lies completely beyond EOF + * - write that lies in a page that is completely beyond EOF * - write that covers the the page from start to EOF or beyond it */ if ((pos_in_page == 0 && len == PAGE_SIZE) || - (pos >= i_size_read(inode)) || + (index > (i_size_read(inode) - 1) / PAGE_SIZE) || (pos_in_page == 0 && (pos + len) >= i_size_read(inode))) { zero_user_segments(page, 0, pos_in_page, pos_in_page + len, PAGE_SIZE); -- 2.31.1