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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 1EB5CC35242 for ; Fri, 24 Jan 2020 11:36:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DF929214DB for ; Fri, 24 Jan 2020 11:36:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579865771; bh=8xtYyg7+SDIEx0EaTtvEbsD9NmTNykgngsI7aLmLz3A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=mq7ukUKvzw66gSIT2FFrgseQ2/DJROZJvTZBSH2Xi52UiP/prEHXgNJy2+cLc7ycx +fkL5a1Bd/Qw2BSwFsC7tQwhhjtBapbURFBhdpFEbo9bgY5TiHoSMdVohV+Oz9vlfa jqsVUyLMGhytNtXSt+aUmTGpvJjmJ4yFA30t19Fk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404522AbgAXLc5 (ORCPT ); Fri, 24 Jan 2020 06:32:57 -0500 Received: from mail.kernel.org ([198.145.29.99]:52024 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404504AbgAXLcv (ORCPT ); Fri, 24 Jan 2020 06:32:51 -0500 Received: from localhost (ip-213-127-102-57.ip.prioritytelecom.net [213.127.102.57]) (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 6324B2075D; Fri, 24 Jan 2020 11:32:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579865571; bh=8xtYyg7+SDIEx0EaTtvEbsD9NmTNykgngsI7aLmLz3A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uOlrbJDpDpxMeU6Kxo2LRM8nm/2KeM0bb7xYn0NLxoOi0ID8mjuUbrLBavjM98roh McRJ80sfIduy/YjUAWTDUHCH4GrzR2k/dS3hbciL+xhKUAahrppywZI65sEmD16c7t X78b+uhxAvCu2bHyKcoH/NUBTcigBYu+PujK0gzY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josef Bacik , Omar Sandoval , David Sterba , Sasha Levin Subject: [PATCH 4.19 556/639] btrfs: use correct count in btrfs_file_write_iter() Date: Fri, 24 Jan 2020 10:32:06 +0100 Message-Id: <20200124093158.919118869@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200124093047.008739095@linuxfoundation.org> References: <20200124093047.008739095@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Omar Sandoval [ Upstream commit c09767a8960ca0500fb636bf73686723337debf4 ] generic_write_checks() may modify iov_iter_count(), so we must get the count after the call, not before. Using the wrong one has a couple of consequences: 1. We check a longer range in check_can_nocow() for nowait than we're actually writing. 2. We create extra hole extent maps in btrfs_cont_expand(). As far as I can tell, this is harmless, but I might be missing something. These issues are pretty minor, but let's fix it before something more important trips on it. Fixes: edf064e7c6fe ("btrfs: nowait aio support") Reviewed-by: Josef Bacik Signed-off-by: Omar Sandoval Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/file.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 78490e544c91e..c2c93fe9d7fd5 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1895,7 +1895,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host); ssize_t err; loff_t pos; - size_t count = iov_iter_count(from); + size_t count; loff_t oldsize; int clean_page = 0; @@ -1917,6 +1917,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, } pos = iocb->ki_pos; + count = iov_iter_count(from); if (iocb->ki_flags & IOCB_NOWAIT) { /* * We will allocate space in case nodatacow is not set, -- 2.20.1