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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 2B49AC33CAF for ; Thu, 16 Jan 2020 18:41:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F18A62073A for ; Thu, 16 Jan 2020 18:41:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579200117; bh=2JHxflA3BEtDI5QcLJ6LyPWNK5cwoOxsgiMg5wbwaxM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=BH2pk0Ampj9oj0I8pffPvXFO/kY/J0OuEqq1ui/v7C6mrusuvFYtl2lRH6I/T8YMs B9H6gOdpet6IxoBgL7g0VUHwTwwgeF0XB3DvtunFbc7+N90uWGjTiDgN0IyLbDPaaG IeFuqgU2sxdeAeYkJjsfXZmxDNCRgJHA/Pb4vMMw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407219AbgAPSlz (ORCPT ); Thu, 16 Jan 2020 13:41:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:52934 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390300AbgAPRLn (ORCPT ); Thu, 16 Jan 2020 12:11:43 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 470A32468B; Thu, 16 Jan 2020 17:11:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579194703; bh=2JHxflA3BEtDI5QcLJ6LyPWNK5cwoOxsgiMg5wbwaxM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PCi6FKUKKaAsKHoo7mH5bgCCIikBmlX1/KDDI12AkN85zWJpVv1sJ53MOG0HlxoB6 QpN6L8xU/Omid01rM7eswkBzPpoVeF3bFq9w5JPvLx8XQgJ5Qms/n/1tScOqK6QiBQ Ms6bUgi7qLQv4D3Et/thJWzZ76fpPef9azh3GsSk= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Omar Sandoval , Josef Bacik , David Sterba , Sasha Levin , linux-btrfs@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 542/671] btrfs: use correct count in btrfs_file_write_iter() Date: Thu, 16 Jan 2020 12:03:00 -0500 Message-Id: <20200116170509.12787-279-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200116170509.12787-1-sashal@kernel.org> References: <20200116170509.12787-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 d9d90f0b66d2..f4a7dac76356 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; @@ -1916,6 +1916,7 @@ 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