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=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 0B39DC33CAF for ; Thu, 16 Jan 2020 17:29:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CE4D824716 for ; Thu, 16 Jan 2020 17:29:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579195768; bh=OEdYCTN3y8EPJ9dDW/5viKwgfPGu0Jh8WKDLMDDsaXg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=SbA0/pnFu8ly76Cml1CuJIV6OOI4mLXTVZtw95cijGSaf2rp/o5x6A/21rk/QqGTx bi5OpUvgrKfNJjDcPkdlxl+bmIPmSPLK8HgWBao4vRd6UIucgwHBsO+QyGt8zhnKQt o9UBSSQYmNo5bzmcyTiARQzpceV/VSTidttJ773U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392721AbgAPR31 (ORCPT ); Thu, 16 Jan 2020 12:29:27 -0500 Received: from mail.kernel.org ([198.145.29.99]:41272 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392712AbgAPR30 (ORCPT ); Thu, 16 Jan 2020 12:29:26 -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 700D7246E3; Thu, 16 Jan 2020 17:29:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579195766; bh=OEdYCTN3y8EPJ9dDW/5viKwgfPGu0Jh8WKDLMDDsaXg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=G8kGH0YZ9JOl22R8yNy8SvwnvNq+DZUSgZHQGXbbKjMUsc1FvHUuORe73tDaljZx/ 6ESr8OfxBkGWD+WlZGCgcsW9R172tKyFNEoDPaVGMkjzz/xWzm+PoSvVPiatMFHfbk FDpkrB1MnAQZDaPotD+YjKshTogrOZW2esmfxs1w= 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 4.14 294/371] btrfs: use correct count in btrfs_file_write_iter() Date: Thu, 16 Jan 2020 12:22:46 -0500 Message-Id: <20200116172403.18149-237-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200116172403.18149-1-sashal@kernel.org> References: <20200116172403.18149-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@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 bf654d48eb46..dd5f6e0df63f 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1882,7 +1882,7 @@ 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; @@ -1903,6 +1903,7 @@ 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