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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH 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 34A8EF83CA1 for ; Sun, 29 Jul 2018 06:03:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA61820893 for ; Sun, 29 Jul 2018 06:03:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="VsYcVi/M" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CA61820893 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726241AbeG2HcS (ORCPT ); Sun, 29 Jul 2018 03:32:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:34984 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725906AbeG2HcS (ORCPT ); Sun, 29 Jul 2018 03:32:18 -0400 Received: from [192.168.0.101] (unknown [180.111.102.36]) (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 0FE0320873; Sun, 29 Jul 2018 06:03:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1532844183; bh=3FFW3zpLyDlYDYwkO1BxvZMT9zOWFGswIalmk2fMRbA=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=VsYcVi/MvcoI9BK7rJCko/bk8C5SmMsEQnicLgXpE8x/6sxvW33FvP9ctpzsQEeqk 4MvUQLo8EjvWQSBZ2z/ocfHK4mgcbvx636+O0SfPSkJvfKXT7n8+gQqMVHFgxJbnxN sBWlGYSzF7JeT1ssRNibvFsg1IFEFfRSia7WWX0Q= Subject: Re: [PATCH 3/4] f2fs: fix avoid race between truncate and background GC To: Jaegeuk Kim , Chao Yu Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org References: <20180727101516.41403-1-yuchao0@huawei.com> <20180727101516.41403-3-yuchao0@huawei.com> <20180729015806.GF83620@jaegeuk-macbookpro.roam.corp.google.com> From: Chao Yu Message-ID: <39022876-5d16-c78a-4869-a316a5021384@kernel.org> Date: Sun, 29 Jul 2018 14:02:59 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180729015806.GF83620@jaegeuk-macbookpro.roam.corp.google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/7/29 9:58, Jaegeuk Kim wrote: > On 07/27, Chao Yu wrote: >> Thread A Background GC >> - f2fs_setattr isize to 0 >> - truncate_setsize >> - gc_data_segment >> - f2fs_get_read_data_page page #0 >> - set_page_dirty >> - set_cold_data >> - f2fs_truncate >> >> - f2fs_setattr isize to 4k >> - read 4k <--- hit data in cached page #0 >> >> Above race condition can cause read out invalid data in a truncated >> page, fix it by i_gc_rwsem[WRITE] lock. > > We can truncate pages again after f2fs_truncate()? I think it can fix this issue, although it looks a little strange to truncate page cache twice. Thanks, > >> >> Signed-off-by: Chao Yu >> --- >> fs/f2fs/data.c | 4 ++++ >> fs/f2fs/file.c | 33 +++++++++++++++++++-------------- >> 2 files changed, 23 insertions(+), 14 deletions(-) >> >> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >> index 071224ded5f4..a29f3162b887 100644 >> --- a/fs/f2fs/data.c >> +++ b/fs/f2fs/data.c >> @@ -2214,10 +2214,14 @@ static void f2fs_write_failed(struct address_space *mapping, loff_t to) >> loff_t i_size = i_size_read(inode); >> >> if (to > i_size) { >> + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); >> down_write(&F2FS_I(inode)->i_mmap_sem); >> + >> truncate_pagecache(inode, i_size); >> f2fs_truncate_blocks(inode, i_size, true); >> + >> up_write(&F2FS_I(inode)->i_mmap_sem); >> + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); >> } >> } >> >> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >> index 7bd2412a8c37..ed5c9b0e0d0c 100644 >> --- a/fs/f2fs/file.c >> +++ b/fs/f2fs/file.c >> @@ -796,22 +796,25 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr) >> } >> >> if (attr->ia_valid & ATTR_SIZE) { >> - if (attr->ia_size <= i_size_read(inode)) { >> - down_write(&F2FS_I(inode)->i_mmap_sem); >> - truncate_setsize(inode, attr->ia_size); >> + bool to_smaller = (attr->ia_size <= i_size_read(inode)); >> + >> + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); >> + down_write(&F2FS_I(inode)->i_mmap_sem); >> + >> + truncate_setsize(inode, attr->ia_size); >> + >> + if (to_smaller) >> err = f2fs_truncate(inode); >> - up_write(&F2FS_I(inode)->i_mmap_sem); >> - if (err) >> - return err; >> - } else { >> - /* >> - * do not trim all blocks after i_size if target size is >> - * larger than i_size. >> - */ >> - down_write(&F2FS_I(inode)->i_mmap_sem); >> - truncate_setsize(inode, attr->ia_size); >> - up_write(&F2FS_I(inode)->i_mmap_sem); >> + /* >> + * do not trim all blocks after i_size if target size is >> + * larger than i_size. >> + */ >> + up_write(&F2FS_I(inode)->i_mmap_sem); >> + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); >> + if (err) >> + return err; >> >> + if (!to_smaller) { >> /* should convert inline inode here */ >> if (!f2fs_may_inline_data(inode)) { >> err = f2fs_convert_inline_inode(inode); >> @@ -958,6 +961,7 @@ static int punch_hole(struct inode *inode, loff_t offset, loff_t len) >> >> blk_start = (loff_t)pg_start << PAGE_SHIFT; >> blk_end = (loff_t)pg_end << PAGE_SHIFT; >> + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); >> down_write(&F2FS_I(inode)->i_mmap_sem); >> truncate_inode_pages_range(mapping, blk_start, >> blk_end - 1); >> @@ -966,6 +970,7 @@ static int punch_hole(struct inode *inode, loff_t offset, loff_t len) >> ret = f2fs_truncate_hole(inode, pg_start, pg_end); >> f2fs_unlock_op(sbi); >> up_write(&F2FS_I(inode)->i_mmap_sem); >> + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); >> } >> } >> >> -- >> 2.18.0.rc1