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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED, USER_AGENT_MUTT 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 68290F83CA2 for ; Sun, 29 Jul 2018 06:13:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0A54E20894 for ; Sun, 29 Jul 2018 06:13:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="TVxQUWC6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0A54E20894 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 S1726281AbeG2HnI (ORCPT ); Sun, 29 Jul 2018 03:43:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:36010 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725899AbeG2HnI (ORCPT ); Sun, 29 Jul 2018 03:43:08 -0400 Received: from localhost (c-67-160-202-76.hsd1.ca.comcast.net [67.160.202.76]) (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 9A94E20892; Sun, 29 Jul 2018 06:13:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1532844831; bh=aOwSVMb1lBso6HHQsLJKMg2WH9VnDqhvjd6pcc1EMPg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TVxQUWC66J1nldTUKxwavDrWulIktVBR20lFCuYL3UiyJMFouNMq7AVtZnHGGZt5/ AVreDOfDOF6oO92G9pTvFu1Fx5f9sZPCUDRg1RmZT/2AjlyLNpoy1/yYsI1E0hD3Hw KTf8gRroWSGRP1MFwSInWoJd19XVnl42NUNyA3IY= Date: Sat, 28 Jul 2018 23:13:51 -0700 From: Jaegeuk Kim To: Chao Yu Cc: Chao Yu , linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4] f2fs: fix avoid race between truncate and background GC Message-ID: <20180729061351.GA5102@jaegeuk-macbookpro.roam.corp.google.com> References: <20180727101516.41403-1-yuchao0@huawei.com> <20180727101516.41403-3-yuchao0@huawei.com> <20180729015806.GF83620@jaegeuk-macbookpro.roam.corp.google.com> <39022876-5d16-c78a-4869-a316a5021384@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <39022876-5d16-c78a-4869-a316a5021384@kernel.org> User-Agent: Mutt/1.8.2 (2017-04-18) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/29, Chao Yu wrote: > 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. It'd be fine to do setsize first, and drop the cache later. > > 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