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 E9E0AC67790 for ; Fri, 27 Jul 2018 10:29:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 917F7208A4 for ; Fri, 27 Jul 2018 10:29:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="z+X/FXds" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 917F7208A4 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 S1731149AbeG0Luh (ORCPT ); Fri, 27 Jul 2018 07:50:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:42698 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729489AbeG0Luh (ORCPT ); Fri, 27 Jul 2018 07:50:37 -0400 Received: from localhost (unknown [119.197.233.250]) (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 8D099208A2; Fri, 27 Jul 2018 10:29:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1532687360; bh=DmKL19mdN8G3ZC0jr7gLOoaBo890N+xZVOp42yp6iw8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=z+X/FXdsGtVVmzMqlHdn3WjvIlS8izdiNu11kexDyH4hrm554TugBcqawpakEG604 Un13iyWlhlmuYyxPAJvnZXVxSYU8/AG3HRqnGeq6LLP8xIuAIb/OLPiY4jrrB7wjOR Q/+euOlswWw2VlPCSiyRg2kyLEy7XPlNaTfpLBTI= Date: Fri, 27 Jul 2018 19:29:16 +0900 From: Jaegeuk Kim To: Chao Yu Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, chao@kernel.org Subject: Re: [PATCH] f2fs: avoid race between zero_range and background GC Message-ID: <20180727102916.GI16155@jaegeuk-macbookpro.roam.corp.google.com> References: <20180726104536.114340-1-yuchao0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180726104536.114340-1-yuchao0@huawei.com> 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 07/26, Chao Yu wrote: > Thread A Background GC > - f2fs_zero_range > - truncate_pagecache_range > - gc_data_segment > - get_read_data_page > - move_data_page > - set_page_dirty > - set_cold_data > - f2fs_do_zero_range > - dn->data_blkaddr = NEW_ADDR; > - f2fs_set_data_blkaddr > > Actually, we don't need to set dirty & checked flag on the page, since > all valid data in the page should be zeroed by zero_range(). But, it doesn't matter too much, right? > Use i_gc_rwsem[WRITE] to avoid such race condition. Hope to avoid abusing i_gc_rwsem[] tho. > > Signed-off-by: Chao Yu > --- > fs/f2fs/file.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > index 267ec3794e1e..7bd2412a8c37 100644 > --- a/fs/f2fs/file.c > +++ b/fs/f2fs/file.c > @@ -1309,6 +1309,7 @@ static int f2fs_zero_range(struct inode *inode, loff_t offset, loff_t len, > if (ret) > return ret; > > + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > down_write(&F2FS_I(inode)->i_mmap_sem); > ret = filemap_write_and_wait_range(mapping, offset, offset + len - 1); > if (ret) > @@ -1389,6 +1390,7 @@ static int f2fs_zero_range(struct inode *inode, loff_t offset, loff_t len, > } > out_sem: > up_write(&F2FS_I(inode)->i_mmap_sem); > + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > return ret; > } > -- > 2.18.0.rc1