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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C6EF7C433B4 for ; Tue, 13 Apr 2021 03:27:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 97086611CC for ; Tue, 13 Apr 2021 03:27:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244354AbhDMD1a (ORCPT ); Mon, 12 Apr 2021 23:27:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:50160 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238029AbhDMD13 (ORCPT ); Mon, 12 Apr 2021 23:27:29 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 33D44610D2; Tue, 13 Apr 2021 03:27:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618284430; bh=0XnIuzI4K1ZQhd0EadbJgO7P+abJbaS+1SwJrUxgrig=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bQEcSE35DaAXjwGNWQnZ0ZVbFIA38TY/UAwm1KwD/AeFpapF/ib7Lm55UC50tH8Ml looATXDVBxBBQ6C8s7v9qoGjfICvFolNd/PFclLdSQo0rlijLaRjHPn0dYcd9clB/D 5mbd6ufP1e5wObcamjBwimH09zySCVboYTaypryjrZFWuBHyioQuEyMDHY+WUzcYyM fv4KXDhpRIUxvYj5rgmrrqzuJa7MLvGGMCn0dnrBls1jVL4ThphLTJ6Q+gKpwaUhaL I+Va8Bs1VgvMdHc+07xZG6/Mz8F3izN1Jn5M8pG4MUiCHDWRnRN21h5R9wwRobZEPt 0pJUx+sarPCuA== Date: Mon, 12 Apr 2021 20:27:08 -0700 From: Jaegeuk Kim To: Chao Yu Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, chao@kernel.org, Yi Chen Subject: Re: [PATCH v3] f2fs: fix to keep isolation of atomic write Message-ID: References: <20210412081512.103592-1-yuchao0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210412081512.103592-1-yuchao0@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/12, Chao Yu wrote: > As Yi Chen reported, there is a potential race case described as below: > > Thread A Thread B > - f2fs_ioc_start_atomic_write > - mkwrite > - set_page_dirty > - f2fs_set_page_private(page, 0) > - set_inode_flag(FI_ATOMIC_FILE) > - mkwrite same page > - set_page_dirty > - f2fs_register_inmem_page > - f2fs_set_page_private(ATOMIC_WRITTEN_PAGE) > failed due to PagePrivate flag has been set > - list_add_tail > - truncate_inode_pages > - f2fs_invalidate_page > - clear page private but w/o remove it from > inmem_list > - set page->mapping to NULL > - f2fs_ioc_commit_atomic_write > - __f2fs_commit_inmem_pages > - __revoke_inmem_pages > - f2fs_put_page panic as page->mapping is NULL > > The root cause is we missed to keep isolation of atomic write in the case > of start_atomic_write vs mkwrite, let start_atomic_write helds i_mmap_sem > lock to avoid this issue. My only concern is performance regression. Could you please verify the numbers? > > Reported-by: Yi Chen > Signed-off-by: Chao Yu > --- > v3: > - rebase to last dev branch > - update commit message because this patch fixes a different racing issue > of atomic write > fs/f2fs/file.c | 3 +++ > fs/f2fs/segment.c | 6 ++++++ > 2 files changed, 9 insertions(+) > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > index d697c8900fa7..6284b2f4a60b 100644 > --- a/fs/f2fs/file.c > +++ b/fs/f2fs/file.c > @@ -2054,6 +2054,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) > goto out; > > down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > + down_write(&F2FS_I(inode)->i_mmap_sem); > > /* > * Should wait end_io to count F2FS_WB_CP_DATA correctly by > @@ -2064,6 +2065,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) > inode->i_ino, get_dirty_pages(inode)); > ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX); > if (ret) { > + up_write(&F2FS_I(inode)->i_mmap_sem); > up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > goto out; > } > @@ -2077,6 +2079,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) > /* add inode in inmem_list first and set atomic_file */ > set_inode_flag(inode, FI_ATOMIC_FILE); > clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST); > + up_write(&F2FS_I(inode)->i_mmap_sem); > up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > f2fs_update_time(F2FS_I_SB(inode), REQ_TIME); > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index 0cb1ca88d4aa..78c8342f52fd 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -325,6 +325,7 @@ void f2fs_drop_inmem_pages(struct inode *inode) > struct f2fs_inode_info *fi = F2FS_I(inode); > > do { > + down_write(&F2FS_I(inode)->i_mmap_sem); > mutex_lock(&fi->inmem_lock); > if (list_empty(&fi->inmem_pages)) { > fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0; > @@ -339,11 +340,13 @@ void f2fs_drop_inmem_pages(struct inode *inode) > spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); > > mutex_unlock(&fi->inmem_lock); > + up_write(&F2FS_I(inode)->i_mmap_sem); > break; > } > __revoke_inmem_pages(inode, &fi->inmem_pages, > true, false, true); > mutex_unlock(&fi->inmem_lock); > + up_write(&F2FS_I(inode)->i_mmap_sem); > } while (1); > } > > @@ -468,6 +471,7 @@ int f2fs_commit_inmem_pages(struct inode *inode) > f2fs_balance_fs(sbi, true); > > down_write(&fi->i_gc_rwsem[WRITE]); > + down_write(&F2FS_I(inode)->i_mmap_sem); > > f2fs_lock_op(sbi); > set_inode_flag(inode, FI_ATOMIC_COMMIT); > @@ -479,6 +483,8 @@ int f2fs_commit_inmem_pages(struct inode *inode) > clear_inode_flag(inode, FI_ATOMIC_COMMIT); > > f2fs_unlock_op(sbi); > + > + up_write(&F2FS_I(inode)->i_mmap_sem); > up_write(&fi->i_gc_rwsem[WRITE]); > > return err; > -- > 2.29.2