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 7D466C433B4 for ; Tue, 13 Apr 2021 17:46:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 448216102A for ; Tue, 13 Apr 2021 17:46:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347280AbhDMRqa (ORCPT ); Tue, 13 Apr 2021 13:46:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:43748 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231224AbhDMRq3 (ORCPT ); Tue, 13 Apr 2021 13:46:29 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 224B060200; Tue, 13 Apr 2021 17:46:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618335969; bh=hce5BP80dHrW/3zrskwEpTFPq4gPKx30JhoHYeCX4p8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HDxZW2S7VGKpduPoCK3JbvmJ92tof7TzmeFggChD8HDZ3hm2JmAJBBWp1ff4alNOu l2uwNoQ8Jcm6A7Vn6TKYeRERD88PZjAhMmK5hHxYJ6w5YrRjIbz8UpHu9ewOAvcukz 7jSWP/gB5BcJkk0PhWZvXSciXPv44Bji6XfSezipbt9mwKBpvdO+J07guLEkHm1o4Y UVyXX7sUPhIw0fmydzyM7lG93Jevf7/74Ml/aRpIO8s6k0wxKO/iCPHlixwivTpApn PXr04ex2FJ1CVeBZ3W5474qF1wV4nslUwI4zLotgvndOGGU+/ezCYD0pNshDAzdkIL JlqnPlVj7c9bA== Date: Tue, 13 Apr 2021 10:46:07 -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> <1171d722-8810-998c-e4b3-0845dbbdea19@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1171d722-8810-998c-e4b3-0845dbbdea19@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/13, Chao Yu wrote: > On 2021/4/13 11:27, Jaegeuk Kim wrote: > > 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? > > Do you have specific test script? > > IIRC, the scenario you mean is multi-threads write/mmap the same db, right? I suggest to run sqlite transaction/check operations in android devices in parallel. > > Thanks, > > > > > > > > > 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 > > . > >