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=-16.2 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 autolearn=unavailable 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 C1118C433E0 for ; Tue, 19 Jan 2021 19:24:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F6E823104 for ; Tue, 19 Jan 2021 19:24:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390835AbhASTYM (ORCPT ); Tue, 19 Jan 2021 14:24:12 -0500 Received: from mail.kernel.org ([198.145.29.99]:39968 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404715AbhASTHO (ORCPT ); Tue, 19 Jan 2021 14:07:14 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 959F620706; Tue, 19 Jan 2021 19:06:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611083193; bh=GFMcQd7MCGExxp99LiWFW+po75/fewRWAf29QDD2b68=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Sr0IvLwt5KD1z2YKY0WKaQt210uFFKSvdgLdnsDzgUguo6V/qWCcsRSkTtbBJzPQL XGe9OfQlyL4XG0lISytwN9eZxrd8kJCfRsliwuGXBElmMaTZpVLfUtm/a1ezRAQbac x3m1XjlEKCbJNKiEaGTnf8fetUdVTH4J+rUYVijzoEEByS+2YnnVKX13PMELaLacZG esAUOxhCuR+7607vK8qvLIX4nBuPJFyknZ52/Qy8EvBfNj6/KqHoZm16ANo8S1gTdJ 6XKHVlcAYbQqLlPkp6A+xzGNBNKCbhxQSI+GggUoDE9LuWPhk/ZyGikAUP5POKfhYs YYsqyYnve9x8A== Date: Tue, 19 Jan 2021 11:06:32 -0800 From: Jaegeuk Kim To: Chao Yu Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, chao@kernel.org Subject: Re: [PATCH v2] f2fs: fix to keep isolation of atomic write Message-ID: References: <20201230075557.108818-1-yuchao0@huawei.com> <3923906d-f208-f6c2-f121-5e77e8fb6b28@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3923906d-f208-f6c2-f121-5e77e8fb6b28@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/15, Chao Yu wrote: > On 2021/1/15 5:53, Jaegeuk Kim wrote: > > On 12/30, Chao Yu wrote: > > > ThreadA ThreadB > > > - f2fs_ioc_start_atomic_write > > > - write > > > - f2fs_ioc_commit_atomic_write > > > - f2fs_commit_inmem_pages > > > - f2fs_drop_inmem_pages > > > - f2fs_drop_inmem_pages > > > - __revoke_inmem_pages > > > - f2fs_vm_page_mkwrite > > > - set_page_dirty > > > - tag ATOMIC_WRITTEN_PAGE and add page > > > to inmem_pages list > > > - clear_inode_flag(FI_ATOMIC_FILE) > > > - f2fs_vm_page_mkwrite > > > - set_page_dirty > > > - f2fs_update_dirty_page > > > - f2fs_trace_pid > > > - tag inmem page private to pid > > > > Hmm, how about removing fs/f2fs/trace.c to make private more complicated > > like this? I think we can get IO traces from tracepoints. > > Hmm, actually, there is are issues, one is the trace IO, the other is the > race issue (atomic_start,commit,drop vs mkwrite) which can make isolation > semantics of transaction be broken. > > Or can we avoid atomic file racing with file mmap? No, we can't. We may need to find other way to check the race. :) > > - atomic_start - file_mmap > - inode_lock > - if (FI_ATOMIC_FILE) return > - inode_lock > - if (FI_MMAP_FILE) return > > Thanks, > > > > > > - truncate > > > - f2fs_invalidate_page > > > - set page->mapping to NULL > > > then it will cause panic once we > > > access page->mapping > > > > > > The root cause is we missed to keep isolation of atomic write in the case > > > of commit_atomic_write vs mkwrite, let commit_atomic_write helds i_mmap_sem > > > lock to avoid this issue. > > > > > > Signed-off-by: Chao Yu > > > --- > > > v2: > > > - use i_mmap_sem to avoid mkwrite racing with below flows: > > > * f2fs_ioc_start_atomic_write > > > * f2fs_drop_inmem_pages > > > * f2fs_commit_inmem_pages > > > > > > fs/f2fs/file.c | 3 +++ > > > fs/f2fs/segment.c | 7 +++++++ > > > 2 files changed, 10 insertions(+) > > > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > > index 4e6d4b9120a8..a48ec650d691 100644 > > > --- a/fs/f2fs/file.c > > > +++ b/fs/f2fs/file.c > > > @@ -2050,6 +2050,7 @@ 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 > > > @@ -2060,6 +2061,7 @@ 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; > > > } > > > @@ -2073,6 +2075,7 @@ 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 d8570b0359f5..dab870d9faf6 100644 > > > --- a/fs/f2fs/segment.c > > > +++ b/fs/f2fs/segment.c > > > @@ -327,6 +327,8 @@ void f2fs_drop_inmem_pages(struct inode *inode) > > > struct f2fs_sb_info *sbi = F2FS_I_SB(inode); > > > struct f2fs_inode_info *fi = F2FS_I(inode); > > > + down_write(&F2FS_I(inode)->i_mmap_sem); > > > + > > > while (!list_empty(&fi->inmem_pages)) { > > > mutex_lock(&fi->inmem_lock); > > > __revoke_inmem_pages(inode, &fi->inmem_pages, > > > @@ -344,6 +346,8 @@ void f2fs_drop_inmem_pages(struct inode *inode) > > > sbi->atomic_files--; > > > } > > > spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); > > > + > > > + up_write(&F2FS_I(inode)->i_mmap_sem); > > > } > > > void f2fs_drop_inmem_page(struct inode *inode, struct page *page) > > > @@ -467,6 +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); > > > @@ -478,6 +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 > > . > >