Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 94E9EC74A5B for ; Fri, 17 Mar 2023 12:45:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230268AbjCQMpS (ORCPT ); Fri, 17 Mar 2023 08:45:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229480AbjCQMpQ (ORCPT ); Fri, 17 Mar 2023 08:45:16 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56FCAA54C2; Fri, 17 Mar 2023 05:45:15 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id E2E3921A57; Fri, 17 Mar 2023 12:45:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1679057113; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=13wHn270QC2EQIv2STg6ZbJmqaKqLZmBmJiFjnKTwvs=; b=Qut3hqc62LhEoqknDZyCmGO2oR93XHZ3JzqRD6vpejnvwODTQcV6jJeK3sasp0abOxdFC/ PRdjRh0NkBRKNn+biTi/XsseBY//nkxiqSFdrRutvWidOENOs51014KWRYmY+ufwrLunbV R7V9tDEqB3j9a4oQ8y5DfhWG9aYUQRg= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1679057113; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=13wHn270QC2EQIv2STg6ZbJmqaKqLZmBmJiFjnKTwvs=; b=q8H+KfiNRWMn9w/fU7d84yvMgpfML13d2YqlfrM54CFcIT80izEqu3difcTYOK7UuCqiCB D7WpQry3Ka05QDCQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id D1AB213428; Fri, 17 Mar 2023 12:45:13 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 3wgjM9lgFGS4PgAAMHmgww (envelope-from ); Fri, 17 Mar 2023 12:45:13 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 57DC4A06FD; Fri, 17 Mar 2023 13:45:13 +0100 (CET) Date: Fri, 17 Mar 2023 13:45:13 +0100 From: Jan Kara To: Zhihao Cheng Cc: tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.com, tudor.ambarus@linaro.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com Subject: Re: [PATCH] ext4: Fix i_disksize exceeding i_size problem in paritally written case Message-ID: <20230317124513.drx3wywcjnap5jme@quack3> References: <20230317013553.1009553-1-chengzhihao1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230317013553.1009553-1-chengzhihao1@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Fri 17-03-23 09:35:53, Zhihao Cheng wrote: > Following process makes i_disksize exceed i_size: > > generic_perform_write > copied = iov_iter_copy_from_user_atomic(len) // copied < len > ext4_da_write_end > | ext4_update_i_disksize > | new_i_size = pos + copied; > | WRITE_ONCE(EXT4_I(inode)->i_disksize, newsize) // update i_disksize > | generic_write_end > | copied = block_write_end(copied, len) // copied = 0 > | if (unlikely(copied < len)) > | if (!PageUptodate(page)) > | copied = 0; > | if (pos + copied > inode->i_size) // return false > if (unlikely(copied == 0)) > goto again; > if (unlikely(iov_iter_fault_in_readable(i, bytes))) { > status = -EFAULT; > break; > } > > We get i_disksize greater than i_size here, which could trigger WARNING > check 'i_size_read(inode) < EXT4_I(inode)->i_disksize' while doing dio: > > ext4_dio_write_iter > iomap_dio_rw > __iomap_dio_rw // return err, length is not aligned to 512 > ext4_handle_inode_extension > WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize) // Oops > > WARNING: CPU: 2 PID: 2609 at fs/ext4/file.c:319 > CPU: 2 PID: 2609 Comm: aa Not tainted 6.3.0-rc2 > RIP: 0010:ext4_file_write_iter+0xbc7 > Call Trace: > vfs_write+0x3b1 > ksys_write+0x77 > do_syscall_64+0x39 > > Fix it by putting block_write_end() before i_disksize updating just > like ext4_write_end() does. > > Fetch a reproducer in [Link]. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=217209 > Fixes: 64769240bd07f ("ext4: Add delayed allocation support in data=writeback mode") > Signed-off-by: Zhihao Cheng Good catch (although practically this will hardly have any negative effect). But rather than opencoding generic_write_end() I'd do: if (unlikely(copied < len) && !PageUptodate(page)) copied = 0; at the beginning of ext4_da_write_end() and that should solve these problems as well? Honza > --- > fs/ext4/inode.c | 32 +++++++++++++++++++++++++------- > 1 file changed, 25 insertions(+), 7 deletions(-) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index bf0b7dea4900..577dc23f3b78 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3136,6 +3136,8 @@ static int ext4_da_write_end(struct file *file, > loff_t new_i_size; > unsigned long start, end; > int write_mode = (int)(unsigned long)fsdata; > + bool i_size_changed = false; > + loff_t old_size = inode->i_size; > > if (write_mode == FALL_BACK_TO_NONDELALLOC) > return ext4_write_end(file, mapping, pos, > @@ -3148,6 +3150,8 @@ static int ext4_da_write_end(struct file *file, > ext4_has_inline_data(inode)) > return ext4_write_inline_data_end(inode, pos, len, copied, page); > > + copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); > + > start = pos & (PAGE_SIZE - 1); > end = start + copied - 1; > > @@ -3162,16 +3166,30 @@ static int ext4_da_write_end(struct file *file, > * check), we need to update i_disksize here as neither > * ext4_writepage() nor certain ext4_writepages() paths not > * allocating blocks update i_disksize. > - * > - * Note that we defer inode dirtying to generic_write_end() / > - * ext4_da_write_inline_data_end(). > */ > new_i_size = pos + copied; > - if (copied && new_i_size > inode->i_size && > - ext4_da_should_update_i_disksize(page, end)) > - ext4_update_i_disksize(inode, new_i_size); > + if (new_i_size > inode->i_size) { > + i_size_write(inode, new_i_size); > + i_size_changed = true; > + if (copied && ext4_da_should_update_i_disksize(page, end)) > + ext4_update_i_disksize(inode, new_i_size); > + } > + > + unlock_page(page); > + put_page(page); > + > + if (old_size < pos) > + pagecache_isize_extended(inode, old_size, pos); > + /* > + * Don't mark the inode dirty under page lock. First, it unnecessarily > + * makes the holding time of page lock longer. Second, it forces lock > + * ordering of page lock and transaction start for journaling > + * filesystems. > + */ > + if (i_size_changed) > + mark_inode_dirty(inode); > > - return generic_write_end(file, mapping, pos, len, copied, page, fsdata); > + return copied; > } > > /* > -- > 2.31.1 > -- Jan Kara SUSE Labs, CR