From nobody Fri Oct 24 20:26:40 2025 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 7B088C28B2C for ; Mon, 15 Aug 2022 23:37:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353782AbiHOXg1 (ORCPT ); Mon, 15 Aug 2022 19:36:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43976 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353433AbiHOXbk (ORCPT ); Mon, 15 Aug 2022 19:31:40 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 919F214F97C; Mon, 15 Aug 2022 13:08:14 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8CB0160B6E; Mon, 15 Aug 2022 20:08:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97F19C433C1; Mon, 15 Aug 2022 20:08:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660594093; bh=qbzUrqN7cH0JP7uC2Tl4OalEZ7Wbjp6GiUMN+PORSdc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zGJsLcPEu4VGkYlSlCo2vlCPEIdfOsRSexEd8ljeM3DkD6YNUa7zqb1Z/iYjynFR+ 98ioYc8UedVte2xhp/a3Bw2SSNhuCXS199yOqPa7S+awO54vKAahVRR9S9n0d/HYsR RneL7NgOFoCVJmO6r+RfbzhmYBjR5pmp3LFnrywc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, stable@kernel.org, Ye Bin , Eric Whitney , Theodore Tso , Sasha Levin Subject: [PATCH 5.18 1055/1095] ext4: fix extent status tree race in writeback error recovery path Date: Mon, 15 Aug 2022 20:07:34 +0200 Message-Id: <20220815180512.700807649@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180429.240518113@linuxfoundation.org> References: <20220815180429.240518113@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Eric Whitney [ Upstream commit 7f0d8e1d607c1a4fa9a27362a108921d82230874 ] A race can occur in the unlikely event ext4 is unable to allocate a physical cluster for a delayed allocation in a bigalloc file system during writeback. Failure to allocate a cluster forces error recovery that includes a call to mpage_release_unused_pages(). That function removes any corresponding delayed allocated blocks from the extent status tree. If a new delayed write is in progress on the same cluster simultaneously, resulting in the addition of an new extent containing one or more blocks in that cluster to the extent status tree, delayed block accounting can be thrown off if that delayed write then encounters a similar cluster allocation failure during future writeback. Write lock the i_data_sem in mpage_release_unused_pages() to fix this problem. Ext4's block/cluster accounting code for bigalloc relies on i_data_sem for mutual exclusion, as is found in the delayed write path, and the locking in mpage_release_unused_pages() is missing. Cc: stable@kernel.org Reported-by: Ye Bin Signed-off-by: Eric Whitney Link: https://lore.kernel.org/r/20220615160530.1928801-1-enwlinux@gmail.com Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- fs/ext4/inode.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index beed9e32571c..826e2deb10f8 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1559,7 +1559,14 @@ static void mpage_release_unused_pages(struct mpage_= da_data *mpd, ext4_lblk_t start, last; start =3D index << (PAGE_SHIFT - inode->i_blkbits); last =3D end << (PAGE_SHIFT - inode->i_blkbits); + + /* + * avoid racing with extent status tree scans made by + * ext4_insert_delayed_block() + */ + down_write(&EXT4_I(inode)->i_data_sem); ext4_es_remove_extent(inode, start, last - start + 1); + up_write(&EXT4_I(inode)->i_data_sem); } =20 pagevec_init(&pvec); --=20 2.35.1