From nobody Wed Dec 17 00:05:05 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 A10ACC04FE2 for ; Tue, 15 Aug 2023 11:30:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236758AbjHOLaP (ORCPT ); Tue, 15 Aug 2023 07:30:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236776AbjHOL3v (ORCPT ); Tue, 15 Aug 2023 07:29:51 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 101201BE8; Tue, 15 Aug 2023 04:29:40 -0700 (PDT) Received: from canpemm500010.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4RQ8CS09wyz1GDW8; Tue, 15 Aug 2023 19:28:20 +0800 (CST) Received: from huawei.com (10.175.127.227) by canpemm500010.china.huawei.com (7.192.105.118) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Tue, 15 Aug 2023 19:29:38 +0800 From: Ye Bin To: , CC: , Ye Bin Subject: [PATCH v2 3/4] ext2: fix race between setxattr and write back Date: Tue, 15 Aug 2023 19:26:11 +0800 Message-ID: <20230815112612.221145-4-yebin10@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20230815112612.221145-1-yebin10@huawei.com> References: <20230815112612.221145-1-yebin10@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To canpemm500010.china.huawei.com (7.192.105.118) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" There's a issue as follows: Block Allocation Reservation Windows Map (ext2_try_to_allocate_with_rsv): reservation window 0x000000006f105382 start: 0, end: 0 reservation window 0x000000008fd1a555 start: 1044, end: 1059 Window map complete. kernel BUG at fs/ext2/balloc.c:1158! invalid opcode: 0000 [#1] PREEMPT SMP KASAN RIP: 0010:ext2_try_to_allocate_with_rsv.isra.0+0x15c4/0x1800 Call Trace: ext2_new_blocks+0x935/0x1690 ext2_new_block+0x73/0xa0 ext2_xattr_set2+0x74f/0x1730 ext2_xattr_set+0x12b6/0x2260 ext2_xattr_user_set+0x9c/0x110 __vfs_setxattr+0x139/0x1d0 __vfs_setxattr_noperm+0xfc/0x370 __vfs_setxattr_locked+0x205/0x2c0 vfs_setxattr+0x19d/0x3b0 do_setxattr+0xff/0x220 setxattr+0x123/0x150 path_setxattr+0x193/0x1e0 __x64_sys_setxattr+0xc8/0x170 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Above issue may happens as follows: setxattr write back ext2_xattr_set ext2_xattr_set2 ext2_new_block ext2_new_blocks ext2_try_to_allocate_with_rsv alloc_new_reservation --> group=3D0 [0, 1023] rsv [1016, 1023] do_writepages mpage_writepages write_cache_pages __mpage_writepage ext2_get_block ext2_get_blocks ext2_alloc_branch ext2_new_blocks ext2_try_to_allocate_w= ith_rsv alloc_new_reservation -->group=3D1 [1024, 2047] rsv [1044, 1= 059] if ((my_rsv->rsv_start > group_last_block) || (my_rsv->rsv_end < group_first_block) rsv_window_dump BUG(); Now ext2 mkwrite delay allocate new blocks. So there maybe allocate blocks = when do write back. However, there is no concurrent protection between ext2_xattr_set() and do_writepages(). To solve about issue don't use reservation window when allocate block for x= attr. Signed-off-by: Ye Bin --- fs/ext2/balloc.c | 15 +++++++++------ fs/ext2/xattr.c | 4 ++-- 2 files changed, 11 insertions(+), 8 deletions(-) diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c index 99a19f2ecd6f..4ff1d831bb80 100644 --- a/fs/ext2/balloc.c +++ b/fs/ext2/balloc.c @@ -1247,13 +1247,16 @@ ext2_fsblk_t ext2_new_blocks(struct inode *inode, e= xt2_fsblk_t goal, * it's a regular file, and * the desired window size is greater than 0 (One could use ioctl * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off - * reservation on that particular file) + * reservation on that particular file), and unspecified Do not use + * reservation window. */ - block_i =3D EXT2_I(inode)->i_block_alloc_info; - if (block_i) { - windowsz =3D block_i->rsv_window_node.rsv_goal_size; - if (windowsz > 0) - my_rsv =3D &block_i->rsv_window_node; + if (!(flag & EXT2_ALLOC_NORESERVE)) { + block_i =3D EXT2_I(inode)->i_block_alloc_info; + if (block_i) { + windowsz =3D block_i->rsv_window_node.rsv_goal_size; + if (windowsz > 0) + my_rsv =3D &block_i->rsv_window_node; + } } =20 if (!ext2_has_free_blocks(sbi)) { diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c index e076386a26f4..21725b8d04c8 100644 --- a/fs/ext2/xattr.c +++ b/fs/ext2/xattr.c @@ -743,8 +743,8 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head= *old_bh, ext2_fsblk_t goal =3D ext2_group_first_block_no(sb, EXT2_I(inode)->i_block_group); unsigned long count =3D 1; - int block =3D ext2_new_blocks(inode, goal, &count, - &error, 0); + int block =3D ext2_new_blocks(inode, goal, &count, &error, + EXT2_ALLOC_NORESERVE); if (error) goto cleanup; ea_idebug(inode, "creating block %d", block); --=20 2.31.1