From patchwork Thu Dec 28 12:46:46 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Long Li X-Patchwork-Id: 13505984 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 699A4748F for ; Thu, 28 Dec 2023 12:50:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.44]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4T17Yt4ZT3z1FGVV; Thu, 28 Dec 2023 20:46:58 +0800 (CST) Received: from kwepemi500009.china.huawei.com (unknown [7.221.188.199]) by mail.maildlp.com (Postfix) with ESMTPS id 106FF140414; Thu, 28 Dec 2023 20:50:51 +0800 (CST) Received: from localhost.localdomain (10.175.127.227) by kwepemi500009.china.huawei.com (7.221.188.199) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Thu, 28 Dec 2023 20:50:50 +0800 From: Long Li To: , CC: , , , , Subject: [PATCH] xfs: ensure submit buffers on LSN boundaries in error handlers Date: Thu, 28 Dec 2023 20:46:46 +0800 Message-ID: <20231228124646.142757-1-leo.lilong@huawei.com> X-Mailer: git-send-email 2.31.1 Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemi500009.china.huawei.com (7.221.188.199) While performing the IO fault injection test, I caught the following data corruption report: XFS (dm-0): Internal error ltbno + ltlen > bno at line 1957 of file fs/xfs/libxfs/xfs_alloc.c. Caller xfs_free_ag_extent+0x79c/0x1130 CPU: 3 PID: 33 Comm: kworker/3:0 Not tainted 6.5.0-rc7-next-20230825-00001-g7f8666926889 #214 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014 Workqueue: xfs-inodegc/dm-0 xfs_inodegc_worker Call Trace: dump_stack_lvl+0x50/0x70 xfs_corruption_error+0x134/0x150 xfs_free_ag_extent+0x7d3/0x1130 __xfs_free_extent+0x201/0x3c0 xfs_trans_free_extent+0x29b/0xa10 xfs_extent_free_finish_item+0x2a/0xb0 xfs_defer_finish_noroll+0x8d1/0x1b40 xfs_defer_finish+0x21/0x200 xfs_itruncate_extents_flags+0x1cb/0x650 xfs_free_eofblocks+0x18f/0x250 xfs_inactive+0x485/0x570 xfs_inodegc_worker+0x207/0x530 process_scheduled_works+0x24a/0xe10 worker_thread+0x5ac/0xc60 kthread+0x2cd/0x3c0 ret_from_fork+0x4a/0x80 ret_from_fork_asm+0x11/0x20 XFS (dm-0): Corruption detected. Unmount and run xfs_repair After analyzing the disk image, it was found that the corruption was triggered by the fact that extent was recorded in both the inode and AGF btrees. After a long time of reproduction and analysis, we found that the root cause of the problem was that the AGF btree block was not recovered. Consider the following situation, Transaction A and Transaction B are in the same record, so Transaction A and Transaction B share the same LSN1. If the buf item in Transaction A has been recovered, then the buf item in Transaction B cannot be recovered, because log recovery skips items with a metadata LSN >= the current LSN of the recovery item. If there is still an inode item in transaction B that records the Extent X, the Extent X will be recorded in both the inode and the AGF btree block after transaction B is recovered. |------------Record (LSN1)------------------|---Record (LSN2)---| |----------Trans A------------|-------------Trans B-------------| | Buf Item(Extent X) | Buf Item / Inode item(Extent X) | | Extent X is freed | Extent X is allocated | After commit 12818d24db8a ("xfs: rework log recovery to submit buffers on LSN boundaries") was introduced, we submit buffers on lsn boundaries during log recovery. The above problem can be avoided under normal paths, but it's not guaranteed under abnormal paths. Consider the following process, if an error was encountered after recover buf item in transaction A and before recover buf item in transaction B, buffers that have been added to buffer_list will still be submitted, this violates the submits rule on lsn boundaries. So buf item in Transaction B cannot be recovered on the next mount due to current lsn of transaction equal to metadata lsn on disk. xlog_do_recovery_pass error = xlog_recover_process xlog_recover_process_data ... xlog_recover_buf_commit_pass2 xlog_recover_do_reg_buffer //recover buf item in Trans A xfs_buf_delwri_queue(bp, buffer_list) ... ====> Encountered error and returned ... xlog_recover_buf_commit_pass2 xlog_recover_do_reg_buffer //recover buf item in Trans B xfs_buf_delwri_queue(bp, buffer_list) if (!list_empty(&buffer_list)) xfs_buf_delwri_submit(&buffer_list); //submit regardless of error In order to make sure that submits buffers on lsn boundaries in the abnormal paths, we need to check error status before submit buffers that have been added from the last record processed. If error status exist, buffers in the bufffer_list should be canceled. Canceling the buffers in the buffer_list directly isn't correct, unlike any other place where write list was canceled, these buffers has been initialized by xfs_buf_item_init() during recovery and held by buf item, buf items will not be released in xfs_buf_delwri_cancel(). If these buffers are submitted successfully, buf items assocated with the buffer will be released in io end process. So releasing buf item in write list cacneling process is needed. Fixes: 50d5c8d8e938 ("xfs: check LSN ordering for v5 superblocks during recovery") Signed-off-by: Long Li --- fs/xfs/xfs_buf.c | 2 ++ fs/xfs/xfs_log_recover.c | 22 +++++++++++++--------- 2 files changed, 15 insertions(+), 9 deletions(-) diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 8e5bd50d29fe..6a1b26aaf97e 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -2075,6 +2075,8 @@ xfs_buf_delwri_cancel( xfs_buf_lock(bp); bp->b_flags &= ~_XBF_DELWRI_Q; xfs_buf_list_del(bp); + if (bp->b_log_item) + xfs_buf_item_relse(bp); xfs_buf_relse(bp); } } diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c index 1251c81e55f9..2cda6c90890d 100644 --- a/fs/xfs/xfs_log_recover.c +++ b/fs/xfs/xfs_log_recover.c @@ -2964,7 +2964,6 @@ xlog_do_recovery_pass( char *offset; char *hbp, *dbp; int error = 0, h_size, h_len; - int error2 = 0; int bblks, split_bblks; int hblks, split_hblks, wrapped_hblks; int i; @@ -3203,16 +3202,21 @@ xlog_do_recovery_pass( bread_err1: kmem_free(hbp); - /* - * Submit buffers that have been added from the last record processed, - * regardless of error status. - */ - if (!list_empty(&buffer_list)) - error2 = xfs_buf_delwri_submit(&buffer_list); - if (error && first_bad) *first_bad = rhead_blk; + /* + * If there are no error, submit buffers that have been added from the + * last record processed, othrewise cancel the write list, to ensure + * submit buffers on LSN boundaries. + */ + if (!list_empty(&buffer_list)) { + if (error) + xfs_buf_delwri_cancel(&buffer_list); + else + error = xfs_buf_delwri_submit(&buffer_list); + } + /* * Transactions are freed at commit time but transactions without commit * records on disk are never committed. Free any that may be left in the @@ -3226,7 +3230,7 @@ xlog_do_recovery_pass( xlog_recover_free_trans(trans); } - return error ? error : error2; + return error; } /*