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Sat, 27 Jan 2024 15:52:00 +0800 (CST) From: Yu Kuai To: mpatocka@redhat.com, heinzm@redhat.com, xni@redhat.com, agk@redhat.com, snitzer@kernel.org, dm-devel@lists.linux.dev, song@kernel.org, yukuai3@huawei.com, jbrassow@f14.redhat.com, neilb@suse.de, shli@fb.com, akpm@osdl.org Cc: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com Subject: [PATCH v3 00/12] dm-raid: fix v6.7 regressions Date: Sat, 27 Jan 2024 15:47:42 +0800 Message-Id: <20240127074754.2380890-1-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: dm-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: cCh0CgDHlxAetrRlWjeACA--.31980S4 X-Coremail-Antispam: 1UD129KBjvJXoWxur4xZw4rCr15WFyxXr1kZrb_yoW7Jry5pa yakw13Xr4UCrn7urZ3J3W0qa45Kas5JrW5Gr9xJ34rAw1YyFyIyrW8GayUWFWDAFy3Jw45 tr45Ka4F9a4YyaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUv014x267AKxVW5JVWrJwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r 4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628v n2kIc2xKxwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F4 0E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GFv_Wryl IxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxV AFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6rW3Jr0E3s1lIxAIcVC2z280aVAFwI0_ Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VUb QVy7UUUUU== X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ From: Yu Kuai Changes in v3: - fix a problem in patch 5; - add patch 12; Changes in v2: - replace revert changes for dm-raid with real fixes; - fix dm-raid5 deadlock that exist for a long time, this deadlock is triggered because another problem is fixed in raid5, and instead of deadlock, user will read wrong data before v6.7, patch 9-11; First regression related to stop sync thread: The lifetime of sync_thread is designed as following: 1) Decide want to start sync_thread, set MD_RECOVERY_NEEDED, and wake up daemon thread; 2) Daemon thread detect that MD_RECOVERY_NEEDED is set, then set MD_RECOVERY_RUNNING and register sync_thread; 3) Execute md_do_sync() for the actual work, if it's done or interrupted, it will set MD_RECOVERY_DONE and wake up daemone thread; 4) Daemon thread detect that MD_RECOVERY_DONE is set, then clear MD_RECOVERY_RUNNING and unregister sync_thread; In v6.7, we fix md/raid to follow this design by commit f52f5c71f3d4 ("md: fix stopping sync thread"), however, dm-raid is not considered at that time, and following test will hang: shell/integrity-caching.sh shell/lvconvert-raid-reshape.sh This patch set fix the broken test by patch 1-4; - patch 1 fix that step 4) is broken by suspended array; - patch 2 fix that step 4) is broken by read-only array; - patch 3 fix that step 3) is broken that md_do_sync() doesn't set MD_RECOVERY_DONE; Noted that this patch will introdece new problem that data will be corrupted, which will be fixed in later patches. - patch 4 fix that setp 1) is broken that sync_thread is register and MD_RECOVERY_RUNNING is set directly, md/raid behaviour, not related to dm-raid; With patch 1-4, the above test won't hang anymore, however, the test will still fail and complain that ext4 is corrupted; Second regression related to frozen sync thread: Noted that for raid456, if reshape is interrupted, then call "pers->start_reshape" will corrupt data. And dm-raid rely on md_do_sync() doesn't set MD_RECOVERY_DONE so that new sync_thread won't be registered, and patch 3 just break this. - Patch 5-6 fix this problem by interrupting reshape and frozen sync_thread in dm_suspend(), then unfrozen and continue reshape in dm_resume(). It's verified that dm-raid tests won't complain that ext4 is corrupted anymore. - Patch 7 fix the problem that raid_message() call md_reap_sync_thread() directly, without holding 'reconfig_mutex'. Last regression related to dm-raid456 IO concurrent with reshape: For raid456, if reshape is still in progress, then IO across reshape position will wait for reshape to make progress. However, for dm-raid, in following cases reshape will never make progress hence IO will hang: 1) the array is read-only; 2) MD_RECOVERY_WAIT is set; 3) MD_RECOVERY_FROZEN is set; After commit c467e97f079f ("md/raid6: use valid sector values to determine if an I/O should wait on the reshape") fix the problem that IO across reshape position doesn't wait for reshape, the dm-raid test shell/lvconvert-raid-reshape.sh start to hang at raid5_make_request(). For md/raid, the problem doesn't exist because: 1) If array is read-only, it can switch to read-write by ioctl/sysfs; 2) md/raid never set MD_RECOVERY_WAIT; 3) If MD_RECOVERY_FROZEN is set, mddev_suspend() doesn't hold 'reconfig_mutex' anymore, it can be cleared and reshape can continue by sysfs api 'sync_action'. However, I'm not sure yet how to avoid the problem in dm-raid yet. - patch 9-11 fix this problem by detecting the above 3 cases in dm_suspend(), and fail those IO directly. If user really meet the IO error, then it means they're reading the wrong data before c467e97f079f. And it's safe to read/write the array after reshape make progress successfully. There are also some other minor changes: patch 8 and patch 12; Yu Kuai (12): md: don't ignore suspended array in md_check_recovery() md: don't ignore read-only array in md_check_recovery() md: make sure md_do_sync() will set MD_RECOVERY_DONE md: don't register sync_thread for reshape directly md: export helpers to stop sync_thread dm-raid: really frozen sync_thread during suspend md/dm-raid: don't call md_reap_sync_thread() directly dm-raid: remove mddev_suspend/resume() dm-raid: add a new helper prepare_suspend() in md_personality md: export helper md_is_rdwr() md/raid456: fix a deadlock for dm-raid456 while io concurrent with reshape dm-raid: fix lockdep waring in "pers->hot_add_disk" drivers/md/dm-raid.c | 78 ++++++++++++++++++++++++----------- drivers/md/md.c | 96 ++++++++++++++++++++++++++++---------------- drivers/md/md.h | 16 ++++++++ drivers/md/raid10.c | 16 +------- drivers/md/raid5.c | 61 +++++++++++++++------------- 5 files changed, 167 insertions(+), 100 deletions(-)