On Tue, Jan 30, 2024 at 10:23 AM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
>
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> Changes in v4:
> - add patch 10 to fix a raid456 deadlock(for both md/raid and dm-raid);
> - add patch 13 to wait for inflight IO completion while removing dm
> device;
>
> 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;
>
> Test result:
>
> I apply this patchset on top of v6.8-rc1, and run lvm2 tests suite with
> folling cmd for 24 round(for about 2 days):
>
> for t in `ls test/shell`; do
> if cat test/shell/$t | grep raid &> /dev/null; then
> make check T=shell/$t
> fi
> done
>
> failed count failed test
> 1 ### failed: [ndev-vanilla] shell/dmsecuretest.sh
> 1 ### failed: [ndev-vanilla] shell/dmsetup-integrity-keys.sh
> 1 ### failed: [ndev-vanilla] shell/dmsetup-keyring.sh
> 5 ### failed: [ndev-vanilla] shell/duplicate-pvs-md0.sh
> 1 ### failed: [ndev-vanilla] shell/duplicate-vgid.sh
> 2 ### failed: [ndev-vanilla] shell/duplicate-vgnames.sh
> 1 ### failed: [ndev-vanilla] shell/fsadm-crypt.sh
> 1 ### failed: [ndev-vanilla] shell/integrity.sh
> 6 ### failed: [ndev-vanilla] shell/lvchange-raid1-writemostly.sh
> 2 ### failed: [ndev-vanilla] shell/lvchange-rebuild-raid.sh
> 5 ### failed: [ndev-vanilla] shell/lvconvert-raid-reshape-stripes-load-reload.sh
> 4 ### failed: [ndev-vanilla] shell/lvconvert-raid-restripe-linear.sh
> 1 ### failed: [ndev-vanilla] shell/lvconvert-raid1-split-trackchanges.sh
> 20 ### failed: [ndev-vanilla] shell/lvconvert-repair-raid.sh
> 20 ### failed: [ndev-vanilla] shell/lvcreate-large-raid.sh
> 24 ### failed: [ndev-vanilla] shell/lvextend-raid.sh
>
> And I ramdomly pick some tests verified by hand that these test will
> fail in v6.6 as well(not all tests, I don't have the time do do this yet):
>
> shell/lvextend-raid.sh
> shell/lvcreate-large-raid.sh
> shell/lvconvert-repair-raid.sh
> shell/lvchange-rebuild-raid.sh
> shell/lvchange-raid1-writemostly.sh
>
> Yu Kuai (14):
> 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: add a new helper prepare_suspend() in md_personality
> md: export helper md_is_rdwr()
> md: don't suspend the array for interrupted reshape
> md/raid456: fix a deadlock for dm-raid456 while io concurrent with
> reshape
> dm-raid: fix lockdep waring in "pers->hot_add_disk"
> dm: wait for IO completion before removing dm device
> dm-raid: remove mddev_suspend/resume()
>
> drivers/md/dm-raid.c | 78 +++++++++++++++++++---------
> drivers/md/dm.c | 3 ++
> drivers/md/md.c | 120 +++++++++++++++++++++++++++++--------------
> drivers/md/md.h | 16 ++++++
> drivers/md/raid10.c | 16 +-----
> drivers/md/raid5.c | 61 ++++++++++++----------
> 6 files changed, 190 insertions(+), 104 deletions(-)
>
> --
> 2.39.2
>
Hi all
In my environment, the lvm2 regression test has passed. There are only
three failed cases which also fail in kernel 6.6.
### failed: [ndev-vanilla] shell/lvresize-fs-crypt.sh
### failed: [ndev-vanilla] shell/pvck-dump.sh
### failed: [ndev-vanilla] shell/select-report.sh
### 426 tests: 346 passed, 70 skipped, 0 timed out, 7 warned, 3 failed
in 89:26.073
Best Regards
Xiao
