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| author | Mikulas Patocka <mpatocka@redhat.com> | 2020-02-24 10:20:28 +0100 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2020-02-27 22:40:58 +0100 |
| commit | adc0daad366b62ca1bce3e2958a40b0b71a8b8b3 (patch) | |
| tree | 03c033437b0699892741bb7363d99bdd2c864ed9 /drivers/md/dm.c | |
| parent | dm thin metadata: fix lockdep complaint (diff) | |
| download | linux-adc0daad366b62ca1bce3e2958a40b0b71a8b8b3.tar.xz linux-adc0daad366b62ca1bce3e2958a40b0b71a8b8b3.zip | |
dm: report suspended device during destroy
The function dm_suspended returns true if the target is suspended.
However, when the target is being suspended during unload, it returns
false.
An example where this is a problem: the test "!dm_suspended(wc->ti)" in
writecache_writeback is not sufficient, because dm_suspended returns
zero while writecache_suspend is in progress. As is, without an
enhanced dm_suspended, simply switching from flush_workqueue to
drain_workqueue still emits warnings:
workqueue writecache-writeback: drain_workqueue() isn't complete after 10 tries
workqueue writecache-writeback: drain_workqueue() isn't complete after 100 tries
workqueue writecache-writeback: drain_workqueue() isn't complete after 200 tries
workqueue writecache-writeback: drain_workqueue() isn't complete after 300 tries
workqueue writecache-writeback: drain_workqueue() isn't complete after 400 tries
writecache_suspend calls flush_workqueue(wc->writeback_wq) - this function
flushes the current work. However, the workqueue may re-queue itself and
flush_workqueue doesn't wait for re-queued works to finish. Because of
this - the function writecache_writeback continues execution after the
device was suspended and then concurrently with writecache_dtr, causing
a crash in writecache_writeback.
We must use drain_workqueue - that waits until the work and all re-queued
works finish.
As a prereq for switching to drain_workqueue, this commit fixes
dm_suspended to return true after the presuspend hook and before the
postsuspend hook - just like during a normal suspend. It allows
simplifying the dm-integrity and dm-writecache targets so that they
don't have to maintain suspended flags on their own.
With this change use of drain_workqueue() can be used effectively. This
change was tested with the lvm2 testsuite and cryptsetup testsuite and
the are no regressions.
Fixes: 48debafe4f2f ("dm: add writecache target")
Cc: stable@vger.kernel.org # 4.18+
Reported-by: Corey Marthaler <cmarthal@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm.c')
| -rw-r--r-- | drivers/md/dm.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index b89f07ee2eff..d01ad6a35dd0 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2368,6 +2368,7 @@ static void __dm_destroy(struct mapped_device *md, bool wait) map = dm_get_live_table(md, &srcu_idx); if (!dm_suspended_md(md)) { dm_table_presuspend_targets(map); + set_bit(DMF_SUSPENDED, &md->flags); dm_table_postsuspend_targets(map); } /* dm_put_live_table must be before msleep, otherwise deadlock is possible */ |