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authorMikulas Patocka <mpatocka@redhat.com>2020-02-24 12:20:28 +0300
committerMike Snitzer <snitzer@redhat.com>2020-02-28 00:40:58 +0300
commitadc0daad366b62ca1bce3e2958a40b0b71a8b8b3 (patch)
tree03c033437b0699892741bb7363d99bdd2c864ed9 /drivers/md/dm.c
parent3918e0667bbac99400b44fa5aef3f8be2eeada4a (diff)
downloadlinux-adc0daad366b62ca1bce3e2958a40b0b71a8b8b3.tar.xz
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.c1
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 */