[PATCH RFC v4 13/14] dm: wait for IO completion before removing dm device

[Yu Kuai]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

__dm_destroy() guarantee that device openers is zero, and then
only call 'presuspend' and 'postsuspend' for the target. For
request-based dm, 'md->holders' will be grabbed for each rq and
__dm_destroy() will wait for 'md->holders' to be zero. However, for
bio-based device, __dm_destroy() doesn't wait for all bios to be done.

Fix this problem by calling dm_wait_for_completion() to wail for all
inflight IO to be done, like what dm_suspend() does.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
 drivers/md/dm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 8dcabf84d866..2c0eae67d0f1 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -58,6 +58,7 @@ static DEFINE_IDR(_minor_idr);
 static DEFINE_SPINLOCK(_minor_lock);
 
 static void do_deferred_remove(struct work_struct *w);
+static int dm_wait_for_completion(struct mapped_device *md, unsigned int task_state);
 
 static DECLARE_WORK(deferred_remove_work, do_deferred_remove);
 
@@ -2495,6 +2496,8 @@ static void __dm_destroy(struct mapped_device *md, bool wait)
 	if (!dm_suspended_md(md)) {
 		dm_table_presuspend_targets(map);
 		set_bit(DMF_SUSPENDED, &md->flags);
+		if (wait)
+			dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
 		set_bit(DMF_POST_SUSPENDING, &md->flags);
 		dm_table_postsuspend_targets(map);
 	}
-- 
2.39.2