[Devel] [PATCH hci-8.1 v6 4/6] dm-qcow2: complete wbd before ending the data qio

[Alexander Ivanov]

data_rw_complete() calls qio_endio() before complete_wbd(). qio_endio()
drops the inflight ref, so qcow2_flush_deferred_activity() may return
on suspend while complete_wbd() for a failed L1/L2 writeback is still
running in AIO completion context. revert_l_entries_update() then
marks clusters unused and dirties R2 after the flush, and the change
is never written back.

Complete the wbd first. The md writeback path already does it in this
order.

https://virtuozzo.atlassian.net/browse/VSTOR-148171
Feature: dm-qcow2: block device over QCOW2 files driver
Signed-off-by: Alexander Ivanov <alexander.ivanov at virtuozzo.com>
---
 drivers/md/dm-qcow2-map.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-qcow2-map.c b/drivers/md/dm-qcow2-map.c
index 810dd22425ae..ef832813b718 100644
--- a/drivers/md/dm-qcow2-map.c
+++ b/drivers/md/dm-qcow2-map.c
@@ -2884,13 +2884,14 @@ static void data_rw_complete(struct qio *qio)
 		spin_unlock_irqrestore(&qcow2->md_pages_lock, flags);
 	}
 
+	/* qio_endio() drops the inflight ref, which suspend waits for */
+	if (finalize_wbd)
+		complete_wbd(qcow2, wbd);
 	if (call_endio) {
 		if (bi_status != BLK_STS_OK)
 			qio->bi_status = bi_status;
 		qio_endio(qio);
 	}
-	if (finalize_wbd)
-		complete_wbd(qcow2, wbd);
 }
 
 static void perform_rw_mapped(struct qcow2_map *map, struct qio *qio)
-- 
2.53.0