[PATCH v8 5/5] dm-crypt: Fix lost ioprio when queuing write bios

[Hongyu Jin]

From: Hongyu Jin <hongyu.jin@xxxxxxxxxx>

Since dm-crypt queues writes to a different kernel thread (workqueue),
the bios will dispatch from tasks with different io_context->ioprio
settings and blkcg than the submitting task, thus giving incorrect
ioprio to the io scheduler.

Get the original io priority setting via struct dm_crypt_io::base_bio
and set this priority to the bio for write.

Link: https://lore.kernel.org/dm-devel/alpine.LRH.2.11.1612141049250.13402@xxxxxxxxxxxxxxxxx

Signed-off-by: Hongyu Jin <hongyu.jin@xxxxxxxxxx>
---
 drivers/md/dm-crypt.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 855b482cbff1..e0804a86946f 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1683,6 +1683,7 @@ static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned int size)
 				 GFP_NOIO, &cc->bs);
 	clone->bi_private = io;
 	clone->bi_end_io = crypt_endio;
+	clone->bi_ioprio = io->base_bio->bi_ioprio;
 
 	remaining_size = size;
 
-- 
2.34.1