block: Always initialize bio IO priority on submit

Currently, IO priority set in task's IO context is not reflected in the
bio->bi_ioprio for most IO (only io_uring and direct IO set it). This
results in odd results where process is submitting some bios with one
priority and other bios with a different (unset) priority and due to
differing priorities bios cannot be merged. Make sure bio->bi_ioprio is
always set on bio submission.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220623074840.5960-9-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index c0ec1938feee06c830f91409d8944296a1748d2c..92aae03103b74e4f489f3cc4e3ede889f7076f05 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2782,6 +2782,9 @@ static inline struct request *blk_mq_get_cached_request(struct request_queue *q,
 
 static void bio_set_ioprio(struct bio *bio)
 {
+       /* Nobody set ioprio so far? Initialize it based on task's nice value */
+       if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) == IOPRIO_CLASS_NONE)
+               bio->bi_ioprio = get_current_ioprio();
        blkcg_set_ioprio(bio);
 }