bio_clone_fast() sets the cloned bio to have the same ->bi_bdev as the
source bio. This means that when request-based dm called setup_clone(),
the cloned bio had its ->bi_bdev pointing to the dm device. After Commit
0b6e522cdc4a ("blk-mq: use ->bi_bdev for I/O accounting")
__blk_account_io_start() started using the request's ->bio->bi_bdev for
I/O accounting, if it was set. This caused IO going to the underlying
devices to use the dm device for their I/O accounting.
Set up the proper ->bi_bdev in blk_rq_prep_clone based on the whole
device bdev for the queue the request is cloned onto.
Fixes: 0b6e522cdc4a ("blk-mq: use ->bi_bdev for I/O accounting")
Reported-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
[hch: the commit message is mostly from a different patch from Benjamin]
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Reviewed-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
---
block/blk-mq.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index a6d4780580fcd..b5e35e63adad4 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2976,6 +2976,7 @@ int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
bio = bio_clone_fast(bio_src, gfp_mask, bs);
if (!bio)
goto free_and_out;
+ bio->bi_bdev = rq->q->disk->part0;
if (bio_ctr && bio_ctr(bio, bio_src, data))
goto free_and_out;
--
2.30.2
