block: assign bi_bdev for cloned bios in blk_rq_prep_clone

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 <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
[hch: the commit message is mostly from a different patch from Benjamin]
Reviewed-by: Ming Lei <[email protected]>
Reviewed-by: Benjamin Marzinski <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

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