[PATCH] block: always set partition number to '0' in blk_partition_remap()

[axboe@kernel.dk (Jens Axboe)]

On 6/6/18 8:22 AM, Hannes Reinecke wrote:
> blk_partition_remap() will only clear bi_partno if an actual remapping
> has happened. But flush request et al don't have an actual size, so
> the remapping doesn't happen and bi_partno is never cleared.
> So for stacked devices blk_partition_remap() will be called on each level.
> If (as is the case for native nvme multipathing) one of the lower-level
> devices do _not_support partitioning a spurious I/O error is generated.

Just move it down, we're now clearing it for both cases.

diff --git a/block/blk-core.c b/block/blk-core.c
index 3f56be15f17e..cf0ee764b908 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2220,10 +2220,10 @@ static inline int blk_partition_remap(struct bio *bio)
 		if (bio_check_eod(bio, part_nr_sects_read(p)))
 			goto out;
 		bio->bi_iter.bi_sector += p->start_sect;
-		bio->bi_partno = 0;
 		trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p),
 				      bio->bi_iter.bi_sector - p->start_sect);
 	}
+	bio->bi_partno = 0;
 	ret = 0;
 out:
 	rcu_read_unlock();

-- 
Jens Axboe