[PATCHv2] block: always set partition number to '0' in blk_partition_remap()

[Hannes Reinecke <hare@suse.de>]

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.

Signed-off-by: Hannes Reinecke <hare@suse.com>
---
 block/blk-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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();
-- 
2.12.3