[PATCH 4.14 01/18] bio: ensure __bio_clone_fast copies bi_partno

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Michael Lyle <mlyle@xxxxxxxx>

commit 62530ed8b1d07a45dec94d46e521c0c6c2d476e6 upstream.

A new field was introduced in 74d46992e0d9, bi_partno, instead of using
bdev->bd_contains and encoding the partition information in the bi_bdev
field.  __bio_clone_fast was changed to copy the disk information, but
not the partition information.  At minimum, this regressed bcache and
caused data corruption.

Signed-off-by: Michael Lyle <mlyle@xxxxxxxx>
Fixes: 74d46992e0d9 ("block: replace bi_bdev with a gendisk pointer and partitions index")
Reported-by: Pavel Goran <via-bcache@xxxxxxxxxxxx>
Reported-by: Campbell Steven <casteven@xxxxxxxxx>
Reviewed-by: Coly Li <colyli@xxxxxxx>
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 block/bio.c |    1 +
 1 file changed, 1 insertion(+)

--- a/block/bio.c
+++ b/block/bio.c
@@ -597,6 +597,7 @@ void __bio_clone_fast(struct bio *bio, s
 	 * so we don't set nor calculate new physical/hw segment counts here
 	 */
 	bio->bi_disk = bio_src->bi_disk;
+	bio->bi_partno = bio_src->bi_partno;
 	bio_set_flag(bio, BIO_CLONED);
 	bio->bi_opf = bio_src->bi_opf;
 	bio->bi_write_hint = bio_src->bi_write_hint;