drbd: Keep a reference to the bio until the completion handler finished

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_actlog.c

@@ -118,6 +118,7 @@ static int _drbd_md_sync_page_io(struct drbd_conf *mdev,
 	bio->bi_end_io = drbd_md_io_complete;
 	bio->bi_rw = rw;
 
+	bio_get(bio); /* one bio_put() is in the completion handler */
 	atomic_inc(&mdev->md_io_in_use); /* drbd_md_put_buffer() is in the completion handler */
 	if (drbd_insert_fault(mdev, (rw & WRITE) ? DRBD_FAULT_MD_WR : DRBD_FAULT_MD_RD))
 		bio_endio(bio, -EIO);

drivers/block/drbd/drbd_worker.c

@@ -79,6 +79,7 @@ void drbd_md_io_complete(struct bio *bio, int error)
 
 	md_io->done = 1;
 	wake_up(&mdev->misc_wait);
+	bio_put(bio);
 	drbd_md_put_buffer(mdev);
 }