All requests allocated from a request_queue with this callback set can
failover their requests during completion.
This callback is expected to use the blk_steal_bios() interface to
transfer a request's bios back to an upper-layer bio-based
request_queue.
This will be used by both NVMe multipath and DM multipath. Without it
DM multipath cannot get access to NVMe-specific error handling that NVMe
core provides in nvme_complete_rq().
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
include/linux/blkdev.h | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 8089ca17db9a..f45f5925e100 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -278,6 +278,7 @@ typedef int (lld_busy_fn) (struct request_queue *q);
typedef int (bsg_job_fn) (struct bsg_job *);
typedef int (init_rq_fn)(struct request_queue *, struct request *, gfp_t);
typedef void (exit_rq_fn)(struct request_queue *, struct request *);
+typedef void (failover_rq_fn)(struct request *);
enum blk_eh_timer_return {
BLK_EH_NOT_HANDLED,
@@ -423,6 +424,11 @@ struct request_queue {
exit_rq_fn *exit_rq_fn;
/* Called from inside blk_get_request() */
void (*initialize_rq_fn)(struct request *rq);
+ /*
+ * Callback to failover request's bios back to upper layer
+ * bio-based request_queue using blk_steal_bios().
+ */
+ failover_rq_fn *failover_rq_fn;
const struct blk_mq_ops *mq_ops;
--
2.15.0
