ublk: convert to refcount_t

Convert to refcount_t and prepare for supporting to register bvec buffer
automatically, which needs to initialize reference counter as 2, and
kref doesn't provide this interface, so convert to refcount_t.

Reviewed-by: Caleb Sander Mateos <[email protected]>
Suggested-by: Caleb Sander Mateos <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

Author: Ming Lei

drivers/block/ublk_drv.c

@@ -79,7 +79,7 @@
 	 UBLK_PARAM_TYPE_DMA_ALIGN | UBLK_PARAM_TYPE_SEGMENT)
 
 struct ublk_rq_data {
-	struct kref ref;
+	refcount_t ref;
 };
 
 struct ublk_uring_cmd_pdu {
@@ -488,7 +488,6 @@ static blk_status_t ublk_setup_iod_zoned(struct ublk_queue *ubq,
 #endif
 
 static inline void __ublk_complete_rq(struct request *req);
-static void ublk_complete_rq(struct kref *ref);
 
 static dev_t ublk_chr_devt;
 static const struct class ublk_chr_class = {
@@ -648,7 +647,7 @@ static inline void ublk_init_req_ref(const struct ublk_queue *ubq,
 	if (ublk_need_req_ref(ubq)) {
 		struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
 
-		kref_init(&data->ref);
+		refcount_set(&data->ref, 1);
 	}
 }
 
@@ -658,7 +657,7 @@ static inline bool ublk_get_req_ref(const struct ublk_queue *ubq,
 	if (ublk_need_req_ref(ubq)) {
 		struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
 
-		return kref_get_unless_zero(&data->ref);
+		return refcount_inc_not_zero(&data->ref);
 	}
 
 	return true;
@@ -670,7 +669,8 @@ static inline void ublk_put_req_ref(const struct ublk_queue *ubq,
 	if (ublk_need_req_ref(ubq)) {
 		struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
 
-		kref_put(&data->ref, ublk_complete_rq);
+		if (refcount_dec_and_test(&data->ref))
+			__ublk_complete_rq(req);
 	} else {
 		__ublk_complete_rq(req);
 	}
@@ -1122,15 +1122,6 @@ static inline void __ublk_complete_rq(struct request *req)
 	blk_mq_end_request(req, res);
 }
 
-static void ublk_complete_rq(struct kref *ref)
-{
-	struct ublk_rq_data *data = container_of(ref, struct ublk_rq_data,
-			ref);
-	struct request *req = blk_mq_rq_from_pdu(data);
-
-	__ublk_complete_rq(req);
-}
-
 static void ublk_complete_io_cmd(struct ublk_io *io, struct request *req,
 				 int res, unsigned issue_flags)
 {