block/rnbd-clt: Does not request pdu to rtrs-clt

Previously the rnbd client requested the rtrs to allocate rnbd_iu
just after the rtrs_iu. So the rnbd client passes the size of
rnbd_iu for rtrs_clt_open() and rtrs creates an array of
rnbd_iu and rtrs_iu.

For IO handling, rnbd_iu exists after the request because we pass
the size of rnbd_iu when setting the tag-set. Therefore we do not
use the rnbd_iu allocated by rtrs for IO handling.
We only use the rnbd_iu allocated by rtrs when doing session
initialization. Almost all rnbd_iu allocated by rtrs are wasted.

By this patch the rnbd client does not request rnbd_iu allocation
to rtrs but allocate it for itself when doing session initialization.

Also remove unused rtrs_permit_to_pdu from rtrs.
Signed-off-by: Gioh Kim <gi-oh.kim@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/rnbd/rnbd-clt.c

@@ -349,12 +349,19 @@ static struct rnbd_iu *rnbd_get_iu(struct rnbd_clt_session *sess,
 	struct rnbd_iu *iu;
 	struct rtrs_permit *permit;
 
+	iu = kzalloc(sizeof(*iu), GFP_KERNEL);
+	if (!iu) {
+		return NULL;
+	}
+
 	permit = rnbd_get_permit(sess, con_type,
 				  wait ? RTRS_PERMIT_WAIT :
 				  RTRS_PERMIT_NOWAIT);
-	if (unlikely(!permit))
+	if (unlikely(!permit)) {
+		kfree(iu);
 		return NULL;
-	iu = rtrs_permit_to_pdu(permit);
+	}
+
 	iu->permit = permit;
 	/*
 	 * 1st reference is dropped after finishing sending a "user" message,
@@ -373,8 +380,10 @@ static struct rnbd_iu *rnbd_get_iu(struct rnbd_clt_session *sess,
 
 static void rnbd_put_iu(struct rnbd_clt_session *sess, struct rnbd_iu *iu)
 {
-	if (atomic_dec_and_test(&iu->refcount))
+	if (atomic_dec_and_test(&iu->refcount)) {
 		rnbd_put_permit(sess, iu->permit);
+		kfree(iu);
+	}
 }
 
 static void rnbd_softirq_done_fn(struct request *rq)
@@ -1218,7 +1227,7 @@ find_and_get_or_create_sess(const char *sessname,
 	 */
 	sess->rtrs = rtrs_clt_open(&rtrs_ops, sessname,
 				   paths, path_cnt, port_nr,
-				   sizeof(struct rnbd_iu),
+				   0, /* Do not use pdu of rtrs */
 				   RECONNECT_DELAY, BMAX_SEGMENTS,
 				   BLK_MAX_SEGMENT_SIZE,
 				   MAX_RECONNECTS);

drivers/infiniband/ulp/rtrs/rtrs-clt.c

@@ -157,12 +157,6 @@ void rtrs_clt_put_permit(struct rtrs_clt *clt, struct rtrs_permit *permit)
 }
 EXPORT_SYMBOL(rtrs_clt_put_permit);
 
-void *rtrs_permit_to_pdu(struct rtrs_permit *permit)
-{
-	return permit + 1;
-}
-EXPORT_SYMBOL(rtrs_permit_to_pdu);
-
 /**
  * rtrs_permit_to_clt_con() - returns RDMA connection pointer by the permit
  * @sess: client session pointer

drivers/infiniband/ulp/rtrs/rtrs.h

@@ -63,13 +63,6 @@ struct rtrs_clt *rtrs_clt_open(struct rtrs_clt_ops *ops,
 
 void rtrs_clt_close(struct rtrs_clt *sess);
 
-/**
- * rtrs_permit_to_pdu() - converts rtrs_permit to opaque pdu pointer
- * @permit: RTRS permit pointer, it associates the memory allocation for future
- *          RDMA operation.
- */
-void *rtrs_permit_to_pdu(struct rtrs_permit *permit);
-
 enum {
 	RTRS_PERMIT_NOWAIT = 0,
 	RTRS_PERMIT_WAIT   = 1,