smb: server: remove separate empty_recvmsg_queue

There's no need to maintain two lists, we can just
have a single list of receive buffers, which are free to use.

Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Fixes: 0626e66 ("cifsd: add server handler for central processing and tranport layers")
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: metze-samba

fs/smb/server/transport_rdma.c

@@ -129,9 +129,6 @@ struct smb_direct_transport {
 	spinlock_t		recvmsg_queue_lock;
 	struct list_head	recvmsg_queue;
 
-	spinlock_t		empty_recvmsg_queue_lock;
-	struct list_head	empty_recvmsg_queue;
-
 	int			send_credit_target;
 	atomic_t		send_credits;
 	spinlock_t		lock_new_recv_credits;
@@ -276,32 +273,6 @@ static void put_recvmsg(struct smb_direct_transport *t,
 	spin_unlock(&t->recvmsg_queue_lock);
 }
 
-static struct
-smb_direct_recvmsg *get_empty_recvmsg(struct smb_direct_transport *t)
-{
-	struct smb_direct_recvmsg *recvmsg = NULL;
-
-	spin_lock(&t->empty_recvmsg_queue_lock);
-	if (!list_empty(&t->empty_recvmsg_queue)) {
-		recvmsg = list_first_entry(&t->empty_recvmsg_queue,
-					   struct smb_direct_recvmsg, list);
-		list_del(&recvmsg->list);
-	}
-	spin_unlock(&t->empty_recvmsg_queue_lock);
-	return recvmsg;
-}
-
-static void put_empty_recvmsg(struct smb_direct_transport *t,
-			      struct smb_direct_recvmsg *recvmsg)
-{
-	ib_dma_unmap_single(t->cm_id->device, recvmsg->sge.addr,
-			    recvmsg->sge.length, DMA_FROM_DEVICE);
-
-	spin_lock(&t->empty_recvmsg_queue_lock);
-	list_add_tail(&recvmsg->list, &t->empty_recvmsg_queue);
-	spin_unlock(&t->empty_recvmsg_queue_lock);
-}
-
 static void enqueue_reassembly(struct smb_direct_transport *t,
 			       struct smb_direct_recvmsg *recvmsg,
 			       int data_length)
@@ -386,9 +357,6 @@ static struct smb_direct_transport *alloc_transport(struct rdma_cm_id *cm_id)
 	spin_lock_init(&t->recvmsg_queue_lock);
 	INIT_LIST_HEAD(&t->recvmsg_queue);
 
-	spin_lock_init(&t->empty_recvmsg_queue_lock);
-	INIT_LIST_HEAD(&t->empty_recvmsg_queue);
-
 	init_waitqueue_head(&t->wait_send_pending);
 	atomic_set(&t->send_pending, 0);
 
@@ -554,7 +522,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 			       wc->opcode);
 			smb_direct_disconnect_rdma_connection(t);
 		}
-		put_empty_recvmsg(t, recvmsg);
+		put_recvmsg(t, recvmsg);
 		return;
 	}
 
@@ -568,7 +536,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 	switch (recvmsg->type) {
 	case SMB_DIRECT_MSG_NEGOTIATE_REQ:
 		if (wc->byte_len < sizeof(struct smb_direct_negotiate_req)) {
-			put_empty_recvmsg(t, recvmsg);
+			put_recvmsg(t, recvmsg);
 			return;
 		}
 		t->negotiation_requested = true;
@@ -585,15 +553,15 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 
 		if (wc->byte_len <
 		    offsetof(struct smb_direct_data_transfer, padding)) {
-			put_empty_recvmsg(t, recvmsg);
+			put_recvmsg(t, recvmsg);
 			return;
 		}
 
 		data_length = le32_to_cpu(data_transfer->data_length);
 		if (data_length) {
 			if (wc->byte_len < sizeof(struct smb_direct_data_transfer) +
 			    (u64)data_length) {
-				put_empty_recvmsg(t, recvmsg);
+				put_recvmsg(t, recvmsg);
 				return;
 			}
 
@@ -613,7 +581,7 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 			avail_recvmsg_count = t->count_avail_recvmsg;
 			spin_unlock(&t->receive_credit_lock);
 		} else {
-			put_empty_recvmsg(t, recvmsg);
+			put_recvmsg(t, recvmsg);
 
 			spin_lock(&t->receive_credit_lock);
 			receive_credits = --(t->recv_credits);
@@ -811,26 +779,16 @@ static void smb_direct_post_recv_credits(struct work_struct *work)
 	struct smb_direct_recvmsg *recvmsg;
 	int receive_credits, credits = 0;
 	int ret;
-	int use_free = 1;
 
 	spin_lock(&t->receive_credit_lock);
 	receive_credits = t->recv_credits;
 	spin_unlock(&t->receive_credit_lock);
 
 	if (receive_credits < t->recv_credit_target) {
 		while (true) {
-			if (use_free)
-				recvmsg = get_free_recvmsg(t);
-			else
-				recvmsg = get_empty_recvmsg(t);
-			if (!recvmsg) {
-				if (use_free) {
-					use_free = 0;
-					continue;
-				} else {
-					break;
-				}
-			}
+			recvmsg = get_free_recvmsg(t);
+			if (!recvmsg)
+				break;
 
 			recvmsg->type = SMB_DIRECT_MSG_DATA_TRANSFER;
 			recvmsg->first_segment = false;
@@ -1806,8 +1764,6 @@ static void smb_direct_destroy_pools(struct smb_direct_transport *t)
 
 	while ((recvmsg = get_free_recvmsg(t)))
 		mempool_free(recvmsg, t->recvmsg_mempool);
-	while ((recvmsg = get_empty_recvmsg(t)))
-		mempool_free(recvmsg, t->recvmsg_mempool);
 
 	mempool_destroy(t->recvmsg_mempool);
 	t->recvmsg_mempool = NULL;