[PATCH 1/2] cifs: smbd: Merge code to track pending packets

[PATCH 1/2] cifs: smbd: Merge code to track pending packets

[longli]

From: Long Li <longli@microsoft.com>

As an optimization, SMBD tries to track two types of packets: packets with
payload and without payload. There is no obvious benefit or performance gain
to separately track two types of packets.

Just treat them as pending packets and merge the tracking code.

Signed-off-by: Long Li <longli@microsoft.com>
---
 fs/cifs/cifs_debug.c |  6 ++----
 fs/cifs/smbdirect.c  | 40 ++++++++++------------------------------
 fs/cifs/smbdirect.h  |  5 -----
 3 files changed, 12 insertions(+), 39 deletions(-)

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index 276e4b5ea8e0..916567d770f5 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -323,10 +323,8 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 			atomic_read(&server->smbd_conn->send_credits),
 			atomic_read(&server->smbd_conn->receive_credits),
 			server->smbd_conn->receive_credit_target);
-		seq_printf(m, "\nPending send_pending: %x "
-			"send_payload_pending: %x",
-			atomic_read(&server->smbd_conn->send_pending),
-			atomic_read(&server->smbd_conn->send_payload_pending));
+		seq_printf(m, "\nPending send_pending: %x ",
+			atomic_read(&server->smbd_conn->send_pending));
 		seq_printf(m, "\nReceive buffers count_receive_queue: %x "
 			"count_empty_packet_queue: %x",
 			server->smbd_conn->count_receive_queue,
diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
index 8da43a500686..79d8dcbd0034 100644
--- a/fs/cifs/smbdirect.c
+++ b/fs/cifs/smbdirect.c
@@ -284,13 +284,9 @@ static void send_done(struct ib_cq *cq, struct ib_wc *wc)
 			request->sge[i].length,
 			DMA_TO_DEVICE);
 
-	if (request->has_payload) {
-		if (atomic_dec_and_test(&request->info->send_payload_pending))
-			wake_up(&request->info->wait_send_payload_pending);
-	} else {
-		if (atomic_dec_and_test(&request->info->send_pending))
-			wake_up(&request->info->wait_send_pending);
-	}
+	if (atomic_dec_and_test(&request->info->send_pending))
+		wake_up(&request->info->wait_send_pending);
+
 
 	mempool_free(request, request->info->request_mempool);
 }
@@ -749,7 +745,6 @@ static int smbd_post_send_negotiate_req(struct smbd_connection *info)
 		request->sge[0].addr,
 		request->sge[0].length, request->sge[0].lkey);
 
-	request->has_payload = false;
 	atomic_inc(&info->send_pending);
 	rc = ib_post_send(info->id->qp, &send_wr, NULL);
 	if (!rc)
@@ -919,7 +914,7 @@ static void smbd_destroy_header(struct smbd_connection *info,
 
 /* Post the send request */
 static int smbd_post_send(struct smbd_connection *info,
-		struct smbd_request *request, bool has_payload)
+		struct smbd_request *request)
 {
 	struct ib_send_wr send_wr;
 	int rc, i;
@@ -944,24 +939,13 @@ static int smbd_post_send(struct smbd_connection *info,
 	send_wr.opcode = IB_WR_SEND;
 	send_wr.send_flags = IB_SEND_SIGNALED;
 
-	if (has_payload) {
-		request->has_payload = true;
-		atomic_inc(&info->send_payload_pending);
-	} else {
-		request->has_payload = false;
-		atomic_inc(&info->send_pending);
-	}
+	atomic_inc(&info->send_pending);
 
 	rc = ib_post_send(info->id->qp, &send_wr, NULL);
 	if (rc) {
 		log_rdma_send(ERR, "ib_post_send failed rc=%d\n", rc);
-		if (has_payload) {
-			if (atomic_dec_and_test(&info->send_payload_pending))
-				wake_up(&info->wait_send_payload_pending);
-		} else {
-			if (atomic_dec_and_test(&info->send_pending))
-				wake_up(&info->wait_send_pending);
-		}
+		if (atomic_dec_and_test(&info->send_pending))
+			wake_up(&info->wait_send_pending);
 		smbd_disconnect_rdma_connection(info);
 		rc = -EAGAIN;
 	} else
@@ -1001,7 +985,7 @@ static int smbd_post_send_sgl(struct smbd_connection *info,
 		request->num_sge++;
 	}
 
-	rc = smbd_post_send(info, request, data_length);
+	rc = smbd_post_send(info, request);
 	if (!rc)
 		return 0;
 
@@ -1413,8 +1397,6 @@ void smbd_destroy(struct TCP_Server_Info *server)
 	log_rdma_event(INFO, "wait for all send posted to IB to finish\n");
 	wait_event(info->wait_send_pending,
 		atomic_read(&info->send_pending) == 0);
-	wait_event(info->wait_send_payload_pending,
-		atomic_read(&info->send_payload_pending) == 0);
 
 	/* It's not posssible for upper layer to get to reassembly */
 	log_rdma_event(INFO, "drain the reassembly queue\n");
@@ -1751,8 +1733,6 @@ static struct smbd_connection *_smbd_get_connection(
 	init_waitqueue_head(&info->wait_send_pending);
 	atomic_set(&info->send_pending, 0);
 
-	init_waitqueue_head(&info->wait_send_payload_pending);
-	atomic_set(&info->send_payload_pending, 0);
 
 	INIT_WORK(&info->disconnect_work, smbd_disconnect_rdma_work);
 	INIT_WORK(&info->post_send_credits_work, smbd_post_send_credits);
@@ -2226,8 +2206,8 @@ int smbd_send(struct TCP_Server_Info *server,
 	 * that means all the I/Os have been out and we are good to return
 	 */
 
-	wait_event(info->wait_send_payload_pending,
-		atomic_read(&info->send_payload_pending) == 0);
+	wait_event(info->wait_send_pending,
+		atomic_read(&info->send_pending) == 0);
 
 	return rc;
 }
diff --git a/fs/cifs/smbdirect.h b/fs/cifs/smbdirect.h
index 8ede915f2b24..f70c7119a456 100644
--- a/fs/cifs/smbdirect.h
+++ b/fs/cifs/smbdirect.h
@@ -114,8 +114,6 @@ struct smbd_connection {
 	/* Activity accoutning */
 	atomic_t send_pending;
 	wait_queue_head_t wait_send_pending;
-	atomic_t send_payload_pending;
-	wait_queue_head_t wait_send_payload_pending;
 
 	/* Receive queue */
 	struct list_head receive_queue;
@@ -234,9 +232,6 @@ struct smbd_request {
 	struct smbd_connection *info;
 	struct ib_cqe cqe;
 
-	/* true if this request carries upper layer payload */
-	bool has_payload;
-
 	/* the SGE entries for this packet */
 	struct ib_sge sge[SMBDIRECT_MAX_SGE];
 	int num_sge;
-- 
2.17.1

[PATCH 2/2] cifs: smbd: Check send queue size before posting a send

[longli]

From: Long Li <longli@microsoft.com>

Sometimes the remote peer may return more send credits than the send queue
depth. If all the send credits are used to post senasd, we may overflow the
send queue.

Fix this by checking the send queue size before posting a send.

Signed-off-by: Long Li <longli@microsoft.com>
---
 fs/cifs/smbdirect.c | 11 ++++++++++-
 fs/cifs/smbdirect.h |  1 +
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
index 79d8dcbd0034..c7ef2d7ce0ef 100644
--- a/fs/cifs/smbdirect.c
+++ b/fs/cifs/smbdirect.c
@@ -287,6 +287,7 @@ static void send_done(struct ib_cq *cq, struct ib_wc *wc)
 	if (atomic_dec_and_test(&request->info->send_pending))
 		wake_up(&request->info->wait_send_pending);
 
+	wake_up(&request->info->wait_post_send);
 
 	mempool_free(request, request->info->request_mempool);
 }
@@ -939,7 +940,14 @@ static int smbd_post_send(struct smbd_connection *info,
 	send_wr.opcode = IB_WR_SEND;
 	send_wr.send_flags = IB_SEND_SIGNALED;
 
-	atomic_inc(&info->send_pending);
+wait_sq:
+	wait_event(info->wait_post_send,
+		atomic_read(&info->send_pending) < info->send_credit_target);
+	if (unlikely(atomic_inc_return(&info->send_pending) >
+				info->send_credit_target)) {
+		atomic_dec(&info->send_pending);
+		goto wait_sq;
+	}
 
 	rc = ib_post_send(info->id->qp, &send_wr, NULL);
 	if (rc) {
@@ -1733,6 +1741,7 @@ static struct smbd_connection *_smbd_get_connection(
 	init_waitqueue_head(&info->wait_send_pending);
 	atomic_set(&info->send_pending, 0);
 
+	init_waitqueue_head(&info->wait_post_send);
 
 	INIT_WORK(&info->disconnect_work, smbd_disconnect_rdma_work);
 	INIT_WORK(&info->post_send_credits_work, smbd_post_send_credits);
diff --git a/fs/cifs/smbdirect.h b/fs/cifs/smbdirect.h
index f70c7119a456..07c8f5638c39 100644
--- a/fs/cifs/smbdirect.h
+++ b/fs/cifs/smbdirect.h
@@ -114,6 +114,7 @@ struct smbd_connection {
 	/* Activity accoutning */
 	atomic_t send_pending;
 	wait_queue_head_t wait_send_pending;
+	wait_queue_head_t wait_post_send;
 
 	/* Receive queue */
 	struct list_head receive_queue;
-- 
2.17.1