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Subject[[PATCH v1] 11/37] [CIFS] SMBD: Post a receive request
Date
From: Long Li <longli@microsoft.com>

Add code to post a receive request to RDMA. Before the SMB server can send a packet to SMB client via SMBD, a receive request must be posted to local RDMA layer.

Signed-off-by: Long Li <longli@microsoft.com>
---
fs/cifs/cifsrdma.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/cifs/cifsrdma.h | 5 +++
2 files changed, 129 insertions(+)

diff --git a/fs/cifs/cifsrdma.c b/fs/cifs/cifsrdma.c
index 8aa8a47..20237b7 100644
--- a/fs/cifs/cifsrdma.c
+++ b/fs/cifs/cifsrdma.c
@@ -62,6 +62,10 @@ static void put_receive_buffer(
static int allocate_receive_buffers(struct cifs_rdma_info *info, int num_buf);
static void destroy_receive_buffers(struct cifs_rdma_info *info);

+static int cifs_rdma_post_recv(
+ struct cifs_rdma_info *info,
+ struct cifs_rdma_response *response);
+
/*
* Per RDMA transport connection parameters
* as defined in [MS-SMBD] 3.1.1.1
@@ -193,6 +197,85 @@ cifs_rdma_qp_async_error_upcall(struct ib_event *event, void *context)
}
}

+/* Called from softirq, when recv is done */
+static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
+{
+ struct smbd_data_transfer *data_transfer;
+ struct cifs_rdma_response *response =
+ container_of(wc->wr_cqe, struct cifs_rdma_response, cqe);
+ struct cifs_rdma_info *info = response->info;
+
+ log_rdma_recv("response=%p type=%d wc status=%d wc opcode %d "
+ "byte_len=%d pkey_index=%x\n",
+ response, response->type, wc->status, wc->opcode,
+ wc->byte_len, wc->pkey_index);
+
+ if (wc->status != IB_WC_SUCCESS || wc->opcode != IB_WC_RECV) {
+ log_rdma_recv("wc->status=%d opcode=%d\n",
+ wc->status, wc->opcode);
+ goto error;
+ }
+
+ ib_dma_sync_single_for_cpu(
+ wc->qp->device,
+ response->sge.addr,
+ response->sge.length,
+ DMA_FROM_DEVICE);
+
+ switch(response->type) {
+ case SMBD_TRANSFER_DATA:
+ data_transfer = (struct smbd_data_transfer *) response->packet;
+ atomic_dec(&info->receive_credits);
+ atomic_set(&info->receive_credit_target,
+ le16_to_cpu(data_transfer->credits_requested));
+ atomic_add(le16_to_cpu(data_transfer->credits_granted),
+ &info->send_credits);
+
+ log_incoming("data flags %d data_offset %d data_length %d "
+ "remaining_data_length %d\n",
+ le16_to_cpu(data_transfer->flags),
+ le32_to_cpu(data_transfer->data_offset),
+ le32_to_cpu(data_transfer->data_length),
+ le32_to_cpu(data_transfer->remaining_data_length));
+
+ log_transport_credit(info);
+
+ // process sending queue on new credits
+ if (atomic_read(&info->send_credits))
+ wake_up(&info->wait_send_queue);
+
+ // process receive queue
+ if (le32_to_cpu(data_transfer->data_length)) {
+ if (info->full_packet_received) {
+ response->first_segment = true;
+ }
+
+ if (le32_to_cpu(data_transfer->remaining_data_length))
+ info->full_packet_received = false;
+ else
+ info->full_packet_received = true;
+
+ goto queue_done;
+ }
+
+ // if we reach here, this is an empty packet, finish it
+ break;
+
+ default:
+ log_rdma_recv("unexpected response type=%d\n", response->type);
+ }
+
+error:
+ put_receive_buffer(info, response);
+
+queue_done:
+ if (atomic_dec_and_test(&info->recv_pending)) {
+ wake_up(&info->wait_recv_pending);
+ }
+
+ return;
+}
+
static struct rdma_cm_id* cifs_rdma_create_id(
struct cifs_rdma_info *info, struct sockaddr *dstaddr)
{
@@ -289,6 +372,44 @@ static int cifs_rdma_ia_open(
}

/*
+ * Post a receive request to the transport
+ * The remote peer can only send data when a receive is posted
+ * The interaction is controlled by send/recieve credit system
+ */
+static int cifs_rdma_post_recv(struct cifs_rdma_info *info, struct cifs_rdma_response *response)
+{
+ struct ib_recv_wr recv_wr, *recv_wr_fail=NULL;
+ int rc = -EIO;
+
+ response->sge.addr = ib_dma_map_single(info->id->device, response->packet,
+ info->max_receive_size, DMA_FROM_DEVICE);
+ if (ib_dma_mapping_error(info->id->device, response->sge.addr))
+ return rc;
+
+ response->sge.length = info->max_receive_size;
+ response->sge.lkey = info->pd->local_dma_lkey;
+
+ response->cqe.done = recv_done;
+
+ recv_wr.wr_cqe = &response->cqe;
+ recv_wr.next = NULL;
+ recv_wr.sg_list = &response->sge;
+ recv_wr.num_sge = 1;
+
+ atomic_inc(&info->recv_pending);
+ rc = ib_post_recv(info->id->qp, &recv_wr, &recv_wr_fail);
+ if (rc) {
+ ib_dma_unmap_single(info->id->device, response->sge.addr,
+ response->sge.length, DMA_FROM_DEVICE);
+
+ log_rdma_recv("ib_post_recv failed rc=%d\n", rc);
+ atomic_dec(&info->recv_pending);
+ }
+
+ return rc;
+}
+
+/*
* Receive buffer operations.
* For each remote send, we need to post a receive. The receive buffers are
* pre-allocated in advance.
@@ -485,6 +606,9 @@ struct cifs_rdma_info* cifs_create_rdma_session(

allocate_receive_buffers(info, info->receive_credit_max);
init_waitqueue_head(&info->wait_send_queue);
+
+ init_waitqueue_head(&info->wait_recv_pending);
+ atomic_set(&info->recv_pending, 0);
out2:
rdma_destroy_id(info->id);

diff --git a/fs/cifs/cifsrdma.h b/fs/cifs/cifsrdma.h
index 287b5b1..8702a2b 100644
--- a/fs/cifs/cifsrdma.h
+++ b/fs/cifs/cifsrdma.h
@@ -59,6 +59,9 @@ struct cifs_rdma_info {
atomic_t receive_credits;
atomic_t receive_credit_target;

+ atomic_t recv_pending;
+ wait_queue_head_t wait_recv_pending;
+
struct list_head receive_queue;
spinlock_t receive_queue_lock;

@@ -68,6 +71,8 @@ struct cifs_rdma_info {
struct kmem_cache *request_cache;
mempool_t *request_mempool;

+ bool full_packet_received;
+
// response pool for RDMA receive
struct kmem_cache *response_cache;
mempool_t *response_mempool;
--
2.7.4
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