[v4,02/22] CIFS: SMBD: Establish SMBDirect connection

Message ID 20171002023030.3582-3-longli@exchange.microsoft.com
State New
Headers show
Series
  • CIFS: Implement SMBDirect
Related show

Commit Message

Long Li Oct. 2, 2017, 2:30 a.m.
From: Long Li <longli@microsoft.com>

Add code to implement the core functions to establish a SMBDirect connection.

1. Establish an RDMA connection to SMB server.
2. Negotiate and setup SMBDirect protocol.
3. Implement idle connection timer and credit management.

Add to Makefile.

Signed-off-by: Long Li <longli@microsoft.com>
---
 fs/cifs/Makefile    |    2 +-
 fs/cifs/smbdirect.c | 1600 +++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/cifs/smbdirect.h |  229 ++++++++
 3 files changed, 1830 insertions(+), 1 deletion(-)

Comments

kbuild test robot Oct. 4, 2017, 11:01 a.m. | #1
Hi Long,

[auto build test ERROR on cifs/for-next]
[also build test ERROR on v4.14-rc3 next-20170929]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Long-Li/CIFS-Implement-SMBDirect/20171004-165915
base:   git://git.samba.org/sfrench/cifs-2.6.git for-next
config: ia64-defconfig (attached as .config)
compiler: ia64-linux-gcc (GCC) 6.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=ia64 

All errors (new ones prefixed by >>):

>> fs//cifs/smbdirect.c:19:21: fatal error: asm/msr.h: No such file or directory
    #include <asm/msr.h>
                        ^
   compilation terminated.

vim +19 fs//cifs/smbdirect.c

  > 19	#include <asm/msr.h>
    20	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Patch

diff --git a/fs/cifs/Makefile b/fs/cifs/Makefile
index 5e853a3..bb54662b 100644
--- a/fs/cifs/Makefile
+++ b/fs/cifs/Makefile
@@ -8,7 +8,7 @@  cifs-y := cifsfs.o cifssmb.o cifs_debug.o connect.o dir.o file.o inode.o \
 	  cifs_unicode.o nterr.o cifsencrypt.o \
 	  readdir.o ioctl.o sess.o export.o smb1ops.o winucase.o \
 	  smb2ops.o smb2maperror.o smb2transport.o \
-	  smb2misc.o smb2pdu.o smb2inode.o smb2file.o
+	  smb2misc.o smb2pdu.o smb2inode.o smb2file.o smbdirect.o
 
 cifs-$(CONFIG_CIFS_XATTR) += xattr.o
 cifs-$(CONFIG_CIFS_ACL) += cifsacl.o
diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
index d3c16f8..e8f976f 100644
--- a/fs/cifs/smbdirect.c
+++ b/fs/cifs/smbdirect.c
@@ -13,7 +13,35 @@ 
  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  *   the GNU General Public License for more details.
  */
+#include <linux/module.h>
 #include "smbdirect.h"
+#include "cifs_debug.h"
+#include <asm/msr.h>
+
+static struct smbd_response *get_empty_queue_buffer(
+		struct smbd_connection *info);
+static struct smbd_response *get_receive_buffer(
+		struct smbd_connection *info);
+static void put_receive_buffer(
+		struct smbd_connection *info,
+		struct smbd_response *response,
+		bool lock);
+static int allocate_receive_buffers(struct smbd_connection *info, int num_buf);
+static void destroy_receive_buffers(struct smbd_connection *info);
+
+static void put_empty_packet(
+		struct smbd_connection *info, struct smbd_response *response);
+static void enqueue_reassembly(
+		struct smbd_connection *info,
+		struct smbd_response *response, int data_length);
+static struct smbd_response *_get_first_reassembly(
+		struct smbd_connection *info);
+
+static int smbd_post_recv(
+		struct smbd_connection *info,
+		struct smbd_response *response);
+
+static int smbd_post_send_empty(struct smbd_connection *info);
 
 /* SMBD version number */
 #define SMBD_V1	0x0100
@@ -75,3 +103,1575 @@  int smbd_max_frmr_depth = 2048;
 
 /* If payload is less than this byte, use RDMA send/recv not read/write */
 int rdma_readwrite_threshold = 4096;
+
+/* Transport logging functions
+ * Logging are defined as classes. They can be OR'ed to define the actual
+ * logging level via module parameter smbd_logging_class
+ * e.g. cifs.smbd_logging_class=0x500 will log all log_rdma_recv() and
+ * log_rdma_event()
+ */
+#define LOG_OUTGOING			0x1
+#define LOG_INCOMING			0x2
+#define LOG_READ			0x4
+#define LOG_WRITE			0x8
+#define LOG_RDMA_SEND			0x10
+#define LOG_RDMA_RECV			0x20
+#define LOG_KEEP_ALIVE			0x40
+#define LOG_RDMA_EVENT			0x80
+#define LOG_RDMA_MR			0x100
+static unsigned int smbd_logging_class = 0;
+module_param(smbd_logging_class, uint, 0644);
+MODULE_PARM_DESC(smbd_logging_class,
+	"Logging class for SMBD transport 0x0 to 0x100");
+
+#define ERR		0x0
+#define INFO		0x1
+static unsigned int smbd_logging_level = ERR;
+module_param(smbd_logging_level, uint, 0644);
+MODULE_PARM_DESC(smbd_logging_level,
+	"Logging level for SMBD transport, 0 (default): error, 1: info");
+
+#define log_rdma(level, class, fmt, args...)				\
+do {									\
+	if (level <= smbd_logging_level || class & smbd_logging_class)	\
+		cifs_dbg(VFS, "%s:%d " fmt, __func__, __LINE__, ##args);\
+} while (0)
+
+#define log_outgoing(level, fmt, args...) \
+		log_rdma(level, LOG_OUTGOING, fmt, ##args)
+#define log_incoming(level, fmt, args...) \
+		log_rdma(level, LOG_INCOMING, fmt, ##args)
+#define log_read(level, fmt, args...)	log_rdma(level, LOG_READ, fmt, ##args)
+#define log_write(level, fmt, args...)	log_rdma(level, LOG_WRITE, fmt, ##args)
+#define log_rdma_send(level, fmt, args...) \
+		log_rdma(level, LOG_RDMA_SEND, fmt, ##args)
+#define log_rdma_recv(level, fmt, args...) \
+		log_rdma(level, LOG_RDMA_RECV, fmt, ##args)
+#define log_keep_alive(level, fmt, args...) \
+		log_rdma(level, LOG_KEEP_ALIVE, fmt, ##args)
+#define log_rdma_event(level, fmt, args...) \
+		log_rdma(level, LOG_RDMA_EVENT, fmt, ##args)
+#define log_rdma_mr(level, fmt, args...) \
+		log_rdma(level, LOG_RDMA_MR, fmt, ##args)
+
+void profiling_display_histogram(
+	struct seq_file *m, unsigned long long array[])
+{
+	int i;
+	unsigned long long total = 0;
+
+	for (i = 0; i < SIZE_LONG_LONG; i++)
+		total += array[i];
+
+	for (i = 0; i < SIZE_LONG_LONG; i++)
+		if (array[i])
+			seq_printf(m, "%d:%llu ", i, array[i] * 10000 / total);
+}
+
+static inline void profiling_add_histogram(
+	unsigned long long value, unsigned long long array[])
+{
+	array[__builtin_clzll(value)]++;
+}
+
+/*
+ * Destroy the transport and related RDMA and memory resources
+ * Need to go through all the pending counters and make sure on one is using
+ * the transport while it is destroyed
+ */
+static void smbd_destroy_rdma_work(struct work_struct *work)
+{
+	struct smbd_response *response;
+	struct smbd_connection *info =
+		container_of(work, struct smbd_connection, destroy_work);
+	unsigned long flags;
+
+	log_rdma_event(INFO, "destroying qp\n");
+	ib_drain_qp(info->id->qp);
+	rdma_destroy_qp(info->id);
+
+	/* Unblock all I/O waiting on the send queue */
+	wake_up_interruptible_all(&info->wait_send_queue);
+
+	log_rdma_event(INFO, "cancelling idle timer\n");
+	cancel_delayed_work_sync(&info->idle_timer_work);
+	log_rdma_event(INFO, "cancelling send immediate work\n");
+	cancel_delayed_work_sync(&info->send_immediate_work);
+
+	log_rdma_event(INFO, "wait for all recv to finish\n");
+	wake_up_interruptible(&info->wait_reassembly_queue);
+
+	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");
+	do {
+		spin_lock_irqsave(&info->reassembly_queue_lock, flags);
+		response = _get_first_reassembly(info);
+		if (response) {
+			list_del(&response->list);
+			spin_unlock_irqrestore(
+				&info->reassembly_queue_lock, flags);
+			put_receive_buffer(info, response, true);
+		}
+	} while (response);
+	spin_unlock_irqrestore(&info->reassembly_queue_lock, flags);
+	info->reassembly_data_length = 0;
+
+	log_rdma_event(INFO, "free receive buffers\n");
+	wait_event(info->wait_receive_queues,
+		info->count_receive_queue + info->count_empty_packet_queue
+			== info->receive_credit_max);
+	destroy_receive_buffers(info);
+
+	ib_free_cq(info->send_cq);
+	ib_free_cq(info->recv_cq);
+	ib_dealloc_pd(info->pd);
+	rdma_destroy_id(info->id);
+
+	/* free mempools */
+	mempool_destroy(info->request_mempool);
+	kmem_cache_destroy(info->request_cache);
+
+	mempool_destroy(info->response_mempool);
+	kmem_cache_destroy(info->response_cache);
+
+	info->transport_status = SMBD_DESTROYED;
+	wake_up_all(&info->wait_destroy);
+}
+
+static int smbd_process_disconnected(struct smbd_connection *info)
+{
+//	queue_work(info->workqueue, &info->destroy_work);
+	schedule_work(&info->destroy_work);
+	return 0;
+}
+
+static void smbd_disconnect_rdma_work(struct work_struct *work)
+{
+	struct smbd_connection *info =
+		container_of(work, struct smbd_connection, disconnect_work);
+
+	if (info->transport_status == SMBD_CONNECTED) {
+		info->transport_status = SMBD_DISCONNECTING;
+		rdma_disconnect(info->id);
+	}
+}
+
+static void smbd_disconnect_rdma_connection(struct smbd_connection *info)
+{
+	queue_work(info->workqueue, &info->disconnect_work);
+}
+
+/* Upcall from RDMA CM */
+static int smbd_conn_upcall(
+		struct rdma_cm_id *id, struct rdma_cm_event *event)
+{
+	struct smbd_connection *info = id->context;
+
+	log_rdma_event(INFO, "event=%d status=%d\n",
+		event->event, event->status);
+
+	switch (event->event) {
+	case RDMA_CM_EVENT_ADDR_RESOLVED:
+	case RDMA_CM_EVENT_ROUTE_RESOLVED:
+		info->ri_rc = 0;
+		complete(&info->ri_done);
+		break;
+
+	case RDMA_CM_EVENT_ADDR_ERROR:
+		info->ri_rc = -EHOSTUNREACH;
+		complete(&info->ri_done);
+		break;
+
+	case RDMA_CM_EVENT_ROUTE_ERROR:
+		info->ri_rc = -ENETUNREACH;
+		complete(&info->ri_done);
+		break;
+
+	case RDMA_CM_EVENT_ESTABLISHED:
+		log_rdma_event(INFO, "connected event=%d\n", event->event);
+		info->transport_status = SMBD_CONNECTED;
+		wake_up_interruptible(&info->conn_wait);
+		break;
+
+	case RDMA_CM_EVENT_CONNECT_ERROR:
+	case RDMA_CM_EVENT_UNREACHABLE:
+	case RDMA_CM_EVENT_REJECTED:
+		log_rdma_event(INFO, "connecting failed event=%d\n", event->event);
+		info->transport_status = SMBD_DISCONNECTED;
+		wake_up_interruptible(&info->conn_wait);
+		break;
+
+	case RDMA_CM_EVENT_DEVICE_REMOVAL:
+	case RDMA_CM_EVENT_DISCONNECTED:
+		/* This happenes when we fail the negotiation */
+		if (info->transport_status == SMBD_NEGOTIATE_FAILED) {
+			info->transport_status = SMBD_DISCONNECTED;
+			wake_up(&info->conn_wait);
+			break;
+		}
+
+		info->transport_status = SMBD_DISCONNECTED;
+		smbd_process_disconnected(info);
+		break;
+
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+/* Upcall from RDMA QP */
+static void
+smbd_qp_async_error_upcall(struct ib_event *event, void *context)
+{
+	struct smbd_connection *info = context;
+
+	log_rdma_event(ERR, "%s on device %s info %p\n",
+		ib_event_msg(event->event), event->device->name, info);
+
+	switch (event->event) {
+	case IB_EVENT_CQ_ERR:
+	case IB_EVENT_QP_FATAL:
+		smbd_disconnect_rdma_connection(info);
+
+	default:
+		break;
+	}
+}
+
+static inline void *smbd_request_payload(struct smbd_request *request)
+{
+	return (void *)request->packet;
+}
+
+static inline void *smbd_response_payload(struct smbd_response *response)
+{
+	return (void *)response->packet;
+}
+
+/* Called when a RDMA send is done */
+static void send_done(struct ib_cq *cq, struct ib_wc *wc)
+{
+	int i;
+	struct smbd_request *request =
+		container_of(wc->wr_cqe, struct smbd_request, cqe);
+
+	log_rdma_send(INFO, "smbd_request %p completed wc->status=%d\n",
+		request, wc->status);
+
+	if (wc->status != IB_WC_SUCCESS || wc->opcode != IB_WC_SEND) {
+		log_rdma_send(ERR, "wc->status=%d wc->opcode=%d\n",
+			wc->status, wc->opcode);
+		smbd_disconnect_rdma_connection(request->info);
+	}
+
+	for (i = 0; i < request->num_sge; i++)
+		ib_dma_unmap_single(request->info->id->device,
+			request->sge[i].addr,
+			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);
+	}
+
+	mempool_free(request, request->info->request_mempool);
+}
+
+static void dump_smbd_negotiate_resp(struct smbd_negotiate_resp *resp)
+{
+	log_rdma_event(INFO, "resp message min_version %u max_version %u "
+		"negotiated_version %u credits_requested %u "
+		"credits_granted %u status %u max_readwrite_size %u "
+		"preferred_send_size %u max_receive_size %u "
+		"max_fragmented_size %u\n",
+		resp->min_version, resp->max_version, resp->negotiated_version,
+		resp->credits_requested, resp->credits_granted, resp->status,
+		resp->max_readwrite_size, resp->preferred_send_size,
+		resp->max_receive_size, resp->max_fragmented_size);
+}
+
+/*
+ * Process a negotiation response message, according to [MS-SMBD]3.1.5.7
+ * response, packet_length: the negotiation response message
+ * return value: true if negotiation is a success, false if failed
+ */
+static bool process_negotiation_response(
+		struct smbd_response *response, int packet_length)
+{
+	struct smbd_connection *info = response->info;
+	struct smbd_negotiate_resp *packet = smbd_response_payload(response);
+
+	if (packet_length < sizeof(struct smbd_negotiate_resp)) {
+		log_rdma_event(ERR,
+			"error: packet_length=%d\n", packet_length);
+		return false;
+	}
+
+	if (le16_to_cpu(packet->negotiated_version) != SMBD_V1) {
+		log_rdma_event(ERR, "error: negotiated_version=%x\n",
+			le16_to_cpu(packet->negotiated_version));
+		return false;
+	}
+	info->protocol = le16_to_cpu(packet->negotiated_version);
+
+	if (packet->credits_requested == 0) {
+		log_rdma_event(ERR, "error: credits_requested==0\n");
+		return false;
+	}
+	info->receive_credit_target = le16_to_cpu(packet->credits_requested);
+
+	if (packet->credits_granted == 0) {
+		log_rdma_event(ERR, "error: credits_granted==0\n");
+		return false;
+	}
+	atomic_set(&info->send_credits, le16_to_cpu(packet->credits_granted));
+
+	atomic_set(&info->receive_credits, 0);
+
+	if (le32_to_cpu(packet->preferred_send_size) > info->max_receive_size) {
+		log_rdma_event(ERR, "error: preferred_send_size=%d\n",
+			le32_to_cpu(packet->preferred_send_size));
+		return false;
+	}
+	info->max_receive_size = le32_to_cpu(packet->preferred_send_size);
+
+	if (le32_to_cpu(packet->max_receive_size) < SMBD_MIN_RECEIVE_SIZE) {
+		log_rdma_event(ERR, "error: max_receive_size=%d\n",
+			le32_to_cpu(packet->max_receive_size));
+		return false;
+	}
+	info->max_send_size = min_t(int, info->max_send_size,
+					le32_to_cpu(packet->max_receive_size));
+
+	if (le32_to_cpu(packet->max_fragmented_size) <
+			SMBD_MIN_FRAGMENTED_SIZE) {
+		log_rdma_event(ERR, "error: max_fragmented_size=%d\n",
+			le32_to_cpu(packet->max_fragmented_size));
+		return false;
+	}
+	info->max_fragmented_send_size =
+		le32_to_cpu(packet->max_fragmented_size);
+
+	return true;
+}
+
+/*
+ * Check and schedule to send an immediate packet
+ * This is used to extend credtis to remote peer to keep the transport busy
+ */
+static void check_and_send_immediate(struct smbd_connection *info)
+{
+	if (info->transport_status != SMBD_CONNECTED)
+		return;
+
+	info->send_immediate = true;
+
+	/*
+	 * Promptly send a packet if our peer is running low on receive
+	 * credits
+	 */
+	if (atomic_read(&info->receive_credits) <
+		info->receive_credit_target - 1)
+		queue_delayed_work(
+			info->workqueue, &info->send_immediate_work, 0);
+}
+
+static void smbd_post_send_credits(struct work_struct *work)
+{
+	int ret = 0;
+	int use_receive_queue = 1;
+	int rc;
+	struct smbd_response *response;
+	struct smbd_connection *info =
+		container_of(work, struct smbd_connection,
+			post_send_credits_work);
+
+	if (info->transport_status != SMBD_CONNECTED) {
+		wake_up(&info->wait_receive_queues);
+		return;
+	}
+
+	if (info->receive_credit_target >
+		atomic_read(&info->receive_credits)) {
+		while (true) {
+			if (use_receive_queue)
+				response = get_receive_buffer(info);
+			else
+				response = get_empty_queue_buffer(info);
+			if (!response) {
+				/* now switch to emtpy packet queue */
+				if (use_receive_queue) {
+					use_receive_queue = 0;
+					continue;
+				} else
+					break;
+			}
+
+			response->type = SMBD_TRANSFER_DATA;
+			response->first_segment = false;
+			rc = smbd_post_recv(info, response);
+			if (rc) {
+				log_rdma_recv(ERR,
+					"post_recv failed rc=%d\n", rc);
+				put_receive_buffer(info, response, true);
+				break;
+			}
+
+			ret++;
+		}
+	}
+
+	spin_lock(&info->lock_new_credits_offered);
+	info->new_credits_offered += ret;
+	spin_unlock(&info->lock_new_credits_offered);
+
+	atomic_add(ret, &info->receive_credits);
+
+	/* Check if we can post new receive and grant credits to peer */
+	check_and_send_immediate(info);
+}
+
+static void smbd_recv_done_work(struct work_struct *work)
+{
+	struct smbd_connection *info =
+		container_of(work, struct smbd_connection, recv_done_work);
+
+	/*
+	 * We may have new send credits granted from remote peer
+	 * If any sender is blcoked on lack of credets, unblock it
+	 */
+	if (atomic_read(&info->send_credits))
+		wake_up_interruptible(&info->wait_send_queue);
+
+	/*
+	 * Check if we need to send something to remote peer to
+	 * grant more credits or respond to KEEP_ALIVE packet
+	 */
+	check_and_send_immediate(info);
+}
+
+/* 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 smbd_response *response =
+		container_of(wc->wr_cqe, struct smbd_response, cqe);
+	struct smbd_connection *info = response->info;
+	unsigned long long t1 = rdtsc();
+	int data_length = 0;
+
+	log_rdma_recv(INFO, "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(INFO, "wc->status=%d opcode=%d\n",
+			wc->status, wc->opcode);
+		smbd_disconnect_rdma_connection(info);
+		goto error;
+	}
+
+	ib_dma_sync_single_for_cpu(
+		wc->qp->device,
+		response->sge.addr,
+		response->sge.length,
+		DMA_FROM_DEVICE);
+
+	switch (response->type) {
+	/* SMBD negotiation response */
+	case SMBD_NEGOTIATE_RESP:
+		dump_smbd_negotiate_resp(smbd_response_payload(response));
+		info->full_packet_received = true;
+		info->negotiate_done =
+			process_negotiation_response(response, wc->byte_len);
+		complete(&info->negotiate_completion);
+		break;
+
+	/* SMBD data transfer packet */
+	case SMBD_TRANSFER_DATA:
+		data_transfer = smbd_response_payload(response);
+		data_length = le32_to_cpu(data_transfer->data_length);
+
+		/*
+		 * If this is a packet with data playload place the data in
+		 * reassembly queue and wake up the reading thread
+		 */
+		if (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;
+
+			enqueue_reassembly(
+				info,
+				response,
+				data_length);
+		} else
+			put_empty_packet(info, response);
+
+		if (data_length) {
+			wake_up_interruptible(&info->wait_reassembly_queue);
+			profiling_add_histogram(rdtsc()-t1, info->recv_done_cycles);
+		}
+
+		atomic_dec(&info->receive_credits);
+		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(INFO, "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));
+
+		/* Send a KEEP_ALIVE response right away if requested */
+		info->keep_alive_requested = KEEP_ALIVE_NONE;
+		if (le16_to_cpu(data_transfer->flags) &
+				le16_to_cpu(SMB_DIRECT_RESPONSE_REQUESTED)) {
+			info->keep_alive_requested = KEEP_ALIVE_PENDING;
+		}
+
+		queue_work(info->workqueue, &info->recv_done_work);
+		return;
+
+	default:
+		log_rdma_recv(ERR,
+			"unexpected response type=%d\n", response->type);
+	}
+
+error:
+	put_receive_buffer(info, response, true);
+}
+
+static struct rdma_cm_id *smbd_create_id(
+		struct smbd_connection *info,
+		struct sockaddr *dstaddr, int port)
+{
+	struct rdma_cm_id *id;
+	int rc;
+	__be16 *sport;
+
+	id = rdma_create_id(&init_net, smbd_conn_upcall, info,
+		RDMA_PS_TCP, IB_QPT_RC);
+	if (IS_ERR(id)) {
+		rc = PTR_ERR(id);
+		log_rdma_event(ERR, "rdma_create_id() failed %i\n", rc);
+		return id;
+	}
+
+	if (dstaddr->sa_family == AF_INET6)
+		sport = &((struct sockaddr_in6 *)dstaddr)->sin6_port;
+	else
+		sport = &((struct sockaddr_in *)dstaddr)->sin_port;
+
+	*sport = htons(port);
+
+	init_completion(&info->ri_done);
+	info->ri_rc = -ETIMEDOUT;
+
+	rc = rdma_resolve_addr(id, NULL, (struct sockaddr *)dstaddr,
+		RDMA_RESOLVE_TIMEOUT);
+	if (rc) {
+		log_rdma_event(ERR, "rdma_resolve_addr() failed %i\n", rc);
+		goto out;
+	}
+	wait_for_completion_interruptible_timeout(
+		&info->ri_done, msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT));
+	rc = info->ri_rc;
+	if (rc) {
+		log_rdma_event(ERR, "rdma_resolve_addr() completed %i\n", rc);
+		goto out;
+	}
+
+	info->ri_rc = -ETIMEDOUT;
+	rc = rdma_resolve_route(id, RDMA_RESOLVE_TIMEOUT);
+	if (rc) {
+		log_rdma_event(ERR, "rdma_resolve_route() failed %i\n", rc);
+		goto out;
+	}
+	wait_for_completion_interruptible_timeout(
+		&info->ri_done, msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT));
+	rc = info->ri_rc;
+	if (rc) {
+		log_rdma_event(ERR, "rdma_resolve_route() completed %i\n", rc);
+		goto out;
+	}
+
+	return id;
+
+out:
+	rdma_destroy_id(id);
+	return ERR_PTR(rc);
+}
+
+/*
+ * Test if FRWR (Fast Registration Work Requests) is supported on the device
+ * This implementation requries FRWR on RDMA read/write
+ * return value: true if it is supported
+ */
+static bool frwr_is_supported(struct ib_device_attr *attrs)
+{
+	if (!(attrs->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS))
+		return false;
+	if (attrs->max_fast_reg_page_list_len == 0)
+		return false;
+	return true;
+}
+
+static int smbd_ia_open(
+		struct smbd_connection *info,
+		struct sockaddr *dstaddr, int port)
+{
+	int rc;
+
+	info->id = smbd_create_id(info, dstaddr, port);
+	if (IS_ERR(info->id)) {
+		rc = PTR_ERR(info->id);
+		goto out1;
+	}
+
+	if (!frwr_is_supported(&info->id->device->attrs)) {
+		log_rdma_event(ERR,
+			"Fast Registration Work Requests "
+			"(FRWR) is not supported\n");
+		log_rdma_event(ERR,
+			"Device capability flags = %llx "
+			"max_fast_reg_page_list_len = %u\n",
+			info->id->device->attrs.device_cap_flags,
+			info->id->device->attrs.max_fast_reg_page_list_len);
+		rc = -EPROTONOSUPPORT;
+		goto out2;
+	}
+
+	info->pd = ib_alloc_pd(info->id->device, 0);
+	if (IS_ERR(info->pd)) {
+		rc = PTR_ERR(info->pd);
+		log_rdma_event(ERR, "ib_alloc_pd() returned %d\n", rc);
+		goto out2;
+	}
+
+	return 0;
+
+out2:
+	rdma_destroy_id(info->id);
+	info->id = NULL;
+
+out1:
+	return rc;
+}
+
+/*
+ * Send a negotiation request message to the peer
+ * The negotiation procedure is in [MS-SMBD] 3.1.5.2 and 3.1.5.3
+ * After negotiation, the transport is connected and ready for
+ * carrying upper layer SMB payload
+ */
+static int smbd_post_send_negotiate_req(struct smbd_connection *info)
+{
+	struct ib_send_wr send_wr, *send_wr_fail;
+	int rc = -ENOMEM;
+	struct smbd_request *request;
+	struct smbd_negotiate_req *packet;
+
+	request = mempool_alloc(info->request_mempool, GFP_KERNEL);
+	if (!request)
+		return rc;
+
+	request->info = info;
+
+	packet = smbd_request_payload(request);
+	packet->min_version = cpu_to_le16(SMBD_V1);
+	packet->max_version = cpu_to_le16(SMBD_V1);
+	packet->reserved = 0;
+	packet->credits_requested = cpu_to_le16(info->send_credit_target);
+	packet->preferred_send_size = cpu_to_le32(info->max_send_size);
+	packet->max_receive_size = cpu_to_le32(info->max_receive_size);
+	packet->max_fragmented_size =
+		cpu_to_le32(info->max_fragmented_recv_size);
+
+	request->num_sge = 1;
+	request->sge[0].addr = ib_dma_map_single(
+				info->id->device, (void *)packet,
+				sizeof(*packet), DMA_TO_DEVICE);
+	if (ib_dma_mapping_error(info->id->device, request->sge[0].addr)) {
+		rc = -EIO;
+		goto dma_mapping_failed;
+	}
+
+	request->sge[0].length = sizeof(*packet);
+	request->sge[0].lkey = info->pd->local_dma_lkey;
+
+	ib_dma_sync_single_for_device(
+		info->id->device, request->sge[0].addr,
+		request->sge[0].length, DMA_TO_DEVICE);
+
+	request->cqe.done = send_done;
+
+	send_wr.next = NULL;
+	send_wr.wr_cqe = &request->cqe;
+	send_wr.sg_list = request->sge;
+	send_wr.num_sge = request->num_sge;
+	send_wr.opcode = IB_WR_SEND;
+	send_wr.send_flags = IB_SEND_SIGNALED;
+
+	log_rdma_send(INFO, "sge addr=%llx length=%x lkey=%x\n",
+		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, &send_wr_fail);
+	if (!rc)
+		return 0;
+
+	/* if we reach here, post send failed */
+	log_rdma_send(ERR, "ib_post_send failed rc=%d\n", rc);
+	atomic_dec(&info->send_pending);
+	ib_dma_unmap_single(info->id->device, request->sge[0].addr,
+		request->sge[0].length, DMA_TO_DEVICE);
+
+dma_mapping_failed:
+	mempool_free(request, info->request_mempool);
+	return rc;
+}
+
+/*
+ * Extend the credits to remote peer
+ * This implements [MS-SMBD] 3.1.5.9
+ * The idea is that we should extend credits to remote peer as quickly as
+ * it's allowed, to maintain data flow. We allocate as much receive
+ * buffer as possible, and extend the receive credits to remote peer
+ * return value: the new credtis being granted.
+ */
+static int manage_credits_prior_sending(struct smbd_connection *info)
+{
+	int new_credits;
+
+	spin_lock(&info->lock_new_credits_offered);
+	new_credits = info->new_credits_offered;
+	info->new_credits_offered = 0;
+	spin_unlock(&info->lock_new_credits_offered);
+
+	return new_credits;
+}
+
+/*
+ * Check if we need to send a KEEP_ALIVE message
+ * The idle connection timer triggers a KEEP_ALIVE message when expires
+ * SMB_DIRECT_RESPONSE_REQUESTED is set in the message flag to have peer send
+ * back a response.
+ * return value:
+ * 1 if SMB_DIRECT_RESPONSE_REQUESTED needs to be set
+ * 0: otherwise
+ */
+static int manage_keep_alive_before_sending(struct smbd_connection *info)
+{
+	if (info->keep_alive_requested == KEEP_ALIVE_PENDING) {
+		info->keep_alive_requested = KEEP_ALIVE_SENT;
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * Build and prepare the SMBD packet header
+ * This function waits for avaialbe send credits and build a SMBD packet
+ * header. The caller then optional append payload to the packet after
+ * the header
+ * intput values
+ * size: the size of the payload
+ * remaining_data_length: remaining data to send if this is part of a
+ * fragmented packet
+ * output values
+ * request_out: the request allocated from this function
+ * return values: 0 on success, otherwise actual error code returned
+ */
+static int smbd_create_header(struct smbd_connection *info,
+		int size, int remaining_data_length,
+		struct smbd_request **request_out)
+{
+	struct smbd_request *request;
+	struct smbd_data_transfer *packet;
+	int header_length;
+	int rc;
+
+	/* Wait for send credits. A SMBD packet needs one credit */
+	rc = wait_event_interruptible(info->wait_send_queue,
+		atomic_read(&info->send_credits) > 0 ||
+		info->transport_status != SMBD_CONNECTED);
+	if (rc)
+		return rc;
+
+	if (info->transport_status != SMBD_CONNECTED) {
+		log_outgoing(ERR, "disconnected not sending\n");
+		return -ENOENT;
+	}
+	atomic_dec(&info->send_credits);
+
+	request = mempool_alloc(info->request_mempool, GFP_KERNEL);
+	if (!request) {
+		rc = -ENOMEM;
+		goto err;
+	}
+
+	request->info = info;
+
+	/* Fill in the packet header */
+	packet = smbd_request_payload(request);
+	packet->credits_requested = cpu_to_le16(info->send_credit_target);
+	packet->credits_granted =
+		cpu_to_le16(manage_credits_prior_sending(info));
+	info->send_immediate = false;
+
+	packet->flags = 0;
+	if (manage_keep_alive_before_sending(info))
+		packet->flags |= cpu_to_le16(SMB_DIRECT_RESPONSE_REQUESTED);
+
+	packet->reserved = 0;
+	if (!size)
+		packet->data_offset = 0;
+	else
+		packet->data_offset = cpu_to_le32(24);
+	packet->data_length = cpu_to_le32(size);
+	packet->remaining_data_length = cpu_to_le32(remaining_data_length);
+	packet->padding = 0;
+
+	log_outgoing(INFO, "credits_requested=%d credits_granted=%d "
+		"data_offset=%d data_length=%d remaining_data_length=%d\n",
+		le16_to_cpu(packet->credits_requested),
+		le16_to_cpu(packet->credits_granted),
+		le32_to_cpu(packet->data_offset),
+		le32_to_cpu(packet->data_length),
+		le32_to_cpu(packet->remaining_data_length));
+
+	/* Map the packet to DMA */
+	header_length = sizeof(struct smbd_data_transfer);
+	/* If this is a packet without payload, don't send padding */
+	if (!size)
+		header_length = offsetof(struct smbd_data_transfer, padding);
+
+	request->num_sge = 1;
+	request->sge[0].addr = ib_dma_map_single(info->id->device,
+						 (void *)packet,
+						 header_length,
+						 DMA_BIDIRECTIONAL);
+	if (ib_dma_mapping_error(info->id->device, request->sge[0].addr)) {
+		mempool_free(request, info->request_mempool);
+		rc = -EIO;
+		goto err;
+	}
+
+	request->sge[0].length = header_length;
+	request->sge[0].lkey = info->pd->local_dma_lkey;
+
+	*request_out = request;
+	return 0;
+
+err:
+	atomic_inc(&info->send_credits);
+	return rc;
+}
+
+static void smbd_destroy_header(struct smbd_connection *info,
+		struct smbd_request *request)
+{
+
+	ib_dma_unmap_single(info->id->device,
+			    request->sge[0].addr,
+			    request->sge[0].length,
+			    DMA_TO_DEVICE);
+	mempool_free(request, info->request_mempool);
+	atomic_inc(&info->send_credits);
+}
+
+/* Post the send request */
+static int smbd_post_send(struct smbd_connection *info,
+		struct smbd_request *request, bool has_payload)
+{
+	struct ib_send_wr send_wr, *send_wr_fail;
+	int rc, i;
+
+	for (i = 0; i < request->num_sge; i++) {
+		log_rdma_send(INFO,
+			"rdma_request sge[%d] addr=%llu legnth=%u\n",
+			i, request->sge[0].addr, request->sge[0].length);
+		ib_dma_sync_single_for_device(
+			info->id->device,
+			request->sge[i].addr,
+			request->sge[i].length,
+			DMA_TO_DEVICE);
+	}
+
+	request->cqe.done = send_done;
+
+	send_wr.next = NULL;
+	send_wr.wr_cqe = &request->cqe;
+	send_wr.sg_list = request->sge;
+	send_wr.num_sge = request->num_sge;
+	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);
+	}
+
+	rc = ib_post_send(info->id->qp, &send_wr, &send_wr_fail);
+	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);
+		}
+	} else
+		/* Reset timer for idle connection after packet is sent */
+		mod_delayed_work(info->workqueue, &info->idle_timer_work,
+			info->keep_alive_interval*HZ);
+
+	return rc;
+}
+
+static int smbd_post_send_sgl(struct smbd_connection *info,
+	struct scatterlist *sgl, int data_length, int remaining_data_length)
+{
+	int num_sgs;
+	int i, rc;
+	struct smbd_request *request;
+	struct scatterlist *sg;
+
+	rc = smbd_create_header(
+		info, data_length, remaining_data_length, &request);
+	if (rc)
+		return rc;
+
+	num_sgs = sgl ? sg_nents(sgl) : 0;
+	for_each_sg(sgl, sg, num_sgs, i) {
+		request->sge[i+1].addr =
+			ib_dma_map_page(info->id->device, sg_page(sg),
+			       sg->offset, sg->length, DMA_BIDIRECTIONAL);
+		if (ib_dma_mapping_error(
+				info->id->device, request->sge[i+1].addr)) {
+			rc = -EIO;
+			request->sge[i+1].addr = 0;
+			goto dma_mapping_failure;
+		}
+		request->sge[i+1].length = sg->length;
+		request->sge[i+1].lkey = info->pd->local_dma_lkey;
+		request->num_sge++;
+	}
+
+	rc = smbd_post_send(info, request, data_length);
+	if (!rc)
+		return 0;
+
+dma_mapping_failure:
+	for (i = 1; i < request->num_sge; i++)
+		if (request->sge[i].addr)
+			ib_dma_unmap_single(info->id->device,
+					    request->sge[i].addr,
+					    request->sge[i].length,
+					    DMA_TO_DEVICE);
+	smbd_destroy_header(info, request);
+	return rc;
+}
+
+/*
+ * Send an empty message
+ * Empty message is used to extend credits to peer to for keep live
+ * while there is no upper layer payload to send at the time
+ */
+static int smbd_post_send_empty(struct smbd_connection *info)
+{
+	info->count_send_empty++;
+	return smbd_post_send_sgl(info, NULL, 0, 0);
+}
+
+/*
+ * Post a receive request to the transport
+ * The remote peer can only send data when a receive request is posted
+ * The interaction is controlled by send/receive credit system
+ */
+static int smbd_post_recv(
+		struct smbd_connection *info, struct smbd_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;
+
+	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(ERR, "ib_post_recv failed rc=%d\n", rc);
+	}
+
+	return rc;
+}
+
+/* Perform SMBD negotiate according to [MS-SMBD] 3.1.5.2 */
+static int smbd_negotiate(struct smbd_connection *info)
+{
+	int rc;
+	struct smbd_response *response = get_receive_buffer(info);
+
+	response->type = SMBD_NEGOTIATE_RESP;
+	rc = smbd_post_recv(info, response);
+	log_rdma_event(INFO,
+		"smbd_post_recv rc=%d iov.addr=%llx iov.length=%x "
+		"iov.lkey=%x\n",
+		rc, response->sge.addr,
+		response->sge.length, response->sge.lkey);
+	if (rc)
+		return rc;
+
+	init_completion(&info->negotiate_completion);
+	info->negotiate_done = false;
+	rc = smbd_post_send_negotiate_req(info);
+	if (rc)
+		return rc;
+
+	rc = wait_for_completion_interruptible_timeout(
+		&info->negotiate_completion, SMBD_NEGOTIATE_TIMEOUT * HZ);
+	log_rdma_event(INFO, "wait_for_completion_timeout rc=%d\n", rc);
+
+	if (info->negotiate_done)
+		return 0;
+
+	if (rc == 0)
+		rc = -ETIMEDOUT;
+	else if (rc == -ERESTARTSYS)
+		rc = -EINTR;
+	else
+		rc = -ENOTCONN;
+
+	return rc;
+}
+
+static void put_empty_packet(
+		struct smbd_connection *info, struct smbd_response *response)
+{
+	spin_lock(&info->empty_packet_queue_lock);
+	list_add_tail(&response->list, &info->empty_packet_queue);
+	info->count_empty_packet_queue++;
+	spin_unlock(&info->empty_packet_queue_lock);
+
+	queue_work(info->workqueue, &info->post_send_credits_work);
+}
+
+/*
+ * Implement Connection.FragmentReassemblyBuffer defined in [MS-SMBD] 3.1.1.1
+ * This is a queue for reassembling upper layer payload and present to upper
+ * layer. All the inncoming payload go to the reassembly queue, regardless of
+ * if reassembly is required. The uuper layer code reads from the queue for all
+ * incoming payloads.
+ * Put a received packet to the reassembly queue
+ * response: the packet received
+ * data_length: the size of payload in this packet
+ */
+static void enqueue_reassembly(
+	struct smbd_connection *info,
+	struct smbd_response *response,
+	int data_length)
+{
+	spin_lock(&info->reassembly_queue_lock);
+	list_add_tail(&response->list, &info->reassembly_queue);
+	info->reassembly_queue_length++;
+	/*
+	 * Make sure reassembly_data_length is updated after list and
+	 * reassembly_queue_length are updated. On the dequeue side
+	 * reassembly_data_length is checked without a lock to determine
+	 * if reassembly_queue_length and list is up to date
+	 */
+	virt_wmb();
+	info->reassembly_data_length += data_length;
+	spin_unlock(&info->reassembly_queue_lock);
+	info->count_reassembly_queue++;
+	info->count_enqueue_reassembly_queue++;
+}
+
+/*
+ * Get the first entry at the front of reassembly queue
+ * Caller is responsible for locking
+ * return value: the first entry if any, NULL if queue is empty
+ */
+static struct smbd_response *_get_first_reassembly(struct smbd_connection *info)
+{
+	struct smbd_response *ret = NULL;
+
+	if (!list_empty(&info->reassembly_queue)) {
+		ret = list_first_entry(
+			&info->reassembly_queue,
+			struct smbd_response, list);
+	}
+	return ret;
+}
+
+static struct smbd_response *get_empty_queue_buffer(
+		struct smbd_connection *info)
+{
+	struct smbd_response *ret = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&info->empty_packet_queue_lock, flags);
+	if (!list_empty(&info->empty_packet_queue)) {
+		ret = list_first_entry(
+			&info->empty_packet_queue,
+			struct smbd_response, list);
+		list_del(&ret->list);
+		info->count_empty_packet_queue--;
+	}
+	spin_unlock_irqrestore(&info->empty_packet_queue_lock, flags);
+
+	return ret;
+}
+
+/*
+ * Get a receive buffer
+ * For each remote send, we need to post a receive. The receive buffers are
+ * pre-allocated in advance.
+ * return value: the receive buffer, NULL if none is available
+ */
+static struct smbd_response *get_receive_buffer(struct smbd_connection *info)
+{
+	struct smbd_response *ret = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&info->receive_queue_lock, flags);
+	if (!list_empty(&info->receive_queue)) {
+		ret = list_first_entry(
+			&info->receive_queue,
+			struct smbd_response, list);
+		list_del(&ret->list);
+		info->count_receive_queue--;
+		info->count_get_receive_buffer++;
+	}
+	spin_unlock_irqrestore(&info->receive_queue_lock, flags);
+
+	return ret;
+}
+
+/*
+ * Return a receive buffer
+ * Upon returning of a receive buffer, we can post new receive and extend
+ * more receive credits to remote peer. This is done immediately after a
+ * receive buffer is returned.
+ */
+static void put_receive_buffer(
+	struct smbd_connection *info, struct smbd_response *response,
+	bool lock)
+{
+	unsigned long flags;
+
+	ib_dma_unmap_single(info->id->device, response->sge.addr,
+		response->sge.length, DMA_FROM_DEVICE);
+
+	if (lock)
+		spin_lock_irqsave(&info->receive_queue_lock, flags);
+	list_add_tail(&response->list, &info->receive_queue);
+	info->count_receive_queue++;
+	info->count_put_receive_buffer++;
+	if (lock)
+		spin_unlock_irqrestore(&info->receive_queue_lock, flags);
+
+	queue_work(info->workqueue, &info->post_send_credits_work);
+}
+
+/* Preallocate all receive buffer on transport establishment */
+static int allocate_receive_buffers(struct smbd_connection *info, int num_buf)
+{
+	int i;
+	struct smbd_response *response;
+
+	INIT_LIST_HEAD(&info->reassembly_queue);
+	spin_lock_init(&info->reassembly_queue_lock);
+	info->reassembly_data_length = 0;
+	info->reassembly_queue_length = 0;
+
+	INIT_LIST_HEAD(&info->receive_queue);
+	spin_lock_init(&info->receive_queue_lock);
+	info->count_receive_queue = 0;
+
+	INIT_LIST_HEAD(&info->empty_packet_queue);
+	spin_lock_init(&info->empty_packet_queue_lock);
+	info->count_empty_packet_queue = 0;
+
+	init_waitqueue_head(&info->wait_receive_queues);
+
+	for (i = 0; i < num_buf; i++) {
+		response = mempool_alloc(info->response_mempool, GFP_KERNEL);
+		if (!response)
+			goto allocate_failed;
+
+		response->info = info;
+		list_add_tail(&response->list, &info->receive_queue);
+		info->count_receive_queue++;
+	}
+
+	return 0;
+
+allocate_failed:
+	while (!list_empty(&info->receive_queue)) {
+		response = list_first_entry(
+				&info->receive_queue,
+				struct smbd_response, list);
+		list_del(&response->list);
+		info->count_receive_queue--;
+
+		mempool_free(response, info->response_mempool);
+	}
+	return -ENOMEM;
+}
+
+static void destroy_receive_buffers(struct smbd_connection *info)
+{
+	struct smbd_response *response;
+
+	while ((response = get_receive_buffer(info)))
+		mempool_free(response, info->response_mempool);
+
+	while ((response = get_empty_queue_buffer(info)))
+		mempool_free(response, info->response_mempool);
+}
+
+/*
+ * Check and send an immediate or keep alive packet
+ * The condition to send those packets are defined in [MS-SMBD] 3.1.1.1
+ * Connection.KeepaliveRequested and Connection.SendImmediate
+ * The idea is to extend credits to server as soon as it becomes available
+ */
+static void send_immediate_work(struct work_struct *work)
+{
+	struct smbd_connection *info = container_of(
+					work, struct smbd_connection,
+					send_immediate_work.work);
+
+	if (info->keep_alive_requested == KEEP_ALIVE_PENDING ||
+	    info->send_immediate) {
+		log_keep_alive(INFO, "send an empty message\n");
+		smbd_post_send_empty(info);
+	}
+}
+
+/* Implement idle connection timer [MS-SMBD] 3.1.6.2 */
+static void idle_connection_timer(struct work_struct *work)
+{
+	struct smbd_connection *info = container_of(
+					work, struct smbd_connection,
+					idle_timer_work.work);
+
+	if (info->keep_alive_requested != KEEP_ALIVE_NONE) {
+		log_keep_alive(ERR,
+			"error status info->keep_alive_requested=%d\n",
+			info->keep_alive_requested);
+		smbd_disconnect_rdma_connection(info);
+		return;
+	}
+
+	log_keep_alive(INFO, "about to send an empty idle message\n");
+	smbd_post_send_empty(info);
+
+	/* Setup the next idle timeout work */
+	queue_delayed_work(info->workqueue, &info->idle_timer_work,
+			info->keep_alive_interval*HZ);
+}
+
+static void destroy_caches_and_workqueue(struct smbd_connection *info)
+{
+	destroy_receive_buffers(info);
+	destroy_workqueue(info->workqueue);
+	mempool_destroy(info->response_mempool);
+	kmem_cache_destroy(info->response_cache);
+	mempool_destroy(info->request_mempool);
+	kmem_cache_destroy(info->request_cache);
+}
+
+#define MAX_NAME_LEN	80
+static int allocate_caches_and_workqueue(struct smbd_connection *info)
+{
+	char name[MAX_NAME_LEN];
+	int rc;
+
+	snprintf(name, MAX_NAME_LEN, "smbd_request_%p", info);
+	info->request_cache =
+		kmem_cache_create(
+			name,
+			sizeof(struct smbd_request) +
+				sizeof(struct smbd_data_transfer),
+			0, SLAB_HWCACHE_ALIGN, NULL);
+	if (!info->request_cache)
+		return -ENOMEM;
+
+	info->request_mempool =
+		mempool_create(info->send_credit_target, mempool_alloc_slab,
+			mempool_free_slab, info->request_cache);
+	if (!info->request_mempool)
+		goto out1;
+
+	snprintf(name, MAX_NAME_LEN, "smbd_response_%p", info);
+	info->response_cache =
+		kmem_cache_create(
+			name,
+			sizeof(struct smbd_response) +
+				info->max_receive_size,
+			0, SLAB_HWCACHE_ALIGN, NULL);
+	if (!info->response_cache)
+		goto out2;
+
+	info->response_mempool =
+		mempool_create(info->receive_credit_max, mempool_alloc_slab,
+		       mempool_free_slab, info->response_cache);
+	if (!info->response_mempool)
+		goto out3;
+
+	snprintf(name, MAX_NAME_LEN, "smbd_%p", info);
+	info->workqueue = create_workqueue(name);
+	if (!info->workqueue)
+		goto out4;
+
+	rc = allocate_receive_buffers(info, info->receive_credit_max);
+	if (rc) {
+		log_rdma_event(ERR, "failed to allocate receive buffers\n");
+		goto out5;
+	}
+
+	return 0;
+
+out5:
+	destroy_workqueue(info->workqueue);
+out4:
+	mempool_destroy(info->response_mempool);
+out3:
+	kmem_cache_destroy(info->response_cache);
+out2:
+	mempool_destroy(info->request_mempool);
+out1:
+	kmem_cache_destroy(info->request_cache);
+	return -ENOMEM;
+}
+
+/* Create a SMBD connection, called by upper layer */
+struct smbd_connection *_smbd_get_connection(
+	struct TCP_Server_Info *server, struct sockaddr *dstaddr, int port)
+{
+	int rc;
+	struct smbd_connection *info;
+	struct rdma_conn_param conn_param;
+	struct ib_qp_init_attr qp_attr;
+	struct sockaddr_in *addr_in = (struct sockaddr_in *) dstaddr;
+
+	info = kzalloc(sizeof(struct smbd_connection), GFP_KERNEL);
+	if (!info)
+		return NULL;
+
+	info->transport_status = SMBD_CONNECTING;
+	rc = smbd_ia_open(info, dstaddr, port);
+	if (rc) {
+		log_rdma_event(INFO, "smbd_ia_open rc=%d\n", rc);
+		goto create_id_failed;
+	}
+
+	if (smbd_send_credit_target > info->id->device->attrs.max_cqe ||
+	    smbd_send_credit_target > info->id->device->attrs.max_qp_wr) {
+		log_rdma_event(ERR,
+			"consider lowering send_credit_target = %d. "
+			"Possible CQE overrun, device "
+			"reporting max_cpe %d max_qp_wr %d\n",
+			smbd_send_credit_target,
+			info->id->device->attrs.max_cqe,
+			info->id->device->attrs.max_qp_wr);
+		goto config_failed;
+	}
+
+	if (smbd_receive_credit_max > info->id->device->attrs.max_cqe ||
+	    smbd_receive_credit_max > info->id->device->attrs.max_qp_wr) {
+		log_rdma_event(ERR,
+			"consider lowering receive_credit_max = %d. "
+			"Possible CQE overrun, device "
+			"reporting max_cpe %d max_qp_wr %d\n",
+			smbd_receive_credit_max,
+			info->id->device->attrs.max_cqe,
+			info->id->device->attrs.max_qp_wr);
+		goto config_failed;
+	}
+
+	info->receive_credit_max = smbd_receive_credit_max;
+	info->send_credit_target = smbd_send_credit_target;
+	info->max_send_size = smbd_max_send_size;
+	info->max_fragmented_recv_size = smbd_max_fragmented_recv_size;
+	info->max_receive_size = smbd_max_receive_size;
+	info->keep_alive_interval = smbd_keep_alive_interval;
+
+	if (SMBDIRECT_MAX_SGE > info->id->device->attrs.max_sge) {
+		log_rdma_event(ERR, "warning: device max_sge = %d too small\n",
+			info->id->device->attrs.max_sge);
+		log_rdma_event(ERR, "Queue Pair creation may fail\n");
+	}
+
+	info->send_cq = NULL;
+	info->recv_cq = NULL;
+	info->send_cq = ib_alloc_cq(info->id->device, info,
+			info->send_credit_target, 0, IB_POLL_SOFTIRQ);
+	if (IS_ERR(info->send_cq)) {
+		info->send_cq = NULL;
+		goto alloc_cq_failed;
+	}
+
+	info->recv_cq = ib_alloc_cq(info->id->device, info,
+			info->receive_credit_max, 0, IB_POLL_SOFTIRQ);
+	if (IS_ERR(info->recv_cq)) {
+		info->recv_cq = NULL;
+		goto alloc_cq_failed;
+	}
+
+	memset(&qp_attr, 0, sizeof(qp_attr));
+	qp_attr.event_handler = smbd_qp_async_error_upcall;
+	qp_attr.qp_context = info;
+	qp_attr.cap.max_send_wr = info->send_credit_target;
+	qp_attr.cap.max_recv_wr = info->receive_credit_max;
+	qp_attr.cap.max_send_sge = SMBDIRECT_MAX_SGE;
+	qp_attr.cap.max_recv_sge = SMBDIRECT_MAX_SGE;
+	qp_attr.cap.max_inline_data = 0;
+	qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
+	qp_attr.qp_type = IB_QPT_RC;
+	qp_attr.send_cq = info->send_cq;
+	qp_attr.recv_cq = info->recv_cq;
+	qp_attr.port_num = ~0;
+
+	rc = rdma_create_qp(info->id, info->pd, &qp_attr);
+	if (rc) {
+		log_rdma_event(ERR, "rdma_create_qp failed %i\n", rc);
+		goto create_qp_failed;
+	}
+
+	memset(&conn_param, 0, sizeof(conn_param));
+	conn_param.initiator_depth = 0;
+
+	conn_param.retry_count = SMBD_CM_RETRY;
+	conn_param.rnr_retry_count = SMBD_CM_RNR_RETRY;
+	conn_param.flow_control = 0;
+	init_waitqueue_head(&info->wait_destroy);
+
+	log_rdma_event(INFO, "connecting to IP %pI4 port %d\n",
+		&addr_in->sin_addr, port);
+
+	init_waitqueue_head(&info->conn_wait);
+	rc = rdma_connect(info->id, &conn_param);
+	if (rc) {
+		log_rdma_event(ERR, "rdma_connect() failed with %i\n", rc);
+		goto rdma_connect_failed;
+	}
+
+	wait_event_interruptible(
+		info->conn_wait, info->transport_status != SMBD_CONNECTING);
+
+	if (info->transport_status != SMBD_CONNECTED) {
+		log_rdma_event(ERR, "rdma_connect failed port=%d\n", port);
+		goto rdma_connect_failed;
+	}
+
+	log_rdma_event(INFO, "rdma_connect connected\n");
+
+	rc = allocate_caches_and_workqueue(info);
+	if (rc) {
+		log_rdma_event(ERR, "cache allocation failed\n");
+		goto allocate_cache_failed;
+	}
+
+	init_waitqueue_head(&info->wait_send_queue);
+	init_waitqueue_head(&info->wait_reassembly_queue);
+
+	INIT_DELAYED_WORK(&info->idle_timer_work, idle_connection_timer);
+	INIT_DELAYED_WORK(&info->send_immediate_work, send_immediate_work);
+	queue_delayed_work(info->workqueue, &info->idle_timer_work,
+		info->keep_alive_interval*HZ);
+
+	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->destroy_work, smbd_destroy_rdma_work);
+	INIT_WORK(&info->recv_done_work, smbd_recv_done_work);
+	INIT_WORK(&info->post_send_credits_work, smbd_post_send_credits);
+	info->new_credits_offered = 0;
+	spin_lock_init(&info->lock_new_credits_offered);
+
+	rc = smbd_negotiate(info);
+	if (rc) {
+		log_rdma_event(ERR, "smbd_negotiate rc=%d\n", rc);
+		goto negotiation_failed;
+	}
+
+	return info;
+
+negotiation_failed:
+	cancel_delayed_work_sync(&info->idle_timer_work);
+	destroy_caches_and_workqueue(info);
+	info->transport_status = SMBD_NEGOTIATE_FAILED;
+	init_waitqueue_head(&info->conn_wait);
+	rdma_disconnect(info->id);
+	wait_event(info->conn_wait,
+		info->transport_status == SMBD_DISCONNECTED);
+
+allocate_cache_failed:
+rdma_connect_failed:
+	rdma_destroy_qp(info->id);
+
+create_qp_failed:
+alloc_cq_failed:
+	if (info->send_cq)
+		ib_free_cq(info->send_cq);
+	if (info->recv_cq)
+		ib_free_cq(info->recv_cq);
+
+config_failed:
+	ib_dealloc_pd(info->pd);
+	rdma_destroy_id(info->id);
+
+create_id_failed:
+	kfree(info);
+	return NULL;
+}
diff --git a/fs/cifs/smbdirect.h b/fs/cifs/smbdirect.h
index c55f28b..ca60700 100644
--- a/fs/cifs/smbdirect.h
+++ b/fs/cifs/smbdirect.h
@@ -16,6 +16,235 @@ 
 #ifndef _SMBDIRECT_H
 #define _SMBDIRECT_H
 
+#include "cifsglob.h"
+#include <rdma/ib_verbs.h>
+#include <rdma/rdma_cm.h>
+#include <linux/mempool.h>
+
+enum keep_alive_status {
+	KEEP_ALIVE_NONE,
+	KEEP_ALIVE_PENDING,
+	KEEP_ALIVE_SENT,
+};
+
+enum smbd_connection_status {
+	SMBD_CREATED,
+	SMBD_CONNECTING,
+	SMBD_CONNECTED,
+	SMBD_NEGOTIATE_FAILED,
+	SMBD_DISCONNECTING,
+	SMBD_DISCONNECTED,
+	SMBD_DESTROYED
+};
+
+/*
+ * The context for the SMBDirect transport
+ * Everything related to the transport is here. It has several logical parts
+ * 1. RDMA related structures
+ * 2. SMBDirect connection parameters
+ * 3. Memory registrations
+ * 4. Receive and reassembly queues for data receive path
+ * 5. mempools for allocating packets
+ */
+struct smbd_connection {
+	enum smbd_connection_status transport_status;
+
+	/* RDMA related */
+	struct rdma_cm_id *id;
+	struct ib_qp_init_attr qp_attr;
+	struct ib_pd *pd;
+	struct ib_cq *send_cq, *recv_cq;
+	struct ib_device_attr dev_attr;
+	int ri_rc;
+	struct completion ri_done;
+	wait_queue_head_t conn_wait;
+	wait_queue_head_t wait_destroy;
+
+	struct completion negotiate_completion;
+	bool negotiate_done;
+
+	struct work_struct destroy_work;
+	struct work_struct disconnect_work;
+	struct work_struct recv_done_work;
+	struct work_struct post_send_credits_work;
+
+	spinlock_t lock_new_credits_offered;
+	int new_credits_offered;
+
+	/* Connection parameters defined in [MS-SMBD] 3.1.1.1 */
+	int receive_credit_max;
+	int send_credit_target;
+	int max_send_size;
+	int max_fragmented_recv_size;
+	int max_fragmented_send_size;
+	int max_receive_size;
+	int keep_alive_interval;
+	int max_readwrite_size;
+	enum keep_alive_status keep_alive_requested;
+	int protocol;
+	atomic_t send_credits;
+	atomic_t receive_credits;
+	int receive_credit_target;
+	int fragment_reassembly_remaining;
+
+	/* 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;
+	int count_receive_queue;
+	spinlock_t receive_queue_lock;
+
+	struct list_head empty_packet_queue;
+	int count_empty_packet_queue;
+	spinlock_t empty_packet_queue_lock;
+
+	wait_queue_head_t wait_receive_queues;
+
+	/* Reassembly queue */
+	struct list_head reassembly_queue;
+	spinlock_t reassembly_queue_lock;
+	wait_queue_head_t wait_reassembly_queue;
+
+	/* total data length of reassembly queue */
+	int reassembly_data_length;
+	int reassembly_queue_length;
+	/* the offset to first buffer in reassembly queue */
+	int first_entry_offset;
+
+	bool send_immediate;
+
+	wait_queue_head_t wait_send_queue;
+
+	/*
+	 * Indicate if we have received a full packet on the connection
+	 * This is used to identify the first SMBD packet of a assembled
+	 * payload (SMB packet) in reassembly queue so we can return a
+	 * RFC1002 length to upper layer to indicate the length of the SMB
+	 * packet received
+	 */
+	bool full_packet_received;
+
+	struct workqueue_struct *workqueue;
+	struct delayed_work idle_timer_work;
+	struct delayed_work send_immediate_work;
+
+	/* Memory pool for preallocating buffers */
+	/* request pool for RDMA send */
+	struct kmem_cache *request_cache;
+	mempool_t *request_mempool;
+
+	/* response pool for RDMA receive */
+	struct kmem_cache *response_cache;
+	mempool_t *response_mempool;
+
+	/* for debug purposes */
+	unsigned int count_get_receive_buffer;
+	unsigned int count_put_receive_buffer;
+	unsigned int count_reassembly_queue;
+	unsigned int count_enqueue_reassembly_queue;
+	unsigned int count_dequeue_reassembly_queue;
+	unsigned int count_send_empty;
+
+#define SIZE_LONG_LONG	64
+	unsigned long long smbd_write_cycles[SIZE_LONG_LONG];
+	unsigned long long smbd_recv_cycles[SIZE_LONG_LONG];
+	unsigned long long recv_done_cycles[SIZE_LONG_LONG];
+};
+
+enum smbd_message_type {
+	SMBD_NEGOTIATE_RESP,
+	SMBD_TRANSFER_DATA,
+};
+
+#define SMB_DIRECT_RESPONSE_REQUESTED 0x0001
+
+/* SMBD negotiation request packet [MS-SMBD] 2.2.1 */
+struct smbd_negotiate_req {
+	__le16 min_version;
+	__le16 max_version;
+	__le16 reserved;
+	__le16 credits_requested;
+	__le32 preferred_send_size;
+	__le32 max_receive_size;
+	__le32 max_fragmented_size;
+} __packed;
+
+/* SMBD negotiation response packet [MS-SMBD] 2.2.2 */
+struct smbd_negotiate_resp {
+	__le16 min_version;
+	__le16 max_version;
+	__le16 negotiated_version;
+	__le16 reserved;
+	__le16 credits_requested;
+	__le16 credits_granted;
+	__le32 status;
+	__le32 max_readwrite_size;
+	__le32 preferred_send_size;
+	__le32 max_receive_size;
+	__le32 max_fragmented_size;
+} __packed;
+
+/* SMBD data transfer packet with payload [MS-SMBD] 2.2.3 */
+struct smbd_data_transfer {
+	__le16 credits_requested;
+	__le16 credits_granted;
+	__le16 flags;
+	__le16 reserved;
+	__le32 remaining_data_length;
+	__le32 data_offset;
+	__le32 data_length;
+	__le32 padding;
+	__u8 buffer[];
+} __packed;
+
+/* The packet fields for a registered RDMA buffer */
+struct smbd_buffer_descriptor_v1 {
+	__le64 offset;
+	__le32 token;
+	__le32 length;
+} __packed;
+
 /* Default maximum number of SGEs in a RDMA send/recv */
 #define SMBDIRECT_MAX_SGE	16
+/* The context for a SMBD request */
+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;
+
+	/* SMBD packet header follows this structure */
+	u8 packet[];
+};
+
+/* The context for a SMBD response */
+struct smbd_response {
+	struct smbd_connection *info;
+	struct ib_cqe cqe;
+	struct ib_sge sge;
+
+	enum smbd_message_type type;
+
+	/* Link to receive queue or reassembly queue */
+	struct list_head list;
+
+	/* Indicate if this is the 1st packet of a payload */
+	bool first_segment;
+
+	/* SMBD packet header and payload follows this structure */
+	u8 packet[];
+};
+
+void profiling_display_histogram(
+	struct seq_file *m, unsigned long long array[]);
 #endif