// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   *   Copyright (C) 2017, Microsoft Corporation.
   *
   *   Author(s): Long Li <longli@microsoft.com>

   */

  #include <linux/module.h>

  #include <linux/highmem.h>

  #include "smbdirect.h"

  #include "cifs_debug.h"

  #include "cifsproto.h"

  #include "smb2proto.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);
  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);

  static int smbd_post_send_data(
  		struct smbd_connection *info,
  		struct kvec *iov, int n_vec, int remaining_data_length);
  static int smbd_post_send_page(struct smbd_connection *info,
  		struct page *page, unsigned long offset,
  		size_t size, int remaining_data_length);

  static void destroy_mr_list(struct smbd_connection *info);
  static int allocate_mr_list(struct smbd_connection *info);

  /* SMBD version number */
  #define SMBD_V1	0x0100
  
  /* Port numbers for SMBD transport */
  #define SMB_PORT	445
  #define SMBD_PORT	5445
  
  /* Address lookup and resolve timeout in ms */
  #define RDMA_RESOLVE_TIMEOUT	5000
  
  /* SMBD negotiation timeout in seconds */
  #define SMBD_NEGOTIATE_TIMEOUT	120
  
  /* SMBD minimum receive size and fragmented sized defined in [MS-SMBD] */
  #define SMBD_MIN_RECEIVE_SIZE		128
  #define SMBD_MIN_FRAGMENTED_SIZE	131072
  
  /*
   * Default maximum number of RDMA read/write outstanding on this connection
   * This value is possibly decreased during QP creation on hardware limit
   */
  #define SMBD_CM_RESPONDER_RESOURCES	32
  
  /* Maximum number of retries on data transfer operations */
  #define SMBD_CM_RETRY			6
  /* No need to retry on Receiver Not Ready since SMBD manages credits */
  #define SMBD_CM_RNR_RETRY		0
  
  /*
   * User configurable initial values per SMBD transport connection
   * as defined in [MS-SMBD] 3.1.1.1
   * Those may change after a SMBD negotiation
   */
  /* The local peer's maximum number of credits to grant to the peer */
  int smbd_receive_credit_max = 255;
  
  /* The remote peer's credit request of local peer */
  int smbd_send_credit_target = 255;
  
  /* The maximum single message size can be sent to remote peer */
  int smbd_max_send_size = 1364;
  
  /*  The maximum fragmented upper-layer payload receive size supported */
  int smbd_max_fragmented_recv_size = 1024 * 1024;
  
  /*  The maximum single-message size which can be received */
  int smbd_max_receive_size = 8192;
  
  /* The timeout to initiate send of a keepalive message on idle */
  int smbd_keep_alive_interval = 120;
  
  /*
   * User configurable initial values for RDMA transport
   * The actual values used may be lower and are limited to hardware capabilities
   */
  /* Default maximum number of SGEs in a RDMA write/read */
  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=0xa0 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;
  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)

  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
  ",
  		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
  ", 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
  ", 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;

  		wake_up_interruptible(&info->disconn_wait);

  		wake_up_interruptible(&info->wait_reassembly_queue);
  		wake_up_interruptible_all(&info->wait_send_queue);

  		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
  ",
  		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
  ",
  		request, wc->status);
  
  	if (wc->status != IB_WC_SUCCESS || wc->opcode != IB_WC_SEND) {
  		log_rdma_send(ERR, "wc->status=%d wc->opcode=%d
  ",
  			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 (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);
  }
  
  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
  ",
  		       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
  ", packet_length);
  		return false;
  	}
  
  	if (le16_to_cpu(packet->negotiated_version) != SMBD_V1) {
  		log_rdma_event(ERR, "error: negotiated_version=%x
  ",
  			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
  ");
  		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
  ");
  		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
  ",
  			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
  ",
  			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
  ",
  			le32_to_cpu(packet->max_fragmented_size));
  		return false;
  	}
  	info->max_fragmented_send_size =
  		le32_to_cpu(packet->max_fragmented_size);

  	info->rdma_readwrite_threshold =
  		rdma_readwrite_threshold > info->max_fragmented_send_size ?
  		info->max_fragmented_send_size :
  		rdma_readwrite_threshold;
  
  
  	info->max_readwrite_size = min_t(u32,
  			le32_to_cpu(packet->max_readwrite_size),
  			info->max_frmr_depth * PAGE_SIZE);
  	info->max_frmr_depth = info->max_readwrite_size / PAGE_SIZE;

  
  	return true;
  }

  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
  ", rc);
  				put_receive_buffer(info, response);
  				break;
  			}
  
  			ret++;
  		}
  	}
  
  	spin_lock(&info->lock_new_credits_offered);
  	info->new_credits_offered += ret;
  	spin_unlock(&info->lock_new_credits_offered);

  	/* Promptly send an immediate packet as defined in [MS-SMBD] 3.1.1.1 */
  	info->send_immediate = true;
  	if (atomic_read(&info->receive_credits) <
  		info->receive_credit_target - 1) {
  		if (info->keep_alive_requested == KEEP_ALIVE_PENDING ||
  		    info->send_immediate) {
  			log_keep_alive(INFO, "send an empty message
  ");
  			smbd_post_send_empty(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;
  	int data_length = 0;

  	log_rdma_recv(INFO, "response=%p type=%d wc status=%d wc opcode %d byte_len=%d pkey_index=%x
  ",
  		      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
  ",
  			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);
  
  		atomic_dec(&info->receive_credits);
  		info->receive_credit_target =
  			le16_to_cpu(data_transfer->credits_requested);

  		if (le16_to_cpu(data_transfer->credits_granted)) {
  			atomic_add(le16_to_cpu(data_transfer->credits_granted),
  				&info->send_credits);
  			/*
  			 * We have new send credits granted from remote peer
  			 * If any sender is waiting for credits, unblock it
  			 */
  			wake_up_interruptible(&info->wait_send_queue);
  		}

  		log_incoming(INFO, "data flags %d data_offset %d data_length %d remaining_data_length %d
  ",
  			     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) &
  				SMB_DIRECT_RESPONSE_REQUESTED) {
  			info->keep_alive_requested = KEEP_ALIVE_PENDING;
  		}

  		return;
  
  	default:
  		log_rdma_recv(ERR,
  			"unexpected response type=%d
  ", response->type);
  	}
  
  error:
  	put_receive_buffer(info, response);
  }
  
  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
  ", 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
  ", 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
  ", 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
  ", 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
  ", 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
  ");
  		log_rdma_event(ERR, "Device capability flags = %llx max_fast_reg_page_list_len = %u
  ",
  			       info->id->device->attrs.device_cap_flags,
  			       info->id->device->attrs.max_fast_reg_page_list_len);

  		rc = -EPROTONOSUPPORT;
  		goto out2;
  	}

  	info->max_frmr_depth = min_t(int,
  		smbd_max_frmr_depth,
  		info->id->device->attrs.max_fast_reg_page_list_len);
  	info->mr_type = IB_MR_TYPE_MEM_REG;
  	if (info->id->device->attrs.device_cap_flags & IB_DEVICE_SG_GAPS_REG)
  		info->mr_type = IB_MR_TYPE_SG_GAPS;

  
  	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
  ", 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;

  	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
  ",
  		request->sge[0].addr,
  		request->sge[0].length, request->sge[0].lkey);

  	atomic_inc(&info->send_pending);

  	rc = ib_post_send(info->id->qp, &send_wr, NULL);

  	if (!rc)
  		return 0;
  
  	/* if we reach here, post send failed */
  	log_rdma_send(ERR, "ib_post_send failed rc=%d
  ", rc);
  	atomic_dec(&info->send_pending);
  	ib_dma_unmap_single(info->id->device, request->sge[0].addr,
  		request->sge[0].length, DMA_TO_DEVICE);

  	smbd_disconnect_rdma_connection(info);

  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;
  }

  /* Post the send request */
  static int smbd_post_send(struct smbd_connection *info,
  		struct smbd_request *request)
  {
  	struct ib_send_wr send_wr;
  	int rc, i;
  
  	for (i = 0; i < request->num_sge; i++) {
  		log_rdma_send(INFO,
  			"rdma_request sge[%d] addr=%llu length=%u
  ",
  			i, request->sge[i].addr, request->sge[i].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;
  
  	rc = ib_post_send(info->id->qp, &send_wr, NULL);
  	if (rc) {
  		log_rdma_send(ERR, "ib_post_send failed rc=%d
  ", rc);
  		smbd_disconnect_rdma_connection(info);
  		rc = -EAGAIN;
  	} 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;
  	int header_length;

  	struct smbd_request *request;
  	struct smbd_data_transfer *packet;

  	int new_credits;

  	struct scatterlist *sg;

  wait_credit:

  	/* 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)

  		goto err_wait_credit;

  
  	if (info->transport_status != SMBD_CONNECTED) {

  		log_outgoing(ERR, "disconnected not sending on wait_credit
  ");
  		rc = -EAGAIN;
  		goto err_wait_credit;
  	}
  	if (unlikely(atomic_dec_return(&info->send_credits) < 0)) {
  		atomic_inc(&info->send_credits);
  		goto wait_credit;
  	}
  
  wait_send_queue:
  	wait_event(info->wait_post_send,
  		atomic_read(&info->send_pending) < info->send_credit_target ||
  		info->transport_status != SMBD_CONNECTED);
  
  	if (info->transport_status != SMBD_CONNECTED) {
  		log_outgoing(ERR, "disconnected not sending on wait_send_queue
  ");
  		rc = -EAGAIN;
  		goto err_wait_send_queue;
  	}
  
  	if (unlikely(atomic_inc_return(&info->send_pending) >
  				info->send_credit_target)) {
  		atomic_dec(&info->send_pending);
  		goto wait_send_queue;

  	}

  
  	request = mempool_alloc(info->request_mempool, GFP_KERNEL);
  	if (!request) {
  		rc = -ENOMEM;

  		goto err_alloc;

  	}
  
  	request->info = info;
  
  	/* Fill in the packet header */
  	packet = smbd_request_payload(request);
  	packet->credits_requested = cpu_to_le16(info->send_credit_target);

  
  	new_credits = manage_credits_prior_sending(info);
  	atomic_add(new_credits, &info->receive_credits);
  	packet->credits_granted = cpu_to_le16(new_credits);

  	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 (!data_length)

  		packet->data_offset = 0;
  	else
  		packet->data_offset = cpu_to_le32(24);

  	packet->data_length = cpu_to_le32(data_length);

  	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
  ",
  		     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 (!data_length)

  		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_TO_DEVICE);

  	if (ib_dma_mapping_error(info->id->device, request->sge[0].addr)) {

  		rc = -EIO;

  		request->sge[0].addr = 0;

  		goto err_dma;

  	}
  
  	request->sge[0].length = header_length;
  	request->sge[0].lkey = info->pd->local_dma_lkey;

  	/* Fill in the packet data payload */

  	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_TO_DEVICE);

  		if (ib_dma_mapping_error(
  				info->id->device, request->sge[i+1].addr)) {
  			rc = -EIO;
  			request->sge[i+1].addr = 0;

  			goto err_dma;

  		}
  		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);

  	if (!rc)
  		return 0;

  err_dma:
  	for (i = 0; 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);

  	mempool_free(request, info->request_mempool);
  
  	/* roll back receive credits and credits to be offered */
  	spin_lock(&info->lock_new_credits_offered);
  	info->new_credits_offered += new_credits;
  	spin_unlock(&info->lock_new_credits_offered);
  	atomic_sub(new_credits, &info->receive_credits);
  
  err_alloc:
  	if (atomic_dec_and_test(&info->send_pending))
  		wake_up(&info->wait_send_pending);
  
  err_wait_send_queue:
  	/* roll back send credits and pending */
  	atomic_inc(&info->send_credits);
  
  err_wait_credit:

  	return rc;
  }
  
  /*

   * Send a page
   * page: the page to send
   * offset: offset in the page to send
   * size: length in the page to send
   * remaining_data_length: remaining data to send in this payload
   */
  static int smbd_post_send_page(struct smbd_connection *info, struct page *page,
  		unsigned long offset, size_t size, int remaining_data_length)
  {
  	struct scatterlist sgl;
  
  	sg_init_table(&sgl, 1);
  	sg_set_page(&sgl, page, size, offset);
  
  	return smbd_post_send_sgl(info, &sgl, size, remaining_data_length);
  }
  
  /*

   * 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);
  }
  
  /*

   * Send a data buffer
   * iov: the iov array describing the data buffers
   * n_vec: number of iov array
   * remaining_data_length: remaining data to send following this packet
   * in segmented SMBD packet
   */
  static int smbd_post_send_data(
  	struct smbd_connection *info, struct kvec *iov, int n_vec,
  	int remaining_data_length)
  {
  	int i;
  	u32 data_length = 0;
  	struct scatterlist sgl[SMBDIRECT_MAX_SGE];
  
  	if (n_vec > SMBDIRECT_MAX_SGE) {
  		cifs_dbg(VFS, "Can't fit data to SGL, n_vec=%d
  ", n_vec);

  		return -EINVAL;

  	}
  
  	sg_init_table(sgl, n_vec);
  	for (i = 0; i < n_vec; i++) {
  		data_length += iov[i].iov_len;
  		sg_set_buf(&sgl[i], iov[i].iov_base, iov[i].iov_len);
  	}
  
  	return smbd_post_send_sgl(info, sgl, data_length, remaining_data_length);
  }
  
  /*

   * 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;

  	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, NULL);

  	if (rc) {
  		ib_dma_unmap_single(info->id->device, response->sge.addr,
  				    response->sge.length, DMA_FROM_DEVICE);

  		smbd_disconnect_rdma_connection(info);

  		log_rdma_recv(ERR, "ib_post_recv failed rc=%d
  ", 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
  ",
  		       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
  ", 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)
  {
  	unsigned long flags;
  
  	ib_dma_unmap_single(info->id->device, response->sge.addr,
  		response->sge.length, DMA_FROM_DEVICE);
  
  	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++;
  	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);
  }

  /* 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
  ",
  			info->keep_alive_requested);
  		smbd_disconnect_rdma_connection(info);
  		return;
  	}
  
  	log_keep_alive(INFO, "about to send an empty idle message
  ");
  	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);
  }

  /*
   * 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
   */
  void smbd_destroy(struct TCP_Server_Info *server)

  {

  	struct smbd_connection *info = server->smbd_conn;
  	struct smbd_response *response;
  	unsigned long flags;
  
  	if (!info) {
  		log_rdma_event(INFO, "rdma session already destroyed
  ");
  		return;
  	}

  	log_rdma_event(INFO, "destroying rdma session
  ");

  	if (info->transport_status != SMBD_DISCONNECTED) {
  		rdma_disconnect(server->smbd_conn->id);
  		log_rdma_event(INFO, "wait for transport being disconnected
  ");

  		wait_event_interruptible(

  			info->disconn_wait,
  			info->transport_status == SMBD_DISCONNECTED);
  	}

  	log_rdma_event(INFO, "destroying qp
  ");
  	ib_drain_qp(info->id->qp);
  	rdma_destroy_qp(info->id);
  
  	log_rdma_event(INFO, "cancelling idle timer
  ");
  	cancel_delayed_work_sync(&info->idle_timer_work);

  	log_rdma_event(INFO, "wait for all send posted to IB to finish
  ");
  	wait_event(info->wait_send_pending,
  		atomic_read(&info->send_pending) == 0);

  
  	/* It's not posssible for upper layer to get to reassembly */
  	log_rdma_event(INFO, "drain the reassembly queue
  ");
  	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);
  		} else
  			spin_unlock_irqrestore(
  				&info->reassembly_queue_lock, flags);
  	} while (response);
  	info->reassembly_data_length = 0;
  
  	log_rdma_event(INFO, "free receive buffers
  ");
  	wait_event(info->wait_receive_queues,
  		info->count_receive_queue + info->count_empty_packet_queue
  			== info->receive_credit_max);
  	destroy_receive_buffers(info);
  
  	/*
  	 * For performance reasons, memory registration and deregistration
  	 * are not locked by srv_mutex. It is possible some processes are
  	 * blocked on transport srv_mutex while holding memory registration.
  	 * Release the transport srv_mutex to allow them to hit the failure
  	 * path when sending data, and then release memory registartions.
  	 */
  	log_rdma_event(INFO, "freeing mr list
  ");
  	wake_up_interruptible_all(&info->wait_mr);
  	while (atomic_read(&info->mr_used_count)) {
  		mutex_unlock(&server->srv_mutex);
  		msleep(1000);
  		mutex_lock(&server->srv_mutex);
  	}
  	destroy_mr_list(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;

  
  	destroy_workqueue(info->workqueue);

  	log_rdma_event(INFO,  "rdma session destroyed
  ");

  	kfree(info);
  }

  /*
   * Reconnect this SMBD connection, called from upper layer
   * return value: 0 on success, or actual error code
   */
  int smbd_reconnect(struct TCP_Server_Info *server)
  {
  	log_rdma_event(INFO, "reconnecting rdma session
  ");
  
  	if (!server->smbd_conn) {

  		log_rdma_event(INFO, "rdma session already destroyed
  ");
  		goto create_conn;

  	}
  
  	/*
  	 * This is possible if transport is disconnected and we haven't received
  	 * notification from RDMA, but upper layer has detected timeout
  	 */
  	if (server->smbd_conn->transport_status == SMBD_CONNECTED) {
  		log_rdma_event(INFO, "disconnecting transport
  ");

  		smbd_destroy(server);

  	}

  create_conn:

  	log_rdma_event(INFO, "creating rdma session
  ");
  	server->smbd_conn = smbd_get_connection(
  		server, (struct sockaddr *) &server->dstaddr);

  
  	if (server->smbd_conn)
  		cifs_dbg(VFS, "RDMA transport re-established
  ");

  
  	return server->smbd_conn ? 0 : -ENOENT;
  }

  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;

  	scnprintf(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;

  	scnprintf(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;

  	scnprintf(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
  ");
  		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 */

  static 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;

  	struct ib_port_immutable port_immutable;
  	u32 ird_ord_hdr[2];

  
  	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
  ", 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
  ",
  			       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
  ",
  			       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 (info->id->device->attrs.max_send_sge < SMBDIRECT_MAX_SGE) {
  		log_rdma_event(ERR,
  			"warning: device max_send_sge = %d too small
  ",
  			info->id->device->attrs.max_send_sge);
  		log_rdma_event(ERR, "Queue Pair creation may fail
  ");
  	}
  	if (info->id->device->attrs.max_recv_sge < SMBDIRECT_MAX_SGE) {
  		log_rdma_event(ERR,
  			"warning: device max_recv_sge = %d too small
  ",
  			info->id->device->attrs.max_recv_sge);

  		log_rdma_event(ERR, "Queue Pair creation may fail
  ");
  	}
  
  	info->send_cq = NULL;
  	info->recv_cq = NULL;

  	info->send_cq =
  		ib_alloc_cq_any(info->id->device, info,
  				info->send_credit_target, IB_POLL_SOFTIRQ);

  	if (IS_ERR(info->send_cq)) {
  		info->send_cq = NULL;
  		goto alloc_cq_failed;
  	}

  	info->recv_cq =
  		ib_alloc_cq_any(info->id->device, info,
  				info->receive_credit_max, 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
  ", rc);
  		goto create_qp_failed;
  	}
  
  	memset(&conn_param, 0, sizeof(conn_param));
  	conn_param.initiator_depth = 0;

  	conn_param.responder_resources =
  		info->id->device->attrs.max_qp_rd_atom
  			< SMBD_CM_RESPONDER_RESOURCES ?
  		info->id->device->attrs.max_qp_rd_atom :
  		SMBD_CM_RESPONDER_RESOURCES;
  	info->responder_resources = conn_param.responder_resources;
  	log_rdma_mr(INFO, "responder_resources=%d
  ",
  		info->responder_resources);
  
  	/* Need to send IRD/ORD in private data for iWARP */

  	info->id->device->ops.get_port_immutable(

  		info->id->device, info->id->port_num, &port_immutable);
  	if (port_immutable.core_cap_flags & RDMA_CORE_PORT_IWARP) {
  		ird_ord_hdr[0] = info->responder_resources;
  		ird_ord_hdr[1] = 1;
  		conn_param.private_data = ird_ord_hdr;
  		conn_param.private_data_len = sizeof(ird_ord_hdr);
  	} else {
  		conn_param.private_data = NULL;
  		conn_param.private_data_len = 0;
  	}

  	conn_param.retry_count = SMBD_CM_RETRY;
  	conn_param.rnr_retry_count = SMBD_CM_RNR_RETRY;
  	conn_param.flow_control = 0;

  
  	log_rdma_event(INFO, "connecting to IP %pI4 port %d
  ",
  		&addr_in->sin_addr, port);
  
  	init_waitqueue_head(&info->conn_wait);

  	init_waitqueue_head(&info->disconn_wait);
  	init_waitqueue_head(&info->wait_reassembly_queue);

  	rc = rdma_connect(info->id, &conn_param);
  	if (rc) {
  		log_rdma_event(ERR, "rdma_connect() failed with %i
  ", 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
  ", port);
  		goto rdma_connect_failed;
  	}
  
  	log_rdma_event(INFO, "rdma_connect connected
  ");
  
  	rc = allocate_caches_and_workqueue(info);
  	if (rc) {
  		log_rdma_event(ERR, "cache allocation failed
  ");
  		goto allocate_cache_failed;
  	}
  
  	init_waitqueue_head(&info->wait_send_queue);

  	INIT_DELAYED_WORK(&info->idle_timer_work, idle_connection_timer);

  	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_post_send);

  
  	INIT_WORK(&info->disconnect_work, smbd_disconnect_rdma_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
  ", rc);
  		goto negotiation_failed;
  	}

  	rc = allocate_mr_list(info);
  	if (rc) {
  		log_rdma_mr(ERR, "memory registration allocation failed
  ");
  		goto allocate_mr_failed;
  	}

  	return info;

  allocate_mr_failed:
  	/* At this point, need to a full transport shutdown */

  	smbd_destroy(server);

  	return NULL;

  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;
  }

  
  struct smbd_connection *smbd_get_connection(
  	struct TCP_Server_Info *server, struct sockaddr *dstaddr)
  {
  	struct smbd_connection *ret;
  	int port = SMBD_PORT;
  
  try_again:
  	ret = _smbd_get_connection(server, dstaddr, port);
  
  	/* Try SMB_PORT if SMBD_PORT doesn't work */
  	if (!ret && port == SMBD_PORT) {
  		port = SMB_PORT;
  		goto try_again;
  	}
  	return ret;
  }

  
  /*
   * Receive data from receive reassembly queue
   * All the incoming data packets are placed in reassembly queue
   * buf: the buffer to read data into
   * size: the length of data to read
   * return value: actual data read
   * Note: this implementation copies the data from reassebmly queue to receive
   * buffers used by upper layer. This is not the optimal code path. A better way
   * to do it is to not have upper layer allocate its receive buffers but rather
   * borrow the buffer from reassembly queue, and return it after data is
   * consumed. But this will require more changes to upper layer code, and also
   * need to consider packet boundaries while they still being reassembled.
   */

  static int smbd_recv_buf(struct smbd_connection *info, char *buf,
  		unsigned int size)

  {
  	struct smbd_response *response;
  	struct smbd_data_transfer *data_transfer;
  	int to_copy, to_read, data_read, offset;
  	u32 data_length, remaining_data_length, data_offset;
  	int rc;

  
  again:

  	/*
  	 * No need to hold the reassembly queue lock all the time as we are
  	 * the only one reading from the front of the queue. The transport
  	 * may add more entries to the back of the queue at the same time
  	 */
  	log_read(INFO, "size=%d info->reassembly_data_length=%d
  ", size,
  		info->reassembly_data_length);
  	if (info->reassembly_data_length >= size) {
  		int queue_length;
  		int queue_removed = 0;
  
  		/*
  		 * Need to make sure reassembly_data_length is read before
  		 * reading reassembly_queue_length and calling
  		 * _get_first_reassembly. This call is lock free
  		 * as we never read at the end of the queue which are being
  		 * updated in SOFTIRQ as more data is received
  		 */
  		virt_rmb();
  		queue_length = info->reassembly_queue_length;
  		data_read = 0;
  		to_read = size;
  		offset = info->first_entry_offset;
  		while (data_read < size) {
  			response = _get_first_reassembly(info);
  			data_transfer = smbd_response_payload(response);
  			data_length = le32_to_cpu(data_transfer->data_length);
  			remaining_data_length =
  				le32_to_cpu(
  					data_transfer->remaining_data_length);
  			data_offset = le32_to_cpu(data_transfer->data_offset);
  
  			/*
  			 * The upper layer expects RFC1002 length at the
  			 * beginning of the payload. Return it to indicate
  			 * the total length of the packet. This minimize the
  			 * change to upper layer packet processing logic. This
  			 * will be eventually remove when an intermediate
  			 * transport layer is added
  			 */
  			if (response->first_segment && size == 4) {
  				unsigned int rfc1002_len =
  					data_length + remaining_data_length;
  				*((__be32 *)buf) = cpu_to_be32(rfc1002_len);
  				data_read = 4;
  				response->first_segment = false;
  				log_read(INFO, "returning rfc1002 length %d
  ",
  					rfc1002_len);
  				goto read_rfc1002_done;
  			}
  
  			to_copy = min_t(int, data_length - offset, to_read);
  			memcpy(
  				buf + data_read,
  				(char *)data_transfer + data_offset + offset,
  				to_copy);
  
  			/* move on to the next buffer? */
  			if (to_copy == data_length - offset) {
  				queue_length--;
  				/*
  				 * No need to lock if we are not at the
  				 * end of the queue
  				 */

  				if (queue_length)
  					list_del(&response->list);
  				else {

  					spin_lock_irq(
  						&info->reassembly_queue_lock);

  					list_del(&response->list);

  					spin_unlock_irq(
  						&info->reassembly_queue_lock);

  				}
  				queue_removed++;

  				info->count_reassembly_queue--;
  				info->count_dequeue_reassembly_queue++;
  				put_receive_buffer(info, response);
  				offset = 0;
  				log_read(INFO, "put_receive_buffer offset=0
  ");
  			} else
  				offset += to_copy;
  
  			to_read -= to_copy;
  			data_read += to_copy;

  			log_read(INFO, "_get_first_reassembly memcpy %d bytes data_transfer_length-offset=%d after that to_read=%d data_read=%d offset=%d
  ",
  				 to_copy, data_length - offset,
  				 to_read, data_read, offset);

  		}

  		spin_lock_irq(&info->reassembly_queue_lock);

  		info->reassembly_data_length -= data_read;
  		info->reassembly_queue_length -= queue_removed;

  		spin_unlock_irq(&info->reassembly_queue_lock);

  
  		info->first_entry_offset = offset;

  		log_read(INFO, "returning to thread data_read=%d reassembly_data_length=%d first_entry_offset=%d
  ",
  			 data_read, info->reassembly_data_length,
  			 info->first_entry_offset);

  read_rfc1002_done:
  		return data_read;
  	}
  
  	log_read(INFO, "wait_event on more data
  ");
  	rc = wait_event_interruptible(
  		info->wait_reassembly_queue,
  		info->reassembly_data_length >= size ||
  			info->transport_status != SMBD_CONNECTED);
  	/* Don't return any data if interrupted */
  	if (rc)

  		return rc;

  	if (info->transport_status != SMBD_CONNECTED) {
  		log_read(ERR, "disconnected
  ");

  		return -ECONNABORTED;

  	}

  	goto again;
  }
  
  /*
   * Receive a page from receive reassembly queue
   * page: the page to read data into
   * to_read: the length of data to read
   * return value: actual data read
   */

  static int smbd_recv_page(struct smbd_connection *info,

  		struct page *page, unsigned int page_offset,
  		unsigned int to_read)

  {
  	int ret;
  	char *to_address;

  	void *page_address;

  
  	/* make sure we have the page ready for read */
  	ret = wait_event_interruptible(
  		info->wait_reassembly_queue,
  		info->reassembly_data_length >= to_read ||
  			info->transport_status != SMBD_CONNECTED);
  	if (ret)

  		return ret;

  
  	/* now we can read from reassembly queue and not sleep */

  	page_address = kmap_atomic(page);
  	to_address = (char *) page_address + page_offset;

  
  	log_read(INFO, "reading from page=%p address=%p to_read=%d
  ",
  		page, to_address, to_read);
  
  	ret = smbd_recv_buf(info, to_address, to_read);

  	kunmap_atomic(page_address);

  
  	return ret;
  }
  
  /*
   * Receive data from transport
   * msg: a msghdr point to the buffer, can be ITER_KVEC or ITER_BVEC
   * return: total bytes read, or 0. SMB Direct will not do partial read.
   */
  int smbd_recv(struct smbd_connection *info, struct msghdr *msg)
  {
  	char *buf;
  	struct page *page;

  	unsigned int to_read, page_offset;

  	int rc;

  	if (iov_iter_rw(&msg->msg_iter) == WRITE) {
  		/* It's a bug in upper layer to get there */

  		cifs_dbg(VFS, "Invalid msg iter dir %u
  ",

  			 iov_iter_rw(&msg->msg_iter));
  		rc = -EINVAL;
  		goto out;
  	}
  
  	switch (iov_iter_type(&msg->msg_iter)) {
  	case ITER_KVEC:

  		buf = msg->msg_iter.kvec->iov_base;
  		to_read = msg->msg_iter.kvec->iov_len;
  		rc = smbd_recv_buf(info, buf, to_read);
  		break;

  	case ITER_BVEC:

  		page = msg->msg_iter.bvec->bv_page;

  		page_offset = msg->msg_iter.bvec->bv_offset;

  		to_read = msg->msg_iter.bvec->bv_len;

  		rc = smbd_recv_page(info, page, page_offset, to_read);

  		break;
  
  	default:
  		/* It's a bug in upper layer to get there */

  		cifs_dbg(VFS, "Invalid msg type %d
  ",

  			 iov_iter_type(&msg->msg_iter));

  		rc = -EINVAL;

  	}

  out:

  	/* SMBDirect will read it all or nothing */
  	if (rc > 0)
  		msg->msg_iter.count = 0;
  	return rc;
  }

  
  /*
   * Send data to transport
   * Each rqst is transported as a SMBDirect payload
   * rqst: the data to write
   * return value: 0 if successfully write, otherwise error code
   */

  int smbd_send(struct TCP_Server_Info *server,
  	int num_rqst, struct smb_rqst *rqst_array)

  {

  	struct smbd_connection *info = server->smbd_conn;

  	struct kvec vec;
  	int nvecs;
  	int size;

  	unsigned int buflen, remaining_data_length;

  	int start, i, j;
  	int max_iov_size =
  		info->max_send_size - sizeof(struct smbd_data_transfer);

  	struct kvec *iov;

  	int rc;

  	struct smb_rqst *rqst;
  	int rqst_idx;

  	if (info->transport_status != SMBD_CONNECTED) {

  		rc = -EAGAIN;

  		goto done;
  	}
  
  	/*

  	 * Add in the page array if there is one. The caller needs to set
  	 * rq_tailsz to PAGE_SIZE when the buffer has multiple pages and
  	 * ends at page boundary
  	 */

  	remaining_data_length = 0;
  	for (i = 0; i < num_rqst; i++)
  		remaining_data_length += smb_rqst_len(server, &rqst_array[i]);

  	if (remaining_data_length > info->max_fragmented_send_size) {

  		log_write(ERR, "payload size %d > max size %d
  ",

  			remaining_data_length, info->max_fragmented_send_size);

  		rc = -EINVAL;
  		goto done;
  	}

  	log_write(INFO, "num_rqst=%d total length=%u
  ",
  			num_rqst, remaining_data_length);

  	rqst_idx = 0;

  next_rqst:
  	rqst = &rqst_array[rqst_idx];
  	iov = rqst->rq_iov;

  	cifs_dbg(FYI, "Sending smb (RDMA): idx=%d smb_len=%lu
  ",
  		rqst_idx, smb_rqst_len(server, rqst));
  	for (i = 0; i < rqst->rq_nvec; i++)

  		dump_smb(iov[i].iov_base, iov[i].iov_len);

  	log_write(INFO, "rqst_idx=%d nvec=%d rqst->rq_npages=%d rq_pagesz=%d rq_tailsz=%d buflen=%lu
  ",
  		  rqst_idx, rqst->rq_nvec, rqst->rq_npages, rqst->rq_pagesz,
  		  rqst->rq_tailsz, smb_rqst_len(server, rqst));

  	start = i = 0;

  	buflen = 0;
  	while (true) {
  		buflen += iov[i].iov_len;
  		if (buflen > max_iov_size) {
  			if (i > start) {
  				remaining_data_length -=
  					(buflen-iov[i].iov_len);

  				log_write(INFO, "sending iov[] from start=%d i=%d nvecs=%d remaining_data_length=%d
  ",
  					  start, i, i - start,
  					  remaining_data_length);

  				rc = smbd_post_send_data(
  					info, &iov[start], i-start,
  					remaining_data_length);
  				if (rc)
  					goto done;
  			} else {
  				/* iov[start] is too big, break it */
  				nvecs = (buflen+max_iov_size-1)/max_iov_size;

  				log_write(INFO, "iov[%d] iov_base=%p buflen=%d break to %d vectors
  ",
  					  start, iov[start].iov_base,
  					  buflen, nvecs);

  				for (j = 0; j < nvecs; j++) {
  					vec.iov_base =
  						(char *)iov[start].iov_base +
  						j*max_iov_size;
  					vec.iov_len = max_iov_size;
  					if (j == nvecs-1)
  						vec.iov_len =
  							buflen -
  							max_iov_size*(nvecs-1);
  					remaining_data_length -= vec.iov_len;
  					log_write(INFO,

  						"sending vec j=%d iov_base=%p iov_len=%zu remaining_data_length=%d
  ",
  						  j, vec.iov_base, vec.iov_len,
  						  remaining_data_length);

  					rc = smbd_post_send_data(
  						info, &vec, 1,
  						remaining_data_length);
  					if (rc)
  						goto done;
  				}
  				i++;

  				if (i == rqst->rq_nvec)

  					break;

  			}
  			start = i;
  			buflen = 0;
  		} else {
  			i++;

  			if (i == rqst->rq_nvec) {

  				/* send out all remaining vecs */
  				remaining_data_length -= buflen;

  				log_write(INFO, "sending iov[] from start=%d i=%d nvecs=%d remaining_data_length=%d
  ",
  					  start, i, i - start,
  					  remaining_data_length);

  				rc = smbd_post_send_data(info, &iov[start],
  					i-start, remaining_data_length);
  				if (rc)
  					goto done;
  				break;
  			}
  		}
  		log_write(INFO, "looping i=%d buflen=%d
  ", i, buflen);
  	}
  
  	/* now sending pages if there are any */
  	for (i = 0; i < rqst->rq_npages; i++) {

  		unsigned int offset;
  
  		rqst_page_get_length(rqst, i, &buflen, &offset);

  		nvecs = (buflen + max_iov_size - 1) / max_iov_size;
  		log_write(INFO, "sending pages buflen=%d nvecs=%d
  ",
  			buflen, nvecs);
  		for (j = 0; j < nvecs; j++) {
  			size = max_iov_size;
  			if (j == nvecs-1)
  				size = buflen - j*max_iov_size;
  			remaining_data_length -= size;

  			log_write(INFO, "sending pages i=%d offset=%d size=%d remaining_data_length=%d
  ",
  				  i, j * max_iov_size + offset, size,
  				  remaining_data_length);

  			rc = smbd_post_send_page(

  				info, rqst->rq_pages[i],
  				j*max_iov_size + offset,

  				size, remaining_data_length);
  			if (rc)
  				goto done;
  		}
  	}

  	rqst_idx++;
  	if (rqst_idx < num_rqst)
  		goto next_rqst;

  done:
  	/*
  	 * As an optimization, we don't wait for individual I/O to finish
  	 * before sending the next one.
  	 * Send them all and wait for pending send count to get to 0
  	 * that means all the I/Os have been out and we are good to return
  	 */

  	wait_event(info->wait_send_pending,
  		atomic_read(&info->send_pending) == 0);

  	return rc;
  }

  
  static void register_mr_done(struct ib_cq *cq, struct ib_wc *wc)
  {
  	struct smbd_mr *mr;
  	struct ib_cqe *cqe;
  
  	if (wc->status) {
  		log_rdma_mr(ERR, "status=%d
  ", wc->status);
  		cqe = wc->wr_cqe;
  		mr = container_of(cqe, struct smbd_mr, cqe);
  		smbd_disconnect_rdma_connection(mr->conn);
  	}
  }
  
  /*
   * The work queue function that recovers MRs
   * We need to call ib_dereg_mr() and ib_alloc_mr() before this MR can be used
   * again. Both calls are slow, so finish them in a workqueue. This will not
   * block I/O path.
   * There is one workqueue that recovers MRs, there is no need to lock as the
   * I/O requests calling smbd_register_mr will never update the links in the
   * mr_list.
   */
  static void smbd_mr_recovery_work(struct work_struct *work)
  {
  	struct smbd_connection *info =
  		container_of(work, struct smbd_connection, mr_recovery_work);
  	struct smbd_mr *smbdirect_mr;
  	int rc;
  
  	list_for_each_entry(smbdirect_mr, &info->mr_list, list) {

  		if (smbdirect_mr->state == MR_ERROR) {

  			/* recover this MR entry */
  			rc = ib_dereg_mr(smbdirect_mr->mr);
  			if (rc) {
  				log_rdma_mr(ERR,
  					"ib_dereg_mr failed rc=%x
  ",
  					rc);
  				smbd_disconnect_rdma_connection(info);
  				continue;
  			}
  
  			smbdirect_mr->mr = ib_alloc_mr(
  				info->pd, info->mr_type,
  				info->max_frmr_depth);
  			if (IS_ERR(smbdirect_mr->mr)) {

  				log_rdma_mr(ERR, "ib_alloc_mr failed mr_type=%x max_frmr_depth=%x
  ",
  					    info->mr_type,
  					    info->max_frmr_depth);

  				smbd_disconnect_rdma_connection(info);
  				continue;
  			}

  		} else
  			/* This MR is being used, don't recover it */
  			continue;

  		smbdirect_mr->state = MR_READY;

  		/* smbdirect_mr->state is updated by this function
  		 * and is read and updated by I/O issuing CPUs trying
  		 * to get a MR, the call to atomic_inc_return
  		 * implicates a memory barrier and guarantees this
  		 * value is updated before waking up any calls to
  		 * get_mr() from the I/O issuing CPUs
  		 */
  		if (atomic_inc_return(&info->mr_ready_count) == 1)
  			wake_up_interruptible(&info->wait_mr);

  	}
  }
  
  static void destroy_mr_list(struct smbd_connection *info)
  {
  	struct smbd_mr *mr, *tmp;
  
  	cancel_work_sync(&info->mr_recovery_work);
  	list_for_each_entry_safe(mr, tmp, &info->mr_list, list) {
  		if (mr->state == MR_INVALIDATED)
  			ib_dma_unmap_sg(info->id->device, mr->sgl,
  				mr->sgl_count, mr->dir);
  		ib_dereg_mr(mr->mr);
  		kfree(mr->sgl);
  		kfree(mr);
  	}
  }
  
  /*
   * Allocate MRs used for RDMA read/write
   * The number of MRs will not exceed hardware capability in responder_resources
   * All MRs are kept in mr_list. The MR can be recovered after it's used
   * Recovery is done in smbd_mr_recovery_work. The content of list entry changes
   * as MRs are used and recovered for I/O, but the list links will not change
   */
  static int allocate_mr_list(struct smbd_connection *info)
  {
  	int i;
  	struct smbd_mr *smbdirect_mr, *tmp;
  
  	INIT_LIST_HEAD(&info->mr_list);
  	init_waitqueue_head(&info->wait_mr);
  	spin_lock_init(&info->mr_list_lock);
  	atomic_set(&info->mr_ready_count, 0);
  	atomic_set(&info->mr_used_count, 0);
  	init_waitqueue_head(&info->wait_for_mr_cleanup);
  	/* Allocate more MRs (2x) than hardware responder_resources */
  	for (i = 0; i < info->responder_resources * 2; i++) {
  		smbdirect_mr = kzalloc(sizeof(*smbdirect_mr), GFP_KERNEL);
  		if (!smbdirect_mr)
  			goto out;
  		smbdirect_mr->mr = ib_alloc_mr(info->pd, info->mr_type,
  					info->max_frmr_depth);
  		if (IS_ERR(smbdirect_mr->mr)) {

  			log_rdma_mr(ERR, "ib_alloc_mr failed mr_type=%x max_frmr_depth=%x
  ",
  				    info->mr_type, info->max_frmr_depth);

  			goto out;
  		}
  		smbdirect_mr->sgl = kcalloc(
  					info->max_frmr_depth,
  					sizeof(struct scatterlist),
  					GFP_KERNEL);
  		if (!smbdirect_mr->sgl) {
  			log_rdma_mr(ERR, "failed to allocate sgl
  ");
  			ib_dereg_mr(smbdirect_mr->mr);
  			goto out;
  		}
  		smbdirect_mr->state = MR_READY;
  		smbdirect_mr->conn = info;
  
  		list_add_tail(&smbdirect_mr->list, &info->mr_list);
  		atomic_inc(&info->mr_ready_count);
  	}
  	INIT_WORK(&info->mr_recovery_work, smbd_mr_recovery_work);
  	return 0;
  
  out:
  	kfree(smbdirect_mr);
  
  	list_for_each_entry_safe(smbdirect_mr, tmp, &info->mr_list, list) {
  		ib_dereg_mr(smbdirect_mr->mr);
  		kfree(smbdirect_mr->sgl);
  		kfree(smbdirect_mr);
  	}
  	return -ENOMEM;
  }
  
  /*
   * Get a MR from mr_list. This function waits until there is at least one
   * MR available in the list. It may access the list while the
   * smbd_mr_recovery_work is recovering the MR list. This doesn't need a lock
   * as they never modify the same places. However, there may be several CPUs
   * issueing I/O trying to get MR at the same time, mr_list_lock is used to
   * protect this situation.
   */
  static struct smbd_mr *get_mr(struct smbd_connection *info)
  {
  	struct smbd_mr *ret;
  	int rc;
  again:
  	rc = wait_event_interruptible(info->wait_mr,
  		atomic_read(&info->mr_ready_count) ||
  		info->transport_status != SMBD_CONNECTED);
  	if (rc) {
  		log_rdma_mr(ERR, "wait_event_interruptible rc=%x
  ", rc);
  		return NULL;
  	}
  
  	if (info->transport_status != SMBD_CONNECTED) {
  		log_rdma_mr(ERR, "info->transport_status=%x
  ",
  			info->transport_status);
  		return NULL;
  	}
  
  	spin_lock(&info->mr_list_lock);
  	list_for_each_entry(ret, &info->mr_list, list) {
  		if (ret->state == MR_READY) {
  			ret->state = MR_REGISTERED;
  			spin_unlock(&info->mr_list_lock);
  			atomic_dec(&info->mr_ready_count);
  			atomic_inc(&info->mr_used_count);
  			return ret;
  		}
  	}
  
  	spin_unlock(&info->mr_list_lock);
  	/*
  	 * It is possible that we could fail to get MR because other processes may
  	 * try to acquire a MR at the same time. If this is the case, retry it.
  	 */
  	goto again;
  }
  
  /*
   * Register memory for RDMA read/write
   * pages[]: the list of pages to register memory with
   * num_pages: the number of pages to register
   * tailsz: if non-zero, the bytes to register in the last page
   * writing: true if this is a RDMA write (SMB read), false for RDMA read
   * need_invalidate: true if this MR needs to be locally invalidated after I/O
   * return value: the MR registered, NULL if failed.
   */
  struct smbd_mr *smbd_register_mr(
  	struct smbd_connection *info, struct page *pages[], int num_pages,

  	int offset, int tailsz, bool writing, bool need_invalidate)

  {
  	struct smbd_mr *smbdirect_mr;
  	int rc, i;
  	enum dma_data_direction dir;
  	struct ib_reg_wr *reg_wr;

  
  	if (num_pages > info->max_frmr_depth) {
  		log_rdma_mr(ERR, "num_pages=%d max_frmr_depth=%d
  ",
  			num_pages, info->max_frmr_depth);
  		return NULL;
  	}
  
  	smbdirect_mr = get_mr(info);
  	if (!smbdirect_mr) {
  		log_rdma_mr(ERR, "get_mr returning NULL
  ");
  		return NULL;
  	}
  	smbdirect_mr->need_invalidate = need_invalidate;
  	smbdirect_mr->sgl_count = num_pages;
  	sg_init_table(smbdirect_mr->sgl, num_pages);

  	log_rdma_mr(INFO, "num_pages=0x%x offset=0x%x tailsz=0x%x
  ",
  			num_pages, offset, tailsz);

  	if (num_pages == 1) {
  		sg_set_page(&smbdirect_mr->sgl[0], pages[0], tailsz, offset);
  		goto skip_multiple_pages;
  	}
  
  	/* We have at least two pages to register */
  	sg_set_page(
  		&smbdirect_mr->sgl[0], pages[0], PAGE_SIZE - offset, offset);
  	i = 1;
  	while (i < num_pages - 1) {
  		sg_set_page(&smbdirect_mr->sgl[i], pages[i], PAGE_SIZE, 0);
  		i++;
  	}

  	sg_set_page(&smbdirect_mr->sgl[i], pages[i],
  		tailsz ? tailsz : PAGE_SIZE, 0);

  skip_multiple_pages:

  	dir = writing ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
  	smbdirect_mr->dir = dir;
  	rc = ib_dma_map_sg(info->id->device, smbdirect_mr->sgl, num_pages, dir);
  	if (!rc) {

  		log_rdma_mr(ERR, "ib_dma_map_sg num_pages=%x dir=%x rc=%x
  ",

  			num_pages, dir, rc);
  		goto dma_map_error;
  	}
  
  	rc = ib_map_mr_sg(smbdirect_mr->mr, smbdirect_mr->sgl, num_pages,
  		NULL, PAGE_SIZE);
  	if (rc != num_pages) {

  		log_rdma_mr(ERR,
  			"ib_map_mr_sg failed rc = %d num_pages = %x
  ",

  			rc, num_pages);
  		goto map_mr_error;
  	}
  
  	ib_update_fast_reg_key(smbdirect_mr->mr,
  		ib_inc_rkey(smbdirect_mr->mr->rkey));
  	reg_wr = &smbdirect_mr->wr;
  	reg_wr->wr.opcode = IB_WR_REG_MR;
  	smbdirect_mr->cqe.done = register_mr_done;
  	reg_wr->wr.wr_cqe = &smbdirect_mr->cqe;
  	reg_wr->wr.num_sge = 0;
  	reg_wr->wr.send_flags = IB_SEND_SIGNALED;
  	reg_wr->mr = smbdirect_mr->mr;
  	reg_wr->key = smbdirect_mr->mr->rkey;
  	reg_wr->access = writing ?
  			IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
  			IB_ACCESS_REMOTE_READ;
  
  	/*
  	 * There is no need for waiting for complemtion on ib_post_send
  	 * on IB_WR_REG_MR. Hardware enforces a barrier and order of execution
  	 * on the next ib_post_send when we actaully send I/O to remote peer
  	 */

  	rc = ib_post_send(info->id->qp, &reg_wr->wr, NULL);

  	if (!rc)
  		return smbdirect_mr;
  
  	log_rdma_mr(ERR, "ib_post_send failed rc=%x reg_wr->key=%x
  ",
  		rc, reg_wr->key);
  
  	/* If all failed, attempt to recover this MR by setting it MR_ERROR*/
  map_mr_error:
  	ib_dma_unmap_sg(info->id->device, smbdirect_mr->sgl,
  		smbdirect_mr->sgl_count, smbdirect_mr->dir);
  
  dma_map_error:
  	smbdirect_mr->state = MR_ERROR;
  	if (atomic_dec_and_test(&info->mr_used_count))
  		wake_up(&info->wait_for_mr_cleanup);

  	smbd_disconnect_rdma_connection(info);

  	return NULL;
  }
  
  static void local_inv_done(struct ib_cq *cq, struct ib_wc *wc)
  {
  	struct smbd_mr *smbdirect_mr;
  	struct ib_cqe *cqe;
  
  	cqe = wc->wr_cqe;
  	smbdirect_mr = container_of(cqe, struct smbd_mr, cqe);
  	smbdirect_mr->state = MR_INVALIDATED;
  	if (wc->status != IB_WC_SUCCESS) {
  		log_rdma_mr(ERR, "invalidate failed status=%x
  ", wc->status);
  		smbdirect_mr->state = MR_ERROR;
  	}
  	complete(&smbdirect_mr->invalidate_done);
  }
  
  /*
   * Deregister a MR after I/O is done
   * This function may wait if remote invalidation is not used
   * and we have to locally invalidate the buffer to prevent data is being
   * modified by remote peer after upper layer consumes it
   */
  int smbd_deregister_mr(struct smbd_mr *smbdirect_mr)
  {

  	struct ib_send_wr *wr;

  	struct smbd_connection *info = smbdirect_mr->conn;
  	int rc = 0;
  
  	if (smbdirect_mr->need_invalidate) {
  		/* Need to finish local invalidation before returning */
  		wr = &smbdirect_mr->inv_wr;
  		wr->opcode = IB_WR_LOCAL_INV;
  		smbdirect_mr->cqe.done = local_inv_done;
  		wr->wr_cqe = &smbdirect_mr->cqe;
  		wr->num_sge = 0;
  		wr->ex.invalidate_rkey = smbdirect_mr->mr->rkey;
  		wr->send_flags = IB_SEND_SIGNALED;
  
  		init_completion(&smbdirect_mr->invalidate_done);

  		rc = ib_post_send(info->id->qp, wr, NULL);

  		if (rc) {
  			log_rdma_mr(ERR, "ib_post_send failed rc=%x
  ", rc);
  			smbd_disconnect_rdma_connection(info);
  			goto done;
  		}
  		wait_for_completion(&smbdirect_mr->invalidate_done);
  		smbdirect_mr->need_invalidate = false;
  	} else
  		/*
  		 * For remote invalidation, just set it to MR_INVALIDATED
  		 * and defer to mr_recovery_work to recover the MR for next use
  		 */
  		smbdirect_mr->state = MR_INVALIDATED;

  	if (smbdirect_mr->state == MR_INVALIDATED) {
  		ib_dma_unmap_sg(
  			info->id->device, smbdirect_mr->sgl,
  			smbdirect_mr->sgl_count,
  			smbdirect_mr->dir);
  		smbdirect_mr->state = MR_READY;
  		if (atomic_inc_return(&info->mr_ready_count) == 1)
  			wake_up_interruptible(&info->wait_mr);
  	} else
  		/*
  		 * Schedule the work to do MR recovery for future I/Os MR
  		 * recovery is slow and don't want it to block current I/O
  		 */
  		queue_work(info->workqueue, &info->mr_recovery_work);

  
  done:
  	if (atomic_dec_and_test(&info->mr_used_count))
  		wake_up(&info->wait_for_mr_cleanup);
  
  	return rc;
  }