Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1818 insertions, 0 deletions

diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c
new file mode 100644
index 0000000000..4f717ad7c2
--- /dev/null
+++ b/fs/smb/client/transport.c
@@ -0,0 +1,1818 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ *
+ *   Copyright (C) International Business Machines  Corp., 2002,2008
+ *   Author(s): Steve French (sfrench@us.ibm.com)
+ *   Jeremy Allison (jra@samba.org) 2006.
+ *
+ */
+
+#include <linux/fs.h>
+#include <linux/list.h>
+#include <linux/gfp.h>
+#include <linux/wait.h>
+#include <linux/net.h>
+#include <linux/delay.h>
+#include <linux/freezer.h>
+#include <linux/tcp.h>
+#include <linux/bvec.h>
+#include <linux/highmem.h>
+#include <linux/uaccess.h>
+#include <linux/processor.h>
+#include <linux/mempool.h>
+#include <linux/sched/signal.h>
+#include <linux/task_io_accounting_ops.h>
+#include "cifspdu.h"
+#include "cifsglob.h"
+#include "cifsproto.h"
+#include "cifs_debug.h"
+#include "smb2proto.h"
+#include "smbdirect.h"
+
+/* Max number of iovectors we can use off the stack when sending requests. */
+#define CIFS_MAX_IOV_SIZE 8
+
+void
+cifs_wake_up_task(struct mid_q_entry *mid)
+{
+	if (mid->mid_state == MID_RESPONSE_RECEIVED)
+		mid->mid_state = MID_RESPONSE_READY;
+	wake_up_process(mid->callback_data);
+}
+
+static struct mid_q_entry *
+alloc_mid(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
+{
+	struct mid_q_entry *temp;
+
+	if (server == NULL) {
+		cifs_dbg(VFS, "%s: null TCP session\n", __func__);
+		return NULL;
+	}
+
+	temp = mempool_alloc(cifs_mid_poolp, GFP_NOFS);
+	memset(temp, 0, sizeof(struct mid_q_entry));
+	kref_init(&temp->refcount);
+	temp->mid = get_mid(smb_buffer);
+	temp->pid = current->pid;
+	temp->command = cpu_to_le16(smb_buffer->Command);
+	cifs_dbg(FYI, "For smb_command %d\n", smb_buffer->Command);
+	/* easier to use jiffies */
+	/* when mid allocated can be before when sent */
+	temp->when_alloc = jiffies;
+	temp->server = server;
+
+	/*
+	 * The default is for the mid to be synchronous, so the
+	 * default callback just wakes up the current task.
+	 */
+	get_task_struct(current);
+	temp->creator = current;
+	temp->callback = cifs_wake_up_task;
+	temp->callback_data = current;
+
+	atomic_inc(&mid_count);
+	temp->mid_state = MID_REQUEST_ALLOCATED;
+	return temp;
+}
+
+void __release_mid(struct kref *refcount)
+{
+	struct mid_q_entry *midEntry =
+			container_of(refcount, struct mid_q_entry, refcount);
+#ifdef CONFIG_CIFS_STATS2
+	__le16 command = midEntry->server->vals->lock_cmd;
+	__u16 smb_cmd = le16_to_cpu(midEntry->command);
+	unsigned long now;
+	unsigned long roundtrip_time;
+#endif
+	struct TCP_Server_Info *server = midEntry->server;
+
+	if (midEntry->resp_buf && (midEntry->mid_flags & MID_WAIT_CANCELLED) &&
+	    (midEntry->mid_state == MID_RESPONSE_RECEIVED ||
+	     midEntry->mid_state == MID_RESPONSE_READY) &&
+	    server->ops->handle_cancelled_mid)
+		server->ops->handle_cancelled_mid(midEntry, server);
+
+	midEntry->mid_state = MID_FREE;
+	atomic_dec(&mid_count);
+	if (midEntry->large_buf)
+		cifs_buf_release(midEntry->resp_buf);
+	else
+		cifs_small_buf_release(midEntry->resp_buf);
+#ifdef CONFIG_CIFS_STATS2
+	now = jiffies;
+	if (now < midEntry->when_alloc)
+		cifs_server_dbg(VFS, "Invalid mid allocation time\n");
+	roundtrip_time = now - midEntry->when_alloc;
+
+	if (smb_cmd < NUMBER_OF_SMB2_COMMANDS) {
+		if (atomic_read(&server->num_cmds[smb_cmd]) == 0) {
+			server->slowest_cmd[smb_cmd] = roundtrip_time;
+			server->fastest_cmd[smb_cmd] = roundtrip_time;
+		} else {
+			if (server->slowest_cmd[smb_cmd] < roundtrip_time)
+				server->slowest_cmd[smb_cmd] = roundtrip_time;
+			else if (server->fastest_cmd[smb_cmd] > roundtrip_time)
+				server->fastest_cmd[smb_cmd] = roundtrip_time;
+		}
+		cifs_stats_inc(&server->num_cmds[smb_cmd]);
+		server->time_per_cmd[smb_cmd] += roundtrip_time;
+	}
+	/*
+	 * commands taking longer than one second (default) can be indications
+	 * that something is wrong, unless it is quite a slow link or a very
+	 * busy server. Note that this calc is unlikely or impossible to wrap
+	 * as long as slow_rsp_threshold is not set way above recommended max
+	 * value (32767 ie 9 hours) and is generally harmless even if wrong
+	 * since only affects debug counters - so leaving the calc as simple
+	 * comparison rather than doing multiple conversions and overflow
+	 * checks
+	 */
+	if ((slow_rsp_threshold != 0) &&
+	    time_after(now, midEntry->when_alloc + (slow_rsp_threshold * HZ)) &&
+	    (midEntry->command != command)) {
+		/*
+		 * smb2slowcmd[NUMBER_OF_SMB2_COMMANDS] counts by command
+		 * NB: le16_to_cpu returns unsigned so can not be negative below
+		 */
+		if (smb_cmd < NUMBER_OF_SMB2_COMMANDS)
+			cifs_stats_inc(&server->smb2slowcmd[smb_cmd]);
+
+		trace_smb3_slow_rsp(smb_cmd, midEntry->mid, midEntry->pid,
+			       midEntry->when_sent, midEntry->when_received);
+		if (cifsFYI & CIFS_TIMER) {
+			pr_debug("slow rsp: cmd %d mid %llu",
+				 midEntry->command, midEntry->mid);
+			cifs_info("A: 0x%lx S: 0x%lx R: 0x%lx\n",
+				  now - midEntry->when_alloc,
+				  now - midEntry->when_sent,
+				  now - midEntry->when_received);
+		}
+	}
+#endif
+	put_task_struct(midEntry->creator);
+
+	mempool_free(midEntry, cifs_mid_poolp);
+}
+
+void
+delete_mid(struct mid_q_entry *mid)
+{
+	spin_lock(&mid->server->mid_lock);
+	if (!(mid->mid_flags & MID_DELETED)) {
+		list_del_init(&mid->qhead);
+		mid->mid_flags |= MID_DELETED;
+	}
+	spin_unlock(&mid->server->mid_lock);
+
+	release_mid(mid);
+}
+
+/*
+ * smb_send_kvec - send an array of kvecs to the server
+ * @server:	Server to send the data to
+ * @smb_msg:	Message to send
+ * @sent:	amount of data sent on socket is stored here
+ *
+ * Our basic "send data to server" function. Should be called with srv_mutex
+ * held. The caller is responsible for handling the results.
+ */
+static int
+smb_send_kvec(struct TCP_Server_Info *server, struct msghdr *smb_msg,
+	      size_t *sent)
+{
+	int rc = 0;
+	int retries = 0;
+	struct socket *ssocket = server->ssocket;
+
+	*sent = 0;
+
+	if (server->noblocksnd)
+		smb_msg->msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
+	else
+		smb_msg->msg_flags = MSG_NOSIGNAL;
+
+	while (msg_data_left(smb_msg)) {
+		/*
+		 * If blocking send, we try 3 times, since each can block
+		 * for 5 seconds. For nonblocking  we have to try more
+		 * but wait increasing amounts of time allowing time for
+		 * socket to clear.  The overall time we wait in either
+		 * case to send on the socket is about 15 seconds.
+		 * Similarly we wait for 15 seconds for a response from
+		 * the server in SendReceive[2] for the server to send
+		 * a response back for most types of requests (except
+		 * SMB Write past end of file which can be slow, and
+		 * blocking lock operations). NFS waits slightly longer
+		 * than CIFS, but this can make it take longer for
+		 * nonresponsive servers to be detected and 15 seconds
+		 * is more than enough time for modern networks to
+		 * send a packet.  In most cases if we fail to send
+		 * after the retries we will kill the socket and
+		 * reconnect which may clear the network problem.
+		 */
+		rc = sock_sendmsg(ssocket, smb_msg);
+		if (rc == -EAGAIN) {
+			retries++;
+			if (retries >= 14 ||
+			    (!server->noblocksnd && (retries > 2))) {
+				cifs_server_dbg(VFS, "sends on sock %p stuck for 15 seconds\n",
+					 ssocket);
+				return -EAGAIN;
+			}
+			msleep(1 << retries);
+			continue;
+		}
+
+		if (rc < 0)
+			return rc;
+
+		if (rc == 0) {
+			/* should never happen, letting socket clear before
+			   retrying is our only obvious option here */
+			cifs_server_dbg(VFS, "tcp sent no data\n");
+			msleep(500);
+			continue;
+		}
+
+		/* send was at least partially successful */
+		*sent += rc;
+		retries = 0; /* in case we get ENOSPC on the next send */
+	}
+	return 0;
+}
+
+unsigned long
+smb_rqst_len(struct TCP_Server_Info *server, struct smb_rqst *rqst)
+{
+	unsigned int i;
+	struct kvec *iov;
+	int nvec;
+	unsigned long buflen = 0;
+
+	if (!is_smb1(server) && rqst->rq_nvec >= 2 &&
+	    rqst->rq_iov[0].iov_len == 4) {
+		iov = &rqst->rq_iov[1];
+		nvec = rqst->rq_nvec - 1;
+	} else {
+		iov = rqst->rq_iov;
+		nvec = rqst->rq_nvec;
+	}
+
+	/* total up iov array first */
+	for (i = 0; i < nvec; i++)
+		buflen += iov[i].iov_len;
+
+	buflen += iov_iter_count(&rqst->rq_iter);
+	return buflen;
+}
+
+static int
+__smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
+		struct smb_rqst *rqst)
+{
+	int rc;
+	struct kvec *iov;
+	int n_vec;
+	unsigned int send_length = 0;
+	unsigned int i, j;
+	sigset_t mask, oldmask;
+	size_t total_len = 0, sent, size;
+	struct socket *ssocket = server->ssocket;
+	struct msghdr smb_msg = {};
+	__be32 rfc1002_marker;
+
+	cifs_in_send_inc(server);
+	if (cifs_rdma_enabled(server)) {
+		/* return -EAGAIN when connecting or reconnecting */
+		rc = -EAGAIN;
+		if (server->smbd_conn)
+			rc = smbd_send(server, num_rqst, rqst);
+		goto smbd_done;
+	}
+
+	rc = -EAGAIN;
+	if (ssocket == NULL)
+		goto out;
+
+	rc = -ERESTARTSYS;
+	if (fatal_signal_pending(current)) {
+		cifs_dbg(FYI, "signal pending before send request\n");
+		goto out;
+	}
+
+	rc = 0;
+	/* cork the socket */
+	tcp_sock_set_cork(ssocket->sk, true);
+
+	for (j = 0; j < num_rqst; j++)
+		send_length += smb_rqst_len(server, &rqst[j]);
+	rfc1002_marker = cpu_to_be32(send_length);
+
+	/*
+	 * We should not allow signals to interrupt the network send because
+	 * any partial send will cause session reconnects thus increasing
+	 * latency of system calls and overload a server with unnecessary
+	 * requests.
+	 */
+
+	sigfillset(&mask);
+	sigprocmask(SIG_BLOCK, &mask, &oldmask);
+
+	/* Generate a rfc1002 marker for SMB2+ */
+	if (!is_smb1(server)) {
+		struct kvec hiov = {
+			.iov_base = &rfc1002_marker,
+			.iov_len  = 4
+		};
+		iov_iter_kvec(&smb_msg.msg_iter, ITER_SOURCE, &hiov, 1, 4);
+		rc = smb_send_kvec(server, &smb_msg, &sent);
+		if (rc < 0)
+			goto unmask;
+
+		total_len += sent;
+		send_length += 4;
+	}
+
+	cifs_dbg(FYI, "Sending smb: smb_len=%u\n", send_length);
+
+	for (j = 0; j < num_rqst; j++) {
+		iov = rqst[j].rq_iov;
+		n_vec = rqst[j].rq_nvec;
+
+		size = 0;
+		for (i = 0; i < n_vec; i++) {
+			dump_smb(iov[i].iov_base, iov[i].iov_len);
+			size += iov[i].iov_len;
+		}
+
+		iov_iter_kvec(&smb_msg.msg_iter, ITER_SOURCE, iov, n_vec, size);
+
+		rc = smb_send_kvec(server, &smb_msg, &sent);
+		if (rc < 0)
+			goto unmask;
+
+		total_len += sent;
+
+		if (iov_iter_count(&rqst[j].rq_iter) > 0) {
+			smb_msg.msg_iter = rqst[j].rq_iter;
+			rc = smb_send_kvec(server, &smb_msg, &sent);
+			if (rc < 0)
+				break;
+			total_len += sent;
+		}
+
+}
+
+unmask:
+	sigprocmask(SIG_SETMASK, &oldmask, NULL);
+
+	/*
+	 * If signal is pending but we have already sent the whole packet to
+	 * the server we need to return success status to allow a corresponding
+	 * mid entry to be kept in the pending requests queue thus allowing
+	 * to handle responses from the server by the client.
+	 *
+	 * If only part of the packet has been sent there is no need to hide
+	 * interrupt because the session will be reconnected anyway, so there
+	 * won't be any response from the server to handle.
+	 */
+
+	if (signal_pending(current) && (total_len != send_length)) {
+		cifs_dbg(FYI, "signal is pending after attempt to send\n");
+		rc = -ERESTARTSYS;
+	}
+
+	/* uncork it */
+	tcp_sock_set_cork(ssocket->sk, false);
+
+	if ((total_len > 0) && (total_len != send_length)) {
+		cifs_dbg(FYI, "partial send (wanted=%u sent=%zu): terminating session\n",
+			 send_length, total_len);
+		/*
+		 * If we have only sent part of an SMB then the next SMB could
+		 * be taken as the remainder of this one. We need to kill the
+		 * socket so the server throws away the partial SMB
+		 */
+		cifs_signal_cifsd_for_reconnect(server, false);
+		trace_smb3_partial_send_reconnect(server->CurrentMid,
+						  server->conn_id, server->hostname);
+	}
+smbd_done:
+	if (rc < 0 && rc != -EINTR)
+		cifs_server_dbg(VFS, "Error %d sending data on socket to server\n",
+			 rc);
+	else if (rc > 0)
+		rc = 0;
+out:
+	cifs_in_send_dec(server);
+	return rc;
+}
+
+struct send_req_vars {
+	struct smb2_transform_hdr tr_hdr;
+	struct smb_rqst rqst[MAX_COMPOUND];
+	struct kvec iov;
+};
+
+static int
+smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
+	      struct smb_rqst *rqst, int flags)
+{
+	struct send_req_vars *vars;
+	struct smb_rqst *cur_rqst;
+	struct kvec *iov;
+	int rc;
+
+	if (!(flags & CIFS_TRANSFORM_REQ))
+		return __smb_send_rqst(server, num_rqst, rqst);
+
+	if (num_rqst > MAX_COMPOUND - 1)
+		return -ENOMEM;
+
+	if (!server->ops->init_transform_rq) {
+		cifs_server_dbg(VFS, "Encryption requested but transform callback is missing\n");
+		return -EIO;
+	}
+
+	vars = kzalloc(sizeof(*vars), GFP_NOFS);
+	if (!vars)
+		return -ENOMEM;
+	cur_rqst = vars->rqst;
+	iov = &vars->iov;
+
+	iov->iov_base = &vars->tr_hdr;
+	iov->iov_len = sizeof(vars->tr_hdr);
+	cur_rqst[0].rq_iov = iov;
+	cur_rqst[0].rq_nvec = 1;
+
+	rc = server->ops->init_transform_rq(server, num_rqst + 1,
+					    &cur_rqst[0], rqst);
+	if (rc)
+		goto out;
+
+	rc = __smb_send_rqst(server, num_rqst + 1, &cur_rqst[0]);
+	smb3_free_compound_rqst(num_rqst, &cur_rqst[1]);
+out:
+	kfree(vars);
+	return rc;
+}
+
+int
+smb_send(struct TCP_Server_Info *server, struct smb_hdr *smb_buffer,
+	 unsigned int smb_buf_length)
+{
+	struct kvec iov[2];
+	struct smb_rqst rqst = { .rq_iov = iov,
+				 .rq_nvec = 2 };
+
+	iov[0].iov_base = smb_buffer;
+	iov[0].iov_len = 4;
+	iov[1].iov_base = (char *)smb_buffer + 4;
+	iov[1].iov_len = smb_buf_length;
+
+	return __smb_send_rqst(server, 1, &rqst);
+}
+
+static int
+wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
+		      const int timeout, const int flags,
+		      unsigned int *instance)
+{
+	long rc;
+	int *credits;
+	int optype;
+	long int t;
+	int scredits, in_flight;
+
+	if (timeout < 0)
+		t = MAX_JIFFY_OFFSET;
+	else
+		t = msecs_to_jiffies(timeout);
+
+	optype = flags & CIFS_OP_MASK;
+
+	*instance = 0;
+
+	credits = server->ops->get_credits_field(server, optype);
+	/* Since an echo is already inflight, no need to wait to send another */
+	if (*credits <= 0 && optype == CIFS_ECHO_OP)
+		return -EAGAIN;
+
+	spin_lock(&server->req_lock);
+	if ((flags & CIFS_TIMEOUT_MASK) == CIFS_NON_BLOCKING) {
+		/* oplock breaks must not be held up */
+		server->in_flight++;
+		if (server->in_flight > server->max_in_flight)
+			server->max_in_flight = server->in_flight;
+		*credits -= 1;
+		*instance = server->reconnect_instance;
+		scredits = *credits;
+		in_flight = server->in_flight;
+		spin_unlock(&server->req_lock);
+
+		trace_smb3_nblk_credits(server->CurrentMid,
+				server->conn_id, server->hostname, scredits, -1, in_flight);
+		cifs_dbg(FYI, "%s: remove %u credits total=%d\n",
+				__func__, 1, scredits);
+
+		return 0;
+	}
+
+	while (1) {
+		spin_unlock(&server->req_lock);
+
+		spin_lock(&server->srv_lock);
+		if (server->tcpStatus == CifsExiting) {
+			spin_unlock(&server->srv_lock);
+			return -ENOENT;
+		}
+		spin_unlock(&server->srv_lock);
+
+		spin_lock(&server->req_lock);
+		if (*credits < num_credits) {
+			scredits = *credits;
+			spin_unlock(&server->req_lock);
+
+			cifs_num_waiters_inc(server);
+			rc = wait_event_killable_timeout(server->request_q,
+				has_credits(server, credits, num_credits), t);
+			cifs_num_waiters_dec(server);
+			if (!rc) {
+				spin_lock(&server->req_lock);
+				scredits = *credits;
+				in_flight = server->in_flight;
+				spin_unlock(&server->req_lock);
+
+				trace_smb3_credit_timeout(server->CurrentMid,
+						server->conn_id, server->hostname, scredits,
+						num_credits, in_flight);
+				cifs_server_dbg(VFS, "wait timed out after %d ms\n",
+						timeout);
+				return -EBUSY;
+			}
+			if (rc == -ERESTARTSYS)
+				return -ERESTARTSYS;
+			spin_lock(&server->req_lock);
+		} else {
+			/*
+			 * For normal commands, reserve the last MAX_COMPOUND
+			 * credits to compound requests.
+			 * Otherwise these compounds could be permanently
+			 * starved for credits by single-credit requests.
+			 *
+			 * To prevent spinning CPU, block this thread until
+			 * there are >MAX_COMPOUND credits available.
+			 * But only do this is we already have a lot of
+			 * credits in flight to avoid triggering this check
+			 * for servers that are slow to hand out credits on
+			 * new sessions.
+			 */
+			if (!optype && num_credits == 1 &&
+			    server->in_flight > 2 * MAX_COMPOUND &&
+			    *credits <= MAX_COMPOUND) {
+				spin_unlock(&server->req_lock);
+
+				cifs_num_waiters_inc(server);
+				rc = wait_event_killable_timeout(
+					server->request_q,
+					has_credits(server, credits,
+						    MAX_COMPOUND + 1),
+					t);
+				cifs_num_waiters_dec(server);
+				if (!rc) {
+					spin_lock(&server->req_lock);
+					scredits = *credits;
+					in_flight = server->in_flight;
+					spin_unlock(&server->req_lock);
+
+					trace_smb3_credit_timeout(
+							server->CurrentMid,
+							server->conn_id, server->hostname,
+							scredits, num_credits, in_flight);
+					cifs_server_dbg(VFS, "wait timed out after %d ms\n",
+							timeout);
+					return -EBUSY;
+				}
+				if (rc == -ERESTARTSYS)
+					return -ERESTARTSYS;
+				spin_lock(&server->req_lock);
+				continue;
+			}
+
+			/*
+			 * Can not count locking commands against total
+			 * as they are allowed to block on server.
+			 */
+
+			/* update # of requests on the wire to server */
+			if ((flags & CIFS_TIMEOUT_MASK) != CIFS_BLOCKING_OP) {
+				*credits -= num_credits;
+				server->in_flight += num_credits;
+				if (server->in_flight > server->max_in_flight)
+					server->max_in_flight = server->in_flight;
+				*instance = server->reconnect_instance;
+			}
+			scredits = *credits;
+			in_flight = server->in_flight;
+			spin_unlock(&server->req_lock);
+
+			trace_smb3_waitff_credits(server->CurrentMid,
+					server->conn_id, server->hostname, scredits,
+					-(num_credits), in_flight);
+			cifs_dbg(FYI, "%s: remove %u credits total=%d\n",
+					__func__, num_credits, scredits);
+			break;
+		}
+	}
+	return 0;
+}
+
+static int
+wait_for_free_request(struct TCP_Server_Info *server, const int flags,
+		      unsigned int *instance)
+{
+	return wait_for_free_credits(server, 1, -1, flags,
+				     instance);
+}
+
+static int
+wait_for_compound_request(struct TCP_Server_Info *server, int num,
+			  const int flags, unsigned int *instance)
+{
+	int *credits;
+	int scredits, in_flight;
+
+	credits = server->ops->get_credits_field(server, flags & CIFS_OP_MASK);
+
+	spin_lock(&server->req_lock);
+	scredits = *credits;
+	in_flight = server->in_flight;
+
+	if (*credits < num) {
+		/*
+		 * If the server is tight on resources or just gives us less
+		 * credits for other reasons (e.g. requests are coming out of
+		 * order and the server delays granting more credits until it
+		 * processes a missing mid) and we exhausted most available
+		 * credits there may be situations when we try to send
+		 * a compound request but we don't have enough credits. At this
+		 * point the client needs to decide if it should wait for
+		 * additional credits or fail the request. If at least one
+		 * request is in flight there is a high probability that the
+		 * server will return enough credits to satisfy this compound
+		 * request.
+		 *
+		 * Return immediately if no requests in flight since we will be
+		 * stuck on waiting for credits.
+		 */
+		if (server->in_flight == 0) {
+			spin_unlock(&server->req_lock);
+			trace_smb3_insufficient_credits(server->CurrentMid,
+					server->conn_id, server->hostname, scredits,
+					num, in_flight);
+			cifs_dbg(FYI, "%s: %d requests in flight, needed %d total=%d\n",
+					__func__, in_flight, num, scredits);
+			return -EDEADLK;
+		}
+	}
+	spin_unlock(&server->req_lock);
+
+	return wait_for_free_credits(server, num, 60000, flags,
+				     instance);
+}
+
+int
+cifs_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
+		      unsigned int *num, struct cifs_credits *credits)
+{
+	*num = size;
+	credits->value = 0;
+	credits->instance = server->reconnect_instance;
+	return 0;
+}
+
+static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
+			struct mid_q_entry **ppmidQ)
+{
+	spin_lock(&ses->ses_lock);
+	if (ses->ses_status == SES_NEW) {
+		if ((in_buf->Command != SMB_COM_SESSION_SETUP_ANDX) &&
+			(in_buf->Command != SMB_COM_NEGOTIATE)) {
+			spin_unlock(&ses->ses_lock);
+			return -EAGAIN;
+		}
+		/* else ok - we are setting up session */
+	}
+
+	if (ses->ses_status == SES_EXITING) {
+		/* check if SMB session is bad because we are setting it up */
+		if (in_buf->Command != SMB_COM_LOGOFF_ANDX) {
+			spin_unlock(&ses->ses_lock);
+			return -EAGAIN;
+		}
+		/* else ok - we are shutting down session */
+	}
+	spin_unlock(&ses->ses_lock);
+
+	*ppmidQ = alloc_mid(in_buf, ses->server);
+	if (*ppmidQ == NULL)
+		return -ENOMEM;
+	spin_lock(&ses->server->mid_lock);
+	list_add_tail(&(*ppmidQ)->qhead, &ses->server->pending_mid_q);
+	spin_unlock(&ses->server->mid_lock);
+	return 0;
+}
+
+static int
+wait_for_response(struct TCP_Server_Info *server, struct mid_q_entry *midQ)
+{
+	int error;
+
+	error = wait_event_state(server->response_q,
+				 midQ->mid_state != MID_REQUEST_SUBMITTED &&
+				 midQ->mid_state != MID_RESPONSE_RECEIVED,
+				 (TASK_KILLABLE|TASK_FREEZABLE_UNSAFE));
+	if (error < 0)
+		return -ERESTARTSYS;
+
+	return 0;
+}
+
+struct mid_q_entry *
+cifs_setup_async_request(struct TCP_Server_Info *server, struct smb_rqst *rqst)
+{
+	int rc;
+	struct smb_hdr *hdr = (struct smb_hdr *)rqst->rq_iov[0].iov_base;
+	struct mid_q_entry *mid;
+
+	if (rqst->rq_iov[0].iov_len != 4 ||
+	    rqst->rq_iov[0].iov_base + 4 != rqst->rq_iov[1].iov_base)
+		return ERR_PTR(-EIO);
+
+	/* enable signing if server requires it */
+	if (server->sign)
+		hdr->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
+
+	mid = alloc_mid(hdr, server);
+	if (mid == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	rc = cifs_sign_rqst(rqst, server, &mid->sequence_number);
+	if (rc) {
+		release_mid(mid);
+		return ERR_PTR(rc);
+	}
+
+	return mid;
+}
+
+/*
+ * Send a SMB request and set the callback function in the mid to handle
+ * the result. Caller is responsible for dealing with timeouts.
+ */
+int
+cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
+		mid_receive_t *receive, mid_callback_t *callback,
+		mid_handle_t *handle, void *cbdata, const int flags,
+		const struct cifs_credits *exist_credits)
+{
+	int rc;
+	struct mid_q_entry *mid;
+	struct cifs_credits credits = { .value = 0, .instance = 0 };
+	unsigned int instance;
+	int optype;
+
+	optype = flags & CIFS_OP_MASK;
+
+	if ((flags & CIFS_HAS_CREDITS) == 0) {
+		rc = wait_for_free_request(server, flags, &instance);
+		if (rc)
+			return rc;
+		credits.value = 1;
+		credits.instance = instance;
+	} else
+		instance = exist_credits->instance;
+
+	cifs_server_lock(server);
+
+	/*
+	 * We can't use credits obtained from the previous session to send this
+	 * request. Check if there were reconnects after we obtained credits and
+	 * return -EAGAIN in such cases to let callers handle it.
+	 */
+	if (instance != server->reconnect_instance) {
+		cifs_server_unlock(server);
+		add_credits_and_wake_if(server, &credits, optype);
+		return -EAGAIN;
+	}
+
+	mid = server->ops->setup_async_request(server, rqst);
+	if (IS_ERR(mid)) {
+		cifs_server_unlock(server);
+		add_credits_and_wake_if(server, &credits, optype);
+		return PTR_ERR(mid);
+	}
+
+	mid->receive = receive;
+	mid->callback = callback;
+	mid->callback_data = cbdata;
+	mid->handle = handle;
+	mid->mid_state = MID_REQUEST_SUBMITTED;
+
+	/* put it on the pending_mid_q */
+	spin_lock(&server->mid_lock);
+	list_add_tail(&mid->qhead, &server->pending_mid_q);
+	spin_unlock(&server->mid_lock);
+
+	/*
+	 * Need to store the time in mid before calling I/O. For call_async,
+	 * I/O response may come back and free the mid entry on another thread.
+	 */
+	cifs_save_when_sent(mid);
+	rc = smb_send_rqst(server, 1, rqst, flags);
+
+	if (rc < 0) {
+		revert_current_mid(server, mid->credits);
+		server->sequence_number -= 2;
+		delete_mid(mid);
+	}
+
+	cifs_server_unlock(server);
+
+	if (rc == 0)
+		return 0;
+
+	add_credits_and_wake_if(server, &credits, optype);
+	return rc;
+}
+
+/*
+ *
+ * Send an SMB Request.  No response info (other than return code)
+ * needs to be parsed.
+ *
+ * flags indicate the type of request buffer and how long to wait
+ * and whether to log NT STATUS code (error) before mapping it to POSIX error
+ *
+ */
+int
+SendReceiveNoRsp(const unsigned int xid, struct cifs_ses *ses,
+		 char *in_buf, int flags)
+{
+	int rc;
+	struct kvec iov[1];
+	struct kvec rsp_iov;
+	int resp_buf_type;
+
+	iov[0].iov_base = in_buf;
+	iov[0].iov_len = get_rfc1002_length(in_buf) + 4;
+	flags |= CIFS_NO_RSP_BUF;
+	rc = SendReceive2(xid, ses, iov, 1, &resp_buf_type, flags, &rsp_iov);
+	cifs_dbg(NOISY, "SendRcvNoRsp flags %d rc %d\n", flags, rc);
+
+	return rc;
+}
+
+static int
+cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
+{
+	int rc = 0;
+
+	cifs_dbg(FYI, "%s: cmd=%d mid=%llu state=%d\n",
+		 __func__, le16_to_cpu(mid->command), mid->mid, mid->mid_state);
+
+	spin_lock(&server->mid_lock);
+	switch (mid->mid_state) {
+	case MID_RESPONSE_READY:
+		spin_unlock(&server->mid_lock);
+		return rc;
+	case MID_RETRY_NEEDED:
+		rc = -EAGAIN;
+		break;
+	case MID_RESPONSE_MALFORMED:
+		rc = -EIO;
+		break;
+	case MID_SHUTDOWN:
+		rc = -EHOSTDOWN;
+		break;
+	default:
+		if (!(mid->mid_flags & MID_DELETED)) {
+			list_del_init(&mid->qhead);
+			mid->mid_flags |= MID_DELETED;
+		}
+		cifs_server_dbg(VFS, "%s: invalid mid state mid=%llu state=%d\n",
+			 __func__, mid->mid, mid->mid_state);
+		rc = -EIO;
+	}
+	spin_unlock(&server->mid_lock);
+
+	release_mid(mid);
+	return rc;
+}
+
+static inline int
+send_cancel(struct TCP_Server_Info *server, struct smb_rqst *rqst,
+	    struct mid_q_entry *mid)
+{
+	return server->ops->send_cancel ?
+				server->ops->send_cancel(server, rqst, mid) : 0;
+}
+
+int
+cifs_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
+		   bool log_error)
+{
+	unsigned int len = get_rfc1002_length(mid->resp_buf) + 4;
+
+	dump_smb(mid->resp_buf, min_t(u32, 92, len));
+
+	/* convert the length into a more usable form */
+	if (server->sign) {
+		struct kvec iov[2];
+		int rc = 0;
+		struct smb_rqst rqst = { .rq_iov = iov,
+					 .rq_nvec = 2 };
+
+		iov[0].iov_base = mid->resp_buf;
+		iov[0].iov_len = 4;
+		iov[1].iov_base = (char *)mid->resp_buf + 4;
+		iov[1].iov_len = len - 4;
+		/* FIXME: add code to kill session */
+		rc = cifs_verify_signature(&rqst, server,
+					   mid->sequence_number);
+		if (rc)
+			cifs_server_dbg(VFS, "SMB signature verification returned error = %d\n",
+				 rc);
+	}
+
+	/* BB special case reconnect tid and uid here? */
+	return map_and_check_smb_error(mid, log_error);
+}
+
+struct mid_q_entry *
+cifs_setup_request(struct cifs_ses *ses, struct TCP_Server_Info *ignored,
+		   struct smb_rqst *rqst)
+{
+	int rc;
+	struct smb_hdr *hdr = (struct smb_hdr *)rqst->rq_iov[0].iov_base;
+	struct mid_q_entry *mid;
+
+	if (rqst->rq_iov[0].iov_len != 4 ||
+	    rqst->rq_iov[0].iov_base + 4 != rqst->rq_iov[1].iov_base)
+		return ERR_PTR(-EIO);
+
+	rc = allocate_mid(ses, hdr, &mid);
+	if (rc)
+		return ERR_PTR(rc);
+	rc = cifs_sign_rqst(rqst, ses->server, &mid->sequence_number);
+	if (rc) {
+		delete_mid(mid);
+		return ERR_PTR(rc);
+	}
+	return mid;
+}
+
+static void
+cifs_compound_callback(struct mid_q_entry *mid)
+{
+	struct TCP_Server_Info *server = mid->server;
+	struct cifs_credits credits;
+
+	credits.value = server->ops->get_credits(mid);
+	credits.instance = server->reconnect_instance;
+
+	add_credits(server, &credits, mid->optype);
+
+	if (mid->mid_state == MID_RESPONSE_RECEIVED)
+		mid->mid_state = MID_RESPONSE_READY;
+}
+
+static void
+cifs_compound_last_callback(struct mid_q_entry *mid)
+{
+	cifs_compound_callback(mid);
+	cifs_wake_up_task(mid);
+}
+
+static void
+cifs_cancelled_callback(struct mid_q_entry *mid)
+{
+	cifs_compound_callback(mid);
+	release_mid(mid);
+}
+
+/*
+ * Return a channel (master if none) of @ses that can be used to send
+ * regular requests.
+ *
+ * If we are currently binding a new channel (negprot/sess.setup),
+ * return the new incomplete channel.
+ */
+struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses)
+{
+	uint index = 0;
+	unsigned int min_in_flight = UINT_MAX, max_in_flight = 0;
+	struct TCP_Server_Info *server = NULL;
+	int i;
+
+	if (!ses)
+		return NULL;
+
+	spin_lock(&ses->chan_lock);
+	for (i = 0; i < ses->chan_count; i++) {
+		server = ses->chans[i].server;
+		if (!server || server->terminate)
+			continue;
+
+		/*
+		 * strictly speaking, we should pick up req_lock to read
+		 * server->in_flight. But it shouldn't matter much here if we
+		 * race while reading this data. The worst that can happen is
+		 * that we could use a channel that's not least loaded. Avoiding
+		 * taking the lock could help reduce wait time, which is
+		 * important for this function
+		 */
+		if (server->in_flight < min_in_flight) {
+			min_in_flight = server->in_flight;
+			index = i;
+		}
+		if (server->in_flight > max_in_flight)
+			max_in_flight = server->in_flight;
+	}
+
+	/* if all channels are equally loaded, fall back to round-robin */
+	if (min_in_flight == max_in_flight) {
+		index = (uint)atomic_inc_return(&ses->chan_seq);
+		index %= ses->chan_count;
+	}
+	spin_unlock(&ses->chan_lock);
+
+	return ses->chans[index].server;
+}
+
+int
+compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
+		   struct TCP_Server_Info *server,
+		   const int flags, const int num_rqst, struct smb_rqst *rqst,
+		   int *resp_buf_type, struct kvec *resp_iov)
+{
+	int i, j, optype, rc = 0;
+	struct mid_q_entry *midQ[MAX_COMPOUND];
+	bool cancelled_mid[MAX_COMPOUND] = {false};
+	struct cifs_credits credits[MAX_COMPOUND] = {
+		{ .value = 0, .instance = 0 }
+	};
+	unsigned int instance;
+	char *buf;
+
+	optype = flags & CIFS_OP_MASK;
+
+	for (i = 0; i < num_rqst; i++)
+		resp_buf_type[i] = CIFS_NO_BUFFER;  /* no response buf yet */
+
+	if (!ses || !ses->server || !server) {
+		cifs_dbg(VFS, "Null session\n");
+		return -EIO;
+	}
+
+	spin_lock(&server->srv_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&server->srv_lock);
+		return -ENOENT;
+	}
+	spin_unlock(&server->srv_lock);
+
+	/*
+	 * Wait for all the requests to become available.
+	 * This approach still leaves the possibility to be stuck waiting for
+	 * credits if the server doesn't grant credits to the outstanding
+	 * requests and if the client is completely idle, not generating any
+	 * other requests.
+	 * This can be handled by the eventual session reconnect.
+	 */
+	rc = wait_for_compound_request(server, num_rqst, flags,
+				       &instance);
+	if (rc)
+		return rc;
+
+	for (i = 0; i < num_rqst; i++) {
+		credits[i].value = 1;
+		credits[i].instance = instance;
+	}
+
+	/*
+	 * Make sure that we sign in the same order that we send on this socket
+	 * and avoid races inside tcp sendmsg code that could cause corruption
+	 * of smb data.
+	 */
+
+	cifs_server_lock(server);
+
+	/*
+	 * All the parts of the compound chain belong obtained credits from the
+	 * same session. We can not use credits obtained from the previous
+	 * session to send this request. Check if there were reconnects after
+	 * we obtained credits and return -EAGAIN in such cases to let callers
+	 * handle it.
+	 */
+	if (instance != server->reconnect_instance) {
+		cifs_server_unlock(server);
+		for (j = 0; j < num_rqst; j++)
+			add_credits(server, &credits[j], optype);
+		return -EAGAIN;
+	}
+
+	for (i = 0; i < num_rqst; i++) {
+		midQ[i] = server->ops->setup_request(ses, server, &rqst[i]);
+		if (IS_ERR(midQ[i])) {
+			revert_current_mid(server, i);
+			for (j = 0; j < i; j++)
+				delete_mid(midQ[j]);
+			cifs_server_unlock(server);
+
+			/* Update # of requests on wire to server */
+			for (j = 0; j < num_rqst; j++)
+				add_credits(server, &credits[j], optype);
+			return PTR_ERR(midQ[i]);
+		}
+
+		midQ[i]->mid_state = MID_REQUEST_SUBMITTED;
+		midQ[i]->optype = optype;
+		/*
+		 * Invoke callback for every part of the compound chain
+		 * to calculate credits properly. Wake up this thread only when
+		 * the last element is received.
+		 */
+		if (i < num_rqst - 1)
+			midQ[i]->callback = cifs_compound_callback;
+		else
+			midQ[i]->callback = cifs_compound_last_callback;
+	}
+	rc = smb_send_rqst(server, num_rqst, rqst, flags);
+
+	for (i = 0; i < num_rqst; i++)
+		cifs_save_when_sent(midQ[i]);
+
+	if (rc < 0) {
+		revert_current_mid(server, num_rqst);
+		server->sequence_number -= 2;
+	}
+
+	cifs_server_unlock(server);
+
+	/*
+	 * If sending failed for some reason or it is an oplock break that we
+	 * will not receive a response to - return credits back
+	 */
+	if (rc < 0 || (flags & CIFS_NO_SRV_RSP)) {
+		for (i = 0; i < num_rqst; i++)
+			add_credits(server, &credits[i], optype);
+		goto out;
+	}
+
+	/*
+	 * At this point the request is passed to the network stack - we assume
+	 * that any credits taken from the server structure on the client have
+	 * been spent and we can't return them back. Once we receive responses
+	 * we will collect credits granted by the server in the mid callbacks
+	 * and add those credits to the server structure.
+	 */
+
+	/*
+	 * Compounding is never used during session establish.
+	 */
+	spin_lock(&ses->ses_lock);
+	if ((ses->ses_status == SES_NEW) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
+		spin_unlock(&ses->ses_lock);
+
+		cifs_server_lock(server);
+		smb311_update_preauth_hash(ses, server, rqst[0].rq_iov, rqst[0].rq_nvec);
+		cifs_server_unlock(server);
+
+		spin_lock(&ses->ses_lock);
+	}
+	spin_unlock(&ses->ses_lock);
+
+	for (i = 0; i < num_rqst; i++) {
+		rc = wait_for_response(server, midQ[i]);
+		if (rc != 0)
+			break;
+	}
+	if (rc != 0) {
+		for (; i < num_rqst; i++) {
+			cifs_server_dbg(FYI, "Cancelling wait for mid %llu cmd: %d\n",
+				 midQ[i]->mid, le16_to_cpu(midQ[i]->command));
+			send_cancel(server, &rqst[i], midQ[i]);
+			spin_lock(&server->mid_lock);
+			midQ[i]->mid_flags |= MID_WAIT_CANCELLED;
+			if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED ||
+			    midQ[i]->mid_state == MID_RESPONSE_RECEIVED) {
+				midQ[i]->callback = cifs_cancelled_callback;
+				cancelled_mid[i] = true;
+				credits[i].value = 0;
+			}
+			spin_unlock(&server->mid_lock);
+		}
+	}
+
+	for (i = 0; i < num_rqst; i++) {
+		if (rc < 0)
+			goto out;
+
+		rc = cifs_sync_mid_result(midQ[i], server);
+		if (rc != 0) {
+			/* mark this mid as cancelled to not free it below */
+			cancelled_mid[i] = true;
+			goto out;
+		}
+
+		if (!midQ[i]->resp_buf ||
+		    midQ[i]->mid_state != MID_RESPONSE_READY) {
+			rc = -EIO;
+			cifs_dbg(FYI, "Bad MID state?\n");
+			goto out;
+		}
+
+		buf = (char *)midQ[i]->resp_buf;
+		resp_iov[i].iov_base = buf;
+		resp_iov[i].iov_len = midQ[i]->resp_buf_size +
+			HEADER_PREAMBLE_SIZE(server);
+
+		if (midQ[i]->large_buf)
+			resp_buf_type[i] = CIFS_LARGE_BUFFER;
+		else
+			resp_buf_type[i] = CIFS_SMALL_BUFFER;
+
+		rc = server->ops->check_receive(midQ[i], server,
+						     flags & CIFS_LOG_ERROR);
+
+		/* mark it so buf will not be freed by delete_mid */
+		if ((flags & CIFS_NO_RSP_BUF) == 0)
+			midQ[i]->resp_buf = NULL;
+
+	}
+
+	/*
+	 * Compounding is never used during session establish.
+	 */
+	spin_lock(&ses->ses_lock);
+	if ((ses->ses_status == SES_NEW) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
+		struct kvec iov = {
+			.iov_base = resp_iov[0].iov_base,
+			.iov_len = resp_iov[0].iov_len
+		};
+		spin_unlock(&ses->ses_lock);
+		cifs_server_lock(server);
+		smb311_update_preauth_hash(ses, server, &iov, 1);
+		cifs_server_unlock(server);
+		spin_lock(&ses->ses_lock);
+	}
+	spin_unlock(&ses->ses_lock);
+
+out:
+	/*
+	 * This will dequeue all mids. After this it is important that the
+	 * demultiplex_thread will not process any of these mids any futher.
+	 * This is prevented above by using a noop callback that will not
+	 * wake this thread except for the very last PDU.
+	 */
+	for (i = 0; i < num_rqst; i++) {
+		if (!cancelled_mid[i])
+			delete_mid(midQ[i]);
+	}
+
+	return rc;
+}
+
+int
+cifs_send_recv(const unsigned int xid, struct cifs_ses *ses,
+	       struct TCP_Server_Info *server,
+	       struct smb_rqst *rqst, int *resp_buf_type, const int flags,
+	       struct kvec *resp_iov)
+{
+	return compound_send_recv(xid, ses, server, flags, 1,
+				  rqst, resp_buf_type, resp_iov);
+}
+
+int
+SendReceive2(const unsigned int xid, struct cifs_ses *ses,
+	     struct kvec *iov, int n_vec, int *resp_buf_type /* ret */,
+	     const int flags, struct kvec *resp_iov)
+{
+	struct smb_rqst rqst;
+	struct kvec s_iov[CIFS_MAX_IOV_SIZE], *new_iov;
+	int rc;
+
+	if (n_vec + 1 > CIFS_MAX_IOV_SIZE) {
+		new_iov = kmalloc_array(n_vec + 1, sizeof(struct kvec),
+					GFP_KERNEL);
+		if (!new_iov) {
+			/* otherwise cifs_send_recv below sets resp_buf_type */
+			*resp_buf_type = CIFS_NO_BUFFER;
+			return -ENOMEM;
+		}
+	} else
+		new_iov = s_iov;
+
+	/* 1st iov is a RFC1001 length followed by the rest of the packet */
+	memcpy(new_iov + 1, iov, (sizeof(struct kvec) * n_vec));
+
+	new_iov[0].iov_base = new_iov[1].iov_base;
+	new_iov[0].iov_len = 4;
+	new_iov[1].iov_base += 4;
+	new_iov[1].iov_len -= 4;
+
+	memset(&rqst, 0, sizeof(struct smb_rqst));
+	rqst.rq_iov = new_iov;
+	rqst.rq_nvec = n_vec + 1;
+
+	rc = cifs_send_recv(xid, ses, ses->server,
+			    &rqst, resp_buf_type, flags, resp_iov);
+	if (n_vec + 1 > CIFS_MAX_IOV_SIZE)
+		kfree(new_iov);
+	return rc;
+}
+
+int
+SendReceive(const unsigned int xid, struct cifs_ses *ses,
+	    struct smb_hdr *in_buf, struct smb_hdr *out_buf,
+	    int *pbytes_returned, const int flags)
+{
+	int rc = 0;
+	struct mid_q_entry *midQ;
+	unsigned int len = be32_to_cpu(in_buf->smb_buf_length);
+	struct kvec iov = { .iov_base = in_buf, .iov_len = len };
+	struct smb_rqst rqst = { .rq_iov = &iov, .rq_nvec = 1 };
+	struct cifs_credits credits = { .value = 1, .instance = 0 };
+	struct TCP_Server_Info *server;
+
+	if (ses == NULL) {
+		cifs_dbg(VFS, "Null smb session\n");
+		return -EIO;
+	}
+	server = ses->server;
+	if (server == NULL) {
+		cifs_dbg(VFS, "Null tcp session\n");
+		return -EIO;
+	}
+
+	spin_lock(&server->srv_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&server->srv_lock);
+		return -ENOENT;
+	}
+	spin_unlock(&server->srv_lock);
+
+	/* Ensure that we do not send more than 50 overlapping requests
+	   to the same server. We may make this configurable later or
+	   use ses->maxReq */
+
+	if (len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) {
+		cifs_server_dbg(VFS, "Invalid length, greater than maximum frame, %d\n",
+				len);
+		return -EIO;
+	}
+
+	rc = wait_for_free_request(server, flags, &credits.instance);
+	if (rc)
+		return rc;
+
+	/* make sure that we sign in the same order that we send on this socket
+	   and avoid races inside tcp sendmsg code that could cause corruption
+	   of smb data */
+
+	cifs_server_lock(server);
+
+	rc = allocate_mid(ses, in_buf, &midQ);
+	if (rc) {
+		cifs_server_unlock(server);
+		/* Update # of requests on wire to server */
+		add_credits(server, &credits, 0);
+		return rc;
+	}
+
+	rc = cifs_sign_smb(in_buf, server, &midQ->sequence_number);
+	if (rc) {
+		cifs_server_unlock(server);
+		goto out;
+	}
+
+	midQ->mid_state = MID_REQUEST_SUBMITTED;
+
+	rc = smb_send(server, in_buf, len);
+	cifs_save_when_sent(midQ);
+
+	if (rc < 0)
+		server->sequence_number -= 2;
+
+	cifs_server_unlock(server);
+
+	if (rc < 0)
+		goto out;
+
+	rc = wait_for_response(server, midQ);
+	if (rc != 0) {
+		send_cancel(server, &rqst, midQ);
+		spin_lock(&server->mid_lock);
+		if (midQ->mid_state == MID_REQUEST_SUBMITTED ||
+		    midQ->mid_state == MID_RESPONSE_RECEIVED) {
+			/* no longer considered to be "in-flight" */
+			midQ->callback = release_mid;
+			spin_unlock(&server->mid_lock);
+			add_credits(server, &credits, 0);
+			return rc;
+		}
+		spin_unlock(&server->mid_lock);
+	}
+
+	rc = cifs_sync_mid_result(midQ, server);
+	if (rc != 0) {
+		add_credits(server, &credits, 0);
+		return rc;
+	}
+
+	if (!midQ->resp_buf || !out_buf ||
+	    midQ->mid_state != MID_RESPONSE_READY) {
+		rc = -EIO;
+		cifs_server_dbg(VFS, "Bad MID state?\n");
+		goto out;
+	}
+
+	*pbytes_returned = get_rfc1002_length(midQ->resp_buf);
+	memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
+	rc = cifs_check_receive(midQ, server, 0);
+out:
+	delete_mid(midQ);
+	add_credits(server, &credits, 0);
+
+	return rc;
+}
+
+/* We send a LOCKINGX_CANCEL_LOCK to cause the Windows
+   blocking lock to return. */
+
+static int
+send_lock_cancel(const unsigned int xid, struct cifs_tcon *tcon,
+			struct smb_hdr *in_buf,
+			struct smb_hdr *out_buf)
+{
+	int bytes_returned;
+	struct cifs_ses *ses = tcon->ses;
+	LOCK_REQ *pSMB = (LOCK_REQ *)in_buf;
+
+	/* We just modify the current in_buf to change
+	   the type of lock from LOCKING_ANDX_SHARED_LOCK
+	   or LOCKING_ANDX_EXCLUSIVE_LOCK to
+	   LOCKING_ANDX_CANCEL_LOCK. */
+
+	pSMB->LockType = LOCKING_ANDX_CANCEL_LOCK|LOCKING_ANDX_LARGE_FILES;
+	pSMB->Timeout = 0;
+	pSMB->hdr.Mid = get_next_mid(ses->server);
+
+	return SendReceive(xid, ses, in_buf, out_buf,
+			&bytes_returned, 0);
+}
+
+int
+SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
+	    struct smb_hdr *in_buf, struct smb_hdr *out_buf,
+	    int *pbytes_returned)
+{
+	int rc = 0;
+	int rstart = 0;
+	struct mid_q_entry *midQ;
+	struct cifs_ses *ses;
+	unsigned int len = be32_to_cpu(in_buf->smb_buf_length);
+	struct kvec iov = { .iov_base = in_buf, .iov_len = len };
+	struct smb_rqst rqst = { .rq_iov = &iov, .rq_nvec = 1 };
+	unsigned int instance;
+	struct TCP_Server_Info *server;
+
+	if (tcon == NULL || tcon->ses == NULL) {
+		cifs_dbg(VFS, "Null smb session\n");
+		return -EIO;
+	}
+	ses = tcon->ses;
+	server = ses->server;
+
+	if (server == NULL) {
+		cifs_dbg(VFS, "Null tcp session\n");
+		return -EIO;
+	}
+
+	spin_lock(&server->srv_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&server->srv_lock);
+		return -ENOENT;
+	}
+	spin_unlock(&server->srv_lock);
+
+	/* Ensure that we do not send more than 50 overlapping requests
+	   to the same server. We may make this configurable later or
+	   use ses->maxReq */
+
+	if (len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) {
+		cifs_tcon_dbg(VFS, "Invalid length, greater than maximum frame, %d\n",
+			      len);
+		return -EIO;
+	}
+
+	rc = wait_for_free_request(server, CIFS_BLOCKING_OP, &instance);
+	if (rc)
+		return rc;
+
+	/* make sure that we sign in the same order that we send on this socket
+	   and avoid races inside tcp sendmsg code that could cause corruption
+	   of smb data */
+
+	cifs_server_lock(server);
+
+	rc = allocate_mid(ses, in_buf, &midQ);
+	if (rc) {
+		cifs_server_unlock(server);
+		return rc;
+	}
+
+	rc = cifs_sign_smb(in_buf, server, &midQ->sequence_number);
+	if (rc) {
+		delete_mid(midQ);
+		cifs_server_unlock(server);
+		return rc;
+	}
+
+	midQ->mid_state = MID_REQUEST_SUBMITTED;
+	rc = smb_send(server, in_buf, len);
+	cifs_save_when_sent(midQ);
+
+	if (rc < 0)
+		server->sequence_number -= 2;
+
+	cifs_server_unlock(server);
+
+	if (rc < 0) {
+		delete_mid(midQ);
+		return rc;
+	}
+
+	/* Wait for a reply - allow signals to interrupt. */
+	rc = wait_event_interruptible(server->response_q,
+		(!(midQ->mid_state == MID_REQUEST_SUBMITTED ||
+		   midQ->mid_state == MID_RESPONSE_RECEIVED)) ||
+		((server->tcpStatus != CifsGood) &&
+		 (server->tcpStatus != CifsNew)));
+
+	/* Were we interrupted by a signal ? */
+	spin_lock(&server->srv_lock);
+	if ((rc == -ERESTARTSYS) &&
+		(midQ->mid_state == MID_REQUEST_SUBMITTED ||
+		 midQ->mid_state == MID_RESPONSE_RECEIVED) &&
+		((server->tcpStatus == CifsGood) ||
+		 (server->tcpStatus == CifsNew))) {
+		spin_unlock(&server->srv_lock);
+
+		if (in_buf->Command == SMB_COM_TRANSACTION2) {
+			/* POSIX lock. We send a NT_CANCEL SMB to cause the
+			   blocking lock to return. */
+			rc = send_cancel(server, &rqst, midQ);
+			if (rc) {
+				delete_mid(midQ);
+				return rc;
+			}
+		} else {
+			/* Windows lock. We send a LOCKINGX_CANCEL_LOCK
+			   to cause the blocking lock to return. */
+
+			rc = send_lock_cancel(xid, tcon, in_buf, out_buf);
+
+			/* If we get -ENOLCK back the lock may have
+			   already been removed. Don't exit in this case. */
+			if (rc && rc != -ENOLCK) {
+				delete_mid(midQ);
+				return rc;
+			}
+		}
+
+		rc = wait_for_response(server, midQ);
+		if (rc) {
+			send_cancel(server, &rqst, midQ);
+			spin_lock(&server->mid_lock);
+			if (midQ->mid_state == MID_REQUEST_SUBMITTED ||
+			    midQ->mid_state == MID_RESPONSE_RECEIVED) {
+				/* no longer considered to be "in-flight" */
+				midQ->callback = release_mid;
+				spin_unlock(&server->mid_lock);
+				return rc;
+			}
+			spin_unlock(&server->mid_lock);
+		}
+
+		/* We got the response - restart system call. */
+		rstart = 1;
+		spin_lock(&server->srv_lock);
+	}
+	spin_unlock(&server->srv_lock);
+
+	rc = cifs_sync_mid_result(midQ, server);
+	if (rc != 0)
+		return rc;
+
+	/* rcvd frame is ok */
+	if (out_buf == NULL || midQ->mid_state != MID_RESPONSE_READY) {
+		rc = -EIO;
+		cifs_tcon_dbg(VFS, "Bad MID state?\n");
+		goto out;
+	}
+
+	*pbytes_returned = get_rfc1002_length(midQ->resp_buf);
+	memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
+	rc = cifs_check_receive(midQ, server, 0);
+out:
+	delete_mid(midQ);
+	if (rstart && rc == -EACCES)
+		return -ERESTARTSYS;
+	return rc;
+}
+
+/*
+ * Discard any remaining data in the current SMB. To do this, we borrow the
+ * current bigbuf.
+ */
+int
+cifs_discard_remaining_data(struct TCP_Server_Info *server)
+{
+	unsigned int rfclen = server->pdu_size;
+	size_t remaining = rfclen + HEADER_PREAMBLE_SIZE(server) -
+		server->total_read;
+
+	while (remaining > 0) {
+		ssize_t length;
+
+		length = cifs_discard_from_socket(server,
+				min_t(size_t, remaining,
+				      CIFSMaxBufSize + MAX_HEADER_SIZE(server)));
+		if (length < 0)
+			return length;
+		server->total_read += length;
+		remaining -= length;
+	}
+
+	return 0;
+}
+
+static int
+__cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid,
+		     bool malformed)
+{
+	int length;
+
+	length = cifs_discard_remaining_data(server);
+	dequeue_mid(mid, malformed);
+	mid->resp_buf = server->smallbuf;
+	server->smallbuf = NULL;
+	return length;
+}
+
+static int
+cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+{
+	struct cifs_readdata *rdata = mid->callback_data;
+
+	return  __cifs_readv_discard(server, mid, rdata->result);
+}
+
+int
+cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+{
+	int length, len;
+	unsigned int data_offset, data_len;
+	struct cifs_readdata *rdata = mid->callback_data;
+	char *buf = server->smallbuf;
+	unsigned int buflen = server->pdu_size + HEADER_PREAMBLE_SIZE(server);
+	bool use_rdma_mr = false;
+
+	cifs_dbg(FYI, "%s: mid=%llu offset=%llu bytes=%u\n",
+		 __func__, mid->mid, rdata->offset, rdata->bytes);
+
+	/*
+	 * read the rest of READ_RSP header (sans Data array), or whatever we
+	 * can if there's not enough data. At this point, we've read down to
+	 * the Mid.
+	 */
+	len = min_t(unsigned int, buflen, server->vals->read_rsp_size) -
+							HEADER_SIZE(server) + 1;
+
+	length = cifs_read_from_socket(server,
+				       buf + HEADER_SIZE(server) - 1, len);
+	if (length < 0)
+		return length;
+	server->total_read += length;
+
+	if (server->ops->is_session_expired &&
+	    server->ops->is_session_expired(buf)) {
+		cifs_reconnect(server, true);
+		return -1;
+	}
+
+	if (server->ops->is_status_pending &&
+	    server->ops->is_status_pending(buf, server)) {
+		cifs_discard_remaining_data(server);
+		return -1;
+	}
+
+	/* set up first two iov for signature check and to get credits */
+	rdata->iov[0].iov_base = buf;
+	rdata->iov[0].iov_len = HEADER_PREAMBLE_SIZE(server);
+	rdata->iov[1].iov_base = buf + HEADER_PREAMBLE_SIZE(server);
+	rdata->iov[1].iov_len =
+		server->total_read - HEADER_PREAMBLE_SIZE(server);
+	cifs_dbg(FYI, "0: iov_base=%p iov_len=%zu\n",
+		 rdata->iov[0].iov_base, rdata->iov[0].iov_len);
+	cifs_dbg(FYI, "1: iov_base=%p iov_len=%zu\n",
+		 rdata->iov[1].iov_base, rdata->iov[1].iov_len);
+
+	/* Was the SMB read successful? */
+	rdata->result = server->ops->map_error(buf, false);
+	if (rdata->result != 0) {
+		cifs_dbg(FYI, "%s: server returned error %d\n",
+			 __func__, rdata->result);
+		/* normal error on read response */
+		return __cifs_readv_discard(server, mid, false);
+	}
+
+	/* Is there enough to get to the rest of the READ_RSP header? */
+	if (server->total_read < server->vals->read_rsp_size) {
+		cifs_dbg(FYI, "%s: server returned short header. got=%u expected=%zu\n",
+			 __func__, server->total_read,
+			 server->vals->read_rsp_size);
+		rdata->result = -EIO;
+		return cifs_readv_discard(server, mid);
+	}
+
+	data_offset = server->ops->read_data_offset(buf) +
+		HEADER_PREAMBLE_SIZE(server);
+	if (data_offset < server->total_read) {
+		/*
+		 * win2k8 sometimes sends an offset of 0 when the read
+		 * is beyond the EOF. Treat it as if the data starts just after
+		 * the header.
+		 */
+		cifs_dbg(FYI, "%s: data offset (%u) inside read response header\n",
+			 __func__, data_offset);
+		data_offset = server->total_read;
+	} else if (data_offset > MAX_CIFS_SMALL_BUFFER_SIZE) {
+		/* data_offset is beyond the end of smallbuf */
+		cifs_dbg(FYI, "%s: data offset (%u) beyond end of smallbuf\n",
+			 __func__, data_offset);
+		rdata->result = -EIO;
+		return cifs_readv_discard(server, mid);
+	}
+
+	cifs_dbg(FYI, "%s: total_read=%u data_offset=%u\n",
+		 __func__, server->total_read, data_offset);
+
+	len = data_offset - server->total_read;
+	if (len > 0) {
+		/* read any junk before data into the rest of smallbuf */
+		length = cifs_read_from_socket(server,
+					       buf + server->total_read, len);
+		if (length < 0)
+			return length;
+		server->total_read += length;
+	}
+
+	/* how much data is in the response? */
+#ifdef CONFIG_CIFS_SMB_DIRECT
+	use_rdma_mr = rdata->mr;
+#endif
+	data_len = server->ops->read_data_length(buf, use_rdma_mr);
+	if (!use_rdma_mr && (data_offset + data_len > buflen)) {
+		/* data_len is corrupt -- discard frame */
+		rdata->result = -EIO;
+		return cifs_readv_discard(server, mid);
+	}
+
+#ifdef CONFIG_CIFS_SMB_DIRECT
+	if (rdata->mr)
+		length = data_len; /* An RDMA read is already done. */
+	else
+#endif
+		length = cifs_read_iter_from_socket(server, &rdata->iter,
+						    data_len);
+	if (length > 0)
+		rdata->got_bytes += length;
+	server->total_read += length;
+
+	cifs_dbg(FYI, "total_read=%u buflen=%u remaining=%u\n",
+		 server->total_read, buflen, data_len);
+
+	/* discard anything left over */
+	if (server->total_read < buflen)
+		return cifs_readv_discard(server, mid);
+
+	dequeue_mid(mid, false);
+	mid->resp_buf = server->smallbuf;
+	server->smallbuf = NULL;
+	return length;
+}