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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // 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 <asm/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)
 {
     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);
     /*  do_gettimeofday(&temp->when_sent);*/ /* 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;
 }
 
 static 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 &&
         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 release_mid(struct mid_q_entry *mid)
 {
     struct TCP_Server_Info *server = mid->server;
 
     spin_lock(&server->mid_lock);
     kref_put(&mid->refcount, __release_mid);
     spin_unlock(&server->mid_lock);
 }
 
 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;
 
     /*
      * Add in the page array if there is one. The caller needs to make
      * sure rq_offset and rq_tailsz are set correctly. If a buffer of
      * multiple pages ends at page boundary, rq_tailsz needs to be set to
      * PAGE_SIZE.
      */
     if (rqst->rq_npages) {
         if (rqst->rq_npages == 1)
             buflen += rqst->rq_tailsz;
         else {
             /*
              * If there is more than one page, calculate the
              * buffer length based on rq_offset and rq_tailsz
              */
             buflen += rqst->rq_pagesz * (rqst->rq_npages - 1) -
                     rqst->rq_offset;
             buflen += rqst->rq_tailsz;
         }
     }
 
     return buflen;
 }
 
 static int
 __smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
         struct smb_rqst *rqst)
 {
     int rc = 0;
     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;
 
     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;
     }
 
     if (ssocket == NULL)
         return -EAGAIN;
 
     if (fatal_signal_pending(current)) {
         cifs_dbg(FYI, "signal pending before send request\n");
         return -ERESTARTSYS;
     }
 
     /* 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, WRITE, &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, WRITE, iov, n_vec, size);
 
         rc = smb_send_kvec(server, &smb_msg, &sent);
         if (rc < 0)
             goto unmask;
 
         total_len += sent;
 
         /* now walk the page array and send each page in it */
         for (i = 0; i < rqst[j].rq_npages; i++) {
             struct bio_vec bvec;
 
             bvec.bv_page = rqst[j].rq_pages[i];
             rqst_page_get_length(&rqst[j], i, &bvec.bv_len,
                          &bvec.bv_offset);
 
             iov_iter_bvec(&smb_msg.msg_iter, WRITE,
                       &bvec, 1, bvec.bv_len);
             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;
 
     return rc;
 }
 
 static int
 smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
           struct smb_rqst *rqst, int flags)
 {
     struct kvec iov;
     struct smb2_transform_hdr *tr_hdr;
     struct smb_rqst cur_rqst[MAX_COMPOUND];
     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;
     }
 
     tr_hdr = kzalloc(sizeof(*tr_hdr), GFP_NOFS);
     if (!tr_hdr)
         return -ENOMEM;
 
     memset(&cur_rqst[0], 0, sizeof(cur_rqst));
     memset(&iov, 0, sizeof(iov));
 
     iov.iov_base = tr_hdr;
     iov.iov_len = sizeof(*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(tr_hdr);
     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) {
         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 {
             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);
 
             /*
              * 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.
              */
             spin_lock(&server->req_lock);
             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_freezekillable_unsafe(server->response_q,
                     midQ->mid_state != MID_REQUEST_SUBMITTED);
     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);
     cifs_in_send_inc(server);
     rc = smb_send_rqst(server, 1, rqst, flags);
     cifs_in_send_dec(server);
 
     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_RECEIVED:
         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);
 }
 
 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;
 
     if (!ses)
         return NULL;
 
     /* round robin */
     index = (uint)atomic_inc_return(&ses->chan_seq);
 
     spin_lock(&ses->chan_lock);
     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;
     }
     cifs_in_send_inc(server);
     rc = smb_send_rqst(server, num_rqst, rqst, flags);
     cifs_in_send_dec(server);
 
     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]->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_RECEIVED) {
             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;
 
     cifs_in_send_inc(server);
     rc = smb_send(server, in_buf, len);
     cifs_in_send_dec(server);
     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) {
             /* 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_RECEIVED) {
         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;
     cifs_in_send_inc(server);
     rc = smb_send(server, in_buf, len);
     cifs_in_send_dec(server);
     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)) ||
         ((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) &&
         ((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) {
                 /* 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_RECEIVED) {
         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;
     int remaining = rfclen + HEADER_PREAMBLE_SIZE(server) -
         server->total_read;
 
     while (remaining > 0) {
         int 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);
     }
 
     length = rdata->read_into_pages(server, rdata, data_len);
     if (length < 0)
         return 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;
 }

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