transport.c

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/*
 *   fs/cifs/transport.c
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2008
 *   Author(s): Steve French ([email protected])
 *   Jeremy Allison ([email protected]) 2006.
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#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/highmem.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
#include <linux/mempool.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"

void
cifs_wake_up_task(struct mid_q_entry *mid)
{
    wake_up_process(mid->callback_data);
}

struct mid_q_entry *
AllocMidQEntry(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
{
    struct mid_q_entry *temp;

    if (server == NULL) {
        cERROR(1, "Null TCP session in AllocMidQEntry");
        return NULL;
    }

    temp = mempool_alloc(cifs_mid_poolp, GFP_NOFS);
    if (temp == NULL)
        return temp;
    else {
        memset(temp, 0, sizeof(struct mid_q_entry));
        temp->mid = smb_buffer->Mid;    /* always LE */
        temp->pid = current->pid;
        temp->command = cpu_to_le16(smb_buffer->Command);
        cFYI(1, "For smb_command %d", 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.
         */
        temp->callback = cifs_wake_up_task;
        temp->callback_data = current;
    }

    atomic_inc(&midCount);
    temp->mid_state = MID_REQUEST_ALLOCATED;
    return temp;
}

void
DeleteMidQEntry(struct mid_q_entry *midEntry)
{
#ifdef CONFIG_CIFS_STATS2
    __le16 command = midEntry->server->vals->lock_cmd;
    unsigned long now;
#endif
    midEntry->mid_state = MID_FREE;
    atomic_dec(&midCount);
    if (midEntry->large_buf)
        cifs_buf_release(midEntry->resp_buf);
    else
        cifs_small_buf_release(midEntry->resp_buf);
#ifdef CONFIG_CIFS_STATS2
    now = jiffies;
    /* commands taking longer than one second are indications that
       something is wrong, unless it is quite a slow link or server */
    if ((now - midEntry->when_alloc) > HZ) {
        if ((cifsFYI & CIFS_TIMER) && (midEntry->command != command)) {
            printk(KERN_DEBUG " CIFS slow rsp: cmd %d mid %llu",
                   midEntry->command, midEntry->mid);
            printk(" A: 0x%lx S: 0x%lx R: 0x%lx\n",
                   now - midEntry->when_alloc,
                   now - midEntry->when_sent,
                   now - midEntry->when_received);
        }
    }
#endif
    mempool_free(midEntry, cifs_mid_poolp);
}

void
cifs_delete_mid(struct mid_q_entry *mid)
{
    spin_lock(&GlobalMid_Lock);
    list_del(&mid->qhead);
    spin_unlock(&GlobalMid_Lock);

    DeleteMidQEntry(mid);
}

/*
 * smb_send_kvec - send an array of kvecs to the server
 * @server: Server to send the data to
 * @iov:    Pointer to array of kvecs
 * @n_vec:  length of kvec array
 * @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 kvec *iov, size_t n_vec,
        size_t *sent)
{
    int rc = 0;
    int i = 0;
    struct msghdr smb_msg;
    unsigned int remaining;
    size_t first_vec = 0;
    struct socket *ssocket = server->ssocket;

    *sent = 0;

    if (ssocket == NULL)
        return -ENOTSOCK; /* BB eventually add reconnect code here */

    smb_msg.msg_name = (struct sockaddr *) &server->dstaddr;
    smb_msg.msg_namelen = sizeof(struct sockaddr);
    smb_msg.msg_control = NULL;
    smb_msg.msg_controllen = 0;
    if (server->noblocksnd)
        smb_msg.msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
    else
        smb_msg.msg_flags = MSG_NOSIGNAL;

    remaining = 0;
    for (i = 0; i < n_vec; i++)
        remaining += iov[i].iov_len;

    i = 0;
    while (remaining) {
        /*
         * 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 = kernel_sendmsg(ssocket, &smb_msg, &iov[first_vec],
                    n_vec - first_vec, remaining);
        if (rc == -ENOSPC || rc == -EAGAIN) {
            /*
             * Catch if a low level driver returns -ENOSPC. This
             * WARN_ON will be removed by 3.10 if no one reports
             * seeing this.
             */
            WARN_ON_ONCE(rc == -ENOSPC);
            i++;
            if (i >= 14 || (!server->noblocksnd && (i > 2))) {
                cERROR(1, "sends on sock %p stuck for 15 "
                      "seconds", ssocket);
                rc = -EAGAIN;
                break;
            }
            msleep(1 << i);
            continue;
        }

        if (rc < 0)
            break;

        /* send was at least partially successful */
        *sent += rc;

        if (rc == remaining) {
            remaining = 0;
            break;
        }

        if (rc > remaining) {
            cERROR(1, "sent %d requested %d", rc, remaining);
            break;
        }

        if (rc == 0) {
            /* should never happen, letting socket clear before
               retrying is our only obvious option here */
            cERROR(1, "tcp sent no data");
            msleep(500);
            continue;
        }

        remaining -= rc;

        /* the line below resets i */
        for (i = first_vec; i < n_vec; i++) {
            if (iov[i].iov_len) {
                if (rc > iov[i].iov_len) {
                    rc -= iov[i].iov_len;
                    iov[i].iov_len = 0;
                } else {
                    iov[i].iov_base += rc;
                    iov[i].iov_len -= rc;
                    first_vec = i;
                    break;
                }
            }
        }

        i = 0; /* in case we get ENOSPC on the next send */
        rc = 0;
    }
    return rc;
}

void
cifs_rqst_page_to_kvec(struct smb_rqst *rqst, unsigned int idx,
            struct kvec *iov)
{
    /*
     * FIXME: We could avoid this kmap altogether if we used
     * kernel_sendpage instead of kernel_sendmsg. That will only
     * work if signing is disabled though as sendpage inlines the
     * page directly into the fraglist. If userspace modifies the
     * page after we calculate the signature, then the server will
     * reject it and may break the connection. kernel_sendmsg does
     * an extra copy of the data and avoids that issue.
     */
    iov->iov_base = kmap(rqst->rq_pages[idx]);

    /* if last page, don't send beyond this offset into page */
    if (idx == (rqst->rq_npages - 1))
        iov->iov_len = rqst->rq_tailsz;
    else
        iov->iov_len = rqst->rq_pagesz;
}

static int
smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst)
{
    int rc;
    struct kvec *iov = rqst->rq_iov;
    int n_vec = rqst->rq_nvec;
    unsigned int smb_buf_length = get_rfc1002_length(iov[0].iov_base);
    unsigned int i;
    size_t total_len = 0, sent;
    struct socket *ssocket = server->ssocket;
    int val = 1;

    cFYI(1, "Sending smb: smb_len=%u", smb_buf_length);
    dump_smb(iov[0].iov_base, iov[0].iov_len);

    /* cork the socket */
    kernel_setsockopt(ssocket, SOL_TCP, TCP_CORK,
                (char *)&val, sizeof(val));

    rc = smb_send_kvec(server, iov, n_vec, &sent);
    if (rc < 0)
        goto uncork;

    total_len += sent;

    /* now walk the page array and send each page in it */
    for (i = 0; i < rqst->rq_npages; i++) {
        struct kvec p_iov;

        cifs_rqst_page_to_kvec(rqst, i, &p_iov);
        rc = smb_send_kvec(server, &p_iov, 1, &sent);
        kunmap(rqst->rq_pages[i]);
        if (rc < 0)
            break;

        total_len += sent;
    }

uncork:
    /* uncork it */
    val = 0;
    kernel_setsockopt(ssocket, SOL_TCP, TCP_CORK,
                (char *)&val, sizeof(val));

    if ((total_len > 0) && (total_len != smb_buf_length + 4)) {
        cFYI(1, "partial send (wanted=%u sent=%zu): terminating "
            "session", smb_buf_length + 4, 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
         */
        server->tcpStatus = CifsNeedReconnect;
    }

    if (rc < 0 && rc != -EINTR)
        cERROR(1, "Error %d sending data on socket to server", rc);
    else
        rc = 0;

    return rc;
}

static int
smb_sendv(struct TCP_Server_Info *server, struct kvec *iov, int n_vec)
{
    struct smb_rqst rqst = { .rq_iov = iov,
                 .rq_nvec = n_vec };

    return smb_send_rqst(server, &rqst);
}

int
smb_send(struct TCP_Server_Info *server, struct smb_hdr *smb_buffer,
     unsigned int smb_buf_length)
{
    struct kvec iov;

    iov.iov_base = smb_buffer;
    iov.iov_len = smb_buf_length + 4;

    return smb_sendv(server, &iov, 1);
}

static int
wait_for_free_credits(struct TCP_Server_Info *server, const int timeout,
              int *credits)
{
    int rc;

    spin_lock(&server->req_lock);
    if (timeout == CIFS_ASYNC_OP) {
        /* oplock breaks must not be held up */
        server->in_flight++;
        *credits -= 1;
        spin_unlock(&server->req_lock);
        return 0;
    }

    while (1) {
        if (*credits <= 0) {
            spin_unlock(&server->req_lock);
            cifs_num_waiters_inc(server);
            rc = wait_event_killable(server->request_q,
                         has_credits(server, credits));
            cifs_num_waiters_dec(server);
            if (rc)
                return rc;
            spin_lock(&server->req_lock);
        } else {
            if (server->tcpStatus == CifsExiting) {
                spin_unlock(&server->req_lock);
                return -ENOENT;
            }

            /*
             * Can not count locking commands against total
             * as they are allowed to block on server.
             */

            /* update # of requests on the wire to server */
            if (timeout != CIFS_BLOCKING_OP) {
                *credits -= 1;
                server->in_flight++;
            }
            spin_unlock(&server->req_lock);
            break;
        }
    }
    return 0;
}

static int
wait_for_free_request(struct TCP_Server_Info *server, const int timeout,
              const int optype)
{
    return wait_for_free_credits(server, timeout,
                server->ops->get_credits_field(server, optype));
}

static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
            struct mid_q_entry **ppmidQ)
{
    if (ses->server->tcpStatus == CifsExiting) {
        return -ENOENT;
    }

    if (ses->server->tcpStatus == CifsNeedReconnect) {
        cFYI(1, "tcp session dead - return to caller to retry");
        return -EAGAIN;
    }

    if (ses->status != CifsGood) {
        /* check if SMB session is bad because we are setting it up */
        if ((in_buf->Command != SMB_COM_SESSION_SETUP_ANDX) &&
            (in_buf->Command != SMB_COM_NEGOTIATE))
            return -EAGAIN;
        /* else ok - we are setting up session */
    }
    *ppmidQ = AllocMidQEntry(in_buf, ses->server);
    if (*ppmidQ == NULL)
        return -ENOMEM;
    spin_lock(&GlobalMid_Lock);
    list_add_tail(&(*ppmidQ)->qhead, &ses->server->pending_mid_q);
    spin_unlock(&GlobalMid_Lock);
    return 0;
}

static int
wait_for_response(struct TCP_Server_Info *server, struct mid_q_entry *midQ)
{
    int error;

    error = wait_event_freezekillable(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;

    /* enable signing if server requires it */
    if (server->sec_mode & (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED))
        hdr->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;

    mid = AllocMidQEntry(hdr, server);
    if (mid == NULL)
        return ERR_PTR(-ENOMEM);

    rc = cifs_sign_rqst(rqst, server, &mid->sequence_number);
    if (rc) {
        DeleteMidQEntry(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,
        void *cbdata, const int flags)
{
    int rc, timeout, optype;
    struct mid_q_entry *mid;

    timeout = flags & CIFS_TIMEOUT_MASK;
    optype = flags & CIFS_OP_MASK;

    rc = wait_for_free_request(server, timeout, optype);
    if (rc)
        return rc;

    mutex_lock(&server->srv_mutex);
    mid = server->ops->setup_async_request(server, rqst);
    if (IS_ERR(mid)) {
        mutex_unlock(&server->srv_mutex);
        add_credits(server, 1, optype);
        wake_up(&server->request_q);
        return PTR_ERR(mid);
    }

    mid->receive = receive;
    mid->callback = callback;
    mid->callback_data = cbdata;
    mid->mid_state = MID_REQUEST_SUBMITTED;

    /* put it on the pending_mid_q */
    spin_lock(&GlobalMid_Lock);
    list_add_tail(&mid->qhead, &server->pending_mid_q);
    spin_unlock(&GlobalMid_Lock);


    cifs_in_send_inc(server);
    rc = smb_send_rqst(server, rqst);
    cifs_in_send_dec(server);
    cifs_save_when_sent(mid);
    mutex_unlock(&server->srv_mutex);

    if (rc == 0)
        return 0;

    cifs_delete_mid(mid);
    add_credits(server, 1, optype);
    wake_up(&server->request_q);
    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];
    int resp_buf_type;

    iov[0].iov_base = in_buf;
    iov[0].iov_len = get_rfc1002_length(in_buf) + 4;
    flags |= CIFS_NO_RESP;
    rc = SendReceive2(xid, ses, iov, 1, &resp_buf_type, flags);
    cFYI(DBG2, "SendRcvNoRsp flags %d rc %d", flags, rc);

    return rc;
}

static int
cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
{
    int rc = 0;

    cFYI(1, "%s: cmd=%d mid=%llu state=%d", __func__,
         le16_to_cpu(mid->command), mid->mid, mid->mid_state);

    spin_lock(&GlobalMid_Lock);
    switch (mid->mid_state) {
    case MID_RESPONSE_RECEIVED:
        spin_unlock(&GlobalMid_Lock);
        return rc;
    case MID_RETRY_NEEDED:
        rc = -EAGAIN;
        break;
    case MID_RESPONSE_MALFORMED:
        rc = -EIO;
        break;
    case MID_SHUTDOWN:
        rc = -EHOSTDOWN;
        break;
    default:
        list_del_init(&mid->qhead);
        cERROR(1, "%s: invalid mid state mid=%llu state=%d", __func__,
               mid->mid, mid->mid_state);
        rc = -EIO;
    }
    spin_unlock(&GlobalMid_Lock);

    DeleteMidQEntry(mid);
    return rc;
}

static inline int
send_cancel(struct TCP_Server_Info *server, void *buf, struct mid_q_entry *mid)
{
    return server->ops->send_cancel ?
                server->ops->send_cancel(server, buf, 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->sec_mode & (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) {
        struct kvec iov;
        int rc = 0;
        struct smb_rqst rqst = { .rq_iov = &iov,
                     .rq_nvec = 1 };

        iov.iov_base = mid->resp_buf;
        iov.iov_len = len;
        /* FIXME: add code to kill session */
        rc = cifs_verify_signature(&rqst, server,
                       mid->sequence_number + 1);
        if (rc)
            cERROR(1, "SMB signature verification returned error = "
                   "%d", rc);
    }

    /* BB special case reconnect tid and uid here? */
    return map_smb_to_linux_error(mid->resp_buf, log_error);
}

struct mid_q_entry *
cifs_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst)
{
    int rc;
    struct smb_hdr *hdr = (struct smb_hdr *)rqst->rq_iov[0].iov_base;
    struct mid_q_entry *mid;

    rc = allocate_mid(ses, hdr, &mid);
    if (rc)
        return ERR_PTR(rc);
    rc = cifs_sign_rqst(rqst, ses->server, &mid->sequence_number);
    if (rc) {
        cifs_delete_mid(mid);
        return ERR_PTR(rc);
    }
    return mid;
}

int
SendReceive2(const unsigned int xid, struct cifs_ses *ses,
         struct kvec *iov, int n_vec, int *resp_buf_type /* ret */,
         const int flags)
{
    int rc = 0;
    int timeout, optype;
    struct mid_q_entry *midQ;
    char *buf = iov[0].iov_base;
    unsigned int credits = 1;
    struct smb_rqst rqst = { .rq_iov = iov,
                 .rq_nvec = n_vec };

    timeout = flags & CIFS_TIMEOUT_MASK;
    optype = flags & CIFS_OP_MASK;

    *resp_buf_type = CIFS_NO_BUFFER;  /* no response buf yet */

    if ((ses == NULL) || (ses->server == NULL)) {
        cifs_small_buf_release(buf);
        cERROR(1, "Null session");
        return -EIO;
    }

    if (ses->server->tcpStatus == CifsExiting) {
        cifs_small_buf_release(buf);
        return -ENOENT;
    }

    /*
     * 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.
     */

    rc = wait_for_free_request(ses->server, timeout, optype);
    if (rc) {
        cifs_small_buf_release(buf);
        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.
     */

    mutex_lock(&ses->server->srv_mutex);

    midQ = ses->server->ops->setup_request(ses, &rqst);
    if (IS_ERR(midQ)) {
        mutex_unlock(&ses->server->srv_mutex);
        cifs_small_buf_release(buf);
        /* Update # of requests on wire to server */
        add_credits(ses->server, 1, optype);
        return PTR_ERR(midQ);
    }

    midQ->mid_state = MID_REQUEST_SUBMITTED;
    cifs_in_send_inc(ses->server);
    rc = smb_sendv(ses->server, iov, n_vec);
    cifs_in_send_dec(ses->server);
    cifs_save_when_sent(midQ);

    mutex_unlock(&ses->server->srv_mutex);

    if (rc < 0) {
        cifs_small_buf_release(buf);
        goto out;
    }

    if (timeout == CIFS_ASYNC_OP) {
        cifs_small_buf_release(buf);
        goto out;
    }

    rc = wait_for_response(ses->server, midQ);
    if (rc != 0) {
        send_cancel(ses->server, buf, midQ);
        spin_lock(&GlobalMid_Lock);
        if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
            midQ->callback = DeleteMidQEntry;
            spin_unlock(&GlobalMid_Lock);
            cifs_small_buf_release(buf);
            add_credits(ses->server, 1, optype);
            return rc;
        }
        spin_unlock(&GlobalMid_Lock);
    }

    cifs_small_buf_release(buf);

    rc = cifs_sync_mid_result(midQ, ses->server);
    if (rc != 0) {
        add_credits(ses->server, 1, optype);
        return rc;
    }

    if (!midQ->resp_buf || midQ->mid_state != MID_RESPONSE_RECEIVED) {
        rc = -EIO;
        cFYI(1, "Bad MID state?");
        goto out;
    }

    buf = (char *)midQ->resp_buf;
    iov[0].iov_base = buf;
    iov[0].iov_len = get_rfc1002_length(buf) + 4;
    if (midQ->large_buf)
        *resp_buf_type = CIFS_LARGE_BUFFER;
    else
        *resp_buf_type = CIFS_SMALL_BUFFER;

    credits = ses->server->ops->get_credits(midQ);

    rc = ses->server->ops->check_receive(midQ, ses->server,
                         flags & CIFS_LOG_ERROR);

    /* mark it so buf will not be freed by cifs_delete_mid */
    if ((flags & CIFS_NO_RESP) == 0)
        midQ->resp_buf = NULL;
out:
    cifs_delete_mid(midQ);
    add_credits(ses->server, credits, optype);

    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 timeout)
{
    int rc = 0;
    struct mid_q_entry *midQ;

    if (ses == NULL) {
        cERROR(1, "Null smb session");
        return -EIO;
    }
    if (ses->server == NULL) {
        cERROR(1, "Null tcp session");
        return -EIO;
    }

    if (ses->server->tcpStatus == CifsExiting)
        return -ENOENT;

    /* 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 (be32_to_cpu(in_buf->smb_buf_length) > CIFSMaxBufSize +
            MAX_CIFS_HDR_SIZE - 4) {
        cERROR(1, "Illegal length, greater than maximum frame, %d",
               be32_to_cpu(in_buf->smb_buf_length));
        return -EIO;
    }

    rc = wait_for_free_request(ses->server, timeout, 0);
    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 */

    mutex_lock(&ses->server->srv_mutex);

    rc = allocate_mid(ses, in_buf, &midQ);
    if (rc) {
        mutex_unlock(&ses->server->srv_mutex);
        /* Update # of requests on wire to server */
        add_credits(ses->server, 1, 0);
        return rc;
    }

    rc = cifs_sign_smb(in_buf, ses->server, &midQ->sequence_number);
    if (rc) {
        mutex_unlock(&ses->server->srv_mutex);
        goto out;
    }

    midQ->mid_state = MID_REQUEST_SUBMITTED;

    cifs_in_send_inc(ses->server);
    rc = smb_send(ses->server, in_buf, be32_to_cpu(in_buf->smb_buf_length));
    cifs_in_send_dec(ses->server);
    cifs_save_when_sent(midQ);
    mutex_unlock(&ses->server->srv_mutex);

    if (rc < 0)
        goto out;

    if (timeout == CIFS_ASYNC_OP)
        goto out;

    rc = wait_for_response(ses->server, midQ);
    if (rc != 0) {
        send_cancel(ses->server, in_buf, midQ);
        spin_lock(&GlobalMid_Lock);
        if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
            /* no longer considered to be "in-flight" */
            midQ->callback = DeleteMidQEntry;
            spin_unlock(&GlobalMid_Lock);
            add_credits(ses->server, 1, 0);
            return rc;
        }
        spin_unlock(&GlobalMid_Lock);
    }

    rc = cifs_sync_mid_result(midQ, ses->server);
    if (rc != 0) {
        add_credits(ses->server, 1, 0);
        return rc;
    }

    if (!midQ->resp_buf || !out_buf ||
        midQ->mid_state != MID_RESPONSE_RECEIVED) {
        rc = -EIO;
        cERROR(1, "Bad MID state?");
        goto out;
    }

    *pbytes_returned = get_rfc1002_length(midQ->resp_buf);
    memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
    rc = cifs_check_receive(midQ, ses->server, 0);
out:
    cifs_delete_mid(midQ);
    add_credits(ses->server, 1, 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;

    if (tcon == NULL || tcon->ses == NULL) {
        cERROR(1, "Null smb session");
        return -EIO;
    }
    ses = tcon->ses;

    if (ses->server == NULL) {
        cERROR(1, "Null tcp session");
        return -EIO;
    }

    if (ses->server->tcpStatus == CifsExiting)
        return -ENOENT;

    /* 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 (be32_to_cpu(in_buf->smb_buf_length) > CIFSMaxBufSize +
            MAX_CIFS_HDR_SIZE - 4) {
        cERROR(1, "Illegal length, greater than maximum frame, %d",
               be32_to_cpu(in_buf->smb_buf_length));
        return -EIO;
    }

    rc = wait_for_free_request(ses->server, CIFS_BLOCKING_OP, 0);
    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 */

    mutex_lock(&ses->server->srv_mutex);

    rc = allocate_mid(ses, in_buf, &midQ);
    if (rc) {
        mutex_unlock(&ses->server->srv_mutex);
        return rc;
    }

    rc = cifs_sign_smb(in_buf, ses->server, &midQ->sequence_number);
    if (rc) {
        cifs_delete_mid(midQ);
        mutex_unlock(&ses->server->srv_mutex);
        return rc;
    }

    midQ->mid_state = MID_REQUEST_SUBMITTED;
    cifs_in_send_inc(ses->server);
    rc = smb_send(ses->server, in_buf, be32_to_cpu(in_buf->smb_buf_length));
    cifs_in_send_dec(ses->server);
    cifs_save_when_sent(midQ);
    mutex_unlock(&ses->server->srv_mutex);

    if (rc < 0) {
        cifs_delete_mid(midQ);
        return rc;
    }

    /* Wait for a reply - allow signals to interrupt. */
    rc = wait_event_interruptible(ses->server->response_q,
        (!(midQ->mid_state == MID_REQUEST_SUBMITTED)) ||
        ((ses->server->tcpStatus != CifsGood) &&
         (ses->server->tcpStatus != CifsNew)));

    /* Were we interrupted by a signal ? */
    if ((rc == -ERESTARTSYS) &&
        (midQ->mid_state == MID_REQUEST_SUBMITTED) &&
        ((ses->server->tcpStatus == CifsGood) ||
         (ses->server->tcpStatus == CifsNew))) {

        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(ses->server, in_buf, midQ);
            if (rc) {
                cifs_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) {
                cifs_delete_mid(midQ);
                return rc;
            }
        }

        rc = wait_for_response(ses->server, midQ);
        if (rc) {
            send_cancel(ses->server, in_buf, midQ);
            spin_lock(&GlobalMid_Lock);
            if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
                /* no longer considered to be "in-flight" */
                midQ->callback = DeleteMidQEntry;
                spin_unlock(&GlobalMid_Lock);
                return rc;
            }
            spin_unlock(&GlobalMid_Lock);
        }

        /* We got the response - restart system call. */
        rstart = 1;
    }

    rc = cifs_sync_mid_result(midQ, ses->server);
    if (rc != 0)
        return rc;

    /* rcvd frame is ok */
    if (out_buf == NULL || midQ->mid_state != MID_RESPONSE_RECEIVED) {
        rc = -EIO;
        cERROR(1, "Bad MID state?");
        goto out;
    }

    *pbytes_returned = get_rfc1002_length(midQ->resp_buf);
    memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
    rc = cifs_check_receive(midQ, ses->server, 0);
out:
    cifs_delete_mid(midQ);
    if (rstart && rc == -EACCES)
        return -ERESTARTSYS;
    return rc;
}