[deliverable/linux.git] / net / 9p / trans_fd.c

/*
 * linux/fs/9p/trans_fd.c
 *
 * Fd transport layer.  Includes deprecated socket layer.
 *
 *  Copyright (C) 2006 by Russ Cox <rsc@swtch.com>
 *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
 *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
 *  Copyright (C) 1997-2002 by Ron Minnich <rminnich@sarnoff.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */

#include <linux/in.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/ipv6.h>
#include <linux/kthread.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/un.h>
#include <linux/uaccess.h>
#include <linux/inet.h>
#include <linux/idr.h>
#include <linux/file.h>
#include <linux/parser.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>

#define P9_PORT 564
#define MAX_SOCK_BUF (64*1024)
#define ERREQFLUSH      1
#define MAXPOLLWADDR    2

/**
 * struct p9_fd_opts - per-transport options
 * @rfd: file descriptor for reading (trans=fd)
 * @wfd: file descriptor for writing (trans=fd)
 * @port: port to connect to (trans=tcp)
 *
 */

struct p9_fd_opts {
        int rfd;
        int wfd;
        u16 port;
};

/**
 * struct p9_trans_fd - transport state
 * @rd: reference to file to read from
 * @wr: reference of file to write to
 * @conn: connection state reference
 *
 */

struct p9_trans_fd {
        struct file *rd;
        struct file *wr;
        struct p9_conn *conn;
};

/*
  * Option Parsing (code inspired by NFS code)
  *  - a little lazy - parse all fd-transport options
  */

enum {
        /* Options that take integer arguments */
        Opt_port, Opt_rfdno, Opt_wfdno, Opt_err,
};

static const match_table_t tokens = {
        {Opt_port, "port=%u"},
        {Opt_rfdno, "rfdno=%u"},
        {Opt_wfdno, "wfdno=%u"},
        {Opt_err, NULL},
};

enum {
        Rworksched = 1,         /* read work scheduled or running */
        Rpending = 2,           /* can read */
        Wworksched = 4,         /* write work scheduled or running */
        Wpending = 8,           /* can write */
};

enum {
        None,
        Flushing,
        Flushed,
};

struct p9_req;
typedef void (*p9_conn_req_callback)(struct p9_req *req, void *a);

/**
 * struct p9_req - fd mux encoding of an rpc transaction
 * @lock: protects req_list
 * @tag: numeric tag for rpc transaction
 * @tcall: request &p9_fcall structure
 * @rcall: response &p9_fcall structure
 * @err: error state
 * @cb: callback for when response is received
 * @cba: argument to pass to callback
 * @flush: flag to indicate RPC has been flushed
 * @req_list: list link for higher level objects to chain requests
 * @m: connection this request was issued on
 * @wqueue: wait queue that client is blocked on for this rpc
 *
 */

struct p9_req {
        spinlock_t lock;
        int tag;
        struct p9_fcall *tcall;
        struct p9_fcall *rcall;
        int err;
        p9_conn_req_callback cb;
        void *cba;
        int flush;
        struct list_head req_list;
        struct p9_conn *m;
        wait_queue_head_t wqueue;
};

struct p9_poll_wait {
        struct p9_conn *conn;
        wait_queue_t wait;
        wait_queue_head_t *wait_addr;
};

/**
 * struct p9_conn - fd mux connection state information
 * @lock: protects mux_list (?)
 * @mux_list: list link for mux to manage multiple connections (?)
 * @client: reference to client instance for this connection
 * @tagpool: id accounting for transactions
 * @err: error state
 * @req_list: accounting for requests which have been sent
 * @unsent_req_list: accounting for requests that haven't been sent
 * @rcall: current response &p9_fcall structure
 * @rpos: read position in current frame
 * @rbuf: current read buffer
 * @wpos: write position for current frame
 * @wsize: amount of data to write for current frame
 * @wbuf: current write buffer
 * @poll_wait: array of wait_q's for various worker threads
 * @poll_waddr: ????
 * @pt: poll state
 * @rq: current read work
 * @wq: current write work
 * @wsched: ????
 *
 */

struct p9_conn {
        spinlock_t lock; /* protect lock structure */
        struct list_head mux_list;
        struct p9_client *client;
        struct p9_idpool *tagpool;
        int err;
        struct list_head req_list;
        struct list_head unsent_req_list;
        struct p9_fcall *rcall;
        int rpos;
        char *rbuf;
        int wpos;
        int wsize;
        char *wbuf;
        struct list_head poll_pending_link;
        struct p9_poll_wait poll_wait[MAXPOLLWADDR];
        poll_table pt;
        struct work_struct rq;
        struct work_struct wq;
        unsigned long wsched;
};

static DEFINE_SPINLOCK(p9_poll_lock);
static LIST_HEAD(p9_poll_pending_list);
static struct workqueue_struct *p9_mux_wq;
static struct task_struct *p9_poll_task;

static u16 p9_mux_get_tag(struct p9_conn *m)
{
        int tag;

        tag = p9_idpool_get(m->tagpool);
        if (tag < 0)
                return P9_NOTAG;
        else
                return (u16) tag;
}

static void p9_mux_put_tag(struct p9_conn *m, u16 tag)
{
        if (tag != P9_NOTAG && p9_idpool_check(tag, m->tagpool))
                p9_idpool_put(tag, m->tagpool);
}

static void p9_mux_poll_stop(struct p9_conn *m)
{
        unsigned long flags;
        int i;

        for (i = 0; i < ARRAY_SIZE(m->poll_wait); i++) {
                struct p9_poll_wait *pwait = &m->poll_wait[i];

                if (pwait->wait_addr) {
                        remove_wait_queue(pwait->wait_addr, &pwait->wait);
                        pwait->wait_addr = NULL;
                }
        }

        spin_lock_irqsave(&p9_poll_lock, flags);
        list_del_init(&m->poll_pending_link);
        spin_unlock_irqrestore(&p9_poll_lock, flags);
}

/**
 * p9_conn_cancel - cancel all pending requests with error
 * @m: mux data
 * @err: error code
 *
 */

void p9_conn_cancel(struct p9_conn *m, int err)
{
        struct p9_req *req, *rtmp;
        LIST_HEAD(cancel_list);

        P9_DPRINTK(P9_DEBUG_ERROR, "mux %p err %d\n", m, err);
        m->err = err;
        spin_lock(&m->lock);
        list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
                list_move(&req->req_list, &cancel_list);
        }
        list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
                list_move(&req->req_list, &cancel_list);
        }
        spin_unlock(&m->lock);

        list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
                list_del(&req->req_list);
                if (!req->err)
                        req->err = err;

                if (req->cb)
                        (*req->cb) (req, req->cba);
                else
                        kfree(req->rcall);
        }
}

static void process_request(struct p9_conn *m, struct p9_req *req)
{
        int ecode;
        struct p9_str *ename;

        if (!req->err && req->rcall->id == P9_RERROR) {
                ecode = req->rcall->params.rerror.errno;
                ename = &req->rcall->params.rerror.error;

                P9_DPRINTK(P9_DEBUG_MUX, "Rerror %.*s\n", ename->len,
                                                                ename->str);

                if (m->client->dotu)
                        req->err = -ecode;

                if (!req->err) {
                        req->err = p9_errstr2errno(ename->str, ename->len);

                        /* string match failed */
                        if (!req->err) {
                                PRINT_FCALL_ERROR("unknown error", req->rcall);
                                req->err = -ESERVERFAULT;
                        }
                }
        } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
                P9_DPRINTK(P9_DEBUG_ERROR,
                                "fcall mismatch: expected %d, got %d\n",
                                req->tcall->id + 1, req->rcall->id);
                if (!req->err)
                        req->err = -EIO;
        }
}

static unsigned int
p9_fd_poll(struct p9_client *client, struct poll_table_struct *pt)
{
        int ret, n;
        struct p9_trans_fd *ts = NULL;

        if (client && client->status == Connected)
                ts = client->trans;

        if (!ts)
                return -EREMOTEIO;

        if (!ts->rd->f_op || !ts->rd->f_op->poll)
                return -EIO;

        if (!ts->wr->f_op || !ts->wr->f_op->poll)
                return -EIO;

        ret = ts->rd->f_op->poll(ts->rd, pt);
        if (ret < 0)
                return ret;

        if (ts->rd != ts->wr) {
                n = ts->wr->f_op->poll(ts->wr, pt);
                if (n < 0)
                        return n;
                ret = (ret & ~POLLOUT) | (n & ~POLLIN);
        }

        return ret;
}

/**
 * p9_fd_read- read from a fd
 * @client: client instance
 * @v: buffer to receive data into
 * @len: size of receive buffer
 *
 */

static int p9_fd_read(struct p9_client *client, void *v, int len)
{
        int ret;
        struct p9_trans_fd *ts = NULL;

        if (client && client->status != Disconnected)
                ts = client->trans;

        if (!ts)
                return -EREMOTEIO;

        if (!(ts->rd->f_flags & O_NONBLOCK))
                P9_DPRINTK(P9_DEBUG_ERROR, "blocking read ...\n");

        ret = kernel_read(ts->rd, ts->rd->f_pos, v, len);
        if (ret <= 0 && ret != -ERESTARTSYS && ret != -EAGAIN)
                client->status = Disconnected;
        return ret;
}

/**
 * p9_read_work - called when there is some data to be read from a transport
 * @work: container of work to be done
 *
 */

static void p9_read_work(struct work_struct *work)
{
        int n, err;
        struct p9_conn *m;
        struct p9_req *req, *rptr, *rreq;
        struct p9_fcall *rcall;
        char *rbuf;

        m = container_of(work, struct p9_conn, rq);

        if (m->err < 0)
                return;

        rcall = NULL;
        P9_DPRINTK(P9_DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);

        if (!m->rcall) {
                m->rcall =
                    kmalloc(sizeof(struct p9_fcall) + m->client->msize,
                                                                GFP_KERNEL);
                if (!m->rcall) {
                        err = -ENOMEM;
                        goto error;
                }

                m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
                m->rpos = 0;
        }

        clear_bit(Rpending, &m->wsched);
        err = p9_fd_read(m->client, m->rbuf + m->rpos,
                                                m->client->msize - m->rpos);
        P9_DPRINTK(P9_DEBUG_MUX, "mux %p got %d bytes\n", m, err);
        if (err == -EAGAIN) {
                clear_bit(Rworksched, &m->wsched);
                return;
        }

        if (err <= 0)
                goto error;

        m->rpos += err;
        while (m->rpos > 4) {
                n = le32_to_cpu(*(__le32 *) m->rbuf);
                if (n >= m->client->msize) {
                        P9_DPRINTK(P9_DEBUG_ERROR,
                                "requested packet size too big: %d\n", n);
                        err = -EIO;
                        goto error;
                }

                if (m->rpos < n)
                        break;

                err =
                    p9_deserialize_fcall(m->rbuf, n, m->rcall, m->client->dotu);
                if (err < 0)
                        goto error;

#ifdef CONFIG_NET_9P_DEBUG
                if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
                        char buf[150];

                        p9_printfcall(buf, sizeof(buf), m->rcall,
                                m->client->dotu);
                        printk(KERN_NOTICE ">>> %p %s\n", m, buf);
                }
#endif

                rcall = m->rcall;
                rbuf = m->rbuf;
                if (m->rpos > n) {
                        m->rcall = kmalloc(sizeof(struct p9_fcall) +
                                                m->client->msize, GFP_KERNEL);
                        if (!m->rcall) {
                                err = -ENOMEM;
                                goto error;
                        }

                        m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
                        memmove(m->rbuf, rbuf + n, m->rpos - n);
                        m->rpos -= n;
                } else {
                        m->rcall = NULL;
                        m->rbuf = NULL;
                        m->rpos = 0;
                }

                P9_DPRINTK(P9_DEBUG_MUX, "mux %p fcall id %d tag %d\n", m,
                                                        rcall->id, rcall->tag);

                req = NULL;
                spin_lock(&m->lock);
                list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
                        if (rreq->tag == rcall->tag) {
                                req = rreq;
                                if (req->flush != Flushing)
                                        list_del(&req->req_list);
                                break;
                        }
                }
                spin_unlock(&m->lock);

                if (req) {
                        req->rcall = rcall;
                        process_request(m, req);

                        if (req->flush != Flushing) {
                                if (req->cb)
                                        (*req->cb) (req, req->cba);
                                else
                                        kfree(req->rcall);
                        }
                } else {
                        if (err >= 0 && rcall->id != P9_RFLUSH)
                                P9_DPRINTK(P9_DEBUG_ERROR,
                                  "unexpected response mux %p id %d tag %d\n",
                                  m, rcall->id, rcall->tag);
                        kfree(rcall);
                }
        }

        if (!list_empty(&m->req_list)) {
                if (test_and_clear_bit(Rpending, &m->wsched))
                        n = POLLIN;
                else
                        n = p9_fd_poll(m->client, NULL);

                if (n & POLLIN) {
                        P9_DPRINTK(P9_DEBUG_MUX, "schedule read work %p\n", m);
                        queue_work(p9_mux_wq, &m->rq);
                } else
                        clear_bit(Rworksched, &m->wsched);
        } else
                clear_bit(Rworksched, &m->wsched);

        return;

error:
        p9_conn_cancel(m, err);
        clear_bit(Rworksched, &m->wsched);
}

/**
 * p9_fd_write - write to a socket
 * @client: client instance
 * @v: buffer to send data from
 * @len: size of send buffer
 *
 */

static int p9_fd_write(struct p9_client *client, void *v, int len)
{
        int ret;
        mm_segment_t oldfs;
        struct p9_trans_fd *ts = NULL;

        if (client && client->status != Disconnected)
                ts = client->trans;

        if (!ts)
                return -EREMOTEIO;

        if (!(ts->wr->f_flags & O_NONBLOCK))
                P9_DPRINTK(P9_DEBUG_ERROR, "blocking write ...\n");

        oldfs = get_fs();
        set_fs(get_ds());
        /* The cast to a user pointer is valid due to the set_fs() */
        ret = vfs_write(ts->wr, (void __user *)v, len, &ts->wr->f_pos);
        set_fs(oldfs);

        if (ret <= 0 && ret != -ERESTARTSYS && ret != -EAGAIN)
                client->status = Disconnected;
        return ret;
}

/**
 * p9_write_work - called when a transport can send some data
 * @work: container for work to be done
 *
 */

static void p9_write_work(struct work_struct *work)
{
        int n, err;
        struct p9_conn *m;
        struct p9_req *req;

        m = container_of(work, struct p9_conn, wq);

        if (m->err < 0) {
                clear_bit(Wworksched, &m->wsched);
                return;
        }

        if (!m->wsize) {
                if (list_empty(&m->unsent_req_list)) {
                        clear_bit(Wworksched, &m->wsched);
                        return;
                }

                spin_lock(&m->lock);
again:
                req = list_entry(m->unsent_req_list.next, struct p9_req,
                               req_list);
                list_move_tail(&req->req_list, &m->req_list);
                if (req->err == ERREQFLUSH)
                        goto again;

                m->wbuf = req->tcall->sdata;
                m->wsize = req->tcall->size;
                m->wpos = 0;
                spin_unlock(&m->lock);
        }

        P9_DPRINTK(P9_DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos,
                                                                m->wsize);
        clear_bit(Wpending, &m->wsched);
        err = p9_fd_write(m->client, m->wbuf + m->wpos, m->wsize - m->wpos);
        P9_DPRINTK(P9_DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
        if (err == -EAGAIN) {
                clear_bit(Wworksched, &m->wsched);
                return;
        }

        if (err < 0)
                goto error;
        else if (err == 0) {
                err = -EREMOTEIO;
                goto error;
        }

        m->wpos += err;
        if (m->wpos == m->wsize)
                m->wpos = m->wsize = 0;

        if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
                if (test_and_clear_bit(Wpending, &m->wsched))
                        n = POLLOUT;
                else
                        n = p9_fd_poll(m->client, NULL);

                if (n & POLLOUT) {
                        P9_DPRINTK(P9_DEBUG_MUX, "schedule write work %p\n", m);
                        queue_work(p9_mux_wq, &m->wq);
                } else
                        clear_bit(Wworksched, &m->wsched);
        } else
                clear_bit(Wworksched, &m->wsched);

        return;

error:
        p9_conn_cancel(m, err);
        clear_bit(Wworksched, &m->wsched);
}

static int p9_pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
{
        struct p9_poll_wait *pwait =
                container_of(wait, struct p9_poll_wait, wait);
        struct p9_conn *m = pwait->conn;
        unsigned long flags;
        DECLARE_WAITQUEUE(dummy_wait, p9_poll_task);

        spin_lock_irqsave(&p9_poll_lock, flags);
        if (list_empty(&m->poll_pending_link))
                list_add_tail(&m->poll_pending_link, &p9_poll_pending_list);
        spin_unlock_irqrestore(&p9_poll_lock, flags);

        /* perform the default wake up operation */
        return default_wake_function(&dummy_wait, mode, sync, key);
}

/**
 * p9_pollwait - add poll task to the wait queue
 * @filp: file pointer being polled
 * @wait_address: wait_q to block on
 * @p: poll state
 *
 * called by files poll operation to add v9fs-poll task to files wait queue
 */

static void
p9_pollwait(struct file *filp, wait_queue_head_t *wait_address, poll_table *p)
{
        struct p9_conn *m = container_of(p, struct p9_conn, pt);
        struct p9_poll_wait *pwait = NULL;
        int i;

        for (i = 0; i < ARRAY_SIZE(m->poll_wait); i++) {
                if (m->poll_wait[i].wait_addr == NULL) {
                        pwait = &m->poll_wait[i];
                        break;
                }
        }

        if (!pwait) {
                P9_DPRINTK(P9_DEBUG_ERROR, "not enough wait_address slots\n");
                return;
        }

        if (!wait_address) {
                P9_DPRINTK(P9_DEBUG_ERROR, "no wait_address\n");
                pwait->wait_addr = ERR_PTR(-EIO);
                return;
        }

        pwait->conn = m;
        pwait->wait_addr = wait_address;
        init_waitqueue_func_entry(&pwait->wait, p9_pollwake);
        add_wait_queue(wait_address, &pwait->wait);
}

/**
 * p9_conn_create - allocate and initialize the per-session mux data
 * @client: client instance
 *
 * Note: Creates the polling task if this is the first session.
 */

static struct p9_conn *p9_conn_create(struct p9_client *client)
{
        int i, n;
        struct p9_conn *m;

        P9_DPRINTK(P9_DEBUG_MUX, "client %p msize %d\n", client, client->msize);
        m = kzalloc(sizeof(struct p9_conn), GFP_KERNEL);
        if (!m)
                return ERR_PTR(-ENOMEM);

        spin_lock_init(&m->lock);
        INIT_LIST_HEAD(&m->mux_list);
        m->client = client;
        m->tagpool = p9_idpool_create();
        if (IS_ERR(m->tagpool)) {
                kfree(m);
                return ERR_PTR(-ENOMEM);
        }

        INIT_LIST_HEAD(&m->req_list);
        INIT_LIST_HEAD(&m->unsent_req_list);
        INIT_WORK(&m->rq, p9_read_work);
        INIT_WORK(&m->wq, p9_write_work);
        INIT_LIST_HEAD(&m->poll_pending_link);
        init_poll_funcptr(&m->pt, p9_pollwait);

        n = p9_fd_poll(client, &m->pt);
        if (n & POLLIN) {
                P9_DPRINTK(P9_DEBUG_MUX, "mux %p can read\n", m);
                set_bit(Rpending, &m->wsched);
        }

        if (n & POLLOUT) {
                P9_DPRINTK(P9_DEBUG_MUX, "mux %p can write\n", m);
                set_bit(Wpending, &m->wsched);
        }

        for (i = 0; i < ARRAY_SIZE(m->poll_wait); i++) {
                if (IS_ERR(m->poll_wait[i].wait_addr)) {
                        p9_mux_poll_stop(m);
                        kfree(m);
                        /* return the error code */
                        return (void *)m->poll_wait[i].wait_addr;
                }
        }

        return m;
}

/**
 * p9_poll_mux - polls a mux and schedules read or write works if necessary
 * @m: connection to poll
 *
 */

static void p9_poll_mux(struct p9_conn *m)
{
        int n;

        if (m->err < 0)
                return;

        n = p9_fd_poll(m->client, NULL);
        if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
                P9_DPRINTK(P9_DEBUG_MUX, "error mux %p err %d\n", m, n);
                if (n >= 0)
                        n = -ECONNRESET;
                p9_conn_cancel(m, n);
        }

        if (n & POLLIN) {
                set_bit(Rpending, &m->wsched);
                P9_DPRINTK(P9_DEBUG_MUX, "mux %p can read\n", m);
                if (!test_and_set_bit(Rworksched, &m->wsched)) {
                        P9_DPRINTK(P9_DEBUG_MUX, "schedule read work %p\n", m);
                        queue_work(p9_mux_wq, &m->rq);
                }
        }

        if (n & POLLOUT) {
                set_bit(Wpending, &m->wsched);
                P9_DPRINTK(P9_DEBUG_MUX, "mux %p can write\n", m);
                if ((m->wsize || !list_empty(&m->unsent_req_list))
                    && !test_and_set_bit(Wworksched, &m->wsched)) {
                        P9_DPRINTK(P9_DEBUG_MUX, "schedule write work %p\n", m);
                        queue_work(p9_mux_wq, &m->wq);
                }
        }
}

/**
 * p9_send_request - send 9P request
 * The function can sleep until the request is scheduled for sending.
 * The function can be interrupted. Return from the function is not
 * a guarantee that the request is sent successfully. Can return errors
 * that can be retrieved by PTR_ERR macros.
 *
 * @m: mux data
 * @tc: request to be sent
 * @cb: callback function to call when response is received
 * @cba: parameter to pass to the callback function
 *
 */

static struct p9_req *p9_send_request(struct p9_conn *m,
                                          struct p9_fcall *tc,
                                          p9_conn_req_callback cb, void *cba)
{
        int n;
        struct p9_req *req;

        P9_DPRINTK(P9_DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
                tc, tc->id);
        if (m->err < 0)
                return ERR_PTR(m->err);

        req = kmalloc(sizeof(struct p9_req), GFP_KERNEL);
        if (!req)
                return ERR_PTR(-ENOMEM);

        if (tc->id == P9_TVERSION)
                n = P9_NOTAG;
        else
                n = p9_mux_get_tag(m);

        if (n < 0) {
                kfree(req);
                return ERR_PTR(-ENOMEM);
        }

        p9_set_tag(tc, n);

#ifdef CONFIG_NET_9P_DEBUG
        if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
                char buf[150];

                p9_printfcall(buf, sizeof(buf), tc, m->client->dotu);
                printk(KERN_NOTICE "<<< %p %s\n", m, buf);
        }
#endif

        spin_lock_init(&req->lock);
        req->m = m;
        init_waitqueue_head(&req->wqueue);
        req->tag = n;
        req->tcall = tc;
        req->rcall = NULL;
        req->err = 0;
        req->cb = cb;
        req->cba = cba;
        req->flush = None;

        spin_lock(&m->lock);
        list_add_tail(&req->req_list, &m->unsent_req_list);
        spin_unlock(&m->lock);

        if (test_and_clear_bit(Wpending, &m->wsched))
                n = POLLOUT;
        else
                n = p9_fd_poll(m->client, NULL);

        if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
                queue_work(p9_mux_wq, &m->wq);

        return req;
}

static void p9_mux_free_request(struct p9_conn *m, struct p9_req *req)
{
        p9_mux_put_tag(m, req->tag);
        kfree(req);
}

static void p9_mux_flush_cb(struct p9_req *freq, void *a)
{
        int tag;
        struct p9_conn *m;
        struct p9_req *req, *rreq, *rptr;

        m = a;
        P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
                freq->tcall, freq->rcall, freq->err,
                freq->tcall->params.tflush.oldtag);

        spin_lock(&m->lock);
        tag = freq->tcall->params.tflush.oldtag;
        req = NULL;
        list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
                if (rreq->tag == tag) {
                        req = rreq;
                        list_del(&req->req_list);
                        break;
                }
        }
        spin_unlock(&m->lock);

        if (req) {
                spin_lock(&req->lock);
                req->flush = Flushed;
                spin_unlock(&req->lock);

                if (req->cb)
                        (*req->cb) (req, req->cba);
                else
                        kfree(req->rcall);
        }

        kfree(freq->tcall);
        kfree(freq->rcall);
        p9_mux_free_request(m, freq);
}

static int
p9_mux_flush_request(struct p9_conn *m, struct p9_req *req)
{
        struct p9_fcall *fc;
        struct p9_req *rreq, *rptr;

        P9_DPRINTK(P9_DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);

        /* if a response was received for a request, do nothing */
        spin_lock(&req->lock);
        if (req->rcall || req->err) {
                spin_unlock(&req->lock);
                P9_DPRINTK(P9_DEBUG_MUX,
                        "mux %p req %p response already received\n", m, req);
                return 0;
        }

        req->flush = Flushing;
        spin_unlock(&req->lock);

        spin_lock(&m->lock);
        /* if the request is not sent yet, just remove it from the list */
        list_for_each_entry_safe(rreq, rptr, &m->unsent_req_list, req_list) {
                if (rreq->tag == req->tag) {
                        P9_DPRINTK(P9_DEBUG_MUX,
                           "mux %p req %p request is not sent yet\n", m, req);
                        list_del(&rreq->req_list);
                        req->flush = Flushed;
                        spin_unlock(&m->lock);
                        if (req->cb)
                                (*req->cb) (req, req->cba);
                        return 0;
                }
        }
        spin_unlock(&m->lock);

        clear_thread_flag(TIF_SIGPENDING);
        fc = p9_create_tflush(req->tag);
        p9_send_request(m, fc, p9_mux_flush_cb, m);
        return 1;
}

static void p9_conn_rpc_cb(struct p9_req *req, void *a)
{
        P9_DPRINTK(P9_DEBUG_MUX, "req %p arg %p\n", req, a);

        if (req->flush != None && !req->err)
                req->err = -ERESTARTSYS;

        wake_up(&req->wqueue);
}

/**
 * p9_fd_rpc- sends 9P request and waits until a response is available.
 *      The function can be interrupted.
 * @client: client instance
 * @tc: request to be sent
 * @rc: pointer where a pointer to the response is stored
 *
 */

int
p9_fd_rpc(struct p9_client *client, struct p9_fcall *tc, struct p9_fcall **rc)
{
        struct p9_trans_fd *p = client->trans;
        struct p9_conn *m = p->conn;
        int err, sigpending;
        unsigned long flags;
        struct p9_req *req;

        if (rc)
                *rc = NULL;

        sigpending = 0;
        if (signal_pending(current)) {
                sigpending = 1;
                clear_thread_flag(TIF_SIGPENDING);
        }

        req = p9_send_request(m, tc, p9_conn_rpc_cb, NULL);
        if (IS_ERR(req)) {
                err = PTR_ERR(req);
                P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);
                return err;
        }

        err = wait_event_interruptible(req->wqueue, req->rcall != NULL ||
                                                                req->err < 0);
        if (req->err < 0)
                err = req->err;

        if (err == -ERESTARTSYS && client->status == Connected
                                                        && m->err == 0) {
                if (p9_mux_flush_request(m, req)) {
                        /* wait until we get response of the flush message */
                        do {
                                clear_thread_flag(TIF_SIGPENDING);
                                err = wait_event_interruptible(req->wqueue,
                                        req->rcall || req->err);
                        } while (!req->rcall && !req->err &&
                                        err == -ERESTARTSYS &&
                                        client->status == Connected && !m->err);

                        err = -ERESTARTSYS;
                }
                sigpending = 1;
        }

        if (sigpending) {
                spin_lock_irqsave(&current->sighand->siglock, flags);
                recalc_sigpending();
                spin_unlock_irqrestore(&current->sighand->siglock, flags);
        }

        if (rc)
                *rc = req->rcall;
        else
                kfree(req->rcall);

        p9_mux_free_request(m, req);
        if (err > 0)
                err = -EIO;

        return err;
}

/**
 * parse_options - parse mount options into session structure
 * @options: options string passed from mount
 * @opts: transport-specific structure to parse options into
 *
 * Returns 0 upon success, -ERRNO upon failure
 */

static int parse_opts(char *params, struct p9_fd_opts *opts)
{
        char *p;
        substring_t args[MAX_OPT_ARGS];
        int option;
        char *options;
        int ret;

        opts->port = P9_PORT;
        opts->rfd = ~0;
        opts->wfd = ~0;

        if (!params)
                return 0;

        options = kstrdup(params, GFP_KERNEL);
        if (!options) {
                P9_DPRINTK(P9_DEBUG_ERROR,
                                "failed to allocate copy of option string\n");
                return -ENOMEM;
        }

        while ((p = strsep(&options, ",")) != NULL) {
                int token;
                int r;
                if (!*p)
                        continue;
                token = match_token(p, tokens, args);
                r = match_int(&args[0], &option);
                if (r < 0) {
                        P9_DPRINTK(P9_DEBUG_ERROR,
                         "integer field, but no integer?\n");
                        ret = r;
                        continue;
                }
                switch (token) {
                case Opt_port:
                        opts->port = option;
                        break;
                case Opt_rfdno:
                        opts->rfd = option;
                        break;
                case Opt_wfdno:
                        opts->wfd = option;
                        break;
                default:
                        continue;
                }
        }
        kfree(options);
        return 0;
}

static int p9_fd_open(struct p9_client *client, int rfd, int wfd)
{
        struct p9_trans_fd *ts = kmalloc(sizeof(struct p9_trans_fd),
                                           GFP_KERNEL);
        if (!ts)
                return -ENOMEM;

        ts->rd = fget(rfd);
        ts->wr = fget(wfd);
        if (!ts->rd || !ts->wr) {
                if (ts->rd)
                        fput(ts->rd);
                if (ts->wr)
                        fput(ts->wr);
                kfree(ts);
                return -EIO;
        }

        client->trans = ts;
        client->status = Connected;

        return 0;
}

static int p9_socket_open(struct p9_client *client, struct socket *csocket)
{
        int fd, ret;

        csocket->sk->sk_allocation = GFP_NOIO;
        fd = sock_map_fd(csocket, 0);
        if (fd < 0) {
                P9_EPRINTK(KERN_ERR, "p9_socket_open: failed to map fd\n");
                return fd;
        }

        ret = p9_fd_open(client, fd, fd);
        if (ret < 0) {
                P9_EPRINTK(KERN_ERR, "p9_socket_open: failed to open fd\n");
                sockfd_put(csocket);
                return ret;
        }

        ((struct p9_trans_fd *)client->trans)->rd->f_flags |= O_NONBLOCK;

        return 0;
}

/**
 * p9_mux_destroy - cancels all pending requests and frees mux resources
 * @m: mux to destroy
 *
 */

static void p9_conn_destroy(struct p9_conn *m)
{
        P9_DPRINTK(P9_DEBUG_MUX, "mux %p prev %p next %p\n", m,
                m->mux_list.prev, m->mux_list.next);

        p9_mux_poll_stop(m);
        cancel_work_sync(&m->rq);
        cancel_work_sync(&m->wq);

        p9_conn_cancel(m, -ECONNRESET);

        m->client = NULL;
        p9_idpool_destroy(m->tagpool);
        kfree(m);
}

/**
 * p9_fd_close - shutdown file descriptor transport
 * @client: client instance
 *
 */

static void p9_fd_close(struct p9_client *client)
{
        struct p9_trans_fd *ts;

        if (!client)
                return;

        ts = client->trans;
        if (!ts)
                return;

        client->status = Disconnected;

        p9_conn_destroy(ts->conn);

        if (ts->rd)
                fput(ts->rd);
        if (ts->wr)
                fput(ts->wr);

        kfree(ts);
}

/*
 * stolen from NFS - maybe should be made a generic function?
 */
static inline int valid_ipaddr4(const char *buf)
{
        int rc, count, in[4];

        rc = sscanf(buf, "%d.%d.%d.%d", &in[0], &in[1], &in[2], &in[3]);
        if (rc != 4)
                return -EINVAL;
        for (count = 0; count < 4; count++) {
                if (in[count] > 255)
                        return -EINVAL;
        }
        return 0;
}

static int
p9_fd_create_tcp(struct p9_client *client, const char *addr, char *args)
{
        int err;
        struct socket *csocket;
        struct sockaddr_in sin_server;
        struct p9_fd_opts opts;
        struct p9_trans_fd *p = NULL; /* this gets allocated in p9_fd_open */

        err = parse_opts(args, &opts);
        if (err < 0)
                return err;

        if (valid_ipaddr4(addr) < 0)
                return -EINVAL;

        csocket = NULL;

        sin_server.sin_family = AF_INET;
        sin_server.sin_addr.s_addr = in_aton(addr);
        sin_server.sin_port = htons(opts.port);
        sock_create_kern(PF_INET, SOCK_STREAM, IPPROTO_TCP, &csocket);

        if (!csocket) {
                P9_EPRINTK(KERN_ERR, "p9_trans_tcp: problem creating socket\n");
                err = -EIO;
                goto error;
        }

        err = csocket->ops->connect(csocket,
                                    (struct sockaddr *)&sin_server,
                                    sizeof(struct sockaddr_in), 0);
        if (err < 0) {
                P9_EPRINTK(KERN_ERR,
                        "p9_trans_tcp: problem connecting socket to %s\n",
                        addr);
                goto error;
        }

        err = p9_socket_open(client, csocket);
        if (err < 0)
                goto error;

        p = (struct p9_trans_fd *) client->trans;
        p->conn = p9_conn_create(client);
        if (IS_ERR(p->conn)) {
                err = PTR_ERR(p->conn);
                p->conn = NULL;
                goto error;
        }

        return 0;

error:
        if (csocket)
                sock_release(csocket);

        kfree(p);

        return err;
}

static int
p9_fd_create_unix(struct p9_client *client, const char *addr, char *args)
{
        int err;
        struct socket *csocket;
        struct sockaddr_un sun_server;
        struct p9_trans_fd *p = NULL; /* this gets allocated in p9_fd_open */

        csocket = NULL;

        if (strlen(addr) > UNIX_PATH_MAX) {
                P9_EPRINTK(KERN_ERR, "p9_trans_unix: address too long: %s\n",
                        addr);
                err = -ENAMETOOLONG;
                goto error;
        }

        sun_server.sun_family = PF_UNIX;
        strcpy(sun_server.sun_path, addr);
        sock_create_kern(PF_UNIX, SOCK_STREAM, 0, &csocket);
        err = csocket->ops->connect(csocket, (struct sockaddr *)&sun_server,
                        sizeof(struct sockaddr_un) - 1, 0);
        if (err < 0) {
                P9_EPRINTK(KERN_ERR,
                        "p9_trans_unix: problem connecting socket: %s: %d\n",
                        addr, err);
                goto error;
        }

        err = p9_socket_open(client, csocket);
        if (err < 0)
                goto error;

        p = (struct p9_trans_fd *) client->trans;
        p->conn = p9_conn_create(client);
        if (IS_ERR(p->conn)) {
                err = PTR_ERR(p->conn);
                p->conn = NULL;
                goto error;
        }

        return 0;

error:
        if (csocket)
                sock_release(csocket);

        kfree(p);
        return err;
}

static int
p9_fd_create(struct p9_client *client, const char *addr, char *args)
{
        int err;
        struct p9_fd_opts opts;
        struct p9_trans_fd *p = NULL; /* this get allocated in p9_fd_open */

        parse_opts(args, &opts);

        if (opts.rfd == ~0 || opts.wfd == ~0) {
                printk(KERN_ERR "v9fs: Insufficient options for proto=fd\n");
                return -ENOPROTOOPT;
        }

        err = p9_fd_open(client, opts.rfd, opts.wfd);
        if (err < 0)
                goto error;

        p = (struct p9_trans_fd *) client->trans;
        p->conn = p9_conn_create(client);
        if (IS_ERR(p->conn)) {
                err = PTR_ERR(p->conn);
                p->conn = NULL;
                goto error;
        }

        return 0;

error:
        kfree(p);
        return err;
}

static struct p9_trans_module p9_tcp_trans = {
        .name = "tcp",
        .maxsize = MAX_SOCK_BUF,
        .def = 1,
        .create = p9_fd_create_tcp,
        .close = p9_fd_close,
        .rpc = p9_fd_rpc,
        .owner = THIS_MODULE,
};

static struct p9_trans_module p9_unix_trans = {
        .name = "unix",
        .maxsize = MAX_SOCK_BUF,
        .def = 0,
        .create = p9_fd_create_unix,
        .close = p9_fd_close,
        .rpc = p9_fd_rpc,
        .owner = THIS_MODULE,
};

static struct p9_trans_module p9_fd_trans = {
        .name = "fd",
        .maxsize = MAX_SOCK_BUF,
        .def = 0,
        .create = p9_fd_create,
        .close = p9_fd_close,
        .rpc = p9_fd_rpc,
        .owner = THIS_MODULE,
};

/**
 * p9_poll_proc - poll worker thread
 * @a: thread state and arguments
 *
 * polls all v9fs transports for new events and queues the appropriate
 * work to the work queue
 *
 */

static int p9_poll_proc(void *a)
{
        unsigned long flags;

        P9_DPRINTK(P9_DEBUG_MUX, "start %p\n", current);
 repeat:
        spin_lock_irqsave(&p9_poll_lock, flags);
        while (!list_empty(&p9_poll_pending_list)) {
                struct p9_conn *conn = list_first_entry(&p9_poll_pending_list,
                                                        struct p9_conn,
                                                        poll_pending_link);
                list_del_init(&conn->poll_pending_link);
                spin_unlock_irqrestore(&p9_poll_lock, flags);

                p9_poll_mux(conn);

                spin_lock_irqsave(&p9_poll_lock, flags);
        }
        spin_unlock_irqrestore(&p9_poll_lock, flags);

        set_current_state(TASK_INTERRUPTIBLE);
        if (list_empty(&p9_poll_pending_list)) {
                P9_DPRINTK(P9_DEBUG_MUX, "sleeping...\n");
                schedule();
        }
        __set_current_state(TASK_RUNNING);

        if (!kthread_should_stop())
                goto repeat;

        P9_DPRINTK(P9_DEBUG_MUX, "finish\n");
        return 0;
}

int p9_trans_fd_init(void)
{
        p9_mux_wq = create_workqueue("v9fs");
        if (!p9_mux_wq) {
                printk(KERN_WARNING "v9fs: mux: creating workqueue failed\n");
                return -ENOMEM;
        }

        p9_poll_task = kthread_run(p9_poll_proc, NULL, "v9fs-poll");
        if (IS_ERR(p9_poll_task)) {
                destroy_workqueue(p9_mux_wq);
                printk(KERN_WARNING "v9fs: mux: creating poll task failed\n");
                return PTR_ERR(p9_poll_task);
        }

        v9fs_register_trans(&p9_tcp_trans);
        v9fs_register_trans(&p9_unix_trans);
        v9fs_register_trans(&p9_fd_trans);

        return 0;
}

void p9_trans_fd_exit(void)
{
        kthread_stop(p9_poll_task);
        v9fs_unregister_trans(&p9_tcp_trans);
        v9fs_unregister_trans(&p9_unix_trans);
        v9fs_unregister_trans(&p9_fd_trans);

        destroy_workqueue(p9_mux_wq);
}