/*
   * 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
   *
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #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 <linux/slab.h>

  #include <net/9p/9p.h>

  #include <net/9p/client.h>

  #include <net/9p/transport.h>

  #include <linux/syscalls.h> /* killme */

  #define P9_PORT 564

  #define MAX_SOCK_BUF (64*1024)

  #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 */
  };

  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

   * @mux_list: list link for mux to manage multiple connections (?)

   * @client: reference to client instance for this connection

   * @err: error state

   * @req_list: accounting for requests which have been sent
   * @unsent_req_list: accounting for requests that haven't been sent

   * @req: current request being processed (if any)
   * @tmp_buf: temporary buffer to read in header
   * @rsize: amount to read for current frame

   * @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_pending_link: pending links to be polled per conn

   * @poll_wait: array of wait_q's for various worker threads

   * @pt: poll state
   * @rq: current read work
   * @wq: current write work
   * @wsched: ????
   *
   */

  
  struct p9_conn {

  	struct list_head mux_list;

  	struct p9_client *client;

  	int err;

  	struct list_head req_list;
  	struct list_head unsent_req_list;

  	struct p9_req_t *req;
  	char tmp_buf[7];
  	int rsize;

  	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 void p9_poll_workfn(struct work_struct *work);

  static DEFINE_SPINLOCK(p9_poll_lock);
  static LIST_HEAD(p9_poll_pending_list);

  static DECLARE_WORK(p9_poll_work, p9_poll_workfn);

  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

   *

   */

  static void p9_conn_cancel(struct p9_conn *m, int err)

  {

  	struct p9_req_t *req, *rtmp;

  	unsigned long flags;

  	LIST_HEAD(cancel_list);

  	p9_debug(P9_DEBUG_ERROR, "mux %p err %d
  ", m, err);

  	spin_lock_irqsave(&m->client->lock, flags);

  
  	if (m->err) {
  		spin_unlock_irqrestore(&m->client->lock, flags);
  		return;
  	}
  
  	m->err = err;

  	list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {

  		req->status = REQ_STATUS_ERROR;
  		if (!req->t_err)
  			req->t_err = err;

  		list_move(&req->req_list, &cancel_list);
  	}
  	list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {

  		req->status = REQ_STATUS_ERROR;
  		if (!req->t_err)
  			req->t_err = err;

  		list_move(&req->req_list, &cancel_list);

  	}

  	spin_unlock_irqrestore(&m->client->lock, flags);

  	list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {

  		p9_debug(P9_DEBUG_ERROR, "call back req %p
  ", req);

  		list_del(&req->req_list);

  		p9_client_cb(m->client, req);

  	}

  }

  static 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_debug(P9_DEBUG_ERROR, "blocking read ...
  ");

  	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;

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

  
  	if (m->err < 0)
  		return;

  	p9_debug(P9_DEBUG_TRANS, "start mux %p pos %d
  ", m, m->rpos);

  	if (!m->rbuf) {
  		m->rbuf = m->tmp_buf;

  		m->rpos = 0;

  		m->rsize = 7; /* start by reading header */

  	}

  	clear_bit(Rpending, &m->wsched);

  	p9_debug(P9_DEBUG_TRANS, "read mux %p pos %d size: %d = %d
  ",
  		 m, m->rpos, m->rsize, m->rsize-m->rpos);

  	err = p9_fd_read(m->client, m->rbuf + m->rpos,

  						m->rsize - m->rpos);

  	p9_debug(P9_DEBUG_TRANS, "mux %p got %d bytes
  ", m, err);

  	if (err == -EAGAIN) {

  		goto end_clear;

  	}

  	if (err <= 0)
  		goto error;
  
  	m->rpos += err;

  
  	if ((!m->req) && (m->rpos == m->rsize)) { /* header read in */
  		u16 tag;

  		p9_debug(P9_DEBUG_TRANS, "got new header
  ");

  
  		n = le32_to_cpu(*(__le32 *) m->rbuf); /* read packet size */

  		if (n >= m->client->msize) {

  			p9_debug(P9_DEBUG_ERROR,
  				 "requested packet size too big: %d
  ", n);

  			err = -EIO;
  			goto error;
  		}

  		tag = le16_to_cpu(*(__le16 *) (m->rbuf+5)); /* read tag */

  		p9_debug(P9_DEBUG_TRANS,
  			 "mux %p pkt: size: %d bytes tag: %d
  ", m, n, tag);

  
  		m->req = p9_tag_lookup(m->client, tag);

  		if (!m->req || (m->req->status != REQ_STATUS_SENT &&
  					m->req->status != REQ_STATUS_FLSH)) {

  			p9_debug(P9_DEBUG_ERROR, "Unexpected packet tag %d
  ",
  				 tag);

  			err = -EIO;
  			goto error;
  		}
  
  		if (m->req->rc == NULL) {
  			m->req->rc = kmalloc(sizeof(struct p9_fcall) +

  						m->client->msize, GFP_NOFS);

  			if (!m->req->rc) {
  				m->req = NULL;
  				err = -ENOMEM;
  				goto error;
  			}
  		}
  		m->rbuf = (char *)m->req->rc + sizeof(struct p9_fcall);
  		memcpy(m->rbuf, m->tmp_buf, m->rsize);
  		m->rsize = n;
  	}

  	/* not an else because some packets (like clunk) have no payload */
  	if ((m->req) && (m->rpos == m->rsize)) { /* packet is read in */

  		p9_debug(P9_DEBUG_TRANS, "got new packet
  ");

  		spin_lock(&m->client->lock);

  		if (m->req->status != REQ_STATUS_ERROR)
  			m->req->status = REQ_STATUS_RCVD;

  		list_del(&m->req->req_list);

  		spin_unlock(&m->client->lock);

  		p9_client_cb(m->client, m->req);

  		m->rbuf = NULL;
  		m->rpos = 0;
  		m->rsize = 0;

  		m->req = NULL;

  	}

  end_clear:
  	clear_bit(Rworksched, &m->wsched);

  	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) && !test_and_set_bit(Rworksched, &m->wsched)) {

  			p9_debug(P9_DEBUG_TRANS, "sched read work %p
  ", m);

  			schedule_work(&m->rq);

  		}
  	}

  
  	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_debug(P9_DEBUG_ERROR, "blocking write ...
  ");

  	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, (__force 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_t *req;

  
  	m = container_of(work, struct p9_conn, wq);
  
  	if (m->err < 0) {
  		clear_bit(Wworksched, &m->wsched);
  		return;
  	}
  
  	if (!m->wsize) {

  		spin_lock(&m->client->lock);

  		if (list_empty(&m->unsent_req_list)) {
  			clear_bit(Wworksched, &m->wsched);

  			spin_unlock(&m->client->lock);

  			return;
  		}

  		req = list_entry(m->unsent_req_list.next, struct p9_req_t,

  			       req_list);

  		req->status = REQ_STATUS_SENT;

  		p9_debug(P9_DEBUG_TRANS, "move req %p
  ", req);

  		list_move_tail(&req->req_list, &m->req_list);

  		m->wbuf = req->tc->sdata;
  		m->wsize = req->tc->size;

  		m->wpos = 0;

  		spin_unlock(&m->client->lock);

  	}

  	p9_debug(P9_DEBUG_TRANS, "mux %p pos %d size %d
  ",
  		 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_debug(P9_DEBUG_TRANS, "mux %p sent %d bytes
  ", m, err);

  	if (err == -EAGAIN)
  		goto end_clear;

  
  	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;

  end_clear:
  	clear_bit(Wworksched, &m->wsched);

  	if (m->wsize || !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) &&
  		   !test_and_set_bit(Wworksched, &m->wsched)) {

  			p9_debug(P9_DEBUG_TRANS, "sched write work %p
  ", m);

  			schedule_work(&m->wq);

  		}
  	}

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

  static int p9_pollwake(wait_queue_t *wait, unsigned int 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;

  	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);

  	schedule_work(&p9_poll_work);
  	return 1;

  }
  
  /**

   * 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_debug(P9_DEBUG_ERROR, "not enough wait_address slots
  ");

  		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 n;

  	struct p9_conn *m;

  	p9_debug(P9_DEBUG_TRANS, "client %p msize %d
  ", client, client->msize);

  	m = kzalloc(sizeof(struct p9_conn), GFP_KERNEL);
  	if (!m)
  		return ERR_PTR(-ENOMEM);

  	INIT_LIST_HEAD(&m->mux_list);
  	m->client = client;

  	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_debug(P9_DEBUG_TRANS, "mux %p can read
  ", m);

  		set_bit(Rpending, &m->wsched);
  	}

  	if (n & POLLOUT) {

  		p9_debug(P9_DEBUG_TRANS, "mux %p can write
  ", m);

  		set_bit(Wpending, &m->wsched);
  	}

  	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_debug(P9_DEBUG_TRANS, "error mux %p err %d
  ", m, n);

  		if (n >= 0)
  			n = -ECONNRESET;
  		p9_conn_cancel(m, n);
  	}
  
  	if (n & POLLIN) {
  		set_bit(Rpending, &m->wsched);

  		p9_debug(P9_DEBUG_TRANS, "mux %p can read
  ", m);

  		if (!test_and_set_bit(Rworksched, &m->wsched)) {

  			p9_debug(P9_DEBUG_TRANS, "sched read work %p
  ", m);

  			schedule_work(&m->rq);

  		}
  	}

  	if (n & POLLOUT) {
  		set_bit(Wpending, &m->wsched);

  		p9_debug(P9_DEBUG_TRANS, "mux %p can write
  ", m);

  		if ((m->wsize || !list_empty(&m->unsent_req_list)) &&
  		    !test_and_set_bit(Wworksched, &m->wsched)) {

  			p9_debug(P9_DEBUG_TRANS, "sched write work %p
  ", m);

  			schedule_work(&m->wq);

  		}
  	}

  }
  
  /**

   * p9_fd_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.

   *

   * @client: client instance
   * @req: request to be sent

   *

   */

  static int p9_fd_request(struct p9_client *client, struct p9_req_t *req)

  {
  	int n;

  	struct p9_trans_fd *ts = client->trans;
  	struct p9_conn *m = ts->conn;

  	p9_debug(P9_DEBUG_TRANS, "mux %p task %p tcall %p id %d
  ",
  		 m, current, req->tc, req->tc->id);

  	if (m->err < 0)

  		return m->err;

  	spin_lock(&client->lock);

  	req->status = REQ_STATUS_UNSENT;

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

  	spin_unlock(&client->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))

  		schedule_work(&m->wq);

  	return 0;

  }

  static int p9_fd_cancel(struct p9_client *client, struct p9_req_t *req)

  {

  	int ret = 1;

  	p9_debug(P9_DEBUG_TRANS, "client %p req %p
  ", client, req);

  	spin_lock(&client->lock);

  	if (req->status == REQ_STATUS_UNSENT) {

  		list_del(&req->req_list);

  		req->status = REQ_STATUS_FLSHD;

  		ret = 0;

  	} else if (req->status == REQ_STATUS_SENT)
  		req->status = REQ_STATUS_FLSH;

  	spin_unlock(&client->lock);
  
  	return ret;

  }

  /**

   * parse_opts - parse mount options into p9_fd_opts structure
   * @params: options string passed from mount
   * @opts: fd 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, *tmp_options;

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

  	if (!params)
  		return 0;

  	tmp_options = kstrdup(params, GFP_KERNEL);
  	if (!tmp_options) {

  		p9_debug(P9_DEBUG_ERROR,
  			 "failed to allocate copy of option string
  ");

  		return -ENOMEM;
  	}

  	options = tmp_options;

  	while ((p = strsep(&options, ",")) != NULL) {
  		int token;

  		int r;

  		if (!*p)
  			continue;
  		token = match_token(p, tokens, args);

  		if (token != Opt_err) {
  			r = match_int(&args[0], &option);
  			if (r < 0) {

  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?
  ");

  				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(tmp_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)

  {

  	struct p9_trans_fd *p;

  	struct file *file;
  	int ret;

  
  	p = kmalloc(sizeof(struct p9_trans_fd), GFP_KERNEL);
  	if (!p)
  		return -ENOMEM;

  
  	csocket->sk->sk_allocation = GFP_NOIO;

  	file = sock_alloc_file(csocket, 0, NULL);

  	if (IS_ERR(file)) {

  		pr_err("%s (%d): failed to map fd
  ",
  		       __func__, task_pid_nr(current));

  		sock_release(csocket);
  		kfree(p);

  		return PTR_ERR(file);

  	}

  	get_file(file);
  	p->wr = p->rd = file;

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

  	p->rd->f_flags |= O_NONBLOCK;
  
  	p->conn = p9_conn_create(client);
  	if (IS_ERR(p->conn)) {
  		ret = PTR_ERR(p->conn);
  		p->conn = NULL;
  		kfree(p);
  		sockfd_put(csocket);

  		sockfd_put(csocket);
  		return ret;
  	}

  	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_debug(P9_DEBUG_TRANS, "mux %p prev %p next %p
  ",
  		 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;

  	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;

  	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);

  	err = __sock_create(read_pnet(&current->nsproxy->net_ns), PF_INET,
  			    SOCK_STREAM, IPPROTO_TCP, &csocket, 1);

  	if (err) {

  		pr_err("%s (%d): problem creating socket
  ",
  		       __func__, task_pid_nr(current));

  		return err;

  	}
  
  	err = csocket->ops->connect(csocket,
  				    (struct sockaddr *)&sin_server,
  				    sizeof(struct sockaddr_in), 0);
  	if (err < 0) {

  		pr_err("%s (%d): problem connecting socket to %s
  ",
  		       __func__, task_pid_nr(current), addr);

  		sock_release(csocket);

  		return err;
  	}

  	return p9_socket_open(client, csocket);

  }

  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;

  
  	csocket = NULL;

  	if (strlen(addr) >= UNIX_PATH_MAX) {

  		pr_err("%s (%d): address too long: %s
  ",
  		       __func__, task_pid_nr(current), addr);

  		return -ENAMETOOLONG;

  	}
  
  	sun_server.sun_family = PF_UNIX;
  	strcpy(sun_server.sun_path, addr);

  	err = __sock_create(read_pnet(&current->nsproxy->net_ns), PF_UNIX,
  			    SOCK_STREAM, 0, &csocket, 1);

  	if (err < 0) {

  		pr_err("%s (%d): problem creating socket
  ",
  		       __func__, task_pid_nr(current));

  		return err;
  	}

  	err = csocket->ops->connect(csocket, (struct sockaddr *)&sun_server,
  			sizeof(struct sockaddr_un) - 1, 0);
  	if (err < 0) {

  		pr_err("%s (%d): problem connecting socket: %s: %d
  ",
  		       __func__, task_pid_nr(current), addr, err);

  		sock_release(csocket);

  		return err;
  	}

  	return p9_socket_open(client, csocket);

  }

  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;

  
  	parse_opts(args, &opts);
  
  	if (opts.rfd == ~0 || opts.wfd == ~0) {

  		pr_err("Insufficient options for proto=fd
  ");

  		return -ENOPROTOOPT;

  	}

  	err = p9_fd_open(client, opts.rfd, opts.wfd);

  	if (err < 0)

  		return err;

  	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;

  		fput(p->rd);
  		fput(p->wr);
  		return err;

  	}

  	return 0;

  }
  
  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,

  	.request = p9_fd_request,
  	.cancel = p9_fd_cancel,

  	.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,

  	.request = p9_fd_request,
  	.cancel = p9_fd_cancel,

  	.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,

  	.request = p9_fd_request,
  	.cancel = p9_fd_cancel,

  	.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 void p9_poll_workfn(struct work_struct *work)

  {
  	unsigned long flags;

  	p9_debug(P9_DEBUG_TRANS, "start %p
  ", current);

  	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);

  	p9_debug(P9_DEBUG_TRANS, "finish
  ");

  }

  int p9_trans_fd_init(void)

  {
  	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)
  {

  	flush_work(&p9_poll_work);

  	v9fs_unregister_trans(&p9_tcp_trans);
  	v9fs_unregister_trans(&p9_unix_trans);
  	v9fs_unregister_trans(&p9_fd_trans);
  }