trans_fd.c 25 KB
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/*
 * 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>
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 *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
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 *  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
 *
 */

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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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#include <linux/in.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/ipv6.h>
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#include <linux/kthread.h>
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#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>
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#include <linux/parser.h>
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#include <linux/slab.h>
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#include <net/9p/9p.h>
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#include <net/9p/client.h>
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#include <net/9p/transport.h>

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

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

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struct p9_fd_opts {
	int rfd;
	int wfd;
	u16 port;
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	int privport;
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};
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/**
 * struct p9_trans_fd - transport state
 * @rd: reference to file to read from
 * @wr: reference of file to write to
 * @conn: connection state reference
 *
 */

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

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/*
  * Option Parsing (code inspired by NFS code)
  *  - a little lazy - parse all fd-transport options
  */
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enum {
	/* Options that take integer arguments */
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	Opt_port, Opt_rfdno, Opt_wfdno, Opt_err,
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	/* Options that take no arguments */
	Opt_privport,
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};
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static const match_table_t tokens = {
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	{Opt_port, "port=%u"},
	{Opt_rfdno, "rfdno=%u"},
	{Opt_wfdno, "wfdno=%u"},
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	{Opt_privport, "privport"},
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	{Opt_err, NULL},
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};
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enum {
	Rworksched = 1,		/* read work scheduled or running */
	Rpending = 2,		/* can read */
	Wworksched = 4,		/* write work scheduled or running */
	Wpending = 8,		/* can write */
};

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

/**
 * struct p9_conn - fd mux connection state information
 * @mux_list: list link for mux to manage multiple connections (?)
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 * @client: reference to client instance for this connection
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 * @err: error state
 * @req_list: accounting for requests which have been sent
 * @unsent_req_list: accounting for requests that haven't been sent
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 * @req: current request being processed (if any)
 * @tmp_buf: temporary buffer to read in header
 * @rsize: amount to read for current frame
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 * @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
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 * @poll_pending_link: pending links to be polled per conn
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 * @poll_wait: array of wait_q's for various worker threads
 * @pt: poll state
 * @rq: current read work
 * @wq: current write work
 * @wsched: ????
 *
 */
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struct p9_conn {
	struct list_head mux_list;
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	struct p9_client *client;
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	int err;
	struct list_head req_list;
	struct list_head unsent_req_list;
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	struct p9_req_t *req;
	char tmp_buf[7];
	int rsize;
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	int rpos;
	char *rbuf;
	int wpos;
	int wsize;
	char *wbuf;
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	struct list_head poll_pending_link;
	struct p9_poll_wait poll_wait[MAXPOLLWADDR];
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	poll_table pt;
	struct work_struct rq;
	struct work_struct wq;
	unsigned long wsched;
};

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static void p9_poll_workfn(struct work_struct *work);

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static DEFINE_SPINLOCK(p9_poll_lock);
static LIST_HEAD(p9_poll_pending_list);
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static DECLARE_WORK(p9_poll_work, p9_poll_workfn);
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static unsigned int p9_ipport_resv_min = P9_DEF_MIN_RESVPORT;
static unsigned int p9_ipport_resv_max = P9_DEF_MAX_RESVPORT;

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static void p9_mux_poll_stop(struct p9_conn *m)
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{
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	unsigned long flags;
	int i;
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	for (i = 0; i < ARRAY_SIZE(m->poll_wait); i++) {
		struct p9_poll_wait *pwait = &m->poll_wait[i];
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		if (pwait->wait_addr) {
			remove_wait_queue(pwait->wait_addr, &pwait->wait);
			pwait->wait_addr = NULL;
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		}
	}

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

/**
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 * p9_conn_cancel - cancel all pending requests with error
 * @m: mux data
 * @err: error code
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 *
 */
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static void p9_conn_cancel(struct p9_conn *m, int err)
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{
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	struct p9_req_t *req, *rtmp;
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	unsigned long flags;
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	LIST_HEAD(cancel_list);
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	p9_debug(P9_DEBUG_ERROR, "mux %p err %d\n", m, err);
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	spin_lock_irqsave(&m->client->lock, flags);
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	if (m->err) {
		spin_unlock_irqrestore(&m->client->lock, flags);
		return;
	}

	m->err = err;

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	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);
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	}
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	spin_unlock_irqrestore(&m->client->lock, flags);
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	list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
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		p9_debug(P9_DEBUG_ERROR, "call back req %p\n", req);
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		list_del(&req->req_list);
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		if (!req->t_err)
			req->t_err = err;
		p9_client_cb(m->client, req, REQ_STATUS_ERROR);
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	}
}

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static int
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p9_fd_poll(struct p9_client *client, struct poll_table_struct *pt)
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{
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	int ret, n;
	struct p9_trans_fd *ts = NULL;
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	if (client && client->status == Connected)
		ts = client->trans;
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	if (!ts)
		return -EREMOTEIO;
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	if (!ts->rd->f_op->poll)
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		return -EIO;
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	if (!ts->wr->f_op->poll)
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		return -EIO;
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	ret = ts->rd->f_op->poll(ts->rd, pt);
	if (ret < 0)
		return ret;
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	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;
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}

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/**
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 * p9_fd_read- read from a fd
 * @client: client instance
 * @v: buffer to receive data into
 * @len: size of receive buffer
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 *
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 */
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static int p9_fd_read(struct p9_client *client, void *v, int len)
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{
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	int ret;
	struct p9_trans_fd *ts = NULL;
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	if (client && client->status != Disconnected)
		ts = client->trans;
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	if (!ts)
		return -EREMOTEIO;
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	if (!(ts->rd->f_flags & O_NONBLOCK))
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		p9_debug(P9_DEBUG_ERROR, "blocking read ...\n");
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	ret = kernel_read(ts->rd, ts->rd->f_pos, v, len);
	if (ret <= 0 && ret != -ERESTARTSYS && ret != -EAGAIN)
		client->status = Disconnected;
	return ret;
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}

/**
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 * p9_read_work - called when there is some data to be read from a transport
 * @work: container of work to be done
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 *
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 */
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static void p9_read_work(struct work_struct *work)
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{
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	int n, err;
	struct p9_conn *m;
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	int status = REQ_STATUS_ERROR;
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	m = container_of(work, struct p9_conn, rq);
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	if (m->err < 0)
		return;

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	p9_debug(P9_DEBUG_TRANS, "start mux %p pos %d\n", m, m->rpos);
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	if (!m->rbuf) {
		m->rbuf = m->tmp_buf;
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		m->rpos = 0;
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		m->rsize = 7; /* start by reading header */
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	}

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	clear_bit(Rpending, &m->wsched);
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	p9_debug(P9_DEBUG_TRANS, "read mux %p pos %d size: %d = %d\n",
		 m, m->rpos, m->rsize, m->rsize-m->rpos);
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	err = p9_fd_read(m->client, m->rbuf + m->rpos,
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						m->rsize - m->rpos);
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	p9_debug(P9_DEBUG_TRANS, "mux %p got %d bytes\n", m, err);
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	if (err == -EAGAIN) {
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		goto end_clear;
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	}

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	if (err <= 0)
		goto error;

	m->rpos += err;
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	if ((!m->req) && (m->rpos == m->rsize)) { /* header read in */
		u16 tag;
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		p9_debug(P9_DEBUG_TRANS, "got new header\n");
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		n = le32_to_cpu(*(__le32 *) m->rbuf); /* read packet size */
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		if (n >= m->client->msize) {
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			p9_debug(P9_DEBUG_ERROR,
				 "requested packet size too big: %d\n", n);
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			err = -EIO;
			goto error;
		}

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		tag = le16_to_cpu(*(__le16 *) (m->rbuf+5)); /* read tag */
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		p9_debug(P9_DEBUG_TRANS,
			 "mux %p pkt: size: %d bytes tag: %d\n", m, n, tag);
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		m->req = p9_tag_lookup(m->client, tag);
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		if (!m->req || (m->req->status != REQ_STATUS_SENT)) {
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			p9_debug(P9_DEBUG_ERROR, "Unexpected packet tag %d\n",
				 tag);
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			err = -EIO;
			goto error;
		}

		if (m->req->rc == NULL) {
			m->req->rc = kmalloc(sizeof(struct p9_fcall) +
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						m->client->msize, GFP_NOFS);
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			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;
	}
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	/* not an else because some packets (like clunk) have no payload */
	if ((m->req) && (m->rpos == m->rsize)) { /* packet is read in */
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		p9_debug(P9_DEBUG_TRANS, "got new packet\n");
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		spin_lock(&m->client->lock);
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		if (m->req->status != REQ_STATUS_ERROR)
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			status = REQ_STATUS_RCVD;
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		list_del(&m->req->req_list);
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		spin_unlock(&m->client->lock);
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		p9_client_cb(m->client, m->req, status);
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		m->rbuf = NULL;
		m->rpos = 0;
		m->rsize = 0;
		m->req = NULL;
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	}

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

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

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		if ((n & POLLIN) && !test_and_set_bit(Rworksched, &m->wsched)) {
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			p9_debug(P9_DEBUG_TRANS, "sched read work %p\n", m);
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			schedule_work(&m->rq);
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		}
	}
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	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
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 *
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 */
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static int p9_fd_write(struct p9_client *client, void *v, int len)
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{
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	int ret;
	mm_segment_t oldfs;
	struct p9_trans_fd *ts = NULL;
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	if (client && client->status != Disconnected)
		ts = client->trans;
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	if (!ts)
		return -EREMOTEIO;
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	if (!(ts->wr->f_flags & O_NONBLOCK))
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		p9_debug(P9_DEBUG_ERROR, "blocking write ...\n");
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	oldfs = get_fs();
	set_fs(get_ds());
	/* The cast to a user pointer is valid due to the set_fs() */
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	ret = vfs_write(ts->wr, (__force void __user *)v, len, &ts->wr->f_pos);
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	set_fs(oldfs);
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	if (ret <= 0 && ret != -ERESTARTSYS && ret != -EAGAIN)
		client->status = Disconnected;
	return ret;
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}

/**
 * p9_write_work - called when a transport can send some data
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 * @work: container for work to be done
 *
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 */
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static void p9_write_work(struct work_struct *work)
{
	int n, err;
	struct p9_conn *m;
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	struct p9_req_t *req;
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	m = container_of(work, struct p9_conn, wq);

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

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

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		req = list_entry(m->unsent_req_list.next, struct p9_req_t,
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			       req_list);
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		req->status = REQ_STATUS_SENT;
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		p9_debug(P9_DEBUG_TRANS, "move req %p\n", req);
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		list_move_tail(&req->req_list, &m->req_list);

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

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	p9_debug(P9_DEBUG_TRANS, "mux %p pos %d size %d\n",
		 m, m->wpos, m->wsize);
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	clear_bit(Wpending, &m->wsched);
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	err = p9_fd_write(m->client, m->wbuf + m->wpos, m->wsize - m->wpos);
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	p9_debug(P9_DEBUG_TRANS, "mux %p sent %d bytes\n", m, err);
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	if (err == -EAGAIN)
		goto end_clear;

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	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;

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

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	if (m->wsize || !list_empty(&m->unsent_req_list)) {
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		if (test_and_clear_bit(Wpending, &m->wsched))
			n = POLLOUT;
		else
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			n = p9_fd_poll(m->client, NULL);
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		if ((n & POLLOUT) &&
		   !test_and_set_bit(Wworksched, &m->wsched)) {
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			p9_debug(P9_DEBUG_TRANS, "sched write work %p\n", m);
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			schedule_work(&m->wq);
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		}
	}
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	return;

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

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static int p9_pollwake(wait_queue_t *wait, unsigned int mode, int sync, void *key)
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{
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	struct p9_poll_wait *pwait =
		container_of(wait, struct p9_poll_wait, wait);
	struct p9_conn *m = pwait->conn;
	unsigned long flags;
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	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);
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	schedule_work(&p9_poll_work);
	return 1;
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}

/**
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 * p9_pollwait - add poll task to the wait queue
 * @filp: file pointer being polled
 * @wait_address: wait_q to block on
 * @p: poll state
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 *
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 * called by files poll operation to add v9fs-poll task to files wait queue
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 */
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static void
p9_pollwait(struct file *filp, wait_queue_head_t *wait_address, poll_table *p)
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{
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	struct p9_conn *m = container_of(p, struct p9_conn, pt);
	struct p9_poll_wait *pwait = NULL;
	int i;
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	for (i = 0; i < ARRAY_SIZE(m->poll_wait); i++) {
		if (m->poll_wait[i].wait_addr == NULL) {
			pwait = &m->poll_wait[i];
			break;
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		}
	}

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	if (!pwait) {
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		p9_debug(P9_DEBUG_ERROR, "not enough wait_address slots\n");
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		return;
	}

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	pwait->conn = m;
	pwait->wait_addr = wait_address;
	init_waitqueue_func_entry(&pwait->wait, p9_pollwake);
	add_wait_queue(wait_address, &pwait->wait);
}
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/**
 * 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.
 */
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static struct p9_conn *p9_conn_create(struct p9_client *client)
{
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	int n;
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	struct p9_conn *m;
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	p9_debug(P9_DEBUG_TRANS, "client %p msize %d\n", client, client->msize);
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	m = kzalloc(sizeof(struct p9_conn), GFP_KERNEL);
	if (!m)
		return ERR_PTR(-ENOMEM);
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	INIT_LIST_HEAD(&m->mux_list);
	m->client = client;
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	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);
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	n = p9_fd_poll(client, &m->pt);
	if (n & POLLIN) {
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		p9_debug(P9_DEBUG_TRANS, "mux %p can read\n", m);
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		set_bit(Rpending, &m->wsched);
	}
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	if (n & POLLOUT) {
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		p9_debug(P9_DEBUG_TRANS, "mux %p can write\n", m);
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		set_bit(Wpending, &m->wsched);
	}

	return m;
}
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/**
 * 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)) {
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		p9_debug(P9_DEBUG_TRANS, "error mux %p err %d\n", m, n);
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		if (n >= 0)
			n = -ECONNRESET;
		p9_conn_cancel(m, n);
	}

	if (n & POLLIN) {
		set_bit(Rpending, &m->wsched);
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		p9_debug(P9_DEBUG_TRANS, "mux %p can read\n", m);
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		if (!test_and_set_bit(Rworksched, &m->wsched)) {
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			p9_debug(P9_DEBUG_TRANS, "sched read work %p\n", m);
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			schedule_work(&m->rq);
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		}
	}
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	if (n & POLLOUT) {
		set_bit(Wpending, &m->wsched);
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		p9_debug(P9_DEBUG_TRANS, "mux %p can write\n", m);
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		if ((m->wsize || !list_empty(&m->unsent_req_list)) &&
		    !test_and_set_bit(Wworksched, &m->wsched)) {
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			p9_debug(P9_DEBUG_TRANS, "sched write work %p\n", m);
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			schedule_work(&m->wq);
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		}
	}
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}

/**
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 * p9_fd_request - send 9P request
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 * The function can sleep until the request is scheduled for sending.
 * The function can be interrupted. Return from the function is not
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 * a guarantee that the request is sent successfully.
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 *
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 * @client: client instance
 * @req: request to be sent
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 *
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 */
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static int p9_fd_request(struct p9_client *client, struct p9_req_t *req)
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{
	int n;
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	struct p9_trans_fd *ts = client->trans;
	struct p9_conn *m = ts->conn;
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	p9_debug(P9_DEBUG_TRANS, "mux %p task %p tcall %p id %d\n",
		 m, current, req->tc, req->tc->id);
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	if (m->err < 0)
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		return m->err;
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	spin_lock(&client->lock);
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	req->status = REQ_STATUS_UNSENT;
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	list_add_tail(&req->req_list, &m->unsent_req_list);
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	spin_unlock(&client->lock);
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	if (test_and_clear_bit(Wpending, &m->wsched))
		n = POLLOUT;
	else
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		n = p9_fd_poll(m->client, NULL);
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	if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
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		schedule_work(&m->wq);
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	return 0;
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}

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static int p9_fd_cancel(struct p9_client *client, struct p9_req_t *req)
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{
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	int ret = 1;
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	p9_debug(P9_DEBUG_TRANS, "client %p req %p\n", client, req);
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	spin_lock(&client->lock);

	if (req->status == REQ_STATUS_UNSENT) {
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		list_del(&req->req_list);
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		req->status = REQ_STATUS_FLSHD;
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		ret = 0;
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	}
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	spin_unlock(&client->lock);

	return ret;
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}

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static int p9_fd_cancelled(struct p9_client *client, struct p9_req_t *req)
{
	p9_debug(P9_DEBUG_TRANS, "client %p req %p\n", client, req);

	/* we haven't received a response for oldreq,
	 * remove it from the list.
	 */
	spin_lock(&client->lock);
	list_del(&req->req_list);
	spin_unlock(&client->lock);

	return 0;
}

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/**
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 * 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
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 *
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 * Returns 0 upon success, -ERRNO upon failure
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 */
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static int parse_opts(char *params, struct p9_fd_opts *opts)
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{
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	char *p;
	substring_t args[MAX_OPT_ARGS];
	int option;
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	char *options, *tmp_options;
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	opts->port = P9_PORT;
	opts->rfd = ~0;
	opts->wfd = ~0;
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	if (!params)
		return 0;

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	tmp_options = kstrdup(params, GFP_KERNEL);
	if (!tmp_options) {
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		p9_debug(P9_DEBUG_ERROR,
			 "failed to allocate copy of option string\n");
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		return -ENOMEM;
	}
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	options = tmp_options;
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	while ((p = strsep(&options, ",")) != NULL) {
		int token;
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		int r;
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		if (!*p)
			continue;
		token = match_token(p, tokens, args);
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		if ((token != Opt_err) && (token != Opt_privport)) {
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			r = match_int(&args[0], &option);
			if (r < 0) {
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				p9_debug(P9_DEBUG_ERROR,
					 "integer field, but no integer?\n");
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				continue;
			}
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		}
		switch (token) {
		case Opt_port:
			opts->port = option;
			break;
		case Opt_rfdno:
			opts->rfd = option;
			break;
		case Opt_wfdno:
			opts->wfd = option;
			break;
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		case Opt_privport:
			opts->privport = 1;
			break;
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		default:
			continue;
		}
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	}
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	kfree(tmp_options);
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	return 0;
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}

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

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	client->trans = ts;
	client->status = Connected;
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	return 0;
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}

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static int p9_socket_open(struct p9_client *client, struct socket *csocket)
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{
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	struct p9_trans_fd *p;
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	struct file *file;
	int ret;
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	p = kmalloc(sizeof(struct p9_trans_fd), GFP_KERNEL);
	if (!p)
		return -ENOMEM;
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	csocket->sk->sk_allocation = GFP_NOIO;
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	file = sock_alloc_file(csocket, 0, NULL);
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	if (IS_ERR(file)) {
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		pr_err("%s (%d): failed to map fd\n",
		       __func__, task_pid_nr(current));
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		sock_release(csocket);
		kfree(p);
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		return PTR_ERR(file);
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	}