path: root/fs/9p/mux.c

/*
 * linux/fs/9p/mux.c
 *
 * Protocol Multiplexer
 *
 *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
 *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
 *
 *  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/config.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/kthread.h>
#include <linux/idr.h>
#include <linux/mutex.h>

#include "debug.h"
#include "v9fs.h"
#include "9p.h"
#include "conv.h"
#include "transport.h"
#include "mux.h"

#define ERREQFLUSH	1
#define SCHED_TIMEOUT	10
#define MAXPOLLWADDR	2

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 v9fs_mux_poll_task;

struct v9fs_req {
	spinlock_t lock;
	int tag;
	struct v9fs_fcall *tcall;
	struct v9fs_fcall *rcall;
	int err;
	v9fs_mux_req_callback cb;
	void *cba;
	int flush;
	struct list_head req_list;
};

struct v9fs_mux_data {
	spinlock_t lock;
	struct list_head mux_list;
	struct v9fs_mux_poll_task *poll_task;
	int msize;
	unsigned char *extended;
	struct v9fs_transport *trans;
	struct v9fs_idpool tagpool;
	int err;
	wait_queue_head_t equeue;
	struct list_head req_list;
	struct list_head unsent_req_list;
	struct v9fs_fcall *rcall;
	int rpos;
	char *rbuf;
	int wpos;
	int wsize;
	char *wbuf;
	wait_queue_t poll_wait[MAXPOLLWADDR];
	wait_queue_head_t *poll_waddr[MAXPOLLWADDR];
	poll_table pt;
	struct work_struct rq;
	struct work_struct wq;
	unsigned long wsched;
};

struct v9fs_mux_poll_task {
	struct task_struct *task;
	struct list_head mux_list;
	int muxnum;
};

struct v9fs_mux_rpc {
	struct v9fs_mux_data *m;
	int err;
	struct v9fs_fcall *tcall;
	struct v9fs_fcall *rcall;
	wait_queue_head_t wqueue;
};

static int v9fs_poll_proc(void *);
static void v9fs_read_work(void *);
static void v9fs_write_work(void *);
static void v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
			  poll_table * p);
static u16 v9fs_mux_get_tag(struct v9fs_mux_data *);
static void v9fs_mux_put_tag(struct v9fs_mux_data *, u16);

static DEFINE_MUTEX(v9fs_mux_task_lock);
static struct workqueue_struct *v9fs_mux_wq;

static int v9fs_mux_num;
static int v9fs_mux_poll_task_num;
static struct v9fs_mux_poll_task v9fs_mux_poll_tasks[100];

int v9fs_mux_global_init(void)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++)
		v9fs_mux_poll_tasks[i].task = NULL;

	v9fs_mux_wq = create_workqueue("v9fs");
	if (!v9fs_mux_wq)
		return -ENOMEM;

	return 0;
}

void v9fs_mux_global_exit(void)
{
	destroy_workqueue(v9fs_mux_wq);
}

/**
 * v9fs_mux_calc_poll_procs - calculates the number of polling procs
 * based on the number of mounted v9fs filesystems.
 *
 * The current implementation returns sqrt of the number of mounts.
 */
static int v9fs_mux_calc_poll_procs(int muxnum)
{
	int n;

	if (v9fs_mux_poll_task_num)
		n = muxnum / v9fs_mux_poll_task_num +
		    (muxnum % v9fs_mux_poll_task_num ? 1 : 0);
	else
		n = 1;

	if (n > ARRAY_SIZE(v9fs_mux_poll_tasks))
		n = ARRAY_SIZE(v9fs_mux_poll_tasks);

	return n;
}

static int v9fs_mux_poll_start(struct v9fs_mux_data *m)
{
	int i, n;
	struct v9fs_mux_poll_task *vpt, *vptlast;
	struct task_struct *pproc;

	dprintk(DEBUG_MUX, "mux %p muxnum %d procnum %d\n", m, v9fs_mux_num,
		v9fs_mux_poll_task_num);
	mutex_lock(&v9fs_mux_task_lock