path: root/drivers/staging/pohmelfs/net.c

/*
 * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 */

#include <linux/fsnotify.h>
#include <linux/jhash.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/kthread.h>
#include <linux/pagemap.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/syscalls.h>
#include <linux/vmalloc.h>

#include "netfs.h"

/*
 * Async machinery lives here.
 * All commands being sent to server do _not_ require sync reply,
 * instead, if it is really needed, like readdir or readpage, caller
 * sleeps waiting for data, which will be placed into provided buffer
 * and caller will be awakened.
 *
 * Every command response can come without some listener. For example
 * readdir response will add new objects into cache without appropriate
 * request from userspace. This is used in cache coherency.
 *
 * If object is not found for given data, it is discarded.
 *
 * All requests are received by dedicated kernel thread.
 */

/*
 * Basic network sending/receiving functions.
 * Blocked mode is used.
 */
static int netfs_data_recv(struct netfs_state *st, void *buf, u64 size)
{
	struct msghdr msg;
	struct kvec iov;
	int err;

	BUG_ON(!size);

	iov.iov_base = buf;
	iov.iov_len = size;

	msg.msg_iov = (struct iovec *)&iov;
	msg.msg_iovlen = 1;
	msg.msg_name = NULL;
	msg.msg_namelen = 0;
	msg.msg_control = NULL;
	msg.msg_controllen = 0;
	msg.msg_flags = MSG_DONTWAIT;

	err = kernel_recvmsg(st->socket, &msg, &iov, 1, iov.iov_len,
			msg.msg_flags);
	if (err <= 0) {
		printk("%s: failed to recv data: size: %llu, err: %d.\n", __func__, size, err);
		if (err == 0)
			err = -ECONNRESET;
	}

	return err;
}

static int pohmelfs_data_recv(struct netfs_state *st, void *data, unsigned int size)
{
	unsigned int revents = 0;
	unsigned int err_mask = POLLERR | POLLHUP | POLLRDHUP;
	unsigned int mask = err_mask | POLLIN;
	int err = 0;

	while (size && !err) {
		revents = netfs_state_poll(st);

		if (!(revents & mask)) {
			DEFINE_WAIT(wait);

			for (;;) {
				prepare_to_wait(&st->thread_wait, &wait, TASK_INTERRUPTIBLE);
				if (kthread_should_stop())
					break;

				revents = netfs_state_poll(st);

				if (revents & mask)
					break;

				if (signal_pending(current))
					break;

				schedule();
				continue;
			}
			finish_wait(&st->thread_wait, &wait);
		}

		err = 0;
		netfs_state_lock(st);
		if (st->socket && (st->read_socket == st->socket) && (revents & POLLIN)) {
			err = netfs_data_recv(st<