path: root/drivers/scsi/iscsi_tcp.c

/*
 * iSCSI Initiator over TCP/IP Data-Path
 *
 * Copyright (C) 2004 Dmitry Yusupov
 * Copyright (C) 2004 Alex Aizman
 * Copyright (C) 2005 - 2006 Mike Christie
 * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
 * maintained by open-iscsi@googlegroups.com
 *
 * 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.
 *
 * See the file COPYING included with this distribution for more details.
 *
 * Credits:
 *	Christoph Hellwig
 *	FUJITA Tomonori
 *	Arne Redlich
 *	Zhenyu Wang
 */

#include <linux/types.h>
#include <linux/inet.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/blkdev.h>
#include <linux/crypto.h>
#include <linux/delay.h>
#include <linux/kfifo.h>
#include <linux/scatterlist.h>
#include <linux/module.h>
#include <net/tcp.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi.h>
#include <scsi/scsi_transport_iscsi.h>

#include "iscsi_tcp.h"

MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, "
	      "Dmitry Yusupov <dmitry_yus@yahoo.com>, "
	      "Alex Aizman <itn780@yahoo.com>");
MODULE_DESCRIPTION("iSCSI/TCP data-path");
MODULE_LICENSE("GPL");

static struct scsi_transport_template *iscsi_sw_tcp_scsi_transport;
static struct scsi_host_template iscsi_sw_tcp_sht;
static struct iscsi_transport iscsi_sw_tcp_transport;

static unsigned int iscsi_max_lun = ~0;
module_param_named(max_lun, iscsi_max_lun, uint, S_IRUGO);

static int iscsi_sw_tcp_dbg;
module_param_named(debug_iscsi_tcp, iscsi_sw_tcp_dbg, int,
		   S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug_iscsi_tcp, "Turn on debugging for iscsi_tcp module "
		 "Set to 1 to turn on, and zero to turn off. Default is off.");

#define ISCSI_SW_TCP_DBG(_conn, dbg_fmt, arg...)		\
	do {							\
		if (iscsi_sw_tcp_dbg)				\
			iscsi_conn_printk(KERN_INFO, _conn,	\
					     "%s " dbg_fmt,	\
					     __func__, ##arg);	\
	} while (0);


/**
 * iscsi_sw_tcp_recv - TCP receive in sendfile fashion
 * @rd_desc: read descriptor
 * @skb: socket buffer
 * @offset: offset in skb
 * @len: skb->len - offset
 */
static int iscsi_sw_tcp_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
			     unsigned int offset, size_t len)
{
	struct iscsi_conn *conn = rd_desc->arg.data;
	unsigned int consumed, total_consumed = 0;
	int status;

	ISCSI_SW_TCP_DBG(conn, "in %d bytes\n", skb->len - offset);

	do {
		status = 0;
		consumed = iscsi_tcp_recv_skb(conn, skb, offset, 0, &status);
		offset += consumed;
		total_consumed += consumed;
	} while (consumed != 0 && status != ISCSI_TCP_SKB_DONE);

	ISCSI_SW_TCP_DBG(conn, "read %d bytes status %d\n",
			 skb->len - offset, status);
	return total_consumed;
}

/**
 * iscsi_sw_sk_state_check - check socket state
 * @sk: socket
 *
 * If the socket is in CLOSE or CLOSE_WAIT we should
 * not close the connection if there is still some
 * data pending.
 *
 * Must be called with sk_callback_lock.
 */
static inline int iscsi_sw_sk_state_check(struct sock *sk)
{
	struct iscsi_conn *conn = sk->sk_user_data;

	if ((sk->sk_state == TCP_CLOSE_WAIT || sk->sk_state == TCP_CLOSE) &&
	    !atomic_read(&sk->sk_rmem_alloc)) {
		ISCSI_SW_TCP_DBG(conn, "TCP_CLOSE|TCP_CLOSE_WAIT\n");
		iscsi_conn_failure(conn, ISCSI_ERR_TCP_CONN_CLOSE);
		return -ECONNRESET;
	}
	return 0;
}

static void iscsi_sw_tcp_data_ready(struct sock *sk, int flag)
{
	struct iscsi_conn *conn;
	struct iscsi_tcp_conn *tcp_conn;
	read_descriptor_t rd_desc;

	read_lock(&sk->sk_callback_lock);
	conn = sk->sk_user_data;
	if (!conn) {
		read_unlock(&sk->sk_callback_lock);
		return;
	}
	tcp_conn = conn->dd_data;

	/*
	 * Use rd_desc to pass 'conn' to iscsi_tcp_recv.
	 * We set count to 1 because we want the network layer to
	 * hand us all the skbs that are available. iscsi_tcp_recv
	 * handled pdus that cross buffers or pdus that still need data.
	 */
	rd_desc.arg.data = conn;
	rd_desc.count = 1;
	tcp_read_sock(sk, &rd_desc, iscsi_sw_tcp_recv);

	iscsi_sw_sk_state_check(sk);

	/* If we had to (atomically) map a highmem page,
	 * unmap it now. */
	iscsi_tcp_segment_unmap(&tcp_conn->in.segment);
	read_unlock(&sk->sk_callback_lock);
}

static void iscsi_sw_tcp_state_change(struct sock *sk)
{
	struct iscsi_tcp_conn *tcp_conn;
	struct iscsi_sw_tcp_conn *tcp_sw_conn;
	struct iscsi_conn *conn;
	struct iscsi_session *session;
	void (*old_state_change)(struct sock *);

	read_lock(&sk->sk_callback_lock);
	conn = sk->sk_user_data;
	if (!conn) {
		read_unlock(&sk->sk_callback_lock);
		return;
	}
	session = conn->session;

	iscsi_sw_sk_stat