iscsi_tcp.c

linux 内核源代码

/*
 * 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 [e-mail]
 *
 * 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/list.h>
#include <linux/inet.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 <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("Dmitry Yusupov <[e-mail]>, "
	      "Alex Aizman <[e-mail]>");
MODULE_DESCRIPTION("iSCSI/TCP data-path");
MODULE_LICENSE("GPL");
/* #define DEBUG_TCP */
#define DEBUG_ASSERT

#ifdef DEBUG_TCP
#define debug_tcp(fmt...) printk(KERN_INFO "tcp: " fmt)
#else
#define debug_tcp(fmt...)
#endif

#ifndef DEBUG_ASSERT
#ifdef BUG_ON
#undef BUG_ON
#endif
#define BUG_ON(expr)
#endif

static unsigned int iscsi_max_lun = 512;
module_param_named(max_lun, iscsi_max_lun, uint, S_IRUGO);

static inline void
iscsi_buf_init_iov(struct iscsi_buf *ibuf, char *vbuf, int size)
{
	sg_init_one(&ibuf->sg, vbuf, size);
	ibuf->sent = 0;
	ibuf->use_sendmsg = 1;
}

static inline void
iscsi_buf_init_sg(struct iscsi_buf *ibuf, struct scatterlist *sg)
{
	sg_init_table(&ibuf->sg, 1);
	sg_set_page(&ibuf->sg, sg_page(sg), sg->length, sg->offset);
	/*
	 * Fastpath: sg element fits into single page
	 */
	if (sg->length + sg->offset <= PAGE_SIZE && !PageSlab(sg_page(sg)))
		ibuf->use_sendmsg = 0;
	else
		ibuf->use_sendmsg = 1;
	ibuf->sent = 0;
}

static inline int
iscsi_buf_left(struct iscsi_buf *ibuf)
{
	int rc;

	rc = ibuf->sg.length - ibuf->sent;
	BUG_ON(rc < 0);
	return rc;
}

static inline void
iscsi_hdr_digest(struct iscsi_conn *conn, struct iscsi_buf *buf,
		 u8* crc)
{
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;

	crypto_hash_digest(&tcp_conn->tx_hash, &buf->sg, buf->sg.length, crc);
	buf->sg.length += sizeof(u32);
}

static inline int
iscsi_hdr_extract(struct iscsi_tcp_conn *tcp_conn)
{
	struct sk_buff *skb = tcp_conn->in.skb;

	tcp_conn->in.zero_copy_hdr = 0;

	if (tcp_conn->in.copy >= tcp_conn->hdr_size &&
	    tcp_conn->in_progress == IN_PROGRESS_WAIT_HEADER) {
		/*
		 * Zero-copy PDU Header: using connection context
		 * to store header pointer.
		 */
		if (skb_shinfo(skb)->frag_list == NULL &&
		    !skb_shinfo(skb)->nr_frags) {
			tcp_conn->in.hdr = (struct iscsi_hdr *)
				((char*)skb->data + tcp_conn->in.offset);
			tcp_conn->in.zero_copy_hdr = 1;
		} else {
			/* ignoring return code since we checked
			 * in.copy before */
			skb_copy_bits(skb, tcp_conn->in.offset,
				&tcp_conn->hdr, tcp_conn->hdr_size);
			tcp_conn->in.hdr = &tcp_conn->hdr;
		}
		tcp_conn->in.offset += tcp_conn->hdr_size;
		tcp_conn->in.copy -= tcp_conn->hdr_size;
	} else {
		int hdr_remains;
		int copylen;

		/*
		 * PDU header scattered across SKB's,
		 * copying it... This'll happen quite rarely.
		 */

		if (tcp_conn->in_progress == IN_PROGRESS_WAIT_HEADER)
			tcp_conn->in.hdr_offset = 0;

		hdr_remains = tcp_conn->hdr_size - tcp_conn->in.hdr_offset;
		BUG_ON(hdr_remains <= 0);

		copylen = min(tcp_conn->in.copy, hdr_remains);
		skb_copy_bits(skb, tcp_conn->in.offset,
			(char*)&tcp_conn->hdr + tcp_conn->in.hdr_offset,
			copylen);

		debug_tcp("PDU gather offset %d bytes %d in.offset %d "
		       "in.copy %d\n", tcp_conn->in.hdr_offset, copylen,
		       tcp_conn->in.offset, tcp_conn->in.copy);

		tcp_conn->in.offset += copylen;
		tcp_conn->in.copy -= copylen;
		if (copylen < hdr_remains)  {
			tcp_conn->in_progress = IN_PROGRESS_HEADER_GATHER;
			tcp_conn->in.hdr_offset += copylen;
		        return -EAGAIN;
		}
		tcp_conn->in.hdr = &tcp_conn->hdr;
		tcp_conn->discontiguous_hdr_cnt++;
	        tcp_conn->in_progress = IN_PROGRESS_WAIT_HEADER;
	}

	return 0;
}

/*
 * must be called with session lock
 */
static void
iscsi_tcp_cleanup_ctask(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
{
	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
	struct iscsi_r2t_info *r2t;
	struct scsi_cmnd *sc;

	/* flush ctask's r2t queues */
	while (__kfifo_get(tcp_ctask->r2tqueue, (void*)&r2t, sizeof(void*))) {
		__kfifo_put(tcp_ctask->r2tpool.queue, (void*)&r2t,
			    sizeof(void*));
		debug_scsi("iscsi_tcp_cleanup_ctask pending r2t dropped\n");
	}

	sc = ctask->sc;
	if (unlikely(!sc))
		return;

	tcp_ctask->xmstate = XMSTATE_VALUE_IDLE;
	tcp_ctask->r2t = NULL;
}

/**
 * iscsi_data_rsp - SCSI Data-In Response processing
 * @conn: iscsi connection
 * @ctask: scsi command task
 **/
static int
iscsi_data_rsp(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
{
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
	struct iscsi_data_rsp *rhdr = (struct iscsi_data_rsp *)tcp_conn->in.hdr;
	struct iscsi_session *session = conn->session;
	struct scsi_cmnd *sc = ctask->sc;
	int datasn = be32_to_cpu(rhdr->datasn);

	iscsi_update_cmdsn(session, (struct iscsi_nopin*)rhdr);
	/*
	 * setup Data-In byte counter (gets decremented..)
	 */
	ctask->data_count = tcp_conn->in.datalen;

	if (tcp_conn->in.datalen == 0)
		return 0;

	if (tcp_ctask->exp_datasn != datasn) {
		debug_tcp("%s: ctask->exp_datasn(%d) != rhdr->datasn(%d)\n",
		          __FUNCTION__, tcp_ctask->exp_datasn, datasn);
		return ISCSI_ERR_DATASN;
	}

	tcp_ctask->exp_datasn++;

	tcp_ctask->data_offset = be32_to_cpu(rhdr->offset);
	if (tcp_ctask->data_offset + tcp_conn->in.datalen > scsi_bufflen(sc)) {
		debug_tcp("%s: data_offset(%d) + data_len(%d) > total_length_in(%d)\n",
		          __FUNCTION__, tcp_ctask->data_offset,
		          tcp_conn->in.datalen, scsi_bufflen(sc));
		return ISCSI_ERR_DATA_OFFSET;
	}

	if (rhdr->flags & ISCSI_FLAG_DATA_STATUS) {
		conn->exp_statsn = be32_to_cpu(rhdr->statsn) + 1;
		if (rhdr->flags & ISCSI_FLAG_DATA_UNDERFLOW) {
			int res_count = be32_to_cpu(rhdr->residual_count);

			if (res_count > 0 &&
			    res_count <= scsi_bufflen(sc)) {
				scsi_set_resid(sc, res_count);
				sc->result = (DID_OK << 16) | rhdr->cmd_status;
			} else
				sc->result = (DID_BAD_TARGET << 16) |
					rhdr->cmd_status;
		} else if (rhdr->flags & ISCSI_FLAG_DATA_OVERFLOW) {
			scsi_set_resid(sc, be32_to_cpu(rhdr->residual_count));
			sc->result = (DID_OK << 16) | rhdr->cmd_status;
		} else
			sc->result = (DID_OK << 16) | rhdr->cmd_status;
	}

	conn->datain_pdus_cnt++;
	return 0;
}

/**
 * iscsi_solicit_data_init - initialize first Data-Out
 * @conn: iscsi connection
 * @ctask: scsi command task
 * @r2t: R2T info
 *
 * Notes:
 *	Initialize first Data-Out within this R2T sequence and finds
 *	proper data_offset within this SCSI command.
 *
 *	This function is called with connection lock taken.
 **/
static void
iscsi_solicit_data_init(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
			struct iscsi_r2t_info *r2t)
{
	struct iscsi_data *hdr;
	struct scsi_cmnd *sc = ctask->sc;
	int i, sg_count = 0;
	struct scatterlist *sg;

	hdr = &r2t->dtask.hdr;
	memset(hdr, 0, sizeof(struct iscsi_data));
	hdr->ttt = r2t->ttt;
	hdr->datasn = cpu_to_be32(r2t->solicit_datasn);
	r2t->solicit_datasn++;
	hdr->opcode = ISCSI_OP_SCSI_DATA_OUT;
	memcpy(hdr->lun, ctask->hdr->lun, sizeof(hdr->lun));
	hdr->itt = ctask->hdr->itt;
	hdr->exp_statsn = r2t->exp_statsn;
	hdr->offset = cpu_to_be32(r2t->data_offset);
	if (r2t->data_length > conn->max_xmit_dlength) {
		hton24(hdr->dlength, conn->max_xmit_dlength);
		r2t->data_count = conn->max_xmit_dlength;
		hdr->flags = 0;
	} else {
		hton24(hdr->dlength, r2t->data_length);
		r2t->data_count = r2t->data_length;
		hdr->flags = ISCSI_FLAG_CMD_FINAL;
	}
	conn->dataout_pdus_cnt++;

	r2t->sent = 0;

	iscsi_buf_init_iov(&r2t->headbuf, (char*)hdr,
			   sizeof(struct iscsi_hdr));

	sg = scsi_sglist(sc);
	r2t->sg = NULL;
	for (i = 0; i < scsi_sg_count(sc); i++, sg += 1) {
		/* FIXME: prefetch ? */
		if (sg_count + sg->length > r2t->data_offset) {
			int page_offset;

			/* sg page found! */

			/* offset within this page */
			page_offset = r2t->data_offset - sg_count;

			/* fill in this buffer */
			iscsi_buf_init_sg(&r2t->sendbuf, sg);
			r2t->sendbuf.sg.offset += page_offset;
			r2t->sendbuf.sg.length -= page_offset;

			/* xmit logic will continue with next one */
			r2t->sg = sg + 1;
			break;
		}
		sg_count += sg->length;
	}
	BUG_ON(r2t->sg == NULL);
}

/**
 * iscsi_r2t_rsp - iSCSI R2T Response processing
 * @conn: iscsi connection
 * @ctask: scsi command task
 **/
static int
iscsi_r2t_rsp(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
{
	struct iscsi_r2t_info *r2t;
	struct iscsi_session *session = conn->session;
	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct iscsi_r2t_rsp *rhdr = (struct iscsi_r2t_rsp *)tcp_conn->in.hdr;
	int r2tsn = be32_to_cpu(rhdr->r2tsn);
	int rc;

	if (tcp_conn->in.datalen) {
		printk(KERN_ERR "iscsi_tcp: invalid R2t with datalen %d\n",
		       tcp_conn->in.datalen);
		return ISCSI_ERR_DATALEN;
	}

	if (tcp_ctask->exp_datasn != r2tsn){
		debug_tcp("%s: ctask->exp_datasn(%d) != rhdr->r2tsn(%d)\n",
		          __FUNCTION__, tcp_ctask->exp_datasn, r2tsn);
		return ISCSI_ERR_R2TSN;
	}

	/* fill-in new R2T associated with the task */
	spin_lock(&session->lock);
	iscsi_update_cmdsn(session, (struct iscsi_nopin*)rhdr);

	if (!ctask->sc || ctask->mtask ||
	     session->state != ISCSI_STATE_LOGGED_IN) {
		printk(KERN_INFO "iscsi_tcp: dropping R2T itt %d in "
		       "recovery...\n", ctask->itt);
		spin_unlock(&session->lock);
		return 0;
	}

	rc = __kfifo_get(tcp_ctask->r2tpool.queue, (void*)&r2t, sizeof(void*));
	BUG_ON(!rc);

	r2t->exp_statsn = rhdr->statsn;
	r2t->data_length = be32_to_cpu(rhdr->data_length);
	if (r2t->data_length == 0) {
		printk(KERN_ERR "iscsi_tcp: invalid R2T with zero data len\n");
		spin_unlock(&session->lock);
		return ISCSI_ERR_DATALEN;
	}

	if (r2t->data_length > session->max_burst)
		debug_scsi("invalid R2T with data len %u and max burst %u."
			   "Attempting to execute request.\n",
			    r2t->data_length, session->max_burst);

	r2t->data_offset = be32_to_cpu(rhdr->data_offset);
	if (r2t->data_offset + r2t->data_length > scsi_bufflen(ctask->sc)) {
		spin_unlock(&session->lock);
		printk(KERN_ERR "iscsi_tcp: invalid R2T with data len %u at "
		       "offset %u and total length %d\n", r2t->data_length,
		       r2t->data_offset, scsi_bufflen(ctask->sc));
		return ISCSI_ERR_DATALEN;
	}

	r2t->ttt = rhdr->ttt; /* no flip */
	r2t->solicit_datasn = 0;

	iscsi_solicit_data_init(conn, ctask, r2t);

	tcp_ctask->exp_datasn = r2tsn + 1;
	__kfifo_put(tcp_ctask->r2tqueue, (void*)&r2t, sizeof(void*));
	set_bit(XMSTATE_BIT_SOL_HDR_INIT, &tcp_ctask->xmstate);
	list_move_tail(&ctask->running, &conn->xmitqueue);

	scsi_queue_work(session->host, &conn->xmitwork);
	conn->r2t_pdus_cnt++;
	spin_unlock(&session->lock);

	return 0;
}

static int
iscsi_tcp_hdr_recv(struct iscsi_conn *conn)
{
	int rc = 0, opcode, ahslen;
	struct iscsi_hdr *hdr;
	struct iscsi_session *session = conn->session;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	uint32_t cdgst, rdgst = 0, itt;

	hdr = tcp_conn->in.hdr;

	/* verify PDU length */
	tcp_conn->in.datalen = ntoh24(hdr->dlength);
	if (tcp_conn->in.datalen > conn->max_recv_dlength) {
		printk(KERN_ERR "iscsi_tcp: datalen %d > %d\n",
		       tcp_conn->in.datalen, conn->max_recv_dlength);
		return ISCSI_ERR_DATALEN;
	}
	tcp_conn->data_copied = 0;

	/* read AHS */
	ahslen = hdr->hlength << 2;
	tcp_conn->in.offset += ahslen;
	tcp_conn->in.copy -= ahslen;
	if (tcp_conn->in.copy < 0) {
		printk(KERN_ERR "iscsi_tcp: can't handle AHS with length "
		       "%d bytes\n", ahslen);
		return ISCSI_ERR_AHSLEN;
	}

	/* calculate read padding */
	tcp_conn->in.padding = tcp_conn->in.datalen & (ISCSI_PAD_LEN-1);
	if (tcp_conn->in.padding) {
		tcp_conn->in.padding = ISCSI_PAD_LEN - tcp_conn->in.padding;
		debug_scsi("read padding %d bytes\n", tcp_conn->in.padding);
	}

	if (conn->hdrdgst_en) {
		struct scatterlist sg;

		sg_init_one(&sg, (u8 *)hdr,
			    sizeof(struct iscsi_hdr) + ahslen);
		crypto_hash_digest(&tcp_conn->rx_hash, &sg, sg.length,