libiscsi.c

linux 内核源代码

/*
 * iSCSI lib functions
 *
 * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
 * Copyright (C) 2004 - 2006 Mike Christie
 * Copyright (C) 2004 - 2005 Dmitry Yusupov
 * Copyright (C) 2004 - 2005 Alex Aizman
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */
#include <linux/types.h>
#include <linux/kfifo.h>
#include <linux/delay.h>
#include <asm/unaligned.h>
#include <net/tcp.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi.h>
#include <scsi/iscsi_proto.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_transport_iscsi.h>
#include <scsi/libiscsi.h>

struct iscsi_session *
class_to_transport_session(struct iscsi_cls_session *cls_session)
{
	struct Scsi_Host *shost = iscsi_session_to_shost(cls_session);
	return iscsi_hostdata(shost->hostdata);
}
EXPORT_SYMBOL_GPL(class_to_transport_session);

/* Serial Number Arithmetic, 32 bits, less than, RFC1982 */
#define SNA32_CHECK 2147483648UL

static int iscsi_sna_lt(u32 n1, u32 n2)
{
	return n1 != n2 && ((n1 < n2 && (n2 - n1 < SNA32_CHECK)) ||
			    (n1 > n2 && (n2 - n1 < SNA32_CHECK)));
}

/* Serial Number Arithmetic, 32 bits, less than, RFC1982 */
static int iscsi_sna_lte(u32 n1, u32 n2)
{
	return n1 == n2 || ((n1 < n2 && (n2 - n1 < SNA32_CHECK)) ||
			    (n1 > n2 && (n2 - n1 < SNA32_CHECK)));
}

void
iscsi_update_cmdsn(struct iscsi_session *session, struct iscsi_nopin *hdr)
{
	uint32_t max_cmdsn = be32_to_cpu(hdr->max_cmdsn);
	uint32_t exp_cmdsn = be32_to_cpu(hdr->exp_cmdsn);

	/*
	 * standard specifies this check for when to update expected and
	 * max sequence numbers
	 */
	if (iscsi_sna_lt(max_cmdsn, exp_cmdsn - 1))
		return;

	if (exp_cmdsn != session->exp_cmdsn &&
	    !iscsi_sna_lt(exp_cmdsn, session->exp_cmdsn))
		session->exp_cmdsn = exp_cmdsn;

	if (max_cmdsn != session->max_cmdsn &&
	    !iscsi_sna_lt(max_cmdsn, session->max_cmdsn)) {
		session->max_cmdsn = max_cmdsn;
		/*
		 * if the window closed with IO queued, then kick the
		 * xmit thread
		 */
		if (!list_empty(&session->leadconn->xmitqueue) ||
		    __kfifo_len(session->leadconn->mgmtqueue))
			scsi_queue_work(session->host,
					&session->leadconn->xmitwork);
	}
}
EXPORT_SYMBOL_GPL(iscsi_update_cmdsn);

void iscsi_prep_unsolicit_data_pdu(struct iscsi_cmd_task *ctask,
				   struct iscsi_data *hdr)
{
	struct iscsi_conn *conn = ctask->conn;

	memset(hdr, 0, sizeof(struct iscsi_data));
	hdr->ttt = cpu_to_be32(ISCSI_RESERVED_TAG);
	hdr->datasn = cpu_to_be32(ctask->unsol_datasn);
	ctask->unsol_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 = cpu_to_be32(conn->exp_statsn);
	hdr->offset = cpu_to_be32(ctask->unsol_offset);

	if (ctask->unsol_count > conn->max_xmit_dlength) {
		hton24(hdr->dlength, conn->max_xmit_dlength);
		ctask->data_count = conn->max_xmit_dlength;
		ctask->unsol_offset += ctask->data_count;
		hdr->flags = 0;
	} else {
		hton24(hdr->dlength, ctask->unsol_count);
		ctask->data_count = ctask->unsol_count;
		hdr->flags = ISCSI_FLAG_CMD_FINAL;
	}
}
EXPORT_SYMBOL_GPL(iscsi_prep_unsolicit_data_pdu);

/**
 * iscsi_prep_scsi_cmd_pdu - prep iscsi scsi cmd pdu
 * @ctask: iscsi cmd task
 *
 * Prep basic iSCSI PDU fields for a scsi cmd pdu. The LLD should set
 * fields like dlength or final based on how much data it sends
 */
static void iscsi_prep_scsi_cmd_pdu(struct iscsi_cmd_task *ctask)
{
	struct iscsi_conn *conn = ctask->conn;
	struct iscsi_session *session = conn->session;
	struct iscsi_cmd *hdr = ctask->hdr;
	struct scsi_cmnd *sc = ctask->sc;

        hdr->opcode = ISCSI_OP_SCSI_CMD;
        hdr->flags = ISCSI_ATTR_SIMPLE;
        int_to_scsilun(sc->device->lun, (struct scsi_lun *)hdr->lun);
        hdr->itt = build_itt(ctask->itt, conn->id, session->age);
        hdr->data_length = cpu_to_be32(scsi_bufflen(sc));
        hdr->cmdsn = cpu_to_be32(session->cmdsn);
        session->cmdsn++;
        hdr->exp_statsn = cpu_to_be32(conn->exp_statsn);
        memcpy(hdr->cdb, sc->cmnd, sc->cmd_len);
	if (sc->cmd_len < MAX_COMMAND_SIZE)
		memset(&hdr->cdb[sc->cmd_len], 0,
			MAX_COMMAND_SIZE - sc->cmd_len);

	ctask->data_count = 0;
	ctask->imm_count = 0;
	if (sc->sc_data_direction == DMA_TO_DEVICE) {
		hdr->flags |= ISCSI_FLAG_CMD_WRITE;
		/*
		 * Write counters:
		 *
		 *	imm_count	bytes to be sent right after
		 *			SCSI PDU Header
		 *
		 *	unsol_count	bytes(as Data-Out) to be sent
		 *			without	R2T ack right after
		 *			immediate data
		 *
		 *	r2t_data_count	bytes to be sent via R2T ack's
		 *
		 *      pad_count       bytes to be sent as zero-padding
		 */
		ctask->unsol_count = 0;
		ctask->unsol_offset = 0;
		ctask->unsol_datasn = 0;

		if (session->imm_data_en) {
			if (scsi_bufflen(sc) >= session->first_burst)
				ctask->imm_count = min(session->first_burst,
							conn->max_xmit_dlength);
			else
				ctask->imm_count = min(scsi_bufflen(sc),
							conn->max_xmit_dlength);
			hton24(ctask->hdr->dlength, ctask->imm_count);
		} else
			zero_data(ctask->hdr->dlength);

		if (!session->initial_r2t_en) {
			ctask->unsol_count = min((session->first_burst),
				(scsi_bufflen(sc))) - ctask->imm_count;
			ctask->unsol_offset = ctask->imm_count;
		}

		if (!ctask->unsol_count)
			/* No unsolicit Data-Out's */
			ctask->hdr->flags |= ISCSI_FLAG_CMD_FINAL;
	} else {
		hdr->flags |= ISCSI_FLAG_CMD_FINAL;
		zero_data(hdr->dlength);

		if (sc->sc_data_direction == DMA_FROM_DEVICE)
			hdr->flags |= ISCSI_FLAG_CMD_READ;
	}

	conn->scsicmd_pdus_cnt++;

        debug_scsi("iscsi prep [%s cid %d sc %p cdb 0x%x itt 0x%x len %d "
		"cmdsn %d win %d]\n",
                sc->sc_data_direction == DMA_TO_DEVICE ? "write" : "read",
		conn->id, sc, sc->cmnd[0], ctask->itt, scsi_bufflen(sc),
                session->cmdsn, session->max_cmdsn - session->exp_cmdsn + 1);
}

/**
 * iscsi_complete_command - return command back to scsi-ml
 * @ctask: iscsi cmd task
 *
 * Must be called with session lock.
 * This function returns the scsi command to scsi-ml and returns
 * the cmd task to the pool of available cmd tasks.
 */
static void iscsi_complete_command(struct iscsi_cmd_task *ctask)
{
	struct iscsi_session *session = ctask->conn->session;
	struct scsi_cmnd *sc = ctask->sc;

	ctask->state = ISCSI_TASK_COMPLETED;
	ctask->sc = NULL;
	/* SCSI eh reuses commands to verify us */
	sc->SCp.ptr = NULL;
	list_del_init(&ctask->running);
	__kfifo_put(session->cmdpool.queue, (void*)&ctask, sizeof(void*));
	sc->scsi_done(sc);
}

static void __iscsi_get_ctask(struct iscsi_cmd_task *ctask)
{
	atomic_inc(&ctask->refcount);
}

static void __iscsi_put_ctask(struct iscsi_cmd_task *ctask)
{
	if (atomic_dec_and_test(&ctask->refcount))
		iscsi_complete_command(ctask);
}

/**
 * iscsi_cmd_rsp - SCSI Command Response processing
 * @conn: iscsi connection
 * @hdr: iscsi header
 * @ctask: scsi command task
 * @data: cmd data buffer
 * @datalen: len of buffer
 *
 * iscsi_cmd_rsp sets up the scsi_cmnd fields based on the PDU and
 * then completes the command and task.
 **/
static void iscsi_scsi_cmd_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
			       struct iscsi_cmd_task *ctask, char *data,
			       int datalen)
{
	struct iscsi_cmd_rsp *rhdr = (struct iscsi_cmd_rsp *)hdr;
	struct iscsi_session *session = conn->session;
	struct scsi_cmnd *sc = ctask->sc;

	iscsi_update_cmdsn(session, (struct iscsi_nopin*)rhdr);
	conn->exp_statsn = be32_to_cpu(rhdr->statsn) + 1;

	sc->result = (DID_OK << 16) | rhdr->cmd_status;

	if (rhdr->response != ISCSI_STATUS_CMD_COMPLETED) {
		sc->result = DID_ERROR << 16;
		goto out;
	}

	if (rhdr->cmd_status == SAM_STAT_CHECK_CONDITION) {
		uint16_t senselen;

		if (datalen < 2) {
invalid_datalen:
			printk(KERN_ERR "iscsi: Got CHECK_CONDITION but "
			       "invalid data buffer size of %d\n", datalen);
			sc->result = DID_BAD_TARGET << 16;
			goto out;
		}

		senselen = be16_to_cpu(get_unaligned((__be16 *) data));
		if (datalen < senselen)
			goto invalid_datalen;

		memcpy(sc->sense_buffer, data + 2,
		       min_t(uint16_t, senselen, SCSI_SENSE_BUFFERSIZE));
		debug_scsi("copied %d bytes of sense\n",
			   min_t(uint16_t, senselen, SCSI_SENSE_BUFFERSIZE));
	}

	if (rhdr->flags & ISCSI_FLAG_CMD_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);
		else
			sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
	} else if (rhdr->flags & ISCSI_FLAG_CMD_BIDI_UNDERFLOW)
		sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
	else if (rhdr->flags & ISCSI_FLAG_CMD_OVERFLOW)
		scsi_set_resid(sc, be32_to_cpu(rhdr->residual_count));

out:
	debug_scsi("done [sc %lx res %d itt 0x%x]\n",
		   (long)sc, sc->result, ctask->itt);
	conn->scsirsp_pdus_cnt++;

	__iscsi_put_ctask(ctask);
}

static void iscsi_tmf_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
{
	struct iscsi_tm_rsp *tmf = (struct iscsi_tm_rsp *)hdr;

	conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
	conn->tmfrsp_pdus_cnt++;

	if (conn->tmabort_state != TMABORT_INITIAL)
		return;

	if (tmf->response == ISCSI_TMF_RSP_COMPLETE)
		conn->tmabort_state = TMABORT_SUCCESS;
	else if (tmf->response == ISCSI_TMF_RSP_NO_TASK)
		conn->tmabort_state = TMABORT_NOT_FOUND;
	else
		conn->tmabort_state = TMABORT_FAILED;
	wake_up(&conn->ehwait);
}

static int iscsi_handle_reject(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
			       char *data, int datalen)
{
	struct iscsi_reject *reject = (struct iscsi_reject *)hdr;
	struct iscsi_hdr rejected_pdu;
	uint32_t itt;

	conn->exp_statsn = be32_to_cpu(reject->statsn) + 1;

	if (reject->reason == ISCSI_REASON_DATA_DIGEST_ERROR) {
		if (ntoh24(reject->dlength) > datalen)
			return ISCSI_ERR_PROTO;

		if (ntoh24(reject->dlength) >= sizeof(struct iscsi_hdr)) {
			memcpy(&rejected_pdu, data, sizeof(struct iscsi_hdr));
			itt = get_itt(rejected_pdu.itt);
			printk(KERN_ERR "itt 0x%x had pdu (op 0x%x) rejected "
				"due to DataDigest error.\n", itt,
				rejected_pdu.opcode);
		}
	}
	return 0;
}

/**
 * __iscsi_complete_pdu - complete pdu
 * @conn: iscsi conn
 * @hdr: iscsi header
 * @data: data buffer
 * @datalen: len of data buffer
 *
 * Completes pdu processing by freeing any resources allocated at
 * queuecommand or send generic. session lock must be held and verify
 * itt must have been called.
 */
int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
			 char *data, int datalen)
{
	struct iscsi_session *session = conn->session;
	int opcode = hdr->opcode & ISCSI_OPCODE_MASK, rc = 0;
	struct iscsi_cmd_task *ctask;
	struct iscsi_mgmt_task *mtask;
	uint32_t itt;

	if (hdr->itt != RESERVED_ITT)
		itt = get_itt(hdr->itt);
	else
		itt = ~0U;

	if (itt < session->cmds_max) {
		ctask = session->cmds[itt];

		debug_scsi("cmdrsp [op 0x%x cid %d itt 0x%x len %d]\n",
			   opcode, conn->id, ctask->itt, datalen);

		switch(opcode) {
		case ISCSI_OP_SCSI_CMD_RSP:
			BUG_ON((void*)ctask != ctask->sc->SCp.ptr);
			iscsi_scsi_cmd_rsp(conn, hdr, ctask, data,
					   datalen);
			break;
		case ISCSI_OP_SCSI_DATA_IN:
			BUG_ON((void*)ctask != ctask->sc->SCp.ptr);
			if (hdr->flags & ISCSI_FLAG_DATA_STATUS) {
				conn->scsirsp_pdus_cnt++;
				__iscsi_put_ctask(ctask);
			}
			break;
		case ISCSI_OP_R2T:
			/* LLD handles this for now */
			break;
		default:
			rc = ISCSI_ERR_BAD_OPCODE;
			break;
		}
	} else if (itt >= ISCSI_MGMT_ITT_OFFSET &&
		   itt < ISCSI_MGMT_ITT_OFFSET + session->mgmtpool_max) {
		mtask = session->mgmt_cmds[itt - ISCSI_MGMT_ITT_OFFSET];

		debug_scsi("immrsp [op 0x%x cid %d itt 0x%x len %d]\n",
			   opcode, conn->id, mtask->itt, datalen);

		iscsi_update_cmdsn(session, (struct iscsi_nopin*)hdr);
		switch(opcode) {
		case ISCSI_OP_LOGOUT_RSP:
			if (datalen) {
				rc = ISCSI_ERR_PROTO;
				break;
			}
			conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
			/* fall through */
		case ISCSI_OP_LOGIN_RSP:
		case ISCSI_OP_TEXT_RSP:
			/*
			 * login related PDU's exp_statsn is handled in
			 * userspace
			 */
			if (iscsi_recv_pdu(conn->cls_conn, hdr, data, datalen))
				rc = ISCSI_ERR_CONN_FAILED;
			list_del(&mtask->running);
			if (conn->login_mtask != mtask)
				__kfifo_put(session->mgmtpool.queue,
					    (void*)&mtask, sizeof(void*));
			break;
		case ISCSI_OP_SCSI_TMFUNC_RSP:
			if (datalen) {
				rc = ISCSI_ERR_PROTO;
				break;
			}

			iscsi_tmf_rsp(conn, hdr);
			break;
		case ISCSI_OP_NOOP_IN:
			if (hdr->ttt != cpu_to_be32(ISCSI_RESERVED_TAG) || datalen) {
				rc = ISCSI_ERR_PROTO;
				break;
			}
			conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;

			if (iscsi_recv_pdu(conn->cls_conn, hdr, data, datalen))
				rc = ISCSI_ERR_CONN_FAILED;
			list_del(&mtask->running);
			if (conn->login_mtask != mtask)
				__kfifo_put(session->mgmtpool.queue,
					    (void*)&mtask, sizeof(void*));
			break;
		default:
			rc = ISCSI_ERR_BAD_OPCODE;
			break;
		}
	} else if (itt == ~0U) {
		iscsi_update_cmdsn(session, (struct iscsi_nopin*)hdr);

		switch(opcode) {
		case ISCSI_OP_NOOP_IN:
			if (datalen) {
				rc = ISCSI_ERR_PROTO;
				break;
			}

			if (hdr->ttt == cpu_to_be32(ISCSI_RESERVED_TAG))
				break;

			if (iscsi_recv_pdu(conn->cls_conn, hdr, NULL, 0))
				rc = ISCSI_ERR_CONN_FAILED;
			break;
		case ISCSI_OP_REJECT:
			rc = iscsi_handle_reject(conn, hdr, data, datalen);
			break;
		case ISCSI_OP_ASYNC_EVENT:
			conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
			if (iscsi_recv_pdu(conn->cls_conn, hdr, data, datalen))
				rc = ISCSI_ERR_CONN_FAILED;
			break;
		default:
			rc = ISCSI_ERR_BAD_OPCODE;
			break;
		}
	} else
		rc = ISCSI_ERR_BAD_ITT;

	return rc;
}
EXPORT_SYMBOL_GPL(__iscsi_complete_pdu);

int iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
		       char *data, int datalen)
{
	int rc;

	spin_lock(&conn->session->lock);
	rc = __iscsi_complete_pdu(conn, hdr, data, datalen);
	spin_unlock(&conn->session->lock);
	return rc;
}
EXPORT_SYMBOL_GPL(iscsi_complete_pdu);

/* verify itt (itt encoding: age+cid+itt) */
int iscsi_verify_itt(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
		     uint32_t *ret_itt)
{
	struct iscsi_session *session = conn->session;
	struct iscsi_cmd_task *ctask;
	uint32_t itt;

	if (hdr->itt != RESERVED_ITT) {
		if (((__force u32)hdr->itt & ISCSI_AGE_MASK) !=
		    (session->age << ISCSI_AGE_SHIFT)) {
			printk(KERN_ERR "iscsi: received itt %x expected "
				"session age (%x)\n", (__force u32)hdr->itt,
				session->age & ISCSI_AGE_MASK);
			return ISCSI_ERR_BAD_ITT;
		}

		if (((__force u32)hdr->itt & ISCSI_CID_MASK) !=
		    (conn->id << ISCSI_CID_SHIFT)) {
			printk(KERN_ERR "iscsi: received itt %x, expected "
				"CID (%x)\n", (__force u32)hdr->itt, conn->id);
			return ISCSI_ERR_BAD_ITT;
		}
		itt = get_itt(hdr->itt);
	} else
		itt = ~0U;