[SCSI] iscsi class: add bsg support to iscsi class

This patch adds bsg support to the iscsi class. There is only
1 request, the host vendor one, supported. It is expected that
this would be used for things like flash updates.

This patch is made over this one
http://marc.info/?l=linux-scsi&m=131149780020992&w=2

Signed-off-by: Mike Christie <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/Kconfig

···
 config SCSI_ISCSI_ATTRS
 	tristate "iSCSI Transport Attributes"
 	depends on SCSI && NET
+	select BLK_DEV_BSGLIB
 	help
 	  If you wish to export transport-specific information about
 	  each attached iSCSI device to sysfs, say Y.

drivers/scsi/scsi_transport_iscsi.c

···
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
+#include <linux/bsg-lib.h>
 #include <net/tcp.h>
 #include <scsi/scsi.h>
 #include <scsi/scsi_host.h>
···
 #include <scsi/scsi_transport_iscsi.h>
 #include <scsi/iscsi_if.h>
 #include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_bsg_iscsi.h>
 
 #define ISCSI_TRANSPORT_VERSION "2.0-870"
 
···
 }
 EXPORT_SYMBOL_GPL(iscsi_destroy_iface);
 
+/*
+ * BSG support
+ */
+/**
+ * iscsi_bsg_host_dispatch - Dispatch command to LLD.
+ * @job: bsg job to be processed
+ */
+static int iscsi_bsg_host_dispatch(struct bsg_job *job)
+{
+	struct Scsi_Host *shost = iscsi_job_to_shost(job);
+	struct iscsi_bsg_request *req = job->request;
+	struct iscsi_bsg_reply *reply = job->reply;
+	struct iscsi_internal *i = to_iscsi_internal(shost->transportt);
+	int cmdlen = sizeof(uint32_t);	/* start with length of msgcode */
+	int ret;
+
+	/* check if we have the msgcode value at least */
+	if (job->request_len < sizeof(uint32_t)) {
+		ret = -ENOMSG;
+		goto fail_host_msg;
+	}
+
+	/* Validate the host command */
+	switch (req->msgcode) {
+	case ISCSI_BSG_HST_VENDOR:
+		cmdlen += sizeof(struct iscsi_bsg_host_vendor);
+		if ((shost->hostt->vendor_id == 0L) ||
+		    (req->rqst_data.h_vendor.vendor_id !=
+			shost->hostt->vendor_id)) {
+			ret = -ESRCH;
+			goto fail_host_msg;
+		}
+		break;
+	default:
+		ret = -EBADR;
+		goto fail_host_msg;
+	}
+
+	/* check if we really have all the request data needed */
+	if (job->request_len < cmdlen) {
+		ret = -ENOMSG;
+		goto fail_host_msg;
+	}
+
+	ret = i->iscsi_transport->bsg_request(job);
+	if (!ret)
+		return 0;
+
+fail_host_msg:
+	/* return the errno failure code as the only status */
+	BUG_ON(job->reply_len < sizeof(uint32_t));
+	reply->reply_payload_rcv_len = 0;
+	reply->result = ret;
+	job->reply_len = sizeof(uint32_t);
+	bsg_job_done(job, ret, 0);
+	return 0;
+}
+
+/**
+ * iscsi_bsg_host_add - Create and add the bsg hooks to receive requests
+ * @shost: shost for iscsi_host
+ * @cls_host: iscsi_cls_host adding the structures to
+ */
+static int
+iscsi_bsg_host_add(struct Scsi_Host *shost, struct iscsi_cls_host *ihost)
+{
+	struct device *dev = &shost->shost_gendev;
+	struct iscsi_internal *i = to_iscsi_internal(shost->transportt);
+	struct request_queue *q;
+	char bsg_name[20];
+	int ret;
+
+	if (!i->iscsi_transport->bsg_request)
+		return -ENOTSUPP;
+
+	snprintf(bsg_name, sizeof(bsg_name), "iscsi_host%d", shost->host_no);
+
+	q = __scsi_alloc_queue(shost, bsg_request_fn);
+	if (!q)
+		return -ENOMEM;
+
+	ret = bsg_setup_queue(dev, q, bsg_name, iscsi_bsg_host_dispatch, 0);
+	if (ret) {
+		shost_printk(KERN_ERR, shost, "bsg interface failed to "
+			     "initialize - no request queue\n");
+		blk_cleanup_queue(q);
+		return ret;
+	}
+
+	ihost->bsg_q = q;
+	return 0;
+}
+
 static int iscsi_setup_host(struct transport_container *tc, struct device *dev,
 			    struct device *cdev)
 {
···
 	memset(ihost, 0, sizeof(*ihost));
 	atomic_set(&ihost->nr_scans, 0);
 	mutex_init(&ihost->mutex);
+
+	iscsi_bsg_host_add(shost, ihost);
+	/* ignore any bsg add error - we just can't do sgio */
+
+	return 0;
+}
+
+static int iscsi_remove_host(struct transport_container *tc,
+			     struct device *dev, struct device *cdev)
+{
+	struct Scsi_Host *shost = dev_to_shost(dev);
+	struct iscsi_cls_host *ihost = shost->shost_data;
+
+	if (ihost->bsg_q) {
+		bsg_remove_queue(ihost->bsg_q);
+		blk_cleanup_queue(ihost->bsg_q);
+	}
 	return 0;
 }
 
 static DECLARE_TRANSPORT_CLASS(iscsi_host_class,
 			       "iscsi_host",
 			       iscsi_setup_host,
-			       NULL,
+			       iscsi_remove_host,
 			       NULL);
 
 static DECLARE_TRANSPORT_CLASS(iscsi_session_class,

include/scsi/scsi_bsg_iscsi.h

···
+/*
+ *  iSCSI Transport BSG Interface
+ *
+ *  Copyright (C) 2009   James Smart, Emulex Corporation
+ *
+ *  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
+ *
+ */
+
+#ifndef SCSI_BSG_ISCSI_H
+#define SCSI_BSG_ISCSI_H
+
+/*
+ * This file intended to be included by both kernel and user space
+ */
+
+#include <scsi/scsi.h>
+
+/*
+ * iSCSI Transport SGIO v4 BSG Message Support
+ */
+
+/* Default BSG request timeout (in seconds) */
+#define ISCSI_DEFAULT_BSG_TIMEOUT      (10 * HZ)
+
+
+/*
+ * Request Message Codes supported by the iSCSI Transport
+ */
+
+/* define the class masks for the message codes */
+#define ISCSI_BSG_CLS_MASK     0xF0000000      /* find object class */
+#define ISCSI_BSG_HST_MASK     0x80000000      /* iscsi host class */
+
+/* iscsi host Message Codes */
+#define ISCSI_BSG_HST_VENDOR           (ISCSI_BSG_HST_MASK | 0x000000FF)
+
+
+/*
+ * iSCSI Host Messages
+ */
+
+/* ISCSI_BSG_HST_VENDOR : */
+
+/* Request:
+ * Note: When specifying vendor_id, be sure to read the Vendor Type and ID
+ *   formatting requirements specified in scsi_netlink.h
+ */
+struct iscsi_bsg_host_vendor {
+	/*
+	 * Identifies the vendor that the message is formatted for. This
+	 * should be the recipient of the message.
+	 */
+	uint64_t vendor_id;
+
+	/* start of vendor command area */
+	uint32_t vendor_cmd[0];
+};
+
+/* Response:
+ */
+struct iscsi_bsg_host_vendor_reply {
+	/* start of vendor response area */
+	uint32_t vendor_rsp[0];
+};
+
+
+/* request (CDB) structure of the sg_io_v4 */
+struct iscsi_bsg_request {
+	uint32_t msgcode;
+	union {
+		struct iscsi_bsg_host_vendor    h_vendor;
+	} rqst_data;
+} __attribute__((packed));
+
+
+/* response (request sense data) structure of the sg_io_v4 */
+struct iscsi_bsg_reply {
+	/*
+	 * The completion result. Result exists in two forms:
+	 * if negative, it is an -Exxx system errno value. There will
+	 * be no further reply information supplied.
+	 * else, it's the 4-byte scsi error result, with driver, host,
+	 * msg and status fields. The per-msgcode reply structure
+	 * will contain valid data.
+	 */
+	uint32_t result;
+
+	/* If there was reply_payload, how much was recevied ? */
+	uint32_t reply_payload_rcv_len;
+
+	union {
+		struct iscsi_bsg_host_vendor_reply      vendor_reply;
+	} reply_data;
+};
+
+
+#endif /* SCSI_BSG_ISCSI_H */

include/scsi/scsi_transport_iscsi.h

···
 struct iscsi_task;
 struct sockaddr;
 struct iscsi_iface;
+struct bsg_job;
 
 /**
  * struct iscsi_transport - iSCSI Transport template
···
 				enum iscsi_param_type param_type,
 				int param, char *buf);
 	mode_t (*attr_is_visible)(int param_type, int param);
+	int (*bsg_request)(struct bsg_job *job);
 };
-
 
 /*
  * transport registration upcalls
···
 struct iscsi_cls_host {
 	atomic_t nr_scans;
 	struct mutex mutex;
+	struct request_queue *bsg_q;
 };
+
+#define iscsi_job_to_shost(_job) \
+        dev_to_shost(_job->dev)
 
 extern void iscsi_host_for_each_session(struct Scsi_Host *shost,
 				void (*fn)(struct iscsi_cls_session *));