RFC: Proposal for BSG Interface

index ea3892e..2b7218c 100644
@@ -29,6 +29,8 @@
 #include <scsi/scsi_transport.h>
 #include <scsi/scsi_transport_iscsi.h>
 #include <scsi/iscsi_if.h>
+#include <scsi/scsi_bsg_iscsi.h>
+#include <scsi/scsi_cmnd.h>
 
 #define ISCSI_SESSION_ATTRS 22
 #define ISCSI_CONN_ATTRS 13

@@ -268,6 +270,447 @@ struct iscsi_endpoint *iscsi_lookup_endpoint(u64 handle)
 }
 EXPORT_SYMBOL_GPL(iscsi_lookup_endpoint);
 
+
+/*
+ * BSG support
+ */
+
+/**
+ * iscsi_destroy_bsgjob - routine to teardown/delete a iscsi bsg job
+ * @job:	iscsi_bsg_job that is to be torn down
+ */
+static void
+iscsi_destroy_bsgjob(struct iscsi_bsg_job *job)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&job->job_lock, flags);
+	if (job->ref_cnt) {
+		spin_unlock_irqrestore(&job->job_lock, flags);
+		return;
+	}
+	spin_unlock_irqrestore(&job->job_lock, flags);
+
+	put_device(job->dev);	/* release reference for the request */
+
+	kfree(job->request_payload.sg_list);
+	kfree(job->reply_payload.sg_list);
+	kfree(job);
+}
+
+/**
+ * iscsi_bsg_jobdone - completion routine for bsg requests that the LLD has
+ *                  completed
+ * @job:	iscsi_bsg_job that is complete
+ */
+static void
+iscsi_bsg_jobdone(struct iscsi_bsg_job *job)
+{
+	struct request *req = job->req;
+	struct request *rsp = req->next_rq;
+	int err;
+
+	err = job->req->errors = job->reply->result;
+
+	if (err < 0)
+		/* we're only returning the result field in the reply */
+		job->req->sense_len = sizeof(uint32_t);
+	else
+		job->req->sense_len = job->reply_len;
+
+	/* we assume all request payload was transferred, residual == 0 */
+	req->resid_len = 0;
+
+	if (rsp) {
+		WARN_ON(job->reply->reply_payload_rcv_len > rsp->resid_len);
+
+		/* set reply (bidi) residual */
+		rsp->resid_len -= min(job->reply->reply_payload_rcv_len,
+				      rsp->resid_len);
+	}
+	blk_complete_request(req);
+}
+
+/**
+ * iscsi_bsg_softirq_done - softirq done routine for destroying the bsg requests
+ * @rq:        BSG request that holds the job to be destroyed
+ */
+static void
+iscsi_bsg_softirq_done(struct request *rq)
+{
+	struct iscsi_bsg_job *job = rq->special;
+	unsigned long flags;
+
+	spin_lock_irqsave(&job->job_lock, flags);
+	job->state_flags |= ISCSI_RQST_STATE_DONE;
+	job->ref_cnt--;
+	spin_unlock_irqrestore(&job->job_lock, flags);
+
+	blk_end_request_all(rq, rq->errors);
+	iscsi_destroy_bsgjob(job);
+}
+
+/**
+ * iscsi_bsg_job_timeout - handler for when a bsg request timesout
+ * @req:	request that timed out
+ */
+static enum blk_eh_timer_return
+iscsi_bsg_job_timeout(struct request *req)
+{
+	struct iscsi_bsg_job *job = (void *) req->special;
+	struct Scsi_Host *shost = job->shost;
+	struct iscsi_internal *i = to_iscsi_internal(shost->transportt);
+	unsigned long flags;
+	int err = 0, done = 0;
+
+	spin_lock_irqsave(&job->job_lock, flags);
+	if (job->state_flags & ISCSI_RQST_STATE_DONE)
+		done = 1;
+	else
+		job->ref_cnt++;
+	spin_unlock_irqrestore(&job->job_lock, flags);
+
+	if (!done && i->iscsi_transport->bsg_timeout) {
+		/* call LLDD to abort the i/o as it has timed out */
+		err = i->iscsi_transport->bsg_timeout(job);
+		if (err == -EAGAIN) {
+			job->ref_cnt--;
+			return BLK_EH_RESET_TIMER;
+		} else if (err)
+			printk(KERN_ERR "ERROR: iSCSI BSG request timeout - "
+				"LLD abort failed with status %d\n", err);
+	}
+
+	/* the blk_end_sync_io() doesn't check the error */
+	if (done)
+		return BLK_EH_NOT_HANDLED;
+	else
+		return BLK_EH_HANDLED;
+}
+
+static int
+iscsi_bsg_map_buffer(struct iscsi_bsg_buffer *buf, struct request *req)
+{
+	size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
+
+	BUG_ON(!req->nr_phys_segments);
+
+	buf->sg_list = kzalloc(sz, GFP_KERNEL);
+	if (!buf->sg_list)
+		return -ENOMEM;
+	sg_init_table(buf->sg_list, req->nr_phys_segments);
+	buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
+	buf->payload_len = blk_rq_bytes(req);
+	return 0;
+}
+
+/**
+ * iscsi_req_to_bsgjob - Allocate/create the iscsi_bsg_job structure for the
+ *                   bsg request
+ * @req:	BSG request that needs a job structure
+ * @shost:	SCSI Host corresponding to the bsg object
+ */
+static int
+iscsi_req_to_bsgjob(struct request *req, struct Scsi_Host *shost)
+{
+	struct iscsi_internal *i = to_iscsi_internal(shost->transportt);
+	struct request *rsp = req->next_rq;
+	struct iscsi_bsg_job *job;
+	int ret;
+
+	BUG_ON(req->special);
+
+	job = kzalloc(sizeof(struct iscsi_bsg_job) +
+				 i->iscsi_transport->dd_bsg_size, GFP_KERNEL);
+	if (!job)
+		return -ENOMEM;
+
+	/*
+	 * Note: this is a bit silly.
+	 * The request gets formatted as a SGIO v4 ioctl request, which
+	 * then gets reformatted as a blk request, which then gets
+	 * reformatted as a iscsi bsg request. And on completion, we have
+	 * to wrap return results such that SGIO v4 thinks it was a scsi
+	 * status.  I hope this was all worth it.
+	 */
+
+	req->special = job;
+	job->shost = shost;
+	job->req = req;
+	if (i->iscsi_transport->dd_bsg_size)
+		job->dd_data = (void *)&job[1];
+	spin_lock_init(&job->job_lock);
+	job->request = (struct iscsi_bsg_request *)req->cmd;
+	job->request_len = req->cmd_len;
+	job->reply = req->sense;
+	job->reply_len = SCSI_SENSE_BUFFERSIZE;	/* Size of sense buffer
+						 * allocated */
+	if (req->bio) {
+		ret = iscsi_bsg_map_buffer(&job->request_payload, req);
+		if (ret)
+			goto failjob_rls_job;
+	}
+	if (rsp && rsp->bio) {
+		ret = iscsi_bsg_map_buffer(&job->reply_payload, rsp);
+		if (ret)
+			goto failjob_rls_rqst_payload;
+	}
+	job->job_done = iscsi_bsg_jobdone;
+	job->dev = &shost->shost_gendev;
+	get_device(job->dev);		/* take a reference for the request */
+
+	job->ref_cnt = 1;
+
+	return 0;
+
+
+failjob_rls_rqst_payload:
+	kfree(job->request_payload.sg_list);
+failjob_rls_job:
+	kfree(job);
+	return -ENOMEM;
+}
+
+
+enum iscsi_dispatch_result {
+	DISPATCH_BREAK,		/* on return, q is locked, break from q loop */
+	DISPATCH_LOCKED,	/* on return, q is locked, continue on */
+	DISPATCH_UNLOCKED,	/* on return, q is unlocked, continue on */
+};
+
+/**
+ * iscsi_bsg_host_dispatch - process iscsi host bsg requests and
+ *                           dispatch to LLDD
+ * @q:		iscsi host request queue
+ * @shost:	scsi host request queue attached to
+ * @job:	bsg job to be processed
+ */
+static enum iscsi_dispatch_result
+iscsi_bsg_host_dispatch(struct request_queue *q, struct Scsi_Host *shost,
+			 struct iscsi_bsg_job *job)
+{
+	unsigned char *pdata;
+	struct iscsi_internal *i = to_iscsi_internal(shost->transportt);
+	int cmdlen = sizeof(uint32_t);	/* start with length of msgcode */
+	int ret, num;
+	unsigned int tot_len = 0;
+	struct scatterlist *sge = NULL;
+
+	/* Validate the host command */
+	job->request_payload.va = NULL;
+	switch (job->request->msgcode) {
+	case ISCSI_BSG_HST_NET_CONFIG:
+		cmdlen += sizeof(struct iscsi_bsg_host_net_config);
+		/*
+		 * Validate set ops have a request payload.
+		 * Get ops are allowed to have none/partial/all reply payloads
+		 */
+		if ((job->request->rqst_data.h_netconfig.set_op) &&
+		    (!job->request_payload.payload_len)) {
+			ret = -EINVAL;
+			goto fail_host_msg;
+		}
+		tot_len = 0;
+		for_each_sg(job->request_payload.sg_list, sge,
+			    job->request_payload.sg_cnt, num) {
+			tot_len += sge->length;
+		}
+
+		job->request_payload.va =  kmalloc(tot_len, GFP_KERNEL);
+		if (job->request_payload.va == NULL) {
+			ret = -EINVAL;
+			goto fail_host_msg;
+		}
+		pdata = job->request_payload.va;
+		job->request_payload.size = tot_len;
+		for_each_sg(job->request_payload.sg_list, sge,
+				 job->request_payload.sg_cnt, num) {
+			memcpy(pdata, sg_virt(sge), sge->length);
+			pdata += sge->length;
+
+		}
+		break;
+
+	case ISCSI_BSG_HST_VENDOR:
+		cmdlen += sizeof(struct iscsi_bsg_host_vendor);
+		if ((shost->hostt->vendor_id == 0L) ||
+		    (job->request->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) {
+		kfree(job->request_payload.va);
+		return DISPATCH_UNLOCKED;
+	}
+
+fail_host_msg:
+	kfree(job->request_payload.va);
+
+	/* return the errno failure code as the only status */
+	BUG_ON(job->reply_len < sizeof(uint32_t));
+	job->reply->reply_payload_rcv_len = 0;
+	job->reply->result = ret;
+	job->reply_len = sizeof(uint32_t);
+	iscsi_bsg_jobdone(job);
+	return DISPATCH_UNLOCKED;
+}
+
+/**
+ * iscsi_bsg_request_handler - generic handler for bsg requests
+ * @q:		request queue to manage
+ * @shost:	Scsi_Host related to the bsg object
+ * @dev:	device structure for bsg object
+ *
+ * NOTE: only shost messages are expected
+ */
+static void
+iscsi_bsg_request_handler(struct request_queue *q, struct Scsi_Host *shost,
+			struct device *dev)
+{
+	struct request *req;
+	struct iscsi_bsg_job *job;
+	enum iscsi_dispatch_result ret;
+
+	if (!get_device(dev))
+		return;
+
+	while (!blk_queue_plugged(q)) {
+
+		req = blk_fetch_request(q);
+		if (!req)
+			break;
+
+		spin_unlock_irq(q->queue_lock);
+
+		ret = iscsi_req_to_bsgjob(req, shost);
+		if (ret) {
+			req->errors = ret;
+			blk_end_request(req, ret, blk_rq_bytes(req));
+			spin_lock_irq(q->queue_lock);
+			continue;
+		}
+
+		job = req->special;
+
+		/* check if we have the msgcode value at least */
+		if (job->request_len < sizeof(uint32_t)) {
+			BUG_ON(job->reply_len < sizeof(uint32_t));
+			job->reply->reply_payload_rcv_len = 0;
+			job->reply->result = -ENOMSG;
+			job->reply_len = sizeof(uint32_t);
+			iscsi_bsg_jobdone(job);
+			spin_lock_irq(q->queue_lock);
+			continue;
+		}
+
+		/* the dispatch routines will unlock the queue_lock */
+		ret = iscsi_bsg_host_dispatch(q, shost, job);
+
+		/* did dispatcher hit state that can't process any more */
+		if (ret == DISPATCH_BREAK)
+			break;
+
+		/* did dispatcher had released the lock */
+		if (ret == DISPATCH_UNLOCKED)
+			spin_lock_irq(q->queue_lock);
+	}
+
+	spin_unlock_irq(q->queue_lock);
+	put_device(dev);
+	spin_lock_irq(q->queue_lock);
+}
+
+/**
+ * iscsi_bsg_host_handler - handler for bsg requests for a iscsi host
+ * @q:		iscsi host request queue
+ */
+static void
+iscsi_bsg_host_handler(struct request_queue *q)
+{
+	struct Scsi_Host *shost = q->queuedata;
+
+	iscsi_bsg_request_handler(q, shost, &shost->shost_gendev);
+}
+
+/**
+ * iscsi_bsg_hostadd - Create and add the bsg hooks so we can receive requests
+ * @shost:	shost for iscsi_host
+ * @cls_host:	iscsi_cls_host adding the structures to
+ */
+static int
+iscsi_bsg_hostadd(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;
+	int err;
+	char bsg_name[20];
+
+	ihost->rqst_q = NULL;
+
+	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, iscsi_bsg_host_handler);
+	if (!q) {
+		printk(KERN_ERR "iscsi_host%d: bsg interface failed to "
+				"initialize - no request queue\n",
+				 shost->host_no);
+		return -ENOMEM;
+	}
+
+	q->queuedata = shost;
+	queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
+	blk_queue_softirq_done(q, iscsi_bsg_softirq_done);
+	blk_queue_rq_timed_out(q, iscsi_bsg_job_timeout);
+	blk_queue_rq_timeout(q, ISCSI_DEFAULT_BSG_TIMEOUT);
+
+	err = bsg_register_queue(q, dev, bsg_name, NULL);
+	if (err) {
+		printk(KERN_ERR "iscsi_host%d: bsg interface failed to "
+				"initialize - register queue\n",
+				shost->host_no);
+		blk_cleanup_queue(q);
+		return err;
+	}
+
+	ihost->rqst_q = q;
+	return 0;
+}
+
+/**
+ * iscsi_bsg_remove - Deletes the bsg hooks on iscsi objects
+ * @q:	the request_queue that is to be torn down.
+ */
+static void
+iscsi_bsg_remove(struct request_queue *q)
+{
+	if (q) {
+		bsg_unregister_queue(q);
+		blk_cleanup_queue(q);
+	}
+}
+
+/* End BSG routines */
+
 static int iscsi_setup_host(struct transport_container *tc, struct device *dev,
 			    struct device *cdev)
 {

@@ -277,13 +720,27 @@ static int iscsi_setup_host(struct transport_container *tc, struct device *dev,
 	memset(ihost, 0, sizeof(*ihost));
 	atomic_set(&ihost->nr_scans, 0);
 	mutex_init(&ihost->mutex);
+
+	iscsi_bsg_hostadd(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;
+
+	iscsi_bsg_remove(ihost->rqst_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,

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