[SCSI] FC Pass Thru support

Attached is the ELS/CT pass-thru patch for the FC Transport. The patch
creates a generic framework that lays on top of bsg and the SGIO v4 ioctl
in order to pass transaction requests to LLDD's.

The interface supports the following operations:
  On an fc_host basis:
    Request login to the specified N_Port_ID, creating an fc_rport.
    Request logout of the specified N_Port_ID, deleting an fc_rport
    Send ELS request to specified N_Port_ID w/o requiring a login, and
      wait for ELS response.
    Send CT request to specified N_Port_ID and wait for CT response.
      Login is required, but LLDD is allowed to manage login and decide
      whether it stays in place after the request is satisfied.
    Vendor-Unique request. Allows a LLDD-specific request to be passed
      to the LLDD, and the passing of a response back to the application.
  On an fc_rport basis:
    Send ELS request to nport and wait for ELS response.
    Send CT request to nport and wait for CT response.

The patch also exports several headers from include/scsi such that
they can be available to user-space applications:
  include/scsi/scsi.h
  include/scsi/scsi_netlink.h
  include/scsi/scsi_netlink_fc.h
  include/scsi/scsi_bsg_fc.h

For further information, refer to the last RFC:
http://marc.info/?l=linux-scsi&m=123436574018579&w=2

Note: Documentation is still spotty and will be added later.

[[email protected]: update for new block API]
Signed-off-by: James Smart <[email protected]>
Signed-off-by: James Bottomley <[email protected]>

drivers/scsi/scsi_transport_fc.c

@@ -35,6 +35,7 @@
 #include <linux/netlink.h>
 #include <net/netlink.h>
 #include <scsi/scsi_netlink_fc.h>
+#include <scsi/scsi_bsg_fc.h>
 #include "scsi_priv.h"
 #include "scsi_transport_fc_internal.h"
 
@@ -43,6 +44,10 @@ static void fc_vport_sched_delete(struct work_struct *work);
 static int fc_vport_setup(struct Scsi_Host *shost, int channel,
 	struct device *pdev, struct fc_vport_identifiers  *ids,
 	struct fc_vport **vport);
+static int fc_bsg_hostadd(struct Scsi_Host *, struct fc_host_attrs *);
+static int fc_bsg_rportadd(struct Scsi_Host *, struct fc_rport *);
+static void fc_bsg_remove(struct request_queue *);
+static void fc_bsg_goose_queue(struct fc_rport *);
 
 /*
  * Redefine so that we can have same named attributes in the
@@ -411,13 +416,26 @@ static int fc_host_setup(struct transport_container *tc, struct device *dev,
 		return -ENOMEM;
 	}
 
+	fc_bsg_hostadd(shost, fc_host);
+	/* ignore any bsg add error - we just can't do sgio */
+
+	return 0;
+}
+
+static int fc_host_remove(struct transport_container *tc, struct device *dev,
+			 struct device *cdev)
+{
+	struct Scsi_Host *shost = dev_to_shost(dev);
+	struct fc_host_attrs *fc_host = shost_to_fc_host(shost);
+
+	fc_bsg_remove(fc_host->rqst_q);
 	return 0;
 }
 
 static DECLARE_TRANSPORT_CLASS(fc_host_class,
 			       "fc_host",
 			       fc_host_setup,
-			       NULL,
+			       fc_host_remove,
 			       NULL);
 
 /*
@@ -2375,6 +2393,7 @@ fc_rport_final_delete(struct work_struct *work)
 		scsi_flush_work(shost);
 
 	fc_terminate_rport_io(rport);
+
 	/*
 	 * Cancel any outstanding timers. These should really exist
 	 * only when rmmod'ing the LLDD and we're asking for
@@ -2407,6 +2426,8 @@ fc_rport_final_delete(struct work_struct *work)
 	    (i->f->dev_loss_tmo_callbk))
 		i->f->dev_loss_tmo_callbk(rport);
 
+	fc_bsg_remove(rport->rqst_q);
+
 	transport_remove_device(dev);
 	device_del(dev);
 	transport_destroy_device(dev);
@@ -2494,6 +2515,9 @@ fc_rport_create(struct Scsi_Host *shost, int channel,
 	transport_add_device(dev);
 	transport_configure_device(dev);
 
+	fc_bsg_rportadd(shost, rport);
+	/* ignore any bsg add error - we just can't do sgio */
+
 	if (rport->roles & FC_PORT_ROLE_FCP_TARGET) {
 		/* initiate a scan of the target */
 		rport->flags |= FC_RPORT_SCAN_PENDING;
@@ -2658,6 +2682,8 @@ fc_remote_port_add(struct Scsi_Host *shost, int channel,
 					spin_unlock_irqrestore(shost->host_lock,
 							flags);
 
+				fc_bsg_goose_queue(rport);
+
 				return rport;
 			}
 		}
@@ -3343,6 +3369,592 @@ fc_vport_sched_delete(struct work_struct *work)
 }
 
 
+/*
+ * BSG support
+ */
+
+
+/**
+ * fc_destroy_bsgjob - routine to teardown/delete a fc bsg job
+ * @job:	fc_bsg_job that is to be torn down
+ */
+static void
+fc_destroy_bsgjob(struct fc_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);
+}
+
+
+/**
+ * fc_bsg_jobdone - completion routine for bsg requests that the LLD has
+ *                  completed
+ * @job:	fc_bsg_job that is complete
+ */
+static void
+fc_bsg_jobdone(struct fc_bsg_job *job)
+{
+	struct request *req = job->req;
+	struct request *rsp = req->next_rq;
+	unsigned long flags;
+	int err;
+
+	spin_lock_irqsave(&job->job_lock, flags);
+	job->state_flags |= FC_RQST_STATE_DONE;
+	job->ref_cnt--;
+	spin_unlock_irqrestore(&job->job_lock, flags);
+
+	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_end_request_all(req, err);
+
+	fc_destroy_bsgjob(job);
+}
+
+
+/**
+ * fc_bsg_job_timeout - handler for when a bsg request timesout
+ * @req:	request that timed out
+ */
+static enum blk_eh_timer_return
+fc_bsg_job_timeout(struct request *req)
+{
+	struct fc_bsg_job *job = (void *) req->special;
+	struct Scsi_Host *shost = job->shost;
+	struct fc_internal *i = to_fc_internal(shost->transportt);
+	unsigned long flags;
+	int err = 0, done = 0;
+
+	if (job->rport && job->rport->port_state == FC_PORTSTATE_BLOCKED)
+		return BLK_EH_RESET_TIMER;
+
+	spin_lock_irqsave(&job->job_lock, flags);
+	if (job->state_flags & FC_RQST_STATE_DONE)
+		done = 1;
+	else
+		job->ref_cnt++;
+	spin_unlock_irqrestore(&job->job_lock, flags);
+
+	if (!done && i->f->bsg_timeout) {
+		/* call LLDD to abort the i/o as it has timed out */
+		err = i->f->bsg_timeout(job);
+		if (err)
+			printk(KERN_ERR "ERROR: FC BSG request timeout - LLD "
+				"abort failed with status %d\n", err);
+	}
+
+	if (!done) {
+		spin_lock_irqsave(&job->job_lock, flags);
+		job->ref_cnt--;
+		spin_unlock_irqrestore(&job->job_lock, flags);
+		fc_destroy_bsgjob(job);
+	}
+
+	/* the blk_end_sync_io() doesn't check the error */
+	return BLK_EH_HANDLED;
+}
+
+
+
+static int
+fc_bsg_map_buffer(struct fc_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;
+}
+
+
+/**
+ * fc_req_to_bsgjob - Allocate/create the fc_bsg_job structure for the
+ *                   bsg request
+ * @shost:	SCSI Host corresponding to the bsg object
+ * @rport:	(optional) FC Remote Port corresponding to the bsg object
+ * @req:	BSG request that needs a job structure
+ */
+static int
+fc_req_to_bsgjob(struct Scsi_Host *shost, struct fc_rport *rport,
+	struct request *req)
+{
+	struct fc_internal *i = to_fc_internal(shost->transportt);
+	struct request *rsp = req->next_rq;
+	struct fc_bsg_job *job;
+	int ret;
+
+	BUG_ON(req->special);
+
+	job = kzalloc(sizeof(struct fc_bsg_job) + i->f->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 fc 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->rport = rport;
+	job->req = req;
+	if (i->f->dd_bsg_size)
+		job->dd_data = (void *)&job[1];
+	spin_lock_init(&job->job_lock);
+	job->request = (struct fc_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 = fc_bsg_map_buffer(&job->request_payload, req);
+		if (ret)
+			goto failjob_rls_job;
+	}
+	if (rsp && rsp->bio) {
+		ret = fc_bsg_map_buffer(&job->reply_payload, rsp);
+		if (ret)
+			goto failjob_rls_rqst_payload;
+	}
+	job->job_done = fc_bsg_jobdone;
+	if (rport)
+		job->dev = &rport->dev;
+	else
+		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 fc_dispatch_result {
+	FC_DISPATCH_BREAK,	/* on return, q is locked, break from q loop */
+	FC_DISPATCH_LOCKED,	/* on return, q is locked, continue on */
+	FC_DISPATCH_UNLOCKED,	/* on return, q is unlocked, continue on */
+};
+
+
+/**
+ * fc_bsg_host_dispatch - process fc host bsg requests and dispatch to LLDD
+ * @shost:	scsi host rport attached to
+ * @job:	bsg job to be processed
+ */
+static enum fc_dispatch_result
+fc_bsg_host_dispatch(struct request_queue *q, struct Scsi_Host *shost,
+			 struct fc_bsg_job *job)
+{
+	struct fc_internal *i = to_fc_internal(shost->transportt);
+	int cmdlen = sizeof(uint32_t);	/* start with length of msgcode */
+	int ret;
+
+	/* Validate the host command */
+	switch (job->request->msgcode) {
+	case FC_BSG_HST_ADD_RPORT:
+		cmdlen += sizeof(struct fc_bsg_host_add_rport);
+		break;
+
+	case FC_BSG_HST_DEL_RPORT:
+		cmdlen += sizeof(struct fc_bsg_host_del_rport);
+		break;
+
+	case FC_BSG_HST_ELS_NOLOGIN:
+		cmdlen += sizeof(struct fc_bsg_host_els);
+		/* there better be a xmt and rcv payloads */
+		if ((!job->request_payload.payload_len) ||
+		    (!job->reply_payload.payload_len)) {
+			ret = -EINVAL;
+			goto fail_host_msg;
+		}
+		break;
+
+	case FC_BSG_HST_CT:
+		cmdlen += sizeof(struct fc_bsg_host_ct);
+		/* there better be xmt and rcv payloads */
+		if ((!job->request_payload.payload_len) ||
+		    (!job->reply_payload.payload_len)) {
+			ret = -EINVAL;
+			goto fail_host_msg;
+		}
+		break;
+
+	case FC_BSG_HST_VENDOR:
+		cmdlen += sizeof(struct fc_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->f->bsg_request(job);
+	if (!ret)
+		return FC_DISPATCH_UNLOCKED;
+
+fail_host_msg:
+	/* return the errno failure code as the only status */
+	BUG_ON(job->reply_len < sizeof(uint32_t));
+	job->reply->result = ret;
+	job->reply_len = sizeof(uint32_t);
+	fc_bsg_jobdone(job);
+	return FC_DISPATCH_UNLOCKED;
+}
+
+
+/*
+ * fc_bsg_goose_queue - restart rport queue in case it was stopped
+ * @rport:	rport to be restarted
+ */
+static void
+fc_bsg_goose_queue(struct fc_rport *rport)
+{
+	int flagset;
+
+	if (!rport->rqst_q)
+		return;
+
+	get_device(&rport->dev);
+
+	spin_lock(rport->rqst_q->queue_lock);
+	flagset = test_bit(QUEUE_FLAG_REENTER, &rport->rqst_q->queue_flags) &&
+		  !test_bit(QUEUE_FLAG_REENTER, &rport->rqst_q->queue_flags);
+	if (flagset)
+		queue_flag_set(QUEUE_FLAG_REENTER, rport->rqst_q);
+	__blk_run_queue(rport->rqst_q);
+	if (flagset)
+		queue_flag_clear(QUEUE_FLAG_REENTER, rport->rqst_q);
+	spin_unlock(rport->rqst_q->queue_lock);
+
+	put_device(&rport->dev);
+}
+
+
+/**
+ * fc_bsg_rport_dispatch - process rport bsg requests and dispatch to LLDD
+ * @shost:	scsi host rport attached to
+ * @rport:	rport request destined to
+ * @job:	bsg job to be processed
+ */
+static enum fc_dispatch_result
+fc_bsg_rport_dispatch(struct request_queue *q, struct Scsi_Host *shost,
+			 struct fc_rport *rport, struct fc_bsg_job *job)
+{
+	struct fc_internal *i = to_fc_internal(shost->transportt);
+	int cmdlen = sizeof(uint32_t);	/* start with length of msgcode */
+	int ret;
+
+	/* Validate the rport command */
+	switch (job->request->msgcode) {
+	case FC_BSG_RPT_ELS:
+		cmdlen += sizeof(struct fc_bsg_rport_els);
+		goto check_bidi;
+
+	case FC_BSG_RPT_CT:
+		cmdlen += sizeof(struct fc_bsg_rport_ct);
+check_bidi:
+		/* there better be xmt and rcv payloads */
+		if ((!job->request_payload.payload_len) ||
+		    (!job->reply_payload.payload_len)) {
+			ret = -EINVAL;
+			goto fail_rport_msg;
+		}
+		break;
+	default:
+		ret = -EBADR;
+		goto fail_rport_msg;
+	}
+
+	/* check if we really have all the request data needed */
+	if (job->request_len < cmdlen) {
+		ret = -ENOMSG;
+		goto fail_rport_msg;
+	}
+
+	ret = i->f->bsg_request(job);
+	if (!ret)
+		return FC_DISPATCH_UNLOCKED;
+
+fail_rport_msg:
+	/* return the errno failure code as the only status */
+	BUG_ON(job->reply_len < sizeof(uint32_t));
+	job->reply->result = ret;
+	job->reply_len = sizeof(uint32_t);
+	fc_bsg_jobdone(job);
+	return FC_DISPATCH_UNLOCKED;
+}
+
+
+/**
+ * fc_bsg_request_handler - generic handler for bsg requests
+ * @q:		request queue to manage
+ * @shost:	Scsi_Host related to the bsg object
+ * @rport:	FC remote port related to the bsg object (optional)
+ * @dev:	device structure for bsg object
+ */
+static void
+fc_bsg_request_handler(struct request_queue *q, struct Scsi_Host *shost,
+		       struct fc_rport *rport, struct device *dev)
+{
+	struct request *req;
+	struct fc_bsg_job *job;
+	enum fc_dispatch_result ret;
+
+	if (!get_device(dev))
+		return;
+
+	while (!blk_queue_plugged(q)) {
+		if (rport && (rport->port_state == FC_PORTSTATE_BLOCKED))
+				break;
+
+		req = blk_fetch_request(q);
+		if (!req)
+			break;
+
+		if (rport && (rport->port_state != FC_PORTSTATE_ONLINE)) {
+			req->errors = -ENXIO;
+			spin_unlock_irq(q->queue_lock);
+			blk_end_request(req, -ENXIO, blk_rq_bytes(req));
+			spin_lock_irq(q->queue_lock);
+			continue;
+		}
+
+		spin_unlock_irq(q->queue_lock);
+
+		ret = fc_req_to_bsgjob(shost, rport, req);
+		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->result = -ENOMSG;
+			job->reply_len = sizeof(uint32_t);
+			fc_bsg_jobdone(job);
+			spin_lock_irq(q->queue_lock);
+			continue;
+		}
+
+		/* the dispatch routines will unlock the queue_lock */
+		if (rport)
+			ret = fc_bsg_rport_dispatch(q, shost, rport, job);
+		else
+			ret = fc_bsg_host_dispatch(q, shost, job);
+
+		/* did dispatcher hit state that can't process any more */
+		if (ret == FC_DISPATCH_BREAK)
+			break;
+
+		/* did dispatcher had released the lock */
+		if (ret == FC_DISPATCH_UNLOCKED)
+			spin_lock_irq(q->queue_lock);
+	}
+
+	spin_unlock_irq(q->queue_lock);
+	put_device(dev);
+	spin_lock_irq(q->queue_lock);
+}
+
+
+/**
+ * fc_bsg_host_handler - handler for bsg requests for a fc host
+ * @q:		fc host request queue
+ */
+static void
+fc_bsg_host_handler(struct request_queue *q)
+{
+	struct Scsi_Host *shost = q->queuedata;
+
+	fc_bsg_request_handler(q, shost, NULL, &shost->shost_gendev);
+}
+
+
+/**
+ * fc_bsg_rport_handler - handler for bsg requests for a fc rport
+ * @q:		rport request queue
+ */
+static void
+fc_bsg_rport_handler(struct request_queue *q)
+{
+	struct fc_rport *rport = q->queuedata;
+	struct Scsi_Host *shost = rport_to_shost(rport);
+
+	fc_bsg_request_handler(q, shost, rport, &rport->dev);
+}
+
+
+/**
+ * fc_bsg_hostadd - Create and add the bsg hooks so we can receive requests
+ * @shost:	shost for fc_host
+ * @fc_host:	fc_host adding the structures to
+ */
+static int
+fc_bsg_hostadd(struct Scsi_Host *shost, struct fc_host_attrs *fc_host)
+{
+	struct device *dev = &shost->shost_gendev;
+	struct fc_internal *i = to_fc_internal(shost->transportt);
+	struct request_queue *q;
+	int err;
+	char bsg_name[BUS_ID_SIZE]; /*20*/
+
+	fc_host->rqst_q = NULL;
+
+	if (!i->f->bsg_request)
+		return -ENOTSUPP;
+
+	snprintf(bsg_name, sizeof(bsg_name),
+		 "fc_host%d", shost->host_no);
+
+	q = __scsi_alloc_queue(shost, fc_bsg_host_handler);
+	if (!q) {
+		printk(KERN_ERR "fc_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_rq_timed_out(q, fc_bsg_job_timeout);
+	blk_queue_rq_timeout(q, FC_DEFAULT_BSG_TIMEOUT);
+
+	err = bsg_register_queue(q, dev, bsg_name, NULL);
+	if (err) {
+		printk(KERN_ERR "fc_host%d: bsg interface failed to "
+				"initialize - register queue\n",
+				shost->host_no);
+		blk_cleanup_queue(q);
+		return err;
+	}
+
+	fc_host->rqst_q = q;
+	return 0;
+}
+
+
+/**
+ * fc_bsg_rportadd - Create and add the bsg hooks so we can receive requests
+ * @shost:	shost that rport is attached to
+ * @rport:	rport that the bsg hooks are being attached to
+ */
+static int
+fc_bsg_rportadd(struct Scsi_Host *shost, struct fc_rport *rport)
+{
+	struct device *dev = &rport->dev;
+	struct fc_internal *i = to_fc_internal(shost->transportt);
+	struct request_queue *q;
+	int err;
+
+	rport->rqst_q = NULL;
+
+	if (!i->f->bsg_request)
+		return -ENOTSUPP;
+
+	q = __scsi_alloc_queue(shost, fc_bsg_rport_handler);
+	if (!q) {
+		printk(KERN_ERR "%s: bsg interface failed to "
+				"initialize - no request queue\n",
+				 dev->kobj.name);
+		return -ENOMEM;
+	}
+
+	q->queuedata = rport;
+	queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
+	blk_queue_rq_timed_out(q, fc_bsg_job_timeout);
+	blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
+
+	err = bsg_register_queue(q, dev, NULL, NULL);
+	if (err) {
+		printk(KERN_ERR "%s: bsg interface failed to "
+				"initialize - register queue\n",
+				 dev->kobj.name);
+		blk_cleanup_queue(q);
+		return err;
+	}
+
+	rport->rqst_q = q;
+	return 0;
+}
+
+
+/**
+ * fc_bsg_remove - Deletes the bsg hooks on fchosts/rports
+ * @q:	the request_queue that is to be torn down.
+ */
+static void
+fc_bsg_remove(struct request_queue *q)
+{
+	if (q) {
+		bsg_unregister_queue(q);
+		blk_cleanup_queue(q);
+	}
+}
+
+
 /* Original Author:  Martin Hicks */
 MODULE_AUTHOR("James Smart");
 MODULE_DESCRIPTION("FC Transport Attributes");