[SCSI] libiscsi: make can_queue configurable

This patch allows us to set can_queue and cmds_per_lun from userspace
when we create the session/host. From there we can set it on a per
target basis. The patch fully converts iscsi_tcp, but only hooks
up ib_iser for cmd_per_lun since it currently has a lots of preallocations
based on can_queue.

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

drivers/infiniband/ulp/iser/iscsi_iser.c

···
 static struct iscsi_cls_session *
 iscsi_iser_session_create(struct iscsi_transport *iscsit,
 			 struct scsi_transport_template *scsit,
-			  uint32_t initial_cmdsn, uint32_t *hostno)
+			 uint16_t cmds_max, uint16_t qdepth,
+			 uint32_t initial_cmdsn, uint32_t *hostno)
 {
 	struct iscsi_cls_session *cls_session;
 	struct iscsi_session *session;
···
 	struct iscsi_iser_cmd_task *iser_ctask;
 	struct iser_desc *desc;
 
+	/*
+	 * we do not support setting can_queue cmd_per_lun from userspace yet
+	 * because we preallocate so many resources
+	 */
 	cls_session = iscsi_session_setup(iscsit, scsit,
+					  ISCSI_DEF_XMIT_CMDS_MAX,
+					  ISCSI_MAX_CMD_PER_LUN,
 					  sizeof(struct iscsi_iser_cmd_task),
 					  sizeof(struct iser_desc),
 					  initial_cmdsn, &hn);
···
 static struct scsi_host_template iscsi_iser_sht = {
 	.name                   = "iSCSI Initiator over iSER, v." DRV_VER,
 	.queuecommand           = iscsi_queuecommand,
-	.can_queue		= ISCSI_XMIT_CMDS_MAX - 1,
+	.can_queue		= ISCSI_DEF_XMIT_CMDS_MAX - 1,
 	.sg_tablesize           = ISCSI_ISER_SG_TABLESIZE,
 	.max_sectors		= 1024,
 	.cmd_per_lun            = ISCSI_MAX_CMD_PER_LUN,

drivers/infiniband/ulp/iser/iscsi_iser.h

···
 #define ISER_MAX_TX_MISC_PDUS		6 /* NOOP_OUT(2), TEXT(1),         *
 					   * SCSI_TMFUNC(2), LOGOUT(1) */
 
-#define ISER_QP_MAX_RECV_DTOS		(ISCSI_XMIT_CMDS_MAX + \
+#define ISER_QP_MAX_RECV_DTOS		(ISCSI_DEF_XMIT_CMDS_MAX + \
 					ISER_MAX_RX_MISC_PDUS    +  \
 					ISER_MAX_TX_MISC_PDUS)
 
···
 
 #define ISER_INFLIGHT_DATAOUTS		8
 
-#define ISER_QP_MAX_REQ_DTOS		(ISCSI_XMIT_CMDS_MAX *    \
+#define ISER_QP_MAX_REQ_DTOS		(ISCSI_DEF_XMIT_CMDS_MAX *    \
 					(1 + ISER_INFLIGHT_DATAOUTS) + \
 					ISER_MAX_TX_MISC_PDUS        + \
 					ISER_MAX_RX_MISC_PDUS)

drivers/infiniband/ulp/iser/iser_verbs.c

···
 	params.max_pages_per_fmr = ISCSI_ISER_SG_TABLESIZE + 1;
 	/* make the pool size twice the max number of SCSI commands *
 	 * the ML is expected to queue, watermark for unmap at 50%  */
-	params.pool_size	 = ISCSI_XMIT_CMDS_MAX * 2;
-	params.dirty_watermark	 = ISCSI_XMIT_CMDS_MAX;
+	params.pool_size	 = ISCSI_DEF_XMIT_CMDS_MAX * 2;
+	params.dirty_watermark	 = ISCSI_DEF_XMIT_CMDS_MAX;
 	params.cache		 = 0;
 	params.flush_function	 = NULL;
 	params.access		 = (IB_ACCESS_LOCAL_WRITE  |

drivers/scsi/iscsi_tcp.c

···
 static struct iscsi_cls_session *
 iscsi_tcp_session_create(struct iscsi_transport *iscsit,
 			 struct scsi_transport_template *scsit,
+			 uint16_t cmds_max, uint16_t qdepth,
 			 uint32_t initial_cmdsn, uint32_t *hostno)
 {
 	struct iscsi_cls_session *cls_session;
···
 	uint32_t hn;
 	int cmd_i;
 
-	cls_session = iscsi_session_setup(iscsit, scsit,
+	cls_session = iscsi_session_setup(iscsit, scsit, cmds_max, qdepth,
 					 sizeof(struct iscsi_tcp_cmd_task),
 					 sizeof(struct iscsi_tcp_mgmt_task),
 					 initial_cmdsn, &hn);
···
 	.name			= "iSCSI Initiator over TCP/IP",
 	.queuecommand           = iscsi_queuecommand,
 	.change_queue_depth	= iscsi_change_queue_depth,
-	.can_queue		= ISCSI_XMIT_CMDS_MAX - 1,
+	.can_queue		= ISCSI_DEF_XMIT_CMDS_MAX - 1,
 	.sg_tablesize		= ISCSI_SG_TABLESIZE,
 	.max_sectors		= 0xFFFF,
 	.cmd_per_lun		= ISCSI_DEF_CMD_PER_LUN,

drivers/scsi/libiscsi.c

···
  * iscsi_session_setup - create iscsi cls session and host and session
  * @scsit: scsi transport template
  * @iscsit: iscsi transport template
+ * @cmds_max: scsi host can queue
+ * @qdepth: scsi host cmds per lun
+ * @cmd_task_size: LLD ctask private data size
+ * @mgmt_task_size: LLD mtask private data size
  * @initial_cmdsn: initial CmdSN
  * @hostno: host no allocated
  *
···
 struct iscsi_cls_session *
 iscsi_session_setup(struct iscsi_transport *iscsit,
 		    struct scsi_transport_template *scsit,
+		    uint16_t cmds_max, uint16_t qdepth,
 		    int cmd_task_size, int mgmt_task_size,
 		    uint32_t initial_cmdsn, uint32_t *hostno)
 {
···
 	struct iscsi_cls_session *cls_session;
 	int cmd_i;
 
+	if (qdepth > ISCSI_MAX_CMD_PER_LUN || qdepth < 1) {
+		if (qdepth != 0)
+			printk(KERN_ERR "iscsi: invalid queue depth of %d. "
+			      "Queue depth must be between 1 and %d.\n",
+			      qdepth, ISCSI_MAX_CMD_PER_LUN);
+		qdepth = ISCSI_DEF_CMD_PER_LUN;
+	}
+
+	if (cmds_max < 2 || (cmds_max & (cmds_max - 1)) ||
+	    cmds_max >= ISCSI_MGMT_ITT_OFFSET) {
+		if (cmds_max != 0)
+			printk(KERN_ERR "iscsi: invalid can_queue of %d. "
+			       "can_queue must be a power of 2 and between "
+			       "2 and %d - setting to %d.\n", cmds_max,
+			       ISCSI_MGMT_ITT_OFFSET, ISCSI_DEF_XMIT_CMDS_MAX);
+		cmds_max = ISCSI_DEF_XMIT_CMDS_MAX;
+	}
+
 	shost = scsi_host_alloc(iscsit->host_template,
 				hostdata_privsize(sizeof(*session)));
 	if (!shost)
 		return NULL;
 
+	/* the iscsi layer takes one task for reserve */
+	shost->can_queue = cmds_max - 1;
+	shost->cmd_per_lun = qdepth;
 	shost->max_id = 1;
 	shost->max_channel = 0;
 	shost->max_lun = iscsit->max_lun;
···
 	session->host = shost;
 	session->state = ISCSI_STATE_FREE;
 	session->mgmtpool_max = ISCSI_MGMT_CMDS_MAX;
-	session->cmds_max = ISCSI_XMIT_CMDS_MAX;
+	session->cmds_max = cmds_max;
 	session->cmdsn = initial_cmdsn;
 	session->exp_cmdsn = initial_cmdsn + 1;
 	session->max_cmdsn = initial_cmdsn + 1;

drivers/scsi/scsi_transport_iscsi.c

···
 	uint32_t hostno;
 
 	session = transport->create_session(transport, &priv->t,
+					    ev->u.c_session.cmds_max,
+					    ev->u.c_session.queue_depth,
 					    ev->u.c_session.initial_cmdsn,
 					    &hostno);
 	if (!session)

include/scsi/iscsi_if.h

···
 		/* messages u -> k */
 		struct msg_create_session {
 			uint32_t	initial_cmdsn;
+			uint16_t	cmds_max;
+			uint16_t	queue_depth;
 		} c_session;
 		struct msg_destroy_session {
 			uint32_t	sid;

include/scsi/libiscsi.h

···
 #define debug_scsi(fmt...)
 #endif
 
-#define ISCSI_XMIT_CMDS_MAX	128	/* must be power of 2 */
-#define ISCSI_MGMT_CMDS_MAX	32	/* must be power of 2 */
-#define ISCSI_CONN_MAX			1
+#define ISCSI_DEF_XMIT_CMDS_MAX	128	/* must be power of 2 */
+#define ISCSI_MGMT_CMDS_MAX	16	/* must be power of 2 */
 
 #define ISCSI_MGMT_ITT_OFFSET	0xa00
 
···
  */
 extern struct iscsi_cls_session *
 iscsi_session_setup(struct iscsi_transport *, struct scsi_transport_template *,
-		    int, int, uint32_t, uint32_t *);
+		    uint16_t, uint16_t, int, int, uint32_t, uint32_t *);
 extern void iscsi_session_teardown(struct iscsi_cls_session *);
 extern struct iscsi_session *class_to_transport_session(struct iscsi_cls_session *);
 extern void iscsi_session_recovery_timedout(struct iscsi_cls_session *);

include/scsi/scsi_transport_iscsi.h

···
 	unsigned int max_conn;
 	unsigned int max_cmd_len;
 	struct iscsi_cls_session *(*create_session) (struct iscsi_transport *it,
-		struct scsi_transport_template *t, uint32_t sn, uint32_t *hn);
+		struct scsi_transport_template *t, uint16_t, uint16_t,
+		uint32_t sn, uint32_t *hn);
 	void (*destroy_session) (struct iscsi_cls_session *session);
 	struct iscsi_cls_conn *(*create_conn) (struct iscsi_cls_session *sess,
 				uint32_t cid);