vhost-scsi: use first free SCSI target ID if -1 specified

Fixes #328

Change-Id: I34b816a31a51d1a8aa4c61285e01d0249c283f53
Signed-off-by: Pawel Wodkowski <pawelx.wodkowski@intel.com>
Reviewed-on: https://review.gerrithub.io/c/442434
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

doc/jsonrpc.md

@@ -4094,9 +4094,13 @@ In vhost target `ctrlr` create SCSI target with ID `scsi_target_num` and add `bd
 Name                    | Optional | Type        | Description
 ----------------------- | -------- | ----------- | -----------
 ctrlr                   | Required | string      | Controller name
-scsi_target_num         | Required | number      | SCSI target ID between 0 and 7
+scsi_target_num         | Required | number      | SCSI target ID between 0 and 7 or -1 to use first free ID.
 bdev_name               | Required | string      | Name of bdev to expose as a LUN 0
 
+### Response
+
+SCSI target ID.
+
 ### Example
 
 Example request:
@@ -4121,7 +4125,7 @@ response:
 {
   "jsonrpc": "2.0",
   "id": 1,
-  "result": true
+  "result": 1
 }
 ~~~
 

include/spdk/vhost.h

@@ -207,12 +207,19 @@ int spdk_vhost_scsi_dev_construct(const char *name, const char *cpumask);
  * automatically detected by the other side.
  *
  * \param vdev vhost SCSI device.
- * \param scsi_tgt_num slot to attach to.
+ * \param scsi_tgt_num slot to attach to or negative value to use first free.
  * \param bdev_name name of the SPDK bdev to associate with SCSI LUN0.
  *
- * \return 0 on success, negative errno on error.
+ * \return value >= 0 on success - the SCSI target ID, negative errno code:
+ * -EINVAL - one of the arguments is invalid:
+ *   - vdev is not vhost SCSI device
+ *   - SCSI target ID is out of range
+ *   - bdev name is NULL
+ *   - can't create SCSI LUN because of other errors e.g.: bdev does not exist
+ * -ENOSPC - scsi_tgt_num is -1 and maximum targets in vhost SCSI device reached
+ * -EEXIST - SCSI target ID already exists
  */
-int spdk_vhost_scsi_dev_add_tgt(struct spdk_vhost_dev *vdev, unsigned scsi_tgt_num,
+int spdk_vhost_scsi_dev_add_tgt(struct spdk_vhost_dev *vdev, int scsi_tgt_num,
 				const char *bdev_name);
 
 /**

lib/vhost/vhost_rpc.c

@@ -103,7 +103,7 @@ SPDK_RPC_REGISTER("construct_vhost_scsi_controller", spdk_rpc_construct_vhost_sc
 
 struct rpc_add_vhost_scsi_ctrlr_lun {
 	char *ctrlr;
-	uint32_t scsi_target_num;
+	int32_t scsi_target_num;
 	char *bdev_name;
 
 	struct spdk_jsonrpc_request *request;
@@ -119,7 +119,7 @@ free_rpc_add_vhost_scsi_ctrlr_lun(struct rpc_add_vhost_scsi_ctrlr_lun *req)
 
 static const struct spdk_json_object_decoder rpc_vhost_add_lun[] = {
 	{"ctrlr", offsetof(struct rpc_add_vhost_scsi_ctrlr_lun, ctrlr), spdk_json_decode_string },
-	{"scsi_target_num", offsetof(struct rpc_add_vhost_scsi_ctrlr_lun, scsi_target_num), spdk_json_decode_uint32},
+	{"scsi_target_num", offsetof(struct rpc_add_vhost_scsi_ctrlr_lun, scsi_target_num), spdk_json_decode_int32},
 	{"bdev_name", offsetof(struct rpc_add_vhost_scsi_ctrlr_lun, bdev_name), spdk_json_decode_string },
 };
 
@@ -148,7 +148,7 @@ spdk_rpc_add_vhost_scsi_lun_cb(struct spdk_vhost_dev *vdev, void *arg)
 		return -1;
 	}
 
-	spdk_json_write_bool(w, true);
+	spdk_json_write_int32(w, rc);
 	spdk_jsonrpc_end_result(request, w);
 	return 0;
 

lib/vhost/vhost_scsi.c

@@ -938,7 +938,7 @@ spdk_vhost_scsi_session_add_tgt(struct spdk_vhost_dev *vdev,
 }
 
 int
-spdk_vhost_scsi_dev_add_tgt(struct spdk_vhost_dev *vdev, unsigned scsi_tgt_num,
+spdk_vhost_scsi_dev_add_tgt(struct spdk_vhost_dev *vdev, int scsi_tgt_num,
 			    const char *bdev_name)
 {
 	struct spdk_vhost_scsi_dev *svdev;
@@ -952,11 +952,24 @@ spdk_vhost_scsi_dev_add_tgt(struct spdk_vhost_dev *vdev, unsigned scsi_tgt_num,
 		return -EINVAL;
 	}
 
+	if (scsi_tgt_num < 0) {
+		for (scsi_tgt_num = 0; scsi_tgt_num < SPDK_VHOST_SCSI_CTRLR_MAX_DEVS; scsi_tgt_num++) {
+			if (svdev->scsi_dev_state[scsi_tgt_num].dev == NULL) {
+				break;
+			}
+		}
+
+		if (scsi_tgt_num == SPDK_VHOST_SCSI_CTRLR_MAX_DEVS) {
+			SPDK_ERRLOG("Controller %s - all targets already in use.\n", vdev->name);
+			return -ENOSPC;
+		}
+	} else {
 		if (scsi_tgt_num >= SPDK_VHOST_SCSI_CTRLR_MAX_DEVS) {
-		SPDK_ERRLOG("Controller %d target number too big (max %d)\n", scsi_tgt_num,
+			SPDK_ERRLOG("Controller %s target %d number too big (max %d)\n", vdev->name, scsi_tgt_num,
 				    SPDK_VHOST_SCSI_CTRLR_MAX_DEVS);
 			return -EINVAL;
 		}
+	}
 
 	if (bdev_name == NULL) {
 		SPDK_ERRLOG("No lun name specified\n");
@@ -993,7 +1006,7 @@ spdk_vhost_scsi_dev_add_tgt(struct spdk_vhost_dev *vdev, unsigned scsi_tgt_num,
 
 	spdk_vhost_dev_foreach_session(vdev, spdk_vhost_scsi_session_add_tgt,
 				       (void *)(uintptr_t)scsi_tgt_num);
-	return 0;
+	return scsi_tgt_num;
 }
 
 static int

scripts/rpc.py

@@ -1580,10 +1580,10 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
     p.set_defaults(func=construct_vhost_scsi_controller)
 
     def add_vhost_scsi_lun(args):
-        rpc.vhost.add_vhost_scsi_lun(args.client,
+        print(rpc.vhost.add_vhost_scsi_lun(args.client,
                                            ctrlr=args.ctrlr,
                                            scsi_target_num=args.scsi_target_num,
-                                     bdev_name=args.bdev_name)
+                                           bdev_name=args.bdev_name))
 
     p = subparsers.add_parser('add_vhost_scsi_lun',
                               help='Add lun to vhost controller')

test/json_config/json_config.sh

@@ -198,7 +198,7 @@ function create_vhost_subsystem_config() {
 
 	tgt_rpc construct_vhost_scsi_controller   VhostScsiCtrlr0
 	tgt_rpc add_vhost_scsi_lun                VhostScsiCtrlr0 0 MallocForVhost0p3
-	tgt_rpc add_vhost_scsi_lun                VhostScsiCtrlr0 1 MallocForVhost0p4
+	tgt_rpc add_vhost_scsi_lun                VhostScsiCtrlr0 -1 MallocForVhost0p4
 	tgt_rpc set_vhost_controller_coalescing   VhostScsiCtrlr0 1 100
 
 	tgt_rpc construct_vhost_blk_controller    VhostBlkCtrlr0 MallocForVhost0p5