module/raid: check for the minimum required base bdevs

Define the minimum number of base devices required for a raid level in
struct raid_module and check that when starting the array.

Change-Id: Ic70d107721e0df48ef8d9406132c103eee3cc9d4
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/851
Reviewed-by: Paul Luse <paul.e.luse@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

module/bdev/raid/bdev_raid.c

@@ -1179,6 +1179,21 @@ raid_bdev_create(struct raid_bdev_config *raid_cfg)
 {
 	struct raid_bdev *raid_bdev;
 	struct spdk_bdev *raid_bdev_gen;
+	struct raid_bdev_module *module;
+
+	module = raid_bdev_module_find(raid_cfg->level);
+	if (module == NULL) {
+		SPDK_ERRLOG("Unsupported raid level '%d'\n", raid_cfg->level);
+		return -EINVAL;
+	}
+
+	assert(module->base_bdevs_min != 0);
+	if (raid_cfg->num_base_bdevs < module->base_bdevs_min) {
+		SPDK_ERRLOG("At least %u base devices required for %s\n",
+			    module->base_bdevs_min,
+			    raid_bdev_level_to_str(raid_cfg->level));
+		return -EINVAL;
+	}
 
 	raid_bdev = calloc(1, sizeof(*raid_bdev));
 	if (!raid_bdev) {
@@ -1186,7 +1201,7 @@ raid_bdev_create(struct raid_bdev_config *raid_cfg)
 		return -ENOMEM;
 	}
 
-	assert(raid_cfg->num_base_bdevs != 0);
+	raid_bdev->module = module;
 	raid_bdev->num_base_bdevs = raid_cfg->num_base_bdevs;
 	raid_bdev->base_bdev_info = calloc(raid_bdev->num_base_bdevs,
 					   sizeof(struct raid_base_bdev_info));
@@ -1205,14 +1220,6 @@ raid_bdev_create(struct raid_bdev_config *raid_cfg)
 	raid_bdev->config = raid_cfg;
 	raid_bdev->level = raid_cfg->level;
 
-	raid_bdev->module = raid_bdev_module_find(raid_bdev->level);
-	if (raid_bdev->module == NULL) {
-		SPDK_ERRLOG("Unsupported raid level '%d'\n", raid_bdev->level);
-		free(raid_bdev->base_bdev_info);
-		free(raid_bdev);
-		return -EINVAL;
-	}
-
 	raid_bdev_gen = &raid_bdev->bdev;
 
 	raid_bdev_gen->name = strdup(raid_cfg->name);

module/bdev/raid/bdev_raid.h

@@ -256,6 +256,9 @@ struct raid_bdev_module {
 	/* RAID level implemented by this module */
 	enum raid_level level;
 
+	/* Minimum required number of base bdevs. Must be > 0. */
+	uint8_t base_bdevs_min;
+
 	/*
 	 * Called when the raid is starting, right before changing the state to
 	 * online and registering the bdev. Parameters of the bdev like blockcnt

module/bdev/raid/raid0.c

@@ -374,6 +374,7 @@ static int raid0_start(struct raid_bdev *raid_bdev)
 
 static struct raid_bdev_module g_raid0_module = {
 	.level = RAID0,
+	.base_bdevs_min = 1,
 	.start = raid0_start,
 	.submit_rw_request = raid0_submit_rw_request,
 	.submit_null_payload_request = raid0_submit_null_payload_request,