module/raid: max degraded bdevs constraint changed

Attribute base_bdevs_max_degraded of raid_bdev_module struct is
replaced with more generic structure allowing implementation of
raid levels for which constraint is by number of operational
drives instead of maximum number of failed drives.

Signed-off-by: Krzysztof Smolinski <krzysztof.smolinski@intel.com>
Change-Id: Ie7079993d27d32118b865c3aabd92252a2807b94
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/14411
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Mellanox Build Bot
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Krzysztof Karas <krzysztof.karas@intel.com>

module/bdev/raid/bdev_raid.c

@@ -918,13 +918,14 @@ raid_bdev_create(const char *name, uint32_t strip_size, uint8_t num_base_bdevs,
 	struct raid_bdev *raid_bdev;
 	struct spdk_bdev *raid_bdev_gen;
 	struct raid_bdev_module *module;
+	uint8_t min_operational;
 
 	if (raid_bdev_find_by_name(name) != NULL) {
 		SPDK_ERRLOG("Duplicate raid bdev name found: %s\n", name);
 		return -EEXIST;
 	}
 
-	if (spdk_u32_is_pow2(strip_size) == false) {
+	if (strip_size && spdk_u32_is_pow2(strip_size) == false) {
 		SPDK_ERRLOG("Invalid strip size %" PRIu32 "\n", strip_size);
 		return -EINVAL;
 	}
@@ -943,6 +944,34 @@ raid_bdev_create(const char *name, uint32_t strip_size, uint8_t num_base_bdevs,
 		return -EINVAL;
 	}
 
+	switch (module->base_bdevs_constraint.type) {
+	case CONSTRAINT_MAX_BASE_BDEVS_REMOVED:
+		min_operational = num_base_bdevs - module->base_bdevs_constraint.value;
+		break;
+	case CONSTRAINT_MIN_BASE_BDEVS_OPERATIONAL:
+		min_operational = module->base_bdevs_constraint.value;
+		break;
+	case CONSTRAINT_UNSET:
+		if (module->base_bdevs_constraint.value != 0) {
+			SPDK_ERRLOG("Unexpected constraint value '%u' provided for raid bdev '%s'.\n",
+				    (uint8_t)module->base_bdevs_constraint.value, name);
+			return -EINVAL;
+		}
+		min_operational = num_base_bdevs;
+		break;
+	default:
+		SPDK_ERRLOG("Unrecognised constraint type '%u' in module for raid level '%s'.\n",
+			    (uint8_t)module->base_bdevs_constraint.type,
+			    raid_bdev_level_to_str(module->level));
+		return -EINVAL;
+	};
+
+	if (min_operational == 0 || min_operational > num_base_bdevs) {
+		SPDK_ERRLOG("Wrong constraint value for raid level '%s'.\n",
+			    raid_bdev_level_to_str(module->level));
+		return -EINVAL;
+	}
+
 	raid_bdev = calloc(1, sizeof(*raid_bdev));
 	if (!raid_bdev) {
 		SPDK_ERRLOG("Unable to allocate memory for raid bdev\n");
@@ -966,6 +995,7 @@ raid_bdev_create(const char *name, uint32_t strip_size, uint8_t num_base_bdevs,
 	raid_bdev->strip_size_kb = strip_size;
 	raid_bdev->state = RAID_BDEV_STATE_CONFIGURING;
 	raid_bdev->level = level;
+	raid_bdev->min_base_bdevs_operational = min_operational;
 
 	raid_bdev_gen = &raid_bdev->bdev;
 

module/bdev/raid/bdev_raid.h

@@ -121,6 +121,9 @@ struct raid_bdev {
 	/* number of base bdevs discovered */
 	uint8_t				num_base_bdevs_discovered;
 
+	/* minimum number of viable base bdevs that are required by array to operate */
+	uint8_t				min_base_bdevs_operational;
+
 	/* Raid Level of this raid bdev */
 	enum raid_level			level;
 
@@ -181,10 +184,17 @@ struct raid_bdev_module {
 	uint8_t base_bdevs_min;
 
 	/*
-	 * Maximum number of base bdevs that can be removed without failing
+	 * RAID constraint. Determines number of base bdevs that can be removed
-	 * the array.
+	 * without failing the array.
 	 */
-	uint8_t base_bdevs_max_degraded;
+	struct {
+		enum {
+			CONSTRAINT_UNSET = 0,
+			CONSTRAINT_MAX_BASE_BDEVS_REMOVED,
+			CONSTRAINT_MIN_BASE_BDEVS_OPERATIONAL,
+		} type;
+		uint8_t value;
+	} base_bdevs_constraint;
 
 	/*
 	 * Called when the raid is starting, right before changing the state to

module/bdev/raid/raid5f.c

@@ -115,7 +115,7 @@ raid5f_chunk_stripe_req(struct chunk *chunk)
 static inline uint8_t
 raid5f_stripe_data_chunks_num(const struct raid_bdev *raid_bdev)
 {
-	return raid_bdev->num_base_bdevs - raid_bdev->module->base_bdevs_max_degraded;
+	return raid_bdev->min_base_bdevs_operational;
 }
 
 static inline uint8_t
@@ -697,7 +697,7 @@ raid5f_get_io_channel(struct raid_bdev *raid_bdev)
 static struct raid_bdev_module g_raid5f_module = {
 	.level = RAID5F,
 	.base_bdevs_min = 3,
-	.base_bdevs_max_degraded = 1,
+	.base_bdevs_constraint = {CONSTRAINT_MAX_BASE_BDEVS_REMOVED, 1},
 	.start = raid5f_start,
 	.stop = raid5f_stop,
 	.submit_rw_request = raid5f_submit_rw_request,

test/unit/lib/bdev/raid/raid5f.c/raid5f_ut.c

@@ -128,6 +128,22 @@ create_raid_bdev(struct raid5f_params *params)
 
 	raid_bdev->module = &g_raid5f_module;
 	raid_bdev->num_base_bdevs = params->num_base_bdevs;
+
+	switch (raid_bdev->module->base_bdevs_constraint.type) {
+	case CONSTRAINT_MAX_BASE_BDEVS_REMOVED:
+		raid_bdev->min_base_bdevs_operational = raid_bdev->num_base_bdevs -
+							raid_bdev->module->base_bdevs_constraint.value;
+		break;
+	case CONSTRAINT_MIN_BASE_BDEVS_OPERATIONAL:
+		raid_bdev->min_base_bdevs_operational = raid_bdev->module->base_bdevs_constraint.value;
+		break;
+	case CONSTRAINT_UNSET:
+		raid_bdev->min_base_bdevs_operational = raid_bdev->num_base_bdevs;
+		break;
+	default:
+		CU_FAIL_FATAL("unsupported raid constraint type");
+	};
+
 	raid_bdev->base_bdev_info = calloc(raid_bdev->num_base_bdevs,
 					   sizeof(struct raid_base_bdev_info));
 	SPDK_CU_ASSERT_FATAL(raid_bdev->base_bdev_info != NULL);