bdev: split examine into two parts

During spdk_bdev_init, examine_config is called.
This call can claim bdev synchronously, based on
configuration. On spdk_bdev_start if none module
claimed bdev, examine_disk is called and can
perform I/O before claiming bdev.

Signed-off-by: Piotr Pelplinski <piotr.pelplinski@intel.com>
Change-Id: I1448dd368cf3a24a5daccab387d7af7c3d231127
Reviewed-on: https://review.gerrithub.io/413913
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Maciej Szwed <maciej.szwed@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

include/spdk/bdev_module.h

@@ -99,11 +99,19 @@ struct spdk_bdev_module {
 	int (*get_ctx_size)(void);
 
 	/**
-	 * Notification that a bdev should be examined by a virtual bdev module.
+	 * First notification that a bdev should be examined by a virtual bdev module.
 	 * Virtual bdev modules may use this to examine newly-added bdevs and automatically
-	 * create their own vbdevs.
+	 * create their own vbdevs, but no I/O to device can be send to bdev at this point.
+	 * Only vbdevs based on config files can be created here.
 	 */
-	void (*examine)(struct spdk_bdev *bdev);
+	void (*examine_config)(struct spdk_bdev *bdev);
+
+	/**
+	 * Second notification that a bdev should be examined by a virtual bdev module.
+	 * Virtual bdev modules may use this to examine newly-added bdevs and automatically
+	 * create their own vbdevs. This callback may use I/O operations end finish asynchronously.
+	 */
+	void (*examine_disk)(struct spdk_bdev *bdev);
 
 	/**
 	 * Denotes if the module_init function may complete asynchronously. If set to true,

lib/bdev/aio/bdev_aio.c

@@ -65,7 +65,6 @@ static struct spdk_bdev_module aio_if = {
 	.module_fini	= NULL,
 	.config_text	= bdev_aio_get_spdk_running_config,
 	.get_ctx_size	= bdev_aio_get_ctx_size,
-	.examine	= NULL,
 };
 
 SPDK_BDEV_MODULE_REGISTER(&aio_if)

lib/bdev/bdev.c

@@ -2801,14 +2801,32 @@ static void
 spdk_bdev_start(struct spdk_bdev *bdev)
 {
 	struct spdk_bdev_module *module;
+	uint32_t action;
 
 	SPDK_DEBUGLOG(SPDK_LOG_BDEV, "Inserting bdev %s into list\n", bdev->name);
 	TAILQ_INSERT_TAIL(&g_bdev_mgr.bdevs, bdev, internal.link);
 
+	/* Examine configuration before initializing I/O */
 	TAILQ_FOREACH(module, &g_bdev_mgr.bdev_modules, internal.tailq) {
-		if (module->examine) {
+		if (module->examine_config) {
+			action = module->internal.action_in_progress;
 			module->internal.action_in_progress++;
-			module->examine(bdev);
+			module->examine_config(bdev);
+			if (action != module->internal.action_in_progress) {
+				SPDK_ERRLOG("examine_config for module %s did not call spdk_bdev_module_examine_done()\n",
+					    module->name);
+			}
+		}
+	}
+
+	if (bdev->internal.claim_module) {
+		return;
+	}
+
+	TAILQ_FOREACH(module, &g_bdev_mgr.bdev_modules, internal.tailq) {
+		if (module->examine_disk) {
+			module->internal.action_in_progress++;
+			module->examine_disk(bdev);
 		}
 	}
 }
@@ -3165,7 +3183,7 @@ spdk_bdev_module_list_add(struct spdk_bdev_module *bdev_module)
 	 *  ready to handle examine callbacks from later modules that will
 	 *  register physical bdevs.
 	 */
-	if (bdev_module->examine != NULL) {
+	if (bdev_module->examine_config != NULL || bdev_module->examine_disk != NULL) {
 		TAILQ_INSERT_HEAD(&g_bdev_mgr.bdev_modules, bdev_module, internal.tailq);
 	} else {
 		TAILQ_INSERT_TAIL(&g_bdev_mgr.bdev_modules, bdev_module, internal.tailq);

lib/bdev/error/vbdev_error.c

@@ -89,7 +89,7 @@ static struct spdk_bdev_module error_if = {
 	.name = "error",
 	.module_init = vbdev_error_init,
 	.module_fini = vbdev_error_fini,
-	.examine = vbdev_error_examine,
+	.examine_config = vbdev_error_examine,
 	.config_json = vbdev_error_config_json,
 
 };

lib/bdev/gpt/vbdev_gpt.c

@@ -55,7 +55,7 @@ static void vbdev_gpt_examine(struct spdk_bdev *bdev);
 static struct spdk_bdev_module gpt_if = {
 	.name = "gpt",
 	.module_init = vbdev_gpt_init,
-	.examine = vbdev_gpt_examine,
+	.examine_disk = vbdev_gpt_examine,
 
 };
 SPDK_BDEV_MODULE_REGISTER(&gpt_if)

lib/bdev/lvol/vbdev_lvol.c

@@ -50,7 +50,7 @@ static void vbdev_lvs_examine(struct spdk_bdev *bdev);
 static struct spdk_bdev_module g_lvol_if = {
 	.name = "lvol",
 	.module_init = vbdev_lvs_init,
-	.examine = vbdev_lvs_examine,
+	.examine_disk = vbdev_lvs_examine,
 	.get_ctx_size = vbdev_lvs_get_ctx_size,
 
 };

lib/bdev/passthru/vbdev_passthru.c

@@ -62,7 +62,7 @@ static struct spdk_bdev_module passthru_if = {
 	.module_init = vbdev_passthru_init,
 	.config_text = vbdev_passthru_get_spdk_running_config,
 	.get_ctx_size = vbdev_passthru_get_ctx_size,
-	.examine = vbdev_passthru_examine,
+	.examine_config = vbdev_passthru_examine,
 	.module_fini = vbdev_passthru_finish
 };
 

lib/bdev/split/vbdev_split.c

@@ -78,7 +78,7 @@ static struct spdk_bdev_module split_if = {
 	.name = "split",
 	.module_init = vbdev_split_init,
 	.module_fini = vbdev_split_fini,
-	.examine = vbdev_split_examine,
+	.examine_config = vbdev_split_examine,
 	.config_json = vbdev_split_config_json,
 };
 
@@ -426,7 +426,6 @@ vbdev_split_examine(struct spdk_bdev *bdev)
 			SPDK_ERRLOG("could not split bdev %s\n", bdev->name);
 		}
 	}
-
 	spdk_bdev_module_examine_done(&split_if);
 }
 

test/unit/lib/bdev/bdev.c/bdev_ut.c

@@ -181,9 +181,9 @@ vbdev_ut_module_fini(void)
 
 struct spdk_bdev_module vbdev_ut_if = {
 	.name = "vbdev_ut",
-	.examine = vbdev_ut_examine,
 	.module_init = vbdev_ut_module_init,
 	.module_fini = vbdev_ut_module_fini,
+	.examine_config = vbdev_ut_examine,
 };
 
 SPDK_BDEV_MODULE_REGISTER(&bdev_ut_if)

test/unit/lib/bdev/part.c/part_ut.c

@@ -68,7 +68,7 @@ static void vbdev_ut_examine(struct spdk_bdev *bdev);
 
 struct spdk_bdev_module vbdev_ut_if = {
 	.name = "vbdev_ut",
-	.examine = vbdev_ut_examine,
+	.examine_config = vbdev_ut_examine,
 };
 
 SPDK_BDEV_MODULE_REGISTER(&bdev_ut_if)