ftl: fast shutdown

Adds API for fast shutdown - the ability for FTL to skip most
of the metadata persists made during clean shutdown, and relying
on their representation in shared memory instead. This allows for
faster update of SPDK (or just FTL, assuming no metadata changes),
with downtime reduction from 2-5 seconds to 500-1000 ms (for
14TiB+800GiB base and cache drives).

Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: Kozlowski Mateusz <mateusz.kozlowski@intel.com>
Change-Id: I5999d31698a81512db8d5893eabee7b505c80d06
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/13348
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

doc/jsonrpc.md

@@ -4742,6 +4742,7 @@ cache                   | Required | string      | Name of the cache device
 uuid                    | Optional | string      | UUID of restored bdev (not applicable when creating new instance)
 core_mask               | Optional | string      | CPU core(s) possible for placement of the ftl core thread, application main thread by default
 overprovisioning        | Optional | int         | Percentage of base device used for relocation, 20% by default
+fast_shutdown           | Optional | bool        | When set FTL will minimize persisted data on target application shutdown and rely on shared memory during next load
 
 #### Result
 
@@ -4796,6 +4797,7 @@ cache                   | Required | string      | Name of the cache device
 uuid                    | Required | string      | UUID of restored bdev
 core_mask               | Optional | string      | CPU core(s) possible for placement of the ftl core thread, application main thread by default
 overprovisioning        | Optional | int         | Percentage of base device used for relocation, 20% by default
+fast_shutdown           | Optional | bool        | When set FTL will minimize persisted data on target application shutdown and rely on shared memory during next load
 
 #### Result
 
@@ -4845,6 +4847,7 @@ This RPC is subject to change.
 Name                    | Optional | Type        | Description
 ----------------------- | -------- | ----------- | -----------
 name                    | Required | string      | Bdev name
+fast_shutdown           | Optional | bool        | When set FTL will minimize persisted data during deletion and rely on shared memory during next load
 
 #### Example
 
@@ -4882,6 +4885,7 @@ This RPC is subject to change.
 Name                    | Optional | Type        | Description
 ----------------------- | -------- | ----------- | -----------
 name                    | Required | string      | Bdev name
+fast_shutdown           | Optional | bool        | When set FTL will minimize persisted data during deletion and rely on shared memory during next load
 
 #### Example
 

include/spdk/ftl.h

@@ -59,6 +59,8 @@ struct spdk_ftl_conf {
 
 	/* Name of cache block device (must support extended metadata) */
 	char					*cache_bdev;
+	/* Enable fast shutdown path */
+	bool					fast_shutdown;
 };
 
 enum spdk_ftl_mode {
@@ -205,6 +207,14 @@ int spdk_ftl_writev(struct spdk_ftl_dev *dev, struct ftl_io *io, struct spdk_io_
  */
 size_t spdk_ftl_io_size(void);
 
+/**
+ * Enable fast shutdown.
+ *
+ * During fast shutdown FTL will keep the necessary metadata in shared memory instead
+ * of serializing it to storage. This allows for shorter downtime during upgrade process.
+ */
+void spdk_ftl_dev_set_fast_shutdown(struct spdk_ftl_dev *dev, bool fast_shutdown);
+
 #ifdef __cplusplus
 }
 #endif

lib/ftl/ftl_core.c

@@ -564,6 +564,13 @@ spdk_ftl_fini(void)
 	spdk_free(g_ftl_read_buf);
 }
 
+void
+spdk_ftl_dev_set_fast_shutdown(struct spdk_ftl_dev *dev, bool fast_shutdown)
+{
+	assert(dev);
+	dev->conf.fast_shutdown = fast_shutdown;
+}
+
 struct spdk_io_channel *
 spdk_ftl_get_io_channel(struct spdk_ftl_dev *dev)
 {

lib/ftl/mngt/ftl_mngt_md.c

@@ -84,7 +84,7 @@ ftl_mngt_deinit_md(struct spdk_ftl_dev *dev, struct ftl_mngt_process *mngt)
 
 	for (i = 0; i < FTL_LAYOUT_REGION_TYPE_MAX; i++, region++) {
 		if (layout->md[i]) {
-			ftl_md_destroy(layout->md[i]);
+			ftl_md_destroy(layout->md[i], ftl_md_destroy_region_flags(dev, layout->region[i].type));
 			layout->md[i] = NULL;
 		}
 	}
@@ -238,7 +238,7 @@ ftl_mngt_md_deinit_vss_emu(struct spdk_ftl_dev *dev, struct ftl_mngt_process *mn
 	struct ftl_layout *layout = &dev->layout;
 
 	if (layout->md[FTL_LAYOUT_REGION_TYPE_VSS]) {
-		ftl_md_destroy(layout->md[FTL_LAYOUT_REGION_TYPE_VSS]);
+		ftl_md_destroy(layout->md[FTL_LAYOUT_REGION_TYPE_VSS], 0);
 		layout->md[FTL_LAYOUT_REGION_TYPE_VSS] = NULL;
 	}
 
@@ -314,16 +314,17 @@ ftl_mngt_superblock_deinit(struct spdk_ftl_dev *dev, struct ftl_mngt_process *mn
 	struct ftl_layout *layout = &dev->layout;
 
 	if (layout->md[FTL_LAYOUT_REGION_TYPE_SB]) {
-		ftl_md_destroy(layout->md[FTL_LAYOUT_REGION_TYPE_SB]);
+		ftl_md_destroy(layout->md[FTL_LAYOUT_REGION_TYPE_SB],
+			       ftl_md_destroy_region_flags(dev, FTL_LAYOUT_REGION_TYPE_SB));
 		layout->md[FTL_LAYOUT_REGION_TYPE_SB] = NULL;
 	}
 
 	if (layout->md[FTL_LAYOUT_REGION_TYPE_SB_BASE]) {
-		ftl_md_destroy(layout->md[FTL_LAYOUT_REGION_TYPE_SB_BASE]);
+		ftl_md_destroy(layout->md[FTL_LAYOUT_REGION_TYPE_SB_BASE], 0);
 		layout->md[FTL_LAYOUT_REGION_TYPE_SB_BASE] = NULL;
 	}
 
-	ftl_md_destroy(dev->sb_shm_md);
+	ftl_md_destroy(dev->sb_shm_md, ftl_md_destroy_shm_flags(dev));
 	dev->sb_shm_md = NULL;
 	dev->sb_shm = NULL;
 

lib/ftl/mngt/ftl_mngt_misc.c

@@ -85,7 +85,7 @@ ftl_mngt_deinit_mem_pools(struct spdk_ftl_dev *dev, struct ftl_mngt_process *mng
 	}
 
 	if (dev->p2l_pool_md) {
-		ftl_md_destroy(dev->p2l_pool_md);
+		ftl_md_destroy(dev->p2l_pool_md, ftl_md_destroy_shm_flags(dev));
 		dev->p2l_pool_md = NULL;
 	}
 

lib/ftl/spdk_ftl.map

@@ -15,6 +15,7 @@
 	spdk_ftl_io_size;
 	spdk_ftl_readv;
 	spdk_ftl_writev;
+	spdk_ftl_dev_set_fast_shutdown;
 
 	local: *;
 };

lib/ftl/utils/ftl_conf.c

@@ -23,6 +23,7 @@ static const struct spdk_ftl_conf g_default_conf = {
 	.nv_cache = {
 		.chunk_compaction_threshold = 80,
 	},
+	.fast_shutdown = true,
 };
 
 void

lib/ftl/utils/ftl_md.c

@@ -229,7 +229,7 @@ err_shm:
 }
 
 static void
-ftl_md_destroy_shm(struct ftl_md *md)
+ftl_md_destroy_shm(struct ftl_md *md, int flags)
 {
 	if (!md->data) {
 		return;
@@ -253,6 +253,11 @@ ftl_md_destroy_shm(struct ftl_md *md)
 	md->data = NULL;
 	md->vss_data = NULL;
 
+	/* If specified, keep the object in SHM */
+	if (flags & FTL_MD_DESTROY_SHM_KEEP) {
+		return;
+	}
+
 	/* Otherwise destroy/unlink the object */
 	assert(md->name[0] != 0 && md->shm_unlink != NULL);
 	md->shm_unlink(md->name);
@@ -306,7 +311,7 @@ struct ftl_md *ftl_md_create(struct spdk_ftl_dev *dev, uint64_t blocks,
 
 	return md;
 err:
-	ftl_md_destroy(md);
+	ftl_md_destroy(md, ftl_md_destroy_region_flags(dev, region->type));
 	return NULL;
 }
 
@@ -327,13 +332,13 @@ ftl_md_unlink(struct spdk_ftl_dev *dev, const char *name, int flags)
 }
 
 void
-ftl_md_destroy(struct ftl_md *md)
+ftl_md_destroy(struct ftl_md *md, int flags)
 {
 	if (!md) {
 		return;
 	}
 
-	ftl_md_free_buf(md);
+	ftl_md_free_buf(md, flags);
 
 	spdk_free(md->entry_vss_dma_buf);
 
@@ -342,16 +347,17 @@ ftl_md_destroy(struct ftl_md *md)
 }
 
 void
-ftl_md_free_buf(struct ftl_md *md)
+ftl_md_free_buf(struct ftl_md *md, int flags)
 {
 	if (!md) {
 		return;
 	}
 
 	if (md->shm_fd < 0) {
+		assert(flags == 0);
 		ftl_md_destroy_heap(md);
 	} else {
-		ftl_md_destroy_shm(md);
+		ftl_md_destroy_shm(md, flags);
 	}
 }
 
@@ -1124,6 +1130,24 @@ ftl_md_create_region_flags(struct spdk_ftl_dev *dev, int region_type)
 	return flags;
 }
 
+int
+ftl_md_destroy_region_flags(struct spdk_ftl_dev *dev, int region_type)
+{
+	switch (region_type) {
+	case FTL_LAYOUT_REGION_TYPE_SB:
+	case FTL_LAYOUT_REGION_TYPE_BAND_MD:
+	case FTL_LAYOUT_REGION_TYPE_NVC_MD:
+		if (dev->conf.fast_shutdown) {
+			return FTL_MD_DESTROY_SHM_KEEP;
+		}
+		break;
+
+	default:
+		break;
+	}
+	return 0;
+}
+
 int
 ftl_md_create_shm_flags(struct spdk_ftl_dev *dev)
 {
@@ -1131,3 +1155,9 @@ ftl_md_create_shm_flags(struct spdk_ftl_dev *dev)
 
 	return flags;
 }
+
+int
+ftl_md_destroy_shm_flags(struct spdk_ftl_dev *dev)
+{
+	return (dev->conf.fast_shutdown) ? FTL_MD_DESTROY_SHM_KEEP : 0;
+}

lib/ftl/utils/ftl_md.h

@@ -175,19 +175,29 @@ struct ftl_md *ftl_md_create(struct spdk_ftl_dev *dev, uint64_t blocks,
  */
 int ftl_md_unlink(struct spdk_ftl_dev *dev, const char *name, int flags);
 
+/**
+ *  FTL metadata destroy flags
+ */
+enum ftl_md_destroy_flags {
+	/** FTL metadata data buf will be kept in SHM */
+	FTL_MD_DESTROY_SHM_KEEP = 0x1,
+};
+
 /**
  * @brief Destroys metadata
  *
  * @param md Metadata to be destroyed
+ * @param flags Bit flags of type ftl_md_destroy_flags
  */
-void ftl_md_destroy(struct ftl_md *md);
+void ftl_md_destroy(struct ftl_md *md, int flags);
 
 /**
  * @brief Free the data buf associated with the metadata
  *
  * @param md Metadata object
+ * @param flags Bit flags of type ftl_md_destroy_flags
  */
-void ftl_md_free_buf(struct ftl_md *md);
+void ftl_md_free_buf(struct ftl_md *md, int flags);
 
 /**
  * @brief Sets the region of a device on which to perform IO when persisting,
@@ -329,13 +339,26 @@ uint64_t ftl_md_xfer_blocks(struct spdk_ftl_dev *dev);
  * 1. superblock upon SPDK_FTL_MODE_CREATE flag set,
  * 2. other regions if not in a fast startup mode.
  *
- * @param dev			The FTL device
+ * @param dev		The FTL device
  * @param region_type	MD region type
  *
  * @return MD creation flags
  */
 int ftl_md_create_region_flags(struct spdk_ftl_dev *dev, int region_type);
 
+/**
+ * @brief Return the md destroy flags for a given md region type
+ *
+ * In a fast shutdown mode, returns FTL_MD_DESTROY_SHM_KEEP.
+ * Otherwise the SHM is unlinked.
+ *
+ * @param dev		The FTL device
+ * @param region_type	MD region type
+ *
+ * #return MD destroy flags
+ */
+int ftl_md_destroy_region_flags(struct spdk_ftl_dev *dev, int region_type);
+
 /**
  * @brief Return the SHM-backed md creation flags
  *
@@ -348,4 +371,15 @@ int ftl_md_create_region_flags(struct spdk_ftl_dev *dev, int region_type);
  */
 int ftl_md_create_shm_flags(struct spdk_ftl_dev *dev);
 
+/**
+ * @brief Return the md destroy flags
+ *
+ * In a fast shutdown mode, returns FTL_MD_DESTROY_SHM_KEEP.
+ * Otherwise the SHM is unlinked.
+ *
+ * @param dev			The FTL device
+ *
+ * @return MD destroy flags
+ */
+int ftl_md_destroy_shm_flags(struct spdk_ftl_dev *dev);
 #endif /* FTL_MD_H */

module/bdev/ftl/bdev_ftl.c

@@ -213,6 +213,8 @@ bdev_ftl_write_config_json(struct spdk_bdev *bdev, struct spdk_json_write_ctx *w
 	spdk_uuid_fmt_lower(uuid, sizeof(uuid), &conf.uuid);
 	spdk_json_write_named_string(w, "uuid", uuid);
 
+	spdk_json_write_named_bool(w, "fast_shutdown", conf.fast_shutdown);
+
 	spdk_json_write_named_string(w, "base_bdev", conf.base_bdev);
 
 	if (conf.cache_bdev) {
@@ -331,6 +333,9 @@ bdev_ftl_create_cb(struct spdk_ftl_dev *dev, void *ctx, int status)
 
 error:
 	if (ftl_bdev->dev) {
+		/* Cleanup all FTL */
+		spdk_ftl_dev_set_fast_shutdown(ftl_bdev->dev, false);
+
 		/* FTL was created, but we have got an error, so we need to delete it */
 		spdk_ftl_dev_free(dev, bdev_ftl_create_err_cleanup_cb, ftl_bdev);
 	} else {
@@ -430,15 +435,47 @@ bdev_ftl_initialize(void)
 	return spdk_ftl_init();
 }
 
-void
+static void
-bdev_ftl_delete_bdev(const char *name, spdk_bdev_unregister_cb cb_fn, void *cb_arg)
+bdev_ftl_event_cb(enum spdk_bdev_event_type type, struct spdk_bdev *bdev, void *ctx)
 {
+}
+
+void
+bdev_ftl_delete_bdev(const char *name, bool fast_shutdown, spdk_bdev_unregister_cb cb_fn,
+		     void *cb_arg)
+{
+	struct spdk_bdev_desc	*ftl_bdev_desc;
+	struct spdk_bdev *bdev;
+	struct ftl_bdev *ftl;
 	int rc;
 
+	rc = spdk_bdev_open_ext(name, false, bdev_ftl_event_cb, NULL, &ftl_bdev_desc);
+
+	if (rc) {
+		goto not_found;
+	}
+
+	bdev = spdk_bdev_desc_get_bdev(ftl_bdev_desc);
+
+	if (bdev->module != &g_ftl_if) {
+		goto bdev_opened;
+	}
+
+	ftl = bdev->ctxt;
+	assert(ftl);
+	spdk_ftl_dev_set_fast_shutdown(ftl->dev, fast_shutdown);
+	spdk_bdev_close(ftl_bdev_desc);
+
 	rc = spdk_bdev_unregister_by_name(name, &g_ftl_if, cb_fn, cb_arg);
 	if (rc) {
 		cb_fn(cb_arg, rc);
 	}
+
+	return;
+bdev_opened:
+	spdk_bdev_close(ftl_bdev_desc);
+not_found:
+	cb_fn(cb_arg, -ENODEV);
 }
 
 static void

module/bdev/ftl/bdev_ftl.h

@@ -21,7 +21,8 @@ typedef void (*ftl_bdev_init_fn)(const struct ftl_bdev_info *, void *, int);
 typedef void (*ftl_bdev_thread_fn)(void *);
 
 int bdev_ftl_create_bdev(const struct spdk_ftl_conf *conf, ftl_bdev_init_fn cb, void *cb_arg);
-void bdev_ftl_delete_bdev(const char *name, spdk_bdev_unregister_cb cb_fn, void *cb_arg);
+void bdev_ftl_delete_bdev(const char *name, bool fast_shutdown, spdk_bdev_unregister_cb cb_fn,
+			  void *cb_arg);
 int bdev_ftl_defer_init(const struct spdk_ftl_conf *conf);
 
 #endif /* SPDK_BDEV_FTL_H */

module/bdev/ftl/bdev_ftl_rpc.c

@@ -41,6 +41,10 @@ static const struct spdk_json_object_decoder rpc_bdev_ftl_create_decoders[] = {
 		"core_mask", offsetof(struct spdk_ftl_conf, core_mask),
 		spdk_json_decode_string, true
 	},
+	{
+		"fast_shutdown", offsetof(struct spdk_ftl_conf, fast_shutdown),
+		spdk_json_decode_bool, true
+	},
 };
 
 static void
@@ -118,10 +122,15 @@ SPDK_RPC_REGISTER("bdev_ftl_load", rpc_bdev_ftl_load, SPDK_RPC_RUNTIME)
 
 struct rpc_delete_ftl {
 	char *name;
+	bool fast_shutdown;
 };
 
 static const struct spdk_json_object_decoder rpc_delete_ftl_decoders[] = {
 	{"name", offsetof(struct rpc_delete_ftl, name), spdk_json_decode_string},
+	{
+		"fast_shutdown", offsetof(struct rpc_delete_ftl, fast_shutdown),
+		spdk_json_decode_bool, true
+	},
 };
 
 static void
@@ -146,7 +155,7 @@ rpc_bdev_ftl_delete(struct spdk_jsonrpc_request *request,
 		goto invalid;
 	}
 
-	bdev_ftl_delete_bdev(attrs.name, rpc_bdev_ftl_delete_cb, request);
+	bdev_ftl_delete_bdev(attrs.name, attrs.fast_shutdown, rpc_bdev_ftl_delete_cb, request);
 invalid:
 	free(attrs.name);
 }

python/spdk/rpc/bdev.py

@@ -1378,7 +1378,7 @@ def bdev_ftl_load(client, name, base_bdev, **kwargs):
     return client.call('bdev_ftl_load', params)
 
 
-def bdev_ftl_unload(client, name):
+def bdev_ftl_unload(client, name, fast_shutdown):
     """Unload FTL bdev
 
     Args:
@@ -1389,13 +1389,14 @@ def bdev_ftl_unload(client, name):
     return client.call('bdev_ftl_unload', params)
 
 
-def bdev_ftl_delete(client, name):
+def bdev_ftl_delete(client, name, fast_shutdown):
     """Delete FTL bdev
 
     Args:
         name: name of the bdev
     """
-    params = {'name': name}
+    params = {'name': name,
+              'fast_shutdown': fast_shutdown}
 
     return client.call('bdev_ftl_delete', params)
 

scripts/rpc.py

@@ -2008,7 +2008,8 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
                                             uuid=args.uuid,
                                             cache=args.cache,
                                             overprovisioning=args.overprovisioning,
-                                            core_mask=args.core_mask))
+                                            core_mask=args.core_mask,
+                                            fast_shutdown=args.fast_shutdown))
 
     p = subparsers.add_parser('bdev_ftl_create', help='Add FTL bdev')
     p.add_argument('-b', '--name', help="Name of the bdev", required=True)
@@ -2022,6 +2023,7 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
                    ' to user (optional); default 20', type=int)
     p.add_argument('--core-mask', help='CPU core mask - which cores will be used for ftl core thread, '
                    'by default core thread will be set to the main application core (optional)')
+    p.add_argument('-f', '--fast-shutdown', help="Enable fast shutdown", action='store_true')
     p.set_defaults(func=bdev_ftl_create)
 
     def bdev_ftl_load(args):
@@ -2031,7 +2033,8 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
                                           uuid=args.uuid,
                                           cache=args.cache,
                                           overprovisioning=args.overprovisioning,
-                                          core_mask=args.core_mask))
+                                          core_mask=args.core_mask,
+                                          fast_shutdown=args.fast_shutdown))
 
     p = subparsers.add_parser('bdev_ftl_load', help='Load FTL bdev')
     p.add_argument('-b', '--name', help="Name of the bdev", required=True)
@@ -2044,6 +2047,7 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
                    ' to user (optional); default 20', type=int)
     p.add_argument('--core-mask', help='CPU core mask - which cores will be used for ftl core thread, '
                    'by default core thread will be set to the main application core (optional)')
+    p.add_argument('-f', '--fast-shutdown', help="Enable fast shutdown", action='store_true')
     p.set_defaults(func=bdev_ftl_load)
 
     def bdev_ftl_unload(args):
@@ -2051,13 +2055,15 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
 
     p = subparsers.add_parser('bdev_ftl_unload', help='Unload FTL bdev')
     p.add_argument('-b', '--name', help="Name of the bdev", required=True)
+    p.add_argument('-f', '--fast-shutdown', help="Fast shutdown", action='store_true')
     p.set_defaults(func=bdev_ftl_unload)
 
     def bdev_ftl_delete(args):
-        print_dict(rpc.bdev.bdev_ftl_delete(args.client, name=args.name))
+        print_dict(rpc.bdev.bdev_ftl_delete(args.client, name=args.name, fast_shutdown=args.fast_shutdown))
 
     p = subparsers.add_parser('bdev_ftl_delete', help='Delete FTL bdev')
     p.add_argument('-b', '--name', help="Name of the bdev", required=True)
+    p.add_argument('-f', '--fast-shutdown', help="Fast shutdown", action='store_true')
     p.set_defaults(func=bdev_ftl_delete)
 
     # vmd