bdev/compress: add RPC to list orphaned comp bdevs

The previous patch in this series introduced the notion of an
orphan comp bdev which is available only for deletion due to
a missing PMEM file.  This RPC allows applications to list
orphaned comp bdevs as they will not show up with get_bdevs
because they are not registered bdevs.

Signed-off-by: paul luse <paul.e.luse@intel.com>
Change-Id: I431f9cdebd4e5ae6068308639cb41d6c52f7309b
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/465812
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

CHANGELOG.md

@@ -33,6 +33,12 @@ connections is moving to a more dynamic model.
 The `bdev_delay_update_latency` has been added to allow users to update
 a latency value for a given delay bdev.
 
+### compress bdev
+
+A new RPC `bdev_compress_get_orphans` has been added to list compress bdevs
+that were not loaded due to a missing pm metadata file. In this state they
+can only be deleted.
+
 ## v19.07:
 
 ### ftl

doc/bdev.md

@@ -172,6 +172,12 @@ compression vbdev will not be available.
 
 `rpc.py bdev_compress_delete COMP_LVS/myLvol`
 
+To list compression volumes that are only available for deletion because their PMEM file
+was missing use the following. The name parameter is optional and if not included will list
+all volumes, if used it will return the name or an error that the device does not exist.
+
+`rpc.py bdev_compress_get_orphans --name COMP_Nvme0n1`
+
 # Crypto Virtual Bdev Module {#bdev_config_crypto}
 
 The crypto virtual bdev module can be configured to provide at rest data encryption

lib/bdev/compress/vbdev_compress.c

@@ -883,6 +883,45 @@ delete_vol_unload_cb(void *cb_arg, int reduce_errno)
 	}
 }
 
+const char *
+compress_get_name(const struct vbdev_compress *comp_bdev)
+{
+	return comp_bdev->comp_bdev.name;
+}
+
+struct vbdev_compress *
+compress_bdev_first(void)
+{
+	struct vbdev_compress *comp_bdev;
+
+	comp_bdev = TAILQ_FIRST(&g_vbdev_comp);
+
+	return comp_bdev;
+}
+
+struct vbdev_compress *
+compress_bdev_next(struct vbdev_compress *prev)
+{
+	struct vbdev_compress *comp_bdev;
+
+	comp_bdev = TAILQ_NEXT(prev, link);
+
+	return comp_bdev;
+}
+
+bool
+compress_has_orphan(const char *name)
+{
+	struct vbdev_compress *comp_bdev;
+
+	TAILQ_FOREACH(comp_bdev, &g_vbdev_comp, link) {
+		if (comp_bdev->orphaned && strcmp(name, comp_bdev->comp_bdev.name) == 0) {
+			return true;
+		}
+	}
+	return false;
+}
+
 /* Called after we've unregistered following a hot remove callback.
  * Our finish entry point will be called next.
  */

lib/bdev/compress/vbdev_compress.h

@@ -38,6 +38,37 @@
 
 #include "spdk/bdev.h"
 
+/**
+ * Get the first compression bdev.
+ *
+ * \return the first compression bdev.
+ */
+struct vbdev_compress *compress_bdev_first(void);
+
+/**
+ * Get the next compression bdev.
+ *
+ * \param prev previous compression bdev.
+ * \return the next compression bdev.
+ */
+struct vbdev_compress *compress_bdev_next(struct vbdev_compress *prev);
+
+/**
+ * Test to see if a compression bdev orphan exists.
+ *
+ * \param name The name of the compression bdev.
+ * \return true if found, false if not.
+ */
+bool compress_has_orphan(const char *name);
+
+/**
+ * Get the name of a compression bdev.
+ *
+ * \param comp_bdev The compression bdev.
+ * \return the name of the compression bdev.
+ */
+const char *compress_get_name(const struct vbdev_compress *comp_bdev);
+
 enum compress_pmd {
 	COMPRESS_PMD_AUTO = 0,
 	COMPRESS_PMD_QAT_ONLY,

lib/bdev/compress/vbdev_compress_rpc.c

@@ -37,6 +37,67 @@
 #include "spdk/string.h"
 #include "spdk_internal/log.h"
 
+struct rpc_bdev_compress_get_orphans {
+	char *name;
+};
+
+static void
+free_rpc_bdev_compress_get_orphans(struct rpc_bdev_compress_get_orphans *r)
+{
+	free(r->name);
+}
+
+static const struct spdk_json_object_decoder rpc_bdev_compress_get_orphans_decoders[] = {
+	{"name", offsetof(struct rpc_bdev_compress_get_orphans, name), spdk_json_decode_string, true},
+};
+
+static void
+spdk_rpc_bdev_compress_get_orphans(struct spdk_jsonrpc_request *request,
+				   const struct spdk_json_val *params)
+{
+	struct rpc_bdev_compress_get_orphans req = {};
+	struct spdk_json_write_ctx *w;
+	struct vbdev_compress *comp_bdev;
+	bool found = false;
+
+
+	if (params && spdk_json_decode_object(params, rpc_bdev_compress_get_orphans_decoders,
+					      SPDK_COUNTOF(rpc_bdev_compress_get_orphans_decoders),
+					      &req)) {
+		SPDK_ERRLOG("spdk_json_decode_object failed\n");
+		spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INTERNAL_ERROR,
+						 "spdk_json_decode_object failed");
+		free_rpc_bdev_compress_get_orphans(&req);
+		return;
+	}
+
+	if (req.name) {
+		if (compress_has_orphan(req.name) == false) {
+			spdk_jsonrpc_send_error_response(request, -ENODEV, spdk_strerror(ENODEV));
+			free_rpc_bdev_compress_get_orphans(&req);
+			return;
+		}
+		found = true;
+	}
+
+	w = spdk_jsonrpc_begin_result(request);
+	spdk_json_write_array_begin(w);
+	if (found) {
+		spdk_json_write_string(w, req.name);
+	} else {
+		for (comp_bdev = compress_bdev_first(); comp_bdev != NULL;
+		     comp_bdev = compress_bdev_next(comp_bdev)) {
+			if (compress_has_orphan(compress_get_name(comp_bdev))) {
+				spdk_json_write_string(w, compress_get_name(comp_bdev));
+			}
+		}
+	}
+	spdk_json_write_array_end(w);
+	spdk_jsonrpc_end_result(request, w);
+	free_rpc_bdev_compress_get_orphans(&req);
+}
+SPDK_RPC_REGISTER("bdev_compress_get_orphans", spdk_rpc_bdev_compress_get_orphans, SPDK_RPC_RUNTIME)
+
 struct rpc_set_compress_pmd {
 	enum compress_pmd pmd;
 };

scripts/rpc.py

@@ -161,6 +161,14 @@ if __name__ == "__main__":
     p.add_argument('-p', '--pmd', type=int, help='0 = auto-select, 1= QAT only, 2 = ISAL only')
     p.set_defaults(func=set_compress_pmd)
 
+    def bdev_compress_get_orphans(args):
+        print_dict(rpc.bdev.bdev_compress_get_orphans(args.client,
+                                                      name=args.name))
+    p = subparsers.add_parser(
+        'bdev_compress_get_orphans', help='Display list of orphaned compress bdevs.')
+    p.add_argument('-b', '--name', help="Name of a comp bdev. Example: COMP_Nvme0n1", required=False)
+    p.set_defaults(func=bdev_compress_get_orphans)
+
     def bdev_crypto_create(args):
         print_json(rpc.bdev.bdev_crypto_create(args.client,
                                                base_bdev_name=args.base_bdev_name,

scripts/rpc/bdev.py

@@ -56,6 +56,21 @@ def set_compress_pmd(client, pmd):
     return client.call('set_compress_pmd', params)
 
 
+def bdev_compress_get_orphans(client, name=None):
+    """Get a list of comp bdevs that do not have a pmem file (aka orphaned).
+
+    Args:
+        name: comp bdev name to query (optional; if omitted, query all comp bdevs)
+
+    Returns:
+        List of comp bdev names.
+    """
+    params = {}
+    if name:
+        params['name'] = name
+    return client.call('bdev_compress_get_orphans', params)
+
+
 @deprecated_alias('construct_crypto_bdev')
 def bdev_crypto_create(client, base_bdev_name, name, crypto_pmd, key):
     """Construct a crypto virtual block device.