bdev: add spdk_bdev_get_uuid() function

Add a generic way to get a UUID from a bdev.

For now, malloc and null bdevs generate random UUIDs, and no other bdev
types report a UUID.

Change-Id: Id9608c8c1b3ce3f1783e7f74bef96d44cd5d98a7
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-on: https://review.gerrithub.io/402177
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>

include/spdk/bdev.h

@@ -63,6 +63,7 @@ struct spdk_bdev_io;
 struct spdk_bdev_fn_table;
 struct spdk_io_channel;
 struct spdk_json_write_ctx;
+struct spdk_uuid;
 
 /** bdev status */
 enum spdk_bdev_status {
@@ -303,6 +304,17 @@ uint32_t spdk_bdev_get_optimal_io_boundary(const struct spdk_bdev *bdev);
  */
 bool spdk_bdev_has_write_cache(const struct spdk_bdev *bdev);
 
+/**
+ * Get a bdev's UUID.
+ *
+ * \param bdev Block device to query.
+ * \return Pointer to UUID.
+ *
+ * Not all bdevs will have a UUID; in this case, the returned UUID will be
+ * the nil UUID (all bytes zero).
+ */
+const struct spdk_uuid *spdk_bdev_get_uuid(const struct spdk_bdev *bdev);
+
 /**
  * Obtain an I/O channel for the block device opened by the specified
  * descriptor. I/O channels are bound to threads, so the resulting I/O

include/spdk_internal/bdev.h

@@ -45,6 +45,7 @@
 #include "spdk/queue.h"
 #include "spdk/scsi_spec.h"
 #include "spdk/io_channel.h"
+#include "spdk/uuid.h"
 
 /** \page block_backend_modules Block Device Backend Modules
  *
@@ -220,6 +221,13 @@ struct spdk_bdev {
 	 */
 	uint32_t optimal_io_boundary;
 
+	/**
+	 * UUID for this bdev.
+	 *
+	 * Fill with zeroes if no uuid is available.
+	 */
+	struct spdk_uuid uuid;
+
 	/**
 	 * Pointer to the bdev module that registered this bdev.
 	 */

lib/bdev/bdev.c

@@ -1192,6 +1192,12 @@ spdk_bdev_has_write_cache(const struct spdk_bdev *bdev)
 	return bdev->write_cache;
 }
 
+const struct spdk_uuid *
+spdk_bdev_get_uuid(const struct spdk_bdev *bdev)
+{
+	return &bdev->uuid;
+}
+
 int
 spdk_bdev_notify_blockcnt_change(struct spdk_bdev *bdev, uint64_t size)
 {

lib/bdev/malloc/bdev_malloc.c

@@ -396,6 +396,7 @@ struct spdk_bdev *create_malloc_disk(const char *name, uint64_t num_blocks, uint
 	mdisk->disk.write_cache = 1;
 	mdisk->disk.blocklen = block_size;
 	mdisk->disk.blockcnt = num_blocks;
+	spdk_uuid_generate(&mdisk->disk.uuid);
 
 	mdisk->disk.ctxt = mdisk;
 	mdisk->disk.fn_table = &malloc_fn_table;

lib/bdev/null/bdev_null.c

@@ -158,6 +158,7 @@ create_null_bdev(const char *name, uint64_t num_blocks, uint32_t block_size)
 	bdev->bdev.write_cache = 0;
 	bdev->bdev.blocklen = block_size;
 	bdev->bdev.blockcnt = num_blocks;
+	spdk_uuid_generate(&bdev->bdev.uuid);
 
 	bdev->bdev.ctxt = bdev;
 	bdev->bdev.fn_table = &null_fn_table;

lib/bdev/rpc/bdev_rpc.c

@@ -33,6 +33,7 @@
 
 #include "spdk/log.h"
 #include "spdk/rpc.h"
+#include "spdk/string.h"
 #include "spdk/util.h"
 
 #include "spdk_internal/bdev.h"
@@ -66,6 +67,13 @@ spdk_rpc_dump_bdev_info(struct spdk_json_write_ctx *w,
 	spdk_json_write_name(w, "num_blocks");
 	spdk_json_write_uint64(w, spdk_bdev_get_num_blocks(bdev));
 
+	if (!spdk_mem_all_zero(&bdev->uuid, sizeof(bdev->uuid))) {
+		char uuid_str[SPDK_UUID_STRING_LEN];
+
+		spdk_uuid_fmt_lower(uuid_str, sizeof(uuid_str), &bdev->uuid);
+		spdk_json_write_named_string(w, "uuid", uuid_str);
+	}
+
 	spdk_json_write_name(w, "claimed");
 	spdk_json_write_bool(w, (bdev->claim_module != NULL));