dm vdo: add dmsetup message for returning configuration info

Add a new dmsetup message called config, which will return
useful configuration information for the vdo volume and
the uds index associated with it. The output is a YAML
string, and contains a version number to allow future
additions to the content.
Signed-off-by: Bruce Johnston <bjohnsto@redhat.com>
Signed-off-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

Documentation/admin-guide/device-mapper/vdo.rst

@@ -251,7 +251,12 @@ The messages are:
 		by the vdostats userspace program to interpret the output
 		buffer.
 
-        dump:
+	config:
+		Outputs useful vdo configuration information. Mostly used
+		by users who want to recreate a similar VDO volume and
+		want to know the creation configuration used.
+
+	dump:
 		Dumps many internal structures to the system log. This is
 		not always safe to run, so it should only be used to debug
 		a hung vdo. Optional parameters to specify structures to

drivers/md/dm-vdo/dm-vdo-target.c

@@ -1105,6 +1105,9 @@ static int vdo_message(struct dm_target *ti, unsigned int argc, char **argv,
 	if ((argc == 1) && (strcasecmp(argv[0], "stats") == 0)) {
 		vdo_write_stats(vdo, result_buffer, maxlen);
 		result = 1;
+	} else if ((argc == 1) && (strcasecmp(argv[0], "config") == 0)) {
+		vdo_write_config(vdo, &result_buffer, &maxlen);
+		result = 1;
 	} else {
 		result = vdo_status_to_errno(process_vdo_message(vdo, argc, argv));
 	}
@@ -2832,7 +2835,7 @@ static void vdo_resume(struct dm_target *ti)
 static struct target_type vdo_target_bio = {
 	.features = DM_TARGET_SINGLETON,
 	.name = "vdo",
-	.version = { 9, 0, 0 },
+	.version = { 9, 1, 0 },
 	.module = THIS_MODULE,
 	.ctr = vdo_ctr,
 	.dtr = vdo_dtr,

drivers/md/dm-vdo/message-stats.c

@@ -4,6 +4,7 @@
  */
 
 #include "dedupe.h"
+#include "indexer.h"
 #include "logger.h"
 #include "memory-alloc.h"
 #include "message-stats.h"
@@ -430,3 +431,50 @@ int vdo_write_stats(struct vdo *vdo, char *buf, unsigned int maxlen)
 	vdo_free(stats);
 	return VDO_SUCCESS;
 }
+
+static void write_index_memory(u32 mem, char **buf, unsigned int *maxlen)
+{
+	char *prefix = "memorySize : ";
+
+	/* Convert index memory to fractional value */
+	if (mem == (u32)UDS_MEMORY_CONFIG_256MB)
+		write_string(prefix, "0.25, ", NULL, buf, maxlen);
+	else if (mem == (u32)UDS_MEMORY_CONFIG_512MB)
+		write_string(prefix, "0.50, ", NULL, buf, maxlen);
+	else if (mem == (u32)UDS_MEMORY_CONFIG_768MB)
+		write_string(prefix, "0.75, ", NULL, buf, maxlen);
+	else
+		write_u32(prefix, mem, ", ", buf, maxlen);
+}
+
+static void write_index_config(struct index_config *config, char **buf,
+			       unsigned int *maxlen)
+{
+	write_string("index :  ", "{ ", NULL, buf, maxlen);
+	/* index mem size */
+	write_index_memory(config->mem, buf, maxlen);
+	/* whether the index is sparse or not */
+	write_bool("isSparse : ", config->sparse, ", ", buf, maxlen);
+	write_string(NULL, "}", ", ", buf, maxlen);
+}
+
+int vdo_write_config(struct vdo *vdo, char **buf, unsigned int *maxlen)
+{
+	struct vdo_config *config = &vdo->states.vdo.config;
+
+	write_string(NULL, "{ ", NULL, buf, maxlen);
+	/* version */
+	write_u32("version : ", 1, ", ", buf, maxlen);
+	/* physical size */
+	write_block_count_t("physicalSize : ", config->physical_blocks * VDO_BLOCK_SIZE, ", ",
+			    buf, maxlen);
+	/* logical size */
+	write_block_count_t("logicalSize : ", config->logical_blocks * VDO_BLOCK_SIZE, ", ",
+			    buf, maxlen);
+	/* slab size */
+	write_block_count_t("slabSize : ", config->slab_size, ", ", buf, maxlen);
+	/* index config */
+	write_index_config(&vdo->geometry.index_config, buf, maxlen);
+	write_string(NULL, "}", NULL, buf, maxlen);
+	return VDO_SUCCESS;
+}

drivers/md/dm-vdo/message-stats.h

@@ -8,6 +8,7 @@
 
 #include "types.h"
 
+int vdo_write_config(struct vdo *vdo, char **buf, unsigned int *maxlen);
 int vdo_write_stats(struct vdo *vdo, char *buf, unsigned int maxlen);
 
 #endif /* VDO_MESSAGE_STATS_H */