dm zoned: add 'status' callback

Add callback to supply information for 'dmsetup status'
and 'dmsetup table'. The output for 'dmsetup status' is

0 <size> zoned <nr_zones> zones <nr_unmap_rnd>/<nr_rnd> random <nr_unmap_seq>/<nr_seq> sequential

where <nr_unmap_rnd> is the number of unmapped (ie free) random zones,
<nr_rnd> the total number of random zones, <nr_unmap_seq> the number
of unmapped sequential zones, and <nr_seq> the total number of
sequential zones.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Documentation/admin-guide/device-mapper/dm-zoned.rst

@@ -144,3 +144,19 @@ underlying zoned block device name. Ex::
 
 	echo "0 `blockdev --getsize ${dev}` zoned ${dev}" | \
 	dmsetup create dmz-`basename ${dev}`
+
+Information about the internal layout and current usage of the zones can
+be obtained with the 'status' callback from dmsetup:
+
+Ex::
+
+	dmsetup status /dev/dm-X
+
+will return a line
+
+	0 <size> zoned <nr_zones> zones <nr_unmap_rnd>/<nr_rnd> random <nr_unmap_seq>/<nr_seq> sequential
+
+where <nr_zones> is the total number of zones, <nr_unmap_rnd> is the number
+of unmapped (ie free) random zones, <nr_rnd> the total number of zones,
+<nr_unmap_seq> the number of unmapped sequential zones, and <nr_seq> the
+total number of sequential zones.

drivers/md/dm-zoned-metadata.c

@@ -202,6 +202,11 @@ sector_t dmz_start_block(struct dmz_metadata *zmd, struct dm_zone *zone)
 	return (sector_t)dmz_id(zmd, zone) << zmd->dev->zone_nr_blocks_shift;
 }
 
+unsigned int dmz_nr_zones(struct dmz_metadata *zmd)
+{
+	return zmd->dev->nr_zones;
+}
+
 unsigned int dmz_nr_chunks(struct dmz_metadata *zmd)
 {
 	return zmd->nr_chunks;
@@ -217,6 +222,16 @@ unsigned int dmz_nr_unmap_rnd_zones(struct dmz_metadata *zmd)
 	return atomic_read(&zmd->unmap_nr_rnd);
 }
 
+unsigned int dmz_nr_seq_zones(struct dmz_metadata *zmd)
+{
+	return zmd->nr_seq;
+}
+
+unsigned int dmz_nr_unmap_seq_zones(struct dmz_metadata *zmd)
+{
+	return atomic_read(&zmd->unmap_nr_seq);
+}
+
 /*
  * Lock/unlock mapping table.
  * The map lock also protects all the zone lists.

drivers/md/dm-zoned-target.c

@@ -965,6 +965,31 @@ static int dmz_iterate_devices(struct dm_target *ti,
 	return fn(ti, dmz->ddev, 0, capacity, data);
 }
 
+static void dmz_status(struct dm_target *ti, status_type_t type,
+		       unsigned int status_flags, char *result,
+		       unsigned int maxlen)
+{
+	struct dmz_target *dmz = ti->private;
+	ssize_t sz = 0;
+	char buf[BDEVNAME_SIZE];
+
+	switch (type) {
+	case STATUSTYPE_INFO:
+		DMEMIT("%u zones %u/%u random %u/%u sequential",
+		       dmz_nr_zones(dmz->metadata),
+		       dmz_nr_unmap_rnd_zones(dmz->metadata),
+		       dmz_nr_rnd_zones(dmz->metadata),
+		       dmz_nr_unmap_seq_zones(dmz->metadata),
+		       dmz_nr_seq_zones(dmz->metadata));
+		break;
+	case STATUSTYPE_TABLE:
+		format_dev_t(buf, dmz->dev->bdev->bd_dev);
+		DMEMIT("%s", buf);
+		break;
+	}
+	return;
+}
+
 static struct target_type dmz_type = {
 	.name		 = "zoned",
 	.version	 = {1, 1, 0},
@@ -978,6 +1003,7 @@ static struct target_type dmz_type = {
 	.postsuspend	 = dmz_suspend,
 	.resume		 = dmz_resume,
 	.iterate_devices = dmz_iterate_devices,
+	.status		 = dmz_status,
 };
 
 static int __init dmz_init(void)

drivers/md/dm-zoned.h

@@ -190,8 +190,11 @@ void dmz_free_zone(struct dmz_metadata *zmd, struct dm_zone *zone);
 void dmz_map_zone(struct dmz_metadata *zmd, struct dm_zone *zone,
 		  unsigned int chunk);
 void dmz_unmap_zone(struct dmz_metadata *zmd, struct dm_zone *zone);
+unsigned int dmz_nr_zones(struct dmz_metadata *zmd);
 unsigned int dmz_nr_rnd_zones(struct dmz_metadata *zmd);
 unsigned int dmz_nr_unmap_rnd_zones(struct dmz_metadata *zmd);
+unsigned int dmz_nr_seq_zones(struct dmz_metadata *zmd);
+unsigned int dmz_nr_unmap_seq_zones(struct dmz_metadata *zmd);
 
 /*
  * Activate a zone (increment its reference count).