dm zoned: convert to xarray

The zones array is getting really large, and large arrays tend to
wreak havoc with the CPU caches.  So convert it to xarray to become
more cache friendly.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com> # fix leak in dmz_insert
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-zoned-metadata.c

@@ -172,7 +172,7 @@ struct dmz_metadata {
 	unsigned int		nr_chunks;
 
 	/* Zone information array */
-	struct dm_zone		*zones;
+	struct xarray		zones;
 
 	struct dmz_sb		sb[3];
 	unsigned int		mblk_primary;
@@ -327,6 +327,32 @@ unsigned int dmz_nr_unmap_seq_zones(struct dmz_metadata *zmd)
 	return atomic_read(&zmd->unmap_nr_seq);
 }
 
+static struct dm_zone *dmz_get(struct dmz_metadata *zmd, unsigned int zone_id)
+{
+	return xa_load(&zmd->zones, zone_id);
+}
+
+static struct dm_zone *dmz_insert(struct dmz_metadata *zmd,
+				  unsigned int zone_id)
+{
+	struct dm_zone *zone = kzalloc(sizeof(struct dm_zone), GFP_KERNEL);
+
+	if (!zone)
+		return ERR_PTR(-ENOMEM);
+
+	if (xa_insert(&zmd->zones, zone_id, zone, GFP_KERNEL)) {
+		kfree(zone);
+		return ERR_PTR(-EBUSY);
+	}
+
+	INIT_LIST_HEAD(&zone->link);
+	atomic_set(&zone->refcount, 0);
+	zone->id = zone_id;
+	zone->chunk = DMZ_MAP_UNMAPPED;
+
+	return zone;
+}
+
 const char *dmz_metadata_label(struct dmz_metadata *zmd)
 {
 	return (const char *)zmd->label;
@@ -1122,6 +1148,7 @@ static int dmz_lookup_secondary_sb(struct dmz_metadata *zmd)
 {
 	unsigned int zone_nr_blocks = zmd->zone_nr_blocks;
 	struct dmz_mblock *mblk;
+	unsigned int zone_id = zmd->sb[0].zone->id;
 	int i;
 
 	/* Allocate a block */
@@ -1134,16 +1161,15 @@ static int dmz_lookup_secondary_sb(struct dmz_metadata *zmd)
 
 	/* Bad first super block: search for the second one */
 	zmd->sb[1].block = zmd->sb[0].block + zone_nr_blocks;
-	zmd->sb[1].zone = zmd->sb[0].zone + 1;
+	zmd->sb[1].zone = dmz_get(zmd, zone_id + 1);
 	zmd->sb[1].dev = zmd->sb[0].dev;
-	for (i = 0; i < zmd->nr_rnd_zones - 1; i++) {
+	for (i = 1; i < zmd->nr_rnd_zones; i++) {
 		if (dmz_read_sb(zmd, 1) != 0)
 			break;
-		if (le32_to_cpu(zmd->sb[1].sb->magic) == DMZ_MAGIC) {
-			zmd->sb[1].zone += i;
+		if (le32_to_cpu(zmd->sb[1].sb->magic) == DMZ_MAGIC)
 			return 0;
-		}
 		zmd->sb[1].block += zone_nr_blocks;
+		zmd->sb[1].zone = dmz_get(zmd, zone_id + i);
 	}
 
 	dmz_free_mblock(zmd, mblk);
@@ -1259,8 +1285,12 @@ static int dmz_load_sb(struct dmz_metadata *zmd)
 	/* Read and check secondary super block */
 	if (ret == 0) {
 		sb_good[0] = true;
-		if (!zmd->sb[1].zone)
-			zmd->sb[1].zone = zmd->sb[0].zone + zmd->nr_meta_zones;
+		if (!zmd->sb[1].zone) {
+			unsigned int zone_id =
+				zmd->sb[0].zone->id + zmd->nr_meta_zones;
+
+			zmd->sb[1].zone = dmz_get(zmd, zone_id);
+		}
 		zmd->sb[1].block = dmz_start_block(zmd, zmd->sb[1].zone);
 		zmd->sb[1].dev = zmd->sb[0].dev;
 		ret = dmz_get_sb(zmd, 1);
@@ -1341,7 +1371,11 @@ static int dmz_init_zone(struct blk_zone *blkz, unsigned int num, void *data)
 	struct dmz_metadata *zmd = data;
 	struct dmz_dev *dev = zmd->nr_devs > 1 ? &zmd->dev[1] : &zmd->dev[0];
 	int idx = num + dev->zone_offset;
-	struct dm_zone *zone = &zmd->zones[idx];
+	struct dm_zone *zone;
+
+	zone = dmz_insert(zmd, idx);
+	if (IS_ERR(zone))
+		return PTR_ERR(zone);
 
 	if (blkz->len != zmd->zone_nr_sectors) {
 		if (zmd->sb_version > 1) {
@@ -1353,11 +1387,6 @@ static int dmz_init_zone(struct blk_zone *blkz, unsigned int num, void *data)
 		return -ENXIO;
 	}
 
-	INIT_LIST_HEAD(&zone->link);
-	atomic_set(&zone->refcount, 0);
-	zone->id = idx;
-	zone->chunk = DMZ_MAP_UNMAPPED;
-
 	switch (blkz->type) {
 	case BLK_ZONE_TYPE_CONVENTIONAL:
 		set_bit(DMZ_RND, &zone->flags);
@@ -1397,18 +1426,17 @@ static int dmz_init_zone(struct blk_zone *blkz, unsigned int num, void *data)
 	return 0;
 }
 
-static void dmz_emulate_zones(struct dmz_metadata *zmd, struct dmz_dev *dev)
+static int dmz_emulate_zones(struct dmz_metadata *zmd, struct dmz_dev *dev)
 {
 	int idx;
 	sector_t zone_offset = 0;
 
 	for(idx = 0; idx < dev->nr_zones; idx++) {
-		struct dm_zone *zone = &zmd->zones[idx];
+		struct dm_zone *zone;
 
-		INIT_LIST_HEAD(&zone->link);
-		atomic_set(&zone->refcount, 0);
-		zone->id = idx;
-		zone->chunk = DMZ_MAP_UNMAPPED;
+		zone = dmz_insert(zmd, idx);
+		if (IS_ERR(zone))
+			return PTR_ERR(zone);
 		set_bit(DMZ_CACHE, &zone->flags);
 		zone->wp_block = 0;
 		zmd->nr_cache_zones++;
@@ -1420,6 +1448,7 @@ static void dmz_emulate_zones(struct dmz_metadata *zmd, struct dmz_dev *dev)
 		}
 		zone_offset += zmd->zone_nr_sectors;
 	}
+	return 0;
 }
 
 /*
@@ -1427,8 +1456,15 @@ static void dmz_emulate_zones(struct dmz_metadata *zmd, struct dmz_dev *dev)
  */
 static void dmz_drop_zones(struct dmz_metadata *zmd)
 {
-	kfree(zmd->zones);
-	zmd->zones = NULL;
+	int idx;
+
+	for(idx = 0; idx < zmd->nr_zones; idx++) {
+		struct dm_zone *zone = xa_load(&zmd->zones, idx);
+
+		kfree(zone);
+		xa_erase(&zmd->zones, idx);
+	}
+	xa_destroy(&zmd->zones);
 }
 
 /*
@@ -1460,20 +1496,25 @@ static int dmz_init_zones(struct dmz_metadata *zmd)
 		DMERR("(%s): No zones found", zmd->devname);
 		return -ENXIO;
 	}
-	zmd->zones = kcalloc(zmd->nr_zones, sizeof(struct dm_zone), GFP_KERNEL);
-	if (!zmd->zones)
-		return -ENOMEM;
+	xa_init(&zmd->zones);
 
 	DMDEBUG("(%s): Using %zu B for zone information",
 		zmd->devname, sizeof(struct dm_zone) * zmd->nr_zones);
 
 	if (zmd->nr_devs > 1) {
-		dmz_emulate_zones(zmd, &zmd->dev[0]);
+		ret = dmz_emulate_zones(zmd, &zmd->dev[0]);
+		if (ret < 0) {
+			DMDEBUG("(%s): Failed to emulate zones, error %d",
+				zmd->devname, ret);
+			dmz_drop_zones(zmd);
+			return ret;
+		}
+
 		/*
 		 * Primary superblock zone is always at zone 0 when multiple
 		 * drives are present.
 		 */
-		zmd->sb[0].zone = &zmd->zones[0];
+		zmd->sb[0].zone = dmz_get(zmd, 0);
 
 		zoned_dev = &zmd->dev[1];
 	}
@@ -1576,11 +1617,6 @@ static int dmz_handle_seq_write_err(struct dmz_metadata *zmd,
 	return 0;
 }
 
-static struct dm_zone *dmz_get(struct dmz_metadata *zmd, unsigned int zone_id)
-{
-	return &zmd->zones[zone_id];
-}
-
 /*
  * Reset a zone write pointer.
  */
@@ -1662,6 +1698,11 @@ static int dmz_load_mapping(struct dmz_metadata *zmd)
 		}
 
 		dzone = dmz_get(zmd, dzone_id);
+		if (!dzone) {
+			dmz_zmd_err(zmd, "Chunk %u mapping: data zone %u not present",
+				    chunk, dzone_id);
+			return -EIO;
+		}
 		set_bit(DMZ_DATA, &dzone->flags);
 		dzone->chunk = chunk;
 		dmz_get_zone_weight(zmd, dzone);
@@ -1685,6 +1726,11 @@ static int dmz_load_mapping(struct dmz_metadata *zmd)
 		}
 
 		bzone = dmz_get(zmd, bzone_id);
+		if (!bzone) {
+			dmz_zmd_err(zmd, "Chunk %u mapping: buffer zone %u not present",
+				    chunk, bzone_id);
+			return -EIO;
+		}
 		if (!dmz_is_rnd(bzone) && !dmz_is_cache(bzone)) {
 			dmz_zmd_err(zmd, "Chunk %u mapping: invalid buffer zone %u",
 				    chunk, bzone_id);
@@ -1715,6 +1761,8 @@ static int dmz_load_mapping(struct dmz_metadata *zmd)
 	 */
 	for (i = 0; i < zmd->nr_zones; i++) {
 		dzone = dmz_get(zmd, i);
+		if (!dzone)
+			continue;
 		if (dmz_is_meta(dzone))
 			continue;
 		if (dmz_is_offline(dzone))
@@ -1978,6 +2026,10 @@ struct dm_zone *dmz_get_chunk_mapping(struct dmz_metadata *zmd, unsigned int chu
 	} else {
 		/* The chunk is already mapped: get the mapping zone */
 		dzone = dmz_get(zmd, dzone_id);
+		if (!dzone) {
+			dzone = ERR_PTR(-EIO);
+			goto out;
+		}
 		if (dzone->chunk != chunk) {
 			dzone = ERR_PTR(-EIO);
 			goto out;
@@ -2794,6 +2846,12 @@ int dmz_ctr_metadata(struct dmz_dev *dev, int num_dev,
 	/* Set metadata zones starting from sb_zone */
 	for (i = 0; i < zmd->nr_meta_zones << 1; i++) {
 		zone = dmz_get(zmd, zmd->sb[0].zone->id + i);
+		if (!zone) {
+			dmz_zmd_err(zmd,
+				    "metadata zone %u not present", i);
+			ret = -ENXIO;
+			goto err;
+		}
 		if (!dmz_is_rnd(zone) && !dmz_is_cache(zone)) {
 			dmz_zmd_err(zmd,
 				    "metadata zone %d is not random", i);