btrfs: zoned: factor out single bg handling from btrfs_load_block_group_zone_info

Split the code handling a type single block group from
btrfs_load_block_group_zone_info to make the code more readable.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/zoned.c

@@ -1374,6 +1374,24 @@ static int btrfs_load_zone_info(struct btrfs_fs_info *fs_info, int zone_idx,
 	return 0;
 }
 
+static int btrfs_load_block_group_single(struct btrfs_block_group *bg,
+					 struct zone_info *info,
+					 unsigned long *active)
+{
+	if (info->alloc_offset == WP_MISSING_DEV) {
+		btrfs_err(bg->fs_info,
+			"zoned: cannot recover write pointer for zone %llu",
+			info->physical);
+		return -EIO;
+	}
+
+	bg->alloc_offset = info->alloc_offset;
+	bg->zone_capacity = info->capacity;
+	if (test_bit(0, active))
+		set_bit(BLOCK_GROUP_FLAG_ZONE_IS_ACTIVE, &bg->runtime_flags);
+	return 0;
+}
+
 int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache, bool new)
 {
 	struct btrfs_fs_info *fs_info = cache->fs_info;
@@ -1460,17 +1478,7 @@ int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache, bool new)
 
 	switch (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
 	case 0: /* single */
-		if (zone_info[0].alloc_offset == WP_MISSING_DEV) {
-			btrfs_err(fs_info,
-			"zoned: cannot recover write pointer for zone %llu",
-				zone_info[0].physical);
-			ret = -EIO;
-			goto out;
-		}
-		cache->alloc_offset = zone_info[0].alloc_offset;
-		cache->zone_capacity = zone_info[0].capacity;
-		if (test_bit(0, active))
-			set_bit(BLOCK_GROUP_FLAG_ZONE_IS_ACTIVE, &cache->runtime_flags);
+		ret = btrfs_load_block_group_single(cache, &zone_info[0], active);
 		break;
 	case BTRFS_BLOCK_GROUP_DUP:
 		if (map->type & BTRFS_BLOCK_GROUP_DATA) {