btrfs: zoned: move btrfs_free_excluded_extents out of btrfs_calc_zone_unusable

btrfs_free_excluded_extents() is not neccessary for
btrfs_calc_zone_unusable() and it makes btrfs_calc_zone_unusable()
difficult to reuse. Move it out and call btrfs_free_excluded_extents()
in proper context.
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NNaohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/block-group.c

@@ -2035,6 +2035,8 @@ static int read_one_block_group(struct btrfs_fs_info *info,
 	 */
 	if (btrfs_is_zoned(info)) {
 		btrfs_calc_zone_unusable(cache);
+		/* Should not have any excluded extents. Just in case, though. */
+		btrfs_free_excluded_extents(cache);
 	} else if (cache->length == cache->used) {
 		cache->last_byte_to_unpin = (u64)-1;
 		cache->cached = BTRFS_CACHE_FINISHED;

fs/btrfs/zoned.c

@@ -1273,9 +1273,6 @@ void btrfs_calc_zone_unusable(struct btrfs_block_group *cache)
 	cache->cached = BTRFS_CACHE_FINISHED;
 	cache->free_space_ctl->free_space = free;
 	cache->zone_unusable = unusable;
-
-	/* Should not have any excluded extents. Just in case, though */
-	btrfs_free_excluded_extents(cache);
 }
 
 void btrfs_redirty_list_add(struct btrfs_transaction *trans,