1 files changed, 34 insertions, 0 deletions
diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 94d73485454a..45404798ee8c 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -1814,3 +1814,37 @@ __cold void btrfs_dump_space_info_for_trans_abort(struct btrfs_fs_info *fs_info)
 	}
 	dump_global_block_rsv(fs_info);
 }
+
+/*
+ * Account the unused space of all the readonly block group in the space_info.
+ * takes mirrors into account.
+ */
+u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo)
+{
+	struct btrfs_block_group *block_group;
+	u64 free_bytes = 0;
+	int factor;
+
+	/* It's df, we don't care if it's racy */
+	if (list_empty(&sinfo->ro_bgs))
+		return 0;
+
+	spin_lock(&sinfo->lock);
+	list_for_each_entry(block_group, &sinfo->ro_bgs, ro_list) {
+		spin_lock(&block_group->lock);
+
+		if (!block_group->ro) {
+			spin_unlock(&block_group->lock);
+			continue;
+		}
+
+		factor = btrfs_bg_type_to_factor(block_group->flags);
+		free_bytes += (block_group->length -
+			       block_group->used) * factor;
+
+		spin_unlock(&block_group->lock);
+	}
+	spin_unlock(&sinfo->lock);
+
+	return free_bytes;
+}