diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 6c2769044b55..53677ecb8c15 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -172,16 +172,6 @@
  *   thing with or without extra unallocated space.
  */
 
-u64 __pure btrfs_space_info_used(const struct btrfs_space_info *s_info,
-			  bool may_use_included)
-{
-	ASSERT(s_info);
-	return s_info->bytes_used + s_info->bytes_reserved +
-		s_info->bytes_pinned + s_info->bytes_readonly +
-		s_info->bytes_zone_unusable +
-		(may_use_included ? s_info->bytes_may_use : 0);
-}
-
 /*
  * after adding space to the filesystem, we need to clear the full flags
  * on all the space infos.
diff --git a/fs/btrfs/space-info.h b/fs/btrfs/space-info.h
index d97b0799649f..7e16d4c116c8 100644
--- a/fs/btrfs/space-info.h
+++ b/fs/btrfs/space-info.h
@@ -266,6 +266,17 @@ DECLARE_SPACE_INFO_UPDATE(bytes_may_use, "space_info");
 DECLARE_SPACE_INFO_UPDATE(bytes_pinned, "pinned");
 DECLARE_SPACE_INFO_UPDATE(bytes_zone_unusable, "zone_unusable");
 
+static inline u64 btrfs_space_info_used(const struct btrfs_space_info *s_info,
+					bool may_use_included)
+{
+	lockdep_assert_held(&s_info->lock);
+
+	return s_info->bytes_used + s_info->bytes_reserved +
+		s_info->bytes_pinned + s_info->bytes_readonly +
+		s_info->bytes_zone_unusable +
+		(may_use_included ? s_info->bytes_may_use : 0);
+}
+
 int btrfs_init_space_info(struct btrfs_fs_info *fs_info);
 void btrfs_add_bg_to_space_info(struct btrfs_fs_info *info,
 				struct btrfs_block_group *block_group);
@@ -273,8 +284,6 @@ void btrfs_update_space_info_chunk_size(struct btrfs_space_info *space_info,
 					u64 chunk_size);
 struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
 					       u64 flags);
-u64 __pure btrfs_space_info_used(const struct btrfs_space_info *s_info,
-			  bool may_use_included);
 void btrfs_clear_space_info_full(struct btrfs_fs_info *info);
 void btrfs_dump_space_info(struct btrfs_space_info *info, u64 bytes,
 			   bool dump_block_groups);