btrfs: make functions static when possible

Signed-off-by: David Sterba <dsterba@suse.cz>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index c60197b..a36c87db 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -74,8 +74,8 @@
  * retake all the spinlocks in the path.  You can safely use NULL
  * for held
  */
-noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
-					struct extent_buffer *held)
+static noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
+					       struct extent_buffer *held)
 {
 	int i;
 
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index cd52f7f..7cdce82 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -94,7 +94,7 @@
 	return (cache->flags & bits) == bits;
 }
 
-void btrfs_get_block_group(struct btrfs_block_group_cache *cache)
+static void btrfs_get_block_group(struct btrfs_block_group_cache *cache)
 {
 	atomic_inc(&cache->count);
 }
@@ -3651,8 +3651,8 @@
 	spin_unlock(&block_rsv->lock);
 }
 
-void block_rsv_release_bytes(struct btrfs_block_rsv *block_rsv,
-			     struct btrfs_block_rsv *dest, u64 num_bytes)
+static void block_rsv_release_bytes(struct btrfs_block_rsv *block_rsv,
+				    struct btrfs_block_rsv *dest, u64 num_bytes)
 {
 	struct btrfs_space_info *space_info = block_rsv->space_info;
 
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 9e69c6b..d06abe2 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1455,8 +1455,8 @@
 	return ret;
 }
 
-bool try_merge_free_space(struct btrfs_block_group_cache *block_group,
-			  struct btrfs_free_space *info, bool update_stat)
+static bool try_merge_free_space(struct btrfs_block_group_cache *block_group,
+				 struct btrfs_free_space *info, bool update_stat)
 {
 	struct btrfs_free_space *left_info;
 	struct btrfs_free_space *right_info;