btrfs: make lock_extent static inline

One call less reduces stack usage, code slightly reduced as well.
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -1347,11 +1347,6 @@ int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 	return err;
 }
 
-int lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
-{
-	return lock_extent_bits(tree, start, end, NULL);
-}
-
 int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
 {
 	int err;

fs/btrfs/extent_io.h

@@ -199,9 +199,14 @@ int try_release_extent_mapping(struct extent_map_tree *map,
 			       struct extent_io_tree *tree, struct page *page,
 			       gfp_t mask);
 int try_release_extent_buffer(struct page *page);
-int lock_extent(struct extent_io_tree *tree, u64 start, u64 end);
 int lock_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 		     struct extent_state **cached);
+
+static inline int lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
+{
+	return lock_extent_bits(tree, start, end, NULL);
+}
+
 int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end);
 int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
 			  get_extent_t *get_extent, int mirror_num);