btrfs: use EXPORT_FOR_TESTS for conditionally exported functions

Several functions in BTRFS are only used inside the source file they are
declared if CONFIG_BTRFS_FS_RUN_SANITY_TESTS is not defined. However if
CONFIG_BTRFS_FS_RUN_SANITY_TESTS is defined these functions are shared
with the unit tests code.

Before the introduction of the EXPORT_FOR_TESTS macro, these functions
could not be declared as static and the compiler had a harder task when
optimizing and inlining them.

As we have EXPORT_FOR_TESTS now, use it where appropriate to support the
compiler.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 30bfeef..22b3442 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -522,10 +522,9 @@ int free_io_failure(struct extent_io_tree *failure_tree,
 		    struct extent_io_tree *io_tree,
 		    struct io_failure_record *rec);
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
-u64 btrfs_find_lock_delalloc_range(struct inode *inode,
-				      struct extent_io_tree *tree,
-				      struct page *locked_page, u64 *start,
-				      u64 *end);
+u64 find_lock_delalloc_range(struct inode *inode, struct extent_io_tree *tree,
+			     struct page *locked_page, u64 *start,
+			     u64 *end);
 #endif
 struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
 					       u64 start);