Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
index 54d5898..777f61d 100644
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -57,7 +57,8 @@
 			  u64 start_off, struct btrfs_path *path,
 			  struct btrfs_inode_extref **ret_extref,
 			  u64 *found_off);
-int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr);
+int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr,
+		struct ulist *roots, struct ulist *tmp_ulist);
 
 int __init btrfs_prelim_ref_init(void);
 void __cold btrfs_prelim_ref_exit(void);