f2fs: fix to avoid overflow when left shifting page offset

We use following method to calculate size with current page index:
size = index << PAGE_SHIFT
If type of index has only 32-bits size, left shifting will incur overflow,
which makes result incorrect.

So let's cast index with 64-bits type to avoid such issue.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/recovery.c

@@ -428,8 +428,9 @@ retry_dn:
 		}
 
 		if (!file_keep_isize(inode) &&
-				(i_size_read(inode) <= (start << PAGE_SHIFT)))
-			f2fs_i_size_write(inode, (start + 1) << PAGE_SHIFT);
+			(i_size_read(inode) <= ((loff_t)start << PAGE_SHIFT)))
+			f2fs_i_size_write(inode,
+				(loff_t)(start + 1) << PAGE_SHIFT);
 
 		/*
 		 * dest is reserved block, invalidate src block