Which of the following statements are FALSE concerning the defragfs command？（）

• A、 The defragfs command should not be run against file systems and logical volumes that contain mostly transitory information， such as /tmp.
• B、 The defragfs command should not be run on a large JFS2 file system when running on a 32-bit kernel.
• C、 The defragfs command can improve file system performance by increasing the file system’s contiguous free space.
• D、 The defragfs command can only be run against file systems that are mounted with read-write permissions.