n Wed, Jan 17, 2018 at 9:05 AM, inventsekar <inventsekar@gmail.com> wrote:
Hi All, i have been reading Unix filesystem - evolution, design and implementation by Steve D. Pate
and it provides a simple file system source code for learning and playing with. On the header file, it defines the fs magic number as #define UX_MAGIC 0x58494e55
1. which means, will it assign this magic number to ALL files created on this sample fs? That can't be so. Otherwise, why we need to define a magic number?
There can be many different types of filesystems on a Linux computer; the magic number can be used to distinguish which type a particular filesystem is. If you look at usr/include/linux/magic.h you'll see, for example, #define EXT2_SUPER_MAGIC 0xEF53 and as an example of using that particular magic number, check out arch/blackfin/kernel/setup.c or fs/ext2/super.c. -- Jim