kernel : the relationship between mount and superblock

kernel : the relationship between mount and superblock

quoted from : professional linux kernel architecture by Wolfgang Mauerer page 550-552.

1. the platfrom for EACH mounted filesystem is an instance of the vfsmount strcuture

2. The mount structures themselves are not the only objects generated in memory when new filesystems are mounted.

3. he mount operation starts by reading a structure called superblock.

4. The read_super function pointer stored in the file_system_type objects returns an object of type super_block that represents a superblock in memory. It is generated with the help of the low-level implementation.

5. mount points because this is where filesystems are attached (mounted).

6. Each mounted filesystem has a local root directory that contains the system directories ( the source and libs directories in the case of a CD-ROM).

7. When a directory is mounted, the contents of the mount point are REPLACED with the relative root directory of the mounted filesystem. THe previous directory data disappear until the new directory is unmounted ( naturally, the data in the old filesystem remain unchanged but can no longer be accessed.)

8. mnt_mntpoint is the dentry structure of the mount point in the parent directory in which the filesystem was mounted; the relative root directory of the filesystem itself is stored in mnt_root.