Summary

This chapter began by looking at the structures and global variables that make up the common file model. The structures include the superblock, the inode, the dentry, and the file structures. We then looked at the structures associated with VFS. We saw how VFS works to support various filesystems.

We then looked at VFS-associated system calls, open and close, to illustrate how it all works together. We then traced the read() and write() user space call through VFS and throughout the twists and turns of the generic filesystem layer and the specific filesystem layer. Using the ext2 filesystem driver as an example of the specific filesystem layer, we showed how the kernel intertwines calls to specific filesystem driver functions and generic filesystem functions. This lead us to discuss the page cache, which is a section of memory that stores recently accessed pages from the block devices attached to the system.