Extent-based File System

Introduction

An extent is a contiguous set of blocks allocated to a file, and is defined by the starting block number and the number of blocks in the extent. Each file or directory in our file system could have at most 512 extents.

Functionalities

• formatting the disk image (mkfs)
• creating and deleting directories (mkdir, rmdir)
• creating and deleting files (creat, unlink)
• writing data to files and reading data from files (read, write)
• displaying metadata about a file or directory (stat)

Potential Problems

We have not test complicate cases yet, so there may be errors when executing commands in complicate cases. We are especially uncertain about the read/write operations.

Testing

There is a shell script called runit.sh that demonstrates some functionality of this file system.