File Systems and Their Implementation

Introduction

• Goal: Create a simplified file system.
• Components: Super block, inodes, disk blocks, file allocation tables.

Super Block

• Meta information about the file system.
• Contains:
  • Number of inodes
  • Number of disk blocks
  • Size of the disk blocks

Inodes

• Represents files in the file system.
• Contains:
  • Size
  • Name

Disk Blocks

• Storage units for file data.
• Contains:
  • Next block number
  • Data (512 bytes)

Operations

Creating the File System

• Initialize super block, inodes, and disk blocks.
• Define global variables for managing the file system.
• Functions:
  • create(): Initializes the file system structures.
  • sync(): Writes the file system data to disk using fopen and fwrite.
  • mount(): Reads file system data from disk using fread.

File Management

Allocate File

• Finds an empty inode and disk block to store new file.
• Returns a file descriptor.

Set File Size

• Calculates the required number of disk blocks.
• Allocates or frees disk blocks as necessary.

Write Byte

• Calculates the block and offset based on position.
• Writes byte to specified position in the file.

Testing

• Tested creating, mounting, and syncing the file system.
• Verified allocation of inodes and disk blocks.
• Verified data writing to files.
• Implemented test scenarios by setting file sizes and writing data.

Future Work

• Implement deleting files.
• Implement reading bytes from files.
• Optimize using bitmap for inode and disk block management.

Notes on Coding Practices

• Includes using malloc for memory allocation.
• Usage of standard libraries: stdio.h, stdlib.h, string.h.
• Error checking not emphasized due to time constraints.
• Good habits mentioned: Always close a file after opening it.

Conclusion

• Basic functionality achieved: Creating, mounting, syncing file system, and writing data to files.
• Further operations like reading and deleting files can be implemented next.