Module disk_layout 

on-disk layout of the file system’s metadata structures.

This module defines the on-disk layout of the file system’s core metadata structures. These types represent raw disk-resident data such as the superblock, block/inode allocation bitmaps, and inode table. Each struct in this module is tightly packed and designed to match the exact binary layout used by the file system when persisting and loading from disk.

This module defines MetaData trait, and support MetaData::load method, allowing them to be generically loaded from a logical block address (LBA).

Examples of accessing metadata.

use crate::ffs::disk_layout::{MetaData, BlockBitmap};

let block_bitmap = BlockBitmap::load(ffs, lba)?; // read BlockPointsTo<BlockBitMap> from lba.
{ // READ
    let guard = block_bitmap.read(); // reading metadata does not requires transaction.
    assert!(guard.is_allocated(0));
}
{ // WRITE
    let tx = ffs.open_transaction(); // Open a new transaction. Only a single transaction can be existed.
    let mut guard = block_bitmap.write(&tx); // writing metadata requires transaction.
    guard.try_allocate(1);
    guard.submit(); // Submit the modified change to the transaction.
}

Structs

BlockBitmap

Represents the on-disk block allocation bitmap for the file system.

DirectoryBlock

Represents a block that contains multiple directory entries.

DirectoryBlockEntry

Represent a single directory entry within a directory block.

IndirectBlock

Represents an indirect block in the filesystem.

Inode

Represent a single inode within a inode array.

InodeArray

Represents a fixed-size array of inodes loaded from a block.

InodeBitmap

Represents the on-disk inode allocation bitmap for the file system.

JournalSb

Represents the on-disk metadata for the journal superblock.

JournalTxBegin

Represents a journal transaction header used to track modified blocks.

JournalTxEnd

Represents a journal transaction is ended.

SuperBlock

On-disk representation of the superblock of the Fast File System (FFS).