Module blockfs 

Block-based persistent filesystem (BlockFS)

A simple ext2-like filesystem with:

• Superblock with metadata
• Inode table for file/directory metadata
• Block allocation bitmap
• Data blocks for file content

Structs

BlockBitmap

Block allocation bitmap

BlockFs

BlockFS filesystem

BlockFsInner

Internal BlockFS state

BlockFsNode

BlockFS node implementation

DiskDirEntry

On-disk directory entry (ext2-style variable-length record)

DiskInode

On-disk inode structure

Superblock

Superblock structure

VirtioBlockBackend

Adapter that wraps the global virtio-blk device as a DiskBackend.

Constants

BLOCKFS_MAGIC

Magic number for BlockFS

BLOCK_SIZE

Block size (4KB)

DIRECT_BLOCKS

Number of direct block pointers in a DiskInode

DIRECT_MAX_BLOCKS

Maximum file size addressable via direct blocks only: 12 * 4KB = 48KB

DIR_ENTRY_HEADER_SIZE

Size of the fixed header in a DiskDirEntry (inode + rec_len + name_len + file_type)

DOUBLE_INDIRECT_MAX_BLOCKS

Maximum file size addressable via direct + single + double indirect: 12 + 1024 + 1024*1024 = 1_049_612 blocks = ~4GB

MAX_FILENAME_LEN

Maximum filename length

PTRS_PER_BLOCK

Number of block pointers that fit in one indirect block (4096 / 4 = 1024)

SINGLE_INDIRECT_MAX_BLOCKS

Maximum file size addressable via direct + single indirect: 12 + 1024 = 1036 blocks = ~4MB

Traits

DiskBackend

Trait for a block-level disk backend that BlockFS can sync to.

Functions

attach_virtio_backend

Try to attach the virtio-blk device as a disk backend for the given BlockFS instance. Returns true if a device was found and attached.

init

Initialize BlockFS