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pub mod block_device;
pub mod disk;
pub mod filesystem;
pub mod memory;
pub mod tests;
pub mod utils;
use indexmap::IndexMap;
use log::debug;
use lru::LruCache;
use std::collections::HashMap;
use std::ffi::OsString;
use std::num::NonZeroUsize;
use std::sync::atomic::AtomicU64;
use std::sync::Arc;
use std::time::Duration;
use crate::disk::block::{DirectoryEntry, InodeBlock, SuperBlock};
use crate::memory::cached_block::BlockCache;
use block_device::{BlockDevice, BLOCK_SIZE};
use disk::bitmap::Bitmap;
use disk::block::DataBlock;
use disk::inode::INODE_SIZE;
use users::{get_current_gid, get_current_uid};
const TTL: Duration = Duration::new(0, 0);
const INODE_PER_BLOCK: usize = BLOCK_SIZE / INODE_SIZE;
/// The design of MyFS is rather simple:
/// +-------------------+
/// | Super Block |
/// +-------------------+
/// | Inode Bitmap |
/// +-------------------+
/// | ... |
/// +-------------------+
/// | Data Block Bitmap |
/// +-------------------+
/// | ... |
/// +-------------------+
/// | Inode Block |
/// +-------------------+
/// | ... |
/// +-------------------+
/// | Data Block |
/// +-------------------+
/// With each block 4KiB, each Inode entry 128B
#[repr(C)]
pub struct AyaFS {
device: Arc<dyn BlockDevice>,
data_bitmap: Bitmap,
inode_bitmap: Bitmap,
inode_start_block: usize,
data_start_block: usize,
next_file_handle: AtomicU64,
// file descriptor -> (inode index, read, write)
file_handle_map: HashMap<u64, (usize, bool, bool)>,
// inode index -> (index aware) hashmap that maps dir entry name to inode index
dir_entry_map: LruCache<usize, IndexMap<OsString, DirectoryEntry>>,
cached_inodes: BlockCache<InodeBlock>,
cached_blocks: BlockCache<DataBlock>,
super_block: SuperBlock,
}
impl AyaFS {
pub fn new(device: Arc<dyn BlockDevice>, total_block_number: usize) -> Self {
let max_inode_number: usize = 16384; // TODO: remove hard-coded magic number
let inode_block_number = max_inode_number / INODE_PER_BLOCK; // == 128
let inode_bitmap_block_number = (inode_block_number + BLOCK_SIZE - 1) / BLOCK_SIZE;
let blocks_remaining =
total_block_number - inode_block_number - inode_bitmap_block_number - 1;
// let number of data blocks be x, the remaining block number be C,
// the corresponding data bitmap length should be ceil(x / BLK_SIZE),
// thus we have BLK_SIZE * (C-1) / (BLK_SIZE+1) <= x <= BLK_SIZE * C / (BLK_SIZE+1)
// the difference of the two bounds is less than 1,
// meaning only 1 integer could be in between.
// Thus we have x = floor(BLK_SIZE * C / (BLK_SIZE + 1))
let data_block_number = BLOCK_SIZE * blocks_remaining / (BLOCK_SIZE + 1);
let data_bitmap_block_number = blocks_remaining - data_block_number;
debug!("data_bitmap_block_number: {}", data_bitmap_block_number);
debug!("inode_bitmap_block_number: {}", inode_bitmap_block_number);
debug!("inode_block_number: {}", inode_block_number);
debug!("data_block_number: {}", data_block_number);
debug!(
"sum: {}",
1 + data_bitmap_block_number
+ inode_bitmap_block_number
+ inode_block_number
+ data_block_number
);
let super_block = SuperBlock::new(
data_bitmap_block_number,
inode_bitmap_block_number,
inode_block_number,
data_block_number,
);
let mut data_bitmap = Bitmap::new(1, data_bitmap_block_number, device.clone());
let _ = data_bitmap.allocate().unwrap(); // data block 0 is not usable
let mut inode_bitmap = Bitmap::new(
data_bitmap_block_number + 1,
inode_bitmap_block_number,
device.clone(),
);
let _ = inode_bitmap.allocate().unwrap(); // inode block 0 is not usable
let mut fs = Self {
device: device.clone(),
data_bitmap,
inode_bitmap,
inode_start_block: data_bitmap_block_number + inode_bitmap_block_number + 1,
data_start_block: data_bitmap_block_number
+ inode_bitmap_block_number
+ inode_block_number
+ 1,
next_file_handle: AtomicU64::new(3), // 0,1,2 are stdin, stdout and stderr
file_handle_map: HashMap::new(),
dir_entry_map: LruCache::new(NonZeroUsize::new(1024).unwrap()),
cached_inodes: BlockCache::new(device.clone(), 1024),
cached_blocks: BlockCache::new(device.clone(), 8192),
super_block,
};
fs.create_directory(0o755, get_current_uid(), get_current_gid(), 0, None);
fs
}
}
|
