139 lines
3.7 KiB
Rust
139 lines
3.7 KiB
Rust
use anyhow::Result;
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use byteorder::{LittleEndian, WriteBytesExt};
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use nom::{number::complete::*, IResult};
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use std::collections::BTreeMap;
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use std::io::Cursor;
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use crate::checksum;
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use crate::io_engine::*;
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use crate::pdata::space_map::*;
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use crate::pdata::space_map_common::*;
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use crate::pdata::unpack::*;
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use crate::write_batcher::*;
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//------------------------------------------
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const MAX_METADATA_BITMAPS: usize = 255;
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//------------------------------------------
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pub struct MetadataIndex {
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pub blocknr: u64,
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pub indexes: Vec<IndexEntry>,
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}
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impl Unpack for MetadataIndex {
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fn disk_size() -> u32 {
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BLOCK_SIZE as u32
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}
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fn unpack(i: &[u8]) -> IResult<&[u8], MetadataIndex> {
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// FIXME: check the checksum
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let (i, _csum) = le_u32(i)?;
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let (i, _padding) = le_u32(i)?;
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let (i, blocknr) = le_u64(i)?;
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let (i, indexes) = nom::multi::count(IndexEntry::unpack, MAX_METADATA_BITMAPS)(i)?;
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Ok((i, MetadataIndex { blocknr, indexes }))
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}
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}
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impl Pack for MetadataIndex {
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fn pack<W: WriteBytesExt>(&self, w: &mut W) -> Result<()> {
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w.write_u32::<LittleEndian>(0)?; // csum
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w.write_u32::<LittleEndian>(0)?; // padding
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w.write_u64::<LittleEndian>(self.blocknr)?;
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assert!(self.indexes.len() <= MAX_METADATA_BITMAPS);
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for ie in &self.indexes {
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ie.pack(w)?;
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}
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Ok(())
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}
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}
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//------------------------------------------
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fn block_to_bitmap(b: u64) -> usize {
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(b / ENTRIES_PER_BITMAP as u64) as usize
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}
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fn adjust_counts(w: &mut WriteBatcher, ie: &IndexEntry, allocs: &[u64]) -> Result<IndexEntry> {
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use BitmapEntry::*;
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let mut first_free = ie.none_free_before;
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let mut nr_free = ie.nr_free - allocs.len() as u32;
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// Read the bitmap
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let bitmap_block = w.engine.read(ie.blocknr)?;
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let (_, mut bitmap) = Bitmap::unpack(bitmap_block.get_data())?;
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// Update all the entries
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for a in allocs {
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if first_free == *a as u32 {
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first_free = *a as u32 + 1;
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}
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if bitmap.entries[*a as usize] == Small(0) {
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nr_free -= 1;
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}
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bitmap.entries[*a as usize] = Small(1);
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}
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// Write the bitmap
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let mut cur = Cursor::new(bitmap_block.get_data());
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bitmap.pack(&mut cur)?;
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w.write(bitmap_block, checksum::BT::BITMAP)?;
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// Return the adjusted index entry
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Ok(IndexEntry {
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blocknr: ie.blocknr,
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nr_free,
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none_free_before: first_free,
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})
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}
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pub fn write_metadata_sm(w: &mut WriteBatcher, sm: &dyn SpaceMap) -> Result<SMRoot> {
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w.clear_allocations();
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let (mut indexes, ref_count_root) = write_common(w, sm)?;
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let bitmap_root = w.alloc()?;
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// Now we need to patch up the counts for the metadata that was used for storing
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// the space map itself. These ref counts all went from 0 to 1.
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let allocations = w.clear_allocations();
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// Sort the allocations by bitmap
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let mut by_bitmap = BTreeMap::new();
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for b in allocations {
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let bitmap = block_to_bitmap(b);
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(*by_bitmap.entry(bitmap).or_insert_with(Vec::new)).push(b % ENTRIES_PER_BITMAP as u64);
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}
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for (bitmap, allocs) in by_bitmap {
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indexes[bitmap] = adjust_counts(w, &indexes[bitmap], &allocs)?;
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}
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// Write out the metadata index
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let metadata_index = MetadataIndex {
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blocknr: bitmap_root.loc,
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indexes,
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};
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let mut cur = Cursor::new(bitmap_root.get_data());
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metadata_index.pack(&mut cur)?;
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let loc = bitmap_root.loc;
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w.write(bitmap_root, checksum::BT::INDEX)?;
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Ok(SMRoot {
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nr_blocks: sm.get_nr_blocks()?,
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nr_allocated: sm.get_nr_allocated()?,
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bitmap_root: loc,
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ref_count_root,
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})
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}
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//------------------------------------------
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