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[space_map (rust)] Fix bitmap packing

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- Allow packing unaligned number of bitmap entries that could happen
  with the last bitmap. Unused trailing entries are zeroed by memset.
- Fix none_free_before in index_entry
This commit is contained in:
Ming-Hung Tsai 2021-06-15 11:14:54 +08:00
parent 3fda9cc1f8
commit 9ab8dfa283
1 changed files with 29 additions and 19 deletions
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48
src/pdata/space_map_common.rs
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@ -111,8 +111,8 @@ impl Pack for Bitmap {
fn pack<W: WriteBytesExt>(&self, out: &mut W) -> Result<()> {
use BitmapEntry::*;
out.write_u32::<LittleEndian>(0)?;
out.write_u32::<LittleEndian>(0)?;
out.write_u32::<LittleEndian>(0)?; // csum
out.write_u32::<LittleEndian>(0)?; // padding
out.write_u64::<LittleEndian>(self.blocknr)?;
for chunk in self.entries.chunks(32) {
@ -135,6 +135,7 @@ impl Pack for Bitmap {
}
}
}
w >>= 64 - chunk.len() * 2;
u64::pack(&w, out)?;
}
@ -203,15 +204,18 @@ pub fn write_common(w: &mut WriteBatcher, sm: &dyn SpaceMap) -> Result<(Vec<Inde
let mut overflow_builder: BTreeBuilder<u32> = BTreeBuilder::new(Box::new(NoopRC {}));
// how many bitmaps do we need?
for bm in 0..div_up(sm.get_nr_blocks()? as usize, ENTRIES_PER_BITMAP) {
let nr_blocks = sm.get_nr_blocks()?;
let nr_bitmaps = div_up(nr_blocks, ENTRIES_PER_BITMAP as u64) as usize;
for bm in 0..nr_bitmaps {
let begin = bm as u64 * ENTRIES_PER_BITMAP as u64;
let len = std::cmp::min(nr_blocks - begin, ENTRIES_PER_BITMAP as u64);
let mut entries = Vec::with_capacity(ENTRIES_PER_BITMAP);
let mut first_free: Option<u32> = None;
let mut nr_free: u32 = 0;
for i in 0..ENTRIES_PER_BITMAP {
let b: u64 = ((bm * ENTRIES_PER_BITMAP) as u64) + i as u64;
if b >= sm.get_nr_blocks()? {
break;
}
for i in 0..len {
let b = begin + i;
let rc = sm.get(b)?;
let e = match rc {
0 => {
@ -231,21 +235,13 @@ pub fn write_common(w: &mut WriteBatcher, sm: &dyn SpaceMap) -> Result<(Vec<Inde
entries.push(e);
}
// allocate a new block
let b = w.alloc()?;
let mut cursor = Cursor::new(b.get_data());
let blocknr = write_bitmap(w, entries)?;
// write the bitmap to it
let blocknr = b.loc;
let bitmap = Bitmap { blocknr, entries };
bitmap.pack(&mut cursor)?;
w.write(b, checksum::BT::BITMAP)?;
// Insert into the index tree
// Insert into the index list
let ie = IndexEntry {
blocknr,
nr_free,
none_free_before: first_free.unwrap_or(ENTRIES_PER_BITMAP as u32),
none_free_before: first_free.unwrap_or(len as u32),
};
index_entries.push(ie);
}
@ -254,4 +250,18 @@ pub fn write_common(w: &mut WriteBatcher, sm: &dyn SpaceMap) -> Result<(Vec<Inde
Ok((index_entries, ref_count_root))
}
fn write_bitmap(w: &mut WriteBatcher, entries: Vec<BitmapEntry>) -> Result<u64> {
// allocate a new block
let b = w.alloc_zeroed()?;
let mut cursor = Cursor::new(b.get_data());
// write the bitmap to it
let blocknr = b.loc;
let bitmap = Bitmap { blocknr, entries };
bitmap.pack(&mut cursor)?;
w.write(b, checksum::BT::BITMAP)?;
Ok(blocknr)
}
//------------------------------------------