[space_map (rust)] Fix space map building

- Fix out-of-bounds index
- Automatically flush queued writes before function return
- Track allocated blocks in write_batcher (might be space consuming)

src/pdata/space_map_common.rs

@@ -209,7 +209,7 @@ pub fn write_common(w: &mut WriteBatcher, sm: &dyn SpaceMap) -> Result<(Vec<Inde
         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()? {
+            if b >= sm.get_nr_blocks()? {
                 break;
             }
             let rc = sm.get(b)?;

src/pdata/space_map_disk.rs

@@ -16,6 +16,7 @@ pub fn write_disk_sm(w: &mut WriteBatcher, sm: &dyn SpaceMap) -> Result<SMRoot>
     }
 
     let bitmap_root = index_builder.complete(w)?;
+    w.flush()?;
 
     Ok(SMRoot {
         nr_blocks: sm.get_nr_blocks()?,

src/pdata/space_map_metadata.rs

@@ -126,6 +126,7 @@ pub fn write_metadata_sm(w: &mut WriteBatcher, sm: &dyn SpaceMap) -> Result<SMRo
     metadata_index.pack(&mut cur)?;
     let loc = bitmap_root.loc;
     w.write(bitmap_root, checksum::BT::INDEX)?;
+    w.flush()?;
 
     Ok(SMRoot {
         nr_blocks: sm.get_nr_blocks()?,

src/write_batcher.rs

@@ -43,6 +43,7 @@ impl WriteBatcher {
             return Err(anyhow!("out of metadata space"));
         }
 
+        self.allocations.insert(b.unwrap());
         Ok(Block::new(b.unwrap()))
     }