diff --git a/nomt/src/beatree/mod.rs b/nomt/src/beatree/mod.rs
index 82dff579..c594e727 100644
--- a/nomt/src/beatree/mod.rs
+++ b/nomt/src/beatree/mod.rs
@@ -133,7 +133,7 @@ impl Tree {
         })
     }
 
-    /// Lookup a key in the btree.
+    /// Lookup a key in the btree. This blocks the current thread.
     pub fn lookup(&self, key: Key) -> Option<Vec<u8>> {
         let shared = self.shared.read();
 
@@ -148,7 +148,7 @@ impl Tree {
         }
 
         // Finally, look up in the btree.
-        ops::lookup(
+        ops::lookup_blocking(
             key,
             &shared.bbn_index,
             &shared.leaf_cache,
@@ -574,7 +574,11 @@ impl ReadTransaction {
         };
 
         match self.load_leaf_async(leaf_pn, io_handle, user_data) {
-            Ok(leaf) => Ok(ops::finish_lookup(key, &leaf.inner, &self.inner.leaf_store)),
+            Ok(leaf) => Ok(ops::finish_lookup_blocking(
+                key,
+                &leaf.inner,
+                &self.inner.leaf_store,
+            )),
             Err(pending) => Err(AsyncLookup(key, pending)),
         }
     }
@@ -631,7 +635,7 @@ impl AsyncLookup {
     /// Calling this with the wrong page will likely lead to panics or bugs in the future.
     pub fn finish(self, page: FatPage) -> Option<Vec<u8>> {
         let leaf = self.1.finish_inner(page);
-        ops::finish_lookup(self.0, &leaf, &self.1.read_tx.leaf_store)
+        ops::finish_lookup_blocking(self.0, &leaf, &self.1.read_tx.leaf_store)
     }
 }
 
diff --git a/nomt/src/beatree/ops/mod.rs b/nomt/src/beatree/ops/mod.rs
index f697f470..6b4323dd 100644
--- a/nomt/src/beatree/ops/mod.rs
+++ b/nomt/src/beatree/ops/mod.rs
@@ -32,19 +32,23 @@ pub fn partial_lookup(key: Key, bbn_index: &Index) -> Option<PageNumber> {
     search_branch(&branch, key.clone()).map(|(_, leaf_pn)| leaf_pn)
 }
 
-/// Finish looking up a key in a leaf node.
-pub fn finish_lookup(key: Key, leaf: &LeafNode, leaf_store: &StoreReader) -> Option<Vec<u8>> {
+/// Finish looking up a key in a leaf node using blocking I/O.
+pub fn finish_lookup_blocking(
+    key: Key,
+    leaf: &LeafNode,
+    leaf_store: &StoreReader,
+) -> Option<Vec<u8>> {
     leaf.get(&key).map(|(v, is_overflow)| {
         if is_overflow {
-            overflow::read(v, leaf_store)
+            overflow::read_blocking(v, leaf_store)
         } else {
             v.to_vec()
         }
     })
 }
 
-/// Lookup a key in the btree.
-pub fn lookup(
+/// Lookup a key in the btree using blocking I/O.
+pub fn lookup_blocking(
     key: Key,
     bbn_index: &Index,
     leaf_cache: &LeafCache,
@@ -66,7 +70,7 @@ pub fn lookup(
         }
     };
 
-    Ok(finish_lookup(key, &leaf, leaf_store))
+    Ok(finish_lookup_blocking(key, &leaf, leaf_store))
 }
 
 /// Binary search a branch node for the child node containing the key. This returns the last child
diff --git a/nomt/src/beatree/ops/overflow.rs b/nomt/src/beatree/ops/overflow.rs
index 310e80ca..68c12122 100644
--- a/nomt/src/beatree/ops/overflow.rs
+++ b/nomt/src/beatree/ops/overflow.rs
@@ -170,8 +170,8 @@ fn needed_pages(size: usize) -> usize {
     (size + BODY_SIZE - 1) / BODY_SIZE
 }
 
-/// Read a large value from pages referenced by an overflow cell.
-pub fn read(cell: &[u8], leaf_reader: &StoreReader) -> Vec<u8> {
+/// Read a large value from pages referenced by an overflow cell using blocking I/O.
+pub fn read_blocking(cell: &[u8], leaf_reader: &StoreReader) -> Vec<u8> {
     let (value_size, _, cell_pages) = decode_cell(cell);
     let total_pages = total_needed_pages(value_size);
 
@@ -182,7 +182,7 @@ pub fn read(cell: &[u8], leaf_reader: &StoreReader) -> Vec<u8> {
 
     for i in 0..total_pages {
         let page = leaf_reader.query(page_numbers[i]);
-        let (page_pns, bytes) = read_page(&page);
+        let (page_pns, bytes) = parse_page(&page);
         page_numbers.extend(page_pns);
         value.extend(bytes);
     }
@@ -194,6 +194,8 @@ pub fn read(cell: &[u8], leaf_reader: &StoreReader) -> Vec<u8> {
 }
 
 /// Iterate all pages related to an overflow cell and push onto a free-list.
+///
+/// This only logically deletes the pages.
 pub fn delete(cell: &[u8], leaf_reader: &StoreReader, freed: &mut Vec<PageNumber>) {
     let (value_size, _, cell_pages) = decode_cell(cell);
     let total_pages = total_needed_pages(value_size);
@@ -203,7 +205,7 @@ pub fn delete(cell: &[u8], leaf_reader: &StoreReader, freed: &mut Vec<PageNumber
 
     for i in 0..total_pages {
         let page = leaf_reader.query(freed[start + i]);
-        let (page_pns, bytes) = read_page(&page);
+        let (page_pns, bytes) = parse_page(&page);
         freed.extend(page_pns);
 
         // stop at the first page containing value data. no more pages will have more
@@ -216,7 +218,7 @@ pub fn delete(cell: &[u8], leaf_reader: &StoreReader, freed: &mut Vec<PageNumber
     assert_eq!(freed.len() - start, total_pages);
 }
 
-fn read_page<'a>(page: &'a FatPage) -> (impl Iterator<Item = PageNumber> + 'a, &'a [u8]) {
+fn parse_page<'a>(page: &'a FatPage) -> (impl Iterator<Item = PageNumber> + 'a, &'a [u8]) {
     let n_pages = u16::from_le_bytes(page[0..2].try_into().unwrap()) as usize;
     let n_bytes = u16::from_le_bytes(page[2..4].try_into().unwrap()) as usize;
 
diff --git a/nomt/src/io/mod.rs b/nomt/src/io/mod.rs
index bbcb9b23..c1f77537 100644
--- a/nomt/src/io/mod.rs
+++ b/nomt/src/io/mod.rs
@@ -3,7 +3,7 @@ std::compile_error!("NOMT only supports Unix-based OSs");
 
 use crossbeam_channel::{Receiver, RecvError, SendError, Sender, TryRecvError};
 use page_pool::Page;
-use std::{fmt, fs::File, os::fd::RawFd};
+use std::{fmt, fs::File, io::IoSliceMut, os::fd::RawFd};
 
 #[cfg(target_os = "linux")]
 #[path = "linux.rs"]