Implement register_fixed_buffer for io_uring IO backend

core/io/io_uring.rs

@@ -460,6 +460,29 @@ impl IO for UringIO {
     fn get_memory_io(&self) -> Arc<MemoryIO> {
         Arc::new(MemoryIO::new())
     }
+
+    fn register_fixed_buffer(&self, ptr: std::ptr::NonNull<u8>, len: usize) -> Result<()> {
+        turso_assert!(
+            len % 512 == 0,
+            "fixed buffer length must be logical block aligned"
+        );
+        let inner = self.inner.borrow_mut();
+        let default_id = 0;
+        unsafe {
+            // RL_MEMLOCK cap is typically 8MB, the current design is to have one large arena
+            // registered at startup and therefore we can simply use the zero index, falling back
+            // to similar logic as the existing buffer pool for cases where it is over capacity.
+            inner.ring.ring.submitter().register_buffers_update(
+                default_id,
+                &[libc::iovec {
+                    iov_base: ptr.as_ptr() as *mut libc::c_void,
+                    iov_len: len,
+                }],
+                None,
+            )?
+        };
+        Ok(())
+    }
 }
 
 impl Clock for UringIO {