From df2c97ff0cbb602d4d7396839fba820ea1404716 Mon Sep 17 00:00:00 2001
From: Dzmitry Malyshau <kvarkus@gmail.com>
Date: Sat, 18 Apr 2020 16:55:30 -0400
Subject: [PATCH] Fix host mapping buffer barriers

---
 wgpu-core/src/conv.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/wgpu-core/src/conv.rs b/wgpu-core/src/conv.rs
index ce1aaa9fa0..23790ac001 100644
--- a/wgpu-core/src/conv.rs
+++ b/wgpu-core/src/conv.rs
@@ -486,6 +486,12 @@ pub fn map_buffer_state(usage: wgt::BufferUsage) -> hal::buffer::State {
     use wgt::BufferUsage as W;
 
     let mut access = A::empty();
+    if usage.contains(W::MAP_READ) {
+        access |= A::HOST_READ;
+    }
+    if usage.contains(W::MAP_WRITE) {
+        access |= A::HOST_WRITE;
+    }
     if usage.contains(W::COPY_SRC) {
         access |= A::TRANSFER_READ;
     }