WIP: page_cache_priming_writer: bugfixes

pageserver/src/virtual_file.rs

@@ -1100,7 +1100,11 @@ impl OwnedAsyncWriter for VirtualFile {
     }
 
     #[inline(always)]
-    async fn write_all_borrowed(&mut self, _buf: &[u8], _ctx: &RequestContext) -> std::io::Result<usize> {
+    async fn write_all_borrowed(
+        &mut self,
+        _buf: &[u8],
+        _ctx: &RequestContext,
+    ) -> std::io::Result<usize> {
         // TODO: ensure this through the type system
         panic!("this should not happen");
     }

pageserver/src/virtual_file/owned_buffers_io/util/page_cache_priming_writer.rs

@@ -85,9 +85,13 @@ where
                     .try_into()
                     .unwrap();
                 self.cache
-                    .fill_cache(&self.under, self.written / (N as u64), page, ctx)
+                    .fill_cache(
+                        &self.under,
+                        (self.written / (N as u64)) + (page_no_in_buf as u64),
+                        page,
+                        ctx,
+                    )
                     .await;
-                self.written += N as u64;
             }
             self.written += nwritten as u64;
             Ok((nwritten, tokio_epoll_uring::Slice::into_inner(buf)))