From 925c862f98cc71044fc894e542f7cf41e2f2dd7b Mon Sep 17 00:00:00 2001
From: Sergio Lopez <slp@redhat.com>
Date: Tue, 21 Jan 2020 12:36:27 +0100
Subject: [PATCH] vmm: device_manager: Add 'direct' support for virtio-blk

vhost_user_blk already has it, so it's only fair to give it to
virtio-blk too. Extend DiskConfig with a 'direct' property, honor
it while opening the file backing the disk image, and pass it to
vm_virtio::RawFile.

Fixes #631

Signed-off-by: Sergio Lopez <slp@redhat.com>
---
 vmm/src/config.rs         |  6 ++++++
 vmm/src/device_manager.rs | 12 ++++++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/vmm/src/config.rs b/vmm/src/config.rs
index 6859e8b9a..d4c53cfb6 100644
--- a/vmm/src/config.rs
+++ b/vmm/src/config.rs
@@ -340,6 +340,8 @@ pub struct DiskConfig {
     #[serde(default)]
     pub readonly: bool,
     #[serde(default)]
+    pub direct: bool,
+    #[serde(default)]
     pub iommu: bool,
 }
 
@@ -350,6 +352,7 @@ impl DiskConfig {
 
         let mut path_str: &str = "";
         let mut readonly_str: &str = "";
+        let mut direct_str: &str = "";
         let mut iommu_str: &str = "";
 
         for param in params_list.iter() {
@@ -357,6 +360,8 @@ impl DiskConfig {
                 path_str = &param[5..];
             } else if param.starts_with("readonly=") {
                 readonly_str = &param[9..];
+            } else if param.starts_with("direct=") {
+                direct_str = &param[7..];
             } else if param.starts_with("iommu=") {
                 iommu_str = &param[6..];
             }
@@ -365,6 +370,7 @@ impl DiskConfig {
         Ok(DiskConfig {
             path: PathBuf::from(path_str),
             readonly: parse_on_off(readonly_str)?,
+            direct: parse_on_off(direct_str)?,
             iommu: parse_on_off(iommu_str)?,
         })
     }
diff --git a/vmm/src/device_manager.rs b/vmm/src/device_manager.rs
index fc67500b8..57c17a00a 100644
--- a/vmm/src/device_manager.rs
+++ b/vmm/src/device_manager.rs
@@ -935,14 +935,18 @@ impl DeviceManager {
 
         if let Some(disk_list_cfg) = &vm_info.vm_cfg.lock().unwrap().disks {
             for disk_cfg in disk_list_cfg.iter() {
+                let mut options = OpenOptions::new();
+                options.read(true);
+                options.write(!disk_cfg.readonly);
+                if disk_cfg.direct {
+                    options.custom_flags(libc::O_DIRECT);
+                }
                 // Open block device path
-                let image: File = OpenOptions::new()
-                    .read(true)
-                    .write(!disk_cfg.readonly)
+                let image: File = options
                     .open(&disk_cfg.path)
                     .map_err(DeviceManagerError::Disk)?;
 
-                let mut raw_img = vm_virtio::RawFile::new(image, false);
+                let mut raw_img = vm_virtio::RawFile::new(image, disk_cfg.direct);
 
                 let image_type = qcow::detect_image_type(&mut raw_img)
                     .map_err(DeviceManagerError::DetectImageType)?;