From 7e599b445076ec4976690570edc3b43ac49e0d04 Mon Sep 17 00:00:00 2001
From: Rob Bradford <robert.bradford@intel.com>
Date: Fri, 13 Mar 2020 10:25:17 +0000
Subject: [PATCH] vmm: Make disk path optional

When using "--disk" with a vhost socket and not using self spawning then
it is not necessary or helpful to specify the path.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>
---
 vmm/src/config.rs         |  8 ++++++--
 vmm/src/device_manager.rs | 29 +++++++++++++++++++++++++----
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/vmm/src/config.rs b/vmm/src/config.rs
index fb045f68c..e656524b6 100644
--- a/vmm/src/config.rs
+++ b/vmm/src/config.rs
@@ -335,7 +335,7 @@ impl CmdlineConfig {
 
 #[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
 pub struct DiskConfig {
-    pub path: PathBuf,
+    pub path: Option<PathBuf>,
     #[serde(default)]
     pub readonly: bool,
     #[serde(default)]
@@ -417,6 +417,7 @@ impl DiskConfig {
         let mut vhost_socket = None;
         let mut wce: bool = default_diskconfig_wce();
         let mut poll_queue: bool = default_diskconfig_poll_queue();
+        let mut path = None;
 
         if !num_queues_str.is_empty() {
             num_queues = num_queues_str
@@ -448,9 +449,12 @@ impl DiskConfig {
                 .parse()
                 .map_err(Error::ParseDiskPollQueueParam)?;
         }
+        if !path_str.is_empty() {
+            path = Some(PathBuf::from(path_str))
+        }
 
         Ok(DiskConfig {
-            path: PathBuf::from(path_str),
+            path,
             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 14cdbab62..9b9e731f6 100644
--- a/vmm/src/device_manager.rs
+++ b/vmm/src/device_manager.rs
@@ -255,6 +255,9 @@ pub enum DeviceManagerError {
 
     /// Incorrect device ID as it is already used by another device.
     DeviceIdAlreadyInUse,
+
+    // No disk path was specified when one was expected
+    NoDiskPath,
 }
 pub type DeviceManagerResult<T> = result::Result<T, DeviceManagerError>;
 
@@ -1026,7 +1029,12 @@ impl DeviceManager {
                 "--block-backend",
                 &format!(
                     "image={},sock={},num_queues={},queue_size={}",
-                    disk_cfg.path.to_str().unwrap(),
+                    disk_cfg
+                        .path
+                        .as_ref()
+                        .ok_or(DeviceManagerError::NoDiskPath)?
+                        .to_str()
+                        .unwrap(),
                     &sock,
                     disk_cfg.num_queues,
                     disk_cfg.queue_size
@@ -1083,7 +1091,12 @@ impl DeviceManager {
                     }
                     // Open block device path
                     let image: File = options
-                        .open(&disk_cfg.path)
+                        .open(
+                            &disk_cfg
+                                .path
+                                .as_ref()
+                                .ok_or(DeviceManagerError::NoDiskPath)?,
+                        )
                         .map_err(DeviceManagerError::Disk)?;
 
                     let mut raw_img = vm_virtio::RawFile::new(image, disk_cfg.direct);
@@ -1094,7 +1107,11 @@ impl DeviceManager {
                         ImageType::Raw => {
                             let dev = vm_virtio::Block::new(
                                 raw_img,
-                                disk_cfg.path.clone(),
+                                disk_cfg
+                                    .path
+                                    .as_ref()
+                                    .ok_or(DeviceManagerError::NoDiskPath)?
+                                    .clone(),
                                 disk_cfg.readonly,
                                 disk_cfg.iommu,
                                 disk_cfg.num_queues,
@@ -1116,7 +1133,11 @@ impl DeviceManager {
                                 .map_err(DeviceManagerError::QcowDeviceCreate)?;
                             let dev = vm_virtio::Block::new(
                                 qcow_img,
-                                disk_cfg.path.clone(),
+                                disk_cfg
+                                    .path
+                                    .as_ref()
+                                    .ok_or(DeviceManagerError::NoDiskPath)?
+                                    .clone(),
                                 disk_cfg.readonly,
                                 disk_cfg.iommu,
                                 disk_cfg.num_queues,