From 70ecd6bab4a8235cd476ce74f5215d224740f4a0 Mon Sep 17 00:00:00 2001
From: Rob Bradford <robert.bradford@intel.com>
Date: Tue, 14 Apr 2020 15:47:11 +0100
Subject: [PATCH] vmm, virtio: fs: Move freeing of mappped region into device

Move the release of the managed memory region from the DeviceManager to
the vhost-user-fs device. This ensures that the memory will be freed when
the device is unplugged which will lead to it being Drop()ed.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>
---
 vm-virtio/src/vhost_user/fs.rs | 13 ++++++++-----
 vmm/src/device_manager.rs      |  5 ++---
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/vm-virtio/src/vhost_user/fs.rs b/vm-virtio/src/vhost_user/fs.rs
index 4ed59c392..4bfbbecd7 100644
--- a/vm-virtio/src/vhost_user/fs.rs
+++ b/vm-virtio/src/vhost_user/fs.rs
@@ -28,6 +28,7 @@ use vhost_rs::vhost_user::{
 use vhost_rs::VhostBackend;
 use vm_memory::{
     Address, ByteValued, GuestAddress, GuestAddressSpace, GuestMemoryAtomic, GuestMemoryMmap,
+    MmapRegion,
 };
 use vm_migration::{Migratable, MigratableError, Pausable, Snapshottable, Transportable};
 use vmm_sys_util::eventfd::EventFd;
@@ -258,7 +259,9 @@ pub struct Fs {
     config: VirtioFsConfig,
     kill_evt: Option<EventFd>,
     pause_evt: Option<EventFd>,
-    cache: Option<(VirtioSharedMemoryList, u64)>,
+    // Hold ownership of the memory that is allocated for the device
+    // which will be automatically dropped when the device is dropped
+    cache: Option<(VirtioSharedMemoryList, u64, MmapRegion)>,
     slave_req_support: bool,
     queue_evts: Option<Vec<EventFd>>,
     interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
@@ -273,7 +276,7 @@ impl Fs {
         tag: &str,
         req_num_queues: usize,
         queue_size: u16,
-        cache: Option<(VirtioSharedMemoryList, u64)>,
+        cache: Option<(VirtioSharedMemoryList, u64, MmapRegion)>,
     ) -> Result<Fs> {
         let mut slave_req_support = false;
 
@@ -471,7 +474,7 @@ impl VirtioDevice for Fs {
 
         // Initialize slave communication.
         let slave_req_handler = if self.slave_req_support {
-            if let Some(cache) = self.cache.clone() {
+            if let Some(cache) = self.cache.as_ref() {
                 let vu_master_req_handler = Arc::new(Mutex::new(SlaveReqHandler {
                     cache_offset: cache.0.addr,
                     cache_size: cache.0.len,
@@ -542,8 +545,8 @@ impl VirtioDevice for Fs {
     }
 
     fn get_shm_regions(&self) -> Option<VirtioSharedMemoryList> {
-        if let Some(cache) = self.cache.clone() {
-            Some(cache.0)
+        if let Some(cache) = self.cache.as_ref() {
+            Some(cache.0.clone())
         } else {
             None
         }
diff --git a/vmm/src/device_manager.rs b/vmm/src/device_manager.rs
index 27330f9cc..594c374a1 100644
--- a/vmm/src/device_manager.rs
+++ b/vmm/src/device_manager.rs
@@ -1331,7 +1331,7 @@ impl DeviceManager {
         if let Some(fs_list_cfg) = &self.config.lock().unwrap().fs {
             for fs_cfg in fs_list_cfg.iter() {
                 if let Some(fs_sock) = fs_cfg.sock.to_str() {
-                    let cache: Option<(VirtioSharedMemoryList, u64)> = if fs_cfg.dax {
+                    let cache = if fs_cfg.dax {
                         let fs_cache = fs_cfg.cache_size;
                         // The memory needs to be 2MiB aligned in order to support
                         // hugepages.
@@ -1356,8 +1356,6 @@ impl DeviceManager {
                         .map_err(DeviceManagerError::NewMmapRegion)?;
                         let addr: u64 = mmap_region.as_ptr() as u64;
 
-                        self._mmap_regions.push(mmap_region);
-
                         self.memory_manager
                             .lock()
                             .unwrap()
@@ -1383,6 +1381,7 @@ impl DeviceManager {
                                 region_list,
                             },
                             addr,
+                            mmap_region,
                         ))
                     } else {
                         None