From 8536a2536e95a3a0762c03d426ff8eaaec7f1acf Mon Sep 17 00:00:00 2001
From: Rob Bradford <rbradford@meta.com>
Date: Thu, 26 Mar 2026 14:14:37 -0700
Subject: [PATCH] virtio-devices: vhost_user: Adapt state() to return Result

This is a refactoring step in preparation for fetching backend device
state via SET_DEVICE_STATE_FD which can fail.

Signed-off-by: Rob Bradford <rbradford@meta.com>
---
 virtio-devices/src/vhost_user/blk.rs                |  4 ++--
 virtio-devices/src/vhost_user/fs.rs                 |  4 ++--
 virtio-devices/src/vhost_user/generic_vhost_user.rs |  4 ++--
 virtio-devices/src/vhost_user/mod.rs                | 12 +++++++++---
 virtio-devices/src/vhost_user/net.rs                |  4 ++--
 5 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/virtio-devices/src/vhost_user/blk.rs b/virtio-devices/src/vhost_user/blk.rs
index 7b574a583..8d6003216 100644
--- a/virtio-devices/src/vhost_user/blk.rs
+++ b/virtio-devices/src/vhost_user/blk.rs
@@ -191,7 +191,7 @@ impl Blk {
         })
     }
 
-    fn state(&self) -> State {
+    fn state(&self) -> std::result::Result<State, MigratableError> {
         self.vu_common.state(&self.common, self.config)
     }
 }
@@ -367,7 +367,7 @@ impl Snapshottable for Blk {
     }
 
     fn snapshot(&mut self) -> std::result::Result<Snapshot, MigratableError> {
-        self.vu_common.snapshot(&self.state())
+        self.vu_common.snapshot(&self.state()?)
     }
 }
 impl Transportable for Blk {}
diff --git a/virtio-devices/src/vhost_user/fs.rs b/virtio-devices/src/vhost_user/fs.rs
index 3ae526264..b5bf495ba 100644
--- a/virtio-devices/src/vhost_user/fs.rs
+++ b/virtio-devices/src/vhost_user/fs.rs
@@ -200,7 +200,7 @@ impl Fs {
         })
     }
 
-    fn state(&self) -> State {
+    fn state(&self) -> std::result::Result<State, MigratableError> {
         self.vu_common.state(&self.common, self.config)
     }
 }
@@ -377,7 +377,7 @@ impl Snapshottable for Fs {
     }
 
     fn snapshot(&mut self) -> std::result::Result<Snapshot, MigratableError> {
-        self.vu_common.snapshot(&self.state())
+        self.vu_common.snapshot(&self.state()?)
     }
 }
 impl Transportable for Fs {}
diff --git a/virtio-devices/src/vhost_user/generic_vhost_user.rs b/virtio-devices/src/vhost_user/generic_vhost_user.rs
index 368f46982..9b4c8e499 100644
--- a/virtio-devices/src/vhost_user/generic_vhost_user.rs
+++ b/virtio-devices/src/vhost_user/generic_vhost_user.rs
@@ -156,7 +156,7 @@ since the backend only supports {backend_num_queues}\n",
         })
     }
 
-    fn state(&self) -> State {
+    fn state(&self) -> std::result::Result<State, MigratableError> {
         self.vu_common.state(&self.common, ())
     }
 
@@ -396,7 +396,7 @@ impl Snapshottable for GenericVhostUser {
     }
 
     fn snapshot(&mut self) -> std::result::Result<Snapshot, MigratableError> {
-        self.vu_common.snapshot(&self.state())
+        self.vu_common.snapshot(&self.state()?)
     }
 }
 impl Transportable for GenericVhostUser {}
diff --git a/virtio-devices/src/vhost_user/mod.rs b/virtio-devices/src/vhost_user/mod.rs
index 811ff92e1..07df6f013 100644
--- a/virtio-devices/src/vhost_user/mod.rs
+++ b/virtio-devices/src/vhost_user/mod.rs
@@ -457,15 +457,21 @@ impl VhostUserCommon {
         Ok(())
     }
 
-    pub fn state<C: Default>(&self, common: &crate::VirtioCommon, config: C) -> VhostUserState<C> {
-        VhostUserState {
+    pub fn state<C: Default>(
+        &self,
+        common: &crate::VirtioCommon,
+        config: C,
+    ) -> std::result::Result<VhostUserState<C>, MigratableError> {
+        let state = VhostUserState {
             avail_features: common.avail_features,
             acked_features: common.acked_features,
             config,
             acked_protocol_features: self.acked_protocol_features,
             vu_num_queues: self.vu_num_queues,
             ..Default::default()
-        }
+        };
+
+        Ok(state)
     }
 
     pub fn snapshot<T>(&mut self, state: &T) -> std::result::Result<Snapshot, MigratableError>
diff --git a/virtio-devices/src/vhost_user/net.rs b/virtio-devices/src/vhost_user/net.rs
index 2145691a0..ac3719d9d 100644
--- a/virtio-devices/src/vhost_user/net.rs
+++ b/virtio-devices/src/vhost_user/net.rs
@@ -220,7 +220,7 @@ impl Net {
         })
     }
 
-    fn state(&self) -> State {
+    fn state(&self) -> std::result::Result<State, MigratableError> {
         self.vu_common.state(&self.common, self.config)
     }
 }
@@ -425,7 +425,7 @@ impl Snapshottable for Net {
     }
 
     fn snapshot(&mut self) -> std::result::Result<Snapshot, MigratableError> {
-        self.vu_common.snapshot(&self.state())
+        self.vu_common.snapshot(&self.state()?)
     }
 }
 impl Transportable for Net {}