From 34c26c01cde72ce2a816d82674141d70ef9fee5c Mon Sep 17 00:00:00 2001
From: Mathias Rieder <Mathias.RIEDER@bachmann.info>
Date: Thu, 19 Mar 2026 08:09:19 +0100
Subject: [PATCH 1/2] Add support for external Tokio runtimes in TokioAdapter

---
 src/experimental.rs | 49 ++++++++++++++++++++++++++++++++++++---------
 1 file changed, 40 insertions(+), 9 deletions(-)

diff --git a/src/experimental.rs b/src/experimental.rs
index 9185b08d..5a347a63 100644
--- a/src/experimental.rs
+++ b/src/experimental.rs
@@ -121,23 +121,54 @@ impl GetAttrResponse {
     }
 }
 
+#[derive(Debug)]
+enum Runtime {
+    /// Use the runtime provided by the user
+    External(tokio::runtime::Handle),
+    /// Use an internal runtime
+    Internal(tokio::runtime::Runtime),
+}
+
 /// Adapter to allow running an [`AsyncFilesystem`] with tokio's runtime.
 #[derive(Debug)]
 pub struct TokioAdapter<T: AsyncFilesystem> {
     inner: Arc<T>,
-    runtime: tokio::runtime::Runtime,
+    runtime: Runtime,
 }
 
 impl<T: AsyncFilesystem> TokioAdapter<T> {
+
+    /// Create a new adapter with an internal tokio runtime.
     pub fn new(inner: T) -> Self {
         Self {
             inner: Arc::new(inner),
-            runtime: tokio::runtime::Builder::new_multi_thread()
-                .enable_all()
-                .build()
-                .unwrap(),
+            runtime: Runtime::Internal(
+                tokio::runtime::Builder::new_multi_thread()
+                    .enable_all()
+                    .build()
+                    .unwrap(),
+            ),
         }
     }
+
+    /// Use an existing tokio runtime. This is useful if you want to run the filesystem 
+    /// in an existing application that already uses a tokio runtime.
+    pub fn with_runtime(inner: T, runtime_handle: tokio::runtime::Handle) -> Self {
+        Self {
+            inner: Arc::new(inner),
+            runtime: Runtime::External(runtime_handle),
+        }
+    }
+
+    fn spawn<F>(&self, fut: F)
+    where
+        F: std::future::Future<Output = ()> + Send + 'static,
+    {
+        match &self.runtime {
+            Runtime::External(handle) => handle.spawn(fut),
+            Runtime::Internal(rt) => rt.spawn(fut),
+        };
+    }
 }
 
 impl<T: AsyncFilesystem + Send + Sync + 'static> Filesystem for TokioAdapter<T> {
@@ -145,7 +176,7 @@ impl<T: AsyncFilesystem + Send + Sync + 'static> Filesystem for TokioAdapter<T>
         let context: RequestContext = req.into();
         let name = name.to_os_string();
         let inner = self.inner.clone();
-        self.runtime.spawn(async move {
+        self.spawn(async move {
             match inner.lookup(&context, parent, &name).await {
                 Ok(LookupResponse {
                     ttl,
@@ -160,7 +191,7 @@ impl<T: AsyncFilesystem + Send + Sync + 'static> Filesystem for TokioAdapter<T>
     fn getattr(&self, req: &Request, ino: INodeNo, fh: Option<FileHandle>, reply: ReplyAttr) {
         let context: RequestContext = req.into();
         let inner = self.inner.clone();
-        self.runtime.spawn(async move {
+        self.spawn(async move {
             match inner.getattr(&context, ino, fh).await {
                 Ok(GetAttrResponse { ttl, attr }) => reply.attr(&ttl, &attr),
                 Err(e) => reply.error(e),
@@ -181,7 +212,7 @@ impl<T: AsyncFilesystem + Send + Sync + 'static> Filesystem for TokioAdapter<T>
     ) {
         let context: RequestContext = req.into();
         let inner = self.inner.clone();
-        self.runtime.spawn(async move {
+        self.spawn(async move {
             let mut buf = vec![];
             match inner
                 .read(&context, ino, fh, offset, size, flags, lock_owner, &mut buf)
@@ -203,7 +234,7 @@ impl<T: AsyncFilesystem + Send + Sync + 'static> Filesystem for TokioAdapter<T>
     ) {
         let context: RequestContext = req.into();
         let inner = self.inner.clone();
-        self.runtime.spawn(async move {
+        self.spawn(async move {
             let builder = DirEntListBuilder {
                 entries: &mut reply,
             };

From 7c2aca280d868d7714dbeaeddc8c4ee5565196ae Mon Sep 17 00:00:00 2001
From: Mathias Rieder <mathias.rieder@gmail.com>
Date: Thu, 19 Mar 2026 15:53:59 +0100
Subject: [PATCH 2/2] wip

---
 src/experimental.rs | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/experimental.rs b/src/experimental.rs
index 5a347a63..ad0e2b70 100644
--- a/src/experimental.rs
+++ b/src/experimental.rs
@@ -244,7 +244,43 @@ impl<T: AsyncFilesystem + Send + Sync + 'static> Filesystem for TokioAdapter<T>
             }
         });
     }
-}
+
+    fn flush(
+            &self,
+            _req: &Request,
+            _ino: INodeNo,
+            _fh: FileHandle,
+            _lock_owner: LockOwner,
+            reply: crate::ReplyEmpty,
+        ) {
+            reply.error(Errno::ENOSYS);
+    }
+
+    fn ioctl(
+            &self,
+            req: &Request,
+            ino: INodeNo,
+            fh: FileHandle,
+            flags: crate::IoctlFlags,
+            cmd: u32,
+            in_data: &[u8],
+            out_size: u32,
+            reply: crate::ReplyIoctl,
+        
+        ) {
+            reply.error(Errno::ENOSYS);
+        }
+
+        fn getxattr(&self, _req: &Request, ino: INodeNo, name: &OsStr, size: u32, reply: crate::ReplyXattr) {
+            reply.error(Errno::ENOSYS);
+        }
+
+        fn listxattr(&self, _req: &Request, ino: INodeNo, size: u32, reply: crate::ReplyXattr) {
+            reply.error(Errno::ENOSYS);
+        }
+
+    }
+
 
 /// Experimental async API. Expect this to change in the future
 #[async_trait::async_trait]