diff --git a/actix-http/examples/echo.rs b/actix-http/examples/echo.rs
index 0b1a5081c..f9188ed9f 100644
--- a/actix-http/examples/echo.rs
+++ b/actix-http/examples/echo.rs
@@ -28,8 +28,6 @@ async fn main() -> io::Result<()> {
                         .insert_header(("x-head", HeaderValue::from_static("dummy value!")))
                         .body(body);
 
-                    res.req_data_mut().insert(5usize);
-
                     Ok::<_, Error>(res)
                 })
                 // No TLS
diff --git a/actix-http/examples/res-ext.rs b/actix-http/examples/res-ext.rs
new file mode 100644
index 000000000..6418a301b
--- /dev/null
+++ b/actix-http/examples/res-ext.rs
@@ -0,0 +1,53 @@
+use std::{convert::Infallible, io};
+
+use actix_http::{
+    body::EitherBody, HttpMessage as _, HttpService, Request, Response, StatusCode,
+};
+use actix_server::Server;
+
+#[actix_rt::main]
+async fn main() -> io::Result<()> {
+    env_logger::init_from_env(env_logger::Env::new().default_filter_or("info"));
+
+    Server::build()
+        .bind("hello-world", ("127.0.0.1", 8080), || {
+            HttpService::build()
+                .client_timeout(1000)
+                .client_disconnect(1000)
+                .finish(|req: Request| async move {
+                    let mut res = Response::build(StatusCode::OK).body("Hello world!");
+
+                    match req.path() {
+                        "/" => {}
+
+                        "/ext" => {
+                            res.extensions_mut().insert(123u8);
+                        }
+
+                        "/more" => {
+                            res.extensions_mut().insert(123u8);
+                            res.extensions_mut().insert(123u16);
+                            res.extensions_mut().insert(123u32);
+                            res.extensions_mut().insert(123u64);
+                            res.extensions_mut().insert(123u128);
+                            res.extensions_mut().insert(123i8);
+                            res.extensions_mut().insert(123i16);
+                            res.extensions_mut().insert(123i32);
+                            res.extensions_mut().insert(123i64);
+                            res.extensions_mut().insert(123i128);
+                        }
+
+                        _ => {
+                            return Ok(Response::not_found()
+                                .map_body(|_, body| EitherBody::right(body)))
+                        }
+                    }
+
+                    Ok::<_, Infallible>(res)
+                })
+                .tcp()
+        })?
+        .workers(4)
+        .run()
+        .await
+}
diff --git a/actix-http/src/error.rs b/actix-http/src/error.rs
index cdf495c45..df6d3813a 100644
--- a/actix-http/src/error.rs
+++ b/actix-http/src/error.rs
@@ -387,6 +387,7 @@ impl StdError for DispatchError {
 
 /// A set of error that can occur during parsing content type.
 #[derive(Debug, Display, Error)]
+#[cfg_attr(test, derive(PartialEq))]
 #[non_exhaustive]
 pub enum ContentTypeError {
     /// Can not parse content type
@@ -398,28 +399,14 @@ pub enum ContentTypeError {
     UnknownEncoding,
 }
 
-#[cfg(test)]
-mod content_type_test_impls {
-    use super::*;
-
-    impl std::cmp::PartialEq for ContentTypeError {
-        fn eq(&self, other: &Self) -> bool {
-            match self {
-                Self::ParseError => matches!(other, ContentTypeError::ParseError),
-                Self::UnknownEncoding => {
-                    matches!(other, ContentTypeError::UnknownEncoding)
-                }
-            }
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
-    use super::*;
-    use http::{Error as HttpError, StatusCode};
     use std::io;
 
+    use http::{Error as HttpError, StatusCode};
+
+    use super::*;
+
     #[test]
     fn test_into_response() {
         let resp: Response<BoxBody> = ParseError::Incomplete.into();
diff --git a/actix-http/src/http_message.rs b/actix-http/src/http_message.rs
index ccaa320fa..3c91b2f40 100644
--- a/actix-http/src/http_message.rs
+++ b/actix-http/src/http_message.rs
@@ -25,10 +25,10 @@ pub trait HttpMessage: Sized {
     /// Message payload stream
     fn take_payload(&mut self) -> Payload<Self::Stream>;
 
-    /// Request's extensions container
+    /// Returns a reference to the request-local data container.
     fn extensions(&self) -> Ref<'_, Extensions>;
 
-    /// Mutable reference to a the request's extensions container
+    /// Returns a mutable reference to the request-local data container.
     fn extensions_mut(&self) -> RefMut<'_, Extensions>;
 
     /// Get a header.
diff --git a/actix-http/src/requests/request.rs b/actix-http/src/requests/request.rs
index 4eaaba8e1..0f8e78d46 100644
--- a/actix-http/src/requests/request.rs
+++ b/actix-http/src/requests/request.rs
@@ -19,7 +19,7 @@ pub struct Request<P = BoxedPayloadStream> {
     pub(crate) payload: Payload<P>,
     pub(crate) head: Message<RequestHead>,
     pub(crate) conn_data: Option<Rc<Extensions>>,
-    pub(crate) req_data: RefCell<Extensions>,
+    pub(crate) extensions: RefCell<Extensions>,
 }
 
 impl<P> HttpMessage for Request<P> {
@@ -34,16 +34,14 @@ impl<P> HttpMessage for Request<P> {
         mem::replace(&mut self.payload, Payload::None)
     }
 
-    /// Request extensions
     #[inline]
     fn extensions(&self) -> Ref<'_, Extensions> {
-        self.req_data.borrow()
+        self.extensions.borrow()
     }
 
-    /// Mutable reference to a the request's extensions
     #[inline]
     fn extensions_mut(&self) -> RefMut<'_, Extensions> {
-        self.req_data.borrow_mut()
+        self.extensions.borrow_mut()
     }
 }
 
@@ -52,7 +50,7 @@ impl From<Message<RequestHead>> for Request<BoxedPayloadStream> {
         Request {
             head,
             payload: Payload::None,
-            req_data: RefCell::new(Extensions::default()),
+            extensions: RefCell::new(Extensions::default()),
             conn_data: None,
         }
     }
@@ -65,7 +63,7 @@ impl Request<BoxedPayloadStream> {
         Request {
             head: Message::new(),
             payload: Payload::None,
-            req_data: RefCell::new(Extensions::default()),
+            extensions: RefCell::new(Extensions::default()),
             conn_data: None,
         }
     }
@@ -77,7 +75,7 @@ impl<P> Request<P> {
         Request {
             payload,
             head: Message::new(),
-            req_data: RefCell::new(Extensions::default()),
+            extensions: RefCell::new(Extensions::default()),
             conn_data: None,
         }
     }
@@ -90,7 +88,7 @@ impl<P> Request<P> {
             Request {
                 payload,
                 head: self.head,
-                req_data: self.req_data,
+                extensions: self.extensions,
                 conn_data: self.conn_data,
             },
             pl,
@@ -195,16 +193,17 @@ impl<P> Request<P> {
             .and_then(|container| container.get::<T>())
     }
 
-    /// Returns the connection data container if an [on-connect] callback was registered.
+    /// Returns the connection-level data/extensions container if an [on-connect] callback was
+    /// registered, leaving an empty one in its place.
     ///
     /// [on-connect]: crate::HttpServiceBuilder::on_connect_ext
     pub fn take_conn_data(&mut self) -> Option<Rc<Extensions>> {
         self.conn_data.take()
     }
 
-    /// Returns the request data container, leaving an empty one in it's place.
+    /// Returns the request-local data/extensions container, leaving an empty one in its place.
     pub fn take_req_data(&mut self) -> Extensions {
-        mem::take(self.req_data.get_mut())
+        mem::take(self.extensions.get_mut())
     }
 }
 
diff --git a/actix-http/src/responses/response.rs b/actix-http/src/responses/response.rs
index 08dddb90a..7a0bae516 100644
--- a/actix-http/src/responses/response.rs
+++ b/actix-http/src/responses/response.rs
@@ -128,18 +128,6 @@ impl<B> Response<B> {
         self.head.keep_alive()
     }
 
-    /// Returns a reference to the extensions of this response.
-    #[inline]
-    pub fn extensions(&self) -> Ref<'_, Extensions> {
-        self.extensions.borrow()
-    }
-
-    /// Returns a mutable reference to the extensions of this response.
-    #[inline]
-    pub fn extensions_mut(&self) -> RefMut<'_, Extensions> {
-        self.extensions.borrow_mut()
-    }
-
     /// Returns a reference to the body of this response.
     #[inline]
     pub fn body(&self) -> &B {
@@ -185,7 +173,9 @@ impl<B> Response<B> {
         self.replace_body(())
     }
 
-    /// Returns new response with mapped body.
+    /// Map the current body type to another using a closure. Returns a new response.
+    ///
+    /// Closure receives the response head and the current body type.
     #[inline]
     pub fn map_body<F, B2>(mut self, f: F) -> Response<B2>
     where
diff --git a/awc/src/responses/response.rs b/awc/src/responses/response.rs
index 017c59744..02ffdbab2 100644
--- a/awc/src/responses/response.rs
+++ b/awc/src/responses/response.rs
@@ -67,7 +67,9 @@ impl<S> ClientResponse<S> {
         &self.head().headers
     }
 
-    /// Set a body and return previous body value
+    /// Map the current body type to another using a closure. Returns a new response.
+    ///
+    /// Closure receives the response head and the current body type.
     pub fn map_body<F, U>(mut self, f: F) -> ClientResponse<U>
     where
         F: FnOnce(&mut ResponseHead, Payload<S>) -> Payload<U>,
@@ -117,18 +119,6 @@ impl<S> ClientResponse<S> {
         self
     }
 
-    /// Returns a reference to the extensions of this response.
-    #[inline]
-    pub fn req_data(&self) -> Ref<'_, Extensions> {
-        self.extensions.borrow()
-    }
-
-    /// Returns a mutable reference to the extensions of this response.
-    #[inline]
-    pub fn req_data_mut(&self) -> RefMut<'_, Extensions> {
-        self.extensions.borrow_mut()
-    }
-
     /// Load request cookies.
     #[cfg(feature = "cookies")]
     pub fn cookies(&self) -> Result<Ref<'_, Vec<Cookie<'static>>>, CookieParseError> {
@@ -241,11 +231,11 @@ impl<S> HttpMessage for ClientResponse<S> {
     }
 
     fn extensions(&self) -> Ref<'_, Extensions> {
-        self.req_data()
+        self.extensions.borrow()
     }
 
     fn extensions_mut(&self) -> RefMut<'_, Extensions> {
-        self.req_data_mut()
+        self.extensions.borrow_mut()
     }
 }
 
diff --git a/src/app_service.rs b/src/app_service.rs
index 56b24f0d8..717e53ff7 100644
--- a/src/app_service.rs
+++ b/src/app_service.rs
@@ -18,7 +18,7 @@ use crate::{
         AppServiceFactory, BoxedHttpService, BoxedHttpServiceFactory, ServiceRequest,
         ServiceResponse,
     },
-    Error, HttpResponse,
+    Error, HttpMessage, HttpResponse,
 };
 
 type Guards = Vec<Box<dyn Guard>>;
@@ -201,27 +201,29 @@ where
     actix_service::forward_ready!(service);
 
     fn call(&self, mut req: Request) -> Self::Future {
-        let req_data = Rc::new(RefCell::new(req.take_req_data()));
+        let extensions = Rc::new(RefCell::new(req.take_req_data()));
         let conn_data = req.take_conn_data();
         let (head, payload) = req.into_parts();
 
-        let req = if let Some(mut req) = self.app_state.pool().pop() {
-            let inner = Rc::get_mut(&mut req.inner).unwrap();
-            inner.path.get_mut().update(&head.uri);
-            inner.path.reset();
-            inner.head = head;
-            inner.conn_data = conn_data;
-            inner.req_data = req_data;
-            req
-        } else {
-            HttpRequest::new(
+        let req = match self.app_state.pool().pop() {
+            Some(mut req) => {
+                let inner = Rc::get_mut(&mut req.inner).unwrap();
+                inner.path.get_mut().update(&head.uri);
+                inner.path.reset();
+                inner.head = head;
+                inner.conn_data = conn_data;
+                inner.extensions = extensions;
+                req
+            }
+
+            None => HttpRequest::new(
                 Path::new(Url::new(head.uri.clone())),
                 head,
-                self.app_state.clone(),
-                self.app_data.clone(),
+                Rc::clone(&self.app_state),
+                Rc::clone(&self.app_data),
                 conn_data,
-                req_data,
-            )
+                extensions,
+            ),
         };
 
         self.service.call(ServiceRequest::new(req, payload))
diff --git a/src/request.rs b/src/request.rs
index 2eed75a36..bcab79205 100644
--- a/src/request.rs
+++ b/src/request.rs
@@ -41,7 +41,7 @@ pub(crate) struct HttpRequestInner {
     pub(crate) path: Path<Url>,
     pub(crate) app_data: SmallVec<[Rc<Extensions>; 4]>,
     pub(crate) conn_data: Option<Rc<Extensions>>,
-    pub(crate) req_data: Rc<RefCell<Extensions>>,
+    pub(crate) extensions: Rc<RefCell<Extensions>>,
     app_state: Rc<AppInitServiceState>,
 }
 
@@ -53,7 +53,7 @@ impl HttpRequest {
         app_state: Rc<AppInitServiceState>,
         app_data: Rc<Extensions>,
         conn_data: Option<Rc<Extensions>>,
-        req_data: Rc<RefCell<Extensions>>,
+        extensions: Rc<RefCell<Extensions>>,
     ) -> HttpRequest {
         let mut data = SmallVec::<[Rc<Extensions>; 4]>::new();
         data.push(app_data);
@@ -65,7 +65,7 @@ impl HttpRequest {
                 app_state,
                 app_data: data,
                 conn_data,
-                req_data,
+                extensions,
             }),
         }
     }
@@ -162,14 +162,6 @@ impl HttpRequest {
         self.resource_map().match_name(self.path())
     }
 
-    pub fn req_data(&self) -> Ref<'_, Extensions> {
-        self.inner.req_data.borrow()
-    }
-
-    pub fn req_data_mut(&self) -> RefMut<'_, Extensions> {
-        self.inner.req_data.borrow_mut()
-    }
-
     /// Returns a reference a piece of connection data set in an [on-connect] callback.
     ///
     /// ```ignore
@@ -359,12 +351,12 @@ impl HttpMessage for HttpRequest {
 
     #[inline]
     fn extensions(&self) -> Ref<'_, Extensions> {
-        self.req_data()
+        self.inner.extensions.borrow()
     }
 
     #[inline]
     fn extensions_mut(&self) -> RefMut<'_, Extensions> {
-        self.req_data_mut()
+        self.inner.extensions.borrow_mut()
     }
 
     #[inline]
@@ -385,7 +377,10 @@ impl Drop for HttpRequest {
 
                 // Inner is borrowed mut here and; get req data mutably to reduce borrow check. Also
                 // we know the req_data Rc will not have any cloned at this point to unwrap is okay.
-                Rc::get_mut(&mut inner.req_data).unwrap().get_mut().clear();
+                Rc::get_mut(&mut inner.extensions)
+                    .unwrap()
+                    .get_mut()
+                    .clear();
 
                 // a re-borrow of pool is necessary here.
                 let req = Rc::clone(&self.inner);
diff --git a/src/response/response.rs b/src/response/response.rs
index f24a75b19..74ccbad89 100644
--- a/src/response/response.rs
+++ b/src/response/response.rs
@@ -22,7 +22,7 @@ use {
     cookie::Cookie,
 };
 
-use crate::{error::Error, HttpRequest, HttpResponseBuilder, Responder};
+use crate::{error::Error, HttpMessage, HttpRequest, HttpResponseBuilder, Responder};
 
 /// An outgoing response.
 pub struct HttpResponse<B = BoxBody> {
@@ -216,7 +216,9 @@ impl<B> HttpResponse<B> {
         }
     }
 
-    /// Set a body and return previous body value
+    /// Map the current body type to another using a closure. Returns a new response.
+    ///
+    /// Closure receives the response head and the current body type.
     pub fn map_body<F, B2>(self, f: F) -> HttpResponse<B2>
     where
         F: FnOnce(&mut ResponseHead, B) -> B2,
diff --git a/src/service.rs b/src/service.rs
index 4ca2b518a..b8d6125a9 100644
--- a/src/service.rs
+++ b/src/service.rs
@@ -399,32 +399,32 @@ impl<B> ServiceResponse<B> {
         ServiceResponse::new(self.request, response)
     }
 
-    /// Get reference to original request
+    /// Returns reference to original request.
     #[inline]
     pub fn request(&self) -> &HttpRequest {
         &self.request
     }
 
-    /// Get reference to response
+    /// Returns reference to response.
     #[inline]
     pub fn response(&self) -> &HttpResponse<B> {
         &self.response
     }
 
-    /// Get mutable reference to response
+    /// Returns mutable reference to response.
     #[inline]
     pub fn response_mut(&mut self) -> &mut HttpResponse<B> {
         &mut self.response
     }
 
-    /// Get the response status code
+    /// Returns response status code.
     #[inline]
     pub fn status(&self) -> StatusCode {
         self.response.status()
     }
 
-    #[inline]
     /// Returns response's headers.
+    #[inline]
     pub fn headers(&self) -> &HeaderMap {
         self.response.headers()
     }
@@ -441,13 +441,9 @@ impl<B> ServiceResponse<B> {
         (self.request, self.response)
     }
 
-    /// Extract response body
-    #[inline]
-    pub fn into_body(self) -> B {
-        self.response.into_body()
-    }
-
-    /// Set a new body
+    /// Map the current body type to another using a closure. Returns a new response.
+    ///
+    /// Closure receives the response head and the current body type.
     #[inline]
     pub fn map_body<F, B2>(self, f: F) -> ServiceResponse<B2>
     where
@@ -478,6 +474,12 @@ impl<B> ServiceResponse<B> {
     {
         self.map_body(|_, body| body.boxed())
     }
+
+    /// Consumes the response and returns its body.
+    #[inline]
+    pub fn into_body(self) -> B {
+        self.response.into_body()
+    }
 }
 
 impl<B> From<ServiceResponse<B>> for HttpResponse<B> {