diff --git a/ntex-bytes/src/debug.rs b/ntex-bytes/src/debug.rs
index cd9df0d9..185f2504 100644
--- a/ntex-bytes/src/debug.rs
+++ b/ntex-bytes/src/debug.rs
@@ -31,7 +31,7 @@ impl fmt::Debug for BsDebug<'_> {
             } else if (0x20..0x7f).contains(&c) {
                 write!(fmt, "{}", c as char)?;
             } else {
-                write!(fmt, "\\x{:02x}", c)?;
+                write!(fmt, "\\x{c:02x}")?;
             }
         }
         write!(fmt, "\"")?;
diff --git a/ntex-bytes/src/hex.rs b/ntex-bytes/src/hex.rs
index 3a6fa5c4..46ad1e1f 100644
--- a/ntex-bytes/src/hex.rs
+++ b/ntex-bytes/src/hex.rs
@@ -6,7 +6,7 @@ struct BytesRef<'a>(&'a [u8]);
 impl<'a> LowerHex for BytesRef<'a> {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result {
         for b in self.0 {
-            write!(f, "{:02x}", b)?;
+            write!(f, "{b:02x}")?;
         }
         Ok(())
     }
@@ -15,7 +15,7 @@ impl<'a> LowerHex for BytesRef<'a> {
 impl<'a> UpperHex for BytesRef<'a> {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result {
         for b in self.0 {
-            write!(f, "{:02X}", b)?;
+            write!(f, "{b:02X}")?;
         }
         Ok(())
     }
diff --git a/ntex-io/CHANGES.md b/ntex-io/CHANGES.md
index e4f7968e..50a5671a 100644
--- a/ntex-io/CHANGES.md
+++ b/ntex-io/CHANGES.md
@@ -1,5 +1,9 @@
 # Changes
 
+## [0.2.7] - 2023-01-29
+
+* Refactor buffer api
+
 ## [0.2.6] - 2023-01-27
 
 * Add IoRef::with_rw_buf() helper
diff --git a/ntex-io/Cargo.toml b/ntex-io/Cargo.toml
index fc53c03e..b0a0e80c 100644
--- a/ntex-io/Cargo.toml
+++ b/ntex-io/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "ntex-io"
-version = "0.2.6"
+version = "0.2.7"
 authors = ["ntex contributors <team@ntex.rs>"]
 description = "Utilities for encoding and decoding frames"
 keywords = ["network", "framework", "async", "futures"]
@@ -29,4 +29,4 @@ pin-project-lite = "0.2"
 rand = "0.8"
 env_logger = "0.10"
 
-ntex = { version = "0.6.2", features = ["tokio"] }
+ntex = { version = "0.6.3", features = ["tokio"] }
diff --git a/ntex-io/src/buf.rs b/ntex-io/src/buf.rs
index 3c530da6..2723d310 100644
--- a/ntex-io/src/buf.rs
+++ b/ntex-io/src/buf.rs
@@ -1,14 +1,15 @@
+use std::cell::Cell;
+
 use ntex_bytes::{BytesVec, PoolRef};
 use ntex_util::future::Either;
 
 use crate::IoRef;
 
-type BufferLine = (Option<BytesVec>, Option<BytesVec>);
+type Buffer = (Cell<Option<BytesVec>>, Cell<Option<BytesVec>>);
 
-#[derive(Debug)]
 pub struct Stack {
     len: usize,
-    buffers: Either<[BufferLine; 3], Vec<BufferLine>>,
+    buffers: Either<[Buffer; 3], Vec<Buffer>>,
 }
 
 impl Stack {
@@ -22,153 +23,204 @@ impl Stack {
     pub(crate) fn add_layer(&mut self) {
         match &mut self.buffers {
             Either::Left(b) => {
+                // move to vec
                 if self.len == 3 {
-                    // move to vec
-                    let mut vec = vec![(None, None)];
+                    let mut vec = vec![(Cell::new(None), Cell::new(None))];
                     for item in b.iter_mut().take(self.len) {
-                        vec.push((item.0.take(), item.1.take()));
+                        vec.push((Cell::new(item.0.take()), Cell::new(item.1.take())));
                     }
                     self.len += 1;
                     self.buffers = Either::Right(vec);
                 } else {
                     let mut idx = self.len;
                     while idx > 0 {
-                        let item = (b[idx - 1].0.take(), b[idx - 1].1.take());
+                        let item = (
+                            Cell::new(b[idx - 1].0.take()),
+                            Cell::new(b[idx - 1].1.take()),
+                        );
                         b[idx] = item;
                         idx -= 1;
                     }
-                    b[0] = (None, None);
+                    b[0] = (Cell::new(None), Cell::new(None));
                     self.len += 1;
                 }
             }
             Either::Right(vec) => {
                 self.len += 1;
-                vec.insert(0, (None, None));
+                vec.insert(0, (Cell::new(None), Cell::new(None)));
             }
         }
     }
 
-    fn get_buffers<F, R>(&mut self, idx: usize, f: F) -> R
+    fn get_buffers<F, R>(&self, idx: usize, f: F) -> R
     where
-        F: FnOnce(&mut BufferLine, &mut BufferLine) -> R,
+        F: FnOnce(&Buffer, &Buffer) -> R,
     {
         let buffers = match self.buffers {
-            Either::Left(ref mut b) => &mut b[..],
-            Either::Right(ref mut b) => &mut b[..],
+            Either::Left(ref b) => &b[..],
+            Either::Right(ref b) => &b[..],
         };
 
-        let pos = idx + 1;
-        if self.len > pos {
-            let (curr, next) = buffers.split_at_mut(pos);
-            f(&mut curr[idx], &mut next[0])
+        let next = idx + 1;
+        if self.len > next {
+            f(&buffers[idx], &buffers[next])
         } else {
-            let mut curr = (buffers[idx].0.take(), None);
-            let mut next = (None, buffers[idx].1.take());
+            let curr = (Cell::new(buffers[idx].0.take()), Cell::new(None));
+            let next = (Cell::new(None), Cell::new(buffers[idx].1.take()));
 
-            let result = f(&mut curr, &mut next);
-            buffers[idx].0 = curr.0;
-            buffers[idx].1 = next.1;
+            let result = f(&curr, &next);
+            buffers[idx].0.set(curr.0.take());
+            buffers[idx].1.set(next.1.take());
             result
         }
     }
 
-    fn get_first_level(&mut self) -> &mut BufferLine {
-        match &mut self.buffers {
-            Either::Left(b) => &mut b[0],
-            Either::Right(b) => &mut b[0],
+    fn get_first_level(&self) -> &Buffer {
+        match &self.buffers {
+            Either::Left(b) => &b[0],
+            Either::Right(b) => &b[0],
         }
     }
 
-    fn get_last_level(&mut self) -> &mut BufferLine {
-        match &mut self.buffers {
-            Either::Left(b) => &mut b[self.len - 1],
-            Either::Right(b) => &mut b[self.len - 1],
+    fn get_last_level(&self) -> &Buffer {
+        match &self.buffers {
+            Either::Left(b) => &b[self.len - 1],
+            Either::Right(b) => &b[self.len - 1],
         }
     }
 
-    pub(crate) fn read_buf<F, R>(
-        &mut self,
-        io: &IoRef,
-        idx: usize,
-        nbytes: usize,
-        f: F,
-    ) -> R
+    pub(crate) fn read_buf<F, R>(&self, io: &IoRef, idx: usize, nbytes: usize, f: F) -> R
     where
-        F: FnOnce(&mut ReadBuf<'_>) -> R,
+        F: FnOnce(&ReadBuf<'_>) -> R,
     {
         self.get_buffers(idx, |curr, next| {
-            let mut buf = ReadBuf {
+            let buf = ReadBuf {
                 io,
                 nbytes,
                 curr,
                 next,
-                need_write: false,
+                need_write: Cell::new(false),
             };
-            f(&mut buf)
+            f(&buf)
         })
     }
 
-    pub(crate) fn write_buf<F, R>(&mut self, io: &IoRef, idx: usize, f: F) -> R
+    pub(crate) fn write_buf<F, R>(&self, io: &IoRef, idx: usize, f: F) -> R
     where
-        F: FnOnce(&mut WriteBuf<'_>) -> R,
+        F: FnOnce(&WriteBuf<'_>) -> R,
     {
         self.get_buffers(idx, |curr, next| {
-            let mut buf = WriteBuf {
+            let buf = WriteBuf {
                 io,
                 curr,
                 next,
-                need_write: false,
+                need_write: Cell::new(false),
             };
-            f(&mut buf)
+            f(&buf)
         })
     }
 
-    pub(crate) fn first_read_buf_size(&mut self) -> usize {
-        self.get_first_level()
-            .0
-            .as_ref()
-            .map(|b| b.len())
-            .unwrap_or(0)
-    }
-
-    pub(crate) fn with_rw_buf<F, R>(&mut self, io: &IoRef, f: F) -> R
+    pub(crate) fn with_read_source<F, R>(&self, io: &IoRef, f: F) -> R
     where
-        F: FnOnce(&mut BytesVec, &mut BytesVec) -> R,
+        F: FnOnce(&mut BytesVec) -> R,
     {
-        let lvl = self.get_first_level();
-        if lvl.0.is_none() {
-            lvl.0 = Some(io.memory_pool().get_read_buf());
+        let item = self.get_last_level();
+        let mut rb = item.0.take();
+        if rb.is_none() {
+            rb = Some(io.memory_pool().get_read_buf());
         }
-        if lvl.1.is_none() {
-            lvl.1 = Some(io.memory_pool().get_write_buf());
+
+        let result = f(rb.as_mut().unwrap());
+        if let Some(b) = rb {
+            if b.is_empty() {
+                io.memory_pool().release_read_buf(b);
+            } else {
+                item.0.set(Some(b));
+            }
         }
-        f(lvl.0.as_mut().unwrap(), lvl.1.as_mut().unwrap())
+        result
     }
 
-    pub(crate) fn first_read_buf(&mut self) -> &mut Option<BytesVec> {
-        &mut self.get_first_level().0
-    }
-
-    pub(crate) fn first_write_buf(&mut self, io: &IoRef) -> &mut BytesVec {
-        let item = &mut self.get_first_level().1;
-        if item.is_none() {
-            *item = Some(io.memory_pool().get_write_buf());
+    pub(crate) fn with_read_destination<F, R>(&self, io: &IoRef, f: F) -> R
+    where
+        F: FnOnce(&mut BytesVec) -> R,
+    {
+        let item = self.get_first_level();
+        let mut rb = item.0.take();
+        if rb.is_none() {
+            rb = Some(io.memory_pool().get_read_buf());
         }
-        item.as_mut().unwrap()
+
+        let result = f(rb.as_mut().unwrap());
+        if let Some(b) = rb {
+            if b.is_empty() {
+                io.memory_pool().release_read_buf(b);
+            } else {
+                item.0.set(Some(b));
+            }
+        }
+        result
     }
 
-    pub(crate) fn last_read_buf(&mut self) -> &mut Option<BytesVec> {
-        &mut self.get_last_level().0
+    pub(crate) fn with_write_source<F, R>(&self, io: &IoRef, f: F) -> R
+    where
+        F: FnOnce(&mut BytesVec) -> R,
+    {
+        let item = self.get_first_level();
+        let mut wb = item.1.take();
+        if wb.is_none() {
+            wb = Some(io.memory_pool().get_write_buf());
+        }
+
+        let result = f(wb.as_mut().unwrap());
+        if let Some(b) = wb {
+            if b.is_empty() {
+                io.memory_pool().release_write_buf(b);
+            } else {
+                item.1.set(Some(b));
+            }
+        }
+        result
     }
 
-    pub(crate) fn last_write_buf(&mut self) -> &mut Option<BytesVec> {
-        &mut self.get_last_level().1
+    pub(crate) fn with_write_destination<F, R>(&self, io: &IoRef, f: F) -> R
+    where
+        F: FnOnce(&mut Option<BytesVec>) -> R,
+    {
+        let item = self.get_last_level();
+        let mut wb = item.1.take();
+
+        let result = f(&mut wb);
+        if let Some(b) = wb {
+            if b.is_empty() {
+                io.memory_pool().release_write_buf(b);
+            } else {
+                item.1.set(Some(b));
+            }
+        }
+        result
     }
 
-    pub(crate) fn release(&mut self, pool: PoolRef) {
-        let items = match &mut self.buffers {
-            Either::Left(b) => &mut b[..],
-            Either::Right(b) => &mut b[..],
+    pub(crate) fn read_destination_size(&self) -> usize {
+        let item = self.get_first_level();
+        let rb = item.0.take();
+        let size = rb.as_ref().map(|b| b.len()).unwrap_or(0);
+        item.0.set(rb);
+        size
+    }
+
+    pub(crate) fn write_destination_size(&self) -> usize {
+        let item = self.get_last_level();
+        let wb = item.1.take();
+        let size = wb.as_ref().map(|b| b.len()).unwrap_or(0);
+        item.1.set(wb);
+        size
+    }
+
+    pub(crate) fn release(&self, pool: PoolRef) {
+        let items = match &self.buffers {
+            Either::Left(b) => &b[..],
+            Either::Right(b) => &b[..],
         };
 
         for item in items {
@@ -181,29 +233,31 @@ impl Stack {
         }
     }
 
-    pub(crate) fn set_memory_pool(&mut self, pool: PoolRef) {
-        let items = match &mut self.buffers {
-            Either::Left(b) => &mut b[..],
-            Either::Right(b) => &mut b[..],
+    pub(crate) fn set_memory_pool(&self, pool: PoolRef) {
+        let items = match &self.buffers {
+            Either::Left(b) => &b[..],
+            Either::Right(b) => &b[..],
         };
-        for buf in items {
-            if let Some(ref mut b) = buf.0 {
-                pool.move_vec_in(b);
+        for item in items {
+            if let Some(mut b) = item.0.take() {
+                pool.move_vec_in(&mut b);
+                item.0.set(Some(b));
             }
-            if let Some(ref mut b) = buf.1 {
-                pool.move_vec_in(b);
+            if let Some(mut b) = item.1.take() {
+                pool.move_vec_in(&mut b);
+                item.1.set(Some(b));
             }
         }
     }
 }
 
-#[derive(Debug)]
+// #[derive(Debug)]
 pub struct ReadBuf<'a> {
     pub(crate) io: &'a IoRef,
-    pub(crate) curr: &'a mut BufferLine,
-    pub(crate) next: &'a mut BufferLine,
+    pub(crate) curr: &'a Buffer,
+    pub(crate) next: &'a Buffer,
     pub(crate) nbytes: usize,
-    pub(crate) need_write: bool,
+    pub(crate) need_write: Cell<bool>,
 }
 
 impl<'a> ReadBuf<'a> {
@@ -219,27 +273,68 @@ impl<'a> ReadBuf<'a> {
         self.io.want_shutdown()
     }
 
+    #[inline]
+    /// Make sure buffer has enough free space
+    pub fn resize_buf(&self, buf: &mut BytesVec) {
+        self.io.memory_pool().resize_read_buf(buf);
+    }
+
     #[inline]
     /// Get reference to source read buffer
-    pub fn get_src(&mut self) -> &mut BytesVec {
-        if self.next.0.is_none() {
-            self.next.0 = Some(self.io.memory_pool().get_read_buf());
+    pub fn with_src<F, R>(&self, f: F) -> R
+    where
+        F: FnOnce(&mut Option<BytesVec>) -> R,
+    {
+        let mut item = self.next.0.take();
+        let result = f(&mut item);
+
+        if let Some(b) = item {
+            if b.is_empty() {
+                self.io.memory_pool().release_read_buf(b);
+            } else {
+                self.next.0.set(Some(b));
+            }
         }
-        self.next.0.as_mut().unwrap()
+        result
+    }
+
+    #[inline]
+    /// Get reference to destination read buffer
+    pub fn with_dst<F, R>(&self, f: F) -> R
+    where
+        F: FnOnce(&mut BytesVec) -> R,
+    {
+        let mut item = self.curr.0.take();
+        if item.is_none() {
+            item = Some(self.io.memory_pool().get_read_buf());
+        }
+        let result = f(item.as_mut().unwrap());
+        if let Some(b) = item {
+            if b.is_empty() {
+                self.io.memory_pool().release_read_buf(b);
+            } else {
+                self.curr.0.set(Some(b));
+            }
+        }
+        result
     }
 
     #[inline]
     /// Take source read buffer
-    pub fn take_src(&mut self) -> Option<BytesVec> {
-        self.next
-            .0
-            .take()
-            .and_then(|b| if b.is_empty() { None } else { Some(b) })
+    pub fn take_src(&self) -> Option<BytesVec> {
+        self.next.0.take().and_then(|b| {
+            if b.is_empty() {
+                self.io.memory_pool().release_read_buf(b);
+                None
+            } else {
+                Some(b)
+            }
+        })
     }
 
     #[inline]
     /// Set source read buffer
-    pub fn set_src(&mut self, src: Option<BytesVec>) {
+    pub fn set_src(&self, src: Option<BytesVec>) {
         if let Some(buf) = self.next.0.take() {
             self.io.memory_pool().release_read_buf(buf);
         }
@@ -247,23 +342,14 @@ impl<'a> ReadBuf<'a> {
             if src.is_empty() {
                 self.io.memory_pool().release_read_buf(src);
             } else {
-                self.next.0 = Some(src);
+                self.next.0.set(Some(src));
             }
         }
     }
 
-    #[inline]
-    /// Get reference to destination read buffer
-    pub fn get_dst(&mut self) -> &mut BytesVec {
-        if self.curr.0.is_none() {
-            self.curr.0 = Some(self.io.memory_pool().get_read_buf());
-        }
-        self.curr.0.as_mut().unwrap()
-    }
-
     #[inline]
     /// Take destination read buffer
-    pub fn take_dst(&mut self) -> BytesVec {
+    pub fn take_dst(&self) -> BytesVec {
         self.curr
             .0
             .take()
@@ -272,7 +358,7 @@ impl<'a> ReadBuf<'a> {
 
     #[inline]
     /// Set destination read buffer
-    pub fn set_dst(&mut self, dst: Option<BytesVec>) {
+    pub fn set_dst(&self, dst: Option<BytesVec>) {
         if let Some(buf) = self.curr.0.take() {
             self.io.memory_pool().release_read_buf(buf);
         }
@@ -280,46 +366,34 @@ impl<'a> ReadBuf<'a> {
             if dst.is_empty() {
                 self.io.memory_pool().release_read_buf(dst);
             } else {
-                self.curr.0 = Some(dst);
+                self.curr.0.set(Some(dst));
             }
         }
     }
 
     #[inline]
-    /// Get reference to source and destination read buffers (src, dst)
-    pub fn get_pair(&mut self) -> (&mut BytesVec, &mut BytesVec) {
-        if self.next.0.is_none() {
-            self.next.0 = Some(self.io.memory_pool().get_read_buf());
-        }
-        if self.curr.0.is_none() {
-            self.curr.0 = Some(self.io.memory_pool().get_read_buf());
-        }
-        (self.next.0.as_mut().unwrap(), self.curr.0.as_mut().unwrap())
-    }
-
-    #[inline]
-    pub fn with_write_buf<'b, F, R>(&'b mut self, f: F) -> R
+    pub fn with_write_buf<'b, F, R>(&'b self, f: F) -> R
     where
-        F: FnOnce(&mut WriteBuf<'b>) -> R,
+        F: FnOnce(&WriteBuf<'b>) -> R,
     {
         let mut buf = WriteBuf {
             io: self.io,
             curr: self.curr,
             next: self.next,
-            need_write: self.need_write,
+            need_write: Cell::new(self.need_write.get()),
         };
         let result = f(&mut buf);
-        self.need_write = buf.need_write;
+        self.need_write.set(buf.need_write.get());
         result
     }
 }
 
-#[derive(Debug)]
+// #[derive(Debug)]
 pub struct WriteBuf<'a> {
     pub(crate) io: &'a IoRef,
-    pub(crate) curr: &'a mut BufferLine,
-    pub(crate) next: &'a mut BufferLine,
-    pub(crate) need_write: bool,
+    pub(crate) curr: &'a Buffer,
+    pub(crate) next: &'a Buffer,
+    pub(crate) need_write: Cell<bool>,
 }
 
 impl<'a> WriteBuf<'a> {
@@ -329,57 +403,85 @@ impl<'a> WriteBuf<'a> {
         self.io.want_shutdown()
     }
 
+    #[inline]
+    /// Make sure buffer has enough free space
+    pub fn resize_buf(&self, buf: &mut BytesVec) {
+        self.io.memory_pool().resize_write_buf(buf);
+    }
+
     #[inline]
     /// Get reference to source write buffer
-    pub fn get_src(&mut self) -> &mut BytesVec {
-        if self.curr.1.is_none() {
-            self.curr.1 = Some(self.io.memory_pool().get_write_buf());
+    pub fn with_src<F, R>(&self, f: F) -> R
+    where
+        F: FnOnce(&mut Option<BytesVec>) -> R,
+    {
+        let mut item = self.curr.1.take();
+        let result = f(&mut item);
+        if let Some(b) = item {
+            if b.is_empty() {
+                self.io.memory_pool().release_write_buf(b);
+            } else {
+                self.curr.1.set(Some(b));
+            }
         }
-        self.curr.1.as_mut().unwrap()
+        result
+    }
+
+    #[inline]
+    /// Get reference to destination write buffer
+    pub fn with_dst<F, R>(&self, f: F) -> R
+    where
+        F: FnOnce(&mut BytesVec) -> R,
+    {
+        let mut item = self.next.1.take();
+        if item.is_none() {
+            item = Some(self.io.memory_pool().get_write_buf());
+        }
+        let buf = item.as_mut().unwrap();
+        let total = buf.len();
+        let result = f(buf);
+
+        if buf.is_empty() {
+            self.io.memory_pool().release_write_buf(item.unwrap());
+        } else {
+            self.need_write
+                .set(self.need_write.get() | (total != buf.len()));
+            self.next.1.set(item);
+        }
+        result
     }
 
     #[inline]
     /// Take source write buffer
-    pub fn take_src(&mut self) -> Option<BytesVec> {
-        self.curr
-            .1
-            .take()
-            .and_then(|b| if b.is_empty() { None } else { Some(b) })
+    pub fn take_src(&self) -> Option<BytesVec> {
+        self.curr.1.take().and_then(|b| {
+            if b.is_empty() {
+                self.io.memory_pool().release_write_buf(b);
+                None
+            } else {
+                Some(b)
+            }
+        })
     }
 
     #[inline]
     /// Set source write buffer
-    pub fn set_src(&mut self, src: Option<BytesVec>) {
+    pub fn set_src(&self, src: Option<BytesVec>) {
         if let Some(buf) = self.curr.1.take() {
-            self.io.memory_pool().release_read_buf(buf);
+            self.io.memory_pool().release_write_buf(buf);
         }
         if let Some(buf) = src {
             if buf.is_empty() {
-                self.io.memory_pool().release_read_buf(buf);
+                self.io.memory_pool().release_write_buf(buf);
             } else {
-                self.curr.1 = Some(buf);
+                self.curr.1.set(Some(buf));
             }
         }
     }
 
-    #[inline]
-    /// Get reference to destination write buffer
-    pub fn with_dst_buf<F, R>(&mut self, f: F) -> R
-    where
-        F: FnOnce(&mut BytesVec) -> R,
-    {
-        if self.next.1.is_none() {
-            self.next.1 = Some(self.io.memory_pool().get_write_buf());
-        }
-        let buf = self.next.1.as_mut().unwrap();
-        let r = f(buf);
-        self.need_write |= !buf.is_empty();
-        r
-    }
-
     #[inline]
     /// Take destination write buffer
-    pub fn take_dst(&mut self) -> BytesVec {
+    pub fn take_dst(&self) -> BytesVec {
         self.next
             .1
             .take()
@@ -388,7 +490,7 @@ impl<'a> WriteBuf<'a> {
 
     #[inline]
     /// Set destination write buffer
-    pub fn set_dst(&mut self, dst: Option<BytesVec>) {
+    pub fn set_dst(&self, dst: Option<BytesVec>) {
         if let Some(buf) = self.next.1.take() {
             self.io.memory_pool().release_write_buf(buf);
         }
@@ -396,26 +498,26 @@ impl<'a> WriteBuf<'a> {
             if dst.is_empty() {
                 self.io.memory_pool().release_write_buf(dst);
             } else {
-                self.need_write |= !dst.is_empty();
-                self.next.1 = Some(dst);
+                self.need_write.set(self.need_write.get() | !dst.is_empty());
+                self.next.1.set(Some(dst));
             }
         }
     }
 
     #[inline]
-    pub fn with_read_buf<'b, F, R>(&'b mut self, f: F) -> R
+    pub fn with_read_buf<'b, F, R>(&'b self, f: F) -> R
     where
-        F: FnOnce(&mut ReadBuf<'b>) -> R,
+        F: FnOnce(&ReadBuf<'b>) -> R,
     {
         let mut buf = ReadBuf {
             io: self.io,
             curr: self.curr,
             next: self.next,
             nbytes: 0,
-            need_write: self.need_write,
+            need_write: Cell::new(self.need_write.get()),
         };
         let result = f(&mut buf);
-        self.need_write = buf.need_write;
+        self.need_write.set(buf.need_write.get());
         result
     }
 }
diff --git a/ntex-io/src/filter.rs b/ntex-io/src/filter.rs
index a69b2cba..7ebe2729 100644
--- a/ntex-io/src/filter.rs
+++ b/ntex-io/src/filter.rs
@@ -41,21 +41,16 @@ pub trait Filter: 'static {
     fn process_read_buf(
         &self,
         io: &IoRef,
-        stack: &mut Stack,
+        stack: &Stack,
         idx: usize,
         nbytes: usize,
     ) -> io::Result<FilterReadStatus>;
 
     /// Process write buffer
-    fn process_write_buf(
-        &self,
-        io: &IoRef,
-        stack: &mut Stack,
-        idx: usize,
-    ) -> io::Result<()>;
+    fn process_write_buf(&self, io: &IoRef, stack: &Stack, idx: usize) -> io::Result<()>;
 
     /// Gracefully shutdown filter
-    fn shutdown(&self, io: &IoRef, stack: &mut Stack, idx: usize) -> io::Result<Poll<()>>;
+    fn shutdown(&self, io: &IoRef, stack: &Stack, idx: usize) -> io::Result<Poll<()>>;
 
     /// Check readiness for read operations
     fn poll_read_ready(&self, cx: &mut Context<'_>) -> Poll<ReadStatus>;
@@ -115,7 +110,7 @@ impl Filter for Base {
     fn process_read_buf(
         &self,
         _: &IoRef,
-        _: &mut Stack,
+        _: &Stack,
         _: usize,
         nbytes: usize,
     ) -> io::Result<FilterReadStatus> {
@@ -126,22 +121,24 @@ impl Filter for Base {
     }
 
     #[inline]
-    fn process_write_buf(&self, _: &IoRef, s: &mut Stack, _: usize) -> io::Result<()> {
-        if let Some(buf) = s.last_write_buf() {
-            let len = buf.len();
-            if len > 0 && self.0.flags().contains(Flags::WR_PAUSED) {
-                self.0 .0.remove_flags(Flags::WR_PAUSED);
-                self.0 .0.write_task.wake();
+    fn process_write_buf(&self, io: &IoRef, s: &Stack, _: usize) -> io::Result<()> {
+        s.with_write_destination(io, |buf| {
+            if let Some(buf) = buf {
+                let len = buf.len();
+                if len > 0 && self.0.flags().contains(Flags::WR_PAUSED) {
+                    self.0 .0.remove_flags(Flags::WR_PAUSED);
+                    self.0 .0.write_task.wake();
+                }
+                if len >= self.0.memory_pool().write_params_high() {
+                    self.0 .0.insert_flags(Flags::WR_BACKPRESSURE);
+                }
             }
-            if len >= self.0.memory_pool().write_params_high() {
-                self.0 .0.insert_flags(Flags::WR_BACKPRESSURE);
-            }
-        }
+        });
         Ok(())
     }
 
     #[inline]
-    fn shutdown(&self, _: &IoRef, _: &mut Stack, _: usize) -> io::Result<Poll<()>> {
+    fn shutdown(&self, _: &IoRef, _: &Stack, _: usize) -> io::Result<Poll<()>> {
         Ok(Poll::Ready(()))
     }
 }
@@ -157,7 +154,7 @@ where
     }
 
     #[inline]
-    fn shutdown(&self, io: &IoRef, stack: &mut Stack, idx: usize) -> io::Result<Poll<()>> {
+    fn shutdown(&self, io: &IoRef, stack: &Stack, idx: usize) -> io::Result<Poll<()>> {
         let result1 = stack.write_buf(io, idx, |buf| self.0.shutdown(buf))?;
         self.process_write_buf(io, stack, idx)?;
 
@@ -178,7 +175,7 @@ where
     fn process_read_buf(
         &self,
         io: &IoRef,
-        stack: &mut Stack,
+        stack: &Stack,
         idx: usize,
         nbytes: usize,
     ) -> io::Result<FilterReadStatus> {
@@ -190,18 +187,13 @@ where
         stack.read_buf(io, idx, status.nbytes, |buf| {
             self.0.process_read_buf(buf).map(|nbytes| FilterReadStatus {
                 nbytes,
-                need_write: status.need_write || buf.need_write,
+                need_write: status.need_write || buf.need_write.get(),
             })
         })
     }
 
     #[inline]
-    fn process_write_buf(
-        &self,
-        io: &IoRef,
-        stack: &mut Stack,
-        idx: usize,
-    ) -> io::Result<()> {
+    fn process_write_buf(&self, io: &IoRef, stack: &Stack, idx: usize) -> io::Result<()> {
         stack.write_buf(io, idx, |buf| self.0.process_write_buf(buf))?;
 
         if F::BUFFERS {
@@ -270,7 +262,7 @@ impl Filter for NullFilter {
     fn process_read_buf(
         &self,
         _: &IoRef,
-        _: &mut Stack,
+        _: &Stack,
         _: usize,
         _: usize,
     ) -> io::Result<FilterReadStatus> {
@@ -278,12 +270,12 @@ impl Filter for NullFilter {
     }
 
     #[inline]
-    fn process_write_buf(&self, _: &IoRef, _: &mut Stack, _: usize) -> io::Result<()> {
+    fn process_write_buf(&self, _: &IoRef, _: &Stack, _: usize) -> io::Result<()> {
         Ok(())
     }
 
     #[inline]
-    fn shutdown(&self, _: &IoRef, _: &mut Stack, _: usize) -> io::Result<Poll<()>> {
+    fn shutdown(&self, _: &IoRef, _: &Stack, _: usize) -> io::Result<Poll<()>> {
         Ok(Poll::Ready(()))
     }
 }
diff --git a/ntex-io/src/io.rs b/ntex-io/src/io.rs
index 41c08361..5be0d46e 100644
--- a/ntex-io/src/io.rs
+++ b/ntex-io/src/io.rs
@@ -1,4 +1,4 @@
-use std::cell::{Cell, RefCell};
+use std::cell::Cell;
 use std::task::{Context, Poll};
 use std::{fmt, future::Future, hash, io, marker, mem, ops, pin::Pin, ptr, rc::Rc, time};
 
@@ -62,7 +62,7 @@ pub(crate) struct IoState {
     pub(super) read_task: LocalWaker,
     pub(super) write_task: LocalWaker,
     pub(super) dispatch_task: LocalWaker,
-    pub(super) buffer: RefCell<Stack>,
+    pub(super) buffer: Stack,
     pub(super) filter: Cell<&'static dyn Filter>,
     pub(super) handle: Cell<Option<Box<dyn Handle>>>,
     #[allow(clippy::box_collection)]
@@ -149,7 +149,7 @@ impl hash::Hash for IoState {
 impl Drop for IoState {
     #[inline]
     fn drop(&mut self) {
-        self.buffer.borrow_mut().release(self.pool.get());
+        self.buffer.release(self.pool.get());
     }
 }
 
@@ -171,7 +171,7 @@ impl Io {
             dispatch_task: LocalWaker::new(),
             read_task: LocalWaker::new(),
             write_task: LocalWaker::new(),
-            buffer: RefCell::new(Stack::new()),
+            buffer: Stack::new(),
             filter: Cell::new(NullFilter::get()),
             handle: Cell::new(None),
             on_disconnect: Cell::new(None),
@@ -199,7 +199,7 @@ impl<F> Io<F> {
     #[inline]
     /// Set memory pool
     pub fn set_memory_pool(&self, pool: PoolRef) {
-        self.0 .0.buffer.borrow_mut().set_memory_pool(pool);
+        self.0 .0.buffer.set_memory_pool(pool);
         self.0 .0.pool.set(pool);
     }
 
@@ -227,7 +227,7 @@ impl<F> Io<F> {
             dispatch_task: LocalWaker::new(),
             read_task: LocalWaker::new(),
             write_task: LocalWaker::new(),
-            buffer: RefCell::new(Stack::new()),
+            buffer: Stack::new(),
             filter: Cell::new(NullFilter::get()),
             handle: Cell::new(None),
             on_disconnect: Cell::new(None),
@@ -292,7 +292,12 @@ impl<F: Filter> Io<F> {
     {
         // add layer to buffers
         if U::BUFFERS {
-            self.0 .0.buffer.borrow_mut().add_layer();
+            // Safety: .add_layer() modifies internal buffers
+            // there is no api that holds references into buffers storage
+            // all apis first removes buffer from storage and then work with it
+            unsafe { &mut *(Rc::as_ptr(&self.0 .0) as *mut IoState) }
+                .buffer
+                .add_layer();
         }
 
         // replace current filter
@@ -489,14 +494,7 @@ impl<F> Io<F> {
             Poll::Ready(self.error().map(Err).unwrap_or(Ok(())))
         } else {
             let inner = &self.0 .0;
-            let len = inner
-                .buffer
-                .borrow_mut()
-                .last_write_buf()
-                .as_ref()
-                .map(|b| b.len())
-                .unwrap_or(0);
-
+            let len = inner.buffer.write_destination_size();
             if len > 0 {
                 if full {
                     inner.insert_flags(Flags::WR_WAIT);
diff --git a/ntex-io/src/ioref.rs b/ntex-io/src/ioref.rs
index 0f271ea6..66205de0 100644
--- a/ntex-io/src/ioref.rs
+++ b/ntex-io/src/ioref.rs
@@ -1,9 +1,9 @@
-use std::{any, cell, fmt, hash, io, time};
+use std::{any, fmt, hash, io, time};
 
 use ntex_bytes::{BytesVec, PoolRef};
 use ntex_codec::{Decoder, Encoder};
 
-use super::{buf::Stack, io::Flags, timer, types, Filter, IoRef, OnDisconnect, WriteBuf};
+use super::{io::Flags, timer, types, Filter, IoRef, OnDisconnect, WriteBuf};
 
 impl IoRef {
     #[inline]
@@ -132,11 +132,9 @@ impl IoRef {
     where
         U: Decoder,
     {
-        borrow_buffer(&self.0.buffer)
-            .first_read_buf()
-            .as_mut()
-            .map(|b| codec.decode_vec(b))
-            .unwrap_or(Ok(None))
+        self.0
+            .buffer
+            .with_read_destination(self, |buf| codec.decode_vec(buf))
     }
 
     #[inline]
@@ -152,59 +150,40 @@ impl IoRef {
     }
 
     #[inline]
-    /// Get mut access to write buffer
+    /// Get access to write buffer
     pub fn with_buf<F, R>(&self, f: F) -> io::Result<R>
     where
-        F: FnOnce(&mut WriteBuf<'_>) -> R,
+        F: FnOnce(&WriteBuf<'_>) -> R,
     {
-        let mut buffer = borrow_buffer(&self.0.buffer);
-        let result = buffer.write_buf(self, 0, f);
+        let result = self.0.buffer.write_buf(self, 0, f);
         self.0
             .filter
             .get()
-            .process_write_buf(self, &mut buffer, 0)?;
+            .process_write_buf(self, &self.0.buffer, 0)?;
         Ok(result)
     }
 
     #[inline]
-    /// Get mut access to write buffer
+    /// Get mut access to source write buffer
     pub fn with_write_buf<F, R>(&self, f: F) -> io::Result<R>
     where
         F: FnOnce(&mut BytesVec) -> R,
     {
-        let mut buffer = borrow_buffer(&self.0.buffer);
-        let result = f(buffer.first_write_buf(self));
+        let result = self.0.buffer.with_write_source(self, f);
         self.0
             .filter
             .get()
-            .process_write_buf(self, &mut buffer, 0)?;
-
+            .process_write_buf(self, &self.0.buffer, 0)?;
         Ok(result)
     }
 
     #[inline]
-    /// Get mut access to read buffer
+    /// Get mut access to source read buffer
     pub fn with_read_buf<F, R>(&self, f: F) -> R
     where
         F: FnOnce(&mut BytesVec) -> R,
     {
-        // use top most buffer
-        let mut buffer = borrow_buffer(&self.0.buffer);
-        let buf = buffer.first_read_buf();
-        if buf.is_none() {
-            *buf = Some(self.memory_pool().get_read_buf());
-        }
-
-        f(buf.as_mut().unwrap())
-    }
-
-    #[inline]
-    /// Get mut access to read and write buffer
-    pub fn with_rw_buf<F, R>(&self, f: F) -> R
-    where
-        F: FnOnce(&mut BytesVec, &mut BytesVec) -> R,
-    {
-        borrow_buffer(&self.0.buffer).with_rw_buf(self, f)
+        self.0.buffer.with_read_destination(self, f)
     }
 
     #[inline]
@@ -260,14 +239,6 @@ impl fmt::Debug for IoRef {
     }
 }
 
-fn borrow_buffer(buf: &cell::RefCell<Stack>) -> cell::RefMut<'_, Stack> {
-    if let Ok(r) = buf.try_borrow_mut() {
-        r
-    } else {
-        panic!("Nested access to read/write buffers are not allowed");
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use std::cell::{Cell, RefCell};
@@ -411,16 +382,16 @@ mod tests {
     impl FilterLayer for Counter {
         const BUFFERS: bool = false;
 
-        fn process_read_buf(&self, buf: &mut ReadBuf<'_>) -> io::Result<usize> {
+        fn process_read_buf(&self, buf: &ReadBuf<'_>) -> io::Result<usize> {
             self.read_order.borrow_mut().push(self.idx);
             self.in_bytes.set(self.in_bytes.get() + buf.nbytes());
             Ok(buf.nbytes())
         }
 
-        fn process_write_buf(&self, buf: &mut WriteBuf<'_>) -> io::Result<()> {
+        fn process_write_buf(&self, buf: &WriteBuf<'_>) -> io::Result<()> {
             self.write_order.borrow_mut().push(self.idx);
             self.out_bytes
-                .set(self.out_bytes.get() + buf.with_dst_buf(|b| b.len()));
+                .set(self.out_bytes.get() + buf.with_dst(|b| b.len()));
             Ok(())
         }
     }
diff --git a/ntex-io/src/lib.rs b/ntex-io/src/lib.rs
index 533354ff..1bba316b 100644
--- a/ntex-io/src/lib.rs
+++ b/ntex-io/src/lib.rs
@@ -71,10 +71,10 @@ pub trait FilterLayer: 'static {
     ///
     /// Inner filter must process buffer before current.
     /// Returns number of new bytes.
-    fn process_read_buf(&self, buf: &mut ReadBuf<'_>) -> sio::Result<usize>;
+    fn process_read_buf(&self, buf: &ReadBuf<'_>) -> sio::Result<usize>;
 
     /// Process write buffer
-    fn process_write_buf(&self, buf: &mut WriteBuf<'_>) -> sio::Result<()>;
+    fn process_write_buf(&self, buf: &WriteBuf<'_>) -> sio::Result<()>;
 
     #[inline]
     /// Query internal filter data
@@ -84,7 +84,7 @@ pub trait FilterLayer: 'static {
 
     #[inline]
     /// Gracefully shutdown filter
-    fn shutdown(&self, buf: &mut WriteBuf<'_>) -> sio::Result<Poll<()>> {
+    fn shutdown(&self, buf: &WriteBuf<'_>) -> sio::Result<Poll<()>> {
         Ok(Poll::Ready(()))
     }
 }
diff --git a/ntex-io/src/tasks.rs b/ntex-io/src/tasks.rs
index e3b493c9..4b80bdbc 100644
--- a/ntex-io/src/tasks.rs
+++ b/ntex-io/src/tasks.rs
@@ -24,71 +24,59 @@ impl ReadContext {
         F: FnOnce(&mut BytesVec, usize, usize) -> Poll<io::Result<()>>,
     {
         let inner = &self.0 .0;
-        let mut stack = inner.buffer.borrow_mut();
-        let mut buf = stack
-            .last_read_buf()
-            .take()
-            .unwrap_or_else(|| self.0.memory_pool().get_read_buf());
-
-        let total = buf.len();
         let (hw, lw) = self.0.memory_pool().read_params().unpack();
+        let (result, nbytes, total) = inner.buffer.with_read_source(&self.0, |buf| {
+            let total = buf.len();
 
-        // call provided callback
-        let result = f(&mut buf, hw, lw);
-
-        // handle buffer changes
-        if buf.is_empty() {
-            self.0.memory_pool().release_read_buf(buf);
-        } else {
+            // call provided callback
+            let result = f(buf, hw, lw);
             let total2 = buf.len();
             let nbytes = if total2 > total { total2 - total } else { 0 };
-            *stack.last_read_buf() = Some(buf);
+            (result, nbytes, total2)
+        });
 
-            if nbytes > 0 {
-                let buf_full = nbytes >= hw;
-                let filter = self.0.filter();
-                let _ = filter.process_read_buf(&self.0, &mut stack, 0, nbytes)
-                    .and_then(|status| {
-                        if status.nbytes > 0 {
-                            if buf_full || stack.first_read_buf_size() >= hw {
-                                log::trace!(
-                                    "io read buffer is too large {}, enable read back-pressure",
-                                    total2
-                                );
-                                inner.insert_flags(Flags::RD_READY | Flags::RD_BUF_FULL);
-                            } else {
-                                inner.insert_flags(Flags::RD_READY);
-                            }
+        // handle buffer changes
+        if nbytes > 0 {
+            let buf_full = nbytes >= hw;
+            let filter = self.0.filter();
+            let _ = filter
+                .process_read_buf(&self.0, &inner.buffer, 0, nbytes)
+                .and_then(|status| {
+                    if status.nbytes > 0 {
+                        if buf_full || inner.buffer.read_destination_size() >= hw {
                             log::trace!(
-                                "new {} bytes available, wakeup dispatcher",
-                                nbytes,
+                                "io read buffer is too large {}, enable read back-pressure",
+                                total
                             );
-                            inner.dispatch_task.wake();
-                        } else if buf_full {
-                            // read task is paused because of read back-pressure
-                            // but there is no new data in top most read buffer
-                            // so we need to wake up read task to read more data
-                            // otherwise read task would sleep forever
-                            inner.read_task.wake();
-                        }
-
-                        // while reading, filter wrote some data
-                        // in that case filters need to process write buffers
-                        // and potentialy wake write task
-                        if status.need_write {
-                            filter.process_write_buf(&self.0, &mut stack, 0)
+                            inner.insert_flags(Flags::RD_READY | Flags::RD_BUF_FULL);
                         } else {
-                            Ok(())
+                            inner.insert_flags(Flags::RD_READY);
                         }
-                    })
-                    .map_err(|err| {
+                        log::trace!("new {} bytes available, wakeup dispatcher", nbytes,);
                         inner.dispatch_task.wake();
-                        inner.insert_flags(Flags::RD_READY);
-                        inner.io_stopped(Some(err));
-                    });
-            }
+                    } else if buf_full {
+                        // read task is paused because of read back-pressure
+                        // but there is no new data in top most read buffer
+                        // so we need to wake up read task to read more data
+                        // otherwise read task would sleep forever
+                        inner.read_task.wake();
+                    }
+
+                    // while reading, filter wrote some data
+                    // in that case filters need to process write buffers
+                    // and potentialy wake write task
+                    if status.need_write {
+                        filter.process_write_buf(&self.0, &inner.buffer, 0)
+                    } else {
+                        Ok(())
+                    }
+                })
+                .map_err(|err| {
+                    inner.dispatch_task.wake();
+                    inner.insert_flags(Flags::RD_READY);
+                    inner.io_stopped(Some(err));
+                });
         }
-        drop(stack);
 
         match result {
             Poll::Ready(Ok(())) => {
@@ -135,20 +123,12 @@ impl WriteContext {
         F: FnOnce(&mut Option<BytesVec>) -> Poll<io::Result<()>>,
     {
         let inner = &self.0 .0;
-        let mut stack = inner.buffer.borrow_mut();
-        let buf = stack.last_write_buf();
 
         // call provided callback
-        let result = f(buf);
-
-        let mut len = 0;
-        if let Some(b) = buf {
-            if b.is_empty() {
-                inner.pool.get().release_write_buf(buf.take().unwrap());
-            } else {
-                len = b.len();
-            }
-        }
+        let (result, len) = inner.buffer.with_write_destination(&self.0, |buf| {
+            let result = f(buf);
+            (result, buf.as_ref().map(|b| b.len()).unwrap_or(0))
+        });
 
         // if write buffer is smaller than high watermark value, turn off back-pressure
         let mut flags = inner.flags.get();
@@ -191,8 +171,7 @@ fn shutdown_filters(io: &IoRef) {
 
     if !flags.intersects(Flags::IO_STOPPED | Flags::IO_STOPPING) {
         let filter = io.filter();
-        let mut buffer = st.buffer.borrow_mut();
-        match filter.shutdown(io, &mut buffer, 0) {
+        match filter.shutdown(io, &st.buffer, 0) {
             Ok(Poll::Ready(())) => {
                 st.dispatch_task.wake();
                 st.insert_flags(Flags::IO_STOPPING);
@@ -211,7 +190,7 @@ fn shutdown_filters(io: &IoRef) {
                 st.io_stopped(Some(err));
             }
         }
-        if let Err(err) = filter.process_write_buf(io, &mut buffer, 0) {
+        if let Err(err) = filter.process_write_buf(io, &st.buffer, 0) {
             st.io_stopped(Some(err));
         }
     }
diff --git a/ntex-io/src/utils.rs b/ntex-io/src/utils.rs
index c196ee45..bdaa3da4 100644
--- a/ntex-io/src/utils.rs
+++ b/ntex-io/src/utils.rs
@@ -118,11 +118,11 @@ mod tests {
     pub(crate) struct TestFilter;
 
     impl FilterLayer for TestFilter {
-        fn process_read_buf(&self, buf: &mut ReadBuf<'_>) -> io::Result<usize> {
+        fn process_read_buf(&self, buf: &ReadBuf<'_>) -> io::Result<usize> {
             Ok(buf.nbytes())
         }
 
-        fn process_write_buf(&self, _: &mut WriteBuf<'_>) -> io::Result<()> {
+        fn process_write_buf(&self, _: &WriteBuf<'_>) -> io::Result<()> {
             Ok(())
         }
     }
diff --git a/ntex-tls/CHANGES.md b/ntex-tls/CHANGES.md
index 162503b3..0aa08998 100644
--- a/ntex-tls/CHANGES.md
+++ b/ntex-tls/CHANGES.md
@@ -1,5 +1,9 @@
 # Changes
 
+## [0.2.4] - 2023-01-29
+
+* Update buffer api
+
 ## [0.2.3] - 2023-01-25
 
 * Fix double buf cleanup
diff --git a/ntex-tls/Cargo.toml b/ntex-tls/Cargo.toml
index d59f2375..38f8b5ba 100644
--- a/ntex-tls/Cargo.toml
+++ b/ntex-tls/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "ntex-tls"
-version = "0.2.3"
+version = "0.2.4"
 authors = ["ntex contributors <team@ntex.rs>"]
 description = "An implementation of SSL streams for ntex backed by OpenSSL"
 keywords = ["network", "framework", "async", "futures"]
@@ -26,7 +26,7 @@ rustls = ["tls_rust"]
 
 [dependencies]
 ntex-bytes = "0.1.19"
-ntex-io = "0.2.3"
+ntex-io = "0.2.7"
 ntex-util = "0.2.0"
 ntex-service = "1.0.0"
 log = "0.4"
@@ -39,7 +39,7 @@ tls_openssl = { version="0.10", package = "openssl", optional = true }
 tls_rust = { version = "0.20", package = "rustls", optional = true }
 
 [dev-dependencies]
-ntex = { version = "0.6.1", features = ["openssl", "rustls", "tokio"] }
+ntex = { version = "0.6.3", features = ["openssl", "rustls", "tokio"] }
 env_logger = "0.10"
 rustls-pemfile = { version = "1.0" }
 webpki-roots = { version = "0.22" }
diff --git a/ntex-tls/src/openssl/mod.rs b/ntex-tls/src/openssl/mod.rs
index b018ff86..93ab73d3 100644
--- a/ntex-tls/src/openssl/mod.rs
+++ b/ntex-tls/src/openssl/mod.rs
@@ -2,7 +2,7 @@
 use std::cell::{Cell, RefCell};
 use std::{any, cmp, error::Error, io, task::Context, task::Poll};
 
-use ntex_bytes::{BufMut, BytesVec, PoolRef};
+use ntex_bytes::{BufMut, BytesVec};
 use ntex_io::{types, Filter, FilterFactory, FilterLayer, Io, Layer, ReadBuf, WriteBuf};
 use ntex_util::{future::poll_fn, future::BoxFuture, ready, time, time::Millis};
 use tls_openssl::ssl::{self, NameType, SslStream};
@@ -24,25 +24,22 @@ pub struct PeerCertChain(pub Vec<X509>);
 /// An implementation of SSL streams
 pub struct SslFilter {
     inner: RefCell<SslStream<IoInner>>,
-    pool: PoolRef,
     handshake: Cell<bool>,
 }
 
 struct IoInner {
     source: Option<BytesVec>,
     destination: Option<BytesVec>,
-    pool: PoolRef,
 }
 
 impl io::Read for IoInner {
     fn read(&mut self, dst: &mut [u8]) -> io::Result<usize> {
-        if let Some(mut buf) = self.source.take() {
+        if let Some(ref mut buf) = self.source {
             if buf.is_empty() {
                 Err(io::Error::from(io::ErrorKind::WouldBlock))
             } else {
                 let len = cmp::min(buf.len(), dst.len());
                 dst[..len].copy_from_slice(&buf.split_to(len));
-                self.source = Some(buf);
                 Ok(len)
             }
         } else {
@@ -53,13 +50,7 @@ impl io::Read for IoInner {
 
 impl io::Write for IoInner {
     fn write(&mut self, src: &[u8]) -> io::Result<usize> {
-        let mut buf = if let Some(buf) = self.destination.take() {
-            buf
-        } else {
-            BytesVec::with_capacity_in(src.len(), self.pool)
-        };
-        buf.extend_from_slice(src);
-        self.destination = Some(buf);
+        self.destination.as_mut().unwrap().extend_from_slice(src);
         Ok(src.len())
     }
 
@@ -69,7 +60,7 @@ impl io::Write for IoInner {
 }
 
 impl SslFilter {
-    fn with_buffers<F, R>(&self, buf: &mut WriteBuf<'_>, f: F) -> R
+    fn with_buffers<F, R>(&self, buf: &WriteBuf<'_>, f: F) -> R
     where
         F: FnOnce() -> R,
     {
@@ -80,16 +71,6 @@ impl SslFilter {
         buf.with_read_buf(|b| b.set_src(self.inner.borrow_mut().get_mut().source.take()));
         result
     }
-
-    fn set_buffers(&self, buf: &mut WriteBuf<'_>) {
-        self.inner.borrow_mut().get_mut().destination = Some(buf.take_dst());
-        self.inner.borrow_mut().get_mut().source = buf.with_read_buf(|b| b.take_src());
-    }
-
-    fn unset_buffers(&self, buf: &mut WriteBuf<'_>) {
-        buf.set_dst(self.inner.borrow_mut().get_mut().destination.take());
-        buf.with_read_buf(|b| b.set_src(self.inner.borrow_mut().get_mut().source.take()));
-    }
 }
 
 impl FilterLayer for SslFilter {
@@ -141,7 +122,7 @@ impl FilterLayer for SslFilter {
         }
     }
 
-    fn shutdown(&self, buf: &mut WriteBuf<'_>) -> io::Result<Poll<()>> {
+    fn shutdown(&self, buf: &WriteBuf<'_>) -> io::Result<Poll<()>> {
         let ssl_result = self.with_buffers(buf, || self.inner.borrow_mut().shutdown());
 
         match ssl_result {
@@ -160,75 +141,72 @@ impl FilterLayer for SslFilter {
         }
     }
 
-    fn process_read_buf(&self, buf: &mut ReadBuf<'_>) -> io::Result<usize> {
-        buf.with_write_buf(|b| self.set_buffers(b));
+    fn process_read_buf(&self, buf: &ReadBuf<'_>) -> io::Result<usize> {
+        buf.with_write_buf(|b| {
+            self.with_buffers(b, || {
+                buf.with_dst(|dst| {
+                    let mut new_bytes = usize::from(self.handshake.get());
+                    loop {
+                        buf.resize_buf(dst);
 
-        let dst = buf.get_dst();
-        //let mut new_bytes = usize::from(self.handshake.get());
-        let mut new_bytes = 1;
-        loop {
-            // make sure we've got room
-            self.pool.resize_read_buf(dst);
-
-            let chunk: &mut [u8] = unsafe { std::mem::transmute(&mut *dst.chunk_mut()) };
-            let ssl_result = self.inner.borrow_mut().ssl_read(chunk);
-            let result = match ssl_result {
-                Ok(v) => {
-                    unsafe { dst.advance_mut(v) };
-                    new_bytes += v;
-                    continue;
-                }
-                Err(ref e)
-                    if e.code() == ssl::ErrorCode::WANT_READ
-                        || e.code() == ssl::ErrorCode::WANT_WRITE =>
-                {
-                    Ok(new_bytes)
-                }
-                Err(ref e) if e.code() == ssl::ErrorCode::ZERO_RETURN => {
-                    buf.want_shutdown();
-                    Ok(new_bytes)
-                }
-                Err(e) => {
-                    log::trace!("SSL Error: {:?}", e);
-                    Err(map_to_ioerr(e))
-                }
-            };
-
-            buf.with_write_buf(|b| self.unset_buffers(b));
-            return result;
-        }
+                        let chunk: &mut [u8] =
+                            unsafe { std::mem::transmute(&mut *dst.chunk_mut()) };
+                        let ssl_result = self.inner.borrow_mut().ssl_read(chunk);
+                        let result = match ssl_result {
+                            Ok(v) => {
+                                unsafe { dst.advance_mut(v) };
+                                new_bytes += v;
+                                continue;
+                            }
+                            Err(ref e)
+                                if e.code() == ssl::ErrorCode::WANT_READ
+                                    || e.code() == ssl::ErrorCode::WANT_WRITE =>
+                            {
+                                Ok(new_bytes)
+                            }
+                            Err(ref e) if e.code() == ssl::ErrorCode::ZERO_RETURN => {
+                                buf.want_shutdown();
+                                Ok(new_bytes)
+                            }
+                            Err(e) => {
+                                log::trace!("SSL Error: {:?}", e);
+                                Err(map_to_ioerr(e))
+                            }
+                        };
+                        return result;
+                    }
+                })
+            })
+        })
     }
 
-    fn process_write_buf(&self, buf: &mut WriteBuf<'_>) -> io::Result<()> {
-        if let Some(mut src) = buf.take_src() {
-            self.set_buffers(buf);
-
-            loop {
-                if src.is_empty() {
-                    self.unset_buffers(buf);
-                    return Ok(());
-                }
-                let ssl_result = self.inner.borrow_mut().ssl_write(&src);
-                match ssl_result {
-                    Ok(v) => {
-                        src.split_to(v);
-                        continue;
+    fn process_write_buf(&self, wb: &WriteBuf<'_>) -> io::Result<()> {
+        wb.with_src(|b| {
+            if let Some(src) = b {
+                self.with_buffers(wb, || loop {
+                    if src.is_empty() {
+                        return Ok(());
                     }
-                    Err(e) => {
-                        buf.set_src(Some(src));
-                        self.unset_buffers(buf);
-                        return match e.code() {
-                            ssl::ErrorCode::WANT_READ | ssl::ErrorCode::WANT_WRITE => {
-                                Ok(())
-                            }
-                            _ => Err(map_to_ioerr(e)),
-                        };
+                    let ssl_result = self.inner.borrow_mut().ssl_write(src);
+                    match ssl_result {
+                        Ok(v) => {
+                            src.split_to(v);
+                            continue;
+                        }
+                        Err(e) => {
+                            return match e.code() {
+                                ssl::ErrorCode::WANT_READ | ssl::ErrorCode::WANT_WRITE => {
+                                    Ok(())
+                                }
+                                _ => Err(map_to_ioerr(e)),
+                            };
+                        }
                     }
-                }
+                })
+            } else {
+                Ok(())
             }
-        } else {
-            Ok(())
-        }
+        })
     }
 }
 
@@ -278,12 +256,10 @@ impl<F: Filter> FilterFactory<F> for SslAcceptor {
             time::timeout(timeout, async {
                 let ssl = ctx_result.map_err(map_to_ioerr)?;
                 let inner = IoInner {
-                    pool: io.memory_pool(),
                     source: None,
                     destination: None,
                 };
                 let filter = SslFilter {
-                    pool: io.memory_pool(),
                     handshake: Cell::new(true),
                     inner: RefCell::new(ssl::SslStream::new(ssl, inner)?),
                 };
@@ -336,12 +312,10 @@ impl<F: Filter> FilterFactory<F> for SslConnector {
     fn create(self, io: Io<F>) -> Self::Future {
         Box::pin(async move {
             let inner = IoInner {
-                pool: io.memory_pool(),
                 source: None,
                 destination: None,
             };
             let filter = SslFilter {
-                pool: io.memory_pool(),
                 handshake: Cell::new(true),
                 inner: RefCell::new(ssl::SslStream::new(self.ssl, inner)?),
             };
diff --git a/ntex-tls/src/rustls/client.rs b/ntex-tls/src/rustls/client.rs
index 557f4c23..9ec38e8a 100644
--- a/ntex-tls/src/rustls/client.rs
+++ b/ntex-tls/src/rustls/client.rs
@@ -56,62 +56,60 @@ impl FilterLayer for TlsClientFilter {
         }
     }
 
-    fn process_read_buf(&self, buf: &mut ReadBuf<'_>) -> io::Result<usize> {
+    fn process_read_buf(&self, buf: &ReadBuf<'_>) -> io::Result<usize> {
         let mut session = self.session.borrow_mut();
+        let mut new_bytes = usize::from(self.inner.handshake.get());
 
         // get processed buffer
-        let (src, dst) = buf.get_pair();
-        let mut new_bytes = usize::from(self.inner.handshake.get());
-        loop {
-            // make sure we've got room
-            self.inner.pool.resize_read_buf(dst);
+        buf.with_src(|src| {
+            if let Some(src) = src {
+                buf.with_dst(|dst| {
+                    loop {
+                        let mut cursor = io::Cursor::new(&src);
+                        let n = session.read_tls(&mut cursor)?;
+                        src.split_to(n);
+                        let state = session
+                            .process_new_packets()
+                            .map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
 
-            let mut cursor = io::Cursor::new(&src);
-            let n = session.read_tls(&mut cursor)?;
-            src.split_to(n);
-            let state = session
-                .process_new_packets()
-                .map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
-
-            let new_b = state.plaintext_bytes_to_read();
-            if new_b > 0 {
-                dst.reserve(new_b);
-                let chunk: &mut [u8] =
-                    unsafe { std::mem::transmute(&mut *dst.chunk_mut()) };
-                let v = session.reader().read(chunk)?;
-                unsafe { dst.advance_mut(v) };
-                new_bytes += v;
-            } else {
-                break;
+                        let new_b = state.plaintext_bytes_to_read();
+                        if new_b > 0 {
+                            dst.reserve(new_b);
+                            let chunk: &mut [u8] =
+                                unsafe { std::mem::transmute(&mut *dst.chunk_mut()) };
+                            let v = session.reader().read(chunk)?;
+                            unsafe { dst.advance_mut(v) };
+                            new_bytes += v;
+                        } else {
+                            break;
+                        }
+                    }
+                    Ok::<_, io::Error>(())
+                })?;
             }
-        }
-
-        Ok(new_bytes)
+            Ok(new_bytes)
+        })
     }
 
-    fn process_write_buf(&self, buf: &mut WriteBuf<'_>) -> io::Result<()> {
-        if let Some(mut src) = buf.take_src() {
-            let mut session = self.session.borrow_mut();
-            let mut io = Wrapper(&self.inner, buf);
+    fn process_write_buf(&self, buf: &WriteBuf<'_>) -> io::Result<()> {
+        buf.with_src(|src| {
+            if let Some(src) = src {
+                let mut session = self.session.borrow_mut();
+                let mut io = Wrapper(&self.inner, buf);
 
-            loop {
-                if !src.is_empty() {
-                    let n = session.writer().write(&src)?;
-                    src.split_to(n);
-                }
-
-                if session.wants_write() {
-                    session.complete_io(&mut io)?;
-                } else {
-                    break;
+                loop {
+                    if !src.is_empty() {
+                        src.split_to(session.writer().write(src)?);
+                    }
+                    if session.wants_write() {
+                        session.complete_io(&mut io)?;
+                    } else {
+                        break;
+                    }
                 }
             }
-
-            buf.set_src(Some(src));
             Ok(())
-        } else {
-            Ok(())
-        }
+        })
     }
 }
 
@@ -125,7 +123,6 @@ impl TlsClientFilter {
             .map_err(|err| io::Error::new(io::ErrorKind::Other, err))?;
         let filter = TlsFilter::new_client(TlsClientFilter {
             inner: IoInner {
-                pool: io.memory_pool(),
                 handshake: Cell::new(true),
             },
             session: RefCell::new(session),
diff --git a/ntex-tls/src/rustls/mod.rs b/ntex-tls/src/rustls/mod.rs
index 814c26c2..52bc7529 100644
--- a/ntex-tls/src/rustls/mod.rs
+++ b/ntex-tls/src/rustls/mod.rs
@@ -2,7 +2,6 @@
 //! An implementation of SSL streams for ntex backed by OpenSSL
 use std::{any, cell::Cell, cmp, io, sync::Arc, task::Context, task::Poll};
 
-use ntex_bytes::PoolRef;
 use ntex_io::{
     Filter, FilterFactory, FilterLayer, Io, Layer, ReadBuf, ReadStatus, WriteBuf,
     WriteStatus,
@@ -71,7 +70,7 @@ impl FilterLayer for TlsFilter {
     }
 
     #[inline]
-    fn shutdown(&self, buf: &mut WriteBuf<'_>) -> io::Result<Poll<()>> {
+    fn shutdown(&self, buf: &WriteBuf<'_>) -> io::Result<Poll<()>> {
         match self.inner {
             InnerTlsFilter::Server(ref f) => f.shutdown(buf),
             InnerTlsFilter::Client(ref f) => f.shutdown(buf),
@@ -95,7 +94,7 @@ impl FilterLayer for TlsFilter {
     }
 
     #[inline]
-    fn process_read_buf(&self, buf: &mut ReadBuf<'_>) -> io::Result<usize> {
+    fn process_read_buf(&self, buf: &ReadBuf<'_>) -> io::Result<usize> {
         match self.inner {
             InnerTlsFilter::Server(ref f) => f.process_read_buf(buf),
             InnerTlsFilter::Client(ref f) => f.process_read_buf(buf),
@@ -103,7 +102,7 @@ impl FilterLayer for TlsFilter {
     }
 
     #[inline]
-    fn process_write_buf(&self, buf: &mut WriteBuf<'_>) -> io::Result<()> {
+    fn process_write_buf(&self, buf: &WriteBuf<'_>) -> io::Result<()> {
         match self.inner {
             InnerTlsFilter::Server(ref f) => f.process_write_buf(buf),
             InnerTlsFilter::Client(ref f) => f.process_write_buf(buf),
@@ -219,30 +218,31 @@ impl<F: Filter> FilterFactory<F> for TlsConnectorConfigured {
 }
 
 pub(crate) struct IoInner {
-    pool: PoolRef,
     handshake: Cell<bool>,
 }
 
-pub(crate) struct Wrapper<'a, 'b>(&'a IoInner, &'a mut WriteBuf<'b>);
+pub(crate) struct Wrapper<'a, 'b>(&'a IoInner, &'a WriteBuf<'b>);
 
 impl<'a, 'b> io::Read for Wrapper<'a, 'b> {
     fn read(&mut self, dst: &mut [u8]) -> io::Result<usize> {
         self.1.with_read_buf(|buf| {
-            let read_buf = buf.get_src();
-            let len = cmp::min(read_buf.len(), dst.len());
-            if len > 0 {
-                dst[..len].copy_from_slice(&read_buf.split_to(len));
-                Ok(len)
-            } else {
+            buf.with_src(|buf| {
+                if let Some(buf) = buf {
+                    let len = cmp::min(buf.len(), dst.len());
+                    if len > 0 {
+                        dst[..len].copy_from_slice(&buf.split_to(len));
+                        return Ok(len);
+                    }
+                }
                 Err(io::Error::new(io::ErrorKind::WouldBlock, ""))
-            }
+            })
         })
     }
 }
 
 impl<'a, 'b> io::Write for Wrapper<'a, 'b> {
     fn write(&mut self, src: &[u8]) -> io::Result<usize> {
-        self.1.with_dst_buf(|buf| buf.extend_from_slice(src));
+        self.1.with_dst(|buf| buf.extend_from_slice(src));
         Ok(src.len())
     }
 
diff --git a/ntex-tls/src/rustls/server.rs b/ntex-tls/src/rustls/server.rs
index 6b22bb1e..8cc965a7 100644
--- a/ntex-tls/src/rustls/server.rs
+++ b/ntex-tls/src/rustls/server.rs
@@ -63,60 +63,60 @@ impl FilterLayer for TlsServerFilter {
         }
     }
 
-    fn process_read_buf(&self, buf: &mut ReadBuf<'_>) -> io::Result<usize> {
+    fn process_read_buf(&self, buf: &ReadBuf<'_>) -> io::Result<usize> {
         let mut session = self.session.borrow_mut();
+        let mut new_bytes = usize::from(self.inner.handshake.get());
 
         // get processed buffer
-        let (src, dst) = buf.get_pair();
-        let mut new_bytes = usize::from(self.inner.handshake.get());
-        loop {
-            // make sure we've got room
-            self.inner.pool.resize_read_buf(dst);
+        buf.with_src(|src| {
+            if let Some(src) = src {
+                buf.with_dst(|dst| {
+                    loop {
+                        let mut cursor = io::Cursor::new(&src);
+                        let n = session.read_tls(&mut cursor)?;
+                        src.split_to(n);
+                        let state = session
+                            .process_new_packets()
+                            .map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
 
-            let mut cursor = io::Cursor::new(&src);
-            let n = session.read_tls(&mut cursor)?;
-            src.split_to(n);
-            let state = session
-                .process_new_packets()
-                .map_err(|e| io::Error::new(io::ErrorKind::Other, e))?;
-
-            let new_b = state.plaintext_bytes_to_read();
-            if new_b > 0 {
-                dst.reserve(new_b);
-                let chunk: &mut [u8] =
-                    unsafe { std::mem::transmute(&mut *dst.chunk_mut()) };
-                let v = session.reader().read(chunk)?;
-                unsafe { dst.advance_mut(v) };
-                new_bytes += v;
-            } else {
-                break;
+                        let new_b = state.plaintext_bytes_to_read();
+                        if new_b > 0 {
+                            dst.reserve(new_b);
+                            let chunk: &mut [u8] =
+                                unsafe { std::mem::transmute(&mut *dst.chunk_mut()) };
+                            let v = session.reader().read(chunk)?;
+                            unsafe { dst.advance_mut(v) };
+                            new_bytes += v;
+                        } else {
+                            break;
+                        }
+                    }
+                    Ok::<_, io::Error>(())
+                })?;
             }
-        }
-
-        Ok(new_bytes)
+            Ok(new_bytes)
+        })
     }
 
-    fn process_write_buf(&self, buf: &mut WriteBuf<'_>) -> io::Result<()> {
-        if let Some(mut src) = buf.take_src() {
-            let mut session = self.session.borrow_mut();
-            let mut io = Wrapper(&self.inner, buf);
+    fn process_write_buf(&self, buf: &WriteBuf<'_>) -> io::Result<()> {
+        buf.with_src(|src| {
+            if let Some(src) = src {
+                let mut session = self.session.borrow_mut();
+                let mut io = Wrapper(&self.inner, buf);
 
-            loop {
-                if !src.is_empty() {
-                    let n = session.writer().write(&src)?;
-                    src.split_to(n);
-                }
-
-                if session.wants_write() {
-                    session.complete_io(&mut io)?;
-                } else {
-                    break;
+                loop {
+                    if !src.is_empty() {
+                        src.split_to(session.writer().write(src)?);
+                    }
+                    if session.wants_write() {
+                        session.complete_io(&mut io)?;
+                    } else {
+                        break;
+                    }
                 }
             }
-
-            buf.set_src(Some(src));
-        }
-        Ok(())
+            Ok(())
+        })
     }
 }
 
@@ -132,7 +132,6 @@ impl TlsServerFilter {
             let filter = TlsFilter::new_server(TlsServerFilter {
                 session: RefCell::new(session),
                 inner: IoInner {
-                    pool: io.memory_pool(),
                     handshake: Cell::new(true),
                 },
             });
diff --git a/ntex/Cargo.toml b/ntex/Cargo.toml
index 5e29ac69..ef4c3c46 100644
--- a/ntex/Cargo.toml
+++ b/ntex/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "ntex"
-version = "0.6.2"
+version = "0.6.3"
 authors = ["ntex contributors <team@ntex.rs>"]
 description = "Framework for composable network services"
 readme = "README.md"
@@ -58,8 +58,8 @@ ntex-util = "0.2.0"
 ntex-bytes = "0.1.19"
 ntex-h2 = "0.2.1"
 ntex-rt = "0.4.7"
-ntex-io = "0.2.3"
-ntex-tls = "0.2.3"
+ntex-io = "0.2.7"
+ntex-tls = "0.2.4"
 ntex-tokio = { version = "0.2.1", optional = true }
 ntex-glommio = { version = "0.2.1", optional = true }
 ntex-async-std = { version = "0.2.1", optional = true }
diff --git a/ntex/src/http/h1/dispatcher.rs b/ntex/src/http/h1/dispatcher.rs
index 4edc70c2..e2244632 100644
--- a/ntex/src/http/h1/dispatcher.rs
+++ b/ntex/src/http/h1/dispatcher.rs
@@ -684,8 +684,7 @@ where
                 // read request payload
                 let mut updated = false;
                 loop {
-                    let res = io.poll_recv(&payload.0, cx);
-                    match res {
+                    match io.poll_recv(&payload.0, cx) {
                         Poll::Ready(Ok(PayloadItem::Chunk(chunk))) => {
                             updated = true;
                             payload.1.feed_data(chunk);
@@ -945,6 +944,7 @@ mod tests {
 
     #[crate::rt_test]
     async fn test_pipeline_with_payload() {
+        env_logger::init();
         let (client, server) = Io::create();
         client.remote_buffer_cap(4096);
         let mut decoder = ClientCodec::default();
diff --git a/ntex/src/ws/transport.rs b/ntex/src/ws/transport.rs
index 7938be7a..e379ee22 100644
--- a/ntex/src/ws/transport.rs
+++ b/ntex/src/ws/transport.rs
@@ -58,7 +58,7 @@ impl WsTransport {
 
 impl FilterLayer for WsTransport {
     #[inline]
-    fn shutdown(&self, buf: &mut WriteBuf<'_>) -> io::Result<Poll<()>> {
+    fn shutdown(&self, buf: &WriteBuf<'_>) -> io::Result<Poll<()>> {
         let flags = self.flags.get();
         if !flags.contains(Flags::CLOSED) {
             self.insert_flags(Flags::CLOSED);
@@ -67,7 +67,7 @@ impl FilterLayer for WsTransport {
             } else {
                 CloseCode::Normal
             };
-            let _ = buf.with_dst_buf(|buf| {
+            let _ = buf.with_dst(|buf| {
                 self.codec.encode_vec(
                     Message::Close(Some(CloseReason {
                         code,
@@ -80,7 +80,7 @@ impl FilterLayer for WsTransport {
         Ok(Poll::Ready(()))
     }
 
-    fn process_read_buf(&self, buf: &mut ReadBuf<'_>) -> io::Result<usize> {
+    fn process_read_buf(&self, buf: &ReadBuf<'_>) -> io::Result<usize> {
         if let Some(mut src) = buf.take_src() {
             let mut dst = buf.take_dst();
             let dst_len = dst.len();
@@ -133,7 +133,7 @@ impl FilterLayer for WsTransport {
                     }
                     Frame::Ping(msg) => {
                         let _ = buf.with_write_buf(|b| {
-                            b.with_dst_buf(|b| self.codec.encode_vec(Message::Pong(msg), b))
+                            b.with_dst(|b| self.codec.encode_vec(Message::Pong(msg), b))
                         });
                     }
                     Frame::Pong(_) => (),
@@ -153,9 +153,9 @@ impl FilterLayer for WsTransport {
         }
     }
 
-    fn process_write_buf(&self, buf: &mut WriteBuf<'_>) -> io::Result<()> {
+    fn process_write_buf(&self, buf: &WriteBuf<'_>) -> io::Result<()> {
         if let Some(src) = buf.take_src() {
-            buf.with_dst_buf(|dst| {
+            buf.with_dst(|dst| {
                 // make sure we've got room
                 let (hw, lw) = self.pool.write_params().unpack();
                 let remaining = dst.remaining_mut();