block/mq/request.rs

25 /// 1. Request is owned by block layer (refcount 0).
27 ///    (refcount 1).
29 ///    (refcount 2).
31 ///    (refcount > 2).
40 /// The states are tracked through the private `refcount` field of
51 ///   `self.wrapper_ref().refcount()`.
63     /// * The caller must own a refcount on `ptr` that is transferred to the
84     /// `self.wrapper_ref().refcount() == 2`.
91     /// Try to take exclusive ownership of `this` by dropping the refcount to 0.
102         if let Err(_old) = this.wrapper_ref().refcount().compare_exchange(
171     /// The Rust request refcount has the following states:
176     refcount: AtomicU64,
180     /// Return a reference to the refcount of the request that is embedding
182     pub(crate) fn refcount(&self) -> &AtomicU64 {
183         &self.refcount
186     /// Return a pointer to the refcount of the request that is embedding the
195         unsafe { &raw mut (*this).refcount }
240         let refcount = &self.wrapper_ref().refcount();
243         let updated = atomic_relaxed_op_unless(refcount, |x| x + 1, 0);
247             panic!("Request refcount zero on clone")
257         let refcount = unsafe { &*RequestDataWrapper::refcount_ptr(wrapper_ptr) };
260         let new_refcount = atomic_relaxed_op_return(refcount, |x| x - 1);
264             panic!("Request reached refcount zero in Rust abstractions");