Hi, We currently only support looking up and canceling requests based on the user_data of the original request. Sometimes it can be useful to instead key off the fd used in the original request, eg if a socket goes away. Patch 1 is just a cleanup spotted while doing this, 2+3 are prep patches, and patch 4 then finally is the meat of it. Adds IORING_ASYNC_CANCEL_FD as a IORING_OP_ASYNC_CANCEL request flag, which tells the kernel that we're looking up by fd rather than user_data. -- Jens Axboe
