Re: [Libguestfs] [libnbd PATCH 4/6] states: Prepare for aio notify callback

On 6/29/19 8:28 AM, Eric Blake wrote: > > We also want the client to be aware of any issued/in-flight commands > that failed because they were stranded when the state machine moved to > CLOSED or DEAD. Previously, nbd_aio_command_completed() would never > locate such stranded commands, but adding a common point to fire the > notifier for such commands makes it also possible to move those > commands to the completion queue. > > +++ b/generator/states.c > @@ -111,6 +111,31 @@ send_from_wbuf (struct nbd_handle *h) > return 0; /* move to next state */ > } > > +/* Forcefully fail any remaining in-flight commands in list */ > +void abort_commands (struct nbd_handle *h, > + struct command_in_flight **list) > +{ > + struct command_in_flight *prev_cmd, *cmd; > + > + for (cmd = *list, prev_cmd = NULL; > + cmd != NULL; > + prev_cmd = cmd, cmd = cmd->next) { > + if (cmd->cb.notify && cmd->type != NBD_CMD_DISC) { > + int error = cmd->error ? cmd->error : ENOTCONN; > + > + if (cmd->cb.notify (cmd->cb.opaque, cmd->handle, &error) == -1 && error) > + cmd->error = error; > + } > + if (cmd->error == 0) > + cmd->error = ENOTCONN; > + } > + if (prev_cmd) { > + prev_cmd->next = h->cmds_done; > + h->cmds_done = *list; > + *list = NULL; > + } This inserts the list to the head of cmds_done, which breaks its use as a FIFO queue for clients using nbd_aio_peek_command_completed to process messages in server order. I'll post a fix that keeps things in order.