Re: iSCSI target: Handling in-flight requests during ctld shutdown
Date: Fri, 31 Dec 2021 21:27:26 UTC
On 31.12.2021 13:41, John Baldwin wrote: > On 12/30/21 3:06 PM, Alexander Motin wrote: >> No. cfiscsi_datamove_out() called before the new flag is set would >> still try to send R2T over the dying connection to be aborted by the >> cfiscsi_session_terminate_tasks() few milliseconds later. >> cfiscsi_data_wait_abort() would only be needed if >> cfiscsi_session_terminate_tasks() has already passed through the data >> waiters list and waiting for the last tasks completion. > > So I think what I was missing is that I had assumed in the race case > that the task was not visible when the NEXUS_I_T_RESET ran, but I think > from re-reading now that the task has to have been in the lun's OOA > queue as we don't permit queueing more tasks due to LUN_RESERVED being > cleared, so I think that means that even in the race case the task > has been aborted. Perhaps then the code in cfiscsi_datamove_out can > just check CTL_FLAG_ABORT instead of cs_terminating? That would > function similar to your proposed new flag I think assuming it is correct > that the task for any I/O being passed to cfiscsi_datamove_out concurrent > with cfiscsi_session_terminate_tasks must have been "visible" on the OAA > queue and thus aborted by the handler? It was looking like a good idea for few seconds, since you right that almost all commands should be visible via OAA queues and so should be aborted by cfiscsi_session_terminate_tasks() at that point. But there are few exceptions of commands that can be executed without LUNs present, see CTL_CMD_FLAG_OK_ON_NO_LUN. All 3 of them are CTL_FLAG_DATA_IN, so should not appear in cfiscsi_datamove_out(), but I am still not sure it is very good, even though it may probably work. -- Alexander Motin