On Tue, May 22, 2018 at 10:57:40PM +0800, Ming Lei wrote: > OK, that still depends on driver's behaviour, even though it is true > for NVMe, you still have to audit other drivers about this sync > because it is required by your patch.
Okay, forget about nvme for a moment here. Please run this thought experiment to decide if what you're saying is even plausible for any block driver with the existing implementation: Your scenario has a driver return EH_HANDLED for a timed out request. The timeout work then completes the request. The request may then be reallocated for a new command and dispatched. At approximately the same time, you're saying the driver that returned EH_HANDLED may then call blk_mq_complete_request() in reference to the *old* request that it returned EH_HANDLED for, incorrectly completing the new request before it is done. That will inevitably lead to data corruption. Is that happening today in any driver?
