On Fri, Aug 27, 2021 at 12:41:31PM +0000, Niklas Cassel wrote: > From: Niklas Cassel <niklas.cassel@xxxxxxx> > > Currently, __blk_mq_alloc_request() calls ops.prepare_request and sets > RQF_ELVPRIV. > > Therefore, (if the request is not a flush) the RQF_ELVPRIV flag will be > set for the request in blk_mq_submit_bio(), regardless if the request > was submitted to a scheduler, or bypassed the scheduler. > > Later, blk_mq_free_request() checks if the RQF_ELVPRIV flag is set, > if it is, the ops.finish_request callback will be called. > > The problem with this is that the finish_request scheduler callback > will be called for requests that bypassed the scheduler. > > Fix this by calling the scheduler ops.prepare_request callback, and > set the RQF_ELVPRIV flag only immediately before calling the insert > callback. One request could be inserted more than one times, such as requeue, however __blk_mq_alloc_request() is just run once, so is it fine to call ->prepare_request more than one time for same request? Or I am wondering why not call ->prepare_request when the following check is true? if (e && e->type->ops.prepare_request && !op_is_flush(data->cmd_flags) && !blk_op_is_passthrough(data->cmd_flags)) e->type->ops.prepare_request() Thanks, Ming
