On Tue, Sep 07, 2021 at 08:15:03AM -0700, Bart Van Assche wrote: > On 9/7/21 7:21 AM, Niklas Cassel wrote: > > blk-mq will no longer call the I/O scheduler .finish_request() callback > > for requests that were never inserted to the I/O scheduler. > > I do not agree. Even with patch 1/2 from this series applied, finish_request() > will still be called for requests inserted by blk_insert_cloned_request() > although these requests are never inserted to the I/O scheduler. > > Bart. Hello Bart, Looking at blk_mq_free_request(), e->type->ops.finish_request() will only be called if RQF_ELVPRIV is set. blk_insert_cloned_request() doesn't seem to allocate a request itself, but instead takes an already cloned request. So I guess it depends on how the supplied request was cloned. I would assume if the original request doesn't have RQF_ELVPRIV set, then neither will the cloned request? I tried to look at blk_rq_prep_clone(), which seems to be a common cloning function, but I don't see req->rq_flags being copied (except for RQF_SPECIAL_PAYLOAD). Anyway, I don't see how .finish_request() will be called in relation to blk_insert_cloned_request(). Could you please help me out and give me an example of a call chain where this can happen? Kind regards, Niklas
