On 9/3/22 3:56 AM, Kanchan Joshi wrote:
> On Fri, Sep 02, 2022 at 05:00:51PM -0600, Jens Axboe wrote:
>> Don't need to rely on the cookie or request type, set the right handler
>> based on how we're handling the IO.
>>
>> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
>> ---
>> drivers/nvme/host/ioctl.c | 30 ++++++++++++++++++++++--------
>> 1 file changed, 22 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
>> index 7756b439a688..f34abe95821e 100644
>> --- a/drivers/nvme/host/ioctl.c
>> +++ b/drivers/nvme/host/ioctl.c
>> @@ -385,25 +385,36 @@ static void nvme_uring_task_cb(struct io_uring_cmd *ioucmd)
>> ????io_uring_cmd_done(ioucmd, status, result);
>> }
>>
>> -static void nvme_uring_cmd_end_io(struct request *req, blk_status_t err)
>> +static void nvme_uring_iopoll_cmd_end_io(struct request *req, blk_status_t err)
>> {
>> ????struct io_uring_cmd *ioucmd = req->end_io_data;
>> ????struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
>> ????/* extract bio before reusing the same field for request */
>> ????struct bio *bio = pdu->bio;
>> -??? void *cookie = READ_ONCE(ioucmd->cookie);
>>
>> ????pdu->req = req;
>> ????req->bio = bio;
>>
>> ????/*
>> ???? * For iopoll, complete it directly.
>> -???? * Otherwise, move the completion to task work.
>> ???? */
>> -??? if (cookie != NULL && blk_rq_is_poll(req))
>> -??????? nvme_uring_task_cb(ioucmd);
>> -??? else
>> -??????? io_uring_cmd_complete_in_task(ioucmd, nvme_uring_task_cb);
>> +??? nvme_uring_task_cb(ioucmd);
>> +}
>> +
>> +static void nvme_uring_cmd_end_io(struct request *req, blk_status_t err)
>> +{
>> +??? struct io_uring_cmd *ioucmd = req->end_io_data;
>> +??? struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
>> +??? /* extract bio before reusing the same field for request */
>> +??? struct bio *bio = pdu->bio;
>> +
>> +??? pdu->req = req;
>> +??? req->bio = bio;
>> +
>> +??? /*
>> +???? * Move the completion to task work.
>> +???? */
>> +??? io_uring_cmd_complete_in_task(ioucmd, nvme_uring_task_cb);
>> }
>>
>> static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
>> @@ -464,7 +475,10 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
>> ??????????? blk_flags);
>> ????if (IS_ERR(req))
>> ??????? return PTR_ERR(req);
>> -??? req->end_io = nvme_uring_cmd_end_io;
>> +??? if (issue_flags & IO_URING_F_IOPOLL)
>> +??????? req->end_io = nvme_uring_iopoll_cmd_end_io;
>> +??? else
>> +??????? req->end_io = nvme_uring_cmd_end_io;
>
> The polled handler (nvme_uring_iopoll_cmd_end_io) may get called in
> irq context (some swapper/kworker etc.) too. And in that case will it
> be safe to call nvme_uring_task_cb directly. We don't touch the
> user-fields in cmd (thanks to Big CQE) so that part is sorted. But
> there is blk_rq_unmap_user call - can that or anything else inside
> io_req_complete_post() cause trouble.
The unmap might be problematic if the data wasn't mapped. That's a slow
path and unexpected, however. Might be better to just leave the unified
completion path and ensure that nvme_uring_task_cb() checks for polled
as well. I'll give it a quick spin.
--
Jens Axboe
