On 5/26/20 1:38 AM, Pavel Begunkov wrote: > On 23/05/2020 21:57, Jens Axboe wrote: >> If the file is flagged with FMODE_BUF_RASYNC, then we don't have to punt >> the buffered read to an io-wq worker. Instead we can rely on page >> unlocking callbacks to support retry based async IO. This is a lot more >> efficient than doing async thread offload. >> >> The retry is done similarly to how we handle poll based retry. From >> the unlock callback, we simply queue the retry to a task_work based >> handler. >> >> Signed-off-by: Jens Axboe <[email protected]> >> --- >> fs/io_uring.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 99 insertions(+) >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index e95481c552ff..dd532d2634c2 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -498,6 +498,8 @@ struct io_async_rw { >> struct iovec *iov; >> ssize_t nr_segs; >> ssize_t size; >> + struct wait_page_queue wpq; >> + struct callback_head task_work; >> }; >> >> struct io_async_ctx { >> @@ -2568,6 +2570,99 @@ static int io_read_prep(struct io_kiocb *req, const >> struct io_uring_sqe *sqe, >> return 0; >> } >> >> +static void io_async_buf_cancel(struct callback_head *cb) >> +{ >> + struct io_async_rw *rw; >> + struct io_ring_ctx *ctx; >> + struct io_kiocb *req; >> + >> + rw = container_of(cb, struct io_async_rw, task_work); >> + req = rw->wpq.wait.private; >> + ctx = req->ctx; >> + >> + spin_lock_irq(&ctx->completion_lock); >> + io_cqring_fill_event(req, -ECANCELED); > > It seems like it should go through kiocb_done()/io_complete_rw_common(). > My concern is missing io_put_kbuf().
Yeah, I noticed that too after sending it out. If you look at the current one that I updated yesterday, it does add that (and also renames the iter read helper): https://git.kernel.dk/cgit/linux-block/commit/?h=async-buffered.5&id=6f4e3a4066d0db3e3478e58cc250afb16d8d4d91 -- Jens Axboe
