On 9/2/20 10:09 AM, Pavel Begunkov wrote:
> On 02/09/2020 19:00, Jens Axboe wrote:
>> Actually two things that need fixing up here:
>>
>> - The io_rw_reissue() -EAGAIN retry is explicit to block devices and
>> regular files, so don't ever attempt to do that on other types of
>> files.
>>
>> - If we hit -EAGAIN on a nonblock marked file, don't arm poll handler for
>> it. It should just complete with -EAGAIN.
>>
>> Cc: stable@xxxxxxxxxxxxxxx
>> Reported-by: Norman Maurer <norman.maurer@xxxxxxxxxxxxxx>
>> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
>>
>> ---
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index b1ccd7072d93..65656102bbeb 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -2300,8 +2300,11 @@ static bool io_resubmit_prep(struct io_kiocb *req, int error)
>> static bool io_rw_reissue(struct io_kiocb *req, long res)
>> {
>> #ifdef CONFIG_BLOCK
>> + umode_t mode = file_inode(req->file)->i_mode;
>> int ret;
>>
>> + if (!S_ISBLK(mode) && !S_ISREG(mode))
>> + return false;
>> if ((res != -EAGAIN && res != -EOPNOTSUPP) || io_wq_current_is_worker())
>> return false;
>>
>> @@ -3146,6 +3149,9 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
>> /* IOPOLL retry should happen for io-wq threads */
>> if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
>> goto done;
>> + /* no retry on NONBLOCK marked file */
>> + if (req->file->f_flags & O_NONBLOCK)
>> + goto done;
>
> Looks like it works with open(O_NONBLOCK) but not with IOCB_NOWAIT in the
> request's flags. Is that so?
The IOCB_NOWAIT case should already be fine, it's just the O_NONBLOCK that
isn't covered. IOCB_NOWAIT on a socket unhelpfully fails anyway, since
FMODE_NOWAIT isn't available. Arguably something that should be fixed
separately.
--
Jens Axboe
