On 1/7/19 9:04 AM, Bart Van Assche wrote:

On Mon, 2019-01-07 at 08:43 -0700, Jens Axboe wrote:

quoted

On 1/7/19 5:52 AM, Weiping Zhang wrote:

quoted

If the low level driver has no timerout handler, the
/sys/block/<disk>/queue/io_timeout will not be displayed.

The alternative would be to make it return an error when read/written
instead of having this separate group code.

Hi Jens,

Christoph and I had asked Weiping to use a sysfs attribute group. See also
https://www.mail-archive.com/linux-block@vger.kernel.org/msg25841.html

I think both solutions have parts that suck. If the file is only there
for some devices, that's a bit of an API wart. But at the same time, if the
file is there and not readable/writeable on those same devices, that's also
kind of ugly (as the wbt exercise has shown).

-- 
Jens Axboe