On 1/7/19 9:04 AM, Bart Van Assche wrote: > On Mon, 2019-01-07 at 08:43 -0700, Jens Axboe wrote: >> On 1/7/19 5:52 AM, Weiping Zhang wrote: >>> 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@xxxxxxxxxxxxxxx/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
