Re: [PATCH 17/17] null_blk: remove legacy IO path

Sébastien Boisvert
2018-10-12T17:37:16Z

On 2018-10-12 01:30 PM, Jens Axboe wrote:
> On 10/12/18 11:24 AM, Sébastien Boisvert wrote:
>>> + if (g_queue_mode == NULL_Q_RQ) {
>>> + pr_err("null_blk: legacy IO path no longer available\n");
>>> + return -EINVAL;
>>> + }
>>
>> Is this the only location where the value NULL_Q_RQ has be checked ?
>
> I've since fixed a few more, all should be well now. The updated version
> is here:
>
> http://git.kernel.dk/cgit/linux-block/commit/?h=mq-conversions&id=d6fd3bd94a7333a8cd0bf7ef18f719ef7e052dc4
>
>> Since the enum that contains NULL_Q_RQ is in
>> drivers/block/null_blk_main.c, and not in a linux header file, would
>> it be thinkable to remove NULL_Q_RQ from the enum too, and not adding
>> this legacy check ?
>>
>> Would that break user space (the number one rule) ?
>
> It wouldn't break user space. In any case, if someone is currently using
> queue_mode=1, it'd fail to load after this patch.
>

Just curious, where can this be passed (mount option, boot option, /sys, /proc, driver code, or whatnot) ?

> I'm checking that at the bottom, we could remove NULL_Q_RQ if we just
> made that check == 1 instead. But cleaner to keep it, imho.
>

I agree, if queue_mode=1 can be passed.

Reviewed-by: Sébastien Boisvert <sboisvert@gydle.com>