Re: ublk invert part scan bit logic

[Jens Axboe <axboe@kernel.dk>]

On 2/12/26 5:42 AM, Ming Lei wrote:
> On Thu, Feb 12, 2026 at 04:05:27AM -0700, Jens Axboe wrote:
>> Hi,
>>
>> For ublk, there's this logic in in ublk_ctrl_start_dev():
>>
>> /* Skip partition scan if disabled by user */
>> if (ub->dev_info.flags & UBLK_F_NO_AUTO_PART_SCAN) {
>> 	clear_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
>> } else {
>> 	/* Schedule async partition scan for trusted daemons */
>> 	if (!ub->unprivileged_daemons)
>> 		schedule_work(&ub->partition_scan_work);
>> }
>>
>> where the
>>
>> clear_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
>>
>> seems reversed? Why is GD_SUPPRESS_PART_SCAN being cleared if
>> UBLK_F_NO_AUTO_PART_SCAN is set? Added in:
>>
>> 8443e2087e70 ("ublk: add UBLK_F_NO_AUTO_PART_SCAN feature flag")
> 
> Yeah, the interface is designed in this way: partition scan is not
> done during add disk, and allowed since then on. The selftest code
> is written in same way too.
> 
> If GD_SUPPRESS_PART_SCAN isn't cleared, userspace can't probe partitions
> any more.
> 
> However, if you think the interface isn't good, we still can change it
> before 7.0 release.

What I mean is, if UBLK_F_NO_AUTO_PART_SCAN is set, should we not
either leave the disk->state alone, or _set_ GD_SUPPRESS_PART_SCAN?
I might be confused here, but the current implementation doesn't
make much sense to me! If it is correct, then a comment to that
effect would be good imho.

-- 
Jens Axboe