[PATCH RFC v2 1/2] block: scan partitions for hidden disks

[John Garry]

On 8/19/26 10:00, Christoph Hellwig wrote:
> On Tue, Aug 18, 2026 at 12:08:53PM +0000, John Garry wrote:
>> From: John Garry<john.garry at linux.dev>
>>
>> If a disk is hidden (GENHD_FL_HIDDEN flags set), we currently do not scan
>> the disk partition table.
>>
>> GENHD_FL_HIDDEN is used in NVMe multipath support to hide the per-path
>> disk.
> It also is used for giving a handle to NVMe devices that we can't support
> as block devices and for which we only want a handle to issue passthrough
> commands.  For those attempting a partition scan is rather suboptimal.

We could set GENHD_FL_NO_PART in that case (as well as the hidden flag).

> 
> As is in general doing an extra scan per controller when we know it must
> give the same results.  Wouldn't it make more sense to just propagate
> the partition table from the ns_head to each individual path?

So you mean that we would have something which can clone the head 
gendisk partitions onto the per-path gendisk by itering  >part_tbl and 
calling something like blk_add_partition(), right?