Re: [PATCH] scsi: storvsc: set max_segment_size as UINT_MAX explicitly

Christoph Hellwig
2025-06-17T04:43:46Z

On Tue, Jun 17, 2025 at 12:05:09AM +0800, Ming Lei wrote:
> Set max_segment_size as UINT_MAX explicitly:
>
> - storvrc uses virt_boundary to define `segment`
>
> - strovrc does not define max_segment_size
>
> So define max_segment_size as UINT_MAX, otherwise __blk_rq_map_sg() takes
> default 64K max segment size and splits one virtual segment into two parts,
> then breaks virt_boundary limit.
>
> Before commit ec84ca4025c0 ("scsi: block: Remove now unused queue limits helpers"),
> max segment size is set as UINT_MAX in case that virt_boundary is
> defined.

Drivers should not have done this. If you need this someone (probably
me) broke the block layer code ensuring it's not needed, and that
affects all drivers using virt_boundary.