[PATCH v1 0/2] dma: fix dma_opt_mapping_size() returning bogus value when no backend hint exists

[Christoph Hellwig]

On Tue, Mar 17, 2026 at 09:11:59AM +0000, John Garry wrote:
> For SAS controllers, don't we limit shost->opt_sectors at 
> shost->max_sectors, and then in sd_revalidate_disk() this value is ignored 
> as sdkp->opt_xfer_blocks would be smaller, right?

That assumes opt_xfer_blocks is actually set.  It's an optional and
relatively recent SCSI feature.  So don't expect crappy SSDs or
RAID controllers faking up SCSI in shitty firmware to actually set
it.