Re: [PATCH 2/2] scsi: scsi_debug: enable sdebug_sector_size > PAGE_SIZE

[John Garry]

On 02/03/2026 12:27, Swarna Prabhu wrote:
> > > > PAGE_SIZE in scsi_debug.
> > Surely the sd driver or block layer should be catching non-compliant HW,
> > right?
> Yes, the sd driver and block layer will catch any non compliant HW.
> > The scsi_debug driver should minic HW, and there is nothing in any SCSI
> > specs which mentions that the sector size needs to be limited to 64KB or the
> > like - am I correct? The useful thing about scsi_debug is that we can
> > pretend to be broken* HW and see if the upper layers catch it.
> >
> > *broken for Linux or non-compliant wrt spec
> As you pointed, the SCSI spec doesn't restrict the sector size to be
> limited to 64 KiB. Earlier block layer had limitations on block size
> upto PAGE_SIZE. With that limitation being addressed and sd driver
> change, sd driver and block layer can handle large block sizes
> correctly. By allowing large sector size on scsi debug we allow
> emulation of spec compliant HW.

Sure, so is there any reason to have those checks in scsi_debug at all? 
Would removing them break that driver and be unsafe?

Thanks,
John

> > > Reviewed-by: Damien Le Moal<dlemoal@xxxxxxxxxx>
> > > Signed-off-by: Swarna Prabhu<s.prabhu@xxxxxxxxxxx>
> > > ---
> > >    drivers/scsi/scsi_debug.c | 8 +-------
> > >    1 file changed, 1 insertion(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> > > index c947655db518..4c6feee87f05 100644
> > > --- a/drivers/scsi/scsi_debug.c
> > > +++ b/drivers/scsi/scsi_debug.c
> > > @@ -8495,13 +8495,7 @@ static int __init scsi_debug_init(void)
> > >    	} else if (sdebug_ndelay > 0)
> > >    		sdebug_jdelay = JDELAY_OVERRIDDEN;
> > > -	switch (sdebug_sector_size) {
> > > -	case  512:
> > > -	case 1024:
> > > -	case 2048:
> > > -	case 4096:
> > > -		break;
> > > -	default:
> > > +	if (blk_validate_block_size(sdebug_sector_size)) {
> > >    		pr_err("invalid sector_size %d\n", sdebug_sector_size);
> > >    		return -EINVAL;