Re: [PATCH RFC 4/4] block: use chunk_sectors when evaluating stacked atomic write limits

[John Garry]

On 06/06/2025 16:23, Nilay Shroff wrote:
> >   	t->atomic_write_hw_unit_min = min(b->atomic_write_hw_unit_min,
> >   					  t->atomic_write_hw_unit_max);
> > -	t->atomic_write_hw_max = min(b->atomic_write_hw_max, t->io_min);
> > +	t->atomic_write_hw_max = min(b->atomic_write_hw_max, chunk_size);
> >   
> >   	return true;
> >   }
> This works well with my NVMe disk which supports atomic writes however the only
> concern is what if in case t->chunk_sectors is also defined for NVMe disk?
> I see that nvme_set_chunk_sectors() initializes the chunk_sectors for NVMe.
> The value which is assigned to lim->chunk_sectors in nvme_set_chunk_sectors()
> represents "noiob" (i.e. Namespace Optimal I/O Boundary). My disk has "noiob"
> set to zero but in case if it's non-zero then would it break the above logic
> for NVMe atomic writes?

Yeah, I think that I need to change the code to account for the bottom 
device setting chunk_sectors.

Thanks,
John