Re: [PATCH 21/21] nvme: Support atomic writes

[John Garry]

On 04/10/2023 12:39, Pankaj Raghav wrote:
> > +++ b/drivers/nvme/host/core.c
> > @@ -1926,6 +1926,35 @@ static void nvme_update_disk_info(struct gendisk *disk,
> >   	blk_queue_io_min(disk->queue, phys_bs);
> >   	blk_queue_io_opt(disk->queue, io_opt);
> >   
> > +	atomic_bs = rounddown_pow_of_two(atomic_bs);
> > +	if (id->nsfeat & NVME_NS_FEAT_ATOMICS && id->nawupf) {
> > +		if (id->nabo) {
> > +			dev_err(ns->ctrl->device, "Support atomic NABO=%x\n",
> > +				id->nabo);
> > +		} else {
> > +			u32 boundary = 0;
> > +
> > +			if (le16_to_cpu(id->nabspf))
> > +				boundary = (le16_to_cpu(id->nabspf) + 1) * bs;
> > +
> > +			if (is_power_of_2(boundary) || !boundary) {

note to self/Alan: boundary just needs to be multiple of atomic write 
unit max, and not necessarily a power-of-2

> > +				blk_queue_atomic_write_max_bytes(disk->queue, atomic_bs);
> > +				blk_queue_atomic_write_unit_min_sectors(disk->queue, 1);
> > +				blk_queue_atomic_write_unit_max_sectors(disk->queue,
> > +									atomic_bs / bs);
> blk_queue_atomic_write_unit_[min| max]_sectors expects sectors (512 bytes unit)
> as input but no conversion is done here from device logical block size
> to SECTORs.

Yeah, you are right. I think that we can just use:

blk_queue_atomic_write_unit_max_sectors(disk->queue,
atomic_bs >> SECTOR_SHIFT);

Thanks,
John

> > +				blk_queue_atomic_write_boundary_bytes(disk->queue, boundary);
> > +			} else {
> > +				dev_err(ns->ctrl->device, "Unsupported atomic boundary=0x%x\n",
> > +					boundary);
> > +			}