Re: [PATCH v20 07/12] nvme: add copy offload support

[Nitesh Shetty]

On 01/06/24 08:22AM, Christoph Hellwig wrote:
> On Mon, May 20, 2024 at 03:50:20PM +0530, Nitesh Shetty wrote:
> > +	if (blk_rq_nr_phys_segments(req) != BLK_COPY_MAX_SEGMENTS)
> > +		return BLK_STS_IOERR;
>
> This sounds like BLK_COPY_MAX_SEGMENTS is misnamed.  Right now this is
> not a max segments, but the exact number of segments required.
We will move this check to block layer, with name
BLK_COPY_TOTAL_SEGMENTS.

> >  /*
> >   * Recommended frequency for KATO commands per NVMe 1.4 section 7.12.1:
> > - *
> > + *
>
> Please submit this whitespace fix separately.
>
> > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> > index 8b1edb46880a..1c5974bb23d5 100644
> > --- a/include/linux/blkdev.h
> > +++ b/include/linux/blkdev.h
> > @@ -1287,6 +1287,7 @@ static inline unsigned int bdev_discard_granularity(struct block_device *bdev)
> >
> >  /* maximum copy offload length, this is set to 128MB based on current testing */
> >  #define BLK_COPY_MAX_BYTES		(1 << 27)
> > +#define BLK_COPY_MAX_SEGMENTS		2
>
> ... and this doesn't belong into a NVMe patch.  I'd also expect that
> the block layer would verify this before sending of the request to the driver.
Acked

> > diff --git a/include/linux/nvme.h b/include/linux/nvme.h
> > index 425573202295..5275a0962a02 100644
> > --- a/include/linux/nvme.h
> > +++ b/include/linux/nvme.h
>
> Note that we've usually kept adding new protocol bits to nvme.h separate
> from the implementation in the host or target code.
Acked, will move it to a separate patch.

Thank you,
Nitesh Shetty