Re: [PATCH v2] scsi: support packing multi-segment in UNMAP command

[Chao Yu]

On 2022/6/15 21:35, Christoph Hellwig wrote:
> On Wed, Jun 15, 2022 at 09:28:46PM +0800, Chao Yu wrote:
> > As SPEC describes that it can support unmapping one or more LBA range
>
> s/SPEC/<insert SPC reference here>/
>
> >   {
> >   	struct scsi_device *sdp = cmd->device;
> >   	struct request *rq = scsi_cmd_to_rq(cmd);
> > +	struct bio *bio;
> >   	struct scsi_disk *sdkp = scsi_disk(rq->q->disk);
> > +	unsigned short segments = blk_rq_nr_discard_segments(rq);
> > +	unsigned int data_len = 8 + 16 * segments, i = 0;
> >   	char *buf;
>
> Nit: for readability I'd move the bio declaration just above the buf
> line.
>
> > +
> > +	__rq_for_each_bio(bio, rq) {
> > +		u64 lba = sectors_to_logical(sdp, bio->bi_iter.bi_sector);
> > +		u32 nr_blocks = sectors_to_logical(sdp, bio_sectors(bio));
> > +
> > +		put_unaligned_be64(lba, &buf[8 + 16 * i]);
> > +		put_unaligned_be32(nr_blocks, &buf[8 + 16 * i + 8]);
>
> Can we have a local variable here?
>
> 	unsigned int data_offset = 8;
>
> 	....

Thanks for the review, I've updated the patch.

Thanks,

> 		put_unaligned_be64(lba, &buf[data_offset]);
> 		put_unaligned_be64(lba, &buf[data_offset + 8]);
> 		data_offset += 16;
> 	}