Re: [PATCH 3/7] rnbd: drop WRITE_SAME support

[Guoqing Jiang <guoqing.jiang@linux.dev>]

On 2/9/22 4:28 PM, Christoph Hellwig wrote:
> REQ_OP_WRITE_SAME was only ever submitted by the legacy Linux zeroing
> code, which has switched to use REQ_OP_WRITE_ZEROES long before rnbd was
> even merged.
>
> Signed-off-by: Christoph Hellwig<hch@lst.de>
> ---
>   drivers/block/rnbd/rnbd-clt.c   | 7 ++-----
>   drivers/block/rnbd/rnbd-clt.h   | 1 -
>   drivers/block/rnbd/rnbd-proto.h | 6 ------
>   drivers/block/rnbd/rnbd-srv.c   | 3 +--
>   4 files changed, 3 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c
> index c08971de369fc..dc192d2738854 100644
> --- a/drivers/block/rnbd/rnbd-clt.c
> +++ b/drivers/block/rnbd/rnbd-clt.c
> @@ -82,7 +82,6 @@ static int rnbd_clt_set_dev_attr(struct rnbd_clt_dev *dev,
>   	dev->nsectors		    = le64_to_cpu(rsp->nsectors);
>   	dev->logical_block_size	    = le16_to_cpu(rsp->logical_block_size);
>   	dev->physical_block_size    = le16_to_cpu(rsp->physical_block_size);
> -	dev->max_write_same_sectors = le32_to_cpu(rsp->max_write_same_sectors);
>   	dev->max_discard_sectors    = le32_to_cpu(rsp->max_discard_sectors);
>   	dev->discard_granularity    = le32_to_cpu(rsp->discard_granularity);
>   	dev->discard_alignment	    = le32_to_cpu(rsp->discard_alignment);
> @@ -1359,8 +1358,6 @@ static void setup_request_queue(struct rnbd_clt_dev *dev)
>   	blk_queue_logical_block_size(dev->queue, dev->logical_block_size);
>   	blk_queue_physical_block_size(dev->queue, dev->physical_block_size);
>   	blk_queue_max_hw_sectors(dev->queue, dev->max_hw_sectors);
> -	blk_queue_max_write_same_sectors(dev->queue,
> -					 dev->max_write_same_sectors);
>   
>   	/*
>   	 * we don't support discards to "discontiguous" segments
> @@ -1610,10 +1607,10 @@ struct rnbd_clt_dev *rnbd_clt_map_device(const char *sessname,
>   	}
>   
>   	rnbd_clt_info(dev,
> -		       "map_device: Device mapped as %s (nsectors: %zu, logical_block_size: %d, physical_block_size: %d, max_write_same_sectors: %d, max_discard_sectors: %d, discard_granularity: %d, discard_alignment: %d, secure_discard: %d, max_segments: %d, max_hw_sectors: %d, rotational: %d, wc: %d, fua: %d)\n",
> +		       "map_device: Device mapped as %s (nsectors: %zu, logical_block_size: %d, physical_block_size: %d, max_discard_sectors: %d, discard_granularity: %d, discard_alignment: %d, secure_discard: %d, max_segments: %d, max_hw_sectors: %d, rotational: %d, wc: %d, fua: %d)\n",
>   		       dev->gd->disk_name, dev->nsectors,
>   		       dev->logical_block_size, dev->physical_block_size,
> -		       dev->max_write_same_sectors, dev->max_discard_sectors,
> +		       dev->max_discard_sectors,
>   		       dev->discard_granularity, dev->discard_alignment,
>   		       dev->secure_discard, dev->max_segments,
>   		       dev->max_hw_sectors, dev->rotational, dev->wc, dev->fua);
> diff --git a/drivers/block/rnbd/rnbd-clt.h b/drivers/block/rnbd/rnbd-clt.h
> index 0c2cae7f39b9f..6946ba23d62e5 100644
> --- a/drivers/block/rnbd/rnbd-clt.h
> +++ b/drivers/block/rnbd/rnbd-clt.h
> @@ -122,7 +122,6 @@ struct rnbd_clt_dev {
>   	bool			wc;
>   	bool			fua;
>   	u32			max_hw_sectors;
> -	u32			max_write_same_sectors;
>   	u32			max_discard_sectors;
>   	u32			discard_granularity;
>   	u32			discard_alignment;

I am planning to remove more members inside struct rnbd_clt_dev.

> diff --git a/drivers/block/rnbd/rnbd-proto.h b/drivers/block/rnbd/rnbd-proto.h
> index de5d5a8df81d7..3eb8b34bd1886 100644
> --- a/drivers/block/rnbd/rnbd-proto.h
> +++ b/drivers/block/rnbd/rnbd-proto.h
> @@ -249,9 +249,6 @@ static inline u32 rnbd_to_bio_flags(u32 rnbd_opf)
>   	case RNBD_OP_SECURE_ERASE:
>   		bio_opf = REQ_OP_SECURE_ERASE;
>   		break;
> -	case RNBD_OP_WRITE_SAME:
> -		bio_opf = REQ_OP_WRITE_SAME;
> -		break;
>   	default:
>   		WARN(1, "Unknown RNBD type: %d (flags %d)\n",
>   		     rnbd_op(rnbd_opf), rnbd_opf);
> @@ -284,9 +281,6 @@ static inline u32 rq_to_rnbd_flags(struct request *rq)
>   	case REQ_OP_SECURE_ERASE:
>   		rnbd_opf = RNBD_OP_SECURE_ERASE;
>   		break;
> -	case REQ_OP_WRITE_SAME:
> -		rnbd_opf = RNBD_OP_WRITE_SAME;
> -		break;
>   	case REQ_OP_FLUSH:
>   		rnbd_opf = RNBD_OP_FLUSH;
>   		break;
> diff --git a/drivers/block/rnbd/rnbd-srv.c b/drivers/block/rnbd/rnbd-srv.c
> index 132e950685d59..0e6b5687f8321 100644
> --- a/drivers/block/rnbd/rnbd-srv.c
> +++ b/drivers/block/rnbd/rnbd-srv.c
> @@ -548,8 +548,7 @@ static void rnbd_srv_fill_msg_open_rsp(struct rnbd_msg_open_rsp *rsp,
>   		cpu_to_le16(rnbd_dev_get_max_segs(rnbd_dev));
>   	rsp->max_hw_sectors =
>   		cpu_to_le32(rnbd_dev_get_max_hw_sects(rnbd_dev));
> -	rsp->max_write_same_sectors =
> -		cpu_to_le32(bdev_write_same(rnbd_dev->bdev));
> +	rsp->max_write_same_sectors = 0;

IIUC, I think we can delete max_write_same_sectors from rsp as well given
the earlier change in setup_request_queue and rnbd_clt_set_dev_attr.

Thanks,
Guoqing