scsi: rnbd: Remove WRITE_SAME support

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.

Link: https://lore.kernel.org/r/20220209082828.2629273-4-hch@lst.deReviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

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);

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;

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;

drivers/block/rnbd/rnbd-srv.c

@@ -558,8 +558,7 @@ 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;
 	rsp->max_discard_sectors =
 		cpu_to_le32(rnbd_dev_get_max_discard_sects(rnbd_dev));
 	rsp->discard_granularity =