RFC: remove REQ_OP_WRITE_SAME

RFC: remove REQ_OP_WRITE_SAME

[Christoph Hellwig]

Now that we are using REQ_OP_WRITE_ZEROES for all zeroing needs in the
kernel there is very little use left for REQ_OP_WRITE_SAME.  We only
have two callers left, and both just export optional protocol features
to remote systems: DRBD and the target code.

Do we have any major users of those?  If not removing it will clean up
a few warts in the block layer.

    git://git.infradead.org/users/hch/block.git delete-write-same

Gitweb:

    http://git.infradead.org/users/hch/block.git/shortlog/refs/heads/delete-write-same

RFC: remove REQ_OP_WRITE_SAME

[Christoph Hellwig]

Now that we are using REQ_OP_WRITE_ZEROES for all zeroing needs in the
kernel there is very little use left for REQ_OP_WRITE_SAME.  We only
have two callers left, and both just export optional protocol features
to remote systems: DRBD and the target code.

Do we have any major users of those?  If not removing it will clean up
a few warts in the block layer.

    git://git.infradead.org/users/hch/block.git delete-write-same

Gitweb:

    http://git.infradead.org/users/hch/block.git/shortlog/refs/heads/delete-write-same

[PATCH 1/8] drbd: drop REQ_OP_WRITE_SAME support

[Christoph Hellwig]

Linux only used it for zeroing, for which we have better methods now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/drbd/drbd_main.c     | 28 ++----------------
 drivers/block/drbd/drbd_nl.c       | 60 --------------------------------------
 drivers/block/drbd/drbd_receiver.c | 38 +++---------------------
 drivers/block/drbd/drbd_req.c      |  1 -
 drivers/block/drbd/drbd_worker.c   |  4 ---
 5 files changed, 7 insertions(+), 124 deletions(-)

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 84455c365f57..183468e0b959 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -931,7 +931,7 @@ void assign_p_sizes_qlim(struct drbd_device *device, struct p_sizes *p, struct r
 		p->qlim->io_min = cpu_to_be32(queue_io_min(q));
 		p->qlim->io_opt = cpu_to_be32(queue_io_opt(q));
 		p->qlim->discard_enabled = blk_queue_discard(q);
-		p->qlim->write_same_capable = !!q->limits.max_write_same_sectors;
+		p->qlim->write_same_capable = 0;
 	} else {
 		q = device->rq_queue;
 		p->qlim->physical_block_size = cpu_to_be32(queue_physical_block_size(q));
@@ -1610,9 +1610,6 @@ static int _drbd_send_bio(struct drbd_peer_device *peer_device, struct bio *bio)
 					 ? 0 : MSG_MORE);
 		if (err)
 			return err;
-		/* REQ_OP_WRITE_SAME has only one segment */
-		if (bio_op(bio) == REQ_OP_WRITE_SAME)
-			break;
 	}
 	return 0;
 }
@@ -1631,9 +1628,6 @@ static int _drbd_send_zc_bio(struct drbd_peer_device *peer_device, struct bio *b
 				      bio_iter_last(bvec, iter) ? 0 : MSG_MORE);
 		if (err)
 			return err;
-		/* REQ_OP_WRITE_SAME has only one segment */
-		if (bio_op(bio) == REQ_OP_WRITE_SAME)
-			break;
 	}
 	return 0;
 }
@@ -1665,7 +1659,6 @@ static u32 bio_flags_to_wire(struct drbd_connection *connection,
 		return  (bio->bi_opf & REQ_SYNC ? DP_RW_SYNC : 0) |
 			(bio->bi_opf & REQ_FUA ? DP_FUA : 0) |
 			(bio->bi_opf & REQ_PREFLUSH ? DP_FLUSH : 0) |
-			(bio_op(bio) == REQ_OP_WRITE_SAME ? DP_WSAME : 0) |
 			(bio_op(bio) == REQ_OP_DISCARD ? DP_DISCARD : 0) |
 			(bio_op(bio) == REQ_OP_WRITE_ZEROES ? DP_DISCARD : 0);
 	else
@@ -1680,7 +1673,6 @@ int drbd_send_dblock(struct drbd_peer_device *peer_device, struct drbd_request *
 	struct drbd_device *device = peer_device->device;
 	struct drbd_socket *sock;
 	struct p_data *p;
-	struct p_wsame *wsame = NULL;
 	void *digest_out;
 	unsigned int dp_flags = 0;
 	int digest_size;
@@ -1717,27 +1709,13 @@ int drbd_send_dblock(struct drbd_peer_device *peer_device, struct drbd_request *
 		err = __send_command(peer_device->connection, device->vnr, sock, P_TRIM, sizeof(*t), NULL, 0);
 		goto out;
 	}
-	if (dp_flags & DP_WSAME) {
-		/* this will only work if DRBD_FF_WSAME is set AND the
-		 * handshake agreed that all nodes and backend devices are
-		 * WRITE_SAME capable and agree on logical_block_size */
-		wsame = (struct p_wsame*)p;
-		digest_out = wsame + 1;
-		wsame->size = cpu_to_be32(req->i.size);
-	} else
-		digest_out = p + 1;
+	digest_out = p + 1;
 
 	/* our digest is still only over the payload.
 	 * TRIM does not carry any payload. */
 	if (digest_size)
 		drbd_csum_bio(peer_device->connection->integrity_tfm, req->master_bio, digest_out);
-	if (wsame) {
-		err =
-		    __send_command(peer_device->connection, device->vnr, sock, P_WSAME,
-				   sizeof(*wsame) + digest_size, NULL,
-				   bio_iovec(req->master_bio).bv_len);
-	} else
-		err =
+	err =
 		    __send_command(peer_device->connection, device->vnr, sock, P_DATA,
 				   sizeof(*p) + digest_size, NULL, req->i.size);
 	if (!err) {
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 02255a0d68b9..53aeed040eb4 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1234,65 +1234,6 @@ static void fixup_discard_if_not_supported(struct request_queue *q)
 	}
 }
 
-static void decide_on_write_same_support(struct drbd_device *device,
-			struct request_queue *q,
-			struct request_queue *b, struct o_qlim *o)
-{
-	struct drbd_peer_device *peer_device = first_peer_device(device);
-	struct drbd_connection *connection = peer_device->connection;
-	bool can_do = b ? b->limits.max_write_same_sectors : true;
-
-	if (can_do && connection->cstate >= C_CONNECTED && !(connection->agreed_features & DRBD_FF_WSAME)) {
-		can_do = false;
-		drbd_info(peer_device, "peer does not support WRITE_SAME\n");
-	}
-
-	if (o) {
-		/* logical block size; queue_logical_block_size(NULL) is 512 */
-		unsigned int peer_lbs = be32_to_cpu(o->logical_block_size);
-		unsigned int me_lbs_b = queue_logical_block_size(b);
-		unsigned int me_lbs = queue_logical_block_size(q);
-
-		if (me_lbs_b != me_lbs) {
-			drbd_warn(device,
-				"logical block size of local backend does not match (drbd:%u, backend:%u); was this a late attach?\n",
-				me_lbs, me_lbs_b);
-			/* rather disable write same than trigger some BUG_ON later in the scsi layer. */
-			can_do = false;
-		}
-		if (me_lbs_b != peer_lbs) {
-			drbd_warn(peer_device, "logical block sizes do not match (me:%u, peer:%u); this may cause problems.\n",
-				me_lbs, peer_lbs);
-			if (can_do) {
-				drbd_dbg(peer_device, "logical block size mismatch: WRITE_SAME disabled.\n");
-				can_do = false;
-			}
-			me_lbs = max(me_lbs, me_lbs_b);
-			/* We cannot change the logical block size of an in-use queue.
-			 * We can only hope that access happens to be properly aligned.
-			 * If not, the peer will likely produce an IO error, and detach. */
-			if (peer_lbs > me_lbs) {
-				if (device->state.role != R_PRIMARY) {
-					blk_queue_logical_block_size(q, peer_lbs);
-					drbd_warn(peer_device, "logical block size set to %u\n", peer_lbs);
-				} else {
-					drbd_warn(peer_device,
-						"current Primary must NOT adjust logical block size (%u -> %u); hope for the best.\n",
-						me_lbs, peer_lbs);
-				}
-			}
-		}
-		if (can_do && !o->write_same_capable) {
-			/* If we introduce an open-coded write-same loop on the receiving side,
-			 * the peer would present itself as "capable". */
-			drbd_dbg(peer_device, "WRITE_SAME disabled (peer device not capable)\n");
-			can_do = false;
-		}
-	}
-
-	blk_queue_max_write_same_sectors(q, can_do ? DRBD_MAX_BBIO_SECTORS : 0);
-}
-
 static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backing_dev *bdev,
 				   unsigned int max_bio_size, struct o_qlim *o)
 {
@@ -1321,7 +1262,6 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
 	blk_queue_max_segments(q, max_segments ? max_segments : BLK_MAX_SEGMENTS);
 	blk_queue_segment_boundary(q, PAGE_SIZE-1);
 	decide_on_discard_support(device, q, b, discard_zeroes_if_aligned);
-	decide_on_write_same_support(device, q, b, o);
 
 	if (b) {
 		blk_queue_stack_limits(q, b);
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 1b0a2be24f39..980d53793007 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -1459,18 +1459,6 @@ static void drbd_issue_peer_discard(struct drbd_device *device, struct drbd_peer
 	drbd_endio_write_sec_final(peer_req);
 }
 
-static void drbd_issue_peer_wsame(struct drbd_device *device,
-				  struct drbd_peer_request *peer_req)
-{
-	struct block_device *bdev = device->ldev->backing_bdev;
-	sector_t s = peer_req->i.sector;
-	sector_t nr = peer_req->i.size >> 9;
-	if (blkdev_issue_write_same(bdev, s, nr, GFP_NOIO, peer_req->pages))
-		peer_req->flags |= EE_WAS_ERROR;
-	drbd_endio_write_sec_final(peer_req);
-}
-
-
 /**
  * drbd_submit_peer_request()
  * @device:	DRBD device.
@@ -1508,7 +1496,7 @@ int drbd_submit_peer_request(struct drbd_device *device,
 	 * Correctness first, performance later.  Next step is to code an
 	 * asynchronous variant of the same.
 	 */
-	if (peer_req->flags & (EE_IS_TRIM|EE_WRITE_SAME)) {
+	if (peer_req->flags & EE_IS_TRIM) {
 		/* wait for all pending IO completions, before we start
 		 * zeroing things out. */
 		conn_wait_active_ee_empty(peer_req->peer_device->connection);
@@ -1527,8 +1515,6 @@ int drbd_submit_peer_request(struct drbd_device *device,
 
 		if (peer_req->flags & EE_IS_TRIM)
 			drbd_issue_peer_discard(device, peer_req);
-		else /* EE_WRITE_SAME */
-			drbd_issue_peer_wsame(device, peer_req);
 		return 0;
 	}
 
@@ -1723,7 +1709,6 @@ read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
 	void *dig_vv = peer_device->connection->int_dig_vv;
 	unsigned long *data;
 	struct p_trim *trim = (pi->cmd == P_TRIM) ? pi->data : NULL;
-	struct p_trim *wsame = (pi->cmd == P_WSAME) ? pi->data : NULL;
 
 	digest_size = 0;
 	if (!trim && peer_device->connection->peer_integrity_tfm) {
@@ -1738,29 +1723,17 @@ read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
 		data_size -= digest_size;
 	}
 
-	/* assume request_size == data_size, but special case trim and wsame. */
+	/* assume request_size == data_size, but special case trim. */
 	ds = data_size;
 	if (trim) {
 		if (!expect(data_size == 0))
 			return NULL;
 		ds = be32_to_cpu(trim->size);
-	} else if (wsame) {
-		if (data_size != queue_logical_block_size(device->rq_queue)) {
-			drbd_err(peer_device, "data size (%u) != drbd logical block size (%u)\n",
-				data_size, queue_logical_block_size(device->rq_queue));
-			return NULL;
-		}
-		if (data_size != bdev_logical_block_size(device->ldev->backing_bdev)) {
-			drbd_err(peer_device, "data size (%u) != backend logical block size (%u)\n",
-				data_size, bdev_logical_block_size(device->ldev->backing_bdev));
-			return NULL;
-		}
-		ds = be32_to_cpu(wsame->size);
 	}
 
 	if (!expect(IS_ALIGNED(ds, 512)))
 		return NULL;
-	if (trim || wsame) {
+	if (trim) {
 		if (!expect(ds <= (DRBD_MAX_BBIO_SECTORS << 9)))
 			return NULL;
 	} else if (!expect(ds <= DRBD_MAX_BIO_SIZE))
@@ -1788,8 +1761,6 @@ read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
 		peer_req->flags |= EE_IS_TRIM;
 		return peer_req;
 	}
-	if (wsame)
-		peer_req->flags |= EE_WRITE_SAME;
 
 	/* receive payload size bytes into page chain */
 	ds = data_size;
@@ -2545,7 +2516,7 @@ static int receive_Data(struct drbd_connection *connection, struct packet_info *
 	 * we wait for all pending requests, respectively wait for
 	 * active_ee to become empty in drbd_submit_peer_request();
 	 * better not add ourselves here. */
-	if ((peer_req->flags & (EE_IS_TRIM|EE_WRITE_SAME)) == 0)
+	if ((peer_req->flags & EE_IS_TRIM) == 0)
 		list_add_tail(&peer_req->w.list, &device->active_ee);
 	spin_unlock_irq(&device->resource->req_lock);
 
@@ -4869,7 +4840,6 @@ static struct data_cmd drbd_cmd_handler[] = {
 	[P_PROTOCOL_UPDATE] = { 1, sizeof(struct p_protocol), receive_protocol },
 	[P_TRIM]	    = { 0, sizeof(struct p_trim), receive_Data },
 	[P_RS_DEALLOCATED]  = { 0, sizeof(struct p_block_desc), receive_rs_deallocated },
-	[P_WSAME]	    = { 1, sizeof(struct p_wsame), receive_Data },
 };
 
 static void drbdd(struct drbd_connection *connection)
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index b5730e17b455..3d3fba937a92 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -58,7 +58,6 @@ static struct drbd_request *drbd_req_new(struct drbd_device *device, struct bio
 
 	drbd_req_make_private_bio(req, bio_src);
 	req->rq_state = (bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0)
-		      | (bio_op(bio_src) == REQ_OP_WRITE_SAME ? RQ_WSAME : 0)
 		      | (bio_op(bio_src) == REQ_OP_WRITE_ZEROES ? RQ_UNMAP : 0)
 		      | (bio_op(bio_src) == REQ_OP_DISCARD ? RQ_UNMAP : 0);
 	req->device = device;
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 1afcb4e02d8d..9fad03491250 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -330,10 +330,6 @@ void drbd_csum_bio(struct crypto_ahash *tfm, struct bio *bio, void *digest)
 		sg_set_page(&sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset);
 		ahash_request_set_crypt(req, &sg, NULL, sg.length);
 		crypto_ahash_update(req);
-		/* REQ_OP_WRITE_SAME has only one segment,
-		 * checksum the payload only once. */
-		if (bio_op(bio) == REQ_OP_WRITE_SAME)
-			break;
 	}
 	ahash_request_set_crypt(req, NULL, digest, 0);
 	crypto_ahash_final(req);
-- 
2.11.0

[PATCH 1/8] drbd: drop REQ_OP_WRITE_SAME support

[Christoph Hellwig]

Linux only used it for zeroing, for which we have better methods now.

Signed-off-by: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
---
 drivers/block/drbd/drbd_main.c     | 28 ++----------------
 drivers/block/drbd/drbd_nl.c       | 60 --------------------------------------
 drivers/block/drbd/drbd_receiver.c | 38 +++---------------------
 drivers/block/drbd/drbd_req.c      |  1 -
 drivers/block/drbd/drbd_worker.c   |  4 ---
 5 files changed, 7 insertions(+), 124 deletions(-)

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 84455c365f57..183468e0b959 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -931,7 +931,7 @@ void assign_p_sizes_qlim(struct drbd_device *device, struct p_sizes *p, struct r
 		p->qlim->io_min = cpu_to_be32(queue_io_min(q));
 		p->qlim->io_opt = cpu_to_be32(queue_io_opt(q));
 		p->qlim->discard_enabled = blk_queue_discard(q);
-		p->qlim->write_same_capable = !!q->limits.max_write_same_sectors;
+		p->qlim->write_same_capable = 0;
 	} else {
 		q = device->rq_queue;
 		p->qlim->physical_block_size = cpu_to_be32(queue_physical_block_size(q));
@@ -1610,9 +1610,6 @@ static int _drbd_send_bio(struct drbd_peer_device *peer_device, struct bio *bio)
 					 ? 0 : MSG_MORE);
 		if (err)
 			return err;
-		/* REQ_OP_WRITE_SAME has only one segment */
-		if (bio_op(bio) == REQ_OP_WRITE_SAME)
-			break;
 	}
 	return 0;
 }
@@ -1631,9 +1628,6 @@ static int _drbd_send_zc_bio(struct drbd_peer_device *peer_device, struct bio *b
 				      bio_iter_last(bvec, iter) ? 0 : MSG_MORE);
 		if (err)
 			return err;
-		/* REQ_OP_WRITE_SAME has only one segment */
-		if (bio_op(bio) == REQ_OP_WRITE_SAME)
-			break;
 	}
 	return 0;
 }
@@ -1665,7 +1659,6 @@ static u32 bio_flags_to_wire(struct drbd_connection *connection,
 		return  (bio->bi_opf & REQ_SYNC ? DP_RW_SYNC : 0) |
 			(bio->bi_opf & REQ_FUA ? DP_FUA : 0) |
 			(bio->bi_opf & REQ_PREFLUSH ? DP_FLUSH : 0) |
-			(bio_op(bio) == REQ_OP_WRITE_SAME ? DP_WSAME : 0) |
 			(bio_op(bio) == REQ_OP_DISCARD ? DP_DISCARD : 0) |
 			(bio_op(bio) == REQ_OP_WRITE_ZEROES ? DP_DISCARD : 0);
 	else
@@ -1680,7 +1673,6 @@ int drbd_send_dblock(struct drbd_peer_device *peer_device, struct drbd_request *
 	struct drbd_device *device = peer_device->device;
 	struct drbd_socket *sock;
 	struct p_data *p;
-	struct p_wsame *wsame = NULL;
 	void *digest_out;
 	unsigned int dp_flags = 0;
 	int digest_size;
@@ -1717,27 +1709,13 @@ int drbd_send_dblock(struct drbd_peer_device *peer_device, struct drbd_request *
 		err = __send_command(peer_device->connection, device->vnr, sock, P_TRIM, sizeof(*t), NULL, 0);
 		goto out;
 	}
-	if (dp_flags & DP_WSAME) {
-		/* this will only work if DRBD_FF_WSAME is set AND the
-		 * handshake agreed that all nodes and backend devices are
-		 * WRITE_SAME capable and agree on logical_block_size */
-		wsame = (struct p_wsame*)p;
-		digest_out = wsame + 1;
-		wsame->size = cpu_to_be32(req->i.size);
-	} else
-		digest_out = p + 1;
+	digest_out = p + 1;
 
 	/* our digest is still only over the payload.
 	 * TRIM does not carry any payload. */
 	if (digest_size)
 		drbd_csum_bio(peer_device->connection->integrity_tfm, req->master_bio, digest_out);
-	if (wsame) {
-		err =
-		    __send_command(peer_device->connection, device->vnr, sock, P_WSAME,
-				   sizeof(*wsame) + digest_size, NULL,
-				   bio_iovec(req->master_bio).bv_len);
-	} else
-		err =
+	err =
 		    __send_command(peer_device->connection, device->vnr, sock, P_DATA,
 				   sizeof(*p) + digest_size, NULL, req->i.size);
 	if (!err) {
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 02255a0d68b9..53aeed040eb4 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1234,65 +1234,6 @@ static void fixup_discard_if_not_supported(struct request_queue *q)
 	}
 }
 
-static void decide_on_write_same_support(struct drbd_device *device,
-			struct request_queue *q,
-			struct request_queue *b, struct o_qlim *o)
-{
-	struct drbd_peer_device *peer_device = first_peer_device(device);
-	struct drbd_connection *connection = peer_device->connection;
-	bool can_do = b ? b->limits.max_write_same_sectors : true;
-
-	if (can_do && connection->cstate >= C_CONNECTED && !(connection->agreed_features & DRBD_FF_WSAME)) {
-		can_do = false;
-		drbd_info(peer_device, "peer does not support WRITE_SAME\n");
-	}
-
-	if (o) {
-		/* logical block size; queue_logical_block_size(NULL) is 512 */
-		unsigned int peer_lbs = be32_to_cpu(o->logical_block_size);
-		unsigned int me_lbs_b = queue_logical_block_size(b);
-		unsigned int me_lbs = queue_logical_block_size(q);
-
-		if (me_lbs_b != me_lbs) {
-			drbd_warn(device,
-				"logical block size of local backend does not match (drbd:%u, backend:%u); was this a late attach?\n",
-				me_lbs, me_lbs_b);
-			/* rather disable write same than trigger some BUG_ON later in the scsi layer. */
-			can_do = false;
-		}
-		if (me_lbs_b != peer_lbs) {
-			drbd_warn(peer_device, "logical block sizes do not match (me:%u, peer:%u); this may cause problems.\n",
-				me_lbs, peer_lbs);
-			if (can_do) {
-				drbd_dbg(peer_device, "logical block size mismatch: WRITE_SAME disabled.\n");
-				can_do = false;
-			}
-			me_lbs = max(me_lbs, me_lbs_b);
-			/* We cannot change the logical block size of an in-use queue.
-			 * We can only hope that access happens to be properly aligned.
-			 * If not, the peer will likely produce an IO error, and detach. */
-			if (peer_lbs > me_lbs) {
-				if (device->state.role != R_PRIMARY) {
-					blk_queue_logical_block_size(q, peer_lbs);
-					drbd_warn(peer_device, "logical block size set to %u\n", peer_lbs);
-				} else {
-					drbd_warn(peer_device,
-						"current Primary must NOT adjust logical block size (%u -> %u); hope for the best.\n",
-						me_lbs, peer_lbs);
-				}
-			}
-		}
-		if (can_do && !o->write_same_capable) {
-			/* If we introduce an open-coded write-same loop on the receiving side,
-			 * the peer would present itself as "capable". */
-			drbd_dbg(peer_device, "WRITE_SAME disabled (peer device not capable)\n");
-			can_do = false;
-		}
-	}
-
-	blk_queue_max_write_same_sectors(q, can_do ? DRBD_MAX_BBIO_SECTORS : 0);
-}
-
 static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backing_dev *bdev,
 				   unsigned int max_bio_size, struct o_qlim *o)
 {
@@ -1321,7 +1262,6 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
 	blk_queue_max_segments(q, max_segments ? max_segments : BLK_MAX_SEGMENTS);
 	blk_queue_segment_boundary(q, PAGE_SIZE-1);
 	decide_on_discard_support(device, q, b, discard_zeroes_if_aligned);
-	decide_on_write_same_support(device, q, b, o);
 
 	if (b) {
 		blk_queue_stack_limits(q, b);
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 1b0a2be24f39..980d53793007 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -1459,18 +1459,6 @@ static void drbd_issue_peer_discard(struct drbd_device *device, struct drbd_peer
 	drbd_endio_write_sec_final(peer_req);
 }
 
-static void drbd_issue_peer_wsame(struct drbd_device *device,
-				  struct drbd_peer_request *peer_req)
-{
-	struct block_device *bdev = device->ldev->backing_bdev;
-	sector_t s = peer_req->i.sector;
-	sector_t nr = peer_req->i.size >> 9;
-	if (blkdev_issue_write_same(bdev, s, nr, GFP_NOIO, peer_req->pages))
-		peer_req->flags |= EE_WAS_ERROR;
-	drbd_endio_write_sec_final(peer_req);
-}
-
-
 /**
  * drbd_submit_peer_request()
  * @device:	DRBD device.
@@ -1508,7 +1496,7 @@ int drbd_submit_peer_request(struct drbd_device *device,
 	 * Correctness first, performance later.  Next step is to code an
 	 * asynchronous variant of the same.
 	 */
-	if (peer_req->flags & (EE_IS_TRIM|EE_WRITE_SAME)) {
+	if (peer_req->flags & EE_IS_TRIM) {
 		/* wait for all pending IO completions, before we start
 		 * zeroing things out. */
 		conn_wait_active_ee_empty(peer_req->peer_device->connection);
@@ -1527,8 +1515,6 @@ int drbd_submit_peer_request(struct drbd_device *device,
 
 		if (peer_req->flags & EE_IS_TRIM)
 			drbd_issue_peer_discard(device, peer_req);
-		else /* EE_WRITE_SAME */
-			drbd_issue_peer_wsame(device, peer_req);
 		return 0;
 	}
 
@@ -1723,7 +1709,6 @@ read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
 	void *dig_vv = peer_device->connection->int_dig_vv;
 	unsigned long *data;
 	struct p_trim *trim = (pi->cmd == P_TRIM) ? pi->data : NULL;
-	struct p_trim *wsame = (pi->cmd == P_WSAME) ? pi->data : NULL;
 
 	digest_size = 0;
 	if (!trim && peer_device->connection->peer_integrity_tfm) {
@@ -1738,29 +1723,17 @@ read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
 		data_size -= digest_size;
 	}
 
-	/* assume request_size == data_size, but special case trim and wsame. */
+	/* assume request_size == data_size, but special case trim. */
 	ds = data_size;
 	if (trim) {
 		if (!expect(data_size == 0))
 			return NULL;
 		ds = be32_to_cpu(trim->size);
-	} else if (wsame) {
-		if (data_size != queue_logical_block_size(device->rq_queue)) {
-			drbd_err(peer_device, "data size (%u) != drbd logical block size (%u)\n",
-				data_size, queue_logical_block_size(device->rq_queue));
-			return NULL;
-		}
-		if (data_size != bdev_logical_block_size(device->ldev->backing_bdev)) {
-			drbd_err(peer_device, "data size (%u) != backend logical block size (%u)\n",
-				data_size, bdev_logical_block_size(device->ldev->backing_bdev));
-			return NULL;
-		}
-		ds = be32_to_cpu(wsame->size);
 	}
 
 	if (!expect(IS_ALIGNED(ds, 512)))
 		return NULL;
-	if (trim || wsame) {
+	if (trim) {
 		if (!expect(ds <= (DRBD_MAX_BBIO_SECTORS << 9)))
 			return NULL;
 	} else if (!expect(ds <= DRBD_MAX_BIO_SIZE))
@@ -1788,8 +1761,6 @@ read_in_block(struct drbd_peer_device *peer_device, u64 id, sector_t sector,
 		peer_req->flags |= EE_IS_TRIM;
 		return peer_req;
 	}
-	if (wsame)
-		peer_req->flags |= EE_WRITE_SAME;
 
 	/* receive payload size bytes into page chain */
 	ds = data_size;
@@ -2545,7 +2516,7 @@ static int receive_Data(struct drbd_connection *connection, struct packet_info *
 	 * we wait for all pending requests, respectively wait for
 	 * active_ee to become empty in drbd_submit_peer_request();
 	 * better not add ourselves here. */
-	if ((peer_req->flags & (EE_IS_TRIM|EE_WRITE_SAME)) == 0)
+	if ((peer_req->flags & EE_IS_TRIM) == 0)
 		list_add_tail(&peer_req->w.list, &device->active_ee);
 	spin_unlock_irq(&device->resource->req_lock);
 
@@ -4869,7 +4840,6 @@ static struct data_cmd drbd_cmd_handler[] = {
 	[P_PROTOCOL_UPDATE] = { 1, sizeof(struct p_protocol), receive_protocol },
 	[P_TRIM]	    = { 0, sizeof(struct p_trim), receive_Data },
 	[P_RS_DEALLOCATED]  = { 0, sizeof(struct p_block_desc), receive_rs_deallocated },
-	[P_WSAME]	    = { 1, sizeof(struct p_wsame), receive_Data },
 };
 
 static void drbdd(struct drbd_connection *connection)
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index b5730e17b455..3d3fba937a92 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -58,7 +58,6 @@ static struct drbd_request *drbd_req_new(struct drbd_device *device, struct bio
 
 	drbd_req_make_private_bio(req, bio_src);
 	req->rq_state = (bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0)
-		      | (bio_op(bio_src) == REQ_OP_WRITE_SAME ? RQ_WSAME : 0)
 		      | (bio_op(bio_src) == REQ_OP_WRITE_ZEROES ? RQ_UNMAP : 0)
 		      | (bio_op(bio_src) == REQ_OP_DISCARD ? RQ_UNMAP : 0);
 	req->device = device;
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 1afcb4e02d8d..9fad03491250 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -330,10 +330,6 @@ void drbd_csum_bio(struct crypto_ahash *tfm, struct bio *bio, void *digest)
 		sg_set_page(&sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset);
 		ahash_request_set_crypt(req, &sg, NULL, sg.length);
 		crypto_ahash_update(req);
-		/* REQ_OP_WRITE_SAME has only one segment,
-		 * checksum the payload only once. */
-		if (bio_op(bio) == REQ_OP_WRITE_SAME)
-			break;
 	}
 	ahash_request_set_crypt(req, NULL, digest, 0);
 	crypto_ahash_final(req);
-- 
2.11.0

[PATCH 2/8] target: remove iblock WRITE_SAME passthrough support

[Christoph Hellwig]

Use the pscsi driver to support arbitrary command passthrough
instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/target/target_core_iblock.c | 34 ----------------------------------
 1 file changed, 34 deletions(-)

diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index d316ed537d59..9da31970a004 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -415,39 +415,8 @@ iblock_execute_unmap(struct se_cmd *cmd, sector_t lba, sector_t nolb)
 }
 
 static sense_reason_t
-iblock_execute_write_same_direct(struct block_device *bdev, struct se_cmd *cmd)
-{
-	struct se_device *dev = cmd->se_dev;
-	struct scatterlist *sg = &cmd->t_data_sg[0];
-	struct page *page = NULL;
-	int ret;
-
-	if (sg->offset) {
-		page = alloc_page(GFP_KERNEL);
-		if (!page)
-			return TCM_OUT_OF_RESOURCES;
-		sg_copy_to_buffer(sg, cmd->t_data_nents, page_address(page),
-				  dev->dev_attrib.block_size);
-	}
-
-	ret = blkdev_issue_write_same(bdev,
-				target_to_linux_sector(dev, cmd->t_task_lba),
-				target_to_linux_sector(dev,
-					sbc_get_write_same_sectors(cmd)),
-				GFP_KERNEL, page ? page : sg_page(sg));
-	if (page)
-		__free_page(page);
-	if (ret)
-		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
-
-	target_complete_cmd(cmd, GOOD);
-	return 0;
-}
-
-static sense_reason_t
 iblock_execute_write_same(struct se_cmd *cmd)
 {
-	struct block_device *bdev = IBLOCK_DEV(cmd->se_dev)->ibd_bd;
 	struct iblock_req *ibr;
 	struct scatterlist *sg;
 	struct bio *bio;
@@ -472,9 +441,6 @@ iblock_execute_write_same(struct se_cmd *cmd)
 		return TCM_INVALID_CDB_FIELD;
 	}
 
-	if (bdev_write_same(bdev))
-		return iblock_execute_write_same_direct(bdev, cmd);
-
 	ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
 	if (!ibr)
 		goto fail;
-- 
2.11.0

Re: [PATCH 2/8] target: remove iblock WRITE_SAME passthrough support

[Nicholas A. Bellinger]

On Mon, 2017-04-10 at 18:08 +0200, Christoph Hellwig wrote:
> Use the pscsi driver to support arbitrary command passthrough
> instead.
> 

The people who are actively using iblock_execute_write_same_direct() are
doing so in the context of ESX VAAI BlockZero, together with
EXTENDED_COPY and COMPARE_AND_WRITE primitives.  Just using PSCSI is not
an option for them.

In practice though I've not seen any users of IBLOCK WRITE_SAME for
anything other than VAAI BlockZero, so just using blkdev_issue_zeroout()
when available, and falling back to iblock_execute_write_same() if the
WRITE_SAME buffer contains anything other than zeros should be OK.

How about something like the following below..?

This would bring parity to how blkdev_issue_write_same() works atm wrt
to synchronous bio completions.  However, most folks with a raw
make_request or blk-mq backend driver that supports multiple GB/sec of
zero bandwidth end up changing IBLOCK to support asynchronous
REQ_WRITE_SAME completions anyways.

I'd be happy to add support for that using __blkdev_issue_zeroout() once
the basic conversion is in place.

>From ff74012eaff38f9fa0d74aca60507b9964f484ce Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab@linux-iscsi.org>
Date: Tue, 11 Apr 2017 22:21:47 -0700
Subject: [PATCH] target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/target/target_core_iblock.c | 44 +++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 17 deletions(-)

diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index d316ed5..5bfde20 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -86,6 +86,7 @@ static int iblock_configure_device(struct se_device *dev)
 	struct block_device *bd = NULL;
 	struct blk_integrity *bi;
 	fmode_t mode;
+	unsigned int max_write_zeroes_sectors;
 	int ret = -ENOMEM;
 
 	if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
@@ -129,7 +130,11 @@ static int iblock_configure_device(struct se_device *dev)
 	 * Enable write same emulation for IBLOCK and use 0xFFFF as
 	 * the smaller WRITE_SAME(10) only has a two-byte block count.
 	 */
-	dev->dev_attrib.max_write_same_len = 0xFFFF;
+	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);
+	if (max_write_zeroes_sectors)
+		dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;
+	else
+		dev->dev_attrib.max_write_same_len = 0xFFFF;
 
 	if (blk_queue_nonrot(q))
 		dev->dev_attrib.is_nonrot = 1;
@@ -415,28 +420,31 @@ static void iblock_end_io_flush(struct bio *bio)
 }
 
 static sense_reason_t
-iblock_execute_write_same_direct(struct block_device *bdev, struct se_cmd *cmd)
+iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd)
 {
 	struct se_device *dev = cmd->se_dev;
 	struct scatterlist *sg = &cmd->t_data_sg[0];
-	struct page *page = NULL;
-	int ret;
+	unsigned char *buf, zero = 0x00, *p = &zero;
+	int rc, ret;
 
-	if (sg->offset) {
-		page = alloc_page(GFP_KERNEL);
-		if (!page)
-			return TCM_OUT_OF_RESOURCES;
-		sg_copy_to_buffer(sg, cmd->t_data_nents, page_address(page),
-				  dev->dev_attrib.block_size);
-	}
+	buf = kmap(sg_page(sg)) + sg->offset;
+	if (!buf)
+		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+	/*
+	 * Fall back to block_execute_write_same() slow-path if
+	 * incoming WRITE_SAME payload does not contain zeros.
+	 */
+	rc = memcmp(buf, p, cmd->data_length);
+	kunmap(sg_page(sg));
+
+	if (rc)
+		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 
-	ret = blkdev_issue_write_same(bdev,
+	ret = blkdev_issue_zeroout(bdev,
 				target_to_linux_sector(dev, cmd->t_task_lba),
 				target_to_linux_sector(dev,
 					sbc_get_write_same_sectors(cmd)),
-				GFP_KERNEL, page ? page : sg_page(sg));
-	if (page)
-		__free_page(page);
+				GFP_KERNEL, false);
 	if (ret)
 		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 
@@ -472,8 +480,10 @@ static void iblock_end_io_flush(struct bio *bio)
 		return TCM_INVALID_CDB_FIELD;
 	}
 
-	if (bdev_write_same(bdev))
-		return iblock_execute_write_same_direct(bdev, cmd);
+	if (bdev_write_zeroes_sectors(bdev)) {
+		if (!iblock_execute_zero_out(bdev, cmd))
+			return 0;
+	}
 
 	ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
 	if (!ibr)

Re: [PATCH 2/8] target: remove iblock WRITE_SAME passthrough support

[Nicholas A. Bellinger]

On Mon, 2017-04-10 at 18:08 +0200, Christoph Hellwig wrote:
> Use the pscsi driver to support arbitrary command passthrough
> instead.
> 

The people who are actively using iblock_execute_write_same_direct() are
doing so in the context of ESX VAAI BlockZero, together with
EXTENDED_COPY and COMPARE_AND_WRITE primitives.  Just using PSCSI is not
an option for them.

In practice though I've not seen any users of IBLOCK WRITE_SAME for
anything other than VAAI BlockZero, so just using blkdev_issue_zeroout()
when available, and falling back to iblock_execute_write_same() if the
WRITE_SAME buffer contains anything other than zeros should be OK.

How about something like the following below..?

This would bring parity to how blkdev_issue_write_same() works atm wrt
to synchronous bio completions.  However, most folks with a raw
make_request or blk-mq backend driver that supports multiple GB/sec of
zero bandwidth end up changing IBLOCK to support asynchronous
REQ_WRITE_SAME completions anyways.

I'd be happy to add support for that using __blkdev_issue_zeroout() once
the basic conversion is in place.

From ff74012eaff38f9fa0d74aca60507b9964f484ce Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab@linux-iscsi.org>
Date: Tue, 11 Apr 2017 22:21:47 -0700
Subject: [PATCH] target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/target/target_core_iblock.c | 44 +++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 17 deletions(-)

diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index d316ed5..5bfde20 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -86,6 +86,7 @@ static int iblock_configure_device(struct se_device *dev)
 	struct block_device *bd = NULL;
 	struct blk_integrity *bi;
 	fmode_t mode;
+	unsigned int max_write_zeroes_sectors;
 	int ret = -ENOMEM;
 
 	if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
@@ -129,7 +130,11 @@ static int iblock_configure_device(struct se_device *dev)
 	 * Enable write same emulation for IBLOCK and use 0xFFFF as
 	 * the smaller WRITE_SAME(10) only has a two-byte block count.
 	 */
-	dev->dev_attrib.max_write_same_len = 0xFFFF;
+	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);
+	if (max_write_zeroes_sectors)
+		dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;
+	else
+		dev->dev_attrib.max_write_same_len = 0xFFFF;
 
 	if (blk_queue_nonrot(q))
 		dev->dev_attrib.is_nonrot = 1;
@@ -415,28 +420,31 @@ static void iblock_end_io_flush(struct bio *bio)
 }
 
 static sense_reason_t
-iblock_execute_write_same_direct(struct block_device *bdev, struct se_cmd *cmd)
+iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd)
 {
 	struct se_device *dev = cmd->se_dev;
 	struct scatterlist *sg = &cmd->t_data_sg[0];
-	struct page *page = NULL;
-	int ret;
+	unsigned char *buf, zero = 0x00, *p = &zero;
+	int rc, ret;
 
-	if (sg->offset) {
-		page = alloc_page(GFP_KERNEL);
-		if (!page)
-			return TCM_OUT_OF_RESOURCES;
-		sg_copy_to_buffer(sg, cmd->t_data_nents, page_address(page),
-				  dev->dev_attrib.block_size);
-	}
+	buf = kmap(sg_page(sg)) + sg->offset;
+	if (!buf)
+		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+	/*
+	 * Fall back to block_execute_write_same() slow-path if
+	 * incoming WRITE_SAME payload does not contain zeros.
+	 */
+	rc = memcmp(buf, p, cmd->data_length);
+	kunmap(sg_page(sg));
+
+	if (rc)
+		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 
-	ret = blkdev_issue_write_same(bdev,
+	ret = blkdev_issue_zeroout(bdev,
 				target_to_linux_sector(dev, cmd->t_task_lba),
 				target_to_linux_sector(dev,
 					sbc_get_write_same_sectors(cmd)),
-				GFP_KERNEL, page ? page : sg_page(sg));
-	if (page)
-		__free_page(page);
+				GFP_KERNEL, false);
 	if (ret)
 		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 
@@ -472,8 +480,10 @@ static void iblock_end_io_flush(struct bio *bio)
 		return TCM_INVALID_CDB_FIELD;
 	}
 
-	if (bdev_write_same(bdev))
-		return iblock_execute_write_same_direct(bdev, cmd);
+	if (bdev_write_zeroes_sectors(bdev)) {
+		if (!iblock_execute_zero_out(bdev, cmd))
+			return 0;
+	}
 
 	ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
 	if (!ibr)

Re: [PATCH 2/8] target: remove iblock WRITE_SAME passthrough support

[Christoph Hellwig]

Hi Nic,

this patch looks fine, and I'll include it for the next post.  I'll
move some of the explanation in this mail into the patch, though.

Re: [PATCH 2/8] target: remove iblock WRITE_SAME passthrough support

[Nicholas A. Bellinger]

Hey HCH & Jens,

Is this already queued up for v4.13 to address the missing LBPRZ feature
bit..?

If not, I'll happy to take it via target-pending along with the
following to re-enable it via max_write_zeroes_sectors.

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index d2f089c..e7caf78 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -851,7 +851,7 @@ bool target_configure_unmap_from_queue(struct se_dev_attrib *attrib,
        attrib->unmap_granularity = q->limits.discard_granularity / block_size;
        attrib->unmap_granularity_alignment = q->limits.discard_alignment /
                                                                block_size;
-       attrib->unmap_zeroes_data = 0;
+       attrib->unmap_zeroes_data = (q->limits.max_write_zeroes_sectors);
        return true;
 }
 EXPORT_SYMBOL(target_configure_unmap_from_queue);

Any objections..?

On Tue, 2017-04-11 at 22:30 -0700, Nicholas A. Bellinger wrote:
> On Mon, 2017-04-10 at 18:08 +0200, Christoph Hellwig wrote:
> > Use the pscsi driver to support arbitrary command passthrough
> > instead.
> > 
> 
> The people who are actively using iblock_execute_write_same_direct() are
> doing so in the context of ESX VAAI BlockZero, together with
> EXTENDED_COPY and COMPARE_AND_WRITE primitives.  Just using PSCSI is not
> an option for them.
> 
> In practice though I've not seen any users of IBLOCK WRITE_SAME for
> anything other than VAAI BlockZero, so just using blkdev_issue_zeroout()
> when available, and falling back to iblock_execute_write_same() if the
> WRITE_SAME buffer contains anything other than zeros should be OK.
> 
> How about something like the following below..?
> 
> This would bring parity to how blkdev_issue_write_same() works atm wrt
> to synchronous bio completions.  However, most folks with a raw
> make_request or blk-mq backend driver that supports multiple GB/sec of
> zero bandwidth end up changing IBLOCK to support asynchronous
> REQ_WRITE_SAME completions anyways.
> 
> I'd be happy to add support for that using __blkdev_issue_zeroout() once
> the basic conversion is in place.
> 
> From ff74012eaff38f9fa0d74aca60507b9964f484ce Mon Sep 17 00:00:00 2001
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> Date: Tue, 11 Apr 2017 22:21:47 -0700
> Subject: [PATCH] target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout
> 
> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
> ---
>  drivers/target/target_core_iblock.c | 44 +++++++++++++++++++++++--------------
>  1 file changed, 27 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
> index d316ed5..5bfde20 100644
> --- a/drivers/target/target_core_iblock.c
> +++ b/drivers/target/target_core_iblock.c
> @@ -86,6 +86,7 @@ static int iblock_configure_device(struct se_device *dev)
>  	struct block_device *bd = NULL;
>  	struct blk_integrity *bi;
>  	fmode_t mode;
> +	unsigned int max_write_zeroes_sectors;
>  	int ret = -ENOMEM;
>  
>  	if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
> @@ -129,7 +130,11 @@ static int iblock_configure_device(struct se_device *dev)
>  	 * Enable write same emulation for IBLOCK and use 0xFFFF as
>  	 * the smaller WRITE_SAME(10) only has a two-byte block count.
>  	 */
> -	dev->dev_attrib.max_write_same_len = 0xFFFF;
> +	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);
> +	if (max_write_zeroes_sectors)
> +		dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;
> +	else
> +		dev->dev_attrib.max_write_same_len = 0xFFFF;
>  
>  	if (blk_queue_nonrot(q))
>  		dev->dev_attrib.is_nonrot = 1;
> @@ -415,28 +420,31 @@ static void iblock_end_io_flush(struct bio *bio)
>  }
>  
>  static sense_reason_t
> -iblock_execute_write_same_direct(struct block_device *bdev, struct se_cmd *cmd)
> +iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd)
>  {
>  	struct se_device *dev = cmd->se_dev;
>  	struct scatterlist *sg = &cmd->t_data_sg[0];
> -	struct page *page = NULL;
> -	int ret;
> +	unsigned char *buf, zero = 0x00, *p = &zero;
> +	int rc, ret;
>  
> -	if (sg->offset) {
> -		page = alloc_page(GFP_KERNEL);
> -		if (!page)
> -			return TCM_OUT_OF_RESOURCES;
> -		sg_copy_to_buffer(sg, cmd->t_data_nents, page_address(page),
> -				  dev->dev_attrib.block_size);
> -	}
> +	buf = kmap(sg_page(sg)) + sg->offset;
> +	if (!buf)
> +		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> +	/*
> +	 * Fall back to block_execute_write_same() slow-path if
> +	 * incoming WRITE_SAME payload does not contain zeros.
> +	 */
> +	rc = memcmp(buf, p, cmd->data_length);
> +	kunmap(sg_page(sg));
> +
> +	if (rc)
> +		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>  
> -	ret = blkdev_issue_write_same(bdev,
> +	ret = blkdev_issue_zeroout(bdev,
>  				target_to_linux_sector(dev, cmd->t_task_lba),
>  				target_to_linux_sector(dev,
>  					sbc_get_write_same_sectors(cmd)),
> -				GFP_KERNEL, page ? page : sg_page(sg));
> -	if (page)
> -		__free_page(page);
> +				GFP_KERNEL, false);
>  	if (ret)
>  		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>  
> @@ -472,8 +480,10 @@ static void iblock_end_io_flush(struct bio *bio)
>  		return TCM_INVALID_CDB_FIELD;
>  	}
>  
> -	if (bdev_write_same(bdev))
> -		return iblock_execute_write_same_direct(bdev, cmd);
> +	if (bdev_write_zeroes_sectors(bdev)) {
> +		if (!iblock_execute_zero_out(bdev, cmd))
> +			return 0;
> +	}
>  
>  	ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
>  	if (!ibr)

Re: [PATCH 2/8] target: remove iblock WRITE_SAME passthrough support

[Nicholas A. Bellinger]

Hey HCH & Jens,

Is this already queued up for v4.13 to address the missing LBPRZ feature
bit..?

If not, I'll happy to take it via target-pending along with the
following to re-enable it via max_write_zeroes_sectors.

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index d2f089c..e7caf78 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -851,7 +851,7 @@ bool target_configure_unmap_from_queue(struct se_dev_attrib *attrib,
        attrib->unmap_granularity = q->limits.discard_granularity / block_size;
        attrib->unmap_granularity_alignment = q->limits.discard_alignment /
                                                                block_size;
-       attrib->unmap_zeroes_data = 0;
+       attrib->unmap_zeroes_data = (q->limits.max_write_zeroes_sectors);
        return true;
 }
 EXPORT_SYMBOL(target_configure_unmap_from_queue);

Any objections..?

On Tue, 2017-04-11 at 22:30 -0700, Nicholas A. Bellinger wrote:
> On Mon, 2017-04-10 at 18:08 +0200, Christoph Hellwig wrote:
> > Use the pscsi driver to support arbitrary command passthrough
> > instead.
> > 
> 
> The people who are actively using iblock_execute_write_same_direct() are
> doing so in the context of ESX VAAI BlockZero, together with
> EXTENDED_COPY and COMPARE_AND_WRITE primitives.  Just using PSCSI is not
> an option for them.
> 
> In practice though I've not seen any users of IBLOCK WRITE_SAME for
> anything other than VAAI BlockZero, so just using blkdev_issue_zeroout()
> when available, and falling back to iblock_execute_write_same() if the
> WRITE_SAME buffer contains anything other than zeros should be OK.
> 
> How about something like the following below..?
> 
> This would bring parity to how blkdev_issue_write_same() works atm wrt
> to synchronous bio completions.  However, most folks with a raw
> make_request or blk-mq backend driver that supports multiple GB/sec of
> zero bandwidth end up changing IBLOCK to support asynchronous
> REQ_WRITE_SAME completions anyways.
> 
> I'd be happy to add support for that using __blkdev_issue_zeroout() once
> the basic conversion is in place.
> 
> From ff74012eaff38f9fa0d74aca60507b9964f484ce Mon Sep 17 00:00:00 2001
> From: Nicholas Bellinger <nab-IzHhD5pYlfBP7FQvKIMDCQ@public.gmane.org>
> Date: Tue, 11 Apr 2017 22:21:47 -0700
> Subject: [PATCH] target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout
> 
> Signed-off-by: Nicholas Bellinger <nab-IzHhD5pYlfBP7FQvKIMDCQ@public.gmane.org>
> ---
>  drivers/target/target_core_iblock.c | 44 +++++++++++++++++++++++--------------
>  1 file changed, 27 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
> index d316ed5..5bfde20 100644
> --- a/drivers/target/target_core_iblock.c
> +++ b/drivers/target/target_core_iblock.c
> @@ -86,6 +86,7 @@ static int iblock_configure_device(struct se_device *dev)
>  	struct block_device *bd = NULL;
>  	struct blk_integrity *bi;
>  	fmode_t mode;
> +	unsigned int max_write_zeroes_sectors;
>  	int ret = -ENOMEM;
>  
>  	if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
> @@ -129,7 +130,11 @@ static int iblock_configure_device(struct se_device *dev)
>  	 * Enable write same emulation for IBLOCK and use 0xFFFF as
>  	 * the smaller WRITE_SAME(10) only has a two-byte block count.
>  	 */
> -	dev->dev_attrib.max_write_same_len = 0xFFFF;
> +	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);
> +	if (max_write_zeroes_sectors)
> +		dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;
> +	else
> +		dev->dev_attrib.max_write_same_len = 0xFFFF;
>  
>  	if (blk_queue_nonrot(q))
>  		dev->dev_attrib.is_nonrot = 1;
> @@ -415,28 +420,31 @@ static void iblock_end_io_flush(struct bio *bio)
>  }
>  
>  static sense_reason_t
> -iblock_execute_write_same_direct(struct block_device *bdev, struct se_cmd *cmd)
> +iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd)
>  {
>  	struct se_device *dev = cmd->se_dev;
>  	struct scatterlist *sg = &cmd->t_data_sg[0];
> -	struct page *page = NULL;
> -	int ret;
> +	unsigned char *buf, zero = 0x00, *p = &zero;
> +	int rc, ret;
>  
> -	if (sg->offset) {
> -		page = alloc_page(GFP_KERNEL);
> -		if (!page)
> -			return TCM_OUT_OF_RESOURCES;
> -		sg_copy_to_buffer(sg, cmd->t_data_nents, page_address(page),
> -				  dev->dev_attrib.block_size);
> -	}
> +	buf = kmap(sg_page(sg)) + sg->offset;
> +	if (!buf)
> +		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> +	/*
> +	 * Fall back to block_execute_write_same() slow-path if
> +	 * incoming WRITE_SAME payload does not contain zeros.
> +	 */
> +	rc = memcmp(buf, p, cmd->data_length);
> +	kunmap(sg_page(sg));
> +
> +	if (rc)
> +		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>  
> -	ret = blkdev_issue_write_same(bdev,
> +	ret = blkdev_issue_zeroout(bdev,
>  				target_to_linux_sector(dev, cmd->t_task_lba),
>  				target_to_linux_sector(dev,
>  					sbc_get_write_same_sectors(cmd)),
> -				GFP_KERNEL, page ? page : sg_page(sg));
> -	if (page)
> -		__free_page(page);
> +				GFP_KERNEL, false);
>  	if (ret)
>  		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>  
> @@ -472,8 +480,10 @@ static void iblock_end_io_flush(struct bio *bio)
>  		return TCM_INVALID_CDB_FIELD;
>  	}
>  
> -	if (bdev_write_same(bdev))
> -		return iblock_execute_write_same_direct(bdev, cmd);
> +	if (bdev_write_zeroes_sectors(bdev)) {
> +		if (!iblock_execute_zero_out(bdev, cmd))
> +			return 0;
> +	}
>  
>  	ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
>  	if (!ibr)

Re: [PATCH 2/8] target: remove iblock WRITE_SAME passthrough support

[Christoph Hellwig]

On Wed, May 31, 2017 at 11:27:01PM -0700, Nicholas A. Bellinger wrote:
> Hey HCH & Jens,
> 
> Is this already queued up for v4.13 to address the missing LBPRZ feature
> bit..?
> 
> If not, I'll happy to take it via target-pending along with the
> following to re-enable it via max_write_zeroes_sectors.

It's not queued up.  Feel free to take it through the target tree.

Re: [PATCH 2/8] target: remove iblock WRITE_SAME passthrough support

[Christoph Hellwig]

On Wed, May 31, 2017 at 11:27:01PM -0700, Nicholas A. Bellinger wrote:
> Hey HCH & Jens,
> 
> Is this already queued up for v4.13 to address the missing LBPRZ feature
> bit..?
> 
> If not, I'll happy to take it via target-pending along with the
> following to re-enable it via max_write_zeroes_sectors.

It's not queued up.  Feel free to take it through the target tree.

Re: [PATCH 2/8] target: remove iblock WRITE_SAME passthrough support

[Bryant G. Ly]

On 4/12/17 12:30 AM, Nicholas A. Bellinger wrote:

> On Mon, 2017-04-10 at 18:08 +0200, Christoph Hellwig wrote:
>> Use the pscsi driver to support arbitrary command passthrough
>> instead.
>>
> The people who are actively using iblock_execute_write_same_direct() are
> doing so in the context of ESX VAAI BlockZero, together with
> EXTENDED_COPY and COMPARE_AND_WRITE primitives.  Just using PSCSI is not
> an option for them.
>
> In practice though I've not seen any users of IBLOCK WRITE_SAME for
> anything other than VAAI BlockZero, so just using blkdev_issue_zeroout()
> when available, and falling back to iblock_execute_write_same() if the
> WRITE_SAME buffer contains anything other than zeros should be OK.
>
> How about something like the following below..?
>
> This would bring parity to how blkdev_issue_write_same() works atm wrt
> to synchronous bio completions.  However, most folks with a raw
> make_request or blk-mq backend driver that supports multiple GB/sec of
> zero bandwidth end up changing IBLOCK to support asynchronous
> REQ_WRITE_SAME completions anyways.
>
> I'd be happy to add support for that using __blkdev_issue_zeroout() once
> the basic conversion is in place.
>
> From ff74012eaff38f9fa0d74aca60507b9964f484ce Mon Sep 17 00:00:00 2001
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> Date: Tue, 11 Apr 2017 22:21:47 -0700
> Subject: [PATCH] target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout
>
> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
> ---
>  drivers/target/target_core_iblock.c | 44 +++++++++++++++++++++++--------------
>  1 file changed, 27 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
> index d316ed5..5bfde20 100644
> --- a/drivers/target/target_core_iblock.c
> +++ b/drivers/target/target_core_iblock.c
> @@ -86,6 +86,7 @@ static int iblock_configure_device(struct se_device *dev)
>  	struct block_device *bd = NULL;
>  	struct blk_integrity *bi;
>  	fmode_t mode;
> +	unsigned int max_write_zeroes_sectors;
>  	int ret = -ENOMEM;
>
>  	if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
> @@ -129,7 +130,11 @@ static int iblock_configure_device(struct se_device *dev)
>  	 * Enable write same emulation for IBLOCK and use 0xFFFF as
>  	 * the smaller WRITE_SAME(10) only has a two-byte block count.
>  	 */
> -	dev->dev_attrib.max_write_same_len = 0xFFFF;
> +	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);
> +	if (max_write_zeroes_sectors)
> +		dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;
> +	else
> +		dev->dev_attrib.max_write_same_len = 0xFFFF;
>
>  	if (blk_queue_nonrot(q))
>  		dev->dev_attrib.is_nonrot = 1;
> @@ -415,28 +420,31 @@ static void iblock_end_io_flush(struct bio *bio)
>  }
>
>  static sense_reason_t
> -iblock_execute_write_same_direct(struct block_device *bdev, struct se_cmd *cmd)
> +iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd)
>  {
>  	struct se_device *dev = cmd->se_dev;
>  	struct scatterlist *sg = &cmd->t_data_sg[0];
> -	struct page *page = NULL;
> -	int ret;
> +	unsigned char *buf, zero = 0x00, *p = &zero;
> +	int rc, ret;
>
> -	if (sg->offset) {
> -		page = alloc_page(GFP_KERNEL);
> -		if (!page)
> -			return TCM_OUT_OF_RESOURCES;
> -		sg_copy_to_buffer(sg, cmd->t_data_nents, page_address(page),
> -				  dev->dev_attrib.block_size);
> -	}
> +	buf = kmap(sg_page(sg)) + sg->offset;
> +	if (!buf)
> +		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> +	/*
> +	 * Fall back to block_execute_write_same() slow-path if
> +	 * incoming WRITE_SAME payload does not contain zeros.
> +	 */
> +	rc = memcmp(buf, p, cmd->data_length);
> +	kunmap(sg_page(sg));
> +

I recently pulled in this patch and I am getting:

[  716.756756] ------------[ cut here ]------------
[  716.756757] kernel BUG at /build/linux-hwe-edge-F6_Smd/linux-hwe-edge-4.13.0/lib/string.c:985!
[  716.756762] Oops: Exception in kernel mode, sig: 5 [#1]
[  716.756764] SMP NR_CPUS=2048 
[  716.756765] NUMA 
[  716.756767] pSeries
[  716.756769] Modules linked in: hvcs(OE) hvcserver dm_snapshot dm_bufio ip6table_raw xt_CT xt_mac xt_tcpudp xt_comment xt_physdev xt_set ip_set_hash_net ip_set rpadlpar_io rpaphp iptable_raw target_core_pscsi(OE) target_core_file(OE) target_core_iblock(OE) iscsi_target_mod(OE) dccp_diag dccp tcp_diag udp_diag inet_diag unix_diag af_packet_diag netlink_diag vport_vxlan vxlan ip6_udp_tunnel udp_tunnel openvswitch nf_nat_ipv6 target_core_user(OE) uio binfmt_misc ibmvmc(OE) pseries_rng vmx_crypto crct10dif_vpmsum xt_conntrack nf_nat_ftp nf_conntrack_ftp nf_conntrack_netlink nfnetlink nf_conntrack_netbios_ns nf_conntrack_broadcast nf_conntrack_ipv6 nf_defrag_ipv6 nbd ipt_REJECT nf_reject_ipv4 ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack
[  716.756825]  iptable_mangle iptable_filter ip_tables ip6table_filter ip6_tables ebtables x_tables br_netfilter bridge stp llc ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq raid1 raid0 multipath linear mlx4_en dm_round_robin ses enclosure scsi_transport_sas ibmvscsis(OE) target_core_mod(OE) ibmveth(OE) mlx5_core mlx4_core bnx2x mdio libcrc32c crc32c_vpmsum mlxfw ipr devlink tg3 scsi_dh_emc scsi_dh_rdac scsi_dh_alua dm_multipath
[  716.756872] CPU: 1 PID: 3685 Comm: kworker/1:2 Tainted: G           OE   4.13.0-16-generic #19~16.04.3-Ubuntu
[  716.756880] Workqueue: ibmvscsis30000008 ibmvscsis_scheduler [ibmvscsis]
[  716.756883] task: c0000001ee076a00 task.stack: c0000001b536c000
[  716.756885] NIP: c000000000c26620 LR: c000000000c2661c CTR: 0000000000655170
[  716.756888] REGS: c0000001b536f590 TRAP: 0700   Tainted: G           OE    (4.13.0-16-generic)
[  716.756891] MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>
[  716.756896]   CR: 28482222  XER: 20000003
[  716.756899] CFAR: c000000000179740 SOFTE: 1 
               GPR00: c000000000c2661c c0000001b536f810 c0000000015c2b00 0000000000000022 
               GPR04: c0000001f704ade8 c0000001f7062068 0000000000000003 ffffffffffffffff 
               GPR08: 0000000000000007 c0000000010d1a74 00000001f5f80000 0000000000000066 
               GPR12: 0000000000002200 c00000000fac0a80 c000000000129158 c0000001f2b5bb00 
               GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
               GPR20: 0000000000000000 0000000000000000 0000000000000000 fffffffffffffef7 
               GPR24: 0000000000000000 f0000000007a82c0 00000000000003f0 0000000000648010 
               GPR28: c00000004394fbd0 c0000001f36c2780 c0000001ddb0e700 c0000001e391a000 
[  716.756932] NIP [c000000000c26620] fortify_panic+0x28/0x38
[  716.756935] LR [c000000000c2661c] fortify_panic+0x24/0x38
[  716.756937] Call Trace:
[  716.756939] [c0000001b536f810] [c000000000c2661c] fortify_panic+0x24/0x38 (unreliable)
[  716.756944] [c0000001b536f870] [d000000013c30bf8] iblock_execute_write_same+0x3b8/0x3c0 [target_core_iblock]
[  716.756955] [c0000001b536f920] [d00000000b6537b4] __target_execute_cmd+0x54/0x150 [target_core_mod]
[  716.756960] [c0000001b536f950] [d00000000b822c90] ibmvscsis_write_pending+0x70/0xc0 [ibmvscsis]
[  716.756969] [c0000001b536f9c0] [d00000000b654f28] transport_generic_new_cmd+0x318/0x370 [target_core_mod]
[  716.756979] [c0000001b536fa40] [d00000000b654fe4] transport_handle_cdb_direct+0x64/0xd0 [target_core_mod]
[  716.756988] [c0000001b536fab0] [d00000000b6551f8] target_submit_cmd_map_sgls+0x1a8/0x320 [target_core_mod]
[  716.756998] [c0000001b536fb40] [d00000000b6553b8] target_submit_cmd+0x48/0x60 [target_core_mod]
[  716.757002] [c0000001b536fbe0] [d00000000b824bb0] ibmvscsis_scheduler+0x370/0x600 [ibmvscsis]
[  716.757007] [c0000001b536fca0] [c0000000001200fc] process_one_work+0x1ec/0x580
[  716.757010] [c0000001b536fd30] [c000000000120528] worker_thread+0x98/0x5d0
[  716.757013] [c0000001b536fdc0] [c0000000001292bc] kthread+0x16c/0x1b0
[  716.757017] [c0000001b536fe30] [c00000000000b4e8] ret_from_kernel_thread+0x5c/0x74
[  716.757020] Instruction dump:
[  716.757022] 7c0803a6 4e800020 3c4c009a 3842c508 7c0802a6 f8010010 f821ffa1 7c641b78 
[  716.757027] 3c62ff98 3863e8b8 4b5530dd 60000000 <0fe00000> 00000000 00000000 00000000 
[  716.757033] ---[ end trace 1f1264fedf09f0b7 ]---

It looks like memcmp is throwing the fortify panic due to size of ptrs being incorrectly
determined at compile time. 

-Bryant 

Re: [PATCH 2/8] target: remove iblock WRITE_SAME passthrough support

[Bryant G. Ly]

On 4/12/17 12:30 AM, Nicholas A. Bellinger wrote:

> On Mon, 2017-04-10 at 18:08 +0200, Christoph Hellwig wrote:
>> Use the pscsi driver to support arbitrary command passthrough
>> instead.
>>
> The people who are actively using iblock_execute_write_same_direct() are
> doing so in the context of ESX VAAI BlockZero, together with
> EXTENDED_COPY and COMPARE_AND_WRITE primitives.  Just using PSCSI is not
> an option for them.
>
> In practice though I've not seen any users of IBLOCK WRITE_SAME for
> anything other than VAAI BlockZero, so just using blkdev_issue_zeroout()
> when available, and falling back to iblock_execute_write_same() if the
> WRITE_SAME buffer contains anything other than zeros should be OK.
>
> How about something like the following below..?
>
> This would bring parity to how blkdev_issue_write_same() works atm wrt
> to synchronous bio completions.  However, most folks with a raw
> make_request or blk-mq backend driver that supports multiple GB/sec of
> zero bandwidth end up changing IBLOCK to support asynchronous
> REQ_WRITE_SAME completions anyways.
>
> I'd be happy to add support for that using __blkdev_issue_zeroout() once
> the basic conversion is in place.
>
> From ff74012eaff38f9fa0d74aca60507b9964f484ce Mon Sep 17 00:00:00 2001
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> Date: Tue, 11 Apr 2017 22:21:47 -0700
> Subject: [PATCH] target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout
>
> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
> ---
>  drivers/target/target_core_iblock.c | 44 +++++++++++++++++++++++--------------
>  1 file changed, 27 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
> index d316ed5..5bfde20 100644
> --- a/drivers/target/target_core_iblock.c
> +++ b/drivers/target/target_core_iblock.c
> @@ -86,6 +86,7 @@ static int iblock_configure_device(struct se_device *dev)
>  	struct block_device *bd = NULL;
>  	struct blk_integrity *bi;
>  	fmode_t mode;
> +	unsigned int max_write_zeroes_sectors;
>  	int ret = -ENOMEM;
>
>  	if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
> @@ -129,7 +130,11 @@ static int iblock_configure_device(struct se_device *dev)
>  	 * Enable write same emulation for IBLOCK and use 0xFFFF as
>  	 * the smaller WRITE_SAME(10) only has a two-byte block count.
>  	 */
> -	dev->dev_attrib.max_write_same_len = 0xFFFF;
> +	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);
> +	if (max_write_zeroes_sectors)
> +		dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;
> +	else
> +		dev->dev_attrib.max_write_same_len = 0xFFFF;
>
>  	if (blk_queue_nonrot(q))
>  		dev->dev_attrib.is_nonrot = 1;
> @@ -415,28 +420,31 @@ static void iblock_end_io_flush(struct bio *bio)
>  }
>
>  static sense_reason_t
> -iblock_execute_write_same_direct(struct block_device *bdev, struct se_cmd *cmd)
> +iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd)
>  {
>  	struct se_device *dev = cmd->se_dev;
>  	struct scatterlist *sg = &cmd->t_data_sg[0];
> -	struct page *page = NULL;
> -	int ret;
> +	unsigned char *buf, zero = 0x00, *p = &zero;
> +	int rc, ret;
>
> -	if (sg->offset) {
> -		page = alloc_page(GFP_KERNEL);
> -		if (!page)
> -			return TCM_OUT_OF_RESOURCES;
> -		sg_copy_to_buffer(sg, cmd->t_data_nents, page_address(page),
> -				  dev->dev_attrib.block_size);
> -	}
> +	buf = kmap(sg_page(sg)) + sg->offset;
> +	if (!buf)
> +		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> +	/*
> +	 * Fall back to block_execute_write_same() slow-path if
> +	 * incoming WRITE_SAME payload does not contain zeros.
> +	 */
> +	rc = memcmp(buf, p, cmd->data_length);
> +	kunmap(sg_page(sg));
> +

I recently pulled in this patch and I am getting:

[  716.756756] ------------[ cut here ]------------
[  716.756757] kernel BUG at /build/linux-hwe-edge-F6_Smd/linux-hwe-edge-4.13.0/lib/string.c:985!
[  716.756762] Oops: Exception in kernel mode, sig: 5 [#1]
[  716.756764] SMP NR_CPUS=2048 
[  716.756765] NUMA 
[  716.756767] pSeries
[  716.756769] Modules linked in: hvcs(OE) hvcserver dm_snapshot dm_bufio ip6table_raw xt_CT xt_mac xt_tcpudp xt_comment xt_physdev xt_set ip_set_hash_net ip_set rpadlpar_io rpaphp iptable_raw target_core_pscsi(OE) target_core_file(OE) target_core_iblock(OE) iscsi_target_mod(OE) dccp_diag dccp tcp_diag udp_diag inet_diag unix_diag af_packet_diag netlink_diag vport_vxlan vxlan ip6_udp_tunnel udp_tunnel openvswitch nf_nat_ipv6 target_core_user(OE) uio binfmt_misc ibmvmc(OE) pseries_rng vmx_crypto crct10dif_vpmsum xt_conntrack nf_nat_ftp nf_conntrack_ftp nf_conntrack_netlink nfnetlink nf_conntrack_netbios_ns nf_conntrack_broadcast nf_conntrack_ipv6 nf_defrag_ipv6 nbd ipt_REJECT nf_reject_ipv4 ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat
  nf_conntrack
[  716.756825]  iptable_mangle iptable_filter ip_tables ip6table_filter ip6_tables ebtables x_tables br_netfilter bridge stp llc ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq raid1 raid0 multipath linear mlx4_en dm_round_robin ses enclosure scsi_transport_sas ibmvscsis(OE) target_core_mod(OE) ibmveth(OE) mlx5_core mlx4_core bnx2x mdio libcrc32c crc32c_vpmsum mlxfw ipr devlink tg3 scsi_dh_emc scsi_dh_rdac scsi_dh_alua dm_multipath
[  716.756872] CPU: 1 PID: 3685 Comm: kworker/1:2 Tainted: G           OE   4.13.0-16-generic #19~16.04.3-Ubuntu
[  716.756880] Workqueue: ibmvscsis30000008 ibmvscsis_scheduler [ibmvscsis]
[  716.756883] task: c0000001ee076a00 task.stack: c0000001b536c000
[  716.756885] NIP: c000000000c26620 LR: c000000000c2661c CTR: 0000000000655170
[  716.756888] REGS: c0000001b536f590 TRAP: 0700   Tainted: G           OE    (4.13.0-16-generic)
[  716.756891] MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>
[  716.756896]   CR: 28482222  XER: 20000003
[  716.756899] CFAR: c000000000179740 SOFTE: 1 
               GPR00: c000000000c2661c c0000001b536f810 c0000000015c2b00 0000000000000022 
               GPR04: c0000001f704ade8 c0000001f7062068 0000000000000003 ffffffffffffffff 
               GPR08: 0000000000000007 c0000000010d1a74 00000001f5f80000 0000000000000066 
               GPR12: 0000000000002200 c00000000fac0a80 c000000000129158 c0000001f2b5bb00 
               GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
               GPR20: 0000000000000000 0000000000000000 0000000000000000 fffffffffffffef7 
               GPR24: 0000000000000000 f0000000007a82c0 00000000000003f0 0000000000648010 
               GPR28: c00000004394fbd0 c0000001f36c2780 c0000001ddb0e700 c0000001e391a000 
[  716.756932] NIP [c000000000c26620] fortify_panic+0x28/0x38
[  716.756935] LR [c000000000c2661c] fortify_panic+0x24/0x38
[  716.756937] Call Trace:
[  716.756939] [c0000001b536f810] [c000000000c2661c] fortify_panic+0x24/0x38 (unreliable)
[  716.756944] [c0000001b536f870] [d000000013c30bf8] iblock_execute_write_same+0x3b8/0x3c0 [target_core_iblock]
[  716.756955] [c0000001b536f920] [d00000000b6537b4] __target_execute_cmd+0x54/0x150 [target_core_mod]
[  716.756960] [c0000001b536f950] [d00000000b822c90] ibmvscsis_write_pending+0x70/0xc0 [ibmvscsis]
[  716.756969] [c0000001b536f9c0] [d00000000b654f28] transport_generic_new_cmd+0x318/0x370 [target_core_mod]
[  716.756979] [c0000001b536fa40] [d00000000b654fe4] transport_handle_cdb_direct+0x64/0xd0 [target_core_mod]
[  716.756988] [c0000001b536fab0] [d00000000b6551f8] target_submit_cmd_map_sgls+0x1a8/0x320 [target_core_mod]
[  716.756998] [c0000001b536fb40] [d00000000b6553b8] target_submit_cmd+0x48/0x60 [target_core_mod]
[  716.757002] [c0000001b536fbe0] [d00000000b824bb0] ibmvscsis_scheduler+0x370/0x600 [ibmvscsis]
[  716.757007] [c0000001b536fca0] [c0000000001200fc] process_one_work+0x1ec/0x580
[  716.757010] [c0000001b536fd30] [c000000000120528] worker_thread+0x98/0x5d0
[  716.757013] [c0000001b536fdc0] [c0000000001292bc] kthread+0x16c/0x1b0
[  716.757017] [c0000001b536fe30] [c00000000000b4e8] ret_from_kernel_thread+0x5c/0x74
[  716.757020] Instruction dump:
[  716.757022] 7c0803a6 4e800020 3c4c009a 3842c508 7c0802a6 f8010010 f821ffa1 7c641b78 
[  716.757027] 3c62ff98 3863e8b8 4b5530dd 60000000 <0fe00000> 00000000 00000000 00000000 
[  716.757033] ---[ end trace 1f1264fedf09f0b7 ]---

It looks like memcmp is throwing the fortify panic due to size of ptrs being incorrectly
determined at compile time. 

-Bryant 

Re: [PATCH 2/8] target: remove iblock WRITE_SAME passthrough support

[Bryant G. Ly]

On 4/12/17 12:30 AM, Nicholas A. Bellinger wrote:

> On Mon, 2017-04-10 at 18:08 +0200, Christoph Hellwig wrote:
>> Use the pscsi driver to support arbitrary command passthrough
>> instead.
>>
> The people who are actively using iblock_execute_write_same_direct() are
> doing so in the context of ESX VAAI BlockZero, together with
> EXTENDED_COPY and COMPARE_AND_WRITE primitives.  Just using PSCSI is not
> an option for them.
>
> In practice though I've not seen any users of IBLOCK WRITE_SAME for
> anything other than VAAI BlockZero, so just using blkdev_issue_zeroout()
> when available, and falling back to iblock_execute_write_same() if the
> WRITE_SAME buffer contains anything other than zeros should be OK.
>
> How about something like the following below..?
>
> This would bring parity to how blkdev_issue_write_same() works atm wrt
> to synchronous bio completions.  However, most folks with a raw
> make_request or blk-mq backend driver that supports multiple GB/sec of
> zero bandwidth end up changing IBLOCK to support asynchronous
> REQ_WRITE_SAME completions anyways.
>
> I'd be happy to add support for that using __blkdev_issue_zeroout() once
> the basic conversion is in place.
>
> From ff74012eaff38f9fa0d74aca60507b9964f484ce Mon Sep 17 00:00:00 2001
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> Date: Tue, 11 Apr 2017 22:21:47 -0700
> Subject: [PATCH] target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout
>
> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
> ---
>  drivers/target/target_core_iblock.c | 44 +++++++++++++++++++++++--------------
>  1 file changed, 27 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
> index d316ed5..5bfde20 100644
> --- a/drivers/target/target_core_iblock.c
> +++ b/drivers/target/target_core_iblock.c
> @@ -86,6 +86,7 @@ static int iblock_configure_device(struct se_device *dev)
>  	struct block_device *bd = NULL;
>  	struct blk_integrity *bi;
>  	fmode_t mode;
> +	unsigned int max_write_zeroes_sectors;
>  	int ret = -ENOMEM;
>
>  	if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
> @@ -129,7 +130,11 @@ static int iblock_configure_device(struct se_device *dev)
>  	 * Enable write same emulation for IBLOCK and use 0xFFFF as
>  	 * the smaller WRITE_SAME(10) only has a two-byte block count.
>  	 */
> -	dev->dev_attrib.max_write_same_len = 0xFFFF;
> +	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);
> +	if (max_write_zeroes_sectors)
> +		dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;
> +	else
> +		dev->dev_attrib.max_write_same_len = 0xFFFF;
>
>  	if (blk_queue_nonrot(q))
>  		dev->dev_attrib.is_nonrot = 1;
> @@ -415,28 +420,31 @@ static void iblock_end_io_flush(struct bio *bio)
>  }
>
>  static sense_reason_t
> -iblock_execute_write_same_direct(struct block_device *bdev, struct se_cmd *cmd)
> +iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd)
>  {
>  	struct se_device *dev = cmd->se_dev;
>  	struct scatterlist *sg = &cmd->t_data_sg[0];
> -	struct page *page = NULL;
> -	int ret;
> +	unsigned char *buf, zero = 0x00, *p = &zero;
> +	int rc, ret;
>
> -	if (sg->offset) {
> -		page = alloc_page(GFP_KERNEL);
> -		if (!page)
> -			return TCM_OUT_OF_RESOURCES;
> -		sg_copy_to_buffer(sg, cmd->t_data_nents, page_address(page),
> -				  dev->dev_attrib.block_size);
> -	}
> +	buf = kmap(sg_page(sg)) + sg->offset;
> +	if (!buf)
> +		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> +	/*
> +	 * Fall back to block_execute_write_same() slow-path if
> +	 * incoming WRITE_SAME payload does not contain zeros.
> +	 */
> +	rc = memcmp(buf, p, cmd->data_length);
> +	kunmap(sg_page(sg));
> +

I recently pulled in this patch and I am getting:

[  716.756756] ------------[ cut here ]------------
[  716.756757] kernel BUG at /build/linux-hwe-edge-F6_Smd/linux-hwe-edge-4.13.0/lib/string.c:985!
[  716.756762] Oops: Exception in kernel mode, sig: 5 [#1]
[  716.756764] SMP NR_CPUS 48 
[  716.756765] NUMA 
[  716.756767] pSeries
[  716.756769] Modules linked in: hvcs(OE) hvcserver dm_snapshot dm_bufio ip6table_raw xt_CT xt_mac xt_tcpudp xt_comment xt_physdev xt_set ip_set_hash_net ip_set rpadlpar_io rpaphp iptable_raw target_core_pscsi(OE) target_core_file(OE) target_core_iblock(OE) iscsi_target_mod(OE) dccp_diag dccp tcp_diag udp_diag inet_diag unix_diag af_packet_diag netlink_diag vport_vxlan vxlan ip6_udp_tunnel udp_tunnel openvswitch nf_nat_ipv6 target_core_user(OE) uio binfmt_misc ibmvmc(OE) pseries_rng vmx_crypto crct10dif_vpmsum xt_conntrack nf_nat_ftp nf_conntrack_ftp nf_conntrack_netlink nfnetlink nf_conntrack_netbios_ns nf_conntrack_broadcast nf_conntrack_ipv6 nf_defrag_ipv6 nbd ipt_REJECT nf_reject_ipv4 ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack
[  716.756825]  iptable_mangle iptable_filter ip_tables ip6table_filter ip6_tables ebtables x_tables br_netfilter bridge stp llc ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq raid1 raid0 multipath linear mlx4_en dm_round_robin ses enclosure scsi_transport_sas ibmvscsis(OE) target_core_mod(OE) ibmveth(OE) mlx5_core mlx4_core bnx2x mdio libcrc32c crc32c_vpmsum mlxfw ipr devlink tg3 scsi_dh_emc scsi_dh_rdac scsi_dh_alua dm_multipath
[  716.756872] CPU: 1 PID: 3685 Comm: kworker/1:2 Tainted: G           OE   4.13.0-16-generic #19~16.04.3-Ubuntu
[  716.756880] Workqueue: ibmvscsis30000008 ibmvscsis_scheduler [ibmvscsis]
[  716.756883] task: c0000001ee076a00 task.stack: c0000001b536c000
[  716.756885] NIP: c000000000c26620 LR: c000000000c2661c CTR: 0000000000655170
[  716.756888] REGS: c0000001b536f590 TRAP: 0700   Tainted: G           OE    (4.13.0-16-generic)
[  716.756891] MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>
[  716.756896]   CR: 28482222  XER: 20000003
[  716.756899] CFAR: c000000000179740 SOFTE: 1 
               GPR00: c000000000c2661c c0000001b536f810 c0000000015c2b00 0000000000000022 
               GPR04: c0000001f704ade8 c0000001f7062068 0000000000000003 ffffffffffffffff 
               GPR08: 0000000000000007 c0000000010d1a74 00000001f5f80000 0000000000000066 
               GPR12: 0000000000002200 c00000000fac0a80 c000000000129158 c0000001f2b5bb00 
               GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
               GPR20: 0000000000000000 0000000000000000 0000000000000000 fffffffffffffef7 
               GPR24: 0000000000000000 f0000000007a82c0 00000000000003f0 0000000000648010 
               GPR28: c00000004394fbd0 c0000001f36c2780 c0000001ddb0e700 c0000001e391a000 
[  716.756932] NIP [c000000000c26620] fortify_panic+0x28/0x38
[  716.756935] LR [c000000000c2661c] fortify_panic+0x24/0x38
[  716.756937] Call Trace:
[  716.756939] [c0000001b536f810] [c000000000c2661c] fortify_panic+0x24/0x38 (unreliable)
[  716.756944] [c0000001b536f870] [d000000013c30bf8] iblock_execute_write_same+0x3b8/0x3c0 [target_core_iblock]
[  716.756955] [c0000001b536f920] [d00000000b6537b4] __target_execute_cmd+0x54/0x150 [target_core_mod]
[  716.756960] [c0000001b536f950] [d00000000b822c90] ibmvscsis_write_pending+0x70/0xc0 [ibmvscsis]
[  716.756969] [c0000001b536f9c0] [d00000000b654f28] transport_generic_new_cmd+0x318/0x370 [target_core_mod]
[  716.756979] [c0000001b536fa40] [d00000000b654fe4] transport_handle_cdb_direct+0x64/0xd0 [target_core_mod]
[  716.756988] [c0000001b536fab0] [d00000000b6551f8] target_submit_cmd_map_sgls+0x1a8/0x320 [target_core_mod]
[  716.756998] [c0000001b536fb40] [d00000000b6553b8] target_submit_cmd+0x48/0x60 [target_core_mod]
[  716.757002] [c0000001b536fbe0] [d00000000b824bb0] ibmvscsis_scheduler+0x370/0x600 [ibmvscsis]
[  716.757007] [c0000001b536fca0] [c0000000001200fc] process_one_work+0x1ec/0x580
[  716.757010] [c0000001b536fd30] [c000000000120528] worker_thread+0x98/0x5d0
[  716.757013] [c0000001b536fdc0] [c0000000001292bc] kthread+0x16c/0x1b0
[  716.757017] [c0000001b536fe30] [c00000000000b4e8] ret_from_kernel_thread+0x5c/0x74
[  716.757020] Instruction dump:
[  716.757022] 7c0803a6 4e800020 3c4c009a 3842c508 7c0802a6 f8010010 f821ffa1 7c641b78 
[  716.757027] 3c62ff98 3863e8b8 4b5530dd 60000000 <0fe00000> 00000000 00000000 00000000 
[  716.757033] ---[ end trace 1f1264fedf09f0b7 ]---

It looks like memcmp is throwing the fortify panic due to size of ptrs being incorrectly
determined at compile time. 

-Bryant 

[PATCH 3/8] sd: remove write same support

[Christoph Hellwig]

There are no more end-users of REQ_OP_WRITE_SAME left, so we can start
deleting it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/scsi/sd.c     | 70 ---------------------------------------------------
 drivers/scsi/sd_zbc.c |  1 -
 2 files changed, 71 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 8cf34a8e3eea..a905802e927e 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -878,77 +878,10 @@ static void sd_config_write_same(struct scsi_disk *sdkp)
 		sdkp->zeroing_mode = SD_ZERO_WRITE;
 
 out:
-	blk_queue_max_write_same_sectors(q, sdkp->max_ws_blocks *
-					 (logical_block_size >> 9));
 	blk_queue_max_write_zeroes_sectors(q, sdkp->max_ws_blocks *
 					 (logical_block_size >> 9));
 }
 
-/**
- * sd_setup_write_same_cmnd - write the same data to multiple blocks
- * @cmd: command to prepare
- *
- * Will issue either WRITE SAME(10) or WRITE SAME(16) depending on
- * preference indicated by target device.
- **/
-static int sd_setup_write_same_cmnd(struct scsi_cmnd *cmd)
-{
-	struct request *rq = cmd->request;
-	struct scsi_device *sdp = cmd->device;
-	struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
-	struct bio *bio = rq->bio;
-	sector_t sector = blk_rq_pos(rq);
-	unsigned int nr_sectors = blk_rq_sectors(rq);
-	unsigned int nr_bytes = blk_rq_bytes(rq);
-	int ret;
-
-	if (sdkp->device->no_write_same)
-		return BLKPREP_INVALID;
-
-	BUG_ON(bio_offset(bio) || bio_iovec(bio).bv_len != sdp->sector_size);
-
-	if (sd_is_zoned(sdkp)) {
-		ret = sd_zbc_setup_write_cmnd(cmd);
-		if (ret != BLKPREP_OK)
-			return ret;
-	}
-
-	sector >>= ilog2(sdp->sector_size) - 9;
-	nr_sectors >>= ilog2(sdp->sector_size) - 9;
-
-	rq->timeout = SD_WRITE_SAME_TIMEOUT;
-
-	if (sdkp->ws16 || sector > 0xffffffff || nr_sectors > 0xffff) {
-		cmd->cmd_len = 16;
-		cmd->cmnd[0] = WRITE_SAME_16;
-		put_unaligned_be64(sector, &cmd->cmnd[2]);
-		put_unaligned_be32(nr_sectors, &cmd->cmnd[10]);
-	} else {
-		cmd->cmd_len = 10;
-		cmd->cmnd[0] = WRITE_SAME;
-		put_unaligned_be32(sector, &cmd->cmnd[2]);
-		put_unaligned_be16(nr_sectors, &cmd->cmnd[7]);
-	}
-
-	cmd->transfersize = sdp->sector_size;
-	cmd->allowed = SD_MAX_RETRIES;
-
-	/*
-	 * For WRITE SAME the data transferred via the DATA OUT buffer is
-	 * different from the amount of data actually written to the target.
-	 *
-	 * We set up __data_len to the amount of data transferred via the
-	 * DATA OUT buffer so that blk_rq_map_sg sets up the proper S/G list
-	 * to transfer a single sector of data first, but then reset it to
-	 * the amount of data to be written right after so that the I/O path
-	 * knows how much to actually write.
-	 */
-	rq->__data_len = sdp->sector_size;
-	ret = scsi_init_io(cmd);
-	rq->__data_len = nr_bytes;
-	return ret;
-}
-
 static int sd_setup_flush_cmnd(struct scsi_cmnd *cmd)
 {
 	struct request *rq = cmd->request;
@@ -1232,8 +1165,6 @@ static int sd_init_command(struct scsi_cmnd *cmd)
 		}
 	case REQ_OP_WRITE_ZEROES:
 		return sd_setup_write_zeroes_cmnd(cmd);
-	case REQ_OP_WRITE_SAME:
-		return sd_setup_write_same_cmnd(cmd);
 	case REQ_OP_FLUSH:
 		return sd_setup_flush_cmnd(cmd);
 	case REQ_OP_READ:
@@ -1872,7 +1803,6 @@ static int sd_done(struct scsi_cmnd *SCpnt)
 	switch (req_op(req)) {
 	case REQ_OP_DISCARD:
 	case REQ_OP_WRITE_ZEROES:
-	case REQ_OP_WRITE_SAME:
 	case REQ_OP_ZONE_RESET:
 		if (!result) {
 			good_bytes = blk_rq_bytes(req);
diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
index 1994f7799fce..8af6c9cd30ca 100644
--- a/drivers/scsi/sd_zbc.c
+++ b/drivers/scsi/sd_zbc.c
@@ -330,7 +330,6 @@ void sd_zbc_complete(struct scsi_cmnd *cmd,
 	switch (req_op(rq)) {
 	case REQ_OP_WRITE:
 	case REQ_OP_WRITE_ZEROES:
-	case REQ_OP_WRITE_SAME:
 	case REQ_OP_ZONE_RESET:
 
 		/* Unlock the zone */
-- 
2.11.0

[PATCH 4/8] md: drop WRITE_SAME support

[Christoph Hellwig]

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/md/linear.c    | 1 -
 drivers/md/md.h        | 7 -------
 drivers/md/multipath.c | 1 -
 drivers/md/raid0.c     | 2 --
 drivers/md/raid1.c     | 4 +---
 drivers/md/raid10.c    | 1 -
 drivers/md/raid5.c     | 1 -
 7 files changed, 1 insertion(+), 16 deletions(-)

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 377a8a3672e3..da363f5d54b0 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -292,7 +292,6 @@ static void linear_make_request(struct mddev *mddev, struct bio *bio)
 				trace_block_bio_remap(bdev_get_queue(split->bi_bdev),
 						      split, disk_devt(mddev->gendisk),
 						      bio_sector);
-			mddev_check_writesame(mddev, split);
 			mddev_check_write_zeroes(mddev, split);
 			generic_make_request(split);
 		}
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 1e76d64ce180..d82b11b5ae5a 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -703,13 +703,6 @@ static inline void mddev_clear_unsupported_flags(struct mddev *mddev,
 	mddev->flags &= ~unsupported_flags;
 }
 
-static inline void mddev_check_writesame(struct mddev *mddev, struct bio *bio)
-{
-	if (bio_op(bio) == REQ_OP_WRITE_SAME &&
-	    !bdev_get_queue(bio->bi_bdev)->limits.max_write_same_sectors)
-		mddev->queue->limits.max_write_same_sectors = 0;
-}
-
 static inline void mddev_check_write_zeroes(struct mddev *mddev, struct bio *bio)
 {
 	if (bio_op(bio) == REQ_OP_WRITE_ZEROES &&
diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index e95d521d93e9..68d67a404aab 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -138,7 +138,6 @@ static void multipath_make_request(struct mddev *mddev, struct bio * bio)
 	mp_bh->bio.bi_opf |= REQ_FAILFAST_TRANSPORT;
 	mp_bh->bio.bi_end_io = multipath_end_request;
 	mp_bh->bio.bi_private = mp_bh;
-	mddev_check_writesame(mddev, &mp_bh->bio);
 	mddev_check_write_zeroes(mddev, &mp_bh->bio);
 	generic_make_request(&mp_bh->bio);
 	return;
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index ce7a6a56cf73..c094749c11e5 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -382,7 +382,6 @@ static int raid0_run(struct mddev *mddev)
 		bool discard_supported = false;
 
 		blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
-		blk_queue_max_write_same_sectors(mddev->queue, mddev->chunk_sectors);
 		blk_queue_max_write_zeroes_sectors(mddev->queue, mddev->chunk_sectors);
 		blk_queue_max_discard_sectors(mddev->queue, mddev->chunk_sectors);
 
@@ -504,7 +503,6 @@ static void raid0_make_request(struct mddev *mddev, struct bio *bio)
 				trace_block_bio_remap(bdev_get_queue(split->bi_bdev),
 						      split, disk_devt(mddev->gendisk),
 						      bio_sector);
-			mddev_check_writesame(mddev, split);
 			mddev_check_write_zeroes(mddev, split);
 			generic_make_request(split);
 		}
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index b59cc100320a..ac9ef686e625 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -3177,10 +3177,8 @@ static int raid1_run(struct mddev *mddev)
 	if (IS_ERR(conf))
 		return PTR_ERR(conf);
 
-	if (mddev->queue) {
-		blk_queue_max_write_same_sectors(mddev->queue, 0);
+	if (mddev->queue)
 		blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
-	}
 
 	rdev_for_each(rdev, mddev) {
 		if (!mddev->gendisk)
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 28ec3a93acee..79988908f862 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3748,7 +3748,6 @@ static int raid10_run(struct mddev *mddev)
 	if (mddev->queue) {
 		blk_queue_max_discard_sectors(mddev->queue,
 					      mddev->chunk_sectors);
-		blk_queue_max_write_same_sectors(mddev->queue, 0);
 		blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
 		blk_queue_io_min(mddev->queue, chunk_size);
 		if (conf->geo.raid_disks % conf->geo.near_copies)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 2efdb0d67460..04fd6a946825 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7262,7 +7262,6 @@ static int raid5_run(struct mddev *mddev)
 		blk_queue_max_discard_sectors(mddev->queue,
 					      0xfffe * STRIPE_SECTORS);
 
-		blk_queue_max_write_same_sectors(mddev->queue, 0);
 		blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
 
 		rdev_for_each(rdev, mddev) {
-- 
2.11.0

[PATCH 5/8] dm: remove write same support

[Christoph Hellwig]

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/md/dm-core.h          |  1 -
 drivers/md/dm-io.c            | 21 +--------------------
 drivers/md/dm-linear.c        |  1 -
 drivers/md/dm-mpath.c         |  1 -
 drivers/md/dm-rq.c            |  3 ---
 drivers/md/dm-stripe.c        |  4 +---
 drivers/md/dm-table.c         | 29 -----------------------------
 drivers/md/dm.c               | 23 -----------------------
 include/linux/device-mapper.h |  6 ------
 9 files changed, 2 insertions(+), 87 deletions(-)

diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index fea5bd52ada8..d661801d72e7 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -131,7 +131,6 @@ struct mapped_device {
 void dm_init_md_queue(struct mapped_device *md);
 void dm_init_normal_md_queue(struct mapped_device *md);
 int md_in_flight(struct mapped_device *md);
-void disable_write_same(struct mapped_device *md);
 void disable_write_zeroes(struct mapped_device *md);
 
 static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 3702e502466d..105e68dabd3e 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -303,7 +303,6 @@ static void do_region(int op, int op_flags, unsigned region,
 	unsigned num_bvecs;
 	sector_t remaining = where->count;
 	struct request_queue *q = bdev_get_queue(where->bdev);
-	unsigned short logical_block_size = queue_logical_block_size(q);
 	sector_t num_sectors;
 	unsigned int uninitialized_var(special_cmd_max_sectors);
 
@@ -314,10 +313,7 @@ static void do_region(int op, int op_flags, unsigned region,
 		special_cmd_max_sectors = q->limits.max_discard_sectors;
 	else if (op == REQ_OP_WRITE_ZEROES)
 		special_cmd_max_sectors = q->limits.max_write_zeroes_sectors;
-	else if (op == REQ_OP_WRITE_SAME)
-		special_cmd_max_sectors = q->limits.max_write_same_sectors;
-	if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES ||
-	     op == REQ_OP_WRITE_SAME)  &&
+	if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) &&
 	    special_cmd_max_sectors == 0) {
 		dec_count(io, region, -EOPNOTSUPP);
 		return;
@@ -336,9 +332,6 @@ static void do_region(int op, int op_flags, unsigned region,
 		case REQ_OP_WRITE_ZEROES:
 			num_bvecs = 0;
 			break;
-		case REQ_OP_WRITE_SAME:
-			num_bvecs = 1;
-			break;
 		default:
 			num_bvecs = min_t(int, BIO_MAX_PAGES,
 					  dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT)));
@@ -355,18 +348,6 @@ static void do_region(int op, int op_flags, unsigned region,
 			num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
 			bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
 			remaining -= num_sectors;
-		} else if (op == REQ_OP_WRITE_SAME) {
-			/*
-			 * WRITE SAME only uses a single page.
-			 */
-			dp->get_page(dp, &page, &len, &offset);
-			bio_add_page(bio, page, logical_block_size, offset);
-			num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
-			bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
-
-			offset = 0;
-			remaining -= num_sectors;
-			dp->next_page(dp);
 		} else while (remaining) {
 			/*
 			 * Try and add as many pages as possible.
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index e17fd44ceef5..f928f7e9ee4a 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -58,7 +58,6 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 	ti->num_flush_bios = 1;
 	ti->num_discard_bios = 1;
-	ti->num_write_same_bios = 1;
 	ti->num_write_zeroes_bios = 1;
 	ti->private = lc;
 	return 0;
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index ab55955ed704..ece53947b99d 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1102,7 +1102,6 @@ static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
 
 	ti->num_flush_bios = 1;
 	ti->num_discard_bios = 1;
-	ti->num_write_same_bios = 1;
 	ti->num_write_zeroes_bios = 1;
 	if (m->queue_mode == DM_TYPE_BIO_BASED)
 		ti->per_io_data_size = multipath_per_bio_data_size();
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index e60f1b6845be..6f8dc99685f2 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -299,9 +299,6 @@ static void dm_done(struct request *clone, int error, bool mapped)
 	}
 
 	if (unlikely(r == -EREMOTEIO)) {
-		if (req_op(clone) == REQ_OP_WRITE_SAME &&
-		    !clone->q->limits.max_write_same_sectors)
-			disable_write_same(tio->md);
 		if (req_op(clone) == REQ_OP_WRITE_ZEROES &&
 		    !clone->q->limits.max_write_zeroes_sectors)
 			disable_write_zeroes(tio->md);
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 5ef49c121d99..cc5a00f2e2de 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -168,7 +168,6 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 	ti->num_flush_bios = stripes;
 	ti->num_discard_bios = stripes;
-	ti->num_write_same_bios = stripes;
 	ti->num_write_zeroes_bios = stripes;
 
 	sc->chunk_size = chunk_size;
@@ -294,8 +293,7 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
 		return DM_MAPIO_REMAPPED;
 	}
 	if (unlikely(bio_op(bio) == REQ_OP_DISCARD) ||
-	    unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES) ||
-	    unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) {
+	    unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES)) {
 		target_bio_nr = dm_bio_get_target_bio_nr(bio);
 		BUG_ON(target_bio_nr >= sc->stripes);
 		return stripe_map_range(sc, bio, target_bio_nr);
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 958275aca008..8bbc3d57fcc7 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1490,33 +1490,6 @@ static bool dm_table_all_devices_attribute(struct dm_table *t,
 	return true;
 }
 
-static int device_not_write_same_capable(struct dm_target *ti, struct dm_dev *dev,
-					 sector_t start, sector_t len, void *data)
-{
-	struct request_queue *q = bdev_get_queue(dev->bdev);
-
-	return q && !q->limits.max_write_same_sectors;
-}
-
-static bool dm_table_supports_write_same(struct dm_table *t)
-{
-	struct dm_target *ti;
-	unsigned i = 0;
-
-	while (i < dm_table_get_num_targets(t)) {
-		ti = dm_table_get_target(t, i++);
-
-		if (!ti->num_write_same_bios)
-			return false;
-
-		if (!ti->type->iterate_devices ||
-		    ti->type->iterate_devices(ti, device_not_write_same_capable, NULL))
-			return false;
-	}
-
-	return true;
-}
-
 static int device_not_write_zeroes_capable(struct dm_target *ti, struct dm_dev *dev,
 					   sector_t start, sector_t len, void *data)
 {
@@ -1610,8 +1583,6 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	else
 		queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, q);
 
-	if (!dm_table_supports_write_same(t))
-		q->limits.max_write_same_sectors = 0;
 	if (!dm_table_supports_write_zeroes(t))
 		q->limits.max_write_zeroes_sectors = 0;
 
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 8bf397729bbd..8259aa76839e 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -816,14 +816,6 @@ static void dec_pending(struct dm_io *io, int error)
 	}
 }
 
-void disable_write_same(struct mapped_device *md)
-{
-	struct queue_limits *limits = dm_get_queue_limits(md);
-
-	/* device doesn't really support WRITE SAME, disable it */
-	limits->max_write_same_sectors = 0;
-}
-
 void disable_write_zeroes(struct mapped_device *md)
 {
 	struct queue_limits *limits = dm_get_queue_limits(md);
@@ -859,9 +851,6 @@ static void clone_endio(struct bio *bio)
 	}
 
 	if (unlikely(r == -EREMOTEIO)) {
-		if (bio_op(bio) == REQ_OP_WRITE_SAME &&
-		    !bdev_get_queue(bio->bi_bdev)->limits.max_write_same_sectors)
-			disable_write_same(md);
 		if (bio_op(bio) == REQ_OP_WRITE_ZEROES &&
 		    !bdev_get_queue(bio->bi_bdev)->limits.max_write_zeroes_sectors)
 			disable_write_zeroes(md);
@@ -1209,11 +1198,6 @@ static unsigned get_num_discard_bios(struct dm_target *ti)
 	return ti->num_discard_bios;
 }
 
-static unsigned get_num_write_same_bios(struct dm_target *ti)
-{
-	return ti->num_write_same_bios;
-}
-
 static unsigned get_num_write_zeroes_bios(struct dm_target *ti)
 {
 	return ti->num_write_zeroes_bios;
@@ -1268,11 +1252,6 @@ static int __send_discard(struct clone_info *ci)
 					   is_split_required_for_discard);
 }
 
-static int __send_write_same(struct clone_info *ci)
-{
-	return __send_changing_extent_only(ci, get_num_write_same_bios, NULL);
-}
-
 static int __send_write_zeroes(struct clone_info *ci)
 {
 	return __send_changing_extent_only(ci, get_num_write_zeroes_bios, NULL);
@@ -1290,8 +1269,6 @@ static int __split_and_process_non_flush(struct clone_info *ci)
 
 	if (unlikely(bio_op(bio) == REQ_OP_DISCARD))
 		return __send_discard(ci);
-	else if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
-		return __send_write_same(ci);
 	else if (unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES))
 		return __send_write_zeroes(ci);
 
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index c7ea33e38fb9..58f451ba9b75 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -249,12 +249,6 @@ struct dm_target {
 	unsigned num_discard_bios;
 
 	/*
-	 * The number of WRITE SAME bios that will be submitted to the target.
-	 * The bio number can be accessed with dm_bio_get_target_bio_nr.
-	 */
-	unsigned num_write_same_bios;
-
-	/*
 	 * The number of WRITE ZEROES bios that will be submitted to the target.
 	 * The bio number can be accessed with dm_bio_get_target_bio_nr.
 	 */
-- 
2.11.0

[PATCH 6/8] block: remove REQ_OP_WRITE_SAME support

[Christoph Hellwig]

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/bio.c                 |  3 --
 block/blk-core.c            | 11 +-----
 block/blk-lib.c             | 90 ---------------------------------------------
 block/blk-merge.c           | 32 ----------------
 block/blk-settings.c        | 16 --------
 block/blk-sysfs.c           | 12 ------
 include/linux/bio.h         |  3 --
 include/linux/blk_types.h   |  4 +-
 include/linux/blkdev.h      | 26 -------------
 include/trace/events/f2fs.h |  1 -
 kernel/trace/blktrace.c     |  1 -
 11 files changed, 2 insertions(+), 197 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index f4d207180266..b310e7ef3fbf 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -684,9 +684,6 @@ static struct bio *__bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
 	case REQ_OP_SECURE_ERASE:
 	case REQ_OP_WRITE_ZEROES:
 		break;
-	case REQ_OP_WRITE_SAME:
-		bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
-		break;
 	default:
 		__bio_for_each_segment(bv, bio_src, iter, iter_src)
 			bio->bi_io_vec[bio->bi_vcnt++] = bv;
diff --git a/block/blk-core.c b/block/blk-core.c
index 8654aa0cef6d..92336bc8495c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1929,10 +1929,6 @@ generic_make_request_checks(struct bio *bio)
 		if (!blk_queue_secure_erase(q))
 			goto not_supported;
 		break;
-	case REQ_OP_WRITE_SAME:
-		if (!bdev_write_same(bio->bi_bdev))
-			goto not_supported;
-		break;
 	case REQ_OP_ZONE_REPORT:
 	case REQ_OP_ZONE_RESET:
 		if (!bdev_is_zoned(bio->bi_bdev))
@@ -2100,12 +2096,7 @@ blk_qc_t submit_bio(struct bio *bio)
 	 * go through the normal accounting stuff before submission.
 	 */
 	if (bio_has_data(bio)) {
-		unsigned int count;
-
-		if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
-			count = bdev_logical_block_size(bio->bi_bdev) >> 9;
-		else
-			count = bio_sectors(bio);
+		unsigned int count = bio_sectors(bio);
 
 		if (op_is_write(bio_op(bio))) {
 			count_vm_events(PGPGOUT, count);
diff --git a/block/blk-lib.c b/block/blk-lib.c
index e8caecd71688..57c99b9b3b78 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -131,96 +131,6 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 }
 EXPORT_SYMBOL(blkdev_issue_discard);
 
-/**
- * __blkdev_issue_write_same - generate number of bios with same page
- * @bdev:	target blockdev
- * @sector:	start sector
- * @nr_sects:	number of sectors to write
- * @gfp_mask:	memory allocation flags (for bio_alloc)
- * @page:	page containing data to write
- * @biop:	pointer to anchor bio
- *
- * Description:
- *  Generate and issue number of bios(REQ_OP_WRITE_SAME) with same page.
- */
-static int __blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
-		sector_t nr_sects, gfp_t gfp_mask, struct page *page,
-		struct bio **biop)
-{
-	struct request_queue *q = bdev_get_queue(bdev);
-	unsigned int max_write_same_sectors;
-	struct bio *bio = *biop;
-	sector_t bs_mask;
-
-	if (!q)
-		return -ENXIO;
-
-	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
-	if ((sector | nr_sects) & bs_mask)
-		return -EINVAL;
-
-	if (!bdev_write_same(bdev))
-		return -EOPNOTSUPP;
-
-	/* Ensure that max_write_same_sectors doesn't overflow bi_size */
-	max_write_same_sectors = UINT_MAX >> 9;
-
-	while (nr_sects) {
-		bio = next_bio(bio, 1, gfp_mask);
-		bio->bi_iter.bi_sector = sector;
-		bio->bi_bdev = bdev;
-		bio->bi_vcnt = 1;
-		bio->bi_io_vec->bv_page = page;
-		bio->bi_io_vec->bv_offset = 0;
-		bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
-		bio_set_op_attrs(bio, REQ_OP_WRITE_SAME, 0);
-
-		if (nr_sects > max_write_same_sectors) {
-			bio->bi_iter.bi_size = max_write_same_sectors << 9;
-			nr_sects -= max_write_same_sectors;
-			sector += max_write_same_sectors;
-		} else {
-			bio->bi_iter.bi_size = nr_sects << 9;
-			nr_sects = 0;
-		}
-		cond_resched();
-	}
-
-	*biop = bio;
-	return 0;
-}
-
-/**
- * blkdev_issue_write_same - queue a write same operation
- * @bdev:	target blockdev
- * @sector:	start sector
- * @nr_sects:	number of sectors to write
- * @gfp_mask:	memory allocation flags (for bio_alloc)
- * @page:	page containing data
- *
- * Description:
- *    Issue a write same request for the sectors in question.
- */
-int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
-				sector_t nr_sects, gfp_t gfp_mask,
-				struct page *page)
-{
-	struct bio *bio = NULL;
-	struct blk_plug plug;
-	int ret;
-
-	blk_start_plug(&plug);
-	ret = __blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask, page,
-			&bio);
-	if (ret == 0 && bio) {
-		ret = submit_bio_wait(bio);
-		bio_put(bio);
-	}
-	blk_finish_plug(&plug);
-	return ret;
-}
-EXPORT_SYMBOL(blkdev_issue_write_same);
-
 static int __blkdev_issue_write_zeroes(struct block_device *bdev,
 		sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
 		struct bio **biop, unsigned flags)
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 3990ae406341..d6c86bfc5722 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -68,22 +68,6 @@ static struct bio *blk_bio_write_zeroes_split(struct request_queue *q,
 	return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs);
 }
 
-static struct bio *blk_bio_write_same_split(struct request_queue *q,
-					    struct bio *bio,
-					    struct bio_set *bs,
-					    unsigned *nsegs)
-{
-	*nsegs = 1;
-
-	if (!q->limits.max_write_same_sectors)
-		return NULL;
-
-	if (bio_sectors(bio) <= q->limits.max_write_same_sectors)
-		return NULL;
-
-	return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs);
-}
-
 static inline unsigned get_max_io_size(struct request_queue *q,
 				       struct bio *bio)
 {
@@ -216,9 +200,6 @@ void blk_queue_split(struct request_queue *q, struct bio **bio,
 	case REQ_OP_WRITE_ZEROES:
 		split = blk_bio_write_zeroes_split(q, *bio, bs, &nsegs);
 		break;
-	case REQ_OP_WRITE_SAME:
-		split = blk_bio_write_same_split(q, *bio, bs, &nsegs);
-		break;
 	default:
 		split = blk_bio_segment_split(q, *bio, q->bio_split, &nsegs);
 		break;
@@ -259,8 +240,6 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
 	case REQ_OP_SECURE_ERASE:
 	case REQ_OP_WRITE_ZEROES:
 		return 0;
-	case REQ_OP_WRITE_SAME:
-		return 1;
 	}
 
 	fbio = bio;
@@ -454,8 +433,6 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
 
 	if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
 		nsegs = __blk_bvec_map_sg(q, rq->special_vec, sglist, &sg);
-	else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME)
-		nsegs = __blk_bvec_map_sg(q, bio_iovec(rq->bio), sglist, &sg);
 	else if (rq->bio)
 		nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg);
 
@@ -688,10 +665,6 @@ static struct request *attempt_merge(struct request_queue *q,
 	    || req_no_special_merge(next))
 		return NULL;
 
-	if (req_op(req) == REQ_OP_WRITE_SAME &&
-	    !blk_write_same_mergeable(req->bio, next->bio))
-		return NULL;
-
 	/*
 	 * If we are allowed to merge, then append bio list
 	 * from next to rq and release next. merge_requests_fn
@@ -806,11 +779,6 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
 	if (blk_integrity_merge_bio(rq->q, rq, bio) == false)
 		return false;
 
-	/* must be using the same buffer */
-	if (req_op(rq) == REQ_OP_WRITE_SAME &&
-	    !blk_write_same_mergeable(rq->bio, bio))
-		return false;
-
 	return true;
 }
 
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 4fa81ed383ca..aea05adfd6b4 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -96,7 +96,6 @@ void blk_set_default_limits(struct queue_limits *lim)
 	lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
 	lim->max_dev_sectors = 0;
 	lim->chunk_sectors = 0;
-	lim->max_write_same_sectors = 0;
 	lim->max_write_zeroes_sectors = 0;
 	lim->max_discard_sectors = 0;
 	lim->max_hw_discard_sectors = 0;
@@ -132,7 +131,6 @@ void blk_set_stacking_limits(struct queue_limits *lim)
 	lim->max_segment_size = UINT_MAX;
 	lim->max_sectors = UINT_MAX;
 	lim->max_dev_sectors = UINT_MAX;
-	lim->max_write_same_sectors = UINT_MAX;
 	lim->max_write_zeroes_sectors = UINT_MAX;
 }
 EXPORT_SYMBOL(blk_set_stacking_limits);
@@ -291,18 +289,6 @@ void blk_queue_max_discard_sectors(struct request_queue *q,
 EXPORT_SYMBOL(blk_queue_max_discard_sectors);
 
 /**
- * blk_queue_max_write_same_sectors - set max sectors for a single write same
- * @q:  the request queue for the device
- * @max_write_same_sectors: maximum number of sectors to write per command
- **/
-void blk_queue_max_write_same_sectors(struct request_queue *q,
-				      unsigned int max_write_same_sectors)
-{
-	q->limits.max_write_same_sectors = max_write_same_sectors;
-}
-EXPORT_SYMBOL(blk_queue_max_write_same_sectors);
-
-/**
  * blk_queue_max_write_zeroes_sectors - set max sectors for a single
  *                                      write zeroes
  * @q:  the request queue for the device
@@ -557,8 +543,6 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
 	t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
 	t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
 	t->max_dev_sectors = min_not_zero(t->max_dev_sectors, b->max_dev_sectors);
-	t->max_write_same_sectors = min(t->max_write_same_sectors,
-					b->max_write_same_sectors);
 	t->max_write_zeroes_sectors = min(t->max_write_zeroes_sectors,
 					b->max_write_zeroes_sectors);
 	t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index fc20489f0d2b..2ea4aca4ec1c 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -211,12 +211,6 @@ static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *pag
 	return queue_var_show(0, page);
 }
 
-static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
-{
-	return sprintf(page, "%llu\n",
-		(unsigned long long)q->limits.max_write_same_sectors << 9);
-}
-
 static ssize_t queue_write_zeroes_max_show(struct request_queue *q, char *page)
 {
 	return sprintf(page, "%llu\n",
@@ -603,11 +597,6 @@ static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
 	.show = queue_discard_zeroes_data_show,
 };
 
-static struct queue_sysfs_entry queue_write_same_max_entry = {
-	.attr = {.name = "write_same_max_bytes", .mode = S_IRUGO },
-	.show = queue_write_same_max_show,
-};
-
 static struct queue_sysfs_entry queue_write_zeroes_max_entry = {
 	.attr = {.name = "write_zeroes_max_bytes", .mode = S_IRUGO },
 	.show = queue_write_zeroes_max_show,
@@ -705,7 +694,6 @@ static struct attribute *default_attrs[] = {
 	&queue_discard_max_entry.attr,
 	&queue_discard_max_hw_entry.attr,
 	&queue_discard_zeroes_data_entry.attr,
-	&queue_write_same_max_entry.attr,
 	&queue_write_zeroes_max_entry.attr,
 	&queue_nonrot_entry.attr,
 	&queue_zoned_entry.attr,
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 4931756d86d9..96a20afb8575 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -87,7 +87,6 @@ static inline bool bio_no_advance_iter(struct bio *bio)
 {
 	return bio_op(bio) == REQ_OP_DISCARD ||
 	       bio_op(bio) == REQ_OP_SECURE_ERASE ||
-	       bio_op(bio) == REQ_OP_WRITE_SAME ||
 	       bio_op(bio) == REQ_OP_WRITE_ZEROES;
 }
 
@@ -199,8 +198,6 @@ static inline unsigned __bio_segments(struct bio *bio, struct bvec_iter *bvec)
 	case REQ_OP_SECURE_ERASE:
 	case REQ_OP_WRITE_ZEROES:
 		return 0;
-	case REQ_OP_WRITE_SAME:
-		return 1;
 	default:
 		break;
 	}
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 61339bc44400..fc4fc927dcc4 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -171,10 +171,8 @@ enum req_opf {
 	REQ_OP_SECURE_ERASE	= 5,
 	/* seset a zone write pointer */
 	REQ_OP_ZONE_RESET	= 6,
-	/* write the same sector many times */
-	REQ_OP_WRITE_SAME	= 7,
 	/* write the zero filled sector many times */
-	REQ_OP_WRITE_ZEROES	= 9,
+	REQ_OP_WRITE_ZEROES	= 7,
 
 	/* SCSI passthrough using struct scsi_request */
 	REQ_OP_SCSI_IN		= 32,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ec993573e0a8..1f066f246dd7 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -326,7 +326,6 @@ struct queue_limits {
 	unsigned int		io_opt;
 	unsigned int		max_discard_sectors;
 	unsigned int		max_hw_discard_sectors;
-	unsigned int		max_write_same_sectors;
 	unsigned int		max_write_zeroes_sectors;
 	unsigned int		discard_granularity;
 	unsigned int		discard_alignment;
@@ -806,14 +805,6 @@ static inline bool rq_mergeable(struct request *rq)
 	return true;
 }
 
-static inline bool blk_write_same_mergeable(struct bio *a, struct bio *b)
-{
-	if (bio_data(a) == bio_data(b))
-		return true;
-
-	return false;
-}
-
 static inline unsigned int blk_queue_depth(struct request_queue *q)
 {
 	if (q->queue_depth)
@@ -1035,9 +1026,6 @@ static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
 	if (unlikely(op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE))
 		return min(q->limits.max_discard_sectors, UINT_MAX >> 9);
 
-	if (unlikely(op == REQ_OP_WRITE_SAME))
-		return q->limits.max_write_same_sectors;
-
 	if (unlikely(op == REQ_OP_WRITE_ZEROES))
 		return q->limits.max_write_zeroes_sectors;
 
@@ -1157,8 +1145,6 @@ extern void blk_queue_max_discard_segments(struct request_queue *,
 extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);
 extern void blk_queue_max_discard_sectors(struct request_queue *q,
 		unsigned int max_discard_sectors);
-extern void blk_queue_max_write_same_sectors(struct request_queue *q,
-		unsigned int max_write_same_sectors);
 extern void blk_queue_max_write_zeroes_sectors(struct request_queue *q,
 		unsigned int max_write_same_sectors);
 extern void blk_queue_logical_block_size(struct request_queue *, unsigned short);
@@ -1336,8 +1322,6 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
 }
 
 extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);
-extern int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
-		sector_t nr_sects, gfp_t gfp_mask, struct page *page);
 
 #define BLKDEV_DISCARD_SECURE	(1 << 0)	/* issue a secure erase */
 
@@ -1539,16 +1523,6 @@ static inline int bdev_discard_alignment(struct block_device *bdev)
 	return q->limits.discard_alignment;
 }
 
-static inline unsigned int bdev_write_same(struct block_device *bdev)
-{
-	struct request_queue *q = bdev_get_queue(bdev);
-
-	if (q)
-		return q->limits.max_write_same_sectors;
-
-	return 0;
-}
-
 static inline unsigned int bdev_write_zeroes_sectors(struct block_device *bdev)
 {
 	struct request_queue *q = bdev_get_queue(bdev);
diff --git a/include/trace/events/f2fs.h b/include/trace/events/f2fs.h
index c80fcad0a6c9..da1b542ef8d6 100644
--- a/include/trace/events/f2fs.h
+++ b/include/trace/events/f2fs.h
@@ -71,7 +71,6 @@ TRACE_DEFINE_ENUM(CP_DISCARD);
 		{ REQ_OP_ZONE_REPORT,		"ZONE_REPORT" },	\
 		{ REQ_OP_SECURE_ERASE,		"SECURE_ERASE" },	\
 		{ REQ_OP_ZONE_RESET,		"ZONE_RESET" },		\
-		{ REQ_OP_WRITE_SAME,		"WRITE_SAME" },		\
 		{ REQ_OP_WRITE_ZEROES,		"WRITE_ZEROES" })
 
 #define show_bio_op_flags(flags)					\
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index b2058a7f94bd..99060c96a4bd 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1750,7 +1750,6 @@ void blk_fill_rwbs(char *rwbs, unsigned int op, int bytes)
 
 	switch (op & REQ_OP_MASK) {
 	case REQ_OP_WRITE:
-	case REQ_OP_WRITE_SAME:
 		rwbs[i++] = 'W';
 		break;
 	case REQ_OP_DISCARD:
-- 
2.11.0

[PATCH 7/8] block: remove bio_no_advance_iter

[Christoph Hellwig]

Now that we don't have to support the odd Write Same special case
we can simply increment the iter if the bio has data, else just
manipulate bi_size directly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/bio.h | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 96a20afb8575..7a24a1a24967 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -83,13 +83,6 @@ static inline bool bio_has_data(struct bio *bio)
 	return false;
 }
 
-static inline bool bio_no_advance_iter(struct bio *bio)
-{
-	return bio_op(bio) == REQ_OP_DISCARD ||
-	       bio_op(bio) == REQ_OP_SECURE_ERASE ||
-	       bio_op(bio) == REQ_OP_WRITE_ZEROES;
-}
-
 static inline bool bio_mergeable(struct bio *bio)
 {
 	if (bio->bi_opf & REQ_NOMERGE_FLAGS)
@@ -165,10 +158,10 @@ static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
 {
 	iter->bi_sector += bytes >> 9;
 
-	if (bio_no_advance_iter(bio))
-		iter->bi_size -= bytes;
-	else
+	if (bio_has_data(bio))
 		bvec_iter_advance(bio->bi_io_vec, iter, bytes);
+	else
+		iter->bi_size -= bytes;
 }
 
 #define __bio_for_each_segment(bvl, bio, iter, start)			\
-- 
2.11.0

[PATCH 8/8] block: use bio_has_data to check if a bio has bvecs

[Christoph Hellwig]

Now that Write Same is gone and discard bios never have a payload we
can simply use bio_has_data as an indicator that the bio has bvecs
that need to be handled.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/bio.c         |  8 +-------
 block/blk-merge.c   |  9 +--------
 include/linux/bio.h | 21 +++++----------------
 3 files changed, 7 insertions(+), 31 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index b310e7ef3fbf..1c9f04c30ba9 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -679,15 +679,9 @@ static struct bio *__bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
 	bio->bi_iter.bi_sector	= bio_src->bi_iter.bi_sector;
 	bio->bi_iter.bi_size	= bio_src->bi_iter.bi_size;
 
-	switch (bio_op(bio)) {
-	case REQ_OP_DISCARD:
-	case REQ_OP_SECURE_ERASE:
-	case REQ_OP_WRITE_ZEROES:
-		break;
-	default:
+	if (bio_has_data(bio)) {
 		__bio_for_each_segment(bv, bio_src, iter, iter_src)
 			bio->bi_io_vec[bio->bi_vcnt++] = bv;
-		break;
 	}
 
 	if (bio_integrity(bio_src)) {
diff --git a/block/blk-merge.c b/block/blk-merge.c
index d6c86bfc5722..549d060097f1 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -232,16 +232,9 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
 	struct bio *fbio, *bbio;
 	struct bvec_iter iter;
 
-	if (!bio)
+	if (!bio || !bio_has_data(bio))
 		return 0;
 
-	switch (bio_op(bio)) {
-	case REQ_OP_DISCARD:
-	case REQ_OP_SECURE_ERASE:
-	case REQ_OP_WRITE_ZEROES:
-		return 0;
-	}
-
 	fbio = bio;
 	cluster = blk_queue_cluster(q);
 	seg_size = 0;
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 7a24a1a24967..86bf531f97aa 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -178,26 +178,15 @@ static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
 static inline unsigned __bio_segments(struct bio *bio, struct bvec_iter *bvec)
 {
 	unsigned segs = 0;
-	struct bio_vec bv;
-	struct bvec_iter iter;
 
-	/*
-	 * We special case discard/write same/write zeroes, because they
-	 * interpret bi_size differently:
-	 */
+	if (bio_has_data(bio)) {
+		struct bio_vec bv;
+		struct bvec_iter iter;
 
-	switch (bio_op(bio)) {
-	case REQ_OP_DISCARD:
-	case REQ_OP_SECURE_ERASE:
-	case REQ_OP_WRITE_ZEROES:
-		return 0;
-	default:
-		break;
+		__bio_for_each_segment(bv, bio, iter, *bvec)
+			segs++;
 	}
 
-	__bio_for_each_segment(bv, bio, iter, *bvec)
-		segs++;
-
 	return segs;
 }
 
-- 
2.11.0

Re: RFC: remove REQ_OP_WRITE_SAME

[Mike Christie]

On 04/10/2017 11:07 AM, Christoph Hellwig wrote:
> Now that we are using REQ_OP_WRITE_ZEROES for all zeroing needs in the
> kernel there is very little use left for REQ_OP_WRITE_SAME.  We only
> have two callers left, and both just export optional protocol features
> to remote systems: DRBD and the target code.
> 
> Do we have any major users of those?  If not removing it will clean up
> a few warts in the block layer.

I added the iblock write same support because for RBD/ceph we were going
to pass it from rbd down to the OSD. We are using tcmu right now, so we
no longer need iblock support.