Merge tag 'pull-iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull iov_iter updates from Al Viro:
"iov_iter work; most of that is about getting rid of direction
misannotations and (hopefully) preventing more of the same for the
future"

* tag 'pull-iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
use less confusing names for iov_iter direction initializers
iov_iter: saner checks for attempt to copy to/from iterator
[xen] fix "direction" argument of iov_iter_kvec()
[vhost] fix 'direction' argument of iov_iter_{init,bvec}()
[target] fix iov_iter_bvec() "direction" argument
[s390] memcpy_real(): WRITE is "data source", not destination...
[s390] zcore: WRITE is "data source", not destination...
[infiniband] READ is "data destination", not source...
[fsi] WRITE is "data source", not destination...
[s390] copy_oldmem_kernel() - WRITE is "data source", not destination
csum_and_copy_to_iter(): handle ITER_DISCARD
get rid of unlikely() on page_copy_sane() calls

arch/s390/kernel/crash_dump.c

···
 
 	kvec.iov_base = dst;
 	kvec.iov_len = count;
-	iov_iter_kvec(&iter, WRITE, &kvec, 1, count);
+	iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
 	if (copy_oldmem_iter(&iter, src, count) < count)
 		return -EFAULT;
 	return 0;

arch/s390/mm/maccess.c

···
 
 	kvec.iov_base = dest;
 	kvec.iov_len = count;
-	iov_iter_kvec(&iter, WRITE, &kvec, 1, count);
+	iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
 	if (memcpy_real_iter(&iter, src, count) < count)
 		return -EFAULT;
 	return 0;

arch/x86/kernel/cpu/microcode/intel.c

···
 
 	kvec.iov_base = (void *)firmware->data;
 	kvec.iov_len = firmware->size;
-	iov_iter_kvec(&iter, WRITE, &kvec, 1, firmware->size);
+	iov_iter_kvec(&iter, ITER_SOURCE, &kvec, 1, firmware->size);
 	ret = generic_load_microcode(cpu, &iter);
 
 	release_firmware(firmware);

arch/x86/kernel/crash_dump_64.c

···
 	struct kvec kvec = { .iov_base = buf, .iov_len = count };
 	struct iov_iter iter;
 
-	iov_iter_kvec(&iter, READ, &kvec, 1, count);
+	iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
 
 	return read_from_oldmem(&iter, count, ppos,
 				cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));

crypto/testmgr.c

···
 	struct iov_iter input;
 	int err;
 
-	iov_iter_kvec(&input, WRITE, inputs, nr_inputs, src_total_len);
+	iov_iter_kvec(&input, ITER_SOURCE, inputs, nr_inputs, src_total_len);
 	err = build_test_sglist(&tsgls->src, cfg->src_divs, alignmask,
 				cfg->inplace_mode != OUT_OF_PLACE ?
 					max(dst_total_len, src_total_len) :
···
 
 	kv.iov_base = (void *)vec->plaintext;
 	kv.iov_len = vec->psize;
-	iov_iter_kvec(&input, WRITE, &kv, 1, vec->psize);
+	iov_iter_kvec(&input, ITER_SOURCE, &kv, 1, vec->psize);
 	return build_test_sglist(tsgl, cfg->src_divs, alignmask, vec->psize,
 				 &input, divs);
 }

drivers/acpi/pfr_update.c

···
 
 	iov.iov_base = (void __user *)buf;
 	iov.iov_len = len;
-	iov_iter_init(&iter, WRITE, &iov, 1, len);
+	iov_iter_init(&iter, ITER_SOURCE, &iov, 1, len);
 
 	/* map the communication buffer */
 	phy_addr = (phys_addr_t)((buf_info.addr_hi << 32) | buf_info.addr_lo);

drivers/block/drbd/drbd_main.c

···
 
 	/* THINK  if (signal_pending) return ... ? */
 
-	iov_iter_kvec(&msg.msg_iter, WRITE, &iov, 1, size);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &iov, 1, size);
 
 	if (sock == connection->data.socket) {
 		rcu_read_lock();

drivers/block/drbd/drbd_receiver.c

···
 	struct msghdr msg = {
 		.msg_flags = (flags ? flags : MSG_WAITALL | MSG_NOSIGNAL)
 	};
-	iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, size);
+	iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, size);
 	return sock_recvmsg(sock, &msg, msg.msg_flags);
 }
 

drivers/block/loop.c

···
 	struct iov_iter i;
 	ssize_t bw;
 
-	iov_iter_bvec(&i, WRITE, bvec, 1, bvec->bv_len);
+	iov_iter_bvec(&i, ITER_SOURCE, bvec, 1, bvec->bv_len);
 
 	file_start_write(file);
 	bw = vfs_iter_write(file, &i, ppos, 0);
···
 	ssize_t len;
 
 	rq_for_each_segment(bvec, rq, iter) {
-		iov_iter_bvec(&i, READ, &bvec, 1, bvec.bv_len);
+		iov_iter_bvec(&i, ITER_DEST, &bvec, 1, bvec.bv_len);
 		len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
 		if (len < 0)
 			return len;
···
 }
 
 static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
-		     loff_t pos, bool rw)
+		     loff_t pos, int rw)
 {
 	struct iov_iter iter;
 	struct req_iterator rq_iter;
···
 	cmd->iocb.ki_flags = IOCB_DIRECT;
 	cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
 
-	if (rw == WRITE)
+	if (rw == ITER_SOURCE)
 		ret = call_write_iter(file, &cmd->iocb, &iter);
 	else
 		ret = call_read_iter(file, &cmd->iocb, &iter);
···
 		return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);
 	case REQ_OP_WRITE:
 		if (cmd->use_aio)
-			return lo_rw_aio(lo, cmd, pos, WRITE);
+			return lo_rw_aio(lo, cmd, pos, ITER_SOURCE);
 		else
 			return lo_write_simple(lo, rq, pos);
 	case REQ_OP_READ:
 		if (cmd->use_aio)
-			return lo_rw_aio(lo, cmd, pos, READ);
+			return lo_rw_aio(lo, cmd, pos, ITER_DEST);
 		else
 			return lo_read_simple(lo, rq, pos);
 	default:

drivers/block/nbd.c

···
 	u32 nbd_cmd_flags = 0;
 	int sent = nsock->sent, skip = 0;
 
-	iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
+	iov_iter_kvec(&from, ITER_SOURCE, &iov, 1, sizeof(request));
 
 	type = req_to_nbd_cmd_type(req);
 	if (type == U32_MAX)
···
 
 			dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
 				req, bvec.bv_len);
-			iov_iter_bvec(&from, WRITE, &bvec, 1, bvec.bv_len);
+			iov_iter_bvec(&from, ITER_SOURCE, &bvec, 1, bvec.bv_len);
 			if (skip) {
 				if (skip >= iov_iter_count(&from)) {
 					skip -= iov_iter_count(&from);
···
 	int result;
 
 	reply->magic = 0;
-	iov_iter_kvec(&to, READ, &iov, 1, sizeof(*reply));
+	iov_iter_kvec(&to, ITER_DEST, &iov, 1, sizeof(*reply));
 	result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 	if (result < 0) {
 		if (!nbd_disconnected(nbd->config))
···
 		struct iov_iter to;
 
 		rq_for_each_segment(bvec, req, iter) {
-			iov_iter_bvec(&to, READ, &bvec, 1, bvec.bv_len);
+			iov_iter_bvec(&to, ITER_DEST, &bvec, 1, bvec.bv_len);
 			result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 			if (result < 0) {
 				dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
···
 	for (i = 0; i < config->num_connections; i++) {
 		struct nbd_sock *nsock = config->socks[i];
 
-		iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
+		iov_iter_kvec(&from, ITER_SOURCE, &iov, 1, sizeof(request));
 		mutex_lock(&nsock->tx_lock);
 		ret = sock_xmit(nbd, i, 1, &from, 0, NULL);
 		if (ret < 0)

drivers/char/random.c

···
 			return ret;
 	}
 
-	ret = import_single_range(READ, ubuf, len, &iov, &iter);
+	ret = import_single_range(ITER_DEST, ubuf, len, &iov, &iter);
 	if (unlikely(ret))
 		return ret;
 	return get_random_bytes_user(&iter);
···
 			return -EINVAL;
 		if (get_user(len, p++))
 			return -EFAULT;
-		ret = import_single_range(WRITE, p, len, &iov, &iter);
+		ret = import_single_range(ITER_SOURCE, p, len, &iov, &iter);
 		if (unlikely(ret))
 			return ret;
 		ret = write_pool_user(&iter);

drivers/fsi/fsi-sbefifo.c

···
 	}
         ffdc_iov.iov_base = ffdc;
 	ffdc_iov.iov_len = SBEFIFO_MAX_FFDC_SIZE;
-        iov_iter_kvec(&ffdc_iter, WRITE, &ffdc_iov, 1, SBEFIFO_MAX_FFDC_SIZE);
+        iov_iter_kvec(&ffdc_iter, ITER_DEST, &ffdc_iov, 1, SBEFIFO_MAX_FFDC_SIZE);
 	cmd[0] = cpu_to_be32(2);
 	cmd[1] = cpu_to_be32(SBEFIFO_CMD_GET_SBE_FFDC);
 	rc = sbefifo_do_command(sbefifo, cmd, 2, &ffdc_iter);
···
 	rbytes = (*resp_len) * sizeof(__be32);
 	resp_iov.iov_base = response;
 	resp_iov.iov_len = rbytes;
-        iov_iter_kvec(&resp_iter, WRITE, &resp_iov, 1, rbytes);
+        iov_iter_kvec(&resp_iter, ITER_DEST, &resp_iov, 1, rbytes);
 
 	/* Perform the command */
 	rc = mutex_lock_interruptible(&sbefifo->lock);
···
 	/* Prepare iov iterator */
 	resp_iov.iov_base = buf;
 	resp_iov.iov_len = len;
-	iov_iter_init(&resp_iter, WRITE, &resp_iov, 1, len);
+	iov_iter_init(&resp_iter, ITER_DEST, &resp_iov, 1, len);
 
 	/* Perform the command */
 	rc = mutex_lock_interruptible(&sbefifo->lock);

drivers/infiniband/ulp/rtrs/rtrs-clt.c

···
 	refcount_set(&req->ref, 1);
 	req->mp_policy = clt_path->clt->mp_policy;
 
-	iov_iter_kvec(&iter, READ, vec, 1, usr_len);
+	iov_iter_kvec(&iter, ITER_SOURCE, vec, 1, usr_len);
 	len = _copy_from_iter(req->iu->buf, usr_len, &iter);
 	WARN_ON(len != usr_len);
 

drivers/isdn/mISDN/l1oip_core.c

···
 		printk(KERN_DEBUG "%s: socket created and open\n",
 		       __func__);
 	while (!signal_pending(current)) {
-		iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, recvbuf_size);
+		iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, recvbuf_size);
 		recvlen = sock_recvmsg(socket, &msg, 0);
 		if (recvlen > 0) {
 			l1oip_socket_parse(hc, &sin_rx, recvbuf, recvlen);

drivers/misc/vmw_vmci/vmci_queue_pair.c

···
 	if (!qpair || !buf)
 		return VMCI_ERROR_INVALID_ARGS;
 
-	iov_iter_kvec(&from, WRITE, &v, 1, buf_size);
+	iov_iter_kvec(&from, ITER_SOURCE, &v, 1, buf_size);
 
 	qp_lock(qpair);
 
···
 	if (!qpair || !buf)
 		return VMCI_ERROR_INVALID_ARGS;
 
-	iov_iter_kvec(&to, READ, &v, 1, buf_size);
+	iov_iter_kvec(&to, ITER_DEST, &v, 1, buf_size);
 
 	qp_lock(qpair);
 
···
 	if (!qpair || !buf)
 		return VMCI_ERROR_INVALID_ARGS;
 
-	iov_iter_kvec(&to, READ, &v, 1, buf_size);
+	iov_iter_kvec(&to, ITER_DEST, &v, 1, buf_size);
 
 	qp_lock(qpair);
 

drivers/net/ppp/ppp_generic.c

···
 	ret = -EFAULT;
 	iov.iov_base = buf;
 	iov.iov_len = count;
-	iov_iter_init(&to, READ, &iov, 1, count);
+	iov_iter_init(&to, ITER_DEST, &iov, 1, count);
 	if (skb_copy_datagram_iter(skb, 0, &to, skb->len))
 		goto outf;
 	ret = skb->len;

drivers/nvme/host/tcp.c

···
 	if (!iov_iter_count(&req->iter) &&
 	    req->data_sent < req->data_len) {
 		req->curr_bio = req->curr_bio->bi_next;
-		nvme_tcp_init_iter(req, WRITE);
+		nvme_tcp_init_iter(req, ITER_SOURCE);
 	}
 }
 
···
 				nvme_tcp_init_recv_ctx(queue);
 				return -EIO;
 			}
-			nvme_tcp_init_iter(req, READ);
+			nvme_tcp_init_iter(req, ITER_DEST);
 		}
 
 		/* we can read only from what is left in this bio */

drivers/nvme/target/io-cmd-file.c

···
 		if (req->cmd->rw.control & cpu_to_le16(NVME_RW_FUA))
 			ki_flags |= IOCB_DSYNC;
 		call_iter = req->ns->file->f_op->write_iter;
-		rw = WRITE;
+		rw = ITER_SOURCE;
 	} else {
 		call_iter = req->ns->file->f_op->read_iter;
-		rw = READ;
+		rw = ITER_DEST;
 	}
 
 	iov_iter_bvec(&iter, rw, req->f.bvec, nr_segs, count);

drivers/nvme/target/tcp.c

···
 		sg_offset = 0;
 	}
 
-	iov_iter_bvec(&cmd->recv_msg.msg_iter, READ, cmd->iov,
+	iov_iter_bvec(&cmd->recv_msg.msg_iter, ITER_DEST, cmd->iov,
 		      nr_pages, cmd->pdu_len);
 }
 

drivers/s390/char/zcore.c

···
 
 	kvec.iov_base = dst;
 	kvec.iov_len = count;
-	iov_iter_kvec(&iter, WRITE, &kvec, 1, count);
+	iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
 	if (memcpy_hsa_iter(&iter, src, count) < count)
 		return -EIO;
 	return 0;

drivers/scsi/sg.c

···
 	Sg_scatter_hold *rsv_schp = &sfp->reserve;
 	struct request_queue *q = sfp->parentdp->device->request_queue;
 	struct rq_map_data *md, map_data;
-	int rw = hp->dxfer_direction == SG_DXFER_TO_DEV ? WRITE : READ;
+	int rw = hp->dxfer_direction == SG_DXFER_TO_DEV ? ITER_SOURCE : ITER_DEST;
 	struct scsi_cmnd *scmd;
 
 	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,

drivers/target/iscsi/iscsi_target_util.c

···
 		return -1;
 
 	memset(&msg, 0, sizeof(struct msghdr));
-	iov_iter_kvec(&msg.msg_iter, READ, iov, iov_count, data);
+	iov_iter_kvec(&msg.msg_iter, ITER_DEST, iov, iov_count, data);
 
 	while (msg_data_left(&msg)) {
 		rx_loop = sock_recvmsg(conn->sock, &msg, MSG_WAITALL);
···
 
 	memset(&msg, 0, sizeof(struct msghdr));
 
-	iov_iter_kvec(&msg.msg_iter, WRITE, iov, iov_count, data);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, iov, iov_count, data);
 
 	while (msg_data_left(&msg)) {
 		int tx_loop = sock_sendmsg(conn->sock, &msg);

drivers/target/target_core_file.c

···
 		len += sg->length;
 	}
 
-	iov_iter_bvec(&iter, READ, bvec, sgl_nents, len);
+	iov_iter_bvec(&iter, is_write, bvec, sgl_nents, len);
 	if (is_write)
 		ret = vfs_iter_write(fd, &iter, &pos, 0);
 	else
···
 		len += se_dev->dev_attrib.block_size;
 	}
 
-	iov_iter_bvec(&iter, READ, bvec, nolb, len);
+	iov_iter_bvec(&iter, ITER_SOURCE, bvec, nolb, len);
 	ret = vfs_iter_write(fd_dev->fd_file, &iter, &pos, 0);
 
 	kfree(bvec);

drivers/usb/usbip/usbip_common.c

···
 	if (!sock || !buf || !size)
 		return -EINVAL;
 
-	iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, size);
+	iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, size);
 
 	usbip_dbg_xmit("enter\n");
 

drivers/vhost/net.c

···
 	/* Skip header. TODO: support TSO. */
 	size_t len = iov_length(vq->iov, out);
 
-	iov_iter_init(iter, WRITE, vq->iov, out, len);
+	iov_iter_init(iter, ITER_SOURCE, vq->iov, out, len);
 	iov_iter_advance(iter, hdr_size);
 
 	return iov_iter_count(iter);
···
 			msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
 		/* On overrun, truncate and discard */
 		if (unlikely(headcount > UIO_MAXIOV)) {
-			iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
+			iov_iter_init(&msg.msg_iter, ITER_DEST, vq->iov, 1, 1);
 			err = sock->ops->recvmsg(sock, &msg,
 						 1, MSG_DONTWAIT | MSG_TRUNC);
 			pr_debug("Discarded rx packet: len %zd\n", sock_len);
 			continue;
 		}
 		/* We don't need to be notified again. */
-		iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
+		iov_iter_init(&msg.msg_iter, ITER_DEST, vq->iov, in, vhost_len);
 		fixup = msg.msg_iter;
 		if (unlikely((vhost_hlen))) {
 			/* We will supply the header ourselves

drivers/vhost/scsi.c

···
 		memcpy(v_rsp.sense, cmd->tvc_sense_buf,
 		       se_cmd->scsi_sense_length);
 
-		iov_iter_init(&iov_iter, READ, &cmd->tvc_resp_iov,
+		iov_iter_init(&iov_iter, ITER_DEST, &cmd->tvc_resp_iov,
 			      cmd->tvc_in_iovs, sizeof(v_rsp));
 		ret = copy_to_iter(&v_rsp, sizeof(v_rsp), &iov_iter);
 		if (likely(ret == sizeof(v_rsp))) {
···
 	 * point at the start of the outgoing WRITE payload, if
 	 * DMA_TO_DEVICE is set.
 	 */
-	iov_iter_init(&vc->out_iter, WRITE, vq->iov, vc->out, vc->out_size);
+	iov_iter_init(&vc->out_iter, ITER_SOURCE, vq->iov, vc->out, vc->out_size);
 	ret = 0;
 
 done:
···
 			data_direction = DMA_FROM_DEVICE;
 			exp_data_len = vc.in_size - vc.rsp_size;
 
-			iov_iter_init(&in_iter, READ, &vq->iov[vc.out], vc.in,
+			iov_iter_init(&in_iter, ITER_DEST, &vq->iov[vc.out], vc.in,
 				      vc.rsp_size + exp_data_len);
 			iov_iter_advance(&in_iter, vc.rsp_size);
 			data_iter = in_iter;
···
 	memset(&rsp, 0, sizeof(rsp));
 	rsp.response = tmf_resp_code;
 
-	iov_iter_init(&iov_iter, READ, resp_iov, in_iovs, sizeof(rsp));
+	iov_iter_init(&iov_iter, ITER_DEST, resp_iov, in_iovs, sizeof(rsp));
 
 	ret = copy_to_iter(&rsp, sizeof(rsp), &iov_iter);
 	if (likely(ret == sizeof(rsp)))
···
 	memset(&rsp, 0, sizeof(rsp));	/* event_actual = 0 */
 	rsp.response = VIRTIO_SCSI_S_OK;
 
-	iov_iter_init(&iov_iter, READ, &vq->iov[vc->out], vc->in, sizeof(rsp));
+	iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[vc->out], vc->in, sizeof(rsp));
 
 	ret = copy_to_iter(&rsp, sizeof(rsp), &iov_iter);
 	if (likely(ret == sizeof(rsp)))

drivers/vhost/vhost.c

···
 				     VHOST_ACCESS_WO);
 		if (ret < 0)
 			goto out;
-		iov_iter_init(&t, WRITE, vq->iotlb_iov, ret, size);
+		iov_iter_init(&t, ITER_DEST, vq->iotlb_iov, ret, size);
 		ret = copy_to_iter(from, size, &t);
 		if (ret == size)
 			ret = 0;
···
 			       (unsigned long long) size);
 			goto out;
 		}
-		iov_iter_init(&f, READ, vq->iotlb_iov, ret, size);
+		iov_iter_init(&f, ITER_SOURCE, vq->iotlb_iov, ret, size);
 		ret = copy_from_iter(to, size, &f);
 		if (ret == size)
 			ret = 0;
···
 			vq_err(vq, "Translation failure %d in indirect.\n", ret);
 		return ret;
 	}
-	iov_iter_init(&from, READ, vq->indirect, ret, len);
+	iov_iter_init(&from, ITER_SOURCE, vq->indirect, ret, len);
 	count = len / sizeof desc;
 	/* Buffers are chained via a 16 bit next field, so
 	 * we can have at most 2^16 of these. */

drivers/vhost/vringh.c

···
 		else if (ret < 0)
 			return ret;
 
-		iov_iter_bvec(&iter, READ, iov, ret, translated);
+		iov_iter_bvec(&iter, ITER_SOURCE, iov, ret, translated);
 
 		ret = copy_from_iter(dst, translated, &iter);
 		if (ret < 0)
···
 		else if (ret < 0)
 			return ret;
 
-		iov_iter_bvec(&iter, WRITE, iov, ret, translated);
+		iov_iter_bvec(&iter, ITER_DEST, iov, ret, translated);
 
 		ret = copy_to_iter(src, translated, &iter);
 		if (ret < 0)

drivers/vhost/vsock.c

···
 			break;
 		}
 
-		iov_iter_init(&iov_iter, READ, &vq->iov[out], in, iov_len);
+		iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[out], in, iov_len);
 		payload_len = pkt->len - pkt->off;
 
 		/* If the packet is greater than the space available in the
···
 		return NULL;
 
 	len = iov_length(vq->iov, out);
-	iov_iter_init(&iov_iter, WRITE, vq->iov, out, len);
+	iov_iter_init(&iov_iter, ITER_SOURCE, vq->iov, out, len);
 
 	nbytes = copy_from_iter(&pkt->hdr, sizeof(pkt->hdr), &iov_iter);
 	if (nbytes != sizeof(pkt->hdr)) {

drivers/xen/pvcalls-back.c

···
 	if (masked_prod < masked_cons) {
 		vec[0].iov_base = data->in + masked_prod;
 		vec[0].iov_len = wanted;
-		iov_iter_kvec(&msg.msg_iter, WRITE, vec, 1, wanted);
+		iov_iter_kvec(&msg.msg_iter, ITER_DEST, vec, 1, wanted);
 	} else {
 		vec[0].iov_base = data->in + masked_prod;
 		vec[0].iov_len = array_size - masked_prod;
 		vec[1].iov_base = data->in;
 		vec[1].iov_len = wanted - vec[0].iov_len;
-		iov_iter_kvec(&msg.msg_iter, WRITE, vec, 2, wanted);
+		iov_iter_kvec(&msg.msg_iter, ITER_DEST, vec, 2, wanted);
 	}
 
 	atomic_set(&map->read, 0);
···
 	if (pvcalls_mask(prod, array_size) > pvcalls_mask(cons, array_size)) {
 		vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
 		vec[0].iov_len = size;
-		iov_iter_kvec(&msg.msg_iter, READ, vec, 1, size);
+		iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, vec, 1, size);
 	} else {
 		vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
 		vec[0].iov_len = array_size - pvcalls_mask(cons, array_size);
 		vec[1].iov_base = data->out;
 		vec[1].iov_len = size - vec[0].iov_len;
-		iov_iter_kvec(&msg.msg_iter, READ, vec, 2, size);
+		iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, vec, 2, size);
 	}
 
 	atomic_set(&map->write, 0);

fs/9p/vfs_addr.c

···
 	size_t len = subreq->len   - subreq->transferred;
 	int total, err;
 
-	iov_iter_xarray(&to, READ, &rreq->mapping->i_pages, pos, len);
+	iov_iter_xarray(&to, ITER_DEST, &rreq->mapping->i_pages, pos, len);
 
 	total = p9_client_read(fid, pos, &to, &err);
 
···
 
 	len = min_t(loff_t, i_size - start, len);
 
-	iov_iter_xarray(&from, WRITE, &folio_mapping(folio)->i_pages, start, len);
+	iov_iter_xarray(&from, ITER_SOURCE, &folio_mapping(folio)->i_pages, start, len);
 
 	/* We should have writeback_fid always set */
 	BUG_ON(!v9inode->writeback_fid);

fs/9p/vfs_dir.c

···
 			struct iov_iter to;
 			int n;
 
-			iov_iter_kvec(&to, READ, &kvec, 1, buflen);
+			iov_iter_kvec(&to, ITER_DEST, &kvec, 1, buflen);
 			n = p9_client_read(file->private_data, ctx->pos, &to,
 					   &err);
 			if (err)

fs/9p/xattr.c

···
 	struct iov_iter to;
 	int err;
 
-	iov_iter_kvec(&to, READ, &kvec, 1, buffer_size);
+	iov_iter_kvec(&to, ITER_DEST, &kvec, 1, buffer_size);
 
 	attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
 	if (IS_ERR(attr_fid)) {
···
 	struct iov_iter from;
 	int retval, err;
 
-	iov_iter_kvec(&from, WRITE, &kvec, 1, value_len);
+	iov_iter_kvec(&from, ITER_SOURCE, &kvec, 1, value_len);
 
 	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
 		 name, value_len, flags);

fs/afs/cmservice.c

···
 		if (call->count2 != call->count && call->count2 != 0)
 			return afs_protocol_error(call, afs_eproto_cb_count);
 		call->iter = &call->def_iter;
-		iov_iter_discard(&call->def_iter, READ, call->count2 * 3 * 4);
+		iov_iter_discard(&call->def_iter, ITER_DEST, call->count2 * 3 * 4);
 		call->unmarshall++;
 
 		fallthrough;

fs/afs/dir.c

···
 	req->actual_len = i_size; /* May change */
 	req->len = nr_pages * PAGE_SIZE; /* We can ask for more than there is */
 	req->data_version = dvnode->status.data_version; /* May change */
-	iov_iter_xarray(&req->def_iter, READ, &dvnode->netfs.inode.i_mapping->i_pages,
+	iov_iter_xarray(&req->def_iter, ITER_DEST, &dvnode->netfs.inode.i_mapping->i_pages,
 			0, i_size);
 	req->iter = &req->def_iter;
 

fs/afs/file.c

···
 	fsreq->vnode	= vnode;
 	fsreq->iter	= &fsreq->def_iter;
 
-	iov_iter_xarray(&fsreq->def_iter, READ,
+	iov_iter_xarray(&fsreq->def_iter, ITER_DEST,
 			&fsreq->vnode->netfs.inode.i_mapping->i_pages,
 			fsreq->pos, fsreq->len);
 
···
 	fsreq->len	= folio_size(folio);
 	fsreq->vnode	= vnode;
 	fsreq->iter	= &fsreq->def_iter;
-	iov_iter_xarray(&fsreq->def_iter, READ, &folio->mapping->i_pages,
+	iov_iter_xarray(&fsreq->def_iter, ITER_DEST, &folio->mapping->i_pages,
 			fsreq->pos, fsreq->len);
 
 	ret = afs_fetch_data(fsreq->vnode, fsreq);

fs/afs/internal.h

···
 	call->iov_len = size;
 	call->kvec[0].iov_base = buf;
 	call->kvec[0].iov_len = size;
-	iov_iter_kvec(&call->def_iter, READ, call->kvec, 1, size);
+	iov_iter_kvec(&call->def_iter, ITER_DEST, call->kvec, 1, size);
 }
 
 static inline void afs_extract_to_tmp(struct afs_call *call)
···
 static inline void afs_extract_discard(struct afs_call *call, size_t size)
 {
 	call->iov_len = size;
-	iov_iter_discard(&call->def_iter, READ, size);
+	iov_iter_discard(&call->def_iter, ITER_DEST, size);
 }
 
 static inline void afs_extract_to_buf(struct afs_call *call, size_t size)

fs/afs/rxrpc.c

···
 
 	msg.msg_name		= NULL;
 	msg.msg_namelen		= 0;
-	iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, call->request_size);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, iov, 1, call->request_size);
 	msg.msg_control		= NULL;
 	msg.msg_controllen	= 0;
 	msg.msg_flags		= MSG_WAITALL | (call->write_iter ? MSG_MORE : 0);
···
 					RX_USER_ABORT, ret, "KSD");
 	} else {
 		len = 0;
-		iov_iter_kvec(&msg.msg_iter, READ, NULL, 0, 0);
+		iov_iter_kvec(&msg.msg_iter, ITER_DEST, NULL, 0, 0);
 		rxrpc_kernel_recv_data(call->net->socket, rxcall,
 				       &msg.msg_iter, &len, false,
 				       &call->abort_code, &call->service_id);
···
 	       ) {
 		if (state == AFS_CALL_SV_AWAIT_ACK) {
 			len = 0;
-			iov_iter_kvec(&call->def_iter, READ, NULL, 0, 0);
+			iov_iter_kvec(&call->def_iter, ITER_DEST, NULL, 0, 0);
 			ret = rxrpc_kernel_recv_data(call->net->socket,
 						     call->rxcall, &call->def_iter,
 						     &len, false, &remote_abort,
···
 
 	msg.msg_name		= NULL;
 	msg.msg_namelen		= 0;
-	iov_iter_kvec(&msg.msg_iter, WRITE, NULL, 0, 0);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, NULL, 0, 0);
 	msg.msg_control		= NULL;
 	msg.msg_controllen	= 0;
 	msg.msg_flags		= 0;
···
 	iov[0].iov_len		= len;
 	msg.msg_name		= NULL;
 	msg.msg_namelen		= 0;
-	iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, len);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, iov, 1, len);
 	msg.msg_control		= NULL;
 	msg.msg_controllen	= 0;
 	msg.msg_flags		= 0;

fs/afs/write.c

···
 		 */
 		afs_write_to_cache(vnode, start, len, i_size, caching);
 
-		iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len);
+		iov_iter_xarray(&iter, ITER_SOURCE, &mapping->i_pages, start, len);
 		ret = afs_store_data(vnode, &iter, start, false);
 	} else {
 		_debug("write discard %x @%llx [%llx]", len, start, i_size);
···
 		bv[0].bv_page = &folio->page;
 		bv[0].bv_offset = f;
 		bv[0].bv_len = t - f;
-		iov_iter_bvec(&iter, WRITE, bv, 1, bv[0].bv_len);
+		iov_iter_bvec(&iter, ITER_SOURCE, bv, 1, bv[0].bv_len);
 
 		trace_afs_folio_dirty(vnode, tracepoint_string("launder"), folio);
 		ret = afs_store_data(vnode, &iter, folio_pos(folio) + f, true);

fs/aio.c

···
 	if (unlikely(!file->f_op->read_iter))
 		return -EINVAL;
 
-	ret = aio_setup_rw(READ, iocb, &iovec, vectored, compat, &iter);
+	ret = aio_setup_rw(ITER_DEST, iocb, &iovec, vectored, compat, &iter);
 	if (ret < 0)
 		return ret;
 	ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
···
 	if (unlikely(!file->f_op->write_iter))
 		return -EINVAL;
 
-	ret = aio_setup_rw(WRITE, iocb, &iovec, vectored, compat, &iter);
+	ret = aio_setup_rw(ITER_SOURCE, iocb, &iovec, vectored, compat, &iter);
 	if (ret < 0)
 		return ret;
 	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));

fs/btrfs/ioctl.c

···
 		goto out_acct;
 	}
 
-	ret = import_iovec(READ, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
+	ret = import_iovec(ITER_DEST, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
 			   &iov, &iter);
 	if (ret < 0)
 		goto out_acct;
···
 	if (args.len > args.unencoded_len - args.unencoded_offset)
 		goto out_acct;
 
-	ret = import_iovec(WRITE, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
+	ret = import_iovec(ITER_SOURCE, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
 			   &iov, &iter);
 	if (ret < 0)
 		goto out_acct;

fs/ceph/addr.c

···
 	}
 
 	len = min_t(size_t, iinfo->inline_len - subreq->start, subreq->len);
-	iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages, subreq->start, len);
+	iov_iter_xarray(&iter, ITER_DEST, &rreq->mapping->i_pages, subreq->start, len);
 	err = copy_to_iter(iinfo->inline_data + subreq->start, len, &iter);
 	if (err == 0)
 		err = -EFAULT;
···
 	}
 
 	dout("%s: pos=%llu orig_len=%zu len=%llu\n", __func__, subreq->start, subreq->len, len);
-	iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages, subreq->start, len);
+	iov_iter_xarray(&iter, ITER_DEST, &rreq->mapping->i_pages, subreq->start, len);
 	err = iov_iter_get_pages_alloc2(&iter, &pages, len, &page_off);
 	if (err < 0) {
 		dout("%s: iov_ter_get_pages_alloc returned %d\n", __func__, err);

fs/ceph/file.c

···
 				aio_req->total_len = rc + zlen;
 			}
 
-			iov_iter_bvec(&i, READ, osd_data->bvec_pos.bvecs,
+			iov_iter_bvec(&i, ITER_DEST, osd_data->bvec_pos.bvecs,
 				      osd_data->num_bvecs, len);
 			iov_iter_advance(&i, rc);
 			iov_iter_zero(zlen, &i);
···
 				int zlen = min_t(size_t, len - ret,
 						 size - pos - ret);
 
-				iov_iter_bvec(&i, READ, bvecs, num_pages, len);
+				iov_iter_bvec(&i, ITER_DEST, bvecs, num_pages, len);
 				iov_iter_advance(&i, ret);
 				iov_iter_zero(zlen, &i);
 				ret += zlen;

fs/cifs/connect.c

···
 {
 	struct msghdr smb_msg = {};
 	struct kvec iov = {.iov_base = buf, .iov_len = to_read};
-	iov_iter_kvec(&smb_msg.msg_iter, READ, &iov, 1, to_read);
+	iov_iter_kvec(&smb_msg.msg_iter, ITER_DEST, &iov, 1, to_read);
 
 	return cifs_readv_from_socket(server, &smb_msg);
 }
···
 	 *  and cifs_readv_from_socket sets msg_control and msg_controllen
 	 *  so little to initialize in struct msghdr
 	 */
-	iov_iter_discard(&smb_msg.msg_iter, READ, to_read);
+	iov_iter_discard(&smb_msg.msg_iter, ITER_DEST, to_read);
 
 	return cifs_readv_from_socket(server, &smb_msg);
 }
···
 	struct msghdr smb_msg = {};
 	struct bio_vec bv = {
 		.bv_page = page, .bv_len = to_read, .bv_offset = page_offset};
-	iov_iter_bvec(&smb_msg.msg_iter, READ, &bv, 1, to_read);
+	iov_iter_bvec(&smb_msg.msg_iter, ITER_DEST, &bv, 1, to_read);
 	return cifs_readv_from_socket(server, &smb_msg);
 }
 

fs/cifs/file.c

···
 		ctx->iter = *from;
 		ctx->len = len;
 	} else {
-		rc = setup_aio_ctx_iter(ctx, from, WRITE);
+		rc = setup_aio_ctx_iter(ctx, from, ITER_SOURCE);
 		if (rc) {
 			kref_put(&ctx->refcount, cifs_aio_ctx_release);
 			return rc;
···
 		ctx->iter = *to;
 		ctx->len = len;
 	} else {
-		rc = setup_aio_ctx_iter(ctx, to, READ);
+		rc = setup_aio_ctx_iter(ctx, to, ITER_DEST);
 		if (rc) {
 			kref_put(&ctx->refcount, cifs_aio_ctx_release);
 			return rc;

fs/cifs/fscache.c

···
 	bvec[0].bv_page		= page;
 	bvec[0].bv_offset	= 0;
 	bvec[0].bv_len		= PAGE_SIZE;
-	iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
+	iov_iter_bvec(&iter, ITER_DEST, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
 
 	ret = fscache_begin_read_operation(&cres, cookie);
 	if (ret < 0)
···
 	bvec[0].bv_page		= page;
 	bvec[0].bv_offset	= 0;
 	bvec[0].bv_len		= PAGE_SIZE;
-	iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
+	iov_iter_bvec(&iter, ITER_SOURCE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
 
 	ret = fscache_begin_write_operation(&cres, cookie);
 	if (ret < 0)

fs/cifs/smb2ops.c

···
 			return 0;
 		}
 
-		iov_iter_bvec(&iter, WRITE, bvec, npages, data_len);
+		iov_iter_bvec(&iter, ITER_SOURCE, bvec, npages, data_len);
 	} else if (buf_len >= data_offset + data_len) {
 		/* read response payload is in buf */
 		WARN_ONCE(npages > 0, "read data can be either in buf or in pages");
 		iov.iov_base = buf + data_offset;
 		iov.iov_len = data_len;
-		iov_iter_kvec(&iter, WRITE, &iov, 1, data_len);
+		iov_iter_kvec(&iter, ITER_SOURCE, &iov, 1, data_len);
 	} else {
 		/* read response payload cannot be in both buf and pages */
 		WARN_ONCE(1, "buf can not contain only a part of read data");

fs/cifs/transport.c

···
 			.iov_base = &rfc1002_marker,
 			.iov_len  = 4
 		};
-		iov_iter_kvec(&smb_msg.msg_iter, WRITE, &hiov, 1, 4);
+		iov_iter_kvec(&smb_msg.msg_iter, ITER_SOURCE, &hiov, 1, 4);
 		rc = smb_send_kvec(server, &smb_msg, &sent);
 		if (rc < 0)
 			goto unmask;
···
 			size += iov[i].iov_len;
 		}
 
-		iov_iter_kvec(&smb_msg.msg_iter, WRITE, iov, n_vec, size);
+		iov_iter_kvec(&smb_msg.msg_iter, ITER_SOURCE, iov, n_vec, size);
 
 		rc = smb_send_kvec(server, &smb_msg, &sent);
 		if (rc < 0)
···
 			rqst_page_get_length(&rqst[j], i, &bvec.bv_len,
 					     &bvec.bv_offset);
 
-			iov_iter_bvec(&smb_msg.msg_iter, WRITE,
+			iov_iter_bvec(&smb_msg.msg_iter, ITER_SOURCE,
 				      &bvec, 1, bvec.bv_len);
 			rc = smb_send_kvec(server, &smb_msg, &sent);
 			if (rc < 0)

fs/coredump.c

···
 	if (dump_interrupted())
 		return 0;
 	pos = file->f_pos;
-	iov_iter_bvec(&iter, WRITE, &bvec, 1, PAGE_SIZE);
+	iov_iter_bvec(&iter, ITER_SOURCE, &bvec, 1, PAGE_SIZE);
 	n = __kernel_write_iter(cprm->file, &iter, &pos);
 	if (n != PAGE_SIZE)
 		return 0;

fs/erofs/fscache.c

···
 
 		atomic_inc(&rreq->nr_outstanding);
 
-		iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages,
+		iov_iter_xarray(&iter, ITER_DEST, &rreq->mapping->i_pages,
 				start + done, subreq->len);
 
 		ret = fscache_read(cres, subreq->start, &iter,
···
 		if (IS_ERR(src))
 			return PTR_ERR(src);
 
-		iov_iter_xarray(&iter, READ, &mapping->i_pages, pos, PAGE_SIZE);
+		iov_iter_xarray(&iter, ITER_DEST, &mapping->i_pages, pos, PAGE_SIZE);
 		if (copy_to_iter(src + offset, size, &iter) != size) {
 			erofs_put_metabuf(&buf);
 			return -EFAULT;
···
 
 	if (!(map.m_flags & EROFS_MAP_MAPPED)) {
 		count = len;
-		iov_iter_xarray(&iter, READ, &mapping->i_pages, pos, count);
+		iov_iter_xarray(&iter, ITER_DEST, &mapping->i_pages, pos, count);
 		iov_iter_zero(count, &iter);
 		return count;
 	}

fs/fscache/io.c

···
 	 * taken into account.
 	 */
 
-	iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len);
+	iov_iter_xarray(&iter, ITER_SOURCE, &mapping->i_pages, start, len);
 	fscache_write(cres, start, &iter, fscache_wreq_done, wreq);
 	return;
 

fs/fuse/ioctl.c

···
 		ap.args.in_pages = true;
 
 		err = -EFAULT;
-		iov_iter_init(&ii, WRITE, in_iov, in_iovs, in_size);
+		iov_iter_init(&ii, ITER_SOURCE, in_iov, in_iovs, in_size);
 		for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
 			c = copy_page_from_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
 			if (c != PAGE_SIZE && iov_iter_count(&ii))
···
 		goto out;
 
 	err = -EFAULT;
-	iov_iter_init(&ii, READ, out_iov, out_iovs, transferred);
+	iov_iter_init(&ii, ITER_DEST, out_iov, out_iovs, transferred);
 	for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
 		c = copy_page_to_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
 		if (c != PAGE_SIZE && iov_iter_count(&ii))

fs/netfs/io.c

···
 {
 	struct iov_iter iter;
 
-	iov_iter_xarray(&iter, READ, &subreq->rreq->mapping->i_pages,
+	iov_iter_xarray(&iter, ITER_DEST, &subreq->rreq->mapping->i_pages,
 			subreq->start + subreq->transferred,
 			subreq->len   - subreq->transferred);
 	iov_iter_zero(iov_iter_count(&iter), &iter);
···
 	struct iov_iter iter;
 
 	netfs_stat(&netfs_n_rh_read);
-	iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages,
+	iov_iter_xarray(&iter, ITER_DEST, &rreq->mapping->i_pages,
 			subreq->start + subreq->transferred,
 			subreq->len   - subreq->transferred);
 
···
 			continue;
 		}
 
-		iov_iter_xarray(&iter, WRITE, &rreq->mapping->i_pages,
+		iov_iter_xarray(&iter, ITER_SOURCE, &rreq->mapping->i_pages,
 				subreq->start, subreq->len);
 
 		atomic_inc(&rreq->nr_copy_ops);

fs/nfs/fscache.c

···
 	bvec[0].bv_page		= page;
 	bvec[0].bv_offset	= 0;
 	bvec[0].bv_len		= PAGE_SIZE;
-	iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
+	iov_iter_bvec(&iter, ITER_DEST, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
 
 	ret = fscache_begin_read_operation(&cres, cookie);
 	if (ret < 0)
···
 	bvec[0].bv_page		= page;
 	bvec[0].bv_offset	= 0;
 	bvec[0].bv_len		= PAGE_SIZE;
-	iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
+	iov_iter_bvec(&iter, ITER_SOURCE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
 
 	ret = fscache_begin_write_operation(&cres, cookie);
 	if (ret < 0)

fs/nfsd/vfs.c

···
 	ssize_t host_err;
 
 	trace_nfsd_read_vector(rqstp, fhp, offset, *count);
-	iov_iter_kvec(&iter, READ, vec, vlen, *count);
+	iov_iter_kvec(&iter, ITER_DEST, vec, vlen, *count);
 	host_err = vfs_iter_read(file, &iter, &ppos, 0);
 	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
 }
···
 	if (stable && !use_wgather)
 		flags |= RWF_SYNC;
 
-	iov_iter_kvec(&iter, WRITE, vec, vlen, *cnt);
+	iov_iter_kvec(&iter, ITER_SOURCE, vec, vlen, *cnt);
 	since = READ_ONCE(file->f_wb_err);
 	if (verf)
 		nfsd_copy_write_verifier(verf, nn);

fs/ocfs2/cluster/tcp.c

···
 {
 	struct kvec vec = { .iov_len = len, .iov_base = data, };
 	struct msghdr msg = { .msg_flags = MSG_DONTWAIT, };
-	iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, len);
+	iov_iter_kvec(&msg.msg_iter, ITER_DEST, &vec, 1, len);
 	return sock_recvmsg(sock, &msg, MSG_DONTWAIT);
 }
 

fs/orangefs/inode.c

···
 	bv.bv_len = wlen;
 	bv.bv_offset = off % PAGE_SIZE;
 	WARN_ON(wlen == 0);
-	iov_iter_bvec(&iter, WRITE, &bv, 1, wlen);
+	iov_iter_bvec(&iter, ITER_SOURCE, &bv, 1, wlen);
 
 	ret = wait_for_direct_io(ORANGEFS_IO_WRITE, inode, &off, &iter, wlen,
 	    len, wr, NULL, NULL);
···
 		else
 			ow->bv[i].bv_offset = 0;
 	}
-	iov_iter_bvec(&iter, WRITE, ow->bv, ow->npages, ow->len);
+	iov_iter_bvec(&iter, ITER_SOURCE, ow->bv, ow->npages, ow->len);
 
 	WARN_ON(ow->off >= len);
 	if (ow->off + ow->len > len)
···
 	offset = readahead_pos(rac);
 	i_pages = &rac->mapping->i_pages;
 
-	iov_iter_xarray(&iter, READ, i_pages, offset, readahead_length(rac));
+	iov_iter_xarray(&iter, ITER_DEST, i_pages, offset, readahead_length(rac));
 
 	/* read in the pages. */
 	if ((ret = wait_for_direct_io(ORANGEFS_IO_READ, inode,
···
 	bv.bv_page = &folio->page;
 	bv.bv_len = folio_size(folio);
 	bv.bv_offset = 0;
-	iov_iter_bvec(&iter, READ, &bv, 1, folio_size(folio));
+	iov_iter_bvec(&iter, ITER_DEST, &bv, 1, folio_size(folio));
 
 	ret = wait_for_direct_io(ORANGEFS_IO_READ, inode, &off, &iter,
 			folio_size(folio), inode->i_size, NULL, NULL, file);

fs/proc/vmcore.c

···
 	struct kvec kvec = { .iov_base = buf, .iov_len = count };
 	struct iov_iter iter;
 
-	iov_iter_kvec(&iter, READ, &kvec, 1, count);
+	iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
 
 	return read_from_oldmem(&iter, count, ppos, false);
 }
···
 	struct kvec kvec = { .iov_base = buf, .iov_len = count };
 	struct iov_iter iter;
 
-	iov_iter_kvec(&iter, READ, &kvec, 1, count);
+	iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
 
 	return read_from_oldmem(&iter, count, ppos,
 			cc_platform_has(CC_ATTR_MEM_ENCRYPT));
···
 		offset = (loff_t) index << PAGE_SHIFT;
 		kvec.iov_base = page_address(page);
 		kvec.iov_len = PAGE_SIZE;
-		iov_iter_kvec(&iter, READ, &kvec, 1, PAGE_SIZE);
+		iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, PAGE_SIZE);
 
 		rc = __read_vmcore(&iter, &offset);
 		if (rc < 0) {

fs/read_write.c

···
 
 	init_sync_kiocb(&kiocb, filp);
 	kiocb.ki_pos = (ppos ? *ppos : 0);
-	iov_iter_ubuf(&iter, READ, buf, len);
+	iov_iter_ubuf(&iter, ITER_DEST, buf, len);
 
 	ret = call_read_iter(filp, &kiocb, &iter);
 	BUG_ON(ret == -EIOCBQUEUED);
···
 
 	init_sync_kiocb(&kiocb, file);
 	kiocb.ki_pos = pos ? *pos : 0;
-	iov_iter_kvec(&iter, READ, &iov, 1, iov.iov_len);
+	iov_iter_kvec(&iter, ITER_DEST, &iov, 1, iov.iov_len);
 	ret = file->f_op->read_iter(&kiocb, &iter);
 	if (ret > 0) {
 		if (pos)
···
 
 	init_sync_kiocb(&kiocb, filp);
 	kiocb.ki_pos = (ppos ? *ppos : 0);
-	iov_iter_ubuf(&iter, WRITE, (void __user *)buf, len);
+	iov_iter_ubuf(&iter, ITER_SOURCE, (void __user *)buf, len);
 
 	ret = call_write_iter(filp, &kiocb, &iter);
 	BUG_ON(ret == -EIOCBQUEUED);
···
 		.iov_len	= min_t(size_t, count, MAX_RW_COUNT),
 	};
 	struct iov_iter iter;
-	iov_iter_kvec(&iter, WRITE, &iov, 1, iov.iov_len);
+	iov_iter_kvec(&iter, ITER_SOURCE, &iov, 1, iov.iov_len);
 	return __kernel_write_iter(file, &iter, pos);
 }
 /*
···
 	struct iov_iter iter;
 	ssize_t ret;
 
-	ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
+	ret = import_iovec(ITER_DEST, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
 	if (ret >= 0) {
 		ret = do_iter_read(file, &iter, pos, flags);
 		kfree(iov);
···
 	struct iov_iter iter;
 	ssize_t ret;
 
-	ret = import_iovec(WRITE, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
+	ret = import_iovec(ITER_SOURCE, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
 	if (ret >= 0) {
 		file_start_write(file);
 		ret = do_iter_write(file, &iter, pos, flags);

fs/seq_file.c

···
 	ssize_t ret;
 
 	init_sync_kiocb(&kiocb, file);
-	iov_iter_init(&iter, READ, &iov, 1, size);
+	iov_iter_init(&iter, ITER_DEST, &iov, 1, size);
 
 	kiocb.ki_pos = *ppos;
 	ret = seq_read_iter(&kiocb, &iter);

fs/splice.c

···
 	struct kiocb kiocb;
 	int ret;
 
-	iov_iter_pipe(&to, READ, pipe, len);
+	iov_iter_pipe(&to, ITER_DEST, pipe, len);
 	init_sync_kiocb(&kiocb, in);
 	kiocb.ki_pos = *ppos;
 	ret = call_read_iter(in, &kiocb, &to);
···
 			n++;
 		}
 
-		iov_iter_bvec(&from, WRITE, array, n, sd.total_len - left);
+		iov_iter_bvec(&from, ITER_SOURCE, array, n, sd.total_len - left);
 		ret = vfs_iter_write(out, &from, &sd.pos, 0);
 		if (ret <= 0)
 			break;
···
 	if (!f.file)
 		return -EBADF;
 	if (f.file->f_mode & FMODE_WRITE) {
-		*type = WRITE;
+		*type = ITER_SOURCE;
 	} else if (f.file->f_mode & FMODE_READ) {
-		*type = READ;
+		*type = ITER_DEST;
 	} else {
 		fdput(f);
 		return -EBADF;
···
 
 	if (!iov_iter_count(&iter))
 		error = 0;
-	else if (iov_iter_rw(&iter) == WRITE)
+	else if (type == ITER_SOURCE)
 		error = vmsplice_to_pipe(f.file, &iter, flags);
 	else
 		error = vmsplice_to_user(f.file, &iter, flags);

include/linux/uio.h

···
 	ITER_UBUF,
 };
 
+#define ITER_SOURCE	1	// == WRITE
+#define ITER_DEST	0	// == READ
+
 struct iov_iter_state {
 	size_t iov_offset;
 	size_t count;

io_uring/net.c

···
 	if (unlikely(!sock))
 		return -ENOTSOCK;
 
-	ret = import_single_range(WRITE, sr->buf, sr->len, &iov, &msg.msg_iter);
+	ret = import_single_range(ITER_SOURCE, sr->buf, sr->len, &iov, &msg.msg_iter);
 	if (unlikely(ret))
 		return ret;
 
···
 		}
 	} else {
 		iomsg->free_iov = iomsg->fast_iov;
-		ret = __import_iovec(READ, msg.msg_iov, msg.msg_iovlen, UIO_FASTIOV,
+		ret = __import_iovec(ITER_DEST, msg.msg_iov, msg.msg_iovlen, UIO_FASTIOV,
 				     &iomsg->free_iov, &iomsg->msg.msg_iter,
 				     false);
 		if (ret > 0)
···
 		}
 	} else {
 		iomsg->free_iov = iomsg->fast_iov;
-		ret = __import_iovec(READ, (struct iovec __user *)uiov, msg.msg_iovlen,
+		ret = __import_iovec(ITER_DEST, (struct iovec __user *)uiov, msg.msg_iovlen,
 				   UIO_FASTIOV, &iomsg->free_iov,
 				   &iomsg->msg.msg_iter, true);
 		if (ret < 0)
···
 
 		kmsg->fast_iov[0].iov_base = buf;
 		kmsg->fast_iov[0].iov_len = len;
-		iov_iter_init(&kmsg->msg.msg_iter, READ, kmsg->fast_iov, 1,
+		iov_iter_init(&kmsg->msg.msg_iter, ITER_DEST, kmsg->fast_iov, 1,
 				len);
 	}
 
···
 		sr->buf = buf;
 	}
 
-	ret = import_single_range(READ, sr->buf, len, &iov, &msg.msg_iter);
+	ret = import_single_range(ITER_DEST, sr->buf, len, &iov, &msg.msg_iter);
 	if (unlikely(ret))
 		goto out_free;
 
···
 		return io_setup_async_addr(req, &__address, issue_flags);
 
 	if (zc->flags & IORING_RECVSEND_FIXED_BUF) {
-		ret = io_import_fixed(WRITE, &msg.msg_iter, req->imu,
+		ret = io_import_fixed(ITER_SOURCE, &msg.msg_iter, req->imu,
 					(u64)(uintptr_t)zc->buf, zc->len);
 		if (unlikely(ret))
 			return ret;
 		msg.sg_from_iter = io_sg_from_iter;
 	} else {
-		ret = import_single_range(WRITE, zc->buf, zc->len, &iov,
+		ret = import_single_range(ITER_SOURCE, zc->buf, zc->len, &iov,
 					  &msg.msg_iter);
 		if (unlikely(ret))
 			return ret;

io_uring/rw.c

···
 
 int io_readv_prep_async(struct io_kiocb *req)
 {
-	return io_rw_prep_async(req, READ);
+	return io_rw_prep_async(req, ITER_DEST);
 }
 
 int io_writev_prep_async(struct io_kiocb *req)
 {
-	return io_rw_prep_async(req, WRITE);
+	return io_rw_prep_async(req, ITER_SOURCE);
 }
 
 /*
···
 	loff_t *ppos;
 
 	if (!req_has_async_data(req)) {
-		ret = io_import_iovec(READ, req, &iovec, s, issue_flags);
+		ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
 		if (unlikely(ret < 0))
 			return ret;
 	} else {
···
 		 * buffers, as we dropped the selected one before retry.
 		 */
 		if (io_do_buffer_select(req)) {
-			ret = io_import_iovec(READ, req, &iovec, s, issue_flags);
+			ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
 			if (unlikely(ret < 0))
 				return ret;
 		}
···
 	loff_t *ppos;
 
 	if (!req_has_async_data(req)) {
-		ret = io_import_iovec(WRITE, req, &iovec, s, issue_flags);
+		ret = io_import_iovec(ITER_SOURCE, req, &iovec, s, issue_flags);
 		if (unlikely(ret < 0))
 			return ret;
 	} else {

kernel/trace/trace_events_user.c

···
 	if (unlikely(*ppos != 0))
 		return -EFAULT;
 
-	if (unlikely(import_single_range(WRITE, (char __user *)ubuf,
+	if (unlikely(import_single_range(ITER_SOURCE, (char __user *)ubuf,
 					 count, &iov, &i)))
 		return -EFAULT;
 

lib/iov_iter.c

···
 
 size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 {
+	if (WARN_ON_ONCE(i->data_source))
+		return 0;
 	if (unlikely(iov_iter_is_pipe(i)))
 		return copy_pipe_to_iter(addr, bytes, i);
 	if (user_backed_iter(i))
···
  */
 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 {
+	if (WARN_ON_ONCE(i->data_source))
+		return 0;
 	if (unlikely(iov_iter_is_pipe(i)))
 		return copy_mc_pipe_to_iter(addr, bytes, i);
 	if (user_backed_iter(i))
···
 
 size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
 {
-	if (unlikely(iov_iter_is_pipe(i))) {
-		WARN_ON(1);
+	if (WARN_ON_ONCE(!i->data_source))
 		return 0;
-	}
+
 	if (user_backed_iter(i))
 		might_fault();
 	iterate_and_advance(i, bytes, base, len, off,
···
 
 size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
 {
-	if (unlikely(iov_iter_is_pipe(i))) {
-		WARN_ON(1);
+	if (WARN_ON_ONCE(!i->data_source))
 		return 0;
-	}
+
 	iterate_and_advance(i, bytes, base, len, off,
 		__copy_from_user_inatomic_nocache(addr + off, base, len),
 		memcpy(addr + off, base, len)
···
  */
 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 {
-	if (unlikely(iov_iter_is_pipe(i))) {
-		WARN_ON(1);
+	if (WARN_ON_ONCE(!i->data_source))
 		return 0;
-	}
+
 	iterate_and_advance(i, bytes, base, len, off,
 		__copy_from_user_flushcache(addr + off, base, len),
 		memcpy_flushcache(addr + off, base, len)
···
 	head = compound_head(page);
 	v += (page - head) << PAGE_SHIFT;
 
-	if (likely(n <= v && v <= (page_size(head))))
-		return true;
-	WARN_ON(1);
-	return false;
+	if (WARN_ON(n > v || v > page_size(head)))
+		return false;
+	return true;
 }
 
 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 			 struct iov_iter *i)
 {
 	size_t res = 0;
-	if (unlikely(!page_copy_sane(page, offset, bytes)))
+	if (!page_copy_sane(page, offset, bytes))
+		return 0;
+	if (WARN_ON_ONCE(i->data_source))
 		return 0;
 	if (unlikely(iov_iter_is_pipe(i)))
 		return copy_page_to_iter_pipe(page, offset, bytes, i);
···
 				  struct iov_iter *i)
 {
 	char *kaddr = kmap_atomic(page), *p = kaddr + offset;
-	if (unlikely(!page_copy_sane(page, offset, bytes))) {
+	if (!page_copy_sane(page, offset, bytes)) {
 		kunmap_atomic(kaddr);
 		return 0;
 	}
-	if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
+	if (WARN_ON_ONCE(!i->data_source)) {
 		kunmap_atomic(kaddr);
-		WARN_ON(1);
 		return 0;
 	}
 	iterate_and_advance(i, bytes, base, len, off,
···
 {
 	__wsum sum, next;
 	sum = *csum;
-	if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
-		WARN_ON(1);
+	if (WARN_ON_ONCE(!i->data_source))
 		return 0;
-	}
+
 	iterate_and_advance(i, bytes, base, len, off, ({
 		next = csum_and_copy_from_user(base, addr + off, len);
 		sum = csum_block_add(sum, next, off);
···
 	struct csum_state *csstate = _csstate;
 	__wsum sum, next;
 
-	if (unlikely(iov_iter_is_discard(i))) {
-		WARN_ON(1);	/* for now */
+	if (WARN_ON_ONCE(i->data_source))
 		return 0;
+	if (unlikely(iov_iter_is_discard(i))) {
+		// can't use csum_memcpy() for that one - data is not copied
+		csstate->csum = csum_block_add(csstate->csum,
+					       csum_partial(addr, bytes, 0),
+					       csstate->off);
+		csstate->off += bytes;
+		return bytes;
 	}
 
 	sum = csum_shift(csstate->csum, csstate->off);

mm/madvise.c

···
 		goto out;
 	}
 
-	ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
+	ret = import_iovec(ITER_DEST, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
 	if (ret < 0)
 		goto out;
 

mm/page_io.c

···
 	struct address_space *mapping = sio->iocb.ki_filp->f_mapping;
 	int ret;
 
-	iov_iter_bvec(&from, WRITE, sio->bvec, sio->pages, sio->len);
+	iov_iter_bvec(&from, ITER_SOURCE, sio->bvec, sio->pages, sio->len);
 	ret = mapping->a_ops->swap_rw(&sio->iocb, &from);
 	if (ret != -EIOCBQUEUED)
 		sio_write_complete(&sio->iocb, ret);
···
 	struct address_space *mapping = sio->iocb.ki_filp->f_mapping;
 	int ret;
 
-	iov_iter_bvec(&from, READ, sio->bvec, sio->pages, sio->len);
+	iov_iter_bvec(&from, ITER_DEST, sio->bvec, sio->pages, sio->len);
 	ret = mapping->a_ops->swap_rw(&sio->iocb, &from);
 	if (ret != -EIOCBQUEUED)
 		sio_read_complete(&sio->iocb, ret);

mm/process_vm_access.c

···
 	struct iovec *iov_r;
 	struct iov_iter iter;
 	ssize_t rc;
-	int dir = vm_write ? WRITE : READ;
+	int dir = vm_write ? ITER_SOURCE : ITER_DEST;
 
 	if (flags != 0)
 		return -EINVAL;

net/9p/client.c

···
 	struct kvec kv = {.iov_base = data, .iov_len = count};
 	struct iov_iter to;
 
-	iov_iter_kvec(&to, READ, &kv, 1, count);
+	iov_iter_kvec(&to, ITER_DEST, &kv, 1, count);
 
 	p9_debug(P9_DEBUG_9P, ">>> TREADDIR fid %d offset %llu count %d\n",
 		 fid->fid, offset, count);

net/bluetooth/6lowpan.c

···
 	iv.iov_len = skb->len;
 
 	memset(&msg, 0, sizeof(msg));
-	iov_iter_kvec(&msg.msg_iter, WRITE, &iv, 1, skb->len);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &iv, 1, skb->len);
 
 	err = l2cap_chan_send(chan, &msg, skb->len);
 	if (err > 0) {

net/bluetooth/a2mp.c

···
 
 	memset(&msg, 0, sizeof(msg));
 
-	iov_iter_kvec(&msg.msg_iter, WRITE, &iv, 1, total_len);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &iv, 1, total_len);
 
 	l2cap_chan_send(chan, &msg, total_len);
 

net/bluetooth/smp.c

···
 
 	memset(&msg, 0, sizeof(msg));
 
-	iov_iter_kvec(&msg.msg_iter, WRITE, iv, 2, 1 + len);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, iv, 2, 1 + len);
 
 	l2cap_chan_send(chan, &msg, 1 + len);
 

net/ceph/messenger_v1.c

···
 	if (!buf)
 		msg.msg_flags |= MSG_TRUNC;
 
-	iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, len);
+	iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, len);
 	r = sock_recvmsg(sock, &msg, msg.msg_flags);
 	if (r == -EAGAIN)
 		r = 0;
···
 	int r;
 
 	BUG_ON(page_offset + length > PAGE_SIZE);
-	iov_iter_bvec(&msg.msg_iter, READ, &bvec, 1, length);
+	iov_iter_bvec(&msg.msg_iter, ITER_DEST, &bvec, 1, length);
 	r = sock_recvmsg(sock, &msg, msg.msg_flags);
 	if (r == -EAGAIN)
 		r = 0;

net/ceph/messenger_v2.c

···
 						  bv.bv_offset, bv.bv_len,
 						  CEPH_MSG_FLAGS);
 		} else {
-			iov_iter_bvec(&msg.msg_iter, WRITE, &bv, 1, bv.bv_len);
+			iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bv, 1, bv.bv_len);
 			ret = sock_sendmsg(sock, &msg);
 		}
 		if (ret <= 0) {
···
 	WARN_ON(iov_iter_count(&con->v2.in_iter));
 
 	con->v2.in_kvec_cnt = 0;
-	iov_iter_kvec(&con->v2.in_iter, READ, con->v2.in_kvecs, 0, 0);
+	iov_iter_kvec(&con->v2.in_iter, ITER_DEST, con->v2.in_kvecs, 0, 0);
 }
 
 static void set_in_bvec(struct ceph_connection *con, const struct bio_vec *bv)
···
 	WARN_ON(iov_iter_count(&con->v2.in_iter));
 
 	con->v2.in_bvec = *bv;
-	iov_iter_bvec(&con->v2.in_iter, READ, &con->v2.in_bvec, 1, bv->bv_len);
+	iov_iter_bvec(&con->v2.in_iter, ITER_DEST, &con->v2.in_bvec, 1, bv->bv_len);
 }
 
 static void set_in_skip(struct ceph_connection *con, int len)
···
 	WARN_ON(iov_iter_count(&con->v2.in_iter));
 
 	dout("%s con %p len %d\n", __func__, con, len);
-	iov_iter_discard(&con->v2.in_iter, READ, len);
+	iov_iter_discard(&con->v2.in_iter, ITER_DEST, len);
 }
 
 static void add_out_kvec(struct ceph_connection *con, void *buf, int len)
···
 
 	con->v2.out_kvec_cnt = 0;
 
-	iov_iter_kvec(&con->v2.out_iter, WRITE, con->v2.out_kvecs, 0, 0);
+	iov_iter_kvec(&con->v2.out_iter, ITER_SOURCE, con->v2.out_kvecs, 0, 0);
 	con->v2.out_iter_sendpage = false;
 }
 
···
 
 	con->v2.out_bvec = *bv;
 	con->v2.out_iter_sendpage = zerocopy;
-	iov_iter_bvec(&con->v2.out_iter, WRITE, &con->v2.out_bvec, 1,
+	iov_iter_bvec(&con->v2.out_iter, ITER_SOURCE, &con->v2.out_bvec, 1,
 		      con->v2.out_bvec.bv_len);
 }
 
···
 	con->v2.out_bvec.bv_offset = 0;
 	con->v2.out_bvec.bv_len = min(con->v2.out_zero, (int)PAGE_SIZE);
 	con->v2.out_iter_sendpage = true;
-	iov_iter_bvec(&con->v2.out_iter, WRITE, &con->v2.out_bvec, 1,
+	iov_iter_bvec(&con->v2.out_iter, ITER_SOURCE, &con->v2.out_bvec, 1,
 		      con->v2.out_bvec.bv_len);
 }
 

net/compat.c

···
 	if (err)
 		return err;
 
-	err = import_iovec(save_addr ? READ : WRITE, compat_ptr(msg.msg_iov), msg.msg_iovlen,
+	err = import_iovec(save_addr ? ITER_DEST : ITER_SOURCE,
+			   compat_ptr(msg.msg_iov), msg.msg_iovlen,
 			   UIO_FASTIOV, iov, &kmsg->msg_iter);
 	return err < 0 ? err : 0;
 }

net/ipv4/tcp.c

···
 	if (copy_address != zc->copybuf_address)
 		return -EINVAL;
 
-	err = import_single_range(READ, (void __user *)copy_address,
+	err = import_single_range(ITER_DEST, (void __user *)copy_address,
 				  inq, &iov, &msg.msg_iter);
 	if (err)
 		return err;
···
 	if (copy_address != zc->copybuf_address)
 		return -EINVAL;
 
-	err = import_single_range(READ, (void __user *)copy_address,
+	err = import_single_range(ITER_DEST, (void __user *)copy_address,
 				  copylen, &iov, &msg.msg_iter);
 	if (err)
 		return err;

net/netfilter/ipvs/ip_vs_sync.c

···
 	EnterFunction(7);
 
 	/* Receive a packet */
-	iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, buflen);
+	iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, buflen);
 	len = sock_recvmsg(sock, &msg, MSG_DONTWAIT);
 	if (len < 0)
 		return len;

net/smc/smc_clc.c

···
 	 */
 	krflags = MSG_PEEK | MSG_WAITALL;
 	clc_sk->sk_rcvtimeo = timeout;
-	iov_iter_kvec(&msg.msg_iter, READ, &vec, 1,
+	iov_iter_kvec(&msg.msg_iter, ITER_DEST, &vec, 1,
 			sizeof(struct smc_clc_msg_hdr));
 	len = sock_recvmsg(smc->clcsock, &msg, krflags);
 	if (signal_pending(current)) {
···
 	} else {
 		recvlen = datlen;
 	}
-	iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, recvlen);
+	iov_iter_kvec(&msg.msg_iter, ITER_DEST, &vec, 1, recvlen);
 	krflags = MSG_WAITALL;
 	len = sock_recvmsg(smc->clcsock, &msg, krflags);
 	if (len < recvlen || !smc_clc_msg_hdr_valid(clcm, check_trl)) {
···
 		/* receive remaining proposal message */
 		recvlen = datlen > SMC_CLC_RECV_BUF_LEN ?
 						SMC_CLC_RECV_BUF_LEN : datlen;
-		iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, recvlen);
+		iov_iter_kvec(&msg.msg_iter, ITER_DEST, &vec, 1, recvlen);
 		len = sock_recvmsg(smc->clcsock, &msg, krflags);
 		datlen -= len;
 	}

net/smc/smc_tx.c

···
 
 	iov.iov_base = kaddr + offset;
 	iov.iov_len = size;
-	iov_iter_kvec(&msg.msg_iter, WRITE, &iov, 1, size);
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &iov, 1, size);
 	rc = smc_tx_sendmsg(smc, &msg, size);
 	kunmap(page);
 	return rc;

net/socket.c

···
 int kernel_sendmsg(struct socket *sock, struct msghdr *msg,
 		   struct kvec *vec, size_t num, size_t size)
 {
-	iov_iter_kvec(&msg->msg_iter, WRITE, vec, num, size);
+	iov_iter_kvec(&msg->msg_iter, ITER_SOURCE, vec, num, size);
 	return sock_sendmsg(sock, msg);
 }
 EXPORT_SYMBOL(kernel_sendmsg);
···
 	if (!sock->ops->sendmsg_locked)
 		return sock_no_sendmsg_locked(sk, msg, size);
 
-	iov_iter_kvec(&msg->msg_iter, WRITE, vec, num, size);
+	iov_iter_kvec(&msg->msg_iter, ITER_SOURCE, vec, num, size);
 
 	return sock->ops->sendmsg_locked(sk, msg, msg_data_left(msg));
 }
···
 		   struct kvec *vec, size_t num, size_t size, int flags)
 {
 	msg->msg_control_is_user = false;
-	iov_iter_kvec(&msg->msg_iter, READ, vec, num, size);
+	iov_iter_kvec(&msg->msg_iter, ITER_DEST, vec, num, size);
 	return sock_recvmsg(sock, msg, flags);
 }
 EXPORT_SYMBOL(kernel_recvmsg);
···
 	struct iovec iov;
 	int fput_needed;
 
-	err = import_single_range(WRITE, buff, len, &iov, &msg.msg_iter);
+	err = import_single_range(ITER_SOURCE, buff, len, &iov, &msg.msg_iter);
 	if (unlikely(err))
 		return err;
 	sock = sockfd_lookup_light(fd, &err, &fput_needed);
···
 	int err, err2;
 	int fput_needed;
 
-	err = import_single_range(READ, ubuf, size, &iov, &msg.msg_iter);
+	err = import_single_range(ITER_DEST, ubuf, size, &iov, &msg.msg_iter);
 	if (unlikely(err))
 		return err;
 	sock = sockfd_lookup_light(fd, &err, &fput_needed);
···
 	if (err)
 		return err;
 
-	err = import_iovec(save_addr ? READ : WRITE,
+	err = import_iovec(save_addr ? ITER_DEST : ITER_SOURCE,
 			    msg.msg_iov, msg.msg_iovlen,
 			    UIO_FASTIOV, iov, &kmsg->msg_iter);
 	return err < 0 ? err : 0;

net/sunrpc/socklib.c

···
 static int xprt_send_kvec(struct socket *sock, struct msghdr *msg,
 			  struct kvec *vec, size_t seek)
 {
-	iov_iter_kvec(&msg->msg_iter, WRITE, vec, 1, vec->iov_len);
+	iov_iter_kvec(&msg->msg_iter, ITER_SOURCE, vec, 1, vec->iov_len);
 	return xprt_sendmsg(sock, msg, seek);
 }
 
 static int xprt_send_pagedata(struct socket *sock, struct msghdr *msg,
 			      struct xdr_buf *xdr, size_t base)
 {
-	iov_iter_bvec(&msg->msg_iter, WRITE, xdr->bvec, xdr_buf_pagecount(xdr),
+	iov_iter_bvec(&msg->msg_iter, ITER_SOURCE, xdr->bvec, xdr_buf_pagecount(xdr),
 		      xdr->page_len + xdr->page_base);
 	return xprt_sendmsg(sock, msg, base + xdr->page_base);
 }
···
 	};
 	size_t len = iov[0].iov_len + iov[1].iov_len;
 
-	iov_iter_kvec(&msg->msg_iter, WRITE, iov, 2, len);
+	iov_iter_kvec(&msg->msg_iter, ITER_SOURCE, iov, 2, len);
 	return xprt_sendmsg(sock, msg, base);
 }
 

net/sunrpc/svcsock.c

···
 	rqstp->rq_respages = &rqstp->rq_pages[i];
 	rqstp->rq_next_page = rqstp->rq_respages + 1;
 
-	iov_iter_bvec(&msg.msg_iter, READ, bvec, i, buflen);
+	iov_iter_bvec(&msg.msg_iter, ITER_DEST, bvec, i, buflen);
 	if (seek) {
 		iov_iter_advance(&msg.msg_iter, seek);
 		buflen -= seek;
···
 		want = sizeof(rpc_fraghdr) - svsk->sk_tcplen;
 		iov.iov_base = ((char *)&svsk->sk_marker) + svsk->sk_tcplen;
 		iov.iov_len  = want;
-		iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, want);
+		iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, want);
 		len = sock_recvmsg(svsk->sk_sock, &msg, MSG_DONTWAIT);
 		if (len < 0)
 			return len;

net/sunrpc/xprtsock.c

···
 xs_read_kvec(struct socket *sock, struct msghdr *msg, int flags,
 		struct kvec *kvec, size_t count, size_t seek)
 {
-	iov_iter_kvec(&msg->msg_iter, READ, kvec, 1, count);
+	iov_iter_kvec(&msg->msg_iter, ITER_DEST, kvec, 1, count);
 	return xs_sock_recvmsg(sock, msg, flags, seek);
 }
 
···
 		struct bio_vec *bvec, unsigned long nr, size_t count,
 		size_t seek)
 {
-	iov_iter_bvec(&msg->msg_iter, READ, bvec, nr, count);
+	iov_iter_bvec(&msg->msg_iter, ITER_DEST, bvec, nr, count);
 	return xs_sock_recvmsg(sock, msg, flags, seek);
 }
 
···
 xs_read_discard(struct socket *sock, struct msghdr *msg, int flags,
 		size_t count)
 {
-	iov_iter_discard(&msg->msg_iter, READ, count);
+	iov_iter_discard(&msg->msg_iter, ITER_DEST, count);
 	return sock_recvmsg(sock, msg, flags);
 }
 

net/tipc/topsrv.c

···
 	iov.iov_base = &s;
 	iov.iov_len = sizeof(s);
 	msg.msg_name = NULL;
-	iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, iov.iov_len);
+	iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, iov.iov_len);
 	ret = sock_recvmsg(con->sock, &msg, MSG_DONTWAIT);
 	if (ret == -EWOULDBLOCK)
 		return -EWOULDBLOCK;

net/tls/tls_device.c

···
 	kaddr = kmap(page);
 	iov.iov_base = kaddr + offset;
 	iov.iov_len = size;
-	iov_iter_kvec(&msg_iter, WRITE, &iov, 1, size);
+	iov_iter_kvec(&msg_iter, ITER_SOURCE, &iov, 1, size);
 	iter_offset.msg_iter = &msg_iter;
 	rc = tls_push_data(sk, iter_offset, size, flags, TLS_RECORD_TYPE_DATA,
 			   NULL);
···
 	union tls_iter_offset iter;
 	struct iov_iter msg_iter;
 
-	iov_iter_kvec(&msg_iter, WRITE, NULL, 0, 0);
+	iov_iter_kvec(&msg_iter, ITER_SOURCE, NULL, 0, 0);
 	iter.msg_iter = &msg_iter;
 	return tls_push_data(sk, iter, 0, flags, TLS_RECORD_TYPE_DATA, NULL);
 }

net/xfrm/espintcp.c

···
 	*((__be16 *)buf) = cpu_to_be16(msglen);
 	pfx_iov.iov_base = buf;
 	pfx_iov.iov_len = sizeof(buf);
-	iov_iter_kvec(&pfx_iter, WRITE, &pfx_iov, 1, pfx_iov.iov_len);
+	iov_iter_kvec(&pfx_iter, ITER_SOURCE, &pfx_iov, 1, pfx_iov.iov_len);
 
 	err = sk_msg_memcopy_from_iter(sk, &pfx_iter, &emsg->skmsg,
 				       pfx_iov.iov_len);

security/keys/keyctl.c

···
 		struct iov_iter from;
 		int ret;
 
-		ret = import_single_range(WRITE, (void __user *)_payload, plen,
+		ret = import_single_range(ITER_SOURCE, (void __user *)_payload, plen,
 					  &iov, &from);
 		if (unlikely(ret))
 			return ret;
···
 	if (!_payload_iov)
 		ioc = 0;
 
-	ret = import_iovec(WRITE, _payload_iov, ioc,
+	ret = import_iovec(ITER_SOURCE, _payload_iov, ioc,
 				    ARRAY_SIZE(iovstack), &iov, &from);
 	if (ret < 0)
 		return ret;