[7/6] cifs: Make the cifs RDMA code use iterators

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 6bb9a90b018f..d9a06704daa8 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -4054,10 +4054,8 @@  smb2_new_read_req(void **buf, unsigned int *total_len,
 		struct smbd_buffer_descriptor_v1 *v1;
 		bool need_invalidate = server->dialect == SMB30_PROT_ID;
 
-		rdata->mr = smbd_register_mr(
-				server->smbd_conn, rdata->pages,
-				rdata->nr_pages, rdata->page_offset,
-				rdata->tailsz, true, need_invalidate);
+		rdata->mr = smbd_register_mr(server->smbd_conn, &rdata->iter,
+					     true, need_invalidate);
 		if (!rdata->mr)
 			return -EAGAIN;
 
@@ -4477,24 +4475,15 @@  smb2_async_writev(struct cifs_writedata *wdata,
 		struct smbd_buffer_descriptor_v1 *v1;
 		bool need_invalidate = server->dialect == SMB30_PROT_ID;
 
-		wdata->mr = smbd_register_mr(
-				server->smbd_conn, wdata->pages,
-				wdata->nr_pages, wdata->page_offset,
-				wdata->tailsz, false, need_invalidate);
+		wdata->mr = smbd_register_mr(server->smbd_conn, &wdata->iter,
+					     false, need_invalidate);
 		if (!wdata->mr) {
 			rc = -EAGAIN;
 			goto async_writev_out;
 		}
 		req->Length = 0;
 		req->DataOffset = 0;
-		if (wdata->nr_pages > 1)
-			req->RemainingBytes =
-				cpu_to_le32(
-					(wdata->nr_pages - 1) * wdata->pagesz -
-					wdata->page_offset + wdata->tailsz
-				);
-		else
-			req->RemainingBytes = cpu_to_le32(wdata->tailsz);
+		req->RemainingBytes = cpu_to_le32(iov_iter_count(&wdata->iter));
 		req->Channel = SMB2_CHANNEL_RDMA_V1_INVALIDATE;
 		if (need_invalidate)
 			req->Channel = SMB2_CHANNEL_RDMA_V1;
@@ -4517,7 +4506,7 @@  smb2_async_writev(struct cifs_writedata *wdata,
 #ifdef CONFIG_CIFS_SMB_DIRECT
 	if (wdata->mr) {
 		iov[0].iov_len += sizeof(struct smbd_buffer_descriptor_v1);
-		rqst.rq_npages = 0;
+		iov_iter_advance(&wdata->iter, iov_iter_count(&wdata->iter));
 	}
 #endif
 	cifs_dbg(FYI, "async write at %llu %u bytes\n",
diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
index 31ef64eb7fbb..5c311de5c9ac 100644
--- a/fs/cifs/smbdirect.c
+++ b/fs/cifs/smbdirect.c
@@ -34,12 +34,6 @@  static int smbd_post_recv(
 		struct smbd_response *response);
 
 static int smbd_post_send_empty(struct smbd_connection *info);
-static int smbd_post_send_data(
-		struct smbd_connection *info,
-		struct kvec *iov, int n_vec, int remaining_data_length);
-static int smbd_post_send_page(struct smbd_connection *info,
-		struct page *page, unsigned long offset,
-		size_t size, int remaining_data_length);
 
 static void destroy_mr_list(struct smbd_connection *info);
 static int allocate_mr_list(struct smbd_connection *info);
@@ -975,24 +969,6 @@  static int smbd_post_send_sgl(struct smbd_connection *info,
 	return rc;
 }
 
-/*
- * Send a page
- * page: the page to send
- * offset: offset in the page to send
- * size: length in the page to send
- * remaining_data_length: remaining data to send in this payload
- */
-static int smbd_post_send_page(struct smbd_connection *info, struct page *page,
-		unsigned long offset, size_t size, int remaining_data_length)
-{
-	struct scatterlist sgl;
-
-	sg_init_table(&sgl, 1);
-	sg_set_page(&sgl, page, size, offset);
-
-	return smbd_post_send_sgl(info, &sgl, size, remaining_data_length);
-}
-
 /*
  * Send an empty message
  * Empty message is used to extend credits to peer to for keep live
@@ -1004,35 +980,6 @@  static int smbd_post_send_empty(struct smbd_connection *info)
 	return smbd_post_send_sgl(info, NULL, 0, 0);
 }
 
-/*
- * Send a data buffer
- * iov: the iov array describing the data buffers
- * n_vec: number of iov array
- * remaining_data_length: remaining data to send following this packet
- * in segmented SMBD packet
- */
-static int smbd_post_send_data(
-	struct smbd_connection *info, struct kvec *iov, int n_vec,
-	int remaining_data_length)
-{
-	int i;
-	u32 data_length = 0;
-	struct scatterlist sgl[SMBDIRECT_MAX_SGE];
-
-	if (n_vec > SMBDIRECT_MAX_SGE) {
-		cifs_dbg(VFS, "Can't fit data to SGL, n_vec=%d\n", n_vec);
-		return -EINVAL;
-	}
-
-	sg_init_table(sgl, n_vec);
-	for (i = 0; i < n_vec; i++) {
-		data_length += iov[i].iov_len;
-		sg_set_buf(&sgl[i], iov[i].iov_base, iov[i].iov_len);
-	}
-
-	return smbd_post_send_sgl(info, sgl, data_length, remaining_data_length);
-}
-
 /*
  * Post a receive request to the transport
  * The remote peer can only send data when a receive request is posted
@@ -1976,6 +1923,42 @@  int smbd_recv(struct smbd_connection *info, struct msghdr *msg)
 	return rc;
 }
 
+/*
+ * Send the contents of an iterator
+ * @iter: The iterator to send
+ * @_remaining_data_length: remaining data to send in this payload
+ */
+static int smbd_post_send_iter(struct smbd_connection *info,
+			       struct iov_iter *iter,
+			       int *_remaining_data_length)
+{
+	struct scatterlist sgl;
+	struct page *page;
+	ssize_t len;
+	size_t offset, maxlen;
+	int i = 0, rc;
+
+	do {
+		maxlen = min_t(size_t, *_remaining_data_length, PAGE_SIZE);
+		len = iov_iter_get_pages(iter, &page, maxlen, 1, &offset);
+		if (len <= 0)
+			return len;
+
+		sg_init_table(&sgl, 1);
+		sg_set_page(&sgl, page, len, offset);
+
+		iov_iter_advance(iter, len);
+		*_remaining_data_length -= len;
+
+		log_write(INFO, "sending page i=%d offset=%zu size=%zu remaining_data_length=%d\n",
+			  i, offset, len, *_remaining_data_length);
+		rc = smbd_post_send_sgl(info, &sgl, len, *_remaining_data_length);
+		put_page(page);
+	} while (rc == 0);
+
+	return rc;
+}
+
 /*
  * Send data to transport
  * Each rqst is transported as a SMBDirect payload
@@ -1986,17 +1969,10 @@  int smbd_send(struct TCP_Server_Info *server,
 	int num_rqst, struct smb_rqst *rqst_array)
 {
 	struct smbd_connection *info = server->smbd_conn;
-	struct kvec vec;
-	int nvecs;
-	int size;
-	unsigned int buflen, remaining_data_length;
-	int start, i, j;
-	int max_iov_size =
-		info->max_send_size - sizeof(struct smbd_data_transfer);
-	struct kvec *iov;
-	int rc;
 	struct smb_rqst *rqst;
-	int rqst_idx;
+	struct iov_iter iter;
+	unsigned int remaining_data_length;
+	int rc, i, rqst_idx;
 
 	if (info->transport_status != SMBD_CONNECTED) {
 		rc = -EAGAIN;
@@ -2025,108 +2001,30 @@  int smbd_send(struct TCP_Server_Info *server,
 	rqst_idx = 0;
 next_rqst:
 	rqst = &rqst_array[rqst_idx];
-	iov = rqst->rq_iov;
 
 	cifs_dbg(FYI, "Sending smb (RDMA): idx=%d smb_len=%lu\n",
 		rqst_idx, smb_rqst_len(server, rqst));
 	for (i = 0; i < rqst->rq_nvec; i++)
-		dump_smb(iov[i].iov_base, iov[i].iov_len);
-
-
-	log_write(INFO, "rqst_idx=%d nvec=%d rqst->rq_npages=%d rq_pagesz=%d rq_tailsz=%d buflen=%lu\n",
-		  rqst_idx, rqst->rq_nvec, rqst->rq_npages, rqst->rq_pagesz,
-		  rqst->rq_tailsz, smb_rqst_len(server, rqst));
-
-	start = i = 0;
-	buflen = 0;
-	while (true) {
-		buflen += iov[i].iov_len;
-		if (buflen > max_iov_size) {
-			if (i > start) {
-				remaining_data_length -=
-					(buflen-iov[i].iov_len);
-				log_write(INFO, "sending iov[] from start=%d i=%d nvecs=%d remaining_data_length=%d\n",
-					  start, i, i - start,
-					  remaining_data_length);
-				rc = smbd_post_send_data(
-					info, &iov[start], i-start,
-					remaining_data_length);
-				if (rc)
-					goto done;
-			} else {
-				/* iov[start] is too big, break it */
-				nvecs = (buflen+max_iov_size-1)/max_iov_size;
-				log_write(INFO, "iov[%d] iov_base=%p buflen=%d break to %d vectors\n",
-					  start, iov[start].iov_base,
-					  buflen, nvecs);
-				for (j = 0; j < nvecs; j++) {
-					vec.iov_base =
-						(char *)iov[start].iov_base +
-						j*max_iov_size;
-					vec.iov_len = max_iov_size;
-					if (j == nvecs-1)
-						vec.iov_len =
-							buflen -
-							max_iov_size*(nvecs-1);
-					remaining_data_length -= vec.iov_len;
-					log_write(INFO,
-						"sending vec j=%d iov_base=%p iov_len=%zu remaining_data_length=%d\n",
-						  j, vec.iov_base, vec.iov_len,
-						  remaining_data_length);
-					rc = smbd_post_send_data(
-						info, &vec, 1,
-						remaining_data_length);
-					if (rc)
-						goto done;
-				}
-				i++;
-				if (i == rqst->rq_nvec)
-					break;
-			}
-			start = i;
-			buflen = 0;
-		} else {
-			i++;
-			if (i == rqst->rq_nvec) {
-				/* send out all remaining vecs */
-				remaining_data_length -= buflen;
-				log_write(INFO, "sending iov[] from start=%d i=%d nvecs=%d remaining_data_length=%d\n",
-					  start, i, i - start,
-					  remaining_data_length);
-				rc = smbd_post_send_data(info, &iov[start],
-					i-start, remaining_data_length);
-				if (rc)
-					goto done;
-				break;
-			}
-		}
-		log_write(INFO, "looping i=%d buflen=%d\n", i, buflen);
-	}
-
-	/* now sending pages if there are any */
-	for (i = 0; i < rqst->rq_npages; i++) {
-		unsigned int offset;
-
-		rqst_page_get_length(rqst, i, &buflen, &offset);
-		nvecs = (buflen + max_iov_size - 1) / max_iov_size;
-		log_write(INFO, "sending pages buflen=%d nvecs=%d\n",
-			buflen, nvecs);
-		for (j = 0; j < nvecs; j++) {
-			size = max_iov_size;
-			if (j == nvecs-1)
-				size = buflen - j*max_iov_size;
-			remaining_data_length -= size;
-			log_write(INFO, "sending pages i=%d offset=%d size=%d remaining_data_length=%d\n",
-				  i, j * max_iov_size + offset, size,
-				  remaining_data_length);
-			rc = smbd_post_send_page(
-				info, rqst->rq_pages[i],
-				j*max_iov_size + offset,
-				size, remaining_data_length);
-			if (rc)
-				goto done;
-		}
-	}
+		dump_smb(rqst->rq_iov[i].iov_base, rqst->rq_iov[i].iov_len);
+
+
+	log_write(INFO, "rqst_idx=%d nvec=%d rqst->rq_iter=%zd buflen=%lu\n",
+		  rqst_idx, rqst->rq_nvec, iov_iter_count(&rqst->rq_iter),
+		  smb_rqst_len(server, rqst));
+
+	/* Send the metadata pages. */
+	iov_iter_kvec(&iter, WRITE, rqst->rq_iov, rqst->rq_nvec,
+		      rqst->rq_iov[0].iov_len +
+		      (rqst->rq_nvec > 1 ? rqst->rq_iov[1].iov_len : 0));
+
+	rc = smbd_post_send_iter(info, &iter, &remaining_data_length);
+	if (rc < 0)
+		goto done;
+
+	/* And then the data pages if there are any */
+	rc = smbd_post_send_iter(info, &rqst->rq_iter, &remaining_data_length);
+	if (rc < 0)
+		goto done;
 
 	rqst_idx++;
 	if (rqst_idx < num_rqst)
@@ -2336,6 +2234,35 @@  static struct smbd_mr *get_mr(struct smbd_connection *info)
 	goto again;
 }
 
+/*
+ * Transcribe the pages from an iterator into an MR scatterlist.
+ * @iter: The iterator to transcribe
+ * @_remaining_data_length: remaining data to send in this payload
+ */
+static int smbd_iter_to_mr(struct smbd_connection *info,
+			   struct iov_iter *iter,
+			   struct scatterlist *sgl,
+			   unsigned int num_pages)
+{
+	struct page *page;
+	ssize_t len;
+	size_t offset, maxlen;
+
+	sg_init_table(sgl, num_pages);
+
+	for (;;) {
+		maxlen = min_t(size_t, iov_iter_count(iter), PAGE_SIZE);
+		len = iov_iter_get_pages(iter, &page, maxlen, 1, &offset);
+		if (len <= 0)
+			return len;
+
+		sg_set_page(sgl, page, len, offset);
+		sgl++;
+		put_page(page);
+		iov_iter_advance(iter, len);
+	}
+}
+
 /*
  * Register memory for RDMA read/write
  * pages[]: the list of pages to register memory with
@@ -2346,14 +2273,15 @@  static struct smbd_mr *get_mr(struct smbd_connection *info)
  * return value: the MR registered, NULL if failed.
  */
 struct smbd_mr *smbd_register_mr(
-	struct smbd_connection *info, struct page *pages[], int num_pages,
-	int offset, int tailsz, bool writing, bool need_invalidate)
+	struct smbd_connection *info, struct iov_iter *iter,
+	bool writing, bool need_invalidate)
 {
 	struct smbd_mr *smbdirect_mr;
-	int rc, i;
+	int rc, num_pages;
 	enum dma_data_direction dir;
 	struct ib_reg_wr *reg_wr;
 
+	num_pages = iov_iter_npages(iter, info->max_frmr_depth + 1);
 	if (num_pages > info->max_frmr_depth) {
 		log_rdma_mr(ERR, "num_pages=%d max_frmr_depth=%d\n",
 			num_pages, info->max_frmr_depth);
@@ -2365,32 +2293,16 @@  struct smbd_mr *smbd_register_mr(
 		log_rdma_mr(ERR, "get_mr returning NULL\n");
 		return NULL;
 	}
+
+	dir = writing ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+	smbdirect_mr->dir = dir;
 	smbdirect_mr->need_invalidate = need_invalidate;
 	smbdirect_mr->sgl_count = num_pages;
-	sg_init_table(smbdirect_mr->sgl, num_pages);
-
-	log_rdma_mr(INFO, "num_pages=0x%x offset=0x%x tailsz=0x%x\n",
-			num_pages, offset, tailsz);
-
-	if (num_pages == 1) {
-		sg_set_page(&smbdirect_mr->sgl[0], pages[0], tailsz, offset);
-		goto skip_multiple_pages;
-	}
 
-	/* We have at least two pages to register */
-	sg_set_page(
-		&smbdirect_mr->sgl[0], pages[0], PAGE_SIZE - offset, offset);
-	i = 1;
-	while (i < num_pages - 1) {
-		sg_set_page(&smbdirect_mr->sgl[i], pages[i], PAGE_SIZE, 0);
-		i++;
-	}
-	sg_set_page(&smbdirect_mr->sgl[i], pages[i],
-		tailsz ? tailsz : PAGE_SIZE, 0);
+	log_rdma_mr(INFO, "num_pages=0x%x count=0x%zx\n",
+		    num_pages, iov_iter_count(iter));
+	smbd_iter_to_mr(info, iter, smbdirect_mr->sgl, num_pages);
 
-skip_multiple_pages:
-	dir = writing ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
-	smbdirect_mr->dir = dir;
 	rc = ib_dma_map_sg(info->id->device, smbdirect_mr->sgl, num_pages, dir);
 	if (!rc) {
 		log_rdma_mr(ERR, "ib_dma_map_sg num_pages=%x dir=%x rc=%x\n",
diff --git a/fs/cifs/smbdirect.h b/fs/cifs/smbdirect.h
index a87fca82a796..3a0d39e148e8 100644
--- a/fs/cifs/smbdirect.h
+++ b/fs/cifs/smbdirect.h
@@ -298,8 +298,8 @@  struct smbd_mr {
 
 /* Interfaces to register and deregister MR for RDMA read/write */
 struct smbd_mr *smbd_register_mr(
-	struct smbd_connection *info, struct page *pages[], int num_pages,
-	int offset, int tailsz, bool writing, bool need_invalidate);
+	struct smbd_connection *info, struct iov_iter *iter,
+	bool writing, bool need_invalidate);
 int smbd_deregister_mr(struct smbd_mr *mr);
 
 #else