util: add spdk_iov_xfer_*() API

Add a new API for incremental copying in or out of an iovec, and replace
current code to use the new API.

Signed-off-by: John Levon <john.levon@nutanix.com>
Change-Id: I088b784aef821310699478989e61411952066c18
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16193
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@nvidia.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

CHANGELOG.md

@@ -131,6 +131,9 @@ names with this option to restrict allowed RPCs to only that list.
 Added `--vfio-vf-token` command line option to specify a VF token (UUID)
 shared between SR-IOV PF and VFs for vfio_pci driver.
 
+The `spdk_iov_xfer_*()` APIs were added for handling incremental copying between
+an iovec and a buffer.
+
 ### json
 
 Added API `spdk_json_write_double` and `spdk_json_write_named_double` to allow

include/spdk/util.h

@@ -169,6 +169,37 @@ size_t spdk_iovcpy(struct iovec *siov, size_t siovcnt, struct iovec *diov, size_
  */
 size_t spdk_iovmove(struct iovec *siov, size_t siovcnt, struct iovec *diov, size_t diovcnt);
 
+/**
+ * Transfer state for iterative copying in or out of an iovec.
+ */
+struct spdk_iov_xfer {
+	struct iovec *iovs;
+	int iovcnt;
+	int cur_iov_idx;
+	size_t cur_iov_offset;
+};
+
+/**
+ * Initialize a transfer context to point to the given iovec.
+ */
+void
+spdk_iov_xfer_init(struct spdk_iov_xfer *ix, struct iovec *iovs, int iovcnt);
+
+/**
+ * Copy from the given buf up to buf_len bytes, into the given ix iovec
+ * iterator, advancing the iterator as needed.. Returns the number of bytes
+ * copied.
+ */
+size_t
+spdk_iov_xfer_from_buf(struct spdk_iov_xfer *ix, const void *buf, size_t buf_len);
+
+/**
+ * Copy from the given ix iovec iterator into the given buf up to buf_len
+ * bytes, advancing the iterator as needed. Returns the number of bytes copied.
+ */
+size_t
+spdk_iov_xfer_to_buf(struct spdk_iov_xfer *ix, const void *buf, size_t buf_len);
+
 /**
  * Copy iovs contents to buf through memcpy.
  */

lib/nvmf/ctrlr.c

@@ -53,56 +53,6 @@ static struct spdk_nvmf_custom_admin_cmd g_nvmf_custom_admin_cmd_hdlrs[SPDK_NVME
 
 static void _nvmf_request_complete(void *ctx);
 
-struct copy_iovs_ctx {
-	struct iovec *iovs;
-	int iovcnt;
-	int cur_iov_idx;
-	size_t cur_iov_offset;
-};
-
-static void
-_init_copy_iovs_ctx(struct copy_iovs_ctx *copy_ctx, struct iovec *iovs, int iovcnt)
-{
-	copy_ctx->iovs = iovs;
-	copy_ctx->iovcnt = iovcnt;
-	copy_ctx->cur_iov_idx = 0;
-	copy_ctx->cur_iov_offset = 0;
-}
-
-static size_t
-_copy_buf_to_iovs(struct copy_iovs_ctx *copy_ctx, const void *buf, size_t buf_len)
-{
-	size_t len, iov_remain_len, copied_len = 0;
-	struct iovec *iov;
-
-	if (buf_len == 0) {
-		return 0;
-	}
-
-	while (copy_ctx->cur_iov_idx < copy_ctx->iovcnt) {
-		iov = &copy_ctx->iovs[copy_ctx->cur_iov_idx];
-		iov_remain_len = iov->iov_len - copy_ctx->cur_iov_offset;
-		if (iov_remain_len == 0) {
-			copy_ctx->cur_iov_idx++;
-			copy_ctx->cur_iov_offset = 0;
-			continue;
-		}
-
-		len = spdk_min(iov_remain_len, buf_len - copied_len);
-		memcpy((char *)iov->iov_base + copy_ctx->cur_iov_offset,
-		       (const char *)buf + copied_len,
-		       len);
-		copied_len += len;
-		copy_ctx->cur_iov_offset += len;
-
-		if (buf_len == copied_len) {
-			return copied_len;
-		}
-	}
-
-	return copied_len;
-}
-
 static inline void
 nvmf_invalid_connect_response(struct spdk_nvmf_fabric_connect_rsp *rsp,
 			      uint8_t iattr, uint16_t ipo)
@@ -1712,7 +1662,7 @@ nvmf_ctrlr_get_features_host_identifier(struct spdk_nvmf_request *req)
 	struct spdk_nvmf_ctrlr *ctrlr = req->qpair->ctrlr;
 	struct spdk_nvme_cmd *cmd = &req->cmd->nvme_cmd;
 	struct spdk_nvme_cpl *response = &req->rsp->nvme_cpl;
-	struct copy_iovs_ctx copy_ctx;
+	struct spdk_iov_xfer ix;
 
 	SPDK_DEBUGLOG(nvmf, "Get Features - Host Identifier\n");
 
@@ -1723,14 +1673,14 @@ nvmf_ctrlr_get_features_host_identifier(struct spdk_nvmf_request *req)
 		return SPDK_NVMF_REQUEST_EXEC_STATUS_COMPLETE;
 	}
 
-	if (req->data == NULL || req->length < sizeof(ctrlr->hostid)) {
+	if (req->iovcnt < 1 || req->length < sizeof(ctrlr->hostid)) {
 		SPDK_ERRLOG("Invalid data buffer for Get Features - Host Identifier\n");
 		response->status.sc = SPDK_NVME_SC_INVALID_FIELD;
 		return SPDK_NVMF_REQUEST_EXEC_STATUS_COMPLETE;
 	}
 
-	_init_copy_iovs_ctx(&copy_ctx, req->iov, req->iovcnt);
+	spdk_iov_xfer_init(&ix, req->iov, req->iovcnt);
-	_copy_buf_to_iovs(&copy_ctx, &ctrlr->hostid, sizeof(ctrlr->hostid));
+	spdk_iov_xfer_from_buf(&ix, &ctrlr->hostid, sizeof(ctrlr->hostid));
 
 	return SPDK_NVMF_REQUEST_EXEC_STATUS_COMPLETE;
 }
@@ -1858,11 +1808,11 @@ nvmf_ctrlr_get_features_host_behavior_support(struct spdk_nvmf_request *req)
 	struct spdk_nvmf_ctrlr *ctrlr = req->qpair->ctrlr;
 	struct spdk_nvme_cpl *response = &req->rsp->nvme_cpl;
 	struct spdk_nvme_host_behavior host_behavior = {};
-	struct copy_iovs_ctx copy_ctx;
+	struct spdk_iov_xfer ix;
 
 	SPDK_DEBUGLOG(nvmf, "Get Features - Host Behavior Support\n");
 
-	if (req->data == NULL || req->length < sizeof(struct spdk_nvme_host_behavior)) {
+	if (req->iovcnt < 1 || req->length < sizeof(struct spdk_nvme_host_behavior)) {
 		SPDK_ERRLOG("invalid data buffer for Host Behavior Support\n");
 		response->status.sct = SPDK_NVME_SCT_GENERIC;
 		response->status.sc = SPDK_NVME_SC_INVALID_FIELD;
@@ -1871,8 +1821,8 @@ nvmf_ctrlr_get_features_host_behavior_support(struct spdk_nvmf_request *req)
 
 	host_behavior.acre = ctrlr->acre_enabled;
 
-	_init_copy_iovs_ctx(&copy_ctx, req->iov, req->iovcnt);
+	spdk_iov_xfer_init(&ix, req->iov, req->iovcnt);
-	_copy_buf_to_iovs(&copy_ctx, &host_behavior, sizeof(host_behavior));
+	spdk_iov_xfer_from_buf(&ix, &host_behavior, sizeof(host_behavior));
 
 	return SPDK_NVMF_REQUEST_EXEC_STATUS_COMPLETE;
 }
@@ -2151,9 +2101,9 @@ nvmf_get_firmware_slot_log_page(struct iovec *iovs, int iovcnt, uint64_t offset,
 {
 	struct spdk_nvme_firmware_page fw_page;
 	size_t copy_len;
-	struct copy_iovs_ctx copy_ctx;
+	struct spdk_iov_xfer ix;
 
-	_init_copy_iovs_ctx(&copy_ctx, iovs, iovcnt);
+	spdk_iov_xfer_init(&ix, iovs, iovcnt);
 
 	memset(&fw_page, 0, sizeof(fw_page));
 	fw_page.afi.active_slot = 1;
@@ -2163,7 +2113,7 @@ nvmf_get_firmware_slot_log_page(struct iovec *iovs, int iovcnt, uint64_t offset,
 	if (offset < sizeof(fw_page)) {
 		copy_len = spdk_min(sizeof(fw_page) - offset, length);
 		if (copy_len > 0) {
-			_copy_buf_to_iovs(&copy_ctx, (const char *)&fw_page + offset, copy_len);
+			spdk_iov_xfer_from_buf(&ix, (const char *)&fw_page + offset, copy_len);
 		}
 	}
 }
@@ -2259,9 +2209,9 @@ nvmf_get_ana_log_page(struct spdk_nvmf_ctrlr *ctrlr, struct iovec *iovs, int iov
 	size_t copy_len, copied_len;
 	uint32_t num_anagrp = 0, anagrpid;
 	struct spdk_nvmf_ns *ns;
-	struct copy_iovs_ctx copy_ctx;
+	struct spdk_iov_xfer ix;
 
-	_init_copy_iovs_ctx(&copy_ctx, iovs, iovcnt);
+	spdk_iov_xfer_init(&ix, iovs, iovcnt);
 
 	if (length == 0) {
 		goto done;
@@ -2283,7 +2233,7 @@ nvmf_get_ana_log_page(struct spdk_nvmf_ctrlr *ctrlr, struct iovec *iovs, int iov
 		ana_hdr.change_count = 0;
 
 		copy_len = spdk_min(sizeof(ana_hdr) - offset, length);
-		copied_len = _copy_buf_to_iovs(&copy_ctx, (const char *)&ana_hdr + offset, copy_len);
+		copied_len = spdk_iov_xfer_from_buf(&ix, (const char *)&ana_hdr + offset, copy_len);
 		assert(copied_len == copy_len);
 		length -= copied_len;
 		offset = 0;
@@ -2308,8 +2258,8 @@ nvmf_get_ana_log_page(struct spdk_nvmf_ctrlr *ctrlr, struct iovec *iovs, int iov
 			ana_desc.ana_state = nvmf_ctrlr_get_ana_state(ctrlr, anagrpid);
 
 			copy_len = spdk_min(sizeof(ana_desc) - offset, length);
-			copied_len = _copy_buf_to_iovs(&copy_ctx, (const char *)&ana_desc + offset,
+			copied_len = spdk_iov_xfer_from_buf(&ix, (const char *)&ana_desc + offset,
-						       copy_len);
+							    copy_len);
 			assert(copied_len == copy_len);
 			length -= copied_len;
 			offset = 0;
@@ -2334,8 +2284,8 @@ nvmf_get_ana_log_page(struct spdk_nvmf_ctrlr *ctrlr, struct iovec *iovs, int iov
 			}
 
 			copy_len = spdk_min(sizeof(uint32_t) - offset, length);
-			copied_len = _copy_buf_to_iovs(&copy_ctx, (const char *)&ns->nsid + offset,
+			copied_len = spdk_iov_xfer_from_buf(&ix, (const char *)&ns->nsid + offset,
-						       copy_len);
+							    copy_len);
 			assert(copied_len == copy_len);
 			length -= copied_len;
 			offset = 0;
@@ -2385,14 +2335,14 @@ nvmf_get_changed_ns_list_log_page(struct spdk_nvmf_ctrlr *ctrlr,
 				  struct iovec *iovs, int iovcnt, uint64_t offset, uint32_t length, uint32_t rae)
 {
 	size_t copy_length;
-	struct copy_iovs_ctx copy_ctx;
+	struct spdk_iov_xfer ix;
 
-	_init_copy_iovs_ctx(&copy_ctx, iovs, iovcnt);
+	spdk_iov_xfer_init(&ix, iovs, iovcnt);
 
 	if (offset < sizeof(ctrlr->changed_ns_list)) {
 		copy_length = spdk_min(length, sizeof(ctrlr->changed_ns_list) - offset);
 		if (copy_length) {
-			_copy_buf_to_iovs(&copy_ctx, (char *)&ctrlr->changed_ns_list + offset, copy_length);
+			spdk_iov_xfer_from_buf(&ix, (char *)&ctrlr->changed_ns_list + offset, copy_length);
 		}
 	}
 
@@ -2450,11 +2400,11 @@ nvmf_get_cmds_and_effects_log_page(struct spdk_nvmf_ctrlr *ctrlr, struct iovec *
 {
 	uint32_t page_size = sizeof(struct spdk_nvme_cmds_and_effect_log_page);
 	size_t copy_len = 0;
-	struct copy_iovs_ctx copy_ctx;
 	struct spdk_nvme_cmds_and_effect_log_page cmds_and_effect_log_page = g_cmds_and_effect_log_page;
 	struct spdk_nvme_cmds_and_effect_entry csupp_and_lbcc_effect_entry = {1, 1, 0, 0, 0, 0, 0, 0};
+	struct spdk_iov_xfer ix;
 
-	_init_copy_iovs_ctx(&copy_ctx, iovs, iovcnt);
+	spdk_iov_xfer_init(&ix, iovs, iovcnt);
 
 	if (offset < page_size) {
 		if (ctrlr->subsys->zone_append_supported) {
@@ -2462,7 +2412,7 @@ nvmf_get_cmds_and_effects_log_page(struct spdk_nvmf_ctrlr *ctrlr, struct iovec *
 				csupp_and_lbcc_effect_entry;
 		}
 		copy_len = spdk_min(page_size - offset, length);
-		_copy_buf_to_iovs(&copy_ctx, (char *)(&cmds_and_effect_log_page) + offset, copy_len);
+		spdk_iov_xfer_from_buf(&ix, (char *)(&cmds_and_effect_log_page) + offset, copy_len);
 	}
 }
 
@@ -2472,9 +2422,9 @@ nvmf_get_reservation_notification_log_page(struct spdk_nvmf_ctrlr *ctrlr,
 {
 	uint32_t unit_log_len, avail_log_len, next_pos, copy_len;
 	struct spdk_nvmf_reservation_log *log, *log_tmp;
-	struct copy_iovs_ctx copy_ctx;
+	struct spdk_iov_xfer ix;
 
-	_init_copy_iovs_ctx(&copy_ctx, iovs, iovcnt);
+	spdk_iov_xfer_init(&ix, iovs, iovcnt);
 
 	unit_log_len = sizeof(struct spdk_nvme_reservation_notification_log);
 	/* No available log, return zeroed log pages */
@@ -2495,7 +2445,7 @@ nvmf_get_reservation_notification_log_page(struct spdk_nvmf_ctrlr *ctrlr,
 		next_pos += unit_log_len;
 		if (next_pos > offset) {
 			copy_len = spdk_min(next_pos - offset, length);
-			_copy_buf_to_iovs(&copy_ctx, &log->log, copy_len);
+			spdk_iov_xfer_from_buf(&ix, &log->log, copy_len);
 			length -= copy_len;
 			offset += copy_len;
 		}
@@ -3055,9 +3005,9 @@ nvmf_ctrlr_identify(struct spdk_nvmf_request *req)
 	struct spdk_nvmf_subsystem *subsystem = ctrlr->subsys;
 	int ret = SPDK_NVMF_REQUEST_EXEC_STATUS_COMPLETE;
 	char tmpbuf[SPDK_NVME_IDENTIFY_BUFLEN] = "";
-	struct copy_iovs_ctx copy_ctx;
+	struct spdk_iov_xfer ix;
 
-	if (req->data == NULL || req->length < SPDK_NVME_IDENTIFY_BUFLEN) {
+	if (req->iovcnt < 1 || req->length < SPDK_NVME_IDENTIFY_BUFLEN) {
 		SPDK_DEBUGLOG(nvmf, "identify command with invalid buffer\n");
 		rsp->status.sct = SPDK_NVME_SCT_GENERIC;
 		rsp->status.sc = SPDK_NVME_SC_INVALID_FIELD;
@@ -3076,7 +3026,7 @@ nvmf_ctrlr_identify(struct spdk_nvmf_request *req)
 	 * We must use a temporary buffer: it's entirely possible the out buffer
 	 * is split across more than one IOV.
 	 */
-	_init_copy_iovs_ctx(&copy_ctx, req->iov, req->iovcnt);
+	spdk_iov_xfer_init(&ix, req->iov, req->iovcnt);
 
 	SPDK_DEBUGLOG(nvmf, "Received identify command with CNS 0x%02x\n", cns);
 
@@ -3105,7 +3055,7 @@ nvmf_ctrlr_identify(struct spdk_nvmf_request *req)
 	}
 
 	if (ret == SPDK_NVMF_REQUEST_EXEC_STATUS_COMPLETE) {
-		_copy_buf_to_iovs(&copy_ctx, tmpbuf, sizeof(tmpbuf));
+		spdk_iov_xfer_from_buf(&ix, tmpbuf, sizeof(tmpbuf));
 	}
 
 	return ret;

lib/nvmf/ctrlr_bdev.c

@@ -581,7 +581,7 @@ nvmf_bdev_ctrlr_unmap(struct spdk_bdev *bdev, struct spdk_bdev_desc *desc,
 	uint16_t nr, i;
 	struct spdk_nvme_cmd *cmd = &req->cmd->nvme_cmd;
 	struct spdk_nvme_cpl *response = &req->rsp->nvme_cpl;
-	struct spdk_nvme_dsm_range *dsm_range;
+	struct spdk_iov_xfer ix;
 	uint64_t lba;
 	uint32_t lba_count;
 	int rc;
@@ -611,10 +611,15 @@ nvmf_bdev_ctrlr_unmap(struct spdk_bdev *bdev, struct spdk_bdev_desc *desc,
 		unmap_ctx->count--;	/* dequeued */
 	}
 
-	dsm_range = (struct spdk_nvme_dsm_range *)req->data;
+	spdk_iov_xfer_init(&ix, req->iov, req->iovcnt);
+
 	for (i = unmap_ctx->range_index; i < nr; i++) {
-		lba = dsm_range[i].starting_lba;
+		struct spdk_nvme_dsm_range dsm_range = { 0 };
-		lba_count = dsm_range[i].length;
+
+		spdk_iov_xfer_to_buf(&ix, &dsm_range, sizeof(dsm_range));
+
+		lba = dsm_range.starting_lba;
+		lba_count = dsm_range.length;
 
 		unmap_ctx->count++;
 
@@ -667,7 +672,8 @@ nvmf_bdev_ctrlr_copy_cmd(struct spdk_bdev *bdev, struct spdk_bdev_desc *desc,
 	struct spdk_nvme_cmd *cmd = &req->cmd->nvme_cmd;
 	struct spdk_nvme_cpl *response = &req->rsp->nvme_cpl;
 	uint64_t sdlba = ((uint64_t)cmd->cdw11 << 32) + cmd->cdw10;
-	struct spdk_nvme_scc_source_range *range;
+	struct spdk_nvme_scc_source_range range = { 0 };
+	struct spdk_iov_xfer ix;
 	int rc;
 
 	SPDK_DEBUGLOG(nvmf, "Copy command: SDLBA %lu, NR %u, desc format %u, PRINFOR %u, "
@@ -696,7 +702,10 @@ nvmf_bdev_ctrlr_copy_cmd(struct spdk_bdev *bdev, struct spdk_bdev_desc *desc,
 		return SPDK_NVMF_REQUEST_EXEC_STATUS_COMPLETE;
 	}
 
-	/* We support only one source range */
+	/*
+	 * We support only one source range, and rely on this with the xfer
+	 * below.
+	 */
 	if (cmd->cdw12_bits.copy.nr > 0) {
 		response->status.sct = SPDK_NVME_SCT_COMMAND_SPECIFIC;
 		response->status.sc = SPDK_NVME_SC_CMD_SIZE_LIMIT_SIZE_EXCEEDED;
@@ -709,8 +718,10 @@ nvmf_bdev_ctrlr_copy_cmd(struct spdk_bdev *bdev, struct spdk_bdev_desc *desc,
 		return SPDK_NVMF_REQUEST_EXEC_STATUS_COMPLETE;
 	}
 
-	range = req->data;
+	spdk_iov_xfer_init(&ix, req->iov, req->iovcnt);
-	rc = spdk_bdev_copy_blocks(desc, ch, sdlba, range->slba, range->nlb + 1,
+	spdk_iov_xfer_to_buf(&ix, &range, sizeof(range));
+
+	rc = spdk_bdev_copy_blocks(desc, ch, sdlba, range.slba, range.nlb + 1,
 				   nvmf_bdev_ctrlr_complete_cmd, req);
 	if (spdk_unlikely(rc)) {
 		if (rc == -ENOMEM) {

lib/util/iov.c

@@ -143,32 +143,80 @@ spdk_iovmove(struct iovec *siov, size_t siovcnt, struct iovec *diov, size_t diov
 	return total_sz;
 }
 
+void
+spdk_iov_xfer_init(struct spdk_iov_xfer *ix, struct iovec *iovs, int iovcnt)
+{
+	ix->iovs = iovs;
+	ix->iovcnt = iovcnt;
+	ix->cur_iov_idx = 0;
+	ix->cur_iov_offset = 0;
+}
+
+static size_t
+iov_xfer(struct spdk_iov_xfer *ix, const void *buf, size_t buf_len, bool to_buf)
+{
+	size_t len, iov_remain_len, copied_len = 0;
+	struct iovec *iov;
+
+	if (buf_len == 0) {
+		return 0;
+	}
+
+	while (ix->cur_iov_idx < ix->iovcnt) {
+		iov = &ix->iovs[ix->cur_iov_idx];
+		iov_remain_len = iov->iov_len - ix->cur_iov_offset;
+		if (iov_remain_len == 0) {
+			ix->cur_iov_idx++;
+			ix->cur_iov_offset = 0;
+			continue;
+		}
+
+		len = spdk_min(iov_remain_len, buf_len - copied_len);
+
+		if (to_buf) {
+			memcpy((char *)buf + copied_len,
+			       iov->iov_base + ix->cur_iov_offset, len);
+		} else {
+			memcpy((char *)iov->iov_base + ix->cur_iov_offset,
+			       (const char *)buf + copied_len, len);
+		}
+		copied_len += len;
+		ix->cur_iov_offset += len;
+
+		if (buf_len == copied_len) {
+			return copied_len;
+		}
+	}
+
+	return copied_len;
+}
+
+size_t
+spdk_iov_xfer_from_buf(struct spdk_iov_xfer *ix, const void *buf, size_t buf_len)
+{
+	return iov_xfer(ix, buf, buf_len, false);
+}
+
+size_t
+spdk_iov_xfer_to_buf(struct spdk_iov_xfer *ix, const void *buf, size_t buf_len)
+{
+	return iov_xfer(ix, buf, buf_len, true);
+}
+
 void
 spdk_copy_iovs_to_buf(void *buf, size_t buf_len, struct iovec *iovs, int iovcnt)
 {
-	int i;
+	struct spdk_iov_xfer ix;
-	size_t len;
 
-	for (i = 0; i < iovcnt; i++) {
+	spdk_iov_xfer_init(&ix, iovs, iovcnt);
-		len = spdk_min(iovs[i].iov_len, buf_len);
+	spdk_iov_xfer_to_buf(&ix, buf, buf_len);
-		memcpy(buf, iovs[i].iov_base, len);
-		buf += len;
-		assert(buf_len >= len);
-		buf_len -= len;
-	}
 }
 
 void
 spdk_copy_buf_to_iovs(struct iovec *iovs, int iovcnt, void *buf, size_t buf_len)
 {
-	int i;
+	struct spdk_iov_xfer ix;
-	size_t len;
 
-	for (i = 0; i < iovcnt; i++) {
+	spdk_iov_xfer_init(&ix, iovs, iovcnt);
-		len = spdk_min(iovs[i].iov_len, buf_len);
+	spdk_iov_xfer_from_buf(&ix, buf, buf_len);
-		memcpy(iovs[i].iov_base, buf, len);
-		buf += len;
-		assert(buf_len >= len);
-		buf_len -= len;
-	}
 }

lib/util/spdk_util.map

@@ -137,6 +137,9 @@
 	spdk_ioviter_next;
 	spdk_iov_memset;
 	spdk_iov_one;
+	spdk_iov_xfer_init;
+	spdk_iov_xfer_from_buf;
+	spdk_iov_xfer_to_buf;
 	spdk_copy_iovs_to_buf;
 	spdk_copy_buf_to_iovs;
 	spdk_memset_s;

test/unit/lib/util/iov.c/iov_ut.c

@@ -281,6 +281,52 @@ test_iov_one(void)
 	CU_ASSERT(iovcnt == 1);
 }
 
+static void
+test_iov_xfer(void)
+{
+	struct spdk_iov_xfer ix;
+	uint8_t data[64] = { 0 };
+	uint8_t iov_buffer[64];
+	struct iovec iov[4];
+	size_t i;
+
+	for (i = 0; i < sizeof(iov_buffer); i++) {
+		iov_buffer[i] = i;
+	}
+
+	iov[0].iov_base = iov_buffer;
+	iov[0].iov_len = 5;
+	iov[1].iov_base = iov[0].iov_base + iov[0].iov_len;
+	iov[1].iov_len = 15;
+	iov[2].iov_base = iov[1].iov_base + iov[1].iov_len;
+	iov[2].iov_len = 21;
+	iov[3].iov_base = iov[2].iov_base + iov[2].iov_len;
+	iov[3].iov_len = 23;
+
+	spdk_iov_xfer_init(&ix, iov, 4);
+
+	spdk_iov_xfer_to_buf(&ix, data, 8);
+	spdk_iov_xfer_to_buf(&ix, data + 8, 56);
+
+	for (i = 0; i < sizeof(data); i++) {
+		CU_ASSERT(data[i] == i);
+	}
+
+	for (i = 0; i < sizeof(data); i++) {
+		data[i] = sizeof(data) - i;
+	}
+
+	spdk_iov_xfer_init(&ix, iov, 4);
+
+	spdk_iov_xfer_from_buf(&ix, data, 5);
+	spdk_iov_xfer_from_buf(&ix, data + 5, 3);
+	spdk_iov_xfer_from_buf(&ix, data + 8, 56);
+
+	for (i = 0; i < sizeof(iov_buffer); i++) {
+		CU_ASSERT(iov_buffer[i] == sizeof(iov_buffer) - i);
+	}
+}
+
 int
 main(int argc, char **argv)
 {
@@ -299,6 +345,7 @@ main(int argc, char **argv)
 	CU_ADD_TEST(suite, test_buf_to_iovs);
 	CU_ADD_TEST(suite, test_memset);
 	CU_ADD_TEST(suite, test_iov_one);
+	CU_ADD_TEST(suite, test_iov_xfer);
 
 	CU_basic_set_mode(CU_BRM_VERBOSE);