drivers/scsi/ibmvscsi_tgt/libsrp.c - linux - Git at Google

 /*******************************************************************************
  * SCSI RDMA Protocol lib functions
  *
  * Copyright (C) 2006 FUJITA Tomonori <tomof@acm.org>
  * Copyright (C) 2016 Bryant G. Ly <bryantly@linux.vnet.ibm.com> IBM Corp.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  ***********************************************************************/

 #define pr_fmt(fmt)	"libsrp: " fmt

 #include <linux/printk.h>
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/kfifo.h>
 #include <linux/scatterlist.h>
 #include <linux/dma-mapping.h>
 #include <linux/module.h>
 #include <scsi/srp.h>
 #include <target/target_core_base.h>
 #include "libsrp.h"
 #include "ibmvscsi_tgt.h"

 static int srp_iu_pool_alloc(struct srp_queue *q, size_t max,
 			     struct srp_buf **ring)
 {
 	struct iu_entry *iue;
 	int i;

 	q->pool = kcalloc(max, sizeof(struct iu_entry *), GFP_KERNEL);
 	if (!q->pool)
 		return -ENOMEM;
 	q->items = kcalloc(max, sizeof(struct iu_entry), GFP_KERNEL);
 	if (!q->items)
 		goto free_pool;

 	spin_lock_init(&q->lock);
 	kfifo_init(&q->queue, (void *)q->pool, max * sizeof(void *));

 	for (i = 0, iue = q->items; i < max; i++) {
 		kfifo_in(&q->queue, (void *)&iue, sizeof(void *));
 		iue->sbuf = ring[i];
 		iue++;
 	}
 	return 0;

 free_pool:
 	kfree(q->pool);
 	return -ENOMEM;
 }

 static void srp_iu_pool_free(struct srp_queue *q)
 {
 	kfree(q->items);
 	kfree(q->pool);
 }

 static struct srp_buf **srp_ring_alloc(struct device *dev,
 				       size_t max, size_t size)
 {
 	struct srp_buf **ring;
 	int i;

 	ring = kcalloc(max, sizeof(struct srp_buf *), GFP_KERNEL);
 	if (!ring)
 		return NULL;

 	for (i = 0; i < max; i++) {
 		ring[i] = kzalloc(sizeof(*ring[i]), GFP_KERNEL);
 		if (!ring[i])
 			goto out;
 		ring[i]->buf = dma_alloc_coherent(dev, size, &ring[i]->dma,
 						  GFP_KERNEL);
 		if (!ring[i]->buf)
 			goto out;
 	}
 	return ring;

 out:
 	for (i = 0; i < max && ring[i]; i++) {
 		if (ring[i]->buf) {
 			dma_free_coherent(dev, size, ring[i]->buf,
 					  ring[i]->dma);
 		}
 		kfree(ring[i]);
 	}
 	kfree(ring);

 	return NULL;
 }

 static void srp_ring_free(struct device *dev, struct srp_buf **ring,
 			  size_t max, size_t size)
 {
 	int i;

 	for (i = 0; i < max; i++) {
 		dma_free_coherent(dev, size, ring[i]->buf, ring[i]->dma);
 		kfree(ring[i]);
 	}
 	kfree(ring);
 }

 int srp_target_alloc(struct srp_target *target, struct device *dev,
 		     size_t nr, size_t iu_size)
 {
 	int err;

 	spin_lock_init(&target->lock);

 	target->dev = dev;

 	target->srp_iu_size = iu_size;
 	target->rx_ring_size = nr;
 	target->rx_ring = srp_ring_alloc(target->dev, nr, iu_size);
 	if (!target->rx_ring)
 		return -ENOMEM;
 	err = srp_iu_pool_alloc(&target->iu_queue, nr, target->rx_ring);
 	if (err)
 		goto free_ring;

 	dev_set_drvdata(target->dev, target);
 	return 0;

 free_ring:
 	srp_ring_free(target->dev, target->rx_ring, nr, iu_size);
 	return -ENOMEM;
 }

 void srp_target_free(struct srp_target *target)
 {
 	dev_set_drvdata(target->dev, NULL);
 	srp_ring_free(target->dev, target->rx_ring, target->rx_ring_size,
 		      target->srp_iu_size);
 	srp_iu_pool_free(&target->iu_queue);
 }

 struct iu_entry *srp_iu_get(struct srp_target *target)
 {
 	struct iu_entry *iue = NULL;

 	if (kfifo_out_locked(&target->iu_queue.queue, (void *)&iue,
 			     sizeof(void *),
 			     &target->iu_queue.lock) != sizeof(void *)) {
 		WARN_ONCE(1, "unexpected fifo state");
 		return NULL;
 	}
 	if (!iue)
 		return iue;
 	iue->target = target;
 	iue->flags = 0;
 	return iue;
 }

 void srp_iu_put(struct iu_entry *iue)
 {
 	kfifo_in_locked(&iue->target->iu_queue.queue, (void *)&iue,
 			sizeof(void *), &iue->target->iu_queue.lock);
 }

 static int srp_direct_data(struct ibmvscsis_cmd *cmd, struct srp_direct_buf *md,
 			   enum dma_data_direction dir, srp_rdma_t rdma_io,
 			   int dma_map, int ext_desc)
 {
 	struct iu_entry *iue = NULL;
 	struct scatterlist *sg = NULL;
 	int err, nsg = 0, len;

 	if (dma_map) {
 		iue = cmd->iue;
 		sg = cmd->se_cmd.t_data_sg;
 		nsg = dma_map_sg(iue->target->dev, sg, cmd->se_cmd.t_data_nents,
 				 DMA_BIDIRECTIONAL);
 		if (!nsg) {
 			pr_err("fail to map %p %d\n", iue,
 			       cmd->se_cmd.t_data_nents);
 			return 0;
 		}
 		len = min(cmd->se_cmd.data_length, be32_to_cpu(md->len));
 	} else {
 		len = be32_to_cpu(md->len);
 	}

 	err = rdma_io(cmd, sg, nsg, md, 1, dir, len);

 	if (dma_map)
 		dma_unmap_sg(iue->target->dev, sg, nsg, DMA_BIDIRECTIONAL);

 	return err;
 }

 static int srp_indirect_data(struct ibmvscsis_cmd *cmd, struct srp_cmd *srp_cmd,
 			     struct srp_indirect_buf *id,
 			     enum dma_data_direction dir, srp_rdma_t rdma_io,
 			     int dma_map, int ext_desc)
 {
 	struct iu_entry *iue = NULL;
 	struct srp_direct_buf *md = NULL;
 	struct scatterlist dummy, *sg = NULL;
 	dma_addr_t token = 0;
 	int err = 0;
 	int nmd, nsg = 0, len;

 	if (dma_map || ext_desc) {
 		iue = cmd->iue;
 		sg = cmd->se_cmd.t_data_sg;
 	}

 	nmd = be32_to_cpu(id->table_desc.len) / sizeof(struct srp_direct_buf);

 	if ((dir == DMA_FROM_DEVICE && nmd == srp_cmd->data_in_desc_cnt) ||
 	    (dir == DMA_TO_DEVICE && nmd == srp_cmd->data_out_desc_cnt)) {
 		md = &id->desc_list[0];
 		goto rdma;
 	}

 	if (ext_desc && dma_map) {
 		md = dma_alloc_coherent(iue->target->dev,
 					be32_to_cpu(id->table_desc.len),
 					&token, GFP_KERNEL);
 		if (!md) {
 			pr_err("Can't get dma memory %u\n",
 			       be32_to_cpu(id->table_desc.len));
 			return -ENOMEM;
 		}

 		sg_init_one(&dummy, md, be32_to_cpu(id->table_desc.len));
 		sg_dma_address(&dummy) = token;
 		sg_dma_len(&dummy) = be32_to_cpu(id->table_desc.len);
 		err = rdma_io(cmd, &dummy, 1, &id->table_desc, 1, DMA_TO_DEVICE,
 			      be32_to_cpu(id->table_desc.len));
 		if (err) {
 			pr_err("Error copying indirect table %d\n", err);
 			goto free_mem;
 		}
 	} else {
 		pr_err("This command uses external indirect buffer\n");
 		return -EINVAL;
 	}

 rdma:
 	if (dma_map) {
 		nsg = dma_map_sg(iue->target->dev, sg, cmd->se_cmd.t_data_nents,
 				 DMA_BIDIRECTIONAL);
 		if (!nsg) {
 			pr_err("fail to map %p %d\n", iue,
 			       cmd->se_cmd.t_data_nents);
 			err = -EIO;
 			goto free_mem;
 		}
 		len = min(cmd->se_cmd.data_length, be32_to_cpu(id->len));
 	} else {
 		len = be32_to_cpu(id->len);
 	}

 	err = rdma_io(cmd, sg, nsg, md, nmd, dir, len);

 	if (dma_map)
 		dma_unmap_sg(iue->target->dev, sg, nsg, DMA_BIDIRECTIONAL);

 free_mem:
 	if (token && dma_map) {
 		dma_free_coherent(iue->target->dev,
 				  be32_to_cpu(id->table_desc.len), md, token);
 	}
 	return err;
 }

 static int data_out_desc_size(struct srp_cmd *cmd)
 {
 	int size = 0;
 	u8 fmt = cmd->buf_fmt >> 4;

 	switch (fmt) {
 	case SRP_NO_DATA_DESC:
 		break;
 	case SRP_DATA_DESC_DIRECT:
 		size = sizeof(struct srp_direct_buf);
 		break;
 	case SRP_DATA_DESC_INDIRECT:
 		size = sizeof(struct srp_indirect_buf) +
 			sizeof(struct srp_direct_buf) * cmd->data_out_desc_cnt;
 		break;
 	default:
 		pr_err("client error. Invalid data_out_format %x\n", fmt);
 		break;
 	}
 	return size;
 }

 /*
  * TODO: this can be called multiple times for a single command if it
  * has very long data.
  */
 int srp_transfer_data(struct ibmvscsis_cmd *cmd, struct srp_cmd *srp_cmd,
 		      srp_rdma_t rdma_io, int dma_map, int ext_desc)
 {
 	struct srp_direct_buf *md;
 	struct srp_indirect_buf *id;
 	enum dma_data_direction dir;
 	int offset, err = 0;
 	u8 format;

 	if (!cmd->se_cmd.t_data_nents)
 		return 0;

 	offset = srp_cmd->add_cdb_len & ~3;

 	dir = srp_cmd_direction(srp_cmd);
 	if (dir == DMA_FROM_DEVICE)
 		offset += data_out_desc_size(srp_cmd);

 	if (dir == DMA_TO_DEVICE)
 		format = srp_cmd->buf_fmt >> 4;
 	else
 		format = srp_cmd->buf_fmt & ((1U << 4) - 1);

 	switch (format) {
 	case SRP_NO_DATA_DESC:
 		break;
 	case SRP_DATA_DESC_DIRECT:
 		md = (struct srp_direct_buf *)(srp_cmd->add_data + offset);
 		err = srp_direct_data(cmd, md, dir, rdma_io, dma_map, ext_desc);
 		break;
 	case SRP_DATA_DESC_INDIRECT:
 		id = (struct srp_indirect_buf *)(srp_cmd->add_data + offset);
 		err = srp_indirect_data(cmd, srp_cmd, id, dir, rdma_io, dma_map,
 					ext_desc);
 		break;
 	default:
 		pr_err("Unknown format %d %x\n", dir, format);
 		err = -EINVAL;
 	}

 	return err;
 }

 u64 srp_data_length(struct srp_cmd *cmd, enum dma_data_direction dir)
 {
 	struct srp_direct_buf *md;
 	struct srp_indirect_buf *id;
 	u64 len = 0;
 	uint offset = cmd->add_cdb_len & ~3;
 	u8 fmt;

 	if (dir == DMA_TO_DEVICE) {
 		fmt = cmd->buf_fmt >> 4;
 	} else {
 		fmt = cmd->buf_fmt & ((1U << 4) - 1);
 		offset += data_out_desc_size(cmd);
 	}

 	switch (fmt) {
 	case SRP_NO_DATA_DESC:
 		break;
 	case SRP_DATA_DESC_DIRECT:
 		md = (struct srp_direct_buf *)(cmd->add_data + offset);
 		len = be32_to_cpu(md->len);
 		break;
 	case SRP_DATA_DESC_INDIRECT:
 		id = (struct srp_indirect_buf *)(cmd->add_data + offset);
 		len = be32_to_cpu(id->len);
 		break;
 	default:
 		pr_err("invalid data format %x\n", fmt);
 		break;
 	}
 	return len;
 }

 int srp_get_desc_table(struct srp_cmd *srp_cmd, enum dma_data_direction *dir,
 		       u64 *data_len)
 {
 	struct srp_indirect_buf *idb;
 	struct srp_direct_buf *db;
 	uint add_cdb_offset;
 	int rc;

 	/*
 	 * The pointer computations below will only be compiled correctly
 	 * if srp_cmd::add_data is declared as s8*, u8*, s8[] or u8[], so check
 	 * whether srp_cmd::add_data has been declared as a byte pointer.
 	 */
 	BUILD_BUG_ON(!__same_type(srp_cmd->add_data[0], (s8)0)
 		     && !__same_type(srp_cmd->add_data[0], (u8)0));

 	BUG_ON(!dir);
 	BUG_ON(!data_len);

 	rc = 0;
 	*data_len = 0;

 	*dir = DMA_NONE;

 	if (srp_cmd->buf_fmt & 0xf)
 		*dir = DMA_FROM_DEVICE;
 	else if (srp_cmd->buf_fmt >> 4)
 		*dir = DMA_TO_DEVICE;

 	add_cdb_offset = srp_cmd->add_cdb_len & ~3;
 	if (((srp_cmd->buf_fmt & 0xf) == SRP_DATA_DESC_DIRECT) ||
 	    ((srp_cmd->buf_fmt >> 4) == SRP_DATA_DESC_DIRECT)) {
 		db = (struct srp_direct_buf *)(srp_cmd->add_data
 					       + add_cdb_offset);
 		*data_len = be32_to_cpu(db->len);
 	} else if (((srp_cmd->buf_fmt & 0xf) == SRP_DATA_DESC_INDIRECT) ||
 		   ((srp_cmd->buf_fmt >> 4) == SRP_DATA_DESC_INDIRECT)) {
 		idb = (struct srp_indirect_buf *)(srp_cmd->add_data
 						  + add_cdb_offset);

 		*data_len = be32_to_cpu(idb->len);
 	}
 	return rc;
 }

 MODULE_DESCRIPTION("SCSI RDMA Protocol lib functions");
 MODULE_AUTHOR("FUJITA Tomonori");
 MODULE_LICENSE("GPL");
	/*******************************************************************************
	* SCSI RDMA Protocol lib functions
	*
	* Copyright (C) 2006 FUJITA Tomonori <tomof@acm.org>
	* Copyright (C) 2016 Bryant G. Ly <bryantly@linux.vnet.ibm.com> IBM Corp.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	***********************************************************************/

	#define pr_fmt(fmt) "libsrp: " fmt

	#include <linux/printk.h>
	#include <linux/err.h>
	#include <linux/slab.h>
	#include <linux/kfifo.h>
	#include <linux/scatterlist.h>
	#include <linux/dma-mapping.h>
	#include <linux/module.h>
	#include <scsi/srp.h>
	#include <target/target_core_base.h>
	#include "libsrp.h"
	#include "ibmvscsi_tgt.h"

	static int srp_iu_pool_alloc(struct srp_queue *q, size_t max,
	struct srp_buf **ring)
	{
	struct iu_entry *iue;
	int i;

	q->pool = kcalloc(max, sizeof(struct iu_entry *), GFP_KERNEL);
	if (!q->pool)
	return -ENOMEM;
	q->items = kcalloc(max, sizeof(struct iu_entry), GFP_KERNEL);
	if (!q->items)
	goto free_pool;

	spin_lock_init(&q->lock);
	kfifo_init(&q->queue, (void )q->pool, max sizeof(void *));

	for (i = 0, iue = q->items; i < max; i++) {
	kfifo_in(&q->queue, (void )&iue, sizeof(void ));
	iue->sbuf = ring[i];
	iue++;
	}
	return 0;

	free_pool:
	kfree(q->pool);
	return -ENOMEM;
	}

	static void srp_iu_pool_free(struct srp_queue *q)
	{
	kfree(q->items);
	kfree(q->pool);
	}

	static struct srp_buf *srp_ring_alloc(struct device dev,
	size_t max, size_t size)
	{
	struct srp_buf **ring;
	int i;

	ring = kcalloc(max, sizeof(struct srp_buf *), GFP_KERNEL);
	if (!ring)
	return NULL;

	for (i = 0; i < max; i++) {
	ring[i] = kzalloc(sizeof(*ring[i]), GFP_KERNEL);
	if (!ring[i])
	goto out;
	ring[i]->buf = dma_alloc_coherent(dev, size, &ring[i]->dma,
	GFP_KERNEL);
	if (!ring[i]->buf)
	goto out;
	}
	return ring;

	out:
	for (i = 0; i < max && ring[i]; i++) {
	if (ring[i]->buf) {
	dma_free_coherent(dev, size, ring[i]->buf,
	ring[i]->dma);
	}
	kfree(ring[i]);
	}
	kfree(ring);

	return NULL;
	}

	static void srp_ring_free(struct device dev, struct srp_buf *ring,
	size_t max, size_t size)
	{
	int i;

	for (i = 0; i < max; i++) {
	dma_free_coherent(dev, size, ring[i]->buf, ring[i]->dma);
	kfree(ring[i]);
	}
	kfree(ring);
	}

	int srp_target_alloc(struct srp_target target, struct device dev,
	size_t nr, size_t iu_size)
	{
	int err;

	spin_lock_init(&target->lock);

	target->dev = dev;

	target->srp_iu_size = iu_size;
	target->rx_ring_size = nr;
	target->rx_ring = srp_ring_alloc(target->dev, nr, iu_size);
	if (!target->rx_ring)
	return -ENOMEM;
	err = srp_iu_pool_alloc(&target->iu_queue, nr, target->rx_ring);
	if (err)
	goto free_ring;

	dev_set_drvdata(target->dev, target);
	return 0;

	free_ring:
	srp_ring_free(target->dev, target->rx_ring, nr, iu_size);
	return -ENOMEM;
	}

	void srp_target_free(struct srp_target *target)
	{
	dev_set_drvdata(target->dev, NULL);
	srp_ring_free(target->dev, target->rx_ring, target->rx_ring_size,
	target->srp_iu_size);
	srp_iu_pool_free(&target->iu_queue);
	}

	struct iu_entry srp_iu_get(struct srp_target target)
	{
	struct iu_entry *iue = NULL;

	if (kfifo_out_locked(&target->iu_queue.queue, (void *)&iue,
	sizeof(void *),
	&target->iu_queue.lock) != sizeof(void *)) {
	WARN_ONCE(1, "unexpected fifo state");
	return NULL;
	}
	if (!iue)
	return iue;
	iue->target = target;
	iue->flags = 0;
	return iue;
	}

	void srp_iu_put(struct iu_entry *iue)
	{
	kfifo_in_locked(&iue->target->iu_queue.queue, (void *)&iue,
	sizeof(void *), &iue->target->iu_queue.lock);
	}

	static int srp_direct_data(struct ibmvscsis_cmd cmd, struct srp_direct_buf md,
	enum dma_data_direction dir, srp_rdma_t rdma_io,
	int dma_map, int ext_desc)
	{
	struct iu_entry *iue = NULL;
	struct scatterlist *sg = NULL;
	int err, nsg = 0, len;

	if (dma_map) {
	iue = cmd->iue;
	sg = cmd->se_cmd.t_data_sg;
	nsg = dma_map_sg(iue->target->dev, sg, cmd->se_cmd.t_data_nents,
	DMA_BIDIRECTIONAL);
	if (!nsg) {
	pr_err("fail to map %p %d\n", iue,
	cmd->se_cmd.t_data_nents);
	return 0;
	}
	len = min(cmd->se_cmd.data_length, be32_to_cpu(md->len));
	} else {
	len = be32_to_cpu(md->len);
	}

	err = rdma_io(cmd, sg, nsg, md, 1, dir, len);

	if (dma_map)
	dma_unmap_sg(iue->target->dev, sg, nsg, DMA_BIDIRECTIONAL);

	return err;
	}

	static int srp_indirect_data(struct ibmvscsis_cmd cmd, struct srp_cmd srp_cmd,
	struct srp_indirect_buf *id,
	enum dma_data_direction dir, srp_rdma_t rdma_io,
	int dma_map, int ext_desc)
	{
	struct iu_entry *iue = NULL;
	struct srp_direct_buf *md = NULL;
	struct scatterlist dummy, *sg = NULL;
	dma_addr_t token = 0;
	int err = 0;
	int nmd, nsg = 0, len;

	if (dma_map \|\| ext_desc) {
	iue = cmd->iue;
	sg = cmd->se_cmd.t_data_sg;
	}

	nmd = be32_to_cpu(id->table_desc.len) / sizeof(struct srp_direct_buf);

	if ((dir == DMA_FROM_DEVICE && nmd == srp_cmd->data_in_desc_cnt) \|\|
	(dir == DMA_TO_DEVICE && nmd == srp_cmd->data_out_desc_cnt)) {
	md = &id->desc_list[0];
	goto rdma;
	}

	if (ext_desc && dma_map) {
	md = dma_alloc_coherent(iue->target->dev,
	be32_to_cpu(id->table_desc.len),
	&token, GFP_KERNEL);
	if (!md) {
	pr_err("Can't get dma memory %u\n",
	be32_to_cpu(id->table_desc.len));
	return -ENOMEM;
	}

	sg_init_one(&dummy, md, be32_to_cpu(id->table_desc.len));
	sg_dma_address(&dummy) = token;
	sg_dma_len(&dummy) = be32_to_cpu(id->table_desc.len);
	err = rdma_io(cmd, &dummy, 1, &id->table_desc, 1, DMA_TO_DEVICE,
	be32_to_cpu(id->table_desc.len));
	if (err) {
	pr_err("Error copying indirect table %d\n", err);
	goto free_mem;
	}
	} else {
	pr_err("This command uses external indirect buffer\n");
	return -EINVAL;
	}

	rdma:
	if (dma_map) {
	nsg = dma_map_sg(iue->target->dev, sg, cmd->se_cmd.t_data_nents,
	DMA_BIDIRECTIONAL);
	if (!nsg) {
	pr_err("fail to map %p %d\n", iue,
	cmd->se_cmd.t_data_nents);
	err = -EIO;
	goto free_mem;
	}
	len = min(cmd->se_cmd.data_length, be32_to_cpu(id->len));
	} else {
	len = be32_to_cpu(id->len);
	}

	err = rdma_io(cmd, sg, nsg, md, nmd, dir, len);

	if (dma_map)
	dma_unmap_sg(iue->target->dev, sg, nsg, DMA_BIDIRECTIONAL);

	free_mem:
	if (token && dma_map) {
	dma_free_coherent(iue->target->dev,
	be32_to_cpu(id->table_desc.len), md, token);
	}
	return err;
	}

	static int data_out_desc_size(struct srp_cmd *cmd)
	{
	int size = 0;
	u8 fmt = cmd->buf_fmt >> 4;

	switch (fmt) {
	case SRP_NO_DATA_DESC:
	break;
	case SRP_DATA_DESC_DIRECT:
	size = sizeof(struct srp_direct_buf);
	break;
	case SRP_DATA_DESC_INDIRECT:
	size = sizeof(struct srp_indirect_buf) +
	sizeof(struct srp_direct_buf) * cmd->data_out_desc_cnt;
	break;
	default:
	pr_err("client error. Invalid data_out_format %x\n", fmt);
	break;
	}
	return size;
	}

	/*
	* TODO: this can be called multiple times for a single command if it
	* has very long data.
	*/
	int srp_transfer_data(struct ibmvscsis_cmd cmd, struct srp_cmd srp_cmd,
	srp_rdma_t rdma_io, int dma_map, int ext_desc)
	{
	struct srp_direct_buf *md;
	struct srp_indirect_buf *id;
	enum dma_data_direction dir;
	int offset, err = 0;
	u8 format;

	if (!cmd->se_cmd.t_data_nents)
	return 0;

	offset = srp_cmd->add_cdb_len & ~3;

	dir = srp_cmd_direction(srp_cmd);
	if (dir == DMA_FROM_DEVICE)
	offset += data_out_desc_size(srp_cmd);

	if (dir == DMA_TO_DEVICE)
	format = srp_cmd->buf_fmt >> 4;
	else
	format = srp_cmd->buf_fmt & ((1U << 4) - 1);

	switch (format) {
	case SRP_NO_DATA_DESC:
	break;
	case SRP_DATA_DESC_DIRECT:
	md = (struct srp_direct_buf *)(srp_cmd->add_data + offset);
	err = srp_direct_data(cmd, md, dir, rdma_io, dma_map, ext_desc);
	break;
	case SRP_DATA_DESC_INDIRECT:
	id = (struct srp_indirect_buf *)(srp_cmd->add_data + offset);
	err = srp_indirect_data(cmd, srp_cmd, id, dir, rdma_io, dma_map,
	ext_desc);
	break;
	default:
	pr_err("Unknown format %d %x\n", dir, format);
	err = -EINVAL;
	}

	return err;
	}

	u64 srp_data_length(struct srp_cmd *cmd, enum dma_data_direction dir)
	{
	struct srp_direct_buf *md;
	struct srp_indirect_buf *id;
	u64 len = 0;
	uint offset = cmd->add_cdb_len & ~3;
	u8 fmt;

	if (dir == DMA_TO_DEVICE) {
	fmt = cmd->buf_fmt >> 4;
	} else {
	fmt = cmd->buf_fmt & ((1U << 4) - 1);
	offset += data_out_desc_size(cmd);
	}

	switch (fmt) {
	case SRP_NO_DATA_DESC:
	break;
	case SRP_DATA_DESC_DIRECT:
	md = (struct srp_direct_buf *)(cmd->add_data + offset);
	len = be32_to_cpu(md->len);
	break;
	case SRP_DATA_DESC_INDIRECT:
	id = (struct srp_indirect_buf *)(cmd->add_data + offset);
	len = be32_to_cpu(id->len);
	break;
	default:
	pr_err("invalid data format %x\n", fmt);
	break;
	}
	return len;
	}

	int srp_get_desc_table(struct srp_cmd srp_cmd, enum dma_data_direction dir,
	u64 *data_len)
	{
	struct srp_indirect_buf *idb;
	struct srp_direct_buf *db;
	uint add_cdb_offset;
	int rc;

	/*
	* The pointer computations below will only be compiled correctly
	* if srp_cmd::add_data is declared as s8, u8, s8[] or u8[], so check
	* whether srp_cmd::add_data has been declared as a byte pointer.
	*/
	BUILD_BUG_ON(!__same_type(srp_cmd->add_data[0], (s8)0)
	&& !__same_type(srp_cmd->add_data[0], (u8)0));

	BUG_ON(!dir);
	BUG_ON(!data_len);

	rc = 0;
	*data_len = 0;

	*dir = DMA_NONE;

	if (srp_cmd->buf_fmt & 0xf)
	*dir = DMA_FROM_DEVICE;
	else if (srp_cmd->buf_fmt >> 4)
	*dir = DMA_TO_DEVICE;

	add_cdb_offset = srp_cmd->add_cdb_len & ~3;
	if (((srp_cmd->buf_fmt & 0xf) == SRP_DATA_DESC_DIRECT) \|\|
	((srp_cmd->buf_fmt >> 4) == SRP_DATA_DESC_DIRECT)) {
	db = (struct srp_direct_buf *)(srp_cmd->add_data
	+ add_cdb_offset);
	*data_len = be32_to_cpu(db->len);
	} else if (((srp_cmd->buf_fmt & 0xf) == SRP_DATA_DESC_INDIRECT) \|\|
	((srp_cmd->buf_fmt >> 4) == SRP_DATA_DESC_INDIRECT)) {
	idb = (struct srp_indirect_buf *)(srp_cmd->add_data
	+ add_cdb_offset);

	*data_len = be32_to_cpu(idb->len);
	}
	return rc;
	}

	MODULE_DESCRIPTION("SCSI RDMA Protocol lib functions");
	MODULE_AUTHOR("FUJITA Tomonori");
	MODULE_LICENSE("GPL");