[linux-2.6-block.git] / drivers / target / target_core_rd.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*******************************************************************************
 * Filename:  target_core_rd.c
 *
 * This file contains the Storage Engine <-> Ramdisk transport
 * specific functions.
 *
 * (c) Copyright 2003-2013 Datera, Inc.
 *
 * Nicholas A. Bellinger <nab@kernel.org>
 *
 ******************************************************************************/

#include <linux/string.h>
#include <linux/parser.h>
#include <linux/highmem.h>
#include <linux/timer.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <scsi/scsi_proto.h>

#include <target/target_core_base.h>
#include <target/target_core_backend.h>

#include "target_core_rd.h"

static inline struct rd_dev *RD_DEV(struct se_device *dev)
{
	return container_of(dev, struct rd_dev, dev);
}

static int rd_attach_hba(struct se_hba *hba, u32 host_id)
{
	struct rd_host *rd_host;

	rd_host = kzalloc(sizeof(*rd_host), GFP_KERNEL);
	if (!rd_host)
		return -ENOMEM;

	rd_host->rd_host_id = host_id;

	hba->hba_ptr = rd_host;

	pr_debug("CORE_HBA[%d] - TCM Ramdisk HBA Driver %s on"
		" Generic Target Core Stack %s\n", hba->hba_id,
		RD_HBA_VERSION, TARGET_CORE_VERSION);

	return 0;
}

static void rd_detach_hba(struct se_hba *hba)
{
	struct rd_host *rd_host = hba->hba_ptr;

	pr_debug("CORE_HBA[%d] - Detached Ramdisk HBA: %u from"
		" Generic Target Core\n", hba->hba_id, rd_host->rd_host_id);

	kfree(rd_host);
	hba->hba_ptr = NULL;
}

static u32 rd_release_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *sg_table,
				 u32 sg_table_count)
{
	struct page *pg;
	struct scatterlist *sg;
	u32 i, j, page_count = 0, sg_per_table;

	for (i = 0; i < sg_table_count; i++) {
		sg = sg_table[i].sg_table;
		sg_per_table = sg_table[i].rd_sg_count;

		for (j = 0; j < sg_per_table; j++) {
			pg = sg_page(&sg[j]);
			if (pg) {
				__free_page(pg);
				page_count++;
			}
		}
		kfree(sg);
	}

	kfree(sg_table);
	return page_count;
}

static void rd_release_device_space(struct rd_dev *rd_dev)
{
	u32 page_count;

	if (!rd_dev->sg_table_array || !rd_dev->sg_table_count)
		return;

	page_count = rd_release_sgl_table(rd_dev, rd_dev->sg_table_array,
					  rd_dev->sg_table_count);

	pr_debug("CORE_RD[%u] - Released device space for Ramdisk"
		" Device ID: %u, pages %u in %u tables total bytes %lu\n",
		rd_dev->rd_host->rd_host_id, rd_dev->rd_dev_id, page_count,
		rd_dev->sg_table_count, (unsigned long)page_count * PAGE_SIZE);

	rd_dev->sg_table_array = NULL;
	rd_dev->sg_table_count = 0;
}


/*	rd_build_device_space():
 *
 *
 */
static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *sg_table,
				 u32 total_sg_needed, unsigned char init_payload)
{
	u32 i = 0, j, page_offset = 0, sg_per_table;
	u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
				sizeof(struct scatterlist));
	struct page *pg;
	struct scatterlist *sg;
	unsigned char *p;

	while (total_sg_needed) {
		unsigned int chain_entry = 0;

		sg_per_table = (total_sg_needed > max_sg_per_table) ?
			max_sg_per_table : total_sg_needed;

		/*
		 * Reserve extra element for chain entry
		 */
		if (sg_per_table < total_sg_needed)
			chain_entry = 1;

		sg = kmalloc_array(sg_per_table + chain_entry, sizeof(*sg),
				GFP_KERNEL);
		if (!sg)
			return -ENOMEM;

		sg_init_table(sg, sg_per_table + chain_entry);

		if (i > 0) {
			sg_chain(sg_table[i - 1].sg_table,
				 max_sg_per_table + 1, sg);
		}

		sg_table[i].sg_table = sg;
		sg_table[i].rd_sg_count = sg_per_table;
		sg_table[i].page_start_offset = page_offset;
		sg_table[i++].page_end_offset = (page_offset + sg_per_table)
						- 1;

		for (j = 0; j < sg_per_table; j++) {
			pg = alloc_pages(GFP_KERNEL, 0);
			if (!pg) {
				pr_err("Unable to allocate scatterlist"
					" pages for struct rd_dev_sg_table\n");
				return -ENOMEM;
			}
			sg_assign_page(&sg[j], pg);
			sg[j].length = PAGE_SIZE;

			p = kmap(pg);
			memset(p, init_payload, PAGE_SIZE);
			kunmap(pg);
		}

		page_offset += sg_per_table;
		total_sg_needed -= sg_per_table;
	}

	return 0;
}

static int rd_build_device_space(struct rd_dev *rd_dev)
{
	struct rd_dev_sg_table *sg_table;
	u32 sg_tables, total_sg_needed;
	u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
				sizeof(struct scatterlist));
	int rc;

	if (rd_dev->rd_page_count <= 0) {
		pr_err("Illegal page count: %u for Ramdisk device\n",
		       rd_dev->rd_page_count);
		return -EINVAL;
	}

	/* Don't need backing pages for NULLIO */
	if (rd_dev->rd_flags & RDF_NULLIO)
		return 0;

	total_sg_needed = rd_dev->rd_page_count;

	sg_tables = (total_sg_needed / max_sg_per_table) + 1;
	sg_table = kcalloc(sg_tables, sizeof(*sg_table), GFP_KERNEL);
	if (!sg_table)
		return -ENOMEM;

	rd_dev->sg_table_array = sg_table;
	rd_dev->sg_table_count = sg_tables;

	rc = rd_allocate_sgl_table(rd_dev, sg_table, total_sg_needed, 0x00);
	if (rc)
		return rc;

	pr_debug("CORE_RD[%u] - Built Ramdisk Device ID: %u space of"
		 " %u pages in %u tables\n", rd_dev->rd_host->rd_host_id,
		 rd_dev->rd_dev_id, rd_dev->rd_page_count,
		 rd_dev->sg_table_count);

	return 0;
}

static void rd_release_prot_space(struct rd_dev *rd_dev)
{
	u32 page_count;

	if (!rd_dev->sg_prot_array || !rd_dev->sg_prot_count)
		return;

	page_count = rd_release_sgl_table(rd_dev, rd_dev->sg_prot_array,
					  rd_dev->sg_prot_count);

	pr_debug("CORE_RD[%u] - Released protection space for Ramdisk"
		 " Device ID: %u, pages %u in %u tables total bytes %lu\n",
		 rd_dev->rd_host->rd_host_id, rd_dev->rd_dev_id, page_count,
		 rd_dev->sg_table_count, (unsigned long)page_count * PAGE_SIZE);

	rd_dev->sg_prot_array = NULL;
	rd_dev->sg_prot_count = 0;
}

static int rd_build_prot_space(struct rd_dev *rd_dev, int prot_length, int block_size)
{
	struct rd_dev_sg_table *sg_table;
	u32 total_sg_needed, sg_tables;
	u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
				sizeof(struct scatterlist));
	int rc;

	if (rd_dev->rd_flags & RDF_NULLIO)
		return 0;
	/*
	 * prot_length=8byte dif data
	 * tot sg needed = rd_page_count * (PGSZ/block_size) *
	 * 		   (prot_length/block_size) + pad
	 * PGSZ canceled each other.
	 */
	total_sg_needed = (rd_dev->rd_page_count * prot_length / block_size) + 1;

	sg_tables = (total_sg_needed / max_sg_per_table) + 1;
	sg_table = kcalloc(sg_tables, sizeof(*sg_table), GFP_KERNEL);
	if (!sg_table)
		return -ENOMEM;

	rd_dev->sg_prot_array = sg_table;
	rd_dev->sg_prot_count = sg_tables;

	rc = rd_allocate_sgl_table(rd_dev, sg_table, total_sg_needed, 0xff);
	if (rc)
		return rc;

	pr_debug("CORE_RD[%u] - Built Ramdisk Device ID: %u prot space of"
		 " %u pages in %u tables\n", rd_dev->rd_host->rd_host_id,
		 rd_dev->rd_dev_id, total_sg_needed, rd_dev->sg_prot_count);

	return 0;
}

static struct se_device *rd_alloc_device(struct se_hba *hba, const char *name)
{
	struct rd_dev *rd_dev;
	struct rd_host *rd_host = hba->hba_ptr;

	rd_dev = kzalloc(sizeof(*rd_dev), GFP_KERNEL);
	if (!rd_dev)
		return NULL;

	rd_dev->rd_host = rd_host;

	return &rd_dev->dev;
}

static int rd_configure_device(struct se_device *dev)
{
	struct rd_dev *rd_dev = RD_DEV(dev);
	struct rd_host *rd_host = dev->se_hba->hba_ptr;
	int ret;

	if (!(rd_dev->rd_flags & RDF_HAS_PAGE_COUNT)) {
		pr_debug("Missing rd_pages= parameter\n");
		return -EINVAL;
	}

	ret = rd_build_device_space(rd_dev);
	if (ret < 0)
		goto fail;

	dev->dev_attrib.hw_block_size = RD_BLOCKSIZE;
	dev->dev_attrib.hw_max_sectors = UINT_MAX;
	dev->dev_attrib.hw_queue_depth = RD_MAX_DEVICE_QUEUE_DEPTH;
	dev->dev_attrib.is_nonrot = 1;

	rd_dev->rd_dev_id = rd_host->rd_host_dev_id_count++;

	pr_debug("CORE_RD[%u] - Added TCM MEMCPY Ramdisk Device ID: %u of"
		" %u pages in %u tables, %lu total bytes\n",
		rd_host->rd_host_id, rd_dev->rd_dev_id, rd_dev->rd_page_count,
		rd_dev->sg_table_count,
		(unsigned long)(rd_dev->rd_page_count * PAGE_SIZE));

	return 0;

fail:
	rd_release_device_space(rd_dev);
	return ret;
}

static void rd_dev_call_rcu(struct rcu_head *p)
{
	struct se_device *dev = container_of(p, struct se_device, rcu_head);
	struct rd_dev *rd_dev = RD_DEV(dev);

	kfree(rd_dev);
}

static void rd_free_device(struct se_device *dev)
{
	call_rcu(&dev->rcu_head, rd_dev_call_rcu);
}

static void rd_destroy_device(struct se_device *dev)
{
	struct rd_dev *rd_dev = RD_DEV(dev);

	rd_release_device_space(rd_dev);
}

static struct rd_dev_sg_table *rd_get_sg_table(struct rd_dev *rd_dev, u32 page)
{
	struct rd_dev_sg_table *sg_table;
	u32 i, sg_per_table = (RD_MAX_ALLOCATION_SIZE /
				sizeof(struct scatterlist));

	i = page / sg_per_table;
	if (i < rd_dev->sg_table_count) {
		sg_table = &rd_dev->sg_table_array[i];
		if ((sg_table->page_start_offset <= page) &&
		    (sg_table->page_end_offset >= page))
			return sg_table;
	}

	pr_err("Unable to locate struct rd_dev_sg_table for page: %u\n",
			page);

	return NULL;
}

static struct rd_dev_sg_table *rd_get_prot_table(struct rd_dev *rd_dev, u32 page)
{
	struct rd_dev_sg_table *sg_table;
	u32 i, sg_per_table = (RD_MAX_ALLOCATION_SIZE /
				sizeof(struct scatterlist));

	i = page / sg_per_table;
	if (i < rd_dev->sg_prot_count) {
		sg_table = &rd_dev->sg_prot_array[i];
		if ((sg_table->page_start_offset <= page) &&
		     (sg_table->page_end_offset >= page))
			return sg_table;
	}

	pr_err("Unable to locate struct prot rd_dev_sg_table for page: %u\n",
			page);

	return NULL;
}

static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, bool is_read)
{
	struct se_device *se_dev = cmd->se_dev;
	struct rd_dev *dev = RD_DEV(se_dev);
	struct rd_dev_sg_table *prot_table;
	struct scatterlist *prot_sg;
	u32 sectors = cmd->data_length / se_dev->dev_attrib.block_size;
	u32 prot_offset, prot_page;
	u32 prot_npages __maybe_unused;
	u64 tmp;
	sense_reason_t rc = 0;

	tmp = cmd->t_task_lba * se_dev->prot_length;
	prot_offset = do_div(tmp, PAGE_SIZE);
	prot_page = tmp;

	prot_table = rd_get_prot_table(dev, prot_page);
	if (!prot_table)
		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

	prot_sg = &prot_table->sg_table[prot_page -
					prot_table->page_start_offset];

	if (se_dev->dev_attrib.pi_prot_verify) {
		if (is_read)
			rc = sbc_dif_verify(cmd, cmd->t_task_lba, sectors, 0,
					    prot_sg, prot_offset);
		else
			rc = sbc_dif_verify(cmd, cmd->t_task_lba, sectors, 0,
					    cmd->t_prot_sg, 0);
	}
	if (!rc)
		sbc_dif_copy_prot(cmd, sectors, is_read, prot_sg, prot_offset);

	return rc;
}

static sense_reason_t
rd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
	      enum dma_data_direction data_direction)
{
	struct se_device *se_dev = cmd->se_dev;
	struct rd_dev *dev = RD_DEV(se_dev);
	struct rd_dev_sg_table *table;
	struct scatterlist *rd_sg;
	struct sg_mapping_iter m;
	u32 rd_offset;
	u32 rd_size;
	u32 rd_page;
	u32 src_len;
	u64 tmp;
	sense_reason_t rc;

	if (dev->rd_flags & RDF_NULLIO) {
		target_complete_cmd(cmd, SAM_STAT_GOOD);
		return 0;
	}

	tmp = cmd->t_task_lba * se_dev->dev_attrib.block_size;
	rd_offset = do_div(tmp, PAGE_SIZE);
	rd_page = tmp;
	rd_size = cmd->data_length;

	table = rd_get_sg_table(dev, rd_page);
	if (!table)
		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

	rd_sg = &table->sg_table[rd_page - table->page_start_offset];

	pr_debug("RD[%u]: %s LBA: %llu, Size: %u Page: %u, Offset: %u\n",
			dev->rd_dev_id,
			data_direction == DMA_FROM_DEVICE ? "Read" : "Write",
			cmd->t_task_lba, rd_size, rd_page, rd_offset);

	if (cmd->prot_type && se_dev->dev_attrib.pi_prot_type &&
	    data_direction == DMA_TO_DEVICE) {
		rc = rd_do_prot_rw(cmd, false);
		if (rc)
			return rc;
	}

	src_len = PAGE_SIZE - rd_offset;
	sg_miter_start(&m, sgl, sgl_nents,
			data_direction == DMA_FROM_DEVICE ?
				SG_MITER_TO_SG : SG_MITER_FROM_SG);
	while (rd_size) {
		u32 len;
		void *rd_addr;

		sg_miter_next(&m);
		if (!(u32)m.length) {
			pr_debug("RD[%u]: invalid sgl %p len %zu\n",
				 dev->rd_dev_id, m.addr, m.length);
			sg_miter_stop(&m);
			return TCM_INCORRECT_AMOUNT_OF_DATA;
		}
		len = min((u32)m.length, src_len);
		if (len > rd_size) {
			pr_debug("RD[%u]: size underrun page %d offset %d "
				 "size %d\n", dev->rd_dev_id,
				 rd_page, rd_offset, rd_size);
			len = rd_size;
		}
		m.consumed = len;

		rd_addr = sg_virt(rd_sg) + rd_offset;

		if (data_direction == DMA_FROM_DEVICE)
			memcpy(m.addr, rd_addr, len);
		else
			memcpy(rd_addr, m.addr, len);

		rd_size -= len;
		if (!rd_size)
			continue;

		src_len -= len;
		if (src_len) {
			rd_offset += len;
			continue;
		}

		/* rd page completed, next one please */
		rd_page++;
		rd_offset = 0;
		src_len = PAGE_SIZE;
		if (rd_page <= table->page_end_offset) {
			rd_sg++;
			continue;
		}

		table = rd_get_sg_table(dev, rd_page);
		if (!table) {
			sg_miter_stop(&m);
			return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
		}

		/* since we increment, the first sg entry is correct */
		rd_sg = table->sg_table;
	}
	sg_miter_stop(&m);

	if (cmd->prot_type && se_dev->dev_attrib.pi_prot_type &&
	    data_direction == DMA_FROM_DEVICE) {
		rc = rd_do_prot_rw(cmd, true);
		if (rc)
			return rc;
	}

	target_complete_cmd(cmd, SAM_STAT_GOOD);
	return 0;
}

enum {
	Opt_rd_pages, Opt_rd_nullio, Opt_rd_dummy, Opt_err
};

static match_table_t tokens = {
	{Opt_rd_pages, "rd_pages=%d"},
	{Opt_rd_nullio, "rd_nullio=%d"},
	{Opt_rd_dummy, "rd_dummy=%d"},
	{Opt_err, NULL}
};

static ssize_t rd_set_configfs_dev_params(struct se_device *dev,
		const char *page, ssize_t count)
{
	struct rd_dev *rd_dev = RD_DEV(dev);
	char *orig, *ptr, *opts;
	substring_t args[MAX_OPT_ARGS];
	int arg, token;

	opts = kstrdup(page, GFP_KERNEL);
	if (!opts)
		return -ENOMEM;

	orig = opts;

	while ((ptr = strsep(&opts, ",\n")) != NULL) {
		if (!*ptr)
			continue;

		token = match_token(ptr, tokens, args);
		switch (token) {
		case Opt_rd_pages:
			match_int(args, &arg);
			rd_dev->rd_page_count = arg;
			pr_debug("RAMDISK: Referencing Page"
				" Count: %u\n", rd_dev->rd_page_count);
			rd_dev->rd_flags |= RDF_HAS_PAGE_COUNT;
			break;
		case Opt_rd_nullio:
			match_int(args, &arg);
			if (arg != 1)
				break;

			pr_debug("RAMDISK: Setting NULLIO flag: %d\n", arg);
			rd_dev->rd_flags |= RDF_NULLIO;
			break;
		case Opt_rd_dummy:
			match_int(args, &arg);
			if (arg != 1)
				break;

			pr_debug("RAMDISK: Setting DUMMY flag: %d\n", arg);
			rd_dev->rd_flags |= RDF_DUMMY;
			break;
		default:
			break;
		}
	}

	kfree(orig);
	return count;
}

static ssize_t rd_show_configfs_dev_params(struct se_device *dev, char *b)
{
	struct rd_dev *rd_dev = RD_DEV(dev);

	ssize_t bl = sprintf(b, "TCM RamDisk ID: %u  RamDisk Makeup: rd_mcp\n",
			rd_dev->rd_dev_id);
	bl += sprintf(b + bl, "        PAGES/PAGE_SIZE: %u*%lu"
			"  SG_table_count: %u  nullio: %d dummy: %d\n",
			rd_dev->rd_page_count,
			PAGE_SIZE, rd_dev->sg_table_count,
			!!(rd_dev->rd_flags & RDF_NULLIO),
			!!(rd_dev->rd_flags & RDF_DUMMY));
	return bl;
}

static u32 rd_get_device_type(struct se_device *dev)
{
	if (RD_DEV(dev)->rd_flags & RDF_DUMMY)
		return 0x3f; /* Unknown device type, not connected */
	else
		return sbc_get_device_type(dev);
}

static sector_t rd_get_blocks(struct se_device *dev)
{
	struct rd_dev *rd_dev = RD_DEV(dev);

	unsigned long long blocks_long = ((rd_dev->rd_page_count * PAGE_SIZE) /
			dev->dev_attrib.block_size) - 1;

	return blocks_long;
}

static int rd_init_prot(struct se_device *dev)
{
	struct rd_dev *rd_dev = RD_DEV(dev);

        if (!dev->dev_attrib.pi_prot_type)
		return 0;

	return rd_build_prot_space(rd_dev, dev->prot_length,
				   dev->dev_attrib.block_size);
}

static void rd_free_prot(struct se_device *dev)
{
	struct rd_dev *rd_dev = RD_DEV(dev);

	rd_release_prot_space(rd_dev);
}

static struct exec_cmd_ops rd_exec_cmd_ops = {
	.execute_rw		= rd_execute_rw,
};

static sense_reason_t
rd_parse_cdb(struct se_cmd *cmd)
{
	return sbc_parse_cdb(cmd, &rd_exec_cmd_ops);
}

static const struct target_backend_ops rd_mcp_ops = {
	.name			= "rd_mcp",
	.inquiry_prod		= "RAMDISK-MCP",
	.inquiry_rev		= RD_MCP_VERSION,
	.attach_hba		= rd_attach_hba,
	.detach_hba		= rd_detach_hba,
	.alloc_device		= rd_alloc_device,
	.configure_device	= rd_configure_device,
	.destroy_device		= rd_destroy_device,
	.free_device		= rd_free_device,
	.parse_cdb		= rd_parse_cdb,
	.set_configfs_dev_params = rd_set_configfs_dev_params,
	.show_configfs_dev_params = rd_show_configfs_dev_params,
	.get_device_type	= rd_get_device_type,
	.get_blocks		= rd_get_blocks,
	.init_prot		= rd_init_prot,
	.free_prot		= rd_free_prot,
	.tb_dev_attrib_attrs	= sbc_attrib_attrs,
};

int __init rd_module_init(void)
{
	return transport_backend_register(&rd_mcp_ops);
}

void rd_module_exit(void)
{
	target_backend_unregister(&rd_mcp_ops);
}
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2	/*******************************************************************************
	3	* Filename: target_core_rd.c
	4	*
	5	* This file contains the Storage Engine <-> Ramdisk transport
	6	* specific functions.
	7	*
	8	* (c) Copyright 2003-2013 Datera, Inc.
	9	*
	10	* Nicholas A. Bellinger <nab@kernel.org>
	11	*
	12	******************************************************************************/
	13
	14	#include <linux/string.h>
	15	#include <linux/parser.h>
	16	#include <linux/highmem.h>
	17	#include <linux/timer.h>
	18	#include <linux/scatterlist.h>
	19	#include <linux/slab.h>
	20	#include <linux/spinlock.h>
	21	#include <scsi/scsi_proto.h>
	22
	23	#include <target/target_core_base.h>
	24	#include <target/target_core_backend.h>
	25
	26	#include "target_core_rd.h"
	27
	28	static inline struct rd_dev RD_DEV(struct se_device dev)
	29	{
	30	return container_of(dev, struct rd_dev, dev);
	31	}
	32
	33	static int rd_attach_hba(struct se_hba *hba, u32 host_id)
	34	{
	35	struct rd_host *rd_host;
	36
	37	rd_host = kzalloc(sizeof(*rd_host), GFP_KERNEL);
	38	if (!rd_host)
	39	return -ENOMEM;
	40
	41	rd_host->rd_host_id = host_id;
	42
	43	hba->hba_ptr = rd_host;
	44
	45	pr_debug("CORE_HBA[%d] - TCM Ramdisk HBA Driver %s on"
	46	" Generic Target Core Stack %s\n", hba->hba_id,
	47	RD_HBA_VERSION, TARGET_CORE_VERSION);
	48
	49	return 0;
	50	}
	51
	52	static void rd_detach_hba(struct se_hba *hba)
	53	{
	54	struct rd_host *rd_host = hba->hba_ptr;
	55
	56	pr_debug("CORE_HBA[%d] - Detached Ramdisk HBA: %u from"
	57	" Generic Target Core\n", hba->hba_id, rd_host->rd_host_id);
	58
	59	kfree(rd_host);
	60	hba->hba_ptr = NULL;
	61	}
	62
	63	static u32 rd_release_sgl_table(struct rd_dev rd_dev, struct rd_dev_sg_table sg_table,
	64	u32 sg_table_count)
	65	{
	66	struct page *pg;
	67	struct scatterlist *sg;
	68	u32 i, j, page_count = 0, sg_per_table;
	69
	70	for (i = 0; i < sg_table_count; i++) {
	71	sg = sg_table[i].sg_table;
	72	sg_per_table = sg_table[i].rd_sg_count;
	73
	74	for (j = 0; j < sg_per_table; j++) {
	75	pg = sg_page(&sg[j]);
	76	if (pg) {
	77	__free_page(pg);
	78	page_count++;
	79	}
	80	}
	81	kfree(sg);
	82	}
	83
	84	kfree(sg_table);
	85	return page_count;
	86	}
	87
	88	static void rd_release_device_space(struct rd_dev *rd_dev)
	89	{
	90	u32 page_count;
	91
	92	if (!rd_dev->sg_table_array \|\| !rd_dev->sg_table_count)
	93	return;
	94
	95	page_count = rd_release_sgl_table(rd_dev, rd_dev->sg_table_array,
	96	rd_dev->sg_table_count);
	97
	98	pr_debug("CORE_RD[%u] - Released device space for Ramdisk"
	99	" Device ID: %u, pages %u in %u tables total bytes %lu\n",
	100	rd_dev->rd_host->rd_host_id, rd_dev->rd_dev_id, page_count,
	101	rd_dev->sg_table_count, (unsigned long)page_count * PAGE_SIZE);
	102
	103	rd_dev->sg_table_array = NULL;
	104	rd_dev->sg_table_count = 0;
	105	}
	106
	107
	108	/* rd_build_device_space():
	109	*
	110	*
	111	*/
	112	static int rd_allocate_sgl_table(struct rd_dev rd_dev, struct rd_dev_sg_table sg_table,
	113	u32 total_sg_needed, unsigned char init_payload)
	114	{
	115	u32 i = 0, j, page_offset = 0, sg_per_table;
	116	u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
	117	sizeof(struct scatterlist));
	118	struct page *pg;
	119	struct scatterlist *sg;
	120	unsigned char *p;
	121
	122	while (total_sg_needed) {
	123	unsigned int chain_entry = 0;
	124
	125	sg_per_table = (total_sg_needed > max_sg_per_table) ?
	126	max_sg_per_table : total_sg_needed;
	127
	128	/*
	129	* Reserve extra element for chain entry
	130	*/
	131	if (sg_per_table < total_sg_needed)
	132	chain_entry = 1;
	133
	134	sg = kmalloc_array(sg_per_table + chain_entry, sizeof(*sg),
	135	GFP_KERNEL);
	136	if (!sg)
	137	return -ENOMEM;
	138
	139	sg_init_table(sg, sg_per_table + chain_entry);
	140
	141	if (i > 0) {
	142	sg_chain(sg_table[i - 1].sg_table,
	143	max_sg_per_table + 1, sg);
	144	}
	145
	146	sg_table[i].sg_table = sg;
	147	sg_table[i].rd_sg_count = sg_per_table;
	148	sg_table[i].page_start_offset = page_offset;
	149	sg_table[i++].page_end_offset = (page_offset + sg_per_table)
	150	- 1;
	151
	152	for (j = 0; j < sg_per_table; j++) {
	153	pg = alloc_pages(GFP_KERNEL, 0);
	154	if (!pg) {
	155	pr_err("Unable to allocate scatterlist"
	156	" pages for struct rd_dev_sg_table\n");
	157	return -ENOMEM;
	158	}
	159	sg_assign_page(&sg[j], pg);
	160	sg[j].length = PAGE_SIZE;
	161
	162	p = kmap(pg);
	163	memset(p, init_payload, PAGE_SIZE);
	164	kunmap(pg);
	165	}
	166
	167	page_offset += sg_per_table;
	168	total_sg_needed -= sg_per_table;
	169	}
	170
	171	return 0;
	172	}
	173
	174	static int rd_build_device_space(struct rd_dev *rd_dev)
	175	{
	176	struct rd_dev_sg_table *sg_table;
	177	u32 sg_tables, total_sg_needed;
	178	u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
	179	sizeof(struct scatterlist));
	180	int rc;
	181
	182	if (rd_dev->rd_page_count <= 0) {
	183	pr_err("Illegal page count: %u for Ramdisk device\n",
	184	rd_dev->rd_page_count);
	185	return -EINVAL;
	186	}
	187
	188	/* Don't need backing pages for NULLIO */
	189	if (rd_dev->rd_flags & RDF_NULLIO)
	190	return 0;
	191
	192	total_sg_needed = rd_dev->rd_page_count;
	193
	194	sg_tables = (total_sg_needed / max_sg_per_table) + 1;
	195	sg_table = kcalloc(sg_tables, sizeof(*sg_table), GFP_KERNEL);
	196	if (!sg_table)
	197	return -ENOMEM;
	198
	199	rd_dev->sg_table_array = sg_table;
	200	rd_dev->sg_table_count = sg_tables;
	201
	202	rc = rd_allocate_sgl_table(rd_dev, sg_table, total_sg_needed, 0x00);
	203	if (rc)
	204	return rc;
	205
	206	pr_debug("CORE_RD[%u] - Built Ramdisk Device ID: %u space of"
	207	" %u pages in %u tables\n", rd_dev->rd_host->rd_host_id,
	208	rd_dev->rd_dev_id, rd_dev->rd_page_count,
	209	rd_dev->sg_table_count);
	210
	211	return 0;
	212	}
	213
	214	static void rd_release_prot_space(struct rd_dev *rd_dev)
	215	{
	216	u32 page_count;
	217
	218	if (!rd_dev->sg_prot_array \|\| !rd_dev->sg_prot_count)
	219	return;
	220
	221	page_count = rd_release_sgl_table(rd_dev, rd_dev->sg_prot_array,
	222	rd_dev->sg_prot_count);
	223
	224	pr_debug("CORE_RD[%u] - Released protection space for Ramdisk"
	225	" Device ID: %u, pages %u in %u tables total bytes %lu\n",
	226	rd_dev->rd_host->rd_host_id, rd_dev->rd_dev_id, page_count,
	227	rd_dev->sg_table_count, (unsigned long)page_count * PAGE_SIZE);
	228
	229	rd_dev->sg_prot_array = NULL;
	230	rd_dev->sg_prot_count = 0;
	231	}
	232
	233	static int rd_build_prot_space(struct rd_dev *rd_dev, int prot_length, int block_size)
	234	{
	235	struct rd_dev_sg_table *sg_table;
	236	u32 total_sg_needed, sg_tables;
	237	u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
	238	sizeof(struct scatterlist));
	239	int rc;
	240
	241	if (rd_dev->rd_flags & RDF_NULLIO)
	242	return 0;
	243	/*
	244	* prot_length=8byte dif data
	245	* tot sg needed = rd_page_count * (PGSZ/block_size) *
	246	* (prot_length/block_size) + pad
	247	* PGSZ canceled each other.
	248	*/
	249	total_sg_needed = (rd_dev->rd_page_count * prot_length / block_size) + 1;
	250
	251	sg_tables = (total_sg_needed / max_sg_per_table) + 1;
	252	sg_table = kcalloc(sg_tables, sizeof(*sg_table), GFP_KERNEL);
	253	if (!sg_table)
	254	return -ENOMEM;
	255
	256	rd_dev->sg_prot_array = sg_table;
	257	rd_dev->sg_prot_count = sg_tables;
	258
	259	rc = rd_allocate_sgl_table(rd_dev, sg_table, total_sg_needed, 0xff);
	260	if (rc)
	261	return rc;
	262
	263	pr_debug("CORE_RD[%u] - Built Ramdisk Device ID: %u prot space of"
	264	" %u pages in %u tables\n", rd_dev->rd_host->rd_host_id,
	265	rd_dev->rd_dev_id, total_sg_needed, rd_dev->sg_prot_count);
	266
	267	return 0;
	268	}
	269
	270	static struct se_device rd_alloc_device(struct se_hba hba, const char *name)
	271	{
	272	struct rd_dev *rd_dev;
	273	struct rd_host *rd_host = hba->hba_ptr;
	274
	275	rd_dev = kzalloc(sizeof(*rd_dev), GFP_KERNEL);
	276	if (!rd_dev)
	277	return NULL;
	278
	279	rd_dev->rd_host = rd_host;
	280
	281	return &rd_dev->dev;
	282	}
	283
	284	static int rd_configure_device(struct se_device *dev)
	285	{
	286	struct rd_dev *rd_dev = RD_DEV(dev);
	287	struct rd_host *rd_host = dev->se_hba->hba_ptr;
	288	int ret;
	289
	290	if (!(rd_dev->rd_flags & RDF_HAS_PAGE_COUNT)) {
	291	pr_debug("Missing rd_pages= parameter\n");
	292	return -EINVAL;
	293	}
	294
	295	ret = rd_build_device_space(rd_dev);
	296	if (ret < 0)
	297	goto fail;
	298
	299	dev->dev_attrib.hw_block_size = RD_BLOCKSIZE;
	300	dev->dev_attrib.hw_max_sectors = UINT_MAX;
	301	dev->dev_attrib.hw_queue_depth = RD_MAX_DEVICE_QUEUE_DEPTH;
	302	dev->dev_attrib.is_nonrot = 1;
	303
	304	rd_dev->rd_dev_id = rd_host->rd_host_dev_id_count++;
	305
	306	pr_debug("CORE_RD[%u] - Added TCM MEMCPY Ramdisk Device ID: %u of"
	307	" %u pages in %u tables, %lu total bytes\n",
	308	rd_host->rd_host_id, rd_dev->rd_dev_id, rd_dev->rd_page_count,
	309	rd_dev->sg_table_count,
	310	(unsigned long)(rd_dev->rd_page_count * PAGE_SIZE));
	311
	312	return 0;
	313
	314	fail:
	315	rd_release_device_space(rd_dev);
	316	return ret;
	317	}
	318
	319	static void rd_dev_call_rcu(struct rcu_head *p)
	320	{
	321	struct se_device *dev = container_of(p, struct se_device, rcu_head);
	322	struct rd_dev *rd_dev = RD_DEV(dev);
	323
	324	kfree(rd_dev);
	325	}
	326
	327	static void rd_free_device(struct se_device *dev)
	328	{
	329	call_rcu(&dev->rcu_head, rd_dev_call_rcu);
	330	}
	331
	332	static void rd_destroy_device(struct se_device *dev)
	333	{
	334	struct rd_dev *rd_dev = RD_DEV(dev);
	335
	336	rd_release_device_space(rd_dev);
	337	}
	338
	339	static struct rd_dev_sg_table rd_get_sg_table(struct rd_dev rd_dev, u32 page)
	340	{
	341	struct rd_dev_sg_table *sg_table;
	342	u32 i, sg_per_table = (RD_MAX_ALLOCATION_SIZE /
	343	sizeof(struct scatterlist));
	344
	345	i = page / sg_per_table;
	346	if (i < rd_dev->sg_table_count) {
	347	sg_table = &rd_dev->sg_table_array[i];
	348	if ((sg_table->page_start_offset <= page) &&
	349	(sg_table->page_end_offset >= page))
	350	return sg_table;
	351	}
	352
	353	pr_err("Unable to locate struct rd_dev_sg_table for page: %u\n",
	354	page);
	355
	356	return NULL;
	357	}
	358
	359	static struct rd_dev_sg_table rd_get_prot_table(struct rd_dev rd_dev, u32 page)
	360	{
	361	struct rd_dev_sg_table *sg_table;
	362	u32 i, sg_per_table = (RD_MAX_ALLOCATION_SIZE /
	363	sizeof(struct scatterlist));
	364
	365	i = page / sg_per_table;
	366	if (i < rd_dev->sg_prot_count) {
	367	sg_table = &rd_dev->sg_prot_array[i];
	368	if ((sg_table->page_start_offset <= page) &&
	369	(sg_table->page_end_offset >= page))
	370	return sg_table;
	371	}
	372
	373	pr_err("Unable to locate struct prot rd_dev_sg_table for page: %u\n",
	374	page);
	375
	376	return NULL;
	377	}
	378
	379	static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, bool is_read)
	380	{
	381	struct se_device *se_dev = cmd->se_dev;
	382	struct rd_dev *dev = RD_DEV(se_dev);
	383	struct rd_dev_sg_table *prot_table;
	384	struct scatterlist *prot_sg;
	385	u32 sectors = cmd->data_length / se_dev->dev_attrib.block_size;
	386	u32 prot_offset, prot_page;
	387	u32 prot_npages __maybe_unused;
	388	u64 tmp;
	389	sense_reason_t rc = 0;
	390
	391	tmp = cmd->t_task_lba * se_dev->prot_length;
	392	prot_offset = do_div(tmp, PAGE_SIZE);
	393	prot_page = tmp;
	394
	395	prot_table = rd_get_prot_table(dev, prot_page);
	396	if (!prot_table)
	397	return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
	398
	399	prot_sg = &prot_table->sg_table[prot_page -
	400	prot_table->page_start_offset];
	401
	402	if (se_dev->dev_attrib.pi_prot_verify) {
	403	if (is_read)
	404	rc = sbc_dif_verify(cmd, cmd->t_task_lba, sectors, 0,
	405	prot_sg, prot_offset);
	406	else
	407	rc = sbc_dif_verify(cmd, cmd->t_task_lba, sectors, 0,
	408	cmd->t_prot_sg, 0);
	409	}
	410	if (!rc)
	411	sbc_dif_copy_prot(cmd, sectors, is_read, prot_sg, prot_offset);
	412
	413	return rc;
	414	}
	415
	416	static sense_reason_t
	417	rd_execute_rw(struct se_cmd cmd, struct scatterlist sgl, u32 sgl_nents,
	418	enum dma_data_direction data_direction)
	419	{
	420	struct se_device *se_dev = cmd->se_dev;
	421	struct rd_dev *dev = RD_DEV(se_dev);
	422	struct rd_dev_sg_table *table;
	423	struct scatterlist *rd_sg;
	424	struct sg_mapping_iter m;
	425	u32 rd_offset;
	426	u32 rd_size;
	427	u32 rd_page;
	428	u32 src_len;
	429	u64 tmp;
	430	sense_reason_t rc;
	431
	432	if (dev->rd_flags & RDF_NULLIO) {
	433	target_complete_cmd(cmd, SAM_STAT_GOOD);
	434	return 0;
	435	}
	436
	437	tmp = cmd->t_task_lba * se_dev->dev_attrib.block_size;
	438	rd_offset = do_div(tmp, PAGE_SIZE);
	439	rd_page = tmp;
	440	rd_size = cmd->data_length;
	441
	442	table = rd_get_sg_table(dev, rd_page);
	443	if (!table)
	444	return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
	445
	446	rd_sg = &table->sg_table[rd_page - table->page_start_offset];
	447
	448	pr_debug("RD[%u]: %s LBA: %llu, Size: %u Page: %u, Offset: %u\n",
	449	dev->rd_dev_id,
	450	data_direction == DMA_FROM_DEVICE ? "Read" : "Write",
	451	cmd->t_task_lba, rd_size, rd_page, rd_offset);
	452
	453	if (cmd->prot_type && se_dev->dev_attrib.pi_prot_type &&
	454	data_direction == DMA_TO_DEVICE) {
	455	rc = rd_do_prot_rw(cmd, false);
	456	if (rc)
	457	return rc;
	458	}
	459
	460	src_len = PAGE_SIZE - rd_offset;
	461	sg_miter_start(&m, sgl, sgl_nents,
	462	data_direction == DMA_FROM_DEVICE ?
	463	SG_MITER_TO_SG : SG_MITER_FROM_SG);
	464	while (rd_size) {
	465	u32 len;
	466	void *rd_addr;
	467
	468	sg_miter_next(&m);
	469	if (!(u32)m.length) {
	470	pr_debug("RD[%u]: invalid sgl %p len %zu\n",
	471	dev->rd_dev_id, m.addr, m.length);
	472	sg_miter_stop(&m);
	473	return TCM_INCORRECT_AMOUNT_OF_DATA;
	474	}
	475	len = min((u32)m.length, src_len);
	476	if (len > rd_size) {
	477	pr_debug("RD[%u]: size underrun page %d offset %d "
	478	"size %d\n", dev->rd_dev_id,
	479	rd_page, rd_offset, rd_size);
	480	len = rd_size;
	481	}
	482	m.consumed = len;
	483
	484	rd_addr = sg_virt(rd_sg) + rd_offset;
	485
	486	if (data_direction == DMA_FROM_DEVICE)
	487	memcpy(m.addr, rd_addr, len);
	488	else
	489	memcpy(rd_addr, m.addr, len);
	490
	491	rd_size -= len;
	492	if (!rd_size)
	493	continue;
	494
	495	src_len -= len;
	496	if (src_len) {
	497	rd_offset += len;
	498	continue;
	499	}
	500
	501	/* rd page completed, next one please */
	502	rd_page++;
	503	rd_offset = 0;
	504	src_len = PAGE_SIZE;
	505	if (rd_page <= table->page_end_offset) {
	506	rd_sg++;
	507	continue;
	508	}
	509
	510	table = rd_get_sg_table(dev, rd_page);
	511	if (!table) {
	512	sg_miter_stop(&m);
	513	return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
	514	}
	515
	516	/* since we increment, the first sg entry is correct */
	517	rd_sg = table->sg_table;
	518	}
	519	sg_miter_stop(&m);
	520
	521	if (cmd->prot_type && se_dev->dev_attrib.pi_prot_type &&
	522	data_direction == DMA_FROM_DEVICE) {
	523	rc = rd_do_prot_rw(cmd, true);
	524	if (rc)
	525	return rc;
	526	}
	527
	528	target_complete_cmd(cmd, SAM_STAT_GOOD);
	529	return 0;
	530	}
	531
	532	enum {
	533	Opt_rd_pages, Opt_rd_nullio, Opt_rd_dummy, Opt_err
	534	};
	535
	536	static match_table_t tokens = {
	537	{Opt_rd_pages, "rd_pages=%d"},
	538	{Opt_rd_nullio, "rd_nullio=%d"},
	539	{Opt_rd_dummy, "rd_dummy=%d"},
	540	{Opt_err, NULL}
	541	};
	542
	543	static ssize_t rd_set_configfs_dev_params(struct se_device *dev,
	544	const char *page, ssize_t count)
	545	{
	546	struct rd_dev *rd_dev = RD_DEV(dev);
	547	char orig, ptr, *opts;
	548	substring_t args[MAX_OPT_ARGS];
	549	int arg, token;
	550
	551	opts = kstrdup(page, GFP_KERNEL);
	552	if (!opts)
	553	return -ENOMEM;
	554
	555	orig = opts;
	556
	557	while ((ptr = strsep(&opts, ",\n")) != NULL) {
	558	if (!*ptr)
	559	continue;
	560
	561	token = match_token(ptr, tokens, args);
	562	switch (token) {
	563	case Opt_rd_pages:
	564	match_int(args, &arg);
	565	rd_dev->rd_page_count = arg;
	566	pr_debug("RAMDISK: Referencing Page"
	567	" Count: %u\n", rd_dev->rd_page_count);
	568	rd_dev->rd_flags \|= RDF_HAS_PAGE_COUNT;
	569	break;
	570	case Opt_rd_nullio:
	571	match_int(args, &arg);
	572	if (arg != 1)
	573	break;
	574
	575	pr_debug("RAMDISK: Setting NULLIO flag: %d\n", arg);
	576	rd_dev->rd_flags \|= RDF_NULLIO;
	577	break;
	578	case Opt_rd_dummy:
	579	match_int(args, &arg);
	580	if (arg != 1)
	581	break;
	582
	583	pr_debug("RAMDISK: Setting DUMMY flag: %d\n", arg);
	584	rd_dev->rd_flags \|= RDF_DUMMY;
	585	break;
	586	default:
	587	break;
	588	}
	589	}
	590
	591	kfree(orig);
	592	return count;
	593	}
	594
	595	static ssize_t rd_show_configfs_dev_params(struct se_device dev, char b)
	596	{
	597	struct rd_dev *rd_dev = RD_DEV(dev);
	598
	599	ssize_t bl = sprintf(b, "TCM RamDisk ID: %u RamDisk Makeup: rd_mcp\n",
	600	rd_dev->rd_dev_id);
	601	bl += sprintf(b + bl, " PAGES/PAGE_SIZE: %u*%lu"
	602	" SG_table_count: %u nullio: %d dummy: %d\n",
	603	rd_dev->rd_page_count,
	604	PAGE_SIZE, rd_dev->sg_table_count,
	605	!!(rd_dev->rd_flags & RDF_NULLIO),
	606	!!(rd_dev->rd_flags & RDF_DUMMY));
	607	return bl;
	608	}
	609
	610	static u32 rd_get_device_type(struct se_device *dev)
	611	{
	612	if (RD_DEV(dev)->rd_flags & RDF_DUMMY)
	613	return 0x3f; /* Unknown device type, not connected */
	614	else
	615	return sbc_get_device_type(dev);
	616	}
	617
	618	static sector_t rd_get_blocks(struct se_device *dev)
	619	{
	620	struct rd_dev *rd_dev = RD_DEV(dev);
	621
	622	unsigned long long blocks_long = ((rd_dev->rd_page_count * PAGE_SIZE) /
	623	dev->dev_attrib.block_size) - 1;
	624
	625	return blocks_long;
	626	}
	627
	628	static int rd_init_prot(struct se_device *dev)
	629	{
	630	struct rd_dev *rd_dev = RD_DEV(dev);
	631
	632	if (!dev->dev_attrib.pi_prot_type)
	633	return 0;
	634
	635	return rd_build_prot_space(rd_dev, dev->prot_length,
	636	dev->dev_attrib.block_size);
	637	}
	638
	639	static void rd_free_prot(struct se_device *dev)
	640	{
	641	struct rd_dev *rd_dev = RD_DEV(dev);
	642
	643	rd_release_prot_space(rd_dev);
	644	}
	645
	646	static struct exec_cmd_ops rd_exec_cmd_ops = {
	647	.execute_rw = rd_execute_rw,
	648	};
	649
	650	static sense_reason_t
	651	rd_parse_cdb(struct se_cmd *cmd)
	652	{
	653	return sbc_parse_cdb(cmd, &rd_exec_cmd_ops);
	654	}
	655
	656	static const struct target_backend_ops rd_mcp_ops = {
	657	.name = "rd_mcp",
	658	.inquiry_prod = "RAMDISK-MCP",
	659	.inquiry_rev = RD_MCP_VERSION,
	660	.attach_hba = rd_attach_hba,
	661	.detach_hba = rd_detach_hba,
	662	.alloc_device = rd_alloc_device,
	663	.configure_device = rd_configure_device,
	664	.destroy_device = rd_destroy_device,
	665	.free_device = rd_free_device,
	666	.parse_cdb = rd_parse_cdb,
	667	.set_configfs_dev_params = rd_set_configfs_dev_params,
	668	.show_configfs_dev_params = rd_show_configfs_dev_params,
	669	.get_device_type = rd_get_device_type,
	670	.get_blocks = rd_get_blocks,
	671	.init_prot = rd_init_prot,
	672	.free_prot = rd_free_prot,
	673	.tb_dev_attrib_attrs = sbc_attrib_attrs,
	674	};
	675
	676	int __init rd_module_init(void)
	677	{
	678	return transport_backend_register(&rd_mcp_ops);
	679	}
	680
	681	void rd_module_exit(void)
	682	{
	683	target_backend_unregister(&rd_mcp_ops);
	684	}