text: /*******************************************************************************
   * 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>
   *
   * 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.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   *
   ******************************************************************************/
  
  #include <linux/string.h>
  #include <linux/parser.h>
  #include <linux/timer.h>
  #include <linux/slab.h>
  #include <linux/spinlock.h>
  #include <scsi/scsi.h>
  #include <scsi/scsi_host.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);
  }
  
  /*	rd_attach_hba(): (Part of se_subsystem_api_t template)
   *
   *
   */
  static int rd_attach_hba(struct se_hba *hba, u32 host_id)
  {
  	struct rd_host *rd_host;
  
  	rd_host = kzalloc(sizeof(struct rd_host), GFP_KERNEL);
  	if (!rd_host) {
  		pr_err("Unable to allocate memory for struct rd_host\n");
  		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_MOD_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) {
  		sg_per_table = (total_sg_needed > max_sg_per_table) ?
  			max_sg_per_table : total_sg_needed;
  
  		sg = kzalloc(sg_per_table * sizeof(struct scatterlist),
  				GFP_KERNEL);
  		if (!sg) {
  			pr_err("Unable to allocate scatterlist array"
  				" for struct rd_dev\n");
  			return -ENOMEM;
  		}
  
  		sg_init_table(sg, sg_per_table);
  
  		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 = kzalloc(sg_tables * sizeof(struct rd_dev_sg_table), GFP_KERNEL);
  	if (!sg_table) {
  		pr_err("Unable to allocate memory for Ramdisk"
  		       " scatterlist tables\n");
  		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)
  {
  	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;
  
  	total_sg_needed = rd_dev->rd_page_count / prot_length;
  
  	sg_tables = (total_sg_needed / max_sg_per_table) + 1;
  
  	sg_table = kzalloc(sg_tables * sizeof(struct rd_dev_sg_table), GFP_KERNEL);
  	if (!sg_table) {
  		pr_err("Unable to allocate memory for Ramdisk protection"
  		       " scatterlist tables\n");
  		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(struct rd_dev), GFP_KERNEL);
  	if (!rd_dev) {
  		pr_err("Unable to allocate memory for struct rd_dev\n");
  		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;
  
  	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_free_device(struct se_device *dev)
  {
  	struct rd_dev *rd_dev = RD_DEV(dev);
  
  	rd_release_device_space(rd_dev);
  	kfree(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_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 && data_direction == DMA_TO_DEVICE) {
  		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;
  
  		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];
  
  		rc = sbc_dif_verify_write(cmd, cmd->t_task_lba, sectors, 0,
  					  prot_sg, prot_offset);
  		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 && data_direction == DMA_FROM_DEVICE) {
  		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;
  
  		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];
  
  		rc = sbc_dif_verify_read(cmd, cmd->t_task_lba, sectors, 0,
  					 prot_sg, prot_offset);
  		if (rc)
  			return rc;
  	}
  
  	target_complete_cmd(cmd, SAM_STAT_GOOD);
  	return 0;
  }
  
  enum {
  	Opt_rd_pages, Opt_rd_nullio, Opt_err
  };
  
  static match_table_t tokens = {
  	{Opt_rd_pages, "rd_pages=%d"},
  	{Opt_rd_nullio, "rd_nullio=%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 ret = 0, 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;
  		default:
  			break;
  		}
  	}
  
  	kfree(orig);
  	return (!ret) ? count : ret;
  }
  
  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\n", rd_dev->rd_page_count,
  			PAGE_SIZE, rd_dev->sg_table_count,
  			!!(rd_dev->rd_flags & RDF_NULLIO));
  	return bl;
  }
  
  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);
  }
  
  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 sbc_ops rd_sbc_ops = {
  	.execute_rw		= rd_execute_rw,
  };
  
  static sense_reason_t
  rd_parse_cdb(struct se_cmd *cmd)
  {
  	return sbc_parse_cdb(cmd, &rd_sbc_ops);
  }
  
  static struct se_subsystem_api rd_mcp_template = {
  	.name			= "rd_mcp",
  	.inquiry_prod		= "RAMDISK-MCP",
  	.inquiry_rev		= RD_MCP_VERSION,
  	.transport_type		= TRANSPORT_PLUGIN_VHBA_VDEV,
  	.attach_hba		= rd_attach_hba,
  	.detach_hba		= rd_detach_hba,
  	.alloc_device		= rd_alloc_device,
  	.configure_device	= rd_configure_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	= sbc_get_device_type,
  	.get_blocks		= rd_get_blocks,
  	.init_prot		= rd_init_prot,
  	.free_prot		= rd_free_prot,
  };
  
  int __init rd_module_init(void)
  {
  	int ret;
  
  	ret = transport_subsystem_register(&rd_mcp_template);
  	if (ret < 0) {
  		return ret;
  	}
  
  	return 0;
  }
  
  void rd_module_exit(void)
  {
  	transport_subsystem_release(&rd_mcp_template);
  }
  