linux/drivers/target/target_core_rd.c
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   1/*******************************************************************************
   2 * Filename:  target_core_rd.c
   3 *
   4 * This file contains the Storage Engine <-> Ramdisk transport
   5 * specific functions.
   6 *
   7 * Copyright (c) 2003, 2004, 2005 PyX Technologies, Inc.
   8 * Copyright (c) 2005, 2006, 2007 SBE, Inc.
   9 * Copyright (c) 2007-2010 Rising Tide Systems
  10 * Copyright (c) 2008-2010 Linux-iSCSI.org
  11 *
  12 * Nicholas A. Bellinger <nab@kernel.org>
  13 *
  14 * This program is free software; you can redistribute it and/or modify
  15 * it under the terms of the GNU General Public License as published by
  16 * the Free Software Foundation; either version 2 of the License, or
  17 * (at your option) any later version.
  18 *
  19 * This program is distributed in the hope that it will be useful,
  20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22 * GNU General Public License for more details.
  23 *
  24 * You should have received a copy of the GNU General Public License
  25 * along with this program; if not, write to the Free Software
  26 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27 *
  28 ******************************************************************************/
  29
  30#include <linux/string.h>
  31#include <linux/parser.h>
  32#include <linux/timer.h>
  33#include <linux/blkdev.h>
  34#include <linux/slab.h>
  35#include <linux/spinlock.h>
  36#include <scsi/scsi.h>
  37#include <scsi/scsi_host.h>
  38
  39#include <target/target_core_base.h>
  40#include <target/target_core_backend.h>
  41
  42#include "target_core_rd.h"
  43
  44static struct se_subsystem_api rd_mcp_template;
  45
  46/*      rd_attach_hba(): (Part of se_subsystem_api_t template)
  47 *
  48 *
  49 */
  50static int rd_attach_hba(struct se_hba *hba, u32 host_id)
  51{
  52        struct rd_host *rd_host;
  53
  54        rd_host = kzalloc(sizeof(struct rd_host), GFP_KERNEL);
  55        if (!rd_host) {
  56                pr_err("Unable to allocate memory for struct rd_host\n");
  57                return -ENOMEM;
  58        }
  59
  60        rd_host->rd_host_id = host_id;
  61
  62        hba->hba_ptr = rd_host;
  63
  64        pr_debug("CORE_HBA[%d] - TCM Ramdisk HBA Driver %s on"
  65                " Generic Target Core Stack %s\n", hba->hba_id,
  66                RD_HBA_VERSION, TARGET_CORE_MOD_VERSION);
  67
  68        return 0;
  69}
  70
  71static void rd_detach_hba(struct se_hba *hba)
  72{
  73        struct rd_host *rd_host = hba->hba_ptr;
  74
  75        pr_debug("CORE_HBA[%d] - Detached Ramdisk HBA: %u from"
  76                " Generic Target Core\n", hba->hba_id, rd_host->rd_host_id);
  77
  78        kfree(rd_host);
  79        hba->hba_ptr = NULL;
  80}
  81
  82/*      rd_release_device_space():
  83 *
  84 *
  85 */
  86static void rd_release_device_space(struct rd_dev *rd_dev)
  87{
  88        u32 i, j, page_count = 0, sg_per_table;
  89        struct rd_dev_sg_table *sg_table;
  90        struct page *pg;
  91        struct scatterlist *sg;
  92
  93        if (!rd_dev->sg_table_array || !rd_dev->sg_table_count)
  94                return;
  95
  96        sg_table = rd_dev->sg_table_array;
  97
  98        for (i = 0; i < rd_dev->sg_table_count; i++) {
  99                sg = sg_table[i].sg_table;
 100                sg_per_table = sg_table[i].rd_sg_count;
 101
 102                for (j = 0; j < sg_per_table; j++) {
 103                        pg = sg_page(&sg[j]);
 104                        if (pg) {
 105                                __free_page(pg);
 106                                page_count++;
 107                        }
 108                }
 109
 110                kfree(sg);
 111        }
 112
 113        pr_debug("CORE_RD[%u] - Released device space for Ramdisk"
 114                " Device ID: %u, pages %u in %u tables total bytes %lu\n",
 115                rd_dev->rd_host->rd_host_id, rd_dev->rd_dev_id, page_count,
 116                rd_dev->sg_table_count, (unsigned long)page_count * PAGE_SIZE);
 117
 118        kfree(sg_table);
 119        rd_dev->sg_table_array = NULL;
 120        rd_dev->sg_table_count = 0;
 121}
 122
 123
 124/*      rd_build_device_space():
 125 *
 126 *
 127 */
 128static int rd_build_device_space(struct rd_dev *rd_dev)
 129{
 130        u32 i = 0, j, page_offset = 0, sg_per_table, sg_tables, total_sg_needed;
 131        u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
 132                                sizeof(struct scatterlist));
 133        struct rd_dev_sg_table *sg_table;
 134        struct page *pg;
 135        struct scatterlist *sg;
 136
 137        if (rd_dev->rd_page_count <= 0) {
 138                pr_err("Illegal page count: %u for Ramdisk device\n",
 139                        rd_dev->rd_page_count);
 140                return -EINVAL;
 141        }
 142        total_sg_needed = rd_dev->rd_page_count;
 143
 144        sg_tables = (total_sg_needed / max_sg_per_table) + 1;
 145
 146        sg_table = kzalloc(sg_tables * sizeof(struct rd_dev_sg_table), GFP_KERNEL);
 147        if (!sg_table) {
 148                pr_err("Unable to allocate memory for Ramdisk"
 149                        " scatterlist tables\n");
 150                return -ENOMEM;
 151        }
 152
 153        rd_dev->sg_table_array = sg_table;
 154        rd_dev->sg_table_count = sg_tables;
 155
 156        while (total_sg_needed) {
 157                sg_per_table = (total_sg_needed > max_sg_per_table) ?
 158                        max_sg_per_table : total_sg_needed;
 159
 160                sg = kzalloc(sg_per_table * sizeof(struct scatterlist),
 161                                GFP_KERNEL);
 162                if (!sg) {
 163                        pr_err("Unable to allocate scatterlist array"
 164                                " for struct rd_dev\n");
 165                        return -ENOMEM;
 166                }
 167
 168                sg_init_table(sg, sg_per_table);
 169
 170                sg_table[i].sg_table = sg;
 171                sg_table[i].rd_sg_count = sg_per_table;
 172                sg_table[i].page_start_offset = page_offset;
 173                sg_table[i++].page_end_offset = (page_offset + sg_per_table)
 174                                                - 1;
 175
 176                for (j = 0; j < sg_per_table; j++) {
 177                        pg = alloc_pages(GFP_KERNEL, 0);
 178                        if (!pg) {
 179                                pr_err("Unable to allocate scatterlist"
 180                                        " pages for struct rd_dev_sg_table\n");
 181                                return -ENOMEM;
 182                        }
 183                        sg_assign_page(&sg[j], pg);
 184                        sg[j].length = PAGE_SIZE;
 185                }
 186
 187                page_offset += sg_per_table;
 188                total_sg_needed -= sg_per_table;
 189        }
 190
 191        pr_debug("CORE_RD[%u] - Built Ramdisk Device ID: %u space of"
 192                " %u pages in %u tables\n", rd_dev->rd_host->rd_host_id,
 193                rd_dev->rd_dev_id, rd_dev->rd_page_count,
 194                rd_dev->sg_table_count);
 195
 196        return 0;
 197}
 198
 199static void *rd_allocate_virtdevice(struct se_hba *hba, const char *name)
 200{
 201        struct rd_dev *rd_dev;
 202        struct rd_host *rd_host = hba->hba_ptr;
 203
 204        rd_dev = kzalloc(sizeof(struct rd_dev), GFP_KERNEL);
 205        if (!rd_dev) {
 206                pr_err("Unable to allocate memory for struct rd_dev\n");
 207                return NULL;
 208        }
 209
 210        rd_dev->rd_host = rd_host;
 211
 212        return rd_dev;
 213}
 214
 215static struct se_device *rd_create_virtdevice(struct se_hba *hba,
 216                struct se_subsystem_dev *se_dev, void *p)
 217{
 218        struct se_device *dev;
 219        struct se_dev_limits dev_limits;
 220        struct rd_dev *rd_dev = p;
 221        struct rd_host *rd_host = hba->hba_ptr;
 222        int dev_flags = 0, ret;
 223        char prod[16], rev[4];
 224
 225        memset(&dev_limits, 0, sizeof(struct se_dev_limits));
 226
 227        ret = rd_build_device_space(rd_dev);
 228        if (ret < 0)
 229                goto fail;
 230
 231        snprintf(prod, 16, "RAMDISK-MCP");
 232        snprintf(rev, 4, "%s", RD_MCP_VERSION);
 233
 234        dev_limits.limits.logical_block_size = RD_BLOCKSIZE;
 235        dev_limits.limits.max_hw_sectors = UINT_MAX;
 236        dev_limits.limits.max_sectors = UINT_MAX;
 237        dev_limits.hw_queue_depth = RD_MAX_DEVICE_QUEUE_DEPTH;
 238        dev_limits.queue_depth = RD_DEVICE_QUEUE_DEPTH;
 239
 240        dev = transport_add_device_to_core_hba(hba,
 241                        &rd_mcp_template, se_dev, dev_flags, rd_dev,
 242                        &dev_limits, prod, rev);
 243        if (!dev)
 244                goto fail;
 245
 246        rd_dev->rd_dev_id = rd_host->rd_host_dev_id_count++;
 247
 248        pr_debug("CORE_RD[%u] - Added TCM MEMCPY Ramdisk Device ID: %u of"
 249                " %u pages in %u tables, %lu total bytes\n",
 250                rd_host->rd_host_id, rd_dev->rd_dev_id, rd_dev->rd_page_count,
 251                rd_dev->sg_table_count,
 252                (unsigned long)(rd_dev->rd_page_count * PAGE_SIZE));
 253
 254        return dev;
 255
 256fail:
 257        rd_release_device_space(rd_dev);
 258        return ERR_PTR(ret);
 259}
 260
 261static void rd_free_device(void *p)
 262{
 263        struct rd_dev *rd_dev = p;
 264
 265        rd_release_device_space(rd_dev);
 266        kfree(rd_dev);
 267}
 268
 269static struct rd_dev_sg_table *rd_get_sg_table(struct rd_dev *rd_dev, u32 page)
 270{
 271        u32 i;
 272        struct rd_dev_sg_table *sg_table;
 273
 274        for (i = 0; i < rd_dev->sg_table_count; i++) {
 275                sg_table = &rd_dev->sg_table_array[i];
 276                if ((sg_table->page_start_offset <= page) &&
 277                    (sg_table->page_end_offset >= page))
 278                        return sg_table;
 279        }
 280
 281        pr_err("Unable to locate struct rd_dev_sg_table for page: %u\n",
 282                        page);
 283
 284        return NULL;
 285}
 286
 287static int rd_execute_rw(struct se_cmd *cmd)
 288{
 289        struct scatterlist *sgl = cmd->t_data_sg;
 290        u32 sgl_nents = cmd->t_data_nents;
 291        enum dma_data_direction data_direction = cmd->data_direction;
 292        struct se_device *se_dev = cmd->se_dev;
 293        struct rd_dev *dev = se_dev->dev_ptr;
 294        struct rd_dev_sg_table *table;
 295        struct scatterlist *rd_sg;
 296        struct sg_mapping_iter m;
 297        u32 rd_offset;
 298        u32 rd_size;
 299        u32 rd_page;
 300        u32 src_len;
 301        u64 tmp;
 302
 303        tmp = cmd->t_task_lba * se_dev->se_sub_dev->se_dev_attrib.block_size;
 304        rd_offset = do_div(tmp, PAGE_SIZE);
 305        rd_page = tmp;
 306        rd_size = cmd->data_length;
 307
 308        table = rd_get_sg_table(dev, rd_page);
 309        if (!table)
 310                return -EINVAL;
 311
 312        rd_sg = &table->sg_table[rd_page - table->page_start_offset];
 313
 314        pr_debug("RD[%u]: %s LBA: %llu, Size: %u Page: %u, Offset: %u\n",
 315                        dev->rd_dev_id,
 316                        data_direction == DMA_FROM_DEVICE ? "Read" : "Write",
 317                        cmd->t_task_lba, rd_size, rd_page, rd_offset);
 318
 319        src_len = PAGE_SIZE - rd_offset;
 320        sg_miter_start(&m, sgl, sgl_nents,
 321                        data_direction == DMA_FROM_DEVICE ?
 322                                SG_MITER_TO_SG : SG_MITER_FROM_SG);
 323        while (rd_size) {
 324                u32 len;
 325                void *rd_addr;
 326
 327                sg_miter_next(&m);
 328                len = min((u32)m.length, src_len);
 329                m.consumed = len;
 330
 331                rd_addr = sg_virt(rd_sg) + rd_offset;
 332
 333                if (data_direction == DMA_FROM_DEVICE)
 334                        memcpy(m.addr, rd_addr, len);
 335                else
 336                        memcpy(rd_addr, m.addr, len);
 337
 338                rd_size -= len;
 339                if (!rd_size)
 340                        continue;
 341
 342                src_len -= len;
 343                if (src_len) {
 344                        rd_offset += len;
 345                        continue;
 346                }
 347
 348                /* rd page completed, next one please */
 349                rd_page++;
 350                rd_offset = 0;
 351                src_len = PAGE_SIZE;
 352                if (rd_page <= table->page_end_offset) {
 353                        rd_sg++;
 354                        continue;
 355                }
 356
 357                table = rd_get_sg_table(dev, rd_page);
 358                if (!table) {
 359                        sg_miter_stop(&m);
 360                        return -EINVAL;
 361                }
 362
 363                /* since we increment, the first sg entry is correct */
 364                rd_sg = table->sg_table;
 365        }
 366        sg_miter_stop(&m);
 367
 368        target_complete_cmd(cmd, SAM_STAT_GOOD);
 369        return 0;
 370}
 371
 372enum {
 373        Opt_rd_pages, Opt_err
 374};
 375
 376static match_table_t tokens = {
 377        {Opt_rd_pages, "rd_pages=%d"},
 378        {Opt_err, NULL}
 379};
 380
 381static ssize_t rd_set_configfs_dev_params(
 382        struct se_hba *hba,
 383        struct se_subsystem_dev *se_dev,
 384        const char *page,
 385        ssize_t count)
 386{
 387        struct rd_dev *rd_dev = se_dev->se_dev_su_ptr;
 388        char *orig, *ptr, *opts;
 389        substring_t args[MAX_OPT_ARGS];
 390        int ret = 0, arg, token;
 391
 392        opts = kstrdup(page, GFP_KERNEL);
 393        if (!opts)
 394                return -ENOMEM;
 395
 396        orig = opts;
 397
 398        while ((ptr = strsep(&opts, ",\n")) != NULL) {
 399                if (!*ptr)
 400                        continue;
 401
 402                token = match_token(ptr, tokens, args);
 403                switch (token) {
 404                case Opt_rd_pages:
 405                        match_int(args, &arg);
 406                        rd_dev->rd_page_count = arg;
 407                        pr_debug("RAMDISK: Referencing Page"
 408                                " Count: %u\n", rd_dev->rd_page_count);
 409                        rd_dev->rd_flags |= RDF_HAS_PAGE_COUNT;
 410                        break;
 411                default:
 412                        break;
 413                }
 414        }
 415
 416        kfree(orig);
 417        return (!ret) ? count : ret;
 418}
 419
 420static ssize_t rd_check_configfs_dev_params(struct se_hba *hba, struct se_subsystem_dev *se_dev)
 421{
 422        struct rd_dev *rd_dev = se_dev->se_dev_su_ptr;
 423
 424        if (!(rd_dev->rd_flags & RDF_HAS_PAGE_COUNT)) {
 425                pr_debug("Missing rd_pages= parameter\n");
 426                return -EINVAL;
 427        }
 428
 429        return 0;
 430}
 431
 432static ssize_t rd_show_configfs_dev_params(
 433        struct se_hba *hba,
 434        struct se_subsystem_dev *se_dev,
 435        char *b)
 436{
 437        struct rd_dev *rd_dev = se_dev->se_dev_su_ptr;
 438        ssize_t bl = sprintf(b, "TCM RamDisk ID: %u  RamDisk Makeup: rd_mcp\n",
 439                        rd_dev->rd_dev_id);
 440        bl += sprintf(b + bl, "        PAGES/PAGE_SIZE: %u*%lu"
 441                        "  SG_table_count: %u\n", rd_dev->rd_page_count,
 442                        PAGE_SIZE, rd_dev->sg_table_count);
 443        return bl;
 444}
 445
 446static u32 rd_get_device_rev(struct se_device *dev)
 447{
 448        return SCSI_SPC_2; /* Returns SPC-3 in Initiator Data */
 449}
 450
 451static u32 rd_get_device_type(struct se_device *dev)
 452{
 453        return TYPE_DISK;
 454}
 455
 456static sector_t rd_get_blocks(struct se_device *dev)
 457{
 458        struct rd_dev *rd_dev = dev->dev_ptr;
 459        unsigned long long blocks_long = ((rd_dev->rd_page_count * PAGE_SIZE) /
 460                        dev->se_sub_dev->se_dev_attrib.block_size) - 1;
 461
 462        return blocks_long;
 463}
 464
 465static struct spc_ops rd_spc_ops = {
 466        .execute_rw             = rd_execute_rw,
 467};
 468
 469static int rd_parse_cdb(struct se_cmd *cmd)
 470{
 471        return sbc_parse_cdb(cmd, &rd_spc_ops);
 472}
 473
 474static struct se_subsystem_api rd_mcp_template = {
 475        .name                   = "rd_mcp",
 476        .transport_type         = TRANSPORT_PLUGIN_VHBA_VDEV,
 477        .attach_hba             = rd_attach_hba,
 478        .detach_hba             = rd_detach_hba,
 479        .allocate_virtdevice    = rd_allocate_virtdevice,
 480        .create_virtdevice      = rd_create_virtdevice,
 481        .free_device            = rd_free_device,
 482        .parse_cdb              = rd_parse_cdb,
 483        .check_configfs_dev_params = rd_check_configfs_dev_params,
 484        .set_configfs_dev_params = rd_set_configfs_dev_params,
 485        .show_configfs_dev_params = rd_show_configfs_dev_params,
 486        .get_device_rev         = rd_get_device_rev,
 487        .get_device_type        = rd_get_device_type,
 488        .get_blocks             = rd_get_blocks,
 489};
 490
 491int __init rd_module_init(void)
 492{
 493        int ret;
 494
 495        ret = transport_subsystem_register(&rd_mcp_template);
 496        if (ret < 0) {
 497                return ret;
 498        }
 499
 500        return 0;
 501}
 502
 503void rd_module_exit(void)
 504{
 505        transport_subsystem_release(&rd_mcp_template);
 506}
 507
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