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 * (c) Copyright 2003-2012 RisingTide Systems LLC.
   8 *
   9 * Nicholas A. Bellinger <nab@kernel.org>
  10 *
  11 * This program is free software; you can redistribute it and/or modify
  12 * it under the terms of the GNU General Public License as published by
  13 * the Free Software Foundation; either version 2 of the License, or
  14 * (at your option) any later version.
  15 *
  16 * This program is distributed in the hope that it will be useful,
  17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 * GNU General Public License for more details.
  20 *
  21 * You should have received a copy of the GNU General Public License
  22 * along with this program; if not, write to the Free Software
  23 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  24 *
  25 ******************************************************************************/
  26
  27#include <linux/string.h>
  28#include <linux/parser.h>
  29#include <linux/timer.h>
  30#include <linux/blkdev.h>
  31#include <linux/slab.h>
  32#include <linux/spinlock.h>
  33#include <scsi/scsi.h>
  34#include <scsi/scsi_host.h>
  35
  36#include <target/target_core_base.h>
  37#include <target/target_core_backend.h>
  38
  39#include "target_core_rd.h"
  40
  41static inline struct rd_dev *RD_DEV(struct se_device *dev)
  42{
  43        return container_of(dev, struct rd_dev, dev);
  44}
  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 struct se_device *rd_alloc_device(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->dev;
 213}
 214
 215static int rd_configure_device(struct se_device *dev)
 216{
 217        struct rd_dev *rd_dev = RD_DEV(dev);
 218        struct rd_host *rd_host = dev->se_hba->hba_ptr;
 219        int ret;
 220
 221        if (!(rd_dev->rd_flags & RDF_HAS_PAGE_COUNT)) {
 222                pr_debug("Missing rd_pages= parameter\n");
 223                return -EINVAL;
 224        }
 225
 226        ret = rd_build_device_space(rd_dev);
 227        if (ret < 0)
 228                goto fail;
 229
 230        dev->dev_attrib.hw_block_size = RD_BLOCKSIZE;
 231        dev->dev_attrib.hw_max_sectors = UINT_MAX;
 232        dev->dev_attrib.hw_queue_depth = RD_MAX_DEVICE_QUEUE_DEPTH;
 233
 234        rd_dev->rd_dev_id = rd_host->rd_host_dev_id_count++;
 235
 236        pr_debug("CORE_RD[%u] - Added TCM MEMCPY Ramdisk Device ID: %u of"
 237                " %u pages in %u tables, %lu total bytes\n",
 238                rd_host->rd_host_id, rd_dev->rd_dev_id, rd_dev->rd_page_count,
 239                rd_dev->sg_table_count,
 240                (unsigned long)(rd_dev->rd_page_count * PAGE_SIZE));
 241
 242        return 0;
 243
 244fail:
 245        rd_release_device_space(rd_dev);
 246        return ret;
 247}
 248
 249static void rd_free_device(struct se_device *dev)
 250{
 251        struct rd_dev *rd_dev = RD_DEV(dev);
 252
 253        rd_release_device_space(rd_dev);
 254        kfree(rd_dev);
 255}
 256
 257static struct rd_dev_sg_table *rd_get_sg_table(struct rd_dev *rd_dev, u32 page)
 258{
 259        struct rd_dev_sg_table *sg_table;
 260        u32 i, sg_per_table = (RD_MAX_ALLOCATION_SIZE /
 261                                sizeof(struct scatterlist));
 262
 263        i = page / sg_per_table;
 264        if (i < rd_dev->sg_table_count) {
 265                sg_table = &rd_dev->sg_table_array[i];
 266                if ((sg_table->page_start_offset <= page) &&
 267                    (sg_table->page_end_offset >= page))
 268                        return sg_table;
 269        }
 270
 271        pr_err("Unable to locate struct rd_dev_sg_table for page: %u\n",
 272                        page);
 273
 274        return NULL;
 275}
 276
 277static sense_reason_t
 278rd_execute_rw(struct se_cmd *cmd)
 279{
 280        struct scatterlist *sgl = cmd->t_data_sg;
 281        u32 sgl_nents = cmd->t_data_nents;
 282        enum dma_data_direction data_direction = cmd->data_direction;
 283        struct se_device *se_dev = cmd->se_dev;
 284        struct rd_dev *dev = RD_DEV(se_dev);
 285        struct rd_dev_sg_table *table;
 286        struct scatterlist *rd_sg;
 287        struct sg_mapping_iter m;
 288        u32 rd_offset;
 289        u32 rd_size;
 290        u32 rd_page;
 291        u32 src_len;
 292        u64 tmp;
 293
 294        if (dev->rd_flags & RDF_NULLIO) {
 295                target_complete_cmd(cmd, SAM_STAT_GOOD);
 296                return 0;
 297        }
 298
 299        tmp = cmd->t_task_lba * se_dev->dev_attrib.block_size;
 300        rd_offset = do_div(tmp, PAGE_SIZE);
 301        rd_page = tmp;
 302        rd_size = cmd->data_length;
 303
 304        table = rd_get_sg_table(dev, rd_page);
 305        if (!table)
 306                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 307
 308        rd_sg = &table->sg_table[rd_page - table->page_start_offset];
 309
 310        pr_debug("RD[%u]: %s LBA: %llu, Size: %u Page: %u, Offset: %u\n",
 311                        dev->rd_dev_id,
 312                        data_direction == DMA_FROM_DEVICE ? "Read" : "Write",
 313                        cmd->t_task_lba, rd_size, rd_page, rd_offset);
 314
 315        src_len = PAGE_SIZE - rd_offset;
 316        sg_miter_start(&m, sgl, sgl_nents,
 317                        data_direction == DMA_FROM_DEVICE ?
 318                                SG_MITER_TO_SG : SG_MITER_FROM_SG);
 319        while (rd_size) {
 320                u32 len;
 321                void *rd_addr;
 322
 323                sg_miter_next(&m);
 324                if (!(u32)m.length) {
 325                        pr_debug("RD[%u]: invalid sgl %p len %zu\n",
 326                                 dev->rd_dev_id, m.addr, m.length);
 327                        sg_miter_stop(&m);
 328                        return TCM_INCORRECT_AMOUNT_OF_DATA;
 329                }
 330                len = min((u32)m.length, src_len);
 331                if (len > rd_size) {
 332                        pr_debug("RD[%u]: size underrun page %d offset %d "
 333                                 "size %d\n", dev->rd_dev_id,
 334                                 rd_page, rd_offset, rd_size);
 335                        len = rd_size;
 336                }
 337                m.consumed = len;
 338
 339                rd_addr = sg_virt(rd_sg) + rd_offset;
 340
 341                if (data_direction == DMA_FROM_DEVICE)
 342                        memcpy(m.addr, rd_addr, len);
 343                else
 344                        memcpy(rd_addr, m.addr, len);
 345
 346                rd_size -= len;
 347                if (!rd_size)
 348                        continue;
 349
 350                src_len -= len;
 351                if (src_len) {
 352                        rd_offset += len;
 353                        continue;
 354                }
 355
 356                /* rd page completed, next one please */
 357                rd_page++;
 358                rd_offset = 0;
 359                src_len = PAGE_SIZE;
 360                if (rd_page <= table->page_end_offset) {
 361                        rd_sg++;
 362                        continue;
 363                }
 364
 365                table = rd_get_sg_table(dev, rd_page);
 366                if (!table) {
 367                        sg_miter_stop(&m);
 368                        return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 369                }
 370
 371                /* since we increment, the first sg entry is correct */
 372                rd_sg = table->sg_table;
 373        }
 374        sg_miter_stop(&m);
 375
 376        target_complete_cmd(cmd, SAM_STAT_GOOD);
 377        return 0;
 378}
 379
 380enum {
 381        Opt_rd_pages, Opt_rd_nullio, Opt_err
 382};
 383
 384static match_table_t tokens = {
 385        {Opt_rd_pages, "rd_pages=%d"},
 386        {Opt_rd_nullio, "rd_nullio=%d"},
 387        {Opt_err, NULL}
 388};
 389
 390static ssize_t rd_set_configfs_dev_params(struct se_device *dev,
 391                const char *page, ssize_t count)
 392{
 393        struct rd_dev *rd_dev = RD_DEV(dev);
 394        char *orig, *ptr, *opts;
 395        substring_t args[MAX_OPT_ARGS];
 396        int ret = 0, arg, token;
 397
 398        opts = kstrdup(page, GFP_KERNEL);
 399        if (!opts)
 400                return -ENOMEM;
 401
 402        orig = opts;
 403
 404        while ((ptr = strsep(&opts, ",\n")) != NULL) {
 405                if (!*ptr)
 406                        continue;
 407
 408                token = match_token(ptr, tokens, args);
 409                switch (token) {
 410                case Opt_rd_pages:
 411                        match_int(args, &arg);
 412                        rd_dev->rd_page_count = arg;
 413                        pr_debug("RAMDISK: Referencing Page"
 414                                " Count: %u\n", rd_dev->rd_page_count);
 415                        rd_dev->rd_flags |= RDF_HAS_PAGE_COUNT;
 416                        break;
 417                case Opt_rd_nullio:
 418                        match_int(args, &arg);
 419                        if (arg != 1)
 420                                break;
 421
 422                        pr_debug("RAMDISK: Setting NULLIO flag: %d\n", arg);
 423                        rd_dev->rd_flags |= RDF_NULLIO;
 424                        break;
 425                default:
 426                        break;
 427                }
 428        }
 429
 430        kfree(orig);
 431        return (!ret) ? count : ret;
 432}
 433
 434static ssize_t rd_show_configfs_dev_params(struct se_device *dev, char *b)
 435{
 436        struct rd_dev *rd_dev = RD_DEV(dev);
 437
 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  nullio: %d\n", rd_dev->rd_page_count,
 442                        PAGE_SIZE, rd_dev->sg_table_count,
 443                        !!(rd_dev->rd_flags & RDF_NULLIO));
 444        return bl;
 445}
 446
 447static sector_t rd_get_blocks(struct se_device *dev)
 448{
 449        struct rd_dev *rd_dev = RD_DEV(dev);
 450
 451        unsigned long long blocks_long = ((rd_dev->rd_page_count * PAGE_SIZE) /
 452                        dev->dev_attrib.block_size) - 1;
 453
 454        return blocks_long;
 455}
 456
 457static struct sbc_ops rd_sbc_ops = {
 458        .execute_rw             = rd_execute_rw,
 459};
 460
 461static sense_reason_t
 462rd_parse_cdb(struct se_cmd *cmd)
 463{
 464        return sbc_parse_cdb(cmd, &rd_sbc_ops);
 465}
 466
 467static struct se_subsystem_api rd_mcp_template = {
 468        .name                   = "rd_mcp",
 469        .inquiry_prod           = "RAMDISK-MCP",
 470        .inquiry_rev            = RD_MCP_VERSION,
 471        .transport_type         = TRANSPORT_PLUGIN_VHBA_VDEV,
 472        .attach_hba             = rd_attach_hba,
 473        .detach_hba             = rd_detach_hba,
 474        .alloc_device           = rd_alloc_device,
 475        .configure_device       = rd_configure_device,
 476        .free_device            = rd_free_device,
 477        .parse_cdb              = rd_parse_cdb,
 478        .set_configfs_dev_params = rd_set_configfs_dev_params,
 479        .show_configfs_dev_params = rd_show_configfs_dev_params,
 480        .get_device_type        = sbc_get_device_type,
 481        .get_blocks             = rd_get_blocks,
 482};
 483
 484int __init rd_module_init(void)
 485{
 486        int ret;
 487
 488        ret = transport_subsystem_register(&rd_mcp_template);
 489        if (ret < 0) {
 490                return ret;
 491        }
 492
 493        return 0;
 494}
 495
 496void rd_module_exit(void)
 497{
 498        transport_subsystem_release(&rd_mcp_template);
 499}
 500
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