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        u32 i;
 260        struct rd_dev_sg_table *sg_table;
 261
 262        for (i = 0; i < rd_dev->sg_table_count; i++) {
 263                sg_table = &rd_dev->sg_table_array[i];
 264                if ((sg_table->page_start_offset <= page) &&
 265                    (sg_table->page_end_offset >= page))
 266                        return sg_table;
 267        }
 268
 269        pr_err("Unable to locate struct rd_dev_sg_table for page: %u\n",
 270                        page);
 271
 272        return NULL;
 273}
 274
 275static sense_reason_t
 276rd_execute_rw(struct se_cmd *cmd)
 277{
 278        struct scatterlist *sgl = cmd->t_data_sg;
 279        u32 sgl_nents = cmd->t_data_nents;
 280        enum dma_data_direction data_direction = cmd->data_direction;
 281        struct se_device *se_dev = cmd->se_dev;
 282        struct rd_dev *dev = RD_DEV(se_dev);
 283        struct rd_dev_sg_table *table;
 284        struct scatterlist *rd_sg;
 285        struct sg_mapping_iter m;
 286        u32 rd_offset;
 287        u32 rd_size;
 288        u32 rd_page;
 289        u32 src_len;
 290        u64 tmp;
 291
 292        tmp = cmd->t_task_lba * se_dev->dev_attrib.block_size;
 293        rd_offset = do_div(tmp, PAGE_SIZE);
 294        rd_page = tmp;
 295        rd_size = cmd->data_length;
 296
 297        table = rd_get_sg_table(dev, rd_page);
 298        if (!table)
 299                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 300
 301        rd_sg = &table->sg_table[rd_page - table->page_start_offset];
 302
 303        pr_debug("RD[%u]: %s LBA: %llu, Size: %u Page: %u, Offset: %u\n",
 304                        dev->rd_dev_id,
 305                        data_direction == DMA_FROM_DEVICE ? "Read" : "Write",
 306                        cmd->t_task_lba, rd_size, rd_page, rd_offset);
 307
 308        src_len = PAGE_SIZE - rd_offset;
 309        sg_miter_start(&m, sgl, sgl_nents,
 310                        data_direction == DMA_FROM_DEVICE ?
 311                                SG_MITER_TO_SG : SG_MITER_FROM_SG);
 312        while (rd_size) {
 313                u32 len;
 314                void *rd_addr;
 315
 316                sg_miter_next(&m);
 317                len = min((u32)m.length, src_len);
 318                m.consumed = len;
 319
 320                rd_addr = sg_virt(rd_sg) + rd_offset;
 321
 322                if (data_direction == DMA_FROM_DEVICE)
 323                        memcpy(m.addr, rd_addr, len);
 324                else
 325                        memcpy(rd_addr, m.addr, len);
 326
 327                rd_size -= len;
 328                if (!rd_size)
 329                        continue;
 330
 331                src_len -= len;
 332                if (src_len) {
 333                        rd_offset += len;
 334                        continue;
 335                }
 336
 337                /* rd page completed, next one please */
 338                rd_page++;
 339                rd_offset = 0;
 340                src_len = PAGE_SIZE;
 341                if (rd_page <= table->page_end_offset) {
 342                        rd_sg++;
 343                        continue;
 344                }
 345
 346                table = rd_get_sg_table(dev, rd_page);
 347                if (!table) {
 348                        sg_miter_stop(&m);
 349                        return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 350                }
 351
 352                /* since we increment, the first sg entry is correct */
 353                rd_sg = table->sg_table;
 354        }
 355        sg_miter_stop(&m);
 356
 357        target_complete_cmd(cmd, SAM_STAT_GOOD);
 358        return 0;
 359}
 360
 361enum {
 362        Opt_rd_pages, Opt_err
 363};
 364
 365static match_table_t tokens = {
 366        {Opt_rd_pages, "rd_pages=%d"},
 367        {Opt_err, NULL}
 368};
 369
 370static ssize_t rd_set_configfs_dev_params(struct se_device *dev,
 371                const char *page, ssize_t count)
 372{
 373        struct rd_dev *rd_dev = RD_DEV(dev);
 374        char *orig, *ptr, *opts;
 375        substring_t args[MAX_OPT_ARGS];
 376        int ret = 0, arg, token;
 377
 378        opts = kstrdup(page, GFP_KERNEL);
 379        if (!opts)
 380                return -ENOMEM;
 381
 382        orig = opts;
 383
 384        while ((ptr = strsep(&opts, ",\n")) != NULL) {
 385                if (!*ptr)
 386                        continue;
 387
 388                token = match_token(ptr, tokens, args);
 389                switch (token) {
 390                case Opt_rd_pages:
 391                        match_int(args, &arg);
 392                        rd_dev->rd_page_count = arg;
 393                        pr_debug("RAMDISK: Referencing Page"
 394                                " Count: %u\n", rd_dev->rd_page_count);
 395                        rd_dev->rd_flags |= RDF_HAS_PAGE_COUNT;
 396                        break;
 397                default:
 398                        break;
 399                }
 400        }
 401
 402        kfree(orig);
 403        return (!ret) ? count : ret;
 404}
 405
 406static ssize_t rd_show_configfs_dev_params(struct se_device *dev, char *b)
 407{
 408        struct rd_dev *rd_dev = RD_DEV(dev);
 409
 410        ssize_t bl = sprintf(b, "TCM RamDisk ID: %u  RamDisk Makeup: rd_mcp\n",
 411                        rd_dev->rd_dev_id);
 412        bl += sprintf(b + bl, "        PAGES/PAGE_SIZE: %u*%lu"
 413                        "  SG_table_count: %u\n", rd_dev->rd_page_count,
 414                        PAGE_SIZE, rd_dev->sg_table_count);
 415        return bl;
 416}
 417
 418static sector_t rd_get_blocks(struct se_device *dev)
 419{
 420        struct rd_dev *rd_dev = RD_DEV(dev);
 421
 422        unsigned long long blocks_long = ((rd_dev->rd_page_count * PAGE_SIZE) /
 423                        dev->dev_attrib.block_size) - 1;
 424
 425        return blocks_long;
 426}
 427
 428static struct sbc_ops rd_sbc_ops = {
 429        .execute_rw             = rd_execute_rw,
 430};
 431
 432static sense_reason_t
 433rd_parse_cdb(struct se_cmd *cmd)
 434{
 435        return sbc_parse_cdb(cmd, &rd_sbc_ops);
 436}
 437
 438static struct se_subsystem_api rd_mcp_template = {
 439        .name                   = "rd_mcp",
 440        .inquiry_prod           = "RAMDISK-MCP",
 441        .inquiry_rev            = RD_MCP_VERSION,
 442        .transport_type         = TRANSPORT_PLUGIN_VHBA_VDEV,
 443        .attach_hba             = rd_attach_hba,
 444        .detach_hba             = rd_detach_hba,
 445        .alloc_device           = rd_alloc_device,
 446        .configure_device       = rd_configure_device,
 447        .free_device            = rd_free_device,
 448        .parse_cdb              = rd_parse_cdb,
 449        .set_configfs_dev_params = rd_set_configfs_dev_params,
 450        .show_configfs_dev_params = rd_show_configfs_dev_params,
 451        .get_device_type        = sbc_get_device_type,
 452        .get_blocks             = rd_get_blocks,
 453};
 454
 455int __init rd_module_init(void)
 456{
 457        int ret;
 458
 459        ret = transport_subsystem_register(&rd_mcp_template);
 460        if (ret < 0) {
 461                return ret;
 462        }
 463
 464        return 0;
 465}
 466
 467void rd_module_exit(void)
 468{
 469        transport_subsystem_release(&rd_mcp_template);
 470}
 471
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