drivers/target/target_core_rd.c

   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
  41 static 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  */
  50 static 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
  71 static 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  */
  86 static 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  */
 128 static 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
 199 static 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
 215 static 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
 244 fail:
 245         rd_release_device_space(rd_dev);
 246         return ret;
 247 }
 248
 249 static 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
 257 static 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
 275 static sense_reason_t
 276 rd_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
 361 enum {
 362         Opt_rd_pages, Opt_err
 363 };
 364
 365 static match_table_t tokens = {
 366         {Opt_rd_pages, "rd_pages=%d"},
 367         {Opt_err, NULL}
 368 };
 369
 370 static 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
 406 static 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
 418 static 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
 428 static struct sbc_ops rd_sbc_ops = {
 429         .execute_rw             = rd_execute_rw,
 430 };
 431
 432 static sense_reason_t
 433 rd_parse_cdb(struct se_cmd *cmd)
 434 {
 435         return sbc_parse_cdb(cmd, &rd_sbc_ops);
 436 }
 437
 438 static 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
 455 int __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
 467 void rd_module_exit(void)
 468 {
 469         transport_subsystem_release(&rd_mcp_template);
 470 }