drivers/target/target_core_iblock.c

   1 /*******************************************************************************
   2  * Filename:  target_core_iblock.c
   3  *
   4  * This file contains the Storage Engine  <-> Linux BlockIO 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/fs.h>
  34 #include <linux/blkdev.h>
  35 #include <linux/slab.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/bio.h>
  38 #include <linux/genhd.h>
  39 #include <linux/file.h>
  40 #include <scsi/scsi.h>
  41 #include <scsi/scsi_host.h>
  42
  43 #include <target/target_core_base.h>
  44 #include <target/target_core_device.h>
  45 #include <target/target_core_transport.h>
  46
  47 #include "target_core_iblock.h"
  48
  49 static struct se_subsystem_api iblock_template;
  50
  51 static void iblock_bio_done(struct bio *, int);
  52
  53 /*      iblock_attach_hba(): (Part of se_subsystem_api_t template)
  54  *
  55  *
  56  */
  57 static int iblock_attach_hba(struct se_hba *hba, u32 host_id)
  58 {
  59         struct iblock_hba *ib_host;
  60
  61         ib_host = kzalloc(sizeof(struct iblock_hba), GFP_KERNEL);
  62         if (!ib_host) {
  63                 pr_err("Unable to allocate memory for"
  64                                 " struct iblock_hba\n");
  65                 return -ENOMEM;
  66         }
  67
  68         ib_host->iblock_host_id = host_id;
  69
  70         hba->hba_ptr = ib_host;
  71
  72         pr_debug("CORE_HBA[%d] - TCM iBlock HBA Driver %s on"
  73                 " Generic Target Core Stack %s\n", hba->hba_id,
  74                 IBLOCK_VERSION, TARGET_CORE_MOD_VERSION);
  75
  76         pr_debug("CORE_HBA[%d] - Attached iBlock HBA: %u to Generic\n",
  77                 hba->hba_id, ib_host->iblock_host_id);
  78
  79         return 0;
  80 }
  81
  82 static void iblock_detach_hba(struct se_hba *hba)
  83 {
  84         struct iblock_hba *ib_host = hba->hba_ptr;
  85
  86         pr_debug("CORE_HBA[%d] - Detached iBlock HBA: %u from Generic"
  87                 " Target Core\n", hba->hba_id, ib_host->iblock_host_id);
  88
  89         kfree(ib_host);
  90         hba->hba_ptr = NULL;
  91 }
  92
  93 static void *iblock_allocate_virtdevice(struct se_hba *hba, const char *name)
  94 {
  95         struct iblock_dev *ib_dev = NULL;
  96         struct iblock_hba *ib_host = hba->hba_ptr;
  97
  98         ib_dev = kzalloc(sizeof(struct iblock_dev), GFP_KERNEL);
  99         if (!ib_dev) {
 100                 pr_err("Unable to allocate struct iblock_dev\n");
 101                 return NULL;
 102         }
 103         ib_dev->ibd_host = ib_host;
 104
 105         pr_debug( "IBLOCK: Allocated ib_dev for %s\n", name);
 106
 107         return ib_dev;
 108 }
 109
 110 static struct se_device *iblock_create_virtdevice(
 111         struct se_hba *hba,
 112         struct se_subsystem_dev *se_dev,
 113         void *p)
 114 {
 115         struct iblock_dev *ib_dev = p;
 116         struct se_device *dev;
 117         struct se_dev_limits dev_limits;
 118         struct block_device *bd = NULL;
 119         struct request_queue *q;
 120         struct queue_limits *limits;
 121         u32 dev_flags = 0;
 122         int ret = -EINVAL;
 123
 124         if (!ib_dev) {
 125                 pr_err("Unable to locate struct iblock_dev parameter\n");
 126                 return ERR_PTR(ret);
 127         }
 128         memset(&dev_limits, 0, sizeof(struct se_dev_limits));
 129         /*
 130          * These settings need to be made tunable..
 131          */
 132         ib_dev->ibd_bio_set = bioset_create(32, 64);
 133         if (!ib_dev->ibd_bio_set) {
 134                 pr_err("IBLOCK: Unable to create bioset()\n");
 135                 return ERR_PTR(-ENOMEM);
 136         }
 137         pr_debug("IBLOCK: Created bio_set()\n");
 138         /*
 139          * iblock_check_configfs_dev_params() ensures that ib_dev->ibd_udev_path
 140          * must already have been set in order for echo 1 > $HBA/$DEV/enable to run.
 141          */
 142         pr_debug( "IBLOCK: Claiming struct block_device: %s\n",
 143                         ib_dev->ibd_udev_path);
 144
 145         bd = blkdev_get_by_path(ib_dev->ibd_udev_path,
 146                                 FMODE_WRITE|FMODE_READ|FMODE_EXCL, ib_dev);
 147         if (IS_ERR(bd)) {
 148                 ret = PTR_ERR(bd);
 149                 goto failed;
 150         }
 151         /*
 152          * Setup the local scope queue_limits from struct request_queue->limits
 153          * to pass into transport_add_device_to_core_hba() as struct se_dev_limits.
 154          */
 155         q = bdev_get_queue(bd);
 156         limits = &dev_limits.limits;
 157         limits->logical_block_size = bdev_logical_block_size(bd);
 158         limits->max_hw_sectors = queue_max_hw_sectors(q);
 159         limits->max_sectors = queue_max_sectors(q);
 160         dev_limits.hw_queue_depth = q->nr_requests;
 161         dev_limits.queue_depth = q->nr_requests;
 162
 163         ib_dev->ibd_bd = bd;
 164
 165         dev = transport_add_device_to_core_hba(hba,
 166                         &iblock_template, se_dev, dev_flags, ib_dev,
 167                         &dev_limits, "IBLOCK", IBLOCK_VERSION);
 168         if (!dev)
 169                 goto failed;
 170
 171         /*
 172          * Check if the underlying struct block_device request_queue supports
 173          * the QUEUE_FLAG_DISCARD bit for UNMAP/WRITE_SAME in SCSI + TRIM
 174          * in ATA and we need to set TPE=1
 175          */
 176         if (blk_queue_discard(q)) {
 177                 dev->se_sub_dev->se_dev_attrib.max_unmap_lba_count =
 178                                 q->limits.max_discard_sectors;
 179                 /*
 180                  * Currently hardcoded to 1 in Linux/SCSI code..
 181                  */
 182                 dev->se_sub_dev->se_dev_attrib.max_unmap_block_desc_count = 1;
 183                 dev->se_sub_dev->se_dev_attrib.unmap_granularity =
 184                                 q->limits.discard_granularity;
 185                 dev->se_sub_dev->se_dev_attrib.unmap_granularity_alignment =
 186                                 q->limits.discard_alignment;
 187
 188                 pr_debug("IBLOCK: BLOCK Discard support available,"
 189                                 " disabled by default\n");
 190         }
 191
 192         if (blk_queue_nonrot(q))
 193                 dev->se_sub_dev->se_dev_attrib.is_nonrot = 1;
 194
 195         return dev;
 196
 197 failed:
 198         if (ib_dev->ibd_bio_set) {
 199                 bioset_free(ib_dev->ibd_bio_set);
 200                 ib_dev->ibd_bio_set = NULL;
 201         }
 202         ib_dev->ibd_bd = NULL;
 203         return ERR_PTR(ret);
 204 }
 205
 206 static void iblock_free_device(void *p)
 207 {
 208         struct iblock_dev *ib_dev = p;
 209
 210         if (ib_dev->ibd_bd != NULL)
 211                 blkdev_put(ib_dev->ibd_bd, FMODE_WRITE|FMODE_READ|FMODE_EXCL);
 212         if (ib_dev->ibd_bio_set != NULL)
 213                 bioset_free(ib_dev->ibd_bio_set);
 214         kfree(ib_dev);
 215 }
 216
 217 static inline struct iblock_req *IBLOCK_REQ(struct se_task *task)
 218 {
 219         return container_of(task, struct iblock_req, ib_task);
 220 }
 221
 222 static struct se_task *
 223 iblock_alloc_task(unsigned char *cdb)
 224 {
 225         struct iblock_req *ib_req;
 226
 227         ib_req = kzalloc(sizeof(struct iblock_req), GFP_KERNEL);
 228         if (!ib_req) {
 229                 pr_err("Unable to allocate memory for struct iblock_req\n");
 230                 return NULL;
 231         }
 232
 233         atomic_set(&ib_req->ib_bio_cnt, 0);
 234         return &ib_req->ib_task;
 235 }
 236
 237 static unsigned long long iblock_emulate_read_cap_with_block_size(
 238         struct se_device *dev,
 239         struct block_device *bd,
 240         struct request_queue *q)
 241 {
 242         unsigned long long blocks_long = (div_u64(i_size_read(bd->bd_inode),
 243                                         bdev_logical_block_size(bd)) - 1);
 244         u32 block_size = bdev_logical_block_size(bd);
 245
 246         if (block_size == dev->se_sub_dev->se_dev_attrib.block_size)
 247                 return blocks_long;
 248
 249         switch (block_size) {
 250         case 4096:
 251                 switch (dev->se_sub_dev->se_dev_attrib.block_size) {
 252                 case 2048:
 253                         blocks_long <<= 1;
 254                         break;
 255                 case 1024:
 256                         blocks_long <<= 2;
 257                         break;
 258                 case 512:
 259                         blocks_long <<= 3;
 260                 default:
 261                         break;
 262                 }
 263                 break;
 264         case 2048:
 265                 switch (dev->se_sub_dev->se_dev_attrib.block_size) {
 266                 case 4096:
 267                         blocks_long >>= 1;
 268                         break;
 269                 case 1024:
 270                         blocks_long <<= 1;
 271                         break;
 272                 case 512:
 273                         blocks_long <<= 2;
 274                         break;
 275                 default:
 276                         break;
 277                 }
 278                 break;
 279         case 1024:
 280                 switch (dev->se_sub_dev->se_dev_attrib.block_size) {
 281                 case 4096:
 282                         blocks_long >>= 2;
 283                         break;
 284                 case 2048:
 285                         blocks_long >>= 1;
 286                         break;
 287                 case 512:
 288                         blocks_long <<= 1;
 289                         break;
 290                 default:
 291                         break;
 292                 }
 293                 break;
 294         case 512:
 295                 switch (dev->se_sub_dev->se_dev_attrib.block_size) {
 296                 case 4096:
 297                         blocks_long >>= 3;
 298                         break;
 299                 case 2048:
 300                         blocks_long >>= 2;
 301                         break;
 302                 case 1024:
 303                         blocks_long >>= 1;
 304                         break;
 305                 default:
 306                         break;
 307                 }
 308                 break;
 309         default:
 310                 break;
 311         }
 312
 313         return blocks_long;
 314 }
 315
 316 /*
 317  * Emulate SYCHRONIZE_CACHE_*
 318  */
 319 static void iblock_emulate_sync_cache(struct se_task *task)
 320 {
 321         struct se_cmd *cmd = task->task_se_cmd;
 322         struct iblock_dev *ib_dev = cmd->se_dev->dev_ptr;
 323         int immed = (cmd->t_task_cdb[1] & 0x2);
 324         sector_t error_sector;
 325         int ret;
 326
 327         /*
 328          * If the Immediate bit is set, queue up the GOOD response
 329          * for this SYNCHRONIZE_CACHE op
 330          */
 331         if (immed)
 332                 transport_complete_sync_cache(cmd, 1);
 333
 334         /*
 335          * blkdev_issue_flush() does not support a specifying a range, so
 336          * we have to flush the entire cache.
 337          */
 338         ret = blkdev_issue_flush(ib_dev->ibd_bd, GFP_KERNEL, &error_sector);
 339         if (ret != 0) {
 340                 pr_err("IBLOCK: block_issue_flush() failed: %d "
 341                         " error_sector: %llu\n", ret,
 342                         (unsigned long long)error_sector);
 343         }
 344
 345         if (!immed)
 346                 transport_complete_sync_cache(cmd, ret == 0);
 347 }
 348
 349 /*
 350  * Tell TCM Core that we are capable of WriteCache emulation for
 351  * an underlying struct se_device.
 352  */
 353 static int iblock_emulated_write_cache(struct se_device *dev)
 354 {
 355         return 1;
 356 }
 357
 358 static int iblock_emulated_dpo(struct se_device *dev)
 359 {
 360         return 0;
 361 }
 362
 363 /*
 364  * Tell TCM Core that we will be emulating Forced Unit Access (FUA) for WRITEs
 365  * for TYPE_DISK.
 366  */
 367 static int iblock_emulated_fua_write(struct se_device *dev)
 368 {
 369         return 1;
 370 }
 371
 372 static int iblock_emulated_fua_read(struct se_device *dev)
 373 {
 374         return 0;
 375 }
 376
 377 static int iblock_do_discard(struct se_device *dev, sector_t lba, u32 range)
 378 {
 379         struct iblock_dev *ibd = dev->dev_ptr;
 380         struct block_device *bd = ibd->ibd_bd;
 381         int barrier = 0;
 382
 383         return blkdev_issue_discard(bd, lba, range, GFP_KERNEL, barrier);
 384 }
 385
 386 static void iblock_free_task(struct se_task *task)
 387 {
 388         kfree(IBLOCK_REQ(task));
 389 }
 390
 391 enum {
 392         Opt_udev_path, Opt_force, Opt_err
 393 };
 394
 395 static match_table_t tokens = {
 396         {Opt_udev_path, "udev_path=%s"},
 397         {Opt_force, "force=%d"},
 398         {Opt_err, NULL}
 399 };
 400
 401 static ssize_t iblock_set_configfs_dev_params(struct se_hba *hba,
 402                                                struct se_subsystem_dev *se_dev,
 403                                                const char *page, ssize_t count)
 404 {
 405         struct iblock_dev *ib_dev = se_dev->se_dev_su_ptr;
 406         char *orig, *ptr, *arg_p, *opts;
 407         substring_t args[MAX_OPT_ARGS];
 408         int ret = 0, token;
 409
 410         opts = kstrdup(page, GFP_KERNEL);
 411         if (!opts)
 412                 return -ENOMEM;
 413
 414         orig = opts;
 415
 416         while ((ptr = strsep(&opts, ",")) != NULL) {
 417                 if (!*ptr)
 418                         continue;
 419
 420                 token = match_token(ptr, tokens, args);
 421                 switch (token) {
 422                 case Opt_udev_path:
 423                         if (ib_dev->ibd_bd) {
 424                                 pr_err("Unable to set udev_path= while"
 425                                         " ib_dev->ibd_bd exists\n");
 426                                 ret = -EEXIST;
 427                                 goto out;
 428                         }
 429                         arg_p = match_strdup(&args[0]);
 430                         if (!arg_p) {
 431                                 ret = -ENOMEM;
 432                                 break;
 433                         }
 434                         snprintf(ib_dev->ibd_udev_path, SE_UDEV_PATH_LEN,
 435                                         "%s", arg_p);
 436                         kfree(arg_p);
 437                         pr_debug("IBLOCK: Referencing UDEV path: %s\n",
 438                                         ib_dev->ibd_udev_path);
 439                         ib_dev->ibd_flags |= IBDF_HAS_UDEV_PATH;
 440                         break;
 441                 case Opt_force:
 442                         break;
 443                 default:
 444                         break;
 445                 }
 446         }
 447
 448 out:
 449         kfree(orig);
 450         return (!ret) ? count : ret;
 451 }
 452
 453 static ssize_t iblock_check_configfs_dev_params(
 454         struct se_hba *hba,
 455         struct se_subsystem_dev *se_dev)
 456 {
 457         struct iblock_dev *ibd = se_dev->se_dev_su_ptr;
 458
 459         if (!(ibd->ibd_flags & IBDF_HAS_UDEV_PATH)) {
 460                 pr_err("Missing udev_path= parameters for IBLOCK\n");
 461                 return -EINVAL;
 462         }
 463
 464         return 0;
 465 }
 466
 467 static ssize_t iblock_show_configfs_dev_params(
 468         struct se_hba *hba,
 469         struct se_subsystem_dev *se_dev,
 470         char *b)
 471 {
 472         struct iblock_dev *ibd = se_dev->se_dev_su_ptr;
 473         struct block_device *bd = ibd->ibd_bd;
 474         char buf[BDEVNAME_SIZE];
 475         ssize_t bl = 0;
 476
 477         if (bd)
 478                 bl += sprintf(b + bl, "iBlock device: %s",
 479                                 bdevname(bd, buf));
 480         if (ibd->ibd_flags & IBDF_HAS_UDEV_PATH) {
 481                 bl += sprintf(b + bl, "  UDEV PATH: %s\n",
 482                                 ibd->ibd_udev_path);
 483         } else
 484                 bl += sprintf(b + bl, "\n");
 485
 486         bl += sprintf(b + bl, "        ");
 487         if (bd) {
 488                 bl += sprintf(b + bl, "Major: %d Minor: %d  %s\n",
 489                         MAJOR(bd->bd_dev), MINOR(bd->bd_dev), (!bd->bd_contains) ?
 490                         "" : (bd->bd_holder == (struct iblock_dev *)ibd) ?
 491                         "CLAIMED: IBLOCK" : "CLAIMED: OS");
 492         } else {
 493                 bl += sprintf(b + bl, "Major: 0 Minor: 0\n");
 494         }
 495
 496         return bl;
 497 }
 498
 499 static void iblock_bio_destructor(struct bio *bio)
 500 {
 501         struct se_task *task = bio->bi_private;
 502         struct iblock_dev *ib_dev = task->task_se_cmd->se_dev->dev_ptr;
 503
 504         bio_free(bio, ib_dev->ibd_bio_set);
 505 }
 506
 507 static struct bio *
 508 iblock_get_bio(struct se_task *task, sector_t lba, u32 sg_num)
 509 {
 510         struct iblock_dev *ib_dev = task->task_se_cmd->se_dev->dev_ptr;
 511         struct iblock_req *ib_req = IBLOCK_REQ(task);
 512         struct bio *bio;
 513
 514         bio = bio_alloc_bioset(GFP_NOIO, sg_num, ib_dev->ibd_bio_set);
 515         if (!bio) {
 516                 pr_err("Unable to allocate memory for bio\n");
 517                 return NULL;
 518         }
 519
 520         pr_debug("Allocated bio: %p task_sg_nents: %u using ibd_bio_set:"
 521                 " %p\n", bio, task->task_sg_nents, ib_dev->ibd_bio_set);
 522         pr_debug("Allocated bio: %p task_size: %u\n", bio, task->task_size);
 523
 524         bio->bi_bdev = ib_dev->ibd_bd;
 525         bio->bi_private = task;
 526         bio->bi_destructor = iblock_bio_destructor;
 527         bio->bi_end_io = &iblock_bio_done;
 528         bio->bi_sector = lba;
 529         atomic_inc(&ib_req->ib_bio_cnt);
 530
 531         pr_debug("Set bio->bi_sector: %llu\n", (unsigned long long)bio->bi_sector);
 532         pr_debug("Set ib_req->ib_bio_cnt: %d\n",
 533                         atomic_read(&ib_req->ib_bio_cnt));
 534         return bio;
 535 }
 536
 537 static int iblock_do_task(struct se_task *task)
 538 {
 539         struct se_cmd *cmd = task->task_se_cmd;
 540         struct se_device *dev = cmd->se_dev;
 541         struct bio *bio;
 542         struct bio_list list;
 543         struct scatterlist *sg;
 544         u32 i, sg_num = task->task_sg_nents;
 545         sector_t block_lba;
 546         struct blk_plug plug;
 547         int rw;
 548
 549         if (task->task_data_direction == DMA_TO_DEVICE) {
 550                 /*
 551                  * Force data to disk if we pretend to not have a volatile
 552                  * write cache, or the initiator set the Force Unit Access bit.
 553                  */
 554                 if (dev->se_sub_dev->se_dev_attrib.emulate_write_cache == 0 ||
 555                     (dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0 &&
 556                      task->task_se_cmd->t_tasks_fua))
 557                         rw = WRITE_FUA;
 558                 else
 559                         rw = WRITE;
 560         } else {
 561                 rw = READ;
 562         }
 563
 564         /*
 565          * Do starting conversion up from non 512-byte blocksize with
 566          * struct se_task SCSI blocksize into Linux/Block 512 units for BIO.
 567          */
 568         if (dev->se_sub_dev->se_dev_attrib.block_size == 4096)
 569                 block_lba = (task->task_lba << 3);
 570         else if (dev->se_sub_dev->se_dev_attrib.block_size == 2048)
 571                 block_lba = (task->task_lba << 2);
 572         else if (dev->se_sub_dev->se_dev_attrib.block_size == 1024)
 573                 block_lba = (task->task_lba << 1);
 574         else if (dev->se_sub_dev->se_dev_attrib.block_size == 512)
 575                 block_lba = task->task_lba;
 576         else {
 577                 pr_err("Unsupported SCSI -> BLOCK LBA conversion:"
 578                                 " %u\n", dev->se_sub_dev->se_dev_attrib.block_size);
 579                 return PYX_TRANSPORT_LU_COMM_FAILURE;
 580         }
 581
 582         bio = iblock_get_bio(task, block_lba, sg_num);
 583         if (!bio)
 584                 return PYX_TRANSPORT_OUT_OF_MEMORY_RESOURCES;
 585
 586         bio_list_init(&list);
 587         bio_list_add(&list, bio);
 588
 589         for_each_sg(task->task_sg, sg, task->task_sg_nents, i) {
 590                 /*
 591                  * XXX: if the length the device accepts is shorter than the
 592                  *      length of the S/G list entry this will cause and
 593                  *      endless loop.  Better hope no driver uses huge pages.
 594                  */
 595                 while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
 596                                 != sg->length) {
 597                         bio = iblock_get_bio(task, block_lba, sg_num);
 598                         if (!bio)
 599                                 goto fail;
 600                         bio_list_add(&list, bio);
 601                 }
 602
 603                 /* Always in 512 byte units for Linux/Block */
 604                 block_lba += sg->length >> IBLOCK_LBA_SHIFT;
 605                 sg_num--;
 606         }
 607
 608         blk_start_plug(&plug);
 609         while ((bio = bio_list_pop(&list)))
 610                 submit_bio(rw, bio);
 611         blk_finish_plug(&plug);
 612
 613         return PYX_TRANSPORT_SENT_TO_TRANSPORT;
 614
 615 fail:
 616         while ((bio = bio_list_pop(&list)))
 617                 bio_put(bio);
 618         return PYX_TRANSPORT_OUT_OF_MEMORY_RESOURCES;
 619 }
 620
 621 static u32 iblock_get_device_rev(struct se_device *dev)
 622 {
 623         return SCSI_SPC_2; /* Returns SPC-3 in Initiator Data */
 624 }
 625
 626 static u32 iblock_get_device_type(struct se_device *dev)
 627 {
 628         return TYPE_DISK;
 629 }
 630
 631 static sector_t iblock_get_blocks(struct se_device *dev)
 632 {
 633         struct iblock_dev *ibd = dev->dev_ptr;
 634         struct block_device *bd = ibd->ibd_bd;
 635         struct request_queue *q = bdev_get_queue(bd);
 636
 637         return iblock_emulate_read_cap_with_block_size(dev, bd, q);
 638 }
 639
 640 static void iblock_bio_done(struct bio *bio, int err)
 641 {
 642         struct se_task *task = bio->bi_private;
 643         struct iblock_req *ibr = IBLOCK_REQ(task);
 644
 645         /*
 646          * Set -EIO if !BIO_UPTODATE and the passed is still err=0
 647          */
 648         if (!test_bit(BIO_UPTODATE, &bio->bi_flags) && !err)
 649                 err = -EIO;
 650
 651         if (err != 0) {
 652                 pr_err("test_bit(BIO_UPTODATE) failed for bio: %p,"
 653                         " err: %d\n", bio, err);
 654                 /*
 655                  * Bump the ib_bio_err_cnt and release bio.
 656                  */
 657                 atomic_inc(&ibr->ib_bio_err_cnt);
 658                 smp_mb__after_atomic_inc();
 659         }
 660
 661         bio_put(bio);
 662
 663         if (!atomic_dec_and_test(&ibr->ib_bio_cnt))
 664                 return;
 665
 666         pr_debug("done[%p] bio: %p task_lba: %llu bio_lba: %llu err=%d\n",
 667                  task, bio, task->task_lba,
 668                  (unsigned long long)bio->bi_sector, err);
 669
 670         transport_complete_task(task, !atomic_read(&ibr->ib_bio_err_cnt));
 671 }
 672
 673 static struct se_subsystem_api iblock_template = {
 674         .name                   = "iblock",
 675         .owner                  = THIS_MODULE,
 676         .transport_type         = TRANSPORT_PLUGIN_VHBA_PDEV,
 677         .attach_hba             = iblock_attach_hba,
 678         .detach_hba             = iblock_detach_hba,
 679         .allocate_virtdevice    = iblock_allocate_virtdevice,
 680         .create_virtdevice      = iblock_create_virtdevice,
 681         .free_device            = iblock_free_device,
 682         .dpo_emulated           = iblock_emulated_dpo,
 683         .fua_write_emulated     = iblock_emulated_fua_write,
 684         .fua_read_emulated      = iblock_emulated_fua_read,
 685         .write_cache_emulated   = iblock_emulated_write_cache,
 686         .alloc_task             = iblock_alloc_task,
 687         .do_task                = iblock_do_task,
 688         .do_discard             = iblock_do_discard,
 689         .do_sync_cache          = iblock_emulate_sync_cache,
 690         .free_task              = iblock_free_task,
 691         .check_configfs_dev_params = iblock_check_configfs_dev_params,
 692         .set_configfs_dev_params = iblock_set_configfs_dev_params,
 693         .show_configfs_dev_params = iblock_show_configfs_dev_params,
 694         .get_device_rev         = iblock_get_device_rev,
 695         .get_device_type        = iblock_get_device_type,
 696         .get_blocks             = iblock_get_blocks,
 697 };
 698
 699 static int __init iblock_module_init(void)
 700 {
 701         return transport_subsystem_register(&iblock_template);
 702 }
 703
 704 static void iblock_module_exit(void)
 705 {
 706         transport_subsystem_release(&iblock_template);
 707 }
 708
 709 MODULE_DESCRIPTION("TCM IBLOCK subsystem plugin");
 710 MODULE_AUTHOR("nab@Linux-iSCSI.org");
 711 MODULE_LICENSE("GPL");
 712
 713 module_init(iblock_module_init);
 714 module_exit(iblock_module_exit);