block/bsg.c

   1 /*
   2  * bsg.c - block layer implementation of the sg v4 interface
   3  *
   4  * Copyright (C) 2004 Jens Axboe <axboe@suse.de> SUSE Labs
   5  * Copyright (C) 2004 Peter M. Jones <pjones@redhat.com>
   6  *
   7  *  This file is subject to the terms and conditions of the GNU General Public
   8  *  License version 2.  See the file "COPYING" in the main directory of this
   9  *  archive for more details.
  10  *
  11  */
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/file.h>
  15 #include <linux/blkdev.h>
  16 #include <linux/poll.h>
  17 #include <linux/cdev.h>
  18 #include <linux/jiffies.h>
  19 #include <linux/percpu.h>
  20 #include <linux/uio.h>
  21 #include <linux/idr.h>
  22 #include <linux/bsg.h>
  23 #include <linux/slab.h>
  24
  25 #include <scsi/scsi.h>
  26 #include <scsi/scsi_ioctl.h>
  27 #include <scsi/scsi_cmnd.h>
  28 #include <scsi/scsi_device.h>
  29 #include <scsi/scsi_driver.h>
  30 #include <scsi/sg.h>
  31
  32 #define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
  33 #define BSG_VERSION     "0.4"
  34
  35 struct bsg_device {
  36         struct request_queue *queue;
  37         spinlock_t lock;
  38         struct list_head busy_list;
  39         struct list_head done_list;
  40         struct hlist_node dev_list;
  41         atomic_t ref_count;
  42         int queued_cmds;
  43         int done_cmds;
  44         wait_queue_head_t wq_done;
  45         wait_queue_head_t wq_free;
  46         char name[20];
  47         int max_queue;
  48         unsigned long flags;
  49 };
  50
  51 enum {
  52         BSG_F_BLOCK             = 1,
  53 };
  54
  55 #define BSG_DEFAULT_CMDS        64
  56 #define BSG_MAX_DEVS            32768
  57
  58 #undef BSG_DEBUG
  59
  60 #ifdef BSG_DEBUG
  61 #define dprintk(fmt, args...) printk(KERN_ERR "%s: " fmt, __func__, ##args)
  62 #else
  63 #define dprintk(fmt, args...)
  64 #endif
  65
  66 static DEFINE_MUTEX(bsg_mutex);
  67 static DEFINE_IDR(bsg_minor_idr);
  68
  69 #define BSG_LIST_ARRAY_SIZE     8
  70 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
  71
  72 static struct class *bsg_class;
  73 static int bsg_major;
  74
  75 static struct kmem_cache *bsg_cmd_cachep;
  76
  77 /*
  78  * our internal command type
  79  */
  80 struct bsg_command {
  81         struct bsg_device *bd;
  82         struct list_head list;
  83         struct request *rq;
  84         struct bio *bio;
  85         struct bio *bidi_bio;
  86         int err;
  87         struct sg_io_v4 hdr;
  88         char sense[SCSI_SENSE_BUFFERSIZE];
  89 };
  90
  91 static void bsg_free_command(struct bsg_command *bc)
  92 {
  93         struct bsg_device *bd = bc->bd;
  94         unsigned long flags;
  95
  96         kmem_cache_free(bsg_cmd_cachep, bc);
  97
  98         spin_lock_irqsave(&bd->lock, flags);
  99         bd->queued_cmds--;
 100         spin_unlock_irqrestore(&bd->lock, flags);
 101
 102         wake_up(&bd->wq_free);
 103 }
 104
 105 static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
 106 {
 107         struct bsg_command *bc = ERR_PTR(-EINVAL);
 108
 109         spin_lock_irq(&bd->lock);
 110
 111         if (bd->queued_cmds >= bd->max_queue)
 112                 goto out;
 113
 114         bd->queued_cmds++;
 115         spin_unlock_irq(&bd->lock);
 116
 117         bc = kmem_cache_zalloc(bsg_cmd_cachep, GFP_KERNEL);
 118         if (unlikely(!bc)) {
 119                 spin_lock_irq(&bd->lock);
 120                 bd->queued_cmds--;
 121                 bc = ERR_PTR(-ENOMEM);
 122                 goto out;
 123         }
 124
 125         bc->bd = bd;
 126         INIT_LIST_HEAD(&bc->list);
 127         dprintk("%s: returning free cmd %p\n", bd->name, bc);
 128         return bc;
 129 out:
 130         spin_unlock_irq(&bd->lock);
 131         return bc;
 132 }
 133
 134 static inline struct hlist_head *bsg_dev_idx_hash(int index)
 135 {
 136         return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
 137 }
 138
 139 static int bsg_io_schedule(struct bsg_device *bd)
 140 {
 141         DEFINE_WAIT(wait);
 142         int ret = 0;
 143
 144         spin_lock_irq(&bd->lock);
 145
 146         BUG_ON(bd->done_cmds > bd->queued_cmds);
 147
 148         /*
 149          * -ENOSPC or -ENODATA?  I'm going for -ENODATA, meaning "I have no
 150          * work to do", even though we return -ENOSPC after this same test
 151          * during bsg_write() -- there, it means our buffer can't have more
 152          * bsg_commands added to it, thus has no space left.
 153          */
 154         if (bd->done_cmds == bd->queued_cmds) {
 155                 ret = -ENODATA;
 156                 goto unlock;
 157         }
 158
 159         if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
 160                 ret = -EAGAIN;
 161                 goto unlock;
 162         }
 163
 164         prepare_to_wait(&bd->wq_done, &wait, TASK_UNINTERRUPTIBLE);
 165         spin_unlock_irq(&bd->lock);
 166         io_schedule();
 167         finish_wait(&bd->wq_done, &wait);
 168
 169         return ret;
 170 unlock:
 171         spin_unlock_irq(&bd->lock);
 172         return ret;
 173 }
 174
 175 static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
 176                                 struct sg_io_v4 *hdr, struct bsg_device *bd,
 177                                 fmode_t has_write_perm)
 178 {
 179         if (hdr->request_len > BLK_MAX_CDB) {
 180                 rq->cmd = kzalloc(hdr->request_len, GFP_KERNEL);
 181                 if (!rq->cmd)
 182                         return -ENOMEM;
 183         }
 184
 185         if (copy_from_user(rq->cmd, (void __user *)(unsigned long)hdr->request,
 186                            hdr->request_len))
 187                 return -EFAULT;
 188
 189         if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
 190                 if (blk_verify_command(rq->cmd, has_write_perm))
 191                         return -EPERM;
 192         } else if (!capable(CAP_SYS_RAWIO))
 193                 return -EPERM;
 194
 195         /*
 196          * fill in request structure
 197          */
 198         rq->cmd_len = hdr->request_len;
 199
 200         rq->timeout = msecs_to_jiffies(hdr->timeout);
 201         if (!rq->timeout)
 202                 rq->timeout = q->sg_timeout;
 203         if (!rq->timeout)
 204                 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
 205         if (rq->timeout < BLK_MIN_SG_TIMEOUT)
 206                 rq->timeout = BLK_MIN_SG_TIMEOUT;
 207
 208         return 0;
 209 }
 210
 211 /*
 212  * Check if sg_io_v4 from user is allowed and valid
 213  */
 214 static int
 215 bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
 216 {
 217         int ret = 0;
 218
 219         if (hdr->guard != 'Q')
 220                 return -EINVAL;
 221
 222         switch (hdr->protocol) {
 223         case BSG_PROTOCOL_SCSI:
 224                 switch (hdr->subprotocol) {
 225                 case BSG_SUB_PROTOCOL_SCSI_CMD:
 226                 case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
 227                         break;
 228                 default:
 229                         ret = -EINVAL;
 230                 }
 231                 break;
 232         default:
 233                 ret = -EINVAL;
 234         }
 235
 236         *rw = hdr->dout_xfer_len ? WRITE : READ;
 237         return ret;
 238 }
 239
 240 /*
 241  * map sg_io_v4 to a request.
 242  */
 243 static struct request *
 244 bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
 245             u8 *sense)
 246 {
 247         struct request_queue *q = bd->queue;
 248         struct request *rq, *next_rq = NULL;
 249         int ret, rw;
 250         unsigned int dxfer_len;
 251         void __user *dxferp = NULL;
 252         struct bsg_class_device *bcd = &q->bsg_dev;
 253
 254         /* if the LLD has been removed then the bsg_unregister_queue will
 255          * eventually be called and the class_dev was freed, so we can no
 256          * longer use this request_queue. Return no such address.
 257          */
 258         if (!bcd->class_dev)
 259                 return ERR_PTR(-ENXIO);
 260
 261         dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
 262                 hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
 263                 hdr->din_xfer_len);
 264
 265         ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
 266         if (ret)
 267                 return ERR_PTR(ret);
 268
 269         /*
 270          * map scatter-gather elements separately and string them to request
 271          */
 272         rq = blk_get_request(q, rw, GFP_KERNEL);
 273         if (IS_ERR(rq))
 274                 return rq;
 275         blk_rq_set_block_pc(rq);
 276
 277         ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
 278         if (ret)
 279                 goto out;
 280
 281         if (rw == WRITE && hdr->din_xfer_len) {
 282                 if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
 283                         ret = -EOPNOTSUPP;
 284                         goto out;
 285                 }
 286
 287                 next_rq = blk_get_request(q, READ, GFP_KERNEL);
 288                 if (IS_ERR(next_rq)) {
 289                         ret = PTR_ERR(next_rq);
 290                         next_rq = NULL;
 291                         goto out;
 292                 }
 293                 rq->next_rq = next_rq;
 294                 next_rq->cmd_type = rq->cmd_type;
 295
 296                 dxferp = (void __user *)(unsigned long)hdr->din_xferp;
 297                 ret =  blk_rq_map_user(q, next_rq, NULL, dxferp,
 298                                        hdr->din_xfer_len, GFP_KERNEL);
 299                 if (ret)
 300                         goto out;
 301         }
 302
 303         if (hdr->dout_xfer_len) {
 304                 dxfer_len = hdr->dout_xfer_len;
 305                 dxferp = (void __user *)(unsigned long)hdr->dout_xferp;
 306         } else if (hdr->din_xfer_len) {
 307                 dxfer_len = hdr->din_xfer_len;
 308                 dxferp = (void __user *)(unsigned long)hdr->din_xferp;
 309         } else
 310                 dxfer_len = 0;
 311
 312         if (dxfer_len) {
 313                 ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
 314                                       GFP_KERNEL);
 315                 if (ret)
 316                         goto out;
 317         }
 318
 319         rq->sense = sense;
 320         rq->sense_len = 0;
 321
 322         return rq;
 323 out:
 324         if (rq->cmd != rq->__cmd)
 325                 kfree(rq->cmd);
 326         blk_put_request(rq);
 327         if (next_rq) {
 328                 blk_rq_unmap_user(next_rq->bio);
 329                 blk_put_request(next_rq);
 330         }
 331         return ERR_PTR(ret);
 332 }
 333
 334 /*
 335  * async completion call-back from the block layer, when scsi/ide/whatever
 336  * calls end_that_request_last() on a request
 337  */
 338 static void bsg_rq_end_io(struct request *rq, int uptodate)
 339 {
 340         struct bsg_command *bc = rq->end_io_data;
 341         struct bsg_device *bd = bc->bd;
 342         unsigned long flags;
 343
 344         dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
 345                 bd->name, rq, bc, bc->bio, uptodate);
 346
 347         bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
 348
 349         spin_lock_irqsave(&bd->lock, flags);
 350         list_move_tail(&bc->list, &bd->done_list);
 351         bd->done_cmds++;
 352         spin_unlock_irqrestore(&bd->lock, flags);
 353
 354         wake_up(&bd->wq_done);
 355 }
 356
 357 /*
 358  * do final setup of a 'bc' and submit the matching 'rq' to the block
 359  * layer for io
 360  */
 361 static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
 362                             struct bsg_command *bc, struct request *rq)
 363 {
 364         int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));
 365
 366         /*
 367          * add bc command to busy queue and submit rq for io
 368          */
 369         bc->rq = rq;
 370         bc->bio = rq->bio;
 371         if (rq->next_rq)
 372                 bc->bidi_bio = rq->next_rq->bio;
 373         bc->hdr.duration = jiffies;
 374         spin_lock_irq(&bd->lock);
 375         list_add_tail(&bc->list, &bd->busy_list);
 376         spin_unlock_irq(&bd->lock);
 377
 378         dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
 379
 380         rq->end_io_data = bc;
 381         blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
 382 }
 383
 384 static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
 385 {
 386         struct bsg_command *bc = NULL;
 387
 388         spin_lock_irq(&bd->lock);
 389         if (bd->done_cmds) {
 390                 bc = list_first_entry(&bd->done_list, struct bsg_command, list);
 391                 list_del(&bc->list);
 392                 bd->done_cmds--;
 393         }
 394         spin_unlock_irq(&bd->lock);
 395
 396         return bc;
 397 }
 398
 399 /*
 400  * Get a finished command from the done list
 401  */
 402 static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
 403 {
 404         struct bsg_command *bc;
 405         int ret;
 406
 407         do {
 408                 bc = bsg_next_done_cmd(bd);
 409                 if (bc)
 410                         break;
 411
 412                 if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
 413                         bc = ERR_PTR(-EAGAIN);
 414                         break;
 415                 }
 416
 417                 ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
 418                 if (ret) {
 419                         bc = ERR_PTR(-ERESTARTSYS);
 420                         break;
 421                 }
 422         } while (1);
 423
 424         dprintk("%s: returning done %p\n", bd->name, bc);
 425
 426         return bc;
 427 }
 428
 429 static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
 430                                     struct bio *bio, struct bio *bidi_bio)
 431 {
 432         int ret = 0;
 433
 434         dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
 435         /*
 436          * fill in all the output members
 437          */
 438         hdr->device_status = rq->errors & 0xff;
 439         hdr->transport_status = host_byte(rq->errors);
 440         hdr->driver_status = driver_byte(rq->errors);
 441         hdr->info = 0;
 442         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
 443                 hdr->info |= SG_INFO_CHECK;
 444         hdr->response_len = 0;
 445
 446         if (rq->sense_len && hdr->response) {
 447                 int len = min_t(unsigned int, hdr->max_response_len,
 448                                         rq->sense_len);
 449
 450                 ret = copy_to_user((void __user *)(unsigned long)hdr->response,
 451                                    rq->sense, len);
 452                 if (!ret)
 453                         hdr->response_len = len;
 454                 else
 455                         ret = -EFAULT;
 456         }
 457
 458         if (rq->next_rq) {
 459                 hdr->dout_resid = rq->resid_len;
 460                 hdr->din_resid = rq->next_rq->resid_len;
 461                 blk_rq_unmap_user(bidi_bio);
 462                 blk_put_request(rq->next_rq);
 463         } else if (rq_data_dir(rq) == READ)
 464                 hdr->din_resid = rq->resid_len;
 465         else
 466                 hdr->dout_resid = rq->resid_len;
 467
 468         /*
 469          * If the request generated a negative error number, return it
 470          * (providing we aren't already returning an error); if it's
 471          * just a protocol response (i.e. non negative), that gets
 472          * processed above.
 473          */
 474         if (!ret && rq->errors < 0)
 475                 ret = rq->errors;
 476
 477         blk_rq_unmap_user(bio);
 478         if (rq->cmd != rq->__cmd)
 479                 kfree(rq->cmd);
 480         blk_put_request(rq);
 481
 482         return ret;
 483 }
 484
 485 static int bsg_complete_all_commands(struct bsg_device *bd)
 486 {
 487         struct bsg_command *bc;
 488         int ret, tret;
 489
 490         dprintk("%s: entered\n", bd->name);
 491
 492         /*
 493          * wait for all commands to complete
 494          */
 495         ret = 0;
 496         do {
 497                 ret = bsg_io_schedule(bd);
 498                 /*
 499                  * look for -ENODATA specifically -- we'll sometimes get
 500                  * -ERESTARTSYS when we've taken a signal, but we can't
 501                  * return until we're done freeing the queue, so ignore
 502                  * it.  The signal will get handled when we're done freeing
 503                  * the bsg_device.
 504                  */
 505         } while (ret != -ENODATA);
 506
 507         /*
 508          * discard done commands
 509          */
 510         ret = 0;
 511         do {
 512                 spin_lock_irq(&bd->lock);
 513                 if (!bd->queued_cmds) {
 514                         spin_unlock_irq(&bd->lock);
 515                         break;
 516                 }
 517                 spin_unlock_irq(&bd->lock);
 518
 519                 bc = bsg_get_done_cmd(bd);
 520                 if (IS_ERR(bc))
 521                         break;
 522
 523                 tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 524                                                 bc->bidi_bio);
 525                 if (!ret)
 526                         ret = tret;
 527
 528                 bsg_free_command(bc);
 529         } while (1);
 530
 531         return ret;
 532 }
 533
 534 static int
 535 __bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
 536            const struct iovec *iov, ssize_t *bytes_read)
 537 {
 538         struct bsg_command *bc;
 539         int nr_commands, ret;
 540
 541         if (count % sizeof(struct sg_io_v4))
 542                 return -EINVAL;
 543
 544         ret = 0;
 545         nr_commands = count / sizeof(struct sg_io_v4);
 546         while (nr_commands) {
 547                 bc = bsg_get_done_cmd(bd);
 548                 if (IS_ERR(bc)) {
 549                         ret = PTR_ERR(bc);
 550                         break;
 551                 }
 552
 553                 /*
 554                  * this is the only case where we need to copy data back
 555                  * after completing the request. so do that here,
 556                  * bsg_complete_work() cannot do that for us
 557                  */
 558                 ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 559                                                bc->bidi_bio);
 560
 561                 if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
 562                         ret = -EFAULT;
 563
 564                 bsg_free_command(bc);
 565
 566                 if (ret)
 567                         break;
 568
 569                 buf += sizeof(struct sg_io_v4);
 570                 *bytes_read += sizeof(struct sg_io_v4);
 571                 nr_commands--;
 572         }
 573
 574         return ret;
 575 }
 576
 577 static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
 578 {
 579         if (file->f_flags & O_NONBLOCK)
 580                 clear_bit(BSG_F_BLOCK, &bd->flags);
 581         else
 582                 set_bit(BSG_F_BLOCK, &bd->flags);
 583 }
 584
 585 /*
 586  * Check if the error is a "real" error that we should return.
 587  */
 588 static inline int err_block_err(int ret)
 589 {
 590         if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
 591                 return 1;
 592
 593         return 0;
 594 }
 595
 596 static ssize_t
 597 bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 598 {
 599         struct bsg_device *bd = file->private_data;
 600         int ret;
 601         ssize_t bytes_read;
 602
 603         dprintk("%s: read %Zd bytes\n", bd->name, count);
 604
 605         bsg_set_block(bd, file);
 606
 607         bytes_read = 0;
 608         ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
 609         *ppos = bytes_read;
 610
 611         if (!bytes_read || err_block_err(ret))
 612                 bytes_read = ret;
 613
 614         return bytes_read;
 615 }
 616
 617 static int __bsg_write(struct bsg_device *bd, const char __user *buf,
 618                        size_t count, ssize_t *bytes_written,
 619                        fmode_t has_write_perm)
 620 {
 621         struct bsg_command *bc;
 622         struct request *rq;
 623         int ret, nr_commands;
 624
 625         if (count % sizeof(struct sg_io_v4))
 626                 return -EINVAL;
 627
 628         nr_commands = count / sizeof(struct sg_io_v4);
 629         rq = NULL;
 630         bc = NULL;
 631         ret = 0;
 632         while (nr_commands) {
 633                 struct request_queue *q = bd->queue;
 634
 635                 bc = bsg_alloc_command(bd);
 636                 if (IS_ERR(bc)) {
 637                         ret = PTR_ERR(bc);
 638                         bc = NULL;
 639                         break;
 640                 }
 641
 642                 if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
 643                         ret = -EFAULT;
 644                         break;
 645                 }
 646
 647                 /*
 648                  * get a request, fill in the blanks, and add to request queue
 649                  */
 650                 rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
 651                 if (IS_ERR(rq)) {
 652                         ret = PTR_ERR(rq);
 653                         rq = NULL;
 654                         break;
 655                 }
 656
 657                 bsg_add_command(bd, q, bc, rq);
 658                 bc = NULL;
 659                 rq = NULL;
 660                 nr_commands--;
 661                 buf += sizeof(struct sg_io_v4);
 662                 *bytes_written += sizeof(struct sg_io_v4);
 663         }
 664
 665         if (bc)
 666                 bsg_free_command(bc);
 667
 668         return ret;
 669 }
 670
 671 static ssize_t
 672 bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 673 {
 674         struct bsg_device *bd = file->private_data;
 675         ssize_t bytes_written;
 676         int ret;
 677
 678         dprintk("%s: write %Zd bytes\n", bd->name, count);
 679
 680         if (unlikely(segment_eq(get_fs(), KERNEL_DS)))
 681                 return -EINVAL;
 682
 683         bsg_set_block(bd, file);
 684
 685         bytes_written = 0;
 686         ret = __bsg_write(bd, buf, count, &bytes_written,
 687                           file->f_mode & FMODE_WRITE);
 688
 689         *ppos = bytes_written;
 690
 691         /*
 692          * return bytes written on non-fatal errors
 693          */
 694         if (!bytes_written || err_block_err(ret))
 695                 bytes_written = ret;
 696
 697         dprintk("%s: returning %Zd\n", bd->name, bytes_written);
 698         return bytes_written;
 699 }
 700
 701 static struct bsg_device *bsg_alloc_device(void)
 702 {
 703         struct bsg_device *bd;
 704
 705         bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
 706         if (unlikely(!bd))
 707                 return NULL;
 708
 709         spin_lock_init(&bd->lock);
 710
 711         bd->max_queue = BSG_DEFAULT_CMDS;
 712
 713         INIT_LIST_HEAD(&bd->busy_list);
 714         INIT_LIST_HEAD(&bd->done_list);
 715         INIT_HLIST_NODE(&bd->dev_list);
 716
 717         init_waitqueue_head(&bd->wq_free);
 718         init_waitqueue_head(&bd->wq_done);
 719         return bd;
 720 }
 721
 722 static void bsg_kref_release_function(struct kref *kref)
 723 {
 724         struct bsg_class_device *bcd =
 725                 container_of(kref, struct bsg_class_device, ref);
 726         struct device *parent = bcd->parent;
 727
 728         if (bcd->release)
 729                 bcd->release(bcd->parent);
 730
 731         put_device(parent);
 732 }
 733
 734 static int bsg_put_device(struct bsg_device *bd)
 735 {
 736         int ret = 0, do_free;
 737         struct request_queue *q = bd->queue;
 738
 739         mutex_lock(&bsg_mutex);
 740
 741         do_free = atomic_dec_and_test(&bd->ref_count);
 742         if (!do_free) {
 743                 mutex_unlock(&bsg_mutex);
 744                 goto out;
 745         }
 746
 747         hlist_del(&bd->dev_list);
 748         mutex_unlock(&bsg_mutex);
 749
 750         dprintk("%s: tearing down\n", bd->name);
 751
 752         /*
 753          * close can always block
 754          */
 755         set_bit(BSG_F_BLOCK, &bd->flags);
 756
 757         /*
 758          * correct error detection baddies here again. it's the responsibility
 759          * of the app to properly reap commands before close() if it wants
 760          * fool-proof error detection
 761          */
 762         ret = bsg_complete_all_commands(bd);
 763
 764         kfree(bd);
 765 out:
 766         kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
 767         if (do_free)
 768                 blk_put_queue(q);
 769         return ret;
 770 }
 771
 772 static struct bsg_device *bsg_add_device(struct inode *inode,
 773                                          struct request_queue *rq,
 774                                          struct file *file)
 775 {
 776         struct bsg_device *bd;
 777 #ifdef BSG_DEBUG
 778         unsigned char buf[32];
 779 #endif
 780         if (!blk_get_queue(rq))
 781                 return ERR_PTR(-ENXIO);
 782
 783         bd = bsg_alloc_device();
 784         if (!bd) {
 785                 blk_put_queue(rq);
 786                 return ERR_PTR(-ENOMEM);
 787         }
 788
 789         bd->queue = rq;
 790
 791         bsg_set_block(bd, file);
 792
 793         atomic_set(&bd->ref_count, 1);
 794         mutex_lock(&bsg_mutex);
 795         hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 796
 797         strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
 798         dprintk("bound to <%s>, max queue %d\n",
 799                 format_dev_t(buf, inode->i_rdev), bd->max_queue);
 800
 801         mutex_unlock(&bsg_mutex);
 802         return bd;
 803 }
 804
 805 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 806 {
 807         struct bsg_device *bd;
 808
 809         mutex_lock(&bsg_mutex);
 810
 811         hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
 812                 if (bd->queue == q) {
 813                         atomic_inc(&bd->ref_count);
 814                         goto found;
 815                 }
 816         }
 817         bd = NULL;
 818 found:
 819         mutex_unlock(&bsg_mutex);
 820         return bd;
 821 }
 822
 823 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 824 {
 825         struct bsg_device *bd;
 826         struct bsg_class_device *bcd;
 827
 828         /*
 829          * find the class device
 830          */
 831         mutex_lock(&bsg_mutex);
 832         bcd = idr_find(&bsg_minor_idr, iminor(inode));
 833         if (bcd)
 834                 kref_get(&bcd->ref);
 835         mutex_unlock(&bsg_mutex);
 836
 837         if (!bcd)
 838                 return ERR_PTR(-ENODEV);
 839
 840         bd = __bsg_get_device(iminor(inode), bcd->queue);
 841         if (bd)
 842                 return bd;
 843
 844         bd = bsg_add_device(inode, bcd->queue, file);
 845         if (IS_ERR(bd))
 846                 kref_put(&bcd->ref, bsg_kref_release_function);
 847
 848         return bd;
 849 }
 850
 851 static int bsg_open(struct inode *inode, struct file *file)
 852 {
 853         struct bsg_device *bd;
 854
 855         bd = bsg_get_device(inode, file);
 856
 857         if (IS_ERR(bd))
 858                 return PTR_ERR(bd);
 859
 860         file->private_data = bd;
 861         return 0;
 862 }
 863
 864 static int bsg_release(struct inode *inode, struct file *file)
 865 {
 866         struct bsg_device *bd = file->private_data;
 867
 868         file->private_data = NULL;
 869         return bsg_put_device(bd);
 870 }
 871
 872 static unsigned int bsg_poll(struct file *file, poll_table *wait)
 873 {
 874         struct bsg_device *bd = file->private_data;
 875         unsigned int mask = 0;
 876
 877         poll_wait(file, &bd->wq_done, wait);
 878         poll_wait(file, &bd->wq_free, wait);
 879
 880         spin_lock_irq(&bd->lock);
 881         if (!list_empty(&bd->done_list))
 882                 mask |= POLLIN | POLLRDNORM;
 883         if (bd->queued_cmds < bd->max_queue)
 884                 mask |= POLLOUT;
 885         spin_unlock_irq(&bd->lock);
 886
 887         return mask;
 888 }
 889
 890 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 891 {
 892         struct bsg_device *bd = file->private_data;
 893         int __user *uarg = (int __user *) arg;
 894         int ret;
 895
 896         switch (cmd) {
 897                 /*
 898                  * our own ioctls
 899                  */
 900         case SG_GET_COMMAND_Q:
 901                 return put_user(bd->max_queue, uarg);
 902         case SG_SET_COMMAND_Q: {
 903                 int queue;
 904
 905                 if (get_user(queue, uarg))
 906                         return -EFAULT;
 907                 if (queue < 1)
 908                         return -EINVAL;
 909
 910                 spin_lock_irq(&bd->lock);
 911                 bd->max_queue = queue;
 912                 spin_unlock_irq(&bd->lock);
 913                 return 0;
 914         }
 915
 916         /*
 917          * SCSI/sg ioctls
 918          */
 919         case SG_GET_VERSION_NUM:
 920         case SCSI_IOCTL_GET_IDLUN:
 921         case SCSI_IOCTL_GET_BUS_NUMBER:
 922         case SG_SET_TIMEOUT:
 923         case SG_GET_TIMEOUT:
 924         case SG_GET_RESERVED_SIZE:
 925         case SG_SET_RESERVED_SIZE:
 926         case SG_EMULATED_HOST:
 927         case SCSI_IOCTL_SEND_COMMAND: {
 928                 void __user *uarg = (void __user *) arg;
 929                 return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
 930         }
 931         case SG_IO: {
 932                 struct request *rq;
 933                 struct bio *bio, *bidi_bio = NULL;
 934                 struct sg_io_v4 hdr;
 935                 int at_head;
 936                 u8 sense[SCSI_SENSE_BUFFERSIZE];
 937
 938                 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 939                         return -EFAULT;
 940
 941                 rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
 942                 if (IS_ERR(rq))
 943                         return PTR_ERR(rq);
 944
 945                 bio = rq->bio;
 946                 if (rq->next_rq)
 947                         bidi_bio = rq->next_rq->bio;
 948
 949                 at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
 950                 blk_execute_rq(bd->queue, NULL, rq, at_head);
 951                 ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
 952
 953                 if (copy_to_user(uarg, &hdr, sizeof(hdr)))
 954                         return -EFAULT;
 955
 956                 return ret;
 957         }
 958         /*
 959          * block device ioctls
 960          */
 961         default:
 962 #if 0
 963                 return ioctl_by_bdev(bd->bdev, cmd, arg);
 964 #else
 965                 return -ENOTTY;
 966 #endif
 967         }
 968 }
 969
 970 static const struct file_operations bsg_fops = {
 971         .read           =       bsg_read,
 972         .write          =       bsg_write,
 973         .poll           =       bsg_poll,
 974         .open           =       bsg_open,
 975         .release        =       bsg_release,
 976         .unlocked_ioctl =       bsg_ioctl,
 977         .owner          =       THIS_MODULE,
 978         .llseek         =       default_llseek,
 979 };
 980
 981 void bsg_unregister_queue(struct request_queue *q)
 982 {
 983         struct bsg_class_device *bcd = &q->bsg_dev;
 984
 985         if (!bcd->class_dev)
 986                 return;
 987
 988         mutex_lock(&bsg_mutex);
 989         idr_remove(&bsg_minor_idr, bcd->minor);
 990         if (q->kobj.sd)
 991                 sysfs_remove_link(&q->kobj, "bsg");
 992         device_unregister(bcd->class_dev);
 993         bcd->class_dev = NULL;
 994         kref_put(&bcd->ref, bsg_kref_release_function);
 995         mutex_unlock(&bsg_mutex);
 996 }
 997 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 998
 999 int bsg_register_queue(struct request_queue *q, struct device *parent,
1000                        const char *name, void (*release)(struct device *))
1001 {
1002         struct bsg_class_device *bcd;
1003         dev_t dev;
1004         int ret;
1005         struct device *class_dev = NULL;
1006         const char *devname;
1007
1008         if (name)
1009                 devname = name;
1010         else
1011                 devname = dev_name(parent);
1012
1013         /*
1014          * we need a proper transport to send commands, not a stacked device
1015          */
1016         if (!queue_is_rq_based(q))
1017                 return 0;
1018
1019         bcd = &q->bsg_dev;
1020         memset(bcd, 0, sizeof(*bcd));
1021
1022         mutex_lock(&bsg_mutex);
1023
1024         ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
1025         if (ret < 0) {
1026                 if (ret == -ENOSPC) {
1027                         printk(KERN_ERR "bsg: too many bsg devices\n");
1028                         ret = -EINVAL;
1029                 }
1030                 goto unlock;
1031         }
1032
1033         bcd->minor = ret;
1034         bcd->queue = q;
1035         bcd->parent = get_device(parent);
1036         bcd->release = release;
1037         kref_init(&bcd->ref);
1038         dev = MKDEV(bsg_major, bcd->minor);
1039         class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1040         if (IS_ERR(class_dev)) {
1041                 ret = PTR_ERR(class_dev);
1042                 goto put_dev;
1043         }
1044         bcd->class_dev = class_dev;
1045
1046         if (q->kobj.sd) {
1047                 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1048                 if (ret)
1049                         goto unregister_class_dev;
1050         }
1051
1052         mutex_unlock(&bsg_mutex);
1053         return 0;
1054
1055 unregister_class_dev:
1056         device_unregister(class_dev);
1057 put_dev:
1058         put_device(parent);
1059         idr_remove(&bsg_minor_idr, bcd->minor);
1060 unlock:
1061         mutex_unlock(&bsg_mutex);
1062         return ret;
1063 }
1064 EXPORT_SYMBOL_GPL(bsg_register_queue);
1065
1066 static struct cdev bsg_cdev;
1067
1068 static char *bsg_devnode(struct device *dev, umode_t *mode)
1069 {
1070         return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
1071 }
1072
1073 static int __init bsg_init(void)
1074 {
1075         int ret, i;
1076         dev_t devid;
1077
1078         bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1079                                 sizeof(struct bsg_command), 0, 0, NULL);
1080         if (!bsg_cmd_cachep) {
1081                 printk(KERN_ERR "bsg: failed creating slab cache\n");
1082                 return -ENOMEM;
1083         }
1084
1085         for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1086                 INIT_HLIST_HEAD(&bsg_device_list[i]);
1087
1088         bsg_class = class_create(THIS_MODULE, "bsg");
1089         if (IS_ERR(bsg_class)) {
1090                 ret = PTR_ERR(bsg_class);
1091                 goto destroy_kmemcache;
1092         }
1093         bsg_class->devnode = bsg_devnode;
1094
1095         ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1096         if (ret)
1097                 goto destroy_bsg_class;
1098
1099         bsg_major = MAJOR(devid);
1100
1101         cdev_init(&bsg_cdev, &bsg_fops);
1102         ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1103         if (ret)
1104                 goto unregister_chrdev;
1105
1106         printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1107                " loaded (major %d)\n", bsg_major);
1108         return 0;
1109 unregister_chrdev:
1110         unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1111 destroy_bsg_class:
1112         class_destroy(bsg_class);
1113 destroy_kmemcache:
1114         kmem_cache_destroy(bsg_cmd_cachep);
1115         return ret;
1116 }
1117
1118 MODULE_AUTHOR("Jens Axboe");
1119 MODULE_DESCRIPTION(BSG_DESCRIPTION);
1120 MODULE_LICENSE("GPL");
1121
1122 device_initcall(bsg_init);