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