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