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