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         struct blk_scsi_cmd_filter *cmd_filter;
  49         mode_t *f_mode;
  50 };
  51
  52 enum {
  53         BSG_F_BLOCK             = 1,
  54 };
  55
  56 #define BSG_DEFAULT_CMDS        64
  57 #define BSG_MAX_DEVS            32768
  58
  59 #undef BSG_DEBUG
  60
  61 #ifdef BSG_DEBUG
  62 #define dprintk(fmt, args...) printk(KERN_ERR "%s: " fmt, __func__, ##args)
  63 #else
  64 #define dprintk(fmt, args...)
  65 #endif
  66
  67 static DEFINE_MUTEX(bsg_mutex);
  68 static DEFINE_IDR(bsg_minor_idr);
  69
  70 #define BSG_LIST_ARRAY_SIZE     8
  71 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
  72
  73 static struct class *bsg_class;
  74 static int bsg_major;
  75
  76 static struct kmem_cache *bsg_cmd_cachep;
  77
  78 /*
  79  * our internal command type
  80  */
  81 struct bsg_command {
  82         struct bsg_device *bd;
  83         struct list_head list;
  84         struct request *rq;
  85         struct bio *bio;
  86         struct bio *bidi_bio;
  87         int err;
  88         struct sg_io_v4 hdr;
  89         char sense[SCSI_SENSE_BUFFERSIZE];
  90 };
  91
  92 static void bsg_free_command(struct bsg_command *bc)
  93 {
  94         struct bsg_device *bd = bc->bd;
  95         unsigned long flags;
  96
  97         kmem_cache_free(bsg_cmd_cachep, bc);
  98
  99         spin_lock_irqsave(&bd->lock, flags);
 100         bd->queued_cmds--;
 101         spin_unlock_irqrestore(&bd->lock, flags);
 102
 103         wake_up(&bd->wq_free);
 104 }
 105
 106 static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
 107 {
 108         struct bsg_command *bc = ERR_PTR(-EINVAL);
 109
 110         spin_lock_irq(&bd->lock);
 111
 112         if (bd->queued_cmds >= bd->max_queue)
 113                 goto out;
 114
 115         bd->queued_cmds++;
 116         spin_unlock_irq(&bd->lock);
 117
 118         bc = kmem_cache_zalloc(bsg_cmd_cachep, GFP_KERNEL);
 119         if (unlikely(!bc)) {
 120                 spin_lock_irq(&bd->lock);
 121                 bd->queued_cmds--;
 122                 bc = ERR_PTR(-ENOMEM);
 123                 goto out;
 124         }
 125
 126         bc->bd = bd;
 127         INIT_LIST_HEAD(&bc->list);
 128         dprintk("%s: returning free cmd %p\n", bd->name, bc);
 129         return bc;
 130 out:
 131         spin_unlock_irq(&bd->lock);
 132         return bc;
 133 }
 134
 135 static inline struct hlist_head *bsg_dev_idx_hash(int index)
 136 {
 137         return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
 138 }
 139
 140 static int bsg_io_schedule(struct bsg_device *bd)
 141 {
 142         DEFINE_WAIT(wait);
 143         int ret = 0;
 144
 145         spin_lock_irq(&bd->lock);
 146
 147         BUG_ON(bd->done_cmds > bd->queued_cmds);
 148
 149         /*
 150          * -ENOSPC or -ENODATA?  I'm going for -ENODATA, meaning "I have no
 151          * work to do", even though we return -ENOSPC after this same test
 152          * during bsg_write() -- there, it means our buffer can't have more
 153          * bsg_commands added to it, thus has no space left.
 154          */
 155         if (bd->done_cmds == bd->queued_cmds) {
 156                 ret = -ENODATA;
 157                 goto unlock;
 158         }
 159
 160         if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
 161                 ret = -EAGAIN;
 162                 goto unlock;
 163         }
 164
 165         prepare_to_wait(&bd->wq_done, &wait, TASK_UNINTERRUPTIBLE);
 166         spin_unlock_irq(&bd->lock);
 167         io_schedule();
 168         finish_wait(&bd->wq_done, &wait);
 169
 170         return ret;
 171 unlock:
 172         spin_unlock_irq(&bd->lock);
 173         return ret;
 174 }
 175
 176 static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
 177                                 struct sg_io_v4 *hdr, struct bsg_device *bd)
 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 *)(unsigned long)hdr->request,
 186                            hdr->request_len))
 187                 return -EFAULT;
 188
 189         if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
 190                 if (blk_cmd_filter_verify_command(bd->cmd_filter, rq->cmd,
 191                                                  bd->f_mode))
 192                         return -EPERM;
 193         } else if (!capable(CAP_SYS_RAWIO))
 194                 return -EPERM;
 195
 196         /*
 197          * fill in request structure
 198          */
 199         rq->cmd_len = hdr->request_len;
 200         rq->cmd_type = REQ_TYPE_BLOCK_PC;
 201
 202         rq->timeout = (hdr->timeout * HZ) / 1000;
 203         if (!rq->timeout)
 204                 rq->timeout = q->sg_timeout;
 205         if (!rq->timeout)
 206                 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
 207
 208         return 0;
 209 }
 210
 211 /*
 212  * Check if sg_io_v4 from user is allowed and valid
 213  */
 214 static int
 215 bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
 216 {
 217         int ret = 0;
 218
 219         if (hdr->guard != 'Q')
 220                 return -EINVAL;
 221         if (hdr->dout_xfer_len > (q->max_sectors << 9) ||
 222             hdr->din_xfer_len > (q->max_sectors << 9))
 223                 return -EIO;
 224
 225         switch (hdr->protocol) {
 226         case BSG_PROTOCOL_SCSI:
 227                 switch (hdr->subprotocol) {
 228                 case BSG_SUB_PROTOCOL_SCSI_CMD:
 229                 case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
 230                         break;
 231                 default:
 232                         ret = -EINVAL;
 233                 }
 234                 break;
 235         default:
 236                 ret = -EINVAL;
 237         }
 238
 239         *rw = hdr->dout_xfer_len ? WRITE : READ;
 240         return ret;
 241 }
 242
 243 /*
 244  * map sg_io_v4 to a request.
 245  */
 246 static struct request *
 247 bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr)
 248 {
 249         struct request_queue *q = bd->queue;
 250         struct request *rq, *next_rq = NULL;
 251         int ret, rw;
 252         unsigned int dxfer_len;
 253         void *dxferp = NULL;
 254
 255         dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
 256                 hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
 257                 hdr->din_xfer_len);
 258
 259         ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
 260         if (ret)
 261                 return ERR_PTR(ret);
 262
 263         /*
 264          * map scatter-gather elements seperately and string them to request
 265          */
 266         rq = blk_get_request(q, rw, GFP_KERNEL);
 267         if (!rq)
 268                 return ERR_PTR(-ENOMEM);
 269         ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd);
 270         if (ret)
 271                 goto out;
 272
 273         if (rw == WRITE && hdr->din_xfer_len) {
 274                 if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
 275                         ret = -EOPNOTSUPP;
 276                         goto out;
 277                 }
 278
 279                 next_rq = blk_get_request(q, READ, GFP_KERNEL);
 280                 if (!next_rq) {
 281                         ret = -ENOMEM;
 282                         goto out;
 283                 }
 284                 rq->next_rq = next_rq;
 285                 next_rq->cmd_type = rq->cmd_type;
 286
 287                 dxferp = (void*)(unsigned long)hdr->din_xferp;
 288                 ret =  blk_rq_map_user(q, next_rq, dxferp, hdr->din_xfer_len);
 289                 if (ret)
 290                         goto out;
 291         }
 292
 293         if (hdr->dout_xfer_len) {
 294                 dxfer_len = hdr->dout_xfer_len;
 295                 dxferp = (void*)(unsigned long)hdr->dout_xferp;
 296         } else if (hdr->din_xfer_len) {
 297                 dxfer_len = hdr->din_xfer_len;
 298                 dxferp = (void*)(unsigned long)hdr->din_xferp;
 299         } else
 300                 dxfer_len = 0;
 301
 302         if (dxfer_len) {
 303                 ret = blk_rq_map_user(q, rq, dxferp, dxfer_len);
 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 static void bsg_set_cmd_filter(struct bsg_device *bd,
 572                            struct file *file)
 573 {
 574         struct inode *inode;
 575         struct gendisk *disk;
 576
 577         if (!file)
 578                 return;
 579
 580         inode = file->f_dentry->d_inode;
 581         if (!inode)
 582                 return;
 583
 584         disk = inode->i_bdev->bd_disk;
 585
 586         bd->cmd_filter = &disk->cmd_filter;
 587         bd->f_mode = &file->f_mode;
 588 }
 589
 590 /*
 591  * Check if the error is a "real" error that we should return.
 592  */
 593 static inline int err_block_err(int ret)
 594 {
 595         if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
 596                 return 1;
 597
 598         return 0;
 599 }
 600
 601 static ssize_t
 602 bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 603 {
 604         struct bsg_device *bd = file->private_data;
 605         int ret;
 606         ssize_t bytes_read;
 607
 608         dprintk("%s: read %Zd bytes\n", bd->name, count);
 609
 610         bsg_set_block(bd, file);
 611         bsg_set_cmd_filter(bd, file);
 612
 613         bytes_read = 0;
 614         ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
 615         *ppos = bytes_read;
 616
 617         if (!bytes_read || (bytes_read && err_block_err(ret)))
 618                 bytes_read = ret;
 619
 620         return bytes_read;
 621 }
 622
 623 static int __bsg_write(struct bsg_device *bd, const char __user *buf,
 624                        size_t count, ssize_t *bytes_written)
 625 {
 626         struct bsg_command *bc;
 627         struct request *rq;
 628         int ret, nr_commands;
 629
 630         if (count % sizeof(struct sg_io_v4))
 631                 return -EINVAL;
 632
 633         nr_commands = count / sizeof(struct sg_io_v4);
 634         rq = NULL;
 635         bc = NULL;
 636         ret = 0;
 637         while (nr_commands) {
 638                 struct request_queue *q = bd->queue;
 639
 640                 bc = bsg_alloc_command(bd);
 641                 if (IS_ERR(bc)) {
 642                         ret = PTR_ERR(bc);
 643                         bc = NULL;
 644                         break;
 645                 }
 646
 647                 if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
 648                         ret = -EFAULT;
 649                         break;
 650                 }
 651
 652                 /*
 653                  * get a request, fill in the blanks, and add to request queue
 654                  */
 655                 rq = bsg_map_hdr(bd, &bc->hdr);
 656                 if (IS_ERR(rq)) {
 657                         ret = PTR_ERR(rq);
 658                         rq = NULL;
 659                         break;
 660                 }
 661
 662                 bsg_add_command(bd, q, bc, rq);
 663                 bc = NULL;
 664                 rq = NULL;
 665                 nr_commands--;
 666                 buf += sizeof(struct sg_io_v4);
 667                 *bytes_written += sizeof(struct sg_io_v4);
 668         }
 669
 670         if (bc)
 671                 bsg_free_command(bc);
 672
 673         return ret;
 674 }
 675
 676 static ssize_t
 677 bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 678 {
 679         struct bsg_device *bd = file->private_data;
 680         ssize_t bytes_written;
 681         int ret;
 682
 683         dprintk("%s: write %Zd bytes\n", bd->name, count);
 684
 685         bsg_set_block(bd, file);
 686         bsg_set_cmd_filter(bd, file);
 687
 688         bytes_written = 0;
 689         ret = __bsg_write(bd, buf, count, &bytes_written);
 690         *ppos = bytes_written;
 691
 692         /*
 693          * return bytes written on non-fatal errors
 694          */
 695         if (!bytes_written || (bytes_written && err_block_err(ret)))
 696                 bytes_written = ret;
 697
 698         dprintk("%s: returning %Zd\n", bd->name, bytes_written);
 699         return bytes_written;
 700 }
 701
 702 static struct bsg_device *bsg_alloc_device(void)
 703 {
 704         struct bsg_device *bd;
 705
 706         bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
 707         if (unlikely(!bd))
 708                 return NULL;
 709
 710         spin_lock_init(&bd->lock);
 711
 712         bd->max_queue = BSG_DEFAULT_CMDS;
 713
 714         INIT_LIST_HEAD(&bd->busy_list);
 715         INIT_LIST_HEAD(&bd->done_list);
 716         INIT_HLIST_NODE(&bd->dev_list);
 717
 718         init_waitqueue_head(&bd->wq_free);
 719         init_waitqueue_head(&bd->wq_done);
 720         return bd;
 721 }
 722
 723 static void bsg_kref_release_function(struct kref *kref)
 724 {
 725         struct bsg_class_device *bcd =
 726                 container_of(kref, struct bsg_class_device, ref);
 727         struct device *parent = bcd->parent;
 728
 729         if (bcd->release)
 730                 bcd->release(bcd->parent);
 731
 732         put_device(parent);
 733 }
 734
 735 static int bsg_put_device(struct bsg_device *bd)
 736 {
 737         int ret = 0, do_free;
 738         struct request_queue *q = bd->queue;
 739
 740         mutex_lock(&bsg_mutex);
 741
 742         do_free = atomic_dec_and_test(&bd->ref_count);
 743         if (!do_free) {
 744                 mutex_unlock(&bsg_mutex);
 745                 goto out;
 746         }
 747
 748         hlist_del(&bd->dev_list);
 749         mutex_unlock(&bsg_mutex);
 750
 751         dprintk("%s: tearing down\n", bd->name);
 752
 753         /*
 754          * close can always block
 755          */
 756         set_bit(BSG_F_BLOCK, &bd->flags);
 757
 758         /*
 759          * correct error detection baddies here again. it's the responsibility
 760          * of the app to properly reap commands before close() if it wants
 761          * fool-proof error detection
 762          */
 763         ret = bsg_complete_all_commands(bd);
 764
 765         kfree(bd);
 766 out:
 767         kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
 768         if (do_free)
 769                 blk_put_queue(q);
 770         return ret;
 771 }
 772
 773 static struct bsg_device *bsg_add_device(struct inode *inode,
 774                                          struct request_queue *rq,
 775                                          struct file *file)
 776 {
 777         struct bsg_device *bd;
 778         int ret;
 779 #ifdef BSG_DEBUG
 780         unsigned char buf[32];
 781 #endif
 782         ret = blk_get_queue(rq);
 783         if (ret)
 784                 return ERR_PTR(-ENXIO);
 785
 786         bd = bsg_alloc_device();
 787         if (!bd) {
 788                 blk_put_queue(rq);
 789                 return ERR_PTR(-ENOMEM);
 790         }
 791
 792         bd->queue = rq;
 793
 794         bsg_set_block(bd, file);
 795         bsg_set_cmd_filter(bd, file);
 796
 797         atomic_set(&bd->ref_count, 1);
 798         mutex_lock(&bsg_mutex);
 799         hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 800
 801         strncpy(bd->name, rq->bsg_dev.class_dev->bus_id, sizeof(bd->name) - 1);
 802         dprintk("bound to <%s>, max queue %d\n",
 803                 format_dev_t(buf, inode->i_rdev), bd->max_queue);
 804
 805         mutex_unlock(&bsg_mutex);
 806         return bd;
 807 }
 808
 809 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 810 {
 811         struct bsg_device *bd;
 812         struct hlist_node *entry;
 813
 814         mutex_lock(&bsg_mutex);
 815
 816         hlist_for_each_entry(bd, entry, bsg_dev_idx_hash(minor), dev_list) {
 817                 if (bd->queue == q) {
 818                         atomic_inc(&bd->ref_count);
 819                         goto found;
 820                 }
 821         }
 822         bd = NULL;
 823 found:
 824         mutex_unlock(&bsg_mutex);
 825         return bd;
 826 }
 827
 828 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 829 {
 830         struct bsg_device *bd;
 831         struct bsg_class_device *bcd;
 832
 833         /*
 834          * find the class device
 835          */
 836         mutex_lock(&bsg_mutex);
 837         bcd = idr_find(&bsg_minor_idr, iminor(inode));
 838         if (bcd)
 839                 kref_get(&bcd->ref);
 840         mutex_unlock(&bsg_mutex);
 841
 842         if (!bcd)
 843                 return ERR_PTR(-ENODEV);
 844
 845         bd = __bsg_get_device(iminor(inode), bcd->queue);
 846         if (bd)
 847                 return bd;
 848
 849         bd = bsg_add_device(inode, bcd->queue, file);
 850         if (IS_ERR(bd))
 851                 kref_put(&bcd->ref, bsg_kref_release_function);
 852
 853         return bd;
 854 }
 855
 856 static int bsg_open(struct inode *inode, struct file *file)
 857 {
 858         struct bsg_device *bd;
 859
 860         lock_kernel();
 861         bd = bsg_get_device(inode, file);
 862         unlock_kernel();
 863
 864         if (IS_ERR(bd))
 865                 return PTR_ERR(bd);
 866
 867         file->private_data = bd;
 868         return 0;
 869 }
 870
 871 static int bsg_release(struct inode *inode, struct file *file)
 872 {
 873         struct bsg_device *bd = file->private_data;
 874
 875         file->private_data = NULL;
 876         return bsg_put_device(bd);
 877 }
 878
 879 static unsigned int bsg_poll(struct file *file, poll_table *wait)
 880 {
 881         struct bsg_device *bd = file->private_data;
 882         unsigned int mask = 0;
 883
 884         poll_wait(file, &bd->wq_done, wait);
 885         poll_wait(file, &bd->wq_free, wait);
 886
 887         spin_lock_irq(&bd->lock);
 888         if (!list_empty(&bd->done_list))
 889                 mask |= POLLIN | POLLRDNORM;
 890         if (bd->queued_cmds >= bd->max_queue)
 891                 mask |= POLLOUT;
 892         spin_unlock_irq(&bd->lock);
 893
 894         return mask;
 895 }
 896
 897 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 898 {
 899         struct bsg_device *bd = file->private_data;
 900         int __user *uarg = (int __user *) arg;
 901         int ret;
 902
 903         switch (cmd) {
 904                 /*
 905                  * our own ioctls
 906                  */
 907         case SG_GET_COMMAND_Q:
 908                 return put_user(bd->max_queue, uarg);
 909         case SG_SET_COMMAND_Q: {
 910                 int queue;
 911
 912                 if (get_user(queue, uarg))
 913                         return -EFAULT;
 914                 if (queue < 1)
 915                         return -EINVAL;
 916
 917                 spin_lock_irq(&bd->lock);
 918                 bd->max_queue = queue;
 919                 spin_unlock_irq(&bd->lock);
 920                 return 0;
 921         }
 922
 923         /*
 924          * SCSI/sg ioctls
 925          */
 926         case SG_GET_VERSION_NUM:
 927         case SCSI_IOCTL_GET_IDLUN:
 928         case SCSI_IOCTL_GET_BUS_NUMBER:
 929         case SG_SET_TIMEOUT:
 930         case SG_GET_TIMEOUT:
 931         case SG_GET_RESERVED_SIZE:
 932         case SG_SET_RESERVED_SIZE:
 933         case SG_EMULATED_HOST:
 934         case SCSI_IOCTL_SEND_COMMAND: {
 935                 void __user *uarg = (void __user *) arg;
 936                 return scsi_cmd_ioctl(file, bd->queue, NULL, cmd, uarg);
 937         }
 938         case SG_IO: {
 939                 struct request *rq;
 940                 struct bio *bio, *bidi_bio = NULL;
 941                 struct sg_io_v4 hdr;
 942
 943                 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 944                         return -EFAULT;
 945
 946                 rq = bsg_map_hdr(bd, &hdr);
 947                 if (IS_ERR(rq))
 948                         return PTR_ERR(rq);
 949
 950                 bio = rq->bio;
 951                 if (rq->next_rq)
 952                         bidi_bio = rq->next_rq->bio;
 953                 blk_execute_rq(bd->queue, NULL, rq, 0);
 954                 ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
 955
 956                 if (copy_to_user(uarg, &hdr, sizeof(hdr)))
 957                         return -EFAULT;
 958
 959                 return ret;
 960         }
 961         /*
 962          * block device ioctls
 963          */
 964         default:
 965 #if 0
 966                 return ioctl_by_bdev(bd->bdev, cmd, arg);
 967 #else
 968                 return -ENOTTY;
 969 #endif
 970         }
 971 }
 972
 973 static const struct file_operations bsg_fops = {
 974         .read           =       bsg_read,
 975         .write          =       bsg_write,
 976         .poll           =       bsg_poll,
 977         .open           =       bsg_open,
 978         .release        =       bsg_release,
 979         .unlocked_ioctl =       bsg_ioctl,
 980         .owner          =       THIS_MODULE,
 981 };
 982
 983 void bsg_unregister_queue(struct request_queue *q)
 984 {
 985         struct bsg_class_device *bcd = &q->bsg_dev;
 986
 987         if (!bcd->class_dev)
 988                 return;
 989
 990         mutex_lock(&bsg_mutex);
 991         idr_remove(&bsg_minor_idr, bcd->minor);
 992         sysfs_remove_link(&q->kobj, "bsg");
 993         device_unregister(bcd->class_dev);
 994         bcd->class_dev = NULL;
 995         kref_put(&bcd->ref, bsg_kref_release_function);
 996         mutex_unlock(&bsg_mutex);
 997 }
 998 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 999
1000 int bsg_register_queue(struct request_queue *q, struct device *parent,
1001                        const char *name, void (*release)(struct device *))
1002 {
1003         struct bsg_class_device *bcd;
1004         dev_t dev;
1005         int ret, minor;
1006         struct device *class_dev = NULL;
1007         const char *devname;
1008
1009         if (name)
1010                 devname = name;
1011         else
1012                 devname = parent->bus_id;
1013
1014         /*
1015          * we need a proper transport to send commands, not a stacked device
1016          */
1017         if (!q->request_fn)
1018                 return 0;
1019
1020         bcd = &q->bsg_dev;
1021         memset(bcd, 0, sizeof(*bcd));
1022
1023         mutex_lock(&bsg_mutex);
1024
1025         ret = idr_pre_get(&bsg_minor_idr, GFP_KERNEL);
1026         if (!ret) {
1027                 ret = -ENOMEM;
1028                 goto unlock;
1029         }
1030
1031         ret = idr_get_new(&bsg_minor_idr, bcd, &minor);
1032         if (ret < 0)
1033                 goto unlock;
1034
1035         if (minor >= BSG_MAX_DEVS) {
1036                 printk(KERN_ERR "bsg: too many bsg devices\n");
1037                 ret = -EINVAL;
1038                 goto remove_idr;
1039         }
1040
1041         bcd->minor = minor;
1042         bcd->queue = q;
1043         bcd->parent = get_device(parent);
1044         bcd->release = release;
1045         kref_init(&bcd->ref);
1046         dev = MKDEV(bsg_major, bcd->minor);
1047         class_dev = device_create_drvdata(bsg_class, parent, dev, NULL,
1048                                           "%s", devname);
1049         if (IS_ERR(class_dev)) {
1050                 ret = PTR_ERR(class_dev);
1051                 goto put_dev;
1052         }
1053         bcd->class_dev = class_dev;
1054
1055         if (q->kobj.sd) {
1056                 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1057                 if (ret)
1058                         goto unregister_class_dev;
1059         }
1060
1061         mutex_unlock(&bsg_mutex);
1062         return 0;
1063
1064 unregister_class_dev:
1065         device_unregister(class_dev);
1066 put_dev:
1067         put_device(parent);
1068 remove_idr:
1069         idr_remove(&bsg_minor_idr, minor);
1070 unlock:
1071         mutex_unlock(&bsg_mutex);
1072         return ret;
1073 }
1074 EXPORT_SYMBOL_GPL(bsg_register_queue);
1075
1076 static struct cdev bsg_cdev;
1077
1078 static int __init bsg_init(void)
1079 {
1080         int ret, i;
1081         dev_t devid;
1082
1083         bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1084                                 sizeof(struct bsg_command), 0, 0, NULL);
1085         if (!bsg_cmd_cachep) {
1086                 printk(KERN_ERR "bsg: failed creating slab cache\n");
1087                 return -ENOMEM;
1088         }
1089
1090         for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1091                 INIT_HLIST_HEAD(&bsg_device_list[i]);
1092
1093         bsg_class = class_create(THIS_MODULE, "bsg");
1094         if (IS_ERR(bsg_class)) {
1095                 ret = PTR_ERR(bsg_class);
1096                 goto destroy_kmemcache;
1097         }
1098
1099         ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1100         if (ret)
1101                 goto destroy_bsg_class;
1102
1103         bsg_major = MAJOR(devid);
1104
1105         cdev_init(&bsg_cdev, &bsg_fops);
1106         ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1107         if (ret)
1108                 goto unregister_chrdev;
1109
1110         printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1111                " loaded (major %d)\n", bsg_major);
1112         return 0;
1113 unregister_chrdev:
1114         unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1115 destroy_bsg_class:
1116         class_destroy(bsg_class);
1117 destroy_kmemcache:
1118         kmem_cache_destroy(bsg_cmd_cachep);
1119         return ret;
1120 }
1121
1122 MODULE_AUTHOR("Jens Axboe");
1123 MODULE_DESCRIPTION(BSG_DESCRIPTION);
1124 MODULE_LICENSE("GPL");
1125
1126 device_initcall(bsg_init);