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