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