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(&q->cmd_filter, rq->cmd, has_write_perm))
 190                         return -EPERM;
 191         } else if (!capable(CAP_SYS_RAWIO))
 192                 return -EPERM;
 193
 194         /*
 195          * fill in request structure
 196          */
 197         rq->cmd_len = hdr->request_len;
 198         rq->cmd_type = REQ_TYPE_BLOCK_PC;
 199
 200         rq->timeout = (hdr->timeout * HZ) / 1000;
 201         if (!rq->timeout)
 202                 rq->timeout = q->sg_timeout;
 203         if (!rq->timeout)
 204                 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
 205         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                 next_rq->bio = NULL;
 319                 blk_put_request(next_rq);
 320         }
 321         return ERR_PTR(ret);
 322 }
 323
 324 /*
 325  * async completion call-back from the block layer, when scsi/ide/whatever
 326  * calls end_that_request_last() on a request
 327  */
 328 static void bsg_rq_end_io(struct request *rq, int uptodate)
 329 {
 330         struct bsg_command *bc = rq->end_io_data;
 331         struct bsg_device *bd = bc->bd;
 332         unsigned long flags;
 333
 334         dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
 335                 bd->name, rq, bc, bc->bio, uptodate);
 336
 337         bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
 338
 339         spin_lock_irqsave(&bd->lock, flags);
 340         list_move_tail(&bc->list, &bd->done_list);
 341         bd->done_cmds++;
 342         spin_unlock_irqrestore(&bd->lock, flags);
 343
 344         wake_up(&bd->wq_done);
 345 }
 346
 347 /*
 348  * do final setup of a 'bc' and submit the matching 'rq' to the block
 349  * layer for io
 350  */
 351 static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
 352                             struct bsg_command *bc, struct request *rq)
 353 {
 354         int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));
 355
 356         /*
 357          * add bc command to busy queue and submit rq for io
 358          */
 359         bc->rq = rq;
 360         bc->bio = rq->bio;
 361         if (rq->next_rq)
 362                 bc->bidi_bio = rq->next_rq->bio;
 363         bc->hdr.duration = jiffies;
 364         spin_lock_irq(&bd->lock);
 365         list_add_tail(&bc->list, &bd->busy_list);
 366         spin_unlock_irq(&bd->lock);
 367
 368         dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
 369
 370         rq->end_io_data = bc;
 371         blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
 372 }
 373
 374 static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
 375 {
 376         struct bsg_command *bc = NULL;
 377
 378         spin_lock_irq(&bd->lock);
 379         if (bd->done_cmds) {
 380                 bc = list_first_entry(&bd->done_list, struct bsg_command, list);
 381                 list_del(&bc->list);
 382                 bd->done_cmds--;
 383         }
 384         spin_unlock_irq(&bd->lock);
 385
 386         return bc;
 387 }
 388
 389 /*
 390  * Get a finished command from the done list
 391  */
 392 static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
 393 {
 394         struct bsg_command *bc;
 395         int ret;
 396
 397         do {
 398                 bc = bsg_next_done_cmd(bd);
 399                 if (bc)
 400                         break;
 401
 402                 if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
 403                         bc = ERR_PTR(-EAGAIN);
 404                         break;
 405                 }
 406
 407                 ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
 408                 if (ret) {
 409                         bc = ERR_PTR(-ERESTARTSYS);
 410                         break;
 411                 }
 412         } while (1);
 413
 414         dprintk("%s: returning done %p\n", bd->name, bc);
 415
 416         return bc;
 417 }
 418
 419 static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
 420                                     struct bio *bio, struct bio *bidi_bio)
 421 {
 422         int ret = 0;
 423
 424         dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
 425         /*
 426          * fill in all the output members
 427          */
 428         hdr->device_status = status_byte(rq->errors);
 429         hdr->transport_status = host_byte(rq->errors);
 430         hdr->driver_status = driver_byte(rq->errors);
 431         hdr->info = 0;
 432         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
 433                 hdr->info |= SG_INFO_CHECK;
 434         hdr->response_len = 0;
 435
 436         if (rq->sense_len && hdr->response) {
 437                 int len = min_t(unsigned int, hdr->max_response_len,
 438                                         rq->sense_len);
 439
 440                 ret = copy_to_user((void*)(unsigned long)hdr->response,
 441                                    rq->sense, len);
 442                 if (!ret)
 443                         hdr->response_len = len;
 444                 else
 445                         ret = -EFAULT;
 446         }
 447
 448         if (rq->next_rq) {
 449                 hdr->dout_resid = rq->data_len;
 450                 hdr->din_resid = rq->next_rq->data_len;
 451                 blk_rq_unmap_user(bidi_bio);
 452                 rq->next_rq->bio = NULL;
 453                 blk_put_request(rq->next_rq);
 454         } else if (rq_data_dir(rq) == READ)
 455                 hdr->din_resid = rq->data_len;
 456         else
 457                 hdr->dout_resid = rq->data_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         rq->bio = NULL;
 472         blk_put_request(rq);
 473
 474         return ret;
 475 }
 476
 477 static int bsg_complete_all_commands(struct bsg_device *bd)
 478 {
 479         struct bsg_command *bc;
 480         int ret, tret;
 481
 482         dprintk("%s: entered\n", bd->name);
 483
 484         /*
 485          * wait for all commands to complete
 486          */
 487         ret = 0;
 488         do {
 489                 ret = bsg_io_schedule(bd);
 490                 /*
 491                  * look for -ENODATA specifically -- we'll sometimes get
 492                  * -ERESTARTSYS when we've taken a signal, but we can't
 493                  * return until we're done freeing the queue, so ignore
 494                  * it.  The signal will get handled when we're done freeing
 495                  * the bsg_device.
 496                  */
 497         } while (ret != -ENODATA);
 498
 499         /*
 500          * discard done commands
 501          */
 502         ret = 0;
 503         do {
 504                 spin_lock_irq(&bd->lock);
 505                 if (!bd->queued_cmds) {
 506                         spin_unlock_irq(&bd->lock);
 507                         break;
 508                 }
 509                 spin_unlock_irq(&bd->lock);
 510
 511                 bc = bsg_get_done_cmd(bd);
 512                 if (IS_ERR(bc))
 513                         break;
 514
 515                 tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 516                                                 bc->bidi_bio);
 517                 if (!ret)
 518                         ret = tret;
 519
 520                 bsg_free_command(bc);
 521         } while (1);
 522
 523         return ret;
 524 }
 525
 526 static int
 527 __bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
 528            const struct iovec *iov, ssize_t *bytes_read)
 529 {
 530         struct bsg_command *bc;
 531         int nr_commands, ret;
 532
 533         if (count % sizeof(struct sg_io_v4))
 534                 return -EINVAL;
 535
 536         ret = 0;
 537         nr_commands = count / sizeof(struct sg_io_v4);
 538         while (nr_commands) {
 539                 bc = bsg_get_done_cmd(bd);
 540                 if (IS_ERR(bc)) {
 541                         ret = PTR_ERR(bc);
 542                         break;
 543                 }
 544
 545                 /*
 546                  * this is the only case where we need to copy data back
 547                  * after completing the request. so do that here,
 548                  * bsg_complete_work() cannot do that for us
 549                  */
 550                 ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 551                                                bc->bidi_bio);
 552
 553                 if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
 554                         ret = -EFAULT;
 555
 556                 bsg_free_command(bc);
 557
 558                 if (ret)
 559                         break;
 560
 561                 buf += sizeof(struct sg_io_v4);
 562                 *bytes_read += sizeof(struct sg_io_v4);
 563                 nr_commands--;
 564         }
 565
 566         return ret;
 567 }
 568
 569 static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
 570 {
 571         if (file->f_flags & O_NONBLOCK)
 572                 clear_bit(BSG_F_BLOCK, &bd->flags);
 573         else
 574                 set_bit(BSG_F_BLOCK, &bd->flags);
 575 }
 576
 577 /*
 578  * Check if the error is a "real" error that we should return.
 579  */
 580 static inline int err_block_err(int ret)
 581 {
 582         if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
 583                 return 1;
 584
 585         return 0;
 586 }
 587
 588 static ssize_t
 589 bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 590 {
 591         struct bsg_device *bd = file->private_data;
 592         int ret;
 593         ssize_t bytes_read;
 594
 595         dprintk("%s: read %Zd bytes\n", bd->name, count);
 596
 597         bsg_set_block(bd, file);
 598
 599         bytes_read = 0;
 600         ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
 601         *ppos = bytes_read;
 602
 603         if (!bytes_read || (bytes_read && err_block_err(ret)))
 604                 bytes_read = ret;
 605
 606         return bytes_read;
 607 }
 608
 609 static int __bsg_write(struct bsg_device *bd, const char __user *buf,
 610                        size_t count, ssize_t *bytes_written,
 611                        fmode_t has_write_perm)
 612 {
 613         struct bsg_command *bc;
 614         struct request *rq;
 615         int ret, nr_commands;
 616
 617         if (count % sizeof(struct sg_io_v4))
 618                 return -EINVAL;
 619
 620         nr_commands = count / sizeof(struct sg_io_v4);
 621         rq = NULL;
 622         bc = NULL;
 623         ret = 0;
 624         while (nr_commands) {
 625                 struct request_queue *q = bd->queue;
 626
 627                 bc = bsg_alloc_command(bd);
 628                 if (IS_ERR(bc)) {
 629                         ret = PTR_ERR(bc);
 630                         bc = NULL;
 631                         break;
 632                 }
 633
 634                 if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
 635                         ret = -EFAULT;
 636                         break;
 637                 }
 638
 639                 /*
 640                  * get a request, fill in the blanks, and add to request queue
 641                  */
 642                 rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
 643                 if (IS_ERR(rq)) {
 644                         ret = PTR_ERR(rq);
 645                         rq = NULL;
 646                         break;
 647                 }
 648
 649                 bsg_add_command(bd, q, bc, rq);
 650                 bc = NULL;
 651                 rq = NULL;
 652                 nr_commands--;
 653                 buf += sizeof(struct sg_io_v4);
 654                 *bytes_written += sizeof(struct sg_io_v4);
 655         }
 656
 657         if (bc)
 658                 bsg_free_command(bc);
 659
 660         return ret;
 661 }
 662
 663 static ssize_t
 664 bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 665 {
 666         struct bsg_device *bd = file->private_data;
 667         ssize_t bytes_written;
 668         int ret;
 669
 670         dprintk("%s: write %Zd bytes\n", bd->name, count);
 671
 672         bsg_set_block(bd, file);
 673
 674         bytes_written = 0;
 675         ret = __bsg_write(bd, buf, count, &bytes_written,
 676                           file->f_mode & FMODE_WRITE);
 677
 678         *ppos = bytes_written;
 679
 680         /*
 681          * return bytes written on non-fatal errors
 682          */
 683         if (!bytes_written || (bytes_written && err_block_err(ret)))
 684                 bytes_written = ret;
 685
 686         dprintk("%s: returning %Zd\n", bd->name, bytes_written);
 687         return bytes_written;
 688 }
 689
 690 static struct bsg_device *bsg_alloc_device(void)
 691 {
 692         struct bsg_device *bd;
 693
 694         bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
 695         if (unlikely(!bd))
 696                 return NULL;
 697
 698         spin_lock_init(&bd->lock);
 699
 700         bd->max_queue = BSG_DEFAULT_CMDS;
 701
 702         INIT_LIST_HEAD(&bd->busy_list);
 703         INIT_LIST_HEAD(&bd->done_list);
 704         INIT_HLIST_NODE(&bd->dev_list);
 705
 706         init_waitqueue_head(&bd->wq_free);
 707         init_waitqueue_head(&bd->wq_done);
 708         return bd;
 709 }
 710
 711 static void bsg_kref_release_function(struct kref *kref)
 712 {
 713         struct bsg_class_device *bcd =
 714                 container_of(kref, struct bsg_class_device, ref);
 715         struct device *parent = bcd->parent;
 716
 717         if (bcd->release)
 718                 bcd->release(bcd->parent);
 719
 720         put_device(parent);
 721 }
 722
 723 static int bsg_put_device(struct bsg_device *bd)
 724 {
 725         int ret = 0, do_free;
 726         struct request_queue *q = bd->queue;
 727
 728         mutex_lock(&bsg_mutex);
 729
 730         do_free = atomic_dec_and_test(&bd->ref_count);
 731         if (!do_free) {
 732                 mutex_unlock(&bsg_mutex);
 733                 goto out;
 734         }
 735
 736         hlist_del(&bd->dev_list);
 737         mutex_unlock(&bsg_mutex);
 738
 739         dprintk("%s: tearing down\n", bd->name);
 740
 741         /*
 742          * close can always block
 743          */
 744         set_bit(BSG_F_BLOCK, &bd->flags);
 745
 746         /*
 747          * correct error detection baddies here again. it's the responsibility
 748          * of the app to properly reap commands before close() if it wants
 749          * fool-proof error detection
 750          */
 751         ret = bsg_complete_all_commands(bd);
 752
 753         kfree(bd);
 754 out:
 755         kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
 756         if (do_free)
 757                 blk_put_queue(q);
 758         return ret;
 759 }
 760
 761 static struct bsg_device *bsg_add_device(struct inode *inode,
 762                                          struct request_queue *rq,
 763                                          struct file *file)
 764 {
 765         struct bsg_device *bd;
 766         int ret;
 767 #ifdef BSG_DEBUG
 768         unsigned char buf[32];
 769 #endif
 770         ret = blk_get_queue(rq);
 771         if (ret)
 772                 return ERR_PTR(-ENXIO);
 773
 774         bd = bsg_alloc_device();
 775         if (!bd) {
 776                 blk_put_queue(rq);
 777                 return ERR_PTR(-ENOMEM);
 778         }
 779
 780         bd->queue = rq;
 781
 782         bsg_set_block(bd, file);
 783
 784         atomic_set(&bd->ref_count, 1);
 785         mutex_lock(&bsg_mutex);
 786         hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 787
 788         strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
 789         dprintk("bound to <%s>, max queue %d\n",
 790                 format_dev_t(buf, inode->i_rdev), bd->max_queue);
 791
 792         mutex_unlock(&bsg_mutex);
 793         return bd;
 794 }
 795
 796 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 797 {
 798         struct bsg_device *bd;
 799         struct hlist_node *entry;
 800
 801         mutex_lock(&bsg_mutex);
 802
 803         hlist_for_each_entry(bd, entry, bsg_dev_idx_hash(minor), dev_list) {
 804                 if (bd->queue == q) {
 805                         atomic_inc(&bd->ref_count);
 806                         goto found;
 807                 }
 808         }
 809         bd = NULL;
 810 found:
 811         mutex_unlock(&bsg_mutex);
 812         return bd;
 813 }
 814
 815 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 816 {
 817         struct bsg_device *bd;
 818         struct bsg_class_device *bcd;
 819
 820         /*
 821          * find the class device
 822          */
 823         mutex_lock(&bsg_mutex);
 824         bcd = idr_find(&bsg_minor_idr, iminor(inode));
 825         if (bcd)
 826                 kref_get(&bcd->ref);
 827         mutex_unlock(&bsg_mutex);
 828
 829         if (!bcd)
 830                 return ERR_PTR(-ENODEV);
 831
 832         bd = __bsg_get_device(iminor(inode), bcd->queue);
 833         if (bd)
 834                 return bd;
 835
 836         bd = bsg_add_device(inode, bcd->queue, file);
 837         if (IS_ERR(bd))
 838                 kref_put(&bcd->ref, bsg_kref_release_function);
 839
 840         return bd;
 841 }
 842
 843 static int bsg_open(struct inode *inode, struct file *file)
 844 {
 845         struct bsg_device *bd;
 846
 847         lock_kernel();
 848         bd = bsg_get_device(inode, file);
 849         unlock_kernel();
 850
 851         if (IS_ERR(bd))
 852                 return PTR_ERR(bd);
 853
 854         file->private_data = bd;
 855         return 0;
 856 }
 857
 858 static int bsg_release(struct inode *inode, struct file *file)
 859 {
 860         struct bsg_device *bd = file->private_data;
 861
 862         file->private_data = NULL;
 863         return bsg_put_device(bd);
 864 }
 865
 866 static unsigned int bsg_poll(struct file *file, poll_table *wait)
 867 {
 868         struct bsg_device *bd = file->private_data;
 869         unsigned int mask = 0;
 870
 871         poll_wait(file, &bd->wq_done, wait);
 872         poll_wait(file, &bd->wq_free, wait);
 873
 874         spin_lock_irq(&bd->lock);
 875         if (!list_empty(&bd->done_list))
 876                 mask |= POLLIN | POLLRDNORM;
 877         if (bd->queued_cmds >= bd->max_queue)
 878                 mask |= POLLOUT;
 879         spin_unlock_irq(&bd->lock);
 880
 881         return mask;
 882 }
 883
 884 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 885 {
 886         struct bsg_device *bd = file->private_data;
 887         int __user *uarg = (int __user *) arg;
 888         int ret;
 889
 890         switch (cmd) {
 891                 /*
 892                  * our own ioctls
 893                  */
 894         case SG_GET_COMMAND_Q:
 895                 return put_user(bd->max_queue, uarg);
 896         case SG_SET_COMMAND_Q: {
 897                 int queue;
 898
 899                 if (get_user(queue, uarg))
 900                         return -EFAULT;
 901                 if (queue < 1)
 902                         return -EINVAL;
 903
 904                 spin_lock_irq(&bd->lock);
 905                 bd->max_queue = queue;
 906                 spin_unlock_irq(&bd->lock);
 907                 return 0;
 908         }
 909
 910         /*
 911          * SCSI/sg ioctls
 912          */
 913         case SG_GET_VERSION_NUM:
 914         case SCSI_IOCTL_GET_IDLUN:
 915         case SCSI_IOCTL_GET_BUS_NUMBER:
 916         case SG_SET_TIMEOUT:
 917         case SG_GET_TIMEOUT:
 918         case SG_GET_RESERVED_SIZE:
 919         case SG_SET_RESERVED_SIZE:
 920         case SG_EMULATED_HOST:
 921         case SCSI_IOCTL_SEND_COMMAND: {
 922                 void __user *uarg = (void __user *) arg;
 923                 return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
 924         }
 925         case SG_IO: {
 926                 struct request *rq;
 927                 struct bio *bio, *bidi_bio = NULL;
 928                 struct sg_io_v4 hdr;
 929                 int at_head;
 930                 u8 sense[SCSI_SENSE_BUFFERSIZE];
 931
 932                 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 933                         return -EFAULT;
 934
 935                 rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
 936                 if (IS_ERR(rq))
 937                         return PTR_ERR(rq);
 938
 939                 bio = rq->bio;
 940                 if (rq->next_rq)
 941                         bidi_bio = rq->next_rq->bio;
 942
 943                 at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
 944                 blk_execute_rq(bd->queue, NULL, rq, at_head);
 945                 ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
 946
 947                 if (copy_to_user(uarg, &hdr, sizeof(hdr)))
 948                         return -EFAULT;
 949
 950                 return ret;
 951         }
 952         /*
 953          * block device ioctls
 954          */
 955         default:
 956 #if 0
 957                 return ioctl_by_bdev(bd->bdev, cmd, arg);
 958 #else
 959                 return -ENOTTY;
 960 #endif
 961         }
 962 }
 963
 964 static const struct file_operations bsg_fops = {
 965         .read           =       bsg_read,
 966         .write          =       bsg_write,
 967         .poll           =       bsg_poll,
 968         .open           =       bsg_open,
 969         .release        =       bsg_release,
 970         .unlocked_ioctl =       bsg_ioctl,
 971         .owner          =       THIS_MODULE,
 972 };
 973
 974 void bsg_unregister_queue(struct request_queue *q)
 975 {
 976         struct bsg_class_device *bcd = &q->bsg_dev;
 977
 978         if (!bcd->class_dev)
 979                 return;
 980
 981         mutex_lock(&bsg_mutex);
 982         idr_remove(&bsg_minor_idr, bcd->minor);
 983         sysfs_remove_link(&q->kobj, "bsg");
 984         device_unregister(bcd->class_dev);
 985         bcd->class_dev = NULL;
 986         kref_put(&bcd->ref, bsg_kref_release_function);
 987         mutex_unlock(&bsg_mutex);
 988 }
 989 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 990
 991 int bsg_register_queue(struct request_queue *q, struct device *parent,
 992                        const char *name, void (*release)(struct device *))
 993 {
 994         struct bsg_class_device *bcd;
 995         dev_t dev;
 996         int ret, minor;
 997         struct device *class_dev = NULL;
 998         const char *devname;
 999
1000         if (name)
1001                 devname = name;
1002         else
1003                 devname = dev_name(parent);
1004
1005         /*
1006          * we need a proper transport to send commands, not a stacked device
1007          */
1008         if (!q->request_fn)
1009                 return 0;
1010
1011         bcd = &q->bsg_dev;
1012         memset(bcd, 0, sizeof(*bcd));
1013
1014         mutex_lock(&bsg_mutex);
1015
1016         ret = idr_pre_get(&bsg_minor_idr, GFP_KERNEL);
1017         if (!ret) {
1018                 ret = -ENOMEM;
1019                 goto unlock;
1020         }
1021
1022         ret = idr_get_new(&bsg_minor_idr, bcd, &minor);
1023         if (ret < 0)
1024                 goto unlock;
1025
1026         if (minor >= BSG_MAX_DEVS) {
1027                 printk(KERN_ERR "bsg: too many bsg devices\n");
1028                 ret = -EINVAL;
1029                 goto remove_idr;
1030         }
1031
1032         bcd->minor = minor;
1033         bcd->queue = q;
1034         bcd->parent = get_device(parent);
1035         bcd->release = release;
1036         kref_init(&bcd->ref);
1037         dev = MKDEV(bsg_major, bcd->minor);
1038         class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1039         if (IS_ERR(class_dev)) {
1040                 ret = PTR_ERR(class_dev);
1041                 goto put_dev;
1042         }
1043         bcd->class_dev = class_dev;
1044
1045         if (q->kobj.sd) {
1046                 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1047                 if (ret)
1048                         goto unregister_class_dev;
1049         }
1050
1051         mutex_unlock(&bsg_mutex);
1052         return 0;
1053
1054 unregister_class_dev:
1055         device_unregister(class_dev);
1056 put_dev:
1057         put_device(parent);
1058 remove_idr:
1059         idr_remove(&bsg_minor_idr, minor);
1060 unlock:
1061         mutex_unlock(&bsg_mutex);
1062         return ret;
1063 }
1064 EXPORT_SYMBOL_GPL(bsg_register_queue);
1065
1066 static struct cdev bsg_cdev;
1067
1068 static int __init bsg_init(void)
1069 {
1070         int ret, i;
1071         dev_t devid;
1072
1073         bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1074                                 sizeof(struct bsg_command), 0, 0, NULL);
1075         if (!bsg_cmd_cachep) {
1076                 printk(KERN_ERR "bsg: failed creating slab cache\n");
1077                 return -ENOMEM;
1078         }
1079
1080         for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1081                 INIT_HLIST_HEAD(&bsg_device_list[i]);
1082
1083         bsg_class = class_create(THIS_MODULE, "bsg");
1084         if (IS_ERR(bsg_class)) {
1085                 ret = PTR_ERR(bsg_class);
1086                 goto destroy_kmemcache;
1087         }
1088
1089         ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1090         if (ret)
1091                 goto destroy_bsg_class;
1092
1093         bsg_major = MAJOR(devid);
1094
1095         cdev_init(&bsg_cdev, &bsg_fops);
1096         ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1097         if (ret)
1098                 goto unregister_chrdev;
1099
1100         printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1101                " loaded (major %d)\n", bsg_major);
1102         return 0;
1103 unregister_chrdev:
1104         unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1105 destroy_bsg_class:
1106         class_destroy(bsg_class);
1107 destroy_kmemcache:
1108         kmem_cache_destroy(bsg_cmd_cachep);
1109         return ret;
1110 }
1111
1112 MODULE_AUTHOR("Jens Axboe");
1113 MODULE_DESCRIPTION(BSG_DESCRIPTION);
1114 MODULE_LICENSE("GPL");
1115
1116 device_initcall(bsg_init);