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/slab.h>
  24
  25 #include <scsi/scsi.h>
  26 #include <scsi/scsi_ioctl.h>
  27 #include <scsi/scsi_cmnd.h>
  28 #include <scsi/scsi_device.h>
  29 #include <scsi/scsi_driver.h>
  30 #include <scsi/sg.h>
  31
  32 #define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
  33 #define BSG_VERSION     "0.4"
  34
  35 struct bsg_device {
  36         struct request_queue *queue;
  37         spinlock_t lock;
  38         struct list_head busy_list;
  39         struct list_head done_list;
  40         struct hlist_node dev_list;
  41         atomic_t ref_count;
  42         int queued_cmds;
  43         int done_cmds;
  44         wait_queue_head_t wq_done;
  45         wait_queue_head_t wq_free;
  46         char name[20];
  47         int max_queue;
  48         unsigned long flags;
  49 };
  50
  51 enum {
  52         BSG_F_BLOCK             = 1,
  53 };
  54
  55 #define BSG_DEFAULT_CMDS        64
  56 #define BSG_MAX_DEVS            32768
  57
  58 #undef BSG_DEBUG
  59
  60 #ifdef BSG_DEBUG
  61 #define dprintk(fmt, args...) printk(KERN_ERR "%s: " fmt, __func__, ##args)
  62 #else
  63 #define dprintk(fmt, args...)
  64 #endif
  65
  66 static DEFINE_MUTEX(bsg_mutex);
  67 static DEFINE_IDR(bsg_minor_idr);
  68
  69 #define BSG_LIST_ARRAY_SIZE     8
  70 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
  71
  72 static struct class *bsg_class;
  73 static int bsg_major;
  74
  75 static struct kmem_cache *bsg_cmd_cachep;
  76
  77 /*
  78  * our internal command type
  79  */
  80 struct bsg_command {
  81         struct bsg_device *bd;
  82         struct list_head list;
  83         struct request *rq;
  84         struct bio *bio;
  85         struct bio *bidi_bio;
  86         int err;
  87         struct sg_io_v4 hdr;
  88         char sense[SCSI_SENSE_BUFFERSIZE];
  89 };
  90
  91 static void bsg_free_command(struct bsg_command *bc)
  92 {
  93         struct bsg_device *bd = bc->bd;
  94         unsigned long flags;
  95
  96         kmem_cache_free(bsg_cmd_cachep, bc);
  97
  98         spin_lock_irqsave(&bd->lock, flags);
  99         bd->queued_cmds--;
 100         spin_unlock_irqrestore(&bd->lock, flags);
 101
 102         wake_up(&bd->wq_free);
 103 }
 104
 105 static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
 106 {
 107         struct bsg_command *bc = ERR_PTR(-EINVAL);
 108
 109         spin_lock_irq(&bd->lock);
 110
 111         if (bd->queued_cmds >= bd->max_queue)
 112                 goto out;
 113
 114         bd->queued_cmds++;
 115         spin_unlock_irq(&bd->lock);
 116
 117         bc = kmem_cache_zalloc(bsg_cmd_cachep, GFP_KERNEL);
 118         if (unlikely(!bc)) {
 119                 spin_lock_irq(&bd->lock);
 120                 bd->queued_cmds--;
 121                 bc = ERR_PTR(-ENOMEM);
 122                 goto out;
 123         }
 124
 125         bc->bd = bd;
 126         INIT_LIST_HEAD(&bc->list);
 127         dprintk("%s: returning free cmd %p\n", bd->name, bc);
 128         return bc;
 129 out:
 130         spin_unlock_irq(&bd->lock);
 131         return bc;
 132 }
 133
 134 static inline struct hlist_head *bsg_dev_idx_hash(int index)
 135 {
 136         return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
 137 }
 138
 139 static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
 140                                 struct sg_io_v4 *hdr, struct bsg_device *bd,
 141                                 fmode_t has_write_perm)
 142 {
 143         if (hdr->request_len > BLK_MAX_CDB) {
 144                 rq->cmd = kzalloc(hdr->request_len, GFP_KERNEL);
 145                 if (!rq->cmd)
 146                         return -ENOMEM;
 147         }
 148
 149         if (copy_from_user(rq->cmd, (void __user *)(unsigned long)hdr->request,
 150                            hdr->request_len))
 151                 return -EFAULT;
 152
 153         if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
 154                 if (blk_verify_command(rq->cmd, has_write_perm))
 155                         return -EPERM;
 156         } else if (!capable(CAP_SYS_RAWIO))
 157                 return -EPERM;
 158
 159         /*
 160          * fill in request structure
 161          */
 162         rq->cmd_len = hdr->request_len;
 163
 164         rq->timeout = msecs_to_jiffies(hdr->timeout);
 165         if (!rq->timeout)
 166                 rq->timeout = q->sg_timeout;
 167         if (!rq->timeout)
 168                 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
 169         if (rq->timeout < BLK_MIN_SG_TIMEOUT)
 170                 rq->timeout = BLK_MIN_SG_TIMEOUT;
 171
 172         return 0;
 173 }
 174
 175 /*
 176  * Check if sg_io_v4 from user is allowed and valid
 177  */
 178 static int
 179 bsg_validate_sgv4_hdr(struct sg_io_v4 *hdr, int *rw)
 180 {
 181         int ret = 0;
 182
 183         if (hdr->guard != 'Q')
 184                 return -EINVAL;
 185
 186         switch (hdr->protocol) {
 187         case BSG_PROTOCOL_SCSI:
 188                 switch (hdr->subprotocol) {
 189                 case BSG_SUB_PROTOCOL_SCSI_CMD:
 190                 case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
 191                         break;
 192                 default:
 193                         ret = -EINVAL;
 194                 }
 195                 break;
 196         default:
 197                 ret = -EINVAL;
 198         }
 199
 200         *rw = hdr->dout_xfer_len ? WRITE : READ;
 201         return ret;
 202 }
 203
 204 /*
 205  * map sg_io_v4 to a request.
 206  */
 207 static struct request *
 208 bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
 209             u8 *sense)
 210 {
 211         struct request_queue *q = bd->queue;
 212         struct request *rq, *next_rq = NULL;
 213         int ret, rw;
 214         unsigned int dxfer_len;
 215         void __user *dxferp = NULL;
 216         struct bsg_class_device *bcd = &q->bsg_dev;
 217
 218         /* if the LLD has been removed then the bsg_unregister_queue will
 219          * eventually be called and the class_dev was freed, so we can no
 220          * longer use this request_queue. Return no such address.
 221          */
 222         if (!bcd->class_dev)
 223                 return ERR_PTR(-ENXIO);
 224
 225         dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
 226                 hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
 227                 hdr->din_xfer_len);
 228
 229         ret = bsg_validate_sgv4_hdr(hdr, &rw);
 230         if (ret)
 231                 return ERR_PTR(ret);
 232
 233         /*
 234          * map scatter-gather elements separately and string them to request
 235          */
 236         rq = blk_get_request(q, rw, GFP_KERNEL);
 237         if (IS_ERR(rq))
 238                 return rq;
 239         blk_rq_set_block_pc(rq);
 240
 241         ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
 242         if (ret)
 243                 goto out;
 244
 245         if (rw == WRITE && hdr->din_xfer_len) {
 246                 if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
 247                         ret = -EOPNOTSUPP;
 248                         goto out;
 249                 }
 250
 251                 next_rq = blk_get_request(q, READ, GFP_KERNEL);
 252                 if (IS_ERR(next_rq)) {
 253                         ret = PTR_ERR(next_rq);
 254                         next_rq = NULL;
 255                         goto out;
 256                 }
 257                 rq->next_rq = next_rq;
 258                 next_rq->cmd_type = rq->cmd_type;
 259
 260                 dxferp = (void __user *)(unsigned long)hdr->din_xferp;
 261                 ret =  blk_rq_map_user(q, next_rq, NULL, dxferp,
 262                                        hdr->din_xfer_len, GFP_KERNEL);
 263                 if (ret)
 264                         goto out;
 265         }
 266
 267         if (hdr->dout_xfer_len) {
 268                 dxfer_len = hdr->dout_xfer_len;
 269                 dxferp = (void __user *)(unsigned long)hdr->dout_xferp;
 270         } else if (hdr->din_xfer_len) {
 271                 dxfer_len = hdr->din_xfer_len;
 272                 dxferp = (void __user *)(unsigned long)hdr->din_xferp;
 273         } else
 274                 dxfer_len = 0;
 275
 276         if (dxfer_len) {
 277                 ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
 278                                       GFP_KERNEL);
 279                 if (ret)
 280                         goto out;
 281         }
 282
 283         rq->sense = sense;
 284         rq->sense_len = 0;
 285
 286         return rq;
 287 out:
 288         if (rq->cmd != rq->__cmd)
 289                 kfree(rq->cmd);
 290         blk_put_request(rq);
 291         if (next_rq) {
 292                 blk_rq_unmap_user(next_rq->bio);
 293                 blk_put_request(next_rq);
 294         }
 295         return ERR_PTR(ret);
 296 }
 297
 298 /*
 299  * async completion call-back from the block layer, when scsi/ide/whatever
 300  * calls end_that_request_last() on a request
 301  */
 302 static void bsg_rq_end_io(struct request *rq, int uptodate)
 303 {
 304         struct bsg_command *bc = rq->end_io_data;
 305         struct bsg_device *bd = bc->bd;
 306         unsigned long flags;
 307
 308         dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
 309                 bd->name, rq, bc, bc->bio, uptodate);
 310
 311         bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
 312
 313         spin_lock_irqsave(&bd->lock, flags);
 314         list_move_tail(&bc->list, &bd->done_list);
 315         bd->done_cmds++;
 316         spin_unlock_irqrestore(&bd->lock, flags);
 317
 318         wake_up(&bd->wq_done);
 319 }
 320
 321 /*
 322  * do final setup of a 'bc' and submit the matching 'rq' to the block
 323  * layer for io
 324  */
 325 static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
 326                             struct bsg_command *bc, struct request *rq)
 327 {
 328         int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));
 329
 330         /*
 331          * add bc command to busy queue and submit rq for io
 332          */
 333         bc->rq = rq;
 334         bc->bio = rq->bio;
 335         if (rq->next_rq)
 336                 bc->bidi_bio = rq->next_rq->bio;
 337         bc->hdr.duration = jiffies;
 338         spin_lock_irq(&bd->lock);
 339         list_add_tail(&bc->list, &bd->busy_list);
 340         spin_unlock_irq(&bd->lock);
 341
 342         dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
 343
 344         rq->end_io_data = bc;
 345         blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
 346 }
 347
 348 static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
 349 {
 350         struct bsg_command *bc = NULL;
 351
 352         spin_lock_irq(&bd->lock);
 353         if (bd->done_cmds) {
 354                 bc = list_first_entry(&bd->done_list, struct bsg_command, list);
 355                 list_del(&bc->list);
 356                 bd->done_cmds--;
 357         }
 358         spin_unlock_irq(&bd->lock);
 359
 360         return bc;
 361 }
 362
 363 /*
 364  * Get a finished command from the done list
 365  */
 366 static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
 367 {
 368         struct bsg_command *bc;
 369         int ret;
 370
 371         do {
 372                 bc = bsg_next_done_cmd(bd);
 373                 if (bc)
 374                         break;
 375
 376                 if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
 377                         bc = ERR_PTR(-EAGAIN);
 378                         break;
 379                 }
 380
 381                 ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
 382                 if (ret) {
 383                         bc = ERR_PTR(-ERESTARTSYS);
 384                         break;
 385                 }
 386         } while (1);
 387
 388         dprintk("%s: returning done %p\n", bd->name, bc);
 389
 390         return bc;
 391 }
 392
 393 static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
 394                                     struct bio *bio, struct bio *bidi_bio)
 395 {
 396         int ret = 0;
 397
 398         dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
 399         /*
 400          * fill in all the output members
 401          */
 402         hdr->device_status = rq->errors & 0xff;
 403         hdr->transport_status = host_byte(rq->errors);
 404         hdr->driver_status = driver_byte(rq->errors);
 405         hdr->info = 0;
 406         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
 407                 hdr->info |= SG_INFO_CHECK;
 408         hdr->response_len = 0;
 409
 410         if (rq->sense_len && hdr->response) {
 411                 int len = min_t(unsigned int, hdr->max_response_len,
 412                                         rq->sense_len);
 413
 414                 ret = copy_to_user((void __user *)(unsigned long)hdr->response,
 415                                    rq->sense, len);
 416                 if (!ret)
 417                         hdr->response_len = len;
 418                 else
 419                         ret = -EFAULT;
 420         }
 421
 422         if (rq->next_rq) {
 423                 hdr->dout_resid = rq->resid_len;
 424                 hdr->din_resid = rq->next_rq->resid_len;
 425                 blk_rq_unmap_user(bidi_bio);
 426                 blk_put_request(rq->next_rq);
 427         } else if (rq_data_dir(rq) == READ)
 428                 hdr->din_resid = rq->resid_len;
 429         else
 430                 hdr->dout_resid = rq->resid_len;
 431
 432         /*
 433          * If the request generated a negative error number, return it
 434          * (providing we aren't already returning an error); if it's
 435          * just a protocol response (i.e. non negative), that gets
 436          * processed above.
 437          */
 438         if (!ret && rq->errors < 0)
 439                 ret = rq->errors;
 440
 441         blk_rq_unmap_user(bio);
 442         if (rq->cmd != rq->__cmd)
 443                 kfree(rq->cmd);
 444         blk_put_request(rq);
 445
 446         return ret;
 447 }
 448
 449 static bool bsg_complete(struct bsg_device *bd)
 450 {
 451         bool ret = false;
 452         bool spin;
 453
 454         do {
 455                 spin_lock_irq(&bd->lock);
 456
 457                 BUG_ON(bd->done_cmds > bd->queued_cmds);
 458
 459                 /*
 460                  * All commands consumed.
 461                  */
 462                 if (bd->done_cmds == bd->queued_cmds)
 463                         ret = true;
 464
 465                 spin = !test_bit(BSG_F_BLOCK, &bd->flags);
 466
 467                 spin_unlock_irq(&bd->lock);
 468         } while (!ret && spin);
 469
 470         return ret;
 471 }
 472
 473 static int bsg_complete_all_commands(struct bsg_device *bd)
 474 {
 475         struct bsg_command *bc;
 476         int ret, tret;
 477
 478         dprintk("%s: entered\n", bd->name);
 479
 480         /*
 481          * wait for all commands to complete
 482          */
 483         io_wait_event(bd->wq_done, bsg_complete(bd));
 484
 485         /*
 486          * discard done commands
 487          */
 488         ret = 0;
 489         do {
 490                 spin_lock_irq(&bd->lock);
 491                 if (!bd->queued_cmds) {
 492                         spin_unlock_irq(&bd->lock);
 493                         break;
 494                 }
 495                 spin_unlock_irq(&bd->lock);
 496
 497                 bc = bsg_get_done_cmd(bd);
 498                 if (IS_ERR(bc))
 499                         break;
 500
 501                 tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 502                                                 bc->bidi_bio);
 503                 if (!ret)
 504                         ret = tret;
 505
 506                 bsg_free_command(bc);
 507         } while (1);
 508
 509         return ret;
 510 }
 511
 512 static int
 513 __bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
 514            const struct iovec *iov, ssize_t *bytes_read)
 515 {
 516         struct bsg_command *bc;
 517         int nr_commands, ret;
 518
 519         if (count % sizeof(struct sg_io_v4))
 520                 return -EINVAL;
 521
 522         ret = 0;
 523         nr_commands = count / sizeof(struct sg_io_v4);
 524         while (nr_commands) {
 525                 bc = bsg_get_done_cmd(bd);
 526                 if (IS_ERR(bc)) {
 527                         ret = PTR_ERR(bc);
 528                         break;
 529                 }
 530
 531                 /*
 532                  * this is the only case where we need to copy data back
 533                  * after completing the request. so do that here,
 534                  * bsg_complete_work() cannot do that for us
 535                  */
 536                 ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 537                                                bc->bidi_bio);
 538
 539                 if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
 540                         ret = -EFAULT;
 541
 542                 bsg_free_command(bc);
 543
 544                 if (ret)
 545                         break;
 546
 547                 buf += sizeof(struct sg_io_v4);
 548                 *bytes_read += sizeof(struct sg_io_v4);
 549                 nr_commands--;
 550         }
 551
 552         return ret;
 553 }
 554
 555 static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
 556 {
 557         if (file->f_flags & O_NONBLOCK)
 558                 clear_bit(BSG_F_BLOCK, &bd->flags);
 559         else
 560                 set_bit(BSG_F_BLOCK, &bd->flags);
 561 }
 562
 563 /*
 564  * Check if the error is a "real" error that we should return.
 565  */
 566 static inline int err_block_err(int ret)
 567 {
 568         if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
 569                 return 1;
 570
 571         return 0;
 572 }
 573
 574 static ssize_t
 575 bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 576 {
 577         struct bsg_device *bd = file->private_data;
 578         int ret;
 579         ssize_t bytes_read;
 580
 581         dprintk("%s: read %Zd bytes\n", bd->name, count);
 582
 583         bsg_set_block(bd, file);
 584
 585         bytes_read = 0;
 586         ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
 587         *ppos = bytes_read;
 588
 589         if (!bytes_read || err_block_err(ret))
 590                 bytes_read = ret;
 591
 592         return bytes_read;
 593 }
 594
 595 static int __bsg_write(struct bsg_device *bd, const char __user *buf,
 596                        size_t count, ssize_t *bytes_written,
 597                        fmode_t has_write_perm)
 598 {
 599         struct bsg_command *bc;
 600         struct request *rq;
 601         int ret, nr_commands;
 602
 603         if (count % sizeof(struct sg_io_v4))
 604                 return -EINVAL;
 605
 606         nr_commands = count / sizeof(struct sg_io_v4);
 607         rq = NULL;
 608         bc = NULL;
 609         ret = 0;
 610         while (nr_commands) {
 611                 struct request_queue *q = bd->queue;
 612
 613                 bc = bsg_alloc_command(bd);
 614                 if (IS_ERR(bc)) {
 615                         ret = PTR_ERR(bc);
 616                         bc = NULL;
 617                         break;
 618                 }
 619
 620                 if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
 621                         ret = -EFAULT;
 622                         break;
 623                 }
 624
 625                 /*
 626                  * get a request, fill in the blanks, and add to request queue
 627                  */
 628                 rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
 629                 if (IS_ERR(rq)) {
 630                         ret = PTR_ERR(rq);
 631                         rq = NULL;
 632                         break;
 633                 }
 634
 635                 bsg_add_command(bd, q, bc, rq);
 636                 bc = NULL;
 637                 rq = NULL;
 638                 nr_commands--;
 639                 buf += sizeof(struct sg_io_v4);
 640                 *bytes_written += sizeof(struct sg_io_v4);
 641         }
 642
 643         if (bc)
 644                 bsg_free_command(bc);
 645
 646         return ret;
 647 }
 648
 649 static ssize_t
 650 bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 651 {
 652         struct bsg_device *bd = file->private_data;
 653         ssize_t bytes_written;
 654         int ret;
 655
 656         dprintk("%s: write %Zd bytes\n", bd->name, count);
 657
 658         if (unlikely(segment_eq(get_fs(), KERNEL_DS)))
 659                 return -EINVAL;
 660
 661         bsg_set_block(bd, file);
 662
 663         bytes_written = 0;
 664         ret = __bsg_write(bd, buf, count, &bytes_written,
 665                           file->f_mode & FMODE_WRITE);
 666
 667         *ppos = bytes_written;
 668
 669         /*
 670          * return bytes written on non-fatal errors
 671          */
 672         if (!bytes_written || err_block_err(ret))
 673                 bytes_written = ret;
 674
 675         dprintk("%s: returning %Zd\n", bd->name, bytes_written);
 676         return bytes_written;
 677 }
 678
 679 static struct bsg_device *bsg_alloc_device(void)
 680 {
 681         struct bsg_device *bd;
 682
 683         bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
 684         if (unlikely(!bd))
 685                 return NULL;
 686
 687         spin_lock_init(&bd->lock);
 688
 689         bd->max_queue = BSG_DEFAULT_CMDS;
 690
 691         INIT_LIST_HEAD(&bd->busy_list);
 692         INIT_LIST_HEAD(&bd->done_list);
 693         INIT_HLIST_NODE(&bd->dev_list);
 694
 695         init_waitqueue_head(&bd->wq_free);
 696         init_waitqueue_head(&bd->wq_done);
 697         return bd;
 698 }
 699
 700 static void bsg_kref_release_function(struct kref *kref)
 701 {
 702         struct bsg_class_device *bcd =
 703                 container_of(kref, struct bsg_class_device, ref);
 704         struct device *parent = bcd->parent;
 705
 706         if (bcd->release)
 707                 bcd->release(bcd->parent);
 708
 709         put_device(parent);
 710 }
 711
 712 static int bsg_put_device(struct bsg_device *bd)
 713 {
 714         int ret = 0, do_free;
 715         struct request_queue *q = bd->queue;
 716
 717         mutex_lock(&bsg_mutex);
 718
 719         do_free = atomic_dec_and_test(&bd->ref_count);
 720         if (!do_free) {
 721                 mutex_unlock(&bsg_mutex);
 722                 goto out;
 723         }
 724
 725         hlist_del(&bd->dev_list);
 726         mutex_unlock(&bsg_mutex);
 727
 728         dprintk("%s: tearing down\n", bd->name);
 729
 730         /*
 731          * close can always block
 732          */
 733         set_bit(BSG_F_BLOCK, &bd->flags);
 734
 735         /*
 736          * correct error detection baddies here again. it's the responsibility
 737          * of the app to properly reap commands before close() if it wants
 738          * fool-proof error detection
 739          */
 740         ret = bsg_complete_all_commands(bd);
 741
 742         kfree(bd);
 743 out:
 744         kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
 745         if (do_free)
 746                 blk_put_queue(q);
 747         return ret;
 748 }
 749
 750 static struct bsg_device *bsg_add_device(struct inode *inode,
 751                                          struct request_queue *rq,
 752                                          struct file *file)
 753 {
 754         struct bsg_device *bd;
 755 #ifdef BSG_DEBUG
 756         unsigned char buf[32];
 757 #endif
 758         if (!blk_get_queue(rq))
 759                 return ERR_PTR(-ENXIO);
 760
 761         bd = bsg_alloc_device();
 762         if (!bd) {
 763                 blk_put_queue(rq);
 764                 return ERR_PTR(-ENOMEM);
 765         }
 766
 767         bd->queue = rq;
 768
 769         bsg_set_block(bd, file);
 770
 771         atomic_set(&bd->ref_count, 1);
 772         mutex_lock(&bsg_mutex);
 773         hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 774
 775         strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
 776         dprintk("bound to <%s>, max queue %d\n",
 777                 format_dev_t(buf, inode->i_rdev), bd->max_queue);
 778
 779         mutex_unlock(&bsg_mutex);
 780         return bd;
 781 }
 782
 783 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 784 {
 785         struct bsg_device *bd;
 786
 787         mutex_lock(&bsg_mutex);
 788
 789         hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
 790                 if (bd->queue == q) {
 791                         atomic_inc(&bd->ref_count);
 792                         goto found;
 793                 }
 794         }
 795         bd = NULL;
 796 found:
 797         mutex_unlock(&bsg_mutex);
 798         return bd;
 799 }
 800
 801 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 802 {
 803         struct bsg_device *bd;
 804         struct bsg_class_device *bcd;
 805
 806         /*
 807          * find the class device
 808          */
 809         mutex_lock(&bsg_mutex);
 810         bcd = idr_find(&bsg_minor_idr, iminor(inode));
 811         if (bcd)
 812                 kref_get(&bcd->ref);
 813         mutex_unlock(&bsg_mutex);
 814
 815         if (!bcd)
 816                 return ERR_PTR(-ENODEV);
 817
 818         bd = __bsg_get_device(iminor(inode), bcd->queue);
 819         if (bd)
 820                 return bd;
 821
 822         bd = bsg_add_device(inode, bcd->queue, file);
 823         if (IS_ERR(bd))
 824                 kref_put(&bcd->ref, bsg_kref_release_function);
 825
 826         return bd;
 827 }
 828
 829 static int bsg_open(struct inode *inode, struct file *file)
 830 {
 831         struct bsg_device *bd;
 832
 833         bd = bsg_get_device(inode, file);
 834
 835         if (IS_ERR(bd))
 836                 return PTR_ERR(bd);
 837
 838         file->private_data = bd;
 839         return 0;
 840 }
 841
 842 static int bsg_release(struct inode *inode, struct file *file)
 843 {
 844         struct bsg_device *bd = file->private_data;
 845
 846         file->private_data = NULL;
 847         return bsg_put_device(bd);
 848 }
 849
 850 static unsigned int bsg_poll(struct file *file, poll_table *wait)
 851 {
 852         struct bsg_device *bd = file->private_data;
 853         unsigned int mask = 0;
 854
 855         poll_wait(file, &bd->wq_done, wait);
 856         poll_wait(file, &bd->wq_free, wait);
 857
 858         spin_lock_irq(&bd->lock);
 859         if (!list_empty(&bd->done_list))
 860                 mask |= POLLIN | POLLRDNORM;
 861         if (bd->queued_cmds < bd->max_queue)
 862                 mask |= POLLOUT;
 863         spin_unlock_irq(&bd->lock);
 864
 865         return mask;
 866 }
 867
 868 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 869 {
 870         struct bsg_device *bd = file->private_data;
 871         int __user *uarg = (int __user *) arg;
 872         int ret;
 873
 874         switch (cmd) {
 875                 /*
 876                  * our own ioctls
 877                  */
 878         case SG_GET_COMMAND_Q:
 879                 return put_user(bd->max_queue, uarg);
 880         case SG_SET_COMMAND_Q: {
 881                 int queue;
 882
 883                 if (get_user(queue, uarg))
 884                         return -EFAULT;
 885                 if (queue < 1)
 886                         return -EINVAL;
 887
 888                 spin_lock_irq(&bd->lock);
 889                 bd->max_queue = queue;
 890                 spin_unlock_irq(&bd->lock);
 891                 return 0;
 892         }
 893
 894         /*
 895          * SCSI/sg ioctls
 896          */
 897         case SG_GET_VERSION_NUM:
 898         case SCSI_IOCTL_GET_IDLUN:
 899         case SCSI_IOCTL_GET_BUS_NUMBER:
 900         case SG_SET_TIMEOUT:
 901         case SG_GET_TIMEOUT:
 902         case SG_GET_RESERVED_SIZE:
 903         case SG_SET_RESERVED_SIZE:
 904         case SG_EMULATED_HOST:
 905         case SCSI_IOCTL_SEND_COMMAND: {
 906                 void __user *uarg = (void __user *) arg;
 907                 return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
 908         }
 909         case SG_IO: {
 910                 struct request *rq;
 911                 struct bio *bio, *bidi_bio = NULL;
 912                 struct sg_io_v4 hdr;
 913                 int at_head;
 914                 u8 sense[SCSI_SENSE_BUFFERSIZE];
 915
 916                 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 917                         return -EFAULT;
 918
 919                 rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
 920                 if (IS_ERR(rq))
 921                         return PTR_ERR(rq);
 922
 923                 bio = rq->bio;
 924                 if (rq->next_rq)
 925                         bidi_bio = rq->next_rq->bio;
 926
 927                 at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
 928                 blk_execute_rq(bd->queue, NULL, rq, at_head);
 929                 ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
 930
 931                 if (copy_to_user(uarg, &hdr, sizeof(hdr)))
 932                         return -EFAULT;
 933
 934                 return ret;
 935         }
 936         /*
 937          * block device ioctls
 938          */
 939         default:
 940 #if 0
 941                 return ioctl_by_bdev(bd->bdev, cmd, arg);
 942 #else
 943                 return -ENOTTY;
 944 #endif
 945         }
 946 }
 947
 948 static const struct file_operations bsg_fops = {
 949         .read           =       bsg_read,
 950         .write          =       bsg_write,
 951         .poll           =       bsg_poll,
 952         .open           =       bsg_open,
 953         .release        =       bsg_release,
 954         .unlocked_ioctl =       bsg_ioctl,
 955         .owner          =       THIS_MODULE,
 956         .llseek         =       default_llseek,
 957 };
 958
 959 void bsg_unregister_queue(struct request_queue *q)
 960 {
 961         struct bsg_class_device *bcd = &q->bsg_dev;
 962
 963         if (!bcd->class_dev)
 964                 return;
 965
 966         mutex_lock(&bsg_mutex);
 967         idr_remove(&bsg_minor_idr, bcd->minor);
 968         if (q->kobj.sd)
 969                 sysfs_remove_link(&q->kobj, "bsg");
 970         device_unregister(bcd->class_dev);
 971         bcd->class_dev = NULL;
 972         kref_put(&bcd->ref, bsg_kref_release_function);
 973         mutex_unlock(&bsg_mutex);
 974 }
 975 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 976
 977 int bsg_register_queue(struct request_queue *q, struct device *parent,
 978                        const char *name, void (*release)(struct device *))
 979 {
 980         struct bsg_class_device *bcd;
 981         dev_t dev;
 982         int ret;
 983         struct device *class_dev = NULL;
 984         const char *devname;
 985
 986         if (name)
 987                 devname = name;
 988         else
 989                 devname = dev_name(parent);
 990
 991         /*
 992          * we need a proper transport to send commands, not a stacked device
 993          */
 994         if (!queue_is_rq_based(q))
 995                 return 0;
 996
 997         bcd = &q->bsg_dev;
 998         memset(bcd, 0, sizeof(*bcd));
 999
1000         mutex_lock(&bsg_mutex);
1001
1002         ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
1003         if (ret < 0) {
1004                 if (ret == -ENOSPC) {
1005                         printk(KERN_ERR "bsg: too many bsg devices\n");
1006                         ret = -EINVAL;
1007                 }
1008                 goto unlock;
1009         }
1010
1011         bcd->minor = ret;
1012         bcd->queue = q;
1013         bcd->parent = get_device(parent);
1014         bcd->release = release;
1015         kref_init(&bcd->ref);
1016         dev = MKDEV(bsg_major, bcd->minor);
1017         class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1018         if (IS_ERR(class_dev)) {
1019                 ret = PTR_ERR(class_dev);
1020                 goto put_dev;
1021         }
1022         bcd->class_dev = class_dev;
1023
1024         if (q->kobj.sd) {
1025                 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1026                 if (ret)
1027                         goto unregister_class_dev;
1028         }
1029
1030         mutex_unlock(&bsg_mutex);
1031         return 0;
1032
1033 unregister_class_dev:
1034         device_unregister(class_dev);
1035 put_dev:
1036         put_device(parent);
1037         idr_remove(&bsg_minor_idr, bcd->minor);
1038 unlock:
1039         mutex_unlock(&bsg_mutex);
1040         return ret;
1041 }
1042 EXPORT_SYMBOL_GPL(bsg_register_queue);
1043
1044 static struct cdev bsg_cdev;
1045
1046 static char *bsg_devnode(struct device *dev, umode_t *mode)
1047 {
1048         return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
1049 }
1050
1051 static int __init bsg_init(void)
1052 {
1053         int ret, i;
1054         dev_t devid;
1055
1056         bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1057                                 sizeof(struct bsg_command), 0, 0, NULL);
1058         if (!bsg_cmd_cachep) {
1059                 printk(KERN_ERR "bsg: failed creating slab cache\n");
1060                 return -ENOMEM;
1061         }
1062
1063         for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1064                 INIT_HLIST_HEAD(&bsg_device_list[i]);
1065
1066         bsg_class = class_create(THIS_MODULE, "bsg");
1067         if (IS_ERR(bsg_class)) {
1068                 ret = PTR_ERR(bsg_class);
1069                 goto destroy_kmemcache;
1070         }
1071         bsg_class->devnode = bsg_devnode;
1072
1073         ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1074         if (ret)
1075                 goto destroy_bsg_class;
1076
1077         bsg_major = MAJOR(devid);
1078
1079         cdev_init(&bsg_cdev, &bsg_fops);
1080         ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1081         if (ret)
1082                 goto unregister_chrdev;
1083
1084         printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1085                " loaded (major %d)\n", bsg_major);
1086         return 0;
1087 unregister_chrdev:
1088         unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1089 destroy_bsg_class:
1090         class_destroy(bsg_class);
1091 destroy_kmemcache:
1092         kmem_cache_destroy(bsg_cmd_cachep);
1093         return ret;
1094 }
1095
1096 MODULE_AUTHOR("Jens Axboe");
1097 MODULE_DESCRIPTION(BSG_DESCRIPTION);
1098 MODULE_LICENSE("GPL");
1099
1100 device_initcall(bsg_init);