block/bsg.c

   1 /*
   2  * bsg.c - block layer implementation of the sg v4 interface
   3  *
   4  * Copyright (C) 2004 Jens Axboe <axboe@suse.de> SUSE Labs
   5  * Copyright (C) 2004 Peter M. Jones <pjones@redhat.com>
   6  *
   7  *  This file is subject to the terms and conditions of the GNU General Public
   8  *  License version 2.  See the file "COPYING" in the main directory of this
   9  *  archive for more details.
  10  *
  11  */
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/file.h>
  15 #include <linux/blkdev.h>
  16 #include <linux/poll.h>
  17 #include <linux/cdev.h>
  18 #include <linux/percpu.h>
  19 #include <linux/uio.h>
  20 #include <linux/idr.h>
  21 #include <linux/bsg.h>
  22 #include <linux/smp_lock.h>
  23
  24 #include <scsi/scsi.h>
  25 #include <scsi/scsi_ioctl.h>
  26 #include <scsi/scsi_cmnd.h>
  27 #include <scsi/scsi_device.h>
  28 #include <scsi/scsi_driver.h>
  29 #include <scsi/sg.h>
  30
  31 #define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
  32 #define BSG_VERSION     "0.4"
  33
  34 struct bsg_device {
  35         struct request_queue *queue;
  36         spinlock_t lock;
  37         struct list_head busy_list;
  38         struct list_head done_list;
  39         struct hlist_node dev_list;
  40         atomic_t ref_count;
  41         int queued_cmds;
  42         int done_cmds;
  43         wait_queue_head_t wq_done;
  44         wait_queue_head_t wq_free;
  45         char name[BUS_ID_SIZE];
  46         int max_queue;
  47         unsigned long flags;
  48 };
  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                                 int 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
 206         return 0;
 207 }
 208
 209 /*
 210  * Check if sg_io_v4 from user is allowed and valid
 211  */
 212 static int
 213 bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
 214 {
 215         int ret = 0;
 216
 217         if (hdr->guard != 'Q')
 218                 return -EINVAL;
 219         if (hdr->dout_xfer_len > (q->max_sectors << 9) ||
 220             hdr->din_xfer_len > (q->max_sectors << 9))
 221                 return -EIO;
 222
 223         switch (hdr->protocol) {
 224         case BSG_PROTOCOL_SCSI:
 225                 switch (hdr->subprotocol) {
 226                 case BSG_SUB_PROTOCOL_SCSI_CMD:
 227                 case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
 228                         break;
 229                 default:
 230                         ret = -EINVAL;
 231                 }
 232                 break;
 233         default:
 234                 ret = -EINVAL;
 235         }
 236
 237         *rw = hdr->dout_xfer_len ? WRITE : READ;
 238         return ret;
 239 }
 240
 241 /*
 242  * map sg_io_v4 to a request.
 243  */
 244 static struct request *
 245 bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, int has_write_perm)
 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, dxferp, hdr->din_xfer_len);
 287                 if (ret)
 288                         goto out;
 289         }
 290
 291         if (hdr->dout_xfer_len) {
 292                 dxfer_len = hdr->dout_xfer_len;
 293                 dxferp = (void*)(unsigned long)hdr->dout_xferp;
 294         } else if (hdr->din_xfer_len) {
 295                 dxfer_len = hdr->din_xfer_len;
 296                 dxferp = (void*)(unsigned long)hdr->din_xferp;
 297         } else
 298                 dxfer_len = 0;
 299
 300         if (dxfer_len) {
 301                 ret = blk_rq_map_user(q, rq, dxferp, dxfer_len);
 302                 if (ret)
 303                         goto out;
 304         }
 305         return rq;
 306 out:
 307         if (rq->cmd != rq->__cmd)
 308                 kfree(rq->cmd);
 309         blk_put_request(rq);
 310         if (next_rq) {
 311                 blk_rq_unmap_user(next_rq->bio);
 312                 blk_put_request(next_rq);
 313         }
 314         return ERR_PTR(ret);
 315 }
 316
 317 /*
 318  * async completion call-back from the block layer, when scsi/ide/whatever
 319  * calls end_that_request_last() on a request
 320  */
 321 static void bsg_rq_end_io(struct request *rq, int uptodate)
 322 {
 323         struct bsg_command *bc = rq->end_io_data;
 324         struct bsg_device *bd = bc->bd;
 325         unsigned long flags;
 326
 327         dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
 328                 bd->name, rq, bc, bc->bio, uptodate);
 329
 330         bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
 331
 332         spin_lock_irqsave(&bd->lock, flags);
 333         list_move_tail(&bc->list, &bd->done_list);
 334         bd->done_cmds++;
 335         spin_unlock_irqrestore(&bd->lock, flags);
 336
 337         wake_up(&bd->wq_done);
 338 }
 339
 340 /*
 341  * do final setup of a 'bc' and submit the matching 'rq' to the block
 342  * layer for io
 343  */
 344 static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
 345                             struct bsg_command *bc, struct request *rq)
 346 {
 347         rq->sense = bc->sense;
 348         rq->sense_len = 0;
 349
 350         /*
 351          * add bc command to busy queue and submit rq for io
 352          */
 353         bc->rq = rq;
 354         bc->bio = rq->bio;
 355         if (rq->next_rq)
 356                 bc->bidi_bio = rq->next_rq->bio;
 357         bc->hdr.duration = jiffies;
 358         spin_lock_irq(&bd->lock);
 359         list_add_tail(&bc->list, &bd->busy_list);
 360         spin_unlock_irq(&bd->lock);
 361
 362         dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
 363
 364         rq->end_io_data = bc;
 365         blk_execute_rq_nowait(q, NULL, rq, 1, bsg_rq_end_io);
 366 }
 367
 368 static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
 369 {
 370         struct bsg_command *bc = NULL;
 371
 372         spin_lock_irq(&bd->lock);
 373         if (bd->done_cmds) {
 374                 bc = list_first_entry(&bd->done_list, struct bsg_command, list);
 375                 list_del(&bc->list);
 376                 bd->done_cmds--;
 377         }
 378         spin_unlock_irq(&bd->lock);
 379
 380         return bc;
 381 }
 382
 383 /*
 384  * Get a finished command from the done list
 385  */
 386 static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
 387 {
 388         struct bsg_command *bc;
 389         int ret;
 390
 391         do {
 392                 bc = bsg_next_done_cmd(bd);
 393                 if (bc)
 394                         break;
 395
 396                 if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
 397                         bc = ERR_PTR(-EAGAIN);
 398                         break;
 399                 }
 400
 401                 ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
 402                 if (ret) {
 403                         bc = ERR_PTR(-ERESTARTSYS);
 404                         break;
 405                 }
 406         } while (1);
 407
 408         dprintk("%s: returning done %p\n", bd->name, bc);
 409
 410         return bc;
 411 }
 412
 413 static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
 414                                     struct bio *bio, struct bio *bidi_bio)
 415 {
 416         int ret = 0;
 417
 418         dprintk("rq %p bio %p %u\n", rq, bio, rq->errors);
 419         /*
 420          * fill in all the output members
 421          */
 422         hdr->device_status = status_byte(rq->errors);
 423         hdr->transport_status = host_byte(rq->errors);
 424         hdr->driver_status = driver_byte(rq->errors);
 425         hdr->info = 0;
 426         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
 427                 hdr->info |= SG_INFO_CHECK;
 428         hdr->response_len = 0;
 429
 430         if (rq->sense_len && hdr->response) {
 431                 int len = min_t(unsigned int, hdr->max_response_len,
 432                                         rq->sense_len);
 433
 434                 ret = copy_to_user((void*)(unsigned long)hdr->response,
 435                                    rq->sense, len);
 436                 if (!ret)
 437                         hdr->response_len = len;
 438                 else
 439                         ret = -EFAULT;
 440         }
 441
 442         if (rq->next_rq) {
 443                 hdr->dout_resid = rq->data_len;
 444                 hdr->din_resid = rq->next_rq->data_len;
 445                 blk_rq_unmap_user(bidi_bio);
 446                 blk_put_request(rq->next_rq);
 447         } else if (rq_data_dir(rq) == READ)
 448                 hdr->din_resid = rq->data_len;
 449         else
 450                 hdr->dout_resid = rq->data_len;
 451
 452         /*
 453          * If the request generated a negative error number, return it
 454          * (providing we aren't already returning an error); if it's
 455          * just a protocol response (i.e. non negative), that gets
 456          * processed above.
 457          */
 458         if (!ret && rq->errors < 0)
 459                 ret = rq->errors;
 460
 461         blk_rq_unmap_user(bio);
 462         if (rq->cmd != rq->__cmd)
 463                 kfree(rq->cmd);
 464         blk_put_request(rq);
 465
 466         return ret;
 467 }
 468
 469 static int bsg_complete_all_commands(struct bsg_device *bd)
 470 {
 471         struct bsg_command *bc;
 472         int ret, tret;
 473
 474         dprintk("%s: entered\n", bd->name);
 475
 476         /*
 477          * wait for all commands to complete
 478          */
 479         ret = 0;
 480         do {
 481                 ret = bsg_io_schedule(bd);
 482                 /*
 483                  * look for -ENODATA specifically -- we'll sometimes get
 484                  * -ERESTARTSYS when we've taken a signal, but we can't
 485                  * return until we're done freeing the queue, so ignore
 486                  * it.  The signal will get handled when we're done freeing
 487                  * the bsg_device.
 488                  */
 489         } while (ret != -ENODATA);
 490
 491         /*
 492          * discard done commands
 493          */
 494         ret = 0;
 495         do {
 496                 spin_lock_irq(&bd->lock);
 497                 if (!bd->queued_cmds) {
 498                         spin_unlock_irq(&bd->lock);
 499                         break;
 500                 }
 501                 spin_unlock_irq(&bd->lock);
 502
 503                 bc = bsg_get_done_cmd(bd);
 504                 if (IS_ERR(bc))
 505                         break;
 506
 507                 tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 508                                                 bc->bidi_bio);
 509                 if (!ret)
 510                         ret = tret;
 511
 512                 bsg_free_command(bc);
 513         } while (1);
 514
 515         return ret;
 516 }
 517
 518 static int
 519 __bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
 520            const struct iovec *iov, ssize_t *bytes_read)
 521 {
 522         struct bsg_command *bc;
 523         int nr_commands, ret;
 524
 525         if (count % sizeof(struct sg_io_v4))
 526                 return -EINVAL;
 527
 528         ret = 0;
 529         nr_commands = count / sizeof(struct sg_io_v4);
 530         while (nr_commands) {
 531                 bc = bsg_get_done_cmd(bd);
 532                 if (IS_ERR(bc)) {
 533                         ret = PTR_ERR(bc);
 534                         break;
 535                 }
 536
 537                 /*
 538                  * this is the only case where we need to copy data back
 539                  * after completing the request. so do that here,
 540                  * bsg_complete_work() cannot do that for us
 541                  */
 542                 ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 543                                                bc->bidi_bio);
 544
 545                 if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
 546                         ret = -EFAULT;
 547
 548                 bsg_free_command(bc);
 549
 550                 if (ret)
 551                         break;
 552
 553                 buf += sizeof(struct sg_io_v4);
 554                 *bytes_read += sizeof(struct sg_io_v4);
 555                 nr_commands--;
 556         }
 557
 558         return ret;
 559 }
 560
 561 static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
 562 {
 563         if (file->f_flags & O_NONBLOCK)
 564                 clear_bit(BSG_F_BLOCK, &bd->flags);
 565         else
 566                 set_bit(BSG_F_BLOCK, &bd->flags);
 567 }
 568
 569 /*
 570  * Check if the error is a "real" error that we should return.
 571  */
 572 static inline int err_block_err(int ret)
 573 {
 574         if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
 575                 return 1;
 576
 577         return 0;
 578 }
 579
 580 static ssize_t
 581 bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 582 {
 583         struct bsg_device *bd = file->private_data;
 584         int ret;
 585         ssize_t bytes_read;
 586
 587         dprintk("%s: read %Zd bytes\n", bd->name, count);
 588
 589         bsg_set_block(bd, file);
 590
 591         bytes_read = 0;
 592         ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
 593         *ppos = bytes_read;
 594
 595         if (!bytes_read || (bytes_read && err_block_err(ret)))
 596                 bytes_read = ret;
 597
 598         return bytes_read;
 599 }
 600
 601 static int __bsg_write(struct bsg_device *bd, const char __user *buf,
 602                        size_t count, ssize_t *bytes_written, int has_write_perm)
 603 {
 604         struct bsg_command *bc;
 605         struct request *rq;
 606         int ret, nr_commands;
 607
 608         if (count % sizeof(struct sg_io_v4))
 609                 return -EINVAL;
 610
 611         nr_commands = count / sizeof(struct sg_io_v4);
 612         rq = NULL;
 613         bc = NULL;
 614         ret = 0;
 615         while (nr_commands) {
 616                 struct request_queue *q = bd->queue;
 617
 618                 bc = bsg_alloc_command(bd);
 619                 if (IS_ERR(bc)) {
 620                         ret = PTR_ERR(bc);
 621                         bc = NULL;
 622                         break;
 623                 }
 624
 625                 if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
 626                         ret = -EFAULT;
 627                         break;
 628                 }
 629
 630                 /*
 631                  * get a request, fill in the blanks, and add to request queue
 632                  */
 633                 rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm);
 634                 if (IS_ERR(rq)) {
 635                         ret = PTR_ERR(rq);
 636                         rq = NULL;
 637                         break;
 638                 }
 639
 640                 bsg_add_command(bd, q, bc, rq);
 641                 bc = NULL;
 642                 rq = NULL;
 643                 nr_commands--;
 644                 buf += sizeof(struct sg_io_v4);
 645                 *bytes_written += sizeof(struct sg_io_v4);
 646         }
 647
 648         if (bc)
 649                 bsg_free_command(bc);
 650
 651         return ret;
 652 }
 653
 654 static ssize_t
 655 bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 656 {
 657         struct bsg_device *bd = file->private_data;
 658         ssize_t bytes_written;
 659         int ret;
 660
 661         dprintk("%s: write %Zd bytes\n", bd->name, count);
 662
 663         bsg_set_block(bd, file);
 664
 665         bytes_written = 0;
 666         ret = __bsg_write(bd, buf, count, &bytes_written,
 667                           file->f_mode & FMODE_WRITE);
 668
 669         *ppos = bytes_written;
 670
 671         /*
 672          * return bytes written on non-fatal errors
 673          */
 674         if (!bytes_written || (bytes_written && err_block_err(ret)))
 675                 bytes_written = ret;
 676
 677         dprintk("%s: returning %Zd\n", bd->name, bytes_written);
 678         return bytes_written;
 679 }
 680
 681 static struct bsg_device *bsg_alloc_device(void)
 682 {
 683         struct bsg_device *bd;
 684
 685         bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
 686         if (unlikely(!bd))
 687                 return NULL;
 688
 689         spin_lock_init(&bd->lock);
 690
 691         bd->max_queue = BSG_DEFAULT_CMDS;
 692
 693         INIT_LIST_HEAD(&bd->busy_list);
 694         INIT_LIST_HEAD(&bd->done_list);
 695         INIT_HLIST_NODE(&bd->dev_list);
 696
 697         init_waitqueue_head(&bd->wq_free);
 698         init_waitqueue_head(&bd->wq_done);
 699         return bd;
 700 }
 701
 702 static void bsg_kref_release_function(struct kref *kref)
 703 {
 704         struct bsg_class_device *bcd =
 705                 container_of(kref, struct bsg_class_device, ref);
 706         struct device *parent = bcd->parent;
 707
 708         if (bcd->release)
 709                 bcd->release(bcd->parent);
 710
 711         put_device(parent);
 712 }
 713
 714 static int bsg_put_device(struct bsg_device *bd)
 715 {
 716         int ret = 0, do_free;
 717         struct request_queue *q = bd->queue;
 718
 719         mutex_lock(&bsg_mutex);
 720
 721         do_free = atomic_dec_and_test(&bd->ref_count);
 722         if (!do_free) {
 723                 mutex_unlock(&bsg_mutex);
 724                 goto out;
 725         }
 726
 727         hlist_del(&bd->dev_list);
 728         mutex_unlock(&bsg_mutex);
 729
 730         dprintk("%s: tearing down\n", bd->name);
 731
 732         /*
 733          * close can always block
 734          */
 735         set_bit(BSG_F_BLOCK, &bd->flags);
 736
 737         /*
 738          * correct error detection baddies here again. it's the responsibility
 739          * of the app to properly reap commands before close() if it wants
 740          * fool-proof error detection
 741          */
 742         ret = bsg_complete_all_commands(bd);
 743
 744         kfree(bd);
 745 out:
 746         kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
 747         if (do_free)
 748                 blk_put_queue(q);
 749         return ret;
 750 }
 751
 752 static struct bsg_device *bsg_add_device(struct inode *inode,
 753                                          struct request_queue *rq,
 754                                          struct file *file)
 755 {
 756         struct bsg_device *bd;
 757         int ret;
 758 #ifdef BSG_DEBUG
 759         unsigned char buf[32];
 760 #endif
 761         ret = blk_get_queue(rq);
 762         if (ret)
 763                 return ERR_PTR(-ENXIO);
 764
 765         bd = bsg_alloc_device();
 766         if (!bd) {
 767                 blk_put_queue(rq);
 768                 return ERR_PTR(-ENOMEM);
 769         }
 770
 771         bd->queue = rq;
 772
 773         bsg_set_block(bd, file);
 774
 775         atomic_set(&bd->ref_count, 1);
 776         mutex_lock(&bsg_mutex);
 777         hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 778
 779         strncpy(bd->name, rq->bsg_dev.class_dev->bus_id, sizeof(bd->name) - 1);
 780         dprintk("bound to <%s>, max queue %d\n",
 781                 format_dev_t(buf, inode->i_rdev), bd->max_queue);
 782
 783         mutex_unlock(&bsg_mutex);
 784         return bd;
 785 }
 786
 787 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 788 {
 789         struct bsg_device *bd;
 790         struct hlist_node *entry;
 791
 792         mutex_lock(&bsg_mutex);
 793
 794         hlist_for_each_entry(bd, entry, bsg_dev_idx_hash(minor), dev_list) {
 795                 if (bd->queue == q) {
 796                         atomic_inc(&bd->ref_count);
 797                         goto found;
 798                 }
 799         }
 800         bd = NULL;
 801 found:
 802         mutex_unlock(&bsg_mutex);
 803         return bd;
 804 }
 805
 806 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 807 {
 808         struct bsg_device *bd;
 809         struct bsg_class_device *bcd;
 810
 811         /*
 812          * find the class device
 813          */
 814         mutex_lock(&bsg_mutex);
 815         bcd = idr_find(&bsg_minor_idr, iminor(inode));
 816         if (bcd)
 817                 kref_get(&bcd->ref);
 818         mutex_unlock(&bsg_mutex);
 819
 820         if (!bcd)
 821                 return ERR_PTR(-ENODEV);
 822
 823         bd = __bsg_get_device(iminor(inode), bcd->queue);
 824         if (bd)
 825                 return bd;
 826
 827         bd = bsg_add_device(inode, bcd->queue, file);
 828         if (IS_ERR(bd))
 829                 kref_put(&bcd->ref, bsg_kref_release_function);
 830
 831         return bd;
 832 }
 833
 834 static int bsg_open(struct inode *inode, struct file *file)
 835 {
 836         struct bsg_device *bd;
 837
 838         lock_kernel();
 839         bd = bsg_get_device(inode, file);
 840         unlock_kernel();
 841
 842         if (IS_ERR(bd))
 843                 return PTR_ERR(bd);
 844
 845         file->private_data = bd;
 846         return 0;
 847 }
 848
 849 static int bsg_release(struct inode *inode, struct file *file)
 850 {
 851         struct bsg_device *bd = file->private_data;
 852
 853         file->private_data = NULL;
 854         return bsg_put_device(bd);
 855 }
 856
 857 static unsigned int bsg_poll(struct file *file, poll_table *wait)
 858 {
 859         struct bsg_device *bd = file->private_data;
 860         unsigned int mask = 0;
 861
 862         poll_wait(file, &bd->wq_done, wait);
 863         poll_wait(file, &bd->wq_free, wait);
 864
 865         spin_lock_irq(&bd->lock);
 866         if (!list_empty(&bd->done_list))
 867                 mask |= POLLIN | POLLRDNORM;
 868         if (bd->queued_cmds >= bd->max_queue)
 869                 mask |= POLLOUT;
 870         spin_unlock_irq(&bd->lock);
 871
 872         return mask;
 873 }
 874
 875 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 876 {
 877         struct bsg_device *bd = file->private_data;
 878         int __user *uarg = (int __user *) arg;
 879         int ret;
 880
 881         switch (cmd) {
 882                 /*
 883                  * our own ioctls
 884                  */
 885         case SG_GET_COMMAND_Q:
 886                 return put_user(bd->max_queue, uarg);
 887         case SG_SET_COMMAND_Q: {
 888                 int queue;
 889
 890                 if (get_user(queue, uarg))
 891                         return -EFAULT;
 892                 if (queue < 1)
 893                         return -EINVAL;
 894
 895                 spin_lock_irq(&bd->lock);
 896                 bd->max_queue = queue;
 897                 spin_unlock_irq(&bd->lock);
 898                 return 0;
 899         }
 900
 901         /*
 902          * SCSI/sg ioctls
 903          */
 904         case SG_GET_VERSION_NUM:
 905         case SCSI_IOCTL_GET_IDLUN:
 906         case SCSI_IOCTL_GET_BUS_NUMBER:
 907         case SG_SET_TIMEOUT:
 908         case SG_GET_TIMEOUT:
 909         case SG_GET_RESERVED_SIZE:
 910         case SG_SET_RESERVED_SIZE:
 911         case SG_EMULATED_HOST:
 912         case SCSI_IOCTL_SEND_COMMAND: {
 913                 void __user *uarg = (void __user *) arg;
 914                 return scsi_cmd_ioctl(file, bd->queue, NULL, cmd, uarg);
 915         }
 916         case SG_IO: {
 917                 struct request *rq;
 918                 struct bio *bio, *bidi_bio = NULL;
 919                 struct sg_io_v4 hdr;
 920
 921                 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 922                         return -EFAULT;
 923
 924                 rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE);
 925                 if (IS_ERR(rq))
 926                         return PTR_ERR(rq);
 927
 928                 bio = rq->bio;
 929                 if (rq->next_rq)
 930                         bidi_bio = rq->next_rq->bio;
 931                 blk_execute_rq(bd->queue, NULL, rq, 0);
 932                 ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
 933
 934                 if (copy_to_user(uarg, &hdr, sizeof(hdr)))
 935                         return -EFAULT;
 936
 937                 return ret;
 938         }
 939         /*
 940          * block device ioctls
 941          */
 942         default:
 943 #if 0
 944                 return ioctl_by_bdev(bd->bdev, cmd, arg);
 945 #else
 946                 return -ENOTTY;
 947 #endif
 948         }
 949 }
 950
 951 static const struct file_operations bsg_fops = {
 952         .read           =       bsg_read,
 953         .write          =       bsg_write,
 954         .poll           =       bsg_poll,
 955         .open           =       bsg_open,
 956         .release        =       bsg_release,
 957         .unlocked_ioctl =       bsg_ioctl,
 958         .owner          =       THIS_MODULE,
 959 };
 960
 961 void bsg_unregister_queue(struct request_queue *q)
 962 {
 963         struct bsg_class_device *bcd = &q->bsg_dev;
 964
 965         if (!bcd->class_dev)
 966                 return;
 967
 968         mutex_lock(&bsg_mutex);
 969         idr_remove(&bsg_minor_idr, bcd->minor);
 970         sysfs_remove_link(&q->kobj, "bsg");
 971         device_unregister(bcd->class_dev);
 972         bcd->class_dev = NULL;
 973         kref_put(&bcd->ref, bsg_kref_release_function);
 974         mutex_unlock(&bsg_mutex);
 975 }
 976 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 977
 978 int bsg_register_queue(struct request_queue *q, struct device *parent,
 979                        const char *name, void (*release)(struct device *))
 980 {
 981         struct bsg_class_device *bcd;
 982         dev_t dev;
 983         int ret, minor;
 984         struct device *class_dev = NULL;
 985         const char *devname;
 986
 987         if (name)
 988                 devname = name;
 989         else
 990                 devname = parent->bus_id;
 991
 992         /*
 993          * we need a proper transport to send commands, not a stacked device
 994          */
 995         if (!q->request_fn)
 996                 return 0;
 997
 998         bcd = &q->bsg_dev;
 999         memset(bcd, 0, sizeof(*bcd));
1000
1001         mutex_lock(&bsg_mutex);
1002
1003         ret = idr_pre_get(&bsg_minor_idr, GFP_KERNEL);
1004         if (!ret) {
1005                 ret = -ENOMEM;
1006                 goto unlock;
1007         }
1008
1009         ret = idr_get_new(&bsg_minor_idr, bcd, &minor);
1010         if (ret < 0)
1011                 goto unlock;
1012
1013         if (minor >= BSG_MAX_DEVS) {
1014                 printk(KERN_ERR "bsg: too many bsg devices\n");
1015                 ret = -EINVAL;
1016                 goto remove_idr;
1017         }
1018
1019         bcd->minor = minor;
1020         bcd->queue = q;
1021         bcd->parent = get_device(parent);
1022         bcd->release = release;
1023         kref_init(&bcd->ref);
1024         dev = MKDEV(bsg_major, bcd->minor);
1025         class_dev = device_create_drvdata(bsg_class, parent, dev, NULL,
1026                                           "%s", devname);
1027         if (IS_ERR(class_dev)) {
1028                 ret = PTR_ERR(class_dev);
1029                 goto put_dev;
1030         }
1031         bcd->class_dev = class_dev;
1032
1033         if (q->kobj.sd) {
1034                 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1035                 if (ret)
1036                         goto unregister_class_dev;
1037         }
1038
1039         mutex_unlock(&bsg_mutex);
1040         return 0;
1041
1042 unregister_class_dev:
1043         device_unregister(class_dev);
1044 put_dev:
1045         put_device(parent);
1046 remove_idr:
1047         idr_remove(&bsg_minor_idr, minor);
1048 unlock:
1049         mutex_unlock(&bsg_mutex);
1050         return ret;
1051 }
1052 EXPORT_SYMBOL_GPL(bsg_register_queue);
1053
1054 static struct cdev bsg_cdev;
1055
1056 static int __init bsg_init(void)
1057 {
1058         int ret, i;
1059         dev_t devid;
1060
1061         bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1062                                 sizeof(struct bsg_command), 0, 0, NULL);
1063         if (!bsg_cmd_cachep) {
1064                 printk(KERN_ERR "bsg: failed creating slab cache\n");
1065                 return -ENOMEM;
1066         }
1067
1068         for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1069                 INIT_HLIST_HEAD(&bsg_device_list[i]);
1070
1071         bsg_class = class_create(THIS_MODULE, "bsg");
1072         if (IS_ERR(bsg_class)) {
1073                 ret = PTR_ERR(bsg_class);
1074                 goto destroy_kmemcache;
1075         }
1076
1077         ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1078         if (ret)
1079                 goto destroy_bsg_class;
1080
1081         bsg_major = MAJOR(devid);
1082
1083         cdev_init(&bsg_cdev, &bsg_fops);
1084         ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1085         if (ret)
1086                 goto unregister_chrdev;
1087
1088         printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1089                " loaded (major %d)\n", bsg_major);
1090         return 0;
1091 unregister_chrdev:
1092         unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1093 destroy_bsg_class:
1094         class_destroy(bsg_class);
1095 destroy_kmemcache:
1096         kmem_cache_destroy(bsg_cmd_cachep);
1097         return ret;
1098 }
1099
1100 MODULE_AUTHOR("Jens Axboe");
1101 MODULE_DESCRIPTION(BSG_DESCRIPTION);
1102 MODULE_LICENSE("GPL");
1103
1104 device_initcall(bsg_init);