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