linux/block/bsg.c
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   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
  34struct bsg_device {
  35        struct request_queue *queue;
  36        spinlock_t lock;
  37        struct list_head busy_list;
  38        struct list_head done_list;
  39        struct hlist_node dev_list;
  40        atomic_t ref_count;
  41        int queued_cmds;
  42        int done_cmds;
  43        wait_queue_head_t wq_done;
  44        wait_queue_head_t wq_free;
  45        char name[20];
  46        int max_queue;
  47        unsigned long flags;
  48};
  49
  50enum {
  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
  65static DEFINE_MUTEX(bsg_mutex);
  66static DEFINE_IDR(bsg_minor_idr);
  67
  68#define BSG_LIST_ARRAY_SIZE     8
  69static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
  70
  71static struct class *bsg_class;
  72static int bsg_major;
  73
  74static struct kmem_cache *bsg_cmd_cachep;
  75
  76/*
  77 * our internal command type
  78 */
  79struct 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
  90static 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
 104static 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;
 128out:
 129        spin_unlock_irq(&bd->lock);
 130        return bc;
 131}
 132
 133static inline struct hlist_head *bsg_dev_idx_hash(int index)
 134{
 135        return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
 136}
 137
 138static 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;
 169unlock:
 170        spin_unlock_irq(&bd->lock);
 171        return ret;
 172}
 173
 174static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
 175                                struct sg_io_v4 *hdr, struct bsg_device *bd,
 176                                fmode_t has_write_perm)
 177{
 178        if (hdr->request_len > BLK_MAX_CDB) {
 179                rq->cmd = kzalloc(hdr->request_len, GFP_KERNEL);
 180                if (!rq->cmd)
 181                        return -ENOMEM;
 182        }
 183
 184        if (copy_from_user(rq->cmd, (void *)(unsigned long)hdr->request,
 185                           hdr->request_len))
 186                return -EFAULT;
 187
 188        if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
 189                if (blk_verify_command(&q->cmd_filter, rq->cmd, has_write_perm))
 190                        return -EPERM;
 191        } else if (!capable(CAP_SYS_RAWIO))
 192                return -EPERM;
 193
 194        /*
 195         * fill in request structure
 196         */
 197        rq->cmd_len = hdr->request_len;
 198        rq->cmd_type = REQ_TYPE_BLOCK_PC;
 199
 200        rq->timeout = (hdr->timeout * HZ) / 1000;
 201        if (!rq->timeout)
 202                rq->timeout = q->sg_timeout;
 203        if (!rq->timeout)
 204                rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
 205        if (rq->timeout < BLK_MIN_SG_TIMEOUT)
 206                rq->timeout = BLK_MIN_SG_TIMEOUT;
 207
 208        return 0;
 209}
 210
 211/*
 212 * Check if sg_io_v4 from user is allowed and valid
 213 */
 214static int
 215bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
 216{
 217        int ret = 0;
 218
 219        if (hdr->guard != 'Q')
 220                return -EINVAL;
 221
 222        switch (hdr->protocol) {
 223        case BSG_PROTOCOL_SCSI:
 224                switch (hdr->subprotocol) {
 225                case BSG_SUB_PROTOCOL_SCSI_CMD:
 226                case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
 227                        break;
 228                default:
 229                        ret = -EINVAL;
 230                }
 231                break;
 232        default:
 233                ret = -EINVAL;
 234        }
 235
 236        *rw = hdr->dout_xfer_len ? WRITE : READ;
 237        return ret;
 238}
 239
 240/*
 241 * map sg_io_v4 to a request.
 242 */
 243static struct request *
 244bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
 245            u8 *sense)
 246{
 247        struct request_queue *q = bd->queue;
 248        struct request *rq, *next_rq = NULL;
 249        int ret, rw;
 250        unsigned int dxfer_len;
 251        void *dxferp = NULL;
 252
 253        dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
 254                hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
 255                hdr->din_xfer_len);
 256
 257        ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
 258        if (ret)
 259                return ERR_PTR(ret);
 260
 261        /*
 262         * map scatter-gather elements seperately and string them to request
 263         */
 264        rq = blk_get_request(q, rw, GFP_KERNEL);
 265        if (!rq)
 266                return ERR_PTR(-ENOMEM);
 267        ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
 268        if (ret)
 269                goto out;
 270
 271        if (rw == WRITE && hdr->din_xfer_len) {
 272                if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
 273                        ret = -EOPNOTSUPP;
 274                        goto out;
 275                }
 276
 277                next_rq = blk_get_request(q, READ, GFP_KERNEL);
 278                if (!next_rq) {
 279                        ret = -ENOMEM;
 280                        goto out;
 281                }
 282                rq->next_rq = next_rq;
 283                next_rq->cmd_type = rq->cmd_type;
 284
 285                dxferp = (void*)(unsigned long)hdr->din_xferp;
 286                ret =  blk_rq_map_user(q, next_rq, NULL, dxferp,
 287                                       hdr->din_xfer_len, GFP_KERNEL);
 288                if (ret)
 289                        goto out;
 290        }
 291
 292        if (hdr->dout_xfer_len) {
 293                dxfer_len = hdr->dout_xfer_len;
 294                dxferp = (void*)(unsigned long)hdr->dout_xferp;
 295        } else if (hdr->din_xfer_len) {
 296                dxfer_len = hdr->din_xfer_len;
 297                dxferp = (void*)(unsigned long)hdr->din_xferp;
 298        } else
 299                dxfer_len = 0;
 300
 301        if (dxfer_len) {
 302                ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
 303                                      GFP_KERNEL);
 304                if (ret)
 305                        goto out;
 306        }
 307
 308        rq->sense = sense;
 309        rq->sense_len = 0;
 310
 311        return rq;
 312out:
 313        if (rq->cmd != rq->__cmd)
 314                kfree(rq->cmd);
 315        blk_put_request(rq);
 316        if (next_rq) {
 317                blk_rq_unmap_user(next_rq->bio);
 318                next_rq->bio = NULL;
 319                blk_put_request(next_rq);
 320        }
 321        return ERR_PTR(ret);
 322}
 323
 324/*
 325 * async completion call-back from the block layer, when scsi/ide/whatever
 326 * calls end_that_request_last() on a request
 327 */
 328static void bsg_rq_end_io(struct request *rq, int uptodate)
 329{
 330        struct bsg_command *bc = rq->end_io_data;
 331        struct bsg_device *bd = bc->bd;
 332        unsigned long flags;
 333
 334        dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
 335                bd->name, rq, bc, bc->bio, uptodate);
 336
 337        bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
 338
 339        spin_lock_irqsave(&bd->lock, flags);
 340        list_move_tail(&bc->list, &bd->done_list);
 341        bd->done_cmds++;
 342        spin_unlock_irqrestore(&bd->lock, flags);
 343
 344        wake_up(&bd->wq_done);
 345}
 346
 347/*
 348 * do final setup of a 'bc' and submit the matching 'rq' to the block
 349 * layer for io
 350 */
 351static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
 352                            struct bsg_command *bc, struct request *rq)
 353{
 354        int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));
 355
 356        /*
 357         * add bc command to busy queue and submit rq for io
 358         */
 359        bc->rq = rq;
 360        bc->bio = rq->bio;
 361        if (rq->next_rq)
 362                bc->bidi_bio = rq->next_rq->bio;
 363        bc->hdr.duration = jiffies;
 364        spin_lock_irq(&bd->lock);
 365        list_add_tail(&bc->list, &bd->busy_list);
 366        spin_unlock_irq(&bd->lock);
 367
 368        dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
 369
 370        rq->end_io_data = bc;
 371        blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
 372}
 373
 374static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
 375{
 376        struct bsg_command *bc = NULL;
 377
 378        spin_lock_irq(&bd->lock);
 379        if (bd->done_cmds) {
 380                bc = list_first_entry(&bd->done_list, struct bsg_command, list);
 381                list_del(&bc->list);
 382                bd->done_cmds--;
 383        }
 384        spin_unlock_irq(&bd->lock);
 385
 386        return bc;
 387}
 388
 389/*
 390 * Get a finished command from the done list
 391 */
 392static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
 393{
 394        struct bsg_command *bc;
 395        int ret;
 396
 397        do {
 398                bc = bsg_next_done_cmd(bd);
 399                if (bc)
 400                        break;
 401
 402                if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
 403                        bc = ERR_PTR(-EAGAIN);
 404                        break;
 405                }
 406
 407                ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
 408                if (ret) {
 409                        bc = ERR_PTR(-ERESTARTSYS);
 410                        break;
 411                }
 412        } while (1);
 413
 414        dprintk("%s: returning done %p\n", bd->name, bc);
 415
 416        return bc;
 417}
 418
 419static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
 420                                    struct bio *bio, struct bio *bidi_bio)
 421{
 422        int ret = 0;
 423
 424        dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
 425        /*
 426         * fill in all the output members
 427         */
 428        hdr->device_status = status_byte(rq->errors);
 429        hdr->transport_status = host_byte(rq->errors);
 430        hdr->driver_status = driver_byte(rq->errors);
 431        hdr->info = 0;
 432        if (hdr->device_status || hdr->transport_status || hdr->driver_status)
 433                hdr->info |= SG_INFO_CHECK;
 434        hdr->response_len = 0;
 435
 436        if (rq->sense_len && hdr->response) {
 437                int len = min_t(unsigned int, hdr->max_response_len,
 438                                        rq->sense_len);
 439
 440                ret = copy_to_user((void*)(unsigned long)hdr->response,
 441                                   rq->sense, len);
 442                if (!ret)
 443                        hdr->response_len = len;
 444                else
 445                        ret = -EFAULT;
 446        }
 447
 448        if (rq->next_rq) {
 449                hdr->dout_resid = rq->data_len;
 450                hdr->din_resid = rq->next_rq->data_len;
 451                blk_rq_unmap_user(bidi_bio);
 452                rq->next_rq->bio = NULL;
 453                blk_put_request(rq->next_rq);
 454        } else if (rq_data_dir(rq) == READ)
 455                hdr->din_resid = rq->data_len;
 456        else
 457                hdr->dout_resid = rq->data_len;
 458
 459        /*
 460         * If the request generated a negative error number, return it
 461         * (providing we aren't already returning an error); if it's
 462         * just a protocol response (i.e. non negative), that gets
 463         * processed above.
 464         */
 465        if (!ret && rq->errors < 0)
 466                ret = rq->errors;
 467
 468        blk_rq_unmap_user(bio);
 469        if (rq->cmd != rq->__cmd)
 470                kfree(rq->cmd);
 471        rq->bio = NULL;
 472        blk_put_request(rq);
 473
 474        return ret;
 475}
 476
 477static int bsg_complete_all_commands(struct bsg_device *bd)
 478{
 479        struct bsg_command *bc;
 480        int ret, tret;
 481
 482        dprintk("%s: entered\n", bd->name);
 483
 484        /*
 485         * wait for all commands to complete
 486         */
 487        ret = 0;
 488        do {
 489                ret = bsg_io_schedule(bd);
 490                /*
 491                 * look for -ENODATA specifically -- we'll sometimes get
 492                 * -ERESTARTSYS when we've taken a signal, but we can't
 493                 * return until we're done freeing the queue, so ignore
 494                 * it.  The signal will get handled when we're done freeing
 495                 * the bsg_device.
 496                 */
 497        } while (ret != -ENODATA);
 498
 499        /*
 500         * discard done commands
 501         */
 502        ret = 0;
 503        do {
 504                spin_lock_irq(&bd->lock);
 505                if (!bd->queued_cmds) {
 506                        spin_unlock_irq(&bd->lock);
 507                        break;
 508                }
 509                spin_unlock_irq(&bd->lock);
 510
 511                bc = bsg_get_done_cmd(bd);
 512                if (IS_ERR(bc))
 513                        break;
 514
 515                tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 516                                                bc->bidi_bio);
 517                if (!ret)
 518                        ret = tret;
 519
 520                bsg_free_command(bc);
 521        } while (1);
 522
 523        return ret;
 524}
 525
 526static int
 527__bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
 528           const struct iovec *iov, ssize_t *bytes_read)
 529{
 530        struct bsg_command *bc;
 531        int nr_commands, ret;
 532
 533        if (count % sizeof(struct sg_io_v4))
 534                return -EINVAL;
 535
 536        ret = 0;
 537        nr_commands = count / sizeof(struct sg_io_v4);
 538        while (nr_commands) {
 539                bc = bsg_get_done_cmd(bd);
 540                if (IS_ERR(bc)) {
 541                        ret = PTR_ERR(bc);
 542                        break;
 543                }
 544
 545                /*
 546                 * this is the only case where we need to copy data back
 547                 * after completing the request. so do that here,
 548                 * bsg_complete_work() cannot do that for us
 549                 */
 550                ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 551                                               bc->bidi_bio);
 552
 553                if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
 554                        ret = -EFAULT;
 555
 556                bsg_free_command(bc);
 557
 558                if (ret)
 559                        break;
 560
 561                buf += sizeof(struct sg_io_v4);
 562                *bytes_read += sizeof(struct sg_io_v4);
 563                nr_commands--;
 564        }
 565
 566        return ret;
 567}
 568
 569static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
 570{
 571        if (file->f_flags & O_NONBLOCK)
 572                clear_bit(BSG_F_BLOCK, &bd->flags);
 573        else
 574                set_bit(BSG_F_BLOCK, &bd->flags);
 575}
 576
 577/*
 578 * Check if the error is a "real" error that we should return.
 579 */
 580static inline int err_block_err(int ret)
 581{
 582        if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
 583                return 1;
 584
 585        return 0;
 586}
 587
 588static ssize_t
 589bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 590{
 591        struct bsg_device *bd = file->private_data;
 592        int ret;
 593        ssize_t bytes_read;
 594
 595        dprintk("%s: read %Zd bytes\n", bd->name, count);
 596
 597        bsg_set_block(bd, file);
 598
 599        bytes_read = 0;
 600        ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
 601        *ppos = bytes_read;
 602
 603        if (!bytes_read || (bytes_read && err_block_err(ret)))
 604                bytes_read = ret;
 605
 606        return bytes_read;
 607}
 608
 609static int __bsg_write(struct bsg_device *bd, const char __user *buf,
 610                       size_t count, ssize_t *bytes_written,
 611                       fmode_t has_write_perm)
 612{
 613        struct bsg_command *bc;
 614        struct request *rq;
 615        int ret, nr_commands;
 616
 617        if (count % sizeof(struct sg_io_v4))
 618                return -EINVAL;
 619
 620        nr_commands = count / sizeof(struct sg_io_v4);
 621        rq = NULL;
 622        bc = NULL;
 623        ret = 0;
 624        while (nr_commands) {
 625                struct request_queue *q = bd->queue;
 626
 627                bc = bsg_alloc_command(bd);
 628                if (IS_ERR(bc)) {
 629                        ret = PTR_ERR(bc);
 630                        bc = NULL;
 631                        break;
 632                }
 633
 634                if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
 635                        ret = -EFAULT;
 636                        break;
 637                }
 638
 639                /*
 640                 * get a request, fill in the blanks, and add to request queue
 641                 */
 642                rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
 643                if (IS_ERR(rq)) {
 644                        ret = PTR_ERR(rq);
 645                        rq = NULL;
 646                        break;
 647                }
 648
 649                bsg_add_command(bd, q, bc, rq);
 650                bc = NULL;
 651                rq = NULL;
 652                nr_commands--;
 653                buf += sizeof(struct sg_io_v4);
 654                *bytes_written += sizeof(struct sg_io_v4);
 655        }
 656
 657        if (bc)
 658                bsg_free_command(bc);
 659
 660        return ret;
 661}
 662
 663static ssize_t
 664bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 665{
 666        struct bsg_device *bd = file->private_data;
 667        ssize_t bytes_written;
 668        int ret;
 669
 670        dprintk("%s: write %Zd bytes\n", bd->name, count);
 671
 672        bsg_set_block(bd, file);
 673
 674        bytes_written = 0;
 675        ret = __bsg_write(bd, buf, count, &bytes_written,
 676                          file->f_mode & FMODE_WRITE);
 677
 678        *ppos = bytes_written;
 679
 680        /*
 681         * return bytes written on non-fatal errors
 682         */
 683        if (!bytes_written || (bytes_written && err_block_err(ret)))
 684                bytes_written = ret;
 685
 686        dprintk("%s: returning %Zd\n", bd->name, bytes_written);
 687        return bytes_written;
 688}
 689
 690static struct bsg_device *bsg_alloc_device(void)
 691{
 692        struct bsg_device *bd;
 693
 694        bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
 695        if (unlikely(!bd))
 696                return NULL;
 697
 698        spin_lock_init(&bd->lock);
 699
 700        bd->max_queue = BSG_DEFAULT_CMDS;
 701
 702        INIT_LIST_HEAD(&bd->busy_list);
 703        INIT_LIST_HEAD(&bd->done_list);
 704        INIT_HLIST_NODE(&bd->dev_list);
 705
 706        init_waitqueue_head(&bd->wq_free);
 707        init_waitqueue_head(&bd->wq_done);
 708        return bd;
 709}
 710
 711static void bsg_kref_release_function(struct kref *kref)
 712{
 713        struct bsg_class_device *bcd =
 714                container_of(kref, struct bsg_class_device, ref);
 715        struct device *parent = bcd->parent;
 716
 717        if (bcd->release)
 718                bcd->release(bcd->parent);
 719
 720        put_device(parent);
 721}
 722
 723static int bsg_put_device(struct bsg_device *bd)
 724{
 725        int ret = 0, do_free;
 726        struct request_queue *q = bd->queue;
 727
 728        mutex_lock(&bsg_mutex);
 729
 730        do_free = atomic_dec_and_test(&bd->ref_count);
 731        if (!do_free) {
 732                mutex_unlock(&bsg_mutex);
 733                goto out;
 734        }
 735
 736        hlist_del(&bd->dev_list);
 737        mutex_unlock(&bsg_mutex);
 738
 739        dprintk("%s: tearing down\n", bd->name);
 740
 741        /*
 742         * close can always block
 743         */
 744        set_bit(BSG_F_BLOCK, &bd->flags);
 745
 746        /*
 747         * correct error detection baddies here again. it's the responsibility
 748         * of the app to properly reap commands before close() if it wants
 749         * fool-proof error detection
 750         */
 751        ret = bsg_complete_all_commands(bd);
 752
 753        kfree(bd);
 754out:
 755        kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
 756        if (do_free)
 757                blk_put_queue(q);
 758        return ret;
 759}
 760
 761static struct bsg_device *bsg_add_device(struct inode *inode,
 762                                         struct request_queue *rq,
 763                                         struct file *file)
 764{
 765        struct bsg_device *bd;
 766        int ret;
 767#ifdef BSG_DEBUG
 768        unsigned char buf[32];
 769#endif
 770        ret = blk_get_queue(rq);
 771        if (ret)
 772                return ERR_PTR(-ENXIO);
 773
 774        bd = bsg_alloc_device();
 775        if (!bd) {
 776                blk_put_queue(rq);
 777                return ERR_PTR(-ENOMEM);
 778        }
 779
 780        bd->queue = rq;
 781
 782        bsg_set_block(bd, file);
 783
 784        atomic_set(&bd->ref_count, 1);
 785        mutex_lock(&bsg_mutex);
 786        hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 787
 788        strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
 789        dprintk("bound to <%s>, max queue %d\n",
 790                format_dev_t(buf, inode->i_rdev), bd->max_queue);
 791
 792        mutex_unlock(&bsg_mutex);
 793        return bd;
 794}
 795
 796static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 797{
 798        struct bsg_device *bd;
 799        struct hlist_node *entry;
 800
 801        mutex_lock(&bsg_mutex);
 802
 803        hlist_for_each_entry(bd, entry, bsg_dev_idx_hash(minor), dev_list) {
 804                if (bd->queue == q) {
 805                        atomic_inc(&bd->ref_count);
 806                        goto found;
 807                }
 808        }
 809        bd = NULL;
 810found:
 811        mutex_unlock(&bsg_mutex);
 812        return bd;
 813}
 814
 815static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 816{
 817        struct bsg_device *bd;
 818        struct bsg_class_device *bcd;
 819
 820        /*
 821         * find the class device
 822         */
 823        mutex_lock(&bsg_mutex);
 824        bcd = idr_find(&bsg_minor_idr, iminor(inode));
 825        if (bcd)
 826                kref_get(&bcd->ref);
 827        mutex_unlock(&bsg_mutex);
 828
 829        if (!bcd)
 830                return ERR_PTR(-ENODEV);
 831
 832        bd = __bsg_get_device(iminor(inode), bcd->queue);
 833        if (bd)
 834                return bd;
 835
 836        bd = bsg_add_device(inode, bcd->queue, file);
 837        if (IS_ERR(bd))
 838                kref_put(&bcd->ref, bsg_kref_release_function);
 839
 840        return bd;
 841}
 842
 843static int bsg_open(struct inode *inode, struct file *file)
 844{
 845        struct bsg_device *bd;
 846
 847        lock_kernel();
 848        bd = bsg_get_device(inode, file);
 849        unlock_kernel();
 850
 851        if (IS_ERR(bd))
 852                return PTR_ERR(bd);
 853
 854        file->private_data = bd;
 855        return 0;
 856}
 857
 858static int bsg_release(struct inode *inode, struct file *file)
 859{
 860        struct bsg_device *bd = file->private_data;
 861
 862        file->private_data = NULL;
 863        return bsg_put_device(bd);
 864}
 865
 866static unsigned int bsg_poll(struct file *file, poll_table *wait)
 867{
 868        struct bsg_device *bd = file->private_data;
 869        unsigned int mask = 0;
 870
 871        poll_wait(file, &bd->wq_done, wait);
 872        poll_wait(file, &bd->wq_free, wait);
 873
 874        spin_lock_irq(&bd->lock);
 875        if (!list_empty(&bd->done_list))
 876                mask |= POLLIN | POLLRDNORM;
 877        if (bd->queued_cmds >= bd->max_queue)
 878                mask |= POLLOUT;
 879        spin_unlock_irq(&bd->lock);
 880
 881        return mask;
 882}
 883
 884static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 885{
 886        struct bsg_device *bd = file->private_data;
 887        int __user *uarg = (int __user *) arg;
 888        int ret;
 889
 890        switch (cmd) {
 891                /*
 892                 * our own ioctls
 893                 */
 894        case SG_GET_COMMAND_Q:
 895                return put_user(bd->max_queue, uarg);
 896        case SG_SET_COMMAND_Q: {
 897                int queue;
 898
 899                if (get_user(queue, uarg))
 900                        return -EFAULT;
 901                if (queue < 1)
 902                        return -EINVAL;
 903
 904                spin_lock_irq(&bd->lock);
 905                bd->max_queue = queue;
 906                spin_unlock_irq(&bd->lock);
 907                return 0;
 908        }
 909
 910        /*
 911         * SCSI/sg ioctls
 912         */
 913        case SG_GET_VERSION_NUM:
 914        case SCSI_IOCTL_GET_IDLUN:
 915        case SCSI_IOCTL_GET_BUS_NUMBER:
 916        case SG_SET_TIMEOUT:
 917        case SG_GET_TIMEOUT:
 918        case SG_GET_RESERVED_SIZE:
 919        case SG_SET_RESERVED_SIZE:
 920        case SG_EMULATED_HOST:
 921        case SCSI_IOCTL_SEND_COMMAND: {
 922                void __user *uarg = (void __user *) arg;
 923                return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
 924        }
 925        case SG_IO: {
 926                struct request *rq;
 927                struct bio *bio, *bidi_bio = NULL;
 928                struct sg_io_v4 hdr;
 929                int at_head;
 930                u8 sense[SCSI_SENSE_BUFFERSIZE];
 931
 932                if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 933                        return -EFAULT;
 934
 935                rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
 936                if (IS_ERR(rq))
 937                        return PTR_ERR(rq);
 938
 939                bio = rq->bio;
 940                if (rq->next_rq)
 941                        bidi_bio = rq->next_rq->bio;
 942
 943                at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
 944                blk_execute_rq(bd->queue, NULL, rq, at_head);
 945                ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
 946
 947                if (copy_to_user(uarg, &hdr, sizeof(hdr)))
 948                        return -EFAULT;
 949
 950                return ret;
 951        }
 952        /*
 953         * block device ioctls
 954         */
 955        default:
 956#if 0
 957                return ioctl_by_bdev(bd->bdev, cmd, arg);
 958#else
 959                return -ENOTTY;
 960#endif
 961        }
 962}
 963
 964static const struct file_operations bsg_fops = {
 965        .read           =       bsg_read,
 966        .write          =       bsg_write,
 967        .poll           =       bsg_poll,
 968        .open           =       bsg_open,
 969        .release        =       bsg_release,
 970        .unlocked_ioctl =       bsg_ioctl,
 971        .owner          =       THIS_MODULE,
 972};
 973
 974void bsg_unregister_queue(struct request_queue *q)
 975{
 976        struct bsg_class_device *bcd = &q->bsg_dev;
 977
 978        if (!bcd->class_dev)
 979                return;
 980
 981        mutex_lock(&bsg_mutex);
 982        idr_remove(&bsg_minor_idr, bcd->minor);
 983        sysfs_remove_link(&q->kobj, "bsg");
 984        device_unregister(bcd->class_dev);
 985        bcd->class_dev = NULL;
 986        kref_put(&bcd->ref, bsg_kref_release_function);
 987        mutex_unlock(&bsg_mutex);
 988}
 989EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 990
 991int bsg_register_queue(struct request_queue *q, struct device *parent,
 992                       const char *name, void (*release)(struct device *))
 993{
 994        struct bsg_class_device *bcd;
 995        dev_t dev;
 996        int ret, minor;
 997        struct device *class_dev = NULL;
 998        const char *devname;
 999
1000        if (name)
1001                devname = name;
1002        else
1003                devname = dev_name(parent);
1004
1005        /*
1006         * we need a proper transport to send commands, not a stacked device
1007         */
1008        if (!q->request_fn)
1009                return 0;
1010
1011        bcd = &q->bsg_dev;
1012        memset(bcd, 0, sizeof(*bcd));
1013
1014        mutex_lock(&bsg_mutex);
1015
1016        ret = idr_pre_get(&bsg_minor_idr, GFP_KERNEL);
1017        if (!ret) {
1018                ret = -ENOMEM;
1019                goto unlock;
1020        }
1021
1022        ret = idr_get_new(&bsg_minor_idr, bcd, &minor);
1023        if (ret < 0)
1024                goto unlock;
1025
1026        if (minor >= BSG_MAX_DEVS) {
1027                printk(KERN_ERR "bsg: too many bsg devices\n");
1028                ret = -EINVAL;
1029                goto remove_idr;
1030        }
1031
1032        bcd->minor = minor;
1033        bcd->queue = q;
1034        bcd->parent = get_device(parent);
1035        bcd->release = release;
1036        kref_init(&bcd->ref);
1037        dev = MKDEV(bsg_major, bcd->minor);
1038        class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1039        if (IS_ERR(class_dev)) {
1040                ret = PTR_ERR(class_dev);
1041                goto put_dev;
1042        }
1043        bcd->class_dev = class_dev;
1044
1045        if (q->kobj.sd) {
1046                ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1047                if (ret)
1048                        goto unregister_class_dev;
1049        }
1050
1051        mutex_unlock(&bsg_mutex);
1052        return 0;
1053
1054unregister_class_dev:
1055        device_unregister(class_dev);
1056put_dev:
1057        put_device(parent);
1058remove_idr:
1059        idr_remove(&bsg_minor_idr, minor);
1060unlock:
1061        mutex_unlock(&bsg_mutex);
1062        return ret;
1063}
1064EXPORT_SYMBOL_GPL(bsg_register_queue);
1065
1066static struct cdev bsg_cdev;
1067
1068static int __init bsg_init(void)
1069{
1070        int ret, i;
1071        dev_t devid;
1072
1073        bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1074                                sizeof(struct bsg_command), 0, 0, NULL);
1075        if (!bsg_cmd_cachep) {
1076                printk(KERN_ERR "bsg: failed creating slab cache\n");
1077                return -ENOMEM;
1078        }
1079
1080        for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1081                INIT_HLIST_HEAD(&bsg_device_list[i]);
1082
1083        bsg_class = class_create(THIS_MODULE, "bsg");
1084        if (IS_ERR(bsg_class)) {
1085                ret = PTR_ERR(bsg_class);
1086                goto destroy_kmemcache;
1087        }
1088
1089        ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1090        if (ret)
1091                goto destroy_bsg_class;
1092
1093        bsg_major = MAJOR(devid);
1094
1095        cdev_init(&bsg_cdev, &bsg_fops);
1096        ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1097        if (ret)
1098                goto unregister_chrdev;
1099
1100        printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1101               " loaded (major %d)\n", bsg_major);
1102        return 0;
1103unregister_chrdev:
1104        unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1105destroy_bsg_class:
1106        class_destroy(bsg_class);
1107destroy_kmemcache:
1108        kmem_cache_destroy(bsg_cmd_cachep);
1109        return ret;
1110}
1111
1112MODULE_AUTHOR("Jens Axboe");
1113MODULE_DESCRIPTION(BSG_DESCRIPTION);
1114MODULE_LICENSE("GPL");
1115
1116device_initcall(bsg_init);
1117