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        if (hdr->dout_xfer_len > (q->max_sectors << 9) ||
 222            hdr->din_xfer_len > (q->max_sectors << 9))
 223                return -EIO;
 224
 225        switch (hdr->protocol) {
 226        case BSG_PROTOCOL_SCSI:
 227                switch (hdr->subprotocol) {
 228                case BSG_SUB_PROTOCOL_SCSI_CMD:
 229                case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
 230                        break;
 231                default:
 232                        ret = -EINVAL;
 233                }
 234                break;
 235        default:
 236                ret = -EINVAL;
 237        }
 238
 239        *rw = hdr->dout_xfer_len ? WRITE : READ;
 240        return ret;
 241}
 242
 243/*
 244 * map sg_io_v4 to a request.
 245 */
 246static struct request *
 247bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
 248            u8 *sense)
 249{
 250        struct request_queue *q = bd->queue;
 251        struct request *rq, *next_rq = NULL;
 252        int ret, rw;
 253        unsigned int dxfer_len;
 254        void *dxferp = NULL;
 255
 256        dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
 257                hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
 258                hdr->din_xfer_len);
 259
 260        ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
 261        if (ret)
 262                return ERR_PTR(ret);
 263
 264        /*
 265         * map scatter-gather elements seperately and string them to request
 266         */
 267        rq = blk_get_request(q, rw, GFP_KERNEL);
 268        if (!rq)
 269                return ERR_PTR(-ENOMEM);
 270        ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
 271        if (ret)
 272                goto out;
 273
 274        if (rw == WRITE && hdr->din_xfer_len) {
 275                if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
 276                        ret = -EOPNOTSUPP;
 277                        goto out;
 278                }
 279
 280                next_rq = blk_get_request(q, READ, GFP_KERNEL);
 281                if (!next_rq) {
 282                        ret = -ENOMEM;
 283                        goto out;
 284                }
 285                rq->next_rq = next_rq;
 286                next_rq->cmd_type = rq->cmd_type;
 287
 288                dxferp = (void*)(unsigned long)hdr->din_xferp;
 289                ret =  blk_rq_map_user(q, next_rq, NULL, dxferp,
 290                                       hdr->din_xfer_len, GFP_KERNEL);
 291                if (ret)
 292                        goto out;
 293        }
 294
 295        if (hdr->dout_xfer_len) {
 296                dxfer_len = hdr->dout_xfer_len;
 297                dxferp = (void*)(unsigned long)hdr->dout_xferp;
 298        } else if (hdr->din_xfer_len) {
 299                dxfer_len = hdr->din_xfer_len;
 300                dxferp = (void*)(unsigned long)hdr->din_xferp;
 301        } else
 302                dxfer_len = 0;
 303
 304        if (dxfer_len) {
 305                ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
 306                                      GFP_KERNEL);
 307                if (ret)
 308                        goto out;
 309        }
 310
 311        rq->sense = sense;
 312        rq->sense_len = 0;
 313
 314        return rq;
 315out:
 316        if (rq->cmd != rq->__cmd)
 317                kfree(rq->cmd);
 318        blk_put_request(rq);
 319        if (next_rq) {
 320                blk_rq_unmap_user(next_rq->bio);
 321                blk_put_request(next_rq);
 322        }
 323        return ERR_PTR(ret);
 324}
 325
 326/*
 327 * async completion call-back from the block layer, when scsi/ide/whatever
 328 * calls end_that_request_last() on a request
 329 */
 330static void bsg_rq_end_io(struct request *rq, int uptodate)
 331{
 332        struct bsg_command *bc = rq->end_io_data;
 333        struct bsg_device *bd = bc->bd;
 334        unsigned long flags;
 335
 336        dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
 337                bd->name, rq, bc, bc->bio, uptodate);
 338
 339        bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
 340
 341        spin_lock_irqsave(&bd->lock, flags);
 342        list_move_tail(&bc->list, &bd->done_list);
 343        bd->done_cmds++;
 344        spin_unlock_irqrestore(&bd->lock, flags);
 345
 346        wake_up(&bd->wq_done);
 347}
 348
 349/*
 350 * do final setup of a 'bc' and submit the matching 'rq' to the block
 351 * layer for io
 352 */
 353static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
 354                            struct bsg_command *bc, struct request *rq)
 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, 1, 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                blk_put_request(rq->next_rq);
 453        } else if (rq_data_dir(rq) == READ)
 454                hdr->din_resid = rq->data_len;
 455        else
 456                hdr->dout_resid = rq->data_len;
 457
 458        /*
 459         * If the request generated a negative error number, return it
 460         * (providing we aren't already returning an error); if it's
 461         * just a protocol response (i.e. non negative), that gets
 462         * processed above.
 463         */
 464        if (!ret && rq->errors < 0)
 465                ret = rq->errors;
 466
 467        blk_rq_unmap_user(bio);
 468        if (rq->cmd != rq->__cmd)
 469                kfree(rq->cmd);
 470        blk_put_request(rq);
 471
 472        return ret;
 473}
 474
 475static int bsg_complete_all_commands(struct bsg_device *bd)
 476{
 477        struct bsg_command *bc;
 478        int ret, tret;
 479
 480        dprintk("%s: entered\n", bd->name);
 481
 482        /*
 483         * wait for all commands to complete
 484         */
 485        ret = 0;
 486        do {
 487                ret = bsg_io_schedule(bd);
 488                /*
 489                 * look for -ENODATA specifically -- we'll sometimes get
 490                 * -ERESTARTSYS when we've taken a signal, but we can't
 491                 * return until we're done freeing the queue, so ignore
 492                 * it.  The signal will get handled when we're done freeing
 493                 * the bsg_device.
 494                 */
 495        } while (ret != -ENODATA);
 496
 497        /*
 498         * discard done commands
 499         */
 500        ret = 0;
 501        do {
 502                spin_lock_irq(&bd->lock);
 503                if (!bd->queued_cmds) {
 504                        spin_unlock_irq(&bd->lock);
 505                        break;
 506                }
 507                spin_unlock_irq(&bd->lock);
 508
 509                bc = bsg_get_done_cmd(bd);
 510                if (IS_ERR(bc))
 511                        break;
 512
 513                tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 514                                                bc->bidi_bio);
 515                if (!ret)
 516                        ret = tret;
 517
 518                bsg_free_command(bc);
 519        } while (1);
 520
 521        return ret;
 522}
 523
 524static int
 525__bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
 526           const struct iovec *iov, ssize_t *bytes_read)
 527{
 528        struct bsg_command *bc;
 529        int nr_commands, ret;
 530
 531        if (count % sizeof(struct sg_io_v4))
 532                return -EINVAL;
 533
 534        ret = 0;
 535        nr_commands = count / sizeof(struct sg_io_v4);
 536        while (nr_commands) {
 537                bc = bsg_get_done_cmd(bd);
 538                if (IS_ERR(bc)) {
 539                        ret = PTR_ERR(bc);
 540                        break;
 541                }
 542
 543                /*
 544                 * this is the only case where we need to copy data back
 545                 * after completing the request. so do that here,
 546                 * bsg_complete_work() cannot do that for us
 547                 */
 548                ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 549                                               bc->bidi_bio);
 550
 551                if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
 552                        ret = -EFAULT;
 553
 554                bsg_free_command(bc);
 555
 556                if (ret)
 557                        break;
 558
 559                buf += sizeof(struct sg_io_v4);
 560                *bytes_read += sizeof(struct sg_io_v4);
 561                nr_commands--;
 562        }
 563
 564        return ret;
 565}
 566
 567static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
 568{
 569        if (file->f_flags & O_NONBLOCK)
 570                clear_bit(BSG_F_BLOCK, &bd->flags);
 571        else
 572                set_bit(BSG_F_BLOCK, &bd->flags);
 573}
 574
 575/*
 576 * Check if the error is a "real" error that we should return.
 577 */
 578static inline int err_block_err(int ret)
 579{
 580        if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
 581                return 1;
 582
 583        return 0;
 584}
 585
 586static ssize_t
 587bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 588{
 589        struct bsg_device *bd = file->private_data;
 590        int ret;
 591        ssize_t bytes_read;
 592
 593        dprintk("%s: read %Zd bytes\n", bd->name, count);
 594
 595        bsg_set_block(bd, file);
 596
 597        bytes_read = 0;
 598        ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
 599        *ppos = bytes_read;
 600
 601        if (!bytes_read || (bytes_read && err_block_err(ret)))
 602                bytes_read = ret;
 603
 604        return bytes_read;
 605}
 606
 607static int __bsg_write(struct bsg_device *bd, const char __user *buf,
 608                       size_t count, ssize_t *bytes_written,
 609                       fmode_t has_write_perm)
 610{
 611        struct bsg_command *bc;
 612        struct request *rq;
 613        int ret, nr_commands;
 614
 615        if (count % sizeof(struct sg_io_v4))
 616                return -EINVAL;
 617
 618        nr_commands = count / sizeof(struct sg_io_v4);
 619        rq = NULL;
 620        bc = NULL;
 621        ret = 0;
 622        while (nr_commands) {
 623                struct request_queue *q = bd->queue;
 624
 625                bc = bsg_alloc_command(bd);
 626                if (IS_ERR(bc)) {
 627                        ret = PTR_ERR(bc);
 628                        bc = NULL;
 629                        break;
 630                }
 631
 632                if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
 633                        ret = -EFAULT;
 634                        break;
 635                }
 636
 637                /*
 638                 * get a request, fill in the blanks, and add to request queue
 639                 */
 640                rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
 641                if (IS_ERR(rq)) {
 642                        ret = PTR_ERR(rq);
 643                        rq = NULL;
 644                        break;
 645                }
 646
 647                bsg_add_command(bd, q, bc, rq);
 648                bc = NULL;
 649                rq = NULL;
 650                nr_commands--;
 651                buf += sizeof(struct sg_io_v4);
 652                *bytes_written += sizeof(struct sg_io_v4);
 653        }
 654
 655        if (bc)
 656                bsg_free_command(bc);
 657
 658        return ret;
 659}
 660
 661static ssize_t
 662bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 663{
 664        struct bsg_device *bd = file->private_data;
 665        ssize_t bytes_written;
 666        int ret;
 667
 668        dprintk("%s: write %Zd bytes\n", bd->name, count);
 669
 670        bsg_set_block(bd, file);
 671
 672        bytes_written = 0;
 673        ret = __bsg_write(bd, buf, count, &bytes_written,
 674                          file->f_mode & FMODE_WRITE);
 675
 676        *ppos = bytes_written;
 677
 678        /*
 679         * return bytes written on non-fatal errors
 680         */
 681        if (!bytes_written || (bytes_written && err_block_err(ret)))
 682                bytes_written = ret;
 683
 684        dprintk("%s: returning %Zd\n", bd->name, bytes_written);
 685        return bytes_written;
 686}
 687
 688static struct bsg_device *bsg_alloc_device(void)
 689{
 690        struct bsg_device *bd;
 691
 692        bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
 693        if (unlikely(!bd))
 694                return NULL;
 695
 696        spin_lock_init(&bd->lock);
 697
 698        bd->max_queue = BSG_DEFAULT_CMDS;
 699
 700        INIT_LIST_HEAD(&bd->busy_list);
 701        INIT_LIST_HEAD(&bd->done_list);
 702        INIT_HLIST_NODE(&bd->dev_list);
 703
 704        init_waitqueue_head(&bd->wq_free);
 705        init_waitqueue_head(&bd->wq_done);
 706        return bd;
 707}
 708
 709static void bsg_kref_release_function(struct kref *kref)
 710{
 711        struct bsg_class_device *bcd =
 712                container_of(kref, struct bsg_class_device, ref);
 713        struct device *parent = bcd->parent;
 714
 715        if (bcd->release)
 716                bcd->release(bcd->parent);
 717
 718        put_device(parent);
 719}
 720
 721static int bsg_put_device(struct bsg_device *bd)
 722{
 723        int ret = 0, do_free;
 724        struct request_queue *q = bd->queue;
 725
 726        mutex_lock(&bsg_mutex);
 727
 728        do_free = atomic_dec_and_test(&bd->ref_count);
 729        if (!do_free) {
 730                mutex_unlock(&bsg_mutex);
 731                goto out;
 732        }
 733
 734        hlist_del(&bd->dev_list);
 735        mutex_unlock(&bsg_mutex);
 736
 737        dprintk("%s: tearing down\n", bd->name);
 738
 739        /*
 740         * close can always block
 741         */
 742        set_bit(BSG_F_BLOCK, &bd->flags);
 743
 744        /*
 745         * correct error detection baddies here again. it's the responsibility
 746         * of the app to properly reap commands before close() if it wants
 747         * fool-proof error detection
 748         */
 749        ret = bsg_complete_all_commands(bd);
 750
 751        kfree(bd);
 752out:
 753        kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
 754        if (do_free)
 755                blk_put_queue(q);
 756        return ret;
 757}
 758
 759static struct bsg_device *bsg_add_device(struct inode *inode,
 760                                         struct request_queue *rq,
 761                                         struct file *file)
 762{
 763        struct bsg_device *bd;
 764        int ret;
 765#ifdef BSG_DEBUG
 766        unsigned char buf[32];
 767#endif
 768        ret = blk_get_queue(rq);
 769        if (ret)
 770                return ERR_PTR(-ENXIO);
 771
 772        bd = bsg_alloc_device();
 773        if (!bd) {
 774                blk_put_queue(rq);
 775                return ERR_PTR(-ENOMEM);
 776        }
 777
 778        bd->queue = rq;
 779
 780        bsg_set_block(bd, file);
 781
 782        atomic_set(&bd->ref_count, 1);
 783        mutex_lock(&bsg_mutex);
 784        hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 785
 786        strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
 787        dprintk("bound to <%s>, max queue %d\n",
 788                format_dev_t(buf, inode->i_rdev), bd->max_queue);
 789
 790        mutex_unlock(&bsg_mutex);
 791        return bd;
 792}
 793
 794static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 795{
 796        struct bsg_device *bd;
 797        struct hlist_node *entry;
 798
 799        mutex_lock(&bsg_mutex);
 800
 801        hlist_for_each_entry(bd, entry, bsg_dev_idx_hash(minor), dev_list) {
 802                if (bd->queue == q) {
 803                        atomic_inc(&bd->ref_count);
 804                        goto found;
 805                }
 806        }
 807        bd = NULL;
 808found:
 809        mutex_unlock(&bsg_mutex);
 810        return bd;
 811}
 812
 813static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 814{
 815        struct bsg_device *bd;
 816        struct bsg_class_device *bcd;
 817
 818        /*
 819         * find the class device
 820         */
 821        mutex_lock(&bsg_mutex);
 822        bcd = idr_find(&bsg_minor_idr, iminor(inode));
 823        if (bcd)
 824                kref_get(&bcd->ref);
 825        mutex_unlock(&bsg_mutex);
 826
 827        if (!bcd)
 828                return ERR_PTR(-ENODEV);
 829
 830        bd = __bsg_get_device(iminor(inode), bcd->queue);
 831        if (bd)
 832                return bd;
 833
 834        bd = bsg_add_device(inode, bcd->queue, file);
 835        if (IS_ERR(bd))
 836                kref_put(&bcd->ref, bsg_kref_release_function);
 837
 838        return bd;
 839}
 840
 841static int bsg_open(struct inode *inode, struct file *file)
 842{
 843        struct bsg_device *bd;
 844
 845        lock_kernel();
 846        bd = bsg_get_device(inode, file);
 847        unlock_kernel();
 848
 849        if (IS_ERR(bd))
 850                return PTR_ERR(bd);
 851
 852        file->private_data = bd;
 853        return 0;
 854}
 855
 856static int bsg_release(struct inode *inode, struct file *file)
 857{
 858        struct bsg_device *bd = file->private_data;
 859
 860        file->private_data = NULL;
 861        return bsg_put_device(bd);
 862}
 863
 864static unsigned int bsg_poll(struct file *file, poll_table *wait)
 865{
 866        struct bsg_device *bd = file->private_data;
 867        unsigned int mask = 0;
 868
 869        poll_wait(file, &bd->wq_done, wait);
 870        poll_wait(file, &bd->wq_free, wait);
 871
 872        spin_lock_irq(&bd->lock);
 873        if (!list_empty(&bd->done_list))
 874                mask |= POLLIN | POLLRDNORM;
 875        if (bd->queued_cmds >= bd->max_queue)
 876                mask |= POLLOUT;
 877        spin_unlock_irq(&bd->lock);
 878
 879        return mask;
 880}
 881
 882static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 883{
 884        struct bsg_device *bd = file->private_data;
 885        int __user *uarg = (int __user *) arg;
 886        int ret;
 887
 888        switch (cmd) {
 889                /*
 890                 * our own ioctls
 891                 */
 892        case SG_GET_COMMAND_Q:
 893                return put_user(bd->max_queue, uarg);
 894        case SG_SET_COMMAND_Q: {
 895                int queue;
 896
 897                if (get_user(queue, uarg))
 898                        return -EFAULT;
 899                if (queue < 1)
 900                        return -EINVAL;
 901
 902                spin_lock_irq(&bd->lock);
 903                bd->max_queue = queue;
 904                spin_unlock_irq(&bd->lock);
 905                return 0;
 906        }
 907
 908        /*
 909         * SCSI/sg ioctls
 910         */
 911        case SG_GET_VERSION_NUM:
 912        case SCSI_IOCTL_GET_IDLUN:
 913        case SCSI_IOCTL_GET_BUS_NUMBER:
 914        case SG_SET_TIMEOUT:
 915        case SG_GET_TIMEOUT:
 916        case SG_GET_RESERVED_SIZE:
 917        case SG_SET_RESERVED_SIZE:
 918        case SG_EMULATED_HOST:
 919        case SCSI_IOCTL_SEND_COMMAND: {
 920                void __user *uarg = (void __user *) arg;
 921                return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
 922        }
 923        case SG_IO: {
 924                struct request *rq;
 925                struct bio *bio, *bidi_bio = NULL;
 926                struct sg_io_v4 hdr;
 927                u8 sense[SCSI_SENSE_BUFFERSIZE];
 928
 929                if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 930                        return -EFAULT;
 931
 932                rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
 933                if (IS_ERR(rq))
 934                        return PTR_ERR(rq);
 935
 936                bio = rq->bio;
 937                if (rq->next_rq)
 938                        bidi_bio = rq->next_rq->bio;
 939                blk_execute_rq(bd->queue, NULL, rq, 0);
 940                ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
 941
 942                if (copy_to_user(uarg, &hdr, sizeof(hdr)))
 943                        return -EFAULT;
 944
 945                return ret;
 946        }
 947        /*
 948         * block device ioctls
 949         */
 950        default:
 951#if 0
 952                return ioctl_by_bdev(bd->bdev, cmd, arg);
 953#else
 954                return -ENOTTY;
 955#endif
 956        }
 957}
 958
 959static const struct file_operations bsg_fops = {
 960        .read           =       bsg_read,
 961        .write          =       bsg_write,
 962        .poll           =       bsg_poll,
 963        .open           =       bsg_open,
 964        .release        =       bsg_release,
 965        .unlocked_ioctl =       bsg_ioctl,
 966        .owner          =       THIS_MODULE,
 967};
 968
 969void bsg_unregister_queue(struct request_queue *q)
 970{
 971        struct bsg_class_device *bcd = &q->bsg_dev;
 972
 973        if (!bcd->class_dev)
 974                return;
 975
 976        mutex_lock(&bsg_mutex);
 977        idr_remove(&bsg_minor_idr, bcd->minor);
 978        sysfs_remove_link(&q->kobj, "bsg");
 979        device_unregister(bcd->class_dev);
 980        bcd->class_dev = NULL;
 981        kref_put(&bcd->ref, bsg_kref_release_function);
 982        mutex_unlock(&bsg_mutex);
 983}
 984EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 985
 986int bsg_register_queue(struct request_queue *q, struct device *parent,
 987                       const char *name, void (*release)(struct device *))
 988{
 989        struct bsg_class_device *bcd;
 990        dev_t dev;
 991        int ret, minor;
 992        struct device *class_dev = NULL;
 993        const char *devname;
 994
 995        if (name)
 996                devname = name;
 997        else
 998                devname = dev_name(parent);
 999
1000        /*
1001         * we need a proper transport to send commands, not a stacked device
1002         */
1003        if (!q->request_fn)
1004                return 0;
1005
1006        bcd = &q->bsg_dev;
1007        memset(bcd, 0, sizeof(*bcd));
1008
1009        mutex_lock(&bsg_mutex);
1010
1011        ret = idr_pre_get(&bsg_minor_idr, GFP_KERNEL);
1012        if (!ret) {
1013                ret = -ENOMEM;
1014                goto unlock;
1015        }
1016
1017        ret = idr_get_new(&bsg_minor_idr, bcd, &minor);
1018        if (ret < 0)
1019                goto unlock;
1020
1021        if (minor >= BSG_MAX_DEVS) {
1022                printk(KERN_ERR "bsg: too many bsg devices\n");
1023                ret = -EINVAL;
1024                goto remove_idr;
1025        }
1026
1027        bcd->minor = minor;
1028        bcd->queue = q;
1029        bcd->parent = get_device(parent);
1030        bcd->release = release;
1031        kref_init(&bcd->ref);
1032        dev = MKDEV(bsg_major, bcd->minor);
1033        class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1034        if (IS_ERR(class_dev)) {
1035                ret = PTR_ERR(class_dev);
1036                goto put_dev;
1037        }
1038        bcd->class_dev = class_dev;
1039
1040        if (q->kobj.sd) {
1041                ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1042                if (ret)
1043                        goto unregister_class_dev;
1044        }
1045
1046        mutex_unlock(&bsg_mutex);
1047        return 0;
1048
1049unregister_class_dev:
1050        device_unregister(class_dev);
1051put_dev:
1052        put_device(parent);
1053remove_idr:
1054        idr_remove(&bsg_minor_idr, minor);
1055unlock:
1056        mutex_unlock(&bsg_mutex);
1057        return ret;
1058}
1059EXPORT_SYMBOL_GPL(bsg_register_queue);
1060
1061static struct cdev bsg_cdev;
1062
1063static int __init bsg_init(void)
1064{
1065        int ret, i;
1066        dev_t devid;
1067
1068        bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1069                                sizeof(struct bsg_command), 0, 0, NULL);
1070        if (!bsg_cmd_cachep) {
1071                printk(KERN_ERR "bsg: failed creating slab cache\n");
1072                return -ENOMEM;
1073        }
1074
1075        for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1076                INIT_HLIST_HEAD(&bsg_device_list[i]);
1077
1078        bsg_class = class_create(THIS_MODULE, "bsg");
1079        if (IS_ERR(bsg_class)) {
1080                ret = PTR_ERR(bsg_class);
1081                goto destroy_kmemcache;
1082        }
1083
1084        ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1085        if (ret)
1086                goto destroy_bsg_class;
1087
1088        bsg_major = MAJOR(devid);
1089
1090        cdev_init(&bsg_cdev, &bsg_fops);
1091        ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1092        if (ret)
1093                goto unregister_chrdev;
1094
1095        printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1096               " loaded (major %d)\n", bsg_major);
1097        return 0;
1098unregister_chrdev:
1099        unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1100destroy_bsg_class:
1101        class_destroy(bsg_class);
1102destroy_kmemcache:
1103        kmem_cache_destroy(bsg_cmd_cachep);
1104        return ret;
1105}
1106
1107MODULE_AUTHOR("Jens Axboe");
1108MODULE_DESCRIPTION(BSG_DESCRIPTION);
1109MODULE_LICENSE("GPL");
1110
1111device_initcall(bsg_init);
1112