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/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
  35struct 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
  51enum {
  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
  66static DEFINE_MUTEX(bsg_mutex);
  67static DEFINE_IDR(bsg_minor_idr);
  68
  69#define BSG_LIST_ARRAY_SIZE     8
  70static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
  71
  72static struct class *bsg_class;
  73static int bsg_major;
  74
  75static struct kmem_cache *bsg_cmd_cachep;
  76
  77/*
  78 * our internal command type
  79 */
  80struct bsg_command {
  81        struct bsg_device *bd;
  82        struct list_head list;
  83        struct request *rq;
  84        struct bio *bio;
  85        struct bio *bidi_bio;
  86        int err;
  87        struct sg_io_v4 hdr;
  88        char sense[SCSI_SENSE_BUFFERSIZE];
  89};
  90
  91static void bsg_free_command(struct bsg_command *bc)
  92{
  93        struct bsg_device *bd = bc->bd;
  94        unsigned long flags;
  95
  96        kmem_cache_free(bsg_cmd_cachep, bc);
  97
  98        spin_lock_irqsave(&bd->lock, flags);
  99        bd->queued_cmds--;
 100        spin_unlock_irqrestore(&bd->lock, flags);
 101
 102        wake_up(&bd->wq_free);
 103}
 104
 105static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
 106{
 107        struct bsg_command *bc = ERR_PTR(-EINVAL);
 108
 109        spin_lock_irq(&bd->lock);
 110
 111        if (bd->queued_cmds >= bd->max_queue)
 112                goto out;
 113
 114        bd->queued_cmds++;
 115        spin_unlock_irq(&bd->lock);
 116
 117        bc = kmem_cache_zalloc(bsg_cmd_cachep, GFP_KERNEL);
 118        if (unlikely(!bc)) {
 119                spin_lock_irq(&bd->lock);
 120                bd->queued_cmds--;
 121                bc = ERR_PTR(-ENOMEM);
 122                goto out;
 123        }
 124
 125        bc->bd = bd;
 126        INIT_LIST_HEAD(&bc->list);
 127        dprintk("%s: returning free cmd %p\n", bd->name, bc);
 128        return bc;
 129out:
 130        spin_unlock_irq(&bd->lock);
 131        return bc;
 132}
 133
 134static inline struct hlist_head *bsg_dev_idx_hash(int index)
 135{
 136        return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
 137}
 138
 139static int bsg_io_schedule(struct bsg_device *bd)
 140{
 141        DEFINE_WAIT(wait);
 142        int ret = 0;
 143
 144        spin_lock_irq(&bd->lock);
 145
 146        BUG_ON(bd->done_cmds > bd->queued_cmds);
 147
 148        /*
 149         * -ENOSPC or -ENODATA?  I'm going for -ENODATA, meaning "I have no
 150         * work to do", even though we return -ENOSPC after this same test
 151         * during bsg_write() -- there, it means our buffer can't have more
 152         * bsg_commands added to it, thus has no space left.
 153         */
 154        if (bd->done_cmds == bd->queued_cmds) {
 155                ret = -ENODATA;
 156                goto unlock;
 157        }
 158
 159        if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
 160                ret = -EAGAIN;
 161                goto unlock;
 162        }
 163
 164        prepare_to_wait(&bd->wq_done, &wait, TASK_UNINTERRUPTIBLE);
 165        spin_unlock_irq(&bd->lock);
 166        io_schedule();
 167        finish_wait(&bd->wq_done, &wait);
 168
 169        return ret;
 170unlock:
 171        spin_unlock_irq(&bd->lock);
 172        return ret;
 173}
 174
 175static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
 176                                struct sg_io_v4 *hdr, struct bsg_device *bd,
 177                                fmode_t has_write_perm)
 178{
 179        if (hdr->request_len > BLK_MAX_CDB) {
 180                rq->cmd = kzalloc(hdr->request_len, GFP_KERNEL);
 181                if (!rq->cmd)
 182                        return -ENOMEM;
 183        }
 184
 185        if (copy_from_user(rq->cmd, (void __user *)(unsigned long)hdr->request,
 186                           hdr->request_len))
 187                return -EFAULT;
 188
 189        if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
 190                if (blk_verify_command(rq->cmd, has_write_perm))
 191                        return -EPERM;
 192        } else if (!capable(CAP_SYS_RAWIO))
 193                return -EPERM;
 194
 195        /*
 196         * fill in request structure
 197         */
 198        rq->cmd_len = hdr->request_len;
 199        rq->cmd_type = REQ_TYPE_BLOCK_PC;
 200
 201        rq->timeout = msecs_to_jiffies(hdr->timeout);
 202        if (!rq->timeout)
 203                rq->timeout = q->sg_timeout;
 204        if (!rq->timeout)
 205                rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
 206        if (rq->timeout < BLK_MIN_SG_TIMEOUT)
 207                rq->timeout = BLK_MIN_SG_TIMEOUT;
 208
 209        return 0;
 210}
 211
 212/*
 213 * Check if sg_io_v4 from user is allowed and valid
 214 */
 215static int
 216bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
 217{
 218        int ret = 0;
 219
 220        if (hdr->guard != 'Q')
 221                return -EINVAL;
 222
 223        switch (hdr->protocol) {
 224        case BSG_PROTOCOL_SCSI:
 225                switch (hdr->subprotocol) {
 226                case BSG_SUB_PROTOCOL_SCSI_CMD:
 227                case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
 228                        break;
 229                default:
 230                        ret = -EINVAL;
 231                }
 232                break;
 233        default:
 234                ret = -EINVAL;
 235        }
 236
 237        *rw = hdr->dout_xfer_len ? WRITE : READ;
 238        return ret;
 239}
 240
 241/*
 242 * map sg_io_v4 to a request.
 243 */
 244static struct request *
 245bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
 246            u8 *sense)
 247{
 248        struct request_queue *q = bd->queue;
 249        struct request *rq, *next_rq = NULL;
 250        int ret, rw;
 251        unsigned int dxfer_len;
 252        void __user *dxferp = NULL;
 253        struct bsg_class_device *bcd = &q->bsg_dev;
 254
 255        /* if the LLD has been removed then the bsg_unregister_queue will
 256         * eventually be called and the class_dev was freed, so we can no
 257         * longer use this request_queue. Return no such address.
 258         */
 259        if (!bcd->class_dev)
 260                return ERR_PTR(-ENXIO);
 261
 262        dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
 263                hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
 264                hdr->din_xfer_len);
 265
 266        ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
 267        if (ret)
 268                return ERR_PTR(ret);
 269
 270        /*
 271         * map scatter-gather elements separately and string them to request
 272         */
 273        rq = blk_get_request(q, rw, GFP_KERNEL);
 274        if (!rq)
 275                return ERR_PTR(-ENOMEM);
 276        ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
 277        if (ret)
 278                goto out;
 279
 280        if (rw == WRITE && hdr->din_xfer_len) {
 281                if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
 282                        ret = -EOPNOTSUPP;
 283                        goto out;
 284                }
 285
 286                next_rq = blk_get_request(q, READ, GFP_KERNEL);
 287                if (!next_rq) {
 288                        ret = -ENOMEM;
 289                        goto out;
 290                }
 291                rq->next_rq = next_rq;
 292                next_rq->cmd_type = rq->cmd_type;
 293
 294                dxferp = (void __user *)(unsigned long)hdr->din_xferp;
 295                ret =  blk_rq_map_user(q, next_rq, NULL, dxferp,
 296                                       hdr->din_xfer_len, GFP_KERNEL);
 297                if (ret)
 298                        goto out;
 299        }
 300
 301        if (hdr->dout_xfer_len) {
 302                dxfer_len = hdr->dout_xfer_len;
 303                dxferp = (void __user *)(unsigned long)hdr->dout_xferp;
 304        } else if (hdr->din_xfer_len) {
 305                dxfer_len = hdr->din_xfer_len;
 306                dxferp = (void __user *)(unsigned long)hdr->din_xferp;
 307        } else
 308                dxfer_len = 0;
 309
 310        if (dxfer_len) {
 311                ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
 312                                      GFP_KERNEL);
 313                if (ret)
 314                        goto out;
 315        }
 316
 317        rq->sense = sense;
 318        rq->sense_len = 0;
 319
 320        return rq;
 321out:
 322        if (rq->cmd != rq->__cmd)
 323                kfree(rq->cmd);
 324        blk_put_request(rq);
 325        if (next_rq) {
 326                blk_rq_unmap_user(next_rq->bio);
 327                blk_put_request(next_rq);
 328        }
 329        return ERR_PTR(ret);
 330}
 331
 332/*
 333 * async completion call-back from the block layer, when scsi/ide/whatever
 334 * calls end_that_request_last() on a request
 335 */
 336static void bsg_rq_end_io(struct request *rq, int uptodate)
 337{
 338        struct bsg_command *bc = rq->end_io_data;
 339        struct bsg_device *bd = bc->bd;
 340        unsigned long flags;
 341
 342        dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
 343                bd->name, rq, bc, bc->bio, uptodate);
 344
 345        bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
 346
 347        spin_lock_irqsave(&bd->lock, flags);
 348        list_move_tail(&bc->list, &bd->done_list);
 349        bd->done_cmds++;
 350        spin_unlock_irqrestore(&bd->lock, flags);
 351
 352        wake_up(&bd->wq_done);
 353}
 354
 355/*
 356 * do final setup of a 'bc' and submit the matching 'rq' to the block
 357 * layer for io
 358 */
 359static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
 360                            struct bsg_command *bc, struct request *rq)
 361{
 362        int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));
 363
 364        /*
 365         * add bc command to busy queue and submit rq for io
 366         */
 367        bc->rq = rq;
 368        bc->bio = rq->bio;
 369        if (rq->next_rq)
 370                bc->bidi_bio = rq->next_rq->bio;
 371        bc->hdr.duration = jiffies;
 372        spin_lock_irq(&bd->lock);
 373        list_add_tail(&bc->list, &bd->busy_list);
 374        spin_unlock_irq(&bd->lock);
 375
 376        dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
 377
 378        rq->end_io_data = bc;
 379        blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
 380}
 381
 382static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
 383{
 384        struct bsg_command *bc = NULL;
 385
 386        spin_lock_irq(&bd->lock);
 387        if (bd->done_cmds) {
 388                bc = list_first_entry(&bd->done_list, struct bsg_command, list);
 389                list_del(&bc->list);
 390                bd->done_cmds--;
 391        }
 392        spin_unlock_irq(&bd->lock);
 393
 394        return bc;
 395}
 396
 397/*
 398 * Get a finished command from the done list
 399 */
 400static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
 401{
 402        struct bsg_command *bc;
 403        int ret;
 404
 405        do {
 406                bc = bsg_next_done_cmd(bd);
 407                if (bc)
 408                        break;
 409
 410                if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
 411                        bc = ERR_PTR(-EAGAIN);
 412                        break;
 413                }
 414
 415                ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
 416                if (ret) {
 417                        bc = ERR_PTR(-ERESTARTSYS);
 418                        break;
 419                }
 420        } while (1);
 421
 422        dprintk("%s: returning done %p\n", bd->name, bc);
 423
 424        return bc;
 425}
 426
 427static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
 428                                    struct bio *bio, struct bio *bidi_bio)
 429{
 430        int ret = 0;
 431
 432        dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
 433        /*
 434         * fill in all the output members
 435         */
 436        hdr->device_status = rq->errors & 0xff;
 437        hdr->transport_status = host_byte(rq->errors);
 438        hdr->driver_status = driver_byte(rq->errors);
 439        hdr->info = 0;
 440        if (hdr->device_status || hdr->transport_status || hdr->driver_status)
 441                hdr->info |= SG_INFO_CHECK;
 442        hdr->response_len = 0;
 443
 444        if (rq->sense_len && hdr->response) {
 445                int len = min_t(unsigned int, hdr->max_response_len,
 446                                        rq->sense_len);
 447
 448                ret = copy_to_user((void __user *)(unsigned long)hdr->response,
 449                                   rq->sense, len);
 450                if (!ret)
 451                        hdr->response_len = len;
 452                else
 453                        ret = -EFAULT;
 454        }
 455
 456        if (rq->next_rq) {
 457                hdr->dout_resid = rq->resid_len;
 458                hdr->din_resid = rq->next_rq->resid_len;
 459                blk_rq_unmap_user(bidi_bio);
 460                blk_put_request(rq->next_rq);
 461        } else if (rq_data_dir(rq) == READ)
 462                hdr->din_resid = rq->resid_len;
 463        else
 464                hdr->dout_resid = rq->resid_len;
 465
 466        /*
 467         * If the request generated a negative error number, return it
 468         * (providing we aren't already returning an error); if it's
 469         * just a protocol response (i.e. non negative), that gets
 470         * processed above.
 471         */
 472        if (!ret && rq->errors < 0)
 473                ret = rq->errors;
 474
 475        blk_rq_unmap_user(bio);
 476        if (rq->cmd != rq->__cmd)
 477                kfree(rq->cmd);
 478        blk_put_request(rq);
 479
 480        return ret;
 481}
 482
 483static int bsg_complete_all_commands(struct bsg_device *bd)
 484{
 485        struct bsg_command *bc;
 486        int ret, tret;
 487
 488        dprintk("%s: entered\n", bd->name);
 489
 490        /*
 491         * wait for all commands to complete
 492         */
 493        ret = 0;
 494        do {
 495                ret = bsg_io_schedule(bd);
 496                /*
 497                 * look for -ENODATA specifically -- we'll sometimes get
 498                 * -ERESTARTSYS when we've taken a signal, but we can't
 499                 * return until we're done freeing the queue, so ignore
 500                 * it.  The signal will get handled when we're done freeing
 501                 * the bsg_device.
 502                 */
 503        } while (ret != -ENODATA);
 504
 505        /*
 506         * discard done commands
 507         */
 508        ret = 0;
 509        do {
 510                spin_lock_irq(&bd->lock);
 511                if (!bd->queued_cmds) {
 512                        spin_unlock_irq(&bd->lock);
 513                        break;
 514                }
 515                spin_unlock_irq(&bd->lock);
 516
 517                bc = bsg_get_done_cmd(bd);
 518                if (IS_ERR(bc))
 519                        break;
 520
 521                tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 522                                                bc->bidi_bio);
 523                if (!ret)
 524                        ret = tret;
 525
 526                bsg_free_command(bc);
 527        } while (1);
 528
 529        return ret;
 530}
 531
 532static int
 533__bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
 534           const struct iovec *iov, ssize_t *bytes_read)
 535{
 536        struct bsg_command *bc;
 537        int nr_commands, ret;
 538
 539        if (count % sizeof(struct sg_io_v4))
 540                return -EINVAL;
 541
 542        ret = 0;
 543        nr_commands = count / sizeof(struct sg_io_v4);
 544        while (nr_commands) {
 545                bc = bsg_get_done_cmd(bd);
 546                if (IS_ERR(bc)) {
 547                        ret = PTR_ERR(bc);
 548                        break;
 549                }
 550
 551                /*
 552                 * this is the only case where we need to copy data back
 553                 * after completing the request. so do that here,
 554                 * bsg_complete_work() cannot do that for us
 555                 */
 556                ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 557                                               bc->bidi_bio);
 558
 559                if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
 560                        ret = -EFAULT;
 561
 562                bsg_free_command(bc);
 563
 564                if (ret)
 565                        break;
 566
 567                buf += sizeof(struct sg_io_v4);
 568                *bytes_read += sizeof(struct sg_io_v4);
 569                nr_commands--;
 570        }
 571
 572        return ret;
 573}
 574
 575static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
 576{
 577        if (file->f_flags & O_NONBLOCK)
 578                clear_bit(BSG_F_BLOCK, &bd->flags);
 579        else
 580                set_bit(BSG_F_BLOCK, &bd->flags);
 581}
 582
 583/*
 584 * Check if the error is a "real" error that we should return.
 585 */
 586static inline int err_block_err(int ret)
 587{
 588        if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
 589                return 1;
 590
 591        return 0;
 592}
 593
 594static ssize_t
 595bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 596{
 597        struct bsg_device *bd = file->private_data;
 598        int ret;
 599        ssize_t bytes_read;
 600
 601        dprintk("%s: read %Zd bytes\n", bd->name, count);
 602
 603        bsg_set_block(bd, file);
 604
 605        bytes_read = 0;
 606        ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
 607        *ppos = bytes_read;
 608
 609        if (!bytes_read || err_block_err(ret))
 610                bytes_read = ret;
 611
 612        return bytes_read;
 613}
 614
 615static int __bsg_write(struct bsg_device *bd, const char __user *buf,
 616                       size_t count, ssize_t *bytes_written,
 617                       fmode_t has_write_perm)
 618{
 619        struct bsg_command *bc;
 620        struct request *rq;
 621        int ret, nr_commands;
 622
 623        if (count % sizeof(struct sg_io_v4))
 624                return -EINVAL;
 625
 626        nr_commands = count / sizeof(struct sg_io_v4);
 627        rq = NULL;
 628        bc = NULL;
 629        ret = 0;
 630        while (nr_commands) {
 631                struct request_queue *q = bd->queue;
 632
 633                bc = bsg_alloc_command(bd);
 634                if (IS_ERR(bc)) {
 635                        ret = PTR_ERR(bc);
 636                        bc = NULL;
 637                        break;
 638                }
 639
 640                if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
 641                        ret = -EFAULT;
 642                        break;
 643                }
 644
 645                /*
 646                 * get a request, fill in the blanks, and add to request queue
 647                 */
 648                rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
 649                if (IS_ERR(rq)) {
 650                        ret = PTR_ERR(rq);
 651                        rq = NULL;
 652                        break;
 653                }
 654
 655                bsg_add_command(bd, q, bc, rq);
 656                bc = NULL;
 657                rq = NULL;
 658                nr_commands--;
 659                buf += sizeof(struct sg_io_v4);
 660                *bytes_written += sizeof(struct sg_io_v4);
 661        }
 662
 663        if (bc)
 664                bsg_free_command(bc);
 665
 666        return ret;
 667}
 668
 669static ssize_t
 670bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 671{
 672        struct bsg_device *bd = file->private_data;
 673        ssize_t bytes_written;
 674        int ret;
 675
 676        dprintk("%s: write %Zd bytes\n", bd->name, count);
 677
 678        bsg_set_block(bd, file);
 679
 680        bytes_written = 0;
 681        ret = __bsg_write(bd, buf, count, &bytes_written,
 682                          file->f_mode & FMODE_WRITE);
 683
 684        *ppos = bytes_written;
 685
 686        /*
 687         * return bytes written on non-fatal errors
 688         */
 689        if (!bytes_written || err_block_err(ret))
 690                bytes_written = ret;
 691
 692        dprintk("%s: returning %Zd\n", bd->name, bytes_written);
 693        return bytes_written;
 694}
 695
 696static struct bsg_device *bsg_alloc_device(void)
 697{
 698        struct bsg_device *bd;
 699
 700        bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
 701        if (unlikely(!bd))
 702                return NULL;
 703
 704        spin_lock_init(&bd->lock);
 705
 706        bd->max_queue = BSG_DEFAULT_CMDS;
 707
 708        INIT_LIST_HEAD(&bd->busy_list);
 709        INIT_LIST_HEAD(&bd->done_list);
 710        INIT_HLIST_NODE(&bd->dev_list);
 711
 712        init_waitqueue_head(&bd->wq_free);
 713        init_waitqueue_head(&bd->wq_done);
 714        return bd;
 715}
 716
 717static void bsg_kref_release_function(struct kref *kref)
 718{
 719        struct bsg_class_device *bcd =
 720                container_of(kref, struct bsg_class_device, ref);
 721        struct device *parent = bcd->parent;
 722
 723        if (bcd->release)
 724                bcd->release(bcd->parent);
 725
 726        put_device(parent);
 727}
 728
 729static int bsg_put_device(struct bsg_device *bd)
 730{
 731        int ret = 0, do_free;
 732        struct request_queue *q = bd->queue;
 733
 734        mutex_lock(&bsg_mutex);
 735
 736        do_free = atomic_dec_and_test(&bd->ref_count);
 737        if (!do_free) {
 738                mutex_unlock(&bsg_mutex);
 739                goto out;
 740        }
 741
 742        hlist_del(&bd->dev_list);
 743        mutex_unlock(&bsg_mutex);
 744
 745        dprintk("%s: tearing down\n", bd->name);
 746
 747        /*
 748         * close can always block
 749         */
 750        set_bit(BSG_F_BLOCK, &bd->flags);
 751
 752        /*
 753         * correct error detection baddies here again. it's the responsibility
 754         * of the app to properly reap commands before close() if it wants
 755         * fool-proof error detection
 756         */
 757        ret = bsg_complete_all_commands(bd);
 758
 759        kfree(bd);
 760out:
 761        kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
 762        if (do_free)
 763                blk_put_queue(q);
 764        return ret;
 765}
 766
 767static struct bsg_device *bsg_add_device(struct inode *inode,
 768                                         struct request_queue *rq,
 769                                         struct file *file)
 770{
 771        struct bsg_device *bd;
 772        int ret;
 773#ifdef BSG_DEBUG
 774        unsigned char buf[32];
 775#endif
 776        ret = blk_get_queue(rq);
 777        if (ret)
 778                return ERR_PTR(-ENXIO);
 779
 780        bd = bsg_alloc_device();
 781        if (!bd) {
 782                blk_put_queue(rq);
 783                return ERR_PTR(-ENOMEM);
 784        }
 785
 786        bd->queue = rq;
 787
 788        bsg_set_block(bd, file);
 789
 790        atomic_set(&bd->ref_count, 1);
 791        mutex_lock(&bsg_mutex);
 792        hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 793
 794        strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
 795        dprintk("bound to <%s>, max queue %d\n",
 796                format_dev_t(buf, inode->i_rdev), bd->max_queue);
 797
 798        mutex_unlock(&bsg_mutex);
 799        return bd;
 800}
 801
 802static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 803{
 804        struct bsg_device *bd;
 805        struct hlist_node *entry;
 806
 807        mutex_lock(&bsg_mutex);
 808
 809        hlist_for_each_entry(bd, entry, bsg_dev_idx_hash(minor), dev_list) {
 810                if (bd->queue == q) {
 811                        atomic_inc(&bd->ref_count);
 812                        goto found;
 813                }
 814        }
 815        bd = NULL;
 816found:
 817        mutex_unlock(&bsg_mutex);
 818        return bd;
 819}
 820
 821static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 822{
 823        struct bsg_device *bd;
 824        struct bsg_class_device *bcd;
 825
 826        /*
 827         * find the class device
 828         */
 829        mutex_lock(&bsg_mutex);
 830        bcd = idr_find(&bsg_minor_idr, iminor(inode));
 831        if (bcd)
 832                kref_get(&bcd->ref);
 833        mutex_unlock(&bsg_mutex);
 834
 835        if (!bcd)
 836                return ERR_PTR(-ENODEV);
 837
 838        bd = __bsg_get_device(iminor(inode), bcd->queue);
 839        if (bd)
 840                return bd;
 841
 842        bd = bsg_add_device(inode, bcd->queue, file);
 843        if (IS_ERR(bd))
 844                kref_put(&bcd->ref, bsg_kref_release_function);
 845
 846        return bd;
 847}
 848
 849static int bsg_open(struct inode *inode, struct file *file)
 850{
 851        struct bsg_device *bd;
 852
 853        bd = bsg_get_device(inode, file);
 854
 855        if (IS_ERR(bd))
 856                return PTR_ERR(bd);
 857
 858        file->private_data = bd;
 859        return 0;
 860}
 861
 862static int bsg_release(struct inode *inode, struct file *file)
 863{
 864        struct bsg_device *bd = file->private_data;
 865
 866        file->private_data = NULL;
 867        return bsg_put_device(bd);
 868}
 869
 870static unsigned int bsg_poll(struct file *file, poll_table *wait)
 871{
 872        struct bsg_device *bd = file->private_data;
 873        unsigned int mask = 0;
 874
 875        poll_wait(file, &bd->wq_done, wait);
 876        poll_wait(file, &bd->wq_free, wait);
 877
 878        spin_lock_irq(&bd->lock);
 879        if (!list_empty(&bd->done_list))
 880                mask |= POLLIN | POLLRDNORM;
 881        if (bd->queued_cmds < bd->max_queue)
 882                mask |= POLLOUT;
 883        spin_unlock_irq(&bd->lock);
 884
 885        return mask;
 886}
 887
 888static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 889{
 890        struct bsg_device *bd = file->private_data;
 891        int __user *uarg = (int __user *) arg;
 892        int ret;
 893
 894        switch (cmd) {
 895                /*
 896                 * our own ioctls
 897                 */
 898        case SG_GET_COMMAND_Q:
 899                return put_user(bd->max_queue, uarg);
 900        case SG_SET_COMMAND_Q: {
 901                int queue;
 902
 903                if (get_user(queue, uarg))
 904                        return -EFAULT;
 905                if (queue < 1)
 906                        return -EINVAL;
 907
 908                spin_lock_irq(&bd->lock);
 909                bd->max_queue = queue;
 910                spin_unlock_irq(&bd->lock);
 911                return 0;
 912        }
 913
 914        /*
 915         * SCSI/sg ioctls
 916         */
 917        case SG_GET_VERSION_NUM:
 918        case SCSI_IOCTL_GET_IDLUN:
 919        case SCSI_IOCTL_GET_BUS_NUMBER:
 920        case SG_SET_TIMEOUT:
 921        case SG_GET_TIMEOUT:
 922        case SG_GET_RESERVED_SIZE:
 923        case SG_SET_RESERVED_SIZE:
 924        case SG_EMULATED_HOST:
 925        case SCSI_IOCTL_SEND_COMMAND: {
 926                void __user *uarg = (void __user *) arg;
 927                return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
 928        }
 929        case SG_IO: {
 930                struct request *rq;
 931                struct bio *bio, *bidi_bio = NULL;
 932                struct sg_io_v4 hdr;
 933                int at_head;
 934                u8 sense[SCSI_SENSE_BUFFERSIZE];
 935
 936                if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 937                        return -EFAULT;
 938
 939                rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
 940                if (IS_ERR(rq))
 941                        return PTR_ERR(rq);
 942
 943                bio = rq->bio;
 944                if (rq->next_rq)
 945                        bidi_bio = rq->next_rq->bio;
 946
 947                at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
 948                blk_execute_rq(bd->queue, NULL, rq, at_head);
 949                ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
 950
 951                if (copy_to_user(uarg, &hdr, sizeof(hdr)))
 952                        return -EFAULT;
 953
 954                return ret;
 955        }
 956        /*
 957         * block device ioctls
 958         */
 959        default:
 960#if 0
 961                return ioctl_by_bdev(bd->bdev, cmd, arg);
 962#else
 963                return -ENOTTY;
 964#endif
 965        }
 966}
 967
 968static const struct file_operations bsg_fops = {
 969        .read           =       bsg_read,
 970        .write          =       bsg_write,
 971        .poll           =       bsg_poll,
 972        .open           =       bsg_open,
 973        .release        =       bsg_release,
 974        .unlocked_ioctl =       bsg_ioctl,
 975        .owner          =       THIS_MODULE,
 976        .llseek         =       default_llseek,
 977};
 978
 979void bsg_unregister_queue(struct request_queue *q)
 980{
 981        struct bsg_class_device *bcd = &q->bsg_dev;
 982
 983        if (!bcd->class_dev)
 984                return;
 985
 986        mutex_lock(&bsg_mutex);
 987        idr_remove(&bsg_minor_idr, bcd->minor);
 988        sysfs_remove_link(&q->kobj, "bsg");
 989        device_unregister(bcd->class_dev);
 990        bcd->class_dev = NULL;
 991        kref_put(&bcd->ref, bsg_kref_release_function);
 992        mutex_unlock(&bsg_mutex);
 993}
 994EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 995
 996int bsg_register_queue(struct request_queue *q, struct device *parent,
 997                       const char *name, void (*release)(struct device *))
 998{
 999        struct bsg_class_device *bcd;
1000        dev_t dev;
1001        int ret, minor;
1002        struct device *class_dev = NULL;
1003        const char *devname;
1004
1005        if (name)
1006                devname = name;
1007        else
1008                devname = dev_name(parent);
1009
1010        /*
1011         * we need a proper transport to send commands, not a stacked device
1012         */
1013        if (!q->request_fn)
1014                return 0;
1015
1016        bcd = &q->bsg_dev;
1017        memset(bcd, 0, sizeof(*bcd));
1018
1019        mutex_lock(&bsg_mutex);
1020
1021        ret = idr_pre_get(&bsg_minor_idr, GFP_KERNEL);
1022        if (!ret) {
1023                ret = -ENOMEM;
1024                goto unlock;
1025        }
1026
1027        ret = idr_get_new(&bsg_minor_idr, bcd, &minor);
1028        if (ret < 0)
1029                goto unlock;
1030
1031        if (minor >= BSG_MAX_DEVS) {
1032                printk(KERN_ERR "bsg: too many bsg devices\n");
1033                ret = -EINVAL;
1034                goto remove_idr;
1035        }
1036
1037        bcd->minor = minor;
1038        bcd->queue = q;
1039        bcd->parent = get_device(parent);
1040        bcd->release = release;
1041        kref_init(&bcd->ref);
1042        dev = MKDEV(bsg_major, bcd->minor);
1043        class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1044        if (IS_ERR(class_dev)) {
1045                ret = PTR_ERR(class_dev);
1046                goto put_dev;
1047        }
1048        bcd->class_dev = class_dev;
1049
1050        if (q->kobj.sd) {
1051                ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1052                if (ret)
1053                        goto unregister_class_dev;
1054        }
1055
1056        mutex_unlock(&bsg_mutex);
1057        return 0;
1058
1059unregister_class_dev:
1060        device_unregister(class_dev);
1061put_dev:
1062        put_device(parent);
1063remove_idr:
1064        idr_remove(&bsg_minor_idr, minor);
1065unlock:
1066        mutex_unlock(&bsg_mutex);
1067        return ret;
1068}
1069EXPORT_SYMBOL_GPL(bsg_register_queue);
1070
1071static struct cdev bsg_cdev;
1072
1073static char *bsg_devnode(struct device *dev, mode_t *mode)
1074{
1075        return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
1076}
1077
1078static int __init bsg_init(void)
1079{
1080        int ret, i;
1081        dev_t devid;
1082
1083        bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1084                                sizeof(struct bsg_command), 0, 0, NULL);
1085        if (!bsg_cmd_cachep) {
1086                printk(KERN_ERR "bsg: failed creating slab cache\n");
1087                return -ENOMEM;
1088        }
1089
1090        for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1091                INIT_HLIST_HEAD(&bsg_device_list[i]);
1092
1093        bsg_class = class_create(THIS_MODULE, "bsg");
1094        if (IS_ERR(bsg_class)) {
1095                ret = PTR_ERR(bsg_class);
1096                goto destroy_kmemcache;
1097        }
1098        bsg_class->devnode = bsg_devnode;
1099
1100        ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1101        if (ret)
1102                goto destroy_bsg_class;
1103
1104        bsg_major = MAJOR(devid);
1105
1106        cdev_init(&bsg_cdev, &bsg_fops);
1107        ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1108        if (ret)
1109                goto unregister_chrdev;
1110
1111        printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1112               " loaded (major %d)\n", bsg_major);
1113        return 0;
1114unregister_chrdev:
1115        unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1116destroy_bsg_class:
1117        class_destroy(bsg_class);
1118destroy_kmemcache:
1119        kmem_cache_destroy(bsg_cmd_cachep);
1120        return ret;
1121}
1122
1123MODULE_AUTHOR("Jens Axboe");
1124MODULE_DESCRIPTION(BSG_DESCRIPTION);
1125MODULE_LICENSE("GPL");
1126
1127device_initcall(bsg_init);
1128
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