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