block/bsg.c

   1 /*
   2  * bsg.c - block layer implementation of the sg v4 interface
   3  *
   4  * Copyright (C) 2004 Jens Axboe <axboe@suse.de> SUSE Labs
   5  * Copyright (C) 2004 Peter M. Jones <pjones@redhat.com>
   6  *
   7  *  This file is subject to the terms and conditions of the GNU General Public
   8  *  License version 2.  See the file "COPYING" in the main directory of this
   9  *  archive for more details.
  10  *
  11  */
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/file.h>
  15 #include <linux/blkdev.h>
  16 #include <linux/cdev.h>
  17 #include <linux/jiffies.h>
  18 #include <linux/percpu.h>
  19 #include <linux/idr.h>
  20 #include <linux/bsg.h>
  21 #include <linux/slab.h>
  22
  23 #include <scsi/scsi.h>
  24 #include <scsi/scsi_ioctl.h>
  25 #include <scsi/scsi_cmnd.h>
  26 #include <scsi/scsi_device.h>
  27 #include <scsi/scsi_driver.h>
  28 #include <scsi/sg.h>
  29
  30 #define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
  31 #define BSG_VERSION     "0.4"
  32
  33 #define bsg_dbg(bd, fmt, ...) \
  34         pr_debug("%s: " fmt, (bd)->name, ##__VA_ARGS__)
  35
  36 struct bsg_device {
  37         struct request_queue *queue;
  38         spinlock_t lock;
  39         struct hlist_node dev_list;
  40         atomic_t ref_count;
  41         char name[20];
  42         int max_queue;
  43 };
  44
  45 #define BSG_DEFAULT_CMDS        64
  46 #define BSG_MAX_DEVS            32768
  47
  48 static DEFINE_MUTEX(bsg_mutex);
  49 static DEFINE_IDR(bsg_minor_idr);
  50
  51 #define BSG_LIST_ARRAY_SIZE     8
  52 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
  53
  54 static struct class *bsg_class;
  55 static int bsg_major;
  56
  57 static inline struct hlist_head *bsg_dev_idx_hash(int index)
  58 {
  59         return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
  60 }
  61
  62 #define uptr64(val) ((void __user *)(uintptr_t)(val))
  63
  64 static int bsg_scsi_check_proto(struct sg_io_v4 *hdr)
  65 {
  66         if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
  67             hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
  68                 return -EINVAL;
  69         return 0;
  70 }
  71
  72 static int bsg_scsi_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
  73                 fmode_t mode)
  74 {
  75         struct scsi_request *sreq = scsi_req(rq);
  76
  77         sreq->cmd_len = hdr->request_len;
  78         if (sreq->cmd_len > BLK_MAX_CDB) {
  79                 sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL);
  80                 if (!sreq->cmd)
  81                         return -ENOMEM;
  82         }
  83
  84         if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len))
  85                 return -EFAULT;
  86         if (blk_verify_command(sreq->cmd, mode))
  87                 return -EPERM;
  88         return 0;
  89 }
  90
  91 static int bsg_scsi_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
  92 {
  93         struct scsi_request *sreq = scsi_req(rq);
  94         int ret = 0;
  95
  96         /*
  97          * fill in all the output members
  98          */
  99         hdr->device_status = sreq->result & 0xff;
 100         hdr->transport_status = host_byte(sreq->result);
 101         hdr->driver_status = driver_byte(sreq->result);
 102         hdr->info = 0;
 103         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
 104                 hdr->info |= SG_INFO_CHECK;
 105         hdr->response_len = 0;
 106
 107         if (sreq->sense_len && hdr->response) {
 108                 int len = min_t(unsigned int, hdr->max_response_len,
 109                                         sreq->sense_len);
 110
 111                 if (copy_to_user(uptr64(hdr->response), sreq->sense, len))
 112                         ret = -EFAULT;
 113                 else
 114                         hdr->response_len = len;
 115         }
 116
 117         if (rq->next_rq) {
 118                 hdr->dout_resid = sreq->resid_len;
 119                 hdr->din_resid = scsi_req(rq->next_rq)->resid_len;
 120         } else if (rq_data_dir(rq) == READ) {
 121                 hdr->din_resid = sreq->resid_len;
 122         } else {
 123                 hdr->dout_resid = sreq->resid_len;
 124         }
 125
 126         return ret;
 127 }
 128
 129 static void bsg_scsi_free_rq(struct request *rq)
 130 {
 131         scsi_req_free_cmd(scsi_req(rq));
 132 }
 133
 134 static const struct bsg_ops bsg_scsi_ops = {
 135         .check_proto            = bsg_scsi_check_proto,
 136         .fill_hdr               = bsg_scsi_fill_hdr,
 137         .complete_rq            = bsg_scsi_complete_rq,
 138         .free_rq                = bsg_scsi_free_rq,
 139 };
 140
 141 static struct request *
 142 bsg_map_hdr(struct request_queue *q, struct sg_io_v4 *hdr, fmode_t mode)
 143 {
 144         struct request *rq, *next_rq = NULL;
 145         int ret;
 146
 147         if (!q->bsg_dev.class_dev)
 148                 return ERR_PTR(-ENXIO);
 149
 150         if (hdr->guard != 'Q')
 151                 return ERR_PTR(-EINVAL);
 152
 153         ret = q->bsg_dev.ops->check_proto(hdr);
 154         if (ret)
 155                 return ERR_PTR(ret);
 156
 157         rq = blk_get_request(q, hdr->dout_xfer_len ?
 158                         REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0);
 159         if (IS_ERR(rq))
 160                 return rq;
 161
 162         ret = q->bsg_dev.ops->fill_hdr(rq, hdr, mode);
 163         if (ret)
 164                 goto out;
 165
 166         rq->timeout = msecs_to_jiffies(hdr->timeout);
 167         if (!rq->timeout)
 168                 rq->timeout = q->sg_timeout;
 169         if (!rq->timeout)
 170                 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
 171         if (rq->timeout < BLK_MIN_SG_TIMEOUT)
 172                 rq->timeout = BLK_MIN_SG_TIMEOUT;
 173
 174         if (hdr->dout_xfer_len && hdr->din_xfer_len) {
 175                 if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
 176                         ret = -EOPNOTSUPP;
 177                         goto out;
 178                 }
 179
 180                 next_rq = blk_get_request(q, REQ_OP_SCSI_IN, 0);
 181                 if (IS_ERR(next_rq)) {
 182                         ret = PTR_ERR(next_rq);
 183                         goto out;
 184                 }
 185
 186                 rq->next_rq = next_rq;
 187                 ret = blk_rq_map_user(q, next_rq, NULL, uptr64(hdr->din_xferp),
 188                                        hdr->din_xfer_len, GFP_KERNEL);
 189                 if (ret)
 190                         goto out_free_nextrq;
 191         }
 192
 193         if (hdr->dout_xfer_len) {
 194                 ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr->dout_xferp),
 195                                 hdr->dout_xfer_len, GFP_KERNEL);
 196         } else if (hdr->din_xfer_len) {
 197                 ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr->din_xferp),
 198                                 hdr->din_xfer_len, GFP_KERNEL);
 199         }
 200
 201         if (ret)
 202                 goto out_unmap_nextrq;
 203         return rq;
 204
 205 out_unmap_nextrq:
 206         if (rq->next_rq)
 207                 blk_rq_unmap_user(rq->next_rq->bio);
 208 out_free_nextrq:
 209         if (rq->next_rq)
 210                 blk_put_request(rq->next_rq);
 211 out:
 212         q->bsg_dev.ops->free_rq(rq);
 213         blk_put_request(rq);
 214         return ERR_PTR(ret);
 215 }
 216
 217 static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
 218                                     struct bio *bio, struct bio *bidi_bio)
 219 {
 220         int ret;
 221
 222         ret = rq->q->bsg_dev.ops->complete_rq(rq, hdr);
 223
 224         if (rq->next_rq) {
 225                 blk_rq_unmap_user(bidi_bio);
 226                 blk_put_request(rq->next_rq);
 227         }
 228
 229         blk_rq_unmap_user(bio);
 230         rq->q->bsg_dev.ops->free_rq(rq);
 231         blk_put_request(rq);
 232         return ret;
 233 }
 234
 235 static struct bsg_device *bsg_alloc_device(void)
 236 {
 237         struct bsg_device *bd;
 238
 239         bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
 240         if (unlikely(!bd))
 241                 return NULL;
 242
 243         spin_lock_init(&bd->lock);
 244         bd->max_queue = BSG_DEFAULT_CMDS;
 245         INIT_HLIST_NODE(&bd->dev_list);
 246         return bd;
 247 }
 248
 249 static int bsg_put_device(struct bsg_device *bd)
 250 {
 251         struct request_queue *q = bd->queue;
 252
 253         mutex_lock(&bsg_mutex);
 254
 255         if (!atomic_dec_and_test(&bd->ref_count)) {
 256                 mutex_unlock(&bsg_mutex);
 257                 return 0;
 258         }
 259
 260         hlist_del(&bd->dev_list);
 261         mutex_unlock(&bsg_mutex);
 262
 263         bsg_dbg(bd, "tearing down\n");
 264
 265         /*
 266          * close can always block
 267          */
 268         kfree(bd);
 269         blk_put_queue(q);
 270         return 0;
 271 }
 272
 273 static struct bsg_device *bsg_add_device(struct inode *inode,
 274                                          struct request_queue *rq,
 275                                          struct file *file)
 276 {
 277         struct bsg_device *bd;
 278         unsigned char buf[32];
 279
 280         lockdep_assert_held(&bsg_mutex);
 281
 282         if (!blk_get_queue(rq))
 283                 return ERR_PTR(-ENXIO);
 284
 285         bd = bsg_alloc_device();
 286         if (!bd) {
 287                 blk_put_queue(rq);
 288                 return ERR_PTR(-ENOMEM);
 289         }
 290
 291         bd->queue = rq;
 292
 293         atomic_set(&bd->ref_count, 1);
 294         hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 295
 296         strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
 297         bsg_dbg(bd, "bound to <%s>, max queue %d\n",
 298                 format_dev_t(buf, inode->i_rdev), bd->max_queue);
 299
 300         return bd;
 301 }
 302
 303 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 304 {
 305         struct bsg_device *bd;
 306
 307         lockdep_assert_held(&bsg_mutex);
 308
 309         hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
 310                 if (bd->queue == q) {
 311                         atomic_inc(&bd->ref_count);
 312                         goto found;
 313                 }
 314         }
 315         bd = NULL;
 316 found:
 317         return bd;
 318 }
 319
 320 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 321 {
 322         struct bsg_device *bd;
 323         struct bsg_class_device *bcd;
 324
 325         /*
 326          * find the class device
 327          */
 328         mutex_lock(&bsg_mutex);
 329         bcd = idr_find(&bsg_minor_idr, iminor(inode));
 330
 331         if (!bcd) {
 332                 bd = ERR_PTR(-ENODEV);
 333                 goto out_unlock;
 334         }
 335
 336         bd = __bsg_get_device(iminor(inode), bcd->queue);
 337         if (!bd)
 338                 bd = bsg_add_device(inode, bcd->queue, file);
 339
 340 out_unlock:
 341         mutex_unlock(&bsg_mutex);
 342         return bd;
 343 }
 344
 345 static int bsg_open(struct inode *inode, struct file *file)
 346 {
 347         struct bsg_device *bd;
 348
 349         bd = bsg_get_device(inode, file);
 350
 351         if (IS_ERR(bd))
 352                 return PTR_ERR(bd);
 353
 354         file->private_data = bd;
 355         return 0;
 356 }
 357
 358 static int bsg_release(struct inode *inode, struct file *file)
 359 {
 360         struct bsg_device *bd = file->private_data;
 361
 362         file->private_data = NULL;
 363         return bsg_put_device(bd);
 364 }
 365
 366 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 367 {
 368         struct bsg_device *bd = file->private_data;
 369         int __user *uarg = (int __user *) arg;
 370         int ret;
 371
 372         switch (cmd) {
 373                 /*
 374                  * our own ioctls
 375                  */
 376         case SG_GET_COMMAND_Q:
 377                 return put_user(bd->max_queue, uarg);
 378         case SG_SET_COMMAND_Q: {
 379                 int queue;
 380
 381                 if (get_user(queue, uarg))
 382                         return -EFAULT;
 383                 if (queue < 1)
 384                         return -EINVAL;
 385
 386                 spin_lock_irq(&bd->lock);
 387                 bd->max_queue = queue;
 388                 spin_unlock_irq(&bd->lock);
 389                 return 0;
 390         }
 391
 392         /*
 393          * SCSI/sg ioctls
 394          */
 395         case SG_GET_VERSION_NUM:
 396         case SCSI_IOCTL_GET_IDLUN:
 397         case SCSI_IOCTL_GET_BUS_NUMBER:
 398         case SG_SET_TIMEOUT:
 399         case SG_GET_TIMEOUT:
 400         case SG_GET_RESERVED_SIZE:
 401         case SG_SET_RESERVED_SIZE:
 402         case SG_EMULATED_HOST:
 403         case SCSI_IOCTL_SEND_COMMAND: {
 404                 void __user *uarg = (void __user *) arg;
 405                 return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
 406         }
 407         case SG_IO: {
 408                 struct request *rq;
 409                 struct bio *bio, *bidi_bio = NULL;
 410                 struct sg_io_v4 hdr;
 411                 int at_head;
 412
 413                 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 414                         return -EFAULT;
 415
 416                 rq = bsg_map_hdr(bd->queue, &hdr, file->f_mode);
 417                 if (IS_ERR(rq))
 418                         return PTR_ERR(rq);
 419
 420                 bio = rq->bio;
 421                 if (rq->next_rq)
 422                         bidi_bio = rq->next_rq->bio;
 423
 424                 at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
 425                 blk_execute_rq(bd->queue, NULL, rq, at_head);
 426                 ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
 427
 428                 if (copy_to_user(uarg, &hdr, sizeof(hdr)))
 429                         return -EFAULT;
 430
 431                 return ret;
 432         }
 433         default:
 434                 return -ENOTTY;
 435         }
 436 }
 437
 438 static const struct file_operations bsg_fops = {
 439         .open           =       bsg_open,
 440         .release        =       bsg_release,
 441         .unlocked_ioctl =       bsg_ioctl,
 442         .owner          =       THIS_MODULE,
 443         .llseek         =       default_llseek,
 444 };
 445
 446 void bsg_unregister_queue(struct request_queue *q)
 447 {
 448         struct bsg_class_device *bcd = &q->bsg_dev;
 449
 450         if (!bcd->class_dev)
 451                 return;
 452
 453         mutex_lock(&bsg_mutex);
 454         idr_remove(&bsg_minor_idr, bcd->minor);
 455         if (q->kobj.sd)
 456                 sysfs_remove_link(&q->kobj, "bsg");
 457         device_unregister(bcd->class_dev);
 458         bcd->class_dev = NULL;
 459         mutex_unlock(&bsg_mutex);
 460 }
 461 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 462
 463 int bsg_register_queue(struct request_queue *q, struct device *parent,
 464                 const char *name, const struct bsg_ops *ops)
 465 {
 466         struct bsg_class_device *bcd;
 467         dev_t dev;
 468         int ret;
 469         struct device *class_dev = NULL;
 470
 471         /*
 472          * we need a proper transport to send commands, not a stacked device
 473          */
 474         if (!queue_is_rq_based(q))
 475                 return 0;
 476
 477         bcd = &q->bsg_dev;
 478         memset(bcd, 0, sizeof(*bcd));
 479
 480         mutex_lock(&bsg_mutex);
 481
 482         ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
 483         if (ret < 0) {
 484                 if (ret == -ENOSPC) {
 485                         printk(KERN_ERR "bsg: too many bsg devices\n");
 486                         ret = -EINVAL;
 487                 }
 488                 goto unlock;
 489         }
 490
 491         bcd->minor = ret;
 492         bcd->queue = q;
 493         bcd->ops = ops;
 494         dev = MKDEV(bsg_major, bcd->minor);
 495         class_dev = device_create(bsg_class, parent, dev, NULL, "%s", name);
 496         if (IS_ERR(class_dev)) {
 497                 ret = PTR_ERR(class_dev);
 498                 goto idr_remove;
 499         }
 500         bcd->class_dev = class_dev;
 501
 502         if (q->kobj.sd) {
 503                 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
 504                 if (ret)
 505                         goto unregister_class_dev;
 506         }
 507
 508         mutex_unlock(&bsg_mutex);
 509         return 0;
 510
 511 unregister_class_dev:
 512         device_unregister(class_dev);
 513 idr_remove:
 514         idr_remove(&bsg_minor_idr, bcd->minor);
 515 unlock:
 516         mutex_unlock(&bsg_mutex);
 517         return ret;
 518 }
 519
 520 int bsg_scsi_register_queue(struct request_queue *q, struct device *parent)
 521 {
 522         if (!blk_queue_scsi_passthrough(q)) {
 523                 WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
 524                 return -EINVAL;
 525         }
 526
 527         return bsg_register_queue(q, parent, dev_name(parent), &bsg_scsi_ops);
 528 }
 529 EXPORT_SYMBOL_GPL(bsg_scsi_register_queue);
 530
 531 static struct cdev bsg_cdev;
 532
 533 static char *bsg_devnode(struct device *dev, umode_t *mode)
 534 {
 535         return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
 536 }
 537
 538 static int __init bsg_init(void)
 539 {
 540         int ret, i;
 541         dev_t devid;
 542
 543         for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
 544                 INIT_HLIST_HEAD(&bsg_device_list[i]);
 545
 546         bsg_class = class_create(THIS_MODULE, "bsg");
 547         if (IS_ERR(bsg_class))
 548                 return PTR_ERR(bsg_class);
 549         bsg_class->devnode = bsg_devnode;
 550
 551         ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
 552         if (ret)
 553                 goto destroy_bsg_class;
 554
 555         bsg_major = MAJOR(devid);
 556
 557         cdev_init(&bsg_cdev, &bsg_fops);
 558         ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
 559         if (ret)
 560                 goto unregister_chrdev;
 561
 562         printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
 563                " loaded (major %d)\n", bsg_major);
 564         return 0;
 565 unregister_chrdev:
 566         unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
 567 destroy_bsg_class:
 568         class_destroy(bsg_class);
 569         return ret;
 570 }
 571
 572 MODULE_AUTHOR("Jens Axboe");
 573 MODULE_DESCRIPTION(BSG_DESCRIPTION);
 574 MODULE_LICENSE("GPL");
 575
 576 device_initcall(bsg_init);