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         refcount_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         if (hdr->dout_xfer_len && hdr->din_xfer_len) {
  78                 pr_warn_once("BIDI support in bsg has been removed.\n");
  79                 return -EOPNOTSUPP;
  80         }
  81
  82         sreq->cmd_len = hdr->request_len;
  83         if (sreq->cmd_len > BLK_MAX_CDB) {
  84                 sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL);
  85                 if (!sreq->cmd)
  86                         return -ENOMEM;
  87         }
  88
  89         if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len))
  90                 return -EFAULT;
  91         if (blk_verify_command(sreq->cmd, mode))
  92                 return -EPERM;
  93         return 0;
  94 }
  95
  96 static int bsg_scsi_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
  97 {
  98         struct scsi_request *sreq = scsi_req(rq);
  99         int ret = 0;
 100
 101         /*
 102          * fill in all the output members
 103          */
 104         hdr->device_status = sreq->result & 0xff;
 105         hdr->transport_status = host_byte(sreq->result);
 106         hdr->driver_status = driver_byte(sreq->result);
 107         hdr->info = 0;
 108         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
 109                 hdr->info |= SG_INFO_CHECK;
 110         hdr->response_len = 0;
 111
 112         if (sreq->sense_len && hdr->response) {
 113                 int len = min_t(unsigned int, hdr->max_response_len,
 114                                         sreq->sense_len);
 115
 116                 if (copy_to_user(uptr64(hdr->response), sreq->sense, len))
 117                         ret = -EFAULT;
 118                 else
 119                         hdr->response_len = len;
 120         }
 121
 122         if (rq_data_dir(rq) == READ)
 123                 hdr->din_resid = sreq->resid_len;
 124         else
 125                 hdr->dout_resid = sreq->resid_len;
 126
 127         return ret;
 128 }
 129
 130 static void bsg_scsi_free_rq(struct request *rq)
 131 {
 132         scsi_req_free_cmd(scsi_req(rq));
 133 }
 134
 135 static const struct bsg_ops bsg_scsi_ops = {
 136         .check_proto            = bsg_scsi_check_proto,
 137         .fill_hdr               = bsg_scsi_fill_hdr,
 138         .complete_rq            = bsg_scsi_complete_rq,
 139         .free_rq                = bsg_scsi_free_rq,
 140 };
 141
 142 static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg)
 143 {
 144         struct request *rq;
 145         struct bio *bio;
 146         struct sg_io_v4 hdr;
 147         int ret;
 148
 149         if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 150                 return -EFAULT;
 151
 152         if (!q->bsg_dev.class_dev)
 153                 return -ENXIO;
 154
 155         if (hdr.guard != 'Q')
 156                 return -EINVAL;
 157         ret = q->bsg_dev.ops->check_proto(&hdr);
 158         if (ret)
 159                 return ret;
 160
 161         rq = blk_get_request(q, hdr.dout_xfer_len ?
 162                         REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0);
 163         if (IS_ERR(rq))
 164                 return PTR_ERR(rq);
 165
 166         ret = q->bsg_dev.ops->fill_hdr(rq, &hdr, mode);
 167         if (ret)
 168                 return ret;
 169
 170         rq->timeout = msecs_to_jiffies(hdr.timeout);
 171         if (!rq->timeout)
 172                 rq->timeout = q->sg_timeout;
 173         if (!rq->timeout)
 174                 rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
 175         if (rq->timeout < BLK_MIN_SG_TIMEOUT)
 176                 rq->timeout = BLK_MIN_SG_TIMEOUT;
 177
 178         if (hdr.dout_xfer_len) {
 179                 ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.dout_xferp),
 180                                 hdr.dout_xfer_len, GFP_KERNEL);
 181         } else if (hdr.din_xfer_len) {
 182                 ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.din_xferp),
 183                                 hdr.din_xfer_len, GFP_KERNEL);
 184         }
 185
 186         if (ret)
 187                 goto out_free_rq;
 188
 189         bio = rq->bio;
 190
 191         blk_execute_rq(q, NULL, rq, !(hdr.flags & BSG_FLAG_Q_AT_TAIL));
 192         ret = rq->q->bsg_dev.ops->complete_rq(rq, &hdr);
 193         blk_rq_unmap_user(bio);
 194
 195 out_free_rq:
 196         rq->q->bsg_dev.ops->free_rq(rq);
 197         blk_put_request(rq);
 198         if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
 199                 return -EFAULT;
 200         return ret;
 201 }
 202
 203 static struct bsg_device *bsg_alloc_device(void)
 204 {
 205         struct bsg_device *bd;
 206
 207         bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
 208         if (unlikely(!bd))
 209                 return NULL;
 210
 211         spin_lock_init(&bd->lock);
 212         bd->max_queue = BSG_DEFAULT_CMDS;
 213         INIT_HLIST_NODE(&bd->dev_list);
 214         return bd;
 215 }
 216
 217 static int bsg_put_device(struct bsg_device *bd)
 218 {
 219         struct request_queue *q = bd->queue;
 220
 221         mutex_lock(&bsg_mutex);
 222
 223         if (!refcount_dec_and_test(&bd->ref_count)) {
 224                 mutex_unlock(&bsg_mutex);
 225                 return 0;
 226         }
 227
 228         hlist_del(&bd->dev_list);
 229         mutex_unlock(&bsg_mutex);
 230
 231         bsg_dbg(bd, "tearing down\n");
 232
 233         /*
 234          * close can always block
 235          */
 236         kfree(bd);
 237         blk_put_queue(q);
 238         return 0;
 239 }
 240
 241 static struct bsg_device *bsg_add_device(struct inode *inode,
 242                                          struct request_queue *rq,
 243                                          struct file *file)
 244 {
 245         struct bsg_device *bd;
 246         unsigned char buf[32];
 247
 248         lockdep_assert_held(&bsg_mutex);
 249
 250         if (!blk_get_queue(rq))
 251                 return ERR_PTR(-ENXIO);
 252
 253         bd = bsg_alloc_device();
 254         if (!bd) {
 255                 blk_put_queue(rq);
 256                 return ERR_PTR(-ENOMEM);
 257         }
 258
 259         bd->queue = rq;
 260
 261         refcount_set(&bd->ref_count, 1);
 262         hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 263
 264         strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
 265         bsg_dbg(bd, "bound to <%s>, max queue %d\n",
 266                 format_dev_t(buf, inode->i_rdev), bd->max_queue);
 267
 268         return bd;
 269 }
 270
 271 static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 272 {
 273         struct bsg_device *bd;
 274
 275         lockdep_assert_held(&bsg_mutex);
 276
 277         hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
 278                 if (bd->queue == q) {
 279                         refcount_inc(&bd->ref_count);
 280                         goto found;
 281                 }
 282         }
 283         bd = NULL;
 284 found:
 285         return bd;
 286 }
 287
 288 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 289 {
 290         struct bsg_device *bd;
 291         struct bsg_class_device *bcd;
 292
 293         /*
 294          * find the class device
 295          */
 296         mutex_lock(&bsg_mutex);
 297         bcd = idr_find(&bsg_minor_idr, iminor(inode));
 298
 299         if (!bcd) {
 300                 bd = ERR_PTR(-ENODEV);
 301                 goto out_unlock;
 302         }
 303
 304         bd = __bsg_get_device(iminor(inode), bcd->queue);
 305         if (!bd)
 306                 bd = bsg_add_device(inode, bcd->queue, file);
 307
 308 out_unlock:
 309         mutex_unlock(&bsg_mutex);
 310         return bd;
 311 }
 312
 313 static int bsg_open(struct inode *inode, struct file *file)
 314 {
 315         struct bsg_device *bd;
 316
 317         bd = bsg_get_device(inode, file);
 318
 319         if (IS_ERR(bd))
 320                 return PTR_ERR(bd);
 321
 322         file->private_data = bd;
 323         return 0;
 324 }
 325
 326 static int bsg_release(struct inode *inode, struct file *file)
 327 {
 328         struct bsg_device *bd = file->private_data;
 329
 330         file->private_data = NULL;
 331         return bsg_put_device(bd);
 332 }
 333
 334 static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)
 335 {
 336         return put_user(bd->max_queue, uarg);
 337 }
 338
 339 static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)
 340 {
 341         int queue;
 342
 343         if (get_user(queue, uarg))
 344                 return -EFAULT;
 345         if (queue < 1)
 346                 return -EINVAL;
 347
 348         spin_lock_irq(&bd->lock);
 349         bd->max_queue = queue;
 350         spin_unlock_irq(&bd->lock);
 351         return 0;
 352 }
 353
 354 static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 355 {
 356         struct bsg_device *bd = file->private_data;
 357         void __user *uarg = (void __user *) arg;
 358
 359         switch (cmd) {
 360         /*
 361          * Our own ioctls
 362          */
 363         case SG_GET_COMMAND_Q:
 364                 return bsg_get_command_q(bd, uarg);
 365         case SG_SET_COMMAND_Q:
 366                 return bsg_set_command_q(bd, uarg);
 367
 368         /*
 369          * SCSI/sg ioctls
 370          */
 371         case SG_GET_VERSION_NUM:
 372         case SCSI_IOCTL_GET_IDLUN:
 373         case SCSI_IOCTL_GET_BUS_NUMBER:
 374         case SG_SET_TIMEOUT:
 375         case SG_GET_TIMEOUT:
 376         case SG_GET_RESERVED_SIZE:
 377         case SG_SET_RESERVED_SIZE:
 378         case SG_EMULATED_HOST:
 379         case SCSI_IOCTL_SEND_COMMAND:
 380                 return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
 381         case SG_IO:
 382                 return bsg_sg_io(bd->queue, file->f_mode, uarg);
 383         default:
 384                 return -ENOTTY;
 385         }
 386 }
 387
 388 static const struct file_operations bsg_fops = {
 389         .open           =       bsg_open,
 390         .release        =       bsg_release,
 391         .unlocked_ioctl =       bsg_ioctl,
 392         .owner          =       THIS_MODULE,
 393         .llseek         =       default_llseek,
 394 };
 395
 396 void bsg_unregister_queue(struct request_queue *q)
 397 {
 398         struct bsg_class_device *bcd = &q->bsg_dev;
 399
 400         if (!bcd->class_dev)
 401                 return;
 402
 403         mutex_lock(&bsg_mutex);
 404         idr_remove(&bsg_minor_idr, bcd->minor);
 405         if (q->kobj.sd)
 406                 sysfs_remove_link(&q->kobj, "bsg");
 407         device_unregister(bcd->class_dev);
 408         bcd->class_dev = NULL;
 409         mutex_unlock(&bsg_mutex);
 410 }
 411 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 412
 413 int bsg_register_queue(struct request_queue *q, struct device *parent,
 414                 const char *name, const struct bsg_ops *ops)
 415 {
 416         struct bsg_class_device *bcd;
 417         dev_t dev;
 418         int ret;
 419         struct device *class_dev = NULL;
 420
 421         /*
 422          * we need a proper transport to send commands, not a stacked device
 423          */
 424         if (!queue_is_mq(q))
 425                 return 0;
 426
 427         bcd = &q->bsg_dev;
 428         memset(bcd, 0, sizeof(*bcd));
 429
 430         mutex_lock(&bsg_mutex);
 431
 432         ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
 433         if (ret < 0) {
 434                 if (ret == -ENOSPC) {
 435                         printk(KERN_ERR "bsg: too many bsg devices\n");
 436                         ret = -EINVAL;
 437                 }
 438                 goto unlock;
 439         }
 440
 441         bcd->minor = ret;
 442         bcd->queue = q;
 443         bcd->ops = ops;
 444         dev = MKDEV(bsg_major, bcd->minor);
 445         class_dev = device_create(bsg_class, parent, dev, NULL, "%s", name);
 446         if (IS_ERR(class_dev)) {
 447                 ret = PTR_ERR(class_dev);
 448                 goto idr_remove;
 449         }
 450         bcd->class_dev = class_dev;
 451
 452         if (q->kobj.sd) {
 453                 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
 454                 if (ret)
 455                         goto unregister_class_dev;
 456         }
 457
 458         mutex_unlock(&bsg_mutex);
 459         return 0;
 460
 461 unregister_class_dev:
 462         device_unregister(class_dev);
 463 idr_remove:
 464         idr_remove(&bsg_minor_idr, bcd->minor);
 465 unlock:
 466         mutex_unlock(&bsg_mutex);
 467         return ret;
 468 }
 469
 470 int bsg_scsi_register_queue(struct request_queue *q, struct device *parent)
 471 {
 472         if (!blk_queue_scsi_passthrough(q)) {
 473                 WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
 474                 return -EINVAL;
 475         }
 476
 477         return bsg_register_queue(q, parent, dev_name(parent), &bsg_scsi_ops);
 478 }
 479 EXPORT_SYMBOL_GPL(bsg_scsi_register_queue);
 480
 481 static struct cdev bsg_cdev;
 482
 483 static char *bsg_devnode(struct device *dev, umode_t *mode)
 484 {
 485         return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
 486 }
 487
 488 static int __init bsg_init(void)
 489 {
 490         int ret, i;
 491         dev_t devid;
 492
 493         for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
 494                 INIT_HLIST_HEAD(&bsg_device_list[i]);
 495
 496         bsg_class = class_create(THIS_MODULE, "bsg");
 497         if (IS_ERR(bsg_class))
 498                 return PTR_ERR(bsg_class);
 499         bsg_class->devnode = bsg_devnode;
 500
 501         ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
 502         if (ret)
 503                 goto destroy_bsg_class;
 504
 505         bsg_major = MAJOR(devid);
 506
 507         cdev_init(&bsg_cdev, &bsg_fops);
 508         ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
 509         if (ret)
 510                 goto unregister_chrdev;
 511
 512         printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
 513                " loaded (major %d)\n", bsg_major);
 514         return 0;
 515 unregister_chrdev:
 516         unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
 517 destroy_bsg_class:
 518         class_destroy(bsg_class);
 519         return ret;
 520 }
 521
 522 MODULE_AUTHOR("Jens Axboe");
 523 MODULE_DESCRIPTION(BSG_DESCRIPTION);
 524 MODULE_LICENSE("GPL");
 525
 526 device_initcall(bsg_init);