aboutsummaryrefslogtreecommitdiff
path: root/block/bsg.c
blob: 79b42c5cafeb80e11dab48c0acdf2acb777efde9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
// SPDX-License-Identifier: GPL-2.0
/*
 * bsg.c - block layer implementation of the sg v4 interface
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/blkdev.h>
#include <linux/cdev.h>
#include <linux/jiffies.h>
#include <linux/percpu.h>
#include <linux/idr.h>
#include <linux/bsg.h>
#include <linux/slab.h>

#include <scsi/scsi.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/sg.h>

#define BSG_DESCRIPTION	"Block layer SCSI generic (bsg) driver"
#define BSG_VERSION	"0.4"

#define bsg_dbg(bd, fmt, ...) \
	pr_debug("%s: " fmt, (bd)->name, ##__VA_ARGS__)

struct bsg_device {
	struct request_queue *queue;
	spinlock_t lock;
	struct hlist_node dev_list;
	refcount_t ref_count;
	char name[20];
	int max_queue;
};

#define BSG_DEFAULT_CMDS	64
#define BSG_MAX_DEVS		32768

static DEFINE_MUTEX(bsg_mutex);
static DEFINE_IDR(bsg_minor_idr);

#define BSG_LIST_ARRAY_SIZE	8
static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];

static struct class *bsg_class;
static int bsg_major;

static inline struct hlist_head *bsg_dev_idx_hash(int index)
{
	return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
}

#define uptr64(val) ((void __user *)(uintptr_t)(val))

static int bsg_scsi_check_proto(struct sg_io_v4 *hdr)
{
	if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
	    hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
		return -EINVAL;
	return 0;
}

static int bsg_scsi_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
		fmode_t mode)
{
	struct scsi_request *sreq = scsi_req(rq);

	if (hdr->dout_xfer_len && hdr->din_xfer_len) {
		pr_warn_once("BIDI support in bsg has been removed.\n");
		return -EOPNOTSUPP;
	}

	sreq->cmd_len = hdr->request_len;
	if (sreq->cmd_len > BLK_MAX_CDB) {
		sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL);
		if (!sreq->cmd)
			return -ENOMEM;
	}

	if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len))
		return -EFAULT;
	if (blk_verify_command(sreq->cmd, mode))
		return -EPERM;
	return 0;
}

static int bsg_scsi_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
{
	struct scsi_request *sreq = scsi_req(rq);
	int ret = 0;

	/*
	 * fill in all the output members
	 */
	hdr->device_status = sreq->result & 0xff;
	hdr->transport_status = host_byte(sreq->result);
	hdr->driver_status = 0;
	if (scsi_status_is_check_condition(sreq->result))
		hdr->driver_status = DRIVER_SENSE;
	hdr->info = 0;
	if (hdr->device_status || hdr->transport_status || hdr->driver_status)
		hdr->info |= SG_INFO_CHECK;
	hdr->response_len = 0;

	if (sreq->sense_len && hdr->response) {
		int len = min_t(unsigned int, hdr->max_response_len,
					sreq->sense_len);

		if (copy_to_user(uptr64(hdr->response), sreq->sense, len))
			ret = -EFAULT;
		else
			hdr->response_len = len;
	}

	if (rq_data_dir(rq) == READ)
		hdr->din_resid = sreq->resid_len;
	else
		hdr->dout_resid = sreq->resid_len;

	return ret;
}

static void bsg_scsi_free_rq(struct request *rq)
{
	scsi_req_free_cmd(scsi_req(rq));
}

static const struct bsg_ops bsg_scsi_ops = {
	.check_proto		= bsg_scsi_check_proto,
	.fill_hdr		= bsg_scsi_fill_hdr,
	.complete_rq		= bsg_scsi_complete_rq,
	.free_rq		= bsg_scsi_free_rq,
};

static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg)
{
	struct request *rq;
	struct bio *bio;
	struct sg_io_v4 hdr;
	int ret;

	if (copy_from_user(&hdr, uarg, sizeof(hdr)))
		return -EFAULT;

	if (!q->bsg_dev.class_dev)
		return -ENXIO;

	if (hdr.guard != 'Q')
		return -EINVAL;
	ret = q->bsg_dev.ops->check_proto(&hdr);
	if (ret)
		return ret;

	rq = blk_get_request(q, hdr.dout_xfer_len ?
			REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
	if (IS_ERR(rq))
		return PTR_ERR(rq);

	ret = q->bsg_dev.ops->fill_hdr(rq, &hdr, mode);
	if (ret) {
		blk_put_request(rq);
		return ret;
	}

	rq->timeout = msecs_to_jiffies(hdr.timeout);
	if (!rq->timeout)
		rq->timeout = q->sg_timeout;
	if (!rq->timeout)
		rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
	if (rq->timeout < BLK_MIN_SG_TIMEOUT)
		rq->timeout = BLK_MIN_SG_TIMEOUT;

	if (hdr.dout_xfer_len) {
		ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.dout_xferp),
				hdr.dout_xfer_len, GFP_KERNEL);
	} else if (hdr.din_xfer_len) {
		ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.din_xferp),
				hdr.din_xfer_len, GFP_KERNEL);
	}

	if (ret)
		goto out_free_rq;

	bio = rq->bio;

	blk_execute_rq(NULL, rq, !(hdr.flags & BSG_FLAG_Q_AT_TAIL));
	ret = rq->q->bsg_dev.ops->complete_rq(rq, &hdr);
	blk_rq_unmap_user(bio);

out_free_rq:
	rq->q->bsg_dev.ops->free_rq(rq);
	blk_put_request(rq);
	if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))
		return -EFAULT;
	return ret;
}

static struct bsg_device *bsg_alloc_device(void)
{
	struct bsg_device *bd;

	bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
	if (unlikely(!bd))
		return NULL;

	spin_lock_init(&bd->lock);
	bd->max_queue = BSG_DEFAULT_CMDS;
	INIT_HLIST_NODE(&bd->dev_list);
	return bd;
}

static int bsg_put_device(struct bsg_device *bd)
{
	struct request_queue *q = bd->queue;

	mutex_lock(&bsg_mutex);

	if (!refcount_dec_and_test(&bd->ref_count)) {
		mutex_unlock(&bsg_mutex);
		return 0;
	}

	hlist_del(&bd->dev_list);
	mutex_unlock(&bsg_mutex);

	bsg_dbg(bd, "tearing down\n");

	/*
	 * close can always block
	 */
	kfree(bd);
	blk_put_queue(q);
	return 0;
}

static struct bsg_device *bsg_add_device(struct inode *inode,
					 struct request_queue *rq,
					 struct file *file)
{
	struct bsg_device *bd;
	unsigned char buf[32];

	lockdep_assert_held(&bsg_mutex);

	if (!blk_get_queue(rq))
		return ERR_PTR(-ENXIO);

	bd = bsg_alloc_device();
	if (!bd) {
		blk_put_queue(rq);
		return ERR_PTR(-ENOMEM);
	}

	bd->queue = rq;

	refcount_set(&bd->ref_count, 1);
	hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));

	strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
	bsg_dbg(bd, "bound to <%s>, max queue %d\n",
		format_dev_t(buf, inode->i_rdev), bd->max_queue);

	return bd;
}

static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
{
	struct bsg_device *bd;

	lockdep_assert_held(&bsg_mutex);

	hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
		if (bd->queue == q) {
			refcount_inc(&bd->ref_count);
			goto found;
		}
	}
	bd = NULL;
found:
	return bd;
}

static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
{
	struct bsg_device *bd;
	struct bsg_class_device *bcd;

	/*
	 * find the class device
	 */
	mutex_lock(&bsg_mutex);
	bcd = idr_find(&bsg_minor_idr, iminor(inode));

	if (!bcd) {
		bd = ERR_PTR(-ENODEV);
		goto out_unlock;
	}

	bd = __bsg_get_device(iminor(inode), bcd->queue);
	if (!bd)
		bd = bsg_add_device(inode, bcd->queue, file);

out_unlock:
	mutex_unlock(&bsg_mutex);
	return bd;
}

static int bsg_open(struct inode *inode, struct file *file)
{
	struct bsg_device *bd;

	bd = bsg_get_device(inode, file);

	if (IS_ERR(bd))
		return PTR_ERR(bd);

	file->private_data = bd;
	return 0;
}

static int bsg_release(struct inode *inode, struct file *file)
{
	struct bsg_device *bd = file->private_data;

	file->private_data = NULL;
	return bsg_put_device(bd);
}

static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)
{
	return put_user(bd->max_queue, uarg);
}

static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)
{
	int queue;

	if (get_user(queue, uarg))
		return -EFAULT;
	if (queue < 1)
		return -EINVAL;

	spin_lock_irq(&bd->lock);
	bd->max_queue = queue;
	spin_unlock_irq(&bd->lock);
	return 0;
}

static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct bsg_device *bd = file->private_data;
	void __user *uarg = (void __user *) arg;

	switch (cmd) {
	/*
	 * Our own ioctls
	 */
	case SG_GET_COMMAND_Q:
		return bsg_get_command_q(bd, uarg);
	case SG_SET_COMMAND_Q:
		return bsg_set_command_q(bd, uarg);

	/*
	 * SCSI/sg ioctls
	 */
	case SG_GET_VERSION_NUM:
	case SCSI_IOCTL_GET_IDLUN:
	case SCSI_IOCTL_GET_BUS_NUMBER:
	case SG_SET_TIMEOUT:
	case SG_GET_TIMEOUT:
	case SG_GET_RESERVED_SIZE:
	case SG_SET_RESERVED_SIZE:
	case SG_EMULATED_HOST:
		return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
	case SG_IO:
		return bsg_sg_io(bd->queue, file->f_mode, uarg);
	case SCSI_IOCTL_SEND_COMMAND:
		pr_warn_ratelimited("%s: calling unsupported SCSI_IOCTL_SEND_COMMAND\n",
				current->comm);
		return -EINVAL;
	default:
		return -ENOTTY;
	}
}

static const struct file_operations bsg_fops = {
	.open		=	bsg_open,
	.release	=	bsg_release,
	.unlocked_ioctl	=	bsg_ioctl,
	.compat_ioctl	=	compat_ptr_ioctl,
	.owner		=	THIS_MODULE,
	.llseek		=	default_llseek,
};

void bsg_unregister_queue(struct request_queue *q)
{
	struct bsg_class_device *bcd = &q->bsg_dev;

	if (!bcd->class_dev)
		return;

	mutex_lock(&bsg_mutex);
	idr_remove(&bsg_minor_idr, bcd->minor);
	if (q->kobj.sd)
		sysfs_remove_link(&q->kobj, "bsg");
	device_unregister(bcd->class_dev);
	bcd->class_dev = NULL;
	mutex_unlock(&bsg_mutex);
}
EXPORT_SYMBOL_GPL(bsg_unregister_queue);

int bsg_register_queue(struct request_queue *q, struct device *parent,
		const char *name, const struct bsg_ops *ops)
{
	struct bsg_class_device *bcd;
	dev_t dev;
	int ret;
	struct device *class_dev = NULL;

	/*
	 * we need a proper transport to send commands, not a stacked device
	 */
	if (!queue_is_mq(q))
		return 0;

	bcd = &q->bsg_dev;
	memset(bcd, 0, sizeof(*bcd));

	mutex_lock(&bsg_mutex);

	ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
	if (ret < 0) {
		if (ret == -ENOSPC) {
			printk(KERN_ERR "bsg: too many bsg devices\n");
			ret = -EINVAL;
		}
		goto unlock;
	}

	bcd->minor = ret;
	bcd->queue = q;
	bcd->ops = ops;
	dev = MKDEV(bsg_major, bcd->minor);
	class_dev = device_create(bsg_class, parent, dev, NULL, "%s", name);
	if (IS_ERR(class_dev)) {
		ret = PTR_ERR(class_dev);
		goto idr_remove;
	}
	bcd->class_dev = class_dev;

	if (q->kobj.sd) {
		ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
		if (ret)
			goto unregister_class_dev;
	}

	mutex_unlock(&bsg_mutex);
	return 0;

unregister_class_dev:
	device_unregister(class_dev);
idr_remove:
	idr_remove(&bsg_minor_idr, bcd->minor);
unlock:
	mutex_unlock(&bsg_mutex);
	return ret;
}

int bsg_scsi_register_queue(struct request_queue *q, struct device *parent)
{
	if (!blk_queue_scsi_passthrough(q)) {
		WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
		return -EINVAL;
	}

	return bsg_register_queue(q, parent, dev_name(parent), &bsg_scsi_ops);
}
EXPORT_SYMBOL_GPL(bsg_scsi_register_queue);

static struct cdev bsg_cdev;

static char *bsg_devnode(struct device *dev, umode_t *mode)
{
	return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
}

static int __init bsg_init(void)
{
	int ret, i;
	dev_t devid;

	for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
		INIT_HLIST_HEAD(&bsg_device_list[i]);

	bsg_class = class_create(THIS_MODULE, "bsg");
	if (IS_ERR(bsg_class))
		return PTR_ERR(bsg_class);
	bsg_class->devnode = bsg_devnode;

	ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
	if (ret)
		goto destroy_bsg_class;

	bsg_major = MAJOR(devid);

	cdev_init(&bsg_cdev, &bsg_fops);
	ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
	if (ret)
		goto unregister_chrdev;

	printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
	       " loaded (major %d)\n", bsg_major);
	return 0;
unregister_chrdev:
	unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
destroy_bsg_class:
	class_destroy(bsg_class);
	return ret;
}

MODULE_AUTHOR("Jens Axboe");
MODULE_DESCRIPTION(BSG_DESCRIPTION);
MODULE_LICENSE("GPL");

device_initcall(bsg_init);