xref: /openbmc/linux/block/bsg.c (revision ebd09753) 
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 	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 (!refcount_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 	refcount_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 			refcount_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);
577