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