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 bsg_io_schedule(struct bsg_device *bd)
140{
141	DEFINE_WAIT(wait);
142	int ret = 0;
143
144	spin_lock_irq(&bd->lock);
145
146	BUG_ON(bd->done_cmds > bd->queued_cmds);
147
148	/*
149	 * -ENOSPC or -ENODATA?  I'm going for -ENODATA, meaning "I have no
150	 * work to do", even though we return -ENOSPC after this same test
151	 * during bsg_write() -- there, it means our buffer can't have more
152	 * bsg_commands added to it, thus has no space left.
153	 */
154	if (bd->done_cmds == bd->queued_cmds) {
155		ret = -ENODATA;
156		goto unlock;
157	}
158
159	if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
160		ret = -EAGAIN;
161		goto unlock;
162	}
163
164	prepare_to_wait(&bd->wq_done, &wait, TASK_UNINTERRUPTIBLE);
165	spin_unlock_irq(&bd->lock);
166	io_schedule();
167	finish_wait(&bd->wq_done, &wait);
168
169	return ret;
170unlock:
171	spin_unlock_irq(&bd->lock);
172	return ret;
173}
174
175static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
176				struct sg_io_v4 *hdr, struct bsg_device *bd,
177				fmode_t has_write_perm)
178{
179	if (hdr->request_len > BLK_MAX_CDB) {
180		rq->cmd = kzalloc(hdr->request_len, GFP_KERNEL);
181		if (!rq->cmd)
182			return -ENOMEM;
183	}
184
185	if (copy_from_user(rq->cmd, (void __user *)(unsigned long)hdr->request,
186			   hdr->request_len))
187		return -EFAULT;
188
189	if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
190		if (blk_verify_command(rq->cmd, has_write_perm))
191			return -EPERM;
192	} else if (!capable(CAP_SYS_RAWIO))
193		return -EPERM;
194
195	/*
196	 * fill in request structure
197	 */
198	rq->cmd_len = hdr->request_len;
199
200	rq->timeout = msecs_to_jiffies(hdr->timeout);
201	if (!rq->timeout)
202		rq->timeout = q->sg_timeout;
203	if (!rq->timeout)
204		rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
205	if (rq->timeout < BLK_MIN_SG_TIMEOUT)
206		rq->timeout = BLK_MIN_SG_TIMEOUT;
207
208	return 0;
209}
210
211/*
212 * Check if sg_io_v4 from user is allowed and valid
213 */
214static int
215bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
216{
217	int ret = 0;
218
219	if (hdr->guard != 'Q')
220		return -EINVAL;
221
222	switch (hdr->protocol) {
223	case BSG_PROTOCOL_SCSI:
224		switch (hdr->subprotocol) {
225		case BSG_SUB_PROTOCOL_SCSI_CMD:
226		case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
227			break;
228		default:
229			ret = -EINVAL;
230		}
231		break;
232	default:
233		ret = -EINVAL;
234	}
235
236	*rw = hdr->dout_xfer_len ? WRITE : READ;
237	return ret;
238}
239
240/*
241 * map sg_io_v4 to a request.
242 */
243static struct request *
244bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
245	    u8 *sense)
246{
247	struct request_queue *q = bd->queue;
248	struct request *rq, *next_rq = NULL;
249	int ret, rw;
250	unsigned int dxfer_len;
251	void __user *dxferp = NULL;
252	struct bsg_class_device *bcd = &q->bsg_dev;
253
254	/* if the LLD has been removed then the bsg_unregister_queue will
255	 * eventually be called and the class_dev was freed, so we can no
256	 * longer use this request_queue. Return no such address.
257	 */
258	if (!bcd->class_dev)
259		return ERR_PTR(-ENXIO);
260
261	dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
262		hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
263		hdr->din_xfer_len);
264
265	ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
266	if (ret)
267		return ERR_PTR(ret);
268
269	/*
270	 * map scatter-gather elements separately and string them to request
271	 */
272	rq = blk_get_request(q, rw, GFP_KERNEL);
273	if (IS_ERR(rq))
274		return rq;
275	blk_rq_set_block_pc(rq);
276
277	ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
278	if (ret)
279		goto out;
280
281	if (rw == WRITE && hdr->din_xfer_len) {
282		if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
283			ret = -EOPNOTSUPP;
284			goto out;
285		}
286
287		next_rq = blk_get_request(q, READ, GFP_KERNEL);
288		if (IS_ERR(next_rq)) {
289			ret = PTR_ERR(next_rq);
290			next_rq = NULL;
291			goto out;
292		}
293		rq->next_rq = next_rq;
294		next_rq->cmd_type = rq->cmd_type;
295
296		dxferp = (void __user *)(unsigned long)hdr->din_xferp;
297		ret =  blk_rq_map_user(q, next_rq, NULL, dxferp,
298				       hdr->din_xfer_len, GFP_KERNEL);
299		if (ret)
300			goto out;
301	}
302
303	if (hdr->dout_xfer_len) {
304		dxfer_len = hdr->dout_xfer_len;
305		dxferp = (void __user *)(unsigned long)hdr->dout_xferp;
306	} else if (hdr->din_xfer_len) {
307		dxfer_len = hdr->din_xfer_len;
308		dxferp = (void __user *)(unsigned long)hdr->din_xferp;
309	} else
310		dxfer_len = 0;
311
312	if (dxfer_len) {
313		ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
314				      GFP_KERNEL);
315		if (ret)
316			goto out;
317	}
318
319	rq->sense = sense;
320	rq->sense_len = 0;
321
322	return rq;
323out:
324	if (rq->cmd != rq->__cmd)
325		kfree(rq->cmd);
326	blk_put_request(rq);
327	if (next_rq) {
328		blk_rq_unmap_user(next_rq->bio);
329		blk_put_request(next_rq);
330	}
331	return ERR_PTR(ret);
332}
333
334/*
335 * async completion call-back from the block layer, when scsi/ide/whatever
336 * calls end_that_request_last() on a request
337 */
338static void bsg_rq_end_io(struct request *rq, int uptodate)
339{
340	struct bsg_command *bc = rq->end_io_data;
341	struct bsg_device *bd = bc->bd;
342	unsigned long flags;
343
344	dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
345		bd->name, rq, bc, bc->bio, uptodate);
346
347	bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
348
349	spin_lock_irqsave(&bd->lock, flags);
350	list_move_tail(&bc->list, &bd->done_list);
351	bd->done_cmds++;
352	spin_unlock_irqrestore(&bd->lock, flags);
353
354	wake_up(&bd->wq_done);
355}
356
357/*
358 * do final setup of a 'bc' and submit the matching 'rq' to the block
359 * layer for io
360 */
361static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
362			    struct bsg_command *bc, struct request *rq)
363{
364	int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));
365
366	/*
367	 * add bc command to busy queue and submit rq for io
368	 */
369	bc->rq = rq;
370	bc->bio = rq->bio;
371	if (rq->next_rq)
372		bc->bidi_bio = rq->next_rq->bio;
373	bc->hdr.duration = jiffies;
374	spin_lock_irq(&bd->lock);
375	list_add_tail(&bc->list, &bd->busy_list);
376	spin_unlock_irq(&bd->lock);
377
378	dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
379
380	rq->end_io_data = bc;
381	blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);
382}
383
384static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
385{
386	struct bsg_command *bc = NULL;
387
388	spin_lock_irq(&bd->lock);
389	if (bd->done_cmds) {
390		bc = list_first_entry(&bd->done_list, struct bsg_command, list);
391		list_del(&bc->list);
392		bd->done_cmds--;
393	}
394	spin_unlock_irq(&bd->lock);
395
396	return bc;
397}
398
399/*
400 * Get a finished command from the done list
401 */
402static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
403{
404	struct bsg_command *bc;
405	int ret;
406
407	do {
408		bc = bsg_next_done_cmd(bd);
409		if (bc)
410			break;
411
412		if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
413			bc = ERR_PTR(-EAGAIN);
414			break;
415		}
416
417		ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
418		if (ret) {
419			bc = ERR_PTR(-ERESTARTSYS);
420			break;
421		}
422	} while (1);
423
424	dprintk("%s: returning done %p\n", bd->name, bc);
425
426	return bc;
427}
428
429static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
430				    struct bio *bio, struct bio *bidi_bio)
431{
432	int ret = 0;
433
434	dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
435	/*
436	 * fill in all the output members
437	 */
438	hdr->device_status = rq->errors & 0xff;
439	hdr->transport_status = host_byte(rq->errors);
440	hdr->driver_status = driver_byte(rq->errors);
441	hdr->info = 0;
442	if (hdr->device_status || hdr->transport_status || hdr->driver_status)
443		hdr->info |= SG_INFO_CHECK;
444	hdr->response_len = 0;
445
446	if (rq->sense_len && hdr->response) {
447		int len = min_t(unsigned int, hdr->max_response_len,
448					rq->sense_len);
449
450		ret = copy_to_user((void __user *)(unsigned long)hdr->response,
451				   rq->sense, len);
452		if (!ret)
453			hdr->response_len = len;
454		else
455			ret = -EFAULT;
456	}
457
458	if (rq->next_rq) {
459		hdr->dout_resid = rq->resid_len;
460		hdr->din_resid = rq->next_rq->resid_len;
461		blk_rq_unmap_user(bidi_bio);
462		blk_put_request(rq->next_rq);
463	} else if (rq_data_dir(rq) == READ)
464		hdr->din_resid = rq->resid_len;
465	else
466		hdr->dout_resid = rq->resid_len;
467
468	/*
469	 * If the request generated a negative error number, return it
470	 * (providing we aren't already returning an error); if it's
471	 * just a protocol response (i.e. non negative), that gets
472	 * processed above.
473	 */
474	if (!ret && rq->errors < 0)
475		ret = rq->errors;
476
477	blk_rq_unmap_user(bio);
478	if (rq->cmd != rq->__cmd)
479		kfree(rq->cmd);
480	blk_put_request(rq);
481
482	return ret;
483}
484
485static int bsg_complete_all_commands(struct bsg_device *bd)
486{
487	struct bsg_command *bc;
488	int ret, tret;
489
490	dprintk("%s: entered\n", bd->name);
491
492	/*
493	 * wait for all commands to complete
494	 */
495	ret = 0;
496	do {
497		ret = bsg_io_schedule(bd);
498		/*
499		 * look for -ENODATA specifically -- we'll sometimes get
500		 * -ERESTARTSYS when we've taken a signal, but we can't
501		 * return until we're done freeing the queue, so ignore
502		 * it.  The signal will get handled when we're done freeing
503		 * the bsg_device.
504		 */
505	} while (ret != -ENODATA);
506
507	/*
508	 * discard done commands
509	 */
510	ret = 0;
511	do {
512		spin_lock_irq(&bd->lock);
513		if (!bd->queued_cmds) {
514			spin_unlock_irq(&bd->lock);
515			break;
516		}
517		spin_unlock_irq(&bd->lock);
518
519		bc = bsg_get_done_cmd(bd);
520		if (IS_ERR(bc))
521			break;
522
523		tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
524						bc->bidi_bio);
525		if (!ret)
526			ret = tret;
527
528		bsg_free_command(bc);
529	} while (1);
530
531	return ret;
532}
533
534static int
535__bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
536	   const struct iovec *iov, ssize_t *bytes_read)
537{
538	struct bsg_command *bc;
539	int nr_commands, ret;
540
541	if (count % sizeof(struct sg_io_v4))
542		return -EINVAL;
543
544	ret = 0;
545	nr_commands = count / sizeof(struct sg_io_v4);
546	while (nr_commands) {
547		bc = bsg_get_done_cmd(bd);
548		if (IS_ERR(bc)) {
549			ret = PTR_ERR(bc);
550			break;
551		}
552
553		/*
554		 * this is the only case where we need to copy data back
555		 * after completing the request. so do that here,
556		 * bsg_complete_work() cannot do that for us
557		 */
558		ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
559					       bc->bidi_bio);
560
561		if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
562			ret = -EFAULT;
563
564		bsg_free_command(bc);
565
566		if (ret)
567			break;
568
569		buf += sizeof(struct sg_io_v4);
570		*bytes_read += sizeof(struct sg_io_v4);
571		nr_commands--;
572	}
573
574	return ret;
575}
576
577static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
578{
579	if (file->f_flags & O_NONBLOCK)
580		clear_bit(BSG_F_BLOCK, &bd->flags);
581	else
582		set_bit(BSG_F_BLOCK, &bd->flags);
583}
584
585/*
586 * Check if the error is a "real" error that we should return.
587 */
588static inline int err_block_err(int ret)
589{
590	if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
591		return 1;
592
593	return 0;
594}
595
596static ssize_t
597bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
598{
599	struct bsg_device *bd = file->private_data;
600	int ret;
601	ssize_t bytes_read;
602
603	dprintk("%s: read %Zd bytes\n", bd->name, count);
604
605	bsg_set_block(bd, file);
606
607	bytes_read = 0;
608	ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
609	*ppos = bytes_read;
610
611	if (!bytes_read || err_block_err(ret))
612		bytes_read = ret;
613
614	return bytes_read;
615}
616
617static int __bsg_write(struct bsg_device *bd, const char __user *buf,
618		       size_t count, ssize_t *bytes_written,
619		       fmode_t has_write_perm)
620{
621	struct bsg_command *bc;
622	struct request *rq;
623	int ret, nr_commands;
624
625	if (count % sizeof(struct sg_io_v4))
626		return -EINVAL;
627
628	nr_commands = count / sizeof(struct sg_io_v4);
629	rq = NULL;
630	bc = NULL;
631	ret = 0;
632	while (nr_commands) {
633		struct request_queue *q = bd->queue;
634
635		bc = bsg_alloc_command(bd);
636		if (IS_ERR(bc)) {
637			ret = PTR_ERR(bc);
638			bc = NULL;
639			break;
640		}
641
642		if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
643			ret = -EFAULT;
644			break;
645		}
646
647		/*
648		 * get a request, fill in the blanks, and add to request queue
649		 */
650		rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm, bc->sense);
651		if (IS_ERR(rq)) {
652			ret = PTR_ERR(rq);
653			rq = NULL;
654			break;
655		}
656
657		bsg_add_command(bd, q, bc, rq);
658		bc = NULL;
659		rq = NULL;
660		nr_commands--;
661		buf += sizeof(struct sg_io_v4);
662		*bytes_written += sizeof(struct sg_io_v4);
663	}
664
665	if (bc)
666		bsg_free_command(bc);
667
668	return ret;
669}
670
671static ssize_t
672bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
673{
674	struct bsg_device *bd = file->private_data;
675	ssize_t bytes_written;
676	int ret;
677
678	dprintk("%s: write %Zd bytes\n", bd->name, count);
679
680	bsg_set_block(bd, file);
681
682	bytes_written = 0;
683	ret = __bsg_write(bd, buf, count, &bytes_written,
684			  file->f_mode & FMODE_WRITE);
685
686	*ppos = bytes_written;
687
688	/*
689	 * return bytes written on non-fatal errors
690	 */
691	if (!bytes_written || err_block_err(ret))
692		bytes_written = ret;
693
694	dprintk("%s: returning %Zd\n", bd->name, bytes_written);
695	return bytes_written;
696}
697
698static struct bsg_device *bsg_alloc_device(void)
699{
700	struct bsg_device *bd;
701
702	bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
703	if (unlikely(!bd))
704		return NULL;
705
706	spin_lock_init(&bd->lock);
707
708	bd->max_queue = BSG_DEFAULT_CMDS;
709
710	INIT_LIST_HEAD(&bd->busy_list);
711	INIT_LIST_HEAD(&bd->done_list);
712	INIT_HLIST_NODE(&bd->dev_list);
713
714	init_waitqueue_head(&bd->wq_free);
715	init_waitqueue_head(&bd->wq_done);
716	return bd;
717}
718
719static void bsg_kref_release_function(struct kref *kref)
720{
721	struct bsg_class_device *bcd =
722		container_of(kref, struct bsg_class_device, ref);
723	struct device *parent = bcd->parent;
724
725	if (bcd->release)
726		bcd->release(bcd->parent);
727
728	put_device(parent);
729}
730
731static int bsg_put_device(struct bsg_device *bd)
732{
733	int ret = 0, do_free;
734	struct request_queue *q = bd->queue;
735
736	mutex_lock(&bsg_mutex);
737
738	do_free = atomic_dec_and_test(&bd->ref_count);
739	if (!do_free) {
740		mutex_unlock(&bsg_mutex);
741		goto out;
742	}
743
744	hlist_del(&bd->dev_list);
745	mutex_unlock(&bsg_mutex);
746
747	dprintk("%s: tearing down\n", bd->name);
748
749	/*
750	 * close can always block
751	 */
752	set_bit(BSG_F_BLOCK, &bd->flags);
753
754	/*
755	 * correct error detection baddies here again. it's the responsibility
756	 * of the app to properly reap commands before close() if it wants
757	 * fool-proof error detection
758	 */
759	ret = bsg_complete_all_commands(bd);
760
761	kfree(bd);
762out:
763	kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
764	if (do_free)
765		blk_put_queue(q);
766	return ret;
767}
768
769static struct bsg_device *bsg_add_device(struct inode *inode,
770					 struct request_queue *rq,
771					 struct file *file)
772{
773	struct bsg_device *bd;
774#ifdef BSG_DEBUG
775	unsigned char buf[32];
776#endif
777	if (!blk_get_queue(rq))
778		return ERR_PTR(-ENXIO);
779
780	bd = bsg_alloc_device();
781	if (!bd) {
782		blk_put_queue(rq);
783		return ERR_PTR(-ENOMEM);
784	}
785
786	bd->queue = rq;
787
788	bsg_set_block(bd, file);
789
790	atomic_set(&bd->ref_count, 1);
791	mutex_lock(&bsg_mutex);
792	hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
793
794	strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
795	dprintk("bound to <%s>, max queue %d\n",
796		format_dev_t(buf, inode->i_rdev), bd->max_queue);
797
798	mutex_unlock(&bsg_mutex);
799	return bd;
800}
801
802static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
803{
804	struct bsg_device *bd;
805
806	mutex_lock(&bsg_mutex);
807
808	hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
809		if (bd->queue == q) {
810			atomic_inc(&bd->ref_count);
811			goto found;
812		}
813	}
814	bd = NULL;
815found:
816	mutex_unlock(&bsg_mutex);
817	return bd;
818}
819
820static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
821{
822	struct bsg_device *bd;
823	struct bsg_class_device *bcd;
824
825	/*
826	 * find the class device
827	 */
828	mutex_lock(&bsg_mutex);
829	bcd = idr_find(&bsg_minor_idr, iminor(inode));
830	if (bcd)
831		kref_get(&bcd->ref);
832	mutex_unlock(&bsg_mutex);
833
834	if (!bcd)
835		return ERR_PTR(-ENODEV);
836
837	bd = __bsg_get_device(iminor(inode), bcd->queue);
838	if (bd)
839		return bd;
840
841	bd = bsg_add_device(inode, bcd->queue, file);
842	if (IS_ERR(bd))
843		kref_put(&bcd->ref, bsg_kref_release_function);
844
845	return bd;
846}
847
848static int bsg_open(struct inode *inode, struct file *file)
849{
850	struct bsg_device *bd;
851
852	bd = bsg_get_device(inode, file);
853
854	if (IS_ERR(bd))
855		return PTR_ERR(bd);
856
857	file->private_data = bd;
858	return 0;
859}
860
861static int bsg_release(struct inode *inode, struct file *file)
862{
863	struct bsg_device *bd = file->private_data;
864
865	file->private_data = NULL;
866	return bsg_put_device(bd);
867}
868
869static unsigned int bsg_poll(struct file *file, poll_table *wait)
870{
871	struct bsg_device *bd = file->private_data;
872	unsigned int mask = 0;
873
874	poll_wait(file, &bd->wq_done, wait);
875	poll_wait(file, &bd->wq_free, wait);
876
877	spin_lock_irq(&bd->lock);
878	if (!list_empty(&bd->done_list))
879		mask |= POLLIN | POLLRDNORM;
880	if (bd->queued_cmds < bd->max_queue)
881		mask |= POLLOUT;
882	spin_unlock_irq(&bd->lock);
883
884	return mask;
885}
886
887static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
888{
889	struct bsg_device *bd = file->private_data;
890	int __user *uarg = (int __user *) arg;
891	int ret;
892
893	switch (cmd) {
894		/*
895		 * our own ioctls
896		 */
897	case SG_GET_COMMAND_Q:
898		return put_user(bd->max_queue, uarg);
899	case SG_SET_COMMAND_Q: {
900		int queue;
901
902		if (get_user(queue, uarg))
903			return -EFAULT;
904		if (queue < 1)
905			return -EINVAL;
906
907		spin_lock_irq(&bd->lock);
908		bd->max_queue = queue;
909		spin_unlock_irq(&bd->lock);
910		return 0;
911	}
912
913	/*
914	 * SCSI/sg ioctls
915	 */
916	case SG_GET_VERSION_NUM:
917	case SCSI_IOCTL_GET_IDLUN:
918	case SCSI_IOCTL_GET_BUS_NUMBER:
919	case SG_SET_TIMEOUT:
920	case SG_GET_TIMEOUT:
921	case SG_GET_RESERVED_SIZE:
922	case SG_SET_RESERVED_SIZE:
923	case SG_EMULATED_HOST:
924	case SCSI_IOCTL_SEND_COMMAND: {
925		void __user *uarg = (void __user *) arg;
926		return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
927	}
928	case SG_IO: {
929		struct request *rq;
930		struct bio *bio, *bidi_bio = NULL;
931		struct sg_io_v4 hdr;
932		int at_head;
933		u8 sense[SCSI_SENSE_BUFFERSIZE];
934
935		if (copy_from_user(&hdr, uarg, sizeof(hdr)))
936			return -EFAULT;
937
938		rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE, sense);
939		if (IS_ERR(rq))
940			return PTR_ERR(rq);
941
942		bio = rq->bio;
943		if (rq->next_rq)
944			bidi_bio = rq->next_rq->bio;
945
946		at_head = (0 == (hdr.flags & BSG_FLAG_Q_AT_TAIL));
947		blk_execute_rq(bd->queue, NULL, rq, at_head);
948		ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
949
950		if (copy_to_user(uarg, &hdr, sizeof(hdr)))
951			return -EFAULT;
952
953		return ret;
954	}
955	/*
956	 * block device ioctls
957	 */
958	default:
959#if 0
960		return ioctl_by_bdev(bd->bdev, cmd, arg);
961#else
962		return -ENOTTY;
963#endif
964	}
965}
966
967static const struct file_operations bsg_fops = {
968	.read		=	bsg_read,
969	.write		=	bsg_write,
970	.poll		=	bsg_poll,
971	.open		=	bsg_open,
972	.release	=	bsg_release,
973	.unlocked_ioctl	=	bsg_ioctl,
974	.owner		=	THIS_MODULE,
975	.llseek		=	default_llseek,
976};
977
978void bsg_unregister_queue(struct request_queue *q)
979{
980	struct bsg_class_device *bcd = &q->bsg_dev;
981
982	if (!bcd->class_dev)
983		return;
984
985	mutex_lock(&bsg_mutex);
986	idr_remove(&bsg_minor_idr, bcd->minor);
987	if (q->kobj.sd)
988		sysfs_remove_link(&q->kobj, "bsg");
989	device_unregister(bcd->class_dev);
990	bcd->class_dev = NULL;
991	kref_put(&bcd->ref, bsg_kref_release_function);
992	mutex_unlock(&bsg_mutex);
993}
994EXPORT_SYMBOL_GPL(bsg_unregister_queue);
995
996int bsg_register_queue(struct request_queue *q, struct device *parent,
997		       const char *name, void (*release)(struct device *))
998{
999	struct bsg_class_device *bcd;
1000	dev_t dev;
1001	int ret;
1002	struct device *class_dev = NULL;
1003	const char *devname;
1004
1005	if (name)
1006		devname = name;
1007	else
1008		devname = dev_name(parent);
1009
1010	/*
1011	 * we need a proper transport to send commands, not a stacked device
1012	 */
1013	if (!queue_is_rq_based(q))
1014		return 0;
1015
1016	bcd = &q->bsg_dev;
1017	memset(bcd, 0, sizeof(*bcd));
1018
1019	mutex_lock(&bsg_mutex);
1020
1021	ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL);
1022	if (ret < 0) {
1023		if (ret == -ENOSPC) {
1024			printk(KERN_ERR "bsg: too many bsg devices\n");
1025			ret = -EINVAL;
1026		}
1027		goto unlock;
1028	}
1029
1030	bcd->minor = ret;
1031	bcd->queue = q;
1032	bcd->parent = get_device(parent);
1033	bcd->release = release;
1034	kref_init(&bcd->ref);
1035	dev = MKDEV(bsg_major, bcd->minor);
1036	class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1037	if (IS_ERR(class_dev)) {
1038		ret = PTR_ERR(class_dev);
1039		goto put_dev;
1040	}
1041	bcd->class_dev = class_dev;
1042
1043	if (q->kobj.sd) {
1044		ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1045		if (ret)
1046			goto unregister_class_dev;
1047	}
1048
1049	mutex_unlock(&bsg_mutex);
1050	return 0;
1051
1052unregister_class_dev:
1053	device_unregister(class_dev);
1054put_dev:
1055	put_device(parent);
1056	idr_remove(&bsg_minor_idr, bcd->minor);
1057unlock:
1058	mutex_unlock(&bsg_mutex);
1059	return ret;
1060}
1061EXPORT_SYMBOL_GPL(bsg_register_queue);
1062
1063static struct cdev bsg_cdev;
1064
1065static char *bsg_devnode(struct device *dev, umode_t *mode)
1066{
1067	return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
1068}
1069
1070static int __init bsg_init(void)
1071{
1072	int ret, i;
1073	dev_t devid;
1074
1075	bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1076				sizeof(struct bsg_command), 0, 0, NULL);
1077	if (!bsg_cmd_cachep) {
1078		printk(KERN_ERR "bsg: failed creating slab cache\n");
1079		return -ENOMEM;
1080	}
1081
1082	for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1083		INIT_HLIST_HEAD(&bsg_device_list[i]);
1084
1085	bsg_class = class_create(THIS_MODULE, "bsg");
1086	if (IS_ERR(bsg_class)) {
1087		ret = PTR_ERR(bsg_class);
1088		goto destroy_kmemcache;
1089	}
1090	bsg_class->devnode = bsg_devnode;
1091
1092	ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1093	if (ret)
1094		goto destroy_bsg_class;
1095
1096	bsg_major = MAJOR(devid);
1097
1098	cdev_init(&bsg_cdev, &bsg_fops);
1099	ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1100	if (ret)
1101		goto unregister_chrdev;
1102
1103	printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1104	       " loaded (major %d)\n", bsg_major);
1105	return 0;
1106unregister_chrdev:
1107	unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1108destroy_bsg_class:
1109	class_destroy(bsg_class);
1110destroy_kmemcache:
1111	kmem_cache_destroy(bsg_cmd_cachep);
1112	return ret;
1113}
1114
1115MODULE_AUTHOR("Jens Axboe");
1116MODULE_DESCRIPTION(BSG_DESCRIPTION);
1117MODULE_LICENSE("GPL");
1118
1119device_initcall(bsg_init);
1120