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Linux/block/bsg.c

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  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 
 35 struct 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 
 51 enum {
 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 
 66 static DEFINE_MUTEX(bsg_mutex);
 67 static DEFINE_IDR(bsg_minor_idr);
 68 
 69 #define BSG_LIST_ARRAY_SIZE     8
 70 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
 71 
 72 static struct class *bsg_class;
 73 static int bsg_major;
 74 
 75 static struct kmem_cache *bsg_cmd_cachep;
 76 
 77 /*
 78  * our internal command type
 79  */
 80 struct 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 
 91 static 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 
105 static 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;
129 out:
130         spin_unlock_irq(&bd->lock);
131         return bc;
132 }
133 
134 static inline struct hlist_head *bsg_dev_idx_hash(int index)
135 {
136         return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
137 }
138 
139 static 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  */
178 static int
179 bsg_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  */
207 static struct request *
208 bsg_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;
287 out:
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  */
302 static 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  */
325 static 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 
348 static 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  */
366 static 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 
393 static 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 
449 static 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 
473 static 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 
512 static 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 
555 static 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  */
566 static 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 
574 static ssize_t
575 bsg_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 
595 static 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 
649 static ssize_t
650 bsg_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 
676 static 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 
697 static 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 
709 static 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);
740 out:
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 
747 static 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 
780 static 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;
793 found:
794         mutex_unlock(&bsg_mutex);
795         return bd;
796 }
797 
798 static 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 
826 static 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 
839 static 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 
847 static 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 
865 static 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 
945 static 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 
956 void 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 }
972 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
973 
974 int 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 
1030 unregister_class_dev:
1031         device_unregister(class_dev);
1032 put_dev:
1033         put_device(parent);
1034         idr_remove(&bsg_minor_idr, bcd->minor);
1035 unlock:
1036         mutex_unlock(&bsg_mutex);
1037         return ret;
1038 }
1039 EXPORT_SYMBOL_GPL(bsg_register_queue);
1040 
1041 static struct cdev bsg_cdev;
1042 
1043 static char *bsg_devnode(struct device *dev, umode_t *mode)
1044 {
1045         return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));
1046 }
1047 
1048 static 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;
1084 unregister_chrdev:
1085         unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1086 destroy_bsg_class:
1087         class_destroy(bsg_class);
1088 destroy_kmemcache:
1089         kmem_cache_destroy(bsg_cmd_cachep);
1090         return ret;
1091 }
1092 
1093 MODULE_AUTHOR("Jens Axboe");
1094 MODULE_DESCRIPTION(BSG_DESCRIPTION);
1095 MODULE_LICENSE("GPL");
1096 
1097 device_initcall(bsg_init);
1098 

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