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mtd_blkdevs.c
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1 /*
2  * Interface to Linux block layer for MTD 'translation layers'.
3  *
4  * Copyright © 2003-2010 David Woodhouse <[email protected]>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19  *
20  */
21 
22 #include <linux/kernel.h>
23 #include <linux/slab.h>
24 #include <linux/module.h>
25 #include <linux/list.h>
26 #include <linux/fs.h>
27 #include <linux/mtd/blktrans.h>
28 #include <linux/mtd/mtd.h>
29 #include <linux/blkdev.h>
30 #include <linux/blkpg.h>
31 #include <linux/spinlock.h>
32 #include <linux/hdreg.h>
33 #include <linux/init.h>
34 #include <linux/mutex.h>
35 #include <linux/kthread.h>
36 #include <asm/uaccess.h>
37 
38 #include "mtdcore.h"
39 
40 static LIST_HEAD(blktrans_majors);
41 static DEFINE_MUTEX(blktrans_ref_mutex);
42 
43 static void blktrans_dev_release(struct kref *kref)
44 {
45  struct mtd_blktrans_dev *dev =
46  container_of(kref, struct mtd_blktrans_dev, ref);
47 
48  dev->disk->private_data = NULL;
49  blk_cleanup_queue(dev->rq);
50  put_disk(dev->disk);
51  list_del(&dev->list);
52  kfree(dev);
53 }
54 
55 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
56 {
57  struct mtd_blktrans_dev *dev;
58 
59  mutex_lock(&blktrans_ref_mutex);
60  dev = disk->private_data;
61 
62  if (!dev)
63  goto unlock;
64  kref_get(&dev->ref);
65 unlock:
66  mutex_unlock(&blktrans_ref_mutex);
67  return dev;
68 }
69 
70 static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
71 {
72  mutex_lock(&blktrans_ref_mutex);
73  kref_put(&dev->ref, blktrans_dev_release);
74  mutex_unlock(&blktrans_ref_mutex);
75 }
76 
77 
78 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
79  struct mtd_blktrans_dev *dev,
80  struct request *req)
81 {
82  unsigned long block, nsect;
83  char *buf;
84 
85  block = blk_rq_pos(req) << 9 >> tr->blkshift;
86  nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
87 
88  buf = req->buffer;
89 
90  if (req->cmd_type != REQ_TYPE_FS)
91  return -EIO;
92 
93  if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
94  get_capacity(req->rq_disk))
95  return -EIO;
96 
97  if (req->cmd_flags & REQ_DISCARD)
98  return tr->discard(dev, block, nsect);
99 
100  switch(rq_data_dir(req)) {
101  case READ:
102  for (; nsect > 0; nsect--, block++, buf += tr->blksize)
103  if (tr->readsect(dev, block, buf))
104  return -EIO;
105  rq_flush_dcache_pages(req);
106  return 0;
107  case WRITE:
108  if (!tr->writesect)
109  return -EIO;
110 
111  rq_flush_dcache_pages(req);
112  for (; nsect > 0; nsect--, block++, buf += tr->blksize)
113  if (tr->writesect(dev, block, buf))
114  return -EIO;
115  return 0;
116  default:
117  printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
118  return -EIO;
119  }
120 }
121 
123 {
124  if (kthread_should_stop())
125  return 1;
126 
127  return dev->bg_stop;
128 }
130 
131 static int mtd_blktrans_thread(void *arg)
132 {
133  struct mtd_blktrans_dev *dev = arg;
134  struct mtd_blktrans_ops *tr = dev->tr;
135  struct request_queue *rq = dev->rq;
136  struct request *req = NULL;
137  int background_done = 0;
138 
139  spin_lock_irq(rq->queue_lock);
140 
141  while (!kthread_should_stop()) {
142  int res;
143 
144  dev->bg_stop = false;
145  if (!req && !(req = blk_fetch_request(rq))) {
146  if (tr->background && !background_done) {
147  spin_unlock_irq(rq->queue_lock);
148  mutex_lock(&dev->lock);
149  tr->background(dev);
150  mutex_unlock(&dev->lock);
151  spin_lock_irq(rq->queue_lock);
152  /*
153  * Do background processing just once per idle
154  * period.
155  */
156  background_done = !dev->bg_stop;
157  continue;
158  }
160 
161  if (kthread_should_stop())
163 
164  spin_unlock_irq(rq->queue_lock);
165  schedule();
166  spin_lock_irq(rq->queue_lock);
167  continue;
168  }
169 
170  spin_unlock_irq(rq->queue_lock);
171 
172  mutex_lock(&dev->lock);
173  res = do_blktrans_request(dev->tr, dev, req);
174  mutex_unlock(&dev->lock);
175 
176  spin_lock_irq(rq->queue_lock);
177 
178  if (!__blk_end_request_cur(req, res))
179  req = NULL;
180 
181  background_done = 0;
182  }
183 
184  if (req)
185  __blk_end_request_all(req, -EIO);
186 
187  spin_unlock_irq(rq->queue_lock);
188 
189  return 0;
190 }
191 
192 static void mtd_blktrans_request(struct request_queue *rq)
193 {
194  struct mtd_blktrans_dev *dev;
195  struct request *req = NULL;
196 
197  dev = rq->queuedata;
198 
199  if (!dev)
200  while ((req = blk_fetch_request(rq)) != NULL)
202  else {
203  dev->bg_stop = true;
204  wake_up_process(dev->thread);
205  }
206 }
207 
208 static int blktrans_open(struct block_device *bdev, fmode_t mode)
209 {
210  struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
211  int ret = 0;
212 
213  if (!dev)
214  return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
215 
216  mutex_lock(&dev->lock);
217 
218  if (dev->open)
219  goto unlock;
220 
221  kref_get(&dev->ref);
222  __module_get(dev->tr->owner);
223 
224  if (!dev->mtd)
225  goto unlock;
226 
227  if (dev->tr->open) {
228  ret = dev->tr->open(dev);
229  if (ret)
230  goto error_put;
231  }
232 
233  ret = __get_mtd_device(dev->mtd);
234  if (ret)
235  goto error_release;
236  dev->file_mode = mode;
237 
238 unlock:
239  dev->open++;
240  mutex_unlock(&dev->lock);
241  blktrans_dev_put(dev);
242  return ret;
243 
244 error_release:
245  if (dev->tr->release)
246  dev->tr->release(dev);
247 error_put:
248  module_put(dev->tr->owner);
249  kref_put(&dev->ref, blktrans_dev_release);
250  mutex_unlock(&dev->lock);
251  blktrans_dev_put(dev);
252  return ret;
253 }
254 
255 static int blktrans_release(struct gendisk *disk, fmode_t mode)
256 {
257  struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
258  int ret = 0;
259 
260  if (!dev)
261  return ret;
262 
263  mutex_lock(&dev->lock);
264 
265  if (--dev->open)
266  goto unlock;
267 
268  kref_put(&dev->ref, blktrans_dev_release);
269  module_put(dev->tr->owner);
270 
271  if (dev->mtd) {
272  ret = dev->tr->release ? dev->tr->release(dev) : 0;
273  __put_mtd_device(dev->mtd);
274  }
275 unlock:
276  mutex_unlock(&dev->lock);
277  blktrans_dev_put(dev);
278  return ret;
279 }
280 
281 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
282 {
283  struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
284  int ret = -ENXIO;
285 
286  if (!dev)
287  return ret;
288 
289  mutex_lock(&dev->lock);
290 
291  if (!dev->mtd)
292  goto unlock;
293 
294  ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
295 unlock:
296  mutex_unlock(&dev->lock);
297  blktrans_dev_put(dev);
298  return ret;
299 }
300 
301 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
302  unsigned int cmd, unsigned long arg)
303 {
304  struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
305  int ret = -ENXIO;
306 
307  if (!dev)
308  return ret;
309 
310  mutex_lock(&dev->lock);
311 
312  if (!dev->mtd)
313  goto unlock;
314 
315  switch (cmd) {
316  case BLKFLSBUF:
317  ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
318  break;
319  default:
320  ret = -ENOTTY;
321  }
322 unlock:
323  mutex_unlock(&dev->lock);
324  blktrans_dev_put(dev);
325  return ret;
326 }
327 
328 static const struct block_device_operations mtd_blktrans_ops = {
329  .owner = THIS_MODULE,
330  .open = blktrans_open,
331  .release = blktrans_release,
332  .ioctl = blktrans_ioctl,
333  .getgeo = blktrans_getgeo,
334 };
335 
337 {
338  struct mtd_blktrans_ops *tr = new->tr;
339  struct mtd_blktrans_dev *d;
340  int last_devnum = -1;
341  struct gendisk *gd;
342  int ret;
343 
346  BUG();
347  }
348 
349  mutex_lock(&blktrans_ref_mutex);
350  list_for_each_entry(d, &tr->devs, list) {
351  if (new->devnum == -1) {
352  /* Use first free number */
353  if (d->devnum != last_devnum+1) {
354  /* Found a free devnum. Plug it in here */
355  new->devnum = last_devnum+1;
356  list_add_tail(&new->list, &d->list);
357  goto added;
358  }
359  } else if (d->devnum == new->devnum) {
360  /* Required number taken */
361  mutex_unlock(&blktrans_ref_mutex);
362  return -EBUSY;
363  } else if (d->devnum > new->devnum) {
364  /* Required number was free */
365  list_add_tail(&new->list, &d->list);
366  goto added;
367  }
368  last_devnum = d->devnum;
369  }
370 
371  ret = -EBUSY;
372  if (new->devnum == -1)
373  new->devnum = last_devnum+1;
374 
375  /* Check that the device and any partitions will get valid
376  * minor numbers and that the disk naming code below can cope
377  * with this number. */
378  if (new->devnum > (MINORMASK >> tr->part_bits) ||
379  (tr->part_bits && new->devnum >= 27 * 26)) {
380  mutex_unlock(&blktrans_ref_mutex);
381  goto error1;
382  }
383 
384  list_add_tail(&new->list, &tr->devs);
385  added:
386  mutex_unlock(&blktrans_ref_mutex);
387 
388  mutex_init(&new->lock);
389  kref_init(&new->ref);
390  if (!tr->writesect)
391  new->readonly = 1;
392 
393  /* Create gendisk */
394  ret = -ENOMEM;
395  gd = alloc_disk(1 << tr->part_bits);
396 
397  if (!gd)
398  goto error2;
399 
400  new->disk = gd;
401  gd->private_data = new;
402  gd->major = tr->major;
403  gd->first_minor = (new->devnum) << tr->part_bits;
404  gd->fops = &mtd_blktrans_ops;
405 
406  if (tr->part_bits)
407  if (new->devnum < 26)
408  snprintf(gd->disk_name, sizeof(gd->disk_name),
409  "%s%c", tr->name, 'a' + new->devnum);
410  else
411  snprintf(gd->disk_name, sizeof(gd->disk_name),
412  "%s%c%c", tr->name,
413  'a' - 1 + new->devnum / 26,
414  'a' + new->devnum % 26);
415  else
416  snprintf(gd->disk_name, sizeof(gd->disk_name),
417  "%s%d", tr->name, new->devnum);
418 
419  set_capacity(gd, (new->size * tr->blksize) >> 9);
420 
421  /* Create the request queue */
422  spin_lock_init(&new->queue_lock);
423  new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
424 
425  if (!new->rq)
426  goto error3;
427 
428  new->rq->queuedata = new;
430 
431  queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
432 
433  if (tr->discard) {
434  queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
435  new->rq->limits.max_discard_sectors = UINT_MAX;
436  }
437 
438  gd->queue = new->rq;
439 
440  /* Create processing thread */
441  /* TODO: workqueue ? */
442  new->thread = kthread_run(mtd_blktrans_thread, new,
443  "%s%d", tr->name, new->mtd->index);
444  if (IS_ERR(new->thread)) {
445  ret = PTR_ERR(new->thread);
446  goto error4;
447  }
448  gd->driverfs_dev = &new->mtd->dev;
449 
450  if (new->readonly)
451  set_disk_ro(gd, 1);
452 
453  add_disk(gd);
454 
455  if (new->disk_attributes) {
456  ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
457  new->disk_attributes);
458  WARN_ON(ret);
459  }
460  return 0;
461 error4:
462  blk_cleanup_queue(new->rq);
463 error3:
464  put_disk(new->disk);
465 error2:
466  list_del(&new->list);
467 error1:
468  return ret;
469 }
470 
472 {
473  unsigned long flags;
474 
477  BUG();
478  }
479 
480  if (old->disk_attributes)
481  sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
482  old->disk_attributes);
483 
484  /* Stop new requests to arrive */
485  del_gendisk(old->disk);
486 
487 
488  /* Stop the thread */
489  kthread_stop(old->thread);
490 
491  /* Kill current requests */
492  spin_lock_irqsave(&old->queue_lock, flags);
493  old->rq->queuedata = NULL;
494  blk_start_queue(old->rq);
495  spin_unlock_irqrestore(&old->queue_lock, flags);
496 
497  /* If the device is currently open, tell trans driver to close it,
498  then put mtd device, and don't touch it again */
499  mutex_lock(&old->lock);
500  if (old->open) {
501  if (old->tr->release)
502  old->tr->release(old);
503  __put_mtd_device(old->mtd);
504  }
505 
506  old->mtd = NULL;
507 
508  mutex_unlock(&old->lock);
509  blktrans_dev_put(old);
510  return 0;
511 }
512 
513 static void blktrans_notify_remove(struct mtd_info *mtd)
514 {
515  struct mtd_blktrans_ops *tr;
516  struct mtd_blktrans_dev *dev, *next;
517 
518  list_for_each_entry(tr, &blktrans_majors, list)
519  list_for_each_entry_safe(dev, next, &tr->devs, list)
520  if (dev->mtd == mtd)
521  tr->remove_dev(dev);
522 }
523 
524 static void blktrans_notify_add(struct mtd_info *mtd)
525 {
526  struct mtd_blktrans_ops *tr;
527 
528  if (mtd->type == MTD_ABSENT)
529  return;
530 
531  list_for_each_entry(tr, &blktrans_majors, list)
532  tr->add_mtd(tr, mtd);
533 }
534 
535 static struct mtd_notifier blktrans_notifier = {
536  .add = blktrans_notify_add,
537  .remove = blktrans_notify_remove,
538 };
539 
540 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
541 {
542  struct mtd_info *mtd;
543  int ret;
544 
545  /* Register the notifier if/when the first device type is
546  registered, to prevent the link/init ordering from fucking
547  us over. */
548  if (!blktrans_notifier.list.next)
549  register_mtd_user(&blktrans_notifier);
550 
551 
553 
554  ret = register_blkdev(tr->major, tr->name);
555  if (ret < 0) {
556  printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
557  tr->name, tr->major, ret);
559  return ret;
560  }
561 
562  if (ret)
563  tr->major = ret;
564 
565  tr->blkshift = ffs(tr->blksize) - 1;
566 
567  INIT_LIST_HEAD(&tr->devs);
568  list_add(&tr->list, &blktrans_majors);
569 
571  if (mtd->type != MTD_ABSENT)
572  tr->add_mtd(tr, mtd);
573 
575  return 0;
576 }
577 
578 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
579 {
580  struct mtd_blktrans_dev *dev, *next;
581 
583 
584  /* Remove it from the list of active majors */
585  list_del(&tr->list);
586 
587  list_for_each_entry_safe(dev, next, &tr->devs, list)
588  tr->remove_dev(dev);
589 
590  unregister_blkdev(tr->major, tr->name);
592 
593  BUG_ON(!list_empty(&tr->devs));
594  return 0;
595 }
596 
597 static void __exit mtd_blktrans_exit(void)
598 {
599  /* No race here -- if someone's currently in register_mtd_blktrans
600  we're screwed anyway. */
601  if (blktrans_notifier.list.next)
602  unregister_mtd_user(&blktrans_notifier);
603 }
604 
605 module_exit(mtd_blktrans_exit);
606 
611 
612 MODULE_AUTHOR("David Woodhouse <[email protected]>");
613 MODULE_LICENSE("GPL");
614 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");