mtd: mtd_blkdevs: don't increase 'open' count on error path
[pandora-kernel.git] / drivers / mtd / mtd_blkdevs.c
1 /*
2  * Interface to Linux block layer for MTD 'translation layers'.
3  *
4  * Copyright © 2003-2010 David Woodhouse <dwmw2@infradead.org>
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
122 int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
123 {
124         if (kthread_should_stop())
125                 return 1;
126
127         return dev->bg_stop;
128 }
129 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
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                         }
159                         set_current_state(TASK_INTERRUPTIBLE);
160
161                         if (kthread_should_stop())
162                                 set_current_state(TASK_RUNNING);
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)
201                         __blk_end_request_all(req, -ENODEV);
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
237 unlock:
238         dev->open++;
239         mutex_unlock(&dev->lock);
240         blktrans_dev_put(dev);
241         return ret;
242
243 error_release:
244         if (dev->tr->release)
245                 dev->tr->release(dev);
246 error_put:
247         module_put(dev->tr->owner);
248         kref_put(&dev->ref, blktrans_dev_release);
249         mutex_unlock(&dev->lock);
250         blktrans_dev_put(dev);
251         return ret;
252 }
253
254 static int blktrans_release(struct gendisk *disk, fmode_t mode)
255 {
256         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
257         int ret = 0;
258
259         if (!dev)
260                 return ret;
261
262         mutex_lock(&dev->lock);
263
264         if (--dev->open)
265                 goto unlock;
266
267         kref_put(&dev->ref, blktrans_dev_release);
268         module_put(dev->tr->owner);
269
270         if (dev->mtd) {
271                 ret = dev->tr->release ? dev->tr->release(dev) : 0;
272                 __put_mtd_device(dev->mtd);
273         }
274 unlock:
275         mutex_unlock(&dev->lock);
276         blktrans_dev_put(dev);
277         return ret;
278 }
279
280 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
281 {
282         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
283         int ret = -ENXIO;
284
285         if (!dev)
286                 return ret;
287
288         mutex_lock(&dev->lock);
289
290         if (!dev->mtd)
291                 goto unlock;
292
293         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
294 unlock:
295         mutex_unlock(&dev->lock);
296         blktrans_dev_put(dev);
297         return ret;
298 }
299
300 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
301                               unsigned int cmd, unsigned long arg)
302 {
303         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
304         int ret = -ENXIO;
305
306         if (!dev)
307                 return ret;
308
309         mutex_lock(&dev->lock);
310
311         if (!dev->mtd)
312                 goto unlock;
313
314         switch (cmd) {
315         case BLKFLSBUF:
316                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
317                 break;
318         default:
319                 ret = -ENOTTY;
320         }
321 unlock:
322         mutex_unlock(&dev->lock);
323         blktrans_dev_put(dev);
324         return ret;
325 }
326
327 static const struct block_device_operations mtd_blktrans_ops = {
328         .owner          = THIS_MODULE,
329         .open           = blktrans_open,
330         .release        = blktrans_release,
331         .ioctl          = blktrans_ioctl,
332         .getgeo         = blktrans_getgeo,
333 };
334
335 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
336 {
337         struct mtd_blktrans_ops *tr = new->tr;
338         struct mtd_blktrans_dev *d;
339         int last_devnum = -1;
340         struct gendisk *gd;
341         int ret;
342
343         if (mutex_trylock(&mtd_table_mutex)) {
344                 mutex_unlock(&mtd_table_mutex);
345                 BUG();
346         }
347
348         mutex_lock(&blktrans_ref_mutex);
349         list_for_each_entry(d, &tr->devs, list) {
350                 if (new->devnum == -1) {
351                         /* Use first free number */
352                         if (d->devnum != last_devnum+1) {
353                                 /* Found a free devnum. Plug it in here */
354                                 new->devnum = last_devnum+1;
355                                 list_add_tail(&new->list, &d->list);
356                                 goto added;
357                         }
358                 } else if (d->devnum == new->devnum) {
359                         /* Required number taken */
360                         mutex_unlock(&blktrans_ref_mutex);
361                         return -EBUSY;
362                 } else if (d->devnum > new->devnum) {
363                         /* Required number was free */
364                         list_add_tail(&new->list, &d->list);
365                         goto added;
366                 }
367                 last_devnum = d->devnum;
368         }
369
370         ret = -EBUSY;
371         if (new->devnum == -1)
372                 new->devnum = last_devnum+1;
373
374         /* Check that the device and any partitions will get valid
375          * minor numbers and that the disk naming code below can cope
376          * with this number. */
377         if (new->devnum > (MINORMASK >> tr->part_bits) ||
378             (tr->part_bits && new->devnum >= 27 * 26)) {
379                 mutex_unlock(&blktrans_ref_mutex);
380                 goto error1;
381         }
382
383         list_add_tail(&new->list, &tr->devs);
384  added:
385         mutex_unlock(&blktrans_ref_mutex);
386
387         mutex_init(&new->lock);
388         kref_init(&new->ref);
389         if (!tr->writesect)
390                 new->readonly = 1;
391
392         /* Create gendisk */
393         ret = -ENOMEM;
394         gd = alloc_disk(1 << tr->part_bits);
395
396         if (!gd)
397                 goto error2;
398
399         new->disk = gd;
400         gd->private_data = new;
401         gd->major = tr->major;
402         gd->first_minor = (new->devnum) << tr->part_bits;
403         gd->fops = &mtd_blktrans_ops;
404
405         if (tr->part_bits)
406                 if (new->devnum < 26)
407                         snprintf(gd->disk_name, sizeof(gd->disk_name),
408                                  "%s%c", tr->name, 'a' + new->devnum);
409                 else
410                         snprintf(gd->disk_name, sizeof(gd->disk_name),
411                                  "%s%c%c", tr->name,
412                                  'a' - 1 + new->devnum / 26,
413                                  'a' + new->devnum % 26);
414         else
415                 snprintf(gd->disk_name, sizeof(gd->disk_name),
416                          "%s%d", tr->name, new->devnum);
417
418         set_capacity(gd, (new->size * tr->blksize) >> 9);
419
420         /* Create the request queue */
421         spin_lock_init(&new->queue_lock);
422         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
423
424         if (!new->rq)
425                 goto error3;
426
427         new->rq->queuedata = new;
428         blk_queue_logical_block_size(new->rq, tr->blksize);
429
430         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
431
432         if (tr->discard) {
433                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
434                 new->rq->limits.max_discard_sectors = UINT_MAX;
435         }
436
437         gd->queue = new->rq;
438
439         /* Create processing thread */
440         /* TODO: workqueue ? */
441         new->thread = kthread_run(mtd_blktrans_thread, new,
442                         "%s%d", tr->name, new->mtd->index);
443         if (IS_ERR(new->thread)) {
444                 ret = PTR_ERR(new->thread);
445                 goto error4;
446         }
447         gd->driverfs_dev = &new->mtd->dev;
448
449         if (new->readonly)
450                 set_disk_ro(gd, 1);
451
452         add_disk(gd);
453
454         if (new->disk_attributes) {
455                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
456                                         new->disk_attributes);
457                 WARN_ON(ret);
458         }
459         return 0;
460 error4:
461         blk_cleanup_queue(new->rq);
462 error3:
463         put_disk(new->disk);
464 error2:
465         list_del(&new->list);
466 error1:
467         return ret;
468 }
469
470 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
471 {
472         unsigned long flags;
473
474         if (mutex_trylock(&mtd_table_mutex)) {
475                 mutex_unlock(&mtd_table_mutex);
476                 BUG();
477         }
478
479         if (old->disk_attributes)
480                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
481                                                 old->disk_attributes);
482
483         /* Stop new requests to arrive */
484         del_gendisk(old->disk);
485
486
487         /* Stop the thread */
488         kthread_stop(old->thread);
489
490         /* Kill current requests */
491         spin_lock_irqsave(&old->queue_lock, flags);
492         old->rq->queuedata = NULL;
493         blk_start_queue(old->rq);
494         spin_unlock_irqrestore(&old->queue_lock, flags);
495
496         /* If the device is currently open, tell trans driver to close it,
497                 then put mtd device, and don't touch it again */
498         mutex_lock(&old->lock);
499         if (old->open) {
500                 if (old->tr->release)
501                         old->tr->release(old);
502                 __put_mtd_device(old->mtd);
503         }
504
505         old->mtd = NULL;
506
507         mutex_unlock(&old->lock);
508         blktrans_dev_put(old);
509         return 0;
510 }
511
512 static void blktrans_notify_remove(struct mtd_info *mtd)
513 {
514         struct mtd_blktrans_ops *tr;
515         struct mtd_blktrans_dev *dev, *next;
516
517         list_for_each_entry(tr, &blktrans_majors, list)
518                 list_for_each_entry_safe(dev, next, &tr->devs, list)
519                         if (dev->mtd == mtd)
520                                 tr->remove_dev(dev);
521 }
522
523 static void blktrans_notify_add(struct mtd_info *mtd)
524 {
525         struct mtd_blktrans_ops *tr;
526
527         if (mtd->type == MTD_ABSENT)
528                 return;
529
530         list_for_each_entry(tr, &blktrans_majors, list)
531                 tr->add_mtd(tr, mtd);
532 }
533
534 static struct mtd_notifier blktrans_notifier = {
535         .add = blktrans_notify_add,
536         .remove = blktrans_notify_remove,
537 };
538
539 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
540 {
541         struct mtd_info *mtd;
542         int ret;
543
544         /* Register the notifier if/when the first device type is
545            registered, to prevent the link/init ordering from fucking
546            us over. */
547         if (!blktrans_notifier.list.next)
548                 register_mtd_user(&blktrans_notifier);
549
550
551         mutex_lock(&mtd_table_mutex);
552
553         ret = register_blkdev(tr->major, tr->name);
554         if (ret < 0) {
555                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
556                        tr->name, tr->major, ret);
557                 mutex_unlock(&mtd_table_mutex);
558                 return ret;
559         }
560
561         if (ret)
562                 tr->major = ret;
563
564         tr->blkshift = ffs(tr->blksize) - 1;
565
566         INIT_LIST_HEAD(&tr->devs);
567         list_add(&tr->list, &blktrans_majors);
568
569         mtd_for_each_device(mtd)
570                 if (mtd->type != MTD_ABSENT)
571                         tr->add_mtd(tr, mtd);
572
573         mutex_unlock(&mtd_table_mutex);
574         return 0;
575 }
576
577 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
578 {
579         struct mtd_blktrans_dev *dev, *next;
580
581         mutex_lock(&mtd_table_mutex);
582
583         /* Remove it from the list of active majors */
584         list_del(&tr->list);
585
586         list_for_each_entry_safe(dev, next, &tr->devs, list)
587                 tr->remove_dev(dev);
588
589         unregister_blkdev(tr->major, tr->name);
590         mutex_unlock(&mtd_table_mutex);
591
592         BUG_ON(!list_empty(&tr->devs));
593         return 0;
594 }
595
596 static void __exit mtd_blktrans_exit(void)
597 {
598         /* No race here -- if someone's currently in register_mtd_blktrans
599            we're screwed anyway. */
600         if (blktrans_notifier.list.next)
601                 unregister_mtd_user(&blktrans_notifier);
602 }
603
604 module_exit(mtd_blktrans_exit);
605
606 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
607 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
608 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
609 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
610
611 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
612 MODULE_LICENSE("GPL");
613 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");