mtd: Remove redundant mutex from mtd_blkdevs.c
[~shefty/rdma-dev.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 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 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 static int mtd_blktrans_thread(void *arg)
123 {
124         struct mtd_blktrans_dev *dev = arg;
125         struct request_queue *rq = dev->rq;
126         struct request *req = NULL;
127
128         spin_lock_irq(rq->queue_lock);
129
130         while (!kthread_should_stop()) {
131                 int res;
132
133                 if (!req && !(req = blk_fetch_request(rq))) {
134                         set_current_state(TASK_INTERRUPTIBLE);
135
136                         if (kthread_should_stop())
137                                 set_current_state(TASK_RUNNING);
138
139                         spin_unlock_irq(rq->queue_lock);
140                         schedule();
141                         spin_lock_irq(rq->queue_lock);
142                         continue;
143                 }
144
145                 spin_unlock_irq(rq->queue_lock);
146
147                 mutex_lock(&dev->lock);
148                 res = do_blktrans_request(dev->tr, dev, req);
149                 mutex_unlock(&dev->lock);
150
151                 spin_lock_irq(rq->queue_lock);
152
153                 if (!__blk_end_request_cur(req, res))
154                         req = NULL;
155         }
156
157         if (req)
158                 __blk_end_request_all(req, -EIO);
159
160         spin_unlock_irq(rq->queue_lock);
161
162         return 0;
163 }
164
165 static void mtd_blktrans_request(struct request_queue *rq)
166 {
167         struct mtd_blktrans_dev *dev;
168         struct request *req = NULL;
169
170         dev = rq->queuedata;
171
172         if (!dev)
173                 while ((req = blk_fetch_request(rq)) != NULL)
174                         __blk_end_request_all(req, -ENODEV);
175         else
176                 wake_up_process(dev->thread);
177 }
178
179 static int blktrans_open(struct block_device *bdev, fmode_t mode)
180 {
181         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
182         int ret = 0;
183
184         if (!dev)
185                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
186
187         mutex_lock(&dev->lock);
188
189         if (dev->open++)
190                 goto unlock;
191
192         kref_get(&dev->ref);
193         __module_get(dev->tr->owner);
194
195         if (dev->mtd) {
196                 ret = dev->tr->open ? dev->tr->open(dev) : 0;
197                 __get_mtd_device(dev->mtd);
198         }
199
200 unlock:
201         mutex_unlock(&dev->lock);
202         blktrans_dev_put(dev);
203         return ret;
204 }
205
206 static int blktrans_release(struct gendisk *disk, fmode_t mode)
207 {
208         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
209         int ret = 0;
210
211         if (!dev)
212                 return ret;
213
214         mutex_lock(&dev->lock);
215
216         if (--dev->open)
217                 goto unlock;
218
219         kref_put(&dev->ref, blktrans_dev_release);
220         module_put(dev->tr->owner);
221
222         if (dev->mtd) {
223                 ret = dev->tr->release ? dev->tr->release(dev) : 0;
224                 __put_mtd_device(dev->mtd);
225         }
226 unlock:
227         mutex_unlock(&dev->lock);
228         blktrans_dev_put(dev);
229         return ret;
230 }
231
232 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
233 {
234         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
235         int ret = -ENXIO;
236
237         if (!dev)
238                 return ret;
239
240         mutex_lock(&dev->lock);
241
242         if (!dev->mtd)
243                 goto unlock;
244
245         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
246 unlock:
247         mutex_unlock(&dev->lock);
248         blktrans_dev_put(dev);
249         return ret;
250 }
251
252 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
253                               unsigned int cmd, unsigned long arg)
254 {
255         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
256         int ret = -ENXIO;
257
258         if (!dev)
259                 return ret;
260
261         mutex_lock(&dev->lock);
262
263         if (!dev->mtd)
264                 goto unlock;
265
266         switch (cmd) {
267         case BLKFLSBUF:
268                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
269                 break;
270         default:
271                 ret = -ENOTTY;
272         }
273 unlock:
274         mutex_unlock(&dev->lock);
275         blktrans_dev_put(dev);
276         return ret;
277 }
278
279 static const struct block_device_operations mtd_blktrans_ops = {
280         .owner          = THIS_MODULE,
281         .open           = blktrans_open,
282         .release        = blktrans_release,
283         .ioctl          = blktrans_ioctl,
284         .getgeo         = blktrans_getgeo,
285 };
286
287 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
288 {
289         struct mtd_blktrans_ops *tr = new->tr;
290         struct mtd_blktrans_dev *d;
291         int last_devnum = -1;
292         struct gendisk *gd;
293         int ret;
294
295         if (mutex_trylock(&mtd_table_mutex)) {
296                 mutex_unlock(&mtd_table_mutex);
297                 BUG();
298         }
299
300         mutex_lock(&blktrans_ref_mutex);
301         list_for_each_entry(d, &tr->devs, list) {
302                 if (new->devnum == -1) {
303                         /* Use first free number */
304                         if (d->devnum != last_devnum+1) {
305                                 /* Found a free devnum. Plug it in here */
306                                 new->devnum = last_devnum+1;
307                                 list_add_tail(&new->list, &d->list);
308                                 goto added;
309                         }
310                 } else if (d->devnum == new->devnum) {
311                         /* Required number taken */
312                         mutex_unlock(&blktrans_ref_mutex);
313                         return -EBUSY;
314                 } else if (d->devnum > new->devnum) {
315                         /* Required number was free */
316                         list_add_tail(&new->list, &d->list);
317                         goto added;
318                 }
319                 last_devnum = d->devnum;
320         }
321
322         ret = -EBUSY;
323         if (new->devnum == -1)
324                 new->devnum = last_devnum+1;
325
326         /* Check that the device and any partitions will get valid
327          * minor numbers and that the disk naming code below can cope
328          * with this number. */
329         if (new->devnum > (MINORMASK >> tr->part_bits) ||
330             (tr->part_bits && new->devnum >= 27 * 26)) {
331                 mutex_unlock(&blktrans_ref_mutex);
332                 goto error1;
333         }
334
335         list_add_tail(&new->list, &tr->devs);
336  added:
337         mutex_unlock(&blktrans_ref_mutex);
338
339         mutex_init(&new->lock);
340         kref_init(&new->ref);
341         if (!tr->writesect)
342                 new->readonly = 1;
343
344         /* Create gendisk */
345         ret = -ENOMEM;
346         gd = alloc_disk(1 << tr->part_bits);
347
348         if (!gd)
349                 goto error2;
350
351         new->disk = gd;
352         gd->private_data = new;
353         gd->major = tr->major;
354         gd->first_minor = (new->devnum) << tr->part_bits;
355         gd->fops = &mtd_blktrans_ops;
356
357         if (tr->part_bits)
358                 if (new->devnum < 26)
359                         snprintf(gd->disk_name, sizeof(gd->disk_name),
360                                  "%s%c", tr->name, 'a' + new->devnum);
361                 else
362                         snprintf(gd->disk_name, sizeof(gd->disk_name),
363                                  "%s%c%c", tr->name,
364                                  'a' - 1 + new->devnum / 26,
365                                  'a' + new->devnum % 26);
366         else
367                 snprintf(gd->disk_name, sizeof(gd->disk_name),
368                          "%s%d", tr->name, new->devnum);
369
370         set_capacity(gd, (new->size * tr->blksize) >> 9);
371
372         /* Create the request queue */
373         spin_lock_init(&new->queue_lock);
374         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
375
376         if (!new->rq)
377                 goto error3;
378
379         new->rq->queuedata = new;
380         blk_queue_logical_block_size(new->rq, tr->blksize);
381
382         if (tr->discard)
383                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
384                                         new->rq);
385
386         gd->queue = new->rq;
387
388         /* Create processing thread */
389         /* TODO: workqueue ? */
390         new->thread = kthread_run(mtd_blktrans_thread, new,
391                         "%s%d", tr->name, new->mtd->index);
392         if (IS_ERR(new->thread)) {
393                 ret = PTR_ERR(new->thread);
394                 goto error4;
395         }
396         gd->driverfs_dev = &new->mtd->dev;
397
398         if (new->readonly)
399                 set_disk_ro(gd, 1);
400
401         add_disk(gd);
402
403         if (new->disk_attributes) {
404                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
405                                         new->disk_attributes);
406                 WARN_ON(ret);
407         }
408         return 0;
409 error4:
410         blk_cleanup_queue(new->rq);
411 error3:
412         put_disk(new->disk);
413 error2:
414         list_del(&new->list);
415 error1:
416         kfree(new);
417         return ret;
418 }
419
420 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
421 {
422         unsigned long flags;
423
424         if (mutex_trylock(&mtd_table_mutex)) {
425                 mutex_unlock(&mtd_table_mutex);
426                 BUG();
427         }
428
429         if (old->disk_attributes)
430                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
431                                                 old->disk_attributes);
432
433         /* Stop new requests to arrive */
434         del_gendisk(old->disk);
435
436
437         /* Stop the thread */
438         kthread_stop(old->thread);
439
440         /* Kill current requests */
441         spin_lock_irqsave(&old->queue_lock, flags);
442         old->rq->queuedata = NULL;
443         blk_start_queue(old->rq);
444         spin_unlock_irqrestore(&old->queue_lock, flags);
445
446         /* If the device is currently open, tell trans driver to close it,
447                 then put mtd device, and don't touch it again */
448         mutex_lock(&old->lock);
449         if (old->open) {
450                 if (old->tr->release)
451                         old->tr->release(old);
452                 __put_mtd_device(old->mtd);
453         }
454
455         old->mtd = NULL;
456
457         mutex_unlock(&old->lock);
458         blktrans_dev_put(old);
459         return 0;
460 }
461
462 static void blktrans_notify_remove(struct mtd_info *mtd)
463 {
464         struct mtd_blktrans_ops *tr;
465         struct mtd_blktrans_dev *dev, *next;
466
467         list_for_each_entry(tr, &blktrans_majors, list)
468                 list_for_each_entry_safe(dev, next, &tr->devs, list)
469                         if (dev->mtd == mtd)
470                                 tr->remove_dev(dev);
471 }
472
473 static void blktrans_notify_add(struct mtd_info *mtd)
474 {
475         struct mtd_blktrans_ops *tr;
476
477         if (mtd->type == MTD_ABSENT)
478                 return;
479
480         list_for_each_entry(tr, &blktrans_majors, list)
481                 tr->add_mtd(tr, mtd);
482 }
483
484 static struct mtd_notifier blktrans_notifier = {
485         .add = blktrans_notify_add,
486         .remove = blktrans_notify_remove,
487 };
488
489 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
490 {
491         struct mtd_info *mtd;
492         int ret;
493
494         /* Register the notifier if/when the first device type is
495            registered, to prevent the link/init ordering from fucking
496            us over. */
497         if (!blktrans_notifier.list.next)
498                 register_mtd_user(&blktrans_notifier);
499
500
501         mutex_lock(&mtd_table_mutex);
502
503         ret = register_blkdev(tr->major, tr->name);
504         if (ret < 0) {
505                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
506                        tr->name, tr->major, ret);
507                 mutex_unlock(&mtd_table_mutex);
508                 return ret;
509         }
510
511         if (ret)
512                 tr->major = ret;
513
514         tr->blkshift = ffs(tr->blksize) - 1;
515
516         INIT_LIST_HEAD(&tr->devs);
517         list_add(&tr->list, &blktrans_majors);
518
519         mtd_for_each_device(mtd)
520                 if (mtd->type != MTD_ABSENT)
521                         tr->add_mtd(tr, mtd);
522
523         mutex_unlock(&mtd_table_mutex);
524         return 0;
525 }
526
527 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
528 {
529         struct mtd_blktrans_dev *dev, *next;
530
531         mutex_lock(&mtd_table_mutex);
532
533         /* Remove it from the list of active majors */
534         list_del(&tr->list);
535
536         list_for_each_entry_safe(dev, next, &tr->devs, list)
537                 tr->remove_dev(dev);
538
539         unregister_blkdev(tr->major, tr->name);
540         mutex_unlock(&mtd_table_mutex);
541
542         BUG_ON(!list_empty(&tr->devs));
543         return 0;
544 }
545
546 static void __exit mtd_blktrans_exit(void)
547 {
548         /* No race here -- if someone's currently in register_mtd_blktrans
549            we're screwed anyway. */
550         if (blktrans_notifier.list.next)
551                 unregister_mtd_user(&blktrans_notifier);
552 }
553
554 module_exit(mtd_blktrans_exit);
555
556 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
557 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
558 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
559 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
560
561 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
562 MODULE_LICENSE("GPL");
563 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");