Root/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
40static LIST_HEAD(blktrans_majors);
41static DEFINE_MUTEX(blktrans_ref_mutex);
42
43static 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
55static 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);
65unlock:
66    mutex_unlock(&blktrans_ref_mutex);
67    return dev;
68}
69
70static 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
78static 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
122int 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}
129EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
130
131static 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
192static 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
208static 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
238unlock:
239    dev->open++;
240    mutex_unlock(&dev->lock);
241    blktrans_dev_put(dev);
242    return ret;
243
244error_release:
245    if (dev->tr->release)
246        dev->tr->release(dev);
247error_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
255static 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    }
275unlock:
276    mutex_unlock(&dev->lock);
277    blktrans_dev_put(dev);
278    return ret;
279}
280
281static 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;
295unlock:
296    mutex_unlock(&dev->lock);
297    blktrans_dev_put(dev);
298    return ret;
299}
300
301static 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    }
322unlock:
323    mutex_unlock(&dev->lock);
324    blktrans_dev_put(dev);
325    return ret;
326}
327
328static 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
336int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
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
344    if (mutex_trylock(&mtd_table_mutex)) {
345        mutex_unlock(&mtd_table_mutex);
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;
429    blk_queue_logical_block_size(new->rq, tr->blksize);
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;
461error4:
462    blk_cleanup_queue(new->rq);
463error3:
464    put_disk(new->disk);
465error2:
466    list_del(&new->list);
467error1:
468    return ret;
469}
470
471int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
472{
473    unsigned long flags;
474
475    if (mutex_trylock(&mtd_table_mutex)) {
476        mutex_unlock(&mtd_table_mutex);
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
513static 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
524static 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
535static struct mtd_notifier blktrans_notifier = {
536    .add = blktrans_notify_add,
537    .remove = blktrans_notify_remove,
538};
539
540int 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
552    mutex_lock(&mtd_table_mutex);
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);
558        mutex_unlock(&mtd_table_mutex);
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
570    mtd_for_each_device(mtd)
571        if (mtd->type != MTD_ABSENT)
572            tr->add_mtd(tr, mtd);
573
574    mutex_unlock(&mtd_table_mutex);
575    return 0;
576}
577
578int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
579{
580    struct mtd_blktrans_dev *dev, *next;
581
582    mutex_lock(&mtd_table_mutex);
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);
591    mutex_unlock(&mtd_table_mutex);
592
593    BUG_ON(!list_empty(&tr->devs));
594    return 0;
595}
596
597static 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
605module_exit(mtd_blktrans_exit);
606
607EXPORT_SYMBOL_GPL(register_mtd_blktrans);
608EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
609EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
610EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
611
612MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
613MODULE_LICENSE("GPL");
614MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");
615

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