block: add helpers to run flush_dcache_page() against a bio and a request's pages
[linux-2.6.git] / drivers / mtd / mtd_blkdevs.c
1 /*
2  * (C) 2003 David Woodhouse <dwmw2@infradead.org>
3  *
4  * Interface to Linux 2.5 block layer for MTD 'translation layers'.
5  *
6  */
7
8 #include <linux/kernel.h>
9 #include <linux/slab.h>
10 #include <linux/module.h>
11 #include <linux/list.h>
12 #include <linux/fs.h>
13 #include <linux/mtd/blktrans.h>
14 #include <linux/mtd/mtd.h>
15 #include <linux/blkdev.h>
16 #include <linux/blkpg.h>
17 #include <linux/freezer.h>
18 #include <linux/spinlock.h>
19 #include <linux/hdreg.h>
20 #include <linux/init.h>
21 #include <linux/mutex.h>
22 #include <linux/kthread.h>
23 #include <asm/uaccess.h>
24
25 #include "mtdcore.h"
26
27 static LIST_HEAD(blktrans_majors);
28
29 struct mtd_blkcore_priv {
30         struct task_struct *thread;
31         struct request_queue *rq;
32         spinlock_t queue_lock;
33 };
34
35 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
36                                struct mtd_blktrans_dev *dev,
37                                struct request *req)
38 {
39         unsigned long block, nsect;
40         char *buf;
41
42         block = blk_rq_pos(req) << 9 >> tr->blkshift;
43         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
44
45         buf = req->buffer;
46
47         if (!blk_fs_request(req))
48                 return -EIO;
49
50         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
51             get_capacity(req->rq_disk))
52                 return -EIO;
53
54         if (blk_discard_rq(req))
55                 return tr->discard(dev, block, nsect);
56
57         switch(rq_data_dir(req)) {
58         case READ:
59                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
60                         if (tr->readsect(dev, block, buf))
61                                 return -EIO;
62                 rq_flush_dcache_pages(req);
63                 return 0;
64
65         case WRITE:
66                 if (!tr->writesect)
67                         return -EIO;
68
69                 rq_flush_dcache_pages(req);
70                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
71                         if (tr->writesect(dev, block, buf))
72                                 return -EIO;
73                 return 0;
74
75         default:
76                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
77                 return -EIO;
78         }
79 }
80
81 static int mtd_blktrans_thread(void *arg)
82 {
83         struct mtd_blktrans_ops *tr = arg;
84         struct request_queue *rq = tr->blkcore_priv->rq;
85         struct request *req = NULL;
86
87         /* we might get involved when memory gets low, so use PF_MEMALLOC */
88         current->flags |= PF_MEMALLOC;
89
90         spin_lock_irq(rq->queue_lock);
91
92         while (!kthread_should_stop()) {
93                 struct mtd_blktrans_dev *dev;
94                 int res;
95
96                 if (!req && !(req = blk_fetch_request(rq))) {
97                         set_current_state(TASK_INTERRUPTIBLE);
98                         spin_unlock_irq(rq->queue_lock);
99                         schedule();
100                         spin_lock_irq(rq->queue_lock);
101                         continue;
102                 }
103
104                 dev = req->rq_disk->private_data;
105                 tr = dev->tr;
106
107                 spin_unlock_irq(rq->queue_lock);
108
109                 mutex_lock(&dev->lock);
110                 res = do_blktrans_request(tr, dev, req);
111                 mutex_unlock(&dev->lock);
112
113                 spin_lock_irq(rq->queue_lock);
114
115                 if (!__blk_end_request_cur(req, res))
116                         req = NULL;
117         }
118
119         if (req)
120                 __blk_end_request_all(req, -EIO);
121
122         spin_unlock_irq(rq->queue_lock);
123
124         return 0;
125 }
126
127 static void mtd_blktrans_request(struct request_queue *rq)
128 {
129         struct mtd_blktrans_ops *tr = rq->queuedata;
130         wake_up_process(tr->blkcore_priv->thread);
131 }
132
133
134 static int blktrans_open(struct block_device *bdev, fmode_t mode)
135 {
136         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
137         struct mtd_blktrans_ops *tr = dev->tr;
138         int ret = -ENODEV;
139
140         if (!get_mtd_device(NULL, dev->mtd->index))
141                 goto out;
142
143         if (!try_module_get(tr->owner))
144                 goto out_tr;
145
146         /* FIXME: Locking. A hot pluggable device can go away
147            (del_mtd_device can be called for it) without its module
148            being unloaded. */
149         dev->mtd->usecount++;
150
151         ret = 0;
152         if (tr->open && (ret = tr->open(dev))) {
153                 dev->mtd->usecount--;
154                 put_mtd_device(dev->mtd);
155         out_tr:
156                 module_put(tr->owner);
157         }
158  out:
159         return ret;
160 }
161
162 static int blktrans_release(struct gendisk *disk, fmode_t mode)
163 {
164         struct mtd_blktrans_dev *dev = disk->private_data;
165         struct mtd_blktrans_ops *tr = dev->tr;
166         int ret = 0;
167
168         if (tr->release)
169                 ret = tr->release(dev);
170
171         if (!ret) {
172                 dev->mtd->usecount--;
173                 put_mtd_device(dev->mtd);
174                 module_put(tr->owner);
175         }
176
177         return ret;
178 }
179
180 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
181 {
182         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
183
184         if (dev->tr->getgeo)
185                 return dev->tr->getgeo(dev, geo);
186         return -ENOTTY;
187 }
188
189 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
190                               unsigned int cmd, unsigned long arg)
191 {
192         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
193         struct mtd_blktrans_ops *tr = dev->tr;
194
195         switch (cmd) {
196         case BLKFLSBUF:
197                 if (tr->flush)
198                         return tr->flush(dev);
199                 /* The core code did the work, we had nothing to do. */
200                 return 0;
201         default:
202                 return -ENOTTY;
203         }
204 }
205
206 static const struct block_device_operations mtd_blktrans_ops = {
207         .owner          = THIS_MODULE,
208         .open           = blktrans_open,
209         .release        = blktrans_release,
210         .locked_ioctl   = blktrans_ioctl,
211         .getgeo         = blktrans_getgeo,
212 };
213
214 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
215 {
216         struct mtd_blktrans_ops *tr = new->tr;
217         struct mtd_blktrans_dev *d;
218         int last_devnum = -1;
219         struct gendisk *gd;
220
221         if (mutex_trylock(&mtd_table_mutex)) {
222                 mutex_unlock(&mtd_table_mutex);
223                 BUG();
224         }
225
226         list_for_each_entry(d, &tr->devs, list) {
227                 if (new->devnum == -1) {
228                         /* Use first free number */
229                         if (d->devnum != last_devnum+1) {
230                                 /* Found a free devnum. Plug it in here */
231                                 new->devnum = last_devnum+1;
232                                 list_add_tail(&new->list, &d->list);
233                                 goto added;
234                         }
235                 } else if (d->devnum == new->devnum) {
236                         /* Required number taken */
237                         return -EBUSY;
238                 } else if (d->devnum > new->devnum) {
239                         /* Required number was free */
240                         list_add_tail(&new->list, &d->list);
241                         goto added;
242                 }
243                 last_devnum = d->devnum;
244         }
245         if (new->devnum == -1)
246                 new->devnum = last_devnum+1;
247
248         if ((new->devnum << tr->part_bits) > 256) {
249                 return -EBUSY;
250         }
251
252         list_add_tail(&new->list, &tr->devs);
253  added:
254         mutex_init(&new->lock);
255         if (!tr->writesect)
256                 new->readonly = 1;
257
258         gd = alloc_disk(1 << tr->part_bits);
259         if (!gd) {
260                 list_del(&new->list);
261                 return -ENOMEM;
262         }
263         gd->major = tr->major;
264         gd->first_minor = (new->devnum) << tr->part_bits;
265         gd->fops = &mtd_blktrans_ops;
266
267         if (tr->part_bits)
268                 if (new->devnum < 26)
269                         snprintf(gd->disk_name, sizeof(gd->disk_name),
270                                  "%s%c", tr->name, 'a' + new->devnum);
271                 else
272                         snprintf(gd->disk_name, sizeof(gd->disk_name),
273                                  "%s%c%c", tr->name,
274                                  'a' - 1 + new->devnum / 26,
275                                  'a' + new->devnum % 26);
276         else
277                 snprintf(gd->disk_name, sizeof(gd->disk_name),
278                          "%s%d", tr->name, new->devnum);
279
280         /* 2.5 has capacity in units of 512 bytes while still
281            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
282         set_capacity(gd, (new->size * tr->blksize) >> 9);
283
284         gd->private_data = new;
285         new->blkcore_priv = gd;
286         gd->queue = tr->blkcore_priv->rq;
287         gd->driverfs_dev = &new->mtd->dev;
288
289         if (new->readonly)
290                 set_disk_ro(gd, 1);
291
292         add_disk(gd);
293
294         return 0;
295 }
296
297 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
298 {
299         if (mutex_trylock(&mtd_table_mutex)) {
300                 mutex_unlock(&mtd_table_mutex);
301                 BUG();
302         }
303
304         list_del(&old->list);
305
306         del_gendisk(old->blkcore_priv);
307         put_disk(old->blkcore_priv);
308
309         return 0;
310 }
311
312 static void blktrans_notify_remove(struct mtd_info *mtd)
313 {
314         struct mtd_blktrans_ops *tr;
315         struct mtd_blktrans_dev *dev, *next;
316
317         list_for_each_entry(tr, &blktrans_majors, list)
318                 list_for_each_entry_safe(dev, next, &tr->devs, list)
319                         if (dev->mtd == mtd)
320                                 tr->remove_dev(dev);
321 }
322
323 static void blktrans_notify_add(struct mtd_info *mtd)
324 {
325         struct mtd_blktrans_ops *tr;
326
327         if (mtd->type == MTD_ABSENT)
328                 return;
329
330         list_for_each_entry(tr, &blktrans_majors, list)
331                 tr->add_mtd(tr, mtd);
332 }
333
334 static struct mtd_notifier blktrans_notifier = {
335         .add = blktrans_notify_add,
336         .remove = blktrans_notify_remove,
337 };
338
339 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
340 {
341         int ret, i;
342
343         /* Register the notifier if/when the first device type is
344            registered, to prevent the link/init ordering from fucking
345            us over. */
346         if (!blktrans_notifier.list.next)
347                 register_mtd_user(&blktrans_notifier);
348
349         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
350         if (!tr->blkcore_priv)
351                 return -ENOMEM;
352
353         mutex_lock(&mtd_table_mutex);
354
355         ret = register_blkdev(tr->major, tr->name);
356         if (ret) {
357                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
358                        tr->name, tr->major, ret);
359                 kfree(tr->blkcore_priv);
360                 mutex_unlock(&mtd_table_mutex);
361                 return ret;
362         }
363         spin_lock_init(&tr->blkcore_priv->queue_lock);
364
365         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
366         if (!tr->blkcore_priv->rq) {
367                 unregister_blkdev(tr->major, tr->name);
368                 kfree(tr->blkcore_priv);
369                 mutex_unlock(&mtd_table_mutex);
370                 return -ENOMEM;
371         }
372
373         tr->blkcore_priv->rq->queuedata = tr;
374         blk_queue_logical_block_size(tr->blkcore_priv->rq, tr->blksize);
375         if (tr->discard)
376                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
377                                         tr->blkcore_priv->rq);
378
379         tr->blkshift = ffs(tr->blksize) - 1;
380
381         tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
382                         "%sd", tr->name);
383         if (IS_ERR(tr->blkcore_priv->thread)) {
384                 int ret = PTR_ERR(tr->blkcore_priv->thread);
385                 blk_cleanup_queue(tr->blkcore_priv->rq);
386                 unregister_blkdev(tr->major, tr->name);
387                 kfree(tr->blkcore_priv);
388                 mutex_unlock(&mtd_table_mutex);
389                 return ret;
390         }
391
392         INIT_LIST_HEAD(&tr->devs);
393         list_add(&tr->list, &blktrans_majors);
394
395         for (i=0; i<MAX_MTD_DEVICES; i++) {
396                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
397                         tr->add_mtd(tr, mtd_table[i]);
398         }
399
400         mutex_unlock(&mtd_table_mutex);
401
402         return 0;
403 }
404
405 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
406 {
407         struct mtd_blktrans_dev *dev, *next;
408
409         mutex_lock(&mtd_table_mutex);
410
411         /* Clean up the kernel thread */
412         kthread_stop(tr->blkcore_priv->thread);
413
414         /* Remove it from the list of active majors */
415         list_del(&tr->list);
416
417         list_for_each_entry_safe(dev, next, &tr->devs, list)
418                 tr->remove_dev(dev);
419
420         blk_cleanup_queue(tr->blkcore_priv->rq);
421         unregister_blkdev(tr->major, tr->name);
422
423         mutex_unlock(&mtd_table_mutex);
424
425         kfree(tr->blkcore_priv);
426
427         BUG_ON(!list_empty(&tr->devs));
428         return 0;
429 }
430
431 static void __exit mtd_blktrans_exit(void)
432 {
433         /* No race here -- if someone's currently in register_mtd_blktrans
434            we're screwed anyway. */
435         if (blktrans_notifier.list.next)
436                 unregister_mtd_user(&blktrans_notifier);
437 }
438
439 module_exit(mtd_blktrans_exit);
440
441 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
442 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
443 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
444 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
445
446 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
447 MODULE_LICENSE("GPL");
448 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");