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
blktrans_discard_request(struct request_queue * q,struct request * req)35 static int blktrans_discard_request(struct request_queue *q,
36 struct request *req)
37 {
38 req->cmd_type = REQ_TYPE_LINUX_BLOCK;
39 req->cmd[0] = REQ_LB_OP_DISCARD;
40 return 0;
41 }
42
do_blktrans_request(struct mtd_blktrans_ops * tr,struct mtd_blktrans_dev * dev,struct request * req)43 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
44 struct mtd_blktrans_dev *dev,
45 struct request *req)
46 {
47 unsigned long block, nsect;
48 char *buf;
49
50 block = req->sector << 9 >> tr->blkshift;
51 nsect = req->current_nr_sectors << 9 >> tr->blkshift;
52
53 buf = req->buffer;
54
55 if (req->cmd_type == REQ_TYPE_LINUX_BLOCK &&
56 req->cmd[0] == REQ_LB_OP_DISCARD)
57 return !tr->discard(dev, block, nsect);
58
59 if (!blk_fs_request(req))
60 return 0;
61
62 if (req->sector + req->current_nr_sectors > get_capacity(req->rq_disk))
63 return 0;
64
65 switch(rq_data_dir(req)) {
66 case READ:
67 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
68 if (tr->readsect(dev, block, buf))
69 return 0;
70 return 1;
71
72 case WRITE:
73 if (!tr->writesect)
74 return 0;
75
76 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
77 if (tr->writesect(dev, block, buf))
78 return 0;
79 return 1;
80
81 default:
82 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
83 return 0;
84 }
85 }
86
mtd_blktrans_thread(void * arg)87 static int mtd_blktrans_thread(void *arg)
88 {
89 struct mtd_blktrans_ops *tr = arg;
90 struct request_queue *rq = tr->blkcore_priv->rq;
91
92 /* we might get involved when memory gets low, so use PF_MEMALLOC */
93 current->flags |= PF_MEMALLOC;
94
95 spin_lock_irq(rq->queue_lock);
96 while (!kthread_should_stop()) {
97 struct request *req;
98 struct mtd_blktrans_dev *dev;
99 int res = 0;
100
101 req = elv_next_request(rq);
102
103 if (!req) {
104 set_current_state(TASK_INTERRUPTIBLE);
105 spin_unlock_irq(rq->queue_lock);
106 schedule();
107 spin_lock_irq(rq->queue_lock);
108 continue;
109 }
110
111 dev = req->rq_disk->private_data;
112 tr = dev->tr;
113
114 spin_unlock_irq(rq->queue_lock);
115
116 mutex_lock(&dev->lock);
117 res = do_blktrans_request(tr, dev, req);
118 mutex_unlock(&dev->lock);
119
120 spin_lock_irq(rq->queue_lock);
121
122 end_request(req, res);
123 }
124 spin_unlock_irq(rq->queue_lock);
125
126 return 0;
127 }
128
mtd_blktrans_request(struct request_queue * rq)129 static void mtd_blktrans_request(struct request_queue *rq)
130 {
131 struct mtd_blktrans_ops *tr = rq->queuedata;
132 wake_up_process(tr->blkcore_priv->thread);
133 }
134
135
blktrans_open(struct block_device * bdev,fmode_t mode)136 static int blktrans_open(struct block_device *bdev, fmode_t mode)
137 {
138 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
139 struct mtd_blktrans_ops *tr = dev->tr;
140 int ret = -ENODEV;
141
142 if (!try_module_get(dev->mtd->owner))
143 goto out;
144
145 if (!try_module_get(tr->owner))
146 goto out_tr;
147
148 /* FIXME: Locking. A hot pluggable device can go away
149 (del_mtd_device can be called for it) without its module
150 being unloaded. */
151 dev->mtd->usecount++;
152
153 ret = 0;
154 if (tr->open && (ret = tr->open(dev))) {
155 dev->mtd->usecount--;
156 module_put(dev->mtd->owner);
157 out_tr:
158 module_put(tr->owner);
159 }
160 out:
161 return ret;
162 }
163
blktrans_release(struct gendisk * disk,fmode_t mode)164 static int blktrans_release(struct gendisk *disk, fmode_t mode)
165 {
166 struct mtd_blktrans_dev *dev = disk->private_data;
167 struct mtd_blktrans_ops *tr = dev->tr;
168 int ret = 0;
169
170 if (tr->release)
171 ret = tr->release(dev);
172
173 if (!ret) {
174 dev->mtd->usecount--;
175 module_put(dev->mtd->owner);
176 module_put(tr->owner);
177 }
178
179 return ret;
180 }
181
blktrans_getgeo(struct block_device * bdev,struct hd_geometry * geo)182 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
183 {
184 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
185
186 if (dev->tr->getgeo)
187 return dev->tr->getgeo(dev, geo);
188 return -ENOTTY;
189 }
190
blktrans_ioctl(struct block_device * bdev,fmode_t mode,unsigned int cmd,unsigned long arg)191 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
192 unsigned int cmd, unsigned long arg)
193 {
194 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
195 struct mtd_blktrans_ops *tr = dev->tr;
196
197 switch (cmd) {
198 case BLKFLSBUF:
199 if (tr->flush)
200 return tr->flush(dev);
201 /* The core code did the work, we had nothing to do. */
202 return 0;
203 default:
204 return -ENOTTY;
205 }
206 }
207
208 static struct block_device_operations mtd_blktrans_ops = {
209 .owner = THIS_MODULE,
210 .open = blktrans_open,
211 .release = blktrans_release,
212 .locked_ioctl = blktrans_ioctl,
213 .getgeo = blktrans_getgeo,
214 };
215
add_mtd_blktrans_dev(struct mtd_blktrans_dev * new)216 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
217 {
218 struct mtd_blktrans_ops *tr = new->tr;
219 struct mtd_blktrans_dev *d;
220 int last_devnum = -1;
221 struct gendisk *gd;
222
223 if (mutex_trylock(&mtd_table_mutex)) {
224 mutex_unlock(&mtd_table_mutex);
225 BUG();
226 }
227
228 list_for_each_entry(d, &tr->devs, list) {
229 if (new->devnum == -1) {
230 /* Use first free number */
231 if (d->devnum != last_devnum+1) {
232 /* Found a free devnum. Plug it in here */
233 new->devnum = last_devnum+1;
234 list_add_tail(&new->list, &d->list);
235 goto added;
236 }
237 } else if (d->devnum == new->devnum) {
238 /* Required number taken */
239 return -EBUSY;
240 } else if (d->devnum > new->devnum) {
241 /* Required number was free */
242 list_add_tail(&new->list, &d->list);
243 goto added;
244 }
245 last_devnum = d->devnum;
246 }
247 if (new->devnum == -1)
248 new->devnum = last_devnum+1;
249
250 if ((new->devnum << tr->part_bits) > 256) {
251 return -EBUSY;
252 }
253
254 list_add_tail(&new->list, &tr->devs);
255 added:
256 mutex_init(&new->lock);
257 if (!tr->writesect)
258 new->readonly = 1;
259
260 gd = alloc_disk(1 << tr->part_bits);
261 if (!gd) {
262 list_del(&new->list);
263 return -ENOMEM;
264 }
265 gd->major = tr->major;
266 gd->first_minor = (new->devnum) << tr->part_bits;
267 gd->fops = &mtd_blktrans_ops;
268
269 if (tr->part_bits)
270 if (new->devnum < 26)
271 snprintf(gd->disk_name, sizeof(gd->disk_name),
272 "%s%c", tr->name, 'a' + new->devnum);
273 else
274 snprintf(gd->disk_name, sizeof(gd->disk_name),
275 "%s%c%c", tr->name,
276 'a' - 1 + new->devnum / 26,
277 'a' + new->devnum % 26);
278 else
279 snprintf(gd->disk_name, sizeof(gd->disk_name),
280 "%s%d", tr->name, new->devnum);
281
282 /* 2.5 has capacity in units of 512 bytes while still
283 having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
284 set_capacity(gd, (new->size * tr->blksize) >> 9);
285
286 gd->private_data = new;
287 new->blkcore_priv = gd;
288 gd->queue = tr->blkcore_priv->rq;
289
290 if (new->readonly)
291 set_disk_ro(gd, 1);
292
293 add_disk(gd);
294
295 return 0;
296 }
297
del_mtd_blktrans_dev(struct mtd_blktrans_dev * old)298 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
299 {
300 if (mutex_trylock(&mtd_table_mutex)) {
301 mutex_unlock(&mtd_table_mutex);
302 BUG();
303 }
304
305 list_del(&old->list);
306
307 del_gendisk(old->blkcore_priv);
308 put_disk(old->blkcore_priv);
309
310 return 0;
311 }
312
blktrans_notify_remove(struct mtd_info * mtd)313 static void blktrans_notify_remove(struct mtd_info *mtd)
314 {
315 struct mtd_blktrans_ops *tr;
316 struct mtd_blktrans_dev *dev, *next;
317
318 list_for_each_entry(tr, &blktrans_majors, list)
319 list_for_each_entry_safe(dev, next, &tr->devs, list)
320 if (dev->mtd == mtd)
321 tr->remove_dev(dev);
322 }
323
blktrans_notify_add(struct mtd_info * mtd)324 static void blktrans_notify_add(struct mtd_info *mtd)
325 {
326 struct mtd_blktrans_ops *tr;
327
328 if (mtd->type == MTD_ABSENT)
329 return;
330
331 list_for_each_entry(tr, &blktrans_majors, list)
332 tr->add_mtd(tr, mtd);
333 }
334
335 static struct mtd_notifier blktrans_notifier = {
336 .add = blktrans_notify_add,
337 .remove = blktrans_notify_remove,
338 };
339
register_mtd_blktrans(struct mtd_blktrans_ops * tr)340 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
341 {
342 int ret, i;
343
344 /* Register the notifier if/when the first device type is
345 registered, to prevent the link/init ordering from fucking
346 us over. */
347 if (!blktrans_notifier.list.next)
348 register_mtd_user(&blktrans_notifier);
349
350 tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
351 if (!tr->blkcore_priv)
352 return -ENOMEM;
353
354 mutex_lock(&mtd_table_mutex);
355
356 ret = register_blkdev(tr->major, tr->name);
357 if (ret) {
358 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
359 tr->name, tr->major, ret);
360 kfree(tr->blkcore_priv);
361 mutex_unlock(&mtd_table_mutex);
362 return ret;
363 }
364 spin_lock_init(&tr->blkcore_priv->queue_lock);
365
366 tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
367 if (!tr->blkcore_priv->rq) {
368 unregister_blkdev(tr->major, tr->name);
369 kfree(tr->blkcore_priv);
370 mutex_unlock(&mtd_table_mutex);
371 return -ENOMEM;
372 }
373
374 tr->blkcore_priv->rq->queuedata = tr;
375 blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
376 if (tr->discard)
377 blk_queue_set_discard(tr->blkcore_priv->rq,
378 blktrans_discard_request);
379
380 tr->blkshift = ffs(tr->blksize) - 1;
381
382 tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
383 "%sd", tr->name);
384 if (IS_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 PTR_ERR(tr->blkcore_priv->thread);
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
deregister_mtd_blktrans(struct mtd_blktrans_ops * tr)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
mtd_blktrans_exit(void)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'");
449