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 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
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 = blk_rq_pos(req) << 9 >> tr->blkshift;
51 nsect = blk_rq_cur_bytes(req) >> 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 -EIO;
61
62 if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
63 get_capacity(req->rq_disk))
64 return -EIO;
65
66 switch(rq_data_dir(req)) {
67 case READ:
68 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
69 if (tr->readsect(dev, block, buf))
70 return -EIO;
71 return 0;
72
73 case WRITE:
74 if (!tr->writesect)
75 return -EIO;
76
77 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
78 if (tr->writesect(dev, block, buf))
79 return -EIO;
80 return 0;
81
82 default:
83 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
84 return -EIO;
85 }
86 }
87
88 static int mtd_blktrans_thread(void *arg)
89 {
90 struct mtd_blktrans_ops *tr = arg;
91 struct request_queue *rq = tr->blkcore_priv->rq;
92 struct request *req = NULL;
93
94 /* we might get involved when memory gets low, so use PF_MEMALLOC */
95 current->flags |= PF_MEMALLOC;
96
97 spin_lock_irq(rq->queue_lock);
98
99 while (!kthread_should_stop()) {
100 struct mtd_blktrans_dev *dev;
101 int res;
102
103 if (!req && !(req = blk_fetch_request(rq))) {
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 if (!__blk_end_request_cur(req, res))
123 req = NULL;
124 }
125
126 if (req)
127 __blk_end_request_all(req, -EIO);
128
129 spin_unlock_irq(rq->queue_lock);
130
131 return 0;
132 }
133
134 static void mtd_blktrans_request(struct request_queue *rq)
135 {
136 struct mtd_blktrans_ops *tr = rq->queuedata;
137 wake_up_process(tr->blkcore_priv->thread);
138 }
139
140
141 static int blktrans_open(struct block_device *bdev, fmode_t mode)
142 {
143 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
144 struct mtd_blktrans_ops *tr = dev->tr;
145 int ret = -ENODEV;
146
147 if (!get_mtd_device(NULL, dev->mtd->index))
148 goto out;
149
150 if (!try_module_get(tr->owner))
151 goto out_tr;
152
153 /* FIXME: Locking. A hot pluggable device can go away
154 (del_mtd_device can be called for it) without its module
155 being unloaded. */
156 dev->mtd->usecount++;
157
158 ret = 0;
159 if (tr->open && (ret = tr->open(dev))) {
160 dev->mtd->usecount--;
161 put_mtd_device(dev->mtd);
162 out_tr:
163 module_put(tr->owner);
164 }
165 out:
166 return ret;
167 }
168
169 static int blktrans_release(struct gendisk *disk, fmode_t mode)
170 {
171 struct mtd_blktrans_dev *dev = disk->private_data;
172 struct mtd_blktrans_ops *tr = dev->tr;
173 int ret = 0;
174
175 if (tr->release)
176 ret = tr->release(dev);
177
178 if (!ret) {
179 dev->mtd->usecount--;
180 put_mtd_device(dev->mtd);
181 module_put(tr->owner);
182 }
183
184 return ret;
185 }
186
187 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
188 {
189 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
190
191 if (dev->tr->getgeo)
192 return dev->tr->getgeo(dev, geo);
193 return -ENOTTY;
194 }
195
196 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
197 unsigned int cmd, unsigned long arg)
198 {
199 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
200 struct mtd_blktrans_ops *tr = dev->tr;
201
202 switch (cmd) {
203 case BLKFLSBUF:
204 if (tr->flush)
205 return tr->flush(dev);
206 /* The core code did the work, we had nothing to do. */
207 return 0;
208 default:
209 return -ENOTTY;
210 }
211 }
212
213 static struct block_device_operations mtd_blktrans_ops = {
214 .owner = THIS_MODULE,
215 .open = blktrans_open,
216 .release = blktrans_release,
217 .locked_ioctl = blktrans_ioctl,
218 .getgeo = blktrans_getgeo,
219 };
220
221 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
222 {
223 struct mtd_blktrans_ops *tr = new->tr;
224 struct mtd_blktrans_dev *d;
225 int last_devnum = -1;
226 struct gendisk *gd;
227
228 if (mutex_trylock(&mtd_table_mutex)) {
229 mutex_unlock(&mtd_table_mutex);
230 BUG();
231 }
232
233 list_for_each_entry(d, &tr->devs, list) {
234 if (new->devnum == -1) {
235 /* Use first free number */
236 if (d->devnum != last_devnum+1) {
237 /* Found a free devnum. Plug it in here */
238 new->devnum = last_devnum+1;
239 list_add_tail(&new->list, &d->list);
240 goto added;
241 }
242 } else if (d->devnum == new->devnum) {
243 /* Required number taken */
244 return -EBUSY;
245 } else if (d->devnum > new->devnum) {
246 /* Required number was free */
247 list_add_tail(&new->list, &d->list);
248 goto added;
249 }
250 last_devnum = d->devnum;
251 }
252 if (new->devnum == -1)
253 new->devnum = last_devnum+1;
254
255 if ((new->devnum << tr->part_bits) > 256) {
256 return -EBUSY;
257 }
258
259 list_add_tail(&new->list, &tr->devs);
260 added:
261 mutex_init(&new->lock);
262 if (!tr->writesect)
263 new->readonly = 1;
264
265 gd = alloc_disk(1 << tr->part_bits);
266 if (!gd) {
267 list_del(&new->list);
268 return -ENOMEM;
269 }
270 gd->major = tr->major;
271 gd->first_minor = (new->devnum) << tr->part_bits;
272 gd->fops = &mtd_blktrans_ops;
273
274 if (tr->part_bits)
275 if (new->devnum < 26)
276 snprintf(gd->disk_name, sizeof(gd->disk_name),
277 "%s%c", tr->name, 'a' + new->devnum);
278 else
279 snprintf(gd->disk_name, sizeof(gd->disk_name),
280 "%s%c%c", tr->name,
281 'a' - 1 + new->devnum / 26,
282 'a' + new->devnum % 26);
283 else
284 snprintf(gd->disk_name, sizeof(gd->disk_name),
285 "%s%d", tr->name, new->devnum);
286
287 /* 2.5 has capacity in units of 512 bytes while still
288 having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
289 set_capacity(gd, (new->size * tr->blksize) >> 9);
290
291 gd->private_data = new;
292 new->blkcore_priv = gd;
293 gd->queue = tr->blkcore_priv->rq;
294 gd->driverfs_dev = &new->mtd->dev;
295
296 if (new->readonly)
297 set_disk_ro(gd, 1);
298
299 add_disk(gd);
300
301 return 0;
302 }
303
304 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
305 {
306 if (mutex_trylock(&mtd_table_mutex)) {
307 mutex_unlock(&mtd_table_mutex);
308 BUG();
309 }
310
311 list_del(&old->list);
312
313 del_gendisk(old->blkcore_priv);
314 put_disk(old->blkcore_priv);
315
316 return 0;
317 }
318
319 static void blktrans_notify_remove(struct mtd_info *mtd)
320 {
321 struct mtd_blktrans_ops *tr;
322 struct mtd_blktrans_dev *dev, *next;
323
324 list_for_each_entry(tr, &blktrans_majors, list)
325 list_for_each_entry_safe(dev, next, &tr->devs, list)
326 if (dev->mtd == mtd)
327 tr->remove_dev(dev);
328 }
329
330 static void blktrans_notify_add(struct mtd_info *mtd)
331 {
332 struct mtd_blktrans_ops *tr;
333
334 if (mtd->type == MTD_ABSENT)
335 return;
336
337 list_for_each_entry(tr, &blktrans_majors, list)
338 tr->add_mtd(tr, mtd);
339 }
340
341 static struct mtd_notifier blktrans_notifier = {
342 .add = blktrans_notify_add,
343 .remove = blktrans_notify_remove,
344 };
345
346 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
347 {
348 int ret, i;
349
350 /* Register the notifier if/when the first device type is
351 registered, to prevent the link/init ordering from fucking
352 us over. */
353 if (!blktrans_notifier.list.next)
354 register_mtd_user(&blktrans_notifier);
355
356 tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
357 if (!tr->blkcore_priv)
358 return -ENOMEM;
359
360 mutex_lock(&mtd_table_mutex);
361
362 ret = register_blkdev(tr->major, tr->name);
363 if (ret) {
364 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
365 tr->name, tr->major, ret);
366 kfree(tr->blkcore_priv);
367 mutex_unlock(&mtd_table_mutex);
368 return ret;
369 }
370 spin_lock_init(&tr->blkcore_priv->queue_lock);
371
372 tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
373 if (!tr->blkcore_priv->rq) {
374 unregister_blkdev(tr->major, tr->name);
375 kfree(tr->blkcore_priv);
376 mutex_unlock(&mtd_table_mutex);
377 return -ENOMEM;
378 }
379
380 tr->blkcore_priv->rq->queuedata = tr;
381 blk_queue_logical_block_size(tr->blkcore_priv->rq, tr->blksize);
382 if (tr->discard)
383 blk_queue_set_discard(tr->blkcore_priv->rq,
384 blktrans_discard_request);
385
386 tr->blkshift = ffs(tr->blksize) - 1;
387
388 tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
389 "%sd", tr->name);
390 if (IS_ERR(tr->blkcore_priv->thread)) {
391 int ret = PTR_ERR(tr->blkcore_priv->thread);
392 blk_cleanup_queue(tr->blkcore_priv->rq);
393 unregister_blkdev(tr->major, tr->name);
394 kfree(tr->blkcore_priv);
395 mutex_unlock(&mtd_table_mutex);
396 return ret;
397 }
398
399 INIT_LIST_HEAD(&tr->devs);
400 list_add(&tr->list, &blktrans_majors);
401
402 for (i=0; i<MAX_MTD_DEVICES; i++) {
403 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
404 tr->add_mtd(tr, mtd_table[i]);
405 }
406
407 mutex_unlock(&mtd_table_mutex);
408
409 return 0;
410 }
411
412 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
413 {
414 struct mtd_blktrans_dev *dev, *next;
415
416 mutex_lock(&mtd_table_mutex);
417
418 /* Clean up the kernel thread */
419 kthread_stop(tr->blkcore_priv->thread);
420
421 /* Remove it from the list of active majors */
422 list_del(&tr->list);
423
424 list_for_each_entry_safe(dev, next, &tr->devs, list)
425 tr->remove_dev(dev);
426
427 blk_cleanup_queue(tr->blkcore_priv->rq);
428 unregister_blkdev(tr->major, tr->name);
429
430 mutex_unlock(&mtd_table_mutex);
431
432 kfree(tr->blkcore_priv);
433
434 BUG_ON(!list_empty(&tr->devs));
435 return 0;
436 }
437
438 static void __exit mtd_blktrans_exit(void)
439 {
440 /* No race here -- if someone's currently in register_mtd_blktrans
441 we're screwed anyway. */
442 if (blktrans_notifier.list.next)
443 unregister_mtd_user(&blktrans_notifier);
444 }
445
446 module_exit(mtd_blktrans_exit);
447
448 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
449 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
450 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
451 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
452
453 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
454 MODULE_LICENSE("GPL");
455 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");
456
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