[SCSI] libiscsi: make can_queue configurable
[linux-2.6] / drivers / mtd / mtd_blkdevs.c
1 /*
2  * $Id: mtd_blkdevs.c,v 1.27 2005/11/07 11:14:20 gleixner Exp $
3  *
4  * (C) 2003 David Woodhouse <dwmw2@infradead.org>
5  *
6  * Interface to Linux 2.5 block layer for MTD 'translation layers'.
7  *
8  */
9
10 #include <linux/kernel.h>
11 #include <linux/slab.h>
12 #include <linux/module.h>
13 #include <linux/list.h>
14 #include <linux/fs.h>
15 #include <linux/mtd/blktrans.h>
16 #include <linux/mtd/mtd.h>
17 #include <linux/blkdev.h>
18 #include <linux/blkpg.h>
19 #include <linux/spinlock.h>
20 #include <linux/hdreg.h>
21 #include <linux/init.h>
22 #include <linux/mutex.h>
23 #include <linux/kthread.h>
24 #include <asm/uaccess.h>
25
26 static LIST_HEAD(blktrans_majors);
27
28 extern struct mutex mtd_table_mutex;
29 extern struct mtd_info *mtd_table[];
30
31 struct mtd_blkcore_priv {
32         struct task_struct *thread;
33         struct request_queue *rq;
34         spinlock_t queue_lock;
35 };
36
37 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
38                                struct mtd_blktrans_dev *dev,
39                                struct request *req)
40 {
41         unsigned long block, nsect;
42         char *buf;
43
44         block = req->sector << 9 >> tr->blkshift;
45         nsect = req->current_nr_sectors << 9 >> tr->blkshift;
46
47         buf = req->buffer;
48
49         if (!blk_fs_request(req))
50                 return 0;
51
52         if (req->sector + req->current_nr_sectors > get_capacity(req->rq_disk))
53                 return 0;
54
55         switch(rq_data_dir(req)) {
56         case READ:
57                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
58                         if (tr->readsect(dev, block, buf))
59                                 return 0;
60                 return 1;
61
62         case WRITE:
63                 if (!tr->writesect)
64                         return 0;
65
66                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
67                         if (tr->writesect(dev, block, buf))
68                                 return 0;
69                 return 1;
70
71         default:
72                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
73                 return 0;
74         }
75 }
76
77 static int mtd_blktrans_thread(void *arg)
78 {
79         struct mtd_blktrans_ops *tr = arg;
80         struct request_queue *rq = tr->blkcore_priv->rq;
81
82         /* we might get involved when memory gets low, so use PF_MEMALLOC */
83         current->flags |= PF_MEMALLOC | PF_NOFREEZE;
84
85         spin_lock_irq(rq->queue_lock);
86         while (!kthread_should_stop()) {
87                 struct request *req;
88                 struct mtd_blktrans_dev *dev;
89                 int res = 0;
90
91                 req = elv_next_request(rq);
92
93                 if (!req) {
94                         set_current_state(TASK_INTERRUPTIBLE);
95                         spin_unlock_irq(rq->queue_lock);
96                         schedule();
97                         spin_lock_irq(rq->queue_lock);
98                         continue;
99                 }
100
101                 dev = req->rq_disk->private_data;
102                 tr = dev->tr;
103
104                 spin_unlock_irq(rq->queue_lock);
105
106                 mutex_lock(&dev->lock);
107                 res = do_blktrans_request(tr, dev, req);
108                 mutex_unlock(&dev->lock);
109
110                 spin_lock_irq(rq->queue_lock);
111
112                 end_request(req, res);
113         }
114         spin_unlock_irq(rq->queue_lock);
115
116         return 0;
117 }
118
119 static void mtd_blktrans_request(struct request_queue *rq)
120 {
121         struct mtd_blktrans_ops *tr = rq->queuedata;
122         wake_up_process(tr->blkcore_priv->thread);
123 }
124
125
126 static int blktrans_open(struct inode *i, struct file *f)
127 {
128         struct mtd_blktrans_dev *dev;
129         struct mtd_blktrans_ops *tr;
130         int ret = -ENODEV;
131
132         dev = i->i_bdev->bd_disk->private_data;
133         tr = dev->tr;
134
135         if (!try_module_get(dev->mtd->owner))
136                 goto out;
137
138         if (!try_module_get(tr->owner))
139                 goto out_tr;
140
141         /* FIXME: Locking. A hot pluggable device can go away
142            (del_mtd_device can be called for it) without its module
143            being unloaded. */
144         dev->mtd->usecount++;
145
146         ret = 0;
147         if (tr->open && (ret = tr->open(dev))) {
148                 dev->mtd->usecount--;
149                 module_put(dev->mtd->owner);
150         out_tr:
151                 module_put(tr->owner);
152         }
153  out:
154         return ret;
155 }
156
157 static int blktrans_release(struct inode *i, struct file *f)
158 {
159         struct mtd_blktrans_dev *dev;
160         struct mtd_blktrans_ops *tr;
161         int ret = 0;
162
163         dev = i->i_bdev->bd_disk->private_data;
164         tr = dev->tr;
165
166         if (tr->release)
167                 ret = tr->release(dev);
168
169         if (!ret) {
170                 dev->mtd->usecount--;
171                 module_put(dev->mtd->owner);
172                 module_put(tr->owner);
173         }
174
175         return ret;
176 }
177
178 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
179 {
180         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
181
182         if (dev->tr->getgeo)
183                 return dev->tr->getgeo(dev, geo);
184         return -ENOTTY;
185 }
186
187 static int blktrans_ioctl(struct inode *inode, struct file *file,
188                               unsigned int cmd, unsigned long arg)
189 {
190         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
191         struct mtd_blktrans_ops *tr = dev->tr;
192
193         switch (cmd) {
194         case BLKFLSBUF:
195                 if (tr->flush)
196                         return tr->flush(dev);
197                 /* The core code did the work, we had nothing to do. */
198                 return 0;
199         default:
200                 return -ENOTTY;
201         }
202 }
203
204 struct block_device_operations mtd_blktrans_ops = {
205         .owner          = THIS_MODULE,
206         .open           = blktrans_open,
207         .release        = blktrans_release,
208         .ioctl          = blktrans_ioctl,
209         .getgeo         = blktrans_getgeo,
210 };
211
212 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
213 {
214         struct mtd_blktrans_ops *tr = new->tr;
215         struct list_head *this;
216         int last_devnum = -1;
217         struct gendisk *gd;
218
219         if (mutex_trylock(&mtd_table_mutex)) {
220                 mutex_unlock(&mtd_table_mutex);
221                 BUG();
222         }
223
224         list_for_each(this, &tr->devs) {
225                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
226                 if (new->devnum == -1) {
227                         /* Use first free number */
228                         if (d->devnum != last_devnum+1) {
229                                 /* Found a free devnum. Plug it in here */
230                                 new->devnum = last_devnum+1;
231                                 list_add_tail(&new->list, &d->list);
232                                 goto added;
233                         }
234                 } else if (d->devnum == new->devnum) {
235                         /* Required number taken */
236                         return -EBUSY;
237                 } else if (d->devnum > new->devnum) {
238                         /* Required number was free */
239                         list_add_tail(&new->list, &d->list);
240                         goto added;
241                 }
242                 last_devnum = d->devnum;
243         }
244         if (new->devnum == -1)
245                 new->devnum = last_devnum+1;
246
247         if ((new->devnum << tr->part_bits) > 256) {
248                 return -EBUSY;
249         }
250
251         mutex_init(&new->lock);
252         list_add_tail(&new->list, &tr->devs);
253  added:
254         if (!tr->writesect)
255                 new->readonly = 1;
256
257         gd = alloc_disk(1 << tr->part_bits);
258         if (!gd) {
259                 list_del(&new->list);
260                 return -ENOMEM;
261         }
262         gd->major = tr->major;
263         gd->first_minor = (new->devnum) << tr->part_bits;
264         gd->fops = &mtd_blktrans_ops;
265
266         if (tr->part_bits)
267                 if (new->devnum < 26)
268                         snprintf(gd->disk_name, sizeof(gd->disk_name),
269                                  "%s%c", tr->name, 'a' + new->devnum);
270                 else
271                         snprintf(gd->disk_name, sizeof(gd->disk_name),
272                                  "%s%c%c", tr->name,
273                                  'a' - 1 + new->devnum / 26,
274                                  'a' + new->devnum % 26);
275         else
276                 snprintf(gd->disk_name, sizeof(gd->disk_name),
277                          "%s%d", tr->name, new->devnum);
278
279         /* 2.5 has capacity in units of 512 bytes while still
280            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
281         set_capacity(gd, (new->size * tr->blksize) >> 9);
282
283         gd->private_data = new;
284         new->blkcore_priv = gd;
285         gd->queue = tr->blkcore_priv->rq;
286
287         if (new->readonly)
288                 set_disk_ro(gd, 1);
289
290         add_disk(gd);
291
292         return 0;
293 }
294
295 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
296 {
297         if (mutex_trylock(&mtd_table_mutex)) {
298                 mutex_unlock(&mtd_table_mutex);
299                 BUG();
300         }
301
302         list_del(&old->list);
303
304         del_gendisk(old->blkcore_priv);
305         put_disk(old->blkcore_priv);
306
307         return 0;
308 }
309
310 static void blktrans_notify_remove(struct mtd_info *mtd)
311 {
312         struct list_head *this, *this2, *next;
313
314         list_for_each(this, &blktrans_majors) {
315                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
316
317                 list_for_each_safe(this2, next, &tr->devs) {
318                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
319
320                         if (dev->mtd == mtd)
321                                 tr->remove_dev(dev);
322                 }
323         }
324 }
325
326 static void blktrans_notify_add(struct mtd_info *mtd)
327 {
328         struct list_head *this;
329
330         if (mtd->type == MTD_ABSENT)
331                 return;
332
333         list_for_each(this, &blktrans_majors) {
334                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
335
336                 tr->add_mtd(tr, mtd);
337         }
338
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_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
382         tr->blkshift = ffs(tr->blksize) - 1;
383
384         tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
385                         "%sd", tr->name);
386         if (IS_ERR(tr->blkcore_priv->thread)) {
387                 blk_cleanup_queue(tr->blkcore_priv->rq);
388                 unregister_blkdev(tr->major, tr->name);
389                 kfree(tr->blkcore_priv);
390                 mutex_unlock(&mtd_table_mutex);
391                 return PTR_ERR(tr->blkcore_priv->thread);
392         }
393
394         INIT_LIST_HEAD(&tr->devs);
395         list_add(&tr->list, &blktrans_majors);
396
397         for (i=0; i<MAX_MTD_DEVICES; i++) {
398                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
399                         tr->add_mtd(tr, mtd_table[i]);
400         }
401
402         mutex_unlock(&mtd_table_mutex);
403
404         return 0;
405 }
406
407 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
408 {
409         struct list_head *this, *next;
410
411         mutex_lock(&mtd_table_mutex);
412
413         /* Clean up the kernel thread */
414         kthread_stop(tr->blkcore_priv->thread);
415
416         /* Remove it from the list of active majors */
417         list_del(&tr->list);
418
419         list_for_each_safe(this, next, &tr->devs) {
420                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
421                 tr->remove_dev(dev);
422         }
423
424         blk_cleanup_queue(tr->blkcore_priv->rq);
425         unregister_blkdev(tr->major, tr->name);
426
427         mutex_unlock(&mtd_table_mutex);
428
429         kfree(tr->blkcore_priv);
430
431         BUG_ON(!list_empty(&tr->devs));
432         return 0;
433 }
434
435 static void __exit mtd_blktrans_exit(void)
436 {
437         /* No race here -- if someone's currently in register_mtd_blktrans
438            we're screwed anyway. */
439         if (blktrans_notifier.list.next)
440                 unregister_mtd_user(&blktrans_notifier);
441 }
442
443 module_exit(mtd_blktrans_exit);
444
445 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
446 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
447 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
448 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
449
450 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
451 MODULE_LICENSE("GPL");
452 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");