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   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'");