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                 return 0;
  63
  64         case WRITE:
  65                 if (!tr->writesect)
  66                         return -EIO;
  67
  68                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  69                         if (tr->writesect(dev, block, buf))
  70                                 return -EIO;
  71                 return 0;
  72
  73         default:
  74                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
  75                 return -EIO;
  76         }
  77 }
  78
  79 static int mtd_blktrans_thread(void *arg)
  80 {
  81         struct mtd_blktrans_ops *tr = arg;
  82         struct request_queue *rq = tr->blkcore_priv->rq;
  83         struct request *req = NULL;
  84
  85         /* we might get involved when memory gets low, so use PF_MEMALLOC */
  86         current->flags |= PF_MEMALLOC;
  87
  88         spin_lock_irq(rq->queue_lock);
  89
  90         while (!kthread_should_stop()) {
  91                 struct mtd_blktrans_dev *dev;
  92                 int res;
  93
  94                 if (!req && !(req = blk_fetch_request(rq))) {
  95                         set_current_state(TASK_INTERRUPTIBLE);
  96                         spin_unlock_irq(rq->queue_lock);
  97                         schedule();
  98                         spin_lock_irq(rq->queue_lock);
  99                         continue;
 100                 }
 101
 102                 dev = req->rq_disk->private_data;
 103                 tr = dev->tr;
 104
 105                 spin_unlock_irq(rq->queue_lock);
 106
 107                 mutex_lock(&dev->lock);
 108                 res = do_blktrans_request(tr, dev, req);
 109                 mutex_unlock(&dev->lock);
 110
 111                 spin_lock_irq(rq->queue_lock);
 112
 113                 if (!__blk_end_request_cur(req, res))
 114                         req = NULL;
 115         }
 116
 117         if (req)
 118                 __blk_end_request_all(req, -EIO);
 119
 120         spin_unlock_irq(rq->queue_lock);
 121
 122         return 0;
 123 }
 124
 125 static void mtd_blktrans_request(struct request_queue *rq)
 126 {
 127         struct mtd_blktrans_ops *tr = rq->queuedata;
 128         wake_up_process(tr->blkcore_priv->thread);
 129 }
 130
 131
 132 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 133 {
 134         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 135         struct mtd_blktrans_ops *tr = dev->tr;
 136         int ret = -ENODEV;
 137
 138         if (!get_mtd_device(NULL, dev->mtd->index))
 139                 goto out;
 140
 141         if (!try_module_get(tr->owner))
 142                 goto out_tr;
 143
 144         /* FIXME: Locking. A hot pluggable device can go away
 145            (del_mtd_device can be called for it) without its module
 146            being unloaded. */
 147         dev->mtd->usecount++;
 148
 149         ret = 0;
 150         if (tr->open && (ret = tr->open(dev))) {
 151                 dev->mtd->usecount--;
 152                 put_mtd_device(dev->mtd);
 153         out_tr:
 154                 module_put(tr->owner);
 155         }
 156  out:
 157         return ret;
 158 }
 159
 160 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 161 {
 162         struct mtd_blktrans_dev *dev = disk->private_data;
 163         struct mtd_blktrans_ops *tr = dev->tr;
 164         int ret = 0;
 165
 166         if (tr->release)
 167                 ret = tr->release(dev);
 168
 169         if (!ret) {
 170                 dev->mtd->usecount--;
 171                 put_mtd_device(dev->mtd);
 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 block_device *bdev, fmode_t mode,
 188                               unsigned int cmd, unsigned long arg)
 189 {
 190         struct mtd_blktrans_dev *dev = 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 static const struct block_device_operations mtd_blktrans_ops = {
 205         .owner          = THIS_MODULE,
 206         .open           = blktrans_open,
 207         .release        = blktrans_release,
 208         .locked_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 mtd_blktrans_dev *d;
 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_entry(d, &tr->devs, list) {
 225                 if (new->devnum == -1) {
 226                         /* Use first free number */
 227                         if (d->devnum != last_devnum+1) {
 228                                 /* Found a free devnum. Plug it in here */
 229                                 new->devnum = last_devnum+1;
 230                                 list_add_tail(&new->list, &d->list);
 231                                 goto added;
 232                         }
 233                 } else if (d->devnum == new->devnum) {
 234                         /* Required number taken */
 235                         return -EBUSY;
 236                 } else if (d->devnum > new->devnum) {
 237                         /* Required number was free */
 238                         list_add_tail(&new->list, &d->list);
 239                         goto added;
 240                 }
 241                 last_devnum = d->devnum;
 242         }
 243         if (new->devnum == -1)
 244                 new->devnum = last_devnum+1;
 245
 246         if ((new->devnum << tr->part_bits) > 256) {
 247                 return -EBUSY;
 248         }
 249
 250         list_add_tail(&new->list, &tr->devs);
 251  added:
 252         mutex_init(&new->lock);
 253         if (!tr->writesect)
 254                 new->readonly = 1;
 255
 256         gd = alloc_disk(1 << tr->part_bits);
 257         if (!gd) {
 258                 list_del(&new->list);
 259                 return -ENOMEM;
 260         }
 261         gd->major = tr->major;
 262         gd->first_minor = (new->devnum) << tr->part_bits;
 263         gd->fops = &mtd_blktrans_ops;
 264
 265         if (tr->part_bits)
 266                 if (new->devnum < 26)
 267                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 268                                  "%s%c", tr->name, 'a' + new->devnum);
 269                 else
 270                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 271                                  "%s%c%c", tr->name,
 272                                  'a' - 1 + new->devnum / 26,
 273                                  'a' + new->devnum % 26);
 274         else
 275                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 276                          "%s%d", tr->name, new->devnum);
 277
 278         /* 2.5 has capacity in units of 512 bytes while still
 279            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
 280         set_capacity(gd, (new->size * tr->blksize) >> 9);
 281
 282         gd->private_data = new;
 283         new->blkcore_priv = gd;
 284         gd->queue = tr->blkcore_priv->rq;
 285         gd->driverfs_dev = &new->mtd->dev;
 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 mtd_blktrans_ops *tr;
 313         struct mtd_blktrans_dev *dev, *next;
 314
 315         list_for_each_entry(tr, &blktrans_majors, list)
 316                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 317                         if (dev->mtd == mtd)
 318                                 tr->remove_dev(dev);
 319 }
 320
 321 static void blktrans_notify_add(struct mtd_info *mtd)
 322 {
 323         struct mtd_blktrans_ops *tr;
 324
 325         if (mtd->type == MTD_ABSENT)
 326                 return;
 327
 328         list_for_each_entry(tr, &blktrans_majors, list)
 329                 tr->add_mtd(tr, mtd);
 330 }
 331
 332 static struct mtd_notifier blktrans_notifier = {
 333         .add = blktrans_notify_add,
 334         .remove = blktrans_notify_remove,
 335 };
 336
 337 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 338 {
 339         int ret, i;
 340
 341         /* Register the notifier if/when the first device type is
 342            registered, to prevent the link/init ordering from fucking
 343            us over. */
 344         if (!blktrans_notifier.list.next)
 345                 register_mtd_user(&blktrans_notifier);
 346
 347         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 348         if (!tr->blkcore_priv)
 349                 return -ENOMEM;
 350
 351         mutex_lock(&mtd_table_mutex);
 352
 353         ret = register_blkdev(tr->major, tr->name);
 354         if (ret) {
 355                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 356                        tr->name, tr->major, ret);
 357                 kfree(tr->blkcore_priv);
 358                 mutex_unlock(&mtd_table_mutex);
 359                 return ret;
 360         }
 361         spin_lock_init(&tr->blkcore_priv->queue_lock);
 362
 363         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 364         if (!tr->blkcore_priv->rq) {
 365                 unregister_blkdev(tr->major, tr->name);
 366                 kfree(tr->blkcore_priv);
 367                 mutex_unlock(&mtd_table_mutex);
 368                 return -ENOMEM;
 369         }
 370
 371         tr->blkcore_priv->rq->queuedata = tr;
 372         blk_queue_logical_block_size(tr->blkcore_priv->rq, tr->blksize);
 373         if (tr->discard)
 374                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 375                                         tr->blkcore_priv->rq);
 376
 377         tr->blkshift = ffs(tr->blksize) - 1;
 378
 379         tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
 380                         "%sd", tr->name);
 381         if (IS_ERR(tr->blkcore_priv->thread)) {
 382                 int ret = PTR_ERR(tr->blkcore_priv->thread);
 383                 blk_cleanup_queue(tr->blkcore_priv->rq);
 384                 unregister_blkdev(tr->major, tr->name);
 385                 kfree(tr->blkcore_priv);
 386                 mutex_unlock(&mtd_table_mutex);
 387                 return ret;
 388         }
 389
 390         INIT_LIST_HEAD(&tr->devs);
 391         list_add(&tr->list, &blktrans_majors);
 392
 393         for (i=0; i<MAX_MTD_DEVICES; i++) {
 394                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 395                         tr->add_mtd(tr, mtd_table[i]);
 396         }
 397
 398         mutex_unlock(&mtd_table_mutex);
 399
 400         return 0;
 401 }
 402
 403 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 404 {
 405         struct mtd_blktrans_dev *dev, *next;
 406
 407         mutex_lock(&mtd_table_mutex);
 408
 409         /* Clean up the kernel thread */
 410         kthread_stop(tr->blkcore_priv->thread);
 411
 412         /* Remove it from the list of active majors */
 413         list_del(&tr->list);
 414
 415         list_for_each_entry_safe(dev, next, &tr->devs, list)
 416                 tr->remove_dev(dev);
 417
 418         blk_cleanup_queue(tr->blkcore_priv->rq);
 419         unregister_blkdev(tr->major, tr->name);
 420
 421         mutex_unlock(&mtd_table_mutex);
 422
 423         kfree(tr->blkcore_priv);
 424
 425         BUG_ON(!list_empty(&tr->devs));
 426         return 0;
 427 }
 428
 429 static void __exit mtd_blktrans_exit(void)
 430 {
 431         /* No race here -- if someone's currently in register_mtd_blktrans
 432            we're screwed anyway. */
 433         if (blktrans_notifier.list.next)
 434                 unregister_mtd_user(&blktrans_notifier);
 435 }
 436
 437 module_exit(mtd_blktrans_exit);
 438
 439 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 440 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 441 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 442 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 443
 444 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 445 MODULE_LICENSE("GPL");
 446 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");