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/spinlock.h>
  18 #include <linux/hdreg.h>
  19 #include <linux/init.h>
  20 #include <linux/mutex.h>
  21 #include <linux/kthread.h>
  22 #include <asm/uaccess.h>
  23
  24 #include "mtdcore.h"
  25
  26 static LIST_HEAD(blktrans_majors);
  27 static DEFINE_MUTEX(blktrans_ref_mutex);
  28
  29 void blktrans_dev_release(struct kref *kref)
  30 {
  31         struct mtd_blktrans_dev *dev =
  32                 container_of(kref, struct mtd_blktrans_dev, ref);
  33
  34         dev->disk->private_data = NULL;
  35         put_disk(dev->disk);
  36         list_del(&dev->list);
  37         kfree(dev);
  38 }
  39
  40 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  41 {
  42         struct mtd_blktrans_dev *dev;
  43
  44         mutex_lock(&blktrans_ref_mutex);
  45         dev = disk->private_data;
  46
  47         if (!dev)
  48                 goto unlock;
  49         kref_get(&dev->ref);
  50 unlock:
  51         mutex_unlock(&blktrans_ref_mutex);
  52         return dev;
  53 }
  54
  55 void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  56 {
  57         mutex_lock(&blktrans_ref_mutex);
  58         kref_put(&dev->ref, blktrans_dev_release);
  59         mutex_unlock(&blktrans_ref_mutex);
  60 }
  61
  62
  63 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  64                                struct mtd_blktrans_dev *dev,
  65                                struct request *req)
  66 {
  67         unsigned long block, nsect;
  68         char *buf;
  69
  70         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  71         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  72
  73         buf = req->buffer;
  74
  75         if (!blk_fs_request(req))
  76                 return -EIO;
  77
  78         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  79             get_capacity(req->rq_disk))
  80                 return -EIO;
  81
  82         if (blk_discard_rq(req))
  83                 return tr->discard(dev, block, nsect);
  84
  85         switch(rq_data_dir(req)) {
  86         case READ:
  87                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  88                         if (tr->readsect(dev, block, buf))
  89                                 return -EIO;
  90                 rq_flush_dcache_pages(req);
  91                 return 0;
  92         case WRITE:
  93                 if (!tr->writesect)
  94                         return -EIO;
  95
  96                 rq_flush_dcache_pages(req);
  97                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  98                         if (tr->writesect(dev, block, buf))
  99                                 return -EIO;
 100                 return 0;
 101         default:
 102                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
 103                 return -EIO;
 104         }
 105 }
 106
 107 static int mtd_blktrans_thread(void *arg)
 108 {
 109         struct mtd_blktrans_dev *dev = arg;
 110         struct request_queue *rq = dev->rq;
 111         struct request *req = NULL;
 112
 113         spin_lock_irq(rq->queue_lock);
 114
 115         while (!kthread_should_stop()) {
 116                 int res;
 117
 118                 if (!req && !(req = blk_fetch_request(rq))) {
 119                         set_current_state(TASK_INTERRUPTIBLE);
 120                         spin_unlock_irq(rq->queue_lock);
 121                         schedule();
 122                         spin_lock_irq(rq->queue_lock);
 123                         continue;
 124                 }
 125
 126                 spin_unlock_irq(rq->queue_lock);
 127
 128                 mutex_lock(&dev->lock);
 129                 res = do_blktrans_request(dev->tr, dev, req);
 130                 mutex_unlock(&dev->lock);
 131
 132                 spin_lock_irq(rq->queue_lock);
 133
 134                 if (!__blk_end_request_cur(req, res))
 135                         req = NULL;
 136         }
 137
 138         if (req)
 139                 __blk_end_request_all(req, -EIO);
 140
 141         spin_unlock_irq(rq->queue_lock);
 142
 143         return 0;
 144 }
 145
 146 static void mtd_blktrans_request(struct request_queue *rq)
 147 {
 148         struct mtd_blktrans_dev *dev;
 149         struct request *req = NULL;
 150
 151         dev = rq->queuedata;
 152
 153         if (!dev)
 154                 while ((req = blk_fetch_request(rq)) != NULL)
 155                         __blk_end_request_all(req, -ENODEV);
 156         else
 157                 wake_up_process(dev->thread);
 158 }
 159
 160 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 161 {
 162         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 163         int ret;
 164
 165         if (!dev)
 166                 return -ERESTARTSYS;
 167
 168         mutex_lock(&dev->lock);
 169
 170         if (!dev->mtd) {
 171                 ret = -ENXIO;
 172                 goto unlock;
 173         }
 174
 175         ret = !dev->open++ && dev->tr->open ? dev->tr->open(dev) : 0;
 176
 177         /* Take another reference on the device so it won't go away till
 178                 last release */
 179         if (!ret)
 180                 kref_get(&dev->ref);
 181 unlock:
 182         mutex_unlock(&dev->lock);
 183         blktrans_dev_put(dev);
 184         return ret;
 185 }
 186
 187 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 188 {
 189         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 190         int ret = -ENXIO;
 191
 192         if (!dev)
 193                 return ret;
 194
 195         mutex_lock(&dev->lock);
 196
 197         /* Release one reference, we sure its not the last one here*/
 198         kref_put(&dev->ref, blktrans_dev_release);
 199
 200         if (!dev->mtd)
 201                 goto unlock;
 202
 203         ret = !--dev->open && dev->tr->release ? dev->tr->release(dev) : 0;
 204 unlock:
 205         mutex_unlock(&dev->lock);
 206         blktrans_dev_put(dev);
 207         return ret;
 208 }
 209
 210 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 211 {
 212         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 213         int ret = -ENXIO;
 214
 215         if (!dev)
 216                 return ret;
 217
 218         mutex_lock(&dev->lock);
 219
 220         if (!dev->mtd)
 221                 goto unlock;
 222
 223         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 224 unlock:
 225         mutex_unlock(&dev->lock);
 226         blktrans_dev_put(dev);
 227         return ret;
 228 }
 229
 230 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 231                               unsigned int cmd, unsigned long arg)
 232 {
 233         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 234         int ret = -ENXIO;
 235
 236         if (!dev)
 237                 return ret;
 238
 239         mutex_lock(&dev->lock);
 240
 241         if (!dev->mtd)
 242                 goto unlock;
 243
 244         switch (cmd) {
 245         case BLKFLSBUF:
 246                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 247         default:
 248                 ret = -ENOTTY;
 249         }
 250 unlock:
 251         mutex_unlock(&dev->lock);
 252         blktrans_dev_put(dev);
 253         return ret;
 254 }
 255
 256 static const struct block_device_operations mtd_blktrans_ops = {
 257         .owner          = THIS_MODULE,
 258         .open           = blktrans_open,
 259         .release        = blktrans_release,
 260         .locked_ioctl   = blktrans_ioctl,
 261         .getgeo         = blktrans_getgeo,
 262 };
 263
 264 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 265 {
 266         struct mtd_blktrans_ops *tr = new->tr;
 267         struct mtd_blktrans_dev *d;
 268         int last_devnum = -1;
 269         struct gendisk *gd;
 270         int ret;
 271
 272         if (mutex_trylock(&mtd_table_mutex)) {
 273                 mutex_unlock(&mtd_table_mutex);
 274                 BUG();
 275         }
 276
 277         mutex_lock(&blktrans_ref_mutex);
 278         list_for_each_entry(d, &tr->devs, list) {
 279                 if (new->devnum == -1) {
 280                         /* Use first free number */
 281                         if (d->devnum != last_devnum+1) {
 282                                 /* Found a free devnum. Plug it in here */
 283                                 new->devnum = last_devnum+1;
 284                                 list_add_tail(&new->list, &d->list);
 285                                 goto added;
 286                         }
 287                 } else if (d->devnum == new->devnum) {
 288                         /* Required number taken */
 289                         mutex_unlock(&blktrans_ref_mutex);
 290                         return -EBUSY;
 291                 } else if (d->devnum > new->devnum) {
 292                         /* Required number was free */
 293                         list_add_tail(&new->list, &d->list);
 294                         goto added;
 295                 }
 296                 last_devnum = d->devnum;
 297         }
 298
 299         ret = -EBUSY;
 300         if (new->devnum == -1)
 301                 new->devnum = last_devnum+1;
 302
 303         /* Check that the device and any partitions will get valid
 304          * minor numbers and that the disk naming code below can cope
 305          * with this number. */
 306         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 307             (tr->part_bits && new->devnum >= 27 * 26)) {
 308                 mutex_unlock(&blktrans_ref_mutex);
 309                 goto error1;
 310         }
 311
 312         list_add_tail(&new->list, &tr->devs);
 313  added:
 314         mutex_unlock(&blktrans_ref_mutex);
 315
 316         mutex_init(&new->lock);
 317         kref_init(&new->ref);
 318         if (!tr->writesect)
 319                 new->readonly = 1;
 320
 321         /* Create gendisk */
 322         ret = -ENOMEM;
 323         gd = alloc_disk(1 << tr->part_bits);
 324
 325         if (!gd)
 326                 goto error2;
 327
 328         new->disk = gd;
 329         gd->private_data = new;
 330         gd->major = tr->major;
 331         gd->first_minor = (new->devnum) << tr->part_bits;
 332         gd->fops = &mtd_blktrans_ops;
 333
 334         if (tr->part_bits)
 335                 if (new->devnum < 26)
 336                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 337                                  "%s%c", tr->name, 'a' + new->devnum);
 338                 else
 339                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 340                                  "%s%c%c", tr->name,
 341                                  'a' - 1 + new->devnum / 26,
 342                                  'a' + new->devnum % 26);
 343         else
 344                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 345                          "%s%d", tr->name, new->devnum);
 346
 347         set_capacity(gd, (new->size * tr->blksize) >> 9);
 348
 349         /* Create the request queue */
 350         spin_lock_init(&new->queue_lock);
 351         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 352
 353         if (!new->rq)
 354                 goto error3;
 355
 356         new->rq->queuedata = new;
 357         blk_queue_logical_block_size(new->rq, tr->blksize);
 358
 359         if (tr->discard)
 360                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 361                                         new->rq);
 362
 363         gd->queue = new->rq;
 364
 365         __get_mtd_device(new->mtd);
 366         __module_get(tr->owner);
 367
 368         /* Create processing thread */
 369         /* TODO: workqueue ? */
 370         new->thread = kthread_run(mtd_blktrans_thread, new,
 371                         "%s%d", tr->name, new->mtd->index);
 372         if (IS_ERR(new->thread)) {
 373                 ret = PTR_ERR(new->thread);
 374                 goto error4;
 375         }
 376         gd->driverfs_dev = &new->mtd->dev;
 377
 378         if (new->readonly)
 379                 set_disk_ro(gd, 1);
 380
 381         add_disk(gd);
 382         return 0;
 383 error4:
 384         module_put(tr->owner);
 385         __put_mtd_device(new->mtd);
 386         blk_cleanup_queue(new->rq);
 387 error3:
 388         put_disk(new->disk);
 389 error2:
 390         list_del(&new->list);
 391 error1:
 392         kfree(new);
 393         return ret;
 394 }
 395
 396 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 397 {
 398         unsigned long flags;
 399
 400         if (mutex_trylock(&mtd_table_mutex)) {
 401                 mutex_unlock(&mtd_table_mutex);
 402                 BUG();
 403         }
 404
 405         /* Stop new requests to arrive */
 406         del_gendisk(old->disk);
 407
 408         /* Stop the thread */
 409         kthread_stop(old->thread);
 410
 411         /* Kill current requests */
 412         spin_lock_irqsave(&old->queue_lock, flags);
 413         old->rq->queuedata = NULL;
 414         blk_start_queue(old->rq);
 415         spin_unlock_irqrestore(&old->queue_lock, flags);
 416         blk_cleanup_queue(old->rq);
 417
 418         /* Ask trans driver for release to the mtd device */
 419         mutex_lock(&old->lock);
 420         if (old->open && old->tr->release) {
 421                 old->tr->release(old);
 422                 old->open = 0;
 423         }
 424
 425         __put_mtd_device(old->mtd);
 426         module_put(old->tr->owner);
 427
 428         /* At that point, we don't touch the mtd anymore */
 429         old->mtd = NULL;
 430
 431         mutex_unlock(&old->lock);
 432         blktrans_dev_put(old);
 433         return 0;
 434 }
 435
 436 static void blktrans_notify_remove(struct mtd_info *mtd)
 437 {
 438         struct mtd_blktrans_ops *tr;
 439         struct mtd_blktrans_dev *dev, *next;
 440
 441         list_for_each_entry(tr, &blktrans_majors, list)
 442                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 443                         if (dev->mtd == mtd)
 444                                 tr->remove_dev(dev);
 445 }
 446
 447 static void blktrans_notify_add(struct mtd_info *mtd)
 448 {
 449         struct mtd_blktrans_ops *tr;
 450
 451         if (mtd->type == MTD_ABSENT)
 452                 return;
 453
 454         list_for_each_entry(tr, &blktrans_majors, list)
 455                 tr->add_mtd(tr, mtd);
 456 }
 457
 458 static struct mtd_notifier blktrans_notifier = {
 459         .add = blktrans_notify_add,
 460         .remove = blktrans_notify_remove,
 461 };
 462
 463 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 464 {
 465         struct mtd_info *mtd;
 466         int ret;
 467
 468         /* Register the notifier if/when the first device type is
 469            registered, to prevent the link/init ordering from fucking
 470            us over. */
 471         if (!blktrans_notifier.list.next)
 472                 register_mtd_user(&blktrans_notifier);
 473
 474
 475         mutex_lock(&mtd_table_mutex);
 476
 477         ret = register_blkdev(tr->major, tr->name);
 478         if (ret) {
 479                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 480                        tr->name, tr->major, ret);
 481                 mutex_unlock(&mtd_table_mutex);
 482                 return ret;
 483         }
 484
 485         tr->blkshift = ffs(tr->blksize) - 1;
 486
 487         INIT_LIST_HEAD(&tr->devs);
 488         list_add(&tr->list, &blktrans_majors);
 489
 490         mtd_for_each_device(mtd)
 491                 if (mtd->type != MTD_ABSENT)
 492                         tr->add_mtd(tr, mtd);
 493
 494         mutex_unlock(&mtd_table_mutex);
 495         return 0;
 496 }
 497
 498 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 499 {
 500         struct mtd_blktrans_dev *dev, *next;
 501
 502         mutex_lock(&mtd_table_mutex);
 503
 504         /* Remove it from the list of active majors */
 505         list_del(&tr->list);
 506
 507         list_for_each_entry_safe(dev, next, &tr->devs, list)
 508                 tr->remove_dev(dev);
 509
 510         unregister_blkdev(tr->major, tr->name);
 511         mutex_unlock(&mtd_table_mutex);
 512
 513         BUG_ON(!list_empty(&tr->devs));
 514         return 0;
 515 }
 516
 517 static void __exit mtd_blktrans_exit(void)
 518 {
 519         /* No race here -- if someone's currently in register_mtd_blktrans
 520            we're screwed anyway. */
 521         if (blktrans_notifier.list.next)
 522                 unregister_mtd_user(&blktrans_notifier);
 523 }
 524
 525 module_exit(mtd_blktrans_exit);
 526
 527 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 528 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 529 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 530 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 531
 532 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 533 MODULE_LICENSE("GPL");
 534 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");