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         blk_cleanup_queue(dev->rq);
  36         put_disk(dev->disk);
  37         list_del(&dev->list);
  38         kfree(dev);
  39 }
  40
  41 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  42 {
  43         struct mtd_blktrans_dev *dev;
  44
  45         mutex_lock(&blktrans_ref_mutex);
  46         dev = disk->private_data;
  47
  48         if (!dev)
  49                 goto unlock;
  50         kref_get(&dev->ref);
  51 unlock:
  52         mutex_unlock(&blktrans_ref_mutex);
  53         return dev;
  54 }
  55
  56 void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  57 {
  58         mutex_lock(&blktrans_ref_mutex);
  59         kref_put(&dev->ref, blktrans_dev_release);
  60         mutex_unlock(&blktrans_ref_mutex);
  61 }
  62
  63
  64 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  65                                struct mtd_blktrans_dev *dev,
  66                                struct request *req)
  67 {
  68         unsigned long block, nsect;
  69         char *buf;
  70
  71         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  72         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  73
  74         buf = req->buffer;
  75
  76         if (!blk_fs_request(req))
  77                 return -EIO;
  78
  79         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  80             get_capacity(req->rq_disk))
  81                 return -EIO;
  82
  83         if (blk_discard_rq(req))
  84                 return tr->discard(dev, block, nsect);
  85
  86         switch(rq_data_dir(req)) {
  87         case READ:
  88                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  89                         if (tr->readsect(dev, block, buf))
  90                                 return -EIO;
  91                 rq_flush_dcache_pages(req);
  92                 return 0;
  93         case WRITE:
  94                 if (!tr->writesect)
  95                         return -EIO;
  96
  97                 rq_flush_dcache_pages(req);
  98                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  99                         if (tr->writesect(dev, block, buf))
 100                                 return -EIO;
 101                 return 0;
 102         default:
 103                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
 104                 return -EIO;
 105         }
 106 }
 107
 108 static int mtd_blktrans_thread(void *arg)
 109 {
 110         struct mtd_blktrans_dev *dev = arg;
 111         struct request_queue *rq = dev->rq;
 112         struct request *req = NULL;
 113
 114         spin_lock_irq(rq->queue_lock);
 115
 116         while (!kthread_should_stop()) {
 117                 int res;
 118
 119                 if (!req && !(req = blk_fetch_request(rq))) {
 120                         set_current_state(TASK_INTERRUPTIBLE);
 121                         spin_unlock_irq(rq->queue_lock);
 122                         schedule();
 123                         spin_lock_irq(rq->queue_lock);
 124                         continue;
 125                 }
 126
 127                 spin_unlock_irq(rq->queue_lock);
 128
 129                 mutex_lock(&dev->lock);
 130                 res = do_blktrans_request(dev->tr, dev, req);
 131                 mutex_unlock(&dev->lock);
 132
 133                 spin_lock_irq(rq->queue_lock);
 134
 135                 if (!__blk_end_request_cur(req, res))
 136                         req = NULL;
 137         }
 138
 139         if (req)
 140                 __blk_end_request_all(req, -EIO);
 141
 142         spin_unlock_irq(rq->queue_lock);
 143
 144         return 0;
 145 }
 146
 147 static void mtd_blktrans_request(struct request_queue *rq)
 148 {
 149         struct mtd_blktrans_dev *dev;
 150         struct request *req = NULL;
 151
 152         dev = rq->queuedata;
 153
 154         if (!dev)
 155                 while ((req = blk_fetch_request(rq)) != NULL)
 156                         __blk_end_request_all(req, -ENODEV);
 157         else
 158                 wake_up_process(dev->thread);
 159 }
 160
 161 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 162 {
 163         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 164         int ret;
 165
 166         if (!dev)
 167                 return -ERESTARTSYS;
 168
 169         mutex_lock(&dev->lock);
 170
 171         if (!dev->mtd) {
 172                 ret = -ENXIO;
 173                 goto unlock;
 174         }
 175
 176         ret = !dev->open++ && dev->tr->open ? dev->tr->open(dev) : 0;
 177
 178         /* Take another reference on the device so it won't go away till
 179                 last release */
 180         if (!ret)
 181                 kref_get(&dev->ref);
 182 unlock:
 183         mutex_unlock(&dev->lock);
 184         blktrans_dev_put(dev);
 185         return ret;
 186 }
 187
 188 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 189 {
 190         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 191         int ret = -ENXIO;
 192
 193         if (!dev)
 194                 return ret;
 195
 196         mutex_lock(&dev->lock);
 197
 198         /* Release one reference, we sure its not the last one here*/
 199         kref_put(&dev->ref, blktrans_dev_release);
 200
 201         if (!dev->mtd)
 202                 goto unlock;
 203
 204         ret = !--dev->open && dev->tr->release ? dev->tr->release(dev) : 0;
 205 unlock:
 206         mutex_unlock(&dev->lock);
 207         blktrans_dev_put(dev);
 208         return ret;
 209 }
 210
 211 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 212 {
 213         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 214         int ret = -ENXIO;
 215
 216         if (!dev)
 217                 return ret;
 218
 219         mutex_lock(&dev->lock);
 220
 221         if (!dev->mtd)
 222                 goto unlock;
 223
 224         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 225 unlock:
 226         mutex_unlock(&dev->lock);
 227         blktrans_dev_put(dev);
 228         return ret;
 229 }
 230
 231 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 232                               unsigned int cmd, unsigned long arg)
 233 {
 234         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 235         int ret = -ENXIO;
 236
 237         if (!dev)
 238                 return ret;
 239
 240         mutex_lock(&dev->lock);
 241
 242         if (!dev->mtd)
 243                 goto unlock;
 244
 245         switch (cmd) {
 246         case BLKFLSBUF:
 247                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 248                 break;
 249         default:
 250                 ret = -ENOTTY;
 251         }
 252 unlock:
 253         mutex_unlock(&dev->lock);
 254         blktrans_dev_put(dev);
 255         return ret;
 256 }
 257
 258 static const struct block_device_operations mtd_blktrans_ops = {
 259         .owner          = THIS_MODULE,
 260         .open           = blktrans_open,
 261         .release        = blktrans_release,
 262         .locked_ioctl   = blktrans_ioctl,
 263         .getgeo         = blktrans_getgeo,
 264 };
 265
 266 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 267 {
 268         struct mtd_blktrans_ops *tr = new->tr;
 269         struct mtd_blktrans_dev *d;
 270         int last_devnum = -1;
 271         struct gendisk *gd;
 272         int ret;
 273
 274         if (mutex_trylock(&mtd_table_mutex)) {
 275                 mutex_unlock(&mtd_table_mutex);
 276                 BUG();
 277         }
 278
 279         mutex_lock(&blktrans_ref_mutex);
 280         list_for_each_entry(d, &tr->devs, list) {
 281                 if (new->devnum == -1) {
 282                         /* Use first free number */
 283                         if (d->devnum != last_devnum+1) {
 284                                 /* Found a free devnum. Plug it in here */
 285                                 new->devnum = last_devnum+1;
 286                                 list_add_tail(&new->list, &d->list);
 287                                 goto added;
 288                         }
 289                 } else if (d->devnum == new->devnum) {
 290                         /* Required number taken */
 291                         mutex_unlock(&blktrans_ref_mutex);
 292                         return -EBUSY;
 293                 } else if (d->devnum > new->devnum) {
 294                         /* Required number was free */
 295                         list_add_tail(&new->list, &d->list);
 296                         goto added;
 297                 }
 298                 last_devnum = d->devnum;
 299         }
 300
 301         ret = -EBUSY;
 302         if (new->devnum == -1)
 303                 new->devnum = last_devnum+1;
 304
 305         /* Check that the device and any partitions will get valid
 306          * minor numbers and that the disk naming code below can cope
 307          * with this number. */
 308         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 309             (tr->part_bits && new->devnum >= 27 * 26)) {
 310                 mutex_unlock(&blktrans_ref_mutex);
 311                 goto error1;
 312         }
 313
 314         list_add_tail(&new->list, &tr->devs);
 315  added:
 316         mutex_unlock(&blktrans_ref_mutex);
 317
 318         mutex_init(&new->lock);
 319         kref_init(&new->ref);
 320         if (!tr->writesect)
 321                 new->readonly = 1;
 322
 323         /* Create gendisk */
 324         ret = -ENOMEM;
 325         gd = alloc_disk(1 << tr->part_bits);
 326
 327         if (!gd)
 328                 goto error2;
 329
 330         new->disk = gd;
 331         gd->private_data = new;
 332         gd->major = tr->major;
 333         gd->first_minor = (new->devnum) << tr->part_bits;
 334         gd->fops = &mtd_blktrans_ops;
 335
 336         if (tr->part_bits)
 337                 if (new->devnum < 26)
 338                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 339                                  "%s%c", tr->name, 'a' + new->devnum);
 340                 else
 341                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 342                                  "%s%c%c", tr->name,
 343                                  'a' - 1 + new->devnum / 26,
 344                                  'a' + new->devnum % 26);
 345         else
 346                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 347                          "%s%d", tr->name, new->devnum);
 348
 349         set_capacity(gd, (new->size * tr->blksize) >> 9);
 350
 351         /* Create the request queue */
 352         spin_lock_init(&new->queue_lock);
 353         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 354
 355         if (!new->rq)
 356                 goto error3;
 357
 358         new->rq->queuedata = new;
 359         blk_queue_logical_block_size(new->rq, tr->blksize);
 360
 361         if (tr->discard)
 362                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 363                                         new->rq);
 364
 365         gd->queue = new->rq;
 366
 367         __get_mtd_device(new->mtd);
 368         __module_get(tr->owner);
 369
 370         /* Create processing thread */
 371         /* TODO: workqueue ? */
 372         new->thread = kthread_run(mtd_blktrans_thread, new,
 373                         "%s%d", tr->name, new->mtd->index);
 374         if (IS_ERR(new->thread)) {
 375                 ret = PTR_ERR(new->thread);
 376                 goto error4;
 377         }
 378         gd->driverfs_dev = &new->mtd->dev;
 379
 380         if (new->readonly)
 381                 set_disk_ro(gd, 1);
 382
 383         add_disk(gd);
 384
 385         if (new->disk_attributes) {
 386                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 387                                         new->disk_attributes);
 388                 WARN_ON(ret);
 389         }
 390         return 0;
 391 error4:
 392         module_put(tr->owner);
 393         __put_mtd_device(new->mtd);
 394         blk_cleanup_queue(new->rq);
 395 error3:
 396         put_disk(new->disk);
 397 error2:
 398         list_del(&new->list);
 399 error1:
 400         kfree(new);
 401         return ret;
 402 }
 403
 404 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 405 {
 406         unsigned long flags;
 407
 408         if (mutex_trylock(&mtd_table_mutex)) {
 409                 mutex_unlock(&mtd_table_mutex);
 410                 BUG();
 411         }
 412
 413         /* Stop new requests to arrive */
 414         del_gendisk(old->disk);
 415
 416         if (old->disk_attributes)
 417                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 418                                                 old->disk_attributes);
 419
 420         /* Stop the thread */
 421         kthread_stop(old->thread);
 422
 423         /* Kill current requests */
 424         spin_lock_irqsave(&old->queue_lock, flags);
 425         old->rq->queuedata = NULL;
 426         blk_start_queue(old->rq);
 427         spin_unlock_irqrestore(&old->queue_lock, flags);
 428
 429         /* Ask trans driver for release to the mtd device */
 430         mutex_lock(&old->lock);
 431         if (old->open && old->tr->release) {
 432                 old->tr->release(old);
 433                 old->open = 0;
 434         }
 435
 436         __put_mtd_device(old->mtd);
 437         module_put(old->tr->owner);
 438
 439         /* At that point, we don't touch the mtd anymore */
 440         old->mtd = NULL;
 441
 442         mutex_unlock(&old->lock);
 443         blktrans_dev_put(old);
 444         return 0;
 445 }
 446
 447 static void blktrans_notify_remove(struct mtd_info *mtd)
 448 {
 449         struct mtd_blktrans_ops *tr;
 450         struct mtd_blktrans_dev *dev, *next;
 451
 452         list_for_each_entry(tr, &blktrans_majors, list)
 453                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 454                         if (dev->mtd == mtd)
 455                                 tr->remove_dev(dev);
 456 }
 457
 458 static void blktrans_notify_add(struct mtd_info *mtd)
 459 {
 460         struct mtd_blktrans_ops *tr;
 461
 462         if (mtd->type == MTD_ABSENT)
 463                 return;
 464
 465         list_for_each_entry(tr, &blktrans_majors, list)
 466                 tr->add_mtd(tr, mtd);
 467 }
 468
 469 static struct mtd_notifier blktrans_notifier = {
 470         .add = blktrans_notify_add,
 471         .remove = blktrans_notify_remove,
 472 };
 473
 474 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 475 {
 476         struct mtd_info *mtd;
 477         int ret;
 478
 479         /* Register the notifier if/when the first device type is
 480            registered, to prevent the link/init ordering from fucking
 481            us over. */
 482         if (!blktrans_notifier.list.next)
 483                 register_mtd_user(&blktrans_notifier);
 484
 485
 486         mutex_lock(&mtd_table_mutex);
 487
 488         ret = register_blkdev(tr->major, tr->name);
 489         if (ret) {
 490                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 491                        tr->name, tr->major, ret);
 492                 mutex_unlock(&mtd_table_mutex);
 493                 return ret;
 494         }
 495
 496         tr->blkshift = ffs(tr->blksize) - 1;
 497
 498         INIT_LIST_HEAD(&tr->devs);
 499         list_add(&tr->list, &blktrans_majors);
 500
 501         mtd_for_each_device(mtd)
 502                 if (mtd->type != MTD_ABSENT)
 503                         tr->add_mtd(tr, mtd);
 504
 505         mutex_unlock(&mtd_table_mutex);
 506         return 0;
 507 }
 508
 509 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 510 {
 511         struct mtd_blktrans_dev *dev, *next;
 512
 513         mutex_lock(&mtd_table_mutex);
 514
 515         /* Remove it from the list of active majors */
 516         list_del(&tr->list);
 517
 518         list_for_each_entry_safe(dev, next, &tr->devs, list)
 519                 tr->remove_dev(dev);
 520
 521         unregister_blkdev(tr->major, tr->name);
 522         mutex_unlock(&mtd_table_mutex);
 523
 524         BUG_ON(!list_empty(&tr->devs));
 525         return 0;
 526 }
 527
 528 static void __exit mtd_blktrans_exit(void)
 529 {
 530         /* No race here -- if someone's currently in register_mtd_blktrans
 531            we're screwed anyway. */
 532         if (blktrans_notifier.list.next)
 533                 unregister_mtd_user(&blktrans_notifier);
 534 }
 535
 536 module_exit(mtd_blktrans_exit);
 537
 538 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 539 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 540 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 541 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 542
 543 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 544 MODULE_LICENSE("GPL");
 545 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");