drivers/mtd/mtd_blkdevs.c

   1 /*
   2  * Interface to Linux block layer for MTD 'translation layers'.
   3  *
   4  * Copyright © 2003-2010 David Woodhouse <dwmw2@infradead.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  */
  21
  22 #include <linux/kernel.h>
  23 #include <linux/slab.h>
  24 #include <linux/module.h>
  25 #include <linux/list.h>
  26 #include <linux/fs.h>
  27 #include <linux/mtd/blktrans.h>
  28 #include <linux/mtd/mtd.h>
  29 #include <linux/blkdev.h>
  30 #include <linux/blkpg.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/hdreg.h>
  33 #include <linux/mutex.h>
  34 #include <asm/uaccess.h>
  35
  36 #include "mtdcore.h"
  37
  38 static LIST_HEAD(blktrans_majors);
  39 static DEFINE_MUTEX(blktrans_ref_mutex);
  40
  41 static void blktrans_dev_release(struct kref *kref)
  42 {
  43         struct mtd_blktrans_dev *dev =
  44                 container_of(kref, struct mtd_blktrans_dev, ref);
  45
  46         dev->disk->private_data = NULL;
  47         blk_cleanup_queue(dev->rq);
  48         put_disk(dev->disk);
  49         list_del(&dev->list);
  50         kfree(dev);
  51 }
  52
  53 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  54 {
  55         struct mtd_blktrans_dev *dev;
  56
  57         mutex_lock(&blktrans_ref_mutex);
  58         dev = disk->private_data;
  59
  60         if (!dev)
  61                 goto unlock;
  62         kref_get(&dev->ref);
  63 unlock:
  64         mutex_unlock(&blktrans_ref_mutex);
  65         return dev;
  66 }
  67
  68 static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  69 {
  70         mutex_lock(&blktrans_ref_mutex);
  71         kref_put(&dev->ref, blktrans_dev_release);
  72         mutex_unlock(&blktrans_ref_mutex);
  73 }
  74
  75
  76 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  77                                struct mtd_blktrans_dev *dev,
  78                                struct request *req)
  79 {
  80         unsigned long block, nsect;
  81         char *buf;
  82
  83         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  84         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  85         buf = bio_data(req->bio);
  86
  87         if (req->cmd_type != REQ_TYPE_FS)
  88                 return -EIO;
  89
  90         if (req->cmd_flags & REQ_FLUSH)
  91                 return tr->flush(dev);
  92
  93         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  94             get_capacity(req->rq_disk))
  95                 return -EIO;
  96
  97         if (req->cmd_flags & REQ_DISCARD)
  98                 return tr->discard(dev, block, nsect);
  99
 100         switch(rq_data_dir(req)) {
 101         case READ:
 102                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 103                         if (tr->readsect(dev, block, buf))
 104                                 return -EIO;
 105                 rq_flush_dcache_pages(req);
 106                 return 0;
 107         case WRITE:
 108                 if (!tr->writesect)
 109                         return -EIO;
 110
 111                 rq_flush_dcache_pages(req);
 112                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 113                         if (tr->writesect(dev, block, buf))
 114                                 return -EIO;
 115                 return 0;
 116         default:
 117                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
 118                 return -EIO;
 119         }
 120 }
 121
 122 int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
 123 {
 124         return dev->bg_stop;
 125 }
 126 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
 127
 128 static void mtd_blktrans_work(struct work_struct *work)
 129 {
 130         struct mtd_blktrans_dev *dev =
 131                 container_of(work, struct mtd_blktrans_dev, work);
 132         struct mtd_blktrans_ops *tr = dev->tr;
 133         struct request_queue *rq = dev->rq;
 134         struct request *req = NULL;
 135         int background_done = 0;
 136
 137         spin_lock_irq(rq->queue_lock);
 138
 139         while (1) {
 140                 int res;
 141
 142                 dev->bg_stop = false;
 143                 if (!req && !(req = blk_fetch_request(rq))) {
 144                         if (tr->background && !background_done) {
 145                                 spin_unlock_irq(rq->queue_lock);
 146                                 mutex_lock(&dev->lock);
 147                                 tr->background(dev);
 148                                 mutex_unlock(&dev->lock);
 149                                 spin_lock_irq(rq->queue_lock);
 150                                 /*
 151                                  * Do background processing just once per idle
 152                                  * period.
 153                                  */
 154                                 background_done = !dev->bg_stop;
 155                                 continue;
 156                         }
 157                         break;
 158                 }
 159
 160                 spin_unlock_irq(rq->queue_lock);
 161
 162                 mutex_lock(&dev->lock);
 163                 res = do_blktrans_request(dev->tr, dev, req);
 164                 mutex_unlock(&dev->lock);
 165
 166                 spin_lock_irq(rq->queue_lock);
 167
 168                 if (!__blk_end_request_cur(req, res))
 169                         req = NULL;
 170
 171                 background_done = 0;
 172         }
 173
 174         spin_unlock_irq(rq->queue_lock);
 175 }
 176
 177 static void mtd_blktrans_request(struct request_queue *rq)
 178 {
 179         struct mtd_blktrans_dev *dev;
 180         struct request *req = NULL;
 181
 182         dev = rq->queuedata;
 183
 184         if (!dev)
 185                 while ((req = blk_fetch_request(rq)) != NULL)
 186                         __blk_end_request_all(req, -ENODEV);
 187         else
 188                 queue_work(dev->wq, &dev->work);
 189 }
 190
 191 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 192 {
 193         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 194         int ret = 0;
 195
 196         if (!dev)
 197                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 198
 199         mutex_lock(&dev->lock);
 200         mutex_lock(&mtd_table_mutex);
 201
 202         if (dev->open)
 203                 goto unlock;
 204
 205         kref_get(&dev->ref);
 206         __module_get(dev->tr->owner);
 207
 208         if (!dev->mtd)
 209                 goto unlock;
 210
 211         if (dev->tr->open) {
 212                 ret = dev->tr->open(dev);
 213                 if (ret)
 214                         goto error_put;
 215         }
 216
 217         ret = __get_mtd_device(dev->mtd);
 218         if (ret)
 219                 goto error_release;
 220         dev->file_mode = mode;
 221
 222 unlock:
 223         dev->open++;
 224         mutex_unlock(&mtd_table_mutex);
 225         mutex_unlock(&dev->lock);
 226         blktrans_dev_put(dev);
 227         return ret;
 228
 229 error_release:
 230         if (dev->tr->release)
 231                 dev->tr->release(dev);
 232 error_put:
 233         module_put(dev->tr->owner);
 234         kref_put(&dev->ref, blktrans_dev_release);
 235         mutex_unlock(&mtd_table_mutex);
 236         mutex_unlock(&dev->lock);
 237         blktrans_dev_put(dev);
 238         return ret;
 239 }
 240
 241 static void blktrans_release(struct gendisk *disk, fmode_t mode)
 242 {
 243         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 244
 245         if (!dev)
 246                 return;
 247
 248         mutex_lock(&dev->lock);
 249         mutex_lock(&mtd_table_mutex);
 250
 251         if (--dev->open)
 252                 goto unlock;
 253
 254         kref_put(&dev->ref, blktrans_dev_release);
 255         module_put(dev->tr->owner);
 256
 257         if (dev->mtd) {
 258                 if (dev->tr->release)
 259                         dev->tr->release(dev);
 260                 __put_mtd_device(dev->mtd);
 261         }
 262 unlock:
 263         mutex_unlock(&mtd_table_mutex);
 264         mutex_unlock(&dev->lock);
 265         blktrans_dev_put(dev);
 266 }
 267
 268 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 269 {
 270         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 271         int ret = -ENXIO;
 272
 273         if (!dev)
 274                 return ret;
 275
 276         mutex_lock(&dev->lock);
 277
 278         if (!dev->mtd)
 279                 goto unlock;
 280
 281         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY;
 282 unlock:
 283         mutex_unlock(&dev->lock);
 284         blktrans_dev_put(dev);
 285         return ret;
 286 }
 287
 288 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 289                               unsigned int cmd, unsigned long arg)
 290 {
 291         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 292         int ret = -ENXIO;
 293
 294         if (!dev)
 295                 return ret;
 296
 297         mutex_lock(&dev->lock);
 298
 299         if (!dev->mtd)
 300                 goto unlock;
 301
 302         switch (cmd) {
 303         case BLKFLSBUF:
 304                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 305                 break;
 306         default:
 307                 ret = -ENOTTY;
 308         }
 309 unlock:
 310         mutex_unlock(&dev->lock);
 311         blktrans_dev_put(dev);
 312         return ret;
 313 }
 314
 315 static const struct block_device_operations mtd_block_ops = {
 316         .owner          = THIS_MODULE,
 317         .open           = blktrans_open,
 318         .release        = blktrans_release,
 319         .ioctl          = blktrans_ioctl,
 320         .getgeo         = blktrans_getgeo,
 321 };
 322
 323 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 324 {
 325         struct mtd_blktrans_ops *tr = new->tr;
 326         struct mtd_blktrans_dev *d;
 327         int last_devnum = -1;
 328         struct gendisk *gd;
 329         int ret;
 330
 331         if (mutex_trylock(&mtd_table_mutex)) {
 332                 mutex_unlock(&mtd_table_mutex);
 333                 BUG();
 334         }
 335
 336         mutex_lock(&blktrans_ref_mutex);
 337         list_for_each_entry(d, &tr->devs, list) {
 338                 if (new->devnum == -1) {
 339                         /* Use first free number */
 340                         if (d->devnum != last_devnum+1) {
 341                                 /* Found a free devnum. Plug it in here */
 342                                 new->devnum = last_devnum+1;
 343                                 list_add_tail(&new->list, &d->list);
 344                                 goto added;
 345                         }
 346                 } else if (d->devnum == new->devnum) {
 347                         /* Required number taken */
 348                         mutex_unlock(&blktrans_ref_mutex);
 349                         return -EBUSY;
 350                 } else if (d->devnum > new->devnum) {
 351                         /* Required number was free */
 352                         list_add_tail(&new->list, &d->list);
 353                         goto added;
 354                 }
 355                 last_devnum = d->devnum;
 356         }
 357
 358         ret = -EBUSY;
 359         if (new->devnum == -1)
 360                 new->devnum = last_devnum+1;
 361
 362         /* Check that the device and any partitions will get valid
 363          * minor numbers and that the disk naming code below can cope
 364          * with this number. */
 365         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 366             (tr->part_bits && new->devnum >= 27 * 26)) {
 367                 mutex_unlock(&blktrans_ref_mutex);
 368                 goto error1;
 369         }
 370
 371         list_add_tail(&new->list, &tr->devs);
 372  added:
 373         mutex_unlock(&blktrans_ref_mutex);
 374
 375         mutex_init(&new->lock);
 376         kref_init(&new->ref);
 377         if (!tr->writesect)
 378                 new->readonly = 1;
 379
 380         /* Create gendisk */
 381         ret = -ENOMEM;
 382         gd = alloc_disk(1 << tr->part_bits);
 383
 384         if (!gd)
 385                 goto error2;
 386
 387         new->disk = gd;
 388         gd->private_data = new;
 389         gd->major = tr->major;
 390         gd->first_minor = (new->devnum) << tr->part_bits;
 391         gd->fops = &mtd_block_ops;
 392
 393         if (tr->part_bits)
 394                 if (new->devnum < 26)
 395                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 396                                  "%s%c", tr->name, 'a' + new->devnum);
 397                 else
 398                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 399                                  "%s%c%c", tr->name,
 400                                  'a' - 1 + new->devnum / 26,
 401                                  'a' + new->devnum % 26);
 402         else
 403                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 404                          "%s%d", tr->name, new->devnum);
 405
 406         set_capacity(gd, (new->size * tr->blksize) >> 9);
 407
 408         /* Create the request queue */
 409         spin_lock_init(&new->queue_lock);
 410         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 411
 412         if (!new->rq)
 413                 goto error3;
 414
 415         if (tr->flush)
 416                 blk_queue_flush(new->rq, REQ_FLUSH);
 417
 418         new->rq->queuedata = new;
 419         blk_queue_logical_block_size(new->rq, tr->blksize);
 420
 421         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
 422         queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, new->rq);
 423
 424         if (tr->discard) {
 425                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
 426                 blk_queue_max_discard_sectors(new->rq, UINT_MAX);
 427         }
 428
 429         gd->queue = new->rq;
 430
 431         /* Create processing workqueue */
 432         new->wq = alloc_workqueue("%s%d", 0, 0,
 433                                   tr->name, new->mtd->index);
 434         if (!new->wq)
 435                 goto error4;
 436         INIT_WORK(&new->work, mtd_blktrans_work);
 437
 438         gd->driverfs_dev = &new->mtd->dev;
 439
 440         if (new->readonly)
 441                 set_disk_ro(gd, 1);
 442
 443         add_disk(gd);
 444
 445         if (new->disk_attributes) {
 446                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 447                                         new->disk_attributes);
 448                 WARN_ON(ret);
 449         }
 450         return 0;
 451 error4:
 452         blk_cleanup_queue(new->rq);
 453 error3:
 454         put_disk(new->disk);
 455 error2:
 456         list_del(&new->list);
 457 error1:
 458         return ret;
 459 }
 460
 461 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 462 {
 463         unsigned long flags;
 464
 465         if (mutex_trylock(&mtd_table_mutex)) {
 466                 mutex_unlock(&mtd_table_mutex);
 467                 BUG();
 468         }
 469
 470         if (old->disk_attributes)
 471                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 472                                                 old->disk_attributes);
 473
 474         /* Stop new requests to arrive */
 475         del_gendisk(old->disk);
 476
 477         /* Stop workqueue. This will perform any pending request. */
 478         destroy_workqueue(old->wq);
 479
 480         /* Kill current requests */
 481         spin_lock_irqsave(&old->queue_lock, flags);
 482         old->rq->queuedata = NULL;
 483         blk_start_queue(old->rq);
 484         spin_unlock_irqrestore(&old->queue_lock, flags);
 485
 486         /* If the device is currently open, tell trans driver to close it,
 487                 then put mtd device, and don't touch it again */
 488         mutex_lock(&old->lock);
 489         if (old->open) {
 490                 if (old->tr->release)
 491                         old->tr->release(old);
 492                 __put_mtd_device(old->mtd);
 493         }
 494
 495         old->mtd = NULL;
 496
 497         mutex_unlock(&old->lock);
 498         blktrans_dev_put(old);
 499         return 0;
 500 }
 501
 502 static void blktrans_notify_remove(struct mtd_info *mtd)
 503 {
 504         struct mtd_blktrans_ops *tr;
 505         struct mtd_blktrans_dev *dev, *next;
 506
 507         list_for_each_entry(tr, &blktrans_majors, list)
 508                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 509                         if (dev->mtd == mtd)
 510                                 tr->remove_dev(dev);
 511 }
 512
 513 static void blktrans_notify_add(struct mtd_info *mtd)
 514 {
 515         struct mtd_blktrans_ops *tr;
 516
 517         if (mtd->type == MTD_ABSENT)
 518                 return;
 519
 520         list_for_each_entry(tr, &blktrans_majors, list)
 521                 tr->add_mtd(tr, mtd);
 522 }
 523
 524 static struct mtd_notifier blktrans_notifier = {
 525         .add = blktrans_notify_add,
 526         .remove = blktrans_notify_remove,
 527 };
 528
 529 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 530 {
 531         struct mtd_info *mtd;
 532         int ret;
 533
 534         /* Register the notifier if/when the first device type is
 535            registered, to prevent the link/init ordering from fucking
 536            us over. */
 537         if (!blktrans_notifier.list.next)
 538                 register_mtd_user(&blktrans_notifier);
 539
 540
 541         mutex_lock(&mtd_table_mutex);
 542
 543         ret = register_blkdev(tr->major, tr->name);
 544         if (ret < 0) {
 545                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 546                        tr->name, tr->major, ret);
 547                 mutex_unlock(&mtd_table_mutex);
 548                 return ret;
 549         }
 550
 551         if (ret)
 552                 tr->major = ret;
 553
 554         tr->blkshift = ffs(tr->blksize) - 1;
 555
 556         INIT_LIST_HEAD(&tr->devs);
 557         list_add(&tr->list, &blktrans_majors);
 558
 559         mtd_for_each_device(mtd)
 560                 if (mtd->type != MTD_ABSENT)
 561                         tr->add_mtd(tr, mtd);
 562
 563         mutex_unlock(&mtd_table_mutex);
 564         return 0;
 565 }
 566
 567 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 568 {
 569         struct mtd_blktrans_dev *dev, *next;
 570
 571         mutex_lock(&mtd_table_mutex);
 572
 573         /* Remove it from the list of active majors */
 574         list_del(&tr->list);
 575
 576         list_for_each_entry_safe(dev, next, &tr->devs, list)
 577                 tr->remove_dev(dev);
 578
 579         unregister_blkdev(tr->major, tr->name);
 580         mutex_unlock(&mtd_table_mutex);
 581
 582         BUG_ON(!list_empty(&tr->devs));
 583         return 0;
 584 }
 585
 586 static void __exit mtd_blktrans_exit(void)
 587 {
 588         /* No race here -- if someone's currently in register_mtd_blktrans
 589            we're screwed anyway. */
 590         if (blktrans_notifier.list.next)
 591                 unregister_mtd_user(&blktrans_notifier);
 592 }
 593
 594 module_exit(mtd_blktrans_exit);
 595
 596 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 597 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 598 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 599 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 600
 601 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 602 MODULE_LICENSE("GPL");
 603 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");