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         if (req)
 175                 __blk_end_request_all(req, -EIO);
 176
 177         spin_unlock_irq(rq->queue_lock);
 178 }
 179
 180 static void mtd_blktrans_request(struct request_queue *rq)
 181 {
 182         struct mtd_blktrans_dev *dev;
 183         struct request *req = NULL;
 184
 185         dev = rq->queuedata;
 186
 187         if (!dev)
 188                 while ((req = blk_fetch_request(rq)) != NULL)
 189                         __blk_end_request_all(req, -ENODEV);
 190         else
 191                 queue_work(dev->wq, &dev->work);
 192 }
 193
 194 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 195 {
 196         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 197         int ret = 0;
 198
 199         if (!dev)
 200                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 201
 202         mutex_lock(&dev->lock);
 203         mutex_lock(&mtd_table_mutex);
 204
 205         if (dev->open)
 206                 goto unlock;
 207
 208         kref_get(&dev->ref);
 209         __module_get(dev->tr->owner);
 210
 211         if (!dev->mtd)
 212                 goto unlock;
 213
 214         if (dev->tr->open) {
 215                 ret = dev->tr->open(dev);
 216                 if (ret)
 217                         goto error_put;
 218         }
 219
 220         ret = __get_mtd_device(dev->mtd);
 221         if (ret)
 222                 goto error_release;
 223         dev->file_mode = mode;
 224
 225 unlock:
 226         dev->open++;
 227         mutex_unlock(&mtd_table_mutex);
 228         mutex_unlock(&dev->lock);
 229         blktrans_dev_put(dev);
 230         return ret;
 231
 232 error_release:
 233         if (dev->tr->release)
 234                 dev->tr->release(dev);
 235 error_put:
 236         module_put(dev->tr->owner);
 237         kref_put(&dev->ref, blktrans_dev_release);
 238         mutex_unlock(&mtd_table_mutex);
 239         mutex_unlock(&dev->lock);
 240         blktrans_dev_put(dev);
 241         return ret;
 242 }
 243
 244 static void blktrans_release(struct gendisk *disk, fmode_t mode)
 245 {
 246         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 247
 248         if (!dev)
 249                 return;
 250
 251         mutex_lock(&dev->lock);
 252         mutex_lock(&mtd_table_mutex);
 253
 254         if (--dev->open)
 255                 goto unlock;
 256
 257         kref_put(&dev->ref, blktrans_dev_release);
 258         module_put(dev->tr->owner);
 259
 260         if (dev->mtd) {
 261                 if (dev->tr->release)
 262                         dev->tr->release(dev);
 263                 __put_mtd_device(dev->mtd);
 264         }
 265 unlock:
 266         mutex_unlock(&mtd_table_mutex);
 267         mutex_unlock(&dev->lock);
 268         blktrans_dev_put(dev);
 269 }
 270
 271 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 272 {
 273         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 274         int ret = -ENXIO;
 275
 276         if (!dev)
 277                 return ret;
 278
 279         mutex_lock(&dev->lock);
 280
 281         if (!dev->mtd)
 282                 goto unlock;
 283
 284         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 285 unlock:
 286         mutex_unlock(&dev->lock);
 287         blktrans_dev_put(dev);
 288         return ret;
 289 }
 290
 291 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 292                               unsigned int cmd, unsigned long arg)
 293 {
 294         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 295         int ret = -ENXIO;
 296
 297         if (!dev)
 298                 return ret;
 299
 300         mutex_lock(&dev->lock);
 301
 302         if (!dev->mtd)
 303                 goto unlock;
 304
 305         switch (cmd) {
 306         case BLKFLSBUF:
 307                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 308                 break;
 309         default:
 310                 ret = -ENOTTY;
 311         }
 312 unlock:
 313         mutex_unlock(&dev->lock);
 314         blktrans_dev_put(dev);
 315         return ret;
 316 }
 317
 318 static const struct block_device_operations mtd_block_ops = {
 319         .owner          = THIS_MODULE,
 320         .open           = blktrans_open,
 321         .release        = blktrans_release,
 322         .ioctl          = blktrans_ioctl,
 323         .getgeo         = blktrans_getgeo,
 324 };
 325
 326 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 327 {
 328         struct mtd_blktrans_ops *tr = new->tr;
 329         struct mtd_blktrans_dev *d;
 330         int last_devnum = -1;
 331         struct gendisk *gd;
 332         int ret;
 333
 334         if (mutex_trylock(&mtd_table_mutex)) {
 335                 mutex_unlock(&mtd_table_mutex);
 336                 BUG();
 337         }
 338
 339         mutex_lock(&blktrans_ref_mutex);
 340         list_for_each_entry(d, &tr->devs, list) {
 341                 if (new->devnum == -1) {
 342                         /* Use first free number */
 343                         if (d->devnum != last_devnum+1) {
 344                                 /* Found a free devnum. Plug it in here */
 345                                 new->devnum = last_devnum+1;
 346                                 list_add_tail(&new->list, &d->list);
 347                                 goto added;
 348                         }
 349                 } else if (d->devnum == new->devnum) {
 350                         /* Required number taken */
 351                         mutex_unlock(&blktrans_ref_mutex);
 352                         return -EBUSY;
 353                 } else if (d->devnum > new->devnum) {
 354                         /* Required number was free */
 355                         list_add_tail(&new->list, &d->list);
 356                         goto added;
 357                 }
 358                 last_devnum = d->devnum;
 359         }
 360
 361         ret = -EBUSY;
 362         if (new->devnum == -1)
 363                 new->devnum = last_devnum+1;
 364
 365         /* Check that the device and any partitions will get valid
 366          * minor numbers and that the disk naming code below can cope
 367          * with this number. */
 368         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 369             (tr->part_bits && new->devnum >= 27 * 26)) {
 370                 mutex_unlock(&blktrans_ref_mutex);
 371                 goto error1;
 372         }
 373
 374         list_add_tail(&new->list, &tr->devs);
 375  added:
 376         mutex_unlock(&blktrans_ref_mutex);
 377
 378         mutex_init(&new->lock);
 379         kref_init(&new->ref);
 380         if (!tr->writesect)
 381                 new->readonly = 1;
 382
 383         /* Create gendisk */
 384         ret = -ENOMEM;
 385         gd = alloc_disk(1 << tr->part_bits);
 386
 387         if (!gd)
 388                 goto error2;
 389
 390         new->disk = gd;
 391         gd->private_data = new;
 392         gd->major = tr->major;
 393         gd->first_minor = (new->devnum) << tr->part_bits;
 394         gd->fops = &mtd_block_ops;
 395
 396         if (tr->part_bits)
 397                 if (new->devnum < 26)
 398                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 399                                  "%s%c", tr->name, 'a' + new->devnum);
 400                 else
 401                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 402                                  "%s%c%c", tr->name,
 403                                  'a' - 1 + new->devnum / 26,
 404                                  'a' + new->devnum % 26);
 405         else
 406                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 407                          "%s%d", tr->name, new->devnum);
 408
 409         set_capacity(gd, (new->size * tr->blksize) >> 9);
 410
 411         /* Create the request queue */
 412         spin_lock_init(&new->queue_lock);
 413         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 414
 415         if (!new->rq)
 416                 goto error3;
 417
 418         if (tr->flush)
 419                 blk_queue_flush(new->rq, REQ_FLUSH);
 420
 421         new->rq->queuedata = new;
 422         blk_queue_logical_block_size(new->rq, tr->blksize);
 423
 424         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
 425         queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, new->rq);
 426
 427         if (tr->discard) {
 428                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
 429                 new->rq->limits.max_discard_sectors = UINT_MAX;
 430         }
 431
 432         gd->queue = new->rq;
 433
 434         /* Create processing workqueue */
 435         new->wq = alloc_workqueue("%s%d", 0, 0,
 436                                   tr->name, new->mtd->index);
 437         if (!new->wq)
 438                 goto error4;
 439         INIT_WORK(&new->work, mtd_blktrans_work);
 440
 441         gd->driverfs_dev = &new->mtd->dev;
 442
 443         if (new->readonly)
 444                 set_disk_ro(gd, 1);
 445
 446         add_disk(gd);
 447
 448         if (new->disk_attributes) {
 449                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 450                                         new->disk_attributes);
 451                 WARN_ON(ret);
 452         }
 453         return 0;
 454 error4:
 455         blk_cleanup_queue(new->rq);
 456 error3:
 457         put_disk(new->disk);
 458 error2:
 459         list_del(&new->list);
 460 error1:
 461         return ret;
 462 }
 463
 464 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 465 {
 466         unsigned long flags;
 467
 468         if (mutex_trylock(&mtd_table_mutex)) {
 469                 mutex_unlock(&mtd_table_mutex);
 470                 BUG();
 471         }
 472
 473         if (old->disk_attributes)
 474                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 475                                                 old->disk_attributes);
 476
 477         /* Stop new requests to arrive */
 478         del_gendisk(old->disk);
 479
 480         /* Stop workqueue. This will perform any pending request. */
 481         destroy_workqueue(old->wq);
 482
 483         /* Kill current requests */
 484         spin_lock_irqsave(&old->queue_lock, flags);
 485         old->rq->queuedata = NULL;
 486         blk_start_queue(old->rq);
 487         spin_unlock_irqrestore(&old->queue_lock, flags);
 488
 489         /* If the device is currently open, tell trans driver to close it,
 490                 then put mtd device, and don't touch it again */
 491         mutex_lock(&old->lock);
 492         if (old->open) {
 493                 if (old->tr->release)
 494                         old->tr->release(old);
 495                 __put_mtd_device(old->mtd);
 496         }
 497
 498         old->mtd = NULL;
 499
 500         mutex_unlock(&old->lock);
 501         blktrans_dev_put(old);
 502         return 0;
 503 }
 504
 505 static void blktrans_notify_remove(struct mtd_info *mtd)
 506 {
 507         struct mtd_blktrans_ops *tr;
 508         struct mtd_blktrans_dev *dev, *next;
 509
 510         list_for_each_entry(tr, &blktrans_majors, list)
 511                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 512                         if (dev->mtd == mtd)
 513                                 tr->remove_dev(dev);
 514 }
 515
 516 static void blktrans_notify_add(struct mtd_info *mtd)
 517 {
 518         struct mtd_blktrans_ops *tr;
 519
 520         if (mtd->type == MTD_ABSENT)
 521                 return;
 522
 523         list_for_each_entry(tr, &blktrans_majors, list)
 524                 tr->add_mtd(tr, mtd);
 525 }
 526
 527 static struct mtd_notifier blktrans_notifier = {
 528         .add = blktrans_notify_add,
 529         .remove = blktrans_notify_remove,
 530 };
 531
 532 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 533 {
 534         struct mtd_info *mtd;
 535         int ret;
 536
 537         /* Register the notifier if/when the first device type is
 538            registered, to prevent the link/init ordering from fucking
 539            us over. */
 540         if (!blktrans_notifier.list.next)
 541                 register_mtd_user(&blktrans_notifier);
 542
 543
 544         mutex_lock(&mtd_table_mutex);
 545
 546         ret = register_blkdev(tr->major, tr->name);
 547         if (ret < 0) {
 548                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 549                        tr->name, tr->major, ret);
 550                 mutex_unlock(&mtd_table_mutex);
 551                 return ret;
 552         }
 553
 554         if (ret)
 555                 tr->major = ret;
 556
 557         tr->blkshift = ffs(tr->blksize) - 1;
 558
 559         INIT_LIST_HEAD(&tr->devs);
 560         list_add(&tr->list, &blktrans_majors);
 561
 562         mtd_for_each_device(mtd)
 563                 if (mtd->type != MTD_ABSENT)
 564                         tr->add_mtd(tr, mtd);
 565
 566         mutex_unlock(&mtd_table_mutex);
 567         return 0;
 568 }
 569
 570 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 571 {
 572         struct mtd_blktrans_dev *dev, *next;
 573
 574         mutex_lock(&mtd_table_mutex);
 575
 576         /* Remove it from the list of active majors */
 577         list_del(&tr->list);
 578
 579         list_for_each_entry_safe(dev, next, &tr->devs, list)
 580                 tr->remove_dev(dev);
 581
 582         unregister_blkdev(tr->major, tr->name);
 583         mutex_unlock(&mtd_table_mutex);
 584
 585         BUG_ON(!list_empty(&tr->devs));
 586         return 0;
 587 }
 588
 589 static void __exit mtd_blktrans_exit(void)
 590 {
 591         /* No race here -- if someone's currently in register_mtd_blktrans
 592            we're screwed anyway. */
 593         if (blktrans_notifier.list.next)
 594                 unregister_mtd_user(&blktrans_notifier);
 595 }
 596
 597 module_exit(mtd_blktrans_exit);
 598
 599 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 600 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 601 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 602 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 603
 604 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 605 MODULE_LICENSE("GPL");
 606 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");