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 <linux/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 blk_status_t 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
  86         if (req_op(req) == REQ_OP_FLUSH) {
  87                 if (tr->flush(dev))
  88                         return BLK_STS_IOERR;
  89                 return BLK_STS_OK;
  90         }
  91
  92         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  93             get_capacity(req->rq_disk))
  94                 return BLK_STS_IOERR;
  95
  96         switch (req_op(req)) {
  97         case REQ_OP_DISCARD:
  98                 if (tr->discard(dev, block, nsect))
  99                         return BLK_STS_IOERR;
 100                 return BLK_STS_OK;
 101         case REQ_OP_READ:
 102                 buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
 103                 for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
 104                         if (tr->readsect(dev, block, buf)) {
 105                                 kunmap(bio_page(req->bio));
 106                                 return BLK_STS_IOERR;
 107                         }
 108                 }
 109                 kunmap(bio_page(req->bio));
 110                 rq_flush_dcache_pages(req);
 111                 return BLK_STS_OK;
 112         case REQ_OP_WRITE:
 113                 if (!tr->writesect)
 114                         return BLK_STS_IOERR;
 115
 116                 rq_flush_dcache_pages(req);
 117                 buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
 118                 for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
 119                         if (tr->writesect(dev, block, buf)) {
 120                                 kunmap(bio_page(req->bio));
 121                                 return BLK_STS_IOERR;
 122                         }
 123                 }
 124                 kunmap(bio_page(req->bio));
 125                 return BLK_STS_OK;
 126         default:
 127                 return BLK_STS_IOERR;
 128         }
 129 }
 130
 131 int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
 132 {
 133         return dev->bg_stop;
 134 }
 135 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
 136
 137 static void mtd_blktrans_work(struct work_struct *work)
 138 {
 139         struct mtd_blktrans_dev *dev =
 140                 container_of(work, struct mtd_blktrans_dev, work);
 141         struct mtd_blktrans_ops *tr = dev->tr;
 142         struct request_queue *rq = dev->rq;
 143         struct request *req = NULL;
 144         int background_done = 0;
 145
 146         spin_lock_irq(rq->queue_lock);
 147
 148         while (1) {
 149                 blk_status_t res;
 150
 151                 dev->bg_stop = false;
 152                 if (!req && !(req = blk_fetch_request(rq))) {
 153                         if (tr->background && !background_done) {
 154                                 spin_unlock_irq(rq->queue_lock);
 155                                 mutex_lock(&dev->lock);
 156                                 tr->background(dev);
 157                                 mutex_unlock(&dev->lock);
 158                                 spin_lock_irq(rq->queue_lock);
 159                                 /*
 160                                  * Do background processing just once per idle
 161                                  * period.
 162                                  */
 163                                 background_done = !dev->bg_stop;
 164                                 continue;
 165                         }
 166                         break;
 167                 }
 168
 169                 spin_unlock_irq(rq->queue_lock);
 170
 171                 mutex_lock(&dev->lock);
 172                 res = do_blktrans_request(dev->tr, dev, req);
 173                 mutex_unlock(&dev->lock);
 174
 175                 spin_lock_irq(rq->queue_lock);
 176
 177                 if (!__blk_end_request_cur(req, res))
 178                         req = NULL;
 179
 180                 background_done = 0;
 181         }
 182
 183         spin_unlock_irq(rq->queue_lock);
 184 }
 185
 186 static void mtd_blktrans_request(struct request_queue *rq)
 187 {
 188         struct mtd_blktrans_dev *dev;
 189         struct request *req = NULL;
 190
 191         dev = rq->queuedata;
 192
 193         if (!dev)
 194                 while ((req = blk_fetch_request(rq)) != NULL)
 195                         __blk_end_request_all(req, BLK_STS_IOERR);
 196         else
 197                 queue_work(dev->wq, &dev->work);
 198 }
 199
 200 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 201 {
 202         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 203         int ret = 0;
 204
 205         if (!dev)
 206                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 207
 208         mutex_lock(&mtd_table_mutex);
 209         mutex_lock(&dev->lock);
 210
 211         if (dev->open)
 212                 goto unlock;
 213
 214         kref_get(&dev->ref);
 215         __module_get(dev->tr->owner);
 216
 217         if (!dev->mtd)
 218                 goto unlock;
 219
 220         if (dev->tr->open) {
 221                 ret = dev->tr->open(dev);
 222                 if (ret)
 223                         goto error_put;
 224         }
 225
 226         ret = __get_mtd_device(dev->mtd);
 227         if (ret)
 228                 goto error_release;
 229         dev->file_mode = mode;
 230
 231 unlock:
 232         dev->open++;
 233         mutex_unlock(&dev->lock);
 234         mutex_unlock(&mtd_table_mutex);
 235         blktrans_dev_put(dev);
 236         return ret;
 237
 238 error_release:
 239         if (dev->tr->release)
 240                 dev->tr->release(dev);
 241 error_put:
 242         module_put(dev->tr->owner);
 243         kref_put(&dev->ref, blktrans_dev_release);
 244         mutex_unlock(&dev->lock);
 245         mutex_unlock(&mtd_table_mutex);
 246         blktrans_dev_put(dev);
 247         return ret;
 248 }
 249
 250 static void blktrans_release(struct gendisk *disk, fmode_t mode)
 251 {
 252         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 253
 254         if (!dev)
 255                 return;
 256
 257         mutex_lock(&mtd_table_mutex);
 258         mutex_lock(&dev->lock);
 259
 260         if (--dev->open)
 261                 goto unlock;
 262
 263         kref_put(&dev->ref, blktrans_dev_release);
 264         module_put(dev->tr->owner);
 265
 266         if (dev->mtd) {
 267                 if (dev->tr->release)
 268                         dev->tr->release(dev);
 269                 __put_mtd_device(dev->mtd);
 270         }
 271 unlock:
 272         mutex_unlock(&dev->lock);
 273         mutex_unlock(&mtd_table_mutex);
 274         blktrans_dev_put(dev);
 275 }
 276
 277 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 278 {
 279         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 280         int ret = -ENXIO;
 281
 282         if (!dev)
 283                 return ret;
 284
 285         mutex_lock(&dev->lock);
 286
 287         if (!dev->mtd)
 288                 goto unlock;
 289
 290         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY;
 291 unlock:
 292         mutex_unlock(&dev->lock);
 293         blktrans_dev_put(dev);
 294         return ret;
 295 }
 296
 297 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 298                               unsigned int cmd, unsigned long arg)
 299 {
 300         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 301         int ret = -ENXIO;
 302
 303         if (!dev)
 304                 return ret;
 305
 306         mutex_lock(&dev->lock);
 307
 308         if (!dev->mtd)
 309                 goto unlock;
 310
 311         switch (cmd) {
 312         case BLKFLSBUF:
 313                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 314                 break;
 315         default:
 316                 ret = -ENOTTY;
 317         }
 318 unlock:
 319         mutex_unlock(&dev->lock);
 320         blktrans_dev_put(dev);
 321         return ret;
 322 }
 323
 324 static const struct block_device_operations mtd_block_ops = {
 325         .owner          = THIS_MODULE,
 326         .open           = blktrans_open,
 327         .release        = blktrans_release,
 328         .ioctl          = blktrans_ioctl,
 329         .getgeo         = blktrans_getgeo,
 330 };
 331
 332 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 333 {
 334         struct mtd_blktrans_ops *tr = new->tr;
 335         struct mtd_blktrans_dev *d;
 336         int last_devnum = -1;
 337         struct gendisk *gd;
 338         int ret;
 339
 340         if (mutex_trylock(&mtd_table_mutex)) {
 341                 mutex_unlock(&mtd_table_mutex);
 342                 BUG();
 343         }
 344
 345         mutex_lock(&blktrans_ref_mutex);
 346         list_for_each_entry(d, &tr->devs, list) {
 347                 if (new->devnum == -1) {
 348                         /* Use first free number */
 349                         if (d->devnum != last_devnum+1) {
 350                                 /* Found a free devnum. Plug it in here */
 351                                 new->devnum = last_devnum+1;
 352                                 list_add_tail(&new->list, &d->list);
 353                                 goto added;
 354                         }
 355                 } else if (d->devnum == new->devnum) {
 356                         /* Required number taken */
 357                         mutex_unlock(&blktrans_ref_mutex);
 358                         return -EBUSY;
 359                 } else if (d->devnum > new->devnum) {
 360                         /* Required number was free */
 361                         list_add_tail(&new->list, &d->list);
 362                         goto added;
 363                 }
 364                 last_devnum = d->devnum;
 365         }
 366
 367         ret = -EBUSY;
 368         if (new->devnum == -1)
 369                 new->devnum = last_devnum+1;
 370
 371         /* Check that the device and any partitions will get valid
 372          * minor numbers and that the disk naming code below can cope
 373          * with this number. */
 374         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 375             (tr->part_bits && new->devnum >= 27 * 26)) {
 376                 mutex_unlock(&blktrans_ref_mutex);
 377                 goto error1;
 378         }
 379
 380         list_add_tail(&new->list, &tr->devs);
 381  added:
 382         mutex_unlock(&blktrans_ref_mutex);
 383
 384         mutex_init(&new->lock);
 385         kref_init(&new->ref);
 386         if (!tr->writesect)
 387                 new->readonly = 1;
 388
 389         /* Create gendisk */
 390         ret = -ENOMEM;
 391         gd = alloc_disk(1 << tr->part_bits);
 392
 393         if (!gd)
 394                 goto error2;
 395
 396         new->disk = gd;
 397         gd->private_data = new;
 398         gd->major = tr->major;
 399         gd->first_minor = (new->devnum) << tr->part_bits;
 400         gd->fops = &mtd_block_ops;
 401
 402         if (tr->part_bits)
 403                 if (new->devnum < 26)
 404                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 405                                  "%s%c", tr->name, 'a' + new->devnum);
 406                 else
 407                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 408                                  "%s%c%c", tr->name,
 409                                  'a' - 1 + new->devnum / 26,
 410                                  'a' + new->devnum % 26);
 411         else
 412                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 413                          "%s%d", tr->name, new->devnum);
 414
 415         set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
 416
 417         /* Create the request queue */
 418         spin_lock_init(&new->queue_lock);
 419         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 420
 421         if (!new->rq)
 422                 goto error3;
 423
 424         if (tr->flush)
 425                 blk_queue_write_cache(new->rq, true, false);
 426
 427         new->rq->queuedata = new;
 428         blk_queue_logical_block_size(new->rq, tr->blksize);
 429
 430         blk_queue_flag_set(QUEUE_FLAG_NONROT, new->rq);
 431         blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq);
 432
 433         if (tr->discard) {
 434                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, new->rq);
 435                 blk_queue_max_discard_sectors(new->rq, UINT_MAX);
 436         }
 437
 438         gd->queue = new->rq;
 439
 440         /* Create processing workqueue */
 441         new->wq = alloc_workqueue("%s%d", 0, 0,
 442                                   tr->name, new->mtd->index);
 443         if (!new->wq)
 444                 goto error4;
 445         INIT_WORK(&new->work, mtd_blktrans_work);
 446
 447         if (new->readonly)
 448                 set_disk_ro(gd, 1);
 449
 450         device_add_disk(&new->mtd->dev, gd);
 451
 452         if (new->disk_attributes) {
 453                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 454                                         new->disk_attributes);
 455                 WARN_ON(ret);
 456         }
 457         return 0;
 458 error4:
 459         blk_cleanup_queue(new->rq);
 460 error3:
 461         put_disk(new->disk);
 462 error2:
 463         list_del(&new->list);
 464 error1:
 465         return ret;
 466 }
 467
 468 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 469 {
 470         unsigned long flags;
 471
 472         if (mutex_trylock(&mtd_table_mutex)) {
 473                 mutex_unlock(&mtd_table_mutex);
 474                 BUG();
 475         }
 476
 477         if (old->disk_attributes)
 478                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 479                                                 old->disk_attributes);
 480
 481         /* Stop new requests to arrive */
 482         del_gendisk(old->disk);
 483
 484         /* Stop workqueue. This will perform any pending request. */
 485         destroy_workqueue(old->wq);
 486
 487         /* Kill current requests */
 488         spin_lock_irqsave(&old->queue_lock, flags);
 489         old->rq->queuedata = NULL;
 490         blk_start_queue(old->rq);
 491         spin_unlock_irqrestore(&old->queue_lock, flags);
 492
 493         /* If the device is currently open, tell trans driver to close it,
 494                 then put mtd device, and don't touch it again */
 495         mutex_lock(&old->lock);
 496         if (old->open) {
 497                 if (old->tr->release)
 498                         old->tr->release(old);
 499                 __put_mtd_device(old->mtd);
 500         }
 501
 502         old->mtd = NULL;
 503
 504         mutex_unlock(&old->lock);
 505         blktrans_dev_put(old);
 506         return 0;
 507 }
 508
 509 static void blktrans_notify_remove(struct mtd_info *mtd)
 510 {
 511         struct mtd_blktrans_ops *tr;
 512         struct mtd_blktrans_dev *dev, *next;
 513
 514         list_for_each_entry(tr, &blktrans_majors, list)
 515                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 516                         if (dev->mtd == mtd)
 517                                 tr->remove_dev(dev);
 518 }
 519
 520 static void blktrans_notify_add(struct mtd_info *mtd)
 521 {
 522         struct mtd_blktrans_ops *tr;
 523
 524         if (mtd->type == MTD_ABSENT)
 525                 return;
 526
 527         list_for_each_entry(tr, &blktrans_majors, list)
 528                 tr->add_mtd(tr, mtd);
 529 }
 530
 531 static struct mtd_notifier blktrans_notifier = {
 532         .add = blktrans_notify_add,
 533         .remove = blktrans_notify_remove,
 534 };
 535
 536 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 537 {
 538         struct mtd_info *mtd;
 539         int ret;
 540
 541         /* Register the notifier if/when the first device type is
 542            registered, to prevent the link/init ordering from fucking
 543            us over. */
 544         if (!blktrans_notifier.list.next)
 545                 register_mtd_user(&blktrans_notifier);
 546
 547
 548         mutex_lock(&mtd_table_mutex);
 549
 550         ret = register_blkdev(tr->major, tr->name);
 551         if (ret < 0) {
 552                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 553                        tr->name, tr->major, ret);
 554                 mutex_unlock(&mtd_table_mutex);
 555                 return ret;
 556         }
 557
 558         if (ret)
 559                 tr->major = ret;
 560
 561         tr->blkshift = ffs(tr->blksize) - 1;
 562
 563         INIT_LIST_HEAD(&tr->devs);
 564         list_add(&tr->list, &blktrans_majors);
 565
 566         mtd_for_each_device(mtd)
 567                 if (mtd->type != MTD_ABSENT)
 568                         tr->add_mtd(tr, mtd);
 569
 570         mutex_unlock(&mtd_table_mutex);
 571         return 0;
 572 }
 573
 574 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 575 {
 576         struct mtd_blktrans_dev *dev, *next;
 577
 578         mutex_lock(&mtd_table_mutex);
 579
 580         /* Remove it from the list of active majors */
 581         list_del(&tr->list);
 582
 583         list_for_each_entry_safe(dev, next, &tr->devs, list)
 584                 tr->remove_dev(dev);
 585
 586         unregister_blkdev(tr->major, tr->name);
 587         mutex_unlock(&mtd_table_mutex);
 588
 589         BUG_ON(!list_empty(&tr->devs));
 590         return 0;
 591 }
 592
 593 static void __exit mtd_blktrans_exit(void)
 594 {
 595         /* No race here -- if someone's currently in register_mtd_blktrans
 596            we're screwed anyway. */
 597         if (blktrans_notifier.list.next)
 598                 unregister_mtd_user(&blktrans_notifier);
 599 }
 600
 601 module_exit(mtd_blktrans_exit);
 602
 603 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 604 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 605 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 606 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 607
 608 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 609 MODULE_LICENSE("GPL");
 610 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");