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/init.h>
  34 #include <linux/mutex.h>
  35 #include <linux/kthread.h>
  36 #include <asm/uaccess.h>
  37
  38 #include "mtdcore.h"
  39
  40 static LIST_HEAD(blktrans_majors);
  41 static DEFINE_MUTEX(blktrans_ref_mutex);
  42
  43 static void blktrans_dev_release(struct kref *kref)
  44 {
  45         struct mtd_blktrans_dev *dev =
  46                 container_of(kref, struct mtd_blktrans_dev, ref);
  47
  48         dev->disk->private_data = NULL;
  49         blk_cleanup_queue(dev->rq);
  50         put_disk(dev->disk);
  51         list_del(&dev->list);
  52         kfree(dev);
  53 }
  54
  55 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  56 {
  57         struct mtd_blktrans_dev *dev;
  58
  59         mutex_lock(&blktrans_ref_mutex);
  60         dev = disk->private_data;
  61
  62         if (!dev)
  63                 goto unlock;
  64         kref_get(&dev->ref);
  65 unlock:
  66         mutex_unlock(&blktrans_ref_mutex);
  67         return dev;
  68 }
  69
  70 static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  71 {
  72         mutex_lock(&blktrans_ref_mutex);
  73         kref_put(&dev->ref, blktrans_dev_release);
  74         mutex_unlock(&blktrans_ref_mutex);
  75 }
  76
  77
  78 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  79                                struct mtd_blktrans_dev *dev,
  80                                struct request *req)
  81 {
  82         unsigned long block, nsect;
  83         char *buf;
  84
  85         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  86         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  87
  88         buf = req->buffer;
  89
  90         if (req->cmd_type != REQ_TYPE_FS)
  91                 return -EIO;
  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         if (kthread_should_stop())
 125                 return 1;
 126
 127         return dev->bg_stop;
 128 }
 129 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
 130
 131 static int mtd_blktrans_thread(void *arg)
 132 {
 133         struct mtd_blktrans_dev *dev = arg;
 134         struct mtd_blktrans_ops *tr = dev->tr;
 135         struct request_queue *rq = dev->rq;
 136         struct request *req = NULL;
 137         int background_done = 0;
 138
 139         spin_lock_irq(rq->queue_lock);
 140
 141         while (!kthread_should_stop()) {
 142                 int res;
 143
 144                 dev->bg_stop = false;
 145                 if (!req && !(req = blk_fetch_request(rq))) {
 146                         if (tr->background && !background_done) {
 147                                 spin_unlock_irq(rq->queue_lock);
 148                                 mutex_lock(&dev->lock);
 149                                 tr->background(dev);
 150                                 mutex_unlock(&dev->lock);
 151                                 spin_lock_irq(rq->queue_lock);
 152                                 /*
 153                                  * Do background processing just once per idle
 154                                  * period.
 155                                  */
 156                                 background_done = !dev->bg_stop;
 157                                 continue;
 158                         }
 159                         set_current_state(TASK_INTERRUPTIBLE);
 160
 161                         if (kthread_should_stop())
 162                                 set_current_state(TASK_RUNNING);
 163
 164                         spin_unlock_irq(rq->queue_lock);
 165                         schedule();
 166                         spin_lock_irq(rq->queue_lock);
 167                         continue;
 168                 }
 169
 170                 spin_unlock_irq(rq->queue_lock);
 171
 172                 mutex_lock(&dev->lock);
 173                 res = do_blktrans_request(dev->tr, dev, req);
 174                 mutex_unlock(&dev->lock);
 175
 176                 spin_lock_irq(rq->queue_lock);
 177
 178                 if (!__blk_end_request_cur(req, res))
 179                         req = NULL;
 180
 181                 background_done = 0;
 182         }
 183
 184         if (req)
 185                 __blk_end_request_all(req, -EIO);
 186
 187         spin_unlock_irq(rq->queue_lock);
 188
 189         return 0;
 190 }
 191
 192 static void mtd_blktrans_request(struct request_queue *rq)
 193 {
 194         struct mtd_blktrans_dev *dev;
 195         struct request *req = NULL;
 196
 197         dev = rq->queuedata;
 198
 199         if (!dev)
 200                 while ((req = blk_fetch_request(rq)) != NULL)
 201                         __blk_end_request_all(req, -ENODEV);
 202         else {
 203                 dev->bg_stop = true;
 204                 wake_up_process(dev->thread);
 205         }
 206 }
 207
 208 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 209 {
 210         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 211         int ret = 0;
 212
 213         if (!dev)
 214                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 215
 216         mutex_lock(&dev->lock);
 217
 218         if (dev->open)
 219                 goto unlock;
 220
 221         kref_get(&dev->ref);
 222         __module_get(dev->tr->owner);
 223
 224         if (!dev->mtd)
 225                 goto unlock;
 226
 227         if (dev->tr->open) {
 228                 ret = dev->tr->open(dev);
 229                 if (ret)
 230                         goto error_put;
 231         }
 232
 233         ret = __get_mtd_device(dev->mtd);
 234         if (ret)
 235                 goto error_release;
 236
 237 unlock:
 238         dev->open++;
 239         mutex_unlock(&dev->lock);
 240         blktrans_dev_put(dev);
 241         return ret;
 242
 243 error_release:
 244         if (dev->tr->release)
 245                 dev->tr->release(dev);
 246 error_put:
 247         module_put(dev->tr->owner);
 248         kref_put(&dev->ref, blktrans_dev_release);
 249         mutex_unlock(&dev->lock);
 250         blktrans_dev_put(dev);
 251         return ret;
 252 }
 253
 254 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 255 {
 256         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 257         int ret = 0;
 258
 259         if (!dev)
 260                 return ret;
 261
 262         mutex_lock(&dev->lock);
 263
 264         if (--dev->open)
 265                 goto unlock;
 266
 267         kref_put(&dev->ref, blktrans_dev_release);
 268         module_put(dev->tr->owner);
 269
 270         if (dev->mtd) {
 271                 ret = dev->tr->release ? dev->tr->release(dev) : 0;
 272                 __put_mtd_device(dev->mtd);
 273         }
 274 unlock:
 275         mutex_unlock(&dev->lock);
 276         blktrans_dev_put(dev);
 277         return ret;
 278 }
 279
 280 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 281 {
 282         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 283         int ret = -ENXIO;
 284
 285         if (!dev)
 286                 return ret;
 287
 288         mutex_lock(&dev->lock);
 289
 290         if (!dev->mtd)
 291                 goto unlock;
 292
 293         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 294 unlock:
 295         mutex_unlock(&dev->lock);
 296         blktrans_dev_put(dev);
 297         return ret;
 298 }
 299
 300 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 301                               unsigned int cmd, unsigned long arg)
 302 {
 303         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 304         int ret = -ENXIO;
 305
 306         if (!dev)
 307                 return ret;
 308
 309         mutex_lock(&dev->lock);
 310
 311         if (!dev->mtd)
 312                 goto unlock;
 313
 314         switch (cmd) {
 315         case BLKFLSBUF:
 316                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 317                 break;
 318         default:
 319                 ret = -ENOTTY;
 320         }
 321 unlock:
 322         mutex_unlock(&dev->lock);
 323         blktrans_dev_put(dev);
 324         return ret;
 325 }
 326
 327 static const struct block_device_operations mtd_blktrans_ops = {
 328         .owner          = THIS_MODULE,
 329         .open           = blktrans_open,
 330         .release        = blktrans_release,
 331         .ioctl          = blktrans_ioctl,
 332         .getgeo         = blktrans_getgeo,
 333 };
 334
 335 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 336 {
 337         struct mtd_blktrans_ops *tr = new->tr;
 338         struct mtd_blktrans_dev *d;
 339         int last_devnum = -1;
 340         struct gendisk *gd;
 341         int ret;
 342
 343         if (mutex_trylock(&mtd_table_mutex)) {
 344                 mutex_unlock(&mtd_table_mutex);
 345                 BUG();
 346         }
 347
 348         mutex_lock(&blktrans_ref_mutex);
 349         list_for_each_entry(d, &tr->devs, list) {
 350                 if (new->devnum == -1) {
 351                         /* Use first free number */
 352                         if (d->devnum != last_devnum+1) {
 353                                 /* Found a free devnum. Plug it in here */
 354                                 new->devnum = last_devnum+1;
 355                                 list_add_tail(&new->list, &d->list);
 356                                 goto added;
 357                         }
 358                 } else if (d->devnum == new->devnum) {
 359                         /* Required number taken */
 360                         mutex_unlock(&blktrans_ref_mutex);
 361                         return -EBUSY;
 362                 } else if (d->devnum > new->devnum) {
 363                         /* Required number was free */
 364                         list_add_tail(&new->list, &d->list);
 365                         goto added;
 366                 }
 367                 last_devnum = d->devnum;
 368         }
 369
 370         ret = -EBUSY;
 371         if (new->devnum == -1)
 372                 new->devnum = last_devnum+1;
 373
 374         /* Check that the device and any partitions will get valid
 375          * minor numbers and that the disk naming code below can cope
 376          * with this number. */
 377         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 378             (tr->part_bits && new->devnum >= 27 * 26)) {
 379                 mutex_unlock(&blktrans_ref_mutex);
 380                 goto error1;
 381         }
 382
 383         list_add_tail(&new->list, &tr->devs);
 384  added:
 385         mutex_unlock(&blktrans_ref_mutex);
 386
 387         mutex_init(&new->lock);
 388         kref_init(&new->ref);
 389         if (!tr->writesect)
 390                 new->readonly = 1;
 391
 392         /* Create gendisk */
 393         ret = -ENOMEM;
 394         gd = alloc_disk(1 << tr->part_bits);
 395
 396         if (!gd)
 397                 goto error2;
 398
 399         new->disk = gd;
 400         gd->private_data = new;
 401         gd->major = tr->major;
 402         gd->first_minor = (new->devnum) << tr->part_bits;
 403         gd->fops = &mtd_blktrans_ops;
 404
 405         if (tr->part_bits)
 406                 if (new->devnum < 26)
 407                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 408                                  "%s%c", tr->name, 'a' + new->devnum);
 409                 else
 410                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 411                                  "%s%c%c", tr->name,
 412                                  'a' - 1 + new->devnum / 26,
 413                                  'a' + new->devnum % 26);
 414         else
 415                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 416                          "%s%d", tr->name, new->devnum);
 417
 418         set_capacity(gd, (new->size * tr->blksize) >> 9);
 419
 420         /* Create the request queue */
 421         spin_lock_init(&new->queue_lock);
 422         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 423
 424         if (!new->rq)
 425                 goto error3;
 426
 427         new->rq->queuedata = new;
 428         blk_queue_logical_block_size(new->rq, tr->blksize);
 429
 430         if (tr->discard) {
 431                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
 432                 new->rq->limits.max_discard_sectors = UINT_MAX;
 433         }
 434
 435         gd->queue = new->rq;
 436
 437         /* Create processing thread */
 438         /* TODO: workqueue ? */
 439         new->thread = kthread_run(mtd_blktrans_thread, new,
 440                         "%s%d", tr->name, new->mtd->index);
 441         if (IS_ERR(new->thread)) {
 442                 ret = PTR_ERR(new->thread);
 443                 goto error4;
 444         }
 445         gd->driverfs_dev = &new->mtd->dev;
 446
 447         if (new->readonly)
 448                 set_disk_ro(gd, 1);
 449
 450         add_disk(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
 485         /* Stop the thread */
 486         kthread_stop(old->thread);
 487
 488         /* Kill current requests */
 489         spin_lock_irqsave(&old->queue_lock, flags);
 490         old->rq->queuedata = NULL;
 491         blk_start_queue(old->rq);
 492         spin_unlock_irqrestore(&old->queue_lock, flags);
 493
 494         /* If the device is currently open, tell trans driver to close it,
 495                 then put mtd device, and don't touch it again */
 496         mutex_lock(&old->lock);
 497         if (old->open) {
 498                 if (old->tr->release)
 499                         old->tr->release(old);
 500                 __put_mtd_device(old->mtd);
 501         }
 502
 503         old->mtd = NULL;
 504
 505         mutex_unlock(&old->lock);
 506         blktrans_dev_put(old);
 507         return 0;
 508 }
 509
 510 static void blktrans_notify_remove(struct mtd_info *mtd)
 511 {
 512         struct mtd_blktrans_ops *tr;
 513         struct mtd_blktrans_dev *dev, *next;
 514
 515         list_for_each_entry(tr, &blktrans_majors, list)
 516                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 517                         if (dev->mtd == mtd)
 518                                 tr->remove_dev(dev);
 519 }
 520
 521 static void blktrans_notify_add(struct mtd_info *mtd)
 522 {
 523         struct mtd_blktrans_ops *tr;
 524
 525         if (mtd->type == MTD_ABSENT)
 526                 return;
 527
 528         list_for_each_entry(tr, &blktrans_majors, list)
 529                 tr->add_mtd(tr, mtd);
 530 }
 531
 532 static struct mtd_notifier blktrans_notifier = {
 533         .add = blktrans_notify_add,
 534         .remove = blktrans_notify_remove,
 535 };
 536
 537 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 538 {
 539         struct mtd_info *mtd;
 540         int ret;
 541
 542         /* Register the notifier if/when the first device type is
 543            registered, to prevent the link/init ordering from fucking
 544            us over. */
 545         if (!blktrans_notifier.list.next)
 546                 register_mtd_user(&blktrans_notifier);
 547
 548
 549         mutex_lock(&mtd_table_mutex);
 550
 551         ret = register_blkdev(tr->major, tr->name);
 552         if (ret < 0) {
 553                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 554                        tr->name, tr->major, ret);
 555                 mutex_unlock(&mtd_table_mutex);
 556                 return ret;
 557         }
 558
 559         if (ret)
 560                 tr->major = ret;
 561
 562         tr->blkshift = ffs(tr->blksize) - 1;
 563
 564         INIT_LIST_HEAD(&tr->devs);
 565         list_add(&tr->list, &blktrans_majors);
 566
 567         mtd_for_each_device(mtd)
 568                 if (mtd->type != MTD_ABSENT)
 569                         tr->add_mtd(tr, mtd);
 570
 571         mutex_unlock(&mtd_table_mutex);
 572         return 0;
 573 }
 574
 575 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 576 {
 577         struct mtd_blktrans_dev *dev, *next;
 578
 579         mutex_lock(&mtd_table_mutex);
 580
 581         /* Remove it from the list of active majors */
 582         list_del(&tr->list);
 583
 584         list_for_each_entry_safe(dev, next, &tr->devs, list)
 585                 tr->remove_dev(dev);
 586
 587         unregister_blkdev(tr->major, tr->name);
 588         mutex_unlock(&mtd_table_mutex);
 589
 590         BUG_ON(!list_empty(&tr->devs));
 591         return 0;
 592 }
 593
 594 static void __exit mtd_blktrans_exit(void)
 595 {
 596         /* No race here -- if someone's currently in register_mtd_blktrans
 597            we're screwed anyway. */
 598         if (blktrans_notifier.list.next)
 599                 unregister_mtd_user(&blktrans_notifier);
 600 }
 601
 602 module_exit(mtd_blktrans_exit);
 603
 604 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 605 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 606 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 607 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 608
 609 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 610 MODULE_LICENSE("GPL");
 611 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");