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(&mtd_table_mutex);
 217         mutex_lock(&dev->lock);
 218
 219         if (dev->open)
 220                 goto unlock;
 221
 222         kref_get(&dev->ref);
 223         __module_get(dev->tr->owner);
 224
 225         if (!dev->mtd)
 226                 goto unlock;
 227
 228         if (dev->tr->open) {
 229                 ret = dev->tr->open(dev);
 230                 if (ret)
 231                         goto error_put;
 232         }
 233
 234         ret = __get_mtd_device(dev->mtd);
 235         if (ret)
 236                 goto error_release;
 237
 238 unlock:
 239         dev->open++;
 240         mutex_unlock(&dev->lock);
 241         mutex_unlock(&mtd_table_mutex);
 242         blktrans_dev_put(dev);
 243         return ret;
 244
 245 error_release:
 246         if (dev->tr->release)
 247                 dev->tr->release(dev);
 248 error_put:
 249         module_put(dev->tr->owner);
 250         kref_put(&dev->ref, blktrans_dev_release);
 251         mutex_unlock(&dev->lock);
 252         mutex_unlock(&mtd_table_mutex);
 253         blktrans_dev_put(dev);
 254         return ret;
 255 }
 256
 257 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 258 {
 259         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 260         int ret = 0;
 261
 262         if (!dev)
 263                 return ret;
 264
 265         mutex_lock(&mtd_table_mutex);
 266         mutex_lock(&dev->lock);
 267
 268         if (--dev->open)
 269                 goto unlock;
 270
 271         kref_put(&dev->ref, blktrans_dev_release);
 272         module_put(dev->tr->owner);
 273
 274         if (dev->mtd) {
 275                 ret = dev->tr->release ? dev->tr->release(dev) : 0;
 276                 __put_mtd_device(dev->mtd);
 277         }
 278 unlock:
 279         mutex_unlock(&dev->lock);
 280         mutex_unlock(&mtd_table_mutex);
 281         blktrans_dev_put(dev);
 282         return ret;
 283 }
 284
 285 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 286 {
 287         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 288         int ret = -ENXIO;
 289
 290         if (!dev)
 291                 return ret;
 292
 293         mutex_lock(&dev->lock);
 294
 295         if (!dev->mtd)
 296                 goto unlock;
 297
 298         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 299 unlock:
 300         mutex_unlock(&dev->lock);
 301         blktrans_dev_put(dev);
 302         return ret;
 303 }
 304
 305 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 306                               unsigned int cmd, unsigned long arg)
 307 {
 308         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 309         int ret = -ENXIO;
 310
 311         if (!dev)
 312                 return ret;
 313
 314         mutex_lock(&dev->lock);
 315
 316         if (!dev->mtd)
 317                 goto unlock;
 318
 319         switch (cmd) {
 320         case BLKFLSBUF:
 321                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 322                 break;
 323         default:
 324                 ret = -ENOTTY;
 325         }
 326 unlock:
 327         mutex_unlock(&dev->lock);
 328         blktrans_dev_put(dev);
 329         return ret;
 330 }
 331
 332 static const struct block_device_operations mtd_blktrans_ops = {
 333         .owner          = THIS_MODULE,
 334         .open           = blktrans_open,
 335         .release        = blktrans_release,
 336         .ioctl          = blktrans_ioctl,
 337         .getgeo         = blktrans_getgeo,
 338 };
 339
 340 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 341 {
 342         struct mtd_blktrans_ops *tr = new->tr;
 343         struct mtd_blktrans_dev *d;
 344         int last_devnum = -1;
 345         struct gendisk *gd;
 346         int ret;
 347
 348         if (mutex_trylock(&mtd_table_mutex)) {
 349                 mutex_unlock(&mtd_table_mutex);
 350                 BUG();
 351         }
 352
 353         mutex_lock(&blktrans_ref_mutex);
 354         list_for_each_entry(d, &tr->devs, list) {
 355                 if (new->devnum == -1) {
 356                         /* Use first free number */
 357                         if (d->devnum != last_devnum+1) {
 358                                 /* Found a free devnum. Plug it in here */
 359                                 new->devnum = last_devnum+1;
 360                                 list_add_tail(&new->list, &d->list);
 361                                 goto added;
 362                         }
 363                 } else if (d->devnum == new->devnum) {
 364                         /* Required number taken */
 365                         mutex_unlock(&blktrans_ref_mutex);
 366                         return -EBUSY;
 367                 } else if (d->devnum > new->devnum) {
 368                         /* Required number was free */
 369                         list_add_tail(&new->list, &d->list);
 370                         goto added;
 371                 }
 372                 last_devnum = d->devnum;
 373         }
 374
 375         ret = -EBUSY;
 376         if (new->devnum == -1)
 377                 new->devnum = last_devnum+1;
 378
 379         /* Check that the device and any partitions will get valid
 380          * minor numbers and that the disk naming code below can cope
 381          * with this number. */
 382         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 383             (tr->part_bits && new->devnum >= 27 * 26)) {
 384                 mutex_unlock(&blktrans_ref_mutex);
 385                 goto error1;
 386         }
 387
 388         list_add_tail(&new->list, &tr->devs);
 389  added:
 390         mutex_unlock(&blktrans_ref_mutex);
 391
 392         mutex_init(&new->lock);
 393         kref_init(&new->ref);
 394         if (!tr->writesect)
 395                 new->readonly = 1;
 396
 397         /* Create gendisk */
 398         ret = -ENOMEM;
 399         gd = alloc_disk(1 << tr->part_bits);
 400
 401         if (!gd)
 402                 goto error2;
 403
 404         new->disk = gd;
 405         gd->private_data = new;
 406         gd->major = tr->major;
 407         gd->first_minor = (new->devnum) << tr->part_bits;
 408         gd->fops = &mtd_blktrans_ops;
 409
 410         if (tr->part_bits)
 411                 if (new->devnum < 26)
 412                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 413                                  "%s%c", tr->name, 'a' + new->devnum);
 414                 else
 415                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 416                                  "%s%c%c", tr->name,
 417                                  'a' - 1 + new->devnum / 26,
 418                                  'a' + new->devnum % 26);
 419         else
 420                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 421                          "%s%d", tr->name, new->devnum);
 422
 423         set_capacity(gd, (new->size * tr->blksize) >> 9);
 424
 425         /* Create the request queue */
 426         spin_lock_init(&new->queue_lock);
 427         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 428
 429         if (!new->rq)
 430                 goto error3;
 431
 432         new->rq->queuedata = new;
 433         blk_queue_logical_block_size(new->rq, tr->blksize);
 434
 435         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
 436
 437         if (tr->discard) {
 438                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
 439                 new->rq->limits.max_discard_sectors = UINT_MAX;
 440         }
 441
 442         gd->queue = new->rq;
 443
 444         /* Create processing thread */
 445         /* TODO: workqueue ? */
 446         new->thread = kthread_run(mtd_blktrans_thread, new,
 447                         "%s%d", tr->name, new->mtd->index);
 448         if (IS_ERR(new->thread)) {
 449                 ret = PTR_ERR(new->thread);
 450                 goto error4;
 451         }
 452         gd->driverfs_dev = &new->mtd->dev;
 453
 454         if (new->readonly)
 455                 set_disk_ro(gd, 1);
 456
 457         add_disk(gd);
 458
 459         if (new->disk_attributes) {
 460                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 461                                         new->disk_attributes);
 462                 WARN_ON(ret);
 463         }
 464         return 0;
 465 error4:
 466         blk_cleanup_queue(new->rq);
 467 error3:
 468         put_disk(new->disk);
 469 error2:
 470         list_del(&new->list);
 471 error1:
 472         return ret;
 473 }
 474
 475 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 476 {
 477         unsigned long flags;
 478
 479         if (mutex_trylock(&mtd_table_mutex)) {
 480                 mutex_unlock(&mtd_table_mutex);
 481                 BUG();
 482         }
 483
 484         if (old->disk_attributes)
 485                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 486                                                 old->disk_attributes);
 487
 488         /* Stop new requests to arrive */
 489         del_gendisk(old->disk);
 490
 491
 492         /* Stop the thread */
 493         kthread_stop(old->thread);
 494
 495         /* Kill current requests */
 496         spin_lock_irqsave(&old->queue_lock, flags);
 497         old->rq->queuedata = NULL;
 498         blk_start_queue(old->rq);
 499         spin_unlock_irqrestore(&old->queue_lock, flags);
 500
 501         /* If the device is currently open, tell trans driver to close it,
 502                 then put mtd device, and don't touch it again */
 503         mutex_lock(&old->lock);
 504         if (old->open) {
 505                 if (old->tr->release)
 506                         old->tr->release(old);
 507                 __put_mtd_device(old->mtd);
 508         }
 509
 510         old->mtd = NULL;
 511
 512         mutex_unlock(&old->lock);
 513         blktrans_dev_put(old);
 514         return 0;
 515 }
 516
 517 static void blktrans_notify_remove(struct mtd_info *mtd)
 518 {
 519         struct mtd_blktrans_ops *tr;
 520         struct mtd_blktrans_dev *dev, *next;
 521
 522         list_for_each_entry(tr, &blktrans_majors, list)
 523                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 524                         if (dev->mtd == mtd)
 525                                 tr->remove_dev(dev);
 526 }
 527
 528 static void blktrans_notify_add(struct mtd_info *mtd)
 529 {
 530         struct mtd_blktrans_ops *tr;
 531
 532         if (mtd->type == MTD_ABSENT)
 533                 return;
 534
 535         list_for_each_entry(tr, &blktrans_majors, list)
 536                 tr->add_mtd(tr, mtd);
 537 }
 538
 539 static struct mtd_notifier blktrans_notifier = {
 540         .add = blktrans_notify_add,
 541         .remove = blktrans_notify_remove,
 542 };
 543
 544 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 545 {
 546         struct mtd_info *mtd;
 547         int ret;
 548
 549         /* Register the notifier if/when the first device type is
 550            registered, to prevent the link/init ordering from fucking
 551            us over. */
 552         if (!blktrans_notifier.list.next)
 553                 register_mtd_user(&blktrans_notifier);
 554
 555
 556         mutex_lock(&mtd_table_mutex);
 557
 558         ret = register_blkdev(tr->major, tr->name);
 559         if (ret < 0) {
 560                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 561                        tr->name, tr->major, ret);
 562                 mutex_unlock(&mtd_table_mutex);
 563                 return ret;
 564         }
 565
 566         if (ret)
 567                 tr->major = ret;
 568
 569         tr->blkshift = ffs(tr->blksize) - 1;
 570
 571         INIT_LIST_HEAD(&tr->devs);
 572         list_add(&tr->list, &blktrans_majors);
 573
 574         mtd_for_each_device(mtd)
 575                 if (mtd->type != MTD_ABSENT)
 576                         tr->add_mtd(tr, mtd);
 577
 578         mutex_unlock(&mtd_table_mutex);
 579         return 0;
 580 }
 581
 582 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 583 {
 584         struct mtd_blktrans_dev *dev, *next;
 585
 586         mutex_lock(&mtd_table_mutex);
 587
 588         /* Remove it from the list of active majors */
 589         list_del(&tr->list);
 590
 591         list_for_each_entry_safe(dev, next, &tr->devs, list)
 592                 tr->remove_dev(dev);
 593
 594         unregister_blkdev(tr->major, tr->name);
 595         mutex_unlock(&mtd_table_mutex);
 596
 597         BUG_ON(!list_empty(&tr->devs));
 598         return 0;
 599 }
 600
 601 static void __exit mtd_blktrans_exit(void)
 602 {
 603         /* No race here -- if someone's currently in register_mtd_blktrans
 604            we're screwed anyway. */
 605         if (blktrans_notifier.list.next)
 606                 unregister_mtd_user(&blktrans_notifier);
 607 }
 608
 609 module_exit(mtd_blktrans_exit);
 610
 611 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 612 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 613 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 614 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 615
 616 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 617 MODULE_LICENSE("GPL");
 618 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");