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