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