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