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