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 DEFINE_MUTEX(mtd_blkdevs_mutex);
  41 static LIST_HEAD(blktrans_majors);
  42 static DEFINE_MUTEX(blktrans_ref_mutex);
  43
  44 void blktrans_dev_release(struct kref *kref)
  45 {
  46         struct mtd_blktrans_dev *dev =
  47                 container_of(kref, struct mtd_blktrans_dev, ref);
  48
  49         dev->disk->private_data = NULL;
  50         blk_cleanup_queue(dev->rq);
  51         put_disk(dev->disk);
  52         list_del(&dev->list);
  53         kfree(dev);
  54 }
  55
  56 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  57 {
  58         struct mtd_blktrans_dev *dev;
  59
  60         mutex_lock(&blktrans_ref_mutex);
  61         dev = disk->private_data;
  62
  63         if (!dev)
  64                 goto unlock;
  65         kref_get(&dev->ref);
  66 unlock:
  67         mutex_unlock(&blktrans_ref_mutex);
  68         return dev;
  69 }
  70
  71 void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  72 {
  73         mutex_lock(&blktrans_ref_mutex);
  74         kref_put(&dev->ref, blktrans_dev_release);
  75         mutex_unlock(&blktrans_ref_mutex);
  76 }
  77
  78
  79 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  80                                struct mtd_blktrans_dev *dev,
  81                                struct request *req)
  82 {
  83         unsigned long block, nsect;
  84         char *buf;
  85
  86         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  87         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  88
  89         buf = req->buffer;
  90
  91         if (req->cmd_type != REQ_TYPE_FS)
  92                 return -EIO;
  93
  94         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  95             get_capacity(req->rq_disk))
  96                 return -EIO;
  97
  98         if (req->cmd_flags & REQ_DISCARD)
  99                 return tr->discard(dev, block, nsect);
 100
 101         switch(rq_data_dir(req)) {
 102         case READ:
 103                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 104                         if (tr->readsect(dev, block, buf))
 105                                 return -EIO;
 106                 rq_flush_dcache_pages(req);
 107                 return 0;
 108         case WRITE:
 109                 if (!tr->writesect)
 110                         return -EIO;
 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 -EIO;
 116                 return 0;
 117         default:
 118                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
 119                 return -EIO;
 120         }
 121 }
 122
 123 static int mtd_blktrans_thread(void *arg)
 124 {
 125         struct mtd_blktrans_dev *dev = arg;
 126         struct request_queue *rq = dev->rq;
 127         struct request *req = NULL;
 128
 129         spin_lock_irq(rq->queue_lock);
 130
 131         while (!kthread_should_stop()) {
 132                 int res;
 133
 134                 if (!req && !(req = blk_fetch_request(rq))) {
 135                         set_current_state(TASK_INTERRUPTIBLE);
 136
 137                         if (kthread_should_stop())
 138                                 set_current_state(TASK_RUNNING);
 139
 140                         spin_unlock_irq(rq->queue_lock);
 141                         schedule();
 142                         spin_lock_irq(rq->queue_lock);
 143                         continue;
 144                 }
 145
 146                 spin_unlock_irq(rq->queue_lock);
 147
 148                 mutex_lock(&dev->lock);
 149                 res = do_blktrans_request(dev->tr, dev, req);
 150                 mutex_unlock(&dev->lock);
 151
 152                 spin_lock_irq(rq->queue_lock);
 153
 154                 if (!__blk_end_request_cur(req, res))
 155                         req = NULL;
 156         }
 157
 158         if (req)
 159                 __blk_end_request_all(req, -EIO);
 160
 161         spin_unlock_irq(rq->queue_lock);
 162
 163         return 0;
 164 }
 165
 166 static void mtd_blktrans_request(struct request_queue *rq)
 167 {
 168         struct mtd_blktrans_dev *dev;
 169         struct request *req = NULL;
 170
 171         dev = rq->queuedata;
 172
 173         if (!dev)
 174                 while ((req = blk_fetch_request(rq)) != NULL)
 175                         __blk_end_request_all(req, -ENODEV);
 176         else
 177                 wake_up_process(dev->thread);
 178 }
 179
 180 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 181 {
 182         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 183         int ret = 0;
 184
 185         if (!dev)
 186                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 187
 188         mutex_lock(&mtd_blkdevs_mutex);
 189         mutex_lock(&dev->lock);
 190
 191         if (dev->open++)
 192                 goto unlock;
 193
 194         kref_get(&dev->ref);
 195         __module_get(dev->tr->owner);
 196
 197         if (dev->mtd) {
 198                 ret = dev->tr->open ? dev->tr->open(dev) : 0;
 199                 __get_mtd_device(dev->mtd);
 200         }
 201
 202 unlock:
 203         mutex_unlock(&dev->lock);
 204         blktrans_dev_put(dev);
 205         mutex_unlock(&mtd_blkdevs_mutex);
 206         return ret;
 207 }
 208
 209 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 210 {
 211         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 212         int ret = 0;
 213
 214         if (!dev)
 215                 return ret;
 216
 217         mutex_lock(&mtd_blkdevs_mutex);
 218         mutex_lock(&dev->lock);
 219
 220         if (--dev->open)
 221                 goto unlock;
 222
 223         kref_put(&dev->ref, blktrans_dev_release);
 224         module_put(dev->tr->owner);
 225
 226         if (dev->mtd) {
 227                 ret = dev->tr->release ? dev->tr->release(dev) : 0;
 228                 __put_mtd_device(dev->mtd);
 229         }
 230 unlock:
 231         mutex_unlock(&dev->lock);
 232         blktrans_dev_put(dev);
 233         mutex_unlock(&mtd_blkdevs_mutex);
 234         return ret;
 235 }
 236
 237 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 238 {
 239         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 240         int ret = -ENXIO;
 241
 242         if (!dev)
 243                 return ret;
 244
 245         mutex_lock(&dev->lock);
 246
 247         if (!dev->mtd)
 248                 goto unlock;
 249
 250         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 251 unlock:
 252         mutex_unlock(&dev->lock);
 253         blktrans_dev_put(dev);
 254         return ret;
 255 }
 256
 257 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 258                               unsigned int cmd, unsigned long arg)
 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(&mtd_blkdevs_mutex);
 267         mutex_lock(&dev->lock);
 268
 269         if (!dev->mtd)
 270                 goto unlock;
 271
 272         switch (cmd) {
 273         case BLKFLSBUF:
 274                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 275                 break;
 276         default:
 277                 ret = -ENOTTY;
 278         }
 279 unlock:
 280         mutex_unlock(&dev->lock);
 281         mutex_unlock(&mtd_blkdevs_mutex);
 282         blktrans_dev_put(dev);
 283         return ret;
 284 }
 285
 286 static const struct block_device_operations mtd_blktrans_ops = {
 287         .owner          = THIS_MODULE,
 288         .open           = blktrans_open,
 289         .release        = blktrans_release,
 290         .ioctl          = blktrans_ioctl,
 291         .getgeo         = blktrans_getgeo,
 292 };
 293
 294 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 295 {
 296         struct mtd_blktrans_ops *tr = new->tr;
 297         struct mtd_blktrans_dev *d;
 298         int last_devnum = -1;
 299         struct gendisk *gd;
 300         int ret;
 301
 302         if (mutex_trylock(&mtd_table_mutex)) {
 303                 mutex_unlock(&mtd_table_mutex);
 304                 BUG();
 305         }
 306
 307         mutex_lock(&blktrans_ref_mutex);
 308         list_for_each_entry(d, &tr->devs, list) {
 309                 if (new->devnum == -1) {
 310                         /* Use first free number */
 311                         if (d->devnum != last_devnum+1) {
 312                                 /* Found a free devnum. Plug it in here */
 313                                 new->devnum = last_devnum+1;
 314                                 list_add_tail(&new->list, &d->list);
 315                                 goto added;
 316                         }
 317                 } else if (d->devnum == new->devnum) {
 318                         /* Required number taken */
 319                         mutex_unlock(&blktrans_ref_mutex);
 320                         return -EBUSY;
 321                 } else if (d->devnum > new->devnum) {
 322                         /* Required number was free */
 323                         list_add_tail(&new->list, &d->list);
 324                         goto added;
 325                 }
 326                 last_devnum = d->devnum;
 327         }
 328
 329         ret = -EBUSY;
 330         if (new->devnum == -1)
 331                 new->devnum = last_devnum+1;
 332
 333         /* Check that the device and any partitions will get valid
 334          * minor numbers and that the disk naming code below can cope
 335          * with this number. */
 336         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 337             (tr->part_bits && new->devnum >= 27 * 26)) {
 338                 mutex_unlock(&blktrans_ref_mutex);
 339                 goto error1;
 340         }
 341
 342         list_add_tail(&new->list, &tr->devs);
 343  added:
 344         mutex_unlock(&blktrans_ref_mutex);
 345
 346         mutex_init(&new->lock);
 347         kref_init(&new->ref);
 348         if (!tr->writesect)
 349                 new->readonly = 1;
 350
 351         /* Create gendisk */
 352         ret = -ENOMEM;
 353         gd = alloc_disk(1 << tr->part_bits);
 354
 355         if (!gd)
 356                 goto error2;
 357
 358         new->disk = gd;
 359         gd->private_data = new;
 360         gd->major = tr->major;
 361         gd->first_minor = (new->devnum) << tr->part_bits;
 362         gd->fops = &mtd_blktrans_ops;
 363
 364         if (tr->part_bits)
 365                 if (new->devnum < 26)
 366                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 367                                  "%s%c", tr->name, 'a' + new->devnum);
 368                 else
 369                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 370                                  "%s%c%c", tr->name,
 371                                  'a' - 1 + new->devnum / 26,
 372                                  'a' + new->devnum % 26);
 373         else
 374                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 375                          "%s%d", tr->name, new->devnum);
 376
 377         set_capacity(gd, (new->size * tr->blksize) >> 9);
 378
 379         /* Create the request queue */
 380         spin_lock_init(&new->queue_lock);
 381         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 382
 383         if (!new->rq)
 384                 goto error3;
 385
 386         new->rq->queuedata = new;
 387         blk_queue_logical_block_size(new->rq, tr->blksize);
 388
 389         if (tr->discard)
 390                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 391                                         new->rq);
 392
 393         gd->queue = new->rq;
 394
 395         /* Create processing thread */
 396         /* TODO: workqueue ? */
 397         new->thread = kthread_run(mtd_blktrans_thread, new,
 398                         "%s%d", tr->name, new->mtd->index);
 399         if (IS_ERR(new->thread)) {
 400                 ret = PTR_ERR(new->thread);
 401                 goto error4;
 402         }
 403         gd->driverfs_dev = &new->mtd->dev;
 404
 405         if (new->readonly)
 406                 set_disk_ro(gd, 1);
 407
 408         add_disk(gd);
 409
 410         if (new->disk_attributes) {
 411                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 412                                         new->disk_attributes);
 413                 WARN_ON(ret);
 414         }
 415         return 0;
 416 error4:
 417         blk_cleanup_queue(new->rq);
 418 error3:
 419         put_disk(new->disk);
 420 error2:
 421         list_del(&new->list);
 422 error1:
 423         kfree(new);
 424         return ret;
 425 }
 426
 427 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 428 {
 429         unsigned long flags;
 430
 431         if (mutex_trylock(&mtd_table_mutex)) {
 432                 mutex_unlock(&mtd_table_mutex);
 433                 BUG();
 434         }
 435
 436         if (old->disk_attributes)
 437                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 438                                                 old->disk_attributes);
 439
 440         /* Stop new requests to arrive */
 441         del_gendisk(old->disk);
 442
 443
 444         /* Stop the thread */
 445         kthread_stop(old->thread);
 446
 447         /* Kill current requests */
 448         spin_lock_irqsave(&old->queue_lock, flags);
 449         old->rq->queuedata = NULL;
 450         blk_start_queue(old->rq);
 451         spin_unlock_irqrestore(&old->queue_lock, flags);
 452
 453         /* If the device is currently open, tell trans driver to close it,
 454                 then put mtd device, and don't touch it again */
 455         mutex_lock(&old->lock);
 456         if (old->open) {
 457                 if (old->tr->release)
 458                         old->tr->release(old);
 459                 __put_mtd_device(old->mtd);
 460         }
 461
 462         old->mtd = NULL;
 463
 464         mutex_unlock(&old->lock);
 465         blktrans_dev_put(old);
 466         return 0;
 467 }
 468
 469 static void blktrans_notify_remove(struct mtd_info *mtd)
 470 {
 471         struct mtd_blktrans_ops *tr;
 472         struct mtd_blktrans_dev *dev, *next;
 473
 474         list_for_each_entry(tr, &blktrans_majors, list)
 475                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 476                         if (dev->mtd == mtd)
 477                                 tr->remove_dev(dev);
 478 }
 479
 480 static void blktrans_notify_add(struct mtd_info *mtd)
 481 {
 482         struct mtd_blktrans_ops *tr;
 483
 484         if (mtd->type == MTD_ABSENT)
 485                 return;
 486
 487         list_for_each_entry(tr, &blktrans_majors, list)
 488                 tr->add_mtd(tr, mtd);
 489 }
 490
 491 static struct mtd_notifier blktrans_notifier = {
 492         .add = blktrans_notify_add,
 493         .remove = blktrans_notify_remove,
 494 };
 495
 496 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 497 {
 498         struct mtd_info *mtd;
 499         int ret;
 500
 501         /* Register the notifier if/when the first device type is
 502            registered, to prevent the link/init ordering from fucking
 503            us over. */
 504         if (!blktrans_notifier.list.next)
 505                 register_mtd_user(&blktrans_notifier);
 506
 507
 508         mutex_lock(&mtd_table_mutex);
 509
 510         ret = register_blkdev(tr->major, tr->name);
 511         if (ret < 0) {
 512                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 513                        tr->name, tr->major, ret);
 514                 mutex_unlock(&mtd_table_mutex);
 515                 return ret;
 516         }
 517
 518         if (ret)
 519                 tr->major = ret;
 520
 521         tr->blkshift = ffs(tr->blksize) - 1;
 522
 523         INIT_LIST_HEAD(&tr->devs);
 524         list_add(&tr->list, &blktrans_majors);
 525
 526         mtd_for_each_device(mtd)
 527                 if (mtd->type != MTD_ABSENT)
 528                         tr->add_mtd(tr, mtd);
 529
 530         mutex_unlock(&mtd_table_mutex);
 531         return 0;
 532 }
 533
 534 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 535 {
 536         struct mtd_blktrans_dev *dev, *next;
 537
 538         mutex_lock(&mtd_table_mutex);
 539
 540         /* Remove it from the list of active majors */
 541         list_del(&tr->list);
 542
 543         list_for_each_entry_safe(dev, next, &tr->devs, list)
 544                 tr->remove_dev(dev);
 545
 546         unregister_blkdev(tr->major, tr->name);
 547         mutex_unlock(&mtd_table_mutex);
 548
 549         BUG_ON(!list_empty(&tr->devs));
 550         return 0;
 551 }
 552
 553 static void __exit mtd_blktrans_exit(void)
 554 {
 555         /* No race here -- if someone's currently in register_mtd_blktrans
 556            we're screwed anyway. */
 557         if (blktrans_notifier.list.next)
 558                 unregister_mtd_user(&blktrans_notifier);
 559 }
 560
 561 module_exit(mtd_blktrans_exit);
 562
 563 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 564 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 565 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 566 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 567
 568 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 569 MODULE_LICENSE("GPL");
 570 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");