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                         spin_unlock_irq(rq->queue_lock);
 137                         schedule();
 138                         spin_lock_irq(rq->queue_lock);
 139                         continue;
 140                 }
 141
 142                 spin_unlock_irq(rq->queue_lock);
 143
 144                 mutex_lock(&dev->lock);
 145                 res = do_blktrans_request(dev->tr, dev, req);
 146                 mutex_unlock(&dev->lock);
 147
 148                 spin_lock_irq(rq->queue_lock);
 149
 150                 if (!__blk_end_request_cur(req, res))
 151                         req = NULL;
 152         }
 153
 154         if (req)
 155                 __blk_end_request_all(req, -EIO);
 156
 157         spin_unlock_irq(rq->queue_lock);
 158
 159         return 0;
 160 }
 161
 162 static void mtd_blktrans_request(struct request_queue *rq)
 163 {
 164         struct mtd_blktrans_dev *dev;
 165         struct request *req = NULL;
 166
 167         dev = rq->queuedata;
 168
 169         if (!dev)
 170                 while ((req = blk_fetch_request(rq)) != NULL)
 171                         __blk_end_request_all(req, -ENODEV);
 172         else
 173                 wake_up_process(dev->thread);
 174 }
 175
 176 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 177 {
 178         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 179         int ret;
 180
 181         if (!dev)
 182                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 183
 184         mutex_lock(&mtd_blkdevs_mutex);
 185         mutex_lock(&dev->lock);
 186
 187         if (!dev->mtd) {
 188                 ret = -ENXIO;
 189                 goto unlock;
 190         }
 191
 192         ret = !dev->open++ && dev->tr->open ? dev->tr->open(dev) : 0;
 193
 194         /* Take another reference on the device so it won't go away till
 195                 last release */
 196         if (!ret)
 197                 kref_get(&dev->ref);
 198 unlock:
 199         mutex_unlock(&dev->lock);
 200         blktrans_dev_put(dev);
 201         mutex_unlock(&mtd_blkdevs_mutex);
 202         return ret;
 203 }
 204
 205 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 206 {
 207         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 208         int ret = -ENXIO;
 209
 210         if (!dev)
 211                 return ret;
 212
 213         mutex_lock(&mtd_blkdevs_mutex);
 214         mutex_lock(&dev->lock);
 215
 216         /* Release one reference, we sure its not the last one here*/
 217         kref_put(&dev->ref, blktrans_dev_release);
 218
 219         if (!dev->mtd)
 220                 goto unlock;
 221
 222         ret = !--dev->open && dev->tr->release ? dev->tr->release(dev) : 0;
 223 unlock:
 224         mutex_unlock(&dev->lock);
 225         blktrans_dev_put(dev);
 226         mutex_unlock(&mtd_blkdevs_mutex);
 227         return ret;
 228 }
 229
 230 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 231 {
 232         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 233         int ret = -ENXIO;
 234
 235         if (!dev)
 236                 return ret;
 237
 238         mutex_lock(&dev->lock);
 239
 240         if (!dev->mtd)
 241                 goto unlock;
 242
 243         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 244 unlock:
 245         mutex_unlock(&dev->lock);
 246         blktrans_dev_put(dev);
 247         return ret;
 248 }
 249
 250 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 251                               unsigned int cmd, unsigned long arg)
 252 {
 253         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 254         int ret = -ENXIO;
 255
 256         if (!dev)
 257                 return ret;
 258
 259         mutex_lock(&mtd_blkdevs_mutex);
 260         mutex_lock(&dev->lock);
 261
 262         if (!dev->mtd)
 263                 goto unlock;
 264
 265         switch (cmd) {
 266         case BLKFLSBUF:
 267                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 268                 break;
 269         default:
 270                 ret = -ENOTTY;
 271         }
 272 unlock:
 273         mutex_unlock(&dev->lock);
 274         mutex_unlock(&mtd_blkdevs_mutex);
 275         blktrans_dev_put(dev);
 276         return ret;
 277 }
 278
 279 static const struct block_device_operations mtd_blktrans_ops = {
 280         .owner          = THIS_MODULE,
 281         .open           = blktrans_open,
 282         .release        = blktrans_release,
 283         .ioctl          = blktrans_ioctl,
 284         .getgeo         = blktrans_getgeo,
 285 };
 286
 287 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 288 {
 289         struct mtd_blktrans_ops *tr = new->tr;
 290         struct mtd_blktrans_dev *d;
 291         int last_devnum = -1;
 292         struct gendisk *gd;
 293         int ret;
 294
 295         if (mutex_trylock(&mtd_table_mutex)) {
 296                 mutex_unlock(&mtd_table_mutex);
 297                 BUG();
 298         }
 299
 300         mutex_lock(&blktrans_ref_mutex);
 301         list_for_each_entry(d, &tr->devs, list) {
 302                 if (new->devnum == -1) {
 303                         /* Use first free number */
 304                         if (d->devnum != last_devnum+1) {
 305                                 /* Found a free devnum. Plug it in here */
 306                                 new->devnum = last_devnum+1;
 307                                 list_add_tail(&new->list, &d->list);
 308                                 goto added;
 309                         }
 310                 } else if (d->devnum == new->devnum) {
 311                         /* Required number taken */
 312                         mutex_unlock(&blktrans_ref_mutex);
 313                         return -EBUSY;
 314                 } else if (d->devnum > new->devnum) {
 315                         /* Required number was free */
 316                         list_add_tail(&new->list, &d->list);
 317                         goto added;
 318                 }
 319                 last_devnum = d->devnum;
 320         }
 321
 322         ret = -EBUSY;
 323         if (new->devnum == -1)
 324                 new->devnum = last_devnum+1;
 325
 326         /* Check that the device and any partitions will get valid
 327          * minor numbers and that the disk naming code below can cope
 328          * with this number. */
 329         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 330             (tr->part_bits && new->devnum >= 27 * 26)) {
 331                 mutex_unlock(&blktrans_ref_mutex);
 332                 goto error1;
 333         }
 334
 335         list_add_tail(&new->list, &tr->devs);
 336  added:
 337         mutex_unlock(&blktrans_ref_mutex);
 338
 339         mutex_init(&new->lock);
 340         kref_init(&new->ref);
 341         if (!tr->writesect)
 342                 new->readonly = 1;
 343
 344         /* Create gendisk */
 345         ret = -ENOMEM;
 346         gd = alloc_disk(1 << tr->part_bits);
 347
 348         if (!gd)
 349                 goto error2;
 350
 351         new->disk = gd;
 352         gd->private_data = new;
 353         gd->major = tr->major;
 354         gd->first_minor = (new->devnum) << tr->part_bits;
 355         gd->fops = &mtd_blktrans_ops;
 356
 357         if (tr->part_bits)
 358                 if (new->devnum < 26)
 359                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 360                                  "%s%c", tr->name, 'a' + new->devnum);
 361                 else
 362                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 363                                  "%s%c%c", tr->name,
 364                                  'a' - 1 + new->devnum / 26,
 365                                  'a' + new->devnum % 26);
 366         else
 367                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 368                          "%s%d", tr->name, new->devnum);
 369
 370         set_capacity(gd, (new->size * tr->blksize) >> 9);
 371
 372         /* Create the request queue */
 373         spin_lock_init(&new->queue_lock);
 374         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 375
 376         if (!new->rq)
 377                 goto error3;
 378
 379         new->rq->queuedata = new;
 380         blk_queue_logical_block_size(new->rq, tr->blksize);
 381
 382         if (tr->discard)
 383                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 384                                         new->rq);
 385
 386         gd->queue = new->rq;
 387
 388         __get_mtd_device(new->mtd);
 389         __module_get(tr->owner);
 390
 391         /* Create processing thread */
 392         /* TODO: workqueue ? */
 393         new->thread = kthread_run(mtd_blktrans_thread, new,
 394                         "%s%d", tr->name, new->mtd->index);
 395         if (IS_ERR(new->thread)) {
 396                 ret = PTR_ERR(new->thread);
 397                 goto error4;
 398         }
 399         gd->driverfs_dev = &new->mtd->dev;
 400
 401         if (new->readonly)
 402                 set_disk_ro(gd, 1);
 403
 404         add_disk(gd);
 405
 406         if (new->disk_attributes) {
 407                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 408                                         new->disk_attributes);
 409                 WARN_ON(ret);
 410         }
 411         return 0;
 412 error4:
 413         module_put(tr->owner);
 414         __put_mtd_device(new->mtd);
 415         blk_cleanup_queue(new->rq);
 416 error3:
 417         put_disk(new->disk);
 418 error2:
 419         list_del(&new->list);
 420 error1:
 421         kfree(new);
 422         return ret;
 423 }
 424
 425 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 426 {
 427         unsigned long flags;
 428
 429         if (mutex_trylock(&mtd_table_mutex)) {
 430                 mutex_unlock(&mtd_table_mutex);
 431                 BUG();
 432         }
 433
 434         if (old->disk_attributes)
 435                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 436                                                 old->disk_attributes);
 437
 438         /* Stop new requests to arrive */
 439         del_gendisk(old->disk);
 440
 441
 442         /* Stop the thread */
 443         kthread_stop(old->thread);
 444
 445         /* Kill current requests */
 446         spin_lock_irqsave(&old->queue_lock, flags);
 447         old->rq->queuedata = NULL;
 448         blk_start_queue(old->rq);
 449         spin_unlock_irqrestore(&old->queue_lock, flags);
 450
 451         /* Ask trans driver for release to the mtd device */
 452         mutex_lock(&old->lock);
 453         if (old->open && old->tr->release) {
 454                 old->tr->release(old);
 455                 old->open = 0;
 456         }
 457
 458         __put_mtd_device(old->mtd);
 459         module_put(old->tr->owner);
 460
 461         /* At that point, we don't touch the mtd anymore */
 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) {
 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         tr->blkshift = ffs(tr->blksize) - 1;
 519
 520         INIT_LIST_HEAD(&tr->devs);
 521         list_add(&tr->list, &blktrans_majors);
 522
 523         mtd_for_each_device(mtd)
 524                 if (mtd->type != MTD_ABSENT)
 525                         tr->add_mtd(tr, mtd);
 526
 527         mutex_unlock(&mtd_table_mutex);
 528         return 0;
 529 }
 530
 531 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 532 {
 533         struct mtd_blktrans_dev *dev, *next;
 534
 535         mutex_lock(&mtd_table_mutex);
 536
 537         /* Remove it from the list of active majors */
 538         list_del(&tr->list);
 539
 540         list_for_each_entry_safe(dev, next, &tr->devs, list)
 541                 tr->remove_dev(dev);
 542
 543         unregister_blkdev(tr->major, tr->name);
 544         mutex_unlock(&mtd_table_mutex);
 545
 546         BUG_ON(!list_empty(&tr->devs));
 547         return 0;
 548 }
 549
 550 static void __exit mtd_blktrans_exit(void)
 551 {
 552         /* No race here -- if someone's currently in register_mtd_blktrans
 553            we're screwed anyway. */
 554         if (blktrans_notifier.list.next)
 555                 unregister_mtd_user(&blktrans_notifier);
 556 }
 557
 558 module_exit(mtd_blktrans_exit);
 559
 560 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 561 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 562 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 563 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 564
 565 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 566 MODULE_LICENSE("GPL");
 567 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");