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 LIST_HEAD(blktrans_majors);
  41 static DEFINE_MUTEX(blktrans_ref_mutex);
  42
  43 void blktrans_dev_release(struct kref *kref)
  44 {
  45         struct mtd_blktrans_dev *dev =
  46                 container_of(kref, struct mtd_blktrans_dev, ref);
  47
  48         dev->disk->private_data = NULL;
  49         blk_cleanup_queue(dev->rq);
  50         put_disk(dev->disk);
  51         list_del(&dev->list);
  52         kfree(dev);
  53 }
  54
  55 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  56 {
  57         struct mtd_blktrans_dev *dev;
  58
  59         mutex_lock(&blktrans_ref_mutex);
  60         dev = disk->private_data;
  61
  62         if (!dev)
  63                 goto unlock;
  64         kref_get(&dev->ref);
  65 unlock:
  66         mutex_unlock(&blktrans_ref_mutex);
  67         return dev;
  68 }
  69
  70 void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  71 {
  72         mutex_lock(&blktrans_ref_mutex);
  73         kref_put(&dev->ref, blktrans_dev_release);
  74         mutex_unlock(&blktrans_ref_mutex);
  75 }
  76
  77
  78 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  79                                struct mtd_blktrans_dev *dev,
  80                                struct request *req)
  81 {
  82         unsigned long block, nsect;
  83         char *buf;
  84
  85         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  86         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  87
  88         buf = req->buffer;
  89
  90         if (req->cmd_type != REQ_TYPE_FS)
  91                 return -EIO;
  92
  93         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  94             get_capacity(req->rq_disk))
  95                 return -EIO;
  96
  97         if (req->cmd_flags & REQ_DISCARD)
  98                 return tr->discard(dev, block, nsect);
  99
 100         switch(rq_data_dir(req)) {
 101         case READ:
 102                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 103                         if (tr->readsect(dev, block, buf))
 104                                 return -EIO;
 105                 rq_flush_dcache_pages(req);
 106                 return 0;
 107         case WRITE:
 108                 if (!tr->writesect)
 109                         return -EIO;
 110
 111                 rq_flush_dcache_pages(req);
 112                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 113                         if (tr->writesect(dev, block, buf))
 114                                 return -EIO;
 115                 return 0;
 116         default:
 117                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
 118                 return -EIO;
 119         }
 120 }
 121
 122 static int mtd_blktrans_thread(void *arg)
 123 {
 124         struct mtd_blktrans_dev *dev = arg;
 125         struct request_queue *rq = dev->rq;
 126         struct request *req = NULL;
 127
 128         spin_lock_irq(rq->queue_lock);
 129
 130         while (!kthread_should_stop()) {
 131                 int res;
 132
 133                 if (!req && !(req = blk_fetch_request(rq))) {
 134                         set_current_state(TASK_INTERRUPTIBLE);
 135
 136                         if (kthread_should_stop())
 137                                 set_current_state(TASK_RUNNING);
 138
 139                         spin_unlock_irq(rq->queue_lock);
 140                         schedule();
 141                         spin_lock_irq(rq->queue_lock);
 142                         continue;
 143                 }
 144
 145                 spin_unlock_irq(rq->queue_lock);
 146
 147                 mutex_lock(&dev->lock);
 148                 res = do_blktrans_request(dev->tr, dev, req);
 149                 mutex_unlock(&dev->lock);
 150
 151                 spin_lock_irq(rq->queue_lock);
 152
 153                 if (!__blk_end_request_cur(req, res))
 154                         req = NULL;
 155         }
 156
 157         if (req)
 158                 __blk_end_request_all(req, -EIO);
 159
 160         spin_unlock_irq(rq->queue_lock);
 161
 162         return 0;
 163 }
 164
 165 static void mtd_blktrans_request(struct request_queue *rq)
 166 {
 167         struct mtd_blktrans_dev *dev;
 168         struct request *req = NULL;
 169
 170         dev = rq->queuedata;
 171
 172         if (!dev)
 173                 while ((req = blk_fetch_request(rq)) != NULL)
 174                         __blk_end_request_all(req, -ENODEV);
 175         else
 176                 wake_up_process(dev->thread);
 177 }
 178
 179 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 180 {
 181         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 182         int ret = 0;
 183
 184         if (!dev)
 185                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 186
 187         mutex_lock(&dev->lock);
 188
 189         if (dev->open++)
 190                 goto unlock;
 191
 192         kref_get(&dev->ref);
 193         __module_get(dev->tr->owner);
 194
 195         if (dev->mtd) {
 196                 ret = dev->tr->open ? dev->tr->open(dev) : 0;
 197                 __get_mtd_device(dev->mtd);
 198         }
 199
 200 unlock:
 201         mutex_unlock(&dev->lock);
 202         blktrans_dev_put(dev);
 203         return ret;
 204 }
 205
 206 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 207 {
 208         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 209         int ret = 0;
 210
 211         if (!dev)
 212                 return ret;
 213
 214         mutex_lock(&dev->lock);
 215
 216         if (--dev->open)
 217                 goto unlock;
 218
 219         kref_put(&dev->ref, blktrans_dev_release);
 220         module_put(dev->tr->owner);
 221
 222         if (dev->mtd) {
 223                 ret = dev->tr->release ? dev->tr->release(dev) : 0;
 224                 __put_mtd_device(dev->mtd);
 225         }
 226 unlock:
 227         mutex_unlock(&dev->lock);
 228         blktrans_dev_put(dev);
 229         return ret;
 230 }
 231
 232 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 233 {
 234         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 235         int ret = -ENXIO;
 236
 237         if (!dev)
 238                 return ret;
 239
 240         mutex_lock(&dev->lock);
 241
 242         if (!dev->mtd)
 243                 goto unlock;
 244
 245         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 246 unlock:
 247         mutex_unlock(&dev->lock);
 248         blktrans_dev_put(dev);
 249         return ret;
 250 }
 251
 252 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 253                               unsigned int cmd, unsigned long arg)
 254 {
 255         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 256         int ret = -ENXIO;
 257
 258         if (!dev)
 259                 return ret;
 260
 261         mutex_lock(&dev->lock);
 262
 263         if (!dev->mtd)
 264                 goto unlock;
 265
 266         switch (cmd) {
 267         case BLKFLSBUF:
 268                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 269                 break;
 270         default:
 271                 ret = -ENOTTY;
 272         }
 273 unlock:
 274         mutex_unlock(&dev->lock);
 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         /* Create processing thread */
 389         /* TODO: workqueue ? */
 390         new->thread = kthread_run(mtd_blktrans_thread, new,
 391                         "%s%d", tr->name, new->mtd->index);
 392         if (IS_ERR(new->thread)) {
 393                 ret = PTR_ERR(new->thread);
 394                 goto error4;
 395         }
 396         gd->driverfs_dev = &new->mtd->dev;
 397
 398         if (new->readonly)
 399                 set_disk_ro(gd, 1);
 400
 401         add_disk(gd);
 402
 403         if (new->disk_attributes) {
 404                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 405                                         new->disk_attributes);
 406                 WARN_ON(ret);
 407         }
 408         return 0;
 409 error4:
 410         blk_cleanup_queue(new->rq);
 411 error3:
 412         put_disk(new->disk);
 413 error2:
 414         list_del(&new->list);
 415 error1:
 416         kfree(new);
 417         return ret;
 418 }
 419
 420 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 421 {
 422         unsigned long flags;
 423
 424         if (mutex_trylock(&mtd_table_mutex)) {
 425                 mutex_unlock(&mtd_table_mutex);
 426                 BUG();
 427         }
 428
 429         if (old->disk_attributes)
 430                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 431                                                 old->disk_attributes);
 432
 433         /* Stop new requests to arrive */
 434         del_gendisk(old->disk);
 435
 436
 437         /* Stop the thread */
 438         kthread_stop(old->thread);
 439
 440         /* Kill current requests */
 441         spin_lock_irqsave(&old->queue_lock, flags);
 442         old->rq->queuedata = NULL;
 443         blk_start_queue(old->rq);
 444         spin_unlock_irqrestore(&old->queue_lock, flags);
 445
 446         /* If the device is currently open, tell trans driver to close it,
 447                 then put mtd device, and don't touch it again */
 448         mutex_lock(&old->lock);
 449         if (old->open) {
 450                 if (old->tr->release)
 451                         old->tr->release(old);
 452                 __put_mtd_device(old->mtd);
 453         }
 454
 455         old->mtd = NULL;
 456
 457         mutex_unlock(&old->lock);
 458         blktrans_dev_put(old);
 459         return 0;
 460 }
 461
 462 static void blktrans_notify_remove(struct mtd_info *mtd)
 463 {
 464         struct mtd_blktrans_ops *tr;
 465         struct mtd_blktrans_dev *dev, *next;
 466
 467         list_for_each_entry(tr, &blktrans_majors, list)
 468                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 469                         if (dev->mtd == mtd)
 470                                 tr->remove_dev(dev);
 471 }
 472
 473 static void blktrans_notify_add(struct mtd_info *mtd)
 474 {
 475         struct mtd_blktrans_ops *tr;
 476
 477         if (mtd->type == MTD_ABSENT)
 478                 return;
 479
 480         list_for_each_entry(tr, &blktrans_majors, list)
 481                 tr->add_mtd(tr, mtd);
 482 }
 483
 484 static struct mtd_notifier blktrans_notifier = {
 485         .add = blktrans_notify_add,
 486         .remove = blktrans_notify_remove,
 487 };
 488
 489 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 490 {
 491         struct mtd_info *mtd;
 492         int ret;
 493
 494         /* Register the notifier if/when the first device type is
 495            registered, to prevent the link/init ordering from fucking
 496            us over. */
 497         if (!blktrans_notifier.list.next)
 498                 register_mtd_user(&blktrans_notifier);
 499
 500
 501         mutex_lock(&mtd_table_mutex);
 502
 503         ret = register_blkdev(tr->major, tr->name);
 504         if (ret < 0) {
 505                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 506                        tr->name, tr->major, ret);
 507                 mutex_unlock(&mtd_table_mutex);
 508                 return ret;
 509         }
 510
 511         if (ret)
 512                 tr->major = ret;
 513
 514         tr->blkshift = ffs(tr->blksize) - 1;
 515
 516         INIT_LIST_HEAD(&tr->devs);
 517         list_add(&tr->list, &blktrans_majors);
 518
 519         mtd_for_each_device(mtd)
 520                 if (mtd->type != MTD_ABSENT)
 521                         tr->add_mtd(tr, mtd);
 522
 523         mutex_unlock(&mtd_table_mutex);
 524         return 0;
 525 }
 526
 527 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 528 {
 529         struct mtd_blktrans_dev *dev, *next;
 530
 531         mutex_lock(&mtd_table_mutex);
 532
 533         /* Remove it from the list of active majors */
 534         list_del(&tr->list);
 535
 536         list_for_each_entry_safe(dev, next, &tr->devs, list)
 537                 tr->remove_dev(dev);
 538
 539         unregister_blkdev(tr->major, tr->name);
 540         mutex_unlock(&mtd_table_mutex);
 541
 542         BUG_ON(!list_empty(&tr->devs));
 543         return 0;
 544 }
 545
 546 static void __exit mtd_blktrans_exit(void)
 547 {
 548         /* No race here -- if someone's currently in register_mtd_blktrans
 549            we're screwed anyway. */
 550         if (blktrans_notifier.list.next)
 551                 unregister_mtd_user(&blktrans_notifier);
 552 }
 553
 554 module_exit(mtd_blktrans_exit);
 555
 556 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 557 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 558 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 559 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 560
 561 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 562 MODULE_LICENSE("GPL");
 563 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");