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/smp_lock.h>
  33 #include <linux/hdreg.h>
  34 #include <linux/init.h>
  35 #include <linux/mutex.h>
  36 #include <linux/kthread.h>
  37 #include <asm/uaccess.h>
  38
  39 #include "mtdcore.h"
  40
  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 = 0;
 180
 181         if (!dev)
 182                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 183
 184         lock_kernel();
 185         mutex_lock(&dev->lock);
 186
 187         if (dev->open++)
 188                 goto unlock;
 189
 190         kref_get(&dev->ref);
 191         __module_get(dev->tr->owner);
 192
 193         if (dev->mtd) {
 194                 ret = dev->tr->open ? dev->tr->open(dev) : 0;
 195                 __get_mtd_device(dev->mtd);
 196         }
 197
 198 unlock:
 199         mutex_unlock(&dev->lock);
 200         blktrans_dev_put(dev);
 201         unlock_kernel();
 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 = 0;
 209
 210         if (!dev)
 211                 return ret;
 212
 213         lock_kernel();
 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         unlock_kernel();
 230         return ret;
 231 }
 232
 233 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 234 {
 235         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 236         int ret = -ENXIO;
 237
 238         if (!dev)
 239                 return ret;
 240
 241         mutex_lock(&dev->lock);
 242
 243         if (!dev->mtd)
 244                 goto unlock;
 245
 246         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 247 unlock:
 248         mutex_unlock(&dev->lock);
 249         blktrans_dev_put(dev);
 250         return ret;
 251 }
 252
 253 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 254                               unsigned int cmd, unsigned long arg)
 255 {
 256         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 257         int ret = -ENXIO;
 258
 259         if (!dev)
 260                 return ret;
 261
 262         lock_kernel();
 263         mutex_lock(&dev->lock);
 264
 265         if (!dev->mtd)
 266                 goto unlock;
 267
 268         switch (cmd) {
 269         case BLKFLSBUF:
 270                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 271                 break;
 272         default:
 273                 ret = -ENOTTY;
 274         }
 275 unlock:
 276         mutex_unlock(&dev->lock);
 277         unlock_kernel();
 278         blktrans_dev_put(dev);
 279         return ret;
 280 }
 281
 282 static const struct block_device_operations mtd_blktrans_ops = {
 283         .owner          = THIS_MODULE,
 284         .open           = blktrans_open,
 285         .release        = blktrans_release,
 286         .ioctl          = blktrans_ioctl,
 287         .getgeo         = blktrans_getgeo,
 288 };
 289
 290 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 291 {
 292         struct mtd_blktrans_ops *tr = new->tr;
 293         struct mtd_blktrans_dev *d;
 294         int last_devnum = -1;
 295         struct gendisk *gd;
 296         int ret;
 297
 298         if (mutex_trylock(&mtd_table_mutex)) {
 299                 mutex_unlock(&mtd_table_mutex);
 300                 BUG();
 301         }
 302
 303         mutex_lock(&blktrans_ref_mutex);
 304         list_for_each_entry(d, &tr->devs, list) {
 305                 if (new->devnum == -1) {
 306                         /* Use first free number */
 307                         if (d->devnum != last_devnum+1) {
 308                                 /* Found a free devnum. Plug it in here */
 309                                 new->devnum = last_devnum+1;
 310                                 list_add_tail(&new->list, &d->list);
 311                                 goto added;
 312                         }
 313                 } else if (d->devnum == new->devnum) {
 314                         /* Required number taken */
 315                         mutex_unlock(&blktrans_ref_mutex);
 316                         return -EBUSY;
 317                 } else if (d->devnum > new->devnum) {
 318                         /* Required number was free */
 319                         list_add_tail(&new->list, &d->list);
 320                         goto added;
 321                 }
 322                 last_devnum = d->devnum;
 323         }
 324
 325         ret = -EBUSY;
 326         if (new->devnum == -1)
 327                 new->devnum = last_devnum+1;
 328
 329         /* Check that the device and any partitions will get valid
 330          * minor numbers and that the disk naming code below can cope
 331          * with this number. */
 332         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 333             (tr->part_bits && new->devnum >= 27 * 26)) {
 334                 mutex_unlock(&blktrans_ref_mutex);
 335                 goto error1;
 336         }
 337
 338         list_add_tail(&new->list, &tr->devs);
 339  added:
 340         mutex_unlock(&blktrans_ref_mutex);
 341
 342         mutex_init(&new->lock);
 343         kref_init(&new->ref);
 344         if (!tr->writesect)
 345                 new->readonly = 1;
 346
 347         /* Create gendisk */
 348         ret = -ENOMEM;
 349         gd = alloc_disk(1 << tr->part_bits);
 350
 351         if (!gd)
 352                 goto error2;
 353
 354         new->disk = gd;
 355         gd->private_data = new;
 356         gd->major = tr->major;
 357         gd->first_minor = (new->devnum) << tr->part_bits;
 358         gd->fops = &mtd_blktrans_ops;
 359
 360         if (tr->part_bits)
 361                 if (new->devnum < 26)
 362                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 363                                  "%s%c", tr->name, 'a' + new->devnum);
 364                 else
 365                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 366                                  "%s%c%c", tr->name,
 367                                  'a' - 1 + new->devnum / 26,
 368                                  'a' + new->devnum % 26);
 369         else
 370                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 371                          "%s%d", tr->name, new->devnum);
 372
 373         set_capacity(gd, (new->size * tr->blksize) >> 9);
 374
 375         /* Create the request queue */
 376         spin_lock_init(&new->queue_lock);
 377         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 378
 379         if (!new->rq)
 380                 goto error3;
 381
 382         new->rq->queuedata = new;
 383         blk_queue_logical_block_size(new->rq, tr->blksize);
 384
 385         if (tr->discard)
 386                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 387                                         new->rq);
 388
 389         gd->queue = new->rq;
 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         blk_cleanup_queue(new->rq);
 414 error3:
 415         put_disk(new->disk);
 416 error2:
 417         list_del(&new->list);
 418 error1:
 419         kfree(new);
 420         return ret;
 421 }
 422
 423 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 424 {
 425         unsigned long flags;
 426
 427         if (mutex_trylock(&mtd_table_mutex)) {
 428                 mutex_unlock(&mtd_table_mutex);
 429                 BUG();
 430         }
 431
 432         if (old->disk_attributes)
 433                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 434                                                 old->disk_attributes);
 435
 436         /* Stop new requests to arrive */
 437         del_gendisk(old->disk);
 438
 439
 440         /* Stop the thread */
 441         kthread_stop(old->thread);
 442
 443         /* Kill current requests */
 444         spin_lock_irqsave(&old->queue_lock, flags);
 445         old->rq->queuedata = NULL;
 446         blk_start_queue(old->rq);
 447         spin_unlock_irqrestore(&old->queue_lock, flags);
 448
 449         /* If the device is currently open, tell trans driver to close it,
 450                 then put mtd device, and don't touch it again */
 451         mutex_lock(&old->lock);
 452         if (old->open) {
 453                 if (old->tr->release)
 454                         old->tr->release(old);
 455                 __put_mtd_device(old->mtd);
 456         }
 457
 458         old->mtd = NULL;
 459
 460         mutex_unlock(&old->lock);
 461         blktrans_dev_put(old);
 462         return 0;
 463 }
 464
 465 static void blktrans_notify_remove(struct mtd_info *mtd)
 466 {
 467         struct mtd_blktrans_ops *tr;
 468         struct mtd_blktrans_dev *dev, *next;
 469
 470         list_for_each_entry(tr, &blktrans_majors, list)
 471                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 472                         if (dev->mtd == mtd)
 473                                 tr->remove_dev(dev);
 474 }
 475
 476 static void blktrans_notify_add(struct mtd_info *mtd)
 477 {
 478         struct mtd_blktrans_ops *tr;
 479
 480         if (mtd->type == MTD_ABSENT)
 481                 return;
 482
 483         list_for_each_entry(tr, &blktrans_majors, list)
 484                 tr->add_mtd(tr, mtd);
 485 }
 486
 487 static struct mtd_notifier blktrans_notifier = {
 488         .add = blktrans_notify_add,
 489         .remove = blktrans_notify_remove,
 490 };
 491
 492 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 493 {
 494         struct mtd_info *mtd;
 495         int ret;
 496
 497         /* Register the notifier if/when the first device type is
 498            registered, to prevent the link/init ordering from fucking
 499            us over. */
 500         if (!blktrans_notifier.list.next)
 501                 register_mtd_user(&blktrans_notifier);
 502
 503
 504         mutex_lock(&mtd_table_mutex);
 505
 506         ret = register_blkdev(tr->major, tr->name);
 507         if (ret) {
 508                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 509                        tr->name, tr->major, ret);
 510                 mutex_unlock(&mtd_table_mutex);
 511                 return ret;
 512         }
 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'");