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         mutex_lock(&dev->lock);
 185
 186         if (dev->open++)
 187                 goto unlock;
 188
 189         kref_get(&dev->ref);
 190         __module_get(dev->tr->owner);
 191
 192         if (dev->mtd) {
 193                 ret = dev->tr->open ? dev->tr->open(dev) : 0;
 194                 __get_mtd_device(dev->mtd);
 195         }
 196
 197 unlock:
 198         mutex_unlock(&dev->lock);
 199         blktrans_dev_put(dev);
 200         return ret;
 201 }
 202
 203 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 204 {
 205         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 206         int ret = 0;
 207
 208         if (!dev)
 209                 return ret;
 210
 211         mutex_lock(&dev->lock);
 212
 213         if (--dev->open)
 214                 goto unlock;
 215
 216         kref_put(&dev->ref, blktrans_dev_release);
 217         module_put(dev->tr->owner);
 218
 219         if (dev->mtd) {
 220                 ret = dev->tr->release ? dev->tr->release(dev) : 0;
 221                 __put_mtd_device(dev->mtd);
 222         }
 223 unlock:
 224         mutex_unlock(&dev->lock);
 225         blktrans_dev_put(dev);
 226         return ret;
 227 }
 228
 229 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 230 {
 231         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 232         int ret = -ENXIO;
 233
 234         if (!dev)
 235                 return ret;
 236
 237         mutex_lock(&dev->lock);
 238
 239         if (!dev->mtd)
 240                 goto unlock;
 241
 242         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 243 unlock:
 244         mutex_unlock(&dev->lock);
 245         blktrans_dev_put(dev);
 246         return ret;
 247 }
 248
 249 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 250                               unsigned int cmd, unsigned long arg)
 251 {
 252         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 253         int ret = -ENXIO;
 254
 255         if (!dev)
 256                 return ret;
 257
 258         mutex_lock(&dev->lock);
 259
 260         if (!dev->mtd)
 261                 goto unlock;
 262
 263         switch (cmd) {
 264         case BLKFLSBUF:
 265                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 266                 break;
 267         default:
 268                 ret = -ENOTTY;
 269         }
 270 unlock:
 271         mutex_unlock(&dev->lock);
 272         blktrans_dev_put(dev);
 273         return ret;
 274 }
 275
 276 static const struct block_device_operations mtd_blktrans_ops = {
 277         .owner          = THIS_MODULE,
 278         .open           = blktrans_open,
 279         .release        = blktrans_release,
 280         .ioctl          = blktrans_ioctl,
 281         .getgeo         = blktrans_getgeo,
 282 };
 283
 284 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 285 {
 286         struct mtd_blktrans_ops *tr = new->tr;
 287         struct mtd_blktrans_dev *d;
 288         int last_devnum = -1;
 289         struct gendisk *gd;
 290         int ret;
 291
 292         if (mutex_trylock(&mtd_table_mutex)) {
 293                 mutex_unlock(&mtd_table_mutex);
 294                 BUG();
 295         }
 296
 297         mutex_lock(&blktrans_ref_mutex);
 298         list_for_each_entry(d, &tr->devs, list) {
 299                 if (new->devnum == -1) {
 300                         /* Use first free number */
 301                         if (d->devnum != last_devnum+1) {
 302                                 /* Found a free devnum. Plug it in here */
 303                                 new->devnum = last_devnum+1;
 304                                 list_add_tail(&new->list, &d->list);
 305                                 goto added;
 306                         }
 307                 } else if (d->devnum == new->devnum) {
 308                         /* Required number taken */
 309                         mutex_unlock(&blktrans_ref_mutex);
 310                         return -EBUSY;
 311                 } else if (d->devnum > new->devnum) {
 312                         /* Required number was free */
 313                         list_add_tail(&new->list, &d->list);
 314                         goto added;
 315                 }
 316                 last_devnum = d->devnum;
 317         }
 318
 319         ret = -EBUSY;
 320         if (new->devnum == -1)
 321                 new->devnum = last_devnum+1;
 322
 323         /* Check that the device and any partitions will get valid
 324          * minor numbers and that the disk naming code below can cope
 325          * with this number. */
 326         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 327             (tr->part_bits && new->devnum >= 27 * 26)) {
 328                 mutex_unlock(&blktrans_ref_mutex);
 329                 goto error1;
 330         }
 331
 332         list_add_tail(&new->list, &tr->devs);
 333  added:
 334         mutex_unlock(&blktrans_ref_mutex);
 335
 336         mutex_init(&new->lock);
 337         kref_init(&new->ref);
 338         if (!tr->writesect)
 339                 new->readonly = 1;
 340
 341         /* Create gendisk */
 342         ret = -ENOMEM;
 343         gd = alloc_disk(1 << tr->part_bits);
 344
 345         if (!gd)
 346                 goto error2;
 347
 348         new->disk = gd;
 349         gd->private_data = new;
 350         gd->major = tr->major;
 351         gd->first_minor = (new->devnum) << tr->part_bits;
 352         gd->fops = &mtd_blktrans_ops;
 353
 354         if (tr->part_bits)
 355                 if (new->devnum < 26)
 356                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 357                                  "%s%c", tr->name, 'a' + new->devnum);
 358                 else
 359                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 360                                  "%s%c%c", tr->name,
 361                                  'a' - 1 + new->devnum / 26,
 362                                  'a' + new->devnum % 26);
 363         else
 364                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 365                          "%s%d", tr->name, new->devnum);
 366
 367         set_capacity(gd, (new->size * tr->blksize) >> 9);
 368
 369         /* Create the request queue */
 370         spin_lock_init(&new->queue_lock);
 371         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 372
 373         if (!new->rq)
 374                 goto error3;
 375
 376         new->rq->queuedata = new;
 377         blk_queue_logical_block_size(new->rq, tr->blksize);
 378
 379         if (tr->discard)
 380                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 381                                         new->rq);
 382
 383         gd->queue = new->rq;
 384
 385         /* Create processing thread */
 386         /* TODO: workqueue ? */
 387         new->thread = kthread_run(mtd_blktrans_thread, new,
 388                         "%s%d", tr->name, new->mtd->index);
 389         if (IS_ERR(new->thread)) {
 390                 ret = PTR_ERR(new->thread);
 391                 goto error4;
 392         }
 393         gd->driverfs_dev = &new->mtd->dev;
 394
 395         if (new->readonly)
 396                 set_disk_ro(gd, 1);
 397
 398         add_disk(gd);
 399
 400         if (new->disk_attributes) {
 401                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 402                                         new->disk_attributes);
 403                 WARN_ON(ret);
 404         }
 405         return 0;
 406 error4:
 407         blk_cleanup_queue(new->rq);
 408 error3:
 409         put_disk(new->disk);
 410 error2:
 411         list_del(&new->list);
 412 error1:
 413         kfree(new);
 414         return ret;
 415 }
 416
 417 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 418 {
 419         unsigned long flags;
 420
 421         if (mutex_trylock(&mtd_table_mutex)) {
 422                 mutex_unlock(&mtd_table_mutex);
 423                 BUG();
 424         }
 425
 426         if (old->disk_attributes)
 427                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 428                                                 old->disk_attributes);
 429
 430         /* Stop new requests to arrive */
 431         del_gendisk(old->disk);
 432
 433
 434         /* Stop the thread */
 435         kthread_stop(old->thread);
 436
 437         /* Kill current requests */
 438         spin_lock_irqsave(&old->queue_lock, flags);
 439         old->rq->queuedata = NULL;
 440         blk_start_queue(old->rq);
 441         spin_unlock_irqrestore(&old->queue_lock, flags);
 442
 443         /* If the device is currently open, tell trans driver to close it,
 444                 then put mtd device, and don't touch it again */
 445         mutex_lock(&old->lock);
 446         if (old->open) {
 447                 if (old->tr->release)
 448                         old->tr->release(old);
 449                 __put_mtd_device(old->mtd);
 450         }
 451
 452         old->mtd = NULL;
 453
 454         mutex_unlock(&old->lock);
 455         blktrans_dev_put(old);
 456         return 0;
 457 }
 458
 459 static void blktrans_notify_remove(struct mtd_info *mtd)
 460 {
 461         struct mtd_blktrans_ops *tr;
 462         struct mtd_blktrans_dev *dev, *next;
 463
 464         list_for_each_entry(tr, &blktrans_majors, list)
 465                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 466                         if (dev->mtd == mtd)
 467                                 tr->remove_dev(dev);
 468 }
 469
 470 static void blktrans_notify_add(struct mtd_info *mtd)
 471 {
 472         struct mtd_blktrans_ops *tr;
 473
 474         if (mtd->type == MTD_ABSENT)
 475                 return;
 476
 477         list_for_each_entry(tr, &blktrans_majors, list)
 478                 tr->add_mtd(tr, mtd);
 479 }
 480
 481 static struct mtd_notifier blktrans_notifier = {
 482         .add = blktrans_notify_add,
 483         .remove = blktrans_notify_remove,
 484 };
 485
 486 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 487 {
 488         struct mtd_info *mtd;
 489         int ret;
 490
 491         /* Register the notifier if/when the first device type is
 492            registered, to prevent the link/init ordering from fucking
 493            us over. */
 494         if (!blktrans_notifier.list.next)
 495                 register_mtd_user(&blktrans_notifier);
 496
 497
 498         mutex_lock(&mtd_table_mutex);
 499
 500         ret = register_blkdev(tr->major, tr->name);
 501         if (ret) {
 502                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 503                        tr->name, tr->major, ret);
 504                 mutex_unlock(&mtd_table_mutex);
 505                 return ret;
 506         }
 507
 508         tr->blkshift = ffs(tr->blksize) - 1;
 509
 510         INIT_LIST_HEAD(&tr->devs);
 511         list_add(&tr->list, &blktrans_majors);
 512
 513         mtd_for_each_device(mtd)
 514                 if (mtd->type != MTD_ABSENT)
 515                         tr->add_mtd(tr, mtd);
 516
 517         mutex_unlock(&mtd_table_mutex);
 518         return 0;
 519 }
 520
 521 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 522 {
 523         struct mtd_blktrans_dev *dev, *next;
 524
 525         mutex_lock(&mtd_table_mutex);
 526
 527         /* Remove it from the list of active majors */
 528         list_del(&tr->list);
 529
 530         list_for_each_entry_safe(dev, next, &tr->devs, list)
 531                 tr->remove_dev(dev);
 532
 533         unregister_blkdev(tr->major, tr->name);
 534         mutex_unlock(&mtd_table_mutex);
 535
 536         BUG_ON(!list_empty(&tr->devs));
 537         return 0;
 538 }
 539
 540 static void __exit mtd_blktrans_exit(void)
 541 {
 542         /* No race here -- if someone's currently in register_mtd_blktrans
 543            we're screwed anyway. */
 544         if (blktrans_notifier.list.next)
 545                 unregister_mtd_user(&blktrans_notifier);
 546 }
 547
 548 module_exit(mtd_blktrans_exit);
 549
 550 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 551 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 552 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 553 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 554
 555 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 556 MODULE_LICENSE("GPL");
 557 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");