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 (!blk_fs_request(req))
  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 (blk_discard_rq(req))
  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                         spin_unlock_irq(rq->queue_lock);
 136                         schedule();
 137                         spin_lock_irq(rq->queue_lock);
 138                         continue;
 139                 }
 140
 141                 spin_unlock_irq(rq->queue_lock);
 142
 143                 mutex_lock(&dev->lock);
 144                 res = do_blktrans_request(dev->tr, dev, req);
 145                 mutex_unlock(&dev->lock);
 146
 147                 spin_lock_irq(rq->queue_lock);
 148
 149                 if (!__blk_end_request_cur(req, res))
 150                         req = NULL;
 151         }
 152
 153         if (req)
 154                 __blk_end_request_all(req, -EIO);
 155
 156         spin_unlock_irq(rq->queue_lock);
 157
 158         return 0;
 159 }
 160
 161 static void mtd_blktrans_request(struct request_queue *rq)
 162 {
 163         struct mtd_blktrans_dev *dev;
 164         struct request *req = NULL;
 165
 166         dev = rq->queuedata;
 167
 168         if (!dev)
 169                 while ((req = blk_fetch_request(rq)) != NULL)
 170                         __blk_end_request_all(req, -ENODEV);
 171         else
 172                 wake_up_process(dev->thread);
 173 }
 174
 175 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 176 {
 177         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 178         int ret;
 179
 180         if (!dev)
 181                 return -ERESTARTSYS;
 182
 183         mutex_lock(&dev->lock);
 184
 185         if (!dev->mtd) {
 186                 ret = -ENXIO;
 187                 goto unlock;
 188         }
 189
 190         ret = !dev->open++ && dev->tr->open ? dev->tr->open(dev) : 0;
 191
 192         /* Take another reference on the device so it won't go away till
 193                 last release */
 194         if (!ret)
 195                 kref_get(&dev->ref);
 196 unlock:
 197         mutex_unlock(&dev->lock);
 198         blktrans_dev_put(dev);
 199         return ret;
 200 }
 201
 202 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 203 {
 204         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 205         int ret = -ENXIO;
 206
 207         if (!dev)
 208                 return ret;
 209
 210         mutex_lock(&dev->lock);
 211
 212         /* Release one reference, we sure its not the last one here*/
 213         kref_put(&dev->ref, blktrans_dev_release);
 214
 215         if (!dev->mtd)
 216                 goto unlock;
 217
 218         ret = !--dev->open && dev->tr->release ? dev->tr->release(dev) : 0;
 219 unlock:
 220         mutex_unlock(&dev->lock);
 221         blktrans_dev_put(dev);
 222         return ret;
 223 }
 224
 225 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 226 {
 227         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 228         int ret = -ENXIO;
 229
 230         if (!dev)
 231                 return ret;
 232
 233         mutex_lock(&dev->lock);
 234
 235         if (!dev->mtd)
 236                 goto unlock;
 237
 238         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 239 unlock:
 240         mutex_unlock(&dev->lock);
 241         blktrans_dev_put(dev);
 242         return ret;
 243 }
 244
 245 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 246                               unsigned int cmd, unsigned long arg)
 247 {
 248         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 249         int ret = -ENXIO;
 250
 251         if (!dev)
 252                 return ret;
 253
 254         mutex_lock(&dev->lock);
 255
 256         if (!dev->mtd)
 257                 goto unlock;
 258
 259         switch (cmd) {
 260         case BLKFLSBUF:
 261                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 262                 break;
 263         default:
 264                 ret = -ENOTTY;
 265         }
 266 unlock:
 267         mutex_unlock(&dev->lock);
 268         blktrans_dev_put(dev);
 269         return ret;
 270 }
 271
 272 static const struct block_device_operations mtd_blktrans_ops = {
 273         .owner          = THIS_MODULE,
 274         .open           = blktrans_open,
 275         .release        = blktrans_release,
 276         .locked_ioctl   = blktrans_ioctl,
 277         .getgeo         = blktrans_getgeo,
 278 };
 279
 280 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 281 {
 282         struct mtd_blktrans_ops *tr = new->tr;
 283         struct mtd_blktrans_dev *d;
 284         int last_devnum = -1;
 285         struct gendisk *gd;
 286         int ret;
 287
 288         if (mutex_trylock(&mtd_table_mutex)) {
 289                 mutex_unlock(&mtd_table_mutex);
 290                 BUG();
 291         }
 292
 293         mutex_lock(&blktrans_ref_mutex);
 294         list_for_each_entry(d, &tr->devs, list) {
 295                 if (new->devnum == -1) {
 296                         /* Use first free number */
 297                         if (d->devnum != last_devnum+1) {
 298                                 /* Found a free devnum. Plug it in here */
 299                                 new->devnum = last_devnum+1;
 300                                 list_add_tail(&new->list, &d->list);
 301                                 goto added;
 302                         }
 303                 } else if (d->devnum == new->devnum) {
 304                         /* Required number taken */
 305                         mutex_unlock(&blktrans_ref_mutex);
 306                         return -EBUSY;
 307                 } else if (d->devnum > new->devnum) {
 308                         /* Required number was free */
 309                         list_add_tail(&new->list, &d->list);
 310                         goto added;
 311                 }
 312                 last_devnum = d->devnum;
 313         }
 314
 315         ret = -EBUSY;
 316         if (new->devnum == -1)
 317                 new->devnum = last_devnum+1;
 318
 319         /* Check that the device and any partitions will get valid
 320          * minor numbers and that the disk naming code below can cope
 321          * with this number. */
 322         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 323             (tr->part_bits && new->devnum >= 27 * 26)) {
 324                 mutex_unlock(&blktrans_ref_mutex);
 325                 goto error1;
 326         }
 327
 328         list_add_tail(&new->list, &tr->devs);
 329  added:
 330         mutex_unlock(&blktrans_ref_mutex);
 331
 332         mutex_init(&new->lock);
 333         kref_init(&new->ref);
 334         if (!tr->writesect)
 335                 new->readonly = 1;
 336
 337         /* Create gendisk */
 338         ret = -ENOMEM;
 339         gd = alloc_disk(1 << tr->part_bits);
 340
 341         if (!gd)
 342                 goto error2;
 343
 344         new->disk = gd;
 345         gd->private_data = new;
 346         gd->major = tr->major;
 347         gd->first_minor = (new->devnum) << tr->part_bits;
 348         gd->fops = &mtd_blktrans_ops;
 349
 350         if (tr->part_bits)
 351                 if (new->devnum < 26)
 352                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 353                                  "%s%c", tr->name, 'a' + new->devnum);
 354                 else
 355                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 356                                  "%s%c%c", tr->name,
 357                                  'a' - 1 + new->devnum / 26,
 358                                  'a' + new->devnum % 26);
 359         else
 360                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 361                          "%s%d", tr->name, new->devnum);
 362
 363         set_capacity(gd, (new->size * tr->blksize) >> 9);
 364
 365         /* Create the request queue */
 366         spin_lock_init(&new->queue_lock);
 367         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 368
 369         if (!new->rq)
 370                 goto error3;
 371
 372         new->rq->queuedata = new;
 373         blk_queue_logical_block_size(new->rq, tr->blksize);
 374
 375         if (tr->discard)
 376                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 377                                         new->rq);
 378
 379         gd->queue = new->rq;
 380
 381         __get_mtd_device(new->mtd);
 382         __module_get(tr->owner);
 383
 384         /* Create processing thread */
 385         /* TODO: workqueue ? */
 386         new->thread = kthread_run(mtd_blktrans_thread, new,
 387                         "%s%d", tr->name, new->mtd->index);
 388         if (IS_ERR(new->thread)) {
 389                 ret = PTR_ERR(new->thread);
 390                 goto error4;
 391         }
 392         gd->driverfs_dev = &new->mtd->dev;
 393
 394         if (new->readonly)
 395                 set_disk_ro(gd, 1);
 396
 397         add_disk(gd);
 398
 399         if (new->disk_attributes) {
 400                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 401                                         new->disk_attributes);
 402                 WARN_ON(ret);
 403         }
 404         return 0;
 405 error4:
 406         module_put(tr->owner);
 407         __put_mtd_device(new->mtd);
 408         blk_cleanup_queue(new->rq);
 409 error3:
 410         put_disk(new->disk);
 411 error2:
 412         list_del(&new->list);
 413 error1:
 414         kfree(new);
 415         return ret;
 416 }
 417
 418 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 419 {
 420         unsigned long flags;
 421
 422         if (mutex_trylock(&mtd_table_mutex)) {
 423                 mutex_unlock(&mtd_table_mutex);
 424                 BUG();
 425         }
 426
 427         if (old->disk_attributes)
 428                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 429                                                 old->disk_attributes);
 430
 431         /* Stop new requests to arrive */
 432         del_gendisk(old->disk);
 433
 434
 435         /* Stop the thread */
 436         kthread_stop(old->thread);
 437
 438         /* Kill current requests */
 439         spin_lock_irqsave(&old->queue_lock, flags);
 440         old->rq->queuedata = NULL;
 441         blk_start_queue(old->rq);
 442         spin_unlock_irqrestore(&old->queue_lock, flags);
 443
 444         /* Ask trans driver for release to the mtd device */
 445         mutex_lock(&old->lock);
 446         if (old->open && old->tr->release) {
 447                 old->tr->release(old);
 448                 old->open = 0;
 449         }
 450
 451         __put_mtd_device(old->mtd);
 452         module_put(old->tr->owner);
 453
 454         /* At that point, we don't touch the mtd anymore */
 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) {
 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         tr->blkshift = ffs(tr->blksize) - 1;
 512
 513         INIT_LIST_HEAD(&tr->devs);
 514         list_add(&tr->list, &blktrans_majors);
 515
 516         mtd_for_each_device(mtd)
 517                 if (mtd->type != MTD_ABSENT)
 518                         tr->add_mtd(tr, mtd);
 519
 520         mutex_unlock(&mtd_table_mutex);
 521         return 0;
 522 }
 523
 524 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 525 {
 526         struct mtd_blktrans_dev *dev, *next;
 527
 528         mutex_lock(&mtd_table_mutex);
 529
 530         /* Remove it from the list of active majors */
 531         list_del(&tr->list);
 532
 533         list_for_each_entry_safe(dev, next, &tr->devs, list)
 534                 tr->remove_dev(dev);
 535
 536         unregister_blkdev(tr->major, tr->name);
 537         mutex_unlock(&mtd_table_mutex);
 538
 539         BUG_ON(!list_empty(&tr->devs));
 540         return 0;
 541 }
 542
 543 static void __exit mtd_blktrans_exit(void)
 544 {
 545         /* No race here -- if someone's currently in register_mtd_blktrans
 546            we're screwed anyway. */
 547         if (blktrans_notifier.list.next)
 548                 unregister_mtd_user(&blktrans_notifier);
 549 }
 550
 551 module_exit(mtd_blktrans_exit);
 552
 553 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 554 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 555 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 556 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 557
 558 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 559 MODULE_LICENSE("GPL");
 560 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");