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
 137                         if (kthread_should_stop())
 138                                 set_current_state(TASK_RUNNING);
 139
 140                         spin_unlock_irq(rq->queue_lock);
 141                         schedule();
 142                         spin_lock_irq(rq->queue_lock);
 143                         continue;
 144                 }
 145
 146                 spin_unlock_irq(rq->queue_lock);
 147
 148                 mutex_lock(&dev->lock);
 149                 res = do_blktrans_request(dev->tr, dev, req);
 150                 mutex_unlock(&dev->lock);
 151
 152                 spin_lock_irq(rq->queue_lock);
 153
 154                 if (!__blk_end_request_cur(req, res))
 155                         req = NULL;
 156         }
 157
 158         if (req)
 159                 __blk_end_request_all(req, -EIO);
 160
 161         spin_unlock_irq(rq->queue_lock);
 162
 163         return 0;
 164 }
 165
 166 static void mtd_blktrans_request(struct request_queue *rq)
 167 {
 168         struct mtd_blktrans_dev *dev;
 169         struct request *req = NULL;
 170
 171         dev = rq->queuedata;
 172
 173         if (!dev)
 174                 while ((req = blk_fetch_request(rq)) != NULL)
 175                         __blk_end_request_all(req, -ENODEV);
 176         else
 177                 wake_up_process(dev->thread);
 178 }
 179
 180 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 181 {
 182         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 183         int ret = 0;
 184
 185         if (!dev)
 186                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 187
 188         mutex_lock(&dev->lock);
 189
 190         if (dev->open++)
 191                 goto unlock;
 192
 193         kref_get(&dev->ref);
 194         __module_get(dev->tr->owner);
 195
 196         if (dev->mtd) {
 197                 ret = dev->tr->open ? dev->tr->open(dev) : 0;
 198                 __get_mtd_device(dev->mtd);
 199         }
 200
 201 unlock:
 202         mutex_unlock(&dev->lock);
 203         blktrans_dev_put(dev);
 204         return ret;
 205 }
 206
 207 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 208 {
 209         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 210         int ret = 0;
 211
 212         if (!dev)
 213                 return ret;
 214
 215         mutex_lock(&dev->lock);
 216
 217         if (--dev->open)
 218                 goto unlock;
 219
 220         kref_put(&dev->ref, blktrans_dev_release);
 221         module_put(dev->tr->owner);
 222
 223         if (dev->mtd) {
 224                 ret = dev->tr->release ? dev->tr->release(dev) : 0;
 225                 __put_mtd_device(dev->mtd);
 226         }
 227 unlock:
 228         mutex_unlock(&dev->lock);
 229         blktrans_dev_put(dev);
 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         mutex_lock(&dev->lock);
 263
 264         if (!dev->mtd)
 265                 goto unlock;
 266
 267         switch (cmd) {
 268         case BLKFLSBUF:
 269                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 270                 break;
 271         default:
 272                 ret = -ENOTTY;
 273         }
 274 unlock:
 275         mutex_unlock(&dev->lock);
 276         blktrans_dev_put(dev);
 277         return ret;
 278 }
 279
 280 static const struct block_device_operations mtd_blktrans_ops = {
 281         .owner          = THIS_MODULE,
 282         .open           = blktrans_open,
 283         .release        = blktrans_release,
 284         .ioctl          = blktrans_ioctl,
 285         .getgeo         = blktrans_getgeo,
 286 };
 287
 288 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 289 {
 290         struct mtd_blktrans_ops *tr = new->tr;
 291         struct mtd_blktrans_dev *d;
 292         int last_devnum = -1;
 293         struct gendisk *gd;
 294         int ret;
 295
 296         if (mutex_trylock(&mtd_table_mutex)) {
 297                 mutex_unlock(&mtd_table_mutex);
 298                 BUG();
 299         }
 300
 301         mutex_lock(&blktrans_ref_mutex);
 302         list_for_each_entry(d, &tr->devs, list) {
 303                 if (new->devnum == -1) {
 304                         /* Use first free number */
 305                         if (d->devnum != last_devnum+1) {
 306                                 /* Found a free devnum. Plug it in here */
 307                                 new->devnum = last_devnum+1;
 308                                 list_add_tail(&new->list, &d->list);
 309                                 goto added;
 310                         }
 311                 } else if (d->devnum == new->devnum) {
 312                         /* Required number taken */
 313                         mutex_unlock(&blktrans_ref_mutex);
 314                         return -EBUSY;
 315                 } else if (d->devnum > new->devnum) {
 316                         /* Required number was free */
 317                         list_add_tail(&new->list, &d->list);
 318                         goto added;
 319                 }
 320                 last_devnum = d->devnum;
 321         }
 322
 323         ret = -EBUSY;
 324         if (new->devnum == -1)
 325                 new->devnum = last_devnum+1;
 326
 327         /* Check that the device and any partitions will get valid
 328          * minor numbers and that the disk naming code below can cope
 329          * with this number. */
 330         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 331             (tr->part_bits && new->devnum >= 27 * 26)) {
 332                 mutex_unlock(&blktrans_ref_mutex);
 333                 goto error1;
 334         }
 335
 336         list_add_tail(&new->list, &tr->devs);
 337  added:
 338         mutex_unlock(&blktrans_ref_mutex);
 339
 340         mutex_init(&new->lock);
 341         kref_init(&new->ref);
 342         if (!tr->writesect)
 343                 new->readonly = 1;
 344
 345         /* Create gendisk */
 346         ret = -ENOMEM;
 347         gd = alloc_disk(1 << tr->part_bits);
 348
 349         if (!gd)
 350                 goto error2;
 351
 352         new->disk = gd;
 353         gd->private_data = new;
 354         gd->major = tr->major;
 355         gd->first_minor = (new->devnum) << tr->part_bits;
 356         gd->fops = &mtd_blktrans_ops;
 357
 358         if (tr->part_bits)
 359                 if (new->devnum < 26)
 360                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 361                                  "%s%c", tr->name, 'a' + new->devnum);
 362                 else
 363                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 364                                  "%s%c%c", tr->name,
 365                                  'a' - 1 + new->devnum / 26,
 366                                  'a' + new->devnum % 26);
 367         else
 368                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 369                          "%s%d", tr->name, new->devnum);
 370
 371         set_capacity(gd, (new->size * tr->blksize) >> 9);
 372
 373         /* Create the request queue */
 374         spin_lock_init(&new->queue_lock);
 375         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 376
 377         if (!new->rq)
 378                 goto error3;
 379
 380         new->rq->queuedata = new;
 381         blk_queue_logical_block_size(new->rq, tr->blksize);
 382
 383         if (tr->discard)
 384                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 385                                         new->rq);
 386
 387         gd->queue = new->rq;
 388
 389         /* Create processing thread */
 390         /* TODO: workqueue ? */
 391         new->thread = kthread_run(mtd_blktrans_thread, new,
 392                         "%s%d", tr->name, new->mtd->index);
 393         if (IS_ERR(new->thread)) {
 394                 ret = PTR_ERR(new->thread);
 395                 goto error4;
 396         }
 397         gd->driverfs_dev = &new->mtd->dev;
 398
 399         if (new->readonly)
 400                 set_disk_ro(gd, 1);
 401
 402         add_disk(gd);
 403
 404         if (new->disk_attributes) {
 405                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 406                                         new->disk_attributes);
 407                 WARN_ON(ret);
 408         }
 409         return 0;
 410 error4:
 411         blk_cleanup_queue(new->rq);
 412 error3:
 413         put_disk(new->disk);
 414 error2:
 415         list_del(&new->list);
 416 error1:
 417         kfree(new);
 418         return ret;
 419 }
 420
 421 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 422 {
 423         unsigned long flags;
 424
 425         if (mutex_trylock(&mtd_table_mutex)) {
 426                 mutex_unlock(&mtd_table_mutex);
 427                 BUG();
 428         }
 429
 430         if (old->disk_attributes)
 431                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 432                                                 old->disk_attributes);
 433
 434         /* Stop new requests to arrive */
 435         del_gendisk(old->disk);
 436
 437
 438         /* Stop the thread */
 439         kthread_stop(old->thread);
 440
 441         /* Kill current requests */
 442         spin_lock_irqsave(&old->queue_lock, flags);
 443         old->rq->queuedata = NULL;
 444         blk_start_queue(old->rq);
 445         spin_unlock_irqrestore(&old->queue_lock, flags);
 446
 447         /* If the device is currently open, tell trans driver to close it,
 448                 then put mtd device, and don't touch it again */
 449         mutex_lock(&old->lock);
 450         if (old->open) {
 451                 if (old->tr->release)
 452                         old->tr->release(old);
 453                 __put_mtd_device(old->mtd);
 454         }
 455
 456         old->mtd = NULL;
 457
 458         mutex_unlock(&old->lock);
 459         blktrans_dev_put(old);
 460         return 0;
 461 }
 462
 463 static void blktrans_notify_remove(struct mtd_info *mtd)
 464 {
 465         struct mtd_blktrans_ops *tr;
 466         struct mtd_blktrans_dev *dev, *next;
 467
 468         list_for_each_entry(tr, &blktrans_majors, list)
 469                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 470                         if (dev->mtd == mtd)
 471                                 tr->remove_dev(dev);
 472 }
 473
 474 static void blktrans_notify_add(struct mtd_info *mtd)
 475 {
 476         struct mtd_blktrans_ops *tr;
 477
 478         if (mtd->type == MTD_ABSENT)
 479                 return;
 480
 481         list_for_each_entry(tr, &blktrans_majors, list)
 482                 tr->add_mtd(tr, mtd);
 483 }
 484
 485 static struct mtd_notifier blktrans_notifier = {
 486         .add = blktrans_notify_add,
 487         .remove = blktrans_notify_remove,
 488 };
 489
 490 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 491 {
 492         struct mtd_info *mtd;
 493         int ret;
 494
 495         /* Register the notifier if/when the first device type is
 496            registered, to prevent the link/init ordering from fucking
 497            us over. */
 498         if (!blktrans_notifier.list.next)
 499                 register_mtd_user(&blktrans_notifier);
 500
 501
 502         mutex_lock(&mtd_table_mutex);
 503
 504         ret = register_blkdev(tr->major, tr->name);
 505         if (ret < 0) {
 506                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 507                        tr->name, tr->major, ret);
 508                 mutex_unlock(&mtd_table_mutex);
 509                 return ret;
 510         }
 511
 512         if (ret)
 513                 tr->major = ret;
 514
 515         tr->blkshift = ffs(tr->blksize) - 1;
 516
 517         INIT_LIST_HEAD(&tr->devs);
 518         list_add(&tr->list, &blktrans_majors);
 519
 520         mtd_for_each_device(mtd)
 521                 if (mtd->type != MTD_ABSENT)
 522                         tr->add_mtd(tr, mtd);
 523
 524         mutex_unlock(&mtd_table_mutex);
 525         return 0;
 526 }
 527
 528 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 529 {
 530         struct mtd_blktrans_dev *dev, *next;
 531
 532         mutex_lock(&mtd_table_mutex);
 533
 534         /* Remove it from the list of active majors */
 535         list_del(&tr->list);
 536
 537         list_for_each_entry_safe(dev, next, &tr->devs, list)
 538                 tr->remove_dev(dev);
 539
 540         unregister_blkdev(tr->major, tr->name);
 541         mutex_unlock(&mtd_table_mutex);
 542
 543         BUG_ON(!list_empty(&tr->devs));
 544         return 0;
 545 }
 546
 547 static void __exit mtd_blktrans_exit(void)
 548 {
 549         /* No race here -- if someone's currently in register_mtd_blktrans
 550            we're screwed anyway. */
 551         if (blktrans_notifier.list.next)
 552                 unregister_mtd_user(&blktrans_notifier);
 553 }
 554
 555 module_exit(mtd_blktrans_exit);
 556
 557 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 558 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 559 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 560 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 561
 562 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 563 MODULE_LICENSE("GPL");
 564 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");