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 <asm/uaccess.h>
  36
  37 #include "mtdcore.h"
  38
  39 static LIST_HEAD(blktrans_majors);
  40 static DEFINE_MUTEX(blktrans_ref_mutex);
  41
  42 static void blktrans_dev_release(struct kref *kref)
  43 {
  44         struct mtd_blktrans_dev *dev =
  45                 container_of(kref, struct mtd_blktrans_dev, ref);
  46
  47         dev->disk->private_data = NULL;
  48         blk_cleanup_queue(dev->rq);
  49         put_disk(dev->disk);
  50         list_del(&dev->list);
  51         kfree(dev);
  52 }
  53
  54 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  55 {
  56         struct mtd_blktrans_dev *dev;
  57
  58         mutex_lock(&blktrans_ref_mutex);
  59         dev = disk->private_data;
  60
  61         if (!dev)
  62                 goto unlock;
  63         kref_get(&dev->ref);
  64 unlock:
  65         mutex_unlock(&blktrans_ref_mutex);
  66         return dev;
  67 }
  68
  69 static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  70 {
  71         mutex_lock(&blktrans_ref_mutex);
  72         kref_put(&dev->ref, blktrans_dev_release);
  73         mutex_unlock(&blktrans_ref_mutex);
  74 }
  75
  76
  77 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  78                                struct mtd_blktrans_dev *dev,
  79                                struct request *req)
  80 {
  81         unsigned long block, nsect;
  82         char *buf;
  83
  84         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  85         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  86
  87         buf = req->buffer;
  88
  89         if (req->cmd_type != REQ_TYPE_FS)
  90                 return -EIO;
  91
  92         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  93             get_capacity(req->rq_disk))
  94                 return -EIO;
  95
  96         if (req->cmd_flags & REQ_DISCARD)
  97                 return tr->discard(dev, block, nsect);
  98
  99         switch(rq_data_dir(req)) {
 100         case READ:
 101                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 102                         if (tr->readsect(dev, block, buf))
 103                                 return -EIO;
 104                 rq_flush_dcache_pages(req);
 105                 return 0;
 106         case WRITE:
 107                 if (!tr->writesect)
 108                         return -EIO;
 109
 110                 rq_flush_dcache_pages(req);
 111                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 112                         if (tr->writesect(dev, block, buf))
 113                                 return -EIO;
 114                 return 0;
 115         default:
 116                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
 117                 return -EIO;
 118         }
 119 }
 120
 121 int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
 122 {
 123         return dev->bg_stop;
 124 }
 125 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
 126
 127 static void mtd_blktrans_work(struct work_struct *work)
 128 {
 129         struct mtd_blktrans_dev *dev =
 130                 container_of(work, struct mtd_blktrans_dev, work);
 131         struct mtd_blktrans_ops *tr = dev->tr;
 132         struct request_queue *rq = dev->rq;
 133         struct request *req = NULL;
 134         int background_done = 0;
 135
 136         spin_lock_irq(rq->queue_lock);
 137
 138         while (1) {
 139                 int res;
 140
 141                 dev->bg_stop = false;
 142                 if (!req && !(req = blk_fetch_request(rq))) {
 143                         if (tr->background && !background_done) {
 144                                 spin_unlock_irq(rq->queue_lock);
 145                                 mutex_lock(&dev->lock);
 146                                 tr->background(dev);
 147                                 mutex_unlock(&dev->lock);
 148                                 spin_lock_irq(rq->queue_lock);
 149                                 /*
 150                                  * Do background processing just once per idle
 151                                  * period.
 152                                  */
 153                                 background_done = !dev->bg_stop;
 154                                 continue;
 155                         }
 156                         break;
 157                 }
 158
 159                 spin_unlock_irq(rq->queue_lock);
 160
 161                 mutex_lock(&dev->lock);
 162                 res = do_blktrans_request(dev->tr, dev, req);
 163                 mutex_unlock(&dev->lock);
 164
 165                 spin_lock_irq(rq->queue_lock);
 166
 167                 if (!__blk_end_request_cur(req, res))
 168                         req = NULL;
 169
 170                 background_done = 0;
 171         }
 172
 173         if (req)
 174                 __blk_end_request_all(req, -EIO);
 175
 176         spin_unlock_irq(rq->queue_lock);
 177 }
 178
 179 static void mtd_blktrans_request(struct request_queue *rq)
 180 {
 181         struct mtd_blktrans_dev *dev;
 182         struct request *req = NULL;
 183
 184         dev = rq->queuedata;
 185
 186         if (!dev)
 187                 while ((req = blk_fetch_request(rq)) != NULL)
 188                         __blk_end_request_all(req, -ENODEV);
 189         else
 190                 queue_work(dev->wq, &dev->work);
 191 }
 192
 193 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 194 {
 195         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 196         int ret = 0;
 197
 198         if (!dev)
 199                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 200
 201         mutex_lock(&dev->lock);
 202
 203         if (dev->open)
 204                 goto unlock;
 205
 206         kref_get(&dev->ref);
 207         __module_get(dev->tr->owner);
 208
 209         if (!dev->mtd)
 210                 goto unlock;
 211
 212         if (dev->tr->open) {
 213                 ret = dev->tr->open(dev);
 214                 if (ret)
 215                         goto error_put;
 216         }
 217
 218         ret = __get_mtd_device(dev->mtd);
 219         if (ret)
 220                 goto error_release;
 221         dev->file_mode = mode;
 222
 223 unlock:
 224         dev->open++;
 225         mutex_unlock(&dev->lock);
 226         blktrans_dev_put(dev);
 227         return ret;
 228
 229 error_release:
 230         if (dev->tr->release)
 231                 dev->tr->release(dev);
 232 error_put:
 233         module_put(dev->tr->owner);
 234         kref_put(&dev->ref, blktrans_dev_release);
 235         mutex_unlock(&dev->lock);
 236         blktrans_dev_put(dev);
 237         return ret;
 238 }
 239
 240 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 241 {
 242         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 243         int ret = 0;
 244
 245         if (!dev)
 246                 return ret;
 247
 248         mutex_lock(&dev->lock);
 249
 250         if (--dev->open)
 251                 goto unlock;
 252
 253         kref_put(&dev->ref, blktrans_dev_release);
 254         module_put(dev->tr->owner);
 255
 256         if (dev->mtd) {
 257                 ret = dev->tr->release ? dev->tr->release(dev) : 0;
 258                 __put_mtd_device(dev->mtd);
 259         }
 260 unlock:
 261         mutex_unlock(&dev->lock);
 262         blktrans_dev_put(dev);
 263         return ret;
 264 }
 265
 266 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 267 {
 268         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 269         int ret = -ENXIO;
 270
 271         if (!dev)
 272                 return ret;
 273
 274         mutex_lock(&dev->lock);
 275
 276         if (!dev->mtd)
 277                 goto unlock;
 278
 279         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 280 unlock:
 281         mutex_unlock(&dev->lock);
 282         blktrans_dev_put(dev);
 283         return ret;
 284 }
 285
 286 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 287                               unsigned int cmd, unsigned long arg)
 288 {
 289         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 290         int ret = -ENXIO;
 291
 292         if (!dev)
 293                 return ret;
 294
 295         mutex_lock(&dev->lock);
 296
 297         if (!dev->mtd)
 298                 goto unlock;
 299
 300         switch (cmd) {
 301         case BLKFLSBUF:
 302                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 303                 break;
 304         default:
 305                 ret = -ENOTTY;
 306         }
 307 unlock:
 308         mutex_unlock(&dev->lock);
 309         blktrans_dev_put(dev);
 310         return ret;
 311 }
 312
 313 static const struct block_device_operations mtd_block_ops = {
 314         .owner          = THIS_MODULE,
 315         .open           = blktrans_open,
 316         .release        = blktrans_release,
 317         .ioctl          = blktrans_ioctl,
 318         .getgeo         = blktrans_getgeo,
 319 };
 320
 321 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 322 {
 323         struct mtd_blktrans_ops *tr = new->tr;
 324         struct mtd_blktrans_dev *d;
 325         int last_devnum = -1;
 326         struct gendisk *gd;
 327         int ret;
 328
 329         if (mutex_trylock(&mtd_table_mutex)) {
 330                 mutex_unlock(&mtd_table_mutex);
 331                 BUG();
 332         }
 333
 334         mutex_lock(&blktrans_ref_mutex);
 335         list_for_each_entry(d, &tr->devs, list) {
 336                 if (new->devnum == -1) {
 337                         /* Use first free number */
 338                         if (d->devnum != last_devnum+1) {
 339                                 /* Found a free devnum. Plug it in here */
 340                                 new->devnum = last_devnum+1;
 341                                 list_add_tail(&new->list, &d->list);
 342                                 goto added;
 343                         }
 344                 } else if (d->devnum == new->devnum) {
 345                         /* Required number taken */
 346                         mutex_unlock(&blktrans_ref_mutex);
 347                         return -EBUSY;
 348                 } else if (d->devnum > new->devnum) {
 349                         /* Required number was free */
 350                         list_add_tail(&new->list, &d->list);
 351                         goto added;
 352                 }
 353                 last_devnum = d->devnum;
 354         }
 355
 356         ret = -EBUSY;
 357         if (new->devnum == -1)
 358                 new->devnum = last_devnum+1;
 359
 360         /* Check that the device and any partitions will get valid
 361          * minor numbers and that the disk naming code below can cope
 362          * with this number. */
 363         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 364             (tr->part_bits && new->devnum >= 27 * 26)) {
 365                 mutex_unlock(&blktrans_ref_mutex);
 366                 goto error1;
 367         }
 368
 369         list_add_tail(&new->list, &tr->devs);
 370  added:
 371         mutex_unlock(&blktrans_ref_mutex);
 372
 373         mutex_init(&new->lock);
 374         kref_init(&new->ref);
 375         if (!tr->writesect)
 376                 new->readonly = 1;
 377
 378         /* Create gendisk */
 379         ret = -ENOMEM;
 380         gd = alloc_disk(1 << tr->part_bits);
 381
 382         if (!gd)
 383                 goto error2;
 384
 385         new->disk = gd;
 386         gd->private_data = new;
 387         gd->major = tr->major;
 388         gd->first_minor = (new->devnum) << tr->part_bits;
 389         gd->fops = &mtd_block_ops;
 390
 391         if (tr->part_bits)
 392                 if (new->devnum < 26)
 393                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 394                                  "%s%c", tr->name, 'a' + new->devnum);
 395                 else
 396                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 397                                  "%s%c%c", tr->name,
 398                                  'a' - 1 + new->devnum / 26,
 399                                  'a' + new->devnum % 26);
 400         else
 401                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 402                          "%s%d", tr->name, new->devnum);
 403
 404         set_capacity(gd, (new->size * tr->blksize) >> 9);
 405
 406         /* Create the request queue */
 407         spin_lock_init(&new->queue_lock);
 408         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 409
 410         if (!new->rq)
 411                 goto error3;
 412
 413         new->rq->queuedata = new;
 414         blk_queue_logical_block_size(new->rq, tr->blksize);
 415
 416         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
 417
 418         if (tr->discard) {
 419                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
 420                 new->rq->limits.max_discard_sectors = UINT_MAX;
 421         }
 422
 423         gd->queue = new->rq;
 424
 425         /* Create processing workqueue */
 426         new->wq = alloc_workqueue("%s%d", 0, 0,
 427                                   tr->name, new->mtd->index);
 428         if (!new->wq)
 429                 goto error4;
 430         INIT_WORK(&new->work, mtd_blktrans_work);
 431
 432         gd->driverfs_dev = &new->mtd->dev;
 433
 434         if (new->readonly)
 435                 set_disk_ro(gd, 1);
 436
 437         add_disk(gd);
 438
 439         if (new->disk_attributes) {
 440                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 441                                         new->disk_attributes);
 442                 WARN_ON(ret);
 443         }
 444         return 0;
 445 error4:
 446         blk_cleanup_queue(new->rq);
 447 error3:
 448         put_disk(new->disk);
 449 error2:
 450         list_del(&new->list);
 451 error1:
 452         return ret;
 453 }
 454
 455 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 456 {
 457         unsigned long flags;
 458
 459         if (mutex_trylock(&mtd_table_mutex)) {
 460                 mutex_unlock(&mtd_table_mutex);
 461                 BUG();
 462         }
 463
 464         if (old->disk_attributes)
 465                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 466                                                 old->disk_attributes);
 467
 468         /* Stop new requests to arrive */
 469         del_gendisk(old->disk);
 470
 471         /* Stop workqueue. This will perform any pending request. */
 472         destroy_workqueue(old->wq);
 473
 474         /* Kill current requests */
 475         spin_lock_irqsave(&old->queue_lock, flags);
 476         old->rq->queuedata = NULL;
 477         blk_start_queue(old->rq);
 478         spin_unlock_irqrestore(&old->queue_lock, flags);
 479
 480         /* If the device is currently open, tell trans driver to close it,
 481                 then put mtd device, and don't touch it again */
 482         mutex_lock(&old->lock);
 483         if (old->open) {
 484                 if (old->tr->release)
 485                         old->tr->release(old);
 486                 __put_mtd_device(old->mtd);
 487         }
 488
 489         old->mtd = NULL;
 490
 491         mutex_unlock(&old->lock);
 492         blktrans_dev_put(old);
 493         return 0;
 494 }
 495
 496 static void blktrans_notify_remove(struct mtd_info *mtd)
 497 {
 498         struct mtd_blktrans_ops *tr;
 499         struct mtd_blktrans_dev *dev, *next;
 500
 501         list_for_each_entry(tr, &blktrans_majors, list)
 502                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 503                         if (dev->mtd == mtd)
 504                                 tr->remove_dev(dev);
 505 }
 506
 507 static void blktrans_notify_add(struct mtd_info *mtd)
 508 {
 509         struct mtd_blktrans_ops *tr;
 510
 511         if (mtd->type == MTD_ABSENT)
 512                 return;
 513
 514         list_for_each_entry(tr, &blktrans_majors, list)
 515                 tr->add_mtd(tr, mtd);
 516 }
 517
 518 static struct mtd_notifier blktrans_notifier = {
 519         .add = blktrans_notify_add,
 520         .remove = blktrans_notify_remove,
 521 };
 522
 523 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 524 {
 525         struct mtd_info *mtd;
 526         int ret;
 527
 528         /* Register the notifier if/when the first device type is
 529            registered, to prevent the link/init ordering from fucking
 530            us over. */
 531         if (!blktrans_notifier.list.next)
 532                 register_mtd_user(&blktrans_notifier);
 533
 534
 535         mutex_lock(&mtd_table_mutex);
 536
 537         ret = register_blkdev(tr->major, tr->name);
 538         if (ret < 0) {
 539                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 540                        tr->name, tr->major, ret);
 541                 mutex_unlock(&mtd_table_mutex);
 542                 return ret;
 543         }
 544
 545         if (ret)
 546                 tr->major = ret;
 547
 548         tr->blkshift = ffs(tr->blksize) - 1;
 549
 550         INIT_LIST_HEAD(&tr->devs);
 551         list_add(&tr->list, &blktrans_majors);
 552
 553         mtd_for_each_device(mtd)
 554                 if (mtd->type != MTD_ABSENT)
 555                         tr->add_mtd(tr, mtd);
 556
 557         mutex_unlock(&mtd_table_mutex);
 558         return 0;
 559 }
 560
 561 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 562 {
 563         struct mtd_blktrans_dev *dev, *next;
 564
 565         mutex_lock(&mtd_table_mutex);
 566
 567         /* Remove it from the list of active majors */
 568         list_del(&tr->list);
 569
 570         list_for_each_entry_safe(dev, next, &tr->devs, list)
 571                 tr->remove_dev(dev);
 572
 573         unregister_blkdev(tr->major, tr->name);
 574         mutex_unlock(&mtd_table_mutex);
 575
 576         BUG_ON(!list_empty(&tr->devs));
 577         return 0;
 578 }
 579
 580 static void __exit mtd_blktrans_exit(void)
 581 {
 582         /* No race here -- if someone's currently in register_mtd_blktrans
 583            we're screwed anyway. */
 584         if (blktrans_notifier.list.next)
 585                 unregister_mtd_user(&blktrans_notifier);
 586 }
 587
 588 module_exit(mtd_blktrans_exit);
 589
 590 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 591 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 592 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 593 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 594
 595 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 596 MODULE_LICENSE("GPL");
 597 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");