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         mutex_lock(&mtd_table_mutex);
 203
 204         if (dev->open)
 205                 goto unlock;
 206
 207         kref_get(&dev->ref);
 208         __module_get(dev->tr->owner);
 209
 210         if (!dev->mtd)
 211                 goto unlock;
 212
 213         if (dev->tr->open) {
 214                 ret = dev->tr->open(dev);
 215                 if (ret)
 216                         goto error_put;
 217         }
 218
 219         ret = __get_mtd_device(dev->mtd);
 220         if (ret)
 221                 goto error_release;
 222         dev->file_mode = mode;
 223
 224 unlock:
 225         dev->open++;
 226         mutex_unlock(&mtd_table_mutex);
 227         mutex_unlock(&dev->lock);
 228         blktrans_dev_put(dev);
 229         return ret;
 230
 231 error_release:
 232         if (dev->tr->release)
 233                 dev->tr->release(dev);
 234 error_put:
 235         module_put(dev->tr->owner);
 236         kref_put(&dev->ref, blktrans_dev_release);
 237         mutex_unlock(&mtd_table_mutex);
 238         mutex_unlock(&dev->lock);
 239         blktrans_dev_put(dev);
 240         return ret;
 241 }
 242
 243 static void blktrans_release(struct gendisk *disk, fmode_t mode)
 244 {
 245         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 246
 247         if (!dev)
 248                 return;
 249
 250         mutex_lock(&dev->lock);
 251         mutex_lock(&mtd_table_mutex);
 252
 253         if (--dev->open)
 254                 goto unlock;
 255
 256         kref_put(&dev->ref, blktrans_dev_release);
 257         module_put(dev->tr->owner);
 258
 259         if (dev->mtd) {
 260                 if (dev->tr->release)
 261                         dev->tr->release(dev);
 262                 __put_mtd_device(dev->mtd);
 263         }
 264 unlock:
 265         mutex_unlock(&mtd_table_mutex);
 266         mutex_unlock(&dev->lock);
 267         blktrans_dev_put(dev);
 268 }
 269
 270 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 271 {
 272         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 273         int ret = -ENXIO;
 274
 275         if (!dev)
 276                 return ret;
 277
 278         mutex_lock(&dev->lock);
 279
 280         if (!dev->mtd)
 281                 goto unlock;
 282
 283         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
 284 unlock:
 285         mutex_unlock(&dev->lock);
 286         blktrans_dev_put(dev);
 287         return ret;
 288 }
 289
 290 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 291                               unsigned int cmd, unsigned long arg)
 292 {
 293         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 294         int ret = -ENXIO;
 295
 296         if (!dev)
 297                 return ret;
 298
 299         mutex_lock(&dev->lock);
 300
 301         if (!dev->mtd)
 302                 goto unlock;
 303
 304         switch (cmd) {
 305         case BLKFLSBUF:
 306                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 307                 break;
 308         default:
 309                 ret = -ENOTTY;
 310         }
 311 unlock:
 312         mutex_unlock(&dev->lock);
 313         blktrans_dev_put(dev);
 314         return ret;
 315 }
 316
 317 static const struct block_device_operations mtd_block_ops = {
 318         .owner          = THIS_MODULE,
 319         .open           = blktrans_open,
 320         .release        = blktrans_release,
 321         .ioctl          = blktrans_ioctl,
 322         .getgeo         = blktrans_getgeo,
 323 };
 324
 325 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 326 {
 327         struct mtd_blktrans_ops *tr = new->tr;
 328         struct mtd_blktrans_dev *d;
 329         int last_devnum = -1;
 330         struct gendisk *gd;
 331         int ret;
 332
 333         if (mutex_trylock(&mtd_table_mutex)) {
 334                 mutex_unlock(&mtd_table_mutex);
 335                 BUG();
 336         }
 337
 338         mutex_lock(&blktrans_ref_mutex);
 339         list_for_each_entry(d, &tr->devs, list) {
 340                 if (new->devnum == -1) {
 341                         /* Use first free number */
 342                         if (d->devnum != last_devnum+1) {
 343                                 /* Found a free devnum. Plug it in here */
 344                                 new->devnum = last_devnum+1;
 345                                 list_add_tail(&new->list, &d->list);
 346                                 goto added;
 347                         }
 348                 } else if (d->devnum == new->devnum) {
 349                         /* Required number taken */
 350                         mutex_unlock(&blktrans_ref_mutex);
 351                         return -EBUSY;
 352                 } else if (d->devnum > new->devnum) {
 353                         /* Required number was free */
 354                         list_add_tail(&new->list, &d->list);
 355                         goto added;
 356                 }
 357                 last_devnum = d->devnum;
 358         }
 359
 360         ret = -EBUSY;
 361         if (new->devnum == -1)
 362                 new->devnum = last_devnum+1;
 363
 364         /* Check that the device and any partitions will get valid
 365          * minor numbers and that the disk naming code below can cope
 366          * with this number. */
 367         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 368             (tr->part_bits && new->devnum >= 27 * 26)) {
 369                 mutex_unlock(&blktrans_ref_mutex);
 370                 goto error1;
 371         }
 372
 373         list_add_tail(&new->list, &tr->devs);
 374  added:
 375         mutex_unlock(&blktrans_ref_mutex);
 376
 377         mutex_init(&new->lock);
 378         kref_init(&new->ref);
 379         if (!tr->writesect)
 380                 new->readonly = 1;
 381
 382         /* Create gendisk */
 383         ret = -ENOMEM;
 384         gd = alloc_disk(1 << tr->part_bits);
 385
 386         if (!gd)
 387                 goto error2;
 388
 389         new->disk = gd;
 390         gd->private_data = new;
 391         gd->major = tr->major;
 392         gd->first_minor = (new->devnum) << tr->part_bits;
 393         gd->fops = &mtd_block_ops;
 394
 395         if (tr->part_bits)
 396                 if (new->devnum < 26)
 397                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 398                                  "%s%c", tr->name, 'a' + new->devnum);
 399                 else
 400                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 401                                  "%s%c%c", tr->name,
 402                                  'a' - 1 + new->devnum / 26,
 403                                  'a' + new->devnum % 26);
 404         else
 405                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 406                          "%s%d", tr->name, new->devnum);
 407
 408         set_capacity(gd, (new->size * tr->blksize) >> 9);
 409
 410         /* Create the request queue */
 411         spin_lock_init(&new->queue_lock);
 412         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
 413
 414         if (!new->rq)
 415                 goto error3;
 416
 417         new->rq->queuedata = new;
 418         blk_queue_logical_block_size(new->rq, tr->blksize);
 419
 420         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
 421
 422         if (tr->discard) {
 423                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
 424                 new->rq->limits.max_discard_sectors = UINT_MAX;
 425         }
 426
 427         gd->queue = new->rq;
 428
 429         /* Create processing workqueue */
 430         new->wq = alloc_workqueue("%s%d", 0, 0,
 431                                   tr->name, new->mtd->index);
 432         if (!new->wq)
 433                 goto error4;
 434         INIT_WORK(&new->work, mtd_blktrans_work);
 435
 436         gd->driverfs_dev = &new->mtd->dev;
 437
 438         if (new->readonly)
 439                 set_disk_ro(gd, 1);
 440
 441         add_disk(gd);
 442
 443         if (new->disk_attributes) {
 444                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 445                                         new->disk_attributes);
 446                 WARN_ON(ret);
 447         }
 448         return 0;
 449 error4:
 450         blk_cleanup_queue(new->rq);
 451 error3:
 452         put_disk(new->disk);
 453 error2:
 454         list_del(&new->list);
 455 error1:
 456         return ret;
 457 }
 458
 459 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 460 {
 461         unsigned long flags;
 462
 463         if (mutex_trylock(&mtd_table_mutex)) {
 464                 mutex_unlock(&mtd_table_mutex);
 465                 BUG();
 466         }
 467
 468         if (old->disk_attributes)
 469                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 470                                                 old->disk_attributes);
 471
 472         /* Stop new requests to arrive */
 473         del_gendisk(old->disk);
 474
 475         /* Stop workqueue. This will perform any pending request. */
 476         destroy_workqueue(old->wq);
 477
 478         /* Kill current requests */
 479         spin_lock_irqsave(&old->queue_lock, flags);
 480         old->rq->queuedata = NULL;
 481         blk_start_queue(old->rq);
 482         spin_unlock_irqrestore(&old->queue_lock, flags);
 483
 484         /* If the device is currently open, tell trans driver to close it,
 485                 then put mtd device, and don't touch it again */
 486         mutex_lock(&old->lock);
 487         if (old->open) {
 488                 if (old->tr->release)
 489                         old->tr->release(old);
 490                 __put_mtd_device(old->mtd);
 491         }
 492
 493         old->mtd = NULL;
 494
 495         mutex_unlock(&old->lock);
 496         blktrans_dev_put(old);
 497         return 0;
 498 }
 499
 500 static void blktrans_notify_remove(struct mtd_info *mtd)
 501 {
 502         struct mtd_blktrans_ops *tr;
 503         struct mtd_blktrans_dev *dev, *next;
 504
 505         list_for_each_entry(tr, &blktrans_majors, list)
 506                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 507                         if (dev->mtd == mtd)
 508                                 tr->remove_dev(dev);
 509 }
 510
 511 static void blktrans_notify_add(struct mtd_info *mtd)
 512 {
 513         struct mtd_blktrans_ops *tr;
 514
 515         if (mtd->type == MTD_ABSENT)
 516                 return;
 517
 518         list_for_each_entry(tr, &blktrans_majors, list)
 519                 tr->add_mtd(tr, mtd);
 520 }
 521
 522 static struct mtd_notifier blktrans_notifier = {
 523         .add = blktrans_notify_add,
 524         .remove = blktrans_notify_remove,
 525 };
 526
 527 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 528 {
 529         struct mtd_info *mtd;
 530         int ret;
 531
 532         /* Register the notifier if/when the first device type is
 533            registered, to prevent the link/init ordering from fucking
 534            us over. */
 535         if (!blktrans_notifier.list.next)
 536                 register_mtd_user(&blktrans_notifier);
 537
 538
 539         mutex_lock(&mtd_table_mutex);
 540
 541         ret = register_blkdev(tr->major, tr->name);
 542         if (ret < 0) {
 543                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 544                        tr->name, tr->major, ret);
 545                 mutex_unlock(&mtd_table_mutex);
 546                 return ret;
 547         }
 548
 549         if (ret)
 550                 tr->major = ret;
 551
 552         tr->blkshift = ffs(tr->blksize) - 1;
 553
 554         INIT_LIST_HEAD(&tr->devs);
 555         list_add(&tr->list, &blktrans_majors);
 556
 557         mtd_for_each_device(mtd)
 558                 if (mtd->type != MTD_ABSENT)
 559                         tr->add_mtd(tr, mtd);
 560
 561         mutex_unlock(&mtd_table_mutex);
 562         return 0;
 563 }
 564
 565 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 566 {
 567         struct mtd_blktrans_dev *dev, *next;
 568
 569         mutex_lock(&mtd_table_mutex);
 570
 571         /* Remove it from the list of active majors */
 572         list_del(&tr->list);
 573
 574         list_for_each_entry_safe(dev, next, &tr->devs, list)
 575                 tr->remove_dev(dev);
 576
 577         unregister_blkdev(tr->major, tr->name);
 578         mutex_unlock(&mtd_table_mutex);
 579
 580         BUG_ON(!list_empty(&tr->devs));
 581         return 0;
 582 }
 583
 584 static void __exit mtd_blktrans_exit(void)
 585 {
 586         /* No race here -- if someone's currently in register_mtd_blktrans
 587            we're screwed anyway. */
 588         if (blktrans_notifier.list.next)
 589                 unregister_mtd_user(&blktrans_notifier);
 590 }
 591
 592 module_exit(mtd_blktrans_exit);
 593
 594 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 595 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 596 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 597 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 598
 599 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 600 MODULE_LICENSE("GPL");
 601 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");