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