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/blk-mq.h>
  31 #include <linux/blkpg.h>
  32 #include <linux/spinlock.h>
  33 #include <linux/hdreg.h>
  34 #include <linux/mutex.h>
  35 #include <linux/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         blk_mq_free_tag_set(dev->tag_set);
  50         kfree(dev->tag_set);
  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 static 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 blk_status_t 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         if (req_op(req) == REQ_OP_FLUSH) {
  90                 if (tr->flush(dev))
  91                         return BLK_STS_IOERR;
  92                 return BLK_STS_OK;
  93         }
  94
  95         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  96             get_capacity(req->rq_disk))
  97                 return BLK_STS_IOERR;
  98
  99         switch (req_op(req)) {
 100         case REQ_OP_DISCARD:
 101                 if (tr->discard(dev, block, nsect))
 102                         return BLK_STS_IOERR;
 103                 return BLK_STS_OK;
 104         case REQ_OP_READ:
 105                 buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
 106                 for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
 107                         if (tr->readsect(dev, block, buf)) {
 108                                 kunmap(bio_page(req->bio));
 109                                 return BLK_STS_IOERR;
 110                         }
 111                 }
 112                 kunmap(bio_page(req->bio));
 113                 rq_flush_dcache_pages(req);
 114                 return BLK_STS_OK;
 115         case REQ_OP_WRITE:
 116                 if (!tr->writesect)
 117                         return BLK_STS_IOERR;
 118
 119                 rq_flush_dcache_pages(req);
 120                 buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
 121                 for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
 122                         if (tr->writesect(dev, block, buf)) {
 123                                 kunmap(bio_page(req->bio));
 124                                 return BLK_STS_IOERR;
 125                         }
 126                 }
 127                 kunmap(bio_page(req->bio));
 128                 return BLK_STS_OK;
 129         default:
 130                 return BLK_STS_IOERR;
 131         }
 132 }
 133
 134 int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
 135 {
 136         return dev->bg_stop;
 137 }
 138 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
 139
 140 static struct request *mtd_next_request(struct mtd_blktrans_dev *dev)
 141 {
 142         struct request *rq;
 143
 144         rq = list_first_entry_or_null(&dev->rq_list, struct request, queuelist);
 145         if (rq) {
 146                 list_del_init(&rq->queuelist);
 147                 blk_mq_start_request(rq);
 148                 return rq;
 149         }
 150
 151         return NULL;
 152 }
 153
 154 static void mtd_blktrans_work(struct mtd_blktrans_dev *dev)
 155         __releases(&dev->queue_lock)
 156         __acquires(&dev->queue_lock)
 157 {
 158         struct mtd_blktrans_ops *tr = dev->tr;
 159         struct request *req = NULL;
 160         int background_done = 0;
 161
 162         while (1) {
 163                 blk_status_t res;
 164
 165                 dev->bg_stop = false;
 166                 if (!req && !(req = mtd_next_request(dev))) {
 167                         if (tr->background && !background_done) {
 168                                 spin_unlock_irq(&dev->queue_lock);
 169                                 mutex_lock(&dev->lock);
 170                                 tr->background(dev);
 171                                 mutex_unlock(&dev->lock);
 172                                 spin_lock_irq(&dev->queue_lock);
 173                                 /*
 174                                  * Do background processing just once per idle
 175                                  * period.
 176                                  */
 177                                 background_done = !dev->bg_stop;
 178                                 continue;
 179                         }
 180                         break;
 181                 }
 182
 183                 spin_unlock_irq(&dev->queue_lock);
 184
 185                 mutex_lock(&dev->lock);
 186                 res = do_blktrans_request(dev->tr, dev, req);
 187                 mutex_unlock(&dev->lock);
 188
 189                 if (!blk_update_request(req, res, blk_rq_cur_bytes(req))) {
 190                         __blk_mq_end_request(req, res);
 191                         req = NULL;
 192                 }
 193
 194                 background_done = 0;
 195                 spin_lock_irq(&dev->queue_lock);
 196         }
 197 }
 198
 199 static blk_status_t mtd_queue_rq(struct blk_mq_hw_ctx *hctx,
 200                                  const struct blk_mq_queue_data *bd)
 201 {
 202         struct mtd_blktrans_dev *dev;
 203
 204         dev = hctx->queue->queuedata;
 205         if (!dev) {
 206                 blk_mq_start_request(bd->rq);
 207                 return BLK_STS_IOERR;
 208         }
 209
 210         spin_lock_irq(&dev->queue_lock);
 211         list_add_tail(&bd->rq->queuelist, &dev->rq_list);
 212         mtd_blktrans_work(dev);
 213         spin_unlock_irq(&dev->queue_lock);
 214
 215         return BLK_STS_OK;
 216 }
 217
 218 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 219 {
 220         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 221         int ret = 0;
 222
 223         if (!dev)
 224                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 225
 226         mutex_lock(&mtd_table_mutex);
 227         mutex_lock(&dev->lock);
 228
 229         if (dev->open)
 230                 goto unlock;
 231
 232         kref_get(&dev->ref);
 233         __module_get(dev->tr->owner);
 234
 235         if (!dev->mtd)
 236                 goto unlock;
 237
 238         if (dev->tr->open) {
 239                 ret = dev->tr->open(dev);
 240                 if (ret)
 241                         goto error_put;
 242         }
 243
 244         ret = __get_mtd_device(dev->mtd);
 245         if (ret)
 246                 goto error_release;
 247         dev->file_mode = mode;
 248
 249 unlock:
 250         dev->open++;
 251         mutex_unlock(&dev->lock);
 252         mutex_unlock(&mtd_table_mutex);
 253         blktrans_dev_put(dev);
 254         return ret;
 255
 256 error_release:
 257         if (dev->tr->release)
 258                 dev->tr->release(dev);
 259 error_put:
 260         module_put(dev->tr->owner);
 261         kref_put(&dev->ref, blktrans_dev_release);
 262         mutex_unlock(&dev->lock);
 263         mutex_unlock(&mtd_table_mutex);
 264         blktrans_dev_put(dev);
 265         return ret;
 266 }
 267
 268 static void blktrans_release(struct gendisk *disk, fmode_t mode)
 269 {
 270         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 271
 272         if (!dev)
 273                 return;
 274
 275         mutex_lock(&mtd_table_mutex);
 276         mutex_lock(&dev->lock);
 277
 278         if (--dev->open)
 279                 goto unlock;
 280
 281         kref_put(&dev->ref, blktrans_dev_release);
 282         module_put(dev->tr->owner);
 283
 284         if (dev->mtd) {
 285                 if (dev->tr->release)
 286                         dev->tr->release(dev);
 287                 __put_mtd_device(dev->mtd);
 288         }
 289 unlock:
 290         mutex_unlock(&dev->lock);
 291         mutex_unlock(&mtd_table_mutex);
 292         blktrans_dev_put(dev);
 293 }
 294
 295 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 296 {
 297         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 298         int ret = -ENXIO;
 299
 300         if (!dev)
 301                 return ret;
 302
 303         mutex_lock(&dev->lock);
 304
 305         if (!dev->mtd)
 306                 goto unlock;
 307
 308         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY;
 309 unlock:
 310         mutex_unlock(&dev->lock);
 311         blktrans_dev_put(dev);
 312         return ret;
 313 }
 314
 315 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 316                               unsigned int cmd, unsigned long arg)
 317 {
 318         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 319         int ret = -ENXIO;
 320
 321         if (!dev)
 322                 return ret;
 323
 324         mutex_lock(&dev->lock);
 325
 326         if (!dev->mtd)
 327                 goto unlock;
 328
 329         switch (cmd) {
 330         case BLKFLSBUF:
 331                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
 332                 break;
 333         default:
 334                 ret = -ENOTTY;
 335         }
 336 unlock:
 337         mutex_unlock(&dev->lock);
 338         blktrans_dev_put(dev);
 339         return ret;
 340 }
 341
 342 static const struct block_device_operations mtd_block_ops = {
 343         .owner          = THIS_MODULE,
 344         .open           = blktrans_open,
 345         .release        = blktrans_release,
 346         .ioctl          = blktrans_ioctl,
 347         .getgeo         = blktrans_getgeo,
 348 };
 349
 350 static const struct blk_mq_ops mtd_mq_ops = {
 351         .queue_rq       = mtd_queue_rq,
 352 };
 353
 354 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 355 {
 356         struct mtd_blktrans_ops *tr = new->tr;
 357         struct mtd_blktrans_dev *d;
 358         int last_devnum = -1;
 359         struct gendisk *gd;
 360         int ret;
 361
 362         if (mutex_trylock(&mtd_table_mutex)) {
 363                 mutex_unlock(&mtd_table_mutex);
 364                 BUG();
 365         }
 366
 367         mutex_lock(&blktrans_ref_mutex);
 368         list_for_each_entry(d, &tr->devs, list) {
 369                 if (new->devnum == -1) {
 370                         /* Use first free number */
 371                         if (d->devnum != last_devnum+1) {
 372                                 /* Found a free devnum. Plug it in here */
 373                                 new->devnum = last_devnum+1;
 374                                 list_add_tail(&new->list, &d->list);
 375                                 goto added;
 376                         }
 377                 } else if (d->devnum == new->devnum) {
 378                         /* Required number taken */
 379                         mutex_unlock(&blktrans_ref_mutex);
 380                         return -EBUSY;
 381                 } else if (d->devnum > new->devnum) {
 382                         /* Required number was free */
 383                         list_add_tail(&new->list, &d->list);
 384                         goto added;
 385                 }
 386                 last_devnum = d->devnum;
 387         }
 388
 389         ret = -EBUSY;
 390         if (new->devnum == -1)
 391                 new->devnum = last_devnum+1;
 392
 393         /* Check that the device and any partitions will get valid
 394          * minor numbers and that the disk naming code below can cope
 395          * with this number. */
 396         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 397             (tr->part_bits && new->devnum >= 27 * 26)) {
 398                 mutex_unlock(&blktrans_ref_mutex);
 399                 goto error1;
 400         }
 401
 402         list_add_tail(&new->list, &tr->devs);
 403  added:
 404         mutex_unlock(&blktrans_ref_mutex);
 405
 406         mutex_init(&new->lock);
 407         kref_init(&new->ref);
 408         if (!tr->writesect)
 409                 new->readonly = 1;
 410
 411         /* Create gendisk */
 412         ret = -ENOMEM;
 413         gd = alloc_disk(1 << tr->part_bits);
 414
 415         if (!gd)
 416                 goto error2;
 417
 418         new->disk = gd;
 419         gd->private_data = new;
 420         gd->major = tr->major;
 421         gd->first_minor = (new->devnum) << tr->part_bits;
 422         gd->fops = &mtd_block_ops;
 423
 424         if (tr->part_bits)
 425                 if (new->devnum < 26)
 426                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 427                                  "%s%c", tr->name, 'a' + new->devnum);
 428                 else
 429                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 430                                  "%s%c%c", tr->name,
 431                                  'a' - 1 + new->devnum / 26,
 432                                  'a' + new->devnum % 26);
 433         else
 434                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 435                          "%s%d", tr->name, new->devnum);
 436
 437         set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
 438
 439         /* Create the request queue */
 440         spin_lock_init(&new->queue_lock);
 441         INIT_LIST_HEAD(&new->rq_list);
 442
 443         new->tag_set = kzalloc(sizeof(*new->tag_set), GFP_KERNEL);
 444         if (!new->tag_set)
 445                 goto error3;
 446
 447         new->rq = blk_mq_init_sq_queue(new->tag_set, &mtd_mq_ops, 2,
 448                                 BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING);
 449         if (IS_ERR(new->rq)) {
 450                 ret = PTR_ERR(new->rq);
 451                 new->rq = NULL;
 452                 goto error4;
 453         }
 454
 455         if (tr->flush)
 456                 blk_queue_write_cache(new->rq, true, false);
 457
 458         new->rq->queuedata = new;
 459         blk_queue_logical_block_size(new->rq, tr->blksize);
 460
 461         blk_queue_flag_set(QUEUE_FLAG_NONROT, new->rq);
 462         blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq);
 463
 464         if (tr->discard) {
 465                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, new->rq);
 466                 blk_queue_max_discard_sectors(new->rq, UINT_MAX);
 467         }
 468
 469         gd->queue = new->rq;
 470
 471         if (new->readonly)
 472                 set_disk_ro(gd, 1);
 473
 474         device_add_disk(&new->mtd->dev, gd, NULL);
 475
 476         if (new->disk_attributes) {
 477                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 478                                         new->disk_attributes);
 479                 WARN_ON(ret);
 480         }
 481         return 0;
 482 error4:
 483         kfree(new->tag_set);
 484 error3:
 485         put_disk(new->disk);
 486 error2:
 487         list_del(&new->list);
 488 error1:
 489         return ret;
 490 }
 491
 492 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 493 {
 494         unsigned long flags;
 495
 496         if (mutex_trylock(&mtd_table_mutex)) {
 497                 mutex_unlock(&mtd_table_mutex);
 498                 BUG();
 499         }
 500
 501         if (old->disk_attributes)
 502                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 503                                                 old->disk_attributes);
 504
 505         /* Stop new requests to arrive */
 506         del_gendisk(old->disk);
 507
 508         /* Kill current requests */
 509         spin_lock_irqsave(&old->queue_lock, flags);
 510         old->rq->queuedata = NULL;
 511         spin_unlock_irqrestore(&old->queue_lock, flags);
 512
 513         /* freeze+quiesce queue to ensure all requests are flushed */
 514         blk_mq_freeze_queue(old->rq);
 515         blk_mq_quiesce_queue(old->rq);
 516         blk_mq_unquiesce_queue(old->rq);
 517         blk_mq_unfreeze_queue(old->rq);
 518
 519         /* If the device is currently open, tell trans driver to close it,
 520                 then put mtd device, and don't touch it again */
 521         mutex_lock(&old->lock);
 522         if (old->open) {
 523                 if (old->tr->release)
 524                         old->tr->release(old);
 525                 __put_mtd_device(old->mtd);
 526         }
 527
 528         old->mtd = NULL;
 529
 530         mutex_unlock(&old->lock);
 531         blktrans_dev_put(old);
 532         return 0;
 533 }
 534
 535 static void blktrans_notify_remove(struct mtd_info *mtd)
 536 {
 537         struct mtd_blktrans_ops *tr;
 538         struct mtd_blktrans_dev *dev, *next;
 539
 540         list_for_each_entry(tr, &blktrans_majors, list)
 541                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 542                         if (dev->mtd == mtd)
 543                                 tr->remove_dev(dev);
 544 }
 545
 546 static void blktrans_notify_add(struct mtd_info *mtd)
 547 {
 548         struct mtd_blktrans_ops *tr;
 549
 550         if (mtd->type == MTD_ABSENT)
 551                 return;
 552
 553         list_for_each_entry(tr, &blktrans_majors, list)
 554                 tr->add_mtd(tr, mtd);
 555 }
 556
 557 static struct mtd_notifier blktrans_notifier = {
 558         .add = blktrans_notify_add,
 559         .remove = blktrans_notify_remove,
 560 };
 561
 562 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 563 {
 564         struct mtd_info *mtd;
 565         int ret;
 566
 567         /* Register the notifier if/when the first device type is
 568            registered, to prevent the link/init ordering from fucking
 569            us over. */
 570         if (!blktrans_notifier.list.next)
 571                 register_mtd_user(&blktrans_notifier);
 572
 573
 574         mutex_lock(&mtd_table_mutex);
 575
 576         ret = register_blkdev(tr->major, tr->name);
 577         if (ret < 0) {
 578                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 579                        tr->name, tr->major, ret);
 580                 mutex_unlock(&mtd_table_mutex);
 581                 return ret;
 582         }
 583
 584         if (ret)
 585                 tr->major = ret;
 586
 587         tr->blkshift = ffs(tr->blksize) - 1;
 588
 589         INIT_LIST_HEAD(&tr->devs);
 590         list_add(&tr->list, &blktrans_majors);
 591
 592         mtd_for_each_device(mtd)
 593                 if (mtd->type != MTD_ABSENT)
 594                         tr->add_mtd(tr, mtd);
 595
 596         mutex_unlock(&mtd_table_mutex);
 597         return 0;
 598 }
 599
 600 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 601 {
 602         struct mtd_blktrans_dev *dev, *next;
 603
 604         mutex_lock(&mtd_table_mutex);
 605
 606         /* Remove it from the list of active majors */
 607         list_del(&tr->list);
 608
 609         list_for_each_entry_safe(dev, next, &tr->devs, list)
 610                 tr->remove_dev(dev);
 611
 612         unregister_blkdev(tr->major, tr->name);
 613         mutex_unlock(&mtd_table_mutex);
 614
 615         BUG_ON(!list_empty(&tr->devs));
 616         return 0;
 617 }
 618
 619 static void __exit mtd_blktrans_exit(void)
 620 {
 621         /* No race here -- if someone's currently in register_mtd_blktrans
 622            we're screwed anyway. */
 623         if (blktrans_notifier.list.next)
 624                 unregister_mtd_user(&blktrans_notifier);
 625 }
 626
 627 module_exit(mtd_blktrans_exit);
 628
 629 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 630 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 631 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 632 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 633
 634 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 635 MODULE_LICENSE("GPL");
 636 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");