drivers/mtd/mtd_blkdevs.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Interface to Linux block layer for MTD 'translation layers'.
   4  *
   5  * Copyright © 2003-2010 David Woodhouse <dwmw2@infradead.org>
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/slab.h>
  10 #include <linux/module.h>
  11 #include <linux/list.h>
  12 #include <linux/fs.h>
  13 #include <linux/mtd/blktrans.h>
  14 #include <linux/mtd/mtd.h>
  15 #include <linux/blkdev.h>
  16 #include <linux/blk-mq.h>
  17 #include <linux/blkpg.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/hdreg.h>
  20 #include <linux/mutex.h>
  21 #include <linux/uaccess.h>
  22
  23 #include "mtdcore.h"
  24
  25 static LIST_HEAD(blktrans_majors);
  26 static DEFINE_MUTEX(blktrans_ref_mutex);
  27
  28 static void blktrans_dev_release(struct kref *kref)
  29 {
  30         struct mtd_blktrans_dev *dev =
  31                 container_of(kref, struct mtd_blktrans_dev, ref);
  32
  33         blk_cleanup_disk(dev->disk);
  34         blk_mq_free_tag_set(dev->tag_set);
  35         kfree(dev->tag_set);
  36         list_del(&dev->list);
  37         kfree(dev);
  38 }
  39
  40 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  41 {
  42         struct mtd_blktrans_dev *dev;
  43
  44         mutex_lock(&blktrans_ref_mutex);
  45         dev = disk->private_data;
  46
  47         if (!dev)
  48                 goto unlock;
  49         kref_get(&dev->ref);
  50 unlock:
  51         mutex_unlock(&blktrans_ref_mutex);
  52         return dev;
  53 }
  54
  55 static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  56 {
  57         mutex_lock(&blktrans_ref_mutex);
  58         kref_put(&dev->ref, blktrans_dev_release);
  59         mutex_unlock(&blktrans_ref_mutex);
  60 }
  61
  62
  63 static blk_status_t do_blktrans_request(struct mtd_blktrans_ops *tr,
  64                                struct mtd_blktrans_dev *dev,
  65                                struct request *req)
  66 {
  67         unsigned long block, nsect;
  68         char *buf;
  69
  70         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  71         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  72
  73         if (req_op(req) == REQ_OP_FLUSH) {
  74                 if (tr->flush(dev))
  75                         return BLK_STS_IOERR;
  76                 return BLK_STS_OK;
  77         }
  78
  79         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  80             get_capacity(req->rq_disk))
  81                 return BLK_STS_IOERR;
  82
  83         switch (req_op(req)) {
  84         case REQ_OP_DISCARD:
  85                 if (tr->discard(dev, block, nsect))
  86                         return BLK_STS_IOERR;
  87                 return BLK_STS_OK;
  88         case REQ_OP_READ:
  89                 buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
  90                 for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
  91                         if (tr->readsect(dev, block, buf)) {
  92                                 kunmap(bio_page(req->bio));
  93                                 return BLK_STS_IOERR;
  94                         }
  95                 }
  96                 kunmap(bio_page(req->bio));
  97                 rq_flush_dcache_pages(req);
  98                 return BLK_STS_OK;
  99         case REQ_OP_WRITE:
 100                 if (!tr->writesect)
 101                         return BLK_STS_IOERR;
 102
 103                 rq_flush_dcache_pages(req);
 104                 buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
 105                 for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
 106                         if (tr->writesect(dev, block, buf)) {
 107                                 kunmap(bio_page(req->bio));
 108                                 return BLK_STS_IOERR;
 109                         }
 110                 }
 111                 kunmap(bio_page(req->bio));
 112                 return BLK_STS_OK;
 113         default:
 114                 return BLK_STS_IOERR;
 115         }
 116 }
 117
 118 int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
 119 {
 120         return dev->bg_stop;
 121 }
 122 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
 123
 124 static struct request *mtd_next_request(struct mtd_blktrans_dev *dev)
 125 {
 126         struct request *rq;
 127
 128         rq = list_first_entry_or_null(&dev->rq_list, struct request, queuelist);
 129         if (rq) {
 130                 list_del_init(&rq->queuelist);
 131                 blk_mq_start_request(rq);
 132                 return rq;
 133         }
 134
 135         return NULL;
 136 }
 137
 138 static void mtd_blktrans_work(struct mtd_blktrans_dev *dev)
 139         __releases(&dev->queue_lock)
 140         __acquires(&dev->queue_lock)
 141 {
 142         struct mtd_blktrans_ops *tr = dev->tr;
 143         struct request *req = NULL;
 144         int background_done = 0;
 145
 146         while (1) {
 147                 blk_status_t res;
 148
 149                 dev->bg_stop = false;
 150                 if (!req && !(req = mtd_next_request(dev))) {
 151                         if (tr->background && !background_done) {
 152                                 spin_unlock_irq(&dev->queue_lock);
 153                                 mutex_lock(&dev->lock);
 154                                 tr->background(dev);
 155                                 mutex_unlock(&dev->lock);
 156                                 spin_lock_irq(&dev->queue_lock);
 157                                 /*
 158                                  * Do background processing just once per idle
 159                                  * period.
 160                                  */
 161                                 background_done = !dev->bg_stop;
 162                                 continue;
 163                         }
 164                         break;
 165                 }
 166
 167                 spin_unlock_irq(&dev->queue_lock);
 168
 169                 mutex_lock(&dev->lock);
 170                 res = do_blktrans_request(dev->tr, dev, req);
 171                 mutex_unlock(&dev->lock);
 172
 173                 if (!blk_update_request(req, res, blk_rq_cur_bytes(req))) {
 174                         __blk_mq_end_request(req, res);
 175                         req = NULL;
 176                 }
 177
 178                 background_done = 0;
 179                 spin_lock_irq(&dev->queue_lock);
 180         }
 181 }
 182
 183 static blk_status_t mtd_queue_rq(struct blk_mq_hw_ctx *hctx,
 184                                  const struct blk_mq_queue_data *bd)
 185 {
 186         struct mtd_blktrans_dev *dev;
 187
 188         dev = hctx->queue->queuedata;
 189         if (!dev) {
 190                 blk_mq_start_request(bd->rq);
 191                 return BLK_STS_IOERR;
 192         }
 193
 194         spin_lock_irq(&dev->queue_lock);
 195         list_add_tail(&bd->rq->queuelist, &dev->rq_list);
 196         mtd_blktrans_work(dev);
 197         spin_unlock_irq(&dev->queue_lock);
 198
 199         return BLK_STS_OK;
 200 }
 201
 202 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 203 {
 204         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 205         int ret = 0;
 206
 207         if (!dev)
 208                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 209
 210         mutex_lock(&mtd_table_mutex);
 211         mutex_lock(&dev->lock);
 212
 213         if (dev->open)
 214                 goto unlock;
 215
 216         kref_get(&dev->ref);
 217         __module_get(dev->tr->owner);
 218
 219         if (!dev->mtd)
 220                 goto unlock;
 221
 222         if (dev->tr->open) {
 223                 ret = dev->tr->open(dev);
 224                 if (ret)
 225                         goto error_put;
 226         }
 227
 228         ret = __get_mtd_device(dev->mtd);
 229         if (ret)
 230                 goto error_release;
 231         dev->file_mode = mode;
 232
 233 unlock:
 234         dev->open++;
 235         mutex_unlock(&dev->lock);
 236         mutex_unlock(&mtd_table_mutex);
 237         blktrans_dev_put(dev);
 238         return ret;
 239
 240 error_release:
 241         if (dev->tr->release)
 242                 dev->tr->release(dev);
 243 error_put:
 244         module_put(dev->tr->owner);
 245         kref_put(&dev->ref, blktrans_dev_release);
 246         mutex_unlock(&dev->lock);
 247         mutex_unlock(&mtd_table_mutex);
 248         blktrans_dev_put(dev);
 249         return ret;
 250 }
 251
 252 static void blktrans_release(struct gendisk *disk, fmode_t mode)
 253 {
 254         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
 255
 256         if (!dev)
 257                 return;
 258
 259         mutex_lock(&mtd_table_mutex);
 260         mutex_lock(&dev->lock);
 261
 262         if (--dev->open)
 263                 goto unlock;
 264
 265         kref_put(&dev->ref, blktrans_dev_release);
 266         module_put(dev->tr->owner);
 267
 268         if (dev->mtd) {
 269                 if (dev->tr->release)
 270                         dev->tr->release(dev);
 271                 __put_mtd_device(dev->mtd);
 272         }
 273 unlock:
 274         mutex_unlock(&dev->lock);
 275         mutex_unlock(&mtd_table_mutex);
 276         blktrans_dev_put(dev);
 277 }
 278
 279 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 280 {
 281         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
 282         int ret = -ENXIO;
 283
 284         if (!dev)
 285                 return ret;
 286
 287         mutex_lock(&dev->lock);
 288
 289         if (!dev->mtd)
 290                 goto unlock;
 291
 292         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY;
 293 unlock:
 294         mutex_unlock(&dev->lock);
 295         blktrans_dev_put(dev);
 296         return ret;
 297 }
 298
 299 static const struct block_device_operations mtd_block_ops = {
 300         .owner          = THIS_MODULE,
 301         .open           = blktrans_open,
 302         .release        = blktrans_release,
 303         .getgeo         = blktrans_getgeo,
 304 };
 305
 306 static const struct blk_mq_ops mtd_mq_ops = {
 307         .queue_rq       = mtd_queue_rq,
 308 };
 309
 310 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 311 {
 312         struct mtd_blktrans_ops *tr = new->tr;
 313         struct mtd_blktrans_dev *d;
 314         int last_devnum = -1;
 315         struct gendisk *gd;
 316         int ret;
 317
 318         if (mutex_trylock(&mtd_table_mutex)) {
 319                 mutex_unlock(&mtd_table_mutex);
 320                 BUG();
 321         }
 322
 323         mutex_lock(&blktrans_ref_mutex);
 324         list_for_each_entry(d, &tr->devs, list) {
 325                 if (new->devnum == -1) {
 326                         /* Use first free number */
 327                         if (d->devnum != last_devnum+1) {
 328                                 /* Found a free devnum. Plug it in here */
 329                                 new->devnum = last_devnum+1;
 330                                 list_add_tail(&new->list, &d->list);
 331                                 goto added;
 332                         }
 333                 } else if (d->devnum == new->devnum) {
 334                         /* Required number taken */
 335                         mutex_unlock(&blktrans_ref_mutex);
 336                         return -EBUSY;
 337                 } else if (d->devnum > new->devnum) {
 338                         /* Required number was free */
 339                         list_add_tail(&new->list, &d->list);
 340                         goto added;
 341                 }
 342                 last_devnum = d->devnum;
 343         }
 344
 345         ret = -EBUSY;
 346         if (new->devnum == -1)
 347                 new->devnum = last_devnum+1;
 348
 349         /* Check that the device and any partitions will get valid
 350          * minor numbers and that the disk naming code below can cope
 351          * with this number. */
 352         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 353             (tr->part_bits && new->devnum >= 27 * 26)) {
 354                 mutex_unlock(&blktrans_ref_mutex);
 355                 return ret;
 356         }
 357
 358         list_add_tail(&new->list, &tr->devs);
 359  added:
 360         mutex_unlock(&blktrans_ref_mutex);
 361
 362         mutex_init(&new->lock);
 363         kref_init(&new->ref);
 364         if (!tr->writesect)
 365                 new->readonly = 1;
 366
 367         ret = -ENOMEM;
 368         new->tag_set = kzalloc(sizeof(*new->tag_set), GFP_KERNEL);
 369         if (!new->tag_set)
 370                 goto out_list_del;
 371
 372         ret = blk_mq_alloc_sq_tag_set(new->tag_set, &mtd_mq_ops, 2,
 373                         BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING);
 374         if (ret)
 375                 goto out_kfree_tag_set;
 376
 377         /* Create gendisk */
 378         gd = blk_mq_alloc_disk(new->tag_set, new);
 379         if (IS_ERR(gd)) {
 380                 ret = PTR_ERR(gd);
 381                 goto out_free_tag_set;
 382         }
 383
 384         new->disk = gd;
 385         new->rq = new->disk->queue;
 386         gd->private_data = new;
 387         gd->major = tr->major;
 388         gd->first_minor = (new->devnum) << tr->part_bits;
 389         gd->minors = 1 << tr->part_bits;
 390         gd->fops = &mtd_block_ops;
 391
 392         if (tr->part_bits)
 393                 if (new->devnum < 26)
 394                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 395                                  "%s%c", tr->name, 'a' + new->devnum);
 396                 else
 397                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 398                                  "%s%c%c", tr->name,
 399                                  'a' - 1 + new->devnum / 26,
 400                                  'a' + new->devnum % 26);
 401         else
 402                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 403                          "%s%d", tr->name, new->devnum);
 404
 405         set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
 406
 407         /* Create the request queue */
 408         spin_lock_init(&new->queue_lock);
 409         INIT_LIST_HEAD(&new->rq_list);
 410
 411         if (tr->flush)
 412                 blk_queue_write_cache(new->rq, true, false);
 413
 414         blk_queue_logical_block_size(new->rq, tr->blksize);
 415
 416         blk_queue_flag_set(QUEUE_FLAG_NONROT, new->rq);
 417         blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq);
 418
 419         if (tr->discard) {
 420                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, new->rq);
 421                 blk_queue_max_discard_sectors(new->rq, UINT_MAX);
 422                 new->rq->limits.discard_granularity = tr->blksize;
 423         }
 424
 425         gd->queue = new->rq;
 426
 427         if (new->readonly)
 428                 set_disk_ro(gd, 1);
 429
 430         device_add_disk(&new->mtd->dev, gd, NULL);
 431
 432         if (new->disk_attributes) {
 433                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 434                                         new->disk_attributes);
 435                 WARN_ON(ret);
 436         }
 437         return 0;
 438
 439 out_free_tag_set:
 440         blk_mq_free_tag_set(new->tag_set);
 441 out_kfree_tag_set:
 442         kfree(new->tag_set);
 443 out_list_del:
 444         list_del(&new->list);
 445         return ret;
 446 }
 447
 448 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 449 {
 450         unsigned long flags;
 451
 452         if (mutex_trylock(&mtd_table_mutex)) {
 453                 mutex_unlock(&mtd_table_mutex);
 454                 BUG();
 455         }
 456
 457         if (old->disk_attributes)
 458                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
 459                                                 old->disk_attributes);
 460
 461         /* Stop new requests to arrive */
 462         del_gendisk(old->disk);
 463
 464         /* Kill current requests */
 465         spin_lock_irqsave(&old->queue_lock, flags);
 466         old->rq->queuedata = NULL;
 467         spin_unlock_irqrestore(&old->queue_lock, flags);
 468
 469         /* freeze+quiesce queue to ensure all requests are flushed */
 470         blk_mq_freeze_queue(old->rq);
 471         blk_mq_quiesce_queue(old->rq);
 472         blk_mq_unquiesce_queue(old->rq);
 473         blk_mq_unfreeze_queue(old->rq);
 474
 475         /* If the device is currently open, tell trans driver to close it,
 476                 then put mtd device, and don't touch it again */
 477         mutex_lock(&old->lock);
 478         if (old->open) {
 479                 if (old->tr->release)
 480                         old->tr->release(old);
 481                 __put_mtd_device(old->mtd);
 482         }
 483
 484         old->mtd = NULL;
 485
 486         mutex_unlock(&old->lock);
 487         blktrans_dev_put(old);
 488         return 0;
 489 }
 490
 491 static void blktrans_notify_remove(struct mtd_info *mtd)
 492 {
 493         struct mtd_blktrans_ops *tr;
 494         struct mtd_blktrans_dev *dev, *next;
 495
 496         list_for_each_entry(tr, &blktrans_majors, list)
 497                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 498                         if (dev->mtd == mtd)
 499                                 tr->remove_dev(dev);
 500 }
 501
 502 static void blktrans_notify_add(struct mtd_info *mtd)
 503 {
 504         struct mtd_blktrans_ops *tr;
 505
 506         if (mtd->type == MTD_ABSENT)
 507                 return;
 508
 509         list_for_each_entry(tr, &blktrans_majors, list)
 510                 tr->add_mtd(tr, mtd);
 511 }
 512
 513 static struct mtd_notifier blktrans_notifier = {
 514         .add = blktrans_notify_add,
 515         .remove = blktrans_notify_remove,
 516 };
 517
 518 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 519 {
 520         struct mtd_info *mtd;
 521         int ret;
 522
 523         /* Register the notifier if/when the first device type is
 524            registered, to prevent the link/init ordering from fucking
 525            us over. */
 526         if (!blktrans_notifier.list.next)
 527                 register_mtd_user(&blktrans_notifier);
 528
 529         ret = register_blkdev(tr->major, tr->name);
 530         if (ret < 0) {
 531                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 532                        tr->name, tr->major, ret);
 533                 return ret;
 534         }
 535
 536         if (ret)
 537                 tr->major = ret;
 538
 539         tr->blkshift = ffs(tr->blksize) - 1;
 540
 541         INIT_LIST_HEAD(&tr->devs);
 542
 543         mutex_lock(&mtd_table_mutex);
 544         list_add(&tr->list, &blktrans_majors);
 545         mtd_for_each_device(mtd)
 546                 if (mtd->type != MTD_ABSENT)
 547                         tr->add_mtd(tr, mtd);
 548         mutex_unlock(&mtd_table_mutex);
 549         return 0;
 550 }
 551
 552 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 553 {
 554         struct mtd_blktrans_dev *dev, *next;
 555
 556         mutex_lock(&mtd_table_mutex);
 557
 558         /* Remove it from the list of active majors */
 559         list_del(&tr->list);
 560
 561         list_for_each_entry_safe(dev, next, &tr->devs, list)
 562                 tr->remove_dev(dev);
 563
 564         mutex_unlock(&mtd_table_mutex);
 565         unregister_blkdev(tr->major, tr->name);
 566
 567         BUG_ON(!list_empty(&tr->devs));
 568         return 0;
 569 }
 570
 571 static void __exit mtd_blktrans_exit(void)
 572 {
 573         /* No race here -- if someone's currently in register_mtd_blktrans
 574            we're screwed anyway. */
 575         if (blktrans_notifier.list.next)
 576                 unregister_mtd_user(&blktrans_notifier);
 577 }
 578
 579 module_exit(mtd_blktrans_exit);
 580
 581 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 582 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 583 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 584 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 585
 586 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 587 MODULE_LICENSE("GPL");
 588 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");