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