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