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 dev->disk->private_data = NULL; 34 blk_cleanup_queue(dev->rq); 35 blk_mq_free_tag_set(dev->tag_set); 36 kfree(dev->tag_set); 37 put_disk(dev->disk); 38 list_del(&dev->list); 39 kfree(dev); 40 } 41 42 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk) 43 { 44 struct mtd_blktrans_dev *dev; 45 46 mutex_lock(&blktrans_ref_mutex); 47 dev = disk->private_data; 48 49 if (!dev) 50 goto unlock; 51 kref_get(&dev->ref); 52 unlock: 53 mutex_unlock(&blktrans_ref_mutex); 54 return dev; 55 } 56 57 static void blktrans_dev_put(struct mtd_blktrans_dev *dev) 58 { 59 mutex_lock(&blktrans_ref_mutex); 60 kref_put(&dev->ref, blktrans_dev_release); 61 mutex_unlock(&blktrans_ref_mutex); 62 } 63 64 65 static blk_status_t do_blktrans_request(struct mtd_blktrans_ops *tr, 66 struct mtd_blktrans_dev *dev, 67 struct request *req) 68 { 69 unsigned long block, nsect; 70 char *buf; 71 72 block = blk_rq_pos(req) << 9 >> tr->blkshift; 73 nsect = blk_rq_cur_bytes(req) >> tr->blkshift; 74 75 if (req_op(req) == REQ_OP_FLUSH) { 76 if (tr->flush(dev)) 77 return BLK_STS_IOERR; 78 return BLK_STS_OK; 79 } 80 81 if (blk_rq_pos(req) + blk_rq_cur_sectors(req) > 82 get_capacity(req->rq_disk)) 83 return BLK_STS_IOERR; 84 85 switch (req_op(req)) { 86 case REQ_OP_DISCARD: 87 if (tr->discard(dev, block, nsect)) 88 return BLK_STS_IOERR; 89 return BLK_STS_OK; 90 case REQ_OP_READ: 91 buf = kmap(bio_page(req->bio)) + bio_offset(req->bio); 92 for (; nsect > 0; nsect--, block++, buf += tr->blksize) { 93 if (tr->readsect(dev, block, buf)) { 94 kunmap(bio_page(req->bio)); 95 return BLK_STS_IOERR; 96 } 97 } 98 kunmap(bio_page(req->bio)); 99 rq_flush_dcache_pages(req); 100 return BLK_STS_OK; 101 case REQ_OP_WRITE: 102 if (!tr->writesect) 103 return BLK_STS_IOERR; 104 105 rq_flush_dcache_pages(req); 106 buf = kmap(bio_page(req->bio)) + bio_offset(req->bio); 107 for (; nsect > 0; nsect--, block++, buf += tr->blksize) { 108 if (tr->writesect(dev, block, buf)) { 109 kunmap(bio_page(req->bio)); 110 return BLK_STS_IOERR; 111 } 112 } 113 kunmap(bio_page(req->bio)); 114 return BLK_STS_OK; 115 default: 116 return BLK_STS_IOERR; 117 } 118 } 119 120 int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev) 121 { 122 return dev->bg_stop; 123 } 124 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background); 125 126 static struct request *mtd_next_request(struct mtd_blktrans_dev *dev) 127 { 128 struct request *rq; 129 130 rq = list_first_entry_or_null(&dev->rq_list, struct request, queuelist); 131 if (rq) { 132 list_del_init(&rq->queuelist); 133 blk_mq_start_request(rq); 134 return rq; 135 } 136 137 return NULL; 138 } 139 140 static void mtd_blktrans_work(struct mtd_blktrans_dev *dev) 141 __releases(&dev->queue_lock) 142 __acquires(&dev->queue_lock) 143 { 144 struct mtd_blktrans_ops *tr = dev->tr; 145 struct request *req = NULL; 146 int background_done = 0; 147 148 while (1) { 149 blk_status_t res; 150 151 dev->bg_stop = false; 152 if (!req && !(req = mtd_next_request(dev))) { 153 if (tr->background && !background_done) { 154 spin_unlock_irq(&dev->queue_lock); 155 mutex_lock(&dev->lock); 156 tr->background(dev); 157 mutex_unlock(&dev->lock); 158 spin_lock_irq(&dev->queue_lock); 159 /* 160 * Do background processing just once per idle 161 * period. 162 */ 163 background_done = !dev->bg_stop; 164 continue; 165 } 166 break; 167 } 168 169 spin_unlock_irq(&dev->queue_lock); 170 171 mutex_lock(&dev->lock); 172 res = do_blktrans_request(dev->tr, dev, req); 173 mutex_unlock(&dev->lock); 174 175 if (!blk_update_request(req, res, blk_rq_cur_bytes(req))) { 176 __blk_mq_end_request(req, res); 177 req = NULL; 178 } 179 180 background_done = 0; 181 spin_lock_irq(&dev->queue_lock); 182 } 183 } 184 185 static blk_status_t mtd_queue_rq(struct blk_mq_hw_ctx *hctx, 186 const struct blk_mq_queue_data *bd) 187 { 188 struct mtd_blktrans_dev *dev; 189 190 dev = hctx->queue->queuedata; 191 if (!dev) { 192 blk_mq_start_request(bd->rq); 193 return BLK_STS_IOERR; 194 } 195 196 spin_lock_irq(&dev->queue_lock); 197 list_add_tail(&bd->rq->queuelist, &dev->rq_list); 198 mtd_blktrans_work(dev); 199 spin_unlock_irq(&dev->queue_lock); 200 201 return BLK_STS_OK; 202 } 203 204 static int blktrans_open(struct block_device *bdev, fmode_t mode) 205 { 206 struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk); 207 int ret = 0; 208 209 if (!dev) 210 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/ 211 212 mutex_lock(&mtd_table_mutex); 213 mutex_lock(&dev->lock); 214 215 if (dev->open) 216 goto unlock; 217 218 kref_get(&dev->ref); 219 __module_get(dev->tr->owner); 220 221 if (!dev->mtd) 222 goto unlock; 223 224 if (dev->tr->open) { 225 ret = dev->tr->open(dev); 226 if (ret) 227 goto error_put; 228 } 229 230 ret = __get_mtd_device(dev->mtd); 231 if (ret) 232 goto error_release; 233 dev->file_mode = mode; 234 235 unlock: 236 dev->open++; 237 mutex_unlock(&dev->lock); 238 mutex_unlock(&mtd_table_mutex); 239 blktrans_dev_put(dev); 240 return ret; 241 242 error_release: 243 if (dev->tr->release) 244 dev->tr->release(dev); 245 error_put: 246 module_put(dev->tr->owner); 247 kref_put(&dev->ref, blktrans_dev_release); 248 mutex_unlock(&dev->lock); 249 mutex_unlock(&mtd_table_mutex); 250 blktrans_dev_put(dev); 251 return ret; 252 } 253 254 static void blktrans_release(struct gendisk *disk, fmode_t mode) 255 { 256 struct mtd_blktrans_dev *dev = blktrans_dev_get(disk); 257 258 if (!dev) 259 return; 260 261 mutex_lock(&mtd_table_mutex); 262 mutex_lock(&dev->lock); 263 264 if (--dev->open) 265 goto unlock; 266 267 kref_put(&dev->ref, blktrans_dev_release); 268 module_put(dev->tr->owner); 269 270 if (dev->mtd) { 271 if (dev->tr->release) 272 dev->tr->release(dev); 273 __put_mtd_device(dev->mtd); 274 } 275 unlock: 276 mutex_unlock(&dev->lock); 277 mutex_unlock(&mtd_table_mutex); 278 blktrans_dev_put(dev); 279 } 280 281 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo) 282 { 283 struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk); 284 int ret = -ENXIO; 285 286 if (!dev) 287 return ret; 288 289 mutex_lock(&dev->lock); 290 291 if (!dev->mtd) 292 goto unlock; 293 294 ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY; 295 unlock: 296 mutex_unlock(&dev->lock); 297 blktrans_dev_put(dev); 298 return ret; 299 } 300 301 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode, 302 unsigned int cmd, unsigned long arg) 303 { 304 struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk); 305 int ret = -ENXIO; 306 307 if (!dev) 308 return ret; 309 310 mutex_lock(&dev->lock); 311 312 if (!dev->mtd) 313 goto unlock; 314 315 switch (cmd) { 316 case BLKFLSBUF: 317 ret = dev->tr->flush ? dev->tr->flush(dev) : 0; 318 break; 319 default: 320 ret = -ENOTTY; 321 } 322 unlock: 323 mutex_unlock(&dev->lock); 324 blktrans_dev_put(dev); 325 return ret; 326 } 327 328 static const struct block_device_operations mtd_block_ops = { 329 .owner = THIS_MODULE, 330 .open = blktrans_open, 331 .release = blktrans_release, 332 .ioctl = blktrans_ioctl, 333 .getgeo = blktrans_getgeo, 334 }; 335 336 static const struct blk_mq_ops mtd_mq_ops = { 337 .queue_rq = mtd_queue_rq, 338 }; 339 340 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) 341 { 342 struct mtd_blktrans_ops *tr = new->tr; 343 struct mtd_blktrans_dev *d; 344 int last_devnum = -1; 345 struct gendisk *gd; 346 int ret; 347 348 if (mutex_trylock(&mtd_table_mutex)) { 349 mutex_unlock(&mtd_table_mutex); 350 BUG(); 351 } 352 353 mutex_lock(&blktrans_ref_mutex); 354 list_for_each_entry(d, &tr->devs, list) { 355 if (new->devnum == -1) { 356 /* Use first free number */ 357 if (d->devnum != last_devnum+1) { 358 /* Found a free devnum. Plug it in here */ 359 new->devnum = last_devnum+1; 360 list_add_tail(&new->list, &d->list); 361 goto added; 362 } 363 } else if (d->devnum == new->devnum) { 364 /* Required number taken */ 365 mutex_unlock(&blktrans_ref_mutex); 366 return -EBUSY; 367 } else if (d->devnum > new->devnum) { 368 /* Required number was free */ 369 list_add_tail(&new->list, &d->list); 370 goto added; 371 } 372 last_devnum = d->devnum; 373 } 374 375 ret = -EBUSY; 376 if (new->devnum == -1) 377 new->devnum = last_devnum+1; 378 379 /* Check that the device and any partitions will get valid 380 * minor numbers and that the disk naming code below can cope 381 * with this number. */ 382 if (new->devnum > (MINORMASK >> tr->part_bits) || 383 (tr->part_bits && new->devnum >= 27 * 26)) { 384 mutex_unlock(&blktrans_ref_mutex); 385 goto error1; 386 } 387 388 list_add_tail(&new->list, &tr->devs); 389 added: 390 mutex_unlock(&blktrans_ref_mutex); 391 392 mutex_init(&new->lock); 393 kref_init(&new->ref); 394 if (!tr->writesect) 395 new->readonly = 1; 396 397 /* Create gendisk */ 398 ret = -ENOMEM; 399 gd = alloc_disk(1 << tr->part_bits); 400 401 if (!gd) 402 goto error2; 403 404 new->disk = gd; 405 gd->private_data = new; 406 gd->major = tr->major; 407 gd->first_minor = (new->devnum) << tr->part_bits; 408 gd->fops = &mtd_block_ops; 409 410 if (tr->part_bits) 411 if (new->devnum < 26) 412 snprintf(gd->disk_name, sizeof(gd->disk_name), 413 "%s%c", tr->name, 'a' + new->devnum); 414 else 415 snprintf(gd->disk_name, sizeof(gd->disk_name), 416 "%s%c%c", tr->name, 417 'a' - 1 + new->devnum / 26, 418 'a' + new->devnum % 26); 419 else 420 snprintf(gd->disk_name, sizeof(gd->disk_name), 421 "%s%d", tr->name, new->devnum); 422 423 set_capacity(gd, ((u64)new->size * tr->blksize) >> 9); 424 425 /* Create the request queue */ 426 spin_lock_init(&new->queue_lock); 427 INIT_LIST_HEAD(&new->rq_list); 428 429 new->tag_set = kzalloc(sizeof(*new->tag_set), GFP_KERNEL); 430 if (!new->tag_set) 431 goto error3; 432 433 new->rq = blk_mq_init_sq_queue(new->tag_set, &mtd_mq_ops, 2, 434 BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING); 435 if (IS_ERR(new->rq)) { 436 ret = PTR_ERR(new->rq); 437 new->rq = NULL; 438 goto error4; 439 } 440 441 if (tr->flush) 442 blk_queue_write_cache(new->rq, true, false); 443 444 new->rq->queuedata = new; 445 blk_queue_logical_block_size(new->rq, tr->blksize); 446 447 blk_queue_flag_set(QUEUE_FLAG_NONROT, new->rq); 448 blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq); 449 450 if (tr->discard) { 451 blk_queue_flag_set(QUEUE_FLAG_DISCARD, new->rq); 452 blk_queue_max_discard_sectors(new->rq, UINT_MAX); 453 } 454 455 gd->queue = new->rq; 456 457 if (new->readonly) 458 set_disk_ro(gd, 1); 459 460 device_add_disk(&new->mtd->dev, gd, NULL); 461 462 if (new->disk_attributes) { 463 ret = sysfs_create_group(&disk_to_dev(gd)->kobj, 464 new->disk_attributes); 465 WARN_ON(ret); 466 } 467 return 0; 468 error4: 469 kfree(new->tag_set); 470 error3: 471 put_disk(new->disk); 472 error2: 473 list_del(&new->list); 474 error1: 475 return ret; 476 } 477 478 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) 479 { 480 unsigned long flags; 481 482 if (mutex_trylock(&mtd_table_mutex)) { 483 mutex_unlock(&mtd_table_mutex); 484 BUG(); 485 } 486 487 if (old->disk_attributes) 488 sysfs_remove_group(&disk_to_dev(old->disk)->kobj, 489 old->disk_attributes); 490 491 /* Stop new requests to arrive */ 492 del_gendisk(old->disk); 493 494 /* Kill current requests */ 495 spin_lock_irqsave(&old->queue_lock, flags); 496 old->rq->queuedata = NULL; 497 spin_unlock_irqrestore(&old->queue_lock, flags); 498 499 /* freeze+quiesce queue to ensure all requests are flushed */ 500 blk_mq_freeze_queue(old->rq); 501 blk_mq_quiesce_queue(old->rq); 502 blk_mq_unquiesce_queue(old->rq); 503 blk_mq_unfreeze_queue(old->rq); 504 505 /* If the device is currently open, tell trans driver to close it, 506 then put mtd device, and don't touch it again */ 507 mutex_lock(&old->lock); 508 if (old->open) { 509 if (old->tr->release) 510 old->tr->release(old); 511 __put_mtd_device(old->mtd); 512 } 513 514 old->mtd = NULL; 515 516 mutex_unlock(&old->lock); 517 blktrans_dev_put(old); 518 return 0; 519 } 520 521 static void blktrans_notify_remove(struct mtd_info *mtd) 522 { 523 struct mtd_blktrans_ops *tr; 524 struct mtd_blktrans_dev *dev, *next; 525 526 list_for_each_entry(tr, &blktrans_majors, list) 527 list_for_each_entry_safe(dev, next, &tr->devs, list) 528 if (dev->mtd == mtd) 529 tr->remove_dev(dev); 530 } 531 532 static void blktrans_notify_add(struct mtd_info *mtd) 533 { 534 struct mtd_blktrans_ops *tr; 535 536 if (mtd->type == MTD_ABSENT) 537 return; 538 539 list_for_each_entry(tr, &blktrans_majors, list) 540 tr->add_mtd(tr, mtd); 541 } 542 543 static struct mtd_notifier blktrans_notifier = { 544 .add = blktrans_notify_add, 545 .remove = blktrans_notify_remove, 546 }; 547 548 int register_mtd_blktrans(struct mtd_blktrans_ops *tr) 549 { 550 struct mtd_info *mtd; 551 int ret; 552 553 /* Register the notifier if/when the first device type is 554 registered, to prevent the link/init ordering from fucking 555 us over. */ 556 if (!blktrans_notifier.list.next) 557 register_mtd_user(&blktrans_notifier); 558 559 560 mutex_lock(&mtd_table_mutex); 561 562 ret = register_blkdev(tr->major, tr->name); 563 if (ret < 0) { 564 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n", 565 tr->name, tr->major, ret); 566 mutex_unlock(&mtd_table_mutex); 567 return ret; 568 } 569 570 if (ret) 571 tr->major = ret; 572 573 tr->blkshift = ffs(tr->blksize) - 1; 574 575 INIT_LIST_HEAD(&tr->devs); 576 list_add(&tr->list, &blktrans_majors); 577 578 mtd_for_each_device(mtd) 579 if (mtd->type != MTD_ABSENT) 580 tr->add_mtd(tr, mtd); 581 582 mutex_unlock(&mtd_table_mutex); 583 return 0; 584 } 585 586 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) 587 { 588 struct mtd_blktrans_dev *dev, *next; 589 590 mutex_lock(&mtd_table_mutex); 591 592 /* Remove it from the list of active majors */ 593 list_del(&tr->list); 594 595 list_for_each_entry_safe(dev, next, &tr->devs, list) 596 tr->remove_dev(dev); 597 598 unregister_blkdev(tr->major, tr->name); 599 mutex_unlock(&mtd_table_mutex); 600 601 BUG_ON(!list_empty(&tr->devs)); 602 return 0; 603 } 604 605 static void __exit mtd_blktrans_exit(void) 606 { 607 /* No race here -- if someone's currently in register_mtd_blktrans 608 we're screwed anyway. */ 609 if (blktrans_notifier.list.next) 610 unregister_mtd_user(&blktrans_notifier); 611 } 612 613 module_exit(mtd_blktrans_exit); 614 615 EXPORT_SYMBOL_GPL(register_mtd_blktrans); 616 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans); 617 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev); 618 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev); 619 620 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); 621 MODULE_LICENSE("GPL"); 622 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'"); 623