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 const struct block_device_operations mtd_block_ops = { 302 .owner = THIS_MODULE, 303 .open = blktrans_open, 304 .release = blktrans_release, 305 .getgeo = blktrans_getgeo, 306 }; 307 308 static const struct blk_mq_ops mtd_mq_ops = { 309 .queue_rq = mtd_queue_rq, 310 }; 311 312 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) 313 { 314 struct mtd_blktrans_ops *tr = new->tr; 315 struct mtd_blktrans_dev *d; 316 int last_devnum = -1; 317 struct gendisk *gd; 318 int ret; 319 320 if (mutex_trylock(&mtd_table_mutex)) { 321 mutex_unlock(&mtd_table_mutex); 322 BUG(); 323 } 324 325 mutex_lock(&blktrans_ref_mutex); 326 list_for_each_entry(d, &tr->devs, list) { 327 if (new->devnum == -1) { 328 /* Use first free number */ 329 if (d->devnum != last_devnum+1) { 330 /* Found a free devnum. Plug it in here */ 331 new->devnum = last_devnum+1; 332 list_add_tail(&new->list, &d->list); 333 goto added; 334 } 335 } else if (d->devnum == new->devnum) { 336 /* Required number taken */ 337 mutex_unlock(&blktrans_ref_mutex); 338 return -EBUSY; 339 } else if (d->devnum > new->devnum) { 340 /* Required number was free */ 341 list_add_tail(&new->list, &d->list); 342 goto added; 343 } 344 last_devnum = d->devnum; 345 } 346 347 ret = -EBUSY; 348 if (new->devnum == -1) 349 new->devnum = last_devnum+1; 350 351 /* Check that the device and any partitions will get valid 352 * minor numbers and that the disk naming code below can cope 353 * with this number. */ 354 if (new->devnum > (MINORMASK >> tr->part_bits) || 355 (tr->part_bits && new->devnum >= 27 * 26)) { 356 mutex_unlock(&blktrans_ref_mutex); 357 goto error1; 358 } 359 360 list_add_tail(&new->list, &tr->devs); 361 added: 362 mutex_unlock(&blktrans_ref_mutex); 363 364 mutex_init(&new->lock); 365 kref_init(&new->ref); 366 if (!tr->writesect) 367 new->readonly = 1; 368 369 /* Create gendisk */ 370 ret = -ENOMEM; 371 gd = alloc_disk(1 << tr->part_bits); 372 373 if (!gd) 374 goto error2; 375 376 new->disk = gd; 377 gd->private_data = new; 378 gd->major = tr->major; 379 gd->first_minor = (new->devnum) << tr->part_bits; 380 gd->fops = &mtd_block_ops; 381 382 if (tr->part_bits) 383 if (new->devnum < 26) 384 snprintf(gd->disk_name, sizeof(gd->disk_name), 385 "%s%c", tr->name, 'a' + new->devnum); 386 else 387 snprintf(gd->disk_name, sizeof(gd->disk_name), 388 "%s%c%c", tr->name, 389 'a' - 1 + new->devnum / 26, 390 'a' + new->devnum % 26); 391 else 392 snprintf(gd->disk_name, sizeof(gd->disk_name), 393 "%s%d", tr->name, new->devnum); 394 395 set_capacity(gd, ((u64)new->size * tr->blksize) >> 9); 396 397 /* Create the request queue */ 398 spin_lock_init(&new->queue_lock); 399 INIT_LIST_HEAD(&new->rq_list); 400 401 new->tag_set = kzalloc(sizeof(*new->tag_set), GFP_KERNEL); 402 if (!new->tag_set) 403 goto error3; 404 405 new->rq = blk_mq_init_sq_queue(new->tag_set, &mtd_mq_ops, 2, 406 BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING); 407 if (IS_ERR(new->rq)) { 408 ret = PTR_ERR(new->rq); 409 new->rq = NULL; 410 goto error4; 411 } 412 413 if (tr->flush) 414 blk_queue_write_cache(new->rq, true, false); 415 416 new->rq->queuedata = new; 417 blk_queue_logical_block_size(new->rq, tr->blksize); 418 419 blk_queue_flag_set(QUEUE_FLAG_NONROT, new->rq); 420 blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq); 421 422 if (tr->discard) { 423 blk_queue_flag_set(QUEUE_FLAG_DISCARD, new->rq); 424 blk_queue_max_discard_sectors(new->rq, UINT_MAX); 425 } 426 427 gd->queue = new->rq; 428 429 if (new->readonly) 430 set_disk_ro(gd, 1); 431 432 device_add_disk(&new->mtd->dev, gd, NULL); 433 434 if (new->disk_attributes) { 435 ret = sysfs_create_group(&disk_to_dev(gd)->kobj, 436 new->disk_attributes); 437 WARN_ON(ret); 438 } 439 return 0; 440 error4: 441 kfree(new->tag_set); 442 error3: 443 put_disk(new->disk); 444 error2: 445 list_del(&new->list); 446 error1: 447 return ret; 448 } 449 450 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) 451 { 452 unsigned long flags; 453 454 if (mutex_trylock(&mtd_table_mutex)) { 455 mutex_unlock(&mtd_table_mutex); 456 BUG(); 457 } 458 459 if (old->disk_attributes) 460 sysfs_remove_group(&disk_to_dev(old->disk)->kobj, 461 old->disk_attributes); 462 463 /* Stop new requests to arrive */ 464 del_gendisk(old->disk); 465 466 /* Kill current requests */ 467 spin_lock_irqsave(&old->queue_lock, flags); 468 old->rq->queuedata = NULL; 469 spin_unlock_irqrestore(&old->queue_lock, flags); 470 471 /* freeze+quiesce queue to ensure all requests are flushed */ 472 blk_mq_freeze_queue(old->rq); 473 blk_mq_quiesce_queue(old->rq); 474 blk_mq_unquiesce_queue(old->rq); 475 blk_mq_unfreeze_queue(old->rq); 476 477 /* If the device is currently open, tell trans driver to close it, 478 then put mtd device, and don't touch it again */ 479 mutex_lock(&old->lock); 480 if (old->open) { 481 if (old->tr->release) 482 old->tr->release(old); 483 __put_mtd_device(old->mtd); 484 } 485 486 old->mtd = NULL; 487 488 mutex_unlock(&old->lock); 489 blktrans_dev_put(old); 490 return 0; 491 } 492 493 static void blktrans_notify_remove(struct mtd_info *mtd) 494 { 495 struct mtd_blktrans_ops *tr; 496 struct mtd_blktrans_dev *dev, *next; 497 498 list_for_each_entry(tr, &blktrans_majors, list) 499 list_for_each_entry_safe(dev, next, &tr->devs, list) 500 if (dev->mtd == mtd) 501 tr->remove_dev(dev); 502 } 503 504 static void blktrans_notify_add(struct mtd_info *mtd) 505 { 506 struct mtd_blktrans_ops *tr; 507 508 if (mtd->type == MTD_ABSENT) 509 return; 510 511 list_for_each_entry(tr, &blktrans_majors, list) 512 tr->add_mtd(tr, mtd); 513 } 514 515 static struct mtd_notifier blktrans_notifier = { 516 .add = blktrans_notify_add, 517 .remove = blktrans_notify_remove, 518 }; 519 520 int register_mtd_blktrans(struct mtd_blktrans_ops *tr) 521 { 522 struct mtd_info *mtd; 523 int ret; 524 525 /* Register the notifier if/when the first device type is 526 registered, to prevent the link/init ordering from fucking 527 us over. */ 528 if (!blktrans_notifier.list.next) 529 register_mtd_user(&blktrans_notifier); 530 531 532 mutex_lock(&mtd_table_mutex); 533 534 ret = register_blkdev(tr->major, tr->name); 535 if (ret < 0) { 536 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n", 537 tr->name, tr->major, ret); 538 mutex_unlock(&mtd_table_mutex); 539 return ret; 540 } 541 542 if (ret) 543 tr->major = ret; 544 545 tr->blkshift = ffs(tr->blksize) - 1; 546 547 INIT_LIST_HEAD(&tr->devs); 548 list_add(&tr->list, &blktrans_majors); 549 550 mtd_for_each_device(mtd) 551 if (mtd->type != MTD_ABSENT) 552 tr->add_mtd(tr, mtd); 553 554 mutex_unlock(&mtd_table_mutex); 555 return 0; 556 } 557 558 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) 559 { 560 struct mtd_blktrans_dev *dev, *next; 561 562 mutex_lock(&mtd_table_mutex); 563 564 /* Remove it from the list of active majors */ 565 list_del(&tr->list); 566 567 list_for_each_entry_safe(dev, next, &tr->devs, list) 568 tr->remove_dev(dev); 569 570 unregister_blkdev(tr->major, tr->name); 571 mutex_unlock(&mtd_table_mutex); 572 573 BUG_ON(!list_empty(&tr->devs)); 574 return 0; 575 } 576 577 static void __exit mtd_blktrans_exit(void) 578 { 579 /* No race here -- if someone's currently in register_mtd_blktrans 580 we're screwed anyway. */ 581 if (blktrans_notifier.list.next) 582 unregister_mtd_user(&blktrans_notifier); 583 } 584 585 module_exit(mtd_blktrans_exit); 586 587 EXPORT_SYMBOL_GPL(register_mtd_blktrans); 588 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans); 589 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev); 590 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev); 591 592 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); 593 MODULE_LICENSE("GPL"); 594 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'"); 595