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'"); 547