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'"); 542