1 /* 2 * Interface to Linux block layer for MTD 'translation layers'. 3 * 4 * Copyright © 2003-2010 David Woodhouse <dwmw2@infradead.org> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 19 * 20 */ 21 22 #include <linux/kernel.h> 23 #include <linux/slab.h> 24 #include <linux/module.h> 25 #include <linux/list.h> 26 #include <linux/fs.h> 27 #include <linux/mtd/blktrans.h> 28 #include <linux/mtd/mtd.h> 29 #include <linux/blkdev.h> 30 #include <linux/blkpg.h> 31 #include <linux/spinlock.h> 32 #include <linux/smp_lock.h> 33 #include <linux/hdreg.h> 34 #include <linux/init.h> 35 #include <linux/mutex.h> 36 #include <linux/kthread.h> 37 #include <asm/uaccess.h> 38 39 #include "mtdcore.h" 40 41 static LIST_HEAD(blktrans_majors); 42 static DEFINE_MUTEX(blktrans_ref_mutex); 43 44 void blktrans_dev_release(struct kref *kref) 45 { 46 struct mtd_blktrans_dev *dev = 47 container_of(kref, struct mtd_blktrans_dev, ref); 48 49 dev->disk->private_data = NULL; 50 blk_cleanup_queue(dev->rq); 51 put_disk(dev->disk); 52 list_del(&dev->list); 53 kfree(dev); 54 } 55 56 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk) 57 { 58 struct mtd_blktrans_dev *dev; 59 60 mutex_lock(&blktrans_ref_mutex); 61 dev = disk->private_data; 62 63 if (!dev) 64 goto unlock; 65 kref_get(&dev->ref); 66 unlock: 67 mutex_unlock(&blktrans_ref_mutex); 68 return dev; 69 } 70 71 void blktrans_dev_put(struct mtd_blktrans_dev *dev) 72 { 73 mutex_lock(&blktrans_ref_mutex); 74 kref_put(&dev->ref, blktrans_dev_release); 75 mutex_unlock(&blktrans_ref_mutex); 76 } 77 78 79 static int do_blktrans_request(struct mtd_blktrans_ops *tr, 80 struct mtd_blktrans_dev *dev, 81 struct request *req) 82 { 83 unsigned long block, nsect; 84 char *buf; 85 86 block = blk_rq_pos(req) << 9 >> tr->blkshift; 87 nsect = blk_rq_cur_bytes(req) >> tr->blkshift; 88 89 buf = req->buffer; 90 91 if (req->cmd_type != REQ_TYPE_FS) 92 return -EIO; 93 94 if (blk_rq_pos(req) + blk_rq_cur_sectors(req) > 95 get_capacity(req->rq_disk)) 96 return -EIO; 97 98 if (req->cmd_flags & REQ_DISCARD) 99 return tr->discard(dev, block, nsect); 100 101 switch(rq_data_dir(req)) { 102 case READ: 103 for (; nsect > 0; nsect--, block++, buf += tr->blksize) 104 if (tr->readsect(dev, block, buf)) 105 return -EIO; 106 rq_flush_dcache_pages(req); 107 return 0; 108 case WRITE: 109 if (!tr->writesect) 110 return -EIO; 111 112 rq_flush_dcache_pages(req); 113 for (; nsect > 0; nsect--, block++, buf += tr->blksize) 114 if (tr->writesect(dev, block, buf)) 115 return -EIO; 116 return 0; 117 default: 118 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req)); 119 return -EIO; 120 } 121 } 122 123 static int mtd_blktrans_thread(void *arg) 124 { 125 struct mtd_blktrans_dev *dev = arg; 126 struct request_queue *rq = dev->rq; 127 struct request *req = NULL; 128 129 spin_lock_irq(rq->queue_lock); 130 131 while (!kthread_should_stop()) { 132 int res; 133 134 if (!req && !(req = blk_fetch_request(rq))) { 135 set_current_state(TASK_INTERRUPTIBLE); 136 spin_unlock_irq(rq->queue_lock); 137 schedule(); 138 spin_lock_irq(rq->queue_lock); 139 continue; 140 } 141 142 spin_unlock_irq(rq->queue_lock); 143 144 mutex_lock(&dev->lock); 145 res = do_blktrans_request(dev->tr, dev, req); 146 mutex_unlock(&dev->lock); 147 148 spin_lock_irq(rq->queue_lock); 149 150 if (!__blk_end_request_cur(req, res)) 151 req = NULL; 152 } 153 154 if (req) 155 __blk_end_request_all(req, -EIO); 156 157 spin_unlock_irq(rq->queue_lock); 158 159 return 0; 160 } 161 162 static void mtd_blktrans_request(struct request_queue *rq) 163 { 164 struct mtd_blktrans_dev *dev; 165 struct request *req = NULL; 166 167 dev = rq->queuedata; 168 169 if (!dev) 170 while ((req = blk_fetch_request(rq)) != NULL) 171 __blk_end_request_all(req, -ENODEV); 172 else 173 wake_up_process(dev->thread); 174 } 175 176 static int blktrans_open(struct block_device *bdev, fmode_t mode) 177 { 178 struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk); 179 int ret; 180 181 if (!dev) 182 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/ 183 184 lock_kernel(); 185 mutex_lock(&dev->lock); 186 187 if (!dev->mtd) { 188 ret = -ENXIO; 189 goto unlock; 190 } 191 192 ret = !dev->open++ && dev->tr->open ? dev->tr->open(dev) : 0; 193 194 /* Take another reference on the device so it won't go away till 195 last release */ 196 if (!ret) 197 kref_get(&dev->ref); 198 unlock: 199 mutex_unlock(&dev->lock); 200 blktrans_dev_put(dev); 201 unlock_kernel(); 202 return ret; 203 } 204 205 static int blktrans_release(struct gendisk *disk, fmode_t mode) 206 { 207 struct mtd_blktrans_dev *dev = blktrans_dev_get(disk); 208 int ret = -ENXIO; 209 210 if (!dev) 211 return ret; 212 213 lock_kernel(); 214 mutex_lock(&dev->lock); 215 216 /* Release one reference, we sure its not the last one here*/ 217 kref_put(&dev->ref, blktrans_dev_release); 218 219 if (!dev->mtd) 220 goto unlock; 221 222 ret = !--dev->open && dev->tr->release ? dev->tr->release(dev) : 0; 223 unlock: 224 mutex_unlock(&dev->lock); 225 blktrans_dev_put(dev); 226 unlock_kernel(); 227 return ret; 228 } 229 230 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo) 231 { 232 struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk); 233 int ret = -ENXIO; 234 235 if (!dev) 236 return ret; 237 238 mutex_lock(&dev->lock); 239 240 if (!dev->mtd) 241 goto unlock; 242 243 ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0; 244 unlock: 245 mutex_unlock(&dev->lock); 246 blktrans_dev_put(dev); 247 return ret; 248 } 249 250 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode, 251 unsigned int cmd, unsigned long arg) 252 { 253 struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk); 254 int ret = -ENXIO; 255 256 if (!dev) 257 return ret; 258 259 lock_kernel(); 260 mutex_lock(&dev->lock); 261 262 if (!dev->mtd) 263 goto unlock; 264 265 switch (cmd) { 266 case BLKFLSBUF: 267 ret = dev->tr->flush ? dev->tr->flush(dev) : 0; 268 break; 269 default: 270 ret = -ENOTTY; 271 } 272 unlock: 273 mutex_unlock(&dev->lock); 274 unlock_kernel(); 275 blktrans_dev_put(dev); 276 return ret; 277 } 278 279 static const struct block_device_operations mtd_blktrans_ops = { 280 .owner = THIS_MODULE, 281 .open = blktrans_open, 282 .release = blktrans_release, 283 .ioctl = blktrans_ioctl, 284 .getgeo = blktrans_getgeo, 285 }; 286 287 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) 288 { 289 struct mtd_blktrans_ops *tr = new->tr; 290 struct mtd_blktrans_dev *d; 291 int last_devnum = -1; 292 struct gendisk *gd; 293 int ret; 294 295 if (mutex_trylock(&mtd_table_mutex)) { 296 mutex_unlock(&mtd_table_mutex); 297 BUG(); 298 } 299 300 mutex_lock(&blktrans_ref_mutex); 301 list_for_each_entry(d, &tr->devs, list) { 302 if (new->devnum == -1) { 303 /* Use first free number */ 304 if (d->devnum != last_devnum+1) { 305 /* Found a free devnum. Plug it in here */ 306 new->devnum = last_devnum+1; 307 list_add_tail(&new->list, &d->list); 308 goto added; 309 } 310 } else if (d->devnum == new->devnum) { 311 /* Required number taken */ 312 mutex_unlock(&blktrans_ref_mutex); 313 return -EBUSY; 314 } else if (d->devnum > new->devnum) { 315 /* Required number was free */ 316 list_add_tail(&new->list, &d->list); 317 goto added; 318 } 319 last_devnum = d->devnum; 320 } 321 322 ret = -EBUSY; 323 if (new->devnum == -1) 324 new->devnum = last_devnum+1; 325 326 /* Check that the device and any partitions will get valid 327 * minor numbers and that the disk naming code below can cope 328 * with this number. */ 329 if (new->devnum > (MINORMASK >> tr->part_bits) || 330 (tr->part_bits && new->devnum >= 27 * 26)) { 331 mutex_unlock(&blktrans_ref_mutex); 332 goto error1; 333 } 334 335 list_add_tail(&new->list, &tr->devs); 336 added: 337 mutex_unlock(&blktrans_ref_mutex); 338 339 mutex_init(&new->lock); 340 kref_init(&new->ref); 341 if (!tr->writesect) 342 new->readonly = 1; 343 344 /* Create gendisk */ 345 ret = -ENOMEM; 346 gd = alloc_disk(1 << tr->part_bits); 347 348 if (!gd) 349 goto error2; 350 351 new->disk = gd; 352 gd->private_data = new; 353 gd->major = tr->major; 354 gd->first_minor = (new->devnum) << tr->part_bits; 355 gd->fops = &mtd_blktrans_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); 369 370 set_capacity(gd, (new->size * tr->blksize) >> 9); 371 372 /* Create the request queue */ 373 spin_lock_init(&new->queue_lock); 374 new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock); 375 376 if (!new->rq) 377 goto error3; 378 379 new->rq->queuedata = new; 380 blk_queue_logical_block_size(new->rq, tr->blksize); 381 382 if (tr->discard) 383 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, 384 new->rq); 385 386 gd->queue = new->rq; 387 388 __get_mtd_device(new->mtd); 389 __module_get(tr->owner); 390 391 /* Create processing thread */ 392 /* TODO: workqueue ? */ 393 new->thread = kthread_run(mtd_blktrans_thread, new, 394 "%s%d", tr->name, new->mtd->index); 395 if (IS_ERR(new->thread)) { 396 ret = PTR_ERR(new->thread); 397 goto error4; 398 } 399 gd->driverfs_dev = &new->mtd->dev; 400 401 if (new->readonly) 402 set_disk_ro(gd, 1); 403 404 add_disk(gd); 405 406 if (new->disk_attributes) { 407 ret = sysfs_create_group(&disk_to_dev(gd)->kobj, 408 new->disk_attributes); 409 WARN_ON(ret); 410 } 411 return 0; 412 error4: 413 module_put(tr->owner); 414 __put_mtd_device(new->mtd); 415 blk_cleanup_queue(new->rq); 416 error3: 417 put_disk(new->disk); 418 error2: 419 list_del(&new->list); 420 error1: 421 kfree(new); 422 return ret; 423 } 424 425 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) 426 { 427 unsigned long flags; 428 429 if (mutex_trylock(&mtd_table_mutex)) { 430 mutex_unlock(&mtd_table_mutex); 431 BUG(); 432 } 433 434 if (old->disk_attributes) 435 sysfs_remove_group(&disk_to_dev(old->disk)->kobj, 436 old->disk_attributes); 437 438 /* Stop new requests to arrive */ 439 del_gendisk(old->disk); 440 441 442 /* Stop the thread */ 443 kthread_stop(old->thread); 444 445 /* Kill current requests */ 446 spin_lock_irqsave(&old->queue_lock, flags); 447 old->rq->queuedata = NULL; 448 blk_start_queue(old->rq); 449 spin_unlock_irqrestore(&old->queue_lock, flags); 450 451 /* Ask trans driver for release to the mtd device */ 452 mutex_lock(&old->lock); 453 if (old->open && old->tr->release) { 454 old->tr->release(old); 455 old->open = 0; 456 } 457 458 __put_mtd_device(old->mtd); 459 module_put(old->tr->owner); 460 461 /* At that point, we don't touch the mtd anymore */ 462 old->mtd = NULL; 463 464 mutex_unlock(&old->lock); 465 blktrans_dev_put(old); 466 return 0; 467 } 468 469 static void blktrans_notify_remove(struct mtd_info *mtd) 470 { 471 struct mtd_blktrans_ops *tr; 472 struct mtd_blktrans_dev *dev, *next; 473 474 list_for_each_entry(tr, &blktrans_majors, list) 475 list_for_each_entry_safe(dev, next, &tr->devs, list) 476 if (dev->mtd == mtd) 477 tr->remove_dev(dev); 478 } 479 480 static void blktrans_notify_add(struct mtd_info *mtd) 481 { 482 struct mtd_blktrans_ops *tr; 483 484 if (mtd->type == MTD_ABSENT) 485 return; 486 487 list_for_each_entry(tr, &blktrans_majors, list) 488 tr->add_mtd(tr, mtd); 489 } 490 491 static struct mtd_notifier blktrans_notifier = { 492 .add = blktrans_notify_add, 493 .remove = blktrans_notify_remove, 494 }; 495 496 int register_mtd_blktrans(struct mtd_blktrans_ops *tr) 497 { 498 struct mtd_info *mtd; 499 int ret; 500 501 /* Register the notifier if/when the first device type is 502 registered, to prevent the link/init ordering from fucking 503 us over. */ 504 if (!blktrans_notifier.list.next) 505 register_mtd_user(&blktrans_notifier); 506 507 508 mutex_lock(&mtd_table_mutex); 509 510 ret = register_blkdev(tr->major, tr->name); 511 if (ret) { 512 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n", 513 tr->name, tr->major, ret); 514 mutex_unlock(&mtd_table_mutex); 515 return ret; 516 } 517 518 tr->blkshift = ffs(tr->blksize) - 1; 519 520 INIT_LIST_HEAD(&tr->devs); 521 list_add(&tr->list, &blktrans_majors); 522 523 mtd_for_each_device(mtd) 524 if (mtd->type != MTD_ABSENT) 525 tr->add_mtd(tr, mtd); 526 527 mutex_unlock(&mtd_table_mutex); 528 return 0; 529 } 530 531 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) 532 { 533 struct mtd_blktrans_dev *dev, *next; 534 535 mutex_lock(&mtd_table_mutex); 536 537 /* Remove it from the list of active majors */ 538 list_del(&tr->list); 539 540 list_for_each_entry_safe(dev, next, &tr->devs, list) 541 tr->remove_dev(dev); 542 543 unregister_blkdev(tr->major, tr->name); 544 mutex_unlock(&mtd_table_mutex); 545 546 BUG_ON(!list_empty(&tr->devs)); 547 return 0; 548 } 549 550 static void __exit mtd_blktrans_exit(void) 551 { 552 /* No race here -- if someone's currently in register_mtd_blktrans 553 we're screwed anyway. */ 554 if (blktrans_notifier.list.next) 555 unregister_mtd_user(&blktrans_notifier); 556 } 557 558 module_exit(mtd_blktrans_exit); 559 560 EXPORT_SYMBOL_GPL(register_mtd_blktrans); 561 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans); 562 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev); 563 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev); 564 565 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); 566 MODULE_LICENSE("GPL"); 567 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'"); 568