mtd_blkdevs.c 14 KB

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  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. #include <linux/kernel.h>
  8. #include <linux/slab.h>
  9. #include <linux/module.h>
  10. #include <linux/list.h>
  11. #include <linux/fs.h>
  12. #include <linux/mtd/blktrans.h>
  13. #include <linux/mtd/mtd.h>
  14. #include <linux/blkdev.h>
  15. #include <linux/blk-mq.h>
  16. #include <linux/blkpg.h>
  17. #include <linux/spinlock.h>
  18. #include <linux/hdreg.h>
  19. #include <linux/mutex.h>
  20. #include <linux/uaccess.h>
  21. #include "mtdcore.h"
  22. static LIST_HEAD(blktrans_majors);
  23. static DEFINE_MUTEX(blktrans_ref_mutex);
  24. static void blktrans_dev_release(struct kref *kref)
  25. {
  26. struct mtd_blktrans_dev *dev =
  27. container_of(kref, struct mtd_blktrans_dev, ref);
  28. dev->disk->private_data = NULL;
  29. blk_cleanup_queue(dev->rq);
  30. blk_mq_free_tag_set(dev->tag_set);
  31. kfree(dev->tag_set);
  32. put_disk(dev->disk);
  33. list_del(&dev->list);
  34. kfree(dev);
  35. }
  36. static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
  37. {
  38. struct mtd_blktrans_dev *dev;
  39. mutex_lock(&blktrans_ref_mutex);
  40. dev = disk->private_data;
  41. if (!dev)
  42. goto unlock;
  43. kref_get(&dev->ref);
  44. unlock:
  45. mutex_unlock(&blktrans_ref_mutex);
  46. return dev;
  47. }
  48. static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
  49. {
  50. mutex_lock(&blktrans_ref_mutex);
  51. kref_put(&dev->ref, blktrans_dev_release);
  52. mutex_unlock(&blktrans_ref_mutex);
  53. }
  54. static blk_status_t do_blktrans_request(struct mtd_blktrans_ops *tr,
  55. struct mtd_blktrans_dev *dev,
  56. struct request *req)
  57. {
  58. unsigned long block, nsect;
  59. char *buf;
  60. block = blk_rq_pos(req) << 9 >> tr->blkshift;
  61. nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  62. if (req_op(req) == REQ_OP_FLUSH) {
  63. if (tr->flush(dev))
  64. return BLK_STS_IOERR;
  65. return BLK_STS_OK;
  66. }
  67. if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  68. get_capacity(req->rq_disk))
  69. return BLK_STS_IOERR;
  70. switch (req_op(req)) {
  71. case REQ_OP_DISCARD:
  72. if (tr->discard(dev, block, nsect))
  73. return BLK_STS_IOERR;
  74. return BLK_STS_OK;
  75. case REQ_OP_READ:
  76. buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
  77. for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
  78. if (tr->readsect(dev, block, buf)) {
  79. kunmap(bio_page(req->bio));
  80. return BLK_STS_IOERR;
  81. }
  82. }
  83. kunmap(bio_page(req->bio));
  84. rq_flush_dcache_pages(req);
  85. return BLK_STS_OK;
  86. case REQ_OP_WRITE:
  87. if (!tr->writesect)
  88. return BLK_STS_IOERR;
  89. rq_flush_dcache_pages(req);
  90. buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
  91. for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
  92. if (tr->writesect(dev, block, buf)) {
  93. kunmap(bio_page(req->bio));
  94. return BLK_STS_IOERR;
  95. }
  96. }
  97. kunmap(bio_page(req->bio));
  98. return BLK_STS_OK;
  99. default:
  100. return BLK_STS_IOERR;
  101. }
  102. }
  103. int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
  104. {
  105. return dev->bg_stop;
  106. }
  107. EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
  108. static struct request *mtd_next_request(struct mtd_blktrans_dev *dev)
  109. {
  110. struct request *rq;
  111. rq = list_first_entry_or_null(&dev->rq_list, struct request, queuelist);
  112. if (rq) {
  113. list_del_init(&rq->queuelist);
  114. blk_mq_start_request(rq);
  115. return rq;
  116. }
  117. return NULL;
  118. }
  119. static void mtd_blktrans_work(struct mtd_blktrans_dev *dev)
  120. __releases(&dev->queue_lock)
  121. __acquires(&dev->queue_lock)
  122. {
  123. struct mtd_blktrans_ops *tr = dev->tr;
  124. struct request *req = NULL;
  125. int background_done = 0;
  126. while (1) {
  127. blk_status_t res;
  128. dev->bg_stop = false;
  129. if (!req && !(req = mtd_next_request(dev))) {
  130. if (tr->background && !background_done) {
  131. spin_unlock_irq(&dev->queue_lock);
  132. mutex_lock(&dev->lock);
  133. tr->background(dev);
  134. mutex_unlock(&dev->lock);
  135. spin_lock_irq(&dev->queue_lock);
  136. /*
  137. * Do background processing just once per idle
  138. * period.
  139. */
  140. background_done = !dev->bg_stop;
  141. continue;
  142. }
  143. break;
  144. }
  145. spin_unlock_irq(&dev->queue_lock);
  146. mutex_lock(&dev->lock);
  147. res = do_blktrans_request(dev->tr, dev, req);
  148. mutex_unlock(&dev->lock);
  149. if (!blk_update_request(req, res, blk_rq_cur_bytes(req))) {
  150. __blk_mq_end_request(req, res);
  151. req = NULL;
  152. }
  153. background_done = 0;
  154. spin_lock_irq(&dev->queue_lock);
  155. }
  156. }
  157. static blk_status_t mtd_queue_rq(struct blk_mq_hw_ctx *hctx,
  158. const struct blk_mq_queue_data *bd)
  159. {
  160. struct mtd_blktrans_dev *dev;
  161. dev = hctx->queue->queuedata;
  162. if (!dev) {
  163. blk_mq_start_request(bd->rq);
  164. return BLK_STS_IOERR;
  165. }
  166. spin_lock_irq(&dev->queue_lock);
  167. list_add_tail(&bd->rq->queuelist, &dev->rq_list);
  168. mtd_blktrans_work(dev);
  169. spin_unlock_irq(&dev->queue_lock);
  170. return BLK_STS_OK;
  171. }
  172. static int blktrans_open(struct block_device *bdev, fmode_t mode)
  173. {
  174. struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
  175. int ret = 0;
  176. if (!dev)
  177. return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
  178. mutex_lock(&mtd_table_mutex);
  179. mutex_lock(&dev->lock);
  180. if (dev->open)
  181. goto unlock;
  182. kref_get(&dev->ref);
  183. __module_get(dev->tr->owner);
  184. if (!dev->mtd)
  185. goto unlock;
  186. if (dev->tr->open) {
  187. ret = dev->tr->open(dev);
  188. if (ret)
  189. goto error_put;
  190. }
  191. ret = __get_mtd_device(dev->mtd);
  192. if (ret)
  193. goto error_release;
  194. dev->file_mode = mode;
  195. unlock:
  196. dev->open++;
  197. mutex_unlock(&dev->lock);
  198. mutex_unlock(&mtd_table_mutex);
  199. blktrans_dev_put(dev);
  200. return ret;
  201. error_release:
  202. if (dev->tr->release)
  203. dev->tr->release(dev);
  204. error_put:
  205. module_put(dev->tr->owner);
  206. kref_put(&dev->ref, blktrans_dev_release);
  207. mutex_unlock(&dev->lock);
  208. mutex_unlock(&mtd_table_mutex);
  209. blktrans_dev_put(dev);
  210. return ret;
  211. }
  212. static void blktrans_release(struct gendisk *disk, fmode_t mode)
  213. {
  214. struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
  215. if (!dev)
  216. return;
  217. mutex_lock(&mtd_table_mutex);
  218. mutex_lock(&dev->lock);
  219. if (--dev->open)
  220. goto unlock;
  221. kref_put(&dev->ref, blktrans_dev_release);
  222. module_put(dev->tr->owner);
  223. if (dev->mtd) {
  224. if (dev->tr->release)
  225. dev->tr->release(dev);
  226. __put_mtd_device(dev->mtd);
  227. }
  228. unlock:
  229. mutex_unlock(&dev->lock);
  230. mutex_unlock(&mtd_table_mutex);
  231. blktrans_dev_put(dev);
  232. }
  233. static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
  234. {
  235. struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
  236. int ret = -ENXIO;
  237. if (!dev)
  238. return ret;
  239. mutex_lock(&dev->lock);
  240. if (!dev->mtd)
  241. goto unlock;
  242. ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY;
  243. unlock:
  244. mutex_unlock(&dev->lock);
  245. blktrans_dev_put(dev);
  246. return ret;
  247. }
  248. static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
  249. unsigned int cmd, unsigned long arg)
  250. {
  251. struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
  252. int ret = -ENXIO;
  253. if (!dev)
  254. return ret;
  255. mutex_lock(&dev->lock);
  256. if (!dev->mtd)
  257. goto unlock;
  258. switch (cmd) {
  259. case BLKFLSBUF:
  260. ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
  261. break;
  262. default:
  263. ret = -ENOTTY;
  264. }
  265. unlock:
  266. mutex_unlock(&dev->lock);
  267. blktrans_dev_put(dev);
  268. return ret;
  269. }
  270. static const struct block_device_operations mtd_block_ops = {
  271. .owner = THIS_MODULE,
  272. .open = blktrans_open,
  273. .release = blktrans_release,
  274. .ioctl = blktrans_ioctl,
  275. .getgeo = blktrans_getgeo,
  276. };
  277. static const struct blk_mq_ops mtd_mq_ops = {
  278. .queue_rq = mtd_queue_rq,
  279. };
  280. int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
  281. {
  282. struct mtd_blktrans_ops *tr = new->tr;
  283. struct mtd_blktrans_dev *d;
  284. int last_devnum = -1;
  285. struct gendisk *gd;
  286. int ret;
  287. if (mutex_trylock(&mtd_table_mutex)) {
  288. mutex_unlock(&mtd_table_mutex);
  289. BUG();
  290. }
  291. mutex_lock(&blktrans_ref_mutex);
  292. list_for_each_entry(d, &tr->devs, list) {
  293. if (new->devnum == -1) {
  294. /* Use first free number */
  295. if (d->devnum != last_devnum+1) {
  296. /* Found a free devnum. Plug it in here */
  297. new->devnum = last_devnum+1;
  298. list_add_tail(&new->list, &d->list);
  299. goto added;
  300. }
  301. } else if (d->devnum == new->devnum) {
  302. /* Required number taken */
  303. mutex_unlock(&blktrans_ref_mutex);
  304. return -EBUSY;
  305. } else if (d->devnum > new->devnum) {
  306. /* Required number was free */
  307. list_add_tail(&new->list, &d->list);
  308. goto added;
  309. }
  310. last_devnum = d->devnum;
  311. }
  312. ret = -EBUSY;
  313. if (new->devnum == -1)
  314. new->devnum = last_devnum+1;
  315. /* Check that the device and any partitions will get valid
  316. * minor numbers and that the disk naming code below can cope
  317. * with this number. */
  318. if (new->devnum > (MINORMASK >> tr->part_bits) ||
  319. (tr->part_bits && new->devnum >= 27 * 26)) {
  320. mutex_unlock(&blktrans_ref_mutex);
  321. goto error1;
  322. }
  323. list_add_tail(&new->list, &tr->devs);
  324. added:
  325. mutex_unlock(&blktrans_ref_mutex);
  326. mutex_init(&new->lock);
  327. kref_init(&new->ref);
  328. if (!tr->writesect)
  329. new->readonly = 1;
  330. /* Create gendisk */
  331. ret = -ENOMEM;
  332. gd = alloc_disk(1 << tr->part_bits);
  333. if (!gd)
  334. goto error2;
  335. new->disk = gd;
  336. gd->private_data = new;
  337. gd->major = tr->major;
  338. gd->first_minor = (new->devnum) << tr->part_bits;
  339. gd->fops = &mtd_block_ops;
  340. if (tr->part_bits)
  341. if (new->devnum < 26)
  342. snprintf(gd->disk_name, sizeof(gd->disk_name),
  343. "%s%c", tr->name, 'a' + new->devnum);
  344. else
  345. snprintf(gd->disk_name, sizeof(gd->disk_name),
  346. "%s%c%c", tr->name,
  347. 'a' - 1 + new->devnum / 26,
  348. 'a' + new->devnum % 26);
  349. else
  350. snprintf(gd->disk_name, sizeof(gd->disk_name),
  351. "%s%d", tr->name, new->devnum);
  352. set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
  353. /* Create the request queue */
  354. spin_lock_init(&new->queue_lock);
  355. INIT_LIST_HEAD(&new->rq_list);
  356. new->tag_set = kzalloc(sizeof(*new->tag_set), GFP_KERNEL);
  357. if (!new->tag_set)
  358. goto error3;
  359. new->rq = blk_mq_init_sq_queue(new->tag_set, &mtd_mq_ops, 2,
  360. BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING);
  361. if (IS_ERR(new->rq)) {
  362. ret = PTR_ERR(new->rq);
  363. new->rq = NULL;
  364. goto error4;
  365. }
  366. if (tr->flush)
  367. blk_queue_write_cache(new->rq, true, false);
  368. new->rq->queuedata = new;
  369. blk_queue_logical_block_size(new->rq, tr->blksize);
  370. blk_queue_flag_set(QUEUE_FLAG_NONROT, new->rq);
  371. blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq);
  372. if (tr->discard) {
  373. blk_queue_flag_set(QUEUE_FLAG_DISCARD, new->rq);
  374. blk_queue_max_discard_sectors(new->rq, UINT_MAX);
  375. }
  376. gd->queue = new->rq;
  377. if (new->readonly)
  378. set_disk_ro(gd, 1);
  379. device_add_disk(&new->mtd->dev, gd, NULL);
  380. if (new->disk_attributes) {
  381. ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
  382. new->disk_attributes);
  383. WARN_ON(ret);
  384. }
  385. return 0;
  386. error4:
  387. kfree(new->tag_set);
  388. error3:
  389. put_disk(new->disk);
  390. error2:
  391. list_del(&new->list);
  392. error1:
  393. return ret;
  394. }
  395. int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
  396. {
  397. unsigned long flags;
  398. if (mutex_trylock(&mtd_table_mutex)) {
  399. mutex_unlock(&mtd_table_mutex);
  400. BUG();
  401. }
  402. if (old->disk_attributes)
  403. sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
  404. old->disk_attributes);
  405. /* Stop new requests to arrive */
  406. del_gendisk(old->disk);
  407. /* Kill current requests */
  408. spin_lock_irqsave(&old->queue_lock, flags);
  409. old->rq->queuedata = NULL;
  410. spin_unlock_irqrestore(&old->queue_lock, flags);
  411. /* freeze+quiesce queue to ensure all requests are flushed */
  412. blk_mq_freeze_queue(old->rq);
  413. blk_mq_quiesce_queue(old->rq);
  414. blk_mq_unquiesce_queue(old->rq);
  415. blk_mq_unfreeze_queue(old->rq);
  416. /* If the device is currently open, tell trans driver to close it,
  417. then put mtd device, and don't touch it again */
  418. mutex_lock(&old->lock);
  419. if (old->open) {
  420. if (old->tr->release)
  421. old->tr->release(old);
  422. __put_mtd_device(old->mtd);
  423. }
  424. old->mtd = NULL;
  425. mutex_unlock(&old->lock);
  426. blktrans_dev_put(old);
  427. return 0;
  428. }
  429. static void blktrans_notify_remove(struct mtd_info *mtd)
  430. {
  431. struct mtd_blktrans_ops *tr;
  432. struct mtd_blktrans_dev *dev, *next;
  433. list_for_each_entry(tr, &blktrans_majors, list)
  434. list_for_each_entry_safe(dev, next, &tr->devs, list)
  435. if (dev->mtd == mtd)
  436. tr->remove_dev(dev);
  437. }
  438. static void blktrans_notify_add(struct mtd_info *mtd)
  439. {
  440. struct mtd_blktrans_ops *tr;
  441. if (mtd->type == MTD_ABSENT)
  442. return;
  443. list_for_each_entry(tr, &blktrans_majors, list)
  444. tr->add_mtd(tr, mtd);
  445. }
  446. static struct mtd_notifier blktrans_notifier = {
  447. .add = blktrans_notify_add,
  448. .remove = blktrans_notify_remove,
  449. };
  450. int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
  451. {
  452. struct mtd_info *mtd;
  453. int ret;
  454. /* Register the notifier if/when the first device type is
  455. registered, to prevent the link/init ordering from fucking
  456. us over. */
  457. if (!blktrans_notifier.list.next)
  458. register_mtd_user(&blktrans_notifier);
  459. mutex_lock(&mtd_table_mutex);
  460. ret = register_blkdev(tr->major, tr->name);
  461. if (ret < 0) {
  462. printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
  463. tr->name, tr->major, ret);
  464. mutex_unlock(&mtd_table_mutex);
  465. return ret;
  466. }
  467. if (ret)
  468. tr->major = ret;
  469. tr->blkshift = ffs(tr->blksize) - 1;
  470. INIT_LIST_HEAD(&tr->devs);
  471. list_add(&tr->list, &blktrans_majors);
  472. mtd_for_each_device(mtd)
  473. if (mtd->type != MTD_ABSENT)
  474. tr->add_mtd(tr, mtd);
  475. mutex_unlock(&mtd_table_mutex);
  476. return 0;
  477. }
  478. int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
  479. {
  480. struct mtd_blktrans_dev *dev, *next;
  481. mutex_lock(&mtd_table_mutex);
  482. /* Remove it from the list of active majors */
  483. list_del(&tr->list);
  484. list_for_each_entry_safe(dev, next, &tr->devs, list)
  485. tr->remove_dev(dev);
  486. unregister_blkdev(tr->major, tr->name);
  487. mutex_unlock(&mtd_table_mutex);
  488. BUG_ON(!list_empty(&tr->devs));
  489. return 0;
  490. }
  491. static void __exit mtd_blktrans_exit(void)
  492. {
  493. /* No race here -- if someone's currently in register_mtd_blktrans
  494. we're screwed anyway. */
  495. if (blktrans_notifier.list.next)
  496. unregister_mtd_user(&blktrans_notifier);
  497. }
  498. module_exit(mtd_blktrans_exit);
  499. EXPORT_SYMBOL_GPL(register_mtd_blktrans);
  500. EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
  501. EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
  502. EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
  503. MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
  504. MODULE_LICENSE("GPL");
  505. MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");