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