xref: /openbmc/linux/drivers/mtd/mtd_blkdevs.c (revision bbaf1ff0)
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 	int last_devnum = -1;
281 	struct gendisk *gd;
282 	int ret;
283 
284 	lockdep_assert_held(&mtd_table_mutex);
285 
286 	list_for_each_entry(d, &tr->devs, list) {
287 		if (new->devnum == -1) {
288 			/* Use first free number */
289 			if (d->devnum != last_devnum+1) {
290 				/* Found a free devnum. Plug it in here */
291 				new->devnum = last_devnum+1;
292 				list_add_tail(&new->list, &d->list);
293 				goto added;
294 			}
295 		} else if (d->devnum == new->devnum) {
296 			/* Required number taken */
297 			return -EBUSY;
298 		} else if (d->devnum > new->devnum) {
299 			/* Required number was free */
300 			list_add_tail(&new->list, &d->list);
301 			goto added;
302 		}
303 		last_devnum = d->devnum;
304 	}
305 
306 	ret = -EBUSY;
307 	if (new->devnum == -1)
308 		new->devnum = last_devnum+1;
309 
310 	/* Check that the device and any partitions will get valid
311 	 * minor numbers and that the disk naming code below can cope
312 	 * with this number. */
313 	if (new->devnum > (MINORMASK >> tr->part_bits) ||
314 	    (tr->part_bits && new->devnum >= 27 * 26))
315 		return ret;
316 
317 	list_add_tail(&new->list, &tr->devs);
318  added:
319 
320 	mutex_init(&new->lock);
321 	kref_init(&new->ref);
322 	if (!tr->writesect)
323 		new->readonly = 1;
324 
325 	ret = -ENOMEM;
326 	new->tag_set = kzalloc(sizeof(*new->tag_set), GFP_KERNEL);
327 	if (!new->tag_set)
328 		goto out_list_del;
329 
330 	ret = blk_mq_alloc_sq_tag_set(new->tag_set, &mtd_mq_ops, 2,
331 			BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING);
332 	if (ret)
333 		goto out_kfree_tag_set;
334 
335 	/* Create gendisk */
336 	gd = blk_mq_alloc_disk(new->tag_set, new);
337 	if (IS_ERR(gd)) {
338 		ret = PTR_ERR(gd);
339 		goto out_free_tag_set;
340 	}
341 
342 	new->disk = gd;
343 	new->rq = new->disk->queue;
344 	gd->private_data = new;
345 	gd->major = tr->major;
346 	gd->first_minor = (new->devnum) << tr->part_bits;
347 	gd->minors = 1 << tr->part_bits;
348 	gd->fops = &mtd_block_ops;
349 
350 	if (tr->part_bits) {
351 		if (new->devnum < 26)
352 			snprintf(gd->disk_name, sizeof(gd->disk_name),
353 				 "%s%c", tr->name, 'a' + new->devnum);
354 		else
355 			snprintf(gd->disk_name, sizeof(gd->disk_name),
356 				 "%s%c%c", tr->name,
357 				 'a' - 1 + new->devnum / 26,
358 				 'a' + new->devnum % 26);
359 	} else {
360 		snprintf(gd->disk_name, sizeof(gd->disk_name),
361 			 "%s%d", tr->name, new->devnum);
362 		gd->flags |= GENHD_FL_NO_PART;
363 	}
364 
365 	set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
366 
367 	/* Create the request queue */
368 	spin_lock_init(&new->queue_lock);
369 	INIT_LIST_HEAD(&new->rq_list);
370 
371 	if (tr->flush)
372 		blk_queue_write_cache(new->rq, true, false);
373 
374 	blk_queue_logical_block_size(new->rq, tr->blksize);
375 
376 	blk_queue_flag_set(QUEUE_FLAG_NONROT, new->rq);
377 	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq);
378 
379 	if (tr->discard) {
380 		blk_queue_max_discard_sectors(new->rq, UINT_MAX);
381 		new->rq->limits.discard_granularity = tr->blksize;
382 	}
383 
384 	gd->queue = new->rq;
385 
386 	if (new->readonly)
387 		set_disk_ro(gd, 1);
388 
389 	ret = device_add_disk(&new->mtd->dev, gd, NULL);
390 	if (ret)
391 		goto out_cleanup_disk;
392 
393 	if (new->disk_attributes) {
394 		ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
395 					new->disk_attributes);
396 		WARN_ON(ret);
397 	}
398 	return 0;
399 
400 out_cleanup_disk:
401 	put_disk(new->disk);
402 out_free_tag_set:
403 	blk_mq_free_tag_set(new->tag_set);
404 out_kfree_tag_set:
405 	kfree(new->tag_set);
406 out_list_del:
407 	list_del(&new->list);
408 	return ret;
409 }
410 
411 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
412 {
413 	unsigned long flags;
414 
415 	lockdep_assert_held(&mtd_table_mutex);
416 
417 	if (old->disk_attributes)
418 		sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
419 						old->disk_attributes);
420 
421 	/* Stop new requests to arrive */
422 	del_gendisk(old->disk);
423 
424 	/* Kill current requests */
425 	spin_lock_irqsave(&old->queue_lock, flags);
426 	old->rq->queuedata = NULL;
427 	spin_unlock_irqrestore(&old->queue_lock, flags);
428 
429 	/* freeze+quiesce queue to ensure all requests are flushed */
430 	blk_mq_freeze_queue(old->rq);
431 	blk_mq_quiesce_queue(old->rq);
432 	blk_mq_unquiesce_queue(old->rq);
433 	blk_mq_unfreeze_queue(old->rq);
434 
435 	/* If the device is currently open, tell trans driver to close it,
436 		then put mtd device, and don't touch it again */
437 	mutex_lock(&old->lock);
438 	if (old->open) {
439 		if (old->tr->release)
440 			old->tr->release(old);
441 		__put_mtd_device(old->mtd);
442 	}
443 
444 	old->mtd = NULL;
445 
446 	mutex_unlock(&old->lock);
447 	blktrans_dev_put(old);
448 	return 0;
449 }
450 
451 static void blktrans_notify_remove(struct mtd_info *mtd)
452 {
453 	struct mtd_blktrans_ops *tr;
454 	struct mtd_blktrans_dev *dev, *next;
455 
456 	list_for_each_entry(tr, &blktrans_majors, list)
457 		list_for_each_entry_safe(dev, next, &tr->devs, list)
458 			if (dev->mtd == mtd)
459 				tr->remove_dev(dev);
460 }
461 
462 static void blktrans_notify_add(struct mtd_info *mtd)
463 {
464 	struct mtd_blktrans_ops *tr;
465 
466 	if (mtd->type == MTD_ABSENT)
467 		return;
468 
469 	list_for_each_entry(tr, &blktrans_majors, list)
470 		tr->add_mtd(tr, mtd);
471 }
472 
473 static struct mtd_notifier blktrans_notifier = {
474 	.add = blktrans_notify_add,
475 	.remove = blktrans_notify_remove,
476 };
477 
478 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
479 {
480 	struct mtd_info *mtd;
481 	int ret;
482 
483 	/* Register the notifier if/when the first device type is
484 	   registered, to prevent the link/init ordering from fucking
485 	   us over. */
486 	if (!blktrans_notifier.list.next)
487 		register_mtd_user(&blktrans_notifier);
488 
489 	ret = register_blkdev(tr->major, tr->name);
490 	if (ret < 0) {
491 		printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
492 		       tr->name, tr->major, ret);
493 		return ret;
494 	}
495 
496 	if (ret)
497 		tr->major = ret;
498 
499 	tr->blkshift = ffs(tr->blksize) - 1;
500 
501 	INIT_LIST_HEAD(&tr->devs);
502 
503 	mutex_lock(&mtd_table_mutex);
504 	list_add(&tr->list, &blktrans_majors);
505 	mtd_for_each_device(mtd)
506 		if (mtd->type != MTD_ABSENT)
507 			tr->add_mtd(tr, mtd);
508 	mutex_unlock(&mtd_table_mutex);
509 	return 0;
510 }
511 
512 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
513 {
514 	struct mtd_blktrans_dev *dev, *next;
515 
516 	mutex_lock(&mtd_table_mutex);
517 
518 	/* Remove it from the list of active majors */
519 	list_del(&tr->list);
520 
521 	list_for_each_entry_safe(dev, next, &tr->devs, list)
522 		tr->remove_dev(dev);
523 
524 	mutex_unlock(&mtd_table_mutex);
525 	unregister_blkdev(tr->major, tr->name);
526 
527 	BUG_ON(!list_empty(&tr->devs));
528 	return 0;
529 }
530 
531 static void __exit mtd_blktrans_exit(void)
532 {
533 	/* No race here -- if someone's currently in register_mtd_blktrans
534 	   we're screwed anyway. */
535 	if (blktrans_notifier.list.next)
536 		unregister_mtd_user(&blktrans_notifier);
537 }
538 
539 module_exit(mtd_blktrans_exit);
540 
541 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
542 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
543 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
544 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
545 
546 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
547 MODULE_LICENSE("GPL");
548 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");
549