xref: /linux/drivers/mtd/mtd_blkdevs.c (revision 55d0969c451159cff86949b38c39171cab962069)
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