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
blktrans_dev_release(struct kref * kref)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
blktrans_dev_put(struct mtd_blktrans_dev * dev)39 static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
40 {
41 kref_put(&dev->ref, blktrans_dev_release);
42 }
43
44
do_blktrans_request(struct mtd_blktrans_ops * tr,struct mtd_blktrans_dev * dev,struct request * req)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
mtd_blktrans_cease_background(struct mtd_blktrans_dev * dev)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
mtd_next_request(struct mtd_blktrans_dev * dev)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
mtd_blktrans_work(struct mtd_blktrans_dev * dev)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
mtd_queue_rq(struct blk_mq_hw_ctx * hctx,const struct blk_mq_queue_data * bd)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
blktrans_open(struct gendisk * disk,blk_mode_t mode)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
blktrans_release(struct gendisk * disk)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
blktrans_getgeo(struct block_device * bdev,struct hd_geometry * geo)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
add_mtd_blktrans_dev(struct mtd_blktrans_dev * new)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
del_mtd_blktrans_dev(struct mtd_blktrans_dev * old)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
blktrans_notify_remove(struct mtd_info * mtd)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
blktrans_notify_add(struct mtd_info * mtd)462 static void blktrans_notify_add(struct mtd_info *mtd)
463 {
464 struct mtd_blktrans_ops *tr;
465
466 if (mtd->type == MTD_ABSENT || mtd->type == MTD_UBIVOLUME)
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
register_mtd_blktrans(struct mtd_blktrans_ops * tr)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 && mtd->type != MTD_UBIVOLUME)
507 tr->add_mtd(tr, mtd);
508 mutex_unlock(&mtd_table_mutex);
509 return 0;
510 }
511
deregister_mtd_blktrans(struct mtd_blktrans_ops * tr)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
mtd_blktrans_exit(void)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