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
25static LIST_HEAD(blktrans_majors);
26
27static 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(disk: dev->disk);
33 blk_mq_free_tag_set(set: dev->tag_set);
34 kfree(objp: dev->tag_set);
35 list_del(entry: &dev->list);
36 kfree(objp: dev);
37}
38
39static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
40{
41 kref_put(kref: &dev->ref, release: blktrans_dev_release);
42}
43
44
45static 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(rq: req) << 9 >> tr->blkshift;
55 nsect = blk_rq_cur_bytes(rq: 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(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(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
100int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
101{
102 return dev->bg_stop;
103}
104EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
105
106static 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(entry: &rq->queuelist);
113 blk_mq_start_request(rq);
114 return rq;
115 }
116
117 return NULL;
118}
119
120static 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(lock: &dev->queue_lock);
135 mutex_lock(&dev->lock);
136 tr->background(dev);
137 mutex_unlock(lock: &dev->lock);
138 spin_lock_irq(lock: &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(lock: &dev->queue_lock);
150
151 mutex_lock(&dev->lock);
152 res = do_blktrans_request(tr: dev->tr, dev, req);
153 mutex_unlock(lock: &dev->lock);
154
155 if (!blk_update_request(rq: req, error: res, nr_bytes: blk_rq_cur_bytes(rq: req))) {
156 __blk_mq_end_request(rq: req, error: res);
157 req = NULL;
158 }
159
160 background_done = 0;
161 cond_resched();
162 spin_lock_irq(lock: &dev->queue_lock);
163 }
164}
165
166static 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(rq: bd->rq);
174 return BLK_STS_IOERR;
175 }
176
177 spin_lock_irq(lock: &dev->queue_lock);
178 list_add_tail(new: &bd->rq->queuelist, head: &dev->rq_list);
179 mtd_blktrans_work(dev);
180 spin_unlock_irq(lock: &dev->queue_lock);
181
182 return BLK_STS_OK;
183}
184
185static 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(kref: &dev->ref);
191
192 mutex_lock(&dev->lock);
193
194 if (dev->open)
195 goto unlock;
196
197 __module_get(module: 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(mtd: dev->mtd);
209 if (ret)
210 goto error_release;
211 dev->writable = mode & BLK_OPEN_WRITE;
212
213unlock:
214 dev->open++;
215 mutex_unlock(lock: &dev->lock);
216 return ret;
217
218error_release:
219 if (dev->tr->release)
220 dev->tr->release(dev);
221error_put:
222 module_put(module: dev->tr->owner);
223 mutex_unlock(lock: &dev->lock);
224 blktrans_dev_put(dev);
225 return ret;
226}
227
228static 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(module: dev->tr->owner);
238
239 if (dev->mtd) {
240 if (dev->tr->release)
241 dev->tr->release(dev);
242 __put_mtd_device(mtd: dev->mtd);
243 }
244unlock:
245 mutex_unlock(lock: &dev->lock);
246 blktrans_dev_put(dev);
247}
248
249static 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;
260unlock:
261 mutex_unlock(lock: &dev->lock);
262 return ret;
263}
264
265static 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
272static const struct blk_mq_ops mtd_mq_ops = {
273 .queue_rq = mtd_queue_rq,
274};
275
276int 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: &new->list, head: &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: &new->list, head: &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: &new->list, head: &tr->devs);
318 added:
319
320 mutex_init(&new->lock);
321 kref_init(kref: &new->ref);
322 if (!tr->writesect)
323 new->readonly = 1;
324
325 ret = -ENOMEM;
326 new->tag_set = kzalloc(size: 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(set: new->tag_set, ops: &mtd_mq_ops, queue_depth: 2,
331 set_flags: 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(ptr: gd)) {
338 ret = PTR_ERR(ptr: 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(buf: gd->disk_name, size: sizeof(gd->disk_name),
353 fmt: "%s%c", tr->name, 'a' + new->devnum);
354 else
355 snprintf(buf: gd->disk_name, size: sizeof(gd->disk_name),
356 fmt: "%s%c%c", tr->name,
357 'a' - 1 + new->devnum / 26,
358 'a' + new->devnum % 26);
359 } else {
360 snprintf(buf: gd->disk_name, size: sizeof(gd->disk_name),
361 fmt: "%s%d", tr->name, new->devnum);
362 gd->flags |= GENHD_FL_NO_PART;
363 }
364
365 set_capacity(disk: gd, size: ((u64)new->size * tr->blksize) >> 9);
366
367 /* Create the request queue */
368 spin_lock_init(&new->queue_lock);
369 INIT_LIST_HEAD(list: &new->rq_list);
370
371 if (tr->flush)
372 blk_queue_write_cache(q: new->rq, enabled: true, fua: false);
373
374 blk_queue_logical_block_size(new->rq, tr->blksize);
375
376 blk_queue_flag_set(QUEUE_FLAG_NONROT, q: new->rq);
377 blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, q: new->rq);
378
379 if (tr->discard) {
380 blk_queue_max_discard_sectors(q: 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(disk: gd, read_only: 1);
388
389 ret = device_add_disk(parent: &new->mtd->dev, disk: gd, NULL);
390 if (ret)
391 goto out_cleanup_disk;
392
393 if (new->disk_attributes) {
394 ret = sysfs_create_group(kobj: &disk_to_dev(gd)->kobj,
395 grp: new->disk_attributes);
396 WARN_ON(ret);
397 }
398 return 0;
399
400out_cleanup_disk:
401 put_disk(disk: new->disk);
402out_free_tag_set:
403 blk_mq_free_tag_set(set: new->tag_set);
404out_kfree_tag_set:
405 kfree(objp: new->tag_set);
406out_list_del:
407 list_del(entry: &new->list);
408 return ret;
409}
410
411int 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(kobj: &disk_to_dev(old->disk)->kobj,
419 grp: old->disk_attributes);
420
421 /* Stop new requests to arrive */
422 del_gendisk(gp: old->disk);
423
424 /* Kill current requests */
425 spin_lock_irqsave(&old->queue_lock, flags);
426 old->rq->queuedata = NULL;
427 spin_unlock_irqrestore(lock: &old->queue_lock, flags);
428
429 /* freeze+quiesce queue to ensure all requests are flushed */
430 blk_mq_freeze_queue(q: old->rq);
431 blk_mq_quiesce_queue(q: old->rq);
432 blk_mq_unquiesce_queue(q: old->rq);
433 blk_mq_unfreeze_queue(q: 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(mtd: old->mtd);
442 }
443
444 old->mtd = NULL;
445
446 mutex_unlock(lock: &old->lock);
447 blktrans_dev_put(dev: old);
448 return 0;
449}
450
451static 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
462static 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
473static struct mtd_notifier blktrans_notifier = {
474 .add = blktrans_notify_add,
475 .remove = blktrans_notify_remove,
476};
477
478int 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(new: &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(list: &tr->devs);
502
503 mutex_lock(&mtd_table_mutex);
504 list_add(new: &tr->list, head: &blktrans_majors);
505 mtd_for_each_device(mtd)
506 if (mtd->type != MTD_ABSENT)
507 tr->add_mtd(tr, mtd);
508 mutex_unlock(lock: &mtd_table_mutex);
509 return 0;
510}
511
512int 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(entry: &tr->list);
520
521 list_for_each_entry_safe(dev, next, &tr->devs, list)
522 tr->remove_dev(dev);
523
524 mutex_unlock(lock: &mtd_table_mutex);
525 unregister_blkdev(major: tr->major, name: tr->name);
526
527 BUG_ON(!list_empty(&tr->devs));
528 return 0;
529}
530
531static 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(old: &blktrans_notifier);
537}
538
539module_exit(mtd_blktrans_exit);
540
541EXPORT_SYMBOL_GPL(register_mtd_blktrans);
542EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
543EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
544EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
545
546MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
547MODULE_LICENSE("GPL");
548MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");
549

source code of linux/drivers/mtd/mtd_blkdevs.c