1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Interface to Linux block layer for MTD 'translation layers'.
5 * Copyright © 2003-2010 David Woodhouse <dwmw2@infradead.org>
8 #include <linux/kernel.h>
9 #include <linux/slab.h>
10 #include <linux/module.h>
11 #include <linux/list.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>
25 static LIST_HEAD(blktrans_majors);
27 static void blktrans_dev_release(struct kref *kref)
29 struct mtd_blktrans_dev *dev =
30 container_of(kref, struct mtd_blktrans_dev, ref);
32 blk_cleanup_disk(dev->disk);
33 blk_mq_free_tag_set(dev->tag_set);
39 static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
41 kref_put(&dev->ref, blktrans_dev_release);
45 static blk_status_t do_blktrans_request(struct mtd_blktrans_ops *tr,
46 struct mtd_blktrans_dev *dev,
49 struct req_iterator iter;
51 unsigned long block, nsect;
54 block = blk_rq_pos(req) << 9 >> tr->blkshift;
55 nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
57 switch (req_op(req)) {
63 if (tr->discard(dev, block, nsect))
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));
74 kunmap(bio_page(req->bio));
76 rq_for_each_segment(bvec, req, iter)
77 flush_dcache_page(bvec.bv_page);
83 rq_for_each_segment(bvec, req, iter)
84 flush_dcache_page(bvec.bv_page);
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));
93 kunmap(bio_page(req->bio));
100 int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
104 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
106 static struct request *mtd_next_request(struct mtd_blktrans_dev *dev)
110 rq = list_first_entry_or_null(&dev->rq_list, struct request, queuelist);
112 list_del_init(&rq->queuelist);
113 blk_mq_start_request(rq);
120 static void mtd_blktrans_work(struct mtd_blktrans_dev *dev)
121 __releases(&dev->queue_lock)
122 __acquires(&dev->queue_lock)
124 struct mtd_blktrans_ops *tr = dev->tr;
125 struct request *req = NULL;
126 int background_done = 0;
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);
137 mutex_unlock(&dev->lock);
138 spin_lock_irq(&dev->queue_lock);
140 * Do background processing just once per idle
143 background_done = !dev->bg_stop;
149 spin_unlock_irq(&dev->queue_lock);
151 mutex_lock(&dev->lock);
152 res = do_blktrans_request(dev->tr, dev, req);
153 mutex_unlock(&dev->lock);
155 if (!blk_update_request(req, res, blk_rq_cur_bytes(req))) {
156 __blk_mq_end_request(req, res);
161 spin_lock_irq(&dev->queue_lock);
165 static blk_status_t mtd_queue_rq(struct blk_mq_hw_ctx *hctx,
166 const struct blk_mq_queue_data *bd)
168 struct mtd_blktrans_dev *dev;
170 dev = hctx->queue->queuedata;
172 blk_mq_start_request(bd->rq);
173 return BLK_STS_IOERR;
176 spin_lock_irq(&dev->queue_lock);
177 list_add_tail(&bd->rq->queuelist, &dev->rq_list);
178 mtd_blktrans_work(dev);
179 spin_unlock_irq(&dev->queue_lock);
184 static int blktrans_open(struct block_device *bdev, fmode_t mode)
186 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
191 mutex_lock(&dev->lock);
196 __module_get(dev->tr->owner);
202 ret = dev->tr->open(dev);
207 ret = __get_mtd_device(dev->mtd);
210 dev->file_mode = mode;
214 mutex_unlock(&dev->lock);
218 if (dev->tr->release)
219 dev->tr->release(dev);
221 module_put(dev->tr->owner);
222 mutex_unlock(&dev->lock);
223 blktrans_dev_put(dev);
227 static void blktrans_release(struct gendisk *disk, fmode_t mode)
229 struct mtd_blktrans_dev *dev = disk->private_data;
231 mutex_lock(&dev->lock);
236 module_put(dev->tr->owner);
239 if (dev->tr->release)
240 dev->tr->release(dev);
241 __put_mtd_device(dev->mtd);
244 mutex_unlock(&dev->lock);
245 blktrans_dev_put(dev);
248 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
250 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
253 mutex_lock(&dev->lock);
258 ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY;
260 mutex_unlock(&dev->lock);
264 static const struct block_device_operations mtd_block_ops = {
265 .owner = THIS_MODULE,
266 .open = blktrans_open,
267 .release = blktrans_release,
268 .getgeo = blktrans_getgeo,
271 static const struct blk_mq_ops mtd_mq_ops = {
272 .queue_rq = mtd_queue_rq,
275 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
277 struct mtd_blktrans_ops *tr = new->tr;
278 struct mtd_blktrans_dev *d;
279 int last_devnum = -1;
283 lockdep_assert_held(&mtd_table_mutex);
285 list_for_each_entry(d, &tr->devs, list) {
286 if (new->devnum == -1) {
287 /* Use first free number */
288 if (d->devnum != last_devnum+1) {
289 /* Found a free devnum. Plug it in here */
290 new->devnum = last_devnum+1;
291 list_add_tail(&new->list, &d->list);
294 } else if (d->devnum == new->devnum) {
295 /* Required number taken */
297 } else if (d->devnum > new->devnum) {
298 /* Required number was free */
299 list_add_tail(&new->list, &d->list);
302 last_devnum = d->devnum;
306 if (new->devnum == -1)
307 new->devnum = last_devnum+1;
309 /* Check that the device and any partitions will get valid
310 * minor numbers and that the disk naming code below can cope
311 * with this number. */
312 if (new->devnum > (MINORMASK >> tr->part_bits) ||
313 (tr->part_bits && new->devnum >= 27 * 26))
316 list_add_tail(&new->list, &tr->devs);
319 mutex_init(&new->lock);
320 kref_init(&new->ref);
325 new->tag_set = kzalloc(sizeof(*new->tag_set), GFP_KERNEL);
329 ret = blk_mq_alloc_sq_tag_set(new->tag_set, &mtd_mq_ops, 2,
330 BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING);
332 goto out_kfree_tag_set;
335 gd = blk_mq_alloc_disk(new->tag_set, new);
338 goto out_free_tag_set;
342 new->rq = new->disk->queue;
343 gd->private_data = new;
344 gd->major = tr->major;
345 gd->first_minor = (new->devnum) << tr->part_bits;
346 gd->minors = 1 << tr->part_bits;
347 gd->fops = &mtd_block_ops;
350 if (new->devnum < 26)
351 snprintf(gd->disk_name, sizeof(gd->disk_name),
352 "%s%c", tr->name, 'a' + new->devnum);
354 snprintf(gd->disk_name, sizeof(gd->disk_name),
356 'a' - 1 + new->devnum / 26,
357 'a' + new->devnum % 26);
359 snprintf(gd->disk_name, sizeof(gd->disk_name),
360 "%s%d", tr->name, new->devnum);
361 gd->flags |= GENHD_FL_NO_PART;
364 set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
366 /* Create the request queue */
367 spin_lock_init(&new->queue_lock);
368 INIT_LIST_HEAD(&new->rq_list);
371 blk_queue_write_cache(new->rq, true, false);
373 blk_queue_logical_block_size(new->rq, tr->blksize);
375 blk_queue_flag_set(QUEUE_FLAG_NONROT, new->rq);
376 blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, new->rq);
379 blk_queue_flag_set(QUEUE_FLAG_DISCARD, new->rq);
380 blk_queue_max_discard_sectors(new->rq, UINT_MAX);
381 new->rq->limits.discard_granularity = tr->blksize;
389 ret = device_add_disk(&new->mtd->dev, gd, NULL);
391 goto out_cleanup_disk;
393 if (new->disk_attributes) {
394 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
395 new->disk_attributes);
401 blk_cleanup_disk(new->disk);
403 blk_mq_free_tag_set(new->tag_set);
407 list_del(&new->list);
411 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
415 lockdep_assert_held(&mtd_table_mutex);
417 if (old->disk_attributes)
418 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
419 old->disk_attributes);
421 /* Stop new requests to arrive */
422 del_gendisk(old->disk);
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);
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);
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);
439 if (old->tr->release)
440 old->tr->release(old);
441 __put_mtd_device(old->mtd);
446 mutex_unlock(&old->lock);
447 blktrans_dev_put(old);
451 static void blktrans_notify_remove(struct mtd_info *mtd)
453 struct mtd_blktrans_ops *tr;
454 struct mtd_blktrans_dev *dev, *next;
456 list_for_each_entry(tr, &blktrans_majors, list)
457 list_for_each_entry_safe(dev, next, &tr->devs, list)
462 static void blktrans_notify_add(struct mtd_info *mtd)
464 struct mtd_blktrans_ops *tr;
466 if (mtd->type == MTD_ABSENT)
469 list_for_each_entry(tr, &blktrans_majors, list)
470 tr->add_mtd(tr, mtd);
473 static struct mtd_notifier blktrans_notifier = {
474 .add = blktrans_notify_add,
475 .remove = blktrans_notify_remove,
478 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
480 struct mtd_info *mtd;
483 /* Register the notifier if/when the first device type is
484 registered, to prevent the link/init ordering from fucking
486 if (!blktrans_notifier.list.next)
487 register_mtd_user(&blktrans_notifier);
489 ret = register_blkdev(tr->major, tr->name);
491 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
492 tr->name, tr->major, ret);
499 tr->blkshift = ffs(tr->blksize) - 1;
501 INIT_LIST_HEAD(&tr->devs);
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);
512 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
514 struct mtd_blktrans_dev *dev, *next;
516 mutex_lock(&mtd_table_mutex);
518 /* Remove it from the list of active majors */
521 list_for_each_entry_safe(dev, next, &tr->devs, list)
524 mutex_unlock(&mtd_table_mutex);
525 unregister_blkdev(tr->major, tr->name);
527 BUG_ON(!list_empty(&tr->devs));
531 static void __exit mtd_blktrans_exit(void)
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);
539 module_exit(mtd_blktrans_exit);
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);
546 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
547 MODULE_LICENSE("GPL");
548 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");