// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Interface to Linux block layer for MTD 'translation layers'.
*
* Copyright © 2003-2010 David Woodhouse <[email protected]>
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/fs.h>
#include <linux/mtd/blktrans.h>
#include <linux/mtd/mtd.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/blkpg.h>
#include <linux/spinlock.h>
#include <linux/hdreg.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>
#include "mtdcore.h"
static LIST_HEAD(blktrans_majors);
static void blktrans_dev_release(struct kref *kref)
{
struct mtd_blktrans_dev *dev =
container_of(kref, struct mtd_blktrans_dev, ref);
put_disk(dev->disk);
blk_mq_free_tag_set(dev->tag_set);
kfree(dev->tag_set);
list_del(&dev->list);
kfree(dev);
}
static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
{
kref_put(&dev->ref, blktrans_dev_release);
}
static blk_status_t do_blktrans_request(struct mtd_blktrans_ops *tr,
struct mtd_blktrans_dev *dev,
struct request *req)
{
struct req_iterator iter;
struct bio_vec bvec;
unsigned long block, nsect;
char *buf;
block = blk_rq_pos(req) << 9 >> tr->blkshift;
nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
switch (req_op(req)) {
case REQ_OP_FLUSH:
if (tr->flush(dev))
return BLK_STS_IOERR;
return BLK_STS_OK;
case REQ_OP_DISCARD:
if (tr->discard(dev, block, nsect))
return BLK_STS_IOERR;
return BLK_STS_OK;
case REQ_OP_READ:
buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
if (tr->readsect(dev, block, buf)) {
kunmap(bio_page(req->bio));
return BLK_STS_IOERR;
}
}
kunmap(bio_page(req->bio));
rq_for_each_segment(bvec, req, iter)
flush_dcache_page(bvec.bv_page);
return BLK_STS_OK;
case REQ_OP_WRITE:
if (!tr->writesect)
return BLK_STS_IOERR;
rq_for_each_segment(bvec, req, iter)
flush_dcache_page(bvec.bv_page);
buf = kmap(bio_page(req->bio)) + bio_offset(req->bio);
for (; nsect > 0; nsect--, block++, buf += tr->blksize) {
if (tr->writesect(dev, block, buf)) {
kunmap(bio_page(req->bio));
return BLK_STS_IOERR;
}
}
kunmap(bio_page(req->bio));
return BLK_STS_OK;
default:
return BLK_STS_IOERR;
}
}
int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
{
return dev->bg_stop;
}
EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
static struct request *mtd_next_request(struct mtd_blktrans_dev *dev)
{
struct request *rq;
rq = list_first_entry_or_null(&dev->rq_list, struct request, queuelist);
if (rq) {
list_del_init(&rq->queuelist);
blk_mq_start_request(rq);
return rq;
}
return NULL;
}
static void mtd_blktrans_work(struct mtd_blktrans_dev *dev)
__releases(&dev->queue_lock)
__acquires(&dev->queue_lock)
{
struct mtd_blktrans_ops *tr = dev->tr;
struct request *req = NULL;
int background_done = 0;
while (1) {
blk_status_t res;
dev->bg_stop = false;
if (!req && !(req = mtd_next_request(dev))) {
if (tr->background && !background_done) {
spin_unlock_irq(&dev->queue_lock);
mutex_lock(&dev->lock);
tr->background(dev);
mutex_unlock(&dev->lock);
spin_lock_irq(&dev->queue_lock);
/*
* Do background processing just once per idle
* period.
*/
background_done = !dev->bg_stop;
continue;
}
break;
}
spin_unlock_irq(&dev->queue_lock);
mutex_lock(&dev->lock);
res = do_blktrans_request(dev->tr, dev, req);
mutex_unlock(&dev->lock);
if (!blk_update_request(req, res, blk_rq_cur_bytes(req))) {
__blk_mq_end_request(req, res);
req = NULL;
}
background_done = 0;
cond_resched();
spin_lock_irq(&dev->queue_lock);
}
}
static blk_status_t mtd_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
{
struct mtd_blktrans_dev *dev;
dev = hctx->queue->queuedata;
if (!dev) {
blk_mq_start_request(bd->rq);
return BLK_STS_IOERR;
}
spin_lock_irq(&dev->queue_lock);
list_add_tail(&bd->rq->queuelist, &dev->rq_list);
mtd_blktrans_work(dev);
spin_unlock_irq(&dev->queue_lock);
return BLK_STS_OK;
}
static int blktrans_open(struct gendisk *disk, blk_mode_t mode)
{
struct mtd_blktrans_dev *dev = disk->private_data;
int ret = 0;
kref_get(&dev->ref);
mutex_lock(&dev->lock);
if (dev->open)
goto unlock;
__module_get(dev->tr->owner);
if (!dev->mtd)
goto unlock;
if (dev->tr->open) {
ret = dev->tr->open(dev);
if (ret)
goto error_put;
}
ret = __get_mtd_device(dev->mtd);
if (ret)
goto error_release;
dev->writable = mode & BLK_OPEN_WRITE;
unlock:
dev->open++;
mutex_unlock(&dev->lock);
return ret;
error_release:
if (dev->tr->release)
dev->tr->release(dev);
error_put:
module_put(dev->tr->owner);
mutex_unlock(&dev->lock);
blktrans_dev_put(dev);
return ret;
}
static void blktrans_release(struct gendisk *disk)
{
struct mtd_blktrans_dev *dev = disk->private_data;
mutex_lock(&dev->lock);
if (--dev->open)
goto unlock;
module_put(dev->tr->owner);
if (dev->mtd) {
if (dev->tr->release)
dev->tr->release(dev);
__put_mtd_device(dev->mtd);
}
unlock:
mutex_unlock(&dev->lock);
blktrans_dev_put(dev);
}
static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
int ret = -ENXIO;
mutex_lock(&dev->lock);
if (!dev->mtd)
goto unlock;
ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY;
unlock:
mutex_unlock(&dev->lock);
return ret;
}
static const struct block_device_operations mtd_block_ops = {
.owner = THIS_MODULE,
.open = blktrans_open,
.release = blktrans_release,
.getgeo = blktrans_getgeo,
};
static const struct blk_mq_ops mtd_mq_ops = {
.queue_rq = mtd_queue_rq,
};
int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
{
struct mtd_blktrans_ops *tr = new->tr;
struct mtd_blktrans_dev *d;
struct queue_limits lim = { };
int last_devnum = -1;
struct gendisk *gd;
int ret;
lockdep_assert_held(&mtd_table_mutex);
list_for_each_entry(d, &tr->devs, list) {
if (new->devnum == -1) {
/* Use first free number */
if (d->devnum != last_devnum+1) {
/* Found a free devnum. Plug it in here */
new->devnum = last_devnum+1;
list_add_tail(&new->list, &d->list);
goto added;
}
} else if (d->devnum == new->devnum) {
/* Required number taken */
return -EBUSY;
} else if (d->devnum > new->devnum) {
/* Required number was free */
list_add_tail(&new->list, &d->list);
goto added;
}
last_devnum = d->devnum;
}
ret = -EBUSY;
if (new->devnum == -1)
new->devnum = last_devnum+1;
/* Check that the device and any partitions will get valid
* minor numbers and that the disk naming code below can cope
* with this number. */
if (new->devnum > (MINORMASK >> tr->part_bits) ||
(tr->part_bits && new->devnum >= 27 * 26))
return ret;
list_add_tail(&new->list, &tr->devs);
added:
mutex_init(&new->lock);
kref_init(&new->ref);
if (!tr->writesect)
new->readonly = 1;
ret = -ENOMEM;
new->tag_set = kzalloc(sizeof(*new->tag_set), GFP_KERNEL);
if (!new->tag_set)
goto out_list_del;
ret = blk_mq_alloc_sq_tag_set(new->tag_set, &mtd_mq_ops, 2,
BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING);
if (ret)
goto out_kfree_tag_set;
lim.logical_block_size = tr->blksize;
if (tr->discard)
lim.max_hw_discard_sectors = UINT_MAX;
if (tr->flush)
lim.features |= BLK_FEAT_WRITE_CACHE;
/* Create gendisk */
gd = blk_mq_alloc_disk(new->tag_set, &lim, new);
if (IS_ERR(gd)) {
ret = PTR_ERR(gd);
goto out_free_tag_set;
}
new->disk = gd;
new->rq = new->disk->queue;
gd->private_data = new;
gd->major = tr->major;
gd->first_minor = (new->devnum) << tr->part_bits;
gd->minors = 1 << tr->part_bits;
gd->fops = &mtd_block_ops;
if (tr->part_bits) {
if (new->devnum < 26)
snprintf(gd->disk_name, sizeof(gd->disk_name),
"%s%c", tr->name, 'a' + new->devnum);
else
snprintf(gd->disk_name, sizeof(gd->disk_name),
"%s%c%c", tr->name,
'a' - 1 + new->devnum / 26,
'a' + new->devnum % 26);
} else {
snprintf(gd->disk_name, sizeof(gd->disk_name),
"%s%d", tr->name, new->devnum);
gd->flags |= GENHD_FL_NO_PART;
}
set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
/* Create the request queue */
spin_lock_init(&new->queue_lock);
INIT_LIST_HEAD(&new->rq_list);
gd->queue = new->rq;
if (new->readonly)
set_disk_ro(gd, 1);
ret = device_add_disk(&new->mtd->dev, gd, NULL);
if (ret)
goto out_cleanup_disk;
if (new->disk_attributes) {
ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
new->disk_attributes);
WARN_ON(ret);
}
return 0;
out_cleanup_disk:
put_disk(new->disk);
out_free_tag_set:
blk_mq_free_tag_set(new->tag_set);
out_kfree_tag_set:
kfree(new->tag_set);
out_list_del:
list_del(&new->list);
return ret;
}
int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
{
unsigned long flags;
lockdep_assert_held(&mtd_table_mutex);
if (old->disk_attributes)
sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
old->disk_attributes);
/* Stop new requests to arrive */
del_gendisk(old->disk);
/* Kill current requests */
spin_lock_irqsave(&old->queue_lock, flags);
old->rq->queuedata = NULL;
spin_unlock_irqrestore(&old->queue_lock, flags);
/* freeze+quiesce queue to ensure all requests are flushed */
blk_mq_freeze_queue(old->rq);
blk_mq_quiesce_queue(old->rq);
blk_mq_unquiesce_queue(old->rq);
blk_mq_unfreeze_queue(old->rq);
/* If the device is currently open, tell trans driver to close it,
then put mtd device, and don't touch it again */
mutex_lock(&old->lock);
if (old->open) {
if (old->tr->release)
old->tr->release(old);
__put_mtd_device(old->mtd);
}
old->mtd = NULL;
mutex_unlock(&old->lock);
blktrans_dev_put(old);
return 0;
}
static void blktrans_notify_remove(struct mtd_info *mtd)
{
struct mtd_blktrans_ops *tr;
struct mtd_blktrans_dev *dev, *next;
list_for_each_entry(tr, &blktrans_majors, list)
list_for_each_entry_safe(dev, next, &tr->devs, list)
if (dev->mtd == mtd)
tr->remove_dev(dev);
}
static void blktrans_notify_add(struct mtd_info *mtd)
{
struct mtd_blktrans_ops *tr;
if (mtd->type == MTD_ABSENT || mtd->type == MTD_UBIVOLUME)
return;
list_for_each_entry(tr, &blktrans_majors, list)
tr->add_mtd(tr, mtd);
}
static struct mtd_notifier blktrans_notifier = {
.add = blktrans_notify_add,
.remove = blktrans_notify_remove,
};
int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
{
struct mtd_info *mtd;
int ret;
/* Register the notifier if/when the first device type is
registered, to prevent the link/init ordering from fucking
us over. */
if (!blktrans_notifier.list.next)
register_mtd_user(&blktrans_notifier);
ret = register_blkdev(tr->major, tr->name);
if (ret < 0) {
printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
tr->name, tr->major, ret);
return ret;
}
if (ret)
tr->major = ret;
tr->blkshift = ffs(tr->blksize) - 1;
INIT_LIST_HEAD(&tr->devs);
mutex_lock(&mtd_table_mutex);
list_add(&tr->list, &blktrans_majors);
mtd_for_each_device(mtd)
if (mtd->type != MTD_ABSENT && mtd->type != MTD_UBIVOLUME)
tr->add_mtd(tr, mtd);
mutex_unlock(&mtd_table_mutex);
return 0;
}
int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
{
struct mtd_blktrans_dev *dev, *next;
mutex_lock(&mtd_table_mutex);
/* Remove it from the list of active majors */
list_del(&tr->list);
list_for_each_entry_safe(dev, next, &tr->devs, list)
tr->remove_dev(dev);
mutex_unlock(&mtd_table_mutex);
unregister_blkdev(tr->major, tr->name);
BUG_ON(!list_empty(&tr->devs));
return 0;
}
static void __exit mtd_blktrans_exit(void)
{
/* No race here -- if someone's currently in register_mtd_blktrans
we're screwed anyway. */
if (blktrans_notifier.list.next)
unregister_mtd_user(&blktrans_notifier);
}
module_exit(mtd_blktrans_exit);
EXPORT_SYMBOL_GPL(register_mtd_blktrans);
EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
MODULE_AUTHOR("David Woodhouse <[email protected]>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");
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