[mirror_ubuntu-focal-kernel.git] / drivers / mtd / ubi / gluebi.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (c) International Business Machines Corp., 2006
 *
 * Author: Artem Bityutskiy (Битюцкий Артём), Joern Engel
 */

/*
 * This is a small driver which implements fake MTD devices on top of UBI
 * volumes. This sounds strange, but it is in fact quite useful to make
 * MTD-oriented software (including all the legacy software) work on top of
 * UBI.
 *
 * Gluebi emulates MTD devices of "MTD_UBIVOLUME" type. Their minimal I/O unit
 * size (@mtd->writesize) is equivalent to the UBI minimal I/O unit. The
 * eraseblock size is equivalent to the logical eraseblock size of the volume.
 */

#include <linux/err.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/mtd/ubi.h>
#include <linux/mtd/mtd.h>
#include "ubi-media.h"

#define err_msg(fmt, ...)                                   \
	pr_err("gluebi (pid %d): %s: " fmt "\n",            \
	       current->pid, __func__, ##__VA_ARGS__)

/**
 * struct gluebi_device - a gluebi device description data structure.
 * @mtd: emulated MTD device description object
 * @refcnt: gluebi device reference count
 * @desc: UBI volume descriptor
 * @ubi_num: UBI device number this gluebi device works on
 * @vol_id: ID of UBI volume this gluebi device works on
 * @list: link in a list of gluebi devices
 */
struct gluebi_device {
	struct mtd_info mtd;
	int refcnt;
	struct ubi_volume_desc *desc;
	int ubi_num;
	int vol_id;
	struct list_head list;
};

/* List of all gluebi devices */
static LIST_HEAD(gluebi_devices);
static DEFINE_MUTEX(devices_mutex);

/**
 * find_gluebi_nolock - find a gluebi device.
 * @ubi_num: UBI device number
 * @vol_id: volume ID
 *
 * This function seraches for gluebi device corresponding to UBI device
 * @ubi_num and UBI volume @vol_id. Returns the gluebi device description
 * object in case of success and %NULL in case of failure. The caller has to
 * have the &devices_mutex locked.
 */
static struct gluebi_device *find_gluebi_nolock(int ubi_num, int vol_id)
{
	struct gluebi_device *gluebi;

	list_for_each_entry(gluebi, &gluebi_devices, list)
		if (gluebi->ubi_num == ubi_num && gluebi->vol_id == vol_id)
			return gluebi;
	return NULL;
}

/**
 * gluebi_get_device - get MTD device reference.
 * @mtd: the MTD device description object
 *
 * This function is called every time the MTD device is being opened and
 * implements the MTD get_device() operation. Returns zero in case of success
 * and a negative error code in case of failure.
 */
static int gluebi_get_device(struct mtd_info *mtd)
{
	struct gluebi_device *gluebi;
	int ubi_mode = UBI_READONLY;

	if (mtd->flags & MTD_WRITEABLE)
		ubi_mode = UBI_READWRITE;

	gluebi = container_of(mtd, struct gluebi_device, mtd);
	mutex_lock(&devices_mutex);
	if (gluebi->refcnt > 0) {
		/*
		 * The MTD device is already referenced and this is just one
		 * more reference. MTD allows many users to open the same
		 * volume simultaneously and do not distinguish between
		 * readers/writers/exclusive/meta openers as UBI does. So we do
		 * not open the UBI volume again - just increase the reference
		 * counter and return.
		 */
		gluebi->refcnt += 1;
		mutex_unlock(&devices_mutex);
		return 0;
	}

	/*
	 * This is the first reference to this UBI volume via the MTD device
	 * interface. Open the corresponding volume in read-write mode.
	 */
	gluebi->desc = ubi_open_volume(gluebi->ubi_num, gluebi->vol_id,
				       ubi_mode);
	if (IS_ERR(gluebi->desc)) {
		mutex_unlock(&devices_mutex);
		return PTR_ERR(gluebi->desc);
	}
	gluebi->refcnt += 1;
	mutex_unlock(&devices_mutex);
	return 0;
}

/**
 * gluebi_put_device - put MTD device reference.
 * @mtd: the MTD device description object
 *
 * This function is called every time the MTD device is being put. Returns
 * zero in case of success and a negative error code in case of failure.
 */
static void gluebi_put_device(struct mtd_info *mtd)
{
	struct gluebi_device *gluebi;

	gluebi = container_of(mtd, struct gluebi_device, mtd);
	mutex_lock(&devices_mutex);
	gluebi->refcnt -= 1;
	if (gluebi->refcnt == 0)
		ubi_close_volume(gluebi->desc);
	mutex_unlock(&devices_mutex);
}

/**
 * gluebi_read - read operation of emulated MTD devices.
 * @mtd: MTD device description object
 * @from: absolute offset from where to read
 * @len: how many bytes to read
 * @retlen: count of read bytes is returned here
 * @buf: buffer to store the read data
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len,
		       size_t *retlen, unsigned char *buf)
{
	int err = 0, lnum, offs, bytes_left;
	struct gluebi_device *gluebi;

	gluebi = container_of(mtd, struct gluebi_device, mtd);
	lnum = div_u64_rem(from, mtd->erasesize, &offs);
	bytes_left = len;
	while (bytes_left) {
		size_t to_read = mtd->erasesize - offs;

		if (to_read > bytes_left)
			to_read = bytes_left;

		err = ubi_read(gluebi->desc, lnum, buf, offs, to_read);
		if (err)
			break;

		lnum += 1;
		offs = 0;
		bytes_left -= to_read;
		buf += to_read;
	}

	*retlen = len - bytes_left;
	return err;
}

/**
 * gluebi_write - write operation of emulated MTD devices.
 * @mtd: MTD device description object
 * @to: absolute offset where to write
 * @len: how many bytes to write
 * @retlen: count of written bytes is returned here
 * @buf: buffer with data to write
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
			size_t *retlen, const u_char *buf)
{
	int err = 0, lnum, offs, bytes_left;
	struct gluebi_device *gluebi;

	gluebi = container_of(mtd, struct gluebi_device, mtd);
	lnum = div_u64_rem(to, mtd->erasesize, &offs);

	if (len % mtd->writesize || offs % mtd->writesize)
		return -EINVAL;

	bytes_left = len;
	while (bytes_left) {
		size_t to_write = mtd->erasesize - offs;

		if (to_write > bytes_left)
			to_write = bytes_left;

		err = ubi_leb_write(gluebi->desc, lnum, buf, offs, to_write);
		if (err)
			break;

		lnum += 1;
		offs = 0;
		bytes_left -= to_write;
		buf += to_write;
	}

	*retlen = len - bytes_left;
	return err;
}

/**
 * gluebi_erase - erase operation of emulated MTD devices.
 * @mtd: the MTD device description object
 * @instr: the erase operation description
 *
 * This function calls the erase callback when finishes. Returns zero in case
 * of success and a negative error code in case of failure.
 */
static int gluebi_erase(struct mtd_info *mtd, struct erase_info *instr)
{
	int err, i, lnum, count;
	struct gluebi_device *gluebi;

	if (mtd_mod_by_ws(instr->addr, mtd) || mtd_mod_by_ws(instr->len, mtd))
		return -EINVAL;

	lnum = mtd_div_by_eb(instr->addr, mtd);
	count = mtd_div_by_eb(instr->len, mtd);
	gluebi = container_of(mtd, struct gluebi_device, mtd);

	for (i = 0; i < count - 1; i++) {
		err = ubi_leb_unmap(gluebi->desc, lnum + i);
		if (err)
			goto out_err;
	}
	/*
	 * MTD erase operations are synchronous, so we have to make sure the
	 * physical eraseblock is wiped out.
	 *
	 * Thus, perform leb_erase instead of leb_unmap operation - leb_erase
	 * will wait for the end of operations
	 */
	err = ubi_leb_erase(gluebi->desc, lnum + i);
	if (err)
		goto out_err;

	return 0;

out_err:
	instr->fail_addr = (long long)lnum * mtd->erasesize;
	return err;
}

/**
 * gluebi_create - create a gluebi device for an UBI volume.
 * @di: UBI device description object
 * @vi: UBI volume description object
 *
 * This function is called when a new UBI volume is created in order to create
 * corresponding fake MTD device. Returns zero in case of success and a
 * negative error code in case of failure.
 */
static int gluebi_create(struct ubi_device_info *di,
			 struct ubi_volume_info *vi)
{
	struct gluebi_device *gluebi, *g;
	struct mtd_info *mtd;

	gluebi = kzalloc(sizeof(struct gluebi_device), GFP_KERNEL);
	if (!gluebi)
		return -ENOMEM;

	mtd = &gluebi->mtd;
	mtd->name = kmemdup(vi->name, vi->name_len + 1, GFP_KERNEL);
	if (!mtd->name) {
		kfree(gluebi);
		return -ENOMEM;
	}

	gluebi->vol_id = vi->vol_id;
	gluebi->ubi_num = vi->ubi_num;
	mtd->type = MTD_UBIVOLUME;
	if (!di->ro_mode)
		mtd->flags = MTD_WRITEABLE;
	mtd->owner      = THIS_MODULE;
	mtd->writesize  = di->min_io_size;
	mtd->erasesize  = vi->usable_leb_size;
	mtd->_read       = gluebi_read;
	mtd->_write      = gluebi_write;
	mtd->_erase      = gluebi_erase;
	mtd->_get_device = gluebi_get_device;
	mtd->_put_device = gluebi_put_device;

	/*
	 * In case of dynamic a volume, MTD device size is just volume size. In
	 * case of a static volume the size is equivalent to the amount of data
	 * bytes.
	 */
	if (vi->vol_type == UBI_DYNAMIC_VOLUME)
		mtd->size = (unsigned long long)vi->usable_leb_size * vi->size;
	else
		mtd->size = vi->used_bytes;

	/* Just a sanity check - make sure this gluebi device does not exist */
	mutex_lock(&devices_mutex);
	g = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	if (g)
		err_msg("gluebi MTD device %d form UBI device %d volume %d already exists",
			g->mtd.index, vi->ubi_num, vi->vol_id);
	mutex_unlock(&devices_mutex);

	if (mtd_device_register(mtd, NULL, 0)) {
		err_msg("cannot add MTD device");
		kfree(mtd->name);
		kfree(gluebi);
		return -ENFILE;
	}

	mutex_lock(&devices_mutex);
	list_add_tail(&gluebi->list, &gluebi_devices);
	mutex_unlock(&devices_mutex);
	return 0;
}

/**
 * gluebi_remove - remove a gluebi device.
 * @vi: UBI volume description object
 *
 * This function is called when an UBI volume is removed and it removes
 * corresponding fake MTD device. Returns zero in case of success and a
 * negative error code in case of failure.
 */
static int gluebi_remove(struct ubi_volume_info *vi)
{
	int err = 0;
	struct mtd_info *mtd;
	struct gluebi_device *gluebi;

	mutex_lock(&devices_mutex);
	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	if (!gluebi) {
		err_msg("got remove notification for unknown UBI device %d volume %d",
			vi->ubi_num, vi->vol_id);
		err = -ENOENT;
	} else if (gluebi->refcnt)
		err = -EBUSY;
	else
		list_del(&gluebi->list);
	mutex_unlock(&devices_mutex);
	if (err)
		return err;

	mtd = &gluebi->mtd;
	err = mtd_device_unregister(mtd);
	if (err) {
		err_msg("cannot remove fake MTD device %d, UBI device %d, volume %d, error %d",
			mtd->index, gluebi->ubi_num, gluebi->vol_id, err);
		mutex_lock(&devices_mutex);
		list_add_tail(&gluebi->list, &gluebi_devices);
		mutex_unlock(&devices_mutex);
		return err;
	}

	kfree(mtd->name);
	kfree(gluebi);
	return 0;
}

/**
 * gluebi_updated - UBI volume was updated notifier.
 * @vi: volume info structure
 *
 * This function is called every time an UBI volume is updated. It does nothing
 * if te volume @vol is dynamic, and changes MTD device size if the
 * volume is static. This is needed because static volumes cannot be read past
 * data they contain. This function returns zero in case of success and a
 * negative error code in case of error.
 */
static int gluebi_updated(struct ubi_volume_info *vi)
{
	struct gluebi_device *gluebi;

	mutex_lock(&devices_mutex);
	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	if (!gluebi) {
		mutex_unlock(&devices_mutex);
		err_msg("got update notification for unknown UBI device %d volume %d",
			vi->ubi_num, vi->vol_id);
		return -ENOENT;
	}

	if (vi->vol_type == UBI_STATIC_VOLUME)
		gluebi->mtd.size = vi->used_bytes;
	mutex_unlock(&devices_mutex);
	return 0;
}

/**
 * gluebi_resized - UBI volume was re-sized notifier.
 * @vi: volume info structure
 *
 * This function is called every time an UBI volume is re-size. It changes the
 * corresponding fake MTD device size. This function returns zero in case of
 * success and a negative error code in case of error.
 */
static int gluebi_resized(struct ubi_volume_info *vi)
{
	struct gluebi_device *gluebi;

	mutex_lock(&devices_mutex);
	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	if (!gluebi) {
		mutex_unlock(&devices_mutex);
		err_msg("got update notification for unknown UBI device %d volume %d",
			vi->ubi_num, vi->vol_id);
		return -ENOENT;
	}
	gluebi->mtd.size = vi->used_bytes;
	mutex_unlock(&devices_mutex);
	return 0;
}

/**
 * gluebi_notify - UBI notification handler.
 * @nb: registered notifier block
 * @l: notification type
 * @ptr: pointer to the &struct ubi_notification object
 */
static int gluebi_notify(struct notifier_block *nb, unsigned long l,
			 void *ns_ptr)
{
	struct ubi_notification *nt = ns_ptr;

	switch (l) {
	case UBI_VOLUME_ADDED:
		gluebi_create(&nt->di, &nt->vi);
		break;
	case UBI_VOLUME_REMOVED:
		gluebi_remove(&nt->vi);
		break;
	case UBI_VOLUME_RESIZED:
		gluebi_resized(&nt->vi);
		break;
	case UBI_VOLUME_UPDATED:
		gluebi_updated(&nt->vi);
		break;
	default:
		break;
	}
	return NOTIFY_OK;
}

static struct notifier_block gluebi_notifier = {
	.notifier_call	= gluebi_notify,
};

static int __init ubi_gluebi_init(void)
{
	return ubi_register_volume_notifier(&gluebi_notifier, 0);
}

static void __exit ubi_gluebi_exit(void)
{
	struct gluebi_device *gluebi, *g;

	list_for_each_entry_safe(gluebi, g, &gluebi_devices, list) {
		int err;
		struct mtd_info *mtd = &gluebi->mtd;

		err = mtd_device_unregister(mtd);
		if (err)
			err_msg("error %d while removing gluebi MTD device %d, UBI device %d, volume %d - ignoring",
				err, mtd->index, gluebi->ubi_num,
				gluebi->vol_id);
		kfree(mtd->name);
		kfree(gluebi);
	}
	ubi_unregister_volume_notifier(&gluebi_notifier);
}

module_init(ubi_gluebi_init);
module_exit(ubi_gluebi_exit);
MODULE_DESCRIPTION("MTD emulation layer over UBI volumes");
MODULE_AUTHOR("Artem Bityutskiy, Joern Engel");
MODULE_LICENSE("GPL");
Commit	Line	Data
1a59d1b8	1	// SPDX-License-Identifier: GPL-2.0-or-later
801c135c AB	2	/*
	3	* Copyright (c) International Business Machines Corp., 2006
	4	*
801c135c AB	5	* Author: Artem Bityutskiy (Битюцкий Артём), Joern Engel
	6	*/
	7
	8	/*
2ba3d76a DP	9	* This is a small driver which implements fake MTD devices on top of UBI
	10	* volumes. This sounds strange, but it is in fact quite useful to make
	11	* MTD-oriented software (including all the legacy software) work on top of
	12	* UBI.
801c135c AB	13	*
801c135c AB	14	* Gluebi emulates MTD devices of "MTD_UBIVOLUME" type. Their minimal I/O unit
2ba3d76a	15	* size (@mtd->writesize) is equivalent to the UBI minimal I/O unit. The
801c135c AB	16	* eraseblock size is equivalent to the logical eraseblock size of the volume.
	17	*/
	18
2ba3d76a DP	19	#include <linux/err.h>
2ba3d76a DP	20	#include <linux/list.h>
5a0e3ad6	21	#include <linux/slab.h>
2ba3d76a	22	#include <linux/sched.h>
3013ee31	23	#include <linux/math64.h>
2ba3d76a DP	24	#include <linux/module.h>
	25	#include <linux/mutex.h>
	26	#include <linux/mtd/ubi.h>
	27	#include <linux/mtd/mtd.h>
	28	#include "ubi-media.h"
	29
	30	#define err_msg(fmt, ...) \
e28453bb	31	pr_err("gluebi (pid %d): %s: " fmt "\n", \
2ba3d76a DP	32	current->pid, __func__, ##__VA_ARGS__)
	33
	34	/**
	35	* struct gluebi_device - a gluebi device description data structure.
	36	* @mtd: emulated MTD device description object
	37	* @refcnt: gluebi device reference count
	38	* @desc: UBI volume descriptor
	39	* @ubi_num: UBI device number this gluebi device works on
	40	* @vol_id: ID of UBI volume this gluebi device works on
	41	* @list: link in a list of gluebi devices
	42	*/
	43	struct gluebi_device {
	44	struct mtd_info mtd;
	45	int refcnt;
	46	struct ubi_volume_desc *desc;
	47	int ubi_num;
	48	int vol_id;
	49	struct list_head list;
	50	};
	51
	52	/* List of all gluebi devices */
	53	static LIST_HEAD(gluebi_devices);
	54	static DEFINE_MUTEX(devices_mutex);
	55
	56	/**
	57	* find_gluebi_nolock - find a gluebi device.
	58	* @ubi_num: UBI device number
	59	* @vol_id: volume ID
	60	*
	61	* This function seraches for gluebi device corresponding to UBI device
	62	* @ubi_num and UBI volume @vol_id. Returns the gluebi device description
	63	* object in case of success and %NULL in case of failure. The caller has to
	64	* have the &devices_mutex locked.
	65	*/
	66	static struct gluebi_device *find_gluebi_nolock(int ubi_num, int vol_id)
	67	{
	68	struct gluebi_device *gluebi;
	69
	70	list_for_each_entry(gluebi, &gluebi_devices, list)
	71	if (gluebi->ubi_num == ubi_num && gluebi->vol_id == vol_id)
	72	return gluebi;
	73	return NULL;
	74	}
801c135c AB	75
	76	/**
	77	* gluebi_get_device - get MTD device reference.
	78	* @mtd: the MTD device description object
	79	*
	80	* This function is called every time the MTD device is being opened and
	81	* implements the MTD get_device() operation. Returns zero in case of success
	82	* and a negative error code in case of failure.
	83	*/
	84	static int gluebi_get_device(struct mtd_info *mtd)
	85	{
2ba3d76a DP	86	struct gluebi_device *gluebi;
2ba3d76a DP	87	int ubi_mode = UBI_READONLY;
801c135c	88
2ba3d76a DP	89	if (mtd->flags & MTD_WRITEABLE)
	90	ubi_mode = UBI_READWRITE;
	91
	92	gluebi = container_of(mtd, struct gluebi_device, mtd);
	93	mutex_lock(&devices_mutex);
	94	if (gluebi->refcnt > 0) {
801c135c AB	95	/*
	96	* The MTD device is already referenced and this is just one
	97	* more reference. MTD allows many users to open the same
	98	* volume simultaneously and do not distinguish between
061eebba AM	99	* readers/writers/exclusive/meta openers as UBI does. So we do
061eebba AM	100	* not open the UBI volume again - just increase the reference
801c135c AB	101	* counter and return.
801c135c AB	102	*/
2ba3d76a DP	103	gluebi->refcnt += 1;
2ba3d76a DP	104	mutex_unlock(&devices_mutex);
801c135c AB	105	return 0;
	106	}
	107
	108	/*
	109	* This is the first reference to this UBI volume via the MTD device
	110	* interface. Open the corresponding volume in read-write mode.
	111	*/
2ba3d76a DP	112	gluebi->desc = ubi_open_volume(gluebi->ubi_num, gluebi->vol_id,
	113	ubi_mode);
	114	if (IS_ERR(gluebi->desc)) {
	115	mutex_unlock(&devices_mutex);
2ba3d76a DP	116	return PTR_ERR(gluebi->desc);
	117	}
	118	gluebi->refcnt += 1;
	119	mutex_unlock(&devices_mutex);
801c135c AB	120	return 0;
	121	}
	122
	123	/**
	124	* gluebi_put_device - put MTD device reference.
	125	* @mtd: the MTD device description object
	126	*
	127	* This function is called every time the MTD device is being put. Returns
	128	* zero in case of success and a negative error code in case of failure.
	129	*/
	130	static void gluebi_put_device(struct mtd_info *mtd)
	131	{
2ba3d76a DP	132	struct gluebi_device *gluebi;
	133
	134	gluebi = container_of(mtd, struct gluebi_device, mtd);
	135	mutex_lock(&devices_mutex);
	136	gluebi->refcnt -= 1;
	137	if (gluebi->refcnt == 0)
	138	ubi_close_volume(gluebi->desc);
2ba3d76a	139	mutex_unlock(&devices_mutex);
801c135c AB	140	}
	141
	142	/**
	143	* gluebi_read - read operation of emulated MTD devices.
	144	* @mtd: MTD device description object
	145	* @from: absolute offset from where to read
	146	* @len: how many bytes to read
	147	* @retlen: count of read bytes is returned here
	148	* @buf: buffer to store the read data
	149	*
	150	* This function returns zero in case of success and a negative error code in
	151	* case of failure.
	152	*/
	153	static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len,
	154	size_t retlen, unsigned char buf)
	155	{
41c04384	156	int err = 0, lnum, offs, bytes_left;
2ba3d76a	157	struct gluebi_device *gluebi;
801c135c	158
2ba3d76a	159	gluebi = container_of(mtd, struct gluebi_device, mtd);
3013ee31	160	lnum = div_u64_rem(from, mtd->erasesize, &offs);
41c04384 EG	161	bytes_left = len;
41c04384 EG	162	while (bytes_left) {
801c135c AB	163	size_t to_read = mtd->erasesize - offs;
801c135c AB	164
41c04384 EG	165	if (to_read > bytes_left)
41c04384 EG	166	to_read = bytes_left;
801c135c	167
2ba3d76a	168	err = ubi_read(gluebi->desc, lnum, buf, offs, to_read);
801c135c AB	169	if (err)
	170	break;
	171
	172	lnum += 1;
	173	offs = 0;
41c04384	174	bytes_left -= to_read;
801c135c AB	175	buf += to_read;
	176	}
	177
41c04384	178	*retlen = len - bytes_left;
801c135c AB	179	return err;
	180	}
	181
	182	/**
	183	* gluebi_write - write operation of emulated MTD devices.
	184	* @mtd: MTD device description object
	185	* @to: absolute offset where to write
	186	* @len: how many bytes to write
	187	* @retlen: count of written bytes is returned here
	188	* @buf: buffer with data to write
	189	*
	190	* This function returns zero in case of success and a negative error code in
	191	* case of failure.
	192	*/
	193	static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
2ba3d76a	194	size_t retlen, const u_char buf)
801c135c	195	{
41c04384	196	int err = 0, lnum, offs, bytes_left;
2ba3d76a	197	struct gluebi_device *gluebi;
801c135c	198
2ba3d76a	199	gluebi = container_of(mtd, struct gluebi_device, mtd);
3013ee31	200	lnum = div_u64_rem(to, mtd->erasesize, &offs);
801c135c AB	201
	202	if (len % mtd->writesize \|\| offs % mtd->writesize)
	203	return -EINVAL;
	204
41c04384 EG	205	bytes_left = len;
41c04384 EG	206	while (bytes_left) {
801c135c AB	207	size_t to_write = mtd->erasesize - offs;
801c135c AB	208
41c04384 EG	209	if (to_write > bytes_left)
41c04384 EG	210	to_write = bytes_left;
801c135c	211
b36a261e	212	err = ubi_leb_write(gluebi->desc, lnum, buf, offs, to_write);
801c135c AB	213	if (err)
	214	break;
	215
	216	lnum += 1;
	217	offs = 0;
41c04384	218	bytes_left -= to_write;
801c135c AB	219	buf += to_write;
	220	}
	221
41c04384	222	*retlen = len - bytes_left;
801c135c AB	223	return err;
	224	}
	225
	226	/**
	227	* gluebi_erase - erase operation of emulated MTD devices.
	228	* @mtd: the MTD device description object
	229	* @instr: the erase operation description
	230	*
	231	* This function calls the erase callback when finishes. Returns zero in case
	232	* of success and a negative error code in case of failure.
	233	*/
	234	static int gluebi_erase(struct mtd_info mtd, struct erase_info instr)
	235	{
	236	int err, i, lnum, count;
2ba3d76a	237	struct gluebi_device *gluebi;
801c135c	238
69423d99	239	if (mtd_mod_by_ws(instr->addr, mtd) \|\| mtd_mod_by_ws(instr->len, mtd))
801c135c AB	240	return -EINVAL;
801c135c AB	241
69423d99 AH	242	lnum = mtd_div_by_eb(instr->addr, mtd);
69423d99 AH	243	count = mtd_div_by_eb(instr->len, mtd);
2ba3d76a	244	gluebi = container_of(mtd, struct gluebi_device, mtd);
801c135c	245
2ba3d76a DP	246	for (i = 0; i < count - 1; i++) {
2ba3d76a DP	247	err = ubi_leb_unmap(gluebi->desc, lnum + i);
801c135c AB	248	if (err)
	249	goto out_err;
	250	}
801c135c AB	251	/*
	252	* MTD erase operations are synchronous, so we have to make sure the
	253	* physical eraseblock is wiped out.
2ba3d76a DP	254	*
	255	* Thus, perform leb_erase instead of leb_unmap operation - leb_erase
	256	* will wait for the end of operations
801c135c	257	*/
2ba3d76a	258	err = ubi_leb_erase(gluebi->desc, lnum + i);
801c135c AB	259	if (err)
	260	goto out_err;
	261
801c135c AB	262	return 0;
	263
	264	out_err:
69423d99	265	instr->fail_addr = (long long)lnum * mtd->erasesize;
801c135c AB	266	return err;
	267	}
	268
	269	/**
2ba3d76a DP	270	* gluebi_create - create a gluebi device for an UBI volume.
	271	* @di: UBI device description object
	272	* @vi: UBI volume description object
801c135c	273	*
2ba3d76a	274	* This function is called when a new UBI volume is created in order to create
801c135c AB	275	* corresponding fake MTD device. Returns zero in case of success and a
	276	* negative error code in case of failure.
	277	*/
2ba3d76a DP	278	static int gluebi_create(struct ubi_device_info *di,
2ba3d76a DP	279	struct ubi_volume_info *vi)
801c135c	280	{
2ba3d76a DP	281	struct gluebi_device gluebi, g;
2ba3d76a DP	282	struct mtd_info *mtd;
801c135c	283
2ba3d76a DP	284	gluebi = kzalloc(sizeof(struct gluebi_device), GFP_KERNEL);
2ba3d76a DP	285	if (!gluebi)
801c135c AB	286	return -ENOMEM;
801c135c AB	287
2ba3d76a DP	288	mtd = &gluebi->mtd;
	289	mtd->name = kmemdup(vi->name, vi->name_len + 1, GFP_KERNEL);
	290	if (!mtd->name) {
	291	kfree(gluebi);
	292	return -ENOMEM;
	293	}
	294
	295	gluebi->vol_id = vi->vol_id;
c8cc4525	296	gluebi->ubi_num = vi->ubi_num;
801c135c	297	mtd->type = MTD_UBIVOLUME;
2ba3d76a	298	if (!di->ro_mode)
801c135c	299	mtd->flags = MTD_WRITEABLE;
801c135c	300	mtd->owner = THIS_MODULE;
2ba3d76a DP	301	mtd->writesize = di->min_io_size;
2ba3d76a DP	302	mtd->erasesize = vi->usable_leb_size;
3c3c10bb AB	303	mtd->_read = gluebi_read;
	304	mtd->_write = gluebi_write;
	305	mtd->_erase = gluebi_erase;
	306	mtd->_get_device = gluebi_get_device;
	307	mtd->_put_device = gluebi_put_device;
801c135c	308
941dfb07	309	/*
2ba3d76a	310	* In case of dynamic a volume, MTD device size is just volume size. In
941dfb07	311	* case of a static volume the size is equivalent to the amount of data
cbd8a9d2	312	* bytes.
941dfb07	313	*/
2ba3d76a DP	314	if (vi->vol_type == UBI_DYNAMIC_VOLUME)
2ba3d76a DP	315	mtd->size = (unsigned long long)vi->usable_leb_size * vi->size;
cbd8a9d2	316	else
2ba3d76a DP	317	mtd->size = vi->used_bytes;
	318
	319	/* Just a sanity check - make sure this gluebi device does not exist */
	320	mutex_lock(&devices_mutex);
	321	g = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	322	if (g)
049333ce AB	323	err_msg("gluebi MTD device %d form UBI device %d volume %d already exists",
049333ce AB	324	g->mtd.index, vi->ubi_num, vi->vol_id);
2ba3d76a	325	mutex_unlock(&devices_mutex);
941dfb07	326
ee0e87b1	327	if (mtd_device_register(mtd, NULL, 0)) {
2ba3d76a	328	err_msg("cannot add MTD device");
801c135c	329	kfree(mtd->name);
2ba3d76a	330	kfree(gluebi);
801c135c AB	331	return -ENFILE;
	332	}
	333
2ba3d76a DP	334	mutex_lock(&devices_mutex);
	335	list_add_tail(&gluebi->list, &gluebi_devices);
	336	mutex_unlock(&devices_mutex);
801c135c AB	337	return 0;
	338	}
	339
	340	/**
2ba3d76a DP	341	* gluebi_remove - remove a gluebi device.
2ba3d76a DP	342	* @vi: UBI volume description object
801c135c	343	*
2ba3d76a	344	* This function is called when an UBI volume is removed and it removes
801c135c AB	345	* corresponding fake MTD device. Returns zero in case of success and a
	346	* negative error code in case of failure.
	347	*/
2ba3d76a	348	static int gluebi_remove(struct ubi_volume_info *vi)
801c135c	349	{
2ba3d76a DP	350	int err = 0;
	351	struct mtd_info *mtd;
	352	struct gluebi_device *gluebi;
	353
	354	mutex_lock(&devices_mutex);
	355	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	356	if (!gluebi) {
049333ce AB	357	err_msg("got remove notification for unknown UBI device %d volume %d",
049333ce AB	358	vi->ubi_num, vi->vol_id);
2ba3d76a DP	359	err = -ENOENT;
	360	} else if (gluebi->refcnt)
	361	err = -EBUSY;
	362	else
	363	list_del(&gluebi->list);
	364	mutex_unlock(&devices_mutex);
	365	if (err)
	366	return err;
801c135c	367
2ba3d76a	368	mtd = &gluebi->mtd;
ee0e87b1	369	err = mtd_device_unregister(mtd);
2ba3d76a	370	if (err) {
049333ce AB	371	err_msg("cannot remove fake MTD device %d, UBI device %d, volume %d, error %d",
049333ce AB	372	mtd->index, gluebi->ubi_num, gluebi->vol_id, err);
2ba3d76a DP	373	mutex_lock(&devices_mutex);
	374	list_add_tail(&gluebi->list, &gluebi_devices);
	375	mutex_unlock(&devices_mutex);
801c135c	376	return err;
2ba3d76a DP	377	}
2ba3d76a DP	378
801c135c	379	kfree(mtd->name);
2ba3d76a	380	kfree(gluebi);
801c135c AB	381	return 0;
801c135c AB	382	}
941dfb07 AB	383
941dfb07 AB	384	/**
2ba3d76a DP	385	* gluebi_updated - UBI volume was updated notifier.
2ba3d76a DP	386	* @vi: volume info structure
941dfb07	387	*
2ba3d76a DP	388	* This function is called every time an UBI volume is updated. It does nothing
2ba3d76a DP	389	* if te volume @vol is dynamic, and changes MTD device size if the
941dfb07	390	* volume is static. This is needed because static volumes cannot be read past
2ba3d76a DP	391	* data they contain. This function returns zero in case of success and a
	392	* negative error code in case of error.
	393	*/
	394	static int gluebi_updated(struct ubi_volume_info *vi)
	395	{
	396	struct gluebi_device *gluebi;
	397
	398	mutex_lock(&devices_mutex);
	399	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	400	if (!gluebi) {
	401	mutex_unlock(&devices_mutex);
049333ce AB	402	err_msg("got update notification for unknown UBI device %d volume %d",
049333ce AB	403	vi->ubi_num, vi->vol_id);
2ba3d76a DP	404	return -ENOENT;
	405	}
	406
	407	if (vi->vol_type == UBI_STATIC_VOLUME)
	408	gluebi->mtd.size = vi->used_bytes;
	409	mutex_unlock(&devices_mutex);
	410	return 0;
	411	}
	412
	413	/**
	414	* gluebi_resized - UBI volume was re-sized notifier.
	415	* @vi: volume info structure
	416	*
	417	* This function is called every time an UBI volume is re-size. It changes the
	418	* corresponding fake MTD device size. This function returns zero in case of
	419	* success and a negative error code in case of error.
	420	*/
	421	static int gluebi_resized(struct ubi_volume_info *vi)
	422	{
	423	struct gluebi_device *gluebi;
	424
	425	mutex_lock(&devices_mutex);
	426	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	427	if (!gluebi) {
	428	mutex_unlock(&devices_mutex);
049333ce AB	429	err_msg("got update notification for unknown UBI device %d volume %d",
049333ce AB	430	vi->ubi_num, vi->vol_id);
2ba3d76a DP	431	return -ENOENT;
	432	}
	433	gluebi->mtd.size = vi->used_bytes;
	434	mutex_unlock(&devices_mutex);
	435	return 0;
	436	}
	437
	438	/**
	439	* gluebi_notify - UBI notification handler.
	440	* @nb: registered notifier block
	441	* @l: notification type
	442	* @ptr: pointer to the &struct ubi_notification object
941dfb07	443	*/
2ba3d76a DP	444	static int gluebi_notify(struct notifier_block *nb, unsigned long l,
2ba3d76a DP	445	void *ns_ptr)
941dfb07	446	{
2ba3d76a DP	447	struct ubi_notification *nt = ns_ptr;
	448
	449	switch (l) {
	450	case UBI_VOLUME_ADDED:
	451	gluebi_create(&nt->di, &nt->vi);
	452	break;
	453	case UBI_VOLUME_REMOVED:
	454	gluebi_remove(&nt->vi);
	455	break;
	456	case UBI_VOLUME_RESIZED:
	457	gluebi_resized(&nt->vi);
	458	break;
	459	case UBI_VOLUME_UPDATED:
	460	gluebi_updated(&nt->vi);
	461	break;
	462	default:
	463	break;
	464	}
	465	return NOTIFY_OK;
	466	}
941dfb07	467
2ba3d76a DP	468	static struct notifier_block gluebi_notifier = {
	469	.notifier_call = gluebi_notify,
	470	};
	471
	472	static int __init ubi_gluebi_init(void)
	473	{
	474	return ubi_register_volume_notifier(&gluebi_notifier, 0);
941dfb07	475	}
2ba3d76a DP	476
	477	static void __exit ubi_gluebi_exit(void)
	478	{
	479	struct gluebi_device gluebi, g;
	480
	481	list_for_each_entry_safe(gluebi, g, &gluebi_devices, list) {
	482	int err;
	483	struct mtd_info *mtd = &gluebi->mtd;
	484
ee0e87b1	485	err = mtd_device_unregister(mtd);
2ba3d76a	486	if (err)
049333ce AB	487	err_msg("error %d while removing gluebi MTD device %d, UBI device %d, volume %d - ignoring",
	488	err, mtd->index, gluebi->ubi_num,
	489	gluebi->vol_id);
2ba3d76a DP	490	kfree(mtd->name);
	491	kfree(gluebi);
	492	}
	493	ubi_unregister_volume_notifier(&gluebi_notifier);
	494	}
	495
	496	module_init(ubi_gluebi_init);
	497	module_exit(ubi_gluebi_exit);
	498	MODULE_DESCRIPTION("MTD emulation layer over UBI volumes");
	499	MODULE_AUTHOR("Artem Bityutskiy, Joern Engel");
	500	MODULE_LICENSE("GPL");