/*
* Copyright (c) International Business Machines Corp., 2006
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Author: Artem Bityutskiy (Битюцкий Артём)
*/
/* This file mostly implements UBI kernel API functions */
#include <linux/module.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/fs.h>
#include <asm/div64.h>
#include "ubi.h"
/**
* ubi_do_get_device_info - get information about UBI device.
* @ubi: UBI device description object
* @di: the information is stored here
*
* This function is the same as 'ubi_get_device_info()', but it assumes the UBI
* device is locked and cannot disappear.
*/
void ubi_do_get_device_info(struct ubi_device *ubi, struct ubi_device_info *di)
{
di->ubi_num = ubi->ubi_num;
di->leb_size = ubi->leb_size;
di->min_io_size = ubi->min_io_size;
di->ro_mode = ubi->ro_mode;
di->cdev = ubi->cdev.dev;
}
EXPORT_SYMBOL_GPL(ubi_do_get_device_info);
/**
* ubi_get_device_info - get information about UBI device.
* @ubi_num: UBI device number
* @di: the information is stored here
*
* This function returns %0 in case of success, %-EINVAL if the UBI device
* number is invalid, and %-ENODEV if there is no such UBI device.
*/
int ubi_get_device_info(int ubi_num, struct ubi_device_info *di)
{
struct ubi_device *ubi;
if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
return -EINVAL;
ubi = ubi_get_device(ubi_num);
if (!ubi)
return -ENODEV;
ubi_do_get_device_info(ubi, di);
ubi_put_device(ubi);
return 0;
}
EXPORT_SYMBOL_GPL(ubi_get_device_info);
/**
* ubi_do_get_volume_info - get information about UBI volume.
* @ubi: UBI device description object
* @vol: volume description object
* @vi: the information is stored here
*/
void ubi_do_get_volume_info(struct ubi_device *ubi, struct ubi_volume *vol,
struct ubi_volume_info *vi)
{
vi->vol_id = vol->vol_id;
vi->ubi_num = ubi->ubi_num;
vi->size = vol->reserved_pebs;
vi->used_bytes = vol->used_bytes;
vi->vol_type = vol->vol_type;
vi->corrupted = vol->corrupted;
vi->upd_marker = vol->upd_marker;
vi->alignment = vol->alignment;
vi->usable_leb_size = vol->usable_leb_size;
vi->name_len = vol->name_len;
vi->name = vol->name;
vi->cdev = vol->cdev.dev;
}
/**
* ubi_get_volume_info - get information about UBI volume.
* @desc: volume descriptor
* @vi: the information is stored here
*/
void ubi_get_volume_info(struct ubi_volume_desc *desc,
struct ubi_volume_info *vi)
{
ubi_do_get_volume_info(desc->vol->ubi, desc->vol, vi);
}
EXPORT_SYMBOL_GPL(ubi_get_volume_info);
/**
* ubi_open_volume - open UBI volume.
* @ubi_num: UBI device number
* @vol_id: volume ID
* @mode: open mode
*
* The @mode parameter specifies if the volume should be opened in read-only
* mode, read-write mode, or exclusive mode. The exclusive mode guarantees that
* nobody else will be able to open this volume. UBI allows to have many volume
* readers and one writer at a time.
*
* If a static volume is being opened for the first time since boot, it will be
* checked by this function, which means it will be fully read and the CRC
* checksum of each logical eraseblock will be checked.
*
* This function returns volume descriptor in case of success and a negative
* error code in case of failure.
*/
struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
{
int err;
struct ubi_volume_desc *desc;
struct ubi_device *ubi;
struct ubi_volume *vol;
dbg_gen("open device %d, volume %d, mode %d", ubi_num, vol_id, mode);
if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
return ERR_PTR(-EINVAL);
if (mode != UBI_READONLY && mode != UBI_READWRITE &&
mode != UBI_EXCLUSIVE)
return ERR_PTR(-EINVAL);
/*
* First of all, we have to get the UBI device to prevent its removal.
*/
ubi = ubi_get_device(ubi_num);
if (!ubi)
return ERR_PTR(-ENODEV);
if (vol_id < 0 || vol_id >= ubi->vtbl_slots) {
err = -EINVAL;
goto out_put_ubi;
}
desc = kmalloc(sizeof(struct ubi_volume_desc), GFP_KERNEL);
if (!desc) {
err = -ENOMEM;
goto out_put_ubi;
}
err = -ENODEV;
if (!try_module_get(THIS_MODULE))
goto out_free;
spin_lock(&ubi->volumes_lock);
vol = ubi->volumes[vol_id];
if (!vol)
goto out_unlock;
err = -EBUSY;
switch (mode) {
case UBI_READONLY:
if (vol->exclusive)
goto out_unlock;
vol->readers += 1;
break;
case UBI_READWRITE:
if (vol->exclusive || vol->writers > 0)
goto out_unlock;
vol->writers += 1;
break;
case UBI_EXCLUSIVE:
if (vol->exclusive || vol->writers || vol->readers)
goto out_unlock;
vol->exclusive = 1;
break;
}
get_device(&vol->dev);
vol->ref_count += 1;
spin_unlock(&ubi->volumes_lock);
desc->vol = vol;
desc->mode = mode;
mutex_lock(&ubi->ckvol_mutex);
if (!vol->checked) {
/* This is the first open - check the volume */
err = ubi_check_volume(ubi, vol_id);
if (err < 0) {
mutex_unlock(&ubi->ckvol_mutex);
ubi_close_volume(desc);
return ERR_PTR(err);
}
if (err == 1) {
ubi_warn("volume %d on UBI device %d is corrupted",
vol_id, ubi->ubi_num);
vol->corrupted = 1;
}
vol->checked = 1;
}
mutex_unlock(&ubi->ckvol_mutex);
return desc;
out_unlock:
spin_unlock(&ubi->volumes_lock);
module_put(THIS_MODULE);
out_free:
kfree(desc);
out_put_ubi:
ubi_put_device(ubi);
dbg_err("cannot open device %d, volume %d, error %d",
ubi_num, vol_id, err);
return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(ubi_open_volume);
/**
* ubi_open_volume_nm - open UBI volume by name.
* @ubi_num: UBI device number
* @name: volume name
* @mode: open mode
*
* This function is similar to 'ubi_open_volume()', but opens a volume by name.
*/
struct ubi_volume_desc *ubi_open_volume_nm(int ubi_num, const char *name,
int mode)
{
int i, vol_id = -1, len;
struct ubi_device *ubi;
struct ubi_volume_desc *ret;
dbg_gen("open device %d, volume %s, mode %d", ubi_num, name, mode);
if (!name)
return ERR_PTR(-EINVAL);
len = strnlen(name, UBI_VOL_NAME_MAX + 1);
if (len > UBI_VOL_NAME_MAX)
return ERR_PTR(-EINVAL);
if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
return ERR_PTR(-EINVAL);
ubi = ubi_get_device(ubi_num);
if (!ubi)
return ERR_PTR(-ENODEV);
spin_lock(&ubi->volumes_lock);
/* Walk all volumes of this UBI device */
for (i = 0; i < ubi->vtbl_slots; i++) {
struct ubi_volume *vol = ubi->volumes[i];
if (vol && len == vol->name_len && !strcmp(name, vol->name)) {
vol_id = i;
break;
}
}
spin_unlock(&ubi->volumes_lock);
if (vol_id >= 0)
ret = ubi_open_volume(ubi_num, vol_id, mode);
else
ret = ERR_PTR(-ENODEV);
/*
* We should put the UBI device even in case of success, because
* 'ubi_open_volume()' took a reference as well.
*/
ubi_put_device(ubi);
return ret;
}
EXPORT_SYMBOL_GPL(ubi_open_volume_nm);
/**
* ubi_open_volume_path - open UBI volume by its character device node path.
* @pathname: volume character device node path
* @mode: open mode
*
* This function is similar to 'ubi_open_volume()', but opens a volume the path
* to its character device node.
*/
struct ubi_volume_desc *ubi_open_volume_path(const char *pathname, int mode)
{
int error, ubi_num, vol_id, mod;
struct inode *inode;
struct path path;
dbg_gen("open volume %s, mode %d", pathname, mode);
if (!pathname || !*pathname)
return ERR_PTR(-EINVAL);
error = kern_path(pathname, LOOKUP_FOLLOW, &path);
if (error)
return ERR_PTR(error);
inode = path.dentry->d_inode;
mod = inode->i_mode;
ubi_num = ubi_major2num(imajor(inode));
vol_id = iminor(inode) - 1;
path_put(&path);
if (!S_ISCHR(mod))
return ERR_PTR(-EINVAL);
if (vol_id >= 0 && ubi_num >= 0)
return ubi_open_volume(ubi_num, vol_id, mode);
return ERR_PTR(-ENODEV);
}
EXPORT_SYMBOL_GPL(ubi_open_volume_path);
/**
* ubi_close_volume - close UBI volume.
* @desc: volume descriptor
*/
void ubi_close_volume(struct ubi_volume_desc *desc)
{
struct ubi_volume *vol = desc->vol;
struct ubi_device *ubi = vol->ubi;
dbg_gen("close device %d, volume %d, mode %d",
ubi->ubi_num, vol->vol_id, desc->mode);
spin_lock(&ubi->volumes_lock);
switch (desc->mode) {
case UBI_READONLY:
vol->readers -= 1;
break;
case UBI_READWRITE:
vol->writers -= 1;
break;
case UBI_EXCLUSIVE:
vol->exclusive = 0;
}
vol->ref_count -= 1;
spin_unlock(&ubi->volumes_lock);
kfree(desc);
put_device(&vol->dev);
ubi_put_device(ubi);
module_put(THIS_MODULE);
}
EXPORT_SYMBOL_GPL(ubi_close_volume);
/**
* ubi_leb_read - read data.
* @desc: volume descriptor
* @lnum: logical eraseblock number to read from
* @buf: buffer where to store the read data
* @offset: offset within the logical eraseblock to read from
* @len: how many bytes to read
* @check: whether UBI has to check the read data's CRC or not.
*
* This function reads data from offset @offset of logical eraseblock @lnum and
* stores the data at @buf. When reading from static volumes, @check specifies
* whether the data has to be checked or not. If yes, the whole logical
* eraseblock will be read and its CRC checksum will be checked (i.e., the CRC
* checksum is per-eraseblock). So checking may substantially slow down the
* read speed. The @check argument is ignored for dynamic volumes.
*
* In case of success, this function returns zero. In case of failure, this
* function returns a negative error code.
*
* %-EBADMSG error code is returned:
* o for both static and dynamic volumes if MTD driver has detected a data
* integrity problem (unrecoverable ECC checksum mismatch in case of NAND);
* o for static volumes in case of data CRC mismatch.
*
* If the volume is damaged because of an interrupted update this function just
* returns immediately with %-EBADF error code.
*/
int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
int len, int check)
{
struct ubi_volume *vol = desc->vol;
struct ubi_device *ubi = vol->ubi;
int err, vol_id = vol->vol_id;
dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);
if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||
lnum >= vol->used_ebs || offset < 0 || len < 0 ||
offset + len > vol->usable_leb_size)
return -EINVAL;
if (vol->vol_type == UBI_STATIC_VOLUME) {
if (vol->used_ebs == 0)
/* Empty static UBI volume */
return 0;
if (lnum == vol->used_ebs - 1 &&
offset + len > vol->last_eb_bytes)
return -EINVAL;
}
if (vol->upd_marker)
return -EBADF;
if (len == 0)
return 0;
err = ubi_eba_read_leb(ubi, vol, lnum, buf, offset, len, check);
if (err && err == -EBADMSG && vol->vol_type == UBI_STATIC_VOLUME) {
ubi_warn("mark volume %d as corrupted", vol_id);
vol->corrupted = 1;
}
return err;
}
EXPORT_SYMBOL_GPL(ubi_leb_read);
/**
* ubi_leb_write - write data.
* @desc: volume descriptor
* @lnum: logical eraseblock number to write to
* @buf: data to write
* @offset: offset within the logical eraseblock where to write
* @len: how many bytes to write
* @dtype: expected data type
*
* This function writes @len bytes of data from @buf to offset @offset of
* logical eraseblock @lnum. The @dtype argument describes expected lifetime of
* the data.
*
* This function takes care of physical eraseblock write failures. If write to
* the physical eraseblock write operation fails, the logical eraseblock is
* re-mapped to another physical eraseblock, the data is recovered, and the
* write finishes. UBI has a pool of reserved physical eraseblocks for this.
*
* If all the data were successfully written, zero is returned. If an error
* occurred and UBI has not been able to recover from it, this function returns
* a negative error code. Note, in case of an error, it is possible that
* something was still written to the flash media, but that may be some
* garbage.
*
* If the volume is damaged because of an interrupted update this function just
* returns immediately with %-EBADF code.
*/
int ubi_leb_write(struct ubi_volume_desc *desc, int lnum, const void *buf,
int offset, int len, int dtype)
{
struct ubi_volume *vol = desc->vol;
struct ubi_device *ubi = vol->ubi;
int vol_id = vol->vol_id;
dbg_gen("write %d bytes to LEB %d:%d:%d", len, vol_id, lnum, offset);
if (vol_id < 0 || vol_id >= ubi->vtbl_slots)
return -EINVAL;
if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
return -EROFS;
if (lnum < 0 || lnum >= vol->reserved_pebs || offset < 0 || len < 0 ||
offset + len > vol->usable_leb_size ||
offset & (ubi->min_io_size - 1) || len & (ubi->min_io_size - 1))
return -EINVAL;
if (dtype != UBI_LONGTERM && dtype != UBI_SHORTTERM &&
dtype != UBI_UNKNOWN)
return -EINVAL;
if (vol->upd_marker)
return -EBADF;
if (len == 0)
return 0;
return ubi_eba_write_leb(ubi, vol, lnum, buf, offset, len, dtype);
}
EXPORT_SYMBOL_GPL(ubi_leb_write);
/*
* ubi_leb_change - change logical eraseblock atomically.
* @desc: volume descriptor
* @lnum: logical eraseblock number to change
* @buf: data to write
* @len: how many bytes to write
* @dtype: expected data type
*
* This function changes the contents of a logical eraseblock atomically. @buf
* has to contain new logical eraseblock data, and @len - the length of the
* data, which has to be aligned. The length may be shorter than the logical
* eraseblock size, ant the logical eraseblock may be appended to more times
* later on. This function guarantees that in case of an unclean reboot the old
* contents is preserved. Returns zero in case of success and a negative error
* code in case of failure.
*/
int ubi_leb_change(struct ubi_volume_desc *desc, int lnum, const void *buf,
int len, int dtype)
{
struct ubi_volume *vol = desc->vol;
struct ubi_device *ubi = vol->ubi;
int vol_id = vol->vol_id;
dbg_gen("atomically write %d bytes to LEB %d:%d", len, vol_id, lnum);
if (vol_id < 0 || vol_id >= ubi->vtbl_slots)
return -EINVAL;
if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
return -EROFS;
if (lnum < 0 || lnum >= vol->reserved_pebs || len < 0 ||
len > vol->usable_leb_size || len & (ubi->min_io_size - 1))
return -EINVAL;
if (dtype != UBI_LONGTERM && dtype != UBI_SHORTTERM &&
dtype != UBI_UNKNOWN)
return -EINVAL;
if (vol->upd_marker)
return -EBADF;
if (len == 0)
return 0;
return ubi_eba_atomic_leb_change(ubi, vol, lnum, buf, len, dtype);
}
EXPORT_SYMBOL_GPL(ubi_leb_change);
/**
* ubi_leb_erase - erase logical eraseblock.
* @desc: volume descriptor
* @lnum: logical eraseblock number
*
* This function un-maps logical eraseblock @lnum and synchronously erases the
* correspondent physical eraseblock. Returns zero in case of success and a
* negative error code in case of failure.
*
* If the volume is damaged because of an interrupted update this function just
* returns immediately with %-EBADF code.
*/
int ubi_leb_erase(struct ubi_volume_desc *desc, int lnum)
{
struct ubi_volume *vol = desc->vol;
struct ubi_device *ubi = vol->ubi;
int err;
dbg_gen("erase LEB %d:%d", vol->vol_id, lnum);
if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
return -EROFS;
if (lnum < 0 || lnum >= vol->reserved_pebs)
return -EINVAL;
if (vol->upd_marker)
return -EBADF;
err = ubi_eba_unmap_leb(ubi, vol, lnum);
if (err)
return err;
return ubi_wl_flush(ubi);
}
EXPORT_SYMBOL_GPL(ubi_leb_erase);
/**
* ubi_leb_unmap - un-map logical eraseblock.
* @desc: volume descriptor
* @lnum: logical eraseblock number
*
* This function un-maps logical eraseblock @lnum and schedules the
* corresponding physical eraseblock for erasure, so that it will eventually be
* physically erased in background. This operation is much faster than the
* erase operation.
*
* Unlike erase, the un-map operation does not guarantee that the logical
* eraseblock will contain all 0xFF bytes when UBI is initialized again. For
* example, if several logical eraseblocks are un-mapped, and an unclean reboot
* happens after this, the logical eraseblocks will not necessarily be
* un-mapped again when this MTD device is attached. They may actually be
* mapped to the same physical eraseblocks again. So, this function has to be
* used with care.
*
* In other words, when un-mapping a logical eraseblock, UBI does not store
* any information about this on the flash media, it just marks the logical
* eraseblock as "un-mapped" in RAM. If UBI is detached before the physical
* eraseblock is physically erased, it will be mapped again to the same logical
* eraseblock when the MTD device is attached again.
*
* The main and obvious use-case of this function is when the contents of a
* logical eraseblock has to be re-written. Then it is much more efficient to
* first un-map it, then write new data, rather than first erase it, then write
* new data. Note, once new data has been written to the logical eraseblock,
* UBI guarantees that the old contents has gone forever. In other words, if an
* unclean reboot happens after the logical eraseblock has been un-mapped and
* then written to, it will contain the last written data.
*
* This function returns zero in case of success and a negative error code in
* case of failure. If the volume is damaged because of an interrupted update
* this function just returns immediately with %-EBADF code.
*/
int ubi_leb_unmap(struct ubi_volume_desc *desc, int lnum)
{
struct ubi_volume *vol = desc->vol;
struct ubi_device *ubi = vol->ubi;
dbg_gen("unmap LEB %d:%d", vol->vol_id, lnum);
if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
return -EROFS;
if (lnum < 0 || lnum >= vol->reserved_pebs)
return -EINVAL;
if (vol->upd_marker)
return -EBADF;
return ubi_eba_unmap_leb(ubi, vol, lnum);
}
EXPORT_SYMBOL_GPL(ubi_leb_unmap);
/**
* ubi_leb_map - map logical eraseblock to a physical eraseblock.
* @desc: volume descriptor
* @lnum: logical eraseblock number
* @dtype: expected data type
*
* This function maps an un-mapped logical eraseblock @lnum to a physical
* eraseblock. This means, that after a successful invocation of this
* function the logical eraseblock @lnum will be empty (contain only %0xFF
* bytes) and be mapped to a physical eraseblock, even if an unclean reboot
* happens.
*
* This function returns zero in case of success, %-EBADF if the volume is
* damaged because of an interrupted update, %-EBADMSG if the logical
* eraseblock is already mapped, and other negative error codes in case of
* other failures.
*/
int ubi_leb_map(struct ubi_volume_desc *desc, int lnum, int dtype)
{
struct ubi_volume *vol = desc->vol;
struct ubi_device *ubi = vol->ubi;
dbg_gen("unmap LEB %d:%d", vol->vol_id, lnum);
if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
return -EROFS;
if (lnum < 0 || lnum >= vol->reserved_pebs)
return -EINVAL;
if (dtype != UBI_LONGTERM && dtype != UBI_SHORTTERM &&
dtype != UBI_UNKNOWN)
return -EINVAL;
if (vol->upd_marker)
return -EBADF;
if (vol->eba_tbl[lnum] >= 0)
return -EBADMSG;
return ubi_eba_write_leb(ubi, vol, lnum, NULL, 0, 0, dtype);
}
EXPORT_SYMBOL_GPL(ubi_leb_map);
/**
* ubi_is_mapped - check if logical eraseblock is mapped.
* @desc: volume descriptor
* @lnum: logical eraseblock number
*
* This function checks if logical eraseblock @lnum is mapped to a physical
* eraseblock. If a logical eraseblock is un-mapped, this does not necessarily
* mean it will still be un-mapped after the UBI device is re-attached. The
* logical eraseblock may become mapped to the physical eraseblock it was last
* mapped to.
*
* This function returns %1 if the LEB is mapped, %0 if not, and a negative
* error code in case of failure. If the volume is damaged because of an
* interrupted update this function just returns immediately with %-EBADF error
* code.
*/
int ubi_is_mapped(struct ubi_volume_desc *desc, int lnum)
{
struct ubi_volume *vol = desc->vol;
dbg_gen("test LEB %d:%d", vol->vol_id, lnum);
if (lnum < 0 || lnum >= vol->reserved_pebs)
return -EINVAL;
if (vol->upd_marker)
return -EBADF;
return vol->eba_tbl[lnum] >= 0;
}
EXPORT_SYMBOL_GPL(ubi_is_mapped);
/**
* ubi_sync - synchronize UBI device buffers.
* @ubi_num: UBI device to synchronize
*
* The underlying MTD device may cache data in hardware or in software. This
* function ensures the caches are flushed. Returns zero in case of success and
* a negative error code in case of failure.
*/
int ubi_sync(int ubi_num)
{
struct ubi_device *ubi;
ubi = ubi_get_device(ubi_num);
if (!ubi)
return -ENODEV;
if (ubi->mtd->sync)
ubi->mtd->sync(ubi->mtd);
ubi_put_device(ubi);
return 0;
}
EXPORT_SYMBOL_GPL(ubi_sync);
BLOCKING_NOTIFIER_HEAD(ubi_notifiers);
/**
* ubi_register_volume_notifier - register a volume notifier.
* @nb: the notifier description object
* @ignore_existing: if non-zero, do not send "added" notification for all
* already existing volumes
*
* This function registers a volume notifier, which means that
* 'nb->notifier_call()' will be invoked when an UBI volume is created,
* removed, re-sized, re-named, or updated. The first argument of the function
* is the notification type. The second argument is pointer to a
* &struct ubi_notification object which describes the notification event.
* Using UBI API from the volume notifier is prohibited.
*
* This function returns zero in case of success and a negative error code
* in case of failure.
*/
int ubi_register_volume_notifier(struct notifier_block *nb,
int ignore_existing)
{
int err;
err = blocking_notifier_chain_register(&ubi_notifiers, nb);
if (err != 0)
return err;
if (ignore_existing)
return 0;
/*
* We are going to walk all UBI devices and all volumes, and
* notify the user about existing volumes by the %UBI_VOLUME_ADDED
* event. We have to lock the @ubi_devices_mutex to make sure UBI
* devices do not disappear.
*/
mutex_lock(&ubi_devices_mutex);
ubi_enumerate_volumes(nb);
mutex_unlock(&ubi_devices_mutex);
return err;
}
EXPORT_SYMBOL_GPL(ubi_register_volume_notifier);
/**
* ubi_unregister_volume_notifier - unregister the volume notifier.
* @nb: the notifier description object
*
* This function unregisters volume notifier @nm and returns zero in case of
* success and a negative error code in case of failure.
*/
int ubi_unregister_volume_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_unregister(&ubi_notifiers, nb);
}
EXPORT_SYMBOL_GPL(ubi_unregister_volume_notifier);
