/*
   * 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->leb_start = ubi->leb_start;
  	di->min_io_size = ubi->min_io_size;
  	di->max_write_size = ubi->max_write_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 && mode != UBI_METAONLY)
  		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 ||
  		    vol->metaonly)
  			goto out_unlock;
  		vol->exclusive = 1;
  		break;
  
  	case UBI_METAONLY:
  		if (vol->metaonly || vol->exclusive)
  			goto out_unlock;
  		vol->metaonly = 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(ubi, "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);
  	ubi_err(ubi, "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 = d_backing_inode(path.dentry);
  	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;
  		break;
  	case UBI_METAONLY:
  		vol->metaonly = 0;
  		break;
  	}
  	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);
  
  /**
   * leb_read_sanity_check - does sanity checks on read requests.
   * @desc: volume descriptor
   * @lnum: logical eraseblock number to read from
   * @offset: offset within the logical eraseblock to read from
   * @len: how many bytes to read
   *
   * This function is used by ubi_leb_read() and ubi_leb_read_sg()
   * to perform sanity checks.
   */
  static int leb_read_sanity_check(struct ubi_volume_desc *desc, int lnum,
  				 int offset, int len)
  {
  	struct ubi_volume *vol = desc->vol;
  	struct ubi_device *ubi = vol->ubi;
  	int vol_id = vol->vol_id;
  
  	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;
  
  	return 0;
  }
  
  /**
   * 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);
  
  	err = leb_read_sanity_check(desc, lnum, offset, len);
  	if (err < 0)
  		return err;
  
  	if (len == 0)
  		return 0;
  
  	err = ubi_eba_read_leb(ubi, vol, lnum, buf, offset, len, check);
  	if (err && mtd_is_eccerr(err) && vol->vol_type == UBI_STATIC_VOLUME) {
  		ubi_warn(ubi, "mark volume %d as corrupted", vol_id);
  		vol->corrupted = 1;
  	}
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(ubi_leb_read);
  
  
  /**
   * ubi_leb_read_sg - read data into a scatter gather list.
   * @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 works exactly like ubi_leb_read_sg(). But instead of
   * storing the read data into a buffer it writes to an UBI scatter gather
   * list.
   */
  int ubi_leb_read_sg(struct ubi_volume_desc *desc, int lnum, struct ubi_sgl *sgl,
  		    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);
  
  	err = leb_read_sanity_check(desc, lnum, offset, len);
  	if (err < 0)
  		return err;
  
  	if (len == 0)
  		return 0;
  
  	err = ubi_eba_read_leb_sg(ubi, vol, sgl, lnum, offset, len, check);
  	if (err && mtd_is_eccerr(err) && vol->vol_type == UBI_STATIC_VOLUME) {
  		ubi_warn(ubi, "mark volume %d as corrupted", vol_id);
  		vol->corrupted = 1;
  	}
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(ubi_leb_read_sg);
  
  /**
   * 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
   *
   * This function writes @len bytes of data from @buf to offset @offset of
   * logical eraseblock @lnum.
   *
   * 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)
  {
  	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 (vol->upd_marker)
  		return -EBADF;
  
  	if (len == 0)
  		return 0;
  
  	return ubi_eba_write_leb(ubi, vol, lnum, buf, offset, len);
  }
  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
   *
   * 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)
  {
  	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 (vol->upd_marker)
  		return -EBADF;
  
  	if (len == 0)
  		return 0;
  
  	return ubi_eba_atomic_leb_change(ubi, vol, lnum, buf, len);
  }
  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, vol->vol_id, lnum);
  }
  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
   *
   * 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)
  {
  	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;
  
  	if (vol->eba_tbl[lnum] >= 0)
  		return -EBADMSG;
  
  	return ubi_eba_write_leb(ubi, vol, lnum, NULL, 0, 0);
  }
  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;
  
  	mtd_sync(ubi->mtd);
  	ubi_put_device(ubi);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(ubi_sync);
  
  /**
   * ubi_flush - flush UBI work queue.
   * @ubi_num: UBI device to flush work queue
   * @vol_id: volume id to flush for
   * @lnum: logical eraseblock number to flush for
   *
   * This function executes all pending works for a particular volume id / logical
   * eraseblock number pair. If either value is set to %UBI_ALL, then it acts as
   * a wildcard for all of the corresponding volume numbers or logical
   * eraseblock numbers. It returns zero in case of success and a negative error
   * code in case of failure.
   */
  int ubi_flush(int ubi_num, int vol_id, int lnum)
  {
  	struct ubi_device *ubi;
  	int err = 0;
  
  	ubi = ubi_get_device(ubi_num);
  	if (!ubi)
  		return -ENODEV;
  
  	err = ubi_wl_flush(ubi, vol_id, lnum);
  	ubi_put_device(ubi);
  	return err;
  }
  EXPORT_SYMBOL_GPL(ubi_flush);
  
  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);