/*
   * Copyright (c) International Business Machines Corp., 2006
   * Copyright (c) Nokia Corporation, 2006, 2007
   *
   * 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)
   */
  
  #ifndef __UBI_UBI_H__
  #define __UBI_UBI_H__
  
  #include <linux/init.h>
  #include <linux/types.h>
  #include <linux/list.h>
  #include <linux/rbtree.h>
  #include <linux/sched.h>
  #include <linux/wait.h>
  #include <linux/mutex.h>
  #include <linux/rwsem.h>
  #include <linux/spinlock.h>
  #include <linux/fs.h>
  #include <linux/cdev.h>
  #include <linux/device.h>

  #include <linux/slab.h>

  #include <linux/string.h>

  #include <linux/vmalloc.h>

  #include <linux/notifier.h>

  #include <linux/mtd/mtd.h>

  #include <linux/mtd/ubi.h>

  #include <asm/pgtable.h>

  #include "ubi-media.h"

  #include "scan.h"

  
  /* Maximum number of supported UBI devices */
  #define UBI_MAX_DEVICES 32
  
  /* UBI name used for character devices, sysfs, etc */
  #define UBI_NAME_STR "ubi"
  
  /* Normal UBI messages */
  #define ubi_msg(fmt, ...) printk(KERN_NOTICE "UBI: " fmt "
  ", ##__VA_ARGS__)
  /* UBI warning messages */
  #define ubi_warn(fmt, ...) printk(KERN_WARNING "UBI warning: %s: " fmt "
  ", \

  				  __func__, ##__VA_ARGS__)

  /* UBI error messages */
  #define ubi_err(fmt, ...) printk(KERN_ERR "UBI error: %s: " fmt "
  ", \

  				 __func__, ##__VA_ARGS__)

  
  /* Lowest number PEBs reserved for bad PEB handling */
  #define MIN_RESEVED_PEBS 2
  
  /* Background thread name pattern */
  #define UBI_BGT_NAME_PATTERN "ubi_bgt%dd"
  
  /* This marker in the EBA table means that the LEB is um-mapped */
  #define UBI_LEB_UNMAPPED -1
  
  /*
   * In case of errors, UBI tries to repeat the operation several times before
   * returning error. The below constant defines how many times UBI re-tries.
   */
  #define UBI_IO_RETRIES 3
  
  /*

   * Length of the protection queue. The length is effectively equivalent to the
   * number of (global) erase cycles PEBs are protected from the wear-leveling
   * worker.
   */
  #define UBI_PROT_QUEUE_LEN 10
  
  /*

   * Error codes returned by the I/O sub-system.

   *

   * UBI_IO_FF: the read region of flash contains only 0xFFs

   * UBI_IO_FF_BITFLIPS: the same as %UBI_IO_FF, but also also there was a data
   *                     integrity error reported by the MTD driver
   *                     (uncorrectable ECC error in case of NAND)

   * UBI_IO_BAD_HDR: the EC or VID header is corrupted (bad magic or CRC)

   * UBI_IO_BAD_HDR_EBADMSG: the same as %UBI_IO_BAD_HDR, but also there was a
   *                         data integrity error reported by the MTD driver
   *                         (uncorrectable ECC error in case of NAND)

   * UBI_IO_BITFLIPS: bit-flips were detected and corrected

   *
   * Note, it is probably better to have bit-flip and ebadmsg as flags which can
   * be or'ed with other error code. But this is a big change because there are
   * may callers, so it does not worth the risk of introducing a bug

   */
  enum {

  	UBI_IO_FF = 1,

  	UBI_IO_FF_BITFLIPS,

  	UBI_IO_BAD_HDR,

  	UBI_IO_BAD_HDR_EBADMSG,

  	UBI_IO_BITFLIPS,

  };

  /*
   * Return codes of the 'ubi_eba_copy_leb()' function.
   *
   * MOVE_CANCEL_RACE: canceled because the volume is being deleted, the source
   *                   PEB was put meanwhile, or there is I/O on the source PEB

   * MOVE_SOURCE_RD_ERR: canceled because there was a read error from the source
   *                     PEB
   * MOVE_TARGET_RD_ERR: canceled because there was a read error from the target
   *                     PEB

   * MOVE_TARGET_WR_ERR: canceled because there was a write error to the target
   *                     PEB
   * MOVE_CANCEL_BITFLIPS: canceled because a bit-flip was detected in the
   *                       target PEB

   * MOVE_RETRY: retry scrubbing the PEB

   */
  enum {
  	MOVE_CANCEL_RACE = 1,

  	MOVE_SOURCE_RD_ERR,
  	MOVE_TARGET_RD_ERR,

  	MOVE_TARGET_WR_ERR,
  	MOVE_CANCEL_BITFLIPS,

  	MOVE_RETRY,

  };

  /**

   * struct ubi_wl_entry - wear-leveling entry.

   * @u.rb: link in the corresponding (free/used) RB-tree

   * @u.list: link in the protection queue

   * @ec: erase counter
   * @pnum: physical eraseblock number
   *

   * This data structure is used in the WL sub-system. Each physical eraseblock
   * has a corresponding &struct wl_entry object which may be kept in different
   * RB-trees. See WL sub-system for details.

   */
  struct ubi_wl_entry {

  	union {
  		struct rb_node rb;

  		struct list_head list;

  	} u;

  	int ec;
  	int pnum;
  };
  
  /**

   * struct ubi_ltree_entry - an entry in the lock tree.
   * @rb: links RB-tree nodes
   * @vol_id: volume ID of the locked logical eraseblock
   * @lnum: locked logical eraseblock number
   * @users: how many tasks are using this logical eraseblock or wait for it
   * @mutex: read/write mutex to implement read/write access serialization to
   *         the (@vol_id, @lnum) logical eraseblock
   *

   * This data structure is used in the EBA sub-system to implement per-LEB
   * locking. When a logical eraseblock is being locked - corresponding

   * &struct ubi_ltree_entry object is inserted to the lock tree (@ubi->ltree).

   * See EBA sub-system for details.

   */
  struct ubi_ltree_entry {
  	struct rb_node rb;
  	int vol_id;
  	int lnum;
  	int users;
  	struct rw_semaphore mutex;
  };

  /**
   * struct ubi_rename_entry - volume re-name description data structure.
   * @new_name_len: new volume name length
   * @new_name: new volume name
   * @remove: if not zero, this volume should be removed, not re-named
   * @desc: descriptor of the volume
   * @list: links re-name entries into a list
   *
   * This data structure is utilized in the multiple volume re-name code. Namely,
   * UBI first creates a list of &struct ubi_rename_entry objects from the
   * &struct ubi_rnvol_req request object, and then utilizes this list to do all
   * the job.
   */
  struct ubi_rename_entry {
  	int new_name_len;
  	char new_name[UBI_VOL_NAME_MAX + 1];
  	int remove;
  	struct ubi_volume_desc *desc;
  	struct list_head list;
  };

  struct ubi_volume_desc;
  
  /**
   * struct ubi_volume - UBI volume description data structure.
   * @dev: device object to make use of the the Linux device model
   * @cdev: character device object to create character device
   * @ubi: reference to the UBI device description object
   * @vol_id: volume ID

   * @ref_count: volume reference count

   * @readers: number of users holding this volume in read-only mode
   * @writers: number of users holding this volume in read-write mode
   * @exclusive: whether somebody holds this volume in exclusive mode

   *
   * @reserved_pebs: how many physical eraseblocks are reserved for this volume
   * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
   * @usable_leb_size: logical eraseblock size without padding
   * @used_ebs: how many logical eraseblocks in this volume contain data
   * @last_eb_bytes: how many bytes are stored in the last logical eraseblock
   * @used_bytes: how many bytes of data this volume contains

   * @alignment: volume alignment
   * @data_pad: how many bytes are not used at the end of physical eraseblocks to

   *            satisfy the requested alignment

   * @name_len: volume name length
   * @name: volume name
   *

   * @upd_ebs: how many eraseblocks are expected to be updated

   * @ch_lnum: LEB number which is being changing by the atomic LEB change
   *           operation
   * @ch_dtype: data persistency type which is being changing by the atomic LEB
   *            change operation
   * @upd_bytes: how many bytes are expected to be received for volume update or
   *             atomic LEB change
   * @upd_received: how many bytes were already received for volume update or
   *                atomic LEB change
   * @upd_buf: update buffer which is used to collect update data or data for
   *           atomic LEB change

   *
   * @eba_tbl: EBA table of this volume (LEB->PEB mapping)

   * @checked: %1 if this static volume was checked
   * @corrupted: %1 if the volume is corrupted (static volumes only)
   * @upd_marker: %1 if the update marker is set for this volume
   * @updating: %1 if the volume is being updated

   * @changing_leb: %1 if the atomic LEB change ioctl command is in progress

   * @direct_writes: %1 if direct writes are enabled for this volume

   *

   * The @corrupted field indicates that the volume's contents is corrupted.
   * Since UBI protects only static volumes, this field is not relevant to
   * dynamic volumes - it is user's responsibility to assure their data
   * integrity.
   *
   * The @upd_marker flag indicates that this volume is either being updated at
   * the moment or is damaged because of an unclean reboot.
   */
  struct ubi_volume {
  	struct device dev;
  	struct cdev cdev;
  	struct ubi_device *ubi;
  	int vol_id;

  	int ref_count;

  	int readers;
  	int writers;
  	int exclusive;

  
  	int reserved_pebs;
  	int vol_type;
  	int usable_leb_size;
  	int used_ebs;
  	int last_eb_bytes;
  	long long used_bytes;

  	int alignment;
  	int data_pad;
  	int name_len;

  	char name[UBI_VOL_NAME_MAX + 1];

  	int upd_ebs;

  	int ch_lnum;
  	int ch_dtype;

  	long long upd_bytes;
  	long long upd_received;
  	void *upd_buf;
  
  	int *eba_tbl;

  	unsigned int checked:1;
  	unsigned int corrupted:1;
  	unsigned int upd_marker:1;
  	unsigned int updating:1;
  	unsigned int changing_leb:1;

  	unsigned int direct_writes:1;

  };
  
  /**

   * struct ubi_volume_desc - UBI volume descriptor returned when it is opened.

   * @vol: reference to the corresponding volume description object
   * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, or %UBI_EXCLUSIVE)
   */
  struct ubi_volume_desc {
  	struct ubi_volume *vol;
  	int mode;
  };
  
  struct ubi_wl_entry;
  
  /**
   * struct ubi_device - UBI device description structure

   * @dev: UBI device object to use the the Linux device model

   * @cdev: character device object to create character device
   * @ubi_num: UBI device number
   * @ubi_name: UBI device name

   * @vol_count: number of volumes in this UBI device
   * @volumes: volumes of this UBI device
   * @volumes_lock: protects @volumes, @rsvd_pebs, @avail_pebs, beb_rsvd_pebs,

   *                @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count,
   *                @vol->readers, @vol->writers, @vol->exclusive,
   *                @vol->ref_count, @vol->mapping and @vol->eba_tbl.

   * @ref_count: count of references on the UBI device

   * @image_seq: image sequence number recorded on EC headers

   *
   * @rsvd_pebs: count of reserved physical eraseblocks
   * @avail_pebs: count of available physical eraseblocks
   * @beb_rsvd_pebs: how many physical eraseblocks are reserved for bad PEB

   *                 handling

   * @beb_rsvd_level: normal level of PEBs reserved for bad PEB handling
   *

   * @autoresize_vol_id: ID of the volume which has to be auto-resized at the end

   *                     of UBI initialization

   * @vtbl_slots: how many slots are available in the volume table
   * @vtbl_size: size of the volume table in bytes
   * @vtbl: in-RAM volume table copy

   * @device_mutex: protects on-flash volume table and serializes volume
   *                creation, deletion, update, re-size, re-name and set
   *                property

   *
   * @max_ec: current highest erase counter value
   * @mean_ec: current mean erase counter value
   *

   * @global_sqnum: global sequence number

   * @ltree_lock: protects the lock tree and @global_sqnum
   * @ltree: the lock tree

   * @alc_mutex: serializes "atomic LEB change" operations

   *
   * @used: RB-tree of used physical eraseblocks

   * @erroneous: RB-tree of erroneous used physical eraseblocks

   * @free: RB-tree of free physical eraseblocks
   * @scrub: RB-tree of physical eraseblocks which need scrubbing

   * @pq: protection queue (contain physical eraseblocks which are temporarily
   *      protected from the wear-leveling worker)
   * @pq_head: protection queue head
   * @wl_lock: protects the @used, @free, @pq, @pq_head, @lookuptbl, @move_from,

   *	     @move_to, @move_to_put @erase_pending, @wl_scheduled, @works,
   *	     @erroneous, and @erroneous_peb_count fields

   * @move_mutex: serializes eraseblock moves

   * @work_sem: synchronizes the WL worker with use tasks

   * @wl_scheduled: non-zero if the wear-leveling was scheduled
   * @lookuptbl: a table to quickly find a &struct ubi_wl_entry object for any

   *             physical eraseblock

   * @move_from: physical eraseblock from where the data is being moved
   * @move_to: physical eraseblock where the data is being moved to

   * @move_to_put: if the "to" PEB was put
   * @works: list of pending works
   * @works_count: count of pending works
   * @bgt_thread: background thread description object
   * @thread_enabled: if the background thread is enabled
   * @bgt_name: background thread name
   *
   * @flash_size: underlying MTD device size (in bytes)
   * @peb_count: count of physical eraseblocks on the MTD device
   * @peb_size: physical eraseblock size
   * @bad_peb_count: count of bad physical eraseblocks
   * @good_peb_count: count of good physical eraseblocks

   * @corr_peb_count: count of corrupted physical eraseblocks (preserved and not
   *                  used by UBI)

   * @erroneous_peb_count: count of erroneous physical eraseblocks in @erroneous
   * @max_erroneous: maximum allowed amount of erroneous physical eraseblocks

   * @min_io_size: minimal input/output unit size of the underlying MTD device
   * @hdrs_min_io_size: minimal I/O unit size used for VID and EC headers
   * @ro_mode: if the UBI device is in read-only mode
   * @leb_size: logical eraseblock size
   * @leb_start: starting offset of logical eraseblocks within physical

   *             eraseblocks

   * @ec_hdr_alsize: size of the EC header aligned to @hdrs_min_io_size
   * @vid_hdr_alsize: size of the VID header aligned to @hdrs_min_io_size
   * @vid_hdr_offset: starting offset of the volume identifier header (might be

   *                  unaligned)

   * @vid_hdr_aloffset: starting offset of the VID header aligned to
   * @hdrs_min_io_size
   * @vid_hdr_shift: contains @vid_hdr_offset - @vid_hdr_aloffset
   * @bad_allowed: whether the MTD device admits of bad physical eraseblocks or

   *               not

   * @nor_flash: non-zero if working on top of NOR flash

   * @max_write_size: maximum amount of bytes the underlying flash can write at a
   *                  time (MTD write buffer size)

   * @mtd: MTD device descriptor

   *
   * @peb_buf1: a buffer of PEB size used for different purposes
   * @peb_buf2: another buffer of PEB size used for different purposes

   * @buf_mutex: protects @peb_buf1 and @peb_buf2

   * @ckvol_mutex: serializes static volume checking when opening

   *
   * @dbg: debugging information for this UBI device

   */
  struct ubi_device {
  	struct cdev cdev;
  	struct device dev;
  	int ubi_num;
  	char ubi_name[sizeof(UBI_NAME_STR)+5];

  	int vol_count;
  	struct ubi_volume *volumes[UBI_MAX_VOLUMES+UBI_INT_VOL_COUNT];
  	spinlock_t volumes_lock;

  	int ref_count;

  	int image_seq;

  
  	int rsvd_pebs;
  	int avail_pebs;
  	int beb_rsvd_pebs;
  	int beb_rsvd_level;

  	int autoresize_vol_id;

  	int vtbl_slots;
  	int vtbl_size;
  	struct ubi_vtbl_record *vtbl;

  	struct mutex device_mutex;

  
  	int max_ec;

  	/* Note, mean_ec is not updated run-time - should be fixed */

  	int mean_ec;

  	/* EBA sub-system's stuff */

  	unsigned long long global_sqnum;
  	spinlock_t ltree_lock;
  	struct rb_root ltree;

  	struct mutex alc_mutex;

  	/* Wear-leveling sub-system's stuff */

  	struct rb_root used;

  	struct rb_root erroneous;

  	struct rb_root free;
  	struct rb_root scrub;

  	struct list_head pq[UBI_PROT_QUEUE_LEN];
  	int pq_head;

  	spinlock_t wl_lock;

  	struct mutex move_mutex;

  	struct rw_semaphore work_sem;

  	int wl_scheduled;
  	struct ubi_wl_entry **lookuptbl;

  	struct ubi_wl_entry *move_from;
  	struct ubi_wl_entry *move_to;

  	int move_to_put;
  	struct list_head works;
  	int works_count;
  	struct task_struct *bgt_thread;
  	int thread_enabled;
  	char bgt_name[sizeof(UBI_BGT_NAME_PATTERN)+2];

  	/* I/O sub-system's stuff */

  	long long flash_size;
  	int peb_count;
  	int peb_size;
  	int bad_peb_count;
  	int good_peb_count;

  	int corr_peb_count;

  	int erroneous_peb_count;
  	int max_erroneous;

  	int min_io_size;
  	int hdrs_min_io_size;
  	int ro_mode;
  	int leb_size;
  	int leb_start;
  	int ec_hdr_alsize;
  	int vid_hdr_alsize;
  	int vid_hdr_offset;
  	int vid_hdr_aloffset;
  	int vid_hdr_shift;

  	unsigned int bad_allowed:1;
  	unsigned int nor_flash:1;

  	int max_write_size;

  	struct mtd_info *mtd;

  
  	void *peb_buf1;
  	void *peb_buf2;
  	struct mutex buf_mutex;

  	struct mutex ckvol_mutex;

  
  	struct ubi_debug_info *dbg;

  };

  #include "debug.h"

  extern struct kmem_cache *ubi_wl_entry_slab;

  extern const struct file_operations ubi_ctrl_cdev_operations;
  extern const struct file_operations ubi_cdev_operations;
  extern const struct file_operations ubi_vol_cdev_operations;

  extern struct class *ubi_class;

  extern struct mutex ubi_devices_mutex;

  extern struct blocking_notifier_head ubi_notifiers;

  
  /* vtbl.c */
  int ubi_change_vtbl_record(struct ubi_device *ubi, int idx,
  			   struct ubi_vtbl_record *vtbl_rec);

  int ubi_vtbl_rename_volumes(struct ubi_device *ubi,
  			    struct list_head *rename_list);

  int ubi_read_volume_table(struct ubi_device *ubi, struct ubi_scan_info *si);
  
  /* vmt.c */
  int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req);

  int ubi_remove_volume(struct ubi_volume_desc *desc, int no_vtbl);

  int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs);

  int ubi_rename_volumes(struct ubi_device *ubi, struct list_head *rename_list);

  int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol);
  void ubi_free_volume(struct ubi_device *ubi, struct ubi_volume *vol);

  
  /* upd.c */

  int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
  		     long long bytes);
  int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,

  			 const void __user *buf, int count);

  int ubi_start_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
  			 const struct ubi_leb_change_req *req);
  int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
  			     const void __user *buf, int count);

  
  /* misc.c */

  int ubi_calc_data_len(const struct ubi_device *ubi, const void *buf,
  		      int length);

  int ubi_check_volume(struct ubi_device *ubi, int vol_id);
  void ubi_calculate_reserved(struct ubi_device *ubi);

  int ubi_check_pattern(const void *buf, uint8_t patt, int size);

  /* eba.c */

  int ubi_eba_unmap_leb(struct ubi_device *ubi, struct ubi_volume *vol,
  		      int lnum);
  int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
  		     void *buf, int offset, int len, int check);
  int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,

  		      const void *buf, int offset, int len, int dtype);

  int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
  			 int lnum, const void *buf, int len, int dtype,

  			 int used_ebs);

  int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
  			      int lnum, const void *buf, int len, int dtype);

  int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
  		     struct ubi_vid_hdr *vid_hdr);
  int ubi_eba_init_scan(struct ubi_device *ubi, struct ubi_scan_info *si);

  
  /* wl.c */
  int ubi_wl_get_peb(struct ubi_device *ubi, int dtype);
  int ubi_wl_put_peb(struct ubi_device *ubi, int pnum, int torture);
  int ubi_wl_flush(struct ubi_device *ubi);
  int ubi_wl_scrub_peb(struct ubi_device *ubi, int pnum);
  int ubi_wl_init_scan(struct ubi_device *ubi, struct ubi_scan_info *si);
  void ubi_wl_close(struct ubi_device *ubi);

  int ubi_thread(void *u);

  
  /* io.c */
  int ubi_io_read(const struct ubi_device *ubi, void *buf, int pnum, int offset,
  		int len);

  int ubi_io_write(struct ubi_device *ubi, const void *buf, int pnum, int offset,
  		 int len);
  int ubi_io_sync_erase(struct ubi_device *ubi, int pnum, int torture);

  int ubi_io_is_bad(const struct ubi_device *ubi, int pnum);
  int ubi_io_mark_bad(const struct ubi_device *ubi, int pnum);

  int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,

  		       struct ubi_ec_hdr *ec_hdr, int verbose);

  int ubi_io_write_ec_hdr(struct ubi_device *ubi, int pnum,

  			struct ubi_ec_hdr *ec_hdr);

  int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,

  			struct ubi_vid_hdr *vid_hdr, int verbose);

  int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,

  			 struct ubi_vid_hdr *vid_hdr);

  /* build.c */

  int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset);

  int ubi_detach_mtd_dev(int ubi_num, int anyway);

  struct ubi_device *ubi_get_device(int ubi_num);
  void ubi_put_device(struct ubi_device *ubi);
  struct ubi_device *ubi_get_by_major(int major);
  int ubi_major2num(int major);

  int ubi_volume_notify(struct ubi_device *ubi, struct ubi_volume *vol,
  		      int ntype);
  int ubi_notify_all(struct ubi_device *ubi, int ntype,
  		   struct notifier_block *nb);
  int ubi_enumerate_volumes(struct notifier_block *nb);
  
  /* kapi.c */
  void ubi_do_get_device_info(struct ubi_device *ubi, struct ubi_device_info *di);
  void ubi_do_get_volume_info(struct ubi_device *ubi, struct ubi_volume *vol,
  			    struct ubi_volume_info *vi);

  /*
   * ubi_rb_for_each_entry - walk an RB-tree.

   * @rb: a pointer to type 'struct rb_node' to use as a loop counter

   * @pos: a pointer to RB-tree entry type to use as a loop counter
   * @root: RB-tree's root
   * @member: the name of the 'struct rb_node' within the RB-tree entry
   */
  #define ubi_rb_for_each_entry(rb, pos, root, member)                         \
  	for (rb = rb_first(root),                                            \
  	     pos = (rb ? container_of(rb, typeof(*pos), member) : NULL);     \
  	     rb;                                                             \

  	     rb = rb_next(rb),                                               \
  	     pos = (rb ? container_of(rb, typeof(*pos), member) : NULL))

  
  /**
   * ubi_zalloc_vid_hdr - allocate a volume identifier header object.
   * @ubi: UBI device description object

   * @gfp_flags: GFP flags to allocate with

   *
   * This function returns a pointer to the newly allocated and zero-filled
   * volume identifier header object in case of success and %NULL in case of
   * failure.
   */

  static inline struct ubi_vid_hdr *
  ubi_zalloc_vid_hdr(const struct ubi_device *ubi, gfp_t gfp_flags)

  {
  	void *vid_hdr;

  	vid_hdr = kzalloc(ubi->vid_hdr_alsize, gfp_flags);

  	if (!vid_hdr)
  		return NULL;
  
  	/*
  	 * VID headers may be stored at un-aligned flash offsets, so we shift
  	 * the pointer.
  	 */
  	return vid_hdr + ubi->vid_hdr_shift;
  }
  
  /**
   * ubi_free_vid_hdr - free a volume identifier header object.
   * @ubi: UBI device description object
   * @vid_hdr: the object to free
   */
  static inline void ubi_free_vid_hdr(const struct ubi_device *ubi,
  				    struct ubi_vid_hdr *vid_hdr)
  {
  	void *p = vid_hdr;
  
  	if (!p)
  		return;
  
  	kfree(p - ubi->vid_hdr_shift);
  }
  
  /*
   * This function is equivalent to 'ubi_io_read()', but @offset is relative to
   * the beginning of the logical eraseblock, not to the beginning of the
   * physical eraseblock.
   */
  static inline int ubi_io_read_data(const struct ubi_device *ubi, void *buf,
  				   int pnum, int offset, int len)
  {
  	ubi_assert(offset >= 0);
  	return ubi_io_read(ubi, buf, pnum, offset + ubi->leb_start, len);
  }
  
  /*
   * This function is equivalent to 'ubi_io_write()', but @offset is relative to
   * the beginning of the logical eraseblock, not to the beginning of the
   * physical eraseblock.
   */

  static inline int ubi_io_write_data(struct ubi_device *ubi, const void *buf,

  				    int pnum, int offset, int len)
  {
  	ubi_assert(offset >= 0);
  	return ubi_io_write(ubi, buf, pnum, offset + ubi->leb_start, len);
  }
  
  /**
   * ubi_ro_mode - switch to read-only mode.
   * @ubi: UBI device description object
   */
  static inline void ubi_ro_mode(struct ubi_device *ubi)
  {

  	if (!ubi->ro_mode) {
  		ubi->ro_mode = 1;
  		ubi_warn("switch to read-only mode");

  		ubi_dbg_dump_stack();

  	}

  }
  
  /**
   * vol_id2idx - get table index by volume ID.
   * @ubi: UBI device description object
   * @vol_id: volume ID
   */
  static inline int vol_id2idx(const struct ubi_device *ubi, int vol_id)
  {
  	if (vol_id >= UBI_INTERNAL_VOL_START)
  		return vol_id - UBI_INTERNAL_VOL_START + ubi->vtbl_slots;
  	else
  		return vol_id;
  }
  
  /**
   * idx2vol_id - get volume ID by table index.
   * @ubi: UBI device description object
   * @idx: table index
   */
  static inline int idx2vol_id(const struct ubi_device *ubi, int idx)
  {
  	if (idx >= ubi->vtbl_slots)
  		return idx - ubi->vtbl_slots + UBI_INTERNAL_VOL_START;
  	else
  		return idx;
  }
  
  #endif /* !__UBI_UBI_H__ */