linux/fs/ubifs/log.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * Authors: Artem Bityutskiy (Битюцкий Артём)
 *          Adrian Hunter
 */

/*
 * This file is a part of UBIFS journal implementation and contains various
 * functions which manipulate the log. The log is a fixed area on the flash
 * which does not contain any data but refers to buds. The log is a part of the
 * journal.
 */

#include "ubifs.h"

static int dbg_check_bud_bytes(struct ubifs_info *c);

/**
 * ubifs_search_bud - search bud LEB.
 * @c: UBIFS file-system description object
 * @lnum: logical eraseblock number to search
 *
 * This function searches bud LEB @lnum. Returns bud description object in case
 * of success and %NULL if there is no bud with this LEB number.
 */
struct ubifs_bud *ubifs_search_bud(struct ubifs_info *c, int lnum)
{ … }

/**
 * ubifs_get_wbuf - get the wbuf associated with a LEB, if there is one.
 * @c: UBIFS file-system description object
 * @lnum: logical eraseblock number to search
 *
 * This functions returns the wbuf for @lnum or %NULL if there is not one.
 */
struct ubifs_wbuf *ubifs_get_wbuf(struct ubifs_info *c, int lnum)
{ … }

/**
 * empty_log_bytes - calculate amount of empty space in the log.
 * @c: UBIFS file-system description object
 */
static inline long long empty_log_bytes(const struct ubifs_info *c)
{ … }

/**
 * ubifs_add_bud - add bud LEB to the tree of buds and its journal head list.
 * @c: UBIFS file-system description object
 * @bud: the bud to add
 */
void ubifs_add_bud(struct ubifs_info *c, struct ubifs_bud *bud)
{ … }

/**
 * ubifs_add_bud_to_log - add a new bud to the log.
 * @c: UBIFS file-system description object
 * @jhead: journal head the bud belongs to
 * @lnum: LEB number of the bud
 * @offs: starting offset of the bud
 *
 * This function writes a reference node for the new bud LEB @lnum to the log,
 * and adds it to the buds trees. It also makes sure that log size does not
 * exceed the 'c->max_bud_bytes' limit. Returns zero in case of success,
 * %-EAGAIN if commit is required, and a negative error code in case of
 * failure.
 */
int ubifs_add_bud_to_log(struct ubifs_info *c, int jhead, int lnum, int offs)
{ … }

/**
 * remove_buds - remove used buds.
 * @c: UBIFS file-system description object
 *
 * This function removes use buds from the buds tree. It does not remove the
 * buds which are pointed to by journal heads.
 */
static void remove_buds(struct ubifs_info *c)
{ … }

/**
 * ubifs_log_start_commit - start commit.
 * @c: UBIFS file-system description object
 * @ltail_lnum: return new log tail LEB number
 *
 * The commit operation starts with writing "commit start" node to the log and
 * reference nodes for all journal heads which will define new journal after
 * the commit has been finished. The commit start and reference nodes are
 * written in one go to the nearest empty log LEB (hence, when commit is
 * finished UBIFS may safely unmap all the previous log LEBs). This function
 * returns zero in case of success and a negative error code in case of
 * failure.
 */
int ubifs_log_start_commit(struct ubifs_info *c, int *ltail_lnum)
{ … }

/**
 * ubifs_log_end_commit - end commit.
 * @c: UBIFS file-system description object
 * @ltail_lnum: new log tail LEB number
 *
 * This function is called on when the commit operation was finished. It
 * moves log tail to new position and updates the master node so that it stores
 * the new log tail LEB number. Returns zero in case of success and a negative
 * error code in case of failure.
 */
int ubifs_log_end_commit(struct ubifs_info *c, int ltail_lnum)
{ … }

/**
 * ubifs_log_post_commit - things to do after commit is completed.
 * @c: UBIFS file-system description object
 * @old_ltail_lnum: old log tail LEB number
 *
 * Release buds only after commit is completed, because they must be unchanged
 * if recovery is needed.
 *
 * Unmap log LEBs only after commit is completed, because they may be needed for
 * recovery.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_log_post_commit(struct ubifs_info *c, int old_ltail_lnum)
{ … }

/**
 * struct done_ref - references that have been done.
 * @rb: rb-tree node
 * @lnum: LEB number
 */
struct done_ref { … };

/**
 * done_already - determine if a reference has been done already.
 * @done_tree: rb-tree to store references that have been done
 * @lnum: LEB number of reference
 *
 * This function returns %1 if the reference has been done, %0 if not, otherwise
 * a negative error code is returned.
 */
static int done_already(struct rb_root *done_tree, int lnum)
{ … }

/**
 * destroy_done_tree - destroy the done tree.
 * @done_tree: done tree to destroy
 */
static void destroy_done_tree(struct rb_root *done_tree)
{ … }

/**
 * add_node - add a node to the consolidated log.
 * @c: UBIFS file-system description object
 * @buf: buffer to which to add
 * @lnum: LEB number to which to write is passed and returned here
 * @offs: offset to where to write is passed and returned here
 * @node: node to add
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int add_node(struct ubifs_info *c, void *buf, int *lnum, int *offs,
		    void *node)
{ … }

/**
 * ubifs_consolidate_log - consolidate the log.
 * @c: UBIFS file-system description object
 *
 * Repeated failed commits could cause the log to be full, but at least 1 LEB is
 * needed for commit. This function rewrites the reference nodes in the log
 * omitting duplicates, and failed CS nodes, and leaving no gaps.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_consolidate_log(struct ubifs_info *c)
{ … }

/**
 * dbg_check_bud_bytes - make sure bud bytes calculation are all right.
 * @c: UBIFS file-system description object
 *
 * This function makes sure the amount of flash space used by closed buds
 * ('c->bud_bytes' is correct). Returns zero in case of success and %-EINVAL in
 * case of failure.
 */
static int dbg_check_bud_bytes(struct ubifs_info *c)
{ … }