linux/fs/ubifs/master.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 implements reading and writing the master node */

#include "ubifs.h"

/**
 * ubifs_compare_master_node - compare two UBIFS master nodes
 * @c: UBIFS file-system description object
 * @m1: the first node
 * @m2: the second node
 *
 * This function compares two UBIFS master nodes. Returns 0 if they are equal
 * and nonzero if not.
 */
int ubifs_compare_master_node(struct ubifs_info *c, void *m1, void *m2)
{ … }

/* mst_node_check_hash - Check hash of a master node
 * @c: UBIFS file-system description object
 * @mst: The master node
 * @expected: The expected hash of the master node
 *
 * This checks the hash of a master node against a given expected hash.
 * Note that we have two master nodes on a UBIFS image which have different
 * sequence numbers and consequently different CRCs. To be able to match
 * both master nodes we exclude the common node header containing the sequence
 * number and CRC from the hash.
 *
 * Returns 0 if the hashes are equal, a negative error code otherwise.
 */
static int mst_node_check_hash(const struct ubifs_info *c,
			       const struct ubifs_mst_node *mst,
			       const u8 *expected)
{ … }

/**
 * scan_for_master - search the valid master node.
 * @c: UBIFS file-system description object
 *
 * This function scans the master node LEBs and search for the latest master
 * node. Returns zero in case of success, %-EUCLEAN if there master area is
 * corrupted and requires recovery, and a negative error code in case of
 * failure.
 */
static int scan_for_master(struct ubifs_info *c)
{ … }

/**
 * validate_master - validate master node.
 * @c: UBIFS file-system description object
 *
 * This function validates data which was read from master node. Returns zero
 * if the data is all right and %-EINVAL if not.
 */
static int validate_master(const struct ubifs_info *c)
{ … }

/**
 * ubifs_read_master - read master node.
 * @c: UBIFS file-system description object
 *
 * This function finds and reads the master node during file-system mount. If
 * the flash is empty, it creates default master node as well. Returns zero in
 * case of success and a negative error code in case of failure.
 */
int ubifs_read_master(struct ubifs_info *c)
{ … }

/**
 * ubifs_write_master - write master node.
 * @c: UBIFS file-system description object
 *
 * This function writes the master node. Returns zero in case of success and a
 * negative error code in case of failure. The master node is written twice to
 * enable recovery.
 */
int ubifs_write_master(struct ubifs_info *c)
{ … }