path: root/drivers/mtd/ubi/scan.c

/*
 * 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)
 */

/*
 * UBI scanning sub-system.
 *
 * This sub-system is responsible for scanning the flash media, checking UBI
 * headers and providing complete information about the UBI flash image.
 *
 * The scanning information is represented by a &struct ubi_scan_info' object.
 * Information about found volumes is represented by &struct ubi_scan_volume
 * objects which are kept in volume RB-tree with root at the @volumes field.
 * The RB-tree is indexed by the volume ID.
 *
 * Found logical eraseblocks are represented by &struct ubi_scan_leb objects.
 * These objects are kept in per-volume RB-trees with the root at the
 * corresponding &struct ubi_scan_volume object. To put it differently, we keep
 * an RB-tree of per-volume objects and each of these objects is the root of
 * RB-tree of per-eraseblock objects.
 *
 * Corrupted physical eraseblocks are put to the @corr list, free physical
 * eraseblocks are put to the @free list and the physical eraseblock to be
 * erased are put to the @erase list.
 */

#include <linux/err.h>
#include <linux/crc32.h>
#include <linux/math64.h>
#include "ubi.h"

#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
static int paranoid_check_si(struct ubi_device *ubi, struct ubi_scan_info *si);
#else
#define paranoid_check_si(ubi, si) 0
#endif

/* Temporary variables used during scanning */
static struct ubi_ec_hdr *ech;
static struct ubi_vid_hdr *vidh;

/**
 * add_to_list - add physical eraseblock to a list.
 * @si: scanning information
 * @pnum: physical eraseblock number to add
 * @ec: erase counter of the physical eraseblock
 * @list: the list to add to
 *
 * This function adds physical eraseblock @pnum to free, erase, corrupted or
 * alien lists. Returns zero in case of success and a negative error code in
 * case of failure.
 */
static int add_to_list(struct ubi_scan_info *si, int pnum, int ec,
		       struct list_head *list)
{
	struct ubi_scan_leb *seb;

	if (list == &si->free)
		dbg_bld("add to free: PEB %d, EC %d", pnum, ec);
	else if (list == &si->erase)
		dbg_bld("add to erase: PEB %d, EC %d", pnum, ec);
	else if (list == &si->corr) {
		dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
		si->corr_count += 1;
	} else if (list == &si->alien)
		dbg_bld("add to alien: PEB %d, EC %d", pnum, ec);
	else
		BUG();

	seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL);
	if (!seb)
		return -ENOMEM