/*
* 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.
*
* Scanned 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.
*
* UBI tries to distinguish between 2 types of corruptions.
* 1. Corruptions caused by power cuts. These are harmless and expected
* corruptions and UBI tries to handle them gracefully, without printing too
* many warnings and error messages. The idea is that we do not lose
* important data in these case - we may lose only the data which was being
* written to the media just before the power cut happened, and the upper
* layers are supposed to handle these situations. UBI puts these PEBs to
* the head of the @erase list and they are scheduled for erasure.
*
* 2. Unexpected corruptions which are not caused by power cuts. During
* scanning, such PEBs are put to the @corr list and UBI preserves them.
* Obviously, this lessens the amount of available PEBs, and if at some
* point UBI runs out of free PEBs, it switches to R/O mode. UBI also loudly
* informs about such PEBs every time the MTD device is attached.
*/
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/crc32.h>
#include <linux/math64.h>
#include <linux/random.h>
#include "ubi.h"
#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
static int paranoid_check_si(struct ubi_device *ubi
