nftlmount.c

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/* 
 * NFTL mount code with extensive checks
 *
 * Author: Fabrice Bellard ([e-mail]) 
 * Copyright (C) 2000 Netgem S.A.
 *
 * $Id: nftlmount.c,v 1.11 2000/11/17 12:24:09 ollie Exp $
 *
 * 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
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/errno.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/malloc.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nftl.h>
#include <linux/mtd/compatmac.h>

#define SECTORSIZE 512

/* find_boot_record: Find the NFTL Media Header and its Spare copy which contains the
 *	various device information of the NFTL partition and Bad Unit Table. Update
 *	the ReplUnitTable[] table accroding to the Bad Unit Table. ReplUnitTable[]
 *	is used for management of Erase Unit in other routines in nftl.c and nftlmount.c
 */
static int find_boot_record(struct NFTLrecord *nftl)
{
	struct nftl_uci1 h1;
	struct nftl_oob oob;
	unsigned int block, boot_record_count;
	int retlen;
	u8 buf[SECTORSIZE];
	struct NFTLMediaHeader *mh = &nftl->MediaHdr;

	nftl->MediaUnit = BLOCK_NIL;
	nftl->SpareMediaUnit = BLOCK_NIL;
	boot_record_count = 0;

	/* search for a valid boot record */
	for (block = 0; block < nftl->nb_blocks; block++) {
		unsigned int erase_mark;

		/* read ANAND header. To be safer with BIOS, also use erase mark as discriminant */
		if (MTD_READOOB(nftl->mtd, block * nftl->EraseSize + SECTORSIZE + 8,
				8, &retlen, (char *)&h1) < 0)
			continue;

		erase_mark = le16_to_cpu ((h1.EraseMark | h1.EraseMark1));
		if (erase_mark != ERASE_MARK) 
			continue;

		if (MTD_READECC(nftl->mtd, block * nftl->EraseSize, SECTORSIZE,
				&retlen, buf, (char *)&oob) < 0)
			continue;

		memcpy(mh, buf, sizeof(struct NFTLMediaHeader));
		if (memcmp(mh->DataOrgID, "ANAND", 6) == 0) {
			/* first boot record */
			if (boot_record_count == 0) {
				unsigned int i;
				/* header found : read the bad block table data */
				if (mh->UnitSizeFactor != 0xff) {
					printk("Sorry, we don't support UnitSizeFactor "
					       "of != 1 yet\n");
					goto ReplUnitTable;
				}

				nftl->nb_boot_blocks = le16_to_cpu(mh->FirstPhysicalEUN);
				if ((nftl->nb_boot_blocks + 2) >= nftl->nb_blocks)
					goto ReplUnitTable; /* small consistency check */

				nftl->numvunits = le32_to_cpu(mh->FormattedSize) / nftl->EraseSize;
				if (nftl->numvunits > (nftl->nb_blocks - nftl->nb_boot_blocks - 2))
					goto ReplUnitTable; /* small consistency check */

				/* FixMe: with bad blocks, the total size available is not FormattedSize any
				   more !!! */
				nftl->nr_sects  = nftl->numvunits * (nftl->EraseSize / SECTORSIZE);
				nftl->MediaUnit = block;

				/* read the Bad Erase Unit Table and modify ReplUnitTable[] accordingly */
				for (i = 0; i < nftl->nb_blocks; i++) {
					if ((i & (SECTORSIZE - 1)) == 0) {
						/* read one sector for every SECTORSIZE of blocks */
						if (MTD_READECC(nftl->mtd, block * nftl->EraseSize +
								i + SECTORSIZE, SECTORSIZE,
								&retlen, buf, (char *)&oob) < 0)
							goto ReplUnitTable;
					}
					/* mark the Bad Erase Unit as RESERVED in ReplUnitTable */
					if (buf[i & (SECTORSIZE - 1)] != 0xff)
						nftl->ReplUnitTable[i] = BLOCK_RESERVED;
				}

				boot_record_count++;
			} else if (boot_record_count == 1) {
				nftl->SpareMediaUnit = block;
				boot_record_count++;
				break;
			}
		}
	ReplUnitTable:
	}

	if (boot_record_count == 0) {
		/* no boot record found */
		return -1;
	} else {
		return 0;
	}
}

static int memcmpb(void *a, int c, int n)
{
	int i;
	for (i = 0; i < n; i++) {
		if (c != ((unsigned char *)a)[i])
			return 1;
	}
	return 0;
}

/* check_free_sector: check if a free sector is actually FREE, i.e. All 0xff in data and oob area */
static int check_free_sectors(struct NFTLrecord *nftl, unsigned int address, int len, 
			      int check_oob)
{
	int i, retlen;
	u8 buf[SECTORSIZE];

	for (i = 0; i < len; i += SECTORSIZE) {
		/* we want to read the sector without ECC check here since a free
		   sector does not have ECC syndrome on it yet */
		if (MTD_READ(nftl->mtd, address, SECTORSIZE, &retlen, buf) < 0)
			return -1;
		if (memcmpb(buf, 0xff, SECTORSIZE) != 0)
			return -1;

		if (check_oob) {
			if (MTD_READOOB(nftl->mtd, address, nftl->mtd->oobsize,
					&retlen, buf) < 0)
				return -1;
			if (memcmpb(buf, 0xff, nftl->mtd->oobsize) != 0)
				return -1;
		}
		address += SECTORSIZE;
	}

	return 0;
}

/* NFTL_format: format a Erase Unit by erasing ALL Erase Zones in the Erase Unit and
 *              Update NFTL metadata. Each erase operation is checked with check_free_sectors
 *
 * Return: 0 when succeed, -1 on error.
 *
 *  ToDo: 1. Is it neceressary to check_free_sector after erasing ?? 
 *        2. UnitSizeFactor != 0xFF
 */
int NFTL_formatblock(struct NFTLrecord *nftl, int block)
{
	int retlen;
	unsigned int nb_erases, erase_mark;
	struct nftl_uci1 uci;
	struct erase_info *instr = &nftl->instr;

	/* Read the Unit Control Information #1 for Wear-Leveling */
	if (MTD_READOOB(nftl->mtd, block * nftl->EraseSize + SECTORSIZE + 8,
			8, &retlen, (char *)&uci) < 0)
		goto default_uci1;

	erase_mark = le16_to_cpu ((uci.EraseMark | uci.EraseMark1));
	if (erase_mark != ERASE_MARK) {
	default_uci1:
		uci.EraseMark = cpu_to_le16(ERASE_MARK);
		uci.EraseMark1 = cpu_to_le16(ERASE_MARK);
		uci.WearInfo = cpu_to_le32(0);
	}

	memset(instr, 0, sizeof(struct erase_info));

	/* XXX: use async erase interface, XXX: test return code */
	instr->addr = block * nftl->EraseSize;
	instr->len = nftl->EraseSize;
	MTD_ERASE(nftl->mtd, instr);

	if (instr->state == MTD_ERASE_FAILED) {
		/* could not format, FixMe: We should update the BadUnitTable 
		   both in memory and on disk */
		printk("Error while formatting block %d\n", block);
		return -1;
	} else {
		/* increase and write Wear-Leveling info */
		nb_erases = le32_to_cpu(uci.WearInfo);
		nb_erases++;

		/* wrap (almost impossible with current flashs) or free block */
		if (nb_erases == 0)
			nb_erases = 1;

		/* check the "freeness" of Erase Unit before updating metadata
		 * FixMe:  is this check really necessary ? since we have check the
		 *         return code after the erase operation. */
		if (check_free_sectors(nftl, instr->addr, nftl->EraseSize, 1) != 0)
			return -1;

		uci.WearInfo = le32_to_cpu(nb_erases);
		if (MTD_WRITEOOB(nftl->mtd, block * nftl->EraseSize + SECTORSIZE + 8, 8,
				 &retlen, (char *)&uci) < 0)
			return -1;
		return 0;
	}
}

/* check_sectors_in_chain: Check that each sector of a Virtual Unit Chain is correct.
 *	Mark as 'IGNORE' each incorrect sector. This check is only done if the chain
 *	was being folded when NFTL was interrupted.
 *
 *	The check_free_sectors in this function is neceressary. There is a possible
 *	situation that after writing the Data area, the Block Control Information is
 *	not updated according (due to power failure or something) which leaves the block
 *	in an umconsistent state. So we have to check if a block is really FREE in this
 *	case. */
static void check_sectors_in_chain(struct NFTLrecord *nftl, unsigned int first_block)
{
	unsigned int block, i, status;
	struct nftl_bci bci;
	int sectors_per_block, retlen;

	sectors_per_block = nftl->EraseSize / SECTORSIZE;
	block = first_block;
	for (;;) {
		for (i = 0; i < sectors_per_block; i++) {
			if (MTD_READOOB(nftl->mtd, block * nftl->EraseSize + i * SECTORSIZE,
					8, &retlen, (char *)&bci) < 0)
				status = SECTOR_IGNORE;
			else
				status = bci.Status | bci.Status1;

			switch(status) {
			case SECTOR_FREE:
				/* verify that the sector is really free. If not, mark
				   as ignore */
				if (memcmpb(&bci, 0xff, 8) != 0 ||
				    check_free_sectors(nftl, block * nftl->EraseSize + i * SECTORSIZE, 
						       SECTORSIZE, 0) != 0) {
					printk("Incorrect free sector %d in block %d: "
					       "marking it as ignored\n",
					       i, block);

					/* sector not free actually : mark it as SECTOR_IGNORE  */
					bci.Status = SECTOR_IGNORE;
					bci.Status1 = SECTOR_IGNORE;
					MTD_WRITEOOB(nftl->mtd,
						     block * nftl->EraseSize + i * SECTORSIZE,
						     8, &retlen, (char *)&bci);
				}
				break;
			default:
				break;
			}
		}

		/* proceed to next Erase Unit on the chain */
		block = nftl->ReplUnitTable[block];
		if (!(block == BLOCK_NIL || block < nftl->nb_blocks))
			printk("incorrect ReplUnitTable[] : %d\n", block);
		if (block == BLOCK_NIL || block >= nftl->nb_blocks)
			break;
	}
}

/* calc_chain_lenght: Walk through a Virtual Unit Chain and estimate chain length */
static int calc_chain_length(struct NFTLrecord *nftl, unsigned int first_block)
{
	unsigned int length = 0, block = first_block;

	for (;;) {
		length++;
		/* avoid infinite loops, although this is guaranted not to
		   happen because of the previous checks */
		if (length >= nftl->nb_blocks) {
			printk("nftl: length too long %d !\n", length);
			break;
		}

		block = nftl->ReplUnitTable[block];
		if (!(block == BLOCK_NIL || block < nftl->nb_blocks))
			printk("incorrect ReplUnitTable[] : %d\n", block);
		if (block == BLOCK_NIL || block >= nftl->nb_blocks)
			break;
	}
	return length;
}

/* format_chain: Format an invalid Virtual Unit chain. It frees all the Erase Units in a
 *	Virtual Unit Chain, i.e. all the units are disconnected.
 *
 *	It is not stricly correct to begin from the first block of the chain because
 *	if we stop the code, we may see again a valid chain if there was a first_block
 *	flag in a block inside it. But is it really a problem ?
 *
 * FixMe: Figure out what the last statesment means. What if power failure when we are
 *	in the for (;;) loop formatting blocks ??
 */
static void format_chain(struct NFTLrecord *nftl, unsigned int first_block)
{
	unsigned int block = first_block, block1;

	printk("Formatting chain at block %d\n", first_block);

	for (;;) {
		block1 = nftl->ReplUnitTable[block];

		printk("Formatting block %d\n", block);
		if (NFTL_formatblock(nftl, block) < 0) {
			/* cannot format !!!! Mark it as Bad Unit,
			   FixMe: update the BadUnitTable on disk */
			nftl->ReplUnitTable[block] = BLOCK_RESERVED;
		} else {
			nftl->ReplUnitTable[block] = BLOCK_FREE;