patch-2.4.0-test12 linux/drivers/mtd/nftlmount.c

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diff -u --recursive --new-file v2.4.0-test11/linux/drivers/mtd/nftlmount.c linux/drivers/mtd/nftlmount.c
@@ -0,0 +1,678 @@
+/* 
+ * NFTL mount code with extensive checks
+ *
+ * Author: Fabrice Bellard (fabrice.bellard@netgem.com) 
+ * 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/config.h>
+#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;
+		}
+
+		/* goto next block on the chain */
+		block = block1;
+
+		if (!(block == BLOCK_NIL || block < nftl->nb_blocks))
+			printk("incorrect ReplUnitTable[] : %d\n", block);
+		if (block == BLOCK_NIL || block >= nftl->nb_blocks)
+			break;
+	}
+}
+
+/* check_and_mark_free_block: Verify that a block is free in the NFTL sense (valid erase mark) or
+ *	totally free (only 0xff).
+ *
+ * Definition: Free Erase Unit -- A properly erased/formatted Free Erase Unit should have meet the
+ *	following critia:
+ *	1. */
+static int check_and_mark_free_block(struct NFTLrecord *nftl, int block)
+{
+	struct nftl_uci1 h1;
+	unsigned int erase_mark;
+	int i, retlen;
+	unsigned char buf[SECTORSIZE];
+
+	/* check erase mark. */
+	if (MTD_READOOB(nftl->mtd, block * nftl->EraseSize + SECTORSIZE + 8, 8, 
+			&retlen, (char *)&h1) < 0)
+		return -1;
+
+	erase_mark = le16_to_cpu ((h1.EraseMark | h1.EraseMark1));
+	if (erase_mark != ERASE_MARK) {
+		/* if no erase mark, the block must be totally free. This is
+		   possible in two cases : empty filsystem or interrupted erase (very unlikely) */
+		if (check_free_sectors (nftl, block * nftl->EraseSize, nftl->EraseSize, 1) != 0)
+			return -1;
+
+		/* free block : write erase mark */
+		h1.EraseMark = cpu_to_le16(ERASE_MARK);
+		h1.EraseMark1 = cpu_to_le16(ERASE_MARK);
+		h1.WearInfo = cpu_to_le32(0);
+		if (MTD_WRITEOOB(nftl->mtd, block * nftl->EraseSize + SECTORSIZE + 8, 8, 
+				 &retlen, (char *)&h1) < 0)
+			return -1;
+	} else {
+#if 0
+		/* if erase mark present, need to skip it when doing check */
+		for (i = 0; i < nftl->EraseSize; i += SECTORSIZE) {
+			/* check free sector */
+			if (check_free_sectors (nftl, block * nftl->EraseSize + i,
+						SECTORSIZE, 0) != 0)
+				return -1;
+
+			if (MTD_READOOB(nftl->mtd, block * nftl->EraseSize + i,
+					16, &retlen, buf) < 0)
+				return -1;
+			if (i == SECTORSIZE) {
+				/* skip erase mark */
+				if (memcmpb(buf, 0xff, 8))
+					return -1;
+			} else {
+				if (memcmpb(buf, 0xff, 16))
+					return -1;
+			}
+		}
+#endif
+	}
+
+	return 0;
+}
+
+/* get_fold_mark: Read fold mark from Unit Control Information #2, we use FOLD_MARK_IN_PROGRESS
+ *	to indicate that we are in the progression of a Virtual Unit Chain folding. If the UCI #2
+ *	is FOLD_MARK_IN_PROGRESS when mounting the NFTL, the (previous) folding process is interrupted
+ *	for some reason. A clean up/check of the VUC is neceressary in this case.
+ *
+ * WARNING: return 0 if read error
+ */
+static int get_fold_mark(struct NFTLrecord *nftl, unsigned int block)
+{
+	struct nftl_uci2 uci;
+	int retlen;
+
+	if (MTD_READOOB(nftl->mtd, block * nftl->EraseSize + 2 * SECTORSIZE + 8,
+			8, &retlen, (char *)&uci) < 0)
+		return 0;
+
+	return le16_to_cpu((uci.FoldMark | uci.FoldMark1));
+}
+
+int NFTL_mount(struct NFTLrecord *s)
+{
+	int i;
+	unsigned int first_logical_block, logical_block, rep_block, nb_erases, erase_mark;
+	unsigned int block, first_block, is_first_block;
+	int chain_length, do_format_chain;
+	struct nftl_uci0 h0;
+	struct nftl_uci1 h1;
+	int retlen;
+
+	/* XXX: will be suppressed */
+	s->lastEUN = s->nb_blocks - 1;
+
+	/* memory alloc */
+	s->EUNtable = kmalloc(s->nb_blocks * sizeof(u16), GFP_KERNEL);
+	s->ReplUnitTable = kmalloc(s->nb_blocks * sizeof(u16), GFP_KERNEL);
+	if (!s->EUNtable || !s->ReplUnitTable) {
+	fail:
+		if (s->EUNtable)
+			kfree(s->EUNtable);
+		if (s->ReplUnitTable)
+			kfree(s->ReplUnitTable);
+		return -1;
+	}
+
+	/* mark all blocks as potentially containing data */
+	for (i = 0; i < s->nb_blocks; i++) { 
+		s->ReplUnitTable[i] = BLOCK_NOTEXPLORED;
+	}
+
+	/* search for NFTL MediaHeader and Spare NFTL Media Header */
+	if (find_boot_record(s) < 0) {
+		printk("Could not find valid boot record\n");
+		goto fail;
+	}
+
+	/* mark the bios blocks (blocks before NFTL MediaHeader) as reserved */
+	for (i = 0; i < s->nb_boot_blocks; i++)
+		s->ReplUnitTable[i] = BLOCK_RESERVED;
+
+	/* also mark the boot records (NFTL MediaHeader) blocks as reserved */
+	if (s->MediaUnit != BLOCK_NIL)
+		s->ReplUnitTable[s->MediaUnit] = BLOCK_RESERVED;
+	if (s->SpareMediaUnit != BLOCK_NIL)
+		s->ReplUnitTable[s->SpareMediaUnit] = BLOCK_RESERVED;
+
+	/* init the logical to physical table */
+	for (i = 0; i < s->nb_blocks; i++) {
+		s->EUNtable[i] = BLOCK_NIL;
+	}
+
+	/* first pass : explore each block chain */
+	first_logical_block = 0;
+	for (first_block = 0; first_block < s->nb_blocks; first_block++) {
+		/* if the block was not already explored, we can look at it */
+		if (s->ReplUnitTable[first_block] == BLOCK_NOTEXPLORED) {
+			block = first_block;
+			chain_length = 0;
+			do_format_chain = 0;
+
+			for (;;) {
+				/* read the block header. If error, we format the chain */
+				if (MTD_READOOB(s->mtd, block * s->EraseSize + 8, 8, 
+						&retlen, (char *)&h0) < 0 ||
+				    MTD_READOOB(s->mtd, block * s->EraseSize + SECTORSIZE + 8, 8, 
+						&retlen, (char *)&h1) < 0) {
+					s->ReplUnitTable[block] = BLOCK_NIL;
+					do_format_chain = 1;
+					break;
+				}
+
+				logical_block = le16_to_cpu ((h0.VirtUnitNum | h0.SpareVirtUnitNum));
+				rep_block = le16_to_cpu ((h0.ReplUnitNum | h0.SpareReplUnitNum));
+				nb_erases = le32_to_cpu (h1.WearInfo);
+				erase_mark = le16_to_cpu ((h1.EraseMark | h1.EraseMark1));
+
+				is_first_block = !(logical_block >> 15);
+				logical_block = logical_block & 0x7fff;
+
+				/* invalid/free block test */
+				if (erase_mark != ERASE_MARK || logical_block >= s->nb_blocks) {
+					if (chain_length == 0) {
+						/* if not currently in a chain, we can handle it safely */
+						if (check_and_mark_free_block(s, block) < 0) {
+							/* not really free: format it */
+							printk("Formatting block %d\n", block);
+							if (NFTL_formatblock(s, block) < 0) {
+								/* could not format: reserve the block */
+								s->ReplUnitTable[block] = BLOCK_RESERVED;
+							} else {
+								s->ReplUnitTable[block] = BLOCK_FREE;
+							}
+						} else {
+							/* free block: mark it */
+							s->ReplUnitTable[block] = BLOCK_FREE;
+						}
+						/* directly examine the next block. */
+						goto examine_ReplUnitTable;
+					} else {
+						/* the block was in a chain : this is bad. We
+						   must format all the chain */
+						printk("Block %d: free but referenced in chain %d\n",
+						       block, first_block);
+						s->ReplUnitTable[block] = BLOCK_NIL;
+						do_format_chain = 1;
+						break;
+					}
+				}
+
+				/* we accept only first blocks here */
+				if (chain_length == 0) {
+					/* this block is not the first block in chain :
+					   ignore it, it will be included in a chain
+					   later, or marked as not explored */
+					if (!is_first_block)
+						goto examine_ReplUnitTable;
+					first_logical_block = logical_block;
+				} else {
+					if (logical_block != first_logical_block) {
+						printk("Block %d: incorrect logical block: %d expected: %d\n", 
+						       block, logical_block, first_logical_block);
+						/* the chain is incorrect : we must format it,
+						   but we need to read it completly */
+						do_format_chain = 1;
+					}
+					if (is_first_block) {
+						/* we accept that a block is marked as first
+						   block while being last block in a chain
+						   only if the chain is being folded */
+						if (get_fold_mark(s, block) != FOLD_MARK_IN_PROGRESS ||
+						    rep_block != 0xffff) {
+							printk("Block %d: incorrectly marked as first block in chain\n",
+							       block);
+							/* the chain is incorrect : we must format it,
+							   but we need to read it completly */
+							do_format_chain = 1;
+						} else {
+							printk("Block %d: folding in progress - ignoring first block flag\n",
+							       block);
+						}
+					}
+				}
+				chain_length++;
+				if (rep_block == 0xffff) {
+					/* no more blocks after */
+					s->ReplUnitTable[block] = BLOCK_NIL;
+					break;
+				} else if (rep_block >= s->nb_blocks) {
+					printk("Block %d: referencing invalid block %d\n", 
+					       block, rep_block);
+					do_format_chain = 1;
+					s->ReplUnitTable[block] = BLOCK_NIL;
+					break;
+				} else if (s->ReplUnitTable[rep_block] != BLOCK_NOTEXPLORED) {
+					/* same problem as previous 'is_first_block' test:
+					   we accept that the last block of a chain has
+					   the first_block flag set if folding is in
+					   progress. We handle here the case where the
+					   last block appeared first */
+					if (s->ReplUnitTable[rep_block] == BLOCK_NIL &&
+					    s->EUNtable[first_logical_block] == rep_block &&
+					    get_fold_mark(s, first_block) == FOLD_MARK_IN_PROGRESS) {
+						/* EUNtable[] will be set after */
+						printk("Block %d: folding in progress - ignoring first block flag\n",
+						       rep_block);
+						s->ReplUnitTable[block] = rep_block;
+						s->EUNtable[first_logical_block] = BLOCK_NIL;
+					} else {
+						printk("Block %d: referencing block %d already in another chain\n", 
+						       block, rep_block);
+						/* XXX: should handle correctly fold in progress chains */
+						do_format_chain = 1;
+						s->ReplUnitTable[block] = BLOCK_NIL;
+					}
+					break;
+				} else {
+					/* this is OK */
+					s->ReplUnitTable[block] = rep_block;
+					block = rep_block;
+				}
+			}
+
+			/* the chain was completely explored. Now we can decide
+			   what to do with it */
+			if (do_format_chain) {
+				/* invalid chain : format it */
+				format_chain(s, first_block);
+			} else {
+				unsigned int first_block1, chain_to_format, chain_length1;
+				int fold_mark;
+				
+				/* valid chain : get foldmark */
+				fold_mark = get_fold_mark(s, first_block);
+				if (fold_mark == 0) {
+					/* cannot get foldmark : format the chain */
+					printk("Could read foldmark at block %d\n", first_block);
+					format_chain(s, first_block);
+				} else {
+					if (fold_mark == FOLD_MARK_IN_PROGRESS)
+						check_sectors_in_chain(s, first_block);
+
+					/* now handle the case where we find two chains at the
+					   same virtual address : we select the longer one,
+					   because the shorter one is the one which was being
+					   folded if the folding was not done in place */
+					first_block1 = s->EUNtable[first_logical_block];
+					if (first_block1 != BLOCK_NIL) {
+						/* XXX: what to do if same length ? */
+						chain_length1 = calc_chain_length(s, first_block1);
+						printk("Two chains at blocks %d (len=%d) and %d (len=%d)\n", 
+						       first_block1, chain_length1, first_block, chain_length);
+						
+						if (chain_length >= chain_length1) {
+							chain_to_format = first_block1;
+							s->EUNtable[first_logical_block] = first_block;
+						} else {
+							chain_to_format = first_block;
+						}
+						format_chain(s, chain_to_format);
+					} else {
+						s->EUNtable[first_logical_block] = first_block;
+					}
+				}
+			}
+		}
+	examine_ReplUnitTable:
+	}
+
+	/* second pass to format unreferenced blocks  and init free block count */
+	s->numfreeEUNs = 0;
+	s->LastFreeEUN = BLOCK_NIL;
+
+	for (block = 0; block < s->nb_blocks; block++) {
+		if (s->ReplUnitTable[block] == BLOCK_NOTEXPLORED) {
+			printk("Unreferenced block %d, formatting it\n", block);
+			if (NFTL_formatblock(s, block) < 0)
+				s->ReplUnitTable[block] = BLOCK_RESERVED;
+			else
+				s->ReplUnitTable[block] = BLOCK_FREE;
+		}
+		if (s->ReplUnitTable[block] == BLOCK_FREE) {
+			s->numfreeEUNs++;
+			s->LastFreeEUN = block;
+		}
+	}
+
+	return 0;
+}
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)