/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright (C) 2001-2003 Red Hat, Inc.
 *
 * Created by David Woodhouse <dwmw2@redhat.com>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 * $Id: scan.c,v 1.104 2003/10/11 14:52:48 dwmw2 Exp $
 *
 */
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/pagemap.h>
#include <linux/crc32.h>
#include <linux/compiler.h>
#include "nodelist.h"

#define EMPTY_SCAN_SIZE 1024

#define DIRTY_SPACE(x) do { typeof(x) _x = (x); \
		c->free_size -= _x; c->dirty_size += _x; \
		jeb->free_size -= _x ; jeb->dirty_size += _x; \
		}while(0)
#define USED_SPACE(x) do { typeof(x) _x = (x); \
		c->free_size -= _x; c->used_size += _x; \
		jeb->free_size -= _x ; jeb->used_size += _x; \
		}while(0)
#define UNCHECKED_SPACE(x) do { typeof(x) _x = (x); \
		c->free_size -= _x; c->unchecked_size += _x; \
		jeb->free_size -= _x ; jeb->unchecked_size += _x; \
		}while(0)

#define noisy_printk(noise, args...) do { \
	if (*(noise)) { \
		printk(KERN_NOTICE args); \
		 (*(noise))--; \
		 if (!(*(noise))) { \
			 printk(KERN_NOTICE "Further such events for this erase block will not be printed\n"); \
		 } \
	} \
} while(0)

static uint32_t pseudo_random;

static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
				  unsigned char *buf, uint32_t buf_size);

/* These helper functions _must_ increase ofs and also do the dirty/used space accounting. 
 * Returning an error will abort the mount - bad checksums etc. should just mark the space
 * as dirty.
 */
static int jffs2_scan_inode_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, 
				 struct jffs2_raw_inode *ri, uint32_t ofs);
static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
				 struct jffs2_raw_dirent *rd, uint32_t ofs);

#define BLK_STATE_ALLFF		0
#define BLK_STATE_CLEAN		1
#define BLK_STATE_PARTDIRTY	2
#define BLK_STATE_CLEANMARKER	3
#define BLK_STATE_ALLDIRTY	4
#define BLK_STATE_BADBLOCK	5

static inline int min_free(struct jffs2_sb_info *c)
{
	uint32_t min = 2 * sizeof(struct jffs2_raw_inode);
#ifdef CONFIG_JFFS2_FS_NAND
	if (!jffs2_can_mark_obsolete(c) && min < c->wbuf_pagesize)
		return c->wbuf_pagesize;
#endif
	return min;

}
int jffs2_scan_medium(struct jffs2_sb_info *c)
{
	int i, ret;
	uint32_t empty_blocks = 0, bad_blocks = 0;
	unsigned char *flashbuf = NULL;
	uint32_t buf_size = 0;
#ifndef __ECOS
	size_t pointlen;

	if (c->mtd->point) {
		ret = c->mtd->point (c->mtd, 0, c->mtd->size, &pointlen, &flashbuf);
		if (!ret && pointlen < c->mtd->size) {
			/* Don't muck about if it won't let us point to the whole flash */
			D1(printk(KERN_DEBUG "MTD point returned len too short: 0x%zx\n", pointlen));
			c->mtd->unpoint(c->mtd, flashbuf, 0, c->mtd->size);
			flashbuf = NULL;
		}
		if (ret)
			D1(printk(KERN_DEBUG "MTD point failed %d\n", ret));
	}
#endif
	if (!flashbuf) {
		/* For NAND it's quicker to read a whole eraseblock at a time,
		   apparently */
		if (jffs2_cleanmarker_oob(c))
			buf_size = c->sector_size;
		else
			buf_size = PAGE_SIZE;

		D1(printk(KERN_DEBUG "Allocating readbuf of %d bytes\n", buf_size));
		flashbuf = kmalloc(buf_size, GFP_KERNEL);
		if (!flashbuf)
			return -ENOMEM;
	}

	for (i=0; i<c->nr_blocks; i++) {
		struct jffs2_eraseblock *jeb = &c->blocks[i];

		ret = jffs2_scan_eraseblock(c, jeb, buf_size?flashbuf:(flashbuf+jeb->offset), buf_size);

		if (ret < 0)
			goto out;

		ACCT_PARANOIA_CHECK(jeb);

		/* Now decide which list to put it on */
		switch(ret) {
		case BLK_STATE_ALLFF:
			/* 
			 * Empty block.   Since we can't be sure it 
			 * was entirely erased, we just queue it for erase
			 * again.  It will be marked as such when the erase
			 * is complete.  Meanwhile we still count it as empty
			 * for later checks.
			 */
			empty_blocks++;
			list_add(&jeb->list, &c->erase_pending_list);
			c->nr_erasing_blocks++;
			break;

		case BLK_STATE_CLEANMARKER:
			/* Only a CLEANMARKER node is valid */
			if (!jeb->dirty_size) {
				/* It's actually free */
				list_add(&jeb->list, &c->free_list);
				c->nr_free_blocks++;
			} else {
				/* Dirt */
				D1(printk(KERN_DEBUG "Adding all-dirty block at 0x%08x to erase_pending_list\n", jeb->offset));
				list_add(&jeb->list, &c->erase_pending_list);
				c->nr_erasing_blocks++;
			}
			break;

		case BLK_STATE_CLEAN:
                        /* Full (or almost full) of clean data. Clean list */
                        list_add(&jeb->list, &c->clean_list);
			break;

		case BLK_STATE_PARTDIRTY:
                        /* Some data, but not full. Dirty list. */
                        /* Except that we want to remember the block with most free space,
                           and stick it in the 'nextblock' position to start writing to it.
                           Later when we do snapshots, this must be the most recent block,
                           not the one with most free space.
                        */
                        if (jeb->free_size > min_free(c) && 
			    (!c->nextblock || c->nextblock->free_size < jeb->free_size)) {
                                /* Better candidate for the next writes to go to */
                                if (c->nextblock) {
					c->nextblock->dirty_size += c->nextblock->free_size + c->nextblock->wasted_size;
					c->dirty_size += c->nextblock->free_size + c->nextblock->wasted_size;
					c->free_size -= c->nextblock->free_size;
					c->wasted_size -= c->nextblock->wasted_size;
					c->nextblock->free_size = c->nextblock->wasted_size = 0;
					if (VERYDIRTY(c, c->nextblock->dirty_size)) {
						list_add(&c->nextblock->list, &c->very_dirty_list);
					} else {
						list_add(&c->nextblock->list, &c->dirty_list);
					}
				}
                                c->nextblock = jeb;
                        } else {
				jeb->dirty_size += jeb->free_size + jeb->wasted_size;
				c->dirty_size += jeb->free_size + jeb->wasted_size;
				c->free_size -= jeb->free_size;
				c->wasted_size -= jeb->wasted_size;
				jeb->free_size = jeb->wasted_size = 0;
				if (VERYDIRTY(c, jeb->dirty_size)) {
					list_add(&jeb->list, &c->very_dirty_list);
				} else {
					list_add(&jeb->list, &c->dirty_list);
				}
                        }
			break;

		case BLK_STATE_ALLDIRTY:
			/* Nothing valid - not even a clean marker. Needs erasing. */
                        /* For now we just put it on the erasing list. We'll start the erases later */
			D1(printk(KERN_NOTICE "JFFS2: Erase block at 0x%08x is not formatted. It will be erased\n", jeb->offset));
                        list_add(&jeb->list, &c->erase_pending_list);
			c->nr_erasing_blocks++;
			break;
			
		case BLK_STATE_BADBLOCK:
			D1(printk(KERN_NOTICE "JFFS2: Block at 0x%08x is bad\n", jeb->offset));
                        list_add(&jeb->list, &c->bad_list);
			c->bad_size += c->sector_size;
			c->free_size -= c->sector_size;
			bad_blocks++;
			break;
		default:
			printk(KERN_WARNING "jffs2_scan_medium(): unknown block state\n");
			BUG();	
		}
	}
	
	/* Nextblock dirty is always seen as wasted, because we cannot recycle it now */
	if (c->nextblock && (c->nextblock->dirty_size)) {
		c->nextblock->wasted_size += c->nextblock->dirty_size;
		c->wasted_size += c->nextblock->dirty_size;
		c->dirty_size -= c->nextblock->dirty_size;
		c->nextblock->dirty_size = 0;
	}
#ifdef CONFIG_JFFS2_FS_NAND
	if (!jffs2_can_mark_obsolete(c) && c->nextblock && (c->nextblock->free_size & (c->wbuf_pagesize-1))) {
		/* If we're going to start writing into a block which already 
		   contains data, and the end of the data isn't page-aligned,
		   skip a little and align it. */

		uint32_t skip = c->nextblock->free_size & (c->wbuf_pagesize-1);

		D1(printk(KERN_DEBUG "jffs2_scan_medium(): Skipping %d bytes in nextblock to ensure page alignment\n",
			  skip));
		c->nextblock->wasted_size += skip;
		c->wasted_size += skip;

		c->nextblock->free_size -= skip;
		c->free_size -= skip;
	}
#endif
	if (c->nr_erasing_blocks) {
		if ( !c->used_size && ((empty_blocks+bad_blocks)!= c->nr_blocks || bad_blocks == c->nr_blocks) ) {
			printk(KERN_NOTICE "Cowardly refusing to erase blocks on filesystem with no valid JFFS2 nodes\n");
			printk(KERN_NOTICE "empty_blocks %d, bad_blocks %d, c->nr_blocks %d\n",empty_blocks,bad_blocks,c->nr_blocks);
			ret = -EIO;
			goto out;
		}
		jffs2_erase_pending_trigger(c);
	}
	ret = 0;
 out:
	if (buf_size)
		kfree(flashbuf);
#ifndef __ECOS
	else 
		c->mtd->unpoint(c->mtd, flashbuf, 0, c->mtd->size);
#endif
	return ret;
}

static int jffs2_fill_scan_buf (struct jffs2_sb_info *c, unsigned char *buf,
				uint32_t ofs, uint32_t len)
{
	int ret;
	size_t retlen;

	ret = jffs2_flash_read(c, ofs, len, &retlen, buf);
	if (ret) {
		D1(printk(KERN_WARNING "mtd->read(0x%x bytes from 0x%x) returned %d\n", len, ofs, ret));
		return ret;
	}
	if (retlen < len) {
		D1(printk(KERN_WARNING "Read at 0x%x gave only 0x%zx bytes\n", ofs, retlen));
		return -EIO;
	}
	D2(printk(KERN_DEBUG "Read 0x%x bytes from 0x%08x into buf\n", len, ofs));
	D2(printk(KERN_DEBUG "000: %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x\n",
		  buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], buf[6], buf[7], buf[8], buf[9], buf[10], buf[11], buf[12], buf[13], buf[14], buf[15]));
	return 0;
}

static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
				  unsigned char *buf, uint32_t buf_size) {
	struct jffs2_unknown_node *node;
	struct jffs2_unknown_node crcnode;
	uint32_t ofs, prevofs;
	uint32_t hdr_crc, buf_ofs, buf_len;
	int err;
	int noise = 0;
	int wasempty = 0;
	uint32_t empty_start = 0;
#ifdef CONFIG_JFFS2_FS_NAND
	int cleanmarkerfound = 0;
#endif

	ofs = jeb->offset;
	prevofs = jeb->offset - 1;

	D1(printk(KERN_DEBUG "jffs2_scan_eraseblock(): Scanning block at 0x%x\n", ofs));

#ifdef CONFIG_JFFS2_FS_NAND
	if (jffs2_cleanmarker_oob(c)) {
		int ret = jffs2_check_nand_cleanmarker(c, jeb);
		D2(printk(KERN_NOTICE "jffs_check_nand_cleanmarker returned %d\n",ret));
		/* Even if it's not found, we still scan to see
		   if the block is empty. We use this information
		   to decide whether to erase it or not. */
		switch (ret) {
		case 0:		cleanmarkerfound = 1; break;
		case 1: 	break;
		case 2: 	return BLK_STATE_BADBLOCK;
		case 3:		return BLK_STATE_ALLDIRTY; /* Block has failed to erase min. once */
		default: 	return ret;
		}
	}
#endif
	buf_ofs = jeb->offset;

	if (!buf_size) {
		buf_len = c->sector_size;
	} else {
		buf_len = EMPTY_SCAN_SIZE;
		err = jffs2_fill_scan_buf(c, buf, buf_ofs, buf_len);
		if (err)
			return err;
	}
	
	/* We temporarily use 'ofs' as a pointer into the buffer/jeb */
	ofs = 0;

	/* Scan only 4KiB of 0xFF before declaring it's empty */
	while(ofs < EMPTY_SCAN_SIZE && *(uint32_t *)(&buf[ofs]) == 0xFFFFFFFF)
		ofs += 4;

	if (ofs == EMPTY_SCAN_SIZE) {
#ifdef CONFIG_JFFS2_FS_NAND
		if (jffs2_cleanmarker_oob(c)) {
			/* scan oob, take care of cleanmarker */
			int ret = jffs2_check_oob_empty(c, jeb, cleanmarkerfound);
			D2(printk(KERN_NOTICE "jffs2_check_oob_empty returned %d\n",ret));
			switch (ret) {
			case 0:		return cleanmarkerfound ? BLK_STATE_CLEANMARKER : BLK_STATE_ALLFF;
			case 1: 	return BLK_STATE_ALLDIRTY;
			case 2: 	return BLK_STATE_BADBLOCK; /* case 2/3 are paranoia checks */
			case 3:		return BLK_STATE_ALLDIRTY; /* Block has failed to erase min. once */
			default: 	return ret;
			}
		}
#endif
		D1(printk(KERN_DEBUG "Block at 0x%08x is empty (erased)\n", jeb->offset));
		return BLK_STATE_ALLFF;	/* OK to erase if all blocks are like this */
	}
	if (ofs) {
		D1(printk(KERN_DEBUG "Free space at %08x ends at %08x\n", jeb->offset,
			  jeb->offset + ofs));
		DIRTY_SPACE(ofs);
	}

	/* Now ofs is a complete physical flash offset as it always was... */
	ofs += jeb->offset;

	noise = 10;

	while(ofs < jeb->offset + c->sector_size) {

		D1(ACCT_PARANOIA_CHECK(jeb));

		cond_resched();

		if (ofs & 3) {
			printk(KERN_WARNING "Eep. ofs 0x%08x not word-aligned!\n", ofs);
			ofs = PAD(ofs);
			continue;
		}
		if (ofs == prevofs) {
			printk(KERN_WARNING "ofs 0x%08x has already been seen. Skipping\n", ofs);
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}
		prevofs = ofs;

		if (jeb->offset + c->sector_size < ofs + sizeof(*node)) {
			D1(printk(KERN_DEBUG "Fewer than %zd bytes left to end of block. (%x+%x<%x+%zx) Not reading\n", sizeof(struct jffs2_unknown_node),
				  jeb->offset, c->sector_size, ofs, sizeof(*node)));
			DIRTY_SPACE((jeb->offset + c->sector_size)-ofs);
			break;
		}

		if (buf_ofs + buf_len < ofs + sizeof(*node)) {
			buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
			D1(printk(KERN_DEBUG "Fewer than %zd bytes (node header) left to end of buf. Reading 0x%x at 0x%08x\n",
				  sizeof(struct jffs2_unknown_node), buf_len, ofs));
			err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
			if (err)
				return err;
			buf_ofs = ofs;
		}

		node = (struct jffs2_unknown_node *)&buf[ofs-buf_ofs];

		if (*(uint32_t *)(&buf[ofs-buf_ofs]) == 0xffffffff) {
			uint32_t inbuf_ofs = ofs - buf_ofs + 4;
			uint32_t scanend;

			empty_start = ofs;
			ofs += 4;

			/* If scanning empty space after only a cleanmarker, don't
			   bother scanning the whole block */
			if (unlikely(empty_start == jeb->offset + c->cleanmarker_size &&
				     jeb->offset + EMPTY_SCAN_SIZE < buf_ofs + buf_len))
				scanend = jeb->offset + EMPTY_SCAN_SIZE - buf_ofs;
			else
				scanend = buf_len;

			D1(printk(KERN_DEBUG "Found empty flash at 0x%08x\n", ofs));
			while (inbuf_ofs < scanend) {
				if (*(uint32_t *)(&buf[inbuf_ofs]) != 0xffffffff)
					goto emptyends;

				inbuf_ofs+=4;
				ofs += 4;
			}
			/* Ran off end. */
			D1(printk(KERN_DEBUG "Empty flash ends normally at 0x%08x\n", ofs));

			if (buf_ofs == jeb->offset &&  jeb->used_size == PAD(c->cleanmarker_size) && 
			    c->cleanmarker_size && !jeb->first_node->next_in_ino && !jeb->dirty_size)
				return BLK_STATE_CLEANMARKER;
			wasempty = 1;
			continue;
		} else if (wasempty) {
		emptyends:
			printk(KERN_WARNING "Empty flash at 0x%08x ends at 0x%08x\n", empty_start, ofs);
			DIRTY_SPACE(ofs-empty_start);
			wasempty = 0;
			continue;
		}

		if (ofs == jeb->offset && je16_to_cpu(node->magic) == KSAMTIB_CIGAM_2SFFJ) {
			printk(KERN_WARNING "Magic bitmask is backwards at offset 0x%08x. Wrong endian filesystem?\n", ofs);
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}
		if (je16_to_cpu(node->magic) == JFFS2_DIRTY_BITMASK) {
			D1(printk(KERN_DEBUG "Dirty bitmask at 0x%08x\n", ofs));
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}
		if (je16_to_cpu(node->magic) == JFFS2_OLD_MAGIC_BITMASK) {
			printk(KERN_WARNING "Old JFFS2 bitmask found at 0x%08x\n", ofs);
			printk(KERN_WARNING "You cannot use older JFFS2 filesystems with newer kernels\n");
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}
		if (je16_to_cpu(node->magic) != JFFS2_MAGIC_BITMASK) {
			/* OK. We're out of possibilities. Whinge and move on */
			noisy_printk(&noise, "jffs2_scan_eraseblock(): Magic bitmask 0x%04x not found at 0x%08x: 0x%04x instead\n", 
				     JFFS2_MAGIC_BITMASK, ofs, 
				     je16_to_cpu(node->magic));
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}
		/* We seem to have a node of sorts. Check the CRC */
		crcnode.magic = node->magic;
		crcnode.nodetype = cpu_to_je16( je16_to_cpu(node->nodetype) | JFFS2_NODE_ACCURATE);
		crcnode.totlen = node->totlen;
		hdr_crc = crc32(0, &crcnode, sizeof(crcnode)-4);

		if (hdr_crc != je32_to_cpu(node->hdr_crc)) {
			noisy_printk(&noise, "jffs2_scan_eraseblock(): Node at 0x%08x {0x%04x, 0x%04x, 0x%08x) has invalid CRC 0x%08x (calculated 0x%08x)\n",
				     ofs, je16_to_cpu(node->magic),
				     je16_to_cpu(node->nodetype), 
				     je32_to_cpu(node->totlen),
				     je32_to_cpu(node->hdr_crc),
				     hdr_crc);
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}

		if (ofs + je32_to_cpu(node->totlen) > 
		    jeb->offset + c->sector_size) {
			/* Eep. Node goes over the end of the erase block. */
			printk(KERN_WARNING "Node at 0x%08x with length 0x%08x would run over the end of the erase block\n",
			       ofs, je32_to_cpu(node->totlen));
			printk(KERN_WARNING "Perhaps the file system was created with the wrong erase size?\n");
			DIRTY_SPACE(4);
			ofs += 4;
			continue;
		}

		if (!(je16_to_cpu(node->nodetype) & JFFS2_NODE_ACCURATE)) {
			/* Wheee. This is an obsoleted node */
			D2(printk(KERN_DEBUG "Node at 0x%08x is obsolete. Skipping\n", ofs));
			DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
			ofs += PAD(je32_to_cpu(node->totlen));
			continue;
		}

		switch(je16_to_cpu(node->nodetype)) {
		case JFFS2_NODETYPE_INODE:
			if (buf_ofs + buf_len < ofs + sizeof(struct jffs2_raw_inode)) {
				buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
				D1(printk(KERN_DEBUG "Fewer than %zd bytes (inode node) left to end of buf. Reading 0x%x at 0x%08x\n",
					  sizeof(struct jffs2_raw_inode), buf_len, ofs));
				err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
				if (err)
					return err;
				buf_ofs = ofs;
				node = (void *)buf;
			}
			err = jffs2_scan_inode_node(c, jeb, (void *)node, ofs);
			if (err) return err;
			ofs += PAD(je32_to_cpu(node->totlen));
			break;
			
		case JFFS2_NODETYPE_DIRENT:
			if (buf_ofs + buf_len < ofs + je32_to_cpu(node->totlen)) {
				buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
				D1(printk(KERN_DEBUG "Fewer than %d bytes (dirent node) left to end of buf. Reading 0x%x at 0x%08x\n",
					  je32_to_cpu(node->totlen), buf_len, ofs));
				err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
				if (err)
					return err;
				buf_ofs = ofs;
				node = (void *)buf;
			}
			err = jffs2_scan_dirent_node(c, jeb, (void *)node, ofs);
			if (err) return err;
			ofs += PAD(je32_to_cpu(node->totlen));
			break;

		case JFFS2_NODETYPE_CLEANMARKER:
			D1(printk(KERN_DEBUG "CLEANMARKER node found at 0x%08x\n", ofs));
			if (je32_to_cpu(node->totlen) != c->cleanmarker_size) {
				printk(KERN_NOTICE "CLEANMARKER node found at 0x%08x has totlen 0x%x != normal 0x%x\n", 
				       ofs, je32_to_cpu(node->totlen), c->cleanmarker_size);
				DIRTY_SPACE(PAD(sizeof(struct jffs2_unknown_node)));
				ofs += PAD(sizeof(struct jffs2_unknown_node));
			} else if (jeb->first_node) {
				printk(KERN_NOTICE "CLEANMARKER node found at 0x%08x, not first node in block (0x%08x)\n", ofs, jeb->offset);
				DIRTY_SPACE(PAD(sizeof(struct jffs2_unknown_node)));
				ofs += PAD(sizeof(struct jffs2_unknown_node));
			} else {
				struct jffs2_raw_node_ref *marker_ref = jffs2_alloc_raw_node_ref();
				if (!marker_ref) {
					printk(KERN_NOTICE "Failed to allocate node ref for clean marker\n");
					return -ENOMEM;
				}
				marker_ref->next_in_ino = NULL;
				marker_ref->next_phys = NULL;
				marker_ref->flash_offset = ofs | REF_NORMAL;
				marker_ref->totlen = c->cleanmarker_size;
				jeb->first_node = jeb->last_node = marker_ref;
			     
				USED_SPACE(PAD(c->cleanmarker_size));
				ofs += PAD(c->cleanmarker_size);
			}
			break;

		case JFFS2_NODETYPE_PADDING:
			DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
			ofs += PAD(je32_to_cpu(node->totlen));
			break;

		default:
			switch (je16_to_cpu(node->nodetype) & JFFS2_COMPAT_MASK) {
			case JFFS2_FEATURE_ROCOMPAT:
				printk(KERN_NOTICE "Read-only compatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs);
			        c->flags |= JFFS2_SB_FLAG_RO;
				if (!(jffs2_is_readonly(c)))
					return -EROFS;
				DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
				ofs += PAD(je32_to_cpu(node->totlen));
				break;

			case JFFS2_FEATURE_INCOMPAT:
				printk(KERN_NOTICE "Incompatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs);
				return -EINVAL;

			case JFFS2_FEATURE_RWCOMPAT_DELETE:
				D1(printk(KERN_NOTICE "Unknown but compatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs));
				DIRTY_SPACE(PAD(je32_to_cpu(node->totlen)));
				ofs += PAD(je32_to_cpu(node->totlen));
				break;

			case JFFS2_FEATURE_RWCOMPAT_COPY:
				D1(printk(KERN_NOTICE "Unknown but compatible feature node (0x%04x) found at offset 0x%08x\n", je16_to_cpu(node->nodetype), ofs));
				USED_SPACE(PAD(je32_to_cpu(node->totlen)));
				ofs += PAD(je32_to_cpu(node->totlen));
				break;
			}
		}
	}


	D1(printk(KERN_DEBUG "Block at 0x%08x: free 0x%08x, dirty 0x%08x, unchecked 0x%08x, used 0x%08x\n", jeb->offset, 
		  jeb->free_size, jeb->dirty_size, jeb->unchecked_size, jeb->used_size));

	/* mark_node_obsolete can add to wasted !! */
	if (jeb->wasted_size) {
		jeb->dirty_size += jeb->wasted_size;
		c->dirty_size += jeb->wasted_size;
		c->wasted_size -= jeb->wasted_size;
		jeb->wasted_size = 0;
	}

	if ((jeb->used_size + jeb->unchecked_size) == PAD(c->cleanmarker_size) && !jeb->dirty_size 
		&& (!jeb->first_node || jeb->first_node->next_in_ino) )
		return BLK_STATE_CLEANMARKER;
		
	/* move blocks with max 4 byte dirty space to cleanlist */	
	else if (!ISDIRTY(c->sector_size - (jeb->used_size + jeb->unchecked_size))) {
		c->dirty_size -= jeb->dirty_size;
		c->wasted_size += jeb->dirty_size; 
		jeb->wasted_size += jeb->dirty_size;
		jeb->dirty_size = 0;
		return BLK_STATE_CLEAN;
	} else if (jeb->used_size || jeb->unchecked_size)
		return BLK_STATE_PARTDIRTY;
	else
		return BLK_STATE_ALLDIRTY;
}

static struct jffs2_inode_cache *jffs2_scan_make_ino_cache(struct jffs2_sb_info *c, uint32_t ino)
{
	struct jffs2_inode_cache *ic;

	ic = jffs2_get_ino_cache(c, ino);
	if (ic)
		return ic;

	ic = jffs2_alloc_inode_cache();
	if (!ic) {
		printk(KERN_NOTICE "jffs2_scan_make_inode_cache(): allocation of inode cache failed\n");
		return NULL;
	}
	memset(ic, 0, sizeof(*ic));

	ic->ino = ino;
	ic->nodes = (void *)ic;
	jffs2_add_ino_cache(c, ic);
	if (ino == 1)
		ic->nlink=1;
	return ic;
}

static int jffs2_scan_inode_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, 
				 struct jffs2_raw_inode *ri, uint32_t ofs)
{
	struct jffs2_raw_node_ref *raw;
	struct jffs2_inode_cache *ic;
	uint32_t ino = je32_to_cpu(ri->ino);

	D1(printk(KERN_DEBUG "jffs2_scan_inode_node(): Node at 0x%08x\n", ofs));

	/* We do very little here now. Just check the ino# to which we should attribute
	   this node; we can do all the CRC checking etc. later. There's a tradeoff here -- 
	   we used to scan the flash once only, reading everything we want from it into
	   memory, then building all our in-core data structures and freeing the extra
	   information. Now we allow the first part of the mount to complete a lot quicker,
	   but we have to go _back_ to the flash in order to finish the CRC checking, etc. 
	   Which means that the _full_ amount of time to get to proper write mode with GC
	   operational may actually be _longer_ than before. Sucks to be me. */

	raw = jffs2_alloc_raw_node_ref();
	if (!raw) {
		printk(KERN_NOTICE "jffs2_scan_inode_node(): allocation of node reference failed\n");
		return -ENOMEM;
	}

	ic = jffs2_get_ino_cache(c, ino);
	if (!ic) {
		/* Inocache get failed. Either we read a bogus ino# or it's just genuinely the
		   first node we found for this inode. Do a CRC check to protect against the former
		   case */
		uint32_t crc = crc32(0, ri, sizeof(*ri)-8);

		if (crc != je32_to_cpu(ri->node_crc)) {
			printk(KERN_NOTICE "jffs2_scan_inode_node(): CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
			       ofs, je32_to_cpu(ri->node_crc), crc);
			/* We believe totlen because the CRC on the node _header_ was OK, just the node itself failed. */
			DIRTY_SPACE(PAD(je32_to_cpu(ri->totlen)));
			jffs2_free_raw_node_ref(raw);
			return 0;
		}
		ic = jffs2_scan_make_ino_cache(c, ino);
		if (!ic) {
			jffs2_free_raw_node_ref(raw);
			return -ENOMEM;
		}
	}

	/* Wheee. It worked */

	raw->flash_offset = ofs | REF_UNCHECKED;
	raw->totlen = PAD(je32_to_cpu(ri->totlen));
	raw->next_phys = NULL;
	raw->next_in_ino = ic->nodes;

	ic->nodes = raw;
	if (!jeb->first_node)
		jeb->first_node = raw;
	if (jeb->last_node)
		jeb->last_node->next_phys = raw;
	jeb->last_node = raw;

	D1(printk(KERN_DEBUG "Node is ino #%u, version %d. Range 0x%x-0x%x\n", 
		  je32_to_cpu(ri->ino), je32_to_cpu(ri->version),
		  je32_to_cpu(ri->offset),
		  je32_to_cpu(ri->offset)+je32_to_cpu(ri->dsize)));

	pseudo_random += je32_to_cpu(ri->version);

	UNCHECKED_SPACE(PAD(je32_to_cpu(ri->totlen)));
	return 0;
}

static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, 
				  struct jffs2_raw_dirent *rd, uint32_t ofs)
{
	struct jffs2_raw_node_ref *raw;
	struct jffs2_full_dirent *fd;
	struct jffs2_inode_cache *ic;
	uint32_t crc;

	D1(printk(KERN_DEBUG "jffs2_scan_dirent_node(): Node at 0x%08x\n", ofs));

	/* We don't get here unless the node is still valid, so we don't have to
	   mask in the ACCURATE bit any more. */
	crc = crc32(0, rd, sizeof(*rd)-8);

	if (crc != je32_to_cpu(rd->node_crc)) {
		printk(KERN_NOTICE "jffs2_scan_dirent_node(): Node CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
		       ofs, je32_to_cpu(rd->node_crc), crc);
		/* We believe totlen because the CRC on the node _header_ was OK, just the node itself failed. */
		DIRTY_SPACE(PAD(je32_to_cpu(rd->totlen)));
		return 0;
	}

	pseudo_random += je32_to_cpu(rd->version);

	fd = jffs2_alloc_full_dirent(rd->nsize+1);
	if (!fd) {
		return -ENOMEM;
	}
	memcpy(&fd->name, rd->name, rd->nsize);
	fd->name[rd->nsize] = 0;

	crc = crc32(0, fd->name, rd->nsize);
	if (crc != je32_to_cpu(rd->name_crc)) {
		printk(KERN_NOTICE "jffs2_scan_dirent_node(): Name CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
		       ofs, je32_to_cpu(rd->name_crc), crc);	
		D1(printk(KERN_NOTICE "Name for which CRC failed is (now) '%s', ino #%d\n", fd->name, je32_to_cpu(rd->ino)));
		jffs2_free_full_dirent(fd);
		/* FIXME: Why do we believe totlen? */
		/* We believe totlen because the CRC on the node _header_ was OK, just the name failed. */
		DIRTY_SPACE(PAD(je32_to_cpu(rd->totlen)));
		return 0;
	}
	raw = jffs2_alloc_raw_node_ref();
	if (!raw) {
		jffs2_free_full_dirent(fd);
		printk(KERN_NOTICE "jffs2_scan_dirent_node(): allocation of node reference failed\n");
		return -ENOMEM;
	}
	ic = jffs2_scan_make_ino_cache(c, je32_to_cpu(rd->pino));
	if (!ic) {
		jffs2_free_full_dirent(fd);
		jffs2_free_raw_node_ref(raw);
		return -ENOMEM;
	}
	
	raw->totlen = PAD(je32_to_cpu(rd->totlen));
	raw->flash_offset = ofs | REF_PRISTINE;
	raw->next_phys = NULL;
	raw->next_in_ino = ic->nodes;
	ic->nodes = raw;
	if (!jeb->first_node)
		jeb->first_node = raw;
	if (jeb->last_node)
		jeb->last_node->next_phys = raw;
	jeb->last_node = raw;

	fd->raw = raw;
	fd->next = NULL;
	fd->version = je32_to_cpu(rd->version);
	fd->ino = je32_to_cpu(rd->ino);
	fd->nhash = full_name_hash(fd->name, rd->nsize);
	fd->type = rd->type;
	USED_SPACE(PAD(je32_to_cpu(rd->totlen)));
	jffs2_add_fd_to_list(c, fd, &ic->scan_dents);

	return 0;
}

static int count_list(struct list_head *l)
{
	uint32_t count = 0;
	struct list_head *tmp;

	list_for_each(tmp, l) {
		count++;
	}
	return count;
}

/* Note: This breaks if list_empty(head). I don't care. You
   might, if you copy this code and use it elsewhere :) */
static void rotate_list(struct list_head *head, uint32_t count)
{
	struct list_head *n = head->next;

	list_del(head);
	while(count--) {
		n = n->next;
	}
	list_add(head, n);
}

void jffs2_rotate_lists(struct jffs2_sb_info *c)
{
	uint32_t x;
	uint32_t rotateby;

	x = count_list(&c->clean_list);
	if (x) {
		rotateby = pseudo_random % x;
		D1(printk(KERN_DEBUG "Rotating clean_list by %d\n", rotateby));

		rotate_list((&c->clean_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of clean_list is at %08x\n",
			  list_entry(c->clean_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty clean_list\n"));
	}

	x = count_list(&c->very_dirty_list);
	if (x) {
		rotateby = pseudo_random % x;
		D1(printk(KERN_DEBUG "Rotating very_dirty_list by %d\n", rotateby));

		rotate_list((&c->very_dirty_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of very_dirty_list is at %08x\n",
			  list_entry(c->very_dirty_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty very_dirty_list\n"));
	}

	x = count_list(&c->dirty_list);
	if (x) {
		rotateby = pseudo_random % x;
		D1(printk(KERN_DEBUG "Rotating dirty_list by %d\n", rotateby));

		rotate_list((&c->dirty_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of dirty_list is at %08x\n",
			  list_entry(c->dirty_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty dirty_list\n"));
	}

	x = count_list(&c->erasable_list);
	if (x) {
		rotateby = pseudo_random % x;
		D1(printk(KERN_DEBUG "Rotating erasable_list by %d\n", rotateby));

		rotate_list((&c->erasable_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of erasable_list is at %08x\n",
			  list_entry(c->erasable_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty erasable_list\n"));
	}

	if (c->nr_erasing_blocks) {
		rotateby = pseudo_random % c->nr_erasing_blocks;
		D1(printk(KERN_DEBUG "Rotating erase_pending_list by %d\n", rotateby));

		rotate_list((&c->erase_pending_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of erase_pending_list is at %08x\n",
			  list_entry(c->erase_pending_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty erase_pending_list\n"));
	}

	if (c->nr_free_blocks) {
		rotateby = pseudo_random % c->nr_free_blocks;
		D1(printk(KERN_DEBUG "Rotating free_list by %d\n", rotateby));

		rotate_list((&c->free_list), rotateby);

		D1(printk(KERN_DEBUG "Erase block at front of free_list is at %08x\n",
			  list_entry(c->free_list.next, struct jffs2_eraseblock, list)->offset));
	} else {
		D1(printk(KERN_DEBUG "Not rotating empty free_list\n"));
	}
}
