/*
 * JFFS -- Journaling Flash File System, Linux implementation.
 *
 * Copyright (C) 1999, 2000  Axis Communications, Inc.
 *
 * Created by Finn Hakansson <finn@axis.com>.
 *
 * This 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.
 *
 * $Id: intrep.c,v 1.102 2001/09/23 23:28:36 dwmw2 Exp $
 *
 * Ported to Linux 2.3.x and MTD:
 * Copyright (C) 2000  Alexander Larsson (alex@cendio.se), Cendio Systems AB
 *
 */

/* This file contains the code for the internal structure of the
   Journaling Flash File System, JFFS.  */

/*
 * Todo list:
 *
 * memcpy_to_flash() and memcpy_from_flash() functions.
 *
 * Implementation of hard links.
 *
 * Organize the source code in a better way. Against the VFS we could
 * have jffs_ext.c, and against the block device jffs_int.c.
 * A better file-internal organization too.
 *
 * A better checksum algorithm.
 *
 * Consider endianness stuff. ntohl() etc.
 *
 * Are we handling the atime, mtime, ctime members of the inode right?
 *
 * Remove some duplicated code. Take a look at jffs_write_node() and
 * jffs_rewrite_data() for instance.
 *
 * Implement more meaning of the nlink member in various data structures.
 * nlink could be used in conjunction with hard links for instance.
 *
 * Better memory management. Allocate data structures in larger chunks
 * if possible.
 *
 * If too much meta data is stored, a garbage collect should be issued.
 * We have experienced problems with too much meta data with for instance
 * log files.
 *
 * Improve the calls to jffs_ioctl(). We would like to retrieve more
 * information to be able to debug (or to supervise) JFFS during run-time.
 *
 */

#include <linux/types.h>
#include <linux/slab.h>
#include <linux/jffs.h>
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/pagemap.h>
#include <linux/mutex.h>
#include <asm/byteorder.h>
#include <linux/smp_lock.h>
#include <linux/time.h>
#include <linux/ctype.h>
#include <linux/freezer.h>

#include "intrep.h"
#include "jffs_fm.h"

long no_jffs_node = 0;
static long no_jffs_file = 0;
#if defined(JFFS_MEMORY_DEBUG) && JFFS_MEMORY_DEBUG
long no_jffs_control = 0;
long no_jffs_raw_inode = 0;
long no_jffs_node_ref = 0;
long no_jffs_fm = 0;
long no_jffs_fmcontrol = 0;
long no_hash = 0;
long no_name = 0;
#endif

static int jffs_scan_flash(struct jffs_control *c);
static int jffs_update_file(struct jffs_file *f, struct jffs_node *node);
static int jffs_build_file(struct jffs_file *f);
static int jffs_free_file(struct jffs_file *f);
static int jffs_free_node_list(struct jffs_file *f);
static int jffs_garbage_collect_now(struct jffs_control *c);
static int jffs_insert_file_into_hash(struct jffs_file *f);
static int jffs_remove_redundant_nodes(struct jffs_file *f);

/* Is there enough space on the flash?  */
static inline int JFFS_ENOUGH_SPACE(struct jffs_control *c, __u32 space)
{
	struct jffs_fmcontrol *fmc = c->fmc;

	while (1) {
		if ((fmc->flash_size - (fmc->used_size + fmc->dirty_size))
			>= fmc->min_free_size + space) {
			return 1;
		}
		if (fmc->dirty_size < fmc->sector_size)
			return 0;

		if (jffs_garbage_collect_now(c)) {
		  D1(printk("JFFS_ENOUGH_SPACE: jffs_garbage_collect_now() failed.\n"));
		  return 0;
		}
	}
}

#if CONFIG_JFFS_FS_VERBOSE > 0
static __u8
flash_read_u8(struct mtd_info *mtd, loff_t from)
{
	size_t retlen;
	__u8 ret;
	int res;

	res = MTD_READ(mtd, from, 1, &retlen, &ret);
	if (retlen != 1) {
		printk("Didn't read a byte in flash_read_u8(). Returned %d\n", res);
		return 0;
	}

	return ret;
}

static void
jffs_hexdump(struct mtd_info *mtd, loff_t pos, int size)
{
	char line[16];
	int j = 0;

	while (size > 0) {
		int i;

		printk("%ld:", (long) pos);
		for (j = 0; j < 16; j++) {
			line[j] = flash_read_u8(mtd, pos++);
		}
		for (i = 0; i < j; i++) {
			if (!(i & 1)) {
				printk(" %.2x", line[i] & 0xff);
			}
			else {
				printk("%.2x", line[i] & 0xff);
			}
		}

		/* Print empty space */
		for (; i < 16; i++) {
			if (!(i & 1)) {
				printk("   ");
			}
			else {
				printk("  ");
			}
		}
		printk("  ");

		for (i = 0; i < j; i++) {
			if (isgraph(line[i])) {
				printk("%c", line[i]);
			}
			else {
				printk(".");
			}
		}
		printk("\n");
		size -= 16;
	}
}

/* Print the contents of a node.  */
static void
jffs_print_node(struct jffs_node *n)
{
	D(printk("jffs_node: 0x%p\n", n));
	D(printk("{\n"));
	D(printk("        0x%08x, /* version  */\n", n->version));
	D(printk("        0x%08x, /* data_offset  */\n", n->data_offset));
	D(printk("        0x%08x, /* data_size  */\n", n->data_size));
	D(printk("        0x%08x, /* removed_size  */\n", n->removed_size));
	D(printk("        0x%08x, /* fm_offset  */\n", n->fm_offset));
	D(printk("        0x%02x,       /* name_size  */\n", n->name_size));
	D(printk("        0x%p, /* fm,  fm->offset: %u  */\n",
		 n->fm, (n->fm ? n->fm->offset : 0)));
	D(printk("        0x%p, /* version_prev  */\n", n->version_prev));
	D(printk("        0x%p, /* version_next  */\n", n->version_next));
	D(printk("        0x%p, /* range_prev  */\n", n->range_prev));
	D(printk("        0x%p, /* range_next  */\n", n->range_next));
	D(printk("}\n"));
}

#endif

/* Print the contents of a raw inode.  */
static void
jffs_print_raw_inode(struct jffs_raw_inode *raw_inode)
{
	D(printk("jffs_raw_inode: inode number: %u\n", raw_inode->ino));
	D(printk("{\n"));
	D(printk("        0x%08x, /* magic  */\n", raw_inode->magic));
	D(printk("        0x%08x, /* ino  */\n", raw_inode->ino));
	D(printk("        0x%08x, /* pino  */\n", raw_inode->pino));
	D(printk("        0x%08x, /* version  */\n", raw_inode->version));
	D(printk("        0x%08x, /* mode  */\n", raw_inode->mode));
	D(printk("        0x%04x,     /* uid  */\n", raw_inode->uid));
	D(printk("        0x%04x,     /* gid  */\n", raw_inode->gid));
	D(printk("        0x%08x, /* atime  */\n", raw_inode->atime));
	D(printk("        0x%08x, /* mtime  */\n", raw_inode->mtime));
	D(printk("        0x%08x, /* ctime  */\n", raw_inode->ctime));
	D(printk("        0x%08x, /* offset  */\n", raw_inode->offset));
	D(printk("        0x%08x, /* dsize  */\n", raw_inode->dsize));
	D(printk("        0x%08x, /* rsize  */\n", raw_inode->rsize));
	D(printk("        0x%02x,       /* nsize  */\n", raw_inode->nsize));
	D(printk("        0x%02x,       /* nlink  */\n", raw_inode->nlink));
	D(printk("        0x%02x,       /* spare  */\n",
		 raw_inode->spare));
	D(printk("        %u,          /* rename  */\n",
		 raw_inode->rename));
	D(printk("        %u,          /* deleted  */\n",
		 raw_inode->deleted));
	D(printk("        0x%02x,       /* accurate  */\n",
		 raw_inode->accurate));
	D(printk("        0x%08x, /* dchksum  */\n", raw_inode->dchksum));
	D(printk("        0x%04x,     /* nchksum  */\n", raw_inode->nchksum));
	D(printk("        0x%04x,     /* chksum  */\n", raw_inode->chksum));
	D(printk("}\n"));
}

#define flash_safe_acquire(arg)
#define flash_safe_release(arg)


static int
flash_safe_read(struct mtd_info *mtd, loff_t from,
		u_char *buf, size_t count)
{
	size_t retlen;
	int res;

	D3(printk(KERN_NOTICE "flash_safe_read(%p, %08x, %p, %08x)\n",
		  mtd, (unsigned int) from, buf, count));

	res = mtd->read(mtd, from, count, &retlen, buf);
	if (retlen != count) {
		panic("Didn't read all bytes in flash_safe_read(). Returned %d\n", res);
	}
	return res?res:retlen;
}


static __u32
flash_read_u32(struct mtd_info *mtd, loff_t from)
{
	size_t retlen;
	__u32 ret;
	int res;

	res = mtd->read(mtd, from, 4, &retlen, (unsigned char *)&ret);
	if (retlen != 4) {
		printk("Didn't read all bytes in flash_read_u32(). Returned %d\n", res);
		return 0;
	}

	return ret;
}


static int
flash_safe_write(struct mtd_info *mtd, loff_t to,
		 const u_char *buf, size_t count)
{
	size_t retlen;
	int res;

	D3(printk(KERN_NOTICE "flash_safe_write(%p, %08x, %p, %08x)\n",
		  mtd, (unsigned int) to, buf, count));

	res = mtd->write(mtd, to, count, &retlen, buf);
	if (retlen != count) {
		printk("Didn't write all bytes in flash_safe_write(). Returned %d\n", res);
	}
	return res?res:retlen;
}


static int
flash_safe_writev(struct mtd_info *mtd, const struct kvec *vecs,
			unsigned long iovec_cnt, loff_t to)
{
	size_t retlen, retlen_a;
	int i;
	int res;

	D3(printk(KERN_NOTICE "flash_safe_writev(%p, %08x, %p)\n",
		  mtd, (unsigned int) to, vecs));

	if (mtd->writev) {
		res = mtd->writev(mtd, vecs, iovec_cnt, to, &retlen);
		return res ? res : retlen;
	}
	/* Not implemented writev. Repeatedly use write - on the not so
	   unreasonable assumption that the mtd driver doesn't care how
	   many write cycles we use. */
	res=0;
	retlen=0;

	for (i=0; !res && i<iovec_cnt; i++) {
		res = mtd->write(mtd, to, vecs[i].iov_len, &retlen_a,
				 vecs[i].iov_base);
		if (retlen_a != vecs[i].iov_len) {
			printk("Didn't write all bytes in flash_safe_writev(). Returned %d\n", res);
			if (i != iovec_cnt-1)
				return -EIO;
		}
		/* If res is non-zero, retlen_a is undefined, but we don't
		   care because in that case it's not going to be 
		   returned anyway.
		*/
		to += retlen_a;
		retlen += retlen_a;
	}
	return res?res:retlen;
}


static int
flash_memset(struct mtd_info *mtd, loff_t to,
	     const u_char c, size_t size)
{
	static unsigned char pattern[64];
	int i;

	/* fill up pattern */

	for(i = 0; i < 64; i++)
		pattern[i] = c;

	/* write as many 64-byte chunks as we can */

	while (size >= 64) {
		flash_safe_write(mtd, to, pattern, 64);
		size -= 64;
		to += 64;
	}

	/* and the rest */

	if(size)
		flash_safe_write(mtd, to, pattern, size);

	return size;
}


static void
intrep_erase_callback(struct erase_info *done)
{
	wait_queue_head_t *wait_q;

	wait_q = (wait_queue_head_t *)done->priv;

	wake_up(wait_q);
}


static int
flash_erase_region(struct mtd_info *mtd, loff_t start,
		   size_t size)
{
	struct erase_info *erase;
	DECLARE_WAITQUEUE(wait, current);
	wait_queue_head_t wait_q;

	erase = kmalloc(sizeof(struct erase_info), GFP_KERNEL);
	if (!erase)
		return -ENOMEM;

	init_waitqueue_head(&wait_q);

	erase->mtd = mtd;
	erase->callback = intrep_erase_callback;
	erase->addr = start;
	erase->len = size;
	erase->priv = (u_long)&wait_q;

	/* FIXME: Use TASK_INTERRUPTIBLE and deal with being interrupted */
	set_current_state(TASK_UNINTERRUPTIBLE);
	add_wait_queue(&wait_q, &wait);

	if (mtd->erase(mtd, erase) < 0) {
		set_current_state(TASK_RUNNING);
		remove_wait_queue(&wait_q, &wait);
		kfree(erase);

		printk(KERN_WARNING "flash: erase of region [0x%lx, 0x%lx] "
		       "totally failed\n", (long)start, (long)start + size);

		return -1;
	}

	schedule(); /* Wait for flash to finish. */
	remove_wait_queue(&wait_q, &wait);

	kfree(erase);

	return 0;
}

/* This routine calculates checksums in JFFS.  */
static __u32
jffs_checksum(const void *data, int size)
{
	__u32 sum = 0;
	__u8 *ptr = (__u8 *)data;
	while (size-- > 0) {
		sum += *ptr++;
	}
	D3(printk(", result: 0x%08x\n", sum));
	return sum;
}


static int
jffs_checksum_flash(struct mtd_info *mtd, loff_t start, int size, __u32 *result)
{
	__u32 sum = 0;
	loff_t ptr = start;
	__u8 *read_buf;
	int i, length;

	/* Allocate read buffer */
	read_buf = (__u8 *) kmalloc (sizeof(__u8) * 4096, GFP_KERNEL);
	if (!read_buf) {
		printk(KERN_NOTICE "kmalloc failed in jffs_checksum_flash()\n");
		return -ENOMEM;
	}
	/* Loop until checksum done */
	while (size) {
		/* Get amount of data to read */
		if (size < 4096)
			length = size;
		else
			length = 4096;

		/* Perform flash read */
		D3(printk(KERN_NOTICE "jffs_checksum_flash\n"));
		flash_safe_read(mtd, ptr, &read_buf[0], length);

		/* Compute checksum */
		for (i=0; i < length ; i++)
			sum += read_buf[i];

		/* Update pointer and size */
		size -= length;
		ptr += length;
	}

	/* Free read buffer */
	kfree(read_buf);

	/* Return result */
	D3(printk("checksum result: 0x%08x\n", sum));
	*result = sum;
	return 0;
}

static __inline__ void jffs_fm_write_lock(struct jffs_fmcontrol *fmc)
{
  //	down(&fmc->wlock);
}

static __inline__ void jffs_fm_write_unlock(struct jffs_fmcontrol *fmc)
{
  //	up(&fmc->wlock);
}


/* Create and initialize a new struct jffs_file.  */
static struct jffs_file *
jffs_create_file(struct jffs_control *c,
		 const struct jffs_raw_inode *raw_inode)
{
	struct jffs_file *f;

	if (!(f = kzalloc(sizeof(*f), GFP_KERNEL))) {
		D(printk("jffs_create_file(): Failed!\n"));
		return NULL;
	}
	no_jffs_file++;
	f->ino = raw_inode->ino;
	f->pino = raw_inode->pino;
	f->nlink = raw_inode->nlink;
	f->deleted = raw_inode->deleted;
	f->c = c;

	return f;
}


/* Build a control block for the file system.  */
static struct jffs_control *
jffs_create_control(struct super_block *sb)
{
	struct jffs_control *c;
	register int s = sizeof(struct jffs_control);
	int i;
	D(char *t = 0);

	D2(printk("jffs_create_control()\n"));

	if (!(c = kmalloc(s, GFP_KERNEL))) {
		goto fail_control;
	}
	DJM(no_jffs_control++);
	c->root = NULL;
	c->gc_task = NULL;
	c->hash_len = JFFS_HASH_SIZE;
	s = sizeof(struct list_head) * c->hash_len;
	if (!(c->hash = kmalloc(s, GFP_KERNEL))) {
		goto fail_hash;
	}
	DJM(no_hash++);
	for (i = 0; i < c->hash_len; i++)
		INIT_LIST_HEAD(&c->hash[i]);
	if (!(c->fmc = jffs_build_begin(c, MINOR(sb->s_dev)))) {
		goto fail_fminit;
	}
	c->next_ino = JFFS_MIN_INO + 1;
	c->delete_list = (struct jffs_delete_list *) 0;
	return c;

fail_fminit:
	D(t = "c->fmc");
fail_hash:
	kfree(c);
	DJM(no_jffs_control--);
	D(t = t ? t : "c->hash");
fail_control:
	D(t = t ? t : "control");
	D(printk("jffs_create_control(): Allocation failed: (%s)\n", t));
	return (struct jffs_control *)0;
}


/* Clean up all data structures associated with the file system.  */
void
jffs_cleanup_control(struct jffs_control *c)
{
	D2(printk("jffs_cleanup_control()\n"));

	if (!c) {
		D(printk("jffs_cleanup_control(): c == NULL !!!\n"));
		return;
	}

	while (c->delete_list) {
		struct jffs_delete_list *delete_list_element;
		delete_list_element = c->delete_list;
		c->delete_list = c->delete_list->next;
		kfree(delete_list_element);
	}

	/* Free all files and nodes.  */
	if (c->hash) {
		jffs_foreach_file(c, jffs_free_node_list);
		jffs_foreach_file(c, jffs_free_file);
		kfree(c->hash);
		DJM(no_hash--);
	}
	jffs_cleanup_fmcontrol(c->fmc);
	kfree(c);
	DJM(no_jffs_control--);
	D3(printk("jffs_cleanup_control(): Leaving...\n"));
}


/* This function adds a virtual root node to the in-RAM representation.
   Called by jffs_build_fs().  */
static int
jffs_add_virtual_root(struct jffs_control *c)
{
	struct jffs_file *root;
	struct jffs_node *node;

	D2(printk("jffs_add_virtual_root(): "
		  "Creating a virtual root directory.\n"));

	if (!(root = kzalloc(sizeof(struct jffs_file), GFP_KERNEL))) {
		return -ENOMEM;
	}
	no_jffs_file++;
	if (!(node = jffs_alloc_node())) {
		kfree(root);
		no_jffs_file--;
		return -ENOMEM;
	}
	DJM(no_jffs_node++);
	memset(node, 0, sizeof(struct jffs_node));
	node->ino = JFFS_MIN_INO;
	root->ino = JFFS_MIN_INO;
	root->mode = S_IFDIR | S_IRWXU | S_IRGRP
		     | S_IXGRP | S_IROTH | S_IXOTH;
	root->atime = root->mtime = root->ctime = get_seconds();
	root->nlink = 1;
	root->c = c;
	root->version_head = root->version_tail = node;
	jffs_insert_file_into_hash(root);
	return 0;
}


/* This is where the file system is built and initialized.  */
int
jffs_build_fs(struct super_block *sb)
{
	struct jffs_control *c;
	int err = 0;

	D2(printk("jffs_build_fs()\n"));

	if (!(c = jffs_create_control(sb))) {
		return -ENOMEM;
	}
	c->building_fs = 1;
	c->sb = sb;
	if ((err = jffs_scan_flash(c)) < 0) {
		if(err == -EAGAIN){
			/* scan_flash() wants us to try once more. A flipping 
			   bits sector was detect in the middle of the scan flash.
			   Clean up old allocated memory before going in.
			*/
			D1(printk("jffs_build_fs: Cleaning up all control structures,"
				  " reallocating them and trying mount again.\n"));
			jffs_cleanup_control(c);
			if (!(c = jffs_create_control(sb))) {
				return -ENOMEM;
			}
			c->building_fs = 1;
			c->sb = sb;

			if ((err = jffs_scan_flash(c)) < 0) {
				goto jffs_build_fs_fail;
			}			
		}else{
			goto jffs_build_fs_fail;
		}
	}

	/* Add a virtual root node if no one exists.  */
	if (!jffs_find_file(c, JFFS_MIN_INO)) {
		if ((err = jffs_add_virtual_root(c)) < 0) {
			goto jffs_build_fs_fail;
		}
	}

	while (c->delete_list) {
		struct jffs_file *f;
		struct jffs_delete_list *delete_list_element;

		if ((f = jffs_find_file(c, c->delete_list->ino))) {
			f->deleted = 1;
		}
		delete_list_element = c->delete_list;
		c->delete_list = c->delete_list->next;
		kfree(delete_list_element);
	}

	/* Remove deleted nodes.  */
	if ((err = jffs_foreach_file(c, jffs_possibly_delete_file)) < 0) {
		printk(KERN_ERR "JFFS: Failed to remove deleted nodes.\n");
		goto jffs_build_fs_fail;
	}
	/* Remove redundant nodes.  (We are not interested in the
	   return value in this case.)  */
	jffs_foreach_file(c, jffs_remove_redundant_nodes);
	/* Try to build a tree from all the nodes.  */
	if ((err = jffs_foreach_file(c, jffs_insert_file_into_tree)) < 0) {
		printk("JFFS: Failed to build tree.\n");
		goto jffs_build_fs_fail;
	}
	/* Compute the sizes of all files in the filesystem.  Adjust if
	   necessary.  */
	if ((err = jffs_foreach_file(c, jffs_build_file)) < 0) {
		printk("JFFS: Failed to build file system.\n");
		goto jffs_build_fs_fail;
	}
	sb->s_fs_info = (void *)c;
	c->building_fs = 0;

	D1(jffs_print_hash_table(c));
	D1(jffs_print_tree(c->root, 0));

	return 0;

jffs_build_fs_fail:
	jffs_cleanup_control(c);
	return err;
} /* jffs_build_fs()  */


/*
  This checks for sectors that were being erased in their previous 
  lifetimes and for some reason or the other (power fail etc.), 
  the erase cycles never completed.
  As the flash array would have reverted back to read status, 
  these sectors are detected by the symptom of the "flipping bits",
  i.e. bits being read back differently from the same location in
  flash if read multiple times.
  The only solution to this is to re-erase the entire
  sector.
  Unfortunately detecting "flipping bits" is not a simple exercise
  as a bit may be read back at 1 or 0 depending on the alignment 
  of the stars in the universe.
  The level of confidence is in direct proportion to the number of 
  scans done. By power fail testing I (Vipin) have been able to 
  proove that reading twice is not enough.
  Maybe 4 times? Change NUM_REREADS to a higher number if you want
  a (even) higher degree of confidence in your mount process. 
  A higher number would of course slow down your mount.
*/
static int check_partly_erased_sectors(struct jffs_fmcontrol *fmc){

#define NUM_REREADS             4 /* see note above */
#define READ_AHEAD_BYTES        4096 /* must be a multiple of 4, 
					usually set to kernel page size */

	__u8 *read_buf1;
	__u8 *read_buf2;

	int err = 0;
	int retlen;
	int i;
	int cnt;
	__u32 offset;
	loff_t pos = 0;
	loff_t end = fmc->flash_size;


	/* Allocate read buffers */
	read_buf1 = (__u8 *) kmalloc (sizeof(__u8) * READ_AHEAD_BYTES, GFP_KERNEL);
	if (!read_buf1)
		return -ENOMEM;

	read_buf2 = (__u8 *) kmalloc (sizeof(__u8) * READ_AHEAD_BYTES, GFP_KERNEL);
	if (!read_buf2) {
		kfree(read_buf1);
		return -ENOMEM;
	}

 CHECK_NEXT:
	while(pos < end){
		
		D1(printk("check_partly_erased_sector():checking sector which contains"
			  " offset 0x%x for flipping bits..\n", (__u32)pos));
		
		retlen = flash_safe_read(fmc->mtd, pos,
					 &read_buf1[0], READ_AHEAD_BYTES);
		retlen &= ~3;
		
		for(cnt = 0; cnt < NUM_REREADS; cnt++){
			(void)flash_safe_read(fmc->mtd, pos,
					      &read_buf2[0], READ_AHEAD_BYTES);
			
			for (i=0 ; i < retlen ; i+=4) {
				/* buffers MUST match, double word for word! */
				if(*((__u32 *) &read_buf1[i]) !=
				   *((__u32 *) &read_buf2[i])
				   ){
				        /* flipping bits detected, time to erase sector */
					/* This will help us log some statistics etc. */
					D1(printk("Flipping bits detected in re-read round:%i of %i\n",
					       cnt, NUM_REREADS));
					D1(printk("check_partly_erased_sectors:flipping bits detected"
						  " @offset:0x%x(0x%x!=0x%x)\n",
						  (__u32)pos+i, *((__u32 *) &read_buf1[i]), 
						  *((__u32 *) &read_buf2[i])));
					
				        /* calculate start of present sector */
					offset = (((__u32)pos+i)/(__u32)fmc->sector_size) * (__u32)fmc->sector_size;
					
					D1(printk("check_partly_erased_sector():erasing sector starting 0x%x.\n",
						  offset));
					
					if (flash_erase_region(fmc->mtd,
							       offset, fmc->sector_size) < 0) {
						printk(KERN_ERR "JFFS: Erase of flash failed. "
						       "offset = %u, erase_size = %d\n",
						       offset , fmc->sector_size);
						
						err = -EIO;
						goto returnBack;

					}else{
						D1(printk("JFFS: Erase of flash sector @0x%x successful.\n",
						       offset));
						/* skip ahead to the next sector */
						pos = (((__u32)pos+i)/(__u32)fmc->sector_size) * (__u32)fmc->sector_size;
						pos += fmc->sector_size;
						goto CHECK_NEXT;
					}
				}
			}
		}
		pos += READ_AHEAD_BYTES;
	}

 returnBack:
	kfree(read_buf1);
	kfree(read_buf2);

	D2(printk("check_partly_erased_sector():Done checking all sectors till offset 0x%x for flipping bits.\n",
		  (__u32)pos));

	return err;

}/* end check_partly_erased_sectors() */


/* Scan the whole flash memory in order to find all nodes in the
   file systems.  */
static int
jffs_scan_flash(struct jffs_control *c)
{
	char name[JFFS_MAX_NAME_LEN + 2];
	struct jffs_raw_inode raw_inode;
	struct jffs_node *node = NULL;
	struct jffs_fmcontrol *fmc = c->fmc;
	__u32 checksum;
	__u8 tmp_accurate;
	__u16 tmp_chksum;
	__u32 deleted_file;
	loff_t pos = 0;
	loff_t start;
	loff_t test_start;
	loff_t end = fmc->flash_size;
	__u8 *read_buf;
	int i, len, retlen;
	__u32 offset;

	__u32 free_chunk_size1;
	__u32 free_chunk_size2;

	
#define NUMFREEALLOWED     2        /* 2 chunks of at least erase size space allowed */
	int num_free_space = 0;       /* Flag err if more than TWO
				       free blocks found. This is NOT allowed
				       by the current jffs design.
				    */
	int num_free_spc_not_accp = 0; /* For debugging purposed keep count 
					of how much free space was rejected and
					marked dirty
				     */

	D1(printk("jffs_scan_flash(): start pos = 0x%lx, end = 0x%lx\n",
		  (long)pos, (long)end));

	flash_safe_acquire(fmc->mtd);

	/*
	  check and make sure that any sector does not suffer
	  from the "partly erased, bit flipping syndrome" (TM Vipin :)
	  If so, offending sectors will be erased.
	*/
	if(check_partly_erased_sectors(fmc) < 0){

		flash_safe_release(fmc->mtd);
		return -EIO; /* bad, bad, bad error. Cannot continue.*/
	}

	/* Allocate read buffer */
	read_buf = (__u8 *) kmalloc (sizeof(__u8) * 4096, GFP_KERNEL);
	if (!read_buf) {
		flash_safe_release(fmc->mtd);
		return -ENOMEM;
	}
			      
	/* Start the scan.  */
	while (pos < end) {
		deleted_file = 0;

		/* Remember the position from where we started this scan.  */
		start = pos;

		switch (flash_read_u32(fmc->mtd, pos)) {
		case JFFS_EMPTY_BITMASK:
			/* We have found 0xffffffff at this position.  We have to
			   scan the rest of the flash till the end or till
			   something else than 0xffffffff is found.
		           Keep going till we do not find JFFS_EMPTY_BITMASK 
			   anymore */

			D1(printk("jffs_scan_flash(): 0xffffffff at pos 0x%lx.\n",
				  (long)pos));

		        while(pos < end){

			      len = end - pos < 4096 ? end - pos : 4096;
			      
			      retlen = flash_safe_read(fmc->mtd, pos,
						 &read_buf[0], len);

			      retlen &= ~3;
			      
			      for (i=0 ; i < retlen ; i+=4, pos += 4) {
				      if(*((__u32 *) &read_buf[i]) !=
					 JFFS_EMPTY_BITMASK)
					break;
			      }
			      if (i == retlen)
				    continue;
			      else
				    break;
			}

			D1(printk("jffs_scan_flash():0xffffffff ended at pos 0x%lx.\n",
				  (long)pos));
			
			/* If some free space ends in the middle of a sector,
			   treat it as dirty rather than clean.
			   This is to handle the case where one thread 
			   allocated space for a node, but didn't get to
			   actually _write_ it before power was lost, leaving
			   a gap in the log. Shifting all node writes into
			   a single kernel thread will fix the original problem.
			*/
			if ((__u32) pos % fmc->sector_size) {
				/* If there was free space in previous 
				   sectors, don't mark that dirty too - 
				   only from the beginning of this sector
				   (or from start) 
				*/

			        test_start = pos & ~(fmc->sector_size-1); /* end of last sector */

				if (start < test_start) {

				        /* free space started in the previous sector! */

					if((num_free_space < NUMFREEALLOWED) && 
					   ((unsigned int)(test_start - start) >= fmc->sector_size)){

				                /*
						  Count it in if we are still under NUMFREEALLOWED *and* it is 
						  at least 1 erase sector in length. This will keep us from 
						  picking any little ole' space as "free".
						*/
					  
					        D1(printk("Reducing end of free space to 0x%x from 0x%x\n",
							  (unsigned int)test_start, (unsigned int)pos));

						D1(printk("Free space accepted: Starting 0x%x for 0x%x bytes\n",
							  (unsigned int) start,
							  (unsigned int)(test_start - start)));

						/* below, space from "start" to "pos" will be marked dirty. */
						start = test_start; 
						
						/* Being in here means that we have found at least an entire 
						   erase sector size of free space ending on a sector boundary.
						   Keep track of free spaces accepted.
						*/
						num_free_space++;
					}else{
					        num_free_spc_not_accp++;
					        D1(printk("Free space (#%i) found but *Not* accepted: Starting"
							  " 0x%x for 0x%x bytes\n",
							  num_free_spc_not_accp, (unsigned int)start, 
							  (unsigned int)((unsigned int)(pos & ~(fmc->sector_size-1)) - (unsigned int)start)));
					        
					}
					
				}
				if((((__u32)(pos - start)) != 0)){

				        D1(printk("Dirty space: Starting 0x%x for 0x%x bytes\n",
						  (unsigned int) start, (unsigned int) (pos - start)));
					jffs_fmalloced(fmc, (__u32) start,
						       (__u32) (pos - start), NULL);
				}else{
					/* "Flipping bits" detected. This means that our scan for them
					   did not catch this offset. See check_partly_erased_sectors() for
					   more info.
					*/
				        
					D1(printk("jffs_scan_flash():wants to allocate dirty flash "
						  "space for 0 bytes.\n"));
					D1(printk("jffs_scan_flash(): Flipping bits! We will free "
						  "all allocated memory, erase this sector and remount\n"));

					/* calculate start of present sector */
					offset = (((__u32)pos)/(__u32)fmc->sector_size) * (__u32)fmc->sector_size;
					
					D1(printk("jffs_scan_flash():erasing sector starting 0x%x.\n",
						  offset));
					
					if (flash_erase_region(fmc->mtd,
							       offset, fmc->sector_size) < 0) {
						printk(KERN_ERR "JFFS: Erase of flash failed. "
						       "offset = %u, erase_size = %d\n",
						       offset , fmc->sector_size);

						flash_safe_release(fmc->mtd);
						kfree(read_buf);
						return -1; /* bad, bad, bad! */

					}
					flash_safe_release(fmc->mtd);
					kfree(read_buf);

					return -EAGAIN; /* erased offending sector. Try mount one more time please. */
				}
			}else{
			        /* Being in here means that we have found free space that ends on an erase sector
				   boundary.
				   Count it in if we are still under NUMFREEALLOWED *and* it is at least 1 erase 
				   sector in length. This will keep us from picking any little ole' space as "free".
				 */
			         if((num_free_space < NUMFREEALLOWED) && 
				    ((unsigned int)(pos - start) >= fmc->sector_size)){
				           /* We really don't do anything to mark space as free, except *not* 
					      mark it dirty and just advance the "pos" location pointer. 
					      It will automatically be picked up as free space.
					    */ 
				           num_free_space++;
				           D1(printk("Free space accepted: Starting 0x%x for 0x%x bytes\n",
						     (unsigned int) start, (unsigned int) (pos - start)));
				 }else{
				         num_free_spc_not_accp++;
					 D1(printk("Free space (#%i) found but *Not* accepted: Starting "
						   "0x%x for 0x%x bytes\n", num_free_spc_not_accp, 
						   (unsigned int) start, 
						   (unsigned int) (pos - start)));
					 
					 /* Mark this space as dirty. We already have our free space. */
					 D1(printk("Dirty space: Starting 0x%x for 0x%x bytes\n",
						   (unsigned int) start, (unsigned int) (pos - start)));
					 jffs_fmalloced(fmc, (__u32) start,
							(__u32) (pos - start), NULL);				           
				 }
				 
			}
			if(num_free_space > NUMFREEALLOWED){
			         printk(KERN_WARNING "jffs_scan_flash(): Found free space "
					"number %i. Only %i free space is allowed.\n",
					num_free_space, NUMFREEALLOWED);			      
			}
			continue;

		case JFFS_DIRTY_BITMASK:
			/* We have found 0x00000000 at this position.  Scan as far
			   as possible to find out how much is dirty.  */
			D1(printk("jffs_scan_flash(): 0x00000000 at pos 0x%lx.\n",
				  (long)pos));
			for (; pos < end
			       && JFFS_DIRTY_BITMASK == flash_read_u32(fmc->mtd, pos);
			     pos += 4);
			D1(printk("jffs_scan_flash(): 0x00 ended at "
				  "pos 0x%lx.\n", (long)pos));
			jffs_fmalloced(fmc, (__u32) start,
				       (__u32) (pos - start), NULL);
			continue;

		case JFFS_MAGIC_BITMASK:
			/* We have probably found a new raw inode.  */
			break;

		default:
		bad_inode:
			/* We're f*cked.  This is not solved yet.  We have
			   to scan for the magic pattern.  */
			D1(printk("*************** Dirty flash memory or "
				  "bad inode: "
				  "hexdump(pos = 0x%lx, len = 128):\n",
				  (long)pos));
			D1(jffs_hexdump(fmc->mtd, pos, 128));

			for (pos += 4; pos < end; pos += 4) {
				switch (flash_read_u32(fmc->mtd, pos)) {
				case JFFS_MAGIC_BITMASK:
				case JFFS_EMPTY_BITMASK:
					/* handle these in the main switch() loop */
					goto cont_scan;

				default:
					break;
				}
			}

			cont_scan:
			/* First, mark as dirty the region
			   which really does contain crap. */
			jffs_fmalloced(fmc, (__u32) start,
				       (__u32) (pos - start),
				       NULL);
			
			continue;
		}/* switch */

		/* We have found the beginning of an inode.  Create a
		   node for it unless there already is one available.  */
		if (!node) {
			if (!(node = jffs_alloc_node())) {
				/* Free read buffer */
				kfree(read_buf);

				/* Release the flash device */
				flash_safe_release(fmc->mtd);
	
				return -ENOMEM;
			}
			DJM(no_jffs_node++);
		}

		/* Read the next raw inode.  */

		flash_safe_read(fmc->mtd, pos, (u_char *) &raw_inode,
				sizeof(struct jffs_raw_inode));

		/* When we compute the checksum for the inode, we never
		   count the 'accurate' or the 'checksum' fields.  */
		tmp_accurate = raw_inode.accurate;
		tmp_chksum = raw_inode.chksum;
		raw_inode.accurate = 0;
		raw_inode.chksum = 0;
		checksum = jffs_checksum(&raw_inode,
					 sizeof(struct jffs_raw_inode));
		raw_inode.accurate = tmp_accurate;
		raw_inode.chksum = tmp_chksum;

		D3(printk("*** We have found this raw inode at pos 0x%lx "
			  "on the flash:\n", (long)pos));
		D3(jffs_print_raw_inode(&raw_inode));

		if (checksum != raw_inode.chksum) {
			D1(printk("jffs_scan_flash(): Bad checksum: "
				  "checksum = %u, "
				  "raw_inode.chksum = %u\n",
				  checksum, raw_inode.chksum));
			pos += sizeof(struct jffs_raw_inode);
			jffs_fmalloced(fmc, (__u32) start,
				       (__u32) (pos - start), NULL);
			/* Reuse this unused struct jffs_node.  */
			continue;
		}

		/* Check the raw inode read so far.  Start with the
		   maximum length of the filename.  */
		if (raw_inode.nsize > JFFS_MAX_NAME_LEN) {
			printk(KERN_WARNING "jffs_scan_flash: Found a "
			       "JFFS node with name too large\n");
			goto bad_inode;
		}

		if (raw_inode.rename && raw_inode.dsize != sizeof(__u32)) {
			printk(KERN_WARNING "jffs_scan_flash: Found a "
			       "rename node with dsize %u.\n",
			       raw_inode.dsize);
			jffs_print_raw_inode(&raw_inode);
			goto bad_inode;
		}

		/* The node's data segment should not exceed a
		   certain length.  */
		if (raw_inode.dsize > fmc->max_chunk_size) {
			printk(KERN_WARNING "jffs_scan_flash: Found a "
			       "JFFS node with dsize (0x%x) > max_chunk_size (0x%x)\n",
			       raw_inode.dsize, fmc->max_chunk_size);
			goto bad_inode;
		}

		pos += sizeof(struct jffs_raw_inode);

		/* This shouldn't be necessary because a node that
		   violates the flash boundaries shouldn't be written
		   in the first place. */
		if (pos >= end) {
			goto check_node;
		}

		/* Read the name.  */
		*name = 0;
		if (raw_inode.nsize) {
		        flash_safe_read(fmc->mtd, pos, name, raw_inode.nsize);
			name[raw_inode.nsize] = '\0';
			pos += raw_inode.nsize
			       + JFFS_GET_PAD_BYTES(raw_inode.nsize);
			D3(printk("name == \"%s\"\n", name));
			checksum = jffs_checksum(name, raw_inode.nsize);
			if (checksum != raw_inode.nchksum) {
				D1(printk("jffs_scan_flash(): Bad checksum: "
					  "checksum = %u, "
					  "raw_inode.nchksum = %u\n",
					  checksum, raw_inode.nchksum));
				jffs_fmalloced(fmc, (__u32) start,
					       (__u32) (pos - start), NULL);
				/* Reuse this unused struct jffs_node.  */
				continue;
			}
			if (pos >= end) {
				goto check_node;
			}
		}

		/* Read the data, if it exists, in order to be sure it
		   matches the checksum.  */
		if (raw_inode.dsize) {
			if (raw_inode.rename) {
				deleted_file = flash_read_u32(fmc->mtd, pos);
			}
			if (jffs_checksum_flash(fmc->mtd, pos, raw_inode.dsize, &checksum)) {
				printk("jffs_checksum_flash() failed to calculate a checksum\n");
				jffs_fmalloced(fmc, (__u32) start,
					       (__u32) (pos - start), NULL);
				/* Reuse this unused struct jffs_node.  */
				continue;
			}				
			pos += raw_inode.dsize
			       + JFFS_GET_PAD_BYTES(raw_inode.dsize);

			if (checksum != raw_inode.dchksum) {
				D1(printk("jffs_scan_flash(): Bad checksum: "
					  "checksum = %u, "
					  "raw_inode.dchksum = %u\n",
					  checksum, raw_inode.dchksum));
				jffs_fmalloced(fmc, (__u32) start,
					       (__u32) (pos - start), NULL);
				/* Reuse this unused struct jffs_node.  */
				continue;
			}
		}

		check_node:

		/* Remember the highest inode number in the whole file
		   system.  This information will be used when assigning
		   new files new inode numbers.  */
		if (c->next_ino <= raw_inode.ino) {
			c->next_ino = raw_inode.ino + 1;
		}

		if (raw_inode.accurate) {
			int err;
			node->data_offset = raw_inode.offset;
			node->data_size = raw_inode.dsize;
			node->removed_size = raw_inode.rsize;
			/* Compute the offset to the actual data in the
			   on-flash node.  */
			node->fm_offset
			= sizeof(struct jffs_raw_inode)
			  + raw_inode.nsize
			  + JFFS_GET_PAD_BYTES(raw_inode.nsize);
			node->fm = jffs_fmalloced(fmc, (__u32) start,
						  (__u32) (pos - start),
						  node);
			if (!node->fm) {
				D(printk("jffs_scan_flash(): !node->fm\n"));
				jffs_free_node(node);
				DJM(no_jffs_node--);

				/* Free read buffer */
				kfree(read_buf);

				/* Release the flash device */
				flash_safe_release(fmc->mtd);

				return -ENOMEM;
			}
			if ((err = jffs_insert_node(c, NULL, &raw_inode,
						    name, node)) < 0) {
				printk("JFFS: Failed to handle raw inode. "
				       "(err = %d)\n", err);
				break;
			}
			if (raw_inode.rename) {
				struct jffs_delete_list *dl
				= (struct jffs_delete_list *)
				  kmalloc(sizeof(struct jffs_delete_list),
					  GFP_KERNEL);
				if (!dl) {
					D(printk("jffs_scan_flash: !dl\n"));
					jffs_free_node(node);
					DJM(no_jffs_node--);

					/* Release the flash device */
					flash_safe_release(fmc->flash_part);

					/* Free read buffer */
					kfree(read_buf);

					return -ENOMEM;
				}
				dl->ino = deleted_file;
				dl->next = c->delete_list;
				c->delete_list = dl;
				node->data_size = 0;
			}
			D3(jffs_print_node(node));
			node = NULL; /* Don't free the node!  */
		}
		else {
			jffs_fmalloced(fmc, (__u32) start,
				       (__u32) (pos - start), NULL);
			D3(printk("jffs_scan_flash(): Just found an obsolete "
				  "raw_inode. Continuing the scan...\n"));
			/* Reuse this unused struct jffs_node.  */
		}
	}

	if (node) {
		jffs_free_node(node);
		DJM(no_jffs_node--);
	}
	jffs_build_end(fmc);

	/* Free read buffer */
	kfree(read_buf);

	if(!num_free_space){
	        printk(KERN_WARNING "jffs_scan_flash(): Did not find even a single "
		       "chunk of free space. This is BAD!\n");
	}

	/* Return happy */
	D3(printk("jffs_scan_flash(): Leaving...\n"));
	flash_safe_release(fmc->mtd);

	/* This is to trap the "free size accounting screwed error. */
	free_chunk_size1 = jffs_free_size1(fmc);
	free_chunk_size2 = jffs_free_size2(fmc);

	if (free_chunk_size1 + free_chunk_size2 != fmc->free_size) {

		printk(KERN_WARNING "jffs_scan_falsh():Free size accounting screwed\n");
		printk(KERN_WARNING "jfffs_scan_flash():free_chunk_size1 == 0x%x, "
		       "free_chunk_size2 == 0x%x, fmc->free_size == 0x%x\n", 
		       free_chunk_size1, free_chunk_size2, fmc->free_size);

		return -1; /* Do NOT mount f/s so that we can inspect what happened.
			      Mounting this  screwed up f/s will screw us up anyway.
			    */
	}	

	return 0; /* as far as we are concerned, we are happy! */
} /* jffs_scan_flash()  */


/* Insert any kind of node into the file system.  Take care of data
   insertions and deletions.  Also remove redundant information. The
   memory allocated for the `name' is regarded as "given away" in the
   caller's perspective.  */
int
jffs_insert_node(struct jffs_control *c, struct jffs_file *f,
		 const struct jffs_raw_inode *raw_inode,
		 const char *name, struct jffs_node *node)
{
	int update_name = 0;
	int insert_into_tree = 0;

	D2(printk("jffs_insert_node(): ino = %u, version = %u, "
		  "name = \"%s\", deleted = %d\n",
		  raw_inode->ino, raw_inode->version,
		  ((name && *name) ? name : ""), raw_inode->deleted));

	/* If there doesn't exist an associated jffs_file, then
	   create, initialize and insert one into the file system.  */
	if (!f && !(f = jffs_find_file(c, raw_inode->ino))) {
		if (!(f = jffs_create_file(c, raw_inode))) {
			return -ENOMEM;
		}
		jffs_insert_file_into_hash(f);
		insert_into_tree = 1;
	}
	node->ino = raw_inode->ino;
	node->version = raw_inode->version;
	node->data_size = raw_inode->dsize;
	node->fm_offset = sizeof(struct jffs_raw_inode) + raw_inode->nsize
			  + JFFS_GET_PAD_BYTES(raw_inode->nsize);
	node->name_size = raw_inode->nsize;

	/* Now insert the node at the correct position into the file's
	   version list.  */
	if (!f->version_head) {
		/* This is the first node.  */
		f->version_head = node;
		f->version_tail = node;
		node->version_prev = NULL;
		node->version_next = NULL;
		f->highest_version = node->version;
		update_name = 1;
		f->mode = raw_inode->mode;
		f->uid = raw_inode->uid;
		f->gid = raw_inode->gid;
		f->atime = raw_inode->atime;
		f->mtime = raw_inode->mtime;
		f->ctime = raw_inode->ctime;
	}
	else if ((f->highest_version < node->version)
		 || (node->version == 0)) {
		/* Insert at the end of the list.  I.e. this node is the
		   newest one so far.  */
		node->version_prev = f->version_tail;
		node->version_next = NULL;
		f->version_tail->version_next = node;
		f->version_tail = node;
		f->highest_version = node->version;
		update_name = 1;
		f->pino = raw_inode->pino;
		f->mode = raw_inode->mode;
		f->uid = raw_inode->uid;
		f->gid = raw_inode->gid;
		f->atime = raw_inode->atime;
		f->mtime = raw_inode->mtime;
		f->ctime = raw_inode->ctime;
	}
	else if (f->version_head->version > node->version) {
		/* Insert at the bottom of the list.  */
		node->version_prev = NULL;
		node->version_next = f->version_head;
		f->version_head->version_prev = node;
		f->version_head = node;
		if (!f->name) {
			update_name = 1;
		}
	}
	else {
		struct jffs_node *n;
		int newer_name = 0;
		/* Search for the insertion position starting from
		   the tail (newest node).  */
		for (n = f->version_tail; n; n = n->version_prev) {
			if (n->version < node->version) {
				node->version_prev = n;
				node->version_next = n->version_next;
				node->version_next->version_prev = node;
				n->version_next = node;
				if (!newer_name) {
					update_name = 1;
				}
				break;
			}
			if (n->name_size) {
				newer_name = 1;
			}
		}
	}

	/* Deletion is irreversible. If any 'deleted' node is ever
	   written, the file is deleted */
	if (raw_inode->deleted)
		f->deleted = raw_inode->deleted;

	/* Perhaps update the name.  */
	if (raw_inode->nsize && update_name && name && *name && (name != f->name)) {
		if (f->name) {
			kfree(f->name);
			DJM(no_name--);
		}
		if (!(f->name = (char *) kmalloc(raw_inode->nsize + 1,
						 GFP_KERNEL))) {
			return -ENOMEM;
		}
		DJM(no_name++);
		memcpy(f->name, name, raw_inode->nsize);
		f->name[raw_inode->nsize] = '\0';
		f->nsize = raw_inode->nsize;
		D3(printk("jffs_insert_node(): Updated the name of "
			  "the file to \"%s\".\n", name));
	}

	if (!c->building_fs) {
		D3(printk("jffs_insert_node(): ---------------------------"
			  "------------------------------------------- 1\n"));
		if (insert_into_tree) {
			jffs_insert_file_into_tree(f);
		}
		/* Once upon a time, we would call jffs_possibly_delete_file()
		   here. That causes an oops if someone's still got the file
		   open, so now we only do it in jffs_delete_inode()
		   -- dwmw2
		*/
		if (node->data_size || node->removed_size) {
			jffs_update_file(f, node);
		}
		jffs_remove_redundant_nodes(f);

		jffs_garbage_collect_trigger(c);

		D3(printk("jffs_insert_node(): ---------------------------"
			  "------------------------------------------- 2\n"));
	}

	return 0;
} /* jffs_insert_node()  */


/* Unlink a jffs_node from the version list it is in.  */
static inline void
jffs_unlink_node_from_version_list(struct jffs_file *f,
				   struct jffs_node *node)
{
	if (node->version_prev) {
		node->version_prev->version_next = node->version_next;
	} else {
		f->version_head = node->version_next;
	}
	if (node->version_next) {
		node->version_next->version_prev = node->version_prev;
	} else {
		f->version_tail = node->version_prev;
	}
}


/* Unlink a jffs_node from the range list it is in.  */
static inline void
jffs_unlink_node_from_range_list(struct jffs_file *f, struct jffs_node *node)
{
	if (node->range_prev) {
		node->range_prev->range_next = node->range_next;
	}
	else {
		f->range_head = node->range_next;
	}
	if (node->range_next) {
		node->range_next->range_prev = node->range_prev;
	}
	else {
		f->range_tail = node->range_prev;
	}
}


/* Function used by jffs_remove_redundant_nodes() below.  This function
   classifies what kind of information a node adds to a file.  */
static inline __u8
jffs_classify_node(struct jffs_node *node)
{
	__u8 mod_type = JFFS_MODIFY_INODE;

	if (node->name_size) {
		mod_type |= JFFS_MODIFY_NAME;
	}
	if (node->data_size || node->removed_size) {
		mod_type |= JFFS_MODIFY_DATA;
	}
	return mod_type;
}


/* Remove redundant nodes from a file.  Mark the on-flash memory
   as dirty.  */
static int
jffs_remove_redundant_nodes(struct jffs_file *f)
{
	struct jffs_node *newest_node;
	struct jffs_node *cur;
	struct jffs_node *prev;
	__u8 newest_type;
	__u8 mod_type;
	__u8 node_with_name_later = 0;

	if (!(newest_node = f->version_tail)) {
		return 0;
	}

	/* What does the `newest_node' modify?  */
	newest_type = jffs_classify_node(newest_node);
	node_with_name_later = newest_type & JFFS_MODIFY_NAME;

	D3(printk("jffs_remove_redundant_nodes(): ino: %u, name: \"%s\", "
		  "newest_type: %u\n", f->ino, (f->name ? f->name : ""),
		  newest_type));

	/* Traverse the file's nodes and determine which of them that are
	   superfluous.  Yeah, this might look very complex at first
	   glance but it is actually very simple.  */
	for (cur = newest_node->version_prev; cur; cur = prev) {
		prev = cur->version_prev;
		mod_type = jffs_classify_node(cur);
		if ((mod_type <= JFFS_MODIFY_INODE)
		    || ((newest_type & JFFS_MODIFY_NAME)
			&& (mod_type
			    <= (JFFS_MODIFY_INODE + JFFS_MODIFY_NAME)))
		    || (cur->data_size == 0 && cur->removed_size
			&& !cur->version_prev && node_with_name_later)) {
			/* Yes, this node is redundant. Remove it.  */
			D2(printk("jffs_remove_redundant_nodes(): "
				  "Removing node: ino: %u, version: %u, "
				  "mod_type: %u\n", cur->ino, cur->version,
				  mod_type));
			jffs_unlink_node_from_version_list(f, cur);
			jffs_fmfree(f->c->fmc, cur->fm, cur);
			jffs_free_node(cur);
			DJM(no_jffs_node--);
		}
		else {
			node_with_name_later |= (mod_type & JFFS_MODIFY_NAME);
		}
	}

	return 0;
}


/* Insert a file into the hash table.  */
static int
jffs_insert_file_into_hash(struct jffs_file *f)
{
	int i = f->ino % f->c->hash_len;

	D3(printk("jffs_insert_file_into_hash(): f->ino: %u\n", f->ino));

	list_add(&f->hash, &f->c->hash[i]);
	return 0;
}


/* Insert a file into the file system tree.  */
int
jffs_insert_file_into_tree(struct jffs_file *f)
{
	struct jffs_file *parent;

	D3(printk("jffs_insert_file_into_tree(): name: \"%s\"\n",
		  (f->name ? f->name : "")));

	if (!(parent = jffs_find_file(f->c, f->pino))) {
		if (f->pino == 0) {
			f->c->root = f;
			f->parent = NULL;
			f->sibling_prev = NULL;
			f->sibling_next = NULL;
			return 0;
		}
		else {
			D1(printk("jffs_insert_file_into_tree(): Found "
				  "inode with no parent and pino == %u\n",
				  f->pino));
			return -1;
		}
	}
	f->parent = parent;
	f->sibling_next = parent->children;
	if (f->sibling_next) {
		f->sibling_next->sibling_prev = f;
	}
	f->sibling_prev = NULL;
	parent->children = f;
	return 0;
}


/* Remove a file from the hash table.  */
static int
jffs_unlink_file_from_hash(struct jffs_file *f)
{
	D3(printk("jffs_unlink_file_from_hash(): f: 0x%p, "
		  "ino %u\n", f, f->ino));

	list_del(&f->hash);
	return 0;
}


/* Just remove the file from the parent's children.  Don't free
   any memory.  */
int
jffs_unlink_file_from_tree(struct jffs_file *f)
{
	D3(printk("jffs_unlink_file_from_tree(): ino: %d, pino: %d, name: "
		  "\"%s\"\n", f->ino, f->pino, (f->name ? f->name : "")));

	if (f->sibling_prev) {
		f->sibling_prev->sibling_next = f->sibling_next;
	}
	else if (f->parent) {
	        D3(printk("f->parent=%p\n", f->parent));
		f->parent->children = f->sibling_next;
	}
	if (f->sibling_next) {
		f->sibling_next->sibling_prev = f->sibling_prev;
	}
	return 0;
}


/* Find a file with its inode number.  */
struct jffs_file *
jffs_find_file(struct jffs_control *c, __u32 ino)
{
	struct jffs_file *f;
	int i = ino % c->hash_len;

	D3(printk("jffs_find_file(): ino: %u\n", ino));

	list_for_each_entry(f, &c->hash[i], hash) {
		if (ino != f->ino)
			continue;
		D3(printk("jffs_find_file(): Found file with ino "
			       "%u. (name: \"%s\")\n",
			       ino, (f->name ? f->name : ""));
		);
		return f;
	}
	D3(printk("jffs_find_file(): Didn't find file "
			 "with ino %u.\n", ino);
	);
	return NULL;
}


/* Find a file in a directory.  We are comparing the names.  */
struct jffs_file *
jffs_find_child(struct jffs_file *dir, const char *name, int len)
{
	struct jffs_file *f;

	D3(printk("jffs_find_child()\n"));

	for (f = dir->children; f; f = f->sibling_next) {
		if (!f->deleted && f->name
		    && !strncmp(f->name, name, len)
		    && f->name[len] == '\0') {
			break;
		}
	}

	D3(if (f) {
		printk("jffs_find_child(): Found \"%s\".\n", f->name);
	}
	else {
		char *copy = (char *) kmalloc(len + 1, GFP_KERNEL);
		if (copy) {
			memcpy(copy, name, len);
			copy[len] = '\0';
		}
		printk("jffs_find_child(): Didn't find the file \"%s\".\n",
		       (copy ? copy : ""));
		kfree(copy);
	});

	return f;
}


/* Write a raw inode that takes up a certain amount of space in the flash
   memory.  At the end of the flash device, there is often space that is
   impossible to use.  At these times we want to mark this space as not
   used.  In the cases when the amount of space is greater or equal than
   a struct jffs_raw_inode, we write a "dummy node" that takes up this
   space.  The space after the raw inode, if it exists, is left as it is.
   Since this space after the raw inode contains JFFS_EMPTY_BITMASK bytes,
   we can compute the checksum of it; we don't have to manipulate it any
   further.

   If the space left on the device is less than the size of a struct
   jffs_raw_inode, this space is filled with JFFS_DIRTY_BITMASK bytes.
   No raw inode is written this time.  */
static int
jffs_write_dummy_node(struct jffs_control *c, struct jffs_fm *dirty_fm)
{
	struct jffs_fmcontrol *fmc = c->fmc;
	int err;

	D1(printk("jffs_write_dummy_node(): dirty_fm->offset = 0x%08x, "
		  "dirty_fm->size = %u\n",
		  dirty_fm->offset, dirty_fm->size));

	if (dirty_fm->size >= sizeof(struct jffs_raw_inode)) {
		struct jffs_raw_inode raw_inode;
		memset(&raw_inode, 0, sizeof(struct jffs_raw_inode));
		raw_inode.magic = JFFS_MAGIC_BITMASK;
		raw_inode.dsize = dirty_fm->size
				  - sizeof(struct jffs_raw_inode);
		raw_inode.dchksum = raw_inode.dsize * 0xff;
		raw_inode.chksum
		= jffs_checksum(&raw_inode, sizeof(struct jffs_raw_inode));

		if ((err = flash_safe_write(fmc->mtd,
					    dirty_fm->offset,
					    (u_char *)&raw_inode,
					    sizeof(struct jffs_raw_inode)))
		    < 0) {
			printk(KERN_ERR "JFFS: jffs_write_dummy_node: "
			       "flash_safe_write failed!\n");
			return err;
		}
	}
	else {
		flash_safe_acquire(fmc->mtd);
		flash_memset(fmc->mtd, dirty_fm->offset, 0, dirty_fm->size);
		flash_safe_release(fmc->mtd);
	}

	D3(printk("jffs_write_dummy_node(): Leaving...\n"));
	return 0;
}


/* Write a raw inode, possibly its name and possibly some data.  */
int
jffs_write_node(struct jffs_control *c, struct jffs_node *node,
		struct jffs_raw_inode *raw_inode,
		const char *name, const unsigned char *data,
		int recoverable,
		struct jffs_file *f)
{
	struct jffs_fmcontrol *fmc = c->fmc;
	struct jffs_fm *fm;
	struct kvec node_iovec[4];
	unsigned long iovec_cnt;

	__u32 pos;
	int err;
	__u32 slack = 0;

	__u32 total_name_size = raw_inode->nsize
				+ JFFS_GET_PAD_BYTES(raw_inode->nsize);
	__u32 total_data_size = raw_inode->dsize
				+ JFFS_GET_PAD_BYTES(raw_inode->dsize);
	__u32 total_size = sizeof(struct jffs_raw_inode)
			   + total_name_size + total_data_size;
	
	/* If this node isn't something that will eventually let
	   GC free even more space, then don't allow it unless
	   there's at least max_chunk_size space still available
	*/
	if (!recoverable)
		slack = fmc->max_chunk_size;
		

	/* Fire the retrorockets and shoot the fruiton torpedoes, sir!  */

	ASSERT(if (!node) {
		printk("jffs_write_node(): node == NULL\n");
		return -EINVAL;
	});
	ASSERT(if (raw_inode && raw_inode->nsize && !name) {
		printk("*** jffs_write_node(): nsize = %u but name == NULL\n",
		       raw_inode->nsize);
		return -EINVAL;
	});

	D1(printk("jffs_write_node(): filename = \"%s\", ino = %u, "
		  "total_size = %u\n",
		  (name ? name : ""), raw_inode->ino,
		  total_size));

	jffs_fm_write_lock(fmc);

retry:
	fm = NULL;
	err = 0;
	while (!fm) {

		/* Deadlocks suck. */
		while(fmc->free_size < fmc->min_free_size + total_size + slack) {
			jffs_fm_write_unlock(fmc);
			if (!JFFS_ENOUGH_SPACE(c, total_size + slack))
				return -ENOSPC;
			jffs_fm_write_lock(fmc);
		}

		/* First try to allocate some flash memory.  */
		err = jffs_fmalloc(fmc, total_size, node, &fm);
		
		if (err == -ENOSPC) {
			/* Just out of space. GC and try again */
			if (fmc->dirty_size < fmc->sector_size) {
				D(printk("jffs_write_node(): jffs_fmalloc(0x%p, %u) "
					 "failed, no dirty space to GC\n", fmc,
					 total_size));
				return err;
			}
			
			D1(printk(KERN_INFO "jffs_write_node(): Calling jffs_garbage_collect_now()\n"));
			jffs_fm_write_unlock(fmc);
			if ((err = jffs_garbage_collect_now(c))) {
				D(printk("jffs_write_node(): jffs_garbage_collect_now() failed\n"));
				return err;
			}
			jffs_fm_write_lock(fmc);
			continue;
		} 

		if (err < 0) {
			jffs_fm_write_unlock(fmc);

			D(printk("jffs_write_node(): jffs_fmalloc(0x%p, %u) "
				 "failed!\n", fmc, total_size));
			return err;
		}

		if (!fm->nodes) {
			/* The jffs_fm struct that we got is not good enough.
			   Make that space dirty and try again  */
			if ((err = jffs_write_dummy_node(c, fm)) < 0) {
				kfree(fm);
				DJM(no_jffs_fm--);
				jffs_fm_write_unlock(fmc);
				D(printk("jffs_write_node(): "
					 "jffs_write_dummy_node(): Failed!\n"));
				return err;
			}
			fm = NULL;
		}
	} /* while(!fm) */
	node->fm = fm;

	ASSERT(if (fm->nodes == 0) {
		printk(KERN_ERR "jffs_write_node(): fm->nodes == 0\n");
	});

	pos = node->fm->offset;

	/* Increment the version number here. We can't let the caller
	   set it beforehand, because we might have had to do GC on a node
	   of this file - and we'd end up reusing version numbers.
	*/
	if (f) {
		raw_inode->version = f->highest_version + 1;
		D1(printk (KERN_NOTICE "jffs_write_node(): setting version of %s to %d\n", f->name, raw_inode->version));

		/* if the file was deleted, set the deleted bit in the raw inode */
		if (f->deleted)
			raw_inode->deleted = 1;
	}

	/* Compute the checksum for the data and name chunks.  */
	raw_inode->dchksum = jffs_checksum(data, raw_inode->dsize);
	raw_inode->nchksum = jffs_checksum(name, raw_inode->nsize);

	/* The checksum is calculated without the chksum and accurate
	   fields so set them to zero first.  */
	raw_inode->accurate = 0;
	raw_inode->chksum = 0;
	raw_inode->chksum = jffs_checksum(raw_inode,
					  sizeof(struct jffs_raw_inode));
	raw_inode->accurate = 0xff;

	D3(printk("jffs_write_node(): About to write this raw inode to the "
		  "flash at pos 0x%lx:\n", (long)pos));
	D3(jffs_print_raw_inode(raw_inode));

	/* The actual raw JFFS node */
	node_iovec[0].iov_base = (void *) raw_inode;
	node_iovec[0].iov_len = (size_t) sizeof(struct jffs_raw_inode);
	iovec_cnt = 1;

	/* Get name and size if there is one */
	if (raw_inode->nsize) {
		node_iovec[iovec_cnt].iov_base = (void *) name;
		node_iovec[iovec_cnt].iov_len = (size_t) raw_inode->nsize;
		iovec_cnt++;

		if (JFFS_GET_PAD_BYTES(raw_inode->nsize)) {
			static unsigned char allff[3]={255,255,255};
			/* Add some extra padding if necessary */
			node_iovec[iovec_cnt].iov_base = allff;
			node_iovec[iovec_cnt].iov_len =
				JFFS_GET_PAD_BYTES(raw_inode->nsize);
			iovec_cnt++;
		}
	}

	/* Get data and size if there is any */
	if (raw_inode->dsize) {
		node_iovec[iovec_cnt].iov_base = (void *) data;
		node_iovec[iovec_cnt].iov_len = (size_t) raw_inode->dsize;
		iovec_cnt++;
		/* No need to pad this because we're not actually putting
		   anything after it.
		*/
	}

	if ((err = flash_safe_writev(fmc->mtd, node_iovec, iovec_cnt,
				    pos)) < 0) {
		jffs_fmfree_partly(fmc, fm, 0);
		jffs_fm_write_unlock(fmc);
		printk(KERN_ERR "JFFS: jffs_write_node: Failed to write, "
		       "requested %i, wrote %i\n", total_size, err);
		goto retry;
	}
	if (raw_inode->deleted)
		f->deleted = 1;

	jffs_fm_write_unlock(fmc);
	D3(printk("jffs_write_node(): Leaving...\n"));
	return raw_inode->dsize;
} /* jffs_write_node()  */


/* Read data from the node and write it to the buffer.  'node_offset'
   is how much we have read from this particular node before and which
   shouldn't be read again.  'max_size' is how much space there is in
   the buffer.  */
static int
jffs_get_node_data(struct jffs_file *f, struct jffs_node *node, 
		   unsigned char *buf,__u32 node_offset, __u32 max_size)
{
	struct jffs_fmcontrol *fmc = f->c->fmc;
	__u32 pos = node->fm->offset + node->fm_offset + node_offset;
	__u32 avail = node->data_size - node_offset;
	__u32 r;

	D2(printk("  jffs_get_node_data(): file: \"%s\", ino: %u, "
		  "version: %u, node_offset: %u\n",
		  f->name, node->ino, node->version, node_offset));

	r = min(avail, max_size);
	D3(printk(KERN_NOTICE "jffs_get_node_data\n"));
	flash_safe_read(fmc->mtd, pos, buf, r);

	D3(printk("  jffs_get_node_data(): Read %u byte%s.\n",
		  r, (r == 1 ? "" : "s")));

	return r;
}


/* Read data from the file's nodes.  Write the data to the buffer
   'buf'.  'read_offset' tells how much data we should skip.  */
int
jffs_read_data(struct jffs_file *f, unsigned char *buf, __u32 read_offset,
	       __u32 size)
{
	struct jffs_node *node;
	__u32 read_data = 0; /* Total amount of read data.  */
	__u32 node_offset = 0;
	__u32 pos = 0; /* Number of bytes traversed.  */

	D2(printk("jffs_read_data(): file = \"%s\", read_offset = %d, "
		  "size = %u\n",
		  (f->name ? f->name : ""), read_offset, size));

	if (read_offset >= f->size) {
		D(printk("  f->size: %d\n", f->size));
		return 0;
	}

	/* First find the node to read data from.  */
	node = f->range_head;
	while (pos <= read_offset) {
		node_offset = read_offset - pos;
		if (node_offset >= node->data_size) {
			pos += node->data_size;
			node = node->range_next;
		}
		else {
			break;
		}
	}

	/* "Cats are living proof that not everything in nature
	   has to be useful."
	   - Garrison Keilor ('97)  */

	/* Fill the buffer.  */
	while (node && (read_data < size)) {
		int r;
		if (!node->fm) {
			/* This node does not refer to real data.  */
			r = min(size - read_data,
				     node->data_size - node_offset);
			memset(&buf[read_data], 0, r);
		}
		else if ((r = jffs_get_node_data(f, node, &buf[read_data],
						 node_offset,
						 size - read_data)) < 0) {
			return r;
		}
		read_data += r;
		node_offset = 0;
		node = node->range_next;
	}
	D3(printk("  jffs_read_data(): Read %u bytes.\n", read_data));
	return read_data;
}


/* Used for traversing all nodes in the hash table.  */
int
jffs_foreach_file(struct jffs_control *c, int (*func)(struct jffs_file *))
{
	int pos;
	int r;
	int result = 0;

	for (pos = 0; pos < c->hash_len; pos++) {
		struct jffs_file *f, *next;

		/* We must do _safe, because 'func' might remove the
		   current file 'f' from the list.  */
		list_for_each_entry_safe(f, next, &c->hash[pos], hash) {
			r = func(f);
			if (r < 0)
				return r;
			result += r;
		}
	}

	return result;
}


/* Free all nodes associated with a file.  */
static int
jffs_free_node_list(struct jffs_file *f)
{
	struct jffs_node *node;
	struct jffs_node *p;

	D3(printk("jffs_free_node_list(): f #%u, \"%s\"\n",
		  f->ino, (f->name ? f->name : "")));
	node = f->version_head;
	while (node) {
		p = node;
		node = node->version_next;
		jffs_free_node(p);
		DJM(no_jffs_node--);
	}
	return 0;
}


/* Free a file and its name.  */
static int
jffs_free_file(struct jffs_file *f)
{
	D3(printk("jffs_free_file: f #%u, \"%s\"\n",
		  f->ino, (f->name ? f->name : "")));

	if (f->name) {
		kfree(f->name);
		DJM(no_name--);
	}
	kfree(f);
	no_jffs_file--;
	return 0;
}

static long
jffs_get_file_count(void)
{
	return no_jffs_file;
}

/* See if a file is deleted. If so, mark that file's nodes as obsolete.  */
int
jffs_possibly_delete_file(struct jffs_file *f)
{
	struct jffs_node *n;

	D3(printk("jffs_possibly_delete_file(): ino: %u\n",
		  f->ino));

	ASSERT(if (!f) {
		printk(KERN_ERR "jffs_possibly_delete_file(): f == NULL\n");
		return -1;
	});

	if (f->deleted) {
		/* First try to remove all older versions.  Commence with
		   the oldest node.  */
		for (n = f->version_head; n; n = n->version_next) {
			if (!n->fm) {
				continue;
			}
			if (jffs_fmfree(f->c->fmc, n->fm, n) < 0) {
				break;
			}
		}
		/* Unlink the file from the filesystem.  */
		if (!f->c->building_fs) {
			jffs_unlink_file_from_tree(f);
		}
		jffs_unlink_file_from_hash(f);
		jffs_free_node_list(f);
		jffs_free_file(f);
	}
	return 0;
}


/* Used in conjunction with jffs_foreach_file() to count the number
   of files in the file system.  */
int
jffs_file_count(struct jffs_file *f)
{
	return 1;
}


/* Build up a file's range list from scratch by going through the
   version list.  */
static int
jffs_build_file(struct jffs_file *f)
{
	struct jffs_node *n;

	D3(printk("jffs_build_file(): ino: %u, name: \"%s\"\n",
		  f->ino, (f->name ? f->name : "")));

	for (n = f->version_head; n; n = n->version_next) {
		jffs_update_file(f, n);
	}
	return 0;
}


/* Remove an amount of data from a file. If this amount of data is
   zero, that could mean that a node should be split in two parts.
   We remove or change the appropriate nodes in the lists.

   Starting offset of area to be removed is node->data_offset,
   and the length of the area is in node->removed_size.   */
static int
jffs_delete_data(struct jffs_file *f, struct jffs_node *node)
{
	struct jffs_node *n;
	__u32 offset = node->data_offset;
	__u32 remove_size = node->removed_size;

	D3(printk("jffs_delete_data(): offset = %u, remove_size = %u\n",
		  offset, remove_size));

	if (remove_size == 0
	    && f->range_tail
	    && f->range_tail->data_offset + f->range_tail->data_size
	       == offset) {
		/* A simple append; nothing to remove or no node to split.  */
		return 0;
	}

	/* Find the node where we should begin the removal.  */
	for (n = f->range_head; n; n = n->range_next) {
		if (n->data_offset + n->data_size > offset) {
			break;
		}
	}
	if (!n) {
		/* If there's no data in the file there's no data to
		   remove either.  */
		return 0;
	}

	if (n->data_offset > offset) {
		/* XXX: Not implemented yet.  */
		printk(KERN_WARNING "JFFS: An unexpected situation "
		       "occurred in jffs_delete_data.\n");
	}
	else if (n->data_offset < offset) {
		/* See if the node has to be split into two parts.  */
		if (n->data_offset + n->data_size > offset + remove_size) {
			/* Do the split.  */
			struct jffs_node *new_node;
			D3(printk("jffs_delete_data(): Split node with "
				  "version number %u.\n", n->version));

			if (!(new_node = jffs_alloc_node())) {
				D(printk("jffs_delete_data(): -ENOMEM\n"));
				return -ENOMEM;
			}
			DJM(no_jffs_node++);

			new_node->ino = n->ino;
			new_node->version = n->version;
			new_node->data_offset = offset;
			new_node->data_size = n->data_size - (remove_size + (offset - n->data_offset));
			new_node->fm_offset = n->fm_offset + (remove_size + (offset - n->data_offset));
			new_node->name_size = n->name_size;
			new_node->fm = n->fm;
			new_node->version_prev = n;
			new_node->version_next = n->version_next;
			if (new_node->version_next) {
				new_node->version_next->version_prev
				= new_node;
			}
			else {
				f->version_tail = new_node;
			}
			n->version_next = new_node;
			new_node->range_prev = n;
			new_node->range_next = n->range_next;
			if (new_node->range_next) {
				new_node->range_next->range_prev = new_node;
			}
			else {
				f->range_tail = new_node;
			}
			/* A very interesting can of worms.  */
			n->range_next = new_node;
			n->data_size = offset - n->data_offset;
			if (new_node->fm)
				jffs_add_node(new_node);
			else {
				D1(printk(KERN_WARNING "jffs_delete_data(): Splitting an empty node (file hold).\n!"));
				D1(printk(KERN_WARNING "FIXME: Did dwmw2 do the right thing here?\n"));
			}
			n = new_node->range_next;
			remove_size = 0;
		}
		else {
			/* No.  No need to split the node.  Just remove
			   the end of the node.  */
			int r = min(n->data_offset + n->data_size
					 - offset, remove_size);
			n->data_size -= r;
			remove_size -= r;
			n = n->range_next;
		}
	}

	/* Remove as many nodes as necessary.  */
	while (n && remove_size) {
		if (n->data_size <= remove_size) {
			struct jffs_node *p = n;
			remove_size -= n->data_size;
			n = n->range_next;
			D3(printk("jffs_delete_data(): Removing node: "
				  "ino: %u, version: %u%s\n",
				  p->ino, p->version,
				  (p->fm ? "" : " (virtual)")));
			if (p->fm) {
				jffs_fmfree(f->c->fmc, p->fm, p);
			}
			jffs_unlink_node_from_range_list(f, p);
			jffs_unlink_node_from_version_list(f, p);
			jffs_free_node(p);
			DJM(no_jffs_node--);
		}
		else {
			n->data_size -= remove_size;
			n->fm_offset += remove_size;
			n->data_offset -= (node->removed_size - remove_size);
			n = n->range_next;
			break;
		}
	}

	/* Adjust the following nodes' information about offsets etc.  */
	while (n && node->removed_size) {
		n->data_offset -= node->removed_size;
		n = n->range_next;
	}

	if (node->removed_size > (f->size - node->data_offset)) {
		/* It's possible that the removed_size is in fact
		 * greater than the amount of data we actually thought
		 * were present in the first place - some of the nodes 
		 * which this node originally obsoleted may already have
		 * been deleted from the flash by subsequent garbage 
		 * collection.
		 *
		 * If this is the case, don't let f->size go negative.
		 * Bad things would happen :)
		 */
		f->size = node->data_offset;
	} else {
		f->size -= node->removed_size;
	}
	D3(printk("jffs_delete_data(): f->size = %d\n", f->size));
	return 0;
} /* jffs_delete_data()  */


/* Insert some data into a file.  Prior to the call to this function,
   jffs_delete_data should be called.  */
static int
jffs_insert_data(struct jffs_file *f, struct jffs_node *node)
{
	D3(printk("jffs_insert_data(): node->data_offset = %u, "
		  "node->data_size = %u, f->size = %u\n",
		  node->data_offset, node->data_size, f->size));

	/* Find the position where we should insert data.  */
	retry:
	if (node->data_offset == f->size) {
		/* A simple append.  This is the most common operation.  */
		node->range_next = NULL;
		node->range_prev = f->range_tail;
		if (node->range_prev) {
			node->range_prev->range_next = node;
		}
		f->range_tail = node;
		f->size += node->data_size;
		if (!f->range_head) {
			f->range_head = node;
		}
	}
	else if (node->data_offset < f->size) {
		/* Trying to insert data into the middle of the file.  This
		   means no problem because jffs_delete_data() has already
		   prepared the range list for us.  */
		struct jffs_node *n;

		/* Find the correct place for the insertion and then insert
		   the node.  */
		for (n = f->range_head; n; n = n->range_next) {
			D2(printk("Cool stuff's happening!\n"));

			if (n->data_offset == node->data_offset) {
				node->range_prev = n->range_prev;
				if (node->range_prev) {
					node->range_prev->range_next = node;
				}
				else {
					f->range_head = node;
				}
				node->range_next = n;
				n->range_prev = node;
				break;
			}
			ASSERT(else if (n->data_offset + n->data_size >
					node->data_offset) {
				printk(KERN_ERR "jffs_insert_data(): "
				       "Couldn't find a place to insert "
				       "the data!\n");
				return -1;
			});
		}

		/* Adjust later nodes' offsets etc.  */
		n = node->range_next;
		while (n) {
			n->data_offset += node->data_size;
			n = n->range_next;
		}
		f->size += node->data_size;
	}
	else if (node->data_offset > f->size) {
		/* Okay.  This is tricky.  This means that we want to insert
		   data at a place that is beyond the limits of the file as
		   it is constructed right now.  This is actually a common
		   event that for instance could occur during the mounting
		   of the file system if a large file have been truncated,
		   rewritten and then only partially garbage collected.  */

		struct jffs_node *n;

		/* We need a place holder for the data that is missing in
		   front of this insertion.  This "virtual node" will not
		   be associated with any space on the flash device.  */
		struct jffs_node *virtual_node;
		if (!(virtual_node = jffs_alloc_node())) {
			return -ENOMEM;
		}

		D(printk("jffs_insert_data: Inserting a virtual node.\n"));
		D(printk("  node->data_offset = %u\n", node->data_offset));
		D(printk("  f->size = %u\n", f->size));

		virtual_node->ino = node->ino;
		virtual_node->version = node->version;
		virtual_node->removed_size = 0;
		virtual_node->fm_offset = 0;
		virtual_node->name_size = 0;
		virtual_node->fm = NULL; /* This is a virtual data holder.  */
		virtual_node->version_prev = NULL;
		virtual_node->version_next = NULL;
		virtual_node->range_next = NULL;

		/* Are there any data at all in the file yet?  */
		if (f->range_head) {
			virtual_node->data_offset
			= f->range_tail->data_offset
			  + f->range_tail->data_size;
			virtual_node->data_size
			= node->data_offset - virtual_node->data_offset;
			virtual_node->range_prev = f->range_tail;
			f->range_tail->range_next = virtual_node;
		}
		else {
			virtual_node->data_offset = 0;
			virtual_node->data_size = node->data_offset;
			virtual_node->range_prev = NULL;
			f->range_head = virtual_node;
		}

		f->range_tail = virtual_node;
		f->size += virtual_node->data_size;

		/* Insert this virtual node in the version list as well.  */
		for (n = f->version_head; n ; n = n->version_next) {
			if (n->version == virtual_node->version) {
				virtual_node->version_prev = n->version_prev;
				n->version_prev = virtual_node;
				if (virtual_node->version_prev) {
					virtual_node->version_prev
					->version_next = virtual_node;
				}
				else {
					f->version_head = virtual_node;
				}
				virtual_node->version_next = n;
				break;
			}
		}

		D(jffs_print_node(virtual_node));

		/* Make a new try to insert the node.  */
		goto retry;
	}

	D3(printk("jffs_insert_data(): f->size = %d\n", f->size));
	return 0;
}


/* A new node (with data) has been added to the file and now the range
   list has to be modified.  */
static int
jffs_update_file(struct jffs_file *f, struct jffs_node *node)
{
	int err;

	D3(printk("jffs_update_file(): ino: %u, version: %u\n",
		  f->ino, node->version));

	if (node->data_size == 0) {
		if (node->removed_size == 0) {
			/* data_offset == X  */
			/* data_size == 0  */
			/* remove_size == 0  */
		}
		else {
			/* data_offset == X  */
			/* data_size == 0  */
			/* remove_size != 0  */
			if ((err = jffs_delete_data(f, node)) < 0) {
				return err;
			}
		}
	}
	else {
		/* data_offset == X  */
		/* data_size != 0  */
		/* remove_size == Y  */
		if ((err = jffs_delete_data(f, node)) < 0) {
			return err;
		}
		if ((err = jffs_insert_data(f, node)) < 0) {
			return err;
		}
	}
	return 0;
}

/* Print the contents of a file.  */
#if 0
int
jffs_print_file(struct jffs_file *f)
{
	D(int i);
	D(printk("jffs_file: 0x%p\n", f));
	D(printk("{\n"));
	D(printk("        0x%08x, /* ino  */\n", f->ino));
	D(printk("        0x%08x, /* pino  */\n", f->pino));
	D(printk("        0x%08x, /* mode  */\n", f->mode));
	D(printk("        0x%04x,     /* uid  */\n", f->uid));
	D(printk("        0x%04x,     /* gid  */\n", f->gid));
	D(printk("        0x%08x, /* atime  */\n", f->atime));
	D(printk("        0x%08x, /* mtime  */\n", f->mtime));
	D(printk("        0x%08x, /* ctime  */\n", f->ctime));
	D(printk("        0x%02x,       /* nsize  */\n", f->nsize));
	D(printk("        0x%02x,       /* nlink  */\n", f->nlink));
	D(printk("        0x%02x,       /* deleted  */\n", f->deleted));
	D(printk("        \"%s\", ", (f->name ? f->name : "")));
	D(for (i = strlen(f->name ? f->name : ""); i < 8; ++i) {
		printk(" ");
	});
	D(printk("/* name  */\n"));
	D(printk("        0x%08x, /* size  */\n", f->size));
	D(printk("        0x%08x, /* highest_version  */\n",
		 f->highest_version));
	D(printk("        0x%p, /* c  */\n", f->c));
	D(printk("        0x%p, /* parent  */\n", f->parent));
	D(printk("        0x%p, /* children  */\n", f->children));
	D(printk("        0x%p, /* sibling_prev  */\n", f->sibling_prev));
	D(printk("        0x%p, /* sibling_next  */\n", f->sibling_next));
	D(printk("        0x%p, /* hash_prev  */\n", f->hash.prev));
	D(printk("        0x%p, /* hash_next  */\n", f->hash.next));
	D(printk("        0x%p, /* range_head  */\n", f->range_head));
	D(printk("        0x%p, /* range_tail  */\n", f->range_tail));
	D(printk("        0x%p, /* version_head  */\n", f->version_head));
	D(printk("        0x%p, /* version_tail  */\n", f->version_tail));
	D(printk("}\n"));
	return 0;
}
#endif  /*  0  */

void
jffs_print_hash_table(struct jffs_control *c)
{
	int i;

	printk("JFFS: Dumping the file system's hash table...\n");
	for (i = 0; i < c->hash_len; i++) {
		struct jffs_file *f;
		list_for_each_entry(f, &c->hash[i], hash) {
			printk("*** c->hash[%u]: \"%s\" "
			       "(ino: %u, pino: %u)\n",
			       i, (f->name ? f->name : ""),
			       f->ino, f->pino);
		}
	}
}


void
jffs_print_tree(struct jffs_file *first_file, int indent)
{
	struct jffs_file *f;
	char *space;
	int dir;

	if (!first_file) {
		return;
	}

	if (!(space = (char *) kmalloc(indent + 1, GFP_KERNEL))) {
		printk("jffs_print_tree(): Out of memory!\n");
		return;
	}

	memset(space, ' ', indent);
	space[indent] = '\0';

	for (f = first_file; f; f = f->sibling_next) {
		dir = S_ISDIR(f->mode);
		printk("%s%s%s (ino: %u, highest_version: %u, size: %u)\n",
		       space, (f->name ? f->name : ""), (dir ? "/" : ""),
		       f->ino, f->highest_version, f->size);
		if (dir) {
			jffs_print_tree(f->children, indent + 2);
		}
	}

	kfree(space);
}


#if defined(JFFS_MEMORY_DEBUG) && JFFS_MEMORY_DEBUG
void
jffs_print_memory_allocation_statistics(void)
{
	static long printout;
	printk("________ Memory printout #%ld ________\n", ++printout);
	printk("no_jffs_file = %ld\n", no_jffs_file);
	printk("no_jffs_node = %ld\n", no_jffs_node);
	printk("no_jffs_control = %ld\n", no_jffs_control);
	printk("no_jffs_raw_inode = %ld\n", no_jffs_raw_inode);
	printk("no_jffs_node_ref = %ld\n", no_jffs_node_ref);
	printk("no_jffs_fm = %ld\n", no_jffs_fm);
	printk("no_jffs_fmcontrol = %ld\n", no_jffs_fmcontrol);
	printk("no_hash = %ld\n", no_hash);
	printk("no_name = %ld\n", no_name);
	printk("\n");
}
#endif


/* Rewrite `size' bytes, and begin at `node'.  */
static int
jffs_rewrite_data(struct jffs_file *f, struct jffs_node *node, __u32 size)
{
	struct jffs_control *c = f->c;
	struct jffs_fmcontrol *fmc = c->fmc;
	struct jffs_raw_inode raw_inode;
	struct jffs_node *new_node;
	struct jffs_fm *fm;
	__u32 pos;
	__u32 pos_dchksum;
	__u32 total_name_size;
	__u32 total_data_size;
	__u32 total_size;
	int err;

	D1(printk("***jffs_rewrite_data(): node: %u, name: \"%s\", size: %u\n",
		  f->ino, (f->name ? f->name : "(null)"), size));

	/* Create and initialize the new node.  */
	if (!(new_node = jffs_alloc_node())) {
		D(printk("jffs_rewrite_data(): "
			 "Failed to allocate node.\n"));
		return -ENOMEM;
	}
	DJM(no_jffs_node++);
	new_node->data_offset = node->data_offset;
	new_node->removed_size = size;
	total_name_size = JFFS_PAD(f->nsize);
	total_data_size = JFFS_PAD(size);
	total_size = sizeof(struct jffs_raw_inode)
		     + total_name_size + total_data_size;
	new_node->fm_offset = sizeof(struct jffs_raw_inode)
			      + total_name_size;

retry:
	jffs_fm_write_lock(fmc);
	err = 0;

	if ((err = jffs_fmalloc(fmc, total_size, new_node, &fm)) < 0) {
		DJM(no_jffs_node--);
		jffs_fm_write_unlock(fmc);
		D(printk("jffs_rewrite_data(): Failed to allocate fm.\n"));
		jffs_free_node(new_node);
		return err;
	}
	else if (!fm->nodes) {
		/* The jffs_fm struct that we got is not big enough.  */
		/* This should never happen, because we deal with this case
		   in jffs_garbage_collect_next().*/
		printk(KERN_WARNING "jffs_rewrite_data(): Allocated node is too small (%d bytes of %d)\n", fm->size, total_size);
		if ((err = jffs_write_dummy_node(c, fm)) < 0) {
			D(printk("jffs_rewrite_data(): "
				 "jffs_write_dummy_node() Failed!\n"));
		} else {
			err = -ENOSPC;
		}
		DJM(no_jffs_fm--);
		jffs_fm_write_unlock(fmc);
		kfree(fm);
		
		return err;
	}
	new_node->fm = fm;

	/* Initialize the raw inode.  */
	raw_inode.magic = JFFS_MAGIC_BITMASK;
	raw_inode.ino = f->ino;
	raw_inode.pino = f->pino;
	raw_inode.version = f->highest_version + 1;
	raw_inode.mode = f->mode;
	raw_inode.uid = f->uid;
	raw_inode.gid = f->gid;
	raw_inode.atime = f->atime;
	raw_inode.mtime = f->mtime;
	raw_inode.ctime = f->ctime;
	raw_inode.offset = node->data_offset;
	raw_inode.dsize = size;
	raw_inode.rsize = size;
	raw_inode.nsize = f->nsize;
	raw_inode.nlink = f->nlink;
	raw_inode.spare = 0;
	raw_inode.rename = 0;
	raw_inode.deleted = f->deleted;
	raw_inode.accurate = 0xff;
	raw_inode.dchksum = 0;
	raw_inode.nchksum = 0;

	pos = new_node->fm->offset;
	pos_dchksum = pos +JFFS_RAW_INODE_DCHKSUM_OFFSET;

	D3(printk("jffs_rewrite_data(): Writing this raw inode "
		  "to pos 0x%ul.\n", pos));
	D3(jffs_print_raw_inode(&raw_inode));

	if ((err = flash_safe_write(fmc->mtd, pos,
				    (u_char *) &raw_inode,
				    sizeof(struct jffs_raw_inode)
				    - sizeof(__u32)
				    - sizeof(__u16) - sizeof(__u16))) < 0) {
		jffs_fmfree_partly(fmc, fm,
				   total_name_size + total_data_size);
		jffs_fm_write_unlock(fmc);
		printk(KERN_ERR "JFFS: jffs_rewrite_data: Write error during "
			"rewrite. (raw inode)\n");
		printk(KERN_ERR "JFFS: jffs_rewrite_data: Now retrying "
			"rewrite. (raw inode)\n");
		goto retry;
	}
	pos += sizeof(struct jffs_raw_inode);

	/* Write the name to the flash memory.  */
	if (f->nsize) {
		D3(printk("jffs_rewrite_data(): Writing name \"%s\" to "
			  "pos 0x%ul.\n", f->name, (unsigned int) pos));
		if ((err = flash_safe_write(fmc->mtd, pos,
					    (u_char *)f->name,
					    f->nsize)) < 0) {
			jffs_fmfree_partly(fmc, fm, total_data_size);
			jffs_fm_write_unlock(fmc);
			printk(KERN_ERR "JFFS: jffs_rewrite_data: Write "
				"error during rewrite. (name)\n");
			printk(KERN_ERR "JFFS: jffs_rewrite_data: Now retrying "
				"rewrite. (name)\n");
			goto retry;
		}
		pos += total_name_size;
		raw_inode.nchksum = jffs_checksum(f->name, f->nsize);
	}

	/* Write the data.  */
	if (size) {
		int r;
		unsigned char *page;
		__u32 offset = node->data_offset;

		if (!(page = (unsigned char *)__get_free_page(GFP_KERNEL))) {
			jffs_fmfree_partly(fmc, fm, 0);
			return -1;
		}

		while (size) {
			__u32 s = min(size, (__u32)PAGE_SIZE);
			if ((r = jffs_read_data(f, (char *)page,
						offset, s)) < s) {
				free_page((unsigned long)page);
				jffs_fmfree_partly(fmc, fm, 0);
				jffs_fm_write_unlock(fmc);
				printk(KERN_ERR "JFFS: jffs_rewrite_data: "
					 "jffs_read_data() "
					 "failed! (r = %d)\n", r);
				return -1;
			}
			if ((err = flash_safe_write(fmc->mtd,
						    pos, page, r)) < 0) {
				free_page((unsigned long)page);
				jffs_fmfree_partly(fmc, fm, 0);
				jffs_fm_write_unlock(fmc);
				printk(KERN_ERR "JFFS: jffs_rewrite_data: "
				       "Write error during rewrite. "
				       "(data)\n");
				goto retry;
			}
			pos += r;
			size -= r;
			offset += r;
			raw_inode.dchksum += jffs_checksum(page, r);
		}

	        free_page((unsigned long)page);
	}

	raw_inode.accurate = 0;
	raw_inode.chksum = jffs_checksum(&raw_inode,
					 sizeof(struct jffs_raw_inode)
					 - sizeof(__u16));

	/* Add the checksum.  */
	if ((err
	     = flash_safe_write(fmc->mtd, pos_dchksum,
				&((u_char *)
				&raw_inode)[JFFS_RAW_INODE_DCHKSUM_OFFSET],
				sizeof(__u32) + sizeof(__u16)
				+ sizeof(__u16))) < 0) {
		jffs_fmfree_partly(fmc, fm, 0);
		jffs_fm_write_unlock(fmc);
		printk(KERN_ERR "JFFS: jffs_rewrite_data: Write error during "
		       "rewrite. (checksum)\n");
		goto retry;
	}

	/* Now make the file system aware of the newly written node.  */
	jffs_insert_node(c, f, &raw_inode, f->name, new_node);
	jffs_fm_write_unlock(fmc);

	D3(printk("jffs_rewrite_data(): Leaving...\n"));
	return 0;
} /* jffs_rewrite_data()  */


/* jffs_garbage_collect_next implements one step in the garbage collect
   process and is often called multiple times at each occasion of a
   garbage collect.  */

static int
jffs_garbage_collect_next(struct jffs_control *c)
{
	struct jffs_fmcontrol *fmc = c->fmc;
	struct jffs_node *node;
	struct jffs_file *f;
	int err = 0;
	__u32 size;
	__u32 data_size;
	__u32 total_name_size;
	__u32 extra_available;
	__u32 space_needed;
	__u32 free_chunk_size1 = jffs_free_size1(fmc);
	D2(__u32 free_chunk_size2 = jffs_free_size2(fmc));

	/* Get the oldest node in the flash.  */
	node = jffs_get_oldest_node(fmc);
	ASSERT(if (!node) {
		printk(KERN_ERR "JFFS: jffs_garbage_collect_next: "
		       "No oldest node found!\n");
                err = -1;
                goto jffs_garbage_collect_next_end;
		

	});

	/* Find its corresponding file too.  */
	f = jffs_find_file(c, node->ino);

	if (!f) {
	  printk (KERN_ERR "JFFS: jffs_garbage_collect_next: "
                  "No file to garbage collect! "
		  "(ino = 0x%08x)\n", node->ino);
          /* FIXME: Free the offending node and recover. */
          err = -1;
          goto jffs_garbage_collect_next_end;
	}

	/* We always write out the name. Theoretically, we don't need
	   to, but for now it's easier - because otherwise we'd have
	   to keep track of how many times the current name exists on
	   the flash and make sure it never reaches zero.

	   The current approach means that would be possible to cause
	   the GC to end up eating its tail by writing lots of nodes
	   with no name for it to garbage-collect. Hence the change in
	   inode.c to write names with _every_ node.

	   It sucks, but it _should_ work.
	*/
	total_name_size = JFFS_PAD(f->nsize);

	D1(printk("jffs_garbage_collect_next(): \"%s\", "
		  "ino: %u, version: %u, location 0x%x, dsize %u\n",
		  (f->name ? f->name : ""), node->ino, node->version, 
		  node->fm->offset, node->data_size));

	/* Compute how many data it's possible to rewrite at the moment.  */
	data_size = f->size - node->data_offset;

	/* And from that, the total size of the chunk we want to write */
	size = sizeof(struct jffs_raw_inode) + total_name_size
	       + data_size + JFFS_GET_PAD_BYTES(data_size);

	/* If that's more than max_chunk_size, reduce it accordingly */
	if (size > fmc->max_chunk_size) {
		size = fmc->max_chunk_size;
		data_size = size - sizeof(struct jffs_raw_inode)
			    - total_name_size;
	}

	/* If we're asking to take up more space than free_chunk_size1
	   but we _could_ fit in it, shrink accordingly.
	*/
	if (size > free_chunk_size1) {

		if (free_chunk_size1 <
		    (sizeof(struct jffs_raw_inode) + total_name_size + BLOCK_SIZE)){
			/* The space left is too small to be of any
			   use really.  */
			struct jffs_fm *dirty_fm
			= jffs_fmalloced(fmc,
					 fmc->tail->offset + fmc->tail->size,
					 free_chunk_size1, NULL);
			if (!dirty_fm) {
				printk(KERN_ERR "JFFS: "
				       "jffs_garbage_collect_next: "
				       "Failed to allocate `dirty' "
				       "flash memory!\n");
				err = -1;
                                goto jffs_garbage_collect_next_end;
			}
			D1(printk("Dirtying end of flash - too small\n"));
			jffs_write_dummy_node(c, dirty_fm);
                        err = 0;
			goto jffs_garbage_collect_next_end;
		}
		D1(printk("Reducing size of new node from %d to %d to avoid "
			  " exceeding free_chunk_size1\n",
			  size, free_chunk_size1));

		size = free_chunk_size1;
		data_size = size - sizeof(struct jffs_raw_inode)
			    - total_name_size;
	}


	/* Calculate the amount of space needed to hold the nodes
	   which are remaining in the tail */
	space_needed = fmc->min_free_size - (node->fm->offset % fmc->sector_size);

	/* From that, calculate how much 'extra' space we can use to
	   increase the size of the node we're writing from the size
	   of the node we're obsoleting
	*/
	if (space_needed > fmc->free_size) {
		/* If we've gone below min_free_size for some reason,
		   don't fuck up. This is why we have 
		   min_free_size > sector_size. Whinge about it though,
		   just so I can convince myself my maths is right.
		*/
		D1(printk(KERN_WARNING "jffs_garbage_collect_next(): "
			  "space_needed %d exceeded free_size %d\n",
			  space_needed, fmc->free_size));
		extra_available = 0;
	} else {
		extra_available = fmc->free_size - space_needed;
	}

	/* Check that we don't use up any more 'extra' space than
	   what's available */
	if (size > JFFS_PAD(node->data_size) + total_name_size + 
	    sizeof(struct jffs_raw_inode) + extra_available) {
		D1(printk("Reducing size of new node from %d to %ld to avoid "
		       "catching our tail\n", size, 
			  (long) (JFFS_PAD(node->data_size) + JFFS_PAD(node->name_size) + 
			  sizeof(struct jffs_raw_inode) + extra_available)));
		D1(printk("space_needed = %d, extra_available = %d\n", 
			  space_needed, extra_available));

		size = JFFS_PAD(node->data_size) + total_name_size + 
		  sizeof(struct jffs_raw_inode) + extra_available;
		data_size = size - sizeof(struct jffs_raw_inode)
			- total_name_size;
	};

	D2(printk("  total_name_size: %u\n", total_name_size));
	D2(printk("  data_size: %u\n", data_size));
	D2(printk("  size: %u\n", size));
	D2(printk("  f->nsize: %u\n", f->nsize));
	D2(printk("  f->size: %u\n", f->size));
	D2(printk("  node->data_offset: %u\n", node->data_offset));
	D2(printk("  free_chunk_size1: %u\n", free_chunk_size1));
	D2(printk("  free_chunk_size2: %u\n", free_chunk_size2));
	D2(printk("  node->fm->offset: 0x%08x\n", node->fm->offset));

	if ((err = jffs_rewrite_data(f, node, data_size))) {
		printk(KERN_WARNING "jffs_rewrite_data() failed: %d\n", err);
		return err;
	}
	  
jffs_garbage_collect_next_end:
	D3(printk("jffs_garbage_collect_next: Leaving...\n"));
	return err;
} /* jffs_garbage_collect_next */


/* If an obsolete node is partly going to be erased due to garbage
   collection, the part that isn't going to be erased must be filled
   with zeroes so that the scan of the flash will work smoothly next
   time.  (The data in the file could for instance be a JFFS image
   which could cause enormous confusion during a scan of the flash
   device if we didn't do this.)
     There are two phases in this procedure: First, the clearing of
   the name and data parts of the node. Second, possibly also clearing
   a part of the raw inode as well.  If the box is power cycled during
   the first phase, only the checksum of this node-to-be-cleared-at-
   the-end will be wrong.  If the box is power cycled during, or after,
   the clearing of the raw inode, the information like the length of
   the name and data parts are zeroed.  The next time the box is
   powered up, the scanning algorithm manages this faulty data too
   because:

   - The checksum is invalid and thus the raw inode must be discarded
     in any case.
   - If the lengths of the data part or the name part are zeroed, the
     scanning just continues after the raw inode.  But after the inode
     the scanning procedure just finds zeroes which is the same as
     dirt.

   So, in the end, this could never fail. :-)  Even if it does fail,
   the scanning algorithm should manage that too.  */

static int
jffs_clear_end_of_node(struct jffs_control *c, __u32 erase_size)
{
	struct jffs_fm *fm;
	struct jffs_fmcontrol *fmc = c->fmc;
	__u32 zero_offset;
	__u32 zero_size;
	__u32 zero_offset_data;
	__u32 zero_size_data;
	__u32 cutting_raw_inode = 0;

	if (!(fm = jffs_cut_node(fmc, erase_size))) {
		D3(printk("jffs_clear_end_of_node(): fm == NULL\n"));
		return 0;
	}

	/* Where and how much shall we clear?  */
	zero_offset = fmc->head->offset + erase_size;
	zero_size = fm->offset + fm->size - zero_offset;

	/* Do we have to clear the raw_inode explicitly?  */
	if (fm->size - zero_size < sizeof(struct jffs_raw_inode)) {
		cutting_raw_inode = sizeof(struct jffs_raw_inode)
				    - (fm->size - zero_size);
	}

	/* First, clear the name and data fields.  */
	zero_offset_data = zero_offset + cutting_raw_inode;
	zero_size_data = zero_size - cutting_raw_inode;
	flash_safe_acquire(fmc->mtd);
	flash_memset(fmc->mtd, zero_offset_data, 0, zero_size_data);
	flash_safe_release(fmc->mtd);

	/* Should we clear a part of the raw inode?  */
	if (cutting_raw_inode) {
		/* I guess it is ok to clear the raw inode in this order.  */
		flash_safe_acquire(fmc->mtd);
		flash_memset(fmc->mtd, zero_offset, 0,
			     cutting_raw_inode);
		flash_safe_release(fmc->mtd);
	}

	return 0;
} /* jffs_clear_end_of_node()  */

/* Try to erase as much as possible of the dirt in the flash memory.  */
static long
jffs_try_to_erase(struct jffs_control *c)
{
	struct jffs_fmcontrol *fmc = c->fmc;
	long erase_size;
	int err;
	__u32 offset;

	D3(printk("jffs_try_to_erase()\n"));

	erase_size = jffs_erasable_size(fmc);

	D2(printk("jffs_try_to_erase(): erase_size = %ld\n", erase_size));

	if (erase_size == 0) {
		return 0;
	}
	else if (erase_size < 0) {
		printk(KERN_ERR "JFFS: jffs_try_to_erase: "
		       "jffs_erasable_size returned %ld.\n", erase_size);
		return erase_size;
	}

	if ((err = jffs_clear_end_of_node(c, erase_size)) < 0) {
		printk(KERN_ERR "JFFS: jffs_try_to_erase: "
		       "Clearing of node failed.\n");
		return err;
	}

	offset = fmc->head->offset;

	/* Now, let's try to do the erase.  */
	if ((err = flash_erase_region(fmc->mtd,
				      offset, erase_size)) < 0) {
		printk(KERN_ERR "JFFS: Erase of flash failed. "
		       "offset = %u, erase_size = %ld\n",
		       offset, erase_size);
		/* XXX: Here we should allocate this area as dirty
		   with jffs_fmalloced or something similar.  Now
		   we just report the error.  */
		return err;
	}

#if 0
	/* Check if the erased sectors really got erased.  */
	{
		__u32 pos;
		__u32 end;

		pos = (__u32)flash_get_direct_pointer(to_kdev_t(c->sb->s_dev), offset);
		end = pos + erase_size;

		D2(printk("JFFS: Checking erased sector(s)...\n"));

		flash_safe_acquire(fmc->mtd);

		for (; pos < end; pos += 4) {
			if (*(__u32 *)pos != JFFS_EMPTY_BITMASK) {
				printk("JFFS: Erase failed! pos = 0x%lx\n",
				       (long)pos);
				jffs_hexdump(fmc->mtd, pos,
					     jffs_min(256, end - pos));
				err = -1;
				break;
			}
		}

		flash_safe_release(fmc->mtd);

		if (!err) {
			D2(printk("JFFS: Erase succeeded.\n"));
		}
		else {
			/* XXX: Here we should allocate the memory
			   with jffs_fmalloced() in order to prevent
			   JFFS from using this area accidentally.  */
			return err;
		}
	}
#endif

	/* Update the flash memory data structures.  */
	jffs_sync_erase(fmc, erase_size);

	return erase_size;
}


/* There are different criteria that should trigger a garbage collect:

   1. There is too much dirt in the memory.
   2. The free space is becoming small.
   3. There are many versions of a node.

   The garbage collect should always be done in a manner that guarantees
   that future garbage collects cannot be locked.  E.g. Rewritten chunks
   should not be too large (span more than one sector in the flash memory
   for exemple).  Of course there is a limit on how intelligent this garbage
   collection can be.  */


static int
jffs_garbage_collect_now(struct jffs_control *c)
{
	struct jffs_fmcontrol *fmc = c->fmc;
	long erased = 0;
	int result = 0;
	D1(int i = 1);
	D2(printk("***jffs_garbage_collect_now(): fmc->dirty_size = %u, fmc->free_size = 0x%x\n, fcs1=0x%x, fcs2=0x%x",
		  fmc->dirty_size, fmc->free_size, jffs_free_size1(fmc), jffs_free_size2(fmc)));
	D2(jffs_print_fmcontrol(fmc));

	//	down(&fmc->gclock);

	/* If it is possible to garbage collect, do so.  */
	
	while (erased == 0) {
		D1(printk("***jffs_garbage_collect_now(): round #%u, "
			  "fmc->dirty_size = %u\n", i++, fmc->dirty_size));
		D2(jffs_print_fmcontrol(fmc));

		if ((erased = jffs_try_to_erase(c)) < 0) {
			printk(KERN_WARNING "JFFS: Error in "
			       "garbage collector.\n");
			result = erased;
			goto gc_end;
		}
		if (erased)
			break;
		
		if (fmc->free_size == 0) {
			/* Argh */
			printk(KERN_ERR "jffs_garbage_collect_now(): free_size == 0. This is BAD.\n");
			result = -ENOSPC;
			break;
		}

		if (fmc->dirty_size < fmc->sector_size) {
			/* Actually, we _may_ have been able to free some, 
			 * if there are many overlapping nodes which aren't
			 * actually marked dirty because they still have
			 * some valid data in each.
			 */
			result = -ENOSPC;
			break;
		}

		/* Let's dare to make a garbage collect.  */
		if ((result = jffs_garbage_collect_next(c)) < 0) {
			printk(KERN_ERR "JFFS: Something "
			       "has gone seriously wrong "
			       "with a garbage collect.\n");
			goto gc_end;
		}

		D1(printk("   jffs_garbage_collect_now(): erased: %ld\n", erased));
		DJM(jffs_print_memory_allocation_statistics());
	}
	
gc_end:
	//	up(&fmc->gclock);

	D3(printk("   jffs_garbage_collect_now(): Leaving...\n"));
	D1(if (erased) {
		printk("jffs_g_c_now(): erased = %ld\n", erased);
		jffs_print_fmcontrol(fmc);
	});

	if (!erased && !result)
		return -ENOSPC;

	return result;
} /* jffs_garbage_collect_now() */


/* Determine if it is reasonable to start garbage collection.
   We start a gc pass if either:
   - The number of free bytes < MIN_FREE_BYTES && at least one
     block is dirty, OR
   - The number of dirty bytes > MAX_DIRTY_BYTES
*/
static inline int thread_should_wake (struct jffs_control *c)
{
	D1(printk (KERN_NOTICE "thread_should_wake(): free=%d, dirty=%d, blocksize=%d.\n",
		   c->fmc->free_size, c->fmc->dirty_size, c->fmc->sector_size));

	/* If there's not enough dirty space to free a block, there's no point. */
	if (c->fmc->dirty_size < c->fmc->sector_size) {
		D2(printk(KERN_NOTICE "thread_should_wake(): Not waking. Insufficient dirty space\n"));
		return 0;
	}
#if 1
	/* If there is too much RAM used by the various structures, GC */
	if (jffs_get_node_inuse() > (c->fmc->used_size/c->fmc->max_chunk_size * 5 + jffs_get_file_count() * 2 + 50)) {
		/* FIXME: Provide proof that this test can be satisfied. We
		   don't want a filesystem doing endless GC just because this
		   condition cannot ever be false.
		*/
		D2(printk(KERN_NOTICE "thread_should_wake(): Waking due to number of nodes\n"));
		return 1;
	}
#endif
	/* If there are fewer free bytes than the threshold, GC */
	if (c->fmc->free_size < c->gc_minfree_threshold) {
		D2(printk(KERN_NOTICE "thread_should_wake(): Waking due to insufficent free space\n"));
		return 1;
	}
	/* If there are more dirty bytes than the threshold, GC */
	if (c->fmc->dirty_size > c->gc_maxdirty_threshold) {
		D2(printk(KERN_NOTICE "thread_should_wake(): Waking due to excessive dirty space\n"));
		return 1;
	}	
	/* FIXME: What about the "There are many versions of a node" condition? */

	return 0;
}


void jffs_garbage_collect_trigger(struct jffs_control *c)
{
	/* NOTE: We rely on the fact that we have the BKL here.
	 * Otherwise, the gc_task could go away between the check
	 * and the wake_up_process()
	 */
	if (c->gc_task && thread_should_wake(c))
		send_sig(SIGHUP, c->gc_task, 1);
}
  

/* Kernel threads  take (void *) as arguments.   Thus we pass
   the jffs_control data as a (void *) and then cast it. */
int
jffs_garbage_collect_thread(void *ptr)
{
        struct jffs_control *c = (struct jffs_control *) ptr;
	struct jffs_fmcontrol *fmc = c->fmc;
	long erased;
	int result = 0;
	D1(int i = 1);

	daemonize("jffs_gcd");

	c->gc_task = current;

	lock_kernel();
	init_completion(&c->gc_thread_comp); /* barrier */ 
	spin_lock_irq(&current->sighand->siglock);
	siginitsetinv (&current->blocked, sigmask(SIGHUP) | sigmask(SIGKILL) | sigmask(SIGSTOP) | sigmask(SIGCONT));
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	D1(printk (KERN_NOTICE "jffs_garbage_collect_thread(): Starting infinite loop.\n"));

	for (;;) {

		/* See if we need to start gc.  If we don't, go to sleep.
		   
		   Current implementation is a BAD THING(tm).  If we try 
		   to unmount the FS, the unmount operation will sleep waiting
		   for this thread to exit.  We need to arrange to send it a
		   sig before the umount process sleeps.
		*/

		if (!thread_should_wake(c))
			set_current_state (TASK_INTERRUPTIBLE);
		
		schedule(); /* Yes, we do this even if we want to go
				       on immediately - we're a low priority 
				       background task. */

		/* Put_super will send a SIGKILL and then wait on the sem. 
		 */
		while (signal_pending(current)) {
			siginfo_t info;
			unsigned long signr = 0;

			if (try_to_freeze())
				continue;

			spin_lock_irq(&current->sighand->siglock);
			signr = dequeue_signal(current, &current->blocked, &info);
			spin_unlock_irq(&current->sighand->siglock);

			switch(signr) {
			case SIGSTOP:
				D1(printk("jffs_garbage_collect_thread(): SIGSTOP received.\n"));
				set_current_state(TASK_STOPPED);
				schedule();
				break;

			case SIGKILL:
				D1(printk("jffs_garbage_collect_thread(): SIGKILL received.\n"));
				c->gc_task = NULL;
				complete_and_exit(&c->gc_thread_comp, 0);
			}
		}


		D1(printk (KERN_NOTICE "jffs_garbage_collect_thread(): collecting.\n"));

		D3(printk (KERN_NOTICE "g_c_thread(): down biglock\n"));
		mutex_lock(&fmc->biglock);
		
		D1(printk("***jffs_garbage_collect_thread(): round #%u, "
			  "fmc->dirty_size = %u\n", i++, fmc->dirty_size));
		D2(jffs_print_fmcontrol(fmc));

		if ((erased = jffs_try_to_erase(c)) < 0) {
			printk(KERN_WARNING "JFFS: Error in "
			       "garbage collector: %ld.\n", erased);
		}

		if (erased)
			goto gc_end;

		if (fmc->free_size == 0) {
			/* Argh. Might as well commit suicide. */
			printk(KERN_ERR "jffs_garbage_collect_thread(): free_size == 0. This is BAD.\n");
			send_sig(SIGQUIT, c->gc_task, 1);
			// panic()
			goto gc_end;
		}
		
		/* Let's dare to make a garbage collect.  */
		if ((result = jffs_garbage_collect_next(c)) < 0) {
			printk(KERN_ERR "JFFS: Something "
			       "has gone seriously wrong "
			       "with a garbage collect: %d\n", result);
		}
		
	gc_end:
		D3(printk (KERN_NOTICE "g_c_thread(): up biglock\n"));
		mutex_unlock(&fmc->biglock);
	} /* for (;;) */
} /* jffs_garbage_collect_thread() */