[JFFS2] Calculate CRC check starting point correctly

[linux-2.6/mini2440.git] / fs / jffs2 / nodelist.c

/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright (C) 2001-2003 Red Hat, Inc.
 *
 * Created by David Woodhouse <dwmw2@infradead.org>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 * $Id: nodelist.c,v 1.111 2005/08/17 14:57:39 dedekind Exp $
 *
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/mtd/mtd.h>
#include <linux/rbtree.h>
#include <linux/crc32.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include "nodelist.h"

void jffs2_add_fd_to_list(struct jffs2_sb_info *c, struct jffs2_full_dirent *new, struct jffs2_full_dirent **list)
{
        struct jffs2_full_dirent **prev = list;
        
        JFFS2_DBG_DENTLIST("add dirent \"%s\", ino #%u\n", new->name, new->ino);

        while ((*prev) && (*prev)->nhash <= new->nhash) {
                if ((*prev)->nhash == new->nhash && !strcmp((*prev)->name, new->name)) {
                        /* Duplicate. Free one */
                        if (new->version < (*prev)->version) {
                                JFFS2_DBG_DENTLIST("Eep! Marking new dirent node is obsolete, old is \"%s\", ino #%u\n",
                                        (*prev)->name, (*prev)->ino);
                                jffs2_mark_node_obsolete(c, new->raw);
                                jffs2_free_full_dirent(new);
                        } else {
                                JFFS2_DBG_DENTLIST("marking old dirent \"%s\", ino #%u bsolete\n",
                                        (*prev)->name, (*prev)->ino);
                                new->next = (*prev)->next;
                                jffs2_mark_node_obsolete(c, ((*prev)->raw));
                                jffs2_free_full_dirent(*prev);
                                *prev = new;
                        }
                        return;
                }
                prev = &((*prev)->next);
        }
        new->next = *prev;
        *prev = new;
}

void jffs2_truncate_fragtree(struct jffs2_sb_info *c, struct rb_root *list, uint32_t size)
{
        struct jffs2_node_frag *frag = jffs2_lookup_node_frag(list, size);

        JFFS2_DBG_FRAGTREE("truncating fragtree to 0x%08x bytes\n", size);

        /* We know frag->ofs <= size. That's what lookup does for us */
        if (frag && frag->ofs != size) {
                if (frag->ofs+frag->size > size) {
                        frag->size = size - frag->ofs;
                }
                frag = frag_next(frag);
        }
        while (frag && frag->ofs >= size) {
                struct jffs2_node_frag *next = frag_next(frag);

                frag_erase(frag, list);
                jffs2_obsolete_node_frag(c, frag);
                frag = next;
        }

        if (size == 0)
                return;

        /* 
         * If the last fragment starts at the RAM page boundary, it is
         * REF_PRISTINE irrespective of its size.
         */
        frag = frag_last(list);
        if ((frag->ofs & (PAGE_CACHE_SIZE - 1)) == 0) {
                JFFS2_DBG_FRAGTREE2("marking the last fragment 0x%08x-0x%08x REF_PRISTINE.\n",
                        frag->ofs, frag->ofs + frag->size); 
                frag->node->raw->flash_offset = ref_offset(frag->node->raw) | REF_PRISTINE;
        }
}

void jffs2_obsolete_node_frag(struct jffs2_sb_info *c, struct jffs2_node_frag *this)
{
        if (this->node) {
                this->node->frags--;
                if (!this->node->frags) {
                        /* The node has no valid frags left. It's totally obsoleted */
                        JFFS2_DBG_FRAGTREE2("marking old node @0x%08x (0x%04x-0x%04x) obsolete\n",
                                ref_offset(this->node->raw), this->node->ofs, this->node->ofs+this->node->size);
                        jffs2_mark_node_obsolete(c, this->node->raw);
                        jffs2_free_full_dnode(this->node);
                } else {
                        JFFS2_DBG_FRAGTREE2("marking old node @0x%08x (0x%04x-0x%04x) REF_NORMAL. frags is %d\n",
                                ref_offset(this->node->raw), this->node->ofs, this->node->ofs+this->node->size, this->node->frags);
                        mark_ref_normal(this->node->raw);
                }
                
        }
        jffs2_free_node_frag(this);
}

static void jffs2_fragtree_insert(struct jffs2_node_frag *newfrag, struct jffs2_node_frag *base)
{
        struct rb_node *parent = &base->rb;
        struct rb_node **link = &parent;

        JFFS2_DBG_FRAGTREE2("insert frag (0x%04x-0x%04x)\n", newfrag->ofs, newfrag->ofs + newfrag->size);

        while (*link) {
                parent = *link;
                base = rb_entry(parent, struct jffs2_node_frag, rb);
        
                if (newfrag->ofs > base->ofs)
                        link = &base->rb.rb_right;
                else if (newfrag->ofs < base->ofs)
                        link = &base->rb.rb_left;
                else {
                        JFFS2_ERROR("duplicate frag at %08x (%p,%p)\n", newfrag->ofs, newfrag, base);
                        BUG();
                }
        }

        rb_link_node(&newfrag->rb, &base->rb, link);
}

/*
 * Allocate and initializes a new fragment.
 */
static inline struct jffs2_node_frag * new_fragment(struct jffs2_full_dnode *fn, uint32_t ofs, uint32_t size)
{
        struct jffs2_node_frag *newfrag;
        
        newfrag = jffs2_alloc_node_frag();
        if (likely(newfrag)) {
                newfrag->ofs = ofs;
                newfrag->size = size;
                newfrag->node = fn;
        } else {
                JFFS2_ERROR("cannot allocate a jffs2_node_frag object\n");
        }

        return newfrag;
}

/*
 * Called when there is no overlapping fragment exist. Inserts a hole before the new
 * fragment and inserts the new fragment to the fragtree.
 */
static int no_overlapping_node(struct jffs2_sb_info *c, struct rb_root *root,
                               struct jffs2_node_frag *newfrag,
                               struct jffs2_node_frag *this, uint32_t lastend)
{
        if (lastend < newfrag->node->ofs) {
                /* put a hole in before the new fragment */
                struct jffs2_node_frag *holefrag;

                holefrag= new_fragment(NULL, lastend, newfrag->node->ofs - lastend);
                if (unlikely(!holefrag)) {
                        jffs2_free_node_frag(newfrag);
                        return -ENOMEM;
                }

                if (this) {
                        /* By definition, the 'this' node has no right-hand child, 
                           because there are no frags with offset greater than it.
                           So that's where we want to put the hole */
                        JFFS2_DBG_FRAGTREE2("add hole frag %#04x-%#04x on the right of the new frag.\n",
                                holefrag->ofs, holefrag->ofs + holefrag->size);
                        rb_link_node(&holefrag->rb, &this->rb, &this->rb.rb_right);
                } else {
                        JFFS2_DBG_FRAGTREE2("Add hole frag %#04x-%#04x to the root of the tree.\n",
                                holefrag->ofs, holefrag->ofs + holefrag->size);
                        rb_link_node(&holefrag->rb, NULL, &root->rb_node);
                }
                rb_insert_color(&holefrag->rb, root);
                this = holefrag;
        }
        
        if (this) {
                /* By definition, the 'this' node has no right-hand child, 
                   because there are no frags with offset greater than it.
                   So that's where we want to put new fragment */
                JFFS2_DBG_FRAGTREE2("add the new node at the right\n");
                rb_link_node(&newfrag->rb, &this->rb, &this->rb.rb_right);                      
        } else {
                JFFS2_DBG_FRAGTREE2("insert the new node at the root of the tree\n");
                rb_link_node(&newfrag->rb, NULL, &root->rb_node);
        }
        rb_insert_color(&newfrag->rb, root);

        return 0;
}

/* Doesn't set inode->i_size */
static int jffs2_add_frag_to_fragtree(struct jffs2_sb_info *c, struct rb_root *root, struct jffs2_node_frag *newfrag)
{
        struct jffs2_node_frag *this;
        uint32_t lastend;

        /* Skip all the nodes which are completed before this one starts */
        this = jffs2_lookup_node_frag(root, newfrag->node->ofs);

        if (this) {
                JFFS2_DBG_FRAGTREE2("lookup gave frag 0x%04x-0x%04x; phys 0x%08x (*%p)\n",
                          this->ofs, this->ofs+this->size, this->node?(ref_offset(this->node->raw)):0xffffffff, this);
                lastend = this->ofs + this->size;
        } else {
                JFFS2_DBG_FRAGTREE2("lookup gave no frag\n");
                lastend = 0;
        }
                          
        /* See if we ran off the end of the fragtree */
        if (lastend <= newfrag->ofs) {
                /* We did */

                /* Check if 'this' node was on the same page as the new node.
                   If so, both 'this' and the new node get marked REF_NORMAL so
                   the GC can take a look.
                */
                if (lastend && (lastend-1) >> PAGE_CACHE_SHIFT == newfrag->ofs >> PAGE_CACHE_SHIFT) {
                        if (this->node)
                                mark_ref_normal(this->node->raw);
                        mark_ref_normal(newfrag->node->raw);
                }

                return no_overlapping_node(c, root, newfrag, this, lastend);
        }

        if (this->node)
                JFFS2_DBG_FRAGTREE2("dealing with frag %u-%u, phys %#08x(%d).\n",
                this->ofs, this->ofs + this->size,
                ref_offset(this->node->raw), ref_flags(this->node->raw));
        else
                JFFS2_DBG_FRAGTREE2("dealing with hole frag %u-%u.\n",
                this->ofs, this->ofs + this->size);

        /* OK. 'this' is pointing at the first frag that newfrag->ofs at least partially obsoletes,
         * - i.e. newfrag->ofs < this->ofs+this->size && newfrag->ofs >= this->ofs  
         */
        if (newfrag->ofs > this->ofs) {
                /* This node isn't completely obsoleted. The start of it remains valid */

                /* Mark the new node and the partially covered node REF_NORMAL -- let
                   the GC take a look at them */
                mark_ref_normal(newfrag->node->raw);
                if (this->node)
                        mark_ref_normal(this->node->raw);

                if (this->ofs + this->size > newfrag->ofs + newfrag->size) {
                        /* The new node splits 'this' frag into two */
                        struct jffs2_node_frag *newfrag2;

                        if (this->node)
                                JFFS2_DBG_FRAGTREE2("split old frag 0x%04x-0x%04x, phys 0x%08x\n",
                                        this->ofs, this->ofs+this->size, ref_offset(this->node->raw));
                        else 
                                JFFS2_DBG_FRAGTREE2("split old hole frag 0x%04x-0x%04x\n",
                                        this->ofs, this->ofs+this->size);
                        
                        /* New second frag pointing to this's node */
                        newfrag2 = new_fragment(this->node, newfrag->ofs + newfrag->size,
                                                this->ofs + this->size - newfrag->ofs - newfrag->size);
                        if (unlikely(!newfrag2))
                                return -ENOMEM;
                        if (this->node)
                                this->node->frags++;

                        /* Adjust size of original 'this' */
                        this->size = newfrag->ofs - this->ofs;

                        /* Now, we know there's no node with offset
                           greater than this->ofs but smaller than
                           newfrag2->ofs or newfrag->ofs, for obvious
                           reasons. So we can do a tree insert from
                           'this' to insert newfrag, and a tree insert
                           from newfrag to insert newfrag2. */
                        jffs2_fragtree_insert(newfrag, this);
                        rb_insert_color(&newfrag->rb, root);
                        
                        jffs2_fragtree_insert(newfrag2, newfrag);
                        rb_insert_color(&newfrag2->rb, root);
                        
                        return 0;
                }
                /* New node just reduces 'this' frag in size, doesn't split it */
                this->size = newfrag->ofs - this->ofs;

                /* Again, we know it lives down here in the tree */
                jffs2_fragtree_insert(newfrag, this);
                rb_insert_color(&newfrag->rb, root);
        } else {
                /* New frag starts at the same point as 'this' used to. Replace 
                   it in the tree without doing a delete and insertion */
                JFFS2_DBG_FRAGTREE2("inserting newfrag (*%p),%d-%d in before 'this' (*%p),%d-%d\n",
                          newfrag, newfrag->ofs, newfrag->ofs+newfrag->size, this, this->ofs, this->ofs+this->size);
        
                rb_replace_node(&this->rb, &newfrag->rb, root);
                
                if (newfrag->ofs + newfrag->size >= this->ofs+this->size) {
                        JFFS2_DBG_FRAGTREE2("obsoleting node frag %p (%x-%x)\n", this, this->ofs, this->ofs+this->size);
                        jffs2_obsolete_node_frag(c, this);
                } else {
                        this->ofs += newfrag->size;
                        this->size -= newfrag->size;

                        jffs2_fragtree_insert(this, newfrag);
                        rb_insert_color(&this->rb, root);
                        return 0;
                }
        }
        /* OK, now we have newfrag added in the correct place in the tree, but
           frag_next(newfrag) may be a fragment which is overlapped by it 
        */
        while ((this = frag_next(newfrag)) && newfrag->ofs + newfrag->size >= this->ofs + this->size) {
                /* 'this' frag is obsoleted completely. */
                JFFS2_DBG_FRAGTREE2("obsoleting node frag %p (%x-%x) and removing from tree\n",
                        this, this->ofs, this->ofs+this->size);
                rb_erase(&this->rb, root);
                jffs2_obsolete_node_frag(c, this);
        }
        /* Now we're pointing at the first frag which isn't totally obsoleted by 
           the new frag */

        if (!this || newfrag->ofs + newfrag->size == this->ofs)
                return 0;

        /* Still some overlap but we don't need to move it in the tree */
        this->size = (this->ofs + this->size) - (newfrag->ofs + newfrag->size);
        this->ofs = newfrag->ofs + newfrag->size;

        /* And mark them REF_NORMAL so the GC takes a look at them */
        if (this->node)
                mark_ref_normal(this->node->raw);
        mark_ref_normal(newfrag->node->raw);

        return 0;
}

/* 
 * Given an inode, probably with existing tree of fragments, add the new node
 * to the fragment tree.
 */
int jffs2_add_full_dnode_to_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f, struct jffs2_full_dnode *fn)
{
        int ret;
        struct jffs2_node_frag *newfrag;

        if (unlikely(!fn->size))
                return 0;

        newfrag = new_fragment(fn, fn->ofs, fn->size);
        if (unlikely(!newfrag))
                return -ENOMEM;
        newfrag->node->frags = 1;

        JFFS2_DBG_FRAGTREE("adding node %#04x-%#04x @0x%08x on flash, newfrag *%p\n",
                  fn->ofs, fn->ofs+fn->size, ref_offset(fn->raw), newfrag);
        
        ret = jffs2_add_frag_to_fragtree(c, &f->fragtree, newfrag);
        if (unlikely(ret))
                return ret;

        /* If we now share a page with other nodes, mark either previous
           or next node REF_NORMAL, as appropriate.  */
        if (newfrag->ofs & (PAGE_CACHE_SIZE-1)) {
                struct jffs2_node_frag *prev = frag_prev(newfrag);

                mark_ref_normal(fn->raw);
                /* If we don't start at zero there's _always_ a previous */     
                if (prev->node)
                        mark_ref_normal(prev->node->raw);
        }

        if ((newfrag->ofs+newfrag->size) & (PAGE_CACHE_SIZE-1)) {
                struct jffs2_node_frag *next = frag_next(newfrag);
                
                if (next) {
                        mark_ref_normal(fn->raw);
                        if (next->node)
                                mark_ref_normal(next->node->raw);
                }
        }
        jffs2_dbg_fragtree_paranoia_check_nolock(f);

        return 0;
}

/*
 * Check the data CRC of the node.
 *
 * Returns: 0 if the data CRC is correct;
 *          1 - if incorrect;
 *          error code if an error occured.
 */
static int check_node_data(struct jffs2_sb_info *c, struct jffs2_tmp_dnode_info *tn)
{
        struct jffs2_raw_node_ref *ref = tn->fn->raw;
        int err = 0, pointed = 0;
        struct jffs2_eraseblock *jeb;
        unsigned char *buffer;
        uint32_t crc, ofs, retlen, len;

        BUG_ON(tn->csize == 0);

        /* Calculate how many bytes were already checked */
        ofs = ref_offset(ref) + sizeof(struct jffs2_raw_inode);
        len = ofs & (c->wbuf_pagesize - 1);
        if (likely(len))
                len = c->wbuf_pagesize - len;

        if (len >= tn->csize) {
                JFFS2_DBG_READINODE("no need to check node at %#08x, data length %u, data starts at %#08x - it has already been checked.\n",
                        ref_offset(ref), tn->csize, ofs);
                goto adj_acc;
        }
        
        ofs += len;
        len = tn->csize - len;
        
        JFFS2_DBG_READINODE("check node at %#08x, data length %u, partial CRC %#08x, correct CRC %#08x, data starts at %#08x, start checking from %#08x - %u bytes.\n",
                ref_offset(ref), tn->csize, tn->partial_crc, tn->data_crc, ofs - len, ofs, len);
        
#ifndef __ECOS
        /* TODO: instead, incapsulate point() stuff to jffs2_flash_read(),
         * adding and jffs2_flash_read_end() interface. */
        if (c->mtd->point) {
                err = c->mtd->point(c->mtd, ofs, len, &retlen, &buffer);
                if (!err && retlen < tn->csize) {
                        JFFS2_WARNING("MTD point returned len too short: %u instead of %u.\n", retlen, tn->csize);
                        c->mtd->unpoint(c->mtd, buffer, ofs, len);
                } else if (err)
                        JFFS2_WARNING("MTD point failed: error code %d.\n", err);
                else
                        pointed = 1; /* succefully pointed to device */
        }
#endif
        
        if (!pointed) {
                buffer = kmalloc(len, GFP_KERNEL);
                if (unlikely(!buffer))
                        return -ENOMEM;
                        
                /* TODO: this is very frequent pattern, make it a separate
                 * routine */
                err = jffs2_flash_read(c, ofs, len, &retlen, buffer);
                if (err) {
                        JFFS2_ERROR("can not read %d bytes from 0x%08x, error code: %d.\n", len, ofs, err);
                        goto free_out;
                }
                        
                if (retlen != len) {
                        JFFS2_ERROR("short read at %#08x: %d instead of %d.\n", ofs, retlen, len);
                        err = -EIO;
                        goto free_out;
                }
        }

        /* Continue calculating CRC */
        crc = crc32(tn->partial_crc, buffer, len);
        if(!pointed)
                kfree(buffer);
#ifndef __ECOS
        else
                c->mtd->unpoint(c->mtd, buffer, ofs, len);
#endif

        if (crc != tn->data_crc) {
                JFFS2_NOTICE("wrong data CRC in data node at 0x%08x: read %#08x, calculated %#08x.\n",
                        ofs, tn->data_crc, crc);
                return 1;
        }

adj_acc:
        jeb = &c->blocks[ref->flash_offset / c->sector_size];
        len = ref_totlen(c, jeb, ref);

        /* 
         * Mark the node as having been checked and fix the
         * accounting accordingly.
         */
        spin_lock(&c->erase_completion_lock);
        jeb->used_size += len;
        jeb->unchecked_size -= len;
        c->used_size += len;
        c->unchecked_size -= len;
        spin_unlock(&c->erase_completion_lock);

        return 0;

free_out:
        if(!pointed)
                kfree(buffer);
#ifndef __ECOS
        else
                c->mtd->unpoint(c->mtd, buffer, ofs, len);
#endif
        return err;
}

/*
 * Helper function for jffs2_add_older_frag_to_fragtree().
 *
 * Checks the node if we are in the checking stage.
 */
static inline int check_node(struct jffs2_sb_info *c, struct jffs2_inode_info *f, struct jffs2_tmp_dnode_info *tn)
{
        int ret;
        
        BUG_ON(ref_obsolete(tn->fn->raw));

        /* We only check the data CRC of unchecked nodes */
        if (ref_flags(tn->fn->raw) != REF_UNCHECKED)
                return 0;
        
        JFFS2_DBG_FRAGTREE2("check node %#04x-%#04x, phys offs %#08x.\n",
                tn->fn->ofs, tn->fn->ofs + tn->fn->size, ref_offset(tn->fn->raw));

        ret = check_node_data(c, tn);
        if (unlikely(ret < 0)) {
                JFFS2_ERROR("check_node_data() returned error: %d.\n",
                        ret);
        } else if (unlikely(ret > 0)) {
                JFFS2_DBG_FRAGTREE2("CRC error, mark it obsolete.\n");
                jffs2_mark_node_obsolete(c, tn->fn->raw);
        }

        return ret;
}

/* 
 * Helper function for jffs2_add_older_frag_to_fragtree().
 *
 * Called when the new fragment that is being inserted
 * splits a hole fragment.
 */
static int split_hole(struct jffs2_sb_info *c, struct rb_root *root,
                      struct jffs2_node_frag *newfrag, struct jffs2_node_frag *hole)
{
        JFFS2_DBG_FRAGTREE2("fragment %#04x-%#04x splits the hole %#04x-%#04x\n",
                newfrag->ofs, newfrag->ofs + newfrag->size, hole->ofs, hole->ofs + hole->size);

        if (hole->ofs == newfrag->ofs) {
                /* 
                 * Well, the new fragment actually starts at the same offset as
                 * the hole.
                 */
                if (hole->ofs + hole->size > newfrag->ofs + newfrag->size) {
                        /* 
                         * We replace the overlapped left part of the hole by
                         * the new node.
                         */
                        
                        JFFS2_DBG_FRAGTREE2("insert fragment %#04x-%#04x and cut the left part of the hole\n",
                                newfrag->ofs, newfrag->ofs + newfrag->size);
                        rb_replace_node(&hole->rb, &newfrag->rb, root);
                        
                        hole->ofs += newfrag->size;
                        hole->size -= newfrag->size;
                        
                        /* 
                         * We know that 'hole' should be the right hand
                         * fragment.
                         */
                        jffs2_fragtree_insert(hole, newfrag);
                        rb_insert_color(&hole->rb, root);
                } else {
                        /* 
                         * Ah, the new fragment is of the same size as the hole.
                         * Relace the hole by it.
                         */
                        JFFS2_DBG_FRAGTREE2("insert fragment %#04x-%#04x and overwrite hole\n",
                                newfrag->ofs, newfrag->ofs + newfrag->size);
                        rb_replace_node(&hole->rb, &newfrag->rb, root);
                        jffs2_free_node_frag(hole);
                }
        } else {
                /* The new fragment lefts some hole space at the left */
                
                struct jffs2_node_frag * newfrag2 = NULL;

                if (hole->ofs + hole->size > newfrag->ofs + newfrag->size) {
                        /* The new frag also lefts some space at the right */
                        newfrag2 = new_fragment(NULL, newfrag->ofs +
                                newfrag->size, hole->ofs + hole->size
                                - newfrag->ofs - newfrag->size);
                        if (unlikely(!newfrag2)) {
                                jffs2_free_node_frag(newfrag);
                                return -ENOMEM;
                        }
                }

                hole->size = newfrag->ofs - hole->ofs;
                JFFS2_DBG_FRAGTREE2("left the hole %#04x-%#04x at the left and inserd fragment %#04x-%#04x\n",
                        hole->ofs, hole->ofs + hole->size, newfrag->ofs, newfrag->ofs + newfrag->size);

                jffs2_fragtree_insert(newfrag, hole);
                rb_insert_color(&newfrag->rb, root);
                
                if (newfrag2) {
                        JFFS2_DBG_FRAGTREE2("left the hole %#04x-%#04x at the right\n",
                                newfrag2->ofs, newfrag2->ofs + newfrag2->size);
                        jffs2_fragtree_insert(newfrag2, newfrag);
                        rb_insert_color(&newfrag2->rb, root);
                }
        }

        return 0;
}

/*
 * This function is used when we build inode. It expects the nodes are passed
 * in the decreasing version order. The whole point of this is to improve the
 * inodes checking on NAND: we check the nodes' data CRC only when they are not
 * obsoleted. Previously, add_frag_to_fragtree() function was used and
 * nodes were passed to it in the increasing version ordes and CRCs of all
 * nodes were checked.
 *
 * Note: tn->fn->size shouldn't be zero.
 *
 * Returns 0 if the node was inserted
 *         1 if it wasn't inserted (since it is obsolete)
 *         < 0 an if error occured
 */
int jffs2_add_older_frag_to_fragtree(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
                                     struct jffs2_tmp_dnode_info *tn)
{
        struct jffs2_node_frag *this, *newfrag;
        uint32_t lastend;
        struct jffs2_full_dnode *fn = tn->fn;
        struct rb_root *root = &f->fragtree;
        uint32_t fn_size = fn->size, fn_ofs = fn->ofs;
        int err, checked = 0;
        int ref_flag;

        JFFS2_DBG_FRAGTREE("insert fragment %#04x-%#04x, ver %u\n", fn_ofs, fn_ofs + fn_size, tn->version);

        /* Skip all the nodes which are completed before this one starts */
        this = jffs2_lookup_node_frag(root, fn_ofs);
        if (this)
                JFFS2_DBG_FRAGTREE2("'this' found %#04x-%#04x (%s)\n", this->ofs, this->ofs + this->size, this->node ? "data" : "hole");

        if (this)
                lastend = this->ofs + this->size;
        else
                lastend = 0;
        
        /* Detect the preliminary type of node */
        if (fn->size >= PAGE_CACHE_SIZE)
                ref_flag = REF_PRISTINE;
        else
                ref_flag = REF_NORMAL;
        
        /* See if we ran off the end of the root */
        if (lastend <= fn_ofs) {
                /* We did */
                
                /* 
                 * We are going to insert the new node into the
                 * fragment tree, so check it.
                 */
                err = check_node(c, f, tn);
                if (err != 0)
                        return err;

                fn->frags = 1;

                newfrag = new_fragment(fn, fn_ofs, fn_size);
                if (unlikely(!newfrag))
                        return -ENOMEM;

                err = no_overlapping_node(c, root, newfrag, this, lastend);
                if (unlikely(err != 0)) {
                        jffs2_free_node_frag(newfrag);
                        return err;
                }

                goto out_ok;
        }

        fn->frags = 0;

        while (1) {
                /* 
                 * Here we have:
                 * fn_ofs < this->ofs + this->size && fn_ofs >= this->ofs.
                 * 
                 * Remember, 'this' has higher version, any non-hole node
                 * which is already in the fragtree is newer then the newly
                 * inserted.
                 */
                if (!this->node) {
                        /* 
                         * 'this' is the hole fragment, so at least the
                         * beginning of the new fragment is valid.
                         */
                        
                        /* 
                         * We are going to insert the new node into the
                         * fragment tree, so check it.
                         */
                        if (!checked) {
                                err = check_node(c, f, tn);
                                if (unlikely(err != 0))
                                        return err;
                                checked = 1;
                        }
                        
                        if (this->ofs + this->size >= fn_ofs + fn_size) {
                                /* We split the hole on two parts */

                                fn->frags += 1;
                                newfrag = new_fragment(fn, fn_ofs, fn_size);
                                if (unlikely(!newfrag))
                                        return -ENOMEM;

                                err = split_hole(c, root, newfrag, this);
                                if (unlikely(err))
                                        return err;
                                goto out_ok;
                        }

                        /* 
                         * The beginning of the new fragment is valid since it
                         * overlaps the hole node.
                         */

                        ref_flag = REF_NORMAL;

                        fn->frags += 1;
                        newfrag = new_fragment(fn, fn_ofs,
                                        this->ofs + this->size - fn_ofs);
                        if (unlikely(!newfrag))
                                return -ENOMEM;
                        
                        if (fn_ofs == this->ofs) {
                                /* 
                                 * The new node starts at the same offset as
                                 * the hole and supersieds the hole.
                                 */
                                JFFS2_DBG_FRAGTREE2("add the new fragment instead of hole %#04x-%#04x, refcnt %d\n",
                                        fn_ofs, fn_ofs + this->ofs + this->size - fn_ofs, fn->frags);

                                rb_replace_node(&this->rb, &newfrag->rb, root);
                                jffs2_free_node_frag(this);
                        } else {
                                /* 
                                 * The hole becomes shorter as its right part
                                 * is supersieded by the new fragment.
                                 */
                                JFFS2_DBG_FRAGTREE2("reduce size of hole %#04x-%#04x to %#04x-%#04x\n",
                                        this->ofs, this->ofs + this->size, this->ofs, this->ofs + this->size - newfrag->size);
                                
                                JFFS2_DBG_FRAGTREE2("add new fragment %#04x-%#04x, refcnt %d\n", fn_ofs,
                                        fn_ofs + this->ofs + this->size - fn_ofs, fn->frags);
        
                                this->size -= newfrag->size;
                                jffs2_fragtree_insert(newfrag, this);
                                rb_insert_color(&newfrag->rb, root);
                        }
                        
                        fn_ofs += newfrag->size;
                        fn_size -= newfrag->size;
                        this = rb_entry(rb_next(&newfrag->rb),
                                        struct jffs2_node_frag, rb);

                        JFFS2_DBG_FRAGTREE2("switch to the next 'this' fragment: %#04x-%#04x %s\n",
                                this->ofs, this->ofs + this->size, this->node ? "(data)" : "(hole)");
                }

                /* 
                 * 'This' node is not the hole so it obsoletes the new fragment
                 * either fully or partially.
                 */
                if (this->ofs + this->size >= fn_ofs + fn_size) {
                        /* The new node is obsolete, drop it */
                        if (fn->frags == 0) {
                                JFFS2_DBG_FRAGTREE2("%#04x-%#04x is obsolete, mark it obsolete\n", fn_ofs, fn_ofs + fn_size);
                                ref_flag = REF_OBSOLETE;
                        }
                        goto out_ok;
                } else {
                        struct jffs2_node_frag *new_this;
                        
                        /* 'This' node obsoletes the beginning of the new node */
                        JFFS2_DBG_FRAGTREE2("the beginning %#04x-%#04x is obsolete\n", fn_ofs, this->ofs + this->size);

                        ref_flag = REF_NORMAL;
                        
                        fn_size -= this->ofs + this->size - fn_ofs;
                        fn_ofs = this->ofs + this->size;
                        JFFS2_DBG_FRAGTREE2("now considering %#04x-%#04x\n", fn_ofs, fn_ofs + fn_size);
                        
                        new_this = rb_entry(rb_next(&this->rb), struct jffs2_node_frag, rb);
                        if (!new_this) {
                                /* 
                                 * There is no next fragment. Add the rest of
                                 * the new node as the right-hand child.
                                 */
                                if (!checked) {
                                        err = check_node(c, f, tn);
                                        if (unlikely(err != 0))
                                                return err;
                                        checked = 1;
                                }
                                
                                fn->frags += 1;
                                newfrag = new_fragment(fn, fn_ofs, fn_size);
                                if (unlikely(!newfrag))
                                        return -ENOMEM;

                                JFFS2_DBG_FRAGTREE2("there are no more fragments, insert %#04x-%#04x\n",
                                        newfrag->ofs, newfrag->ofs + newfrag->size);
                                rb_link_node(&newfrag->rb, &this->rb, &this->rb.rb_right);                      
                                rb_insert_color(&newfrag->rb, root);
                                goto out_ok;
                        } else {
                                this = new_this;
                                JFFS2_DBG_FRAGTREE2("switch to the next 'this' fragment: %#04x-%#04x %s\n",
                                        this->ofs, this->ofs + this->size, this->node ? "(data)" : "(hole)");
                        }
                }
        }

out_ok:
        BUG_ON(fn->size < PAGE_CACHE_SIZE && ref_flag == REF_PRISTINE);

        if (ref_flag == REF_OBSOLETE) {
                JFFS2_DBG_FRAGTREE2("the node is obsolete now\n");
                /* jffs2_mark_node_obsolete() will adjust space accounting */
                jffs2_mark_node_obsolete(c, fn->raw);
                return 1;
        }

        JFFS2_DBG_FRAGTREE2("the node is \"%s\" now\n", ref_flag == REF_NORMAL ? "REF_NORMAL" : "REF_PRISTINE");

        /* Space accounting was adjusted at check_node_data() */
        spin_lock(&c->erase_completion_lock);
        fn->raw->flash_offset = ref_offset(fn->raw) | ref_flag;
        spin_unlock(&c->erase_completion_lock);

        return 0;
}

void jffs2_set_inocache_state(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic, int state)
{
        spin_lock(&c->inocache_lock);
        ic->state = state;
        wake_up(&c->inocache_wq);
        spin_unlock(&c->inocache_lock);
}

/* During mount, this needs no locking. During normal operation, its
   callers want to do other stuff while still holding the inocache_lock.
   Rather than introducing special case get_ino_cache functions or 
   callbacks, we just let the caller do the locking itself. */
   
struct jffs2_inode_cache *jffs2_get_ino_cache(struct jffs2_sb_info *c, uint32_t ino)
{
        struct jffs2_inode_cache *ret;

        ret = c->inocache_list[ino % INOCACHE_HASHSIZE];
        while (ret && ret->ino < ino) {
                ret = ret->next;
        }
        
        if (ret && ret->ino != ino)
                ret = NULL;

        return ret;
}

void jffs2_add_ino_cache (struct jffs2_sb_info *c, struct jffs2_inode_cache *new)
{
        struct jffs2_inode_cache **prev;

        spin_lock(&c->inocache_lock);
        if (!new->ino)
                new->ino = ++c->highest_ino;

        JFFS2_DBG_INOCACHE("add %p (ino #%u)\n", new, new->ino);

        prev = &c->inocache_list[new->ino % INOCACHE_HASHSIZE];

        while ((*prev) && (*prev)->ino < new->ino) {
                prev = &(*prev)->next;
        }
        new->next = *prev;
        *prev = new;

        spin_unlock(&c->inocache_lock);
}

void jffs2_del_ino_cache(struct jffs2_sb_info *c, struct jffs2_inode_cache *old)
{
        struct jffs2_inode_cache **prev;

        JFFS2_DBG_INOCACHE("del %p (ino #%u)\n", old, old->ino);
        spin_lock(&c->inocache_lock);
        
        prev = &c->inocache_list[old->ino % INOCACHE_HASHSIZE];
        
        while ((*prev) && (*prev)->ino < old->ino) {
                prev = &(*prev)->next;
        }
        if ((*prev) == old) {
                *prev = old->next;
        }

        /* Free it now unless it's in READING or CLEARING state, which
           are the transitions upon read_inode() and clear_inode(). The
           rest of the time we know nobody else is looking at it, and 
           if it's held by read_inode() or clear_inode() they'll free it
           for themselves. */
        if (old->state != INO_STATE_READING && old->state != INO_STATE_CLEARING)
                jffs2_free_inode_cache(old);

        spin_unlock(&c->inocache_lock);
}

void jffs2_free_ino_caches(struct jffs2_sb_info *c)
{
        int i;
        struct jffs2_inode_cache *this, *next;
        
        for (i=0; i<INOCACHE_HASHSIZE; i++) {
                this = c->inocache_list[i];
                while (this) {
                        next = this->next;
                        jffs2_free_inode_cache(this);
                        this = next;
                }
                c->inocache_list[i] = NULL;
        }
}

void jffs2_free_raw_node_refs(struct jffs2_sb_info *c)
{
        int i;
        struct jffs2_raw_node_ref *this, *next;

        for (i=0; i<c->nr_blocks; i++) {
                this = c->blocks[i].first_node;
                while(this) {
                        next = this->next_phys;
                        jffs2_free_raw_node_ref(this);
                        this = next;
                }
                c->blocks[i].first_node = c->blocks[i].last_node = NULL;
        }
}
        
struct jffs2_node_frag *jffs2_lookup_node_frag(struct rb_root *fragtree, uint32_t offset)
{
        /* The common case in lookup is that there will be a node 
           which precisely matches. So we go looking for that first */
        struct rb_node *next;
        struct jffs2_node_frag *prev = NULL;
        struct jffs2_node_frag *frag = NULL;

        JFFS2_DBG_FRAGTREE2("root %p, offset %d\n", fragtree, offset);

        next = fragtree->rb_node;

        while(next) {
                frag = rb_entry(next, struct jffs2_node_frag, rb);

                if (frag->ofs + frag->size <= offset) {
                        /* Remember the closest smaller match on the way down */
                        if (!prev || frag->ofs > prev->ofs)
                                prev = frag;
                        next = frag->rb.rb_right;
                } else if (frag->ofs > offset) {
                        next = frag->rb.rb_left;
                } else {
                        return frag;
                }
        }

        /* Exact match not found. Go back up looking at each parent,
           and return the closest smaller one */

        if (prev)
                JFFS2_DBG_FRAGTREE2("no match. Returning frag %#04x-%#04x, closest previous\n",
                          prev->ofs, prev->ofs+prev->size);
        else 
                JFFS2_DBG_FRAGTREE2("returning NULL, empty fragtree\n");
        
        return prev;
}

/* Pass 'c' argument to indicate that nodes should be marked obsolete as
   they're killed. */
void jffs2_kill_fragtree(struct rb_root *root, struct jffs2_sb_info *c)
{
        struct jffs2_node_frag *frag;
        struct jffs2_node_frag *parent;

        if (!root->rb_node)
                return;

        JFFS2_DBG_FRAGTREE("killing\n");
        
        frag = (rb_entry(root->rb_node, struct jffs2_node_frag, rb));
        while(frag) {
                if (frag->rb.rb_left) {
                        frag = frag_left(frag);
                        continue;
                }
                if (frag->rb.rb_right) {
                        frag = frag_right(frag);
                        continue;
                }

                if (frag->node && !(--frag->node->frags)) {
                        /* Not a hole, and it's the final remaining frag 
                           of this node. Free the node */
                        if (c)
                                jffs2_mark_node_obsolete(c, frag->node->raw);
                        
                        jffs2_free_full_dnode(frag->node);
                }
                parent = frag_parent(frag);
                if (parent) {
                        if (frag_left(parent) == frag)
                                parent->rb.rb_left = NULL;
                        else 
                                parent->rb.rb_right = NULL;
                }

                jffs2_free_node_frag(frag);
                frag = parent;

                cond_resched();
        }
}