nodelist.c

linux 内核源代码

/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2001-2007 Red Hat, Inc.
 *
 * Created by David Woodhouse <[e-mail]>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#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"

static void jffs2_obsolete_node_frag(struct jffs2_sb_info *c,
				     struct jffs2_node_frag *this);

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;

	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) {
				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 Marking new dirent node is obsolete, old is \"%s\", ino #%u\n",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 {
				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;
}

uint32_t 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);

	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 0;

	frag = frag_last(list);

	/* Sanity check for truncation to longer than we started with... */
	if (!frag)
		return 0;
	if (frag->ofs + frag->size < size)
		return frag->ofs + frag->size;

	/* If the last fragment starts at the RAM page boundary, it is
	 * REF_PRISTINE irrespective of its size. */
	if (frag->node && (frag->ofs & (PAGE_CACHE_SIZE - 1)) == 0) {
		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;
	}
	return size;
}

static 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 */
			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 {
			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;

	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 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 */
			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 {
			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 */
		dbg_fragtree2("add the new node at the right\n");
		rb_link_node(&newfrag->rb, &this->rb, &this->rb.rb_right);
	} else {
		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) {
		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 {
		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)
		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
		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)
				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
				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 */
		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) {
			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. */
		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;

	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 */