path: root/fs/ocfs2/extent_map.c

/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * extent_map.c
 *
 * Block/Cluster mapping functions
 *
 * Copyright (C) 2004 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License, version 2,  as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/fiemap.h>

#include <cluster/masklog.h>

#include "ocfs2.h"

#include "alloc.h"
#include "dlmglue.h"
#include "extent_map.h"
#include "inode.h"
#include "super.h"
#include "symlink.h"
#include "ocfs2_trace.h"

#include "buffer_head_io.h"

/*
 * The extent caching implementation is intentionally trivial.
 *
 * We only cache a small number of extents stored directly on the
 * inode, so linear order operations are acceptable. If we ever want
 * to increase the size of the extent map, then these algorithms must
 * get smarter.
 */

void ocfs2_extent_map_init(struct inode *inode)
{
	struct ocfs2_inode_info *oi = OCFS2_I(inode);

	oi->ip_extent_map.em_num_items = 0;
	INIT_LIST_HEAD(&oi->ip_extent_map.em_list);
}

static void __ocfs2_extent_map_lookup(struct ocfs2_extent_map *em,
				      unsigned int cpos,
				      struct ocfs2_extent_map_item **ret_emi)
{
	unsigned int range;
	struct ocfs2_extent_map_item *emi;

	*ret_emi = NULL;

	list_for_each_entry(emi, &em->em_list, ei_list) {
		range = emi->ei_cpos + emi->ei_clusters;

		if (cpos >= emi->ei_cpos && cpos < range) {
			list_move(&emi->ei_list, &em->em_list);

			*ret_emi = emi;
			break;
		}
	}
}

static int ocfs2_extent_map_lookup(struct inode *inode, unsigned int cpos,
				   unsigned int *phys, unsigned int *len,
				   unsigned int *flags)
{
	unsigned int coff;
	struct ocfs2_inode_info *oi = OCFS2_I(inode);
	struct ocfs2_extent_map_item *emi;

	spin_lock(&oi->ip_lock);

	__ocfs2_extent_map_lookup(&oi->ip_extent_map, cpos, &emi);
	if (emi) {
		coff = cpos - emi->ei_cpos;
		*phys = emi->ei_phys + coff;
		if (len)
			*len = emi->ei_clusters - coff;
		if (flags)
			*flags = emi->ei_flags;
	}

	spin_unlock(&oi->ip_lock);

	if (emi == NULL)
		return -ENOENT;

	return 0;
}

/*
 * Forget about all clusters equal to or greater than cpos.
 */
void ocfs2_extent_map_trunc(struct inode *inode, unsigned int cpos)
{
	struct ocfs2_extent_map_item *emi, *n;
	struct ocfs2_inode_info *oi = OCFS2_I(inode);
	struct ocfs2_extent_map *em = &oi->ip_extent_map;
	LIST_HEAD(tmp_list);
	unsigned int range;

	spin_lock(&oi->ip_lock);
	list_for_each_entry_safe(emi, n, &em->em_list, ei_list) {
		if (emi->ei_cpos >= cpos) {
			/* Full truncate of this record. */
			list_move(&emi->ei_list, &tmp_list);
			BUG_ON(em->em_num_items == 0);
			em->em_num_items--;
			continue;
		}

		range = emi->ei_cpos + emi->ei_clusters;
		if (range > cpos) {
			/* Partial truncate */
			emi->ei_clusters = cpos - emi->ei_cpos;
		}
	}
	spin_unlock(&oi->ip_lock);

	list_for_each_entry_safe(emi, n, &tmp_list, ei_list) {
		list_del(&emi->ei_list);
		kfree(emi);
	}
}

/*
 * Is any part of emi2 contained within emi1
 */
static int ocfs2_ei_is_contained(struct ocfs2_extent_map_item *emi1,
				 struct ocfs2_extent_map_item *emi2)
{
	unsigned int range1, range2;

	/*
	 * Check if logical start of emi2 is inside emi1
	 */
	range1 = emi1->ei_cpos + emi1->ei_clusters;
	if (emi2->ei_cpos >= emi1->ei_cpos && emi2->ei_cpos < range1)
		return 1;

	/*
	 * Check if logical end of emi2 is inside emi1
	 */
	range2 = emi2->ei_cpos + emi2->ei_clusters;
	if (range2 > emi1->ei_cpos && range2 <=<