Btrfs: Change the super to point to a tree of trees to enable persistent snapshots

[linux.git] / fs / btrfs / root-tree.c

#include <stdio.h>
#include <stdlib.h>
#include "kerncompat.h"
#include "radix-tree.h"
#include "ctree.h"
#include "disk-io.h"
#include "print-tree.h"

int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
			struct btrfs_root_item *item, struct btrfs_key *key)
{
	struct btrfs_path path;
	struct btrfs_key search_key;
	struct btrfs_leaf *l;
	int ret;
	int slot;

	search_key.objectid = objectid;
	search_key.flags = (u32)-1;
	search_key.offset = (u32)-1;

	btrfs_init_path(&path);
	ret = btrfs_search_slot(root, &search_key, &path, 0, 0);
	if (ret < 0)
		goto out;
	BUG_ON(ret == 0);
	l = &path.nodes[0]->leaf;
	BUG_ON(path.slots[0] == 0);
	slot = path.slots[0] - 1;
	if (btrfs_key_objectid(&l->items[slot].key) != objectid) {
		ret = 1;
		goto out;
	}
	memcpy(item, l->data + btrfs_item_offset(l->items + slot),
		sizeof(*item));
	btrfs_disk_key_to_cpu(key, &l->items[slot].key);
	btrfs_release_path(root, &path);
	ret = 0;
out:
	return ret;
}

int btrfs_update_root(struct btrfs_root *root, struct btrfs_key *key,
		      struct btrfs_root_item *item)
{
	struct btrfs_path path;
	struct btrfs_leaf *l;
	int ret;
	int slot;

	btrfs_init_path(&path);
	ret = btrfs_search_slot(root, key, &path, 0, 1);
	if (ret < 0)
		goto out;
	BUG_ON(ret != 0);
	l = &path.nodes[0]->leaf;
	slot = path.slots[0];
	memcpy(l->data + btrfs_item_offset(l->items + slot), item,
		sizeof(*item));
out:
	btrfs_release_path(root, &path);
	return ret;
}

int btrfs_insert_root(struct btrfs_root *root, struct btrfs_key *key,
		      struct btrfs_root_item *item)
{
	int ret;
	ret = btrfs_insert_item(root, key, item, sizeof(*item));
	BUG_ON(ret);
	return ret;
}

int btrfs_del_root(struct btrfs_root *root, struct btrfs_key *key)
{
	struct btrfs_path path;
	int ret;

	btrfs_init_path(&path);
	ret = btrfs_search_slot(root, key, &path, -1, 1);
	if (ret < 0)
		goto out;
	BUG_ON(ret != 0);
	ret = btrfs_del_item(root, &path);
out:
	btrfs_release_path(root, &path);
	return ret;
}