path: root/fs/btrfs/volumes.c

/*
 * Copyright (C) 2007 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 v2 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/sched.h>
#include <linux/bio.h>
#include "ctree.h"
#include "extent_map.h"
#include "disk-io.h"
#include "transaction.h"
#include "print-tree.h"
#include "volumes.h"

struct map_lookup {
	struct btrfs_device *dev;
	u64 physical;
};

/*
 * this uses a pretty simple search, the expectation is that it is
 * called very infrequently and that a given device has a small number
 * of extents
 */
static int find_free_dev_extent(struct btrfs_trans_handle *trans,
				struct btrfs_device *device,
				struct btrfs_path *path,
				u64 num_bytes, u64 *start)
{
	struct btrfs_key key;
	struct btrfs_root *root = device->dev_root;
	struct btrfs_dev_extent *dev_extent = NULL;
	u64 hole_size = 0;
	u64 last_byte = 0;
	u64 search_start = 0;
	u64 search_end = device->total_bytes;
	int ret;
	int slot = 0;
	int start_found;
	struct extent_buffer *l;

	start_found = 0;
	path->reada = 2;

	/* FIXME use last free of some kind */

	key.objectid = device->devid;
	key.offset = search_start;
	key.type = BTRFS_DEV_EXTENT_KEY;
	ret = btrfs_search_slot(trans, root, &key, path, 0, 0);
	if (ret < 0)
		goto error;
	ret = btrfs_previous_item(root, path, 0, key.type);
	if (ret < 0)
		goto error;
	l = path->nodes[0];
	btrfs_item_key_to_cpu(l, &key, path->slots[0]);
	while (1) {
		l = path->nodes[0];
		slot = path->slots[0];
		if (slot >= btrfs_header_nritems(l)) {
			ret = btrfs_next_leaf(root, path);
			if (ret == 0)
				continue;
			if (ret < 0)
				goto error;
no_more_items:
			if (!start_found) {
				if (search_start >= search_end) {
					ret = -ENOSPC;
					goto error;
				}
				*start = search_start;
				start_found = 1;
				goto check_pending;
			}
			*start = last_byte > search_start ?
				last_byte : search_start;
			if (search_end <= *start) {
				ret = -ENOSPC;
				goto error;
			}
			goto check_pending;
		}
		btrfs_item_key_to_cpu(l, &key, slot);

		if (key.objectid < device->devid)
			goto next;

		if (key.objectid > device->devid)
			goto no_more_items;

		if (key.offset >= search_start && key.offset > last_byte &&
		    start_found) {
			if (last_byte < search_start)
				last_byte = search_start;
			hole_size = key.offset - last_byte;
			if (key.offset > last_byte &&
			    hole_size >= num_bytes) {
				*start = last_byte;
				goto check_pending;
			}
		}
		if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY) {
			goto next;
		}

		start_found = 1;
		dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
		last_byte = key.offset + btrfs_dev_extent_length(l, dev_extent);
next:
		path->slots[0]++;
		cond_resched();
	}
check_pending:
	/* we have to make sure we didn't find an extent that has already
	 * been allocated by the map tree or the original allocation
	 */
	btrfs_release_path(root, path);
	BUG_ON(*start < search_start);

	if (*start + num_bytes > search_end) {
		ret = -ENOSPC;
		goto error;
	}
	/* check for pending inserts here */
	return 0;

error:
	btrfs_release_path(root, path);
	return ret;
}

int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
			   struct btrfs_device *device,
			   u64 owner, u64 num_bytes, u64 *start)
{
	int ret;
	struct btrfs_path *path;
	struct btrfs_root *root = device->dev_root;
	struct btrfs_dev_extent *extent;
	struct extent_buffer *leaf;
	struct btrfs_key key;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	ret = find_free_dev_extent(trans, device, path, num_bytes, start);
	if (ret) {
		goto err;
	}

	key.objectid = device->devid;
	key.offset = *start;
	key.type = BTRFS_DEV_EXTENT_KEY;
	ret = btrfs_insert_empty_item(trans, root, path,</