1/*
  2 * Copyright (C) 2007 Oracle.  All rights reserved.
  3 *
  4 * This program is free software; you can redistribute it and/or
  5 * modify it under the terms of the GNU General Public
  6 * License v2 as published by the Free Software Foundation.
  7 *
  8 * This program is distributed in the hope that it will be useful,
  9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 11 * General Public License for more details.
 12 *
 13 * You should have received a copy of the GNU General Public
 14 * License along with this program; if not, write to the
 15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 16 * Boston, MA 021110-1307, USA.
 17 */
 18
 19#include <linux/sched.h>
 20#include "ctree.h"
 21#include "disk-io.h"
 22#include "print-tree.h"
 23#include "transaction.h"
 24#include "locking.h"
 25
 26/* defrag all the leaves in a given btree.  If cache_only == 1, don't read
 27 * things from disk, otherwise read all the leaves and try to get key order to
 28 * better reflect disk order
 29 */
 30
 31int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
 32			struct btrfs_root *root, int cache_only)
 33{
 34	struct btrfs_path *path = NULL;
 35	struct btrfs_key key;
 36	int ret = 0;
 37	int wret;
 38	int level;
 39	int is_extent = 0;
 40	int next_key_ret = 0;
 41	u64 last_ret = 0;
 42	u64 min_trans = 0;
 43
 44	if (cache_only)
 45		goto out;
 46
 47	if (root->fs_info->extent_root == root) {
 48		/*
 49		 * there's recursion here right now in the tree locking,
 50		 * we can't defrag the extent root without deadlock
 51		 */
 52		goto out;
 53	}
 54
 55	if (root->ref_cows == 0 && !is_extent)
 56		goto out;
 57
 58	if (btrfs_test_opt(root, SSD))
 59		goto out;
 60
 61	path = btrfs_alloc_path();
 62	if (!path)
 63		return -ENOMEM;
 64
 65	level = btrfs_header_level(root->node);
 66
 67	if (level == 0)
 68		goto out;
 69
 70	if (root->defrag_progress.objectid == 0) {
 71		struct extent_buffer *root_node;
 72		u32 nritems;
 73
 74		root_node = btrfs_lock_root_node(root);
 75		btrfs_set_lock_blocking(root_node);
 76		nritems = btrfs_header_nritems(root_node);
 77		root->defrag_max.objectid = 0;
 78		/* from above we know this is not a leaf */
 79		btrfs_node_key_to_cpu(root_node, &root->defrag_max,
 80				      nritems - 1);
 81		btrfs_tree_unlock(root_node);
 82		free_extent_buffer(root_node);
 83		memset(&key, 0, sizeof(key));
 84	} else {
 85		memcpy(&key, &root->defrag_progress, sizeof(key));
 86	}
 87
 88	path->keep_locks = 1;
 89	if (cache_only)
 90		min_trans = root->defrag_trans_start;
 91
 92	ret = btrfs_search_forward(root, &key, NULL, path,
 93				   cache_only, min_trans);
 94	if (ret < 0)
 95		goto out;
 96	if (ret > 0) {
 97		ret = 0;
 98		goto out;
 99	}
100	btrfs_release_path(path);
101	wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
102
103	if (wret < 0) {
104		ret = wret;
105		goto out;
106	}
107	if (!path->nodes[1]) {
108		ret = 0;
109		goto out;
110	}
111	path->slots[1] = btrfs_header_nritems(path->nodes[1]);
112	next_key_ret = btrfs_find_next_key(root, path, &key, 1, cache_only,
113					   min_trans);
114	ret = btrfs_realloc_node(trans, root,
115				 path->nodes[1], 0,
116				 cache_only, &last_ret,
117				 &root->defrag_progress);
118	if (ret) {
119		WARN_ON(ret == -EAGAIN);
120		goto out;
121	}
122	if (next_key_ret == 0) {
123		memcpy(&root->defrag_progress, &key, sizeof(key));
124		ret = -EAGAIN;
125	}
126out:
127	if (path)
128		btrfs_free_path(path);
129	if (ret == -EAGAIN) {
130		if (root->defrag_max.objectid > root->defrag_progress.objectid)
131			goto done;
132		if (root->defrag_max.type > root->defrag_progress.type)
133			goto done;
134		if (root->defrag_max.offset > root->defrag_progress.offset)
135			goto done;
136		ret = 0;
137	}
138done:
139	if (ret != -EAGAIN) {
140		memset(&root->defrag_progress, 0,
141		       sizeof(root->defrag_progress));
142		root->defrag_trans_start = trans->transid;
143	}
144	return ret;
145}