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/*
 27 * Defrag all the leaves in a given btree.
 28 * Read all the leaves and try to get key order to
 29 * better reflect disk order
 30 */
 31
 32int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
 33			struct btrfs_root *root)
 34{
 35	struct btrfs_path *path = NULL;
 36	struct btrfs_key key;
 37	int ret = 0;
 38	int wret;
 39	int level;
 40	int next_key_ret = 0;
 41	u64 last_ret = 0;
 42	u64 min_trans = 0;
 43
 44	if (root->fs_info->extent_root == root) {
 45		/*
 46		 * there's recursion here right now in the tree locking,
 47		 * we can't defrag the extent root without deadlock
 48		 */
 49		goto out;
 50	}
 51
 52	if (root->ref_cows == 0)
 53		goto out;
 54
 55	if (btrfs_test_opt(root, SSD))
 56		goto out;
 57
 58	path = btrfs_alloc_path();
 59	if (!path)
 60		return -ENOMEM;
 61
 62	level = btrfs_header_level(root->node);
 63
 64	if (level == 0)
 65		goto out;
 66
 67	if (root->defrag_progress.objectid == 0) {
 68		struct extent_buffer *root_node;
 69		u32 nritems;
 70
 71		root_node = btrfs_lock_root_node(root);
 72		btrfs_set_lock_blocking(root_node);
 73		nritems = btrfs_header_nritems(root_node);
 74		root->defrag_max.objectid = 0;
 75		/* from above we know this is not a leaf */
 76		btrfs_node_key_to_cpu(root_node, &root->defrag_max,
 77				      nritems - 1);
 78		btrfs_tree_unlock(root_node);
 79		free_extent_buffer(root_node);
 80		memset(&key, 0, sizeof(key));
 81	} else {
 82		memcpy(&key, &root->defrag_progress, sizeof(key));
 83	}
 84
 85	path->keep_locks = 1;
 86
 87	ret = btrfs_search_forward(root, &key, path, min_trans);
 88	if (ret < 0)
 89		goto out;
 90	if (ret > 0) {
 91		ret = 0;
 92		goto out;
 93	}
 94	btrfs_release_path(path);
 95	wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
 96
 97	if (wret < 0) {
 98		ret = wret;
 99		goto out;
100	}
101	if (!path->nodes[1]) {
102		ret = 0;
103		goto out;
104	}
105	path->slots[1] = btrfs_header_nritems(path->nodes[1]);
106	next_key_ret = btrfs_find_next_key(root, path, &key, 1,
107					   min_trans);
108	ret = btrfs_realloc_node(trans, root,
109				 path->nodes[1], 0,
110				 &last_ret,
111				 &root->defrag_progress);
112	if (ret) {
113		WARN_ON(ret == -EAGAIN);
114		goto out;
115	}
116	if (next_key_ret == 0) {
117		memcpy(&root->defrag_progress, &key, sizeof(key));
118		ret = -EAGAIN;
119	}
120out:
121	if (path)
122		btrfs_free_path(path);
123	if (ret == -EAGAIN) {
124		if (root->defrag_max.objectid > root->defrag_progress.objectid)
125			goto done;
126		if (root->defrag_max.type > root->defrag_progress.type)
127			goto done;
128		if (root->defrag_max.offset > root->defrag_progress.offset)
129			goto done;
130		ret = 0;
131	}
132done:
133	if (ret != -EAGAIN) {
134		memset(&root->defrag_progress, 0,
135		       sizeof(root->defrag_progress));
136		root->defrag_trans_start = trans->transid;
137	}
138	return ret;
139}