LXR linux/fs/btrfs/tree-defrag.c

   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 is_extent = 0;
  41        int next_key_ret = 0;
  42        u64 last_ret = 0;
  43        u64 min_trans = 0;
  44
  45        if (root->fs_info->extent_root == root) {
  46                /*
  47                 * there's recursion here right now in the tree locking,
  48                 * we can't defrag the extent root without deadlock
  49                 */
  50                goto out;
  51        }
  52
  53        if (root->ref_cows == 0 && !is_extent)
  54                goto out;
  55
  56        if (btrfs_test_opt(root, SSD))
  57                goto out;
  58
  59        path = btrfs_alloc_path();
  60        if (!path)
  61                return -ENOMEM;
  62
  63        level = btrfs_header_level(root->node);
  64
  65        if (level == 0)
  66                goto out;
  67
  68        if (root->defrag_progress.objectid == 0) {
  69                struct extent_buffer *root_node;
  70                u32 nritems;
  71
  72                root_node = btrfs_lock_root_node(root);
  73                btrfs_set_lock_blocking(root_node);
  74                nritems = btrfs_header_nritems(root_node);
  75                root->defrag_max.objectid = 0;
  76                /* from above we know this is not a leaf */
  77                btrfs_node_key_to_cpu(root_node, &root->defrag_max,
  78                                      nritems - 1);
  79                btrfs_tree_unlock(root_node);
  80                free_extent_buffer(root_node);
  81                memset(&key, 0, sizeof(key));
  82        } else {
  83                memcpy(&key, &root->defrag_progress, sizeof(key));
  84        }
  85
  86        path->keep_locks = 1;
  87
  88        ret = btrfs_search_forward(root, &key, NULL, path, min_trans);
  89        if (ret < 0)
  90                goto out;
  91        if (ret > 0) {
  92                ret = 0;
  93                goto out;
  94        }
  95        btrfs_release_path(path);
  96        wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
  97
  98        if (wret < 0) {
  99                ret = wret;
 100                goto out;
 101        }
 102        if (!path->nodes[1]) {
 103                ret = 0;
 104                goto out;
 105        }
 106        path->slots[1] = btrfs_header_nritems(path->nodes[1]);
 107        next_key_ret = btrfs_find_next_key(root, path, &key, 1,
 108                                           min_trans);
 109        ret = btrfs_realloc_node(trans, root,
 110                                 path->nodes[1], 0,
 111                                 &last_ret,
 112                                 &root->defrag_progress);
 113        if (ret) {
 114                WARN_ON(ret == -EAGAIN);
 115                goto out;
 116        }
 117        if (next_key_ret == 0) {
 118                memcpy(&root->defrag_progress, &key, sizeof(key));
 119                ret = -EAGAIN;
 120        }
 121out:
 122        if (path)
 123                btrfs_free_path(path);
 124        if (ret == -EAGAIN) {
 125                if (root->defrag_max.objectid > root->defrag_progress.objectid)
 126                        goto done;
 127                if (root->defrag_max.type > root->defrag_progress.type)
 128                        goto done;
 129                if (root->defrag_max.offset > root->defrag_progress.offset)
 130                        goto done;
 131                ret = 0;
 132        }
 133done:
 134        if (ret != -EAGAIN) {
 135                memset(&root->defrag_progress, 0,
 136                       sizeof(root->defrag_progress));
 137                root->defrag_trans_start = trans->transid;
 138        }
 139        return ret;
 140}
 141