linux/fs/btrfs/tree-defrag.c
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   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}
 146
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