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
  32 int 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         }
 120 out:
 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         }
 132 done:
 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 }