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 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         }
 121 out:
 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         }
 133 done:
 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 }