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 int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
  27                         struct btrfs_root *root, int cache_only)
  28 {
  29         struct btrfs_path *path = NULL;
  30         struct btrfs_key key;
  31         int ret = 0;
  32         int wret;
  33         int level;
  34         int orig_level;
  35         int is_extent = 0;
  36         int next_key_ret = 0;
  37         u64 last_ret = 0;
  38         u64 min_trans = 0;
  39
  40         if (cache_only)
  41                 goto out;
  42
  43         if (root->fs_info->extent_root == root) {
  44                 /*
  45                  * there's recursion here right now in the tree locking,
  46                  * we can't defrag the extent root without deadlock
  47                  */
  48                 goto out;
  49         }
  50
  51         if (root->ref_cows == 0 && !is_extent)
  52                 goto out;
  53
  54         if (btrfs_test_opt(root, SSD))
  55                 goto out;
  56
  57         path = btrfs_alloc_path();
  58         if (!path)
  59                 return -ENOMEM;
  60
  61         level = btrfs_header_level(root->node);
  62         orig_level = level;
  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                 nritems = btrfs_header_nritems(root_node);
  73                 root->defrag_max.objectid = 0;
  74                 /* from above we know this is not a leaf */
  75                 btrfs_node_key_to_cpu(root_node, &root->defrag_max,
  76                                       nritems - 1);
  77                 btrfs_tree_unlock(root_node);
  78                 free_extent_buffer(root_node);
  79                 memset(&key, 0, sizeof(key));
  80         } else {
  81                 memcpy(&key, &root->defrag_progress, sizeof(key));
  82         }
  83
  84         path->lowest_level = 1;
  85         path->keep_locks = 1;
  86         if (cache_only)
  87                 min_trans = root->defrag_trans_start;
  88
  89         ret = btrfs_search_forward(root, &key, path, cache_only, min_trans);
  90         if (ret < 0)
  91                 goto out;
  92         if (ret > 0) {
  93                 ret = 0;
  94                 goto out;
  95         }
  96         btrfs_release_path(root, path);
  97         wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
  98
  99         if (wret < 0) {
 100                 ret = wret;
 101                 goto out;
 102         }
 103         if (!path->nodes[1]) {
 104                 ret = 0;
 105                 goto out;
 106         }
 107         path->slots[1] = btrfs_header_nritems(path->nodes[1]);
 108         next_key_ret = btrfs_find_next_key(root, path, &key, 1, cache_only,
 109                                            min_trans);
 110         ret = btrfs_realloc_node(trans, root,
 111                                  path->nodes[1], 0,
 112                                  cache_only, &last_ret,
 113                                  &root->defrag_progress);
 114         WARN_ON(ret && ret != -EAGAIN);
 115         if (next_key_ret == 0) {
 116                 memcpy(&root->defrag_progress, &key, sizeof(key));
 117                 ret = -EAGAIN;
 118         }
 119
 120         btrfs_release_path(root, path);
 121         if (is_extent)
 122                 btrfs_extent_post_op(trans, root);
 123 out:
 124         if (is_extent)
 125                 mutex_unlock(&root->fs_info->alloc_mutex);
 126
 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         }
 138 done:
 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 }