SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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 i;
  36         int is_extent = 0;
  37         int next_key_ret = 0;
  38         u64 last_ret = 0;
  39
  40         if (root->fs_info->extent_root == root) {
  41                 /*
  42                  * there's recursion here right now in the tree locking,
  43                  * we can't defrag the extent root without deadlock
  44                  */
  45                 goto out;
  46 #if 0
  47                 mutex_lock(&root->fs_info->alloc_mutex);
  48                 is_extent = 1;
  49 #endif
  50         }
  51
  52         if (root->ref_cows == 0 && !is_extent)
  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         orig_level = level;
  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                 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->lowest_level = 1;
  86         path->keep_locks = 1;
  87         wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
  88
  89         if (wret < 0) {
  90                 ret = wret;
  91                 goto out;
  92         }
  93         if (!path->nodes[1]) {
  94                 ret = 0;
  95                 goto out;
  96         }
  97         path->slots[1] = btrfs_header_nritems(path->nodes[1]);
  98         next_key_ret = btrfs_find_next_key(root, path, &key, 1);
  99         ret = btrfs_realloc_node(trans, root,
 100                                  path->nodes[1], 0,
 101                                  cache_only, &last_ret,
 102                                  &root->defrag_progress);
 103         WARN_ON(ret && ret != -EAGAIN);
 104         if (next_key_ret == 0) {
 105                 memcpy(&root->defrag_progress, &key, sizeof(key));
 106                 ret = -EAGAIN;
 107         }
 108
 109         for (i = 1; i < BTRFS_MAX_LEVEL; i++) {
 110                 if (path->locks[i]) {
 111                         btrfs_tree_unlock(path->nodes[i]);
 112                         path->locks[i] = 0;
 113                 }
 114                 if (path->nodes[i]) {
 115                         free_extent_buffer(path->nodes[i]);
 116                         path->nodes[i] = NULL;
 117                 }
 118         }
 119         if (is_extent)
 120                 btrfs_extent_post_op(trans, root);
 121
 122 out:
 123         if (is_extent)
 124                 mutex_unlock(&root->fs_info->alloc_mutex);
 125
 126         if (path)
 127                 btrfs_free_path(path);
 128         if (ret == -EAGAIN) {
 129                 if (root->defrag_max.objectid > root->defrag_progress.objectid)
 130                         goto done;
 131                 if (root->defrag_max.type > root->defrag_progress.type)
 132                         goto done;
 133                 if (root->defrag_max.offset > root->defrag_progress.offset)
 134                         goto done;
 135                 ret = 0;
 136         }
 137 done:
 138         if (ret != -EAGAIN) {
 139                 memset(&root->defrag_progress, 0,
 140                        sizeof(root->defrag_progress));
 141         }
 142         return ret;
 143 }