release/src-rt-6.x.4708/linux/linux-2.6.36/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 /* 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
  31 int 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 orig_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 (cache_only)
  46                 goto out;
  47
  48         if (root->fs_info->extent_root == root) {
  49                 /*
  50                  * there's recursion here right now in the tree locking,
  51                  * we can't defrag the extent root without deadlock
  52                  */
  53                 goto out;
  54         }
  55
  56         if (root->ref_cows == 0 && !is_extent)
  57                 goto out;
  58
  59         if (btrfs_test_opt(root, SSD))
  60                 goto out;
  61
  62         path = btrfs_alloc_path();
  63         if (!path)
  64                 return -ENOMEM;
  65
  66         level = btrfs_header_level(root->node);
  67         orig_level = level;
  68
  69         if (level == 0)
  70                 goto out;
  71
  72         if (root->defrag_progress.objectid == 0) {
  73                 struct extent_buffer *root_node;
  74                 u32 nritems;
  75
  76                 root_node = btrfs_lock_root_node(root);
  77                 btrfs_set_lock_blocking(root_node);
  78                 nritems = btrfs_header_nritems(root_node);
  79                 root->defrag_max.objectid = 0;
  80                 /* from above we know this is not a leaf */
  81                 btrfs_node_key_to_cpu(root_node, &root->defrag_max,
  82                                       nritems - 1);
  83                 btrfs_tree_unlock(root_node);
  84                 free_extent_buffer(root_node);
  85                 memset(&key, 0, sizeof(key));
  86         } else {
  87                 memcpy(&key, &root->defrag_progress, sizeof(key));
  88         }
  89
  90         path->keep_locks = 1;
  91         if (cache_only)
  92                 min_trans = root->defrag_trans_start;
  93
  94         ret = btrfs_search_forward(root, &key, NULL, path,
  95                                    cache_only, min_trans);
  96         if (ret < 0)
  97                 goto out;
  98         if (ret > 0) {
  99                 ret = 0;
 100                 goto out;
 101         }
 102         btrfs_release_path(root, path);
 103         wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
 104
 105         if (wret < 0) {
 106                 ret = wret;
 107                 goto out;
 108         }
 109         if (!path->nodes[1]) {
 110                 ret = 0;
 111                 goto out;
 112         }
 113         path->slots[1] = btrfs_header_nritems(path->nodes[1]);
 114         next_key_ret = btrfs_find_next_key(root, path, &key, 1, cache_only,
 115                                            min_trans);
 116         ret = btrfs_realloc_node(trans, root,
 117                                  path->nodes[1], 0,
 118                                  cache_only, &last_ret,
 119                                  &root->defrag_progress);
 120         if (ret) {
 121                 WARN_ON(ret == -EAGAIN);
 122                 goto out;
 123         }
 124         if (next_key_ret == 0) {
 125                 memcpy(&root->defrag_progress, &key, sizeof(key));
 126                 ret = -EAGAIN;
 127         }
 128 out:
 129         if (path)
 130                 btrfs_free_path(path);
 131         if (ret == -EAGAIN) {
 132                 if (root->defrag_max.objectid > root->defrag_progress.objectid)
 133                         goto done;
 134                 if (root->defrag_max.type > root->defrag_progress.type)
 135                         goto done;
 136                 if (root->defrag_max.offset > root->defrag_progress.offset)
 137                         goto done;
 138                 ret = 0;
 139         }
 140 done:
 141         if (ret != -EAGAIN) {
 142                 memset(&root->defrag_progress, 0,
 143                        sizeof(root->defrag_progress));
 144                 root->defrag_trans_start = trans->transid;
 145         }
 146         return ret;
 147 }