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Linux/fs/btrfs/tree-defrag.c

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  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         WARN_ON(ret && ret != -EAGAIN);
121         if (next_key_ret == 0) {
122                 memcpy(&root->defrag_progress, &key, sizeof(key));
123                 ret = -EAGAIN;
124         }
125 
126         btrfs_release_path(root, path);
127 out:
128         if (path)
129                 btrfs_free_path(path);
130         if (ret == -EAGAIN) {
131                 if (root->defrag_max.objectid > root->defrag_progress.objectid)
132                         goto done;
133                 if (root->defrag_max.type > root->defrag_progress.type)
134                         goto done;
135                 if (root->defrag_max.offset > root->defrag_progress.offset)
136                         goto done;
137                 ret = 0;
138         }
139 done:
140         if (ret != -EAGAIN) {
141                 memset(&root->defrag_progress, 0,
142                        sizeof(root->defrag_progress));
143                 root->defrag_trans_start = trans->transid;
144         }
145         return ret;
146 }
147 

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