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
  25 static void reada_defrag(struct btrfs_root *root,
  26                          struct extent_buffer *node)
  27 {
  28         int i;
  29         u32 nritems;
  30         u64 bytenr;
  31         u32 blocksize;
  32         int ret;
  33
  34         blocksize = btrfs_level_size(root, btrfs_header_level(node) - 1);
  35         nritems = btrfs_header_nritems(node);
  36         for (i = 0; i < nritems; i++) {
  37                 bytenr = btrfs_node_blockptr(node, i);
  38                 ret = readahead_tree_block(root, bytenr, blocksize);
  39                 if (ret)
  40                         break;
  41         }
  42 }
  43
  44 static int defrag_walk_down(struct btrfs_trans_handle *trans,
  45                             struct btrfs_root *root,
  46                             struct btrfs_path *path, int *level,
  47                             int cache_only, u64 *last_ret)
  48 {
  49         struct extent_buffer *next;
  50         struct extent_buffer *cur;
  51         u64 bytenr;
  52         int ret = 0;
  53         int is_extent = 0;
  54
  55         WARN_ON(*level < 0);
  56         WARN_ON(*level >= BTRFS_MAX_LEVEL);
  57
  58         if (root->fs_info->extent_root == root)
  59                 is_extent = 1;
  60
  61         while(*level > 0) {
  62                 WARN_ON(*level < 0);
  63                 WARN_ON(*level >= BTRFS_MAX_LEVEL);
  64                 cur = path->nodes[*level];
  65
  66                 if (!cache_only && *level > 1 && path->slots[*level] == 0)
  67                         reada_defrag(root, cur);
  68
  69                 if (btrfs_header_level(cur) != *level)
  70                         WARN_ON(1);
  71
  72                 if (path->slots[*level] >=
  73                     btrfs_header_nritems(cur))
  74                         break;
  75
  76                 if (*level == 1) {
  77                         ret = btrfs_realloc_node(trans, root,
  78                                                  path->nodes[*level],
  79                                                  path->slots[*level],
  80                                                  cache_only, last_ret,
  81                                                  &root->defrag_progress);
  82                         if (is_extent)
  83                                 btrfs_extent_post_op(trans, root);
  84
  85                         break;
  86                 }
  87                 bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
  88
  89                 if (cache_only) {
  90                         next = btrfs_find_tree_block(root, bytenr,
  91                                            btrfs_level_size(root, *level - 1));
  92                         if (!next || !btrfs_buffer_uptodate(next) ||
  93                             !btrfs_buffer_defrag(next)) {
  94                                 free_extent_buffer(next);
  95                                 path->slots[*level]++;
  96                                 continue;
  97                         }
  98                 } else {
  99                         next = read_tree_block(root, bytenr,
 100                                        btrfs_level_size(root, *level - 1));
 101                 }
 102                 ret = btrfs_cow_block(trans, root, next, path->nodes[*level],
 103                                       path->slots[*level], &next);
 104                 BUG_ON(ret);
 105                 if (is_extent)
 106                         btrfs_extent_post_op(trans, root);
 107
 108                 WARN_ON(*level <= 0);
 109                 if (path->nodes[*level-1])
 110                         free_extent_buffer(path->nodes[*level-1]);
 111                 path->nodes[*level-1] = next;
 112                 *level = btrfs_header_level(next);
 113                 path->slots[*level] = 0;
 114         }
 115         WARN_ON(*level < 0);
 116         WARN_ON(*level >= BTRFS_MAX_LEVEL);
 117
 118         btrfs_clear_buffer_defrag(path->nodes[*level]);
 119
 120         free_extent_buffer(path->nodes[*level]);
 121         path->nodes[*level] = NULL;
 122         *level += 1;
 123         WARN_ON(ret && ret != -EAGAIN);
 124         return ret;
 125 }
 126
 127 static int defrag_walk_up(struct btrfs_trans_handle *trans,
 128                           struct btrfs_root *root,
 129                           struct btrfs_path *path, int *level,
 130                           int cache_only)
 131 {
 132         int i;
 133         int slot;
 134         struct extent_buffer *node;
 135
 136         for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
 137                 slot = path->slots[i];
 138                 if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
 139                         path->slots[i]++;
 140                         *level = i;
 141                         node = path->nodes[i];
 142                         WARN_ON(i == 0);
 143                         btrfs_node_key_to_cpu(node, &root->defrag_progress,
 144                                               path->slots[i]);
 145                         root->defrag_level = i;
 146                         return 0;
 147                 } else {
 148                         btrfs_clear_buffer_defrag(path->nodes[*level]);
 149                         free_extent_buffer(path->nodes[*level]);
 150                         path->nodes[*level] = NULL;
 151                         *level = i + 1;
 152                 }
 153         }
 154         return 1;
 155 }
 156
 157 int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
 158                         struct btrfs_root *root, int cache_only)
 159 {
 160         struct btrfs_path *path = NULL;
 161         struct extent_buffer *tmp;
 162         int ret = 0;
 163         int wret;
 164         int level;
 165         int orig_level;
 166         int i;
 167         int is_extent = 0;
 168         u64 last_ret = 0;
 169
 170         if (root->fs_info->extent_root == root)
 171                 is_extent = 1;
 172
 173         if (root->ref_cows == 0 && !is_extent)
 174                 goto out;
 175
 176         path = btrfs_alloc_path();
 177         if (!path)
 178                 return -ENOMEM;
 179
 180         level = btrfs_header_level(root->node);
 181         orig_level = level;
 182
 183         if (level == 0) {
 184                 goto out;
 185         }
 186         if (root->defrag_progress.objectid == 0) {
 187                 extent_buffer_get(root->node);
 188                 ret = btrfs_cow_block(trans, root, root->node, NULL, 0, &tmp);
 189                 BUG_ON(ret);
 190                 path->nodes[level] = root->node;
 191                 path->slots[level] = 0;
 192                 if (is_extent)
 193                         btrfs_extent_post_op(trans, root);
 194         } else {
 195                 level = root->defrag_level;
 196                 path->lowest_level = level;
 197                 wret = btrfs_search_slot(trans, root, &root->defrag_progress,
 198                                          path, 0, 1);
 199
 200                 if (is_extent)
 201                         btrfs_extent_post_op(trans, root);
 202
 203                 if (wret < 0) {
 204                         ret = wret;
 205                         goto out;
 206                 }
 207
 208                 while(level > 0 && !path->nodes[level])
 209                         level--;
 210
 211                 if (!path->nodes[level]) {
 212                         ret = 0;
 213                         goto out;
 214                 }
 215         }
 216
 217         while(1) {
 218                 wret = defrag_walk_down(trans, root, path, &level, cache_only,
 219                                         &last_ret);
 220                 if (wret > 0)
 221                         break;
 222                 if (wret < 0)
 223                         ret = wret;
 224
 225                 wret = defrag_walk_up(trans, root, path, &level, cache_only);
 226                 if (wret > 0)
 227                         break;
 228                 if (wret < 0)
 229                         ret = wret;
 230                 ret = -EAGAIN;
 231                 break;
 232         }
 233         for (i = 0; i <= orig_level; i++) {
 234                 if (path->nodes[i]) {
 235                         free_extent_buffer(path->nodes[i]);
 236                         path->nodes[i] = NULL;
 237                 }
 238         }
 239 out:
 240         if (path)
 241                 btrfs_free_path(path);
 242         if (ret != -EAGAIN) {
 243                 memset(&root->defrag_progress, 0,
 244                        sizeof(root->defrag_progress));
 245         }
 246         return ret;
 247 }