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
  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         if (*level == 1 && cache_only && path->nodes[1] &&
  62             !btrfs_buffer_defrag(path->nodes[1])) {
  63                 goto out;
  64         }
  65         while(*level > 0) {
  66                 WARN_ON(*level < 0);
  67                 WARN_ON(*level >= BTRFS_MAX_LEVEL);
  68                 cur = path->nodes[*level];
  69
  70                 if (!cache_only && *level > 1 && path->slots[*level] == 0)
  71                         reada_defrag(root, cur);
  72
  73                 if (btrfs_header_level(cur) != *level)
  74                         WARN_ON(1);
  75
  76                 if (path->slots[*level] >=
  77                     btrfs_header_nritems(cur))
  78                         break;
  79
  80                 if (*level == 1) {
  81                         ret = btrfs_realloc_node(trans, root,
  82                                                  path->nodes[*level],
  83                                                  path->slots[*level],
  84                                                  cache_only, last_ret,
  85                                                  &root->defrag_progress);
  86                         if (is_extent)
  87                                 btrfs_extent_post_op(trans, root);
  88
  89                         break;
  90                 }
  91                 bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
  92
  93                 if (cache_only) {
  94                         next = btrfs_find_tree_block(root, bytenr,
  95                                            btrfs_level_size(root, *level - 1));
  96                         if (!next || !btrfs_buffer_uptodate(next) ||
  97                             !btrfs_buffer_defrag(next)) {
  98                                 free_extent_buffer(next);
  99                                 path->slots[*level]++;
 100                                 continue;
 101                         }
 102                 } else {
 103                         next = read_tree_block(root, bytenr,
 104                                        btrfs_level_size(root, *level - 1));
 105                 }
 106                 ret = btrfs_cow_block(trans, root, next, path->nodes[*level],
 107                                       path->slots[*level], &next);
 108                 BUG_ON(ret);
 109                 if (is_extent)
 110                         btrfs_extent_post_op(trans, root);
 111
 112                 WARN_ON(*level <= 0);
 113                 if (path->nodes[*level-1])
 114                         free_extent_buffer(path->nodes[*level-1]);
 115                 path->nodes[*level-1] = next;
 116                 *level = btrfs_header_level(next);
 117                 path->slots[*level] = 0;
 118         }
 119         WARN_ON(*level < 0);
 120         WARN_ON(*level >= BTRFS_MAX_LEVEL);
 121
 122         btrfs_clear_buffer_defrag(path->nodes[*level]);
 123 out:
 124         free_extent_buffer(path->nodes[*level]);
 125         path->nodes[*level] = NULL;
 126         *level += 1;
 127         WARN_ON(ret && ret != -EAGAIN);
 128         return ret;
 129 }
 130
 131 static int defrag_walk_up(struct btrfs_trans_handle *trans,
 132                           struct btrfs_root *root,
 133                           struct btrfs_path *path, int *level,
 134                           int cache_only)
 135 {
 136         int i;
 137         int slot;
 138         struct extent_buffer *node;
 139
 140         for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
 141                 slot = path->slots[i];
 142                 if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
 143                         path->slots[i]++;
 144                         *level = i;
 145                         node = path->nodes[i];
 146                         WARN_ON(i == 0);
 147                         btrfs_node_key_to_cpu(node, &root->defrag_progress,
 148                                               path->slots[i]);
 149                         root->defrag_level = i;
 150                         return 0;
 151                 } else {
 152                         btrfs_clear_buffer_defrag(path->nodes[*level]);
 153                         free_extent_buffer(path->nodes[*level]);
 154                         path->nodes[*level] = NULL;
 155                         *level = i + 1;
 156                 }
 157         }
 158         return 1;
 159 }
 160
 161 int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
 162                         struct btrfs_root *root, int cache_only)
 163 {
 164         struct btrfs_path *path = NULL;
 165         struct extent_buffer *tmp;
 166         int ret = 0;
 167         int wret;
 168         int level;
 169         int orig_level;
 170         int i;
 171         int is_extent = 0;
 172         u64 last_ret = 0;
 173
 174         if (root->fs_info->extent_root == root)
 175                 is_extent = 1;
 176
 177         if (root->ref_cows == 0 && !is_extent)
 178                 goto out;
 179
 180         path = btrfs_alloc_path();
 181         if (!path)
 182                 return -ENOMEM;
 183
 184         level = btrfs_header_level(root->node);
 185         orig_level = level;
 186
 187         if (level == 0) {
 188                 goto out;
 189         }
 190         if (root->defrag_progress.objectid == 0) {
 191                 extent_buffer_get(root->node);
 192                 ret = btrfs_cow_block(trans, root, root->node, NULL, 0, &tmp);
 193                 BUG_ON(ret);
 194                 path->nodes[level] = root->node;
 195                 path->slots[level] = 0;
 196                 if (is_extent)
 197                         btrfs_extent_post_op(trans, root);
 198         } else {
 199                 level = root->defrag_level;
 200                 path->lowest_level = level;
 201                 wret = btrfs_search_slot(trans, root, &root->defrag_progress,
 202                                          path, 0, 1);
 203
 204                 if (is_extent)
 205                         btrfs_extent_post_op(trans, root);
 206
 207                 if (wret < 0) {
 208                         ret = wret;
 209                         goto out;
 210                 }
 211
 212                 while(level > 0 && !path->nodes[level])
 213                         level--;
 214
 215                 if (!path->nodes[level]) {
 216                         ret = 0;
 217                         goto out;
 218                 }
 219         }
 220
 221         while(1) {
 222                 wret = defrag_walk_down(trans, root, path, &level, cache_only,
 223                                         &last_ret);
 224                 if (wret > 0)
 225                         break;
 226                 if (wret < 0)
 227                         ret = wret;
 228
 229                 wret = defrag_walk_up(trans, root, path, &level, cache_only);
 230                 if (wret > 0)
 231                         break;
 232                 if (wret < 0)
 233                         ret = wret;
 234                 else
 235                         ret = -EAGAIN;
 236                 break;
 237         }
 238         for (i = 0; i <= orig_level; i++) {
 239                 if (path->nodes[i]) {
 240                         free_extent_buffer(path->nodes[i]);
 241                         path->nodes[i] = NULL;
 242                 }
 243         }
 244 out:
 245         if (path)
 246                 btrfs_free_path(path);
 247         if (ret != -EAGAIN) {
 248                 memset(&root->defrag_progress, 0,
 249                        sizeof(root->defrag_progress));
 250         }
 251         return ret;
 252 }