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                                                  cache_only, last_ret);
  80                         if (is_extent)
  81                                 btrfs_extent_post_op(trans, root);
  82
  83                         break;
  84                 }
  85                 bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
  86
  87                 if (cache_only) {
  88                         next = btrfs_find_tree_block(root, bytenr,
  89                                            btrfs_level_size(root, *level - 1));
  90                         /* FIXME, test for defrag */
  91                         if (!next || !btrfs_buffer_uptodate(next)) {
  92                                 free_extent_buffer(next);
  93                                 path->slots[*level]++;
  94                                 continue;
  95                         }
  96                 } else {
  97                         next = read_tree_block(root, bytenr,
  98                                        btrfs_level_size(root, *level - 1));
  99                 }
 100                 ret = btrfs_cow_block(trans, root, next, path->nodes[*level],
 101                                       path->slots[*level], &next);
 102                 BUG_ON(ret);
 103                 ret = btrfs_realloc_node(trans, root, next, cache_only,
 104                                          last_ret);
 105                 BUG_ON(ret);
 106
 107                 if (is_extent)
 108                         btrfs_extent_post_op(trans, root);
 109
 110                 WARN_ON(*level <= 0);
 111                 if (path->nodes[*level-1])
 112                         free_extent_buffer(path->nodes[*level-1]);
 113                 path->nodes[*level-1] = next;
 114                 *level = btrfs_header_level(next);
 115                 path->slots[*level] = 0;
 116         }
 117         WARN_ON(*level < 0);
 118         WARN_ON(*level >= BTRFS_MAX_LEVEL);
 119 #if 0
 120         clear_buffer_defrag(path->nodes[*level]);
 121         clear_buffer_defrag_done(path->nodes[*level]);
 122 #endif
 123         free_extent_buffer(path->nodes[*level]);
 124         path->nodes[*level] = NULL;
 125         *level += 1;
 126         WARN_ON(ret);
 127         return 0;
 128 }
 129
 130 static int defrag_walk_up(struct btrfs_trans_handle *trans,
 131                           struct btrfs_root *root,
 132                           struct btrfs_path *path, int *level,
 133                           int cache_only)
 134 {
 135         int i;
 136         int slot;
 137         struct extent_buffer *node;
 138
 139         for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
 140                 slot = path->slots[i];
 141                 if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
 142                         path->slots[i]++;
 143                         *level = i;
 144                         node = path->nodes[i];
 145                         WARN_ON(i == 0);
 146                         btrfs_node_key_to_cpu(node, &root->defrag_progress,
 147                                               path->slots[i]);
 148                         root->defrag_level = i;
 149                         return 0;
 150                 } else {
 151                         /*
 152                         clear_buffer_defrag(path->nodes[*level]);
 153                         clear_buffer_defrag_done(path->nodes[*level]);
 154                         */
 155                         free_extent_buffer(path->nodes[*level]);
 156                         path->nodes[*level] = NULL;
 157                         *level = i + 1;
 158                 }
 159         }
 160         return 1;
 161 }
 162
 163 int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
 164                         struct btrfs_root *root, int cache_only)
 165 {
 166         struct btrfs_path *path = NULL;
 167         struct extent_buffer *tmp;
 168         int ret = 0;
 169         int wret;
 170         int level;
 171         int orig_level;
 172         int i;
 173         int is_extent = 0;
 174         u64 last_ret = 0;
 175
 176         if (root->fs_info->extent_root == root)
 177                 is_extent = 1;
 178
 179         if (root->ref_cows == 0 && !is_extent)
 180                 goto out;
 181
 182         path = btrfs_alloc_path();
 183         if (!path)
 184                 return -ENOMEM;
 185
 186         level = btrfs_header_level(root->node);
 187         orig_level = level;
 188         if (level == 0) {
 189                 goto out;
 190         }
 191         if (root->defrag_progress.objectid == 0) {
 192                 extent_buffer_get(root->node);
 193                 ret = btrfs_cow_block(trans, root, root->node, NULL, 0, &tmp);
 194                 BUG_ON(ret);
 195                 ret = btrfs_realloc_node(trans, root, root->node, cache_only,
 196                                          &last_ret);
 197                 BUG_ON(ret);
 198                 path->nodes[level] = root->node;
 199                 path->slots[level] = 0;
 200                 if (is_extent)
 201                         btrfs_extent_post_op(trans, root);
 202         } else {
 203                 level = root->defrag_level;
 204                 path->lowest_level = level;
 205                 wret = btrfs_search_slot(trans, root, &root->defrag_progress,
 206                                          path, 0, 1);
 207
 208                 if (is_extent)
 209                         btrfs_extent_post_op(trans, root);
 210
 211                 if (wret < 0) {
 212                         ret = wret;
 213                         goto out;
 214                 }
 215
 216                 while(level > 0 && !path->nodes[level])
 217                         level--;
 218
 219                 if (!path->nodes[level]) {
 220                         ret = 0;
 221                         goto out;
 222                 }
 223         }
 224
 225         while(1) {
 226                 wret = defrag_walk_down(trans, root, path, &level, cache_only,
 227                                         &last_ret);
 228                 if (wret > 0)
 229                         break;
 230                 if (wret < 0)
 231                         ret = wret;
 232
 233                 wret = defrag_walk_up(trans, root, path, &level, cache_only);
 234                 if (wret > 0)
 235                         break;
 236                 if (wret < 0)
 237                         ret = wret;
 238                 ret = -EAGAIN;
 239                 break;
 240         }
 241         for (i = 0; i <= orig_level; i++) {
 242                 if (path->nodes[i]) {
 243                         free_extent_buffer(path->nodes[i]);
 244                         path->nodes[i] = 0;
 245                 }
 246         }
 247 out:
 248         if (path)
 249                 btrfs_free_path(path);
 250         if (ret != -EAGAIN) {
 251                 memset(&root->defrag_progress, 0,
 252                        sizeof(root->defrag_progress));
 253         }
 254         return ret;
 255 }