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