Pileus Git - ~andy/linux/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) || !buffer_defrag(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                         clear_buffer_defrag(path->nodes[*level]);
 146                         btrfs_block_release(root, path->nodes[*level]);
 147                         path->nodes[*level] = NULL;
 148                         *level = i + 1;
 149                 }
 150         }
 151         return 1;
 152 }
 153
 154 int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
 155                         struct btrfs_root *root, int cache_only)
 156 {
 157         struct btrfs_path *path = NULL;
 158         struct buffer_head *tmp;
 159         int ret = 0;
 160         int wret;
 161         int level;
 162         int orig_level;
 163         int i;
 164         int is_extent = 0;
 165         u64 last_ret = 0;
 166
 167         if (root->fs_info->extent_root == root)
 168                 is_extent = 1;
 169
 170         if (root->ref_cows == 0 && !is_extent)
 171                 goto out;
 172         path = btrfs_alloc_path();
 173         if (!path)
 174                 return -ENOMEM;
 175
 176         level = btrfs_header_level(btrfs_buffer_header(root->node));
 177         orig_level = level;
 178         if (level == 0) {
 179                 goto out;
 180         }
 181         if (root->defrag_progress.objectid == 0) {
 182                 get_bh(root->node);
 183                 ret = btrfs_cow_block(trans, root, root->node, NULL, 0, &tmp);
 184                 BUG_ON(ret);
 185                 ret = btrfs_realloc_node(trans, root, root->node, cache_only,
 186                                          &last_ret);
 187                 BUG_ON(ret);
 188                 path->nodes[level] = root->node;
 189                 path->slots[level] = 0;
 190                 if (is_extent)
 191                         btrfs_extent_post_op(trans, root);
 192         } else {
 193                 level = root->defrag_level;
 194                 path->lowest_level = level;
 195                 wret = btrfs_search_slot(trans, root, &root->defrag_progress,
 196                                          path, 0, 1);
 197
 198                 if (is_extent)
 199                         btrfs_extent_post_op(trans, root);
 200                 if (wret < 0) {
 201                         ret = wret;
 202                         goto out;
 203                 }
 204                 while(level > 0 && !path->nodes[level])
 205                         level--;
 206                 if (!path->nodes[level]) {
 207                         ret = 0;
 208                         goto out;
 209                 }
 210         }
 211
 212         while(1) {
 213                 wret = defrag_walk_down(trans, root, path, &level, cache_only,
 214                                         &last_ret);
 215                 if (wret > 0)
 216                         break;
 217                 if (wret < 0)
 218                         ret = wret;
 219
 220                 wret = defrag_walk_up(trans, root, path, &level, cache_only);
 221                 if (wret > 0)
 222                         break;
 223                 if (wret < 0)
 224                         ret = wret;
 225                 ret = -EAGAIN;
 226                 break;
 227         }
 228         for (i = 0; i <= orig_level; i++) {
 229                 if (path->nodes[i]) {
 230                         btrfs_block_release(root, path->nodes[i]);
 231                         path->nodes[i] = 0;
 232                 }
 233         }
 234 out:
 235         if (path)
 236                 btrfs_free_path(path);
 237         if (ret != -EAGAIN) {
 238                 memset(&root->defrag_progress, 0,
 239                        sizeof(root->defrag_progress));
 240         }
 241         return ret;
 242 }