transaction.c

   1 /*
   2  * This program is free software; you can redistribute it and/or
   3  * modify it under the terms of the GNU General Public
   4  * License v2 as published by the Free Software Foundation.
   5  *
   6  * This program is distributed in the hope that it will be useful,
   7  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   8  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   9  * General Public License for more details.
  10  *
  11  * You should have received a copy of the GNU General Public
  12  * License along with this program; if not, write to the
  13  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  14  * Boston, MA 021110-1307, USA.
  15  */
  16
  17 #include "kerncompat.h"
  18 #include "disk-io.h"
  19 #include "transaction.h"
  20
  21 #include "messages.h"
  22
  23 struct btrfs_trans_handle* btrfs_start_transaction(struct btrfs_root *root,
  24                 int num_blocks)
  25 {
  26         struct btrfs_fs_info *fs_info = root->fs_info;
  27         struct btrfs_trans_handle *h = kzalloc(sizeof(*h), GFP_NOFS);
  28
  29         if (!h)
  30                 return ERR_PTR(-ENOMEM);
  31         if (root->commit_root) {
  32                 error("commit_root aleady set when starting transaction");
  33                 kfree(h);
  34                 return ERR_PTR(-EINVAL);
  35         }
  36         if (fs_info->running_transaction) {
  37                 error("attempt to start transaction over already running one");
  38                 kfree(h);
  39                 return ERR_PTR(-EINVAL);
  40         }
  41         fs_info->running_transaction = h;
  42         fs_info->generation++;
  43         h->transid = fs_info->generation;
  44         h->blocks_reserved = num_blocks;
  45         root->last_trans = h->transid;
  46         root->commit_root = root->node;
  47         extent_buffer_get(root->node);
  48
  49         return h;
  50 }
  51
  52 static int update_cowonly_root(struct btrfs_trans_handle *trans,
  53                                struct btrfs_root *root)
  54 {
  55         int ret;
  56         u64 old_root_bytenr;
  57         struct btrfs_root *tree_root = root->fs_info->tree_root;
  58
  59         btrfs_write_dirty_block_groups(trans, root);
  60         while(1) {
  61                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
  62                 if (old_root_bytenr == root->node->start)
  63                         break;
  64                 btrfs_set_root_bytenr(&root->root_item,
  65                                        root->node->start);
  66                 btrfs_set_root_generation(&root->root_item,
  67                                           trans->transid);
  68                 root->root_item.level = btrfs_header_level(root->node);
  69                 ret = btrfs_update_root(trans, tree_root,
  70                                         &root->root_key,
  71                                         &root->root_item);
  72                 BUG_ON(ret);
  73                 btrfs_write_dirty_block_groups(trans, root);
  74         }
  75         return 0;
  76 }
  77
  78 int commit_tree_roots(struct btrfs_trans_handle *trans,
  79                              struct btrfs_fs_info *fs_info)
  80 {
  81         struct btrfs_root *root;
  82         struct list_head *next;
  83         struct extent_buffer *eb;
  84         int ret;
  85
  86         if (fs_info->readonly)
  87                 return 0;
  88
  89         eb = fs_info->tree_root->node;
  90         extent_buffer_get(eb);
  91         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
  92         free_extent_buffer(eb);
  93         if (ret)
  94                 return ret;
  95
  96         while(!list_empty(&fs_info->dirty_cowonly_roots)) {
  97                 next = fs_info->dirty_cowonly_roots.next;
  98                 list_del_init(next);
  99                 root = list_entry(next, struct btrfs_root, dirty_list);
 100                 update_cowonly_root(trans, root);
 101                 free_extent_buffer(root->commit_root);
 102                 root->commit_root = NULL;
 103         }
 104
 105         return 0;
 106 }
 107
 108 int __commit_transaction(struct btrfs_trans_handle *trans,
 109                                 struct btrfs_root *root)
 110 {
 111         u64 start;
 112         u64 end;
 113         struct btrfs_fs_info *fs_info = root->fs_info;
 114         struct extent_buffer *eb;
 115         struct extent_io_tree *tree = &fs_info->extent_cache;
 116         int ret;
 117
 118         while(1) {
 119                 ret = find_first_extent_bit(tree, 0, &start, &end,
 120                                             EXTENT_DIRTY);
 121                 if (ret)
 122                         break;
 123                 while(start <= end) {
 124                         eb = find_first_extent_buffer(tree, start);
 125                         BUG_ON(!eb || eb->start != start);
 126                         ret = write_tree_block(trans, fs_info, eb);
 127                         BUG_ON(ret);
 128                         start += eb->len;
 129                         clear_extent_buffer_dirty(eb);
 130                         free_extent_buffer(eb);
 131                 }
 132         }
 133         return 0;
 134 }
 135
 136 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 137                              struct btrfs_root *root)
 138 {
 139         u64 transid = trans->transid;
 140         int ret = 0;
 141         struct btrfs_fs_info *fs_info = root->fs_info;
 142
 143         if (root->commit_root == root->node)
 144                 goto commit_tree;
 145         if (root == root->fs_info->tree_root)
 146                 goto commit_tree;
 147         if (root == root->fs_info->chunk_root)
 148                 goto commit_tree;
 149
 150         free_extent_buffer(root->commit_root);
 151         root->commit_root = NULL;
 152
 153         btrfs_set_root_bytenr(&root->root_item, root->node->start);
 154         btrfs_set_root_generation(&root->root_item, trans->transid);
 155         root->root_item.level = btrfs_header_level(root->node);
 156         ret = btrfs_update_root(trans, root->fs_info->tree_root,
 157                                 &root->root_key, &root->root_item);
 158         BUG_ON(ret);
 159 commit_tree:
 160         ret = commit_tree_roots(trans, fs_info);
 161         BUG_ON(ret);
 162         ret = __commit_transaction(trans, root);
 163         BUG_ON(ret);
 164         write_ctree_super(trans, fs_info);
 165         btrfs_finish_extent_commit(trans, fs_info->extent_root,
 166                                    &fs_info->pinned_extents);
 167         kfree(trans);
 168         free_extent_buffer(root->commit_root);
 169         root->commit_root = NULL;
 170         fs_info->running_transaction = NULL;
 171         fs_info->last_trans_committed = transid;
 172         return 0;
 173 }
 174