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         h->fs_info = fs_info;
  42         fs_info->running_transaction = h;
  43         fs_info->generation++;
  44         h->transid = fs_info->generation;
  45         h->blocks_reserved = num_blocks;
  46         root->last_trans = h->transid;
  47         root->commit_root = root->node;
  48         extent_buffer_get(root->node);
  49
  50         return h;
  51 }
  52
  53 static int update_cowonly_root(struct btrfs_trans_handle *trans,
  54                                struct btrfs_root *root)
  55 {
  56         int ret;
  57         u64 old_root_bytenr;
  58         struct btrfs_root *tree_root = root->fs_info->tree_root;
  59
  60         btrfs_write_dirty_block_groups(trans, root);
  61         while(1) {
  62                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
  63                 if (old_root_bytenr == root->node->start)
  64                         break;
  65                 btrfs_set_root_bytenr(&root->root_item,
  66                                        root->node->start);
  67                 btrfs_set_root_generation(&root->root_item,
  68                                           trans->transid);
  69                 root->root_item.level = btrfs_header_level(root->node);
  70                 ret = btrfs_update_root(trans, tree_root,
  71                                         &root->root_key,
  72                                         &root->root_item);
  73                 BUG_ON(ret);
  74                 btrfs_write_dirty_block_groups(trans, root);
  75         }
  76         return 0;
  77 }
  78
  79 int commit_tree_roots(struct btrfs_trans_handle *trans,
  80                              struct btrfs_fs_info *fs_info)
  81 {
  82         struct btrfs_root *root;
  83         struct list_head *next;
  84         struct extent_buffer *eb;
  85         int ret;
  86
  87         if (fs_info->readonly)
  88                 return 0;
  89
  90         eb = fs_info->tree_root->node;
  91         extent_buffer_get(eb);
  92         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
  93         free_extent_buffer(eb);
  94         if (ret)
  95                 return ret;
  96
  97         while(!list_empty(&fs_info->dirty_cowonly_roots)) {
  98                 next = fs_info->dirty_cowonly_roots.next;
  99                 list_del_init(next);
 100                 root = list_entry(next, struct btrfs_root, dirty_list);
 101                 update_cowonly_root(trans, root);
 102                 free_extent_buffer(root->commit_root);
 103                 root->commit_root = NULL;
 104         }
 105
 106         return 0;
 107 }
 108
 109 int __commit_transaction(struct btrfs_trans_handle *trans,
 110                                 struct btrfs_root *root)
 111 {
 112         u64 start;
 113         u64 end;
 114         struct btrfs_fs_info *fs_info = root->fs_info;
 115         struct extent_buffer *eb;
 116         struct extent_io_tree *tree = &fs_info->extent_cache;
 117         int ret;
 118
 119         while(1) {
 120                 ret = find_first_extent_bit(tree, 0, &start, &end,
 121                                             EXTENT_DIRTY);
 122                 if (ret)
 123                         break;
 124                 while(start <= end) {
 125                         eb = find_first_extent_buffer(tree, start);
 126                         BUG_ON(!eb || eb->start != start);
 127                         ret = write_tree_block(trans, fs_info, eb);
 128                         BUG_ON(ret);
 129                         start += eb->len;
 130                         clear_extent_buffer_dirty(eb);
 131                         free_extent_buffer(eb);
 132                 }
 133         }
 134         return 0;
 135 }
 136
 137 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 138                              struct btrfs_root *root)
 139 {
 140         u64 transid = trans->transid;
 141         int ret = 0;
 142         struct btrfs_fs_info *fs_info = root->fs_info;
 143
 144         if (root->commit_root == root->node)
 145                 goto commit_tree;
 146         if (root == root->fs_info->tree_root)
 147                 goto commit_tree;
 148         if (root == root->fs_info->chunk_root)
 149                 goto commit_tree;
 150
 151         free_extent_buffer(root->commit_root);
 152         root->commit_root = NULL;
 153
 154         btrfs_set_root_bytenr(&root->root_item, root->node->start);
 155         btrfs_set_root_generation(&root->root_item, trans->transid);
 156         root->root_item.level = btrfs_header_level(root->node);
 157         ret = btrfs_update_root(trans, root->fs_info->tree_root,
 158                                 &root->root_key, &root->root_item);
 159         BUG_ON(ret);
 160 commit_tree:
 161         ret = commit_tree_roots(trans, fs_info);
 162         BUG_ON(ret);
 163         ret = __commit_transaction(trans, root);
 164         BUG_ON(ret);
 165         write_ctree_super(trans, fs_info);
 166         btrfs_finish_extent_commit(trans, fs_info->extent_root,
 167                                    &fs_info->pinned_extents);
 168         kfree(trans);
 169         free_extent_buffer(root->commit_root);
 170         root->commit_root = NULL;
 171         fs_info->running_transaction = NULL;
 172         fs_info->last_trans_committed = transid;
 173         return 0;
 174 }
 175
 176 void btrfs_abort_transaction(struct btrfs_trans_handle *trans, int error)
 177 {
 178         trans->fs_info->transaction_aborted = error;
 179 }