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 (fs_info->transaction_aborted)
  30                 return ERR_PTR(-EROFS);
  31
  32         if (!h)
  33                 return ERR_PTR(-ENOMEM);
  34         if (root->commit_root) {
  35                 error("commit_root aleady set when starting transaction");
  36                 kfree(h);
  37                 return ERR_PTR(-EINVAL);
  38         }
  39         if (fs_info->running_transaction) {
  40                 error("attempt to start transaction over already running one");
  41                 kfree(h);
  42                 return ERR_PTR(-EINVAL);
  43         }
  44         h->fs_info = fs_info;
  45         fs_info->running_transaction = h;
  46         fs_info->generation++;
  47         h->transid = fs_info->generation;
  48         h->blocks_reserved = num_blocks;
  49         root->last_trans = h->transid;
  50         root->commit_root = root->node;
  51         extent_buffer_get(root->node);
  52
  53         return h;
  54 }
  55
  56 static int update_cowonly_root(struct btrfs_trans_handle *trans,
  57                                struct btrfs_root *root)
  58 {
  59         int ret;
  60         u64 old_root_bytenr;
  61         struct btrfs_root *tree_root = root->fs_info->tree_root;
  62
  63         btrfs_write_dirty_block_groups(trans, root);
  64         while(1) {
  65                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
  66                 if (old_root_bytenr == root->node->start)
  67                         break;
  68                 btrfs_set_root_bytenr(&root->root_item,
  69                                        root->node->start);
  70                 btrfs_set_root_generation(&root->root_item,
  71                                           trans->transid);
  72                 root->root_item.level = btrfs_header_level(root->node);
  73                 ret = btrfs_update_root(trans, tree_root,
  74                                         &root->root_key,
  75                                         &root->root_item);
  76                 BUG_ON(ret);
  77                 btrfs_write_dirty_block_groups(trans, root);
  78         }
  79         return 0;
  80 }
  81
  82 int commit_tree_roots(struct btrfs_trans_handle *trans,
  83                              struct btrfs_fs_info *fs_info)
  84 {
  85         struct btrfs_root *root;
  86         struct list_head *next;
  87         struct extent_buffer *eb;
  88         int ret;
  89
  90         if (fs_info->readonly)
  91                 return 0;
  92
  93         eb = fs_info->tree_root->node;
  94         extent_buffer_get(eb);
  95         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
  96         free_extent_buffer(eb);
  97         if (ret)
  98                 return ret;
  99
 100         while(!list_empty(&fs_info->dirty_cowonly_roots)) {
 101                 next = fs_info->dirty_cowonly_roots.next;
 102                 list_del_init(next);
 103                 root = list_entry(next, struct btrfs_root, dirty_list);
 104                 update_cowonly_root(trans, root);
 105                 free_extent_buffer(root->commit_root);
 106                 root->commit_root = NULL;
 107         }
 108
 109         return 0;
 110 }
 111
 112 int __commit_transaction(struct btrfs_trans_handle *trans,
 113                                 struct btrfs_root *root)
 114 {
 115         u64 start;
 116         u64 end;
 117         struct btrfs_fs_info *fs_info = root->fs_info;
 118         struct extent_buffer *eb;
 119         struct extent_io_tree *tree = &fs_info->extent_cache;
 120         int ret;
 121
 122         while(1) {
 123                 ret = find_first_extent_bit(tree, 0, &start, &end,
 124                                             EXTENT_DIRTY);
 125                 if (ret)
 126                         break;
 127                 while(start <= end) {
 128                         eb = find_first_extent_buffer(tree, start);
 129                         BUG_ON(!eb || eb->start != start);
 130                         ret = write_tree_block(trans, fs_info, eb);
 131                         BUG_ON(ret);
 132                         start += eb->len;
 133                         clear_extent_buffer_dirty(eb);
 134                         free_extent_buffer(eb);
 135                 }
 136         }
 137         return 0;
 138 }
 139
 140 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 141                              struct btrfs_root *root)
 142 {
 143         u64 transid = trans->transid;
 144         int ret = 0;
 145         struct btrfs_fs_info *fs_info = root->fs_info;
 146
 147         if (trans->fs_info->transaction_aborted)
 148                 return -EROFS;
 149
 150         if (root->commit_root == root->node)
 151                 goto commit_tree;
 152         if (root == root->fs_info->tree_root)
 153                 goto commit_tree;
 154         if (root == root->fs_info->chunk_root)
 155                 goto commit_tree;
 156
 157         free_extent_buffer(root->commit_root);
 158         root->commit_root = NULL;
 159
 160         btrfs_set_root_bytenr(&root->root_item, root->node->start);
 161         btrfs_set_root_generation(&root->root_item, trans->transid);
 162         root->root_item.level = btrfs_header_level(root->node);
 163         ret = btrfs_update_root(trans, root->fs_info->tree_root,
 164                                 &root->root_key, &root->root_item);
 165         BUG_ON(ret);
 166 commit_tree:
 167         ret = commit_tree_roots(trans, fs_info);
 168         BUG_ON(ret);
 169         ret = __commit_transaction(trans, root);
 170         BUG_ON(ret);
 171         write_ctree_super(trans, fs_info);
 172         btrfs_finish_extent_commit(trans, fs_info->extent_root,
 173                                    &fs_info->pinned_extents);
 174         kfree(trans);
 175         free_extent_buffer(root->commit_root);
 176         root->commit_root = NULL;
 177         fs_info->running_transaction = NULL;
 178         fs_info->last_trans_committed = transid;
 179         return 0;
 180 }
 181
 182 void btrfs_abort_transaction(struct btrfs_trans_handle *trans, int error)
 183 {
 184         trans->fs_info->transaction_aborted = error;
 185 }