root-tree.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 "ctree.h"
  20 #include "transaction.h"
  21 #include "disk-io.h"
  22 #include "print-tree.h"
  23
  24 int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
  25                         struct btrfs_root_item *item, struct btrfs_key *key)
  26 {
  27         struct btrfs_path *path;
  28         struct btrfs_key search_key;
  29         struct btrfs_key found_key;
  30         struct extent_buffer *l;
  31         int ret;
  32         int slot;
  33
  34         path = btrfs_alloc_path();
  35         if (!path)
  36                 return -ENOMEM;
  37
  38         search_key.objectid = objectid;
  39         search_key.type = BTRFS_ROOT_ITEM_KEY;
  40         search_key.offset = (u64)-1;
  41
  42         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
  43         if (ret < 0)
  44                 goto out;
  45         if (path->slots[0] == 0) {
  46                 ret = -ENOENT;
  47                 goto out;
  48         }
  49
  50         BUG_ON(ret == 0);
  51         l = path->nodes[0];
  52         slot = path->slots[0] - 1;
  53         btrfs_item_key_to_cpu(l, &found_key, slot);
  54         if (found_key.objectid != objectid) {
  55                 ret = -ENOENT;
  56                 goto out;
  57         }
  58         read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
  59                            sizeof(*item));
  60         memcpy(key, &found_key, sizeof(found_key));
  61         ret = 0;
  62 out:
  63         btrfs_free_path(path);
  64         return ret;
  65 }
  66
  67 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
  68                       *root, struct btrfs_key *key, struct btrfs_root_item
  69                       *item)
  70 {
  71         struct btrfs_path *path;
  72         struct extent_buffer *l;
  73         int ret;
  74         int slot;
  75         unsigned long ptr;
  76         u32 old_len;
  77
  78         path = btrfs_alloc_path();
  79         if (!path)
  80                 return -ENOMEM;
  81
  82         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
  83         if (ret < 0)
  84                 goto out;
  85         BUG_ON(ret != 0);
  86         l = path->nodes[0];
  87         slot = path->slots[0];
  88         ptr = btrfs_item_ptr_offset(l, slot);
  89         old_len = btrfs_item_size_nr(l, slot);
  90
  91         /*
  92          * If this is the first time we update the root item which originated
  93          * from an older kernel, we need to enlarge the item size to make room
  94          * for the added fields.
  95          */
  96         if (old_len < sizeof(*item)) {
  97                 btrfs_release_path(path);
  98                 ret = btrfs_search_slot(trans, root, key, path,
  99                                 -1, 1);
 100                 if (ret < 0) {
 101                         goto out;
 102                 }
 103
 104                 ret = btrfs_del_item(trans, root, path);
 105                 if (ret < 0) {
 106                         goto out;
 107                 }
 108                 btrfs_release_path(path);
 109                 ret = btrfs_insert_empty_item(trans, root, path,
 110                                 key, sizeof(*item));
 111                 if (ret < 0) {
 112                         goto out;
 113                 }
 114                 l = path->nodes[0];
 115                 slot = path->slots[0];
 116                 ptr = btrfs_item_ptr_offset(l, slot);
 117         }
 118
 119         /*
 120          * Update generation_v2 so at the next mount we know the new root
 121          * fields are valid.
 122          */
 123         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 124
 125         write_extent_buffer(l, item, ptr, sizeof(*item));
 126         btrfs_mark_buffer_dirty(path->nodes[0]);
 127 out:
 128         btrfs_free_path(path);
 129         return ret;
 130 }
 131
 132 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
 133                       *root, struct btrfs_key *key, struct btrfs_root_item
 134                       *item)
 135 {
 136         int ret;
 137
 138         /*
 139          * Make sure generation v1 and v2 match. See update_root for details.
 140          */
 141         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 142         ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
 143         return ret;
 144 }
 145
 146 /* drop the root item for 'key' from 'root' */
 147 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 148                    struct btrfs_key *key)
 149 {
 150         struct btrfs_path *path;
 151         int ret;
 152
 153         path = btrfs_alloc_path();
 154         if (!path)
 155                 return -ENOMEM;
 156         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 157         if (ret < 0)
 158                 goto out;
 159
 160         if (ret != 0) {
 161                 ret = -ENOENT;
 162                 goto out;
 163         }
 164
 165         ret = btrfs_del_item(trans, root, path);
 166 out:
 167         btrfs_free_path(path);
 168         return ret;
 169 }
 170
 171 /*
 172  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 173  * or BTRFS_ROOT_BACKREF_KEY.
 174  *
 175  * The dirid, sequence, name and name_len refer to the directory entry
 176  * that is referencing the root.
 177  *
 178  * For a forward ref, the root_id is the id of the tree referencing
 179  * the root and ref_id is the id of the subvol  or snapshot.
 180  *
 181  * For a back ref the root_id is the id of the subvol or snapshot and
 182  * ref_id is the id of the tree referencing it.
 183  */
 184 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 185                        struct btrfs_root *tree_root,
 186                        u64 root_id, u8 type, u64 ref_id,
 187                        u64 dirid, u64 sequence,
 188                        const char *name, int name_len)
 189 {
 190         struct btrfs_key key;
 191         int ret;
 192         struct btrfs_path *path;
 193         struct btrfs_root_ref *ref;
 194         struct extent_buffer *leaf;
 195         unsigned long ptr;
 196
 197
 198         path = btrfs_alloc_path();
 199         if (!path)
 200                 return -ENOMEM;
 201
 202         key.objectid = root_id;
 203         key.type = type;
 204         key.offset = ref_id;
 205
 206         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 207                                       sizeof(*ref) + name_len);
 208         BUG_ON(ret);
 209
 210         leaf = path->nodes[0];
 211         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 212         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 213         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 214         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 215         ptr = (unsigned long)(ref + 1);
 216         write_extent_buffer(leaf, name, ptr, name_len);
 217         btrfs_mark_buffer_dirty(leaf);
 218
 219         btrfs_free_path(path);
 220         return ret;
 221 }