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.type != BTRFS_ROOT_ITEM_KEY ||
  55             found_key.objectid != objectid) {
  56                 ret = -ENOENT;
  57                 goto out;
  58         }
  59         read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
  60                            sizeof(*item));
  61         memcpy(key, &found_key, sizeof(found_key));
  62         ret = 0;
  63 out:
  64         btrfs_free_path(path);
  65         return ret;
  66 }
  67
  68 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
  69                       *root, struct btrfs_key *key, struct btrfs_root_item
  70                       *item)
  71 {
  72         struct btrfs_path *path;
  73         struct extent_buffer *l;
  74         int ret;
  75         int slot;
  76         unsigned long ptr;
  77         u32 old_len;
  78
  79         path = btrfs_alloc_path();
  80         if (!path)
  81                 return -ENOMEM;
  82
  83         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
  84         if (ret < 0)
  85                 goto out;
  86         BUG_ON(ret != 0);
  87         l = path->nodes[0];
  88         slot = path->slots[0];
  89         ptr = btrfs_item_ptr_offset(l, slot);
  90         old_len = btrfs_item_size_nr(l, slot);
  91
  92         /*
  93          * If this is the first time we update the root item which originated
  94          * from an older kernel, we need to enlarge the item size to make room
  95          * for the added fields.
  96          */
  97         if (old_len < sizeof(*item)) {
  98                 btrfs_release_path(path);
  99                 ret = btrfs_search_slot(trans, root, key, path,
 100                                 -1, 1);
 101                 if (ret < 0) {
 102                         goto out;
 103                 }
 104
 105                 ret = btrfs_del_item(trans, root, path);
 106                 if (ret < 0) {
 107                         goto out;
 108                 }
 109                 btrfs_release_path(path);
 110                 ret = btrfs_insert_empty_item(trans, root, path,
 111                                 key, sizeof(*item));
 112                 if (ret < 0) {
 113                         goto out;
 114                 }
 115                 l = path->nodes[0];
 116                 slot = path->slots[0];
 117                 ptr = btrfs_item_ptr_offset(l, slot);
 118         }
 119
 120         /*
 121          * Update generation_v2 so at the next mount we know the new root
 122          * fields are valid.
 123          */
 124         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 125
 126         write_extent_buffer(l, item, ptr, sizeof(*item));
 127         btrfs_mark_buffer_dirty(path->nodes[0]);
 128 out:
 129         btrfs_free_path(path);
 130         return ret;
 131 }
 132
 133 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
 134                       *root, struct btrfs_key *key, struct btrfs_root_item
 135                       *item)
 136 {
 137         int ret;
 138
 139         /*
 140          * Make sure generation v1 and v2 match. See update_root for details.
 141          */
 142         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 143         ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
 144         return ret;
 145 }
 146
 147 /* drop the root item for 'key' from 'root' */
 148 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 149                    struct btrfs_key *key)
 150 {
 151         struct btrfs_path *path;
 152         int ret;
 153
 154         path = btrfs_alloc_path();
 155         if (!path)
 156                 return -ENOMEM;
 157         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 158         if (ret < 0)
 159                 goto out;
 160
 161         if (ret != 0) {
 162                 ret = -ENOENT;
 163                 goto out;
 164         }
 165
 166         ret = btrfs_del_item(trans, root, path);
 167 out:
 168         btrfs_free_path(path);
 169         return ret;
 170 }
 171
 172 /*
 173  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 174  * or BTRFS_ROOT_BACKREF_KEY.
 175  *
 176  * The dirid, sequence, name and name_len refer to the directory entry
 177  * that is referencing the root.
 178  *
 179  * For a forward ref, the root_id is the id of the tree referencing
 180  * the root and ref_id is the id of the subvol  or snapshot.
 181  *
 182  * For a back ref the root_id is the id of the subvol or snapshot and
 183  * ref_id is the id of the tree referencing it.
 184  */
 185 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 186                        struct btrfs_root *tree_root,
 187                        u64 root_id, u8 type, u64 ref_id,
 188                        u64 dirid, u64 sequence,
 189                        const char *name, int name_len)
 190 {
 191         struct btrfs_key key;
 192         int ret;
 193         struct btrfs_path *path;
 194         struct btrfs_root_ref *ref;
 195         struct extent_buffer *leaf;
 196         unsigned long ptr;
 197
 198
 199         path = btrfs_alloc_path();
 200         if (!path)
 201                 return -ENOMEM;
 202
 203         key.objectid = root_id;
 204         key.type = type;
 205         key.offset = ref_id;
 206
 207         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 208                                       sizeof(*ref) + name_len);
 209         BUG_ON(ret);
 210
 211         leaf = path->nodes[0];
 212         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 213         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 214         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 215         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 216         ptr = (unsigned long)(ref + 1);
 217         write_extent_buffer(leaf, name, ptr, name_len);
 218         btrfs_mark_buffer_dirty(leaf);
 219
 220         btrfs_free_path(path);
 221         return ret;
 222 }