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