fs/btrfs/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 /*
  25  *  search forward for a root, starting with objectid 'search_start'
  26  *  if a root key is found, the objectid we find is filled into 'found_objectid'
  27  *  and 0 is returned.  < 0 is returned on error, 1 if there is nothing
  28  *  left in the tree.
  29  */
  30 int btrfs_search_root(struct btrfs_root *root, u64 search_start,
  31                       u64 *found_objectid)
  32 {
  33         struct btrfs_path *path;
  34         struct btrfs_key search_key;
  35         int ret;
  36
  37         root = root->fs_info->tree_root;
  38         search_key.objectid = search_start;
  39         search_key.type = (u8)-1;
  40         search_key.offset = (u64)-1;
  41
  42         path = btrfs_alloc_path();
  43         BUG_ON(!path);
  44 again:
  45         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
  46         if (ret < 0)
  47                 goto out;
  48         if (ret == 0) {
  49                 ret = 1;
  50                 goto out;
  51         }
  52         if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
  53                 ret = btrfs_next_leaf(root, path);
  54                 if (ret)
  55                         goto out;
  56         }
  57         btrfs_item_key_to_cpu(path->nodes[0], &search_key, path->slots[0]);
  58         if (search_key.type != BTRFS_ROOT_ITEM_KEY) {
  59                 search_key.offset++;
  60                 btrfs_release_path(root, path);
  61                 goto again;
  62         }
  63         ret = 0;
  64         *found_objectid = search_key.objectid;
  65
  66 out:
  67         btrfs_free_path(path);
  68         return ret;
  69 }
  70
  71 /*
  72  * lookup the root with the highest offset for a given objectid.  The key we do
  73  * find is copied into 'key'.  If we find something return 0, otherwise 1, < 0
  74  * on error.
  75  */
  76 int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
  77                         struct btrfs_root_item *item, struct btrfs_key *key)
  78 {
  79         struct btrfs_path *path;
  80         struct btrfs_key search_key;
  81         struct btrfs_key found_key;
  82         struct extent_buffer *l;
  83         int ret;
  84         int slot;
  85
  86         search_key.objectid = objectid;
  87         search_key.type = BTRFS_ROOT_ITEM_KEY;
  88         search_key.offset = (u64)-1;
  89
  90         path = btrfs_alloc_path();
  91         BUG_ON(!path);
  92         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
  93         if (ret < 0)
  94                 goto out;
  95
  96         BUG_ON(ret == 0);
  97         l = path->nodes[0];
  98         BUG_ON(path->slots[0] == 0);
  99         slot = path->slots[0] - 1;
 100         btrfs_item_key_to_cpu(l, &found_key, slot);
 101         if (found_key.objectid != objectid) {
 102                 ret = 1;
 103                 goto out;
 104         }
 105         read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
 106                            sizeof(*item));
 107         memcpy(key, &found_key, sizeof(found_key));
 108         ret = 0;
 109 out:
 110         btrfs_free_path(path);
 111         return ret;
 112 }
 113
 114 /*
 115  * copy the data in 'item' into the btree
 116  */
 117 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 118                       *root, struct btrfs_key *key, struct btrfs_root_item
 119                       *item)
 120 {
 121         struct btrfs_path *path;
 122         struct extent_buffer *l;
 123         int ret;
 124         int slot;
 125         unsigned long ptr;
 126
 127         path = btrfs_alloc_path();
 128         BUG_ON(!path);
 129         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 130         if (ret < 0)
 131                 goto out;
 132
 133         if (ret != 0) {
 134                 btrfs_print_leaf(root, path->nodes[0]);
 135                 printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
 136                        (unsigned long long)key->objectid, key->type,
 137                        (unsigned long long)key->offset);
 138                 BUG_ON(1);
 139         }
 140
 141         l = path->nodes[0];
 142         slot = path->slots[0];
 143         ptr = btrfs_item_ptr_offset(l, slot);
 144         write_extent_buffer(l, item, ptr, sizeof(*item));
 145         btrfs_mark_buffer_dirty(path->nodes[0]);
 146 out:
 147         btrfs_release_path(root, path);
 148         btrfs_free_path(path);
 149         return ret;
 150 }
 151
 152 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
 153                       *root, struct btrfs_key *key, struct btrfs_root_item
 154                       *item)
 155 {
 156         int ret;
 157         ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
 158         return ret;
 159 }
 160
 161 /*
 162  * at mount time we want to find all the old transaction snapshots that were in
 163  * the process of being deleted if we crashed.  This is any root item with an
 164  * offset lower than the latest root.  They need to be queued for deletion to
 165  * finish what was happening when we crashed.
 166  */
 167 int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid,
 168                           struct btrfs_root *latest)
 169 {
 170         struct btrfs_root *dead_root;
 171         struct btrfs_item *item;
 172         struct btrfs_root_item *ri;
 173         struct btrfs_key key;
 174         struct btrfs_key found_key;
 175         struct btrfs_path *path;
 176         int ret;
 177         u32 nritems;
 178         struct extent_buffer *leaf;
 179         int slot;
 180
 181         key.objectid = objectid;
 182         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 183         key.offset = 0;
 184         path = btrfs_alloc_path();
 185         if (!path)
 186                 return -ENOMEM;
 187
 188 again:
 189         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 190         if (ret < 0)
 191                 goto err;
 192         while (1) {
 193                 leaf = path->nodes[0];
 194                 nritems = btrfs_header_nritems(leaf);
 195                 slot = path->slots[0];
 196                 if (slot >= nritems) {
 197                         ret = btrfs_next_leaf(root, path);
 198                         if (ret)
 199                                 break;
 200                         leaf = path->nodes[0];
 201                         nritems = btrfs_header_nritems(leaf);
 202                         slot = path->slots[0];
 203                 }
 204                 item = btrfs_item_nr(leaf, slot);
 205                 btrfs_item_key_to_cpu(leaf, &key, slot);
 206                 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
 207                         goto next;
 208
 209                 if (key.objectid < objectid)
 210                         goto next;
 211
 212                 if (key.objectid > objectid)
 213                         break;
 214
 215                 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
 216                 if (btrfs_disk_root_refs(leaf, ri) != 0)
 217                         goto next;
 218
 219                 memcpy(&found_key, &key, sizeof(key));
 220                 key.offset++;
 221                 btrfs_release_path(root, path);
 222                 dead_root =
 223                         btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
 224                                                     &found_key);
 225                 if (IS_ERR(dead_root)) {
 226                         ret = PTR_ERR(dead_root);
 227                         goto err;
 228                 }
 229
 230                 if (objectid == BTRFS_TREE_RELOC_OBJECTID)
 231                         ret = btrfs_add_dead_reloc_root(dead_root);
 232                 else
 233                         ret = btrfs_add_dead_root(dead_root, latest);
 234                 if (ret)
 235                         goto err;
 236                 goto again;
 237 next:
 238                 slot++;
 239                 path->slots[0]++;
 240         }
 241         ret = 0;
 242 err:
 243         btrfs_free_path(path);
 244         return ret;
 245 }
 246
 247 /* drop the root item for 'key' from 'root' */
 248 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 249                    struct btrfs_key *key)
 250 {
 251         struct btrfs_path *path;
 252         int ret;
 253         u32 refs;
 254         struct btrfs_root_item *ri;
 255         struct extent_buffer *leaf;
 256
 257         path = btrfs_alloc_path();
 258         BUG_ON(!path);
 259         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 260         if (ret < 0)
 261                 goto out;
 262
 263         BUG_ON(ret != 0);
 264         leaf = path->nodes[0];
 265         ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
 266
 267         refs = btrfs_disk_root_refs(leaf, ri);
 268         BUG_ON(refs != 0);
 269         ret = btrfs_del_item(trans, root, path);
 270 out:
 271         btrfs_release_path(root, path);
 272         btrfs_free_path(path);
 273         return ret;
 274 }
 275
 276 #if 0 /* this will get used when snapshot deletion is implemented */
 277 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 278                        struct btrfs_root *tree_root,
 279                        u64 root_id, u8 type, u64 ref_id)
 280 {
 281         struct btrfs_key key;
 282         int ret;
 283         struct btrfs_path *path;
 284
 285         path = btrfs_alloc_path();
 286
 287         key.objectid = root_id;
 288         key.type = type;
 289         key.offset = ref_id;
 290
 291         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 292         BUG_ON(ret);
 293
 294         ret = btrfs_del_item(trans, tree_root, path);
 295         BUG_ON(ret);
 296
 297         btrfs_free_path(path);
 298         return ret;
 299 }
 300 #endif
 301
 302 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 303                    struct btrfs_path *path,
 304                    u64 root_id, u64 ref_id)
 305 {
 306         struct btrfs_key key;
 307         int ret;
 308
 309         key.objectid = root_id;
 310         key.type = BTRFS_ROOT_REF_KEY;
 311         key.offset = ref_id;
 312
 313         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 314         return ret;
 315 }
 316
 317
 318 /*
 319  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 320  * or BTRFS_ROOT_BACKREF_KEY.
 321  *
 322  * The dirid, sequence, name and name_len refer to the directory entry
 323  * that is referencing the root.
 324  *
 325  * For a forward ref, the root_id is the id of the tree referencing
 326  * the root and ref_id is the id of the subvol  or snapshot.
 327  *
 328  * For a back ref the root_id is the id of the subvol or snapshot and
 329  * ref_id is the id of the tree referencing it.
 330  */
 331 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 332                        struct btrfs_root *tree_root,
 333                        u64 root_id, u8 type, u64 ref_id,
 334                        u64 dirid, u64 sequence,
 335                        const char *name, int name_len)
 336 {
 337         struct btrfs_key key;
 338         int ret;
 339         struct btrfs_path *path;
 340         struct btrfs_root_ref *ref;
 341         struct extent_buffer *leaf;
 342         unsigned long ptr;
 343
 344
 345         path = btrfs_alloc_path();
 346
 347         key.objectid = root_id;
 348         key.type = type;
 349         key.offset = ref_id;
 350
 351         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 352                                       sizeof(*ref) + name_len);
 353         BUG_ON(ret);
 354
 355         leaf = path->nodes[0];
 356         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 357         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 358         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 359         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 360         ptr = (unsigned long)(ref + 1);
 361         write_extent_buffer(leaf, name, ptr, name_len);
 362         btrfs_mark_buffer_dirty(leaf);
 363
 364         btrfs_free_path(path);
 365         return ret;
 366 }