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 int btrfs_set_root_node(struct btrfs_root_item *item,
 115                         struct extent_buffer *node)
 116 {
 117         btrfs_set_root_bytenr(item, node->start);
 118         btrfs_set_root_level(item, btrfs_header_level(node));
 119         btrfs_set_root_generation(item, btrfs_header_generation(node));
 120         return 0;
 121 }
 122
 123 /*
 124  * copy the data in 'item' into the btree
 125  */
 126 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 127                       *root, struct btrfs_key *key, struct btrfs_root_item
 128                       *item)
 129 {
 130         struct btrfs_path *path;
 131         struct extent_buffer *l;
 132         int ret;
 133         int slot;
 134         unsigned long ptr;
 135
 136         path = btrfs_alloc_path();
 137         BUG_ON(!path);
 138         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 139         if (ret < 0)
 140                 goto out;
 141
 142         if (ret != 0) {
 143                 btrfs_print_leaf(root, path->nodes[0]);
 144                 printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
 145                        (unsigned long long)key->objectid, key->type,
 146                        (unsigned long long)key->offset);
 147                 BUG_ON(1);
 148         }
 149
 150         l = path->nodes[0];
 151         slot = path->slots[0];
 152         ptr = btrfs_item_ptr_offset(l, slot);
 153         write_extent_buffer(l, item, ptr, sizeof(*item));
 154         btrfs_mark_buffer_dirty(path->nodes[0]);
 155 out:
 156         btrfs_release_path(root, path);
 157         btrfs_free_path(path);
 158         return ret;
 159 }
 160
 161 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
 162                       *root, struct btrfs_key *key, struct btrfs_root_item
 163                       *item)
 164 {
 165         int ret;
 166         ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
 167         return ret;
 168 }
 169
 170 /*
 171  * at mount time we want to find all the old transaction snapshots that were in
 172  * the process of being deleted if we crashed.  This is any root item with an
 173  * offset lower than the latest root.  They need to be queued for deletion to
 174  * finish what was happening when we crashed.
 175  */
 176 int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
 177 {
 178         struct btrfs_root *dead_root;
 179         struct btrfs_item *item;
 180         struct btrfs_root_item *ri;
 181         struct btrfs_key key;
 182         struct btrfs_key found_key;
 183         struct btrfs_path *path;
 184         int ret;
 185         u32 nritems;
 186         struct extent_buffer *leaf;
 187         int slot;
 188
 189         key.objectid = objectid;
 190         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 191         key.offset = 0;
 192         path = btrfs_alloc_path();
 193         if (!path)
 194                 return -ENOMEM;
 195
 196 again:
 197         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 198         if (ret < 0)
 199                 goto err;
 200         while (1) {
 201                 leaf = path->nodes[0];
 202                 nritems = btrfs_header_nritems(leaf);
 203                 slot = path->slots[0];
 204                 if (slot >= nritems) {
 205                         ret = btrfs_next_leaf(root, path);
 206                         if (ret)
 207                                 break;
 208                         leaf = path->nodes[0];
 209                         nritems = btrfs_header_nritems(leaf);
 210                         slot = path->slots[0];
 211                 }
 212                 item = btrfs_item_nr(leaf, slot);
 213                 btrfs_item_key_to_cpu(leaf, &key, slot);
 214                 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
 215                         goto next;
 216
 217                 if (key.objectid < objectid)
 218                         goto next;
 219
 220                 if (key.objectid > objectid)
 221                         break;
 222
 223                 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
 224                 if (btrfs_disk_root_refs(leaf, ri) != 0)
 225                         goto next;
 226
 227                 memcpy(&found_key, &key, sizeof(key));
 228                 key.offset++;
 229                 btrfs_release_path(root, path);
 230                 dead_root =
 231                         btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
 232                                                     &found_key);
 233                 if (IS_ERR(dead_root)) {
 234                         ret = PTR_ERR(dead_root);
 235                         goto err;
 236                 }
 237
 238                 ret = btrfs_add_dead_root(dead_root);
 239                 if (ret)
 240                         goto err;
 241                 goto again;
 242 next:
 243                 slot++;
 244                 path->slots[0]++;
 245         }
 246         ret = 0;
 247 err:
 248         btrfs_free_path(path);
 249         return ret;
 250 }
 251
 252 /* drop the root item for 'key' from 'root' */
 253 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 254                    struct btrfs_key *key)
 255 {
 256         struct btrfs_path *path;
 257         int ret;
 258         u32 refs;
 259         struct btrfs_root_item *ri;
 260         struct extent_buffer *leaf;
 261
 262         path = btrfs_alloc_path();
 263         BUG_ON(!path);
 264         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 265         if (ret < 0)
 266                 goto out;
 267
 268         BUG_ON(ret != 0);
 269         leaf = path->nodes[0];
 270         ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
 271
 272         refs = btrfs_disk_root_refs(leaf, ri);
 273         BUG_ON(refs != 0);
 274         ret = btrfs_del_item(trans, root, path);
 275 out:
 276         btrfs_release_path(root, path);
 277         btrfs_free_path(path);
 278         return ret;
 279 }
 280
 281 #if 0 /* this will get used when snapshot deletion is implemented */
 282 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 283                        struct btrfs_root *tree_root,
 284                        u64 root_id, u8 type, u64 ref_id)
 285 {
 286         struct btrfs_key key;
 287         int ret;
 288         struct btrfs_path *path;
 289
 290         path = btrfs_alloc_path();
 291
 292         key.objectid = root_id;
 293         key.type = type;
 294         key.offset = ref_id;
 295
 296         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 297         BUG_ON(ret);
 298
 299         ret = btrfs_del_item(trans, tree_root, path);
 300         BUG_ON(ret);
 301
 302         btrfs_free_path(path);
 303         return ret;
 304 }
 305 #endif
 306
 307 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 308                    struct btrfs_path *path,
 309                    u64 root_id, u64 ref_id)
 310 {
 311         struct btrfs_key key;
 312         int ret;
 313
 314         key.objectid = root_id;
 315         key.type = BTRFS_ROOT_REF_KEY;
 316         key.offset = ref_id;
 317
 318         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 319         return ret;
 320 }
 321
 322
 323 /*
 324  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 325  * or BTRFS_ROOT_BACKREF_KEY.
 326  *
 327  * The dirid, sequence, name and name_len refer to the directory entry
 328  * that is referencing the root.
 329  *
 330  * For a forward ref, the root_id is the id of the tree referencing
 331  * the root and ref_id is the id of the subvol  or snapshot.
 332  *
 333  * For a back ref the root_id is the id of the subvol or snapshot and
 334  * ref_id is the id of the tree referencing it.
 335  */
 336 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 337                        struct btrfs_root *tree_root,
 338                        u64 root_id, u8 type, u64 ref_id,
 339                        u64 dirid, u64 sequence,
 340                        const char *name, int name_len)
 341 {
 342         struct btrfs_key key;
 343         int ret;
 344         struct btrfs_path *path;
 345         struct btrfs_root_ref *ref;
 346         struct extent_buffer *leaf;
 347         unsigned long ptr;
 348
 349
 350         path = btrfs_alloc_path();
 351
 352         key.objectid = root_id;
 353         key.type = type;
 354         key.offset = ref_id;
 355
 356         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 357                                       sizeof(*ref) + name_len);
 358         BUG_ON(ret);
 359
 360         leaf = path->nodes[0];
 361         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 362         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 363         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 364         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 365         ptr = (unsigned long)(ref + 1);
 366         write_extent_buffer(leaf, name, ptr, name_len);
 367         btrfs_mark_buffer_dirty(leaf);
 368
 369         btrfs_free_path(path);
 370         return ret;
 371 }