linux/fs/btrfs/inode-item.c
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   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 "disk-io.h"
  21#include "transaction.h"
  22#include "print-tree.h"
  23
  24static int find_name_in_backref(struct btrfs_path *path, const char *name,
  25                         int name_len, struct btrfs_inode_ref **ref_ret)
  26{
  27        struct extent_buffer *leaf;
  28        struct btrfs_inode_ref *ref;
  29        unsigned long ptr;
  30        unsigned long name_ptr;
  31        u32 item_size;
  32        u32 cur_offset = 0;
  33        int len;
  34
  35        leaf = path->nodes[0];
  36        item_size = btrfs_item_size_nr(leaf, path->slots[0]);
  37        ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
  38        while (cur_offset < item_size) {
  39                ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
  40                len = btrfs_inode_ref_name_len(leaf, ref);
  41                name_ptr = (unsigned long)(ref + 1);
  42                cur_offset += len + sizeof(*ref);
  43                if (len != name_len)
  44                        continue;
  45                if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0) {
  46                        *ref_ret = ref;
  47                        return 1;
  48                }
  49        }
  50        return 0;
  51}
  52
  53struct btrfs_inode_ref *
  54btrfs_lookup_inode_ref(struct btrfs_trans_handle *trans,
  55                        struct btrfs_root *root,
  56                        struct btrfs_path *path,
  57                        const char *name, int name_len,
  58                        u64 inode_objectid, u64 ref_objectid, int mod)
  59{
  60        struct btrfs_key key;
  61        struct btrfs_inode_ref *ref;
  62        int ins_len = mod < 0 ? -1 : 0;
  63        int cow = mod != 0;
  64        int ret;
  65
  66        key.objectid = inode_objectid;
  67        key.type = BTRFS_INODE_REF_KEY;
  68        key.offset = ref_objectid;
  69
  70        ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
  71        if (ret < 0)
  72                return ERR_PTR(ret);
  73        if (ret > 0)
  74                return NULL;
  75        if (!find_name_in_backref(path, name, name_len, &ref))
  76                return NULL;
  77        return ref;
  78}
  79
  80int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
  81                           struct btrfs_root *root,
  82                           const char *name, int name_len,
  83                           u64 inode_objectid, u64 ref_objectid, u64 *index)
  84{
  85        struct btrfs_path *path;
  86        struct btrfs_key key;
  87        struct btrfs_inode_ref *ref;
  88        struct extent_buffer *leaf;
  89        unsigned long ptr;
  90        unsigned long item_start;
  91        u32 item_size;
  92        u32 sub_item_len;
  93        int ret;
  94        int del_len = name_len + sizeof(*ref);
  95
  96        key.objectid = inode_objectid;
  97        key.offset = ref_objectid;
  98        btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
  99
 100        path = btrfs_alloc_path();
 101        if (!path)
 102                return -ENOMEM;
 103
 104        path->leave_spinning = 1;
 105
 106        ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 107        if (ret > 0) {
 108                ret = -ENOENT;
 109                goto out;
 110        } else if (ret < 0) {
 111                goto out;
 112        }
 113        if (!find_name_in_backref(path, name, name_len, &ref)) {
 114                ret = -ENOENT;
 115                goto out;
 116        }
 117        leaf = path->nodes[0];
 118        item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 119
 120        if (index)
 121                *index = btrfs_inode_ref_index(leaf, ref);
 122
 123        if (del_len == item_size) {
 124                ret = btrfs_del_item(trans, root, path);
 125                goto out;
 126        }
 127        ptr = (unsigned long)ref;
 128        sub_item_len = name_len + sizeof(*ref);
 129        item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 130        memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 131                              item_size - (ptr + sub_item_len - item_start));
 132        btrfs_truncate_item(trans, root, path,
 133                                  item_size - sub_item_len, 1);
 134out:
 135        btrfs_free_path(path);
 136        return ret;
 137}
 138
 139/* Will return 0, -ENOMEM, -EMLINK, or -EEXIST or anything from the CoW path */
 140int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
 141                           struct btrfs_root *root,
 142                           const char *name, int name_len,
 143                           u64 inode_objectid, u64 ref_objectid, u64 index)
 144{
 145        struct btrfs_path *path;
 146        struct btrfs_key key;
 147        struct btrfs_inode_ref *ref;
 148        unsigned long ptr;
 149        int ret;
 150        int ins_len = name_len + sizeof(*ref);
 151
 152        key.objectid = inode_objectid;
 153        key.offset = ref_objectid;
 154        btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
 155
 156        path = btrfs_alloc_path();
 157        if (!path)
 158                return -ENOMEM;
 159
 160        path->leave_spinning = 1;
 161        ret = btrfs_insert_empty_item(trans, root, path, &key,
 162                                      ins_len);
 163        if (ret == -EEXIST) {
 164                u32 old_size;
 165
 166                if (find_name_in_backref(path, name, name_len, &ref))
 167                        goto out;
 168
 169                old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
 170                btrfs_extend_item(trans, root, path, ins_len);
 171                ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 172                                     struct btrfs_inode_ref);
 173                ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
 174                btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
 175                btrfs_set_inode_ref_index(path->nodes[0], ref, index);
 176                ptr = (unsigned long)(ref + 1);
 177                ret = 0;
 178        } else if (ret < 0) {
 179                if (ret == -EOVERFLOW)
 180                        ret = -EMLINK;
 181                goto out;
 182        } else {
 183                ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 184                                     struct btrfs_inode_ref);
 185                btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
 186                btrfs_set_inode_ref_index(path->nodes[0], ref, index);
 187                ptr = (unsigned long)(ref + 1);
 188        }
 189        write_extent_buffer(path->nodes[0], name, ptr, name_len);
 190        btrfs_mark_buffer_dirty(path->nodes[0]);
 191
 192out:
 193        btrfs_free_path(path);
 194        return ret;
 195}
 196
 197int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
 198                             struct btrfs_root *root,
 199                             struct btrfs_path *path, u64 objectid)
 200{
 201        struct btrfs_key key;
 202        int ret;
 203        key.objectid = objectid;
 204        btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
 205        key.offset = 0;
 206
 207        ret = btrfs_insert_empty_item(trans, root, path, &key,
 208                                      sizeof(struct btrfs_inode_item));
 209        return ret;
 210}
 211
 212int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
 213                       *root, struct btrfs_path *path,
 214                       struct btrfs_key *location, int mod)
 215{
 216        int ins_len = mod < 0 ? -1 : 0;
 217        int cow = mod != 0;
 218        int ret;
 219        int slot;
 220        struct extent_buffer *leaf;
 221        struct btrfs_key found_key;
 222
 223        ret = btrfs_search_slot(trans, root, location, path, ins_len, cow);
 224        if (ret > 0 && btrfs_key_type(location) == BTRFS_ROOT_ITEM_KEY &&
 225            location->offset == (u64)-1 && path->slots[0] != 0) {
 226                slot = path->slots[0] - 1;
 227                leaf = path->nodes[0];
 228                btrfs_item_key_to_cpu(leaf, &found_key, slot);
 229                if (found_key.objectid == location->objectid &&
 230                    btrfs_key_type(&found_key) == btrfs_key_type(location)) {
 231                        path->slots[0]--;
 232                        return 0;
 233                }
 234        }
 235        return ret;
 236}
 237
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