fs/btrfs/inode-item.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 "disk-io.h"
  21 #include "transaction.h"
  22
  23 static int find_name_in_backref(struct btrfs_path *path, const char *name,
  24                          int name_len, struct btrfs_inode_ref **ref_ret)
  25 {
  26         struct extent_buffer *leaf;
  27         struct btrfs_inode_ref *ref;
  28         unsigned long ptr;
  29         unsigned long name_ptr;
  30         u32 item_size;
  31         u32 cur_offset = 0;
  32         int len;
  33
  34         leaf = path->nodes[0];
  35         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
  36         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
  37         while (cur_offset < item_size) {
  38                 ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
  39                 len = btrfs_inode_ref_name_len(leaf, ref);
  40                 name_ptr = (unsigned long)(ref + 1);
  41                 cur_offset += len + sizeof(*ref);
  42                 if (len != name_len)
  43                         continue;
  44                 if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0) {
  45                         *ref_ret = ref;
  46                         return 1;
  47                 }
  48         }
  49         return 0;
  50 }
  51
  52 struct btrfs_inode_ref *
  53 btrfs_lookup_inode_ref(struct btrfs_trans_handle *trans,
  54                         struct btrfs_root *root,
  55                         struct btrfs_path *path,
  56                         const char *name, int name_len,
  57                         u64 inode_objectid, u64 ref_objectid, int mod)
  58 {
  59         struct btrfs_key key;
  60         struct btrfs_inode_ref *ref;
  61         int ins_len = mod < 0 ? -1 : 0;
  62         int cow = mod != 0;
  63         int ret;
  64
  65         key.objectid = inode_objectid;
  66         key.type = BTRFS_INODE_REF_KEY;
  67         key.offset = ref_objectid;
  68
  69         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
  70         if (ret < 0)
  71                 return ERR_PTR(ret);
  72         if (ret > 0)
  73                 return NULL;
  74         if (!find_name_in_backref(path, name, name_len, &ref))
  75                 return NULL;
  76         return ref;
  77 }
  78
  79 int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
  80                            struct btrfs_root *root,
  81                            const char *name, int name_len,
  82                            u64 inode_objectid, u64 ref_objectid, u64 *index)
  83 {
  84         struct btrfs_path *path;
  85         struct btrfs_key key;
  86         struct btrfs_inode_ref *ref;
  87         struct extent_buffer *leaf;
  88         unsigned long ptr;
  89         unsigned long item_start;
  90         u32 item_size;
  91         u32 sub_item_len;
  92         int ret;
  93         int del_len = name_len + sizeof(*ref);
  94
  95         key.objectid = inode_objectid;
  96         key.offset = ref_objectid;
  97         btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
  98
  99         path = btrfs_alloc_path();
 100         if (!path)
 101                 return -ENOMEM;
 102
 103         path->leave_spinning = 1;
 104
 105         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 106         if (ret > 0) {
 107                 ret = -ENOENT;
 108                 goto out;
 109         } else if (ret < 0) {
 110                 goto out;
 111         }
 112         if (!find_name_in_backref(path, name, name_len, &ref)) {
 113                 ret = -ENOENT;
 114                 goto out;
 115         }
 116         leaf = path->nodes[0];
 117         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 118
 119         if (index)
 120                 *index = btrfs_inode_ref_index(leaf, ref);
 121
 122         if (del_len == item_size) {
 123                 ret = btrfs_del_item(trans, root, path);
 124                 goto out;
 125         }
 126         ptr = (unsigned long)ref;
 127         sub_item_len = name_len + sizeof(*ref);
 128         item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 129         memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 130                               item_size - (ptr + sub_item_len - item_start));
 131         ret = btrfs_truncate_item(trans, root, path,
 132                                   item_size - sub_item_len, 1);
 133         BUG_ON(ret);
 134 out:
 135         btrfs_free_path(path);
 136         return ret;
 137 }
 138
 139 int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
 140                            struct btrfs_root *root,
 141                            const char *name, int name_len,
 142                            u64 inode_objectid, u64 ref_objectid, u64 index)
 143 {
 144         struct btrfs_path *path;
 145         struct btrfs_key key;
 146         struct btrfs_inode_ref *ref;
 147         unsigned long ptr;
 148         int ret;
 149         int ins_len = name_len + sizeof(*ref);
 150
 151         key.objectid = inode_objectid;
 152         key.offset = ref_objectid;
 153         btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
 154
 155         path = btrfs_alloc_path();
 156         if (!path)
 157                 return -ENOMEM;
 158
 159         path->leave_spinning = 1;
 160         ret = btrfs_insert_empty_item(trans, root, path, &key,
 161                                       ins_len);
 162         if (ret == -EEXIST) {
 163                 u32 old_size;
 164
 165                 if (find_name_in_backref(path, name, name_len, &ref))
 166                         goto out;
 167
 168                 old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
 169                 ret = btrfs_extend_item(trans, root, path, ins_len);
 170                 BUG_ON(ret);
 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
 192 out:
 193         btrfs_free_path(path);
 194         return ret;
 195 }
 196
 197 int 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
 212 int 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 }