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 #include "crc32c.h"
  23
  24 static 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
  53 int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
  54                            struct btrfs_root *root,
  55                            const char *name, int name_len,
  56                            u64 inode_objectid, u64 ref_objectid, u64 index)
  57 {
  58         struct btrfs_path *path;
  59         struct btrfs_key key;
  60         struct btrfs_inode_ref *ref;
  61         unsigned long ptr;
  62         int ret;
  63         int ins_len = name_len + sizeof(*ref);
  64
  65         key.objectid = inode_objectid;
  66         key.offset = ref_objectid;
  67         btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
  68
  69         path = btrfs_alloc_path();
  70         if (!path)
  71                 return -ENOMEM;
  72
  73         ret = btrfs_insert_empty_item(trans, root, path, &key,
  74                                       ins_len);
  75         if (ret == -EEXIST) {
  76                 u32 old_size;
  77
  78                 if (find_name_in_backref(path, name, name_len, &ref))
  79                         goto out;
  80
  81                 old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
  82                 ret = btrfs_extend_item(trans, root, path, ins_len);
  83                 BUG_ON(ret);
  84                 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
  85                                      struct btrfs_inode_ref);
  86                 ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
  87                 btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
  88                 btrfs_set_inode_ref_index(path->nodes[0], ref, index);
  89                 ptr = (unsigned long)(ref + 1);
  90                 ret = 0;
  91         } else if (ret < 0) {
  92                 goto out;
  93         } else {
  94                 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
  95                                      struct btrfs_inode_ref);
  96                 btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
  97                 btrfs_set_inode_ref_index(path->nodes[0], ref, index);
  98                 ptr = (unsigned long)(ref + 1);
  99         }
 100         write_extent_buffer(path->nodes[0], name, ptr, name_len);
 101         btrfs_mark_buffer_dirty(path->nodes[0]);
 102
 103 out:
 104         btrfs_free_path(path);
 105         return ret;
 106 }
 107
 108 int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
 109                        *root, struct btrfs_path *path,
 110                        struct btrfs_key *location, int mod)
 111 {
 112         int ins_len = mod < 0 ? -1 : 0;
 113         int cow = mod != 0;
 114         int ret;
 115         int slot;
 116         struct extent_buffer *leaf;
 117         struct btrfs_key found_key;
 118
 119         ret = btrfs_search_slot(trans, root, location, path, ins_len, cow);
 120         if (ret > 0 && btrfs_key_type(location) == BTRFS_ROOT_ITEM_KEY &&
 121             location->offset == (u64)-1 && path->slots[0] != 0) {
 122                 slot = path->slots[0] - 1;
 123                 leaf = path->nodes[0];
 124                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 125                 if (found_key.objectid == location->objectid &&
 126                     btrfs_key_type(&found_key) == btrfs_key_type(location)) {
 127                         path->slots[0]--;
 128                         return 0;
 129                 }
 130         }
 131         return ret;
 132 }
 133
 134 int btrfs_insert_inode(struct btrfs_trans_handle *trans, struct btrfs_root
 135                        *root, u64 objectid, struct btrfs_inode_item
 136                        *inode_item)
 137 {
 138         int ret;
 139         struct btrfs_key key;
 140
 141         key.objectid = objectid;
 142         key.type = BTRFS_INODE_ITEM_KEY;
 143         key.offset = 0;
 144
 145         ret = btrfs_insert_item(trans, root, &key, inode_item,
 146                                 sizeof(*inode_item));
 147         return ret;
 148 }
 149
 150 static inline u64 btrfs_extref_hash(u64 parent_ino, const char *name,
 151                                     int namelen)
 152 {
 153         return (u64)btrfs_crc32c(parent_ino, name, namelen);
 154 }
 155
 156 static int btrfs_find_name_in_ext_backref(struct btrfs_path *path,
 157                 u64 parent_ino, const char *name, int namelen,
 158                 struct btrfs_inode_extref **extref_ret)
 159 {
 160         struct extent_buffer *node;
 161         struct btrfs_inode_extref *extref;
 162         unsigned long ptr;
 163         unsigned long name_ptr;
 164         u32 item_size;
 165         u32 cur_offset = 0;
 166         int ref_name_len;
 167         int slot;
 168
 169         node = path->nodes[0];
 170         slot = path->slots[0];
 171         item_size = btrfs_item_size_nr(node, slot);
 172         ptr = btrfs_item_ptr_offset(node, slot);
 173
 174         /*
 175          * Search all extended backrefs in this item. We're only looking
 176          * through any collisions so most of the time this is just going to
 177          * compare against one buffer. If all is well, we'll return success and
 178          * the inode ref object.
 179          */
 180         while (cur_offset < item_size) {
 181                 extref = (struct btrfs_inode_extref *) (ptr + cur_offset);
 182                 name_ptr = (unsigned long)(&extref->name);
 183                 ref_name_len = btrfs_inode_extref_name_len(node, extref);
 184
 185                 if (ref_name_len == namelen &&
 186                     btrfs_inode_extref_parent(node, extref) == parent_ino &&
 187                     (memcmp_extent_buffer(node, name, name_ptr, namelen) == 0))
 188                 {
 189                         if (extref_ret)
 190                                 *extref_ret = extref;
 191                         return 1;
 192                 }
 193
 194                 cur_offset += ref_name_len + sizeof(*extref);
 195         }
 196
 197         return 0;
 198 }
 199
 200 struct btrfs_inode_extref *btrfs_lookup_inode_extref(struct btrfs_trans_handle
 201                 *trans, struct btrfs_path *path, struct btrfs_root *root,
 202                 u64 ino, u64 parent_ino, u64 index, const char *name,
 203                 int namelen, int ins_len)
 204 {
 205         struct btrfs_key key;
 206         struct btrfs_inode_extref *extref;
 207         int ret = 0;
 208
 209         key.objectid = ino;
 210         key.type = BTRFS_INODE_EXTREF_KEY;
 211         key.offset = btrfs_extref_hash(parent_ino, name, namelen);
 212
 213         ret = btrfs_search_slot(trans, root, &key, path, ins_len,
 214                         ins_len ? 1 : 0);
 215         if (ret < 0)
 216                 return ERR_PTR(ret);
 217         if (ret > 0)
 218                 return NULL;
 219         if (!btrfs_find_name_in_ext_backref(path, parent_ino, name,
 220                                             namelen, &extref))
 221                 return NULL;
 222
 223         return extref;
 224 }
 225
 226 int btrfs_del_inode_extref(struct btrfs_trans_handle *trans,
 227                            struct btrfs_root *root,
 228                            const char *name, int name_len,
 229                            u64 inode_objectid, u64 ref_objectid,
 230                            u64 *index)
 231 {
 232         struct btrfs_path *path;
 233         struct btrfs_key key;
 234         struct btrfs_inode_extref *extref;
 235         struct extent_buffer *leaf;
 236         int ret;
 237         int del_len = name_len + sizeof(*extref);
 238         unsigned long ptr;
 239         unsigned long item_start;
 240         u32 item_size;
 241
 242         key.objectid = inode_objectid;
 243         key.type = BTRFS_INODE_EXTREF_KEY;
 244         key.offset = btrfs_extref_hash(ref_objectid, name, name_len);
 245
 246         path = btrfs_alloc_path();
 247         if (!path)
 248                 return -ENOMEM;
 249
 250         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 251         if (ret > 0)
 252                 ret = -ENOENT;
 253         if (ret < 0)
 254                 goto out;
 255
 256         /*
 257          * Sanity check - did we find the right item for this name?  This
 258          * should always succeed so error here will make the FS readonly.
 259          */
 260         if (!btrfs_find_name_in_ext_backref(path, ref_objectid,
 261                                             name, name_len, &extref)) {
 262                 ret = -ENOENT;
 263                 goto out;
 264         }
 265
 266         leaf = path->nodes[0];
 267         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 268         if (index)
 269                 *index = btrfs_inode_extref_index(leaf, extref);
 270
 271         if (del_len == item_size) {
 272                 /*
 273                  * Common case only one ref in the item, remove the whole item.
 274                  */
 275                 ret = btrfs_del_item(trans, root, path);
 276                 goto out;
 277         }
 278
 279         ptr = (unsigned long)extref;
 280         item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 281
 282         memmove_extent_buffer(leaf, ptr, ptr + del_len,
 283                               item_size - (ptr + del_len - item_start));
 284
 285         btrfs_truncate_item(trans, root, path, item_size - del_len, 1);
 286
 287 out:
 288         btrfs_free_path(path);
 289
 290         return ret;
 291 }
 292
 293 /*
 294  * btrfs_insert_inode_extref() - Inserts an extended inode ref into a tree.
 295  *
 296  * The caller must have checked against BTRFS_LINK_MAX already.
 297  */
 298 int btrfs_insert_inode_extref(struct btrfs_trans_handle *trans,
 299                               struct btrfs_root *root,
 300                               const char *name, int name_len,
 301                               u64 inode_objectid, u64 ref_objectid, u64 index)
 302 {
 303         struct btrfs_inode_extref *extref;
 304         int ret;
 305         int ins_len = name_len + sizeof(*extref);
 306         unsigned long ptr;
 307         struct btrfs_path *path;
 308         struct btrfs_key key;
 309         struct extent_buffer *leaf;
 310         struct btrfs_item *item;
 311
 312         key.objectid = inode_objectid;
 313         key.type = BTRFS_INODE_EXTREF_KEY;
 314         key.offset = btrfs_extref_hash(ref_objectid, name, name_len);
 315
 316         path = btrfs_alloc_path();
 317         if (!path)
 318                 return -ENOMEM;
 319
 320         ret = btrfs_insert_empty_item(trans, root, path, &key,
 321                                       ins_len);
 322         if (ret == -EEXIST) {
 323                 if (btrfs_find_name_in_ext_backref(path, ref_objectid,
 324                                                    name, name_len, NULL))
 325                         goto out;
 326
 327                 btrfs_extend_item(trans, root, path, ins_len);
 328                 ret = 0;
 329         }
 330
 331         if (ret < 0)
 332                 goto out;
 333
 334         leaf = path->nodes[0];
 335         item = btrfs_item_nr(path->slots[0]);
 336         ptr = (unsigned long)btrfs_item_ptr(leaf, path->slots[0], char);
 337         ptr += btrfs_item_size(leaf, item) - ins_len;
 338         extref = (struct btrfs_inode_extref *)ptr;
 339
 340         btrfs_set_inode_extref_name_len(path->nodes[0], extref, name_len);
 341         btrfs_set_inode_extref_index(path->nodes[0], extref, index);
 342         btrfs_set_inode_extref_parent(path->nodes[0], extref, ref_objectid);
 343
 344         ptr = (unsigned long)&extref->name;
 345         write_extent_buffer(path->nodes[0], name, ptr, name_len);
 346         btrfs_mark_buffer_dirty(path->nodes[0]);
 347
 348 out:
 349         btrfs_free_path(path);
 350
 351         return ret;
 352 }