release/src-rt-6.x.4708/linux/linux-2.6.36/fs/btrfs/dir-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 "hash.h"
  22 #include "transaction.h"
  23
  24 /*
  25  * insert a name into a directory, doing overflow properly if there is a hash
  26  * collision.  data_size indicates how big the item inserted should be.  On
  27  * success a struct btrfs_dir_item pointer is returned, otherwise it is
  28  * an ERR_PTR.
  29  *
  30  * The name is not copied into the dir item, you have to do that yourself.
  31  */
  32 static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle
  33                                                    *trans,
  34                                                    struct btrfs_root *root,
  35                                                    struct btrfs_path *path,
  36                                                    struct btrfs_key *cpu_key,
  37                                                    u32 data_size,
  38                                                    const char *name,
  39                                                    int name_len)
  40 {
  41         int ret;
  42         char *ptr;
  43         struct btrfs_item *item;
  44         struct extent_buffer *leaf;
  45
  46         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
  47         if (ret == -EEXIST) {
  48                 struct btrfs_dir_item *di;
  49                 di = btrfs_match_dir_item_name(root, path, name, name_len);
  50                 if (di)
  51                         return ERR_PTR(-EEXIST);
  52                 ret = btrfs_extend_item(trans, root, path, data_size);
  53                 WARN_ON(ret > 0);
  54         }
  55         if (ret < 0)
  56                 return ERR_PTR(ret);
  57         WARN_ON(ret > 0);
  58         leaf = path->nodes[0];
  59         item = btrfs_item_nr(leaf, path->slots[0]);
  60         ptr = btrfs_item_ptr(leaf, path->slots[0], char);
  61         BUG_ON(data_size > btrfs_item_size(leaf, item));
  62         ptr += btrfs_item_size(leaf, item) - data_size;
  63         return (struct btrfs_dir_item *)ptr;
  64 }
  65
  66 /*
  67  * xattrs work a lot like directories, this inserts an xattr item
  68  * into the tree
  69  */
  70 int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
  71                             struct btrfs_root *root,
  72                             struct btrfs_path *path, u64 objectid,
  73                             const char *name, u16 name_len,
  74                             const void *data, u16 data_len)
  75 {
  76         int ret = 0;
  77         struct btrfs_dir_item *dir_item;
  78         unsigned long name_ptr, data_ptr;
  79         struct btrfs_key key, location;
  80         struct btrfs_disk_key disk_key;
  81         struct extent_buffer *leaf;
  82         u32 data_size;
  83
  84         BUG_ON(name_len + data_len > BTRFS_MAX_XATTR_SIZE(root));
  85
  86         key.objectid = objectid;
  87         btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
  88         key.offset = btrfs_name_hash(name, name_len);
  89
  90         data_size = sizeof(*dir_item) + name_len + data_len;
  91         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
  92                                         name, name_len);
  93         BUG_ON(IS_ERR(dir_item));
  94         memset(&location, 0, sizeof(location));
  95
  96         leaf = path->nodes[0];
  97         btrfs_cpu_key_to_disk(&disk_key, &location);
  98         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
  99         btrfs_set_dir_type(leaf, dir_item, BTRFS_FT_XATTR);
 100         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 101         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 102         btrfs_set_dir_data_len(leaf, dir_item, data_len);
 103         name_ptr = (unsigned long)(dir_item + 1);
 104         data_ptr = (unsigned long)((char *)name_ptr + name_len);
 105
 106         write_extent_buffer(leaf, name, name_ptr, name_len);
 107         write_extent_buffer(leaf, data, data_ptr, data_len);
 108         btrfs_mark_buffer_dirty(path->nodes[0]);
 109
 110         return ret;
 111 }
 112
 113 /*
 114  * insert a directory item in the tree, doing all the magic for
 115  * both indexes. 'dir' indicates which objectid to insert it into,
 116  * 'location' is the key to stuff into the directory item, 'type' is the
 117  * type of the inode we're pointing to, and 'index' is the sequence number
 118  * to use for the second index (if one is created).
 119  */
 120 int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
 121                           *root, const char *name, int name_len, u64 dir,
 122                           struct btrfs_key *location, u8 type, u64 index)
 123 {
 124         int ret = 0;
 125         int ret2 = 0;
 126         struct btrfs_path *path;
 127         struct btrfs_dir_item *dir_item;
 128         struct extent_buffer *leaf;
 129         unsigned long name_ptr;
 130         struct btrfs_key key;
 131         struct btrfs_disk_key disk_key;
 132         u32 data_size;
 133
 134         key.objectid = dir;
 135         btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
 136         key.offset = btrfs_name_hash(name, name_len);
 137
 138         path = btrfs_alloc_path();
 139         path->leave_spinning = 1;
 140
 141         data_size = sizeof(*dir_item) + name_len;
 142         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
 143                                         name, name_len);
 144         if (IS_ERR(dir_item)) {
 145                 ret = PTR_ERR(dir_item);
 146                 if (ret == -EEXIST)
 147                         goto second_insert;
 148                 goto out;
 149         }
 150
 151         leaf = path->nodes[0];
 152         btrfs_cpu_key_to_disk(&disk_key, location);
 153         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 154         btrfs_set_dir_type(leaf, dir_item, type);
 155         btrfs_set_dir_data_len(leaf, dir_item, 0);
 156         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 157         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 158         name_ptr = (unsigned long)(dir_item + 1);
 159
 160         write_extent_buffer(leaf, name, name_ptr, name_len);
 161         btrfs_mark_buffer_dirty(leaf);
 162
 163 second_insert:
 164         if (root == root->fs_info->tree_root) {
 165                 ret = 0;
 166                 goto out;
 167         }
 168         btrfs_release_path(root, path);
 169
 170         btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
 171         key.offset = index;
 172         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
 173                                         name, name_len);
 174         if (IS_ERR(dir_item)) {
 175                 ret2 = PTR_ERR(dir_item);
 176                 goto out;
 177         }
 178         leaf = path->nodes[0];
 179         btrfs_cpu_key_to_disk(&disk_key, location);
 180         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 181         btrfs_set_dir_type(leaf, dir_item, type);
 182         btrfs_set_dir_data_len(leaf, dir_item, 0);
 183         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 184         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 185         name_ptr = (unsigned long)(dir_item + 1);
 186         write_extent_buffer(leaf, name, name_ptr, name_len);
 187         btrfs_mark_buffer_dirty(leaf);
 188 out:
 189         btrfs_free_path(path);
 190         if (ret)
 191                 return ret;
 192         if (ret2)
 193                 return ret2;
 194         return 0;
 195 }
 196
 197 /*
 198  * lookup a directory item based on name.  'dir' is the objectid
 199  * we're searching in, and 'mod' tells us if you plan on deleting the
 200  * item (use mod < 0) or changing the options (use mod > 0)
 201  */
 202 struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
 203                                              struct btrfs_root *root,
 204                                              struct btrfs_path *path, u64 dir,
 205                                              const char *name, int name_len,
 206                                              int mod)
 207 {
 208         int ret;
 209         struct btrfs_key key;
 210         int ins_len = mod < 0 ? -1 : 0;
 211         int cow = mod != 0;
 212         struct btrfs_key found_key;
 213         struct extent_buffer *leaf;
 214
 215         key.objectid = dir;
 216         btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
 217
 218         key.offset = btrfs_name_hash(name, name_len);
 219
 220         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 221         if (ret < 0)
 222                 return ERR_PTR(ret);
 223         if (ret > 0) {
 224                 if (path->slots[0] == 0)
 225                         return NULL;
 226                 path->slots[0]--;
 227         }
 228
 229         leaf = path->nodes[0];
 230         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 231
 232         if (found_key.objectid != dir ||
 233             btrfs_key_type(&found_key) != BTRFS_DIR_ITEM_KEY ||
 234             found_key.offset != key.offset)
 235                 return NULL;
 236
 237         return btrfs_match_dir_item_name(root, path, name, name_len);
 238 }
 239
 240 /*
 241  * lookup a directory item based on index.  'dir' is the objectid
 242  * we're searching in, and 'mod' tells us if you plan on deleting the
 243  * item (use mod < 0) or changing the options (use mod > 0)
 244  *
 245  * The name is used to make sure the index really points to the name you were
 246  * looking for.
 247  */
 248 struct btrfs_dir_item *
 249 btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
 250                             struct btrfs_root *root,
 251                             struct btrfs_path *path, u64 dir,
 252                             u64 objectid, const char *name, int name_len,
 253                             int mod)
 254 {
 255         int ret;
 256         struct btrfs_key key;
 257         int ins_len = mod < 0 ? -1 : 0;
 258         int cow = mod != 0;
 259
 260         key.objectid = dir;
 261         btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
 262         key.offset = objectid;
 263
 264         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 265         if (ret < 0)
 266                 return ERR_PTR(ret);
 267         if (ret > 0)
 268                 return ERR_PTR(-ENOENT);
 269         return btrfs_match_dir_item_name(root, path, name, name_len);
 270 }
 271
 272 struct btrfs_dir_item *
 273 btrfs_search_dir_index_item(struct btrfs_root *root,
 274                             struct btrfs_path *path, u64 dirid,
 275                             const char *name, int name_len)
 276 {
 277         struct extent_buffer *leaf;
 278         struct btrfs_dir_item *di;
 279         struct btrfs_key key;
 280         u32 nritems;
 281         int ret;
 282
 283         key.objectid = dirid;
 284         key.type = BTRFS_DIR_INDEX_KEY;
 285         key.offset = 0;
 286
 287         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 288         if (ret < 0)
 289                 return ERR_PTR(ret);
 290
 291         leaf = path->nodes[0];
 292         nritems = btrfs_header_nritems(leaf);
 293
 294         while (1) {
 295                 if (path->slots[0] >= nritems) {
 296                         ret = btrfs_next_leaf(root, path);
 297                         if (ret < 0)
 298                                 return ERR_PTR(ret);
 299                         if (ret > 0)
 300                                 break;
 301                         leaf = path->nodes[0];
 302                         nritems = btrfs_header_nritems(leaf);
 303                         continue;
 304                 }
 305
 306                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 307                 if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
 308                         break;
 309
 310                 di = btrfs_match_dir_item_name(root, path, name, name_len);
 311                 if (di)
 312                         return di;
 313
 314                 path->slots[0]++;
 315         }
 316         return NULL;
 317 }
 318
 319 struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
 320                                           struct btrfs_root *root,
 321                                           struct btrfs_path *path, u64 dir,
 322                                           const char *name, u16 name_len,
 323                                           int mod)
 324 {
 325         int ret;
 326         struct btrfs_key key;
 327         int ins_len = mod < 0 ? -1 : 0;
 328         int cow = mod != 0;
 329         struct btrfs_key found_key;
 330         struct extent_buffer *leaf;
 331
 332         key.objectid = dir;
 333         btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
 334         key.offset = btrfs_name_hash(name, name_len);
 335         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 336         if (ret < 0)
 337                 return ERR_PTR(ret);
 338         if (ret > 0) {
 339                 if (path->slots[0] == 0)
 340                         return NULL;
 341                 path->slots[0]--;
 342         }
 343
 344         leaf = path->nodes[0];
 345         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 346
 347         if (found_key.objectid != dir ||
 348             btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY ||
 349             found_key.offset != key.offset)
 350                 return NULL;
 351
 352         return btrfs_match_dir_item_name(root, path, name, name_len);
 353 }
 354
 355 /*
 356  * helper function to look at the directory item pointed to by 'path'
 357  * this walks through all the entries in a dir item and finds one
 358  * for a specific name.
 359  */
 360 struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root,
 361                               struct btrfs_path *path,
 362                               const char *name, int name_len)
 363 {
 364         struct btrfs_dir_item *dir_item;
 365         unsigned long name_ptr;
 366         u32 total_len;
 367         u32 cur = 0;
 368         u32 this_len;
 369         struct extent_buffer *leaf;
 370
 371         leaf = path->nodes[0];
 372         dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
 373         total_len = btrfs_item_size_nr(leaf, path->slots[0]);
 374         while (cur < total_len) {
 375                 this_len = sizeof(*dir_item) +
 376                         btrfs_dir_name_len(leaf, dir_item) +
 377                         btrfs_dir_data_len(leaf, dir_item);
 378                 name_ptr = (unsigned long)(dir_item + 1);
 379
 380                 if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
 381                     memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
 382                         return dir_item;
 383
 384                 cur += this_len;
 385                 dir_item = (struct btrfs_dir_item *)((char *)dir_item +
 386                                                      this_len);
 387         }
 388         return NULL;
 389 }
 390
 391 /*
 392  * given a pointer into a directory item, delete it.  This
 393  * handles items that have more than one entry in them.
 394  */
 395 int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 396                               struct btrfs_root *root,
 397                               struct btrfs_path *path,
 398                               struct btrfs_dir_item *di)
 399 {
 400
 401         struct extent_buffer *leaf;
 402         u32 sub_item_len;
 403         u32 item_len;
 404         int ret = 0;
 405
 406         leaf = path->nodes[0];
 407         sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
 408                 btrfs_dir_data_len(leaf, di);
 409         item_len = btrfs_item_size_nr(leaf, path->slots[0]);
 410         if (sub_item_len == item_len) {
 411                 ret = btrfs_del_item(trans, root, path);
 412         } else {
 413                 /* MARKER */
 414                 unsigned long ptr = (unsigned long)di;
 415                 unsigned long start;
 416
 417                 start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 418                 memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 419                         item_len - (ptr + sub_item_len - start));
 420                 ret = btrfs_truncate_item(trans, root, path,
 421                                           item_len - sub_item_len, 1);
 422         }
 423         return 0;
 424 }