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 static struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root,
  25                               struct btrfs_path *path,
  26                               const char *name, int name_len);
  27
  28 /*
  29  * insert a name into a directory, doing overflow properly if there is a hash
  30  * collision.  data_size indicates how big the item inserted should be.  On
  31  * success a struct btrfs_dir_item pointer is returned, otherwise it is
  32  * an ERR_PTR.
  33  *
  34  * The name is not copied into the dir item, you have to do that yourself.
  35  */
  36 static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle
  37                                                    *trans,
  38                                                    struct btrfs_root *root,
  39                                                    struct btrfs_path *path,
  40                                                    struct btrfs_key *cpu_key,
  41                                                    u32 data_size,
  42                                                    const char *name,
  43                                                    int name_len)
  44 {
  45         int ret;
  46         char *ptr;
  47         struct btrfs_item *item;
  48         struct extent_buffer *leaf;
  49
  50         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
  51         if (ret == -EEXIST) {
  52                 struct btrfs_dir_item *di;
  53                 di = btrfs_match_dir_item_name(root, path, name, name_len);
  54                 if (di)
  55                         return ERR_PTR(-EEXIST);
  56                 btrfs_extend_item(root, path, data_size);
  57         } else if (ret < 0)
  58                 return ERR_PTR(ret);
  59         WARN_ON(ret > 0);
  60         leaf = path->nodes[0];
  61         item = btrfs_item_nr(path->slots[0]);
  62         ptr = btrfs_item_ptr(leaf, path->slots[0], char);
  63         BUG_ON(data_size > btrfs_item_size(leaf, item));
  64         ptr += btrfs_item_size(leaf, item) - data_size;
  65         return (struct btrfs_dir_item *)ptr;
  66 }
  67
  68 /*
  69  * xattrs work a lot like directories, this inserts an xattr item
  70  * into the tree
  71  */
  72 int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
  73                             struct btrfs_root *root,
  74                             struct btrfs_path *path, u64 objectid,
  75                             const char *name, u16 name_len,
  76                             const void *data, u16 data_len)
  77 {
  78         int ret = 0;
  79         struct btrfs_dir_item *dir_item;
  80         unsigned long name_ptr, data_ptr;
  81         struct btrfs_key key, location;
  82         struct btrfs_disk_key disk_key;
  83         struct extent_buffer *leaf;
  84         u32 data_size;
  85
  86         BUG_ON(name_len + data_len > BTRFS_MAX_XATTR_SIZE(root));
  87
  88         key.objectid = objectid;
  89         btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
  90         key.offset = btrfs_name_hash(name, name_len);
  91
  92         data_size = sizeof(*dir_item) + name_len + data_len;
  93         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
  94                                         name, name_len);
  95         if (IS_ERR(dir_item))
  96                 return PTR_ERR(dir_item);
  97         memset(&location, 0, sizeof(location));
  98
  99         leaf = path->nodes[0];
 100         btrfs_cpu_key_to_disk(&disk_key, &location);
 101         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 102         btrfs_set_dir_type(leaf, dir_item, BTRFS_FT_XATTR);
 103         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 104         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 105         btrfs_set_dir_data_len(leaf, dir_item, data_len);
 106         name_ptr = (unsigned long)(dir_item + 1);
 107         data_ptr = (unsigned long)((char *)name_ptr + name_len);
 108
 109         write_extent_buffer(leaf, name, name_ptr, name_len);
 110         write_extent_buffer(leaf, data, data_ptr, data_len);
 111         btrfs_mark_buffer_dirty(path->nodes[0]);
 112
 113         return ret;
 114 }
 115
 116 /*
 117  * insert a directory item in the tree, doing all the magic for
 118  * both indexes. 'dir' indicates which objectid to insert it into,
 119  * 'location' is the key to stuff into the directory item, 'type' is the
 120  * type of the inode we're pointing to, and 'index' is the sequence number
 121  * to use for the second index (if one is created).
 122  * Will return 0 or -ENOMEM
 123  */
 124 int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
 125                           *root, const char *name, int name_len,
 126                           struct inode *dir, struct btrfs_key *location,
 127                           u8 type, u64 index)
 128 {
 129         int ret = 0;
 130         int ret2 = 0;
 131         struct btrfs_path *path;
 132         struct btrfs_dir_item *dir_item;
 133         struct extent_buffer *leaf;
 134         unsigned long name_ptr;
 135         struct btrfs_key key;
 136         struct btrfs_disk_key disk_key;
 137         u32 data_size;
 138
 139         key.objectid = btrfs_ino(dir);
 140         btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
 141         key.offset = btrfs_name_hash(name, name_len);
 142
 143         path = btrfs_alloc_path();
 144         if (!path)
 145                 return -ENOMEM;
 146         path->leave_spinning = 1;
 147
 148         btrfs_cpu_key_to_disk(&disk_key, location);
 149
 150         data_size = sizeof(*dir_item) + name_len;
 151         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
 152                                         name, name_len);
 153         if (IS_ERR(dir_item)) {
 154                 ret = PTR_ERR(dir_item);
 155                 if (ret == -EEXIST)
 156                         goto second_insert;
 157                 goto out_free;
 158         }
 159
 160         leaf = path->nodes[0];
 161         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 162         btrfs_set_dir_type(leaf, dir_item, type);
 163         btrfs_set_dir_data_len(leaf, dir_item, 0);
 164         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 165         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 166         name_ptr = (unsigned long)(dir_item + 1);
 167
 168         write_extent_buffer(leaf, name, name_ptr, name_len);
 169         btrfs_mark_buffer_dirty(leaf);
 170
 171 second_insert:
 172         /* FIXME, use some real flag for selecting the extra index */
 173         if (root == root->fs_info->tree_root) {
 174                 ret = 0;
 175                 goto out_free;
 176         }
 177         btrfs_release_path(path);
 178
 179         ret2 = btrfs_insert_delayed_dir_index(trans, root, name, name_len, dir,
 180                                               &disk_key, type, index);
 181 out_free:
 182         btrfs_free_path(path);
 183         if (ret)
 184                 return ret;
 185         if (ret2)
 186                 return ret2;
 187         return 0;
 188 }
 189
 190 /*
 191  * lookup a directory item based on name.  'dir' is the objectid
 192  * we're searching in, and 'mod' tells us if you plan on deleting the
 193  * item (use mod < 0) or changing the options (use mod > 0)
 194  */
 195 struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
 196                                              struct btrfs_root *root,
 197                                              struct btrfs_path *path, u64 dir,
 198                                              const char *name, int name_len,
 199                                              int mod)
 200 {
 201         int ret;
 202         struct btrfs_key key;
 203         int ins_len = mod < 0 ? -1 : 0;
 204         int cow = mod != 0;
 205
 206         key.objectid = dir;
 207         btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
 208
 209         key.offset = btrfs_name_hash(name, name_len);
 210
 211         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 212         if (ret < 0)
 213                 return ERR_PTR(ret);
 214         if (ret > 0)
 215                 return NULL;
 216
 217         return btrfs_match_dir_item_name(root, path, name, name_len);
 218 }
 219
 220 int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
 221                                    const char *name, int name_len)
 222 {
 223         int ret;
 224         struct btrfs_key key;
 225         struct btrfs_dir_item *di;
 226         int data_size;
 227         struct extent_buffer *leaf;
 228         int slot;
 229         struct btrfs_path *path;
 230
 231
 232         path = btrfs_alloc_path();
 233         if (!path)
 234                 return -ENOMEM;
 235
 236         key.objectid = dir;
 237         btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
 238         key.offset = btrfs_name_hash(name, name_len);
 239
 240         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 241
 242         /* return back any errors */
 243         if (ret < 0)
 244                 goto out;
 245
 246         /* nothing found, we're safe */
 247         if (ret > 0) {
 248                 ret = 0;
 249                 goto out;
 250         }
 251
 252         /* we found an item, look for our name in the item */
 253         di = btrfs_match_dir_item_name(root, path, name, name_len);
 254         if (di) {
 255                 /* our exact name was found */
 256                 ret = -EEXIST;
 257                 goto out;
 258         }
 259
 260         /*
 261          * see if there is room in the item to insert this
 262          * name
 263          */
 264         data_size = sizeof(*di) + name_len + sizeof(struct btrfs_item);
 265         leaf = path->nodes[0];
 266         slot = path->slots[0];
 267         if (data_size + btrfs_item_size_nr(leaf, slot) +
 268             sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root)) {
 269                 ret = -EOVERFLOW;
 270         } else {
 271                 /* plenty of insertion room */
 272                 ret = 0;
 273         }
 274 out:
 275         btrfs_free_path(path);
 276         return ret;
 277 }
 278
 279 /*
 280  * lookup a directory item based on index.  'dir' is the objectid
 281  * we're searching in, and 'mod' tells us if you plan on deleting the
 282  * item (use mod < 0) or changing the options (use mod > 0)
 283  *
 284  * The name is used to make sure the index really points to the name you were
 285  * looking for.
 286  */
 287 struct btrfs_dir_item *
 288 btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
 289                             struct btrfs_root *root,
 290                             struct btrfs_path *path, u64 dir,
 291                             u64 objectid, const char *name, int name_len,
 292                             int mod)
 293 {
 294         int ret;
 295         struct btrfs_key key;
 296         int ins_len = mod < 0 ? -1 : 0;
 297         int cow = mod != 0;
 298
 299         key.objectid = dir;
 300         btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
 301         key.offset = objectid;
 302
 303         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 304         if (ret < 0)
 305                 return ERR_PTR(ret);
 306         if (ret > 0)
 307                 return ERR_PTR(-ENOENT);
 308         return btrfs_match_dir_item_name(root, path, name, name_len);
 309 }
 310
 311 struct btrfs_dir_item *
 312 btrfs_search_dir_index_item(struct btrfs_root *root,
 313                             struct btrfs_path *path, u64 dirid,
 314                             const char *name, int name_len)
 315 {
 316         struct extent_buffer *leaf;
 317         struct btrfs_dir_item *di;
 318         struct btrfs_key key;
 319         u32 nritems;
 320         int ret;
 321
 322         key.objectid = dirid;
 323         key.type = BTRFS_DIR_INDEX_KEY;
 324         key.offset = 0;
 325
 326         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 327         if (ret < 0)
 328                 return ERR_PTR(ret);
 329
 330         leaf = path->nodes[0];
 331         nritems = btrfs_header_nritems(leaf);
 332
 333         while (1) {
 334                 if (path->slots[0] >= nritems) {
 335                         ret = btrfs_next_leaf(root, path);
 336                         if (ret < 0)
 337                                 return ERR_PTR(ret);
 338                         if (ret > 0)
 339                                 break;
 340                         leaf = path->nodes[0];
 341                         nritems = btrfs_header_nritems(leaf);
 342                         continue;
 343                 }
 344
 345                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 346                 if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
 347                         break;
 348
 349                 di = btrfs_match_dir_item_name(root, path, name, name_len);
 350                 if (di)
 351                         return di;
 352
 353                 path->slots[0]++;
 354         }
 355         return NULL;
 356 }
 357
 358 struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
 359                                           struct btrfs_root *root,
 360                                           struct btrfs_path *path, u64 dir,
 361                                           const char *name, u16 name_len,
 362                                           int mod)
 363 {
 364         int ret;
 365         struct btrfs_key key;
 366         int ins_len = mod < 0 ? -1 : 0;
 367         int cow = mod != 0;
 368
 369         key.objectid = dir;
 370         btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
 371         key.offset = btrfs_name_hash(name, name_len);
 372         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 373         if (ret < 0)
 374                 return ERR_PTR(ret);
 375         if (ret > 0)
 376                 return NULL;
 377
 378         return btrfs_match_dir_item_name(root, path, name, name_len);
 379 }
 380
 381 /*
 382  * helper function to look at the directory item pointed to by 'path'
 383  * this walks through all the entries in a dir item and finds one
 384  * for a specific name.
 385  */
 386 static struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root,
 387                               struct btrfs_path *path,
 388                               const char *name, int name_len)
 389 {
 390         struct btrfs_dir_item *dir_item;
 391         unsigned long name_ptr;
 392         u32 total_len;
 393         u32 cur = 0;
 394         u32 this_len;
 395         struct extent_buffer *leaf;
 396
 397         leaf = path->nodes[0];
 398         dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
 399         if (verify_dir_item(root, leaf, dir_item))
 400                 return NULL;
 401
 402         total_len = btrfs_item_size_nr(leaf, path->slots[0]);
 403         while (cur < total_len) {
 404                 this_len = sizeof(*dir_item) +
 405                         btrfs_dir_name_len(leaf, dir_item) +
 406                         btrfs_dir_data_len(leaf, dir_item);
 407                 name_ptr = (unsigned long)(dir_item + 1);
 408
 409                 if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
 410                     memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
 411                         return dir_item;
 412
 413                 cur += this_len;
 414                 dir_item = (struct btrfs_dir_item *)((char *)dir_item +
 415                                                      this_len);
 416         }
 417         return NULL;
 418 }
 419
 420 /*
 421  * given a pointer into a directory item, delete it.  This
 422  * handles items that have more than one entry in them.
 423  */
 424 int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 425                               struct btrfs_root *root,
 426                               struct btrfs_path *path,
 427                               struct btrfs_dir_item *di)
 428 {
 429
 430         struct extent_buffer *leaf;
 431         u32 sub_item_len;
 432         u32 item_len;
 433         int ret = 0;
 434
 435         leaf = path->nodes[0];
 436         sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
 437                 btrfs_dir_data_len(leaf, di);
 438         item_len = btrfs_item_size_nr(leaf, path->slots[0]);
 439         if (sub_item_len == item_len) {
 440                 ret = btrfs_del_item(trans, root, path);
 441         } else {
 442                 /* MARKER */
 443                 unsigned long ptr = (unsigned long)di;
 444                 unsigned long start;
 445
 446                 start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 447                 memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 448                         item_len - (ptr + sub_item_len - start));
 449                 btrfs_truncate_item(root, path, item_len - sub_item_len, 1);
 450         }
 451         return ret;
 452 }
 453
 454 int verify_dir_item(struct btrfs_root *root,
 455                     struct extent_buffer *leaf,
 456                     struct btrfs_dir_item *dir_item)
 457 {
 458         u16 namelen = BTRFS_NAME_LEN;
 459         u8 type = btrfs_dir_type(leaf, dir_item);
 460
 461         if (type >= BTRFS_FT_MAX) {
 462                 printk(KERN_CRIT "btrfs: invalid dir item type: %d\n",
 463                        (int)type);
 464                 return 1;
 465         }
 466
 467         if (type == BTRFS_FT_XATTR)
 468                 namelen = XATTR_NAME_MAX;
 469
 470         if (btrfs_dir_name_len(leaf, dir_item) > namelen) {
 471                 printk(KERN_CRIT "btrfs: invalid dir item name len: %u\n",
 472                        (unsigned)btrfs_dir_data_len(leaf, dir_item));
 473                 return 1;
 474         }
 475
 476         /* BTRFS_MAX_XATTR_SIZE is the same for all dir items */
 477         if ((btrfs_dir_data_len(leaf, dir_item) +
 478              btrfs_dir_name_len(leaf, dir_item)) > BTRFS_MAX_XATTR_SIZE(root)) {
 479                 printk(KERN_CRIT "btrfs: invalid dir item name + data len: %u + %u\n",
 480                        (unsigned)btrfs_dir_name_len(leaf, dir_item),
 481                        (unsigned)btrfs_dir_data_len(leaf, dir_item));
 482                 return 1;
 483         }
 484
 485         return 0;
 486 }