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