fs/btrfs/dir-item.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include "ctree.h"
   7 #include "disk-io.h"
   8 #include "transaction.h"
   9
  10 /*
  11  * insert a name into a directory, doing overflow properly if there is a hash
  12  * collision.  data_size indicates how big the item inserted should be.  On
  13  * success a struct btrfs_dir_item pointer is returned, otherwise it is
  14  * an ERR_PTR.
  15  *
  16  * The name is not copied into the dir item, you have to do that yourself.
  17  */
  18 static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle
  19                                                    *trans,
  20                                                    struct btrfs_root *root,
  21                                                    struct btrfs_path *path,
  22                                                    struct btrfs_key *cpu_key,
  23                                                    u32 data_size,
  24                                                    const char *name,
  25                                                    int name_len)
  26 {
  27         struct btrfs_fs_info *fs_info = root->fs_info;
  28         int ret;
  29         char *ptr;
  30         struct btrfs_item *item;
  31         struct extent_buffer *leaf;
  32
  33         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
  34         if (ret == -EEXIST) {
  35                 struct btrfs_dir_item *di;
  36                 di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
  37                 if (di)
  38                         return ERR_PTR(-EEXIST);
  39                 btrfs_extend_item(path, data_size);
  40         } else if (ret < 0)
  41                 return ERR_PTR(ret);
  42         WARN_ON(ret > 0);
  43         leaf = path->nodes[0];
  44         item = btrfs_item_nr(path->slots[0]);
  45         ptr = btrfs_item_ptr(leaf, path->slots[0], char);
  46         BUG_ON(data_size > btrfs_item_size(leaf, item));
  47         ptr += btrfs_item_size(leaf, item) - data_size;
  48         return (struct btrfs_dir_item *)ptr;
  49 }
  50
  51 /*
  52  * xattrs work a lot like directories, this inserts an xattr item
  53  * into the tree
  54  */
  55 int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
  56                             struct btrfs_root *root,
  57                             struct btrfs_path *path, u64 objectid,
  58                             const char *name, u16 name_len,
  59                             const void *data, u16 data_len)
  60 {
  61         int ret = 0;
  62         struct btrfs_dir_item *dir_item;
  63         unsigned long name_ptr, data_ptr;
  64         struct btrfs_key key, location;
  65         struct btrfs_disk_key disk_key;
  66         struct extent_buffer *leaf;
  67         u32 data_size;
  68
  69         if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root->fs_info))
  70                 return -ENOSPC;
  71
  72         key.objectid = objectid;
  73         key.type = BTRFS_XATTR_ITEM_KEY;
  74         key.offset = btrfs_name_hash(name, name_len);
  75
  76         data_size = sizeof(*dir_item) + name_len + data_len;
  77         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
  78                                         name, name_len);
  79         if (IS_ERR(dir_item))
  80                 return PTR_ERR(dir_item);
  81         memset(&location, 0, sizeof(location));
  82
  83         leaf = path->nodes[0];
  84         btrfs_cpu_key_to_disk(&disk_key, &location);
  85         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
  86         btrfs_set_dir_type(leaf, dir_item, BTRFS_FT_XATTR);
  87         btrfs_set_dir_name_len(leaf, dir_item, name_len);
  88         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
  89         btrfs_set_dir_data_len(leaf, dir_item, data_len);
  90         name_ptr = (unsigned long)(dir_item + 1);
  91         data_ptr = (unsigned long)((char *)name_ptr + name_len);
  92
  93         write_extent_buffer(leaf, name, name_ptr, name_len);
  94         write_extent_buffer(leaf, data, data_ptr, data_len);
  95         btrfs_mark_buffer_dirty(path->nodes[0]);
  96
  97         return ret;
  98 }
  99
 100 /*
 101  * insert a directory item in the tree, doing all the magic for
 102  * both indexes. 'dir' indicates which objectid to insert it into,
 103  * 'location' is the key to stuff into the directory item, 'type' is the
 104  * type of the inode we're pointing to, and 'index' is the sequence number
 105  * to use for the second index (if one is created).
 106  * Will return 0 or -ENOMEM
 107  */
 108 int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, const char *name,
 109                           int name_len, struct btrfs_inode *dir,
 110                           struct btrfs_key *location, u8 type, u64 index)
 111 {
 112         int ret = 0;
 113         int ret2 = 0;
 114         struct btrfs_root *root = dir->root;
 115         struct btrfs_path *path;
 116         struct btrfs_dir_item *dir_item;
 117         struct extent_buffer *leaf;
 118         unsigned long name_ptr;
 119         struct btrfs_key key;
 120         struct btrfs_disk_key disk_key;
 121         u32 data_size;
 122
 123         key.objectid = btrfs_ino(dir);
 124         key.type = BTRFS_DIR_ITEM_KEY;
 125         key.offset = btrfs_name_hash(name, name_len);
 126
 127         path = btrfs_alloc_path();
 128         if (!path)
 129                 return -ENOMEM;
 130
 131         btrfs_cpu_key_to_disk(&disk_key, location);
 132
 133         data_size = sizeof(*dir_item) + name_len;
 134         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
 135                                         name, name_len);
 136         if (IS_ERR(dir_item)) {
 137                 ret = PTR_ERR(dir_item);
 138                 if (ret == -EEXIST)
 139                         goto second_insert;
 140                 goto out_free;
 141         }
 142
 143         leaf = path->nodes[0];
 144         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 145         btrfs_set_dir_type(leaf, dir_item, type);
 146         btrfs_set_dir_data_len(leaf, dir_item, 0);
 147         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 148         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 149         name_ptr = (unsigned long)(dir_item + 1);
 150
 151         write_extent_buffer(leaf, name, name_ptr, name_len);
 152         btrfs_mark_buffer_dirty(leaf);
 153
 154 second_insert:
 155         /* FIXME, use some real flag for selecting the extra index */
 156         if (root == root->fs_info->tree_root) {
 157                 ret = 0;
 158                 goto out_free;
 159         }
 160         btrfs_release_path(path);
 161
 162         ret2 = btrfs_insert_delayed_dir_index(trans, name, name_len, dir,
 163                                               &disk_key, type, index);
 164 out_free:
 165         btrfs_free_path(path);
 166         if (ret)
 167                 return ret;
 168         if (ret2)
 169                 return ret2;
 170         return 0;
 171 }
 172
 173 /*
 174  * lookup a directory item based on name.  'dir' is the objectid
 175  * we're searching in, and 'mod' tells us if you plan on deleting the
 176  * item (use mod < 0) or changing the options (use mod > 0)
 177  */
 178 struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
 179                                              struct btrfs_root *root,
 180                                              struct btrfs_path *path, u64 dir,
 181                                              const char *name, int name_len,
 182                                              int mod)
 183 {
 184         int ret;
 185         struct btrfs_key key;
 186         int ins_len = mod < 0 ? -1 : 0;
 187         int cow = mod != 0;
 188
 189         key.objectid = dir;
 190         key.type = BTRFS_DIR_ITEM_KEY;
 191
 192         key.offset = btrfs_name_hash(name, name_len);
 193
 194         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 195         if (ret < 0)
 196                 return ERR_PTR(ret);
 197         if (ret > 0)
 198                 return NULL;
 199
 200         return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 201 }
 202
 203 int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
 204                                    const char *name, int name_len)
 205 {
 206         int ret;
 207         struct btrfs_key key;
 208         struct btrfs_dir_item *di;
 209         int data_size;
 210         struct extent_buffer *leaf;
 211         int slot;
 212         struct btrfs_path *path;
 213
 214
 215         path = btrfs_alloc_path();
 216         if (!path)
 217                 return -ENOMEM;
 218
 219         key.objectid = dir;
 220         key.type = BTRFS_DIR_ITEM_KEY;
 221         key.offset = btrfs_name_hash(name, name_len);
 222
 223         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 224
 225         /* return back any errors */
 226         if (ret < 0)
 227                 goto out;
 228
 229         /* nothing found, we're safe */
 230         if (ret > 0) {
 231                 ret = 0;
 232                 goto out;
 233         }
 234
 235         /* we found an item, look for our name in the item */
 236         di = btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 237         if (di) {
 238                 /* our exact name was found */
 239                 ret = -EEXIST;
 240                 goto out;
 241         }
 242
 243         /*
 244          * see if there is room in the item to insert this
 245          * name
 246          */
 247         data_size = sizeof(*di) + name_len;
 248         leaf = path->nodes[0];
 249         slot = path->slots[0];
 250         if (data_size + btrfs_item_size_nr(leaf, slot) +
 251             sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root->fs_info)) {
 252                 ret = -EOVERFLOW;
 253         } else {
 254                 /* plenty of insertion room */
 255                 ret = 0;
 256         }
 257 out:
 258         btrfs_free_path(path);
 259         return ret;
 260 }
 261
 262 /*
 263  * lookup a directory item based on index.  'dir' is the objectid
 264  * we're searching in, and 'mod' tells us if you plan on deleting the
 265  * item (use mod < 0) or changing the options (use mod > 0)
 266  *
 267  * The name is used to make sure the index really points to the name you were
 268  * looking for.
 269  */
 270 struct btrfs_dir_item *
 271 btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
 272                             struct btrfs_root *root,
 273                             struct btrfs_path *path, u64 dir,
 274                             u64 objectid, const char *name, int name_len,
 275                             int mod)
 276 {
 277         int ret;
 278         struct btrfs_key key;
 279         int ins_len = mod < 0 ? -1 : 0;
 280         int cow = mod != 0;
 281
 282         key.objectid = dir;
 283         key.type = BTRFS_DIR_INDEX_KEY;
 284         key.offset = objectid;
 285
 286         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 287         if (ret < 0)
 288                 return ERR_PTR(ret);
 289         if (ret > 0)
 290                 return ERR_PTR(-ENOENT);
 291         return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 292 }
 293
 294 struct btrfs_dir_item *
 295 btrfs_search_dir_index_item(struct btrfs_root *root,
 296                             struct btrfs_path *path, u64 dirid,
 297                             const char *name, int name_len)
 298 {
 299         struct extent_buffer *leaf;
 300         struct btrfs_dir_item *di;
 301         struct btrfs_key key;
 302         u32 nritems;
 303         int ret;
 304
 305         key.objectid = dirid;
 306         key.type = BTRFS_DIR_INDEX_KEY;
 307         key.offset = 0;
 308
 309         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 310         if (ret < 0)
 311                 return ERR_PTR(ret);
 312
 313         leaf = path->nodes[0];
 314         nritems = btrfs_header_nritems(leaf);
 315
 316         while (1) {
 317                 if (path->slots[0] >= nritems) {
 318                         ret = btrfs_next_leaf(root, path);
 319                         if (ret < 0)
 320                                 return ERR_PTR(ret);
 321                         if (ret > 0)
 322                                 break;
 323                         leaf = path->nodes[0];
 324                         nritems = btrfs_header_nritems(leaf);
 325                         continue;
 326                 }
 327
 328                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 329                 if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
 330                         break;
 331
 332                 di = btrfs_match_dir_item_name(root->fs_info, path,
 333                                                name, name_len);
 334                 if (di)
 335                         return di;
 336
 337                 path->slots[0]++;
 338         }
 339         return NULL;
 340 }
 341
 342 struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
 343                                           struct btrfs_root *root,
 344                                           struct btrfs_path *path, u64 dir,
 345                                           const char *name, u16 name_len,
 346                                           int mod)
 347 {
 348         int ret;
 349         struct btrfs_key key;
 350         int ins_len = mod < 0 ? -1 : 0;
 351         int cow = mod != 0;
 352
 353         key.objectid = dir;
 354         key.type = BTRFS_XATTR_ITEM_KEY;
 355         key.offset = btrfs_name_hash(name, name_len);
 356         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 357         if (ret < 0)
 358                 return ERR_PTR(ret);
 359         if (ret > 0)
 360                 return NULL;
 361
 362         return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 363 }
 364
 365 /*
 366  * helper function to look at the directory item pointed to by 'path'
 367  * this walks through all the entries in a dir item and finds one
 368  * for a specific name.
 369  */
 370 struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
 371                                                  struct btrfs_path *path,
 372                                                  const char *name, int name_len)
 373 {
 374         struct btrfs_dir_item *dir_item;
 375         unsigned long name_ptr;
 376         u32 total_len;
 377         u32 cur = 0;
 378         u32 this_len;
 379         struct extent_buffer *leaf;
 380
 381         leaf = path->nodes[0];
 382         dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
 383
 384         total_len = btrfs_item_size_nr(leaf, path->slots[0]);
 385         while (cur < total_len) {
 386                 this_len = sizeof(*dir_item) +
 387                         btrfs_dir_name_len(leaf, dir_item) +
 388                         btrfs_dir_data_len(leaf, dir_item);
 389                 name_ptr = (unsigned long)(dir_item + 1);
 390
 391                 if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
 392                     memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
 393                         return dir_item;
 394
 395                 cur += this_len;
 396                 dir_item = (struct btrfs_dir_item *)((char *)dir_item +
 397                                                      this_len);
 398         }
 399         return NULL;
 400 }
 401
 402 /*
 403  * given a pointer into a directory item, delete it.  This
 404  * handles items that have more than one entry in them.
 405  */
 406 int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 407                               struct btrfs_root *root,
 408                               struct btrfs_path *path,
 409                               struct btrfs_dir_item *di)
 410 {
 411
 412         struct extent_buffer *leaf;
 413         u32 sub_item_len;
 414         u32 item_len;
 415         int ret = 0;
 416
 417         leaf = path->nodes[0];
 418         sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
 419                 btrfs_dir_data_len(leaf, di);
 420         item_len = btrfs_item_size_nr(leaf, path->slots[0]);
 421         if (sub_item_len == item_len) {
 422                 ret = btrfs_del_item(trans, root, path);
 423         } else {
 424                 /* MARKER */
 425                 unsigned long ptr = (unsigned long)di;
 426                 unsigned long start;
 427
 428                 start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 429                 memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 430                         item_len - (ptr + sub_item_len - start));
 431                 btrfs_truncate_item(path, item_len - sub_item_len, 1);
 432         }
 433         return ret;
 434 }