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 "messages.h"
   7 #include "ctree.h"
   8 #include "disk-io.h"
   9 #include "transaction.h"
  10 #include "accessors.h"
  11 #include "dir-item.h"
  12
  13 /*
  14  * insert a name into a directory, doing overflow properly if there is a hash
  15  * collision.  data_size indicates how big the item inserted should be.  On
  16  * success a struct btrfs_dir_item pointer is returned, otherwise it is
  17  * an ERR_PTR.
  18  *
  19  * The name is not copied into the dir item, you have to do that yourself.
  20  */
  21 static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle
  22                                                    *trans,
  23                                                    struct btrfs_root *root,
  24                                                    struct btrfs_path *path,
  25                                                    const struct btrfs_key *cpu_key,
  26                                                    u32 data_size,
  27                                                    const char *name,
  28                                                    int name_len)
  29 {
  30         struct btrfs_fs_info *fs_info = root->fs_info;
  31         int ret;
  32         char *ptr;
  33         struct extent_buffer *leaf;
  34
  35         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
  36         if (ret == -EEXIST) {
  37                 struct btrfs_dir_item *di;
  38                 di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
  39                 if (di)
  40                         return ERR_PTR(-EEXIST);
  41                 btrfs_extend_item(trans, path, data_size);
  42         } else if (ret < 0)
  43                 return ERR_PTR(ret);
  44         WARN_ON(ret > 0);
  45         leaf = path->nodes[0];
  46         ptr = btrfs_item_ptr(leaf, path->slots[0], char);
  47         ASSERT(data_size <= btrfs_item_size(leaf, path->slots[0]));
  48         ptr += btrfs_item_size(leaf, path->slots[0]) - data_size;
  49         return (struct btrfs_dir_item *)ptr;
  50 }
  51
  52 /*
  53  * xattrs work a lot like directories, this inserts an xattr item
  54  * into the tree
  55  */
  56 int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
  57                             struct btrfs_root *root,
  58                             struct btrfs_path *path, u64 objectid,
  59                             const char *name, u16 name_len,
  60                             const void *data, u16 data_len)
  61 {
  62         int ret = 0;
  63         struct btrfs_dir_item *dir_item;
  64         unsigned long name_ptr, data_ptr;
  65         struct btrfs_key key, location;
  66         struct btrfs_disk_key disk_key;
  67         struct extent_buffer *leaf;
  68         u32 data_size;
  69
  70         if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root->fs_info))
  71                 return -ENOSPC;
  72
  73         key.objectid = objectid;
  74         key.type = BTRFS_XATTR_ITEM_KEY;
  75         key.offset = btrfs_name_hash(name, name_len);
  76
  77         data_size = sizeof(*dir_item) + name_len + data_len;
  78         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
  79                                         name, name_len);
  80         if (IS_ERR(dir_item))
  81                 return PTR_ERR(dir_item);
  82         memset(&location, 0, sizeof(location));
  83
  84         leaf = path->nodes[0];
  85         btrfs_cpu_key_to_disk(&disk_key, &location);
  86         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
  87         btrfs_set_dir_flags(leaf, dir_item, BTRFS_FT_XATTR);
  88         btrfs_set_dir_name_len(leaf, dir_item, name_len);
  89         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
  90         btrfs_set_dir_data_len(leaf, dir_item, data_len);
  91         name_ptr = (unsigned long)(dir_item + 1);
  92         data_ptr = (unsigned long)((char *)name_ptr + name_len);
  93
  94         write_extent_buffer(leaf, name, name_ptr, name_len);
  95         write_extent_buffer(leaf, data, data_ptr, data_len);
  96         btrfs_mark_buffer_dirty(trans, path->nodes[0]);
  97
  98         return ret;
  99 }
 100
 101 /*
 102  * insert a directory item in the tree, doing all the magic for
 103  * both indexes. 'dir' indicates which objectid to insert it into,
 104  * 'location' is the key to stuff into the directory item, 'type' is the
 105  * type of the inode we're pointing to, and 'index' is the sequence number
 106  * to use for the second index (if one is created).
 107  * Will return 0 or -ENOMEM
 108  */
 109 int btrfs_insert_dir_item(struct btrfs_trans_handle *trans,
 110                           const struct fscrypt_str *name, struct btrfs_inode *dir,
 111                           const struct btrfs_key *location, u8 type, u64 index)
 112 {
 113         int ret = 0;
 114         int ret2 = 0;
 115         struct btrfs_root *root = dir->root;
 116         struct btrfs_path *path;
 117         struct btrfs_dir_item *dir_item;
 118         struct extent_buffer *leaf;
 119         unsigned long name_ptr;
 120         struct btrfs_key key;
 121         struct btrfs_disk_key disk_key;
 122         u32 data_size;
 123
 124         key.objectid = btrfs_ino(dir);
 125         key.type = BTRFS_DIR_ITEM_KEY;
 126         key.offset = btrfs_name_hash(name->name, name->len);
 127
 128         path = btrfs_alloc_path();
 129         if (!path)
 130                 return -ENOMEM;
 131
 132         btrfs_cpu_key_to_disk(&disk_key, location);
 133
 134         data_size = sizeof(*dir_item) + name->len;
 135         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
 136                                         name->name, name->len);
 137         if (IS_ERR(dir_item)) {
 138                 ret = PTR_ERR(dir_item);
 139                 if (ret == -EEXIST)
 140                         goto second_insert;
 141                 goto out_free;
 142         }
 143
 144         if (IS_ENCRYPTED(&dir->vfs_inode))
 145                 type |= BTRFS_FT_ENCRYPTED;
 146
 147         leaf = path->nodes[0];
 148         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 149         btrfs_set_dir_flags(leaf, dir_item, type);
 150         btrfs_set_dir_data_len(leaf, dir_item, 0);
 151         btrfs_set_dir_name_len(leaf, dir_item, name->len);
 152         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 153         name_ptr = (unsigned long)(dir_item + 1);
 154
 155         write_extent_buffer(leaf, name->name, name_ptr, name->len);
 156         btrfs_mark_buffer_dirty(trans, leaf);
 157
 158 second_insert:
 159         /* FIXME, use some real flag for selecting the extra index */
 160         if (root == root->fs_info->tree_root) {
 161                 ret = 0;
 162                 goto out_free;
 163         }
 164         btrfs_release_path(path);
 165
 166         ret2 = btrfs_insert_delayed_dir_index(trans, name->name, name->len, dir,
 167                                               &disk_key, type, index);
 168 out_free:
 169         btrfs_free_path(path);
 170         if (ret)
 171                 return ret;
 172         if (ret2)
 173                 return ret2;
 174         return 0;
 175 }
 176
 177 static struct btrfs_dir_item *btrfs_lookup_match_dir(
 178                         struct btrfs_trans_handle *trans,
 179                         struct btrfs_root *root, struct btrfs_path *path,
 180                         struct btrfs_key *key, const char *name,
 181                         int name_len, int mod)
 182 {
 183         const int ins_len = (mod < 0 ? -1 : 0);
 184         const int cow = (mod != 0);
 185         int ret;
 186
 187         ret = btrfs_search_slot(trans, root, key, path, ins_len, cow);
 188         if (ret < 0)
 189                 return ERR_PTR(ret);
 190         if (ret > 0)
 191                 return ERR_PTR(-ENOENT);
 192
 193         return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 194 }
 195
 196 /*
 197  * Lookup for a directory item by name.
 198  *
 199  * @trans:      The transaction handle to use. Can be NULL if @mod is 0.
 200  * @root:       The root of the target tree.
 201  * @path:       Path to use for the search.
 202  * @dir:        The inode number (objectid) of the directory.
 203  * @name:       The name associated to the directory entry we are looking for.
 204  * @name_len:   The length of the name.
 205  * @mod:        Used to indicate if the tree search is meant for a read only
 206  *              lookup, for a modification lookup or for a deletion lookup, so
 207  *              its value should be 0, 1 or -1, respectively.
 208  *
 209  * Returns: NULL if the dir item does not exists, an error pointer if an error
 210  * happened, or a pointer to a dir item if a dir item exists for the given name.
 211  */
 212 struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
 213                                              struct btrfs_root *root,
 214                                              struct btrfs_path *path, u64 dir,
 215                                              const struct fscrypt_str *name,
 216                                              int mod)
 217 {
 218         struct btrfs_key key;
 219         struct btrfs_dir_item *di;
 220
 221         key.objectid = dir;
 222         key.type = BTRFS_DIR_ITEM_KEY;
 223         key.offset = btrfs_name_hash(name->name, name->len);
 224
 225         di = btrfs_lookup_match_dir(trans, root, path, &key, name->name,
 226                                     name->len, mod);
 227         if (IS_ERR(di) && PTR_ERR(di) == -ENOENT)
 228                 return NULL;
 229
 230         return di;
 231 }
 232
 233 int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
 234                                    const struct fscrypt_str *name)
 235 {
 236         int ret;
 237         struct btrfs_key key;
 238         struct btrfs_dir_item *di;
 239         int data_size;
 240         struct extent_buffer *leaf;
 241         int slot;
 242         struct btrfs_path *path;
 243
 244         path = btrfs_alloc_path();
 245         if (!path)
 246                 return -ENOMEM;
 247
 248         key.objectid = dir;
 249         key.type = BTRFS_DIR_ITEM_KEY;
 250         key.offset = btrfs_name_hash(name->name, name->len);
 251
 252         di = btrfs_lookup_match_dir(NULL, root, path, &key, name->name,
 253                                     name->len, 0);
 254         if (IS_ERR(di)) {
 255                 ret = PTR_ERR(di);
 256                 /* Nothing found, we're safe */
 257                 if (ret == -ENOENT) {
 258                         ret = 0;
 259                         goto out;
 260                 }
 261
 262                 if (ret < 0)
 263                         goto out;
 264         }
 265
 266         /* we found an item, look for our name in the item */
 267         if (di) {
 268                 /* our exact name was found */
 269                 ret = -EEXIST;
 270                 goto out;
 271         }
 272
 273         /* See if there is room in the item to insert this name. */
 274         data_size = sizeof(*di) + name->len;
 275         leaf = path->nodes[0];
 276         slot = path->slots[0];
 277         if (data_size + btrfs_item_size(leaf, slot) +
 278             sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root->fs_info)) {
 279                 ret = -EOVERFLOW;
 280         } else {
 281                 /* plenty of insertion room */
 282                 ret = 0;
 283         }
 284 out:
 285         btrfs_free_path(path);
 286         return ret;
 287 }
 288
 289 /*
 290  * Lookup for a directory index item by name and index number.
 291  *
 292  * @trans:      The transaction handle to use. Can be NULL if @mod is 0.
 293  * @root:       The root of the target tree.
 294  * @path:       Path to use for the search.
 295  * @dir:        The inode number (objectid) of the directory.
 296  * @index:      The index number.
 297  * @name:       The name associated to the directory entry we are looking for.
 298  * @name_len:   The length of the name.
 299  * @mod:        Used to indicate if the tree search is meant for a read only
 300  *              lookup, for a modification lookup or for a deletion lookup, so
 301  *              its value should be 0, 1 or -1, respectively.
 302  *
 303  * Returns: NULL if the dir index item does not exists, an error pointer if an
 304  * error happened, or a pointer to a dir item if the dir index item exists and
 305  * matches the criteria (name and index number).
 306  */
 307 struct btrfs_dir_item *
 308 btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
 309                             struct btrfs_root *root,
 310                             struct btrfs_path *path, u64 dir,
 311                             u64 index, const struct fscrypt_str *name, int mod)
 312 {
 313         struct btrfs_dir_item *di;
 314         struct btrfs_key key;
 315
 316         key.objectid = dir;
 317         key.type = BTRFS_DIR_INDEX_KEY;
 318         key.offset = index;
 319
 320         di = btrfs_lookup_match_dir(trans, root, path, &key, name->name,
 321                                     name->len, mod);
 322         if (di == ERR_PTR(-ENOENT))
 323                 return NULL;
 324
 325         return di;
 326 }
 327
 328 struct btrfs_dir_item *
 329 btrfs_search_dir_index_item(struct btrfs_root *root, struct btrfs_path *path,
 330                             u64 dirid, const struct fscrypt_str *name)
 331 {
 332         struct btrfs_dir_item *di;
 333         struct btrfs_key key;
 334         int ret;
 335
 336         key.objectid = dirid;
 337         key.type = BTRFS_DIR_INDEX_KEY;
 338         key.offset = 0;
 339
 340         btrfs_for_each_slot(root, &key, &key, path, ret) {
 341                 if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
 342                         break;
 343
 344                 di = btrfs_match_dir_item_name(root->fs_info, path,
 345                                                name->name, name->len);
 346                 if (di)
 347                         return di;
 348         }
 349         /* Adjust return code if the key was not found in the next leaf. */
 350         if (ret > 0)
 351                 ret = 0;
 352
 353         return ERR_PTR(ret);
 354 }
 355
 356 struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
 357                                           struct btrfs_root *root,
 358                                           struct btrfs_path *path, u64 dir,
 359                                           const char *name, u16 name_len,
 360                                           int mod)
 361 {
 362         struct btrfs_key key;
 363         struct btrfs_dir_item *di;
 364
 365         key.objectid = dir;
 366         key.type = BTRFS_XATTR_ITEM_KEY;
 367         key.offset = btrfs_name_hash(name, name_len);
 368
 369         di = btrfs_lookup_match_dir(trans, root, path, &key, name, name_len, mod);
 370         if (IS_ERR(di) && PTR_ERR(di) == -ENOENT)
 371                 return NULL;
 372
 373         return di;
 374 }
 375
 376 /*
 377  * helper function to look at the directory item pointed to by 'path'
 378  * this walks through all the entries in a dir item and finds one
 379  * for a specific name.
 380  */
 381 struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
 382                                                  const struct btrfs_path *path,
 383                                                  const char *name, int name_len)
 384 {
 385         struct btrfs_dir_item *dir_item;
 386         unsigned long name_ptr;
 387         u32 total_len;
 388         u32 cur = 0;
 389         u32 this_len;
 390         struct extent_buffer *leaf;
 391
 392         leaf = path->nodes[0];
 393         dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
 394
 395         total_len = btrfs_item_size(leaf, path->slots[0]);
 396         while (cur < total_len) {
 397                 this_len = sizeof(*dir_item) +
 398                         btrfs_dir_name_len(leaf, dir_item) +
 399                         btrfs_dir_data_len(leaf, dir_item);
 400                 name_ptr = (unsigned long)(dir_item + 1);
 401
 402                 if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
 403                     memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
 404                         return dir_item;
 405
 406                 cur += this_len;
 407                 dir_item = (struct btrfs_dir_item *)((char *)dir_item +
 408                                                      this_len);
 409         }
 410         return NULL;
 411 }
 412
 413 /*
 414  * given a pointer into a directory item, delete it.  This
 415  * handles items that have more than one entry in them.
 416  */
 417 int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 418                               struct btrfs_root *root,
 419                               struct btrfs_path *path,
 420                               const struct btrfs_dir_item *di)
 421 {
 422
 423         struct extent_buffer *leaf;
 424         u32 sub_item_len;
 425         u32 item_len;
 426         int ret = 0;
 427
 428         leaf = path->nodes[0];
 429         sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
 430                 btrfs_dir_data_len(leaf, di);
 431         item_len = btrfs_item_size(leaf, path->slots[0]);
 432         if (sub_item_len == item_len) {
 433                 ret = btrfs_del_item(trans, root, path);
 434         } else {
 435                 /* MARKER */
 436                 unsigned long ptr = (unsigned long)di;
 437                 unsigned long start;
 438
 439                 start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 440                 memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 441                         item_len - (ptr + sub_item_len - start));
 442                 btrfs_truncate_item(trans, path, item_len - sub_item_len, 1);
 443         }
 444         return ret;
 445 }