root/fs/btrfs/dir-item.c

DEFINITIONS

1. insert_with_overflow
2. btrfs_insert_xattr_item
3. btrfs_insert_dir_item
4. btrfs_lookup_dir_item
5. btrfs_check_dir_item_collision
6. btrfs_lookup_dir_index_item
7. btrfs_search_dir_index_item
8. btrfs_lookup_xattr
9. btrfs_match_dir_item_name
10. btrfs_delete_one_dir_name

   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         path->leave_spinning = 1;
 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_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         leaf = path->nodes[0];
 145         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 146         btrfs_set_dir_type(leaf, dir_item, type);
 147         btrfs_set_dir_data_len(leaf, dir_item, 0);
 148         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 149         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 150         name_ptr = (unsigned long)(dir_item + 1);
 151 
 152         write_extent_buffer(leaf, name, name_ptr, name_len);
 153         btrfs_mark_buffer_dirty(leaf);
 154 
 155 second_insert:
 156         /* FIXME, use some real flag for selecting the extra index */
 157         if (root == root->fs_info->tree_root) {
 158                 ret = 0;
 159                 goto out_free;
 160         }
 161         btrfs_release_path(path);
 162 
 163         ret2 = btrfs_insert_delayed_dir_index(trans, name, name_len, dir,
 164                                               &disk_key, type, index);
 165 out_free:
 166         btrfs_free_path(path);
 167         if (ret)
 168                 return ret;
 169         if (ret2)
 170                 return ret2;
 171         return 0;
 172 }
 173 
 174 /*
 175  * lookup a directory item based on name.  'dir' is the objectid
 176  * we're searching in, and 'mod' tells us if you plan on deleting the
 177  * item (use mod < 0) or changing the options (use mod > 0)
 178  */
 179 struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
 180                                              struct btrfs_root *root,
 181                                              struct btrfs_path *path, u64 dir,
 182                                              const char *name, int name_len,
 183                                              int mod)
 184 {
 185         int ret;
 186         struct btrfs_key key;
 187         int ins_len = mod < 0 ? -1 : 0;
 188         int cow = mod != 0;
 189 
 190         key.objectid = dir;
 191         key.type = BTRFS_DIR_ITEM_KEY;
 192 
 193         key.offset = btrfs_name_hash(name, name_len);
 194 
 195         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 196         if (ret < 0)
 197                 return ERR_PTR(ret);
 198         if (ret > 0)
 199                 return NULL;
 200 
 201         return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 202 }
 203 
 204 int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
 205                                    const char *name, int name_len)
 206 {
 207         int ret;
 208         struct btrfs_key key;
 209         struct btrfs_dir_item *di;
 210         int data_size;
 211         struct extent_buffer *leaf;
 212         int slot;
 213         struct btrfs_path *path;
 214 
 215 
 216         path = btrfs_alloc_path();
 217         if (!path)
 218                 return -ENOMEM;
 219 
 220         key.objectid = dir;
 221         key.type = BTRFS_DIR_ITEM_KEY;
 222         key.offset = btrfs_name_hash(name, name_len);
 223 
 224         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 225 
 226         /* return back any errors */
 227         if (ret < 0)
 228                 goto out;
 229 
 230         /* nothing found, we're safe */
 231         if (ret > 0) {
 232                 ret = 0;
 233                 goto out;
 234         }
 235 
 236         /* we found an item, look for our name in the item */
 237         di = btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 238         if (di) {
 239                 /* our exact name was found */
 240                 ret = -EEXIST;
 241                 goto out;
 242         }
 243 
 244         /*
 245          * see if there is room in the item to insert this
 246          * name
 247          */
 248         data_size = sizeof(*di) + name_len;
 249         leaf = path->nodes[0];
 250         slot = path->slots[0];
 251         if (data_size + btrfs_item_size_nr(leaf, slot) +
 252             sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root->fs_info)) {
 253                 ret = -EOVERFLOW;
 254         } else {
 255                 /* plenty of insertion room */
 256                 ret = 0;
 257         }
 258 out:
 259         btrfs_free_path(path);
 260         return ret;
 261 }
 262 
 263 /*
 264  * lookup a directory item based on index.  'dir' is the objectid
 265  * we're searching in, and 'mod' tells us if you plan on deleting the
 266  * item (use mod < 0) or changing the options (use mod > 0)
 267  *
 268  * The name is used to make sure the index really points to the name you were
 269  * looking for.
 270  */
 271 struct btrfs_dir_item *
 272 btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
 273                             struct btrfs_root *root,
 274                             struct btrfs_path *path, u64 dir,
 275                             u64 objectid, const char *name, int name_len,
 276                             int mod)
 277 {
 278         int ret;
 279         struct btrfs_key key;
 280         int ins_len = mod < 0 ? -1 : 0;
 281         int cow = mod != 0;
 282 
 283         key.objectid = dir;
 284         key.type = BTRFS_DIR_INDEX_KEY;
 285         key.offset = objectid;
 286 
 287         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 288         if (ret < 0)
 289                 return ERR_PTR(ret);
 290         if (ret > 0)
 291                 return ERR_PTR(-ENOENT);
 292         return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 293 }
 294 
 295 struct btrfs_dir_item *
 296 btrfs_search_dir_index_item(struct btrfs_root *root,
 297                             struct btrfs_path *path, u64 dirid,
 298                             const char *name, int name_len)
 299 {
 300         struct extent_buffer *leaf;
 301         struct btrfs_dir_item *di;
 302         struct btrfs_key key;
 303         u32 nritems;
 304         int ret;
 305 
 306         key.objectid = dirid;
 307         key.type = BTRFS_DIR_INDEX_KEY;
 308         key.offset = 0;
 309 
 310         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 311         if (ret < 0)
 312                 return ERR_PTR(ret);
 313 
 314         leaf = path->nodes[0];
 315         nritems = btrfs_header_nritems(leaf);
 316 
 317         while (1) {
 318                 if (path->slots[0] >= nritems) {
 319                         ret = btrfs_next_leaf(root, path);
 320                         if (ret < 0)
 321                                 return ERR_PTR(ret);
 322                         if (ret > 0)
 323                                 break;
 324                         leaf = path->nodes[0];
 325                         nritems = btrfs_header_nritems(leaf);
 326                         continue;
 327                 }
 328 
 329                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 330                 if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
 331                         break;
 332 
 333                 di = btrfs_match_dir_item_name(root->fs_info, path,
 334                                                name, name_len);
 335                 if (di)
 336                         return di;
 337 
 338                 path->slots[0]++;
 339         }
 340         return NULL;
 341 }
 342 
 343 struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
 344                                           struct btrfs_root *root,
 345                                           struct btrfs_path *path, u64 dir,
 346                                           const char *name, u16 name_len,
 347                                           int mod)
 348 {
 349         int ret;
 350         struct btrfs_key key;
 351         int ins_len = mod < 0 ? -1 : 0;
 352         int cow = mod != 0;
 353 
 354         key.objectid = dir;
 355         key.type = BTRFS_XATTR_ITEM_KEY;
 356         key.offset = btrfs_name_hash(name, name_len);
 357         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 358         if (ret < 0)
 359                 return ERR_PTR(ret);
 360         if (ret > 0)
 361                 return NULL;
 362 
 363         return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 364 }
 365 
 366 /*
 367  * helper function to look at the directory item pointed to by 'path'
 368  * this walks through all the entries in a dir item and finds one
 369  * for a specific name.
 370  */
 371 struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
 372                                                  struct btrfs_path *path,
 373                                                  const char *name, int name_len)
 374 {
 375         struct btrfs_dir_item *dir_item;
 376         unsigned long name_ptr;
 377         u32 total_len;
 378         u32 cur = 0;
 379         u32 this_len;
 380         struct extent_buffer *leaf;
 381 
 382         leaf = path->nodes[0];
 383         dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
 384 
 385         total_len = btrfs_item_size_nr(leaf, path->slots[0]);
 386         while (cur < total_len) {
 387                 this_len = sizeof(*dir_item) +
 388                         btrfs_dir_name_len(leaf, dir_item) +
 389                         btrfs_dir_data_len(leaf, dir_item);
 390                 name_ptr = (unsigned long)(dir_item + 1);
 391 
 392                 if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
 393                     memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
 394                         return dir_item;
 395 
 396                 cur += this_len;
 397                 dir_item = (struct btrfs_dir_item *)((char *)dir_item +
 398                                                      this_len);
 399         }
 400         return NULL;
 401 }
 402 
 403 /*
 404  * given a pointer into a directory item, delete it.  This
 405  * handles items that have more than one entry in them.
 406  */
 407 int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 408                               struct btrfs_root *root,
 409                               struct btrfs_path *path,
 410                               struct btrfs_dir_item *di)
 411 {
 412 
 413         struct extent_buffer *leaf;
 414         u32 sub_item_len;
 415         u32 item_len;
 416         int ret = 0;
 417 
 418         leaf = path->nodes[0];
 419         sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
 420                 btrfs_dir_data_len(leaf, di);
 421         item_len = btrfs_item_size_nr(leaf, path->slots[0]);
 422         if (sub_item_len == item_len) {
 423                 ret = btrfs_del_item(trans, root, path);
 424         } else {
 425                 /* MARKER */
 426                 unsigned long ptr = (unsigned long)di;
 427                 unsigned long start;
 428 
 429                 start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 430                 memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 431                         item_len - (ptr + sub_item_len - start));
 432                 btrfs_truncate_item(path, item_len - sub_item_len, 1);
 433         }
 434         return ret;
 435 }