linux/fs/btrfs/dir-item.c
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   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 */
  32static 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 */
  68int 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 */
 120int 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
 167second_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);
 177out_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 */
 191struct 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/*
 217 * lookup a directory item based on index.  'dir' is the objectid
 218 * we're searching in, and 'mod' tells us if you plan on deleting the
 219 * item (use mod < 0) or changing the options (use mod > 0)
 220 *
 221 * The name is used to make sure the index really points to the name you were
 222 * looking for.
 223 */
 224struct btrfs_dir_item *
 225btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
 226                            struct btrfs_root *root,
 227                            struct btrfs_path *path, u64 dir,
 228                            u64 objectid, const char *name, int name_len,
 229                            int mod)
 230{
 231        int ret;
 232        struct btrfs_key key;
 233        int ins_len = mod < 0 ? -1 : 0;
 234        int cow = mod != 0;
 235
 236        key.objectid = dir;
 237        btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
 238        key.offset = objectid;
 239
 240        ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 241        if (ret < 0)
 242                return ERR_PTR(ret);
 243        if (ret > 0)
 244                return ERR_PTR(-ENOENT);
 245        return btrfs_match_dir_item_name(root, path, name, name_len);
 246}
 247
 248struct btrfs_dir_item *
 249btrfs_search_dir_index_item(struct btrfs_root *root,
 250                            struct btrfs_path *path, u64 dirid,
 251                            const char *name, int name_len)
 252{
 253        struct extent_buffer *leaf;
 254        struct btrfs_dir_item *di;
 255        struct btrfs_key key;
 256        u32 nritems;
 257        int ret;
 258
 259        key.objectid = dirid;
 260        key.type = BTRFS_DIR_INDEX_KEY;
 261        key.offset = 0;
 262
 263        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 264        if (ret < 0)
 265                return ERR_PTR(ret);
 266
 267        leaf = path->nodes[0];
 268        nritems = btrfs_header_nritems(leaf);
 269
 270        while (1) {
 271                if (path->slots[0] >= nritems) {
 272                        ret = btrfs_next_leaf(root, path);
 273                        if (ret < 0)
 274                                return ERR_PTR(ret);
 275                        if (ret > 0)
 276                                break;
 277                        leaf = path->nodes[0];
 278                        nritems = btrfs_header_nritems(leaf);
 279                        continue;
 280                }
 281
 282                btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 283                if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
 284                        break;
 285
 286                di = btrfs_match_dir_item_name(root, path, name, name_len);
 287                if (di)
 288                        return di;
 289
 290                path->slots[0]++;
 291        }
 292        return NULL;
 293}
 294
 295struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
 296                                          struct btrfs_root *root,
 297                                          struct btrfs_path *path, u64 dir,
 298                                          const char *name, u16 name_len,
 299                                          int mod)
 300{
 301        int ret;
 302        struct btrfs_key key;
 303        int ins_len = mod < 0 ? -1 : 0;
 304        int cow = mod != 0;
 305
 306        key.objectid = dir;
 307        btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
 308        key.offset = btrfs_name_hash(name, name_len);
 309        ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 310        if (ret < 0)
 311                return ERR_PTR(ret);
 312        if (ret > 0)
 313                return NULL;
 314
 315        return btrfs_match_dir_item_name(root, path, name, name_len);
 316}
 317
 318/*
 319 * helper function to look at the directory item pointed to by 'path'
 320 * this walks through all the entries in a dir item and finds one
 321 * for a specific name.
 322 */
 323struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root,
 324                              struct btrfs_path *path,
 325                              const char *name, int name_len)
 326{
 327        struct btrfs_dir_item *dir_item;
 328        unsigned long name_ptr;
 329        u32 total_len;
 330        u32 cur = 0;
 331        u32 this_len;
 332        struct extent_buffer *leaf;
 333
 334        leaf = path->nodes[0];
 335        dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
 336        if (verify_dir_item(root, leaf, dir_item))
 337                return NULL;
 338
 339        total_len = btrfs_item_size_nr(leaf, path->slots[0]);
 340        while (cur < total_len) {
 341                this_len = sizeof(*dir_item) +
 342                        btrfs_dir_name_len(leaf, dir_item) +
 343                        btrfs_dir_data_len(leaf, dir_item);
 344                name_ptr = (unsigned long)(dir_item + 1);
 345
 346                if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
 347                    memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
 348                        return dir_item;
 349
 350                cur += this_len;
 351                dir_item = (struct btrfs_dir_item *)((char *)dir_item +
 352                                                     this_len);
 353        }
 354        return NULL;
 355}
 356
 357/*
 358 * given a pointer into a directory item, delete it.  This
 359 * handles items that have more than one entry in them.
 360 */
 361int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 362                              struct btrfs_root *root,
 363                              struct btrfs_path *path,
 364                              struct btrfs_dir_item *di)
 365{
 366
 367        struct extent_buffer *leaf;
 368        u32 sub_item_len;
 369        u32 item_len;
 370        int ret = 0;
 371
 372        leaf = path->nodes[0];
 373        sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
 374                btrfs_dir_data_len(leaf, di);
 375        item_len = btrfs_item_size_nr(leaf, path->slots[0]);
 376        if (sub_item_len == item_len) {
 377                ret = btrfs_del_item(trans, root, path);
 378        } else {
 379                /* MARKER */
 380                unsigned long ptr = (unsigned long)di;
 381                unsigned long start;
 382
 383                start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 384                memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 385                        item_len - (ptr + sub_item_len - start));
 386                btrfs_truncate_item(trans, root, path,
 387                                    item_len - sub_item_len, 1);
 388        }
 389        return ret;
 390}
 391
 392int verify_dir_item(struct btrfs_root *root,
 393                    struct extent_buffer *leaf,
 394                    struct btrfs_dir_item *dir_item)
 395{
 396        u16 namelen = BTRFS_NAME_LEN;
 397        u8 type = btrfs_dir_type(leaf, dir_item);
 398
 399        if (type >= BTRFS_FT_MAX) {
 400                printk(KERN_CRIT "btrfs: invalid dir item type: %d\n",
 401                       (int)type);
 402                return 1;
 403        }
 404
 405        if (type == BTRFS_FT_XATTR)
 406                namelen = XATTR_NAME_MAX;
 407
 408        if (btrfs_dir_name_len(leaf, dir_item) > namelen) {
 409                printk(KERN_CRIT "btrfs: invalid dir item name len: %u\n",
 410                       (unsigned)btrfs_dir_data_len(leaf, dir_item));
 411                return 1;
 412        }
 413
 414        /* BTRFS_MAX_XATTR_SIZE is the same for all dir items */
 415        if (btrfs_dir_data_len(leaf, dir_item) > BTRFS_MAX_XATTR_SIZE(root)) {
 416                printk(KERN_CRIT "btrfs: invalid dir item data len: %u\n",
 417                       (unsigned)btrfs_dir_data_len(leaf, dir_item));
 418                return 1;
 419        }
 420
 421        return 0;
 422}
 423
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