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         struct btrfs_fs_info *fs_info = root->fs_info;
  42         int ret;
  43         char *ptr;
  44         struct btrfs_item *item;
  45         struct extent_buffer *leaf;
  46
  47         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
  48         if (ret == -EEXIST) {
  49                 struct btrfs_dir_item *di;
  50                 di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
  51                 if (di)
  52                         return ERR_PTR(-EEXIST);
  53                 btrfs_extend_item(fs_info, path, data_size);
  54         } else if (ret < 0)
  55                 return ERR_PTR(ret);
  56         WARN_ON(ret > 0);
  57         leaf = path->nodes[0];
  58         item = btrfs_item_nr(path->slots[0]);
  59         ptr = btrfs_item_ptr(leaf, path->slots[0], char);
  60         BUG_ON(data_size > btrfs_item_size(leaf, item));
  61         ptr += btrfs_item_size(leaf, item) - data_size;
  62         return (struct btrfs_dir_item *)ptr;
  63 }
  64
  65 /*
  66  * xattrs work a lot like directories, this inserts an xattr item
  67  * into the tree
  68  */
  69 int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
  70                             struct btrfs_root *root,
  71                             struct btrfs_path *path, u64 objectid,
  72                             const char *name, u16 name_len,
  73                             const void *data, u16 data_len)
  74 {
  75         int ret = 0;
  76         struct btrfs_dir_item *dir_item;
  77         unsigned long name_ptr, data_ptr;
  78         struct btrfs_key key, location;
  79         struct btrfs_disk_key disk_key;
  80         struct extent_buffer *leaf;
  81         u32 data_size;
  82
  83         if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root->fs_info))
  84                 return -ENOSPC;
  85
  86         key.objectid = objectid;
  87         key.type = BTRFS_XATTR_ITEM_KEY;
  88         key.offset = btrfs_name_hash(name, name_len);
  89
  90         data_size = sizeof(*dir_item) + name_len + data_len;
  91         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
  92                                         name, name_len);
  93         if (IS_ERR(dir_item))
  94                 return PTR_ERR(dir_item);
  95         memset(&location, 0, sizeof(location));
  96
  97         leaf = path->nodes[0];
  98         btrfs_cpu_key_to_disk(&disk_key, &location);
  99         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 100         btrfs_set_dir_type(leaf, dir_item, BTRFS_FT_XATTR);
 101         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 102         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 103         btrfs_set_dir_data_len(leaf, dir_item, data_len);
 104         name_ptr = (unsigned long)(dir_item + 1);
 105         data_ptr = (unsigned long)((char *)name_ptr + name_len);
 106
 107         write_extent_buffer(leaf, name, name_ptr, name_len);
 108         write_extent_buffer(leaf, data, data_ptr, data_len);
 109         btrfs_mark_buffer_dirty(path->nodes[0]);
 110
 111         return ret;
 112 }
 113
 114 /*
 115  * insert a directory item in the tree, doing all the magic for
 116  * both indexes. 'dir' indicates which objectid to insert it into,
 117  * 'location' is the key to stuff into the directory item, 'type' is the
 118  * type of the inode we're pointing to, and 'index' is the sequence number
 119  * to use for the second index (if one is created).
 120  * Will return 0 or -ENOMEM
 121  */
 122 int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
 123                           *root, const char *name, int name_len,
 124                           struct btrfs_inode *dir, struct btrfs_key *location,
 125                           u8 type, u64 index)
 126 {
 127         int ret = 0;
 128         int ret2 = 0;
 129         struct btrfs_path *path;
 130         struct btrfs_dir_item *dir_item;
 131         struct extent_buffer *leaf;
 132         unsigned long name_ptr;
 133         struct btrfs_key key;
 134         struct btrfs_disk_key disk_key;
 135         u32 data_size;
 136
 137         key.objectid = btrfs_ino(dir);
 138         key.type = BTRFS_DIR_ITEM_KEY;
 139         key.offset = btrfs_name_hash(name, name_len);
 140
 141         path = btrfs_alloc_path();
 142         if (!path)
 143                 return -ENOMEM;
 144         path->leave_spinning = 1;
 145
 146         btrfs_cpu_key_to_disk(&disk_key, location);
 147
 148         data_size = sizeof(*dir_item) + name_len;
 149         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
 150                                         name, name_len);
 151         if (IS_ERR(dir_item)) {
 152                 ret = PTR_ERR(dir_item);
 153                 if (ret == -EEXIST)
 154                         goto second_insert;
 155                 goto out_free;
 156         }
 157
 158         leaf = path->nodes[0];
 159         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 160         btrfs_set_dir_type(leaf, dir_item, type);
 161         btrfs_set_dir_data_len(leaf, dir_item, 0);
 162         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 163         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 164         name_ptr = (unsigned long)(dir_item + 1);
 165
 166         write_extent_buffer(leaf, name, name_ptr, name_len);
 167         btrfs_mark_buffer_dirty(leaf);
 168
 169 second_insert:
 170         /* FIXME, use some real flag for selecting the extra index */
 171         if (root == root->fs_info->tree_root) {
 172                 ret = 0;
 173                 goto out_free;
 174         }
 175         btrfs_release_path(path);
 176
 177         ret2 = btrfs_insert_delayed_dir_index(trans, root->fs_info, name,
 178                         name_len, dir, &disk_key, type, index);
 179 out_free:
 180         btrfs_free_path(path);
 181         if (ret)
 182                 return ret;
 183         if (ret2)
 184                 return ret2;
 185         return 0;
 186 }
 187
 188 /*
 189  * lookup a directory item based on name.  'dir' is the objectid
 190  * we're searching in, and 'mod' tells us if you plan on deleting the
 191  * item (use mod < 0) or changing the options (use mod > 0)
 192  */
 193 struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
 194                                              struct btrfs_root *root,
 195                                              struct btrfs_path *path, u64 dir,
 196                                              const char *name, int name_len,
 197                                              int mod)
 198 {
 199         int ret;
 200         struct btrfs_key key;
 201         int ins_len = mod < 0 ? -1 : 0;
 202         int cow = mod != 0;
 203
 204         key.objectid = dir;
 205         key.type = BTRFS_DIR_ITEM_KEY;
 206
 207         key.offset = btrfs_name_hash(name, name_len);
 208
 209         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 210         if (ret < 0)
 211                 return ERR_PTR(ret);
 212         if (ret > 0)
 213                 return NULL;
 214
 215         return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 216 }
 217
 218 int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
 219                                    const char *name, int name_len)
 220 {
 221         int ret;
 222         struct btrfs_key key;
 223         struct btrfs_dir_item *di;
 224         int data_size;
 225         struct extent_buffer *leaf;
 226         int slot;
 227         struct btrfs_path *path;
 228
 229
 230         path = btrfs_alloc_path();
 231         if (!path)
 232                 return -ENOMEM;
 233
 234         key.objectid = dir;
 235         key.type = BTRFS_DIR_ITEM_KEY;
 236         key.offset = btrfs_name_hash(name, name_len);
 237
 238         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 239
 240         /* return back any errors */
 241         if (ret < 0)
 242                 goto out;
 243
 244         /* nothing found, we're safe */
 245         if (ret > 0) {
 246                 ret = 0;
 247                 goto out;
 248         }
 249
 250         /* we found an item, look for our name in the item */
 251         di = btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 252         if (di) {
 253                 /* our exact name was found */
 254                 ret = -EEXIST;
 255                 goto out;
 256         }
 257
 258         /*
 259          * see if there is room in the item to insert this
 260          * name
 261          */
 262         data_size = sizeof(*di) + name_len;
 263         leaf = path->nodes[0];
 264         slot = path->slots[0];
 265         if (data_size + btrfs_item_size_nr(leaf, slot) +
 266             sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root->fs_info)) {
 267                 ret = -EOVERFLOW;
 268         } else {
 269                 /* plenty of insertion room */
 270                 ret = 0;
 271         }
 272 out:
 273         btrfs_free_path(path);
 274         return ret;
 275 }
 276
 277 /*
 278  * lookup a directory item based on index.  'dir' is the objectid
 279  * we're searching in, and 'mod' tells us if you plan on deleting the
 280  * item (use mod < 0) or changing the options (use mod > 0)
 281  *
 282  * The name is used to make sure the index really points to the name you were
 283  * looking for.
 284  */
 285 struct btrfs_dir_item *
 286 btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
 287                             struct btrfs_root *root,
 288                             struct btrfs_path *path, u64 dir,
 289                             u64 objectid, const char *name, int name_len,
 290                             int mod)
 291 {
 292         int ret;
 293         struct btrfs_key key;
 294         int ins_len = mod < 0 ? -1 : 0;
 295         int cow = mod != 0;
 296
 297         key.objectid = dir;
 298         key.type = BTRFS_DIR_INDEX_KEY;
 299         key.offset = objectid;
 300
 301         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 302         if (ret < 0)
 303                 return ERR_PTR(ret);
 304         if (ret > 0)
 305                 return ERR_PTR(-ENOENT);
 306         return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 307 }
 308
 309 struct btrfs_dir_item *
 310 btrfs_search_dir_index_item(struct btrfs_root *root,
 311                             struct btrfs_path *path, u64 dirid,
 312                             const char *name, int name_len)
 313 {
 314         struct extent_buffer *leaf;
 315         struct btrfs_dir_item *di;
 316         struct btrfs_key key;
 317         u32 nritems;
 318         int ret;
 319
 320         key.objectid = dirid;
 321         key.type = BTRFS_DIR_INDEX_KEY;
 322         key.offset = 0;
 323
 324         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 325         if (ret < 0)
 326                 return ERR_PTR(ret);
 327
 328         leaf = path->nodes[0];
 329         nritems = btrfs_header_nritems(leaf);
 330
 331         while (1) {
 332                 if (path->slots[0] >= nritems) {
 333                         ret = btrfs_next_leaf(root, path);
 334                         if (ret < 0)
 335                                 return ERR_PTR(ret);
 336                         if (ret > 0)
 337                                 break;
 338                         leaf = path->nodes[0];
 339                         nritems = btrfs_header_nritems(leaf);
 340                         continue;
 341                 }
 342
 343                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 344                 if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
 345                         break;
 346
 347                 di = btrfs_match_dir_item_name(root->fs_info, path,
 348                                                name, name_len);
 349                 if (di)
 350                         return di;
 351
 352                 path->slots[0]++;
 353         }
 354         return NULL;
 355 }
 356
 357 struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
 358                                           struct btrfs_root *root,
 359                                           struct btrfs_path *path, u64 dir,
 360                                           const char *name, u16 name_len,
 361                                           int mod)
 362 {
 363         int ret;
 364         struct btrfs_key key;
 365         int ins_len = mod < 0 ? -1 : 0;
 366         int cow = mod != 0;
 367
 368         key.objectid = dir;
 369         key.type = BTRFS_XATTR_ITEM_KEY;
 370         key.offset = btrfs_name_hash(name, name_len);
 371         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 372         if (ret < 0)
 373                 return ERR_PTR(ret);
 374         if (ret > 0)
 375                 return NULL;
 376
 377         return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
 378 }
 379
 380 /*
 381  * helper function to look at the directory item pointed to by 'path'
 382  * this walks through all the entries in a dir item and finds one
 383  * for a specific name.
 384  */
 385 struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
 386                                                  struct btrfs_path *path,
 387                                                  const char *name, int name_len)
 388 {
 389         struct btrfs_dir_item *dir_item;
 390         unsigned long name_ptr;
 391         u32 total_len;
 392         u32 cur = 0;
 393         u32 this_len;
 394         struct extent_buffer *leaf;
 395
 396         leaf = path->nodes[0];
 397         dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
 398
 399         total_len = btrfs_item_size_nr(leaf, path->slots[0]);
 400         while (cur < total_len) {
 401                 this_len = sizeof(*dir_item) +
 402                         btrfs_dir_name_len(leaf, dir_item) +
 403                         btrfs_dir_data_len(leaf, dir_item);
 404                 name_ptr = (unsigned long)(dir_item + 1);
 405
 406                 if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
 407                     memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
 408                         return dir_item;
 409
 410                 cur += this_len;
 411                 dir_item = (struct btrfs_dir_item *)((char *)dir_item +
 412                                                      this_len);
 413         }
 414         return NULL;
 415 }
 416
 417 /*
 418  * given a pointer into a directory item, delete it.  This
 419  * handles items that have more than one entry in them.
 420  */
 421 int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 422                               struct btrfs_root *root,
 423                               struct btrfs_path *path,
 424                               struct btrfs_dir_item *di)
 425 {
 426
 427         struct extent_buffer *leaf;
 428         u32 sub_item_len;
 429         u32 item_len;
 430         int ret = 0;
 431
 432         leaf = path->nodes[0];
 433         sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
 434                 btrfs_dir_data_len(leaf, di);
 435         item_len = btrfs_item_size_nr(leaf, path->slots[0]);
 436         if (sub_item_len == item_len) {
 437                 ret = btrfs_del_item(trans, root, path);
 438         } else {
 439                 /* MARKER */
 440                 unsigned long ptr = (unsigned long)di;
 441                 unsigned long start;
 442
 443                 start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 444                 memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 445                         item_len - (ptr + sub_item_len - start));
 446                 btrfs_truncate_item(root->fs_info, path,
 447                                     item_len - sub_item_len, 1);
 448         }
 449         return ret;
 450 }