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