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, const char *name,
  72                             u16 name_len, const void *data, u16 data_len,
  73                             u64 dir)
  74 {
  75         int ret = 0;
  76         struct btrfs_path *path;
  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         key.objectid = dir;
  85         btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
  86         key.offset = btrfs_name_hash(name, name_len);
  87         path = btrfs_alloc_path();
  88         if (!path)
  89                 return -ENOMEM;
  90         if (name_len + data_len + sizeof(struct btrfs_dir_item) >
  91             BTRFS_LEAF_DATA_SIZE(root) - sizeof(struct btrfs_item))
  92                 return -ENOSPC;
  93
  94         data_size = sizeof(*dir_item) + name_len + data_len;
  95         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
  96                                         name, name_len);
  97         /*
  98          * FIXME: at some point we should handle xattr's that are larger than
  99          * what we can fit in our leaf.  We set location to NULL b/c we arent
 100          * pointing at anything else, that will change if we store the xattr
 101          * data in a separate inode.
 102          */
 103         BUG_ON(IS_ERR(dir_item));
 104         memset(&location, 0, sizeof(location));
 105
 106         leaf = path->nodes[0];
 107         btrfs_cpu_key_to_disk(&disk_key, &location);
 108         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 109         btrfs_set_dir_type(leaf, dir_item, BTRFS_FT_XATTR);
 110         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 111         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 112         btrfs_set_dir_data_len(leaf, dir_item, data_len);
 113         name_ptr = (unsigned long)(dir_item + 1);
 114         data_ptr = (unsigned long)((char *)name_ptr + name_len);
 115
 116         write_extent_buffer(leaf, name, name_ptr, name_len);
 117         write_extent_buffer(leaf, data, data_ptr, data_len);
 118         btrfs_mark_buffer_dirty(path->nodes[0]);
 119
 120         btrfs_free_path(path);
 121         return ret;
 122 }
 123
 124 /*
 125  * insert a directory item in the tree, doing all the magic for
 126  * both indexes. 'dir' indicates which objectid to insert it into,
 127  * 'location' is the key to stuff into the directory item, 'type' is the
 128  * type of the inode we're pointing to, and 'index' is the sequence number
 129  * to use for the second index (if one is created).
 130  */
 131 int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
 132                           *root, const char *name, int name_len, u64 dir,
 133                           struct btrfs_key *location, u8 type, u64 index)
 134 {
 135         int ret = 0;
 136         int ret2 = 0;
 137         struct btrfs_path *path;
 138         struct btrfs_dir_item *dir_item;
 139         struct extent_buffer *leaf;
 140         unsigned long name_ptr;
 141         struct btrfs_key key;
 142         struct btrfs_disk_key disk_key;
 143         u32 data_size;
 144
 145         key.objectid = dir;
 146         btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
 147         key.offset = btrfs_name_hash(name, name_len);
 148         path = btrfs_alloc_path();
 149         data_size = sizeof(*dir_item) + name_len;
 150         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
 151                                         name, name_len);
 152         if (IS_ERR(dir_item)) {
 153                 ret = PTR_ERR(dir_item);
 154                 if (ret == -EEXIST)
 155                         goto second_insert;
 156                 goto out;
 157         }
 158
 159         leaf = path->nodes[0];
 160         btrfs_cpu_key_to_disk(&disk_key, location);
 161         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 162         btrfs_set_dir_type(leaf, dir_item, type);
 163         btrfs_set_dir_data_len(leaf, dir_item, 0);
 164         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 165         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 166         name_ptr = (unsigned long)(dir_item + 1);
 167
 168         write_extent_buffer(leaf, name, name_ptr, name_len);
 169         btrfs_mark_buffer_dirty(leaf);
 170
 171 second_insert:
 172         /* FIXME, use some real flag for selecting the extra index */
 173         if (root == root->fs_info->tree_root) {
 174                 ret = 0;
 175                 goto out;
 176         }
 177         btrfs_release_path(root, path);
 178
 179         btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
 180         key.offset = index;
 181         dir_item = insert_with_overflow(trans, root, path, &key, data_size,
 182                                         name, name_len);
 183         if (IS_ERR(dir_item)) {
 184                 ret2 = PTR_ERR(dir_item);
 185                 goto out;
 186         }
 187         leaf = path->nodes[0];
 188         btrfs_cpu_key_to_disk(&disk_key, location);
 189         btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
 190         btrfs_set_dir_type(leaf, dir_item, type);
 191         btrfs_set_dir_data_len(leaf, dir_item, 0);
 192         btrfs_set_dir_name_len(leaf, dir_item, name_len);
 193         btrfs_set_dir_transid(leaf, dir_item, trans->transid);
 194         name_ptr = (unsigned long)(dir_item + 1);
 195         write_extent_buffer(leaf, name, name_ptr, name_len);
 196         btrfs_mark_buffer_dirty(leaf);
 197 out:
 198         btrfs_free_path(path);
 199         if (ret)
 200                 return ret;
 201         if (ret2)
 202                 return ret2;
 203         return 0;
 204 }
 205
 206 /*
 207  * lookup a directory item based on name.  'dir' is the objectid
 208  * we're searching in, and 'mod' tells us if you plan on deleting the
 209  * item (use mod < 0) or changing the options (use mod > 0)
 210  */
 211 struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
 212                                              struct btrfs_root *root,
 213                                              struct btrfs_path *path, u64 dir,
 214                                              const char *name, int name_len,
 215                                              int mod)
 216 {
 217         int ret;
 218         struct btrfs_key key;
 219         int ins_len = mod < 0 ? -1 : 0;
 220         int cow = mod != 0;
 221         struct btrfs_key found_key;
 222         struct extent_buffer *leaf;
 223
 224         key.objectid = dir;
 225         btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
 226
 227         key.offset = btrfs_name_hash(name, name_len);
 228
 229         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 230         if (ret < 0)
 231                 return ERR_PTR(ret);
 232         if (ret > 0) {
 233                 if (path->slots[0] == 0)
 234                         return NULL;
 235                 path->slots[0]--;
 236         }
 237
 238         leaf = path->nodes[0];
 239         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 240
 241         if (found_key.objectid != dir ||
 242             btrfs_key_type(&found_key) != BTRFS_DIR_ITEM_KEY ||
 243             found_key.offset != key.offset)
 244                 return NULL;
 245
 246         return btrfs_match_dir_item_name(root, path, name, name_len);
 247 }
 248
 249 /*
 250  * lookup a directory item based on index.  'dir' is the objectid
 251  * we're searching in, and 'mod' tells us if you plan on deleting the
 252  * item (use mod < 0) or changing the options (use mod > 0)
 253  *
 254  * The name is used to make sure the index really points to the name you were
 255  * looking for.
 256  */
 257 struct btrfs_dir_item *
 258 btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
 259                             struct btrfs_root *root,
 260                             struct btrfs_path *path, u64 dir,
 261                             u64 objectid, const char *name, int name_len,
 262                             int mod)
 263 {
 264         int ret;
 265         struct btrfs_key key;
 266         int ins_len = mod < 0 ? -1 : 0;
 267         int cow = mod != 0;
 268
 269         key.objectid = dir;
 270         btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
 271         key.offset = objectid;
 272
 273         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 274         if (ret < 0)
 275                 return ERR_PTR(ret);
 276         if (ret > 0)
 277                 return ERR_PTR(-ENOENT);
 278         return btrfs_match_dir_item_name(root, path, name, name_len);
 279 }
 280
 281 struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
 282                                           struct btrfs_root *root,
 283                                           struct btrfs_path *path, u64 dir,
 284                                           const char *name, u16 name_len,
 285                                           int mod)
 286 {
 287         int ret;
 288         struct btrfs_key key;
 289         int ins_len = mod < 0 ? -1 : 0;
 290         int cow = mod != 0;
 291         struct btrfs_key found_key;
 292         struct extent_buffer *leaf;
 293
 294         key.objectid = dir;
 295         btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
 296         key.offset = btrfs_name_hash(name, name_len);
 297         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 298         if (ret < 0)
 299                 return ERR_PTR(ret);
 300         if (ret > 0) {
 301                 if (path->slots[0] == 0)
 302                         return NULL;
 303                 path->slots[0]--;
 304         }
 305
 306         leaf = path->nodes[0];
 307         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 308
 309         if (found_key.objectid != dir ||
 310             btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY ||
 311             found_key.offset != key.offset)
 312                 return NULL;
 313
 314         return btrfs_match_dir_item_name(root, path, name, name_len);
 315 }
 316
 317 /*
 318  * helper function to look at the directory item pointed to by 'path'
 319  * this walks through all the entries in a dir item and finds one
 320  * for a specific name.
 321  */
 322 struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root,
 323                               struct btrfs_path *path,
 324                               const char *name, int name_len)
 325 {
 326         struct btrfs_dir_item *dir_item;
 327         unsigned long name_ptr;
 328         u32 total_len;
 329         u32 cur = 0;
 330         u32 this_len;
 331         struct extent_buffer *leaf;
 332
 333         leaf = path->nodes[0];
 334         dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
 335         total_len = btrfs_item_size_nr(leaf, path->slots[0]);
 336         while (cur < total_len) {
 337                 this_len = sizeof(*dir_item) +
 338                         btrfs_dir_name_len(leaf, dir_item) +
 339                         btrfs_dir_data_len(leaf, dir_item);
 340                 name_ptr = (unsigned long)(dir_item + 1);
 341
 342                 if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
 343                     memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
 344                         return dir_item;
 345
 346                 cur += this_len;
 347                 dir_item = (struct btrfs_dir_item *)((char *)dir_item +
 348                                                      this_len);
 349         }
 350         return NULL;
 351 }
 352
 353 /*
 354  * given a pointer into a directory item, delete it.  This
 355  * handles items that have more than one entry in them.
 356  */
 357 int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
 358                               struct btrfs_root *root,
 359                               struct btrfs_path *path,
 360                               struct btrfs_dir_item *di)
 361 {
 362
 363         struct extent_buffer *leaf;
 364         u32 sub_item_len;
 365         u32 item_len;
 366         int ret = 0;
 367
 368         leaf = path->nodes[0];
 369         sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
 370                 btrfs_dir_data_len(leaf, di);
 371         item_len = btrfs_item_size_nr(leaf, path->slots[0]);
 372         if (sub_item_len == item_len) {
 373                 ret = btrfs_del_item(trans, root, path);
 374         } else {
 375                 /* MARKER */
 376                 unsigned long ptr = (unsigned long)di;
 377                 unsigned long start;
 378
 379                 start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 380                 memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 381                         item_len - (ptr + sub_item_len - start));
 382                 ret = btrfs_truncate_item(trans, root, path,
 383                                           item_len - sub_item_len, 1);
 384         }
 385         return 0;
 386 }