fs/btrfs/inode-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 #include "print-tree.h"
  24
  25 static int find_name_in_backref(struct btrfs_path *path, const char *name,
  26                          int name_len, struct btrfs_inode_ref **ref_ret)
  27 {
  28         struct extent_buffer *leaf;
  29         struct btrfs_inode_ref *ref;
  30         unsigned long ptr;
  31         unsigned long name_ptr;
  32         u32 item_size;
  33         u32 cur_offset = 0;
  34         int len;
  35
  36         leaf = path->nodes[0];
  37         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
  38         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
  39         while (cur_offset < item_size) {
  40                 ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
  41                 len = btrfs_inode_ref_name_len(leaf, ref);
  42                 name_ptr = (unsigned long)(ref + 1);
  43                 cur_offset += len + sizeof(*ref);
  44                 if (len != name_len)
  45                         continue;
  46                 if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0) {
  47                         *ref_ret = ref;
  48                         return 1;
  49                 }
  50         }
  51         return 0;
  52 }
  53
  54 int btrfs_find_name_in_ext_backref(struct btrfs_path *path, u64 ref_objectid,
  55                                    const char *name, int name_len,
  56                                    struct btrfs_inode_extref **extref_ret)
  57 {
  58         struct extent_buffer *leaf;
  59         struct btrfs_inode_extref *extref;
  60         unsigned long ptr;
  61         unsigned long name_ptr;
  62         u32 item_size;
  63         u32 cur_offset = 0;
  64         int ref_name_len;
  65
  66         leaf = path->nodes[0];
  67         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
  68         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
  69
  70         /*
  71          * Search all extended backrefs in this item. We're only
  72          * looking through any collisions so most of the time this is
  73          * just going to compare against one buffer. If all is well,
  74          * we'll return success and the inode ref object.
  75          */
  76         while (cur_offset < item_size) {
  77                 extref = (struct btrfs_inode_extref *) (ptr + cur_offset);
  78                 name_ptr = (unsigned long)(&extref->name);
  79                 ref_name_len = btrfs_inode_extref_name_len(leaf, extref);
  80
  81                 if (ref_name_len == name_len &&
  82                     btrfs_inode_extref_parent(leaf, extref) == ref_objectid &&
  83                     (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)) {
  84                         if (extref_ret)
  85                                 *extref_ret = extref;
  86                         return 1;
  87                 }
  88
  89                 cur_offset += ref_name_len + sizeof(*extref);
  90         }
  91         return 0;
  92 }
  93
  94 /* Returns NULL if no extref found */
  95 struct btrfs_inode_extref *
  96 btrfs_lookup_inode_extref(struct btrfs_trans_handle *trans,
  97                           struct btrfs_root *root,
  98                           struct btrfs_path *path,
  99                           const char *name, int name_len,
 100                           u64 inode_objectid, u64 ref_objectid, int ins_len,
 101                           int cow)
 102 {
 103         int ret;
 104         struct btrfs_key key;
 105         struct btrfs_inode_extref *extref;
 106
 107         key.objectid = inode_objectid;
 108         key.type = BTRFS_INODE_EXTREF_KEY;
 109         key.offset = btrfs_extref_hash(ref_objectid, name, name_len);
 110
 111         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
 112         if (ret < 0)
 113                 return ERR_PTR(ret);
 114         if (ret > 0)
 115                 return NULL;
 116         if (!btrfs_find_name_in_ext_backref(path, ref_objectid, name, name_len, &extref))
 117                 return NULL;
 118         return extref;
 119 }
 120
 121 static int btrfs_del_inode_extref(struct btrfs_trans_handle *trans,
 122                                   struct btrfs_root *root,
 123                                   const char *name, int name_len,
 124                                   u64 inode_objectid, u64 ref_objectid,
 125                                   u64 *index)
 126 {
 127         struct btrfs_path *path;
 128         struct btrfs_key key;
 129         struct btrfs_inode_extref *extref;
 130         struct extent_buffer *leaf;
 131         int ret;
 132         int del_len = name_len + sizeof(*extref);
 133         unsigned long ptr;
 134         unsigned long item_start;
 135         u32 item_size;
 136
 137         key.objectid = inode_objectid;
 138         key.type = BTRFS_INODE_EXTREF_KEY;
 139         key.offset = btrfs_extref_hash(ref_objectid, name, name_len);
 140
 141         path = btrfs_alloc_path();
 142         if (!path)
 143                 return -ENOMEM;
 144
 145         path->leave_spinning = 1;
 146
 147         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 148         if (ret > 0)
 149                 ret = -ENOENT;
 150         if (ret < 0)
 151                 goto out;
 152
 153         /*
 154          * Sanity check - did we find the right item for this name?
 155          * This should always succeed so error here will make the FS
 156          * readonly.
 157          */
 158         if (!btrfs_find_name_in_ext_backref(path, ref_objectid,
 159                                             name, name_len, &extref)) {
 160                 btrfs_std_error(root->fs_info, -ENOENT, NULL);
 161                 ret = -EROFS;
 162                 goto out;
 163         }
 164
 165         leaf = path->nodes[0];
 166         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 167         if (index)
 168                 *index = btrfs_inode_extref_index(leaf, extref);
 169
 170         if (del_len == item_size) {
 171                 /*
 172                  * Common case only one ref in the item, remove the
 173                  * whole item.
 174                  */
 175                 ret = btrfs_del_item(trans, root, path);
 176                 goto out;
 177         }
 178
 179         ptr = (unsigned long)extref;
 180         item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 181
 182         memmove_extent_buffer(leaf, ptr, ptr + del_len,
 183                               item_size - (ptr + del_len - item_start));
 184
 185         btrfs_truncate_item(root, path, item_size - del_len, 1);
 186
 187 out:
 188         btrfs_free_path(path);
 189
 190         return ret;
 191 }
 192
 193 int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
 194                         struct btrfs_root *root,
 195                         const char *name, int name_len,
 196                         u64 inode_objectid, u64 ref_objectid, u64 *index)
 197 {
 198         struct btrfs_path *path;
 199         struct btrfs_key key;
 200         struct btrfs_inode_ref *ref;
 201         struct extent_buffer *leaf;
 202         unsigned long ptr;
 203         unsigned long item_start;
 204         u32 item_size;
 205         u32 sub_item_len;
 206         int ret;
 207         int search_ext_refs = 0;
 208         int del_len = name_len + sizeof(*ref);
 209
 210         key.objectid = inode_objectid;
 211         key.offset = ref_objectid;
 212         key.type = BTRFS_INODE_REF_KEY;
 213
 214         path = btrfs_alloc_path();
 215         if (!path)
 216                 return -ENOMEM;
 217
 218         path->leave_spinning = 1;
 219
 220         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 221         if (ret > 0) {
 222                 ret = -ENOENT;
 223                 search_ext_refs = 1;
 224                 goto out;
 225         } else if (ret < 0) {
 226                 goto out;
 227         }
 228         if (!find_name_in_backref(path, name, name_len, &ref)) {
 229                 ret = -ENOENT;
 230                 search_ext_refs = 1;
 231                 goto out;
 232         }
 233         leaf = path->nodes[0];
 234         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 235
 236         if (index)
 237                 *index = btrfs_inode_ref_index(leaf, ref);
 238
 239         if (del_len == item_size) {
 240                 ret = btrfs_del_item(trans, root, path);
 241                 goto out;
 242         }
 243         ptr = (unsigned long)ref;
 244         sub_item_len = name_len + sizeof(*ref);
 245         item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 246         memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 247                               item_size - (ptr + sub_item_len - item_start));
 248         btrfs_truncate_item(root, path, item_size - sub_item_len, 1);
 249 out:
 250         btrfs_free_path(path);
 251
 252         if (search_ext_refs) {
 253                 /*
 254                  * No refs were found, or we could not find the
 255                  * name in our ref array. Find and remove the extended
 256                  * inode ref then.
 257                  */
 258                 return btrfs_del_inode_extref(trans, root, name, name_len,
 259                                               inode_objectid, ref_objectid, index);
 260         }
 261
 262         return ret;
 263 }
 264
 265 /*
 266  * btrfs_insert_inode_extref() - Inserts an extended inode ref into a tree.
 267  *
 268  * The caller must have checked against BTRFS_LINK_MAX already.
 269  */
 270 static int btrfs_insert_inode_extref(struct btrfs_trans_handle *trans,
 271                                      struct btrfs_root *root,
 272                                      const char *name, int name_len,
 273                                      u64 inode_objectid, u64 ref_objectid, u64 index)
 274 {
 275         struct btrfs_inode_extref *extref;
 276         int ret;
 277         int ins_len = name_len + sizeof(*extref);
 278         unsigned long ptr;
 279         struct btrfs_path *path;
 280         struct btrfs_key key;
 281         struct extent_buffer *leaf;
 282         struct btrfs_item *item;
 283
 284         key.objectid = inode_objectid;
 285         key.type = BTRFS_INODE_EXTREF_KEY;
 286         key.offset = btrfs_extref_hash(ref_objectid, name, name_len);
 287
 288         path = btrfs_alloc_path();
 289         if (!path)
 290                 return -ENOMEM;
 291
 292         path->leave_spinning = 1;
 293         ret = btrfs_insert_empty_item(trans, root, path, &key,
 294                                       ins_len);
 295         if (ret == -EEXIST) {
 296                 if (btrfs_find_name_in_ext_backref(path, ref_objectid,
 297                                                    name, name_len, NULL))
 298                         goto out;
 299
 300                 btrfs_extend_item(root, path, ins_len);
 301                 ret = 0;
 302         }
 303         if (ret < 0)
 304                 goto out;
 305
 306         leaf = path->nodes[0];
 307         item = btrfs_item_nr(path->slots[0]);
 308         ptr = (unsigned long)btrfs_item_ptr(leaf, path->slots[0], char);
 309         ptr += btrfs_item_size(leaf, item) - ins_len;
 310         extref = (struct btrfs_inode_extref *)ptr;
 311
 312         btrfs_set_inode_extref_name_len(path->nodes[0], extref, name_len);
 313         btrfs_set_inode_extref_index(path->nodes[0], extref, index);
 314         btrfs_set_inode_extref_parent(path->nodes[0], extref, ref_objectid);
 315
 316         ptr = (unsigned long)&extref->name;
 317         write_extent_buffer(path->nodes[0], name, ptr, name_len);
 318         btrfs_mark_buffer_dirty(path->nodes[0]);
 319
 320 out:
 321         btrfs_free_path(path);
 322         return ret;
 323 }
 324
 325 /* Will return 0, -ENOMEM, -EMLINK, or -EEXIST or anything from the CoW path */
 326 int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
 327                            struct btrfs_root *root,
 328                            const char *name, int name_len,
 329                            u64 inode_objectid, u64 ref_objectid, u64 index)
 330 {
 331         struct btrfs_path *path;
 332         struct btrfs_key key;
 333         struct btrfs_inode_ref *ref;
 334         unsigned long ptr;
 335         int ret;
 336         int ins_len = name_len + sizeof(*ref);
 337
 338         key.objectid = inode_objectid;
 339         key.offset = ref_objectid;
 340         key.type = BTRFS_INODE_REF_KEY;
 341
 342         path = btrfs_alloc_path();
 343         if (!path)
 344                 return -ENOMEM;
 345
 346         path->leave_spinning = 1;
 347         path->skip_release_on_error = 1;
 348         ret = btrfs_insert_empty_item(trans, root, path, &key,
 349                                       ins_len);
 350         if (ret == -EEXIST) {
 351                 u32 old_size;
 352
 353                 if (find_name_in_backref(path, name, name_len, &ref))
 354                         goto out;
 355
 356                 old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
 357                 btrfs_extend_item(root, path, ins_len);
 358                 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 359                                      struct btrfs_inode_ref);
 360                 ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
 361                 btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
 362                 btrfs_set_inode_ref_index(path->nodes[0], ref, index);
 363                 ptr = (unsigned long)(ref + 1);
 364                 ret = 0;
 365         } else if (ret < 0) {
 366                 if (ret == -EOVERFLOW) {
 367                         if (find_name_in_backref(path, name, name_len, &ref))
 368                                 ret = -EEXIST;
 369                         else
 370                                 ret = -EMLINK;
 371                 }
 372                 goto out;
 373         } else {
 374                 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 375                                      struct btrfs_inode_ref);
 376                 btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
 377                 btrfs_set_inode_ref_index(path->nodes[0], ref, index);
 378                 ptr = (unsigned long)(ref + 1);
 379         }
 380         write_extent_buffer(path->nodes[0], name, ptr, name_len);
 381         btrfs_mark_buffer_dirty(path->nodes[0]);
 382
 383 out:
 384         btrfs_free_path(path);
 385
 386         if (ret == -EMLINK) {
 387                 struct btrfs_super_block *disk_super = root->fs_info->super_copy;
 388                 /* We ran out of space in the ref array. Need to
 389                  * add an extended ref. */
 390                 if (btrfs_super_incompat_flags(disk_super)
 391                     & BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
 392                         ret = btrfs_insert_inode_extref(trans, root, name,
 393                                                         name_len,
 394                                                         inode_objectid,
 395                                                         ref_objectid, index);
 396         }
 397
 398         return ret;
 399 }
 400
 401 int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
 402                              struct btrfs_root *root,
 403                              struct btrfs_path *path, u64 objectid)
 404 {
 405         struct btrfs_key key;
 406         int ret;
 407         key.objectid = objectid;
 408         key.type = BTRFS_INODE_ITEM_KEY;
 409         key.offset = 0;
 410
 411         ret = btrfs_insert_empty_item(trans, root, path, &key,
 412                                       sizeof(struct btrfs_inode_item));
 413         return ret;
 414 }
 415
 416 int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
 417                        *root, struct btrfs_path *path,
 418                        struct btrfs_key *location, int mod)
 419 {
 420         int ins_len = mod < 0 ? -1 : 0;
 421         int cow = mod != 0;
 422         int ret;
 423         int slot;
 424         struct extent_buffer *leaf;
 425         struct btrfs_key found_key;
 426
 427         ret = btrfs_search_slot(trans, root, location, path, ins_len, cow);
 428         if (ret > 0 && location->type == BTRFS_ROOT_ITEM_KEY &&
 429             location->offset == (u64)-1 && path->slots[0] != 0) {
 430                 slot = path->slots[0] - 1;
 431                 leaf = path->nodes[0];
 432                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 433                 if (found_key.objectid == location->objectid &&
 434                     found_key.type == location->type) {
 435                         path->slots[0]--;
 436                         return 0;
 437                 }
 438         }
 439         return ret;
 440 }