root/fs/btrfs/inode-item.c

DEFINITIONS

1. btrfs_find_name_in_backref
2. btrfs_find_name_in_ext_backref
3. btrfs_lookup_inode_extref
4. btrfs_del_inode_extref
5. btrfs_del_inode_ref
6. btrfs_insert_inode_extref
7. btrfs_insert_inode_ref
8. btrfs_insert_empty_inode
9. btrfs_lookup_inode

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5 
   6 #include "ctree.h"
   7 #include "disk-io.h"
   8 #include "transaction.h"
   9 #include "print-tree.h"
  10 
  11 struct btrfs_inode_ref *btrfs_find_name_in_backref(struct extent_buffer *leaf,
  12                                                    int slot, const char *name,
  13                                                    int name_len)
  14 {
  15         struct btrfs_inode_ref *ref;
  16         unsigned long ptr;
  17         unsigned long name_ptr;
  18         u32 item_size;
  19         u32 cur_offset = 0;
  20         int len;
  21 
  22         item_size = btrfs_item_size_nr(leaf, slot);
  23         ptr = btrfs_item_ptr_offset(leaf, slot);
  24         while (cur_offset < item_size) {
  25                 ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
  26                 len = btrfs_inode_ref_name_len(leaf, ref);
  27                 name_ptr = (unsigned long)(ref + 1);
  28                 cur_offset += len + sizeof(*ref);
  29                 if (len != name_len)
  30                         continue;
  31                 if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
  32                         return ref;
  33         }
  34         return NULL;
  35 }
  36 
  37 struct btrfs_inode_extref *btrfs_find_name_in_ext_backref(
  38                 struct extent_buffer *leaf, int slot, u64 ref_objectid,
  39                 const char *name, int name_len)
  40 {
  41         struct btrfs_inode_extref *extref;
  42         unsigned long ptr;
  43         unsigned long name_ptr;
  44         u32 item_size;
  45         u32 cur_offset = 0;
  46         int ref_name_len;
  47 
  48         item_size = btrfs_item_size_nr(leaf, slot);
  49         ptr = btrfs_item_ptr_offset(leaf, slot);
  50 
  51         /*
  52          * Search all extended backrefs in this item. We're only
  53          * looking through any collisions so most of the time this is
  54          * just going to compare against one buffer. If all is well,
  55          * we'll return success and the inode ref object.
  56          */
  57         while (cur_offset < item_size) {
  58                 extref = (struct btrfs_inode_extref *) (ptr + cur_offset);
  59                 name_ptr = (unsigned long)(&extref->name);
  60                 ref_name_len = btrfs_inode_extref_name_len(leaf, extref);
  61 
  62                 if (ref_name_len == name_len &&
  63                     btrfs_inode_extref_parent(leaf, extref) == ref_objectid &&
  64                     (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0))
  65                         return extref;
  66 
  67                 cur_offset += ref_name_len + sizeof(*extref);
  68         }
  69         return NULL;
  70 }
  71 
  72 /* Returns NULL if no extref found */
  73 struct btrfs_inode_extref *
  74 btrfs_lookup_inode_extref(struct btrfs_trans_handle *trans,
  75                           struct btrfs_root *root,
  76                           struct btrfs_path *path,
  77                           const char *name, int name_len,
  78                           u64 inode_objectid, u64 ref_objectid, int ins_len,
  79                           int cow)
  80 {
  81         int ret;
  82         struct btrfs_key key;
  83 
  84         key.objectid = inode_objectid;
  85         key.type = BTRFS_INODE_EXTREF_KEY;
  86         key.offset = btrfs_extref_hash(ref_objectid, name, name_len);
  87 
  88         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
  89         if (ret < 0)
  90                 return ERR_PTR(ret);
  91         if (ret > 0)
  92                 return NULL;
  93         return btrfs_find_name_in_ext_backref(path->nodes[0], path->slots[0],
  94                                               ref_objectid, name, name_len);
  95 
  96 }
  97 
  98 static int btrfs_del_inode_extref(struct btrfs_trans_handle *trans,
  99                                   struct btrfs_root *root,
 100                                   const char *name, int name_len,
 101                                   u64 inode_objectid, u64 ref_objectid,
 102                                   u64 *index)
 103 {
 104         struct btrfs_path *path;
 105         struct btrfs_key key;
 106         struct btrfs_inode_extref *extref;
 107         struct extent_buffer *leaf;
 108         int ret;
 109         int del_len = name_len + sizeof(*extref);
 110         unsigned long ptr;
 111         unsigned long item_start;
 112         u32 item_size;
 113 
 114         key.objectid = inode_objectid;
 115         key.type = BTRFS_INODE_EXTREF_KEY;
 116         key.offset = btrfs_extref_hash(ref_objectid, name, name_len);
 117 
 118         path = btrfs_alloc_path();
 119         if (!path)
 120                 return -ENOMEM;
 121 
 122         path->leave_spinning = 1;
 123 
 124         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 125         if (ret > 0)
 126                 ret = -ENOENT;
 127         if (ret < 0)
 128                 goto out;
 129 
 130         /*
 131          * Sanity check - did we find the right item for this name?
 132          * This should always succeed so error here will make the FS
 133          * readonly.
 134          */
 135         extref = btrfs_find_name_in_ext_backref(path->nodes[0], path->slots[0],
 136                                                 ref_objectid, name, name_len);
 137         if (!extref) {
 138                 btrfs_handle_fs_error(root->fs_info, -ENOENT, NULL);
 139                 ret = -EROFS;
 140                 goto out;
 141         }
 142 
 143         leaf = path->nodes[0];
 144         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 145         if (index)
 146                 *index = btrfs_inode_extref_index(leaf, extref);
 147 
 148         if (del_len == item_size) {
 149                 /*
 150                  * Common case only one ref in the item, remove the
 151                  * whole item.
 152                  */
 153                 ret = btrfs_del_item(trans, root, path);
 154                 goto out;
 155         }
 156 
 157         ptr = (unsigned long)extref;
 158         item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 159 
 160         memmove_extent_buffer(leaf, ptr, ptr + del_len,
 161                               item_size - (ptr + del_len - item_start));
 162 
 163         btrfs_truncate_item(path, item_size - del_len, 1);
 164 
 165 out:
 166         btrfs_free_path(path);
 167 
 168         return ret;
 169 }
 170 
 171 int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
 172                         struct btrfs_root *root,
 173                         const char *name, int name_len,
 174                         u64 inode_objectid, u64 ref_objectid, u64 *index)
 175 {
 176         struct btrfs_path *path;
 177         struct btrfs_key key;
 178         struct btrfs_inode_ref *ref;
 179         struct extent_buffer *leaf;
 180         unsigned long ptr;
 181         unsigned long item_start;
 182         u32 item_size;
 183         u32 sub_item_len;
 184         int ret;
 185         int search_ext_refs = 0;
 186         int del_len = name_len + sizeof(*ref);
 187 
 188         key.objectid = inode_objectid;
 189         key.offset = ref_objectid;
 190         key.type = BTRFS_INODE_REF_KEY;
 191 
 192         path = btrfs_alloc_path();
 193         if (!path)
 194                 return -ENOMEM;
 195 
 196         path->leave_spinning = 1;
 197 
 198         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 199         if (ret > 0) {
 200                 ret = -ENOENT;
 201                 search_ext_refs = 1;
 202                 goto out;
 203         } else if (ret < 0) {
 204                 goto out;
 205         }
 206 
 207         ref = btrfs_find_name_in_backref(path->nodes[0], path->slots[0], name,
 208                                          name_len);
 209         if (!ref) {
 210                 ret = -ENOENT;
 211                 search_ext_refs = 1;
 212                 goto out;
 213         }
 214         leaf = path->nodes[0];
 215         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 216 
 217         if (index)
 218                 *index = btrfs_inode_ref_index(leaf, ref);
 219 
 220         if (del_len == item_size) {
 221                 ret = btrfs_del_item(trans, root, path);
 222                 goto out;
 223         }
 224         ptr = (unsigned long)ref;
 225         sub_item_len = name_len + sizeof(*ref);
 226         item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 227         memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 228                               item_size - (ptr + sub_item_len - item_start));
 229         btrfs_truncate_item(path, item_size - sub_item_len, 1);
 230 out:
 231         btrfs_free_path(path);
 232 
 233         if (search_ext_refs) {
 234                 /*
 235                  * No refs were found, or we could not find the
 236                  * name in our ref array. Find and remove the extended
 237                  * inode ref then.
 238                  */
 239                 return btrfs_del_inode_extref(trans, root, name, name_len,
 240                                               inode_objectid, ref_objectid, index);
 241         }
 242 
 243         return ret;
 244 }
 245 
 246 /*
 247  * btrfs_insert_inode_extref() - Inserts an extended inode ref into a tree.
 248  *
 249  * The caller must have checked against BTRFS_LINK_MAX already.
 250  */
 251 static int btrfs_insert_inode_extref(struct btrfs_trans_handle *trans,
 252                                      struct btrfs_root *root,
 253                                      const char *name, int name_len,
 254                                      u64 inode_objectid, u64 ref_objectid, u64 index)
 255 {
 256         struct btrfs_inode_extref *extref;
 257         int ret;
 258         int ins_len = name_len + sizeof(*extref);
 259         unsigned long ptr;
 260         struct btrfs_path *path;
 261         struct btrfs_key key;
 262         struct extent_buffer *leaf;
 263         struct btrfs_item *item;
 264 
 265         key.objectid = inode_objectid;
 266         key.type = BTRFS_INODE_EXTREF_KEY;
 267         key.offset = btrfs_extref_hash(ref_objectid, name, name_len);
 268 
 269         path = btrfs_alloc_path();
 270         if (!path)
 271                 return -ENOMEM;
 272 
 273         path->leave_spinning = 1;
 274         ret = btrfs_insert_empty_item(trans, root, path, &key,
 275                                       ins_len);
 276         if (ret == -EEXIST) {
 277                 if (btrfs_find_name_in_ext_backref(path->nodes[0],
 278                                                    path->slots[0],
 279                                                    ref_objectid,
 280                                                    name, name_len))
 281                         goto out;
 282 
 283                 btrfs_extend_item(path, ins_len);
 284                 ret = 0;
 285         }
 286         if (ret < 0)
 287                 goto out;
 288 
 289         leaf = path->nodes[0];
 290         item = btrfs_item_nr(path->slots[0]);
 291         ptr = (unsigned long)btrfs_item_ptr(leaf, path->slots[0], char);
 292         ptr += btrfs_item_size(leaf, item) - ins_len;
 293         extref = (struct btrfs_inode_extref *)ptr;
 294 
 295         btrfs_set_inode_extref_name_len(path->nodes[0], extref, name_len);
 296         btrfs_set_inode_extref_index(path->nodes[0], extref, index);
 297         btrfs_set_inode_extref_parent(path->nodes[0], extref, ref_objectid);
 298 
 299         ptr = (unsigned long)&extref->name;
 300         write_extent_buffer(path->nodes[0], name, ptr, name_len);
 301         btrfs_mark_buffer_dirty(path->nodes[0]);
 302 
 303 out:
 304         btrfs_free_path(path);
 305         return ret;
 306 }
 307 
 308 /* Will return 0, -ENOMEM, -EMLINK, or -EEXIST or anything from the CoW path */
 309 int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
 310                            struct btrfs_root *root,
 311                            const char *name, int name_len,
 312                            u64 inode_objectid, u64 ref_objectid, u64 index)
 313 {
 314         struct btrfs_fs_info *fs_info = root->fs_info;
 315         struct btrfs_path *path;
 316         struct btrfs_key key;
 317         struct btrfs_inode_ref *ref;
 318         unsigned long ptr;
 319         int ret;
 320         int ins_len = name_len + sizeof(*ref);
 321 
 322         key.objectid = inode_objectid;
 323         key.offset = ref_objectid;
 324         key.type = BTRFS_INODE_REF_KEY;
 325 
 326         path = btrfs_alloc_path();
 327         if (!path)
 328                 return -ENOMEM;
 329 
 330         path->leave_spinning = 1;
 331         path->skip_release_on_error = 1;
 332         ret = btrfs_insert_empty_item(trans, root, path, &key,
 333                                       ins_len);
 334         if (ret == -EEXIST) {
 335                 u32 old_size;
 336                 ref = btrfs_find_name_in_backref(path->nodes[0], path->slots[0],
 337                                                  name, name_len);
 338                 if (ref)
 339                         goto out;
 340 
 341                 old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
 342                 btrfs_extend_item(path, ins_len);
 343                 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 344                                      struct btrfs_inode_ref);
 345                 ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
 346                 btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
 347                 btrfs_set_inode_ref_index(path->nodes[0], ref, index);
 348                 ptr = (unsigned long)(ref + 1);
 349                 ret = 0;
 350         } else if (ret < 0) {
 351                 if (ret == -EOVERFLOW) {
 352                         if (btrfs_find_name_in_backref(path->nodes[0],
 353                                                        path->slots[0],
 354                                                        name, name_len))
 355                                 ret = -EEXIST;
 356                         else
 357                                 ret = -EMLINK;
 358                 }
 359                 goto out;
 360         } else {
 361                 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 362                                      struct btrfs_inode_ref);
 363                 btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
 364                 btrfs_set_inode_ref_index(path->nodes[0], ref, index);
 365                 ptr = (unsigned long)(ref + 1);
 366         }
 367         write_extent_buffer(path->nodes[0], name, ptr, name_len);
 368         btrfs_mark_buffer_dirty(path->nodes[0]);
 369 
 370 out:
 371         btrfs_free_path(path);
 372 
 373         if (ret == -EMLINK) {
 374                 struct btrfs_super_block *disk_super = fs_info->super_copy;
 375                 /* We ran out of space in the ref array. Need to
 376                  * add an extended ref. */
 377                 if (btrfs_super_incompat_flags(disk_super)
 378                     & BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
 379                         ret = btrfs_insert_inode_extref(trans, root, name,
 380                                                         name_len,
 381                                                         inode_objectid,
 382                                                         ref_objectid, index);
 383         }
 384 
 385         return ret;
 386 }
 387 
 388 int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
 389                              struct btrfs_root *root,
 390                              struct btrfs_path *path, u64 objectid)
 391 {
 392         struct btrfs_key key;
 393         int ret;
 394         key.objectid = objectid;
 395         key.type = BTRFS_INODE_ITEM_KEY;
 396         key.offset = 0;
 397 
 398         ret = btrfs_insert_empty_item(trans, root, path, &key,
 399                                       sizeof(struct btrfs_inode_item));
 400         return ret;
 401 }
 402 
 403 int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
 404                        *root, struct btrfs_path *path,
 405                        struct btrfs_key *location, int mod)
 406 {
 407         int ins_len = mod < 0 ? -1 : 0;
 408         int cow = mod != 0;
 409         int ret;
 410         int slot;
 411         struct extent_buffer *leaf;
 412         struct btrfs_key found_key;
 413 
 414         ret = btrfs_search_slot(trans, root, location, path, ins_len, cow);
 415         if (ret > 0 && location->type == BTRFS_ROOT_ITEM_KEY &&
 416             location->offset == (u64)-1 && path->slots[0] != 0) {
 417                 slot = path->slots[0] - 1;
 418                 leaf = path->nodes[0];
 419                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 420                 if (found_key.objectid == location->objectid &&
 421                     found_key.type == location->type) {
 422                         path->slots[0]--;
 423                         return 0;
 424                 }
 425         }
 426         return ret;
 427 }