fs/btrfs/uuid-tree.c

   1 /*
   2  * Copyright (C) STRATO AG 2013.  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 #include <linux/uuid.h>
  19 #include <asm/unaligned.h>
  20 #include "ctree.h"
  21 #include "transaction.h"
  22 #include "disk-io.h"
  23 #include "print-tree.h"
  24
  25
  26 static void btrfs_uuid_to_key(u8 *uuid, u8 type, struct btrfs_key *key)
  27 {
  28         key->type = type;
  29         key->objectid = get_unaligned_le64(uuid);
  30         key->offset = get_unaligned_le64(uuid + sizeof(u64));
  31 }
  32
  33 /* return -ENOENT for !found, < 0 for errors, or 0 if an item was found */
  34 static int btrfs_uuid_tree_lookup(struct btrfs_root *uuid_root, u8 *uuid,
  35                                   u8 type, u64 subid)
  36 {
  37         int ret;
  38         struct btrfs_path *path = NULL;
  39         struct extent_buffer *eb;
  40         int slot;
  41         u32 item_size;
  42         unsigned long offset;
  43         struct btrfs_key key;
  44
  45         if (WARN_ON_ONCE(!uuid_root)) {
  46                 ret = -ENOENT;
  47                 goto out;
  48         }
  49
  50         path = btrfs_alloc_path();
  51         if (!path) {
  52                 ret = -ENOMEM;
  53                 goto out;
  54         }
  55
  56         btrfs_uuid_to_key(uuid, type, &key);
  57         ret = btrfs_search_slot(NULL, uuid_root, &key, path, 0, 0);
  58         if (ret < 0) {
  59                 goto out;
  60         } else if (ret > 0) {
  61                 ret = -ENOENT;
  62                 goto out;
  63         }
  64
  65         eb = path->nodes[0];
  66         slot = path->slots[0];
  67         item_size = btrfs_item_size_nr(eb, slot);
  68         offset = btrfs_item_ptr_offset(eb, slot);
  69         ret = -ENOENT;
  70
  71         if (!IS_ALIGNED(item_size, sizeof(u64))) {
  72                 btrfs_warn(uuid_root->fs_info,
  73                            "uuid item with illegal size %lu!",
  74                            (unsigned long)item_size);
  75                 goto out;
  76         }
  77         while (item_size) {
  78                 __le64 data;
  79
  80                 read_extent_buffer(eb, &data, offset, sizeof(data));
  81                 if (le64_to_cpu(data) == subid) {
  82                         ret = 0;
  83                         break;
  84                 }
  85                 offset += sizeof(data);
  86                 item_size -= sizeof(data);
  87         }
  88
  89 out:
  90         btrfs_free_path(path);
  91         return ret;
  92 }
  93
  94 int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans,
  95                         struct btrfs_root *uuid_root, u8 *uuid, u8 type,
  96                         u64 subid_cpu)
  97 {
  98         int ret;
  99         struct btrfs_path *path = NULL;
 100         struct btrfs_key key;
 101         struct extent_buffer *eb;
 102         int slot;
 103         unsigned long offset;
 104         __le64 subid_le;
 105
 106         ret = btrfs_uuid_tree_lookup(uuid_root, uuid, type, subid_cpu);
 107         if (ret != -ENOENT)
 108                 return ret;
 109
 110         if (WARN_ON_ONCE(!uuid_root)) {
 111                 ret = -EINVAL;
 112                 goto out;
 113         }
 114
 115         btrfs_uuid_to_key(uuid, type, &key);
 116
 117         path = btrfs_alloc_path();
 118         if (!path) {
 119                 ret = -ENOMEM;
 120                 goto out;
 121         }
 122
 123         ret = btrfs_insert_empty_item(trans, uuid_root, path, &key,
 124                                       sizeof(subid_le));
 125         if (ret >= 0) {
 126                 /* Add an item for the type for the first time */
 127                 eb = path->nodes[0];
 128                 slot = path->slots[0];
 129                 offset = btrfs_item_ptr_offset(eb, slot);
 130         } else if (ret == -EEXIST) {
 131                 /*
 132                  * An item with that type already exists.
 133                  * Extend the item and store the new subid at the end.
 134                  */
 135                 btrfs_extend_item(uuid_root, path, sizeof(subid_le));
 136                 eb = path->nodes[0];
 137                 slot = path->slots[0];
 138                 offset = btrfs_item_ptr_offset(eb, slot);
 139                 offset += btrfs_item_size_nr(eb, slot) - sizeof(subid_le);
 140         } else if (ret < 0) {
 141                 btrfs_warn(uuid_root->fs_info,
 142                            "insert uuid item failed %d (0x%016llx, 0x%016llx) type %u!",
 143                            ret, (unsigned long long)key.objectid,
 144                            (unsigned long long)key.offset, type);
 145                 goto out;
 146         }
 147
 148         ret = 0;
 149         subid_le = cpu_to_le64(subid_cpu);
 150         write_extent_buffer(eb, &subid_le, offset, sizeof(subid_le));
 151         btrfs_mark_buffer_dirty(eb);
 152
 153 out:
 154         btrfs_free_path(path);
 155         return ret;
 156 }
 157
 158 int btrfs_uuid_tree_rem(struct btrfs_trans_handle *trans,
 159                         struct btrfs_root *uuid_root, u8 *uuid, u8 type,
 160                         u64 subid)
 161 {
 162         int ret;
 163         struct btrfs_path *path = NULL;
 164         struct btrfs_key key;
 165         struct extent_buffer *eb;
 166         int slot;
 167         unsigned long offset;
 168         u32 item_size;
 169         unsigned long move_dst;
 170         unsigned long move_src;
 171         unsigned long move_len;
 172
 173         if (WARN_ON_ONCE(!uuid_root)) {
 174                 ret = -EINVAL;
 175                 goto out;
 176         }
 177
 178         btrfs_uuid_to_key(uuid, type, &key);
 179
 180         path = btrfs_alloc_path();
 181         if (!path) {
 182                 ret = -ENOMEM;
 183                 goto out;
 184         }
 185
 186         ret = btrfs_search_slot(trans, uuid_root, &key, path, -1, 1);
 187         if (ret < 0) {
 188                 btrfs_warn(uuid_root->fs_info,
 189                            "error %d while searching for uuid item!", ret);
 190                 goto out;
 191         }
 192         if (ret > 0) {
 193                 ret = -ENOENT;
 194                 goto out;
 195         }
 196
 197         eb = path->nodes[0];
 198         slot = path->slots[0];
 199         offset = btrfs_item_ptr_offset(eb, slot);
 200         item_size = btrfs_item_size_nr(eb, slot);
 201         if (!IS_ALIGNED(item_size, sizeof(u64))) {
 202                 btrfs_warn(uuid_root->fs_info,
 203                            "uuid item with illegal size %lu!",
 204                            (unsigned long)item_size);
 205                 ret = -ENOENT;
 206                 goto out;
 207         }
 208         while (item_size) {
 209                 __le64 read_subid;
 210
 211                 read_extent_buffer(eb, &read_subid, offset, sizeof(read_subid));
 212                 if (le64_to_cpu(read_subid) == subid)
 213                         break;
 214                 offset += sizeof(read_subid);
 215                 item_size -= sizeof(read_subid);
 216         }
 217
 218         if (!item_size) {
 219                 ret = -ENOENT;
 220                 goto out;
 221         }
 222
 223         item_size = btrfs_item_size_nr(eb, slot);
 224         if (item_size == sizeof(subid)) {
 225                 ret = btrfs_del_item(trans, uuid_root, path);
 226                 goto out;
 227         }
 228
 229         move_dst = offset;
 230         move_src = offset + sizeof(subid);
 231         move_len = item_size - (move_src - btrfs_item_ptr_offset(eb, slot));
 232         memmove_extent_buffer(eb, move_dst, move_src, move_len);
 233         btrfs_truncate_item(uuid_root, path, item_size - sizeof(subid), 1);
 234
 235 out:
 236         btrfs_free_path(path);
 237         return ret;
 238 }
 239
 240 static int btrfs_uuid_iter_rem(struct btrfs_root *uuid_root, u8 *uuid, u8 type,
 241                                u64 subid)
 242 {
 243         struct btrfs_trans_handle *trans;
 244         int ret;
 245
 246         /* 1 - for the uuid item */
 247         trans = btrfs_start_transaction(uuid_root, 1);
 248         if (IS_ERR(trans)) {
 249                 ret = PTR_ERR(trans);
 250                 goto out;
 251         }
 252
 253         ret = btrfs_uuid_tree_rem(trans, uuid_root, uuid, type, subid);
 254         btrfs_end_transaction(trans, uuid_root);
 255
 256 out:
 257         return ret;
 258 }
 259
 260 int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info,
 261                             int (*check_func)(struct btrfs_fs_info *, u8 *, u8,
 262                                               u64))
 263 {
 264         struct btrfs_root *root = fs_info->uuid_root;
 265         struct btrfs_key key;
 266         struct btrfs_path *path;
 267         int ret = 0;
 268         struct extent_buffer *leaf;
 269         int slot;
 270         u32 item_size;
 271         unsigned long offset;
 272
 273         path = btrfs_alloc_path();
 274         if (!path) {
 275                 ret = -ENOMEM;
 276                 goto out;
 277         }
 278
 279         key.objectid = 0;
 280         key.type = 0;
 281         key.offset = 0;
 282
 283 again_search_slot:
 284         ret = btrfs_search_forward(root, &key, path, 0);
 285         if (ret) {
 286                 if (ret > 0)
 287                         ret = 0;
 288                 goto out;
 289         }
 290
 291         while (1) {
 292                 cond_resched();
 293                 leaf = path->nodes[0];
 294                 slot = path->slots[0];
 295                 btrfs_item_key_to_cpu(leaf, &key, slot);
 296
 297                 if (key.type != BTRFS_UUID_KEY_SUBVOL &&
 298                     key.type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
 299                         goto skip;
 300
 301                 offset = btrfs_item_ptr_offset(leaf, slot);
 302                 item_size = btrfs_item_size_nr(leaf, slot);
 303                 if (!IS_ALIGNED(item_size, sizeof(u64))) {
 304                         btrfs_warn(fs_info,
 305                                    "uuid item with illegal size %lu!",
 306                                    (unsigned long)item_size);
 307                         goto skip;
 308                 }
 309                 while (item_size) {
 310                         u8 uuid[BTRFS_UUID_SIZE];
 311                         __le64 subid_le;
 312                         u64 subid_cpu;
 313
 314                         put_unaligned_le64(key.objectid, uuid);
 315                         put_unaligned_le64(key.offset, uuid + sizeof(u64));
 316                         read_extent_buffer(leaf, &subid_le, offset,
 317                                            sizeof(subid_le));
 318                         subid_cpu = le64_to_cpu(subid_le);
 319                         ret = check_func(fs_info, uuid, key.type, subid_cpu);
 320                         if (ret < 0)
 321                                 goto out;
 322                         if (ret > 0) {
 323                                 btrfs_release_path(path);
 324                                 ret = btrfs_uuid_iter_rem(root, uuid, key.type,
 325                                                           subid_cpu);
 326                                 if (ret == 0) {
 327                                         /*
 328                                          * this might look inefficient, but the
 329                                          * justification is that it is an
 330                                          * exception that check_func returns 1,
 331                                          * and that in the regular case only one
 332                                          * entry per UUID exists.
 333                                          */
 334                                         goto again_search_slot;
 335                                 }
 336                                 if (ret < 0 && ret != -ENOENT)
 337                                         goto out;
 338                         }
 339                         item_size -= sizeof(subid_le);
 340                         offset += sizeof(subid_le);
 341                 }
 342
 343 skip:
 344                 ret = btrfs_next_item(root, path);
 345                 if (ret == 0)
 346                         continue;
 347                 else if (ret > 0)
 348                         ret = 0;
 349                 break;
 350         }
 351
 352 out:
 353         btrfs_free_path(path);
 354         if (ret)
 355                 btrfs_warn(fs_info, "btrfs_uuid_tree_iterate failed %d", ret);
 356         return 0;
 357 }