fs/btrfs/uuid-tree.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) STRATO AG 2013.  All rights reserved.
   4  */
   5
   6 #include <linux/uuid.h>
   7 #include <asm/unaligned.h>
   8 #include "ctree.h"
   9 #include "transaction.h"
  10 #include "disk-io.h"
  11 #include "print-tree.h"
  12
  13
  14 static void btrfs_uuid_to_key(u8 *uuid, u8 type, struct btrfs_key *key)
  15 {
  16         key->type = type;
  17         key->objectid = get_unaligned_le64(uuid);
  18         key->offset = get_unaligned_le64(uuid + sizeof(u64));
  19 }
  20
  21 /* return -ENOENT for !found, < 0 for errors, or 0 if an item was found */
  22 static int btrfs_uuid_tree_lookup(struct btrfs_root *uuid_root, u8 *uuid,
  23                                   u8 type, u64 subid)
  24 {
  25         int ret;
  26         struct btrfs_path *path = NULL;
  27         struct extent_buffer *eb;
  28         int slot;
  29         u32 item_size;
  30         unsigned long offset;
  31         struct btrfs_key key;
  32
  33         if (WARN_ON_ONCE(!uuid_root)) {
  34                 ret = -ENOENT;
  35                 goto out;
  36         }
  37
  38         path = btrfs_alloc_path();
  39         if (!path) {
  40                 ret = -ENOMEM;
  41                 goto out;
  42         }
  43
  44         btrfs_uuid_to_key(uuid, type, &key);
  45         ret = btrfs_search_slot(NULL, uuid_root, &key, path, 0, 0);
  46         if (ret < 0) {
  47                 goto out;
  48         } else if (ret > 0) {
  49                 ret = -ENOENT;
  50                 goto out;
  51         }
  52
  53         eb = path->nodes[0];
  54         slot = path->slots[0];
  55         item_size = btrfs_item_size_nr(eb, slot);
  56         offset = btrfs_item_ptr_offset(eb, slot);
  57         ret = -ENOENT;
  58
  59         if (!IS_ALIGNED(item_size, sizeof(u64))) {
  60                 btrfs_warn(uuid_root->fs_info,
  61                            "uuid item with illegal size %lu!",
  62                            (unsigned long)item_size);
  63                 goto out;
  64         }
  65         while (item_size) {
  66                 __le64 data;
  67
  68                 read_extent_buffer(eb, &data, offset, sizeof(data));
  69                 if (le64_to_cpu(data) == subid) {
  70                         ret = 0;
  71                         break;
  72                 }
  73                 offset += sizeof(data);
  74                 item_size -= sizeof(data);
  75         }
  76
  77 out:
  78         btrfs_free_path(path);
  79         return ret;
  80 }
  81
  82 int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans, u8 *uuid, u8 type,
  83                         u64 subid_cpu)
  84 {
  85         struct btrfs_fs_info *fs_info = trans->fs_info;
  86         struct btrfs_root *uuid_root = fs_info->uuid_root;
  87         int ret;
  88         struct btrfs_path *path = NULL;
  89         struct btrfs_key key;
  90         struct extent_buffer *eb;
  91         int slot;
  92         unsigned long offset;
  93         __le64 subid_le;
  94
  95         ret = btrfs_uuid_tree_lookup(uuid_root, uuid, type, subid_cpu);
  96         if (ret != -ENOENT)
  97                 return ret;
  98
  99         if (WARN_ON_ONCE(!uuid_root)) {
 100                 ret = -EINVAL;
 101                 goto out;
 102         }
 103
 104         btrfs_uuid_to_key(uuid, type, &key);
 105
 106         path = btrfs_alloc_path();
 107         if (!path) {
 108                 ret = -ENOMEM;
 109                 goto out;
 110         }
 111
 112         ret = btrfs_insert_empty_item(trans, uuid_root, path, &key,
 113                                       sizeof(subid_le));
 114         if (ret >= 0) {
 115                 /* Add an item for the type for the first time */
 116                 eb = path->nodes[0];
 117                 slot = path->slots[0];
 118                 offset = btrfs_item_ptr_offset(eb, slot);
 119         } else if (ret == -EEXIST) {
 120                 /*
 121                  * An item with that type already exists.
 122                  * Extend the item and store the new subid at the end.
 123                  */
 124                 btrfs_extend_item(path, sizeof(subid_le));
 125                 eb = path->nodes[0];
 126                 slot = path->slots[0];
 127                 offset = btrfs_item_ptr_offset(eb, slot);
 128                 offset += btrfs_item_size_nr(eb, slot) - sizeof(subid_le);
 129         } else {
 130                 btrfs_warn(fs_info,
 131                            "insert uuid item failed %d (0x%016llx, 0x%016llx) type %u!",
 132                            ret, key.objectid, key.offset, type);
 133                 goto out;
 134         }
 135
 136         ret = 0;
 137         subid_le = cpu_to_le64(subid_cpu);
 138         write_extent_buffer(eb, &subid_le, offset, sizeof(subid_le));
 139         btrfs_mark_buffer_dirty(eb);
 140
 141 out:
 142         btrfs_free_path(path);
 143         return ret;
 144 }
 145
 146 int btrfs_uuid_tree_remove(struct btrfs_trans_handle *trans, u8 *uuid, u8 type,
 147                         u64 subid)
 148 {
 149         struct btrfs_fs_info *fs_info = trans->fs_info;
 150         struct btrfs_root *uuid_root = fs_info->uuid_root;
 151         int ret;
 152         struct btrfs_path *path = NULL;
 153         struct btrfs_key key;
 154         struct extent_buffer *eb;
 155         int slot;
 156         unsigned long offset;
 157         u32 item_size;
 158         unsigned long move_dst;
 159         unsigned long move_src;
 160         unsigned long move_len;
 161
 162         if (WARN_ON_ONCE(!uuid_root)) {
 163                 ret = -EINVAL;
 164                 goto out;
 165         }
 166
 167         btrfs_uuid_to_key(uuid, type, &key);
 168
 169         path = btrfs_alloc_path();
 170         if (!path) {
 171                 ret = -ENOMEM;
 172                 goto out;
 173         }
 174
 175         ret = btrfs_search_slot(trans, uuid_root, &key, path, -1, 1);
 176         if (ret < 0) {
 177                 btrfs_warn(fs_info, "error %d while searching for uuid item!",
 178                            ret);
 179                 goto out;
 180         }
 181         if (ret > 0) {
 182                 ret = -ENOENT;
 183                 goto out;
 184         }
 185
 186         eb = path->nodes[0];
 187         slot = path->slots[0];
 188         offset = btrfs_item_ptr_offset(eb, slot);
 189         item_size = btrfs_item_size_nr(eb, slot);
 190         if (!IS_ALIGNED(item_size, sizeof(u64))) {
 191                 btrfs_warn(fs_info, "uuid item with illegal size %lu!",
 192                            (unsigned long)item_size);
 193                 ret = -ENOENT;
 194                 goto out;
 195         }
 196         while (item_size) {
 197                 __le64 read_subid;
 198
 199                 read_extent_buffer(eb, &read_subid, offset, sizeof(read_subid));
 200                 if (le64_to_cpu(read_subid) == subid)
 201                         break;
 202                 offset += sizeof(read_subid);
 203                 item_size -= sizeof(read_subid);
 204         }
 205
 206         if (!item_size) {
 207                 ret = -ENOENT;
 208                 goto out;
 209         }
 210
 211         item_size = btrfs_item_size_nr(eb, slot);
 212         if (item_size == sizeof(subid)) {
 213                 ret = btrfs_del_item(trans, uuid_root, path);
 214                 goto out;
 215         }
 216
 217         move_dst = offset;
 218         move_src = offset + sizeof(subid);
 219         move_len = item_size - (move_src - btrfs_item_ptr_offset(eb, slot));
 220         memmove_extent_buffer(eb, move_dst, move_src, move_len);
 221         btrfs_truncate_item(path, item_size - sizeof(subid), 1);
 222
 223 out:
 224         btrfs_free_path(path);
 225         return ret;
 226 }
 227
 228 static int btrfs_uuid_iter_rem(struct btrfs_root *uuid_root, u8 *uuid, u8 type,
 229                                u64 subid)
 230 {
 231         struct btrfs_trans_handle *trans;
 232         int ret;
 233
 234         /* 1 - for the uuid item */
 235         trans = btrfs_start_transaction(uuid_root, 1);
 236         if (IS_ERR(trans)) {
 237                 ret = PTR_ERR(trans);
 238                 goto out;
 239         }
 240
 241         ret = btrfs_uuid_tree_remove(trans, uuid, type, subid);
 242         btrfs_end_transaction(trans);
 243
 244 out:
 245         return ret;
 246 }
 247
 248 /*
 249  * Check if there's an matching subvolume for given UUID
 250  *
 251  * Return:
 252  * 0    check succeeded, the entry is not outdated
 253  * > 0  if the check failed, the caller should remove the entry
 254  * < 0  if an error occurred
 255  */
 256 static int btrfs_check_uuid_tree_entry(struct btrfs_fs_info *fs_info,
 257                                        u8 *uuid, u8 type, u64 subvolid)
 258 {
 259         int ret = 0;
 260         struct btrfs_root *subvol_root;
 261
 262         if (type != BTRFS_UUID_KEY_SUBVOL &&
 263             type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
 264                 goto out;
 265
 266         subvol_root = btrfs_get_fs_root(fs_info, subvolid, true);
 267         if (IS_ERR(subvol_root)) {
 268                 ret = PTR_ERR(subvol_root);
 269                 if (ret == -ENOENT)
 270                         ret = 1;
 271                 goto out;
 272         }
 273
 274         switch (type) {
 275         case BTRFS_UUID_KEY_SUBVOL:
 276                 if (memcmp(uuid, subvol_root->root_item.uuid, BTRFS_UUID_SIZE))
 277                         ret = 1;
 278                 break;
 279         case BTRFS_UUID_KEY_RECEIVED_SUBVOL:
 280                 if (memcmp(uuid, subvol_root->root_item.received_uuid,
 281                            BTRFS_UUID_SIZE))
 282                         ret = 1;
 283                 break;
 284         }
 285         btrfs_put_root(subvol_root);
 286 out:
 287         return ret;
 288 }
 289
 290 int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info)
 291 {
 292         struct btrfs_root *root = fs_info->uuid_root;
 293         struct btrfs_key key;
 294         struct btrfs_path *path;
 295         int ret = 0;
 296         struct extent_buffer *leaf;
 297         int slot;
 298         u32 item_size;
 299         unsigned long offset;
 300
 301         path = btrfs_alloc_path();
 302         if (!path) {
 303                 ret = -ENOMEM;
 304                 goto out;
 305         }
 306
 307         key.objectid = 0;
 308         key.type = 0;
 309         key.offset = 0;
 310
 311 again_search_slot:
 312         ret = btrfs_search_forward(root, &key, path, BTRFS_OLDEST_GENERATION);
 313         if (ret) {
 314                 if (ret > 0)
 315                         ret = 0;
 316                 goto out;
 317         }
 318
 319         while (1) {
 320                 if (btrfs_fs_closing(fs_info)) {
 321                         ret = -EINTR;
 322                         goto out;
 323                 }
 324                 cond_resched();
 325                 leaf = path->nodes[0];
 326                 slot = path->slots[0];
 327                 btrfs_item_key_to_cpu(leaf, &key, slot);
 328
 329                 if (key.type != BTRFS_UUID_KEY_SUBVOL &&
 330                     key.type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
 331                         goto skip;
 332
 333                 offset = btrfs_item_ptr_offset(leaf, slot);
 334                 item_size = btrfs_item_size_nr(leaf, slot);
 335                 if (!IS_ALIGNED(item_size, sizeof(u64))) {
 336                         btrfs_warn(fs_info,
 337                                    "uuid item with illegal size %lu!",
 338                                    (unsigned long)item_size);
 339                         goto skip;
 340                 }
 341                 while (item_size) {
 342                         u8 uuid[BTRFS_UUID_SIZE];
 343                         __le64 subid_le;
 344                         u64 subid_cpu;
 345
 346                         put_unaligned_le64(key.objectid, uuid);
 347                         put_unaligned_le64(key.offset, uuid + sizeof(u64));
 348                         read_extent_buffer(leaf, &subid_le, offset,
 349                                            sizeof(subid_le));
 350                         subid_cpu = le64_to_cpu(subid_le);
 351                         ret = btrfs_check_uuid_tree_entry(fs_info, uuid,
 352                                                           key.type, subid_cpu);
 353                         if (ret < 0)
 354                                 goto out;
 355                         if (ret > 0) {
 356                                 btrfs_release_path(path);
 357                                 ret = btrfs_uuid_iter_rem(root, uuid, key.type,
 358                                                           subid_cpu);
 359                                 if (ret == 0) {
 360                                         /*
 361                                          * this might look inefficient, but the
 362                                          * justification is that it is an
 363                                          * exception that check_func returns 1,
 364                                          * and that in the regular case only one
 365                                          * entry per UUID exists.
 366                                          */
 367                                         goto again_search_slot;
 368                                 }
 369                                 if (ret < 0 && ret != -ENOENT)
 370                                         goto out;
 371                                 key.offset++;
 372                                 goto again_search_slot;
 373                         }
 374                         item_size -= sizeof(subid_le);
 375                         offset += sizeof(subid_le);
 376                 }
 377
 378 skip:
 379                 ret = btrfs_next_item(root, path);
 380                 if (ret == 0)
 381                         continue;
 382                 else if (ret > 0)
 383                         ret = 0;
 384                 break;
 385         }
 386
 387 out:
 388         btrfs_free_path(path);
 389         return ret;
 390 }