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