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