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                 pr_warn("btrfs: uuid item with illegal size %lu!\n",
  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
  88 out:
  89         btrfs_free_path(path);
  90         return ret;
  91 }
  92
  93 int 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                 pr_warn("btrfs: insert uuid item failed %d (0x%016llx, 0x%016llx) type %u!\n",
 141                         ret, (unsigned long long)key.objectid,
 142                         (unsigned long long)key.offset, type);
 143                 goto out;
 144         }
 145
 146         ret = 0;
 147         subid_le = cpu_to_le64(subid_cpu);
 148         write_extent_buffer(eb, &subid_le, offset, sizeof(subid_le));
 149         btrfs_mark_buffer_dirty(eb);
 150
 151 out:
 152         btrfs_free_path(path);
 153         return ret;
 154 }
 155
 156 int btrfs_uuid_tree_rem(struct btrfs_trans_handle *trans,
 157                         struct btrfs_root *uuid_root, u8 *uuid, u8 type,
 158                         u64 subid)
 159 {
 160         int ret;
 161         struct btrfs_path *path = NULL;
 162         struct btrfs_key key;
 163         struct extent_buffer *eb;
 164         int slot;
 165         unsigned long offset;
 166         u32 item_size;
 167         unsigned long move_dst;
 168         unsigned long move_src;
 169         unsigned long move_len;
 170
 171         if (WARN_ON_ONCE(!uuid_root)) {
 172                 ret = -EINVAL;
 173                 goto out;
 174         }
 175
 176         btrfs_uuid_to_key(uuid, type, &key);
 177
 178         path = btrfs_alloc_path();
 179         if (!path) {
 180                 ret = -ENOMEM;
 181                 goto out;
 182         }
 183
 184         ret = btrfs_search_slot(trans, uuid_root, &key, path, -1, 1);
 185         if (ret < 0) {
 186                 pr_warn("btrfs: error %d while searching for uuid item!\n",
 187                         ret);
 188                 goto out;
 189         }
 190         if (ret > 0) {
 191                 ret = -ENOENT;
 192                 goto out;
 193         }
 194
 195         eb = path->nodes[0];
 196         slot = path->slots[0];
 197         offset = btrfs_item_ptr_offset(eb, slot);
 198         item_size = btrfs_item_size_nr(eb, slot);
 199         if (!IS_ALIGNED(item_size, sizeof(u64))) {
 200                 pr_warn("btrfs: uuid item with illegal size %lu!\n",
 201                         (unsigned long)item_size);
 202                 ret = -ENOENT;
 203                 goto out;
 204         }
 205         while (item_size) {
 206                 __le64 read_subid;
 207
 208                 read_extent_buffer(eb, &read_subid, offset, sizeof(read_subid));
 209                 if (le64_to_cpu(read_subid) == subid)
 210                         break;
 211                 offset += sizeof(read_subid);
 212                 item_size -= sizeof(read_subid);
 213         }
 214
 215         if (!item_size) {
 216                 ret = -ENOENT;
 217                 goto out;
 218         }
 219
 220         item_size = btrfs_item_size_nr(eb, slot);
 221         if (item_size == sizeof(subid)) {
 222                 ret = btrfs_del_item(trans, uuid_root, path);
 223                 goto out;
 224         }
 225
 226         move_dst = offset;
 227         move_src = offset + sizeof(subid);
 228         move_len = item_size - (move_src - btrfs_item_ptr_offset(eb, slot));
 229         memmove_extent_buffer(eb, move_dst, move_src, move_len);
 230         btrfs_truncate_item(uuid_root, path, item_size - sizeof(subid), 1);
 231
 232 out:
 233         btrfs_free_path(path);
 234         return ret;
 235 }
 236
 237 static int btrfs_uuid_iter_rem(struct btrfs_root *uuid_root, u8 *uuid, u8 type,
 238                                u64 subid)
 239 {
 240         struct btrfs_trans_handle *trans;
 241         int ret;
 242
 243         /* 1 - for the uuid item */
 244         trans = btrfs_start_transaction(uuid_root, 1);
 245         if (IS_ERR(trans)) {
 246                 ret = PTR_ERR(trans);
 247                 goto out;
 248         }
 249
 250         ret = btrfs_uuid_tree_rem(trans, uuid_root, uuid, type, subid);
 251         btrfs_end_transaction(trans, uuid_root);
 252
 253 out:
 254         return ret;
 255 }
 256
 257 int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info,
 258                             int (*check_func)(struct btrfs_fs_info *, u8 *, u8,
 259                                               u64))
 260 {
 261         struct btrfs_root *root = fs_info->uuid_root;
 262         struct btrfs_key key;
 263         struct btrfs_path *path;
 264         int ret = 0;
 265         struct extent_buffer *leaf;
 266         int slot;
 267         u32 item_size;
 268         unsigned long offset;
 269
 270         path = btrfs_alloc_path();
 271         if (!path) {
 272                 ret = -ENOMEM;
 273                 goto out;
 274         }
 275
 276         key.objectid = 0;
 277         key.type = 0;
 278         key.offset = 0;
 279
 280 again_search_slot:
 281         path->keep_locks = 1;
 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                         pr_warn("btrfs: uuid item with illegal size %lu!\n",
 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
 340 skip:
 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
 349 out:
 350         btrfs_free_path(path);
 351         if (ret)
 352                 pr_warn("btrfs: btrfs_uuid_tree_iterate failed %d\n", ret);
 353         return 0;
 354 }