+/*
+ * this will find the highest generation in the array of
+ * root backups. The index of the highest array is returned,
+ * or -1 if we can't find anything.
+ *
+ * We check to make sure the array is valid by comparing the
+ * generation of the latest root in the array with the generation
+ * in the super block. If they don't match we pitch it.
+ */
+static int find_newest_super_backup(struct btrfs_fs_info *info, u64 newest_gen)
+{
+ u64 cur;
+ int newest_index = -1;
+ struct btrfs_root_backup *root_backup;
+ int i;
+
+ for (i = 0; i < BTRFS_NUM_BACKUP_ROOTS; i++) {
+ root_backup = info->super_copy->super_roots + i;
+ cur = btrfs_backup_tree_root_gen(root_backup);
+ if (cur == newest_gen)
+ newest_index = i;
+ }
+
+ /* check to see if we actually wrapped around */
+ if (newest_index == BTRFS_NUM_BACKUP_ROOTS - 1) {
+ root_backup = info->super_copy->super_roots;
+ cur = btrfs_backup_tree_root_gen(root_backup);
+ if (cur == newest_gen)
+ newest_index = 0;
+ }
+ return newest_index;
+}
+
+
+/*
+ * find the oldest backup so we know where to store new entries
+ * in the backup array. This will set the backup_root_index
+ * field in the fs_info struct
+ */
+static void find_oldest_super_backup(struct btrfs_fs_info *info,
+ u64 newest_gen)
+{
+ int newest_index = -1;
+
+ newest_index = find_newest_super_backup(info, newest_gen);
+ /* if there was garbage in there, just move along */
+ if (newest_index == -1) {
+ info->backup_root_index = 0;
+ } else {
+ info->backup_root_index = (newest_index + 1) % BTRFS_NUM_BACKUP_ROOTS;
+ }
+}
+
+/*
+ * copy all the root pointers into the super backup array.
+ * this will bump the backup pointer by one when it is
+ * done
+ */
+static void backup_super_roots(struct btrfs_fs_info *info)
+{
+ int next_backup;
+ struct btrfs_root_backup *root_backup;
+ int last_backup;
+
+ next_backup = info->backup_root_index;
+ last_backup = (next_backup + BTRFS_NUM_BACKUP_ROOTS - 1) %
+ BTRFS_NUM_BACKUP_ROOTS;
+
+ /*
+ * just overwrite the last backup if we're at the same generation
+ * this happens only at umount
+ */
+ root_backup = info->super_for_commit->super_roots + last_backup;
+ if (btrfs_backup_tree_root_gen(root_backup) ==
+ btrfs_header_generation(info->tree_root->node))
+ next_backup = last_backup;
+
+ root_backup = info->super_for_commit->super_roots + next_backup;
+
+ /*
+ * make sure all of our padding and empty slots get zero filled
+ * regardless of which ones we use today
+ */
+ memset(root_backup, 0, sizeof(*root_backup));
+
+ info->backup_root_index = (next_backup + 1) % BTRFS_NUM_BACKUP_ROOTS;
+
+ btrfs_set_backup_tree_root(root_backup, info->tree_root->node->start);
+ btrfs_set_backup_tree_root_gen(root_backup,
+ btrfs_header_generation(info->tree_root->node));
+
+ btrfs_set_backup_tree_root_level(root_backup,
+ btrfs_header_level(info->tree_root->node));
+
+ btrfs_set_backup_chunk_root(root_backup, info->chunk_root->node->start);
+ btrfs_set_backup_chunk_root_gen(root_backup,
+ btrfs_header_generation(info->chunk_root->node));
+ btrfs_set_backup_chunk_root_level(root_backup,
+ btrfs_header_level(info->chunk_root->node));
+
+ btrfs_set_backup_extent_root(root_backup, info->extent_root->node->start);
+ btrfs_set_backup_extent_root_gen(root_backup,
+ btrfs_header_generation(info->extent_root->node));
+ btrfs_set_backup_extent_root_level(root_backup,
+ btrfs_header_level(info->extent_root->node));
+
+ btrfs_set_backup_fs_root(root_backup, info->fs_root->node->start);
+ btrfs_set_backup_fs_root_gen(root_backup,
+ btrfs_header_generation(info->fs_root->node));
+ btrfs_set_backup_fs_root_level(root_backup,
+ btrfs_header_level(info->fs_root->node));
+
+ btrfs_set_backup_dev_root(root_backup, info->dev_root->node->start);
+ btrfs_set_backup_dev_root_gen(root_backup,
+ btrfs_header_generation(info->dev_root->node));
+ btrfs_set_backup_dev_root_level(root_backup,
+ btrfs_header_level(info->dev_root->node));
+
+ btrfs_set_backup_csum_root(root_backup, info->csum_root->node->start);
+ btrfs_set_backup_csum_root_gen(root_backup,
+ btrfs_header_generation(info->csum_root->node));
+ btrfs_set_backup_csum_root_level(root_backup,
+ btrfs_header_level(info->csum_root->node));
+
+ btrfs_set_backup_total_bytes(root_backup,
+ btrfs_super_total_bytes(info->super_copy));
+ btrfs_set_backup_bytes_used(root_backup,
+ btrfs_super_bytes_used(info->super_copy));
+ btrfs_set_backup_num_devices(root_backup,
+ btrfs_super_num_devices(info->super_copy));
+
+ /*
+ * if we don't copy this out to the super_copy, it won't get remembered
+ * for the next commit
+ */
+ memcpy(&info->super_copy->super_roots,
+ &info->super_for_commit->super_roots,
+ sizeof(*root_backup) * BTRFS_NUM_BACKUP_ROOTS);
+}
+
+/*
+ * this copies info out of the root backup array and back into
+ * the in-memory super block. It is meant to help iterate through
+ * the array, so you send it the number of backups you've already
+ * tried and the last backup index you used.
+ *
+ * this returns -1 when it has tried all the backups
+ */
+static noinline int next_root_backup(struct btrfs_fs_info *info,
+ struct btrfs_super_block *super,
+ int *num_backups_tried, int *backup_index)
+{
+ struct btrfs_root_backup *root_backup;
+ int newest = *backup_index;
+
+ if (*num_backups_tried == 0) {
+ u64 gen = btrfs_super_generation(super);
+
+ newest = find_newest_super_backup(info, gen);
+ if (newest == -1)
+ return -1;
+
+ *backup_index = newest;
+ *num_backups_tried = 1;
+ } else if (*num_backups_tried == BTRFS_NUM_BACKUP_ROOTS) {
+ /* we've tried all the backups, all done */
+ return -1;
+ } else {
+ /* jump to the next oldest backup */
+ newest = (*backup_index + BTRFS_NUM_BACKUP_ROOTS - 1) %
+ BTRFS_NUM_BACKUP_ROOTS;
+ *backup_index = newest;
+ *num_backups_tried += 1;
+ }
+ root_backup = super->super_roots + newest;
+
+ btrfs_set_super_generation(super,
+ btrfs_backup_tree_root_gen(root_backup));
+ btrfs_set_super_root(super, btrfs_backup_tree_root(root_backup));
+ btrfs_set_super_root_level(super,
+ btrfs_backup_tree_root_level(root_backup));
+ btrfs_set_super_bytes_used(super, btrfs_backup_bytes_used(root_backup));
+
+ /*
+ * fixme: the total bytes and num_devices need to match or we should
+ * need a fsck
+ */
+ btrfs_set_super_total_bytes(super, btrfs_backup_total_bytes(root_backup));
+ btrfs_set_super_num_devices(super, btrfs_backup_num_devices(root_backup));
+ return 0;
+}
+
+/* helper to cleanup tree roots */
+static void free_root_pointers(struct btrfs_fs_info *info, int chunk_root)
+{
+ free_extent_buffer(info->tree_root->node);
+ free_extent_buffer(info->tree_root->commit_root);
+ free_extent_buffer(info->dev_root->node);
+ free_extent_buffer(info->dev_root->commit_root);
+ free_extent_buffer(info->extent_root->node);
+ free_extent_buffer(info->extent_root->commit_root);
+ free_extent_buffer(info->csum_root->node);
+ free_extent_buffer(info->csum_root->commit_root);
+
+ info->tree_root->node = NULL;
+ info->tree_root->commit_root = NULL;
+ info->dev_root->node = NULL;
+ info->dev_root->commit_root = NULL;
+ info->extent_root->node = NULL;
+ info->extent_root->commit_root = NULL;
+ info->csum_root->node = NULL;
+ info->csum_root->commit_root = NULL;
+
+ if (chunk_root) {
+ free_extent_buffer(info->chunk_root->node);
+ free_extent_buffer(info->chunk_root->commit_root);
+ info->chunk_root->node = NULL;
+ info->chunk_root->commit_root = NULL;
+ }
+}
+
+