// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2007 Oracle. All rights reserved. */ #include <linux/err.h> #include <linux/uuid.h> #include "ctree.h" #include "transaction.h" #include "disk-io.h" #include "print-tree.h" /* * Read a root item from the tree. In case we detect a root item smaller then * sizeof(root_item), we know it's an old version of the root structure and * initialize all new fields to zero. The same happens if we detect mismatching * generation numbers as then we know the root was once mounted with an older * kernel that was not aware of the root item structure change. */ static void btrfs_read_root_item(struct extent_buffer *eb, int slot, struct btrfs_root_item *item) { uuid_le uuid; int len; int need_reset = 0; len = btrfs_item_size_nr(eb, slot); read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot), min_t(int, len, (int)sizeof(*item))); if (len < sizeof(*item)) need_reset = 1; if (!need_reset && btrfs_root_generation(item) != btrfs_root_generation_v2(item)) { if (btrfs_root_generation_v2(item) != 0) { btrfs_warn(eb->fs_info, "mismatching generation and generation_v2 found in root item. This root was probably mounted with an older kernel. Resetting all new fields."); } need_reset = 1; } if (need_reset) { memset(&item->generation_v2, 0, sizeof(*item) - offsetof(struct btrfs_root_item, generation_v2)); uuid_le_gen(&uuid); memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE); } } /* * btrfs_find_root - lookup the root by the key. * root: the root of the root tree * search_key: the key to search * path: the path we search * root_item: the root item of the tree we look for * root_key: the root key of the tree we look for * * If ->offset of 'search_key' is -1ULL, it means we are not sure the offset * of the search key, just lookup the root with the highest offset for a * given objectid. * * If we find something return 0, otherwise > 0, < 0 on error. */ int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key, struct btrfs_path *path, struct btrfs_root_item *root_item, struct btrfs_key *root_key) { struct btrfs_key found_key; struct extent_buffer *l; int ret; int slot; ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0); if (ret < 0) return ret; if (search_key->offset != -1ULL) { /* the search key is exact */ if (ret > 0) goto out; } else { BUG_ON(ret == 0); /* Logical error */ if (path->slots[0] == 0) goto out; path->slots[0]--; ret = 0; } l = path->nodes[0]; slot = path->slots[0]; btrfs_item_key_to_cpu(l, &found_key, slot); if (found_key.objectid != search_key->objectid || found_key.type != BTRFS_ROOT_ITEM_KEY) { ret = 1; goto out; } if (root_item) btrfs_read_root_item(l, slot, root_item); if (root_key) memcpy(root_key, &found_key, sizeof(found_key)); out: btrfs_release_path(path); return ret; } void btrfs_set_root_node(struct btrfs_root_item *item, struct extent_buffer *node) { btrfs_set_root_bytenr(item, node->start); btrfs_set_root_level(item, btrfs_header_level(node)); btrfs_set_root_generation(item, btrfs_header_generation(node)); } /* * copy the data in 'item' into the btree */ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_key *key, struct btrfs_root_item *item) { struct btrfs_fs_info *fs_info = root->fs_info; struct btrfs_path *path; struct extent_buffer *l; int ret; int slot; unsigned long ptr; u32 old_len; path = btrfs_alloc_path(); if (!path) return -ENOMEM; ret = btrfs_search_slot(trans, root, key, path, 0, 1); if (ret < 0) { btrfs_abort_transaction(trans, ret); goto out; } if (ret != 0) { btrfs_print_leaf(path->nodes[0]); btrfs_crit(fs_info, "unable to update root key %llu %u %llu", key->objectid, key->type, key->offset); BUG_ON(1); } l = path->nodes[0]; slot = path->slots[0]; ptr = btrfs_item_ptr_offset(l, slot); old_len = btrfs_item_size_nr(l, slot); /* * If this is the first time we update the root item which originated * from an older kernel, we need to enlarge the item size to make room * for the added fields. */ if (old_len < sizeof(*item)) { btrfs_release_path(path); ret = btrfs_search_slot(trans, root, key, path, -1, 1); if (ret < 0) { btrfs_abort_transaction(trans, ret); goto out; } ret = btrfs_del_item(trans, root, path); if (ret < 0) { btrfs_abort_transaction(trans, ret); goto out; } btrfs_release_path(path); ret = btrfs_insert_empty_item(trans, root, path, key, sizeof(*item)); if (ret < 0) { btrfs_abort_transaction(trans, ret); goto out; } l = path->nodes[0]; slot = path->slots[0]; ptr = btrfs_item_ptr_offset(l, slot); } /* * Update generation_v2 so at the next mount we know the new root * fields are valid. */ btrfs_set_root_generation_v2(item, btrfs_root_generation(item)); write_extent_buffer(l, item, ptr, sizeof(*item)); btrfs_mark_buffer_dirty(path->nodes[0]); out: btrfs_free_path(path); return ret; } int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, const struct btrfs_key *key, struct btrfs_root_item *item) { /* * Make sure generation v1 and v2 match. See update_root for details. */ btrfs_set_root_generation_v2(item, btrfs_root_generation(item)); return btrfs_insert_item(trans, root, key, item, sizeof(*item)); } int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info) { struct btrfs_root *tree_root = fs_info->tree_root; struct extent_buffer *leaf; struct btrfs_path *path; struct btrfs_key key; struct btrfs_key root_key; struct btrfs_root *root; int err = 0; int ret; path = btrfs_alloc_path(); if (!path) return -ENOMEM; key.objectid = BTRFS_ORPHAN_OBJECTID; key.type = BTRFS_ORPHAN_ITEM_KEY; key.offset = 0; root_key.type = BTRFS_ROOT_ITEM_KEY; root_key.offset = (u64)-1; while (1) { ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0); if (ret < 0) { err = ret; break; } leaf = path->nodes[0]; if (path->slots[0] >= btrfs_header_nritems(leaf)) { ret = btrfs_next_leaf(tree_root, path); if (ret < 0) err = ret; if (ret != 0) break; leaf = path->nodes[0]; } btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); btrfs_release_path(path); if (key.objectid != BTRFS_ORPHAN_OBJECTID || key.type != BTRFS_ORPHAN_ITEM_KEY) break; root_key.objectid = key.offset; key.offset++; /* * The root might have been inserted already, as before we look * for orphan roots, log replay might have happened, which * triggers a transaction commit and qgroup accounting, which * in turn reads and inserts fs roots while doing backref * walking. */ root = btrfs_lookup_fs_root(fs_info, root_key.objectid); if (root) { WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state)); if (btrfs_root_refs(&root->root_item) == 0) btrfs_add_dead_root(root); continue; } root = btrfs_read_fs_root(tree_root, &root_key); err = PTR_ERR_OR_ZERO(root); if (err && err != -ENOENT) { break; } else if (err == -ENOENT) { struct btrfs_trans_handle *trans; btrfs_release_path(path); trans = btrfs_join_transaction(tree_root); if (IS_ERR(trans)) { err = PTR_ERR(trans); btrfs_handle_fs_error(fs_info, err, "Failed to start trans to delete orphan item"); break; } err = btrfs_del_orphan_item(trans, tree_root, root_key.objectid); btrfs_end_transaction(trans); if (err) { btrfs_handle_fs_error(fs_info, err, "Failed to delete root orphan item"); break; } continue; } err = btrfs_init_fs_root(root); if (err) { btrfs_free_fs_root(root); break; } set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state); err = btrfs_insert_fs_root(fs_info, root); if (err) { BUG_ON(err == -EEXIST); btrfs_free_fs_root(root); break; } if (btrfs_root_refs(&root->root_item) == 0) btrfs_add_dead_root(root); } btrfs_free_path(path); return err; } /* drop the root item for 'key' from the tree root */ int btrfs_del_root(struct btrfs_trans_handle *trans, const struct btrfs_key *key) { struct btrfs_root *root = trans->fs_info->tree_root; struct btrfs_path *path; int ret; path = btrfs_alloc_path(); if (!path) return -ENOMEM; ret = btrfs_search_slot(trans, root, key, path, -1, 1); if (ret < 0) goto out; BUG_ON(ret != 0); ret = btrfs_del_item(trans, root, path); out: btrfs_free_path(path); return ret; } int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id, u64 ref_id, u64 dirid, u64 *sequence, const char *name, int name_len) { struct btrfs_root *tree_root = trans->fs_info->tree_root; struct btrfs_path *path; struct btrfs_root_ref *ref; struct extent_buffer *leaf; struct btrfs_key key; unsigned long ptr; int err = 0; int ret; path = btrfs_alloc_path(); if (!path) return -ENOMEM; key.objectid = root_id; key.type = BTRFS_ROOT_BACKREF_KEY; key.offset = ref_id; again: ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1); BUG_ON(ret < 0); if (ret == 0) { leaf = path->nodes[0]; ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref); WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid); WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len); ptr = (unsigned long)(ref + 1); WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len)); *sequence = btrfs_root_ref_sequence(leaf, ref); ret = btrfs_del_item(trans, tree_root, path); if (ret) { err = ret; goto out; } } else err = -ENOENT; if (key.type == BTRFS_ROOT_BACKREF_KEY) { btrfs_release_path(path); key.objectid = ref_id; key.type = BTRFS_ROOT_REF_KEY; key.offset = root_id; goto again; } out: btrfs_free_path(path); return err; } /* * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY * or BTRFS_ROOT_BACKREF_KEY. * * The dirid, sequence, name and name_len refer to the directory entry * that is referencing the root. * * For a forward ref, the root_id is the id of the tree referencing * the root and ref_id is the id of the subvol or snapshot. * * For a back ref the root_id is the id of the subvol or snapshot and * ref_id is the id of the tree referencing it. * * Will return 0, -ENOMEM, or anything from the CoW path */ int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id, u64 ref_id, u64 dirid, u64 sequence, const char *name, int name_len) { struct btrfs_root *tree_root = trans->fs_info->tree_root; struct btrfs_key key; int ret; struct btrfs_path *path; struct btrfs_root_ref *ref; struct extent_buffer *leaf; unsigned long ptr; path = btrfs_alloc_path(); if (!path) return -ENOMEM; key.objectid = root_id; key.type = BTRFS_ROOT_BACKREF_KEY; key.offset = ref_id; again: ret = btrfs_insert_empty_item(trans, tree_root, path, &key, sizeof(*ref) + name_len); if (ret) { btrfs_abort_transaction(trans, ret); btrfs_free_path(path); return ret; } leaf = path->nodes[0]; ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref); btrfs_set_root_ref_dirid(leaf, ref, dirid); btrfs_set_root_ref_sequence(leaf, ref, sequence); btrfs_set_root_ref_name_len(leaf, ref, name_len); ptr = (unsigned long)(ref + 1); write_extent_buffer(leaf, name, ptr, name_len); btrfs_mark_buffer_dirty(leaf); if (key.type == BTRFS_ROOT_BACKREF_KEY) { btrfs_release_path(path); key.objectid = ref_id; key.type = BTRFS_ROOT_REF_KEY; key.offset = root_id; goto again; } btrfs_free_path(path); return 0; } /* * Old btrfs forgets to init root_item->flags and root_item->byte_limit * for subvolumes. To work around this problem, we steal a bit from * root_item->inode_item->flags, and use it to indicate if those fields * have been properly initialized. */ void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item) { u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode); if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) { inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT; btrfs_set_stack_inode_flags(&root_item->inode, inode_flags); btrfs_set_root_flags(root_item, 0); btrfs_set_root_limit(root_item, 0); } } void btrfs_update_root_times(struct btrfs_trans_handle *trans, struct btrfs_root *root) { struct btrfs_root_item *item = &root->root_item; struct timespec64 ct; ktime_get_real_ts64(&ct); spin_lock(&root->root_item_lock); btrfs_set_root_ctransid(item, trans->transid); btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec); btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec); spin_unlock(&root->root_item_lock); }