// 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 "fs.h"
#include "messages.h"
#include "transaction.h"
#include "disk-io.h"
#include "qgroup.h"
#include "space-info.h"
#include "accessors.h"
#include "root-tree.h"
#include "orphan.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)
{
        u32 len;
        int need_reset = 0;

        len = btrfs_item_size(eb, slot);
        read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
                           min_t(u32, len, 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) {
                /* Clear all members from generation_v2 onwards. */
                memset_startat(item, 0, generation_v2);
                generate_random_guid(item->uuid);
        }
}

/*
 * 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 {
                /*
                 * Key with offset -1 found, there would have to exist a root
                 * with such id, but this is out of the valid range.
                 */
                if (unlikely(ret == 0)) {
                        ret = -EUCLEAN;
                        goto out;
                }
                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;
        BTRFS_PATH_AUTO_FREE(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)
                return ret;

        if (unlikely(ret > 0)) {
                btrfs_crit(fs_info,
                           "unable to find root key " BTRFS_KEY_FMT " in tree %llu",
                           BTRFS_KEY_FMT_VALUE(key), btrfs_root_id(root));
                ret = -EUCLEAN;
                btrfs_abort_transaction(trans, ret);
                return ret;
        }

        l = path->nodes[0];
        slot = path->slots[0];
        ptr = btrfs_item_ptr_offset(l, slot);
        old_len = btrfs_item_size(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 (unlikely(ret < 0)) {
                        btrfs_abort_transaction(trans, ret);
                        return ret;
                }

                ret = btrfs_del_item(trans, root, path);
                if (unlikely(ret < 0)) {
                        btrfs_abort_transaction(trans, ret);
                        return ret;
                }
                btrfs_release_path(path);
                ret = btrfs_insert_empty_item(trans, root, path,
                                key, sizeof(*item));
                if (unlikely(ret < 0)) {
                        btrfs_abort_transaction(trans, ret);
                        return ret;
                }
                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));
        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;
        BTRFS_PATH_AUTO_FREE(path);
        struct btrfs_key key;
        struct btrfs_root *root;

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        key.objectid = BTRFS_ORPHAN_OBJECTID;
        key.type = BTRFS_ORPHAN_ITEM_KEY;
        key.offset = 0;

        while (1) {
                u64 root_objectid;
                int ret;

                ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
                if (ret < 0)
                        return ret;

                leaf = path->nodes[0];
                if (path->slots[0] >= btrfs_header_nritems(leaf)) {
                        ret = btrfs_next_leaf(tree_root, path);
                        if (ret < 0)
                                return ret;
                        else if (ret > 0)
                                return 0;
                        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)
                        return 0;

                root_objectid = key.offset;
                key.offset++;

                root = btrfs_get_fs_root(fs_info, root_objectid, false);
                ret = PTR_ERR_OR_ZERO(root);
                if (ret && ret != -ENOENT) {
                        return ret;
                } else if (ret == -ENOENT) {
                        struct btrfs_trans_handle *trans;

                        trans = btrfs_join_transaction(tree_root);
                        if (IS_ERR(trans)) {
                                ret = PTR_ERR(trans);
                                btrfs_err(fs_info,
                          "failed to join transaction to delete orphan item: %d",
                                          ret);
                                return ret;
                        }
                        ret = btrfs_del_orphan_item(trans, tree_root, root_objectid);
                        btrfs_end_transaction(trans);
                        if (ret) {
                                btrfs_err(fs_info,
                                  "failed to delete root orphan item: %d", ret);
                                return ret;
                        }
                        continue;
                }

                WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state));
                if (btrfs_root_refs(&root->root_item) == 0) {
                        struct btrfs_key drop_key;

                        btrfs_disk_key_to_cpu(&drop_key, &root->root_item.drop_progress);
                        /*
                         * If we have a non-zero drop_progress then we know we
                         * made it partly through deleting this snapshot, and
                         * thus we need to make sure we block any balance from
                         * happening until this snapshot is completely dropped.
                         */
                        if (drop_key.objectid != 0 || drop_key.type != 0 ||
                            drop_key.offset != 0) {
                                set_bit(BTRFS_FS_UNFINISHED_DROPS, &fs_info->flags);
                                set_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state);
                        }

                        set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
                        btrfs_add_dead_root(root);
                }
                btrfs_put_root(root);
        }

        return 0;
}

/* 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;
        BTRFS_PATH_AUTO_FREE(path);
        int ret;

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;
        ret = btrfs_search_slot(trans, root, key, path, -1, 1);
        if (ret < 0)
                return ret;
        if (unlikely(ret > 0))
                /* The root must exist but we did not find it by the key. */
                return -EUCLEAN;

        return btrfs_del_item(trans, root, path);
}

int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
                       u64 ref_id, u64 dirid, u64 *sequence,
                       const struct fscrypt_str *name)
{
        struct btrfs_root *tree_root = trans->fs_info->tree_root;
        BTRFS_PATH_AUTO_FREE(path);
        struct btrfs_root_ref *ref;
        struct extent_buffer *leaf;
        struct btrfs_key key;
        unsigned long ptr;
        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);
        if (ret < 0) {
                return ret;
        } else if (ret == 0) {
                leaf = path->nodes[0];
                ref = btrfs_item_ptr(leaf, path->slots[0],
                                     struct btrfs_root_ref);
                ptr = (unsigned long)(ref + 1);
                if ((btrfs_root_ref_dirid(leaf, ref) != dirid) ||
                    (btrfs_root_ref_name_len(leaf, ref) != name->len) ||
                    memcmp_extent_buffer(leaf, name->name, ptr, name->len))
                        return -ENOENT;

                *sequence = btrfs_root_ref_sequence(leaf, ref);

                ret = btrfs_del_item(trans, tree_root, path);
                if (ret)
                        return ret;
        } else {
                return -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;
        }

        return ret;
}

/*
 * 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 struct fscrypt_str *name)
{
        struct btrfs_root *tree_root = trans->fs_info->tree_root;
        struct btrfs_key key;
        int ret;
        BTRFS_PATH_AUTO_FREE(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 (unlikely(ret)) {
                btrfs_abort_transaction(trans, ret);
                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->name, ptr, name->len);

        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;
        }

        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);
}

/*
 * Reserve space for subvolume operation.
 *
 * root: the root of the parent directory
 * rsv: block reservation
 * items: the number of items that we need do reservation
 * use_global_rsv: allow fallback to the global block reservation
 *
 * This function is used to reserve the space for snapshot/subvolume
 * creation and deletion. Those operations are different with the
 * common file/directory operations, they change two fs/file trees
 * and root tree, the number of items that the qgroup reserves is
 * different with the free space reservation. So we can not use
 * the space reservation mechanism in start_transaction().
 */
int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,
                                     struct btrfs_block_rsv *rsv, int items,
                                     bool use_global_rsv)
{
        u64 qgroup_num_bytes = 0;
        u64 num_bytes;
        int ret;
        struct btrfs_fs_info *fs_info = root->fs_info;
        struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;

        if (btrfs_qgroup_enabled(fs_info)) {
                /* One for parent inode, two for dir entries */
                qgroup_num_bytes = 3 * fs_info->nodesize;
                ret = btrfs_qgroup_reserve_meta_prealloc(root,
                                                         qgroup_num_bytes, true,
                                                         false);
                if (ret)
                        return ret;
        }

        num_bytes = btrfs_calc_insert_metadata_size(fs_info, items);
        rsv->space_info = btrfs_find_space_info(fs_info,
                                            BTRFS_BLOCK_GROUP_METADATA);
        ret = btrfs_block_rsv_add(fs_info, rsv, num_bytes,
                                  BTRFS_RESERVE_FLUSH_ALL);

        if (ret == -ENOSPC && use_global_rsv)
                ret = btrfs_block_rsv_migrate(global_rsv, rsv, num_bytes, true);

        if (ret && qgroup_num_bytes)
                btrfs_qgroup_free_meta_prealloc(root, qgroup_num_bytes);

        if (!ret) {
                spin_lock(&rsv->lock);
                rsv->qgroup_rsv_reserved += qgroup_num_bytes;
                spin_unlock(&rsv->lock);
        }
        return ret;
}