/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include "ctree.h"
#include "transaction.h"
#include "disk-io.h"
#include "print-tree.h"

/*
 *  search forward for a root, starting with objectid 'search_start'
 *  if a root key is found, the objectid we find is filled into 'found_objectid'
 *  and 0 is returned.  < 0 is returned on error, 1 if there is nothing
 *  left in the tree.
 */
int btrfs_search_root(struct btrfs_root *root, u64 search_start,
                      u64 *found_objectid)
{
        struct btrfs_path *path;
        struct btrfs_key search_key;
        int ret;

        root = root->fs_info->tree_root;
        search_key.objectid = search_start;
        search_key.type = (u8)-1;
        search_key.offset = (u64)-1;

        path = btrfs_alloc_path();
        BUG_ON(!path);
again:
        ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
        if (ret < 0)
                goto out;
        if (ret == 0) {
                ret = 1;
                goto out;
        }
        if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
                ret = btrfs_next_leaf(root, path);
                if (ret)
                        goto out;
        }
        btrfs_item_key_to_cpu(path->nodes[0], &search_key, path->slots[0]);
        if (search_key.type != BTRFS_ROOT_ITEM_KEY) {
                search_key.offset++;
                btrfs_release_path(root, path);
                goto again;
        }
        ret = 0;
        *found_objectid = search_key.objectid;

out:
        btrfs_free_path(path);
        return ret;
}

/*
 * lookup the root with the highest offset for a given objectid.  The key we do
 * find is copied into 'key'.  If we find something return 0, otherwise 1, < 0
 * on error.
 */
int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
                        struct btrfs_root_item *item, struct btrfs_key *key)
{
        struct btrfs_path *path;
        struct btrfs_key search_key;
        struct btrfs_key found_key;
        struct extent_buffer *l;
        int ret;
        int slot;

        search_key.objectid = objectid;
        search_key.type = BTRFS_ROOT_ITEM_KEY;
        search_key.offset = (u64)-1;

        path = btrfs_alloc_path();
        BUG_ON(!path);
        ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
        if (ret < 0)
                goto out;

        BUG_ON(ret == 0);
        if (path->slots[0] == 0) {
                ret = 1;
                goto out;
        }
        l = path->nodes[0];
        slot = path->slots[0] - 1;
        btrfs_item_key_to_cpu(l, &found_key, slot);
        if (found_key.objectid != objectid ||
            found_key.type != BTRFS_ROOT_ITEM_KEY) {
                ret = 1;
                goto out;
        }
        if (item)
                read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
                                   sizeof(*item));
        if (key)
                memcpy(key, &found_key, sizeof(found_key));
        ret = 0;
out:
        btrfs_free_path(path);
        return ret;
}

int 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));
        return 0;
}

/*
 * 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_path *path;
        struct extent_buffer *l;
        int ret;
        int slot;
        unsigned long ptr;

        path = btrfs_alloc_path();
        BUG_ON(!path);
        ret = btrfs_search_slot(trans, root, key, path, 0, 1);
        if (ret < 0)
                goto out;

        if (ret != 0) {
                btrfs_print_leaf(root, path->nodes[0]);
                printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
                       (unsigned long long)key->objectid, key->type,
                       (unsigned long long)key->offset);
                BUG_ON(1);
        }

        l = path->nodes[0];
        slot = path->slots[0];
        ptr = btrfs_item_ptr_offset(l, slot);
        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, struct btrfs_key *key, struct btrfs_root_item
                      *item)
{
        int ret;
        ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
        return ret;
}

/*
 * at mount time we want to find all the old transaction snapshots that were in
 * the process of being deleted if we crashed.  This is any root item with an
 * offset lower than the latest root.  They need to be queued for deletion to
 * finish what was happening when we crashed.
 */
int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
{
        struct btrfs_root *dead_root;
        struct btrfs_item *item;
        struct btrfs_root_item *ri;
        struct btrfs_key key;
        struct btrfs_key found_key;
        struct btrfs_path *path;
        int ret;
        u32 nritems;
        struct extent_buffer *leaf;
        int slot;

        key.objectid = objectid;
        btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
        key.offset = 0;
        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

again:
        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
        if (ret < 0)
                goto err;
        while (1) {
                leaf = path->nodes[0];
                nritems = btrfs_header_nritems(leaf);
                slot = path->slots[0];
                if (slot >= nritems) {
                        ret = btrfs_next_leaf(root, path);
                        if (ret)
                                break;
                        leaf = path->nodes[0];
                        nritems = btrfs_header_nritems(leaf);
                        slot = path->slots[0];
                }
                item = btrfs_item_nr(leaf, slot);
                btrfs_item_key_to_cpu(leaf, &key, slot);
                if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
                        goto next;

                if (key.objectid < objectid)
                        goto next;

                if (key.objectid > objectid)
                        break;

                ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
                if (btrfs_disk_root_refs(leaf, ri) != 0)
                        goto next;

                memcpy(&found_key, &key, sizeof(key));
                key.offset++;
                btrfs_release_path(root, path);
                dead_root =
                        btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
                                                    &found_key);
                if (IS_ERR(dead_root)) {
                        ret = PTR_ERR(dead_root);
                        goto err;
                }

                ret = btrfs_add_dead_root(dead_root);
                if (ret)
                        goto err;
                goto again;
next:
                slot++;
                path->slots[0]++;
        }
        ret = 0;
err:
        btrfs_free_path(path);
        return ret;
}

int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
{
        struct extent_buffer *leaf;
        struct btrfs_path *path;
        struct btrfs_key key;
        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;

        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(tree_root, path);

                if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
                    key.type != BTRFS_ORPHAN_ITEM_KEY)
                        break;

                ret = btrfs_find_dead_roots(tree_root, key.offset);
                if (ret) {
                        err = ret;
                        break;
                }

                key.offset++;
        }

        btrfs_free_path(path);
        return err;
}

/* drop the root item for 'key' from 'root' */
int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                   struct btrfs_key *key)
{
        struct btrfs_path *path;
        int ret;
        u32 refs;
        struct btrfs_root_item *ri;
        struct extent_buffer *leaf;

        path = btrfs_alloc_path();
        BUG_ON(!path);
        ret = btrfs_search_slot(trans, root, key, path, -1, 1);
        if (ret < 0)
                goto out;

        BUG_ON(ret != 0);
        leaf = path->nodes[0];
        ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);

        refs = btrfs_disk_root_refs(leaf, ri);
        BUG_ON(refs != 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,
                       struct btrfs_root *tree_root,
                       u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
                       const char *name, int name_len)

{
        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);
                BUG_ON(ret);
        } else
                err = -ENOENT;

        if (key.type == BTRFS_ROOT_BACKREF_KEY) {
                btrfs_release_path(tree_root, path);
                key.objectid = ref_id;
                key.type = BTRFS_ROOT_REF_KEY;
                key.offset = root_id;
                goto again;
        }

        btrfs_free_path(path);
        return err;
}

int btrfs_find_root_ref(struct btrfs_root *tree_root,
                   struct btrfs_path *path,
                   u64 root_id, u64 ref_id)
{
        struct btrfs_key key;
        int ret;

        key.objectid = root_id;
        key.type = BTRFS_ROOT_REF_KEY;
        key.offset = ref_id;

        ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
        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.
 */
int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
                       struct btrfs_root *tree_root,
                       u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
                       const char *name, int name_len)
{
        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);
        BUG_ON(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(tree_root, path);
                key.objectid = ref_id;
                key.type = BTRFS_ROOT_REF_KEY;
                key.offset = root_id;
                goto again;
        }

        btrfs_free_path(path);
        return 0;
}