/*
 * 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 "disk-io.h"
#include "hash.h"
#include "transaction.h"
#include "print-tree.h"

static int find_name_in_backref(struct btrfs_path *path, const char *name,
                         int name_len, struct btrfs_inode_ref **ref_ret)
{
        struct extent_buffer *leaf;
        struct btrfs_inode_ref *ref;
        unsigned long ptr;
        unsigned long name_ptr;
        u32 item_size;
        u32 cur_offset = 0;
        int len;

        leaf = path->nodes[0];
        item_size = btrfs_item_size_nr(leaf, path->slots[0]);
        ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
        while (cur_offset < item_size) {
                ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
                len = btrfs_inode_ref_name_len(leaf, ref);
                name_ptr = (unsigned long)(ref + 1);
                cur_offset += len + sizeof(*ref);
                if (len != name_len)
                        continue;
                if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0) {
                        *ref_ret = ref;
                        return 1;
                }
        }
        return 0;
}

int btrfs_find_name_in_ext_backref(struct btrfs_path *path, u64 ref_objectid,
                                   const char *name, int name_len,
                                   struct btrfs_inode_extref **extref_ret)
{
        struct extent_buffer *leaf;
        struct btrfs_inode_extref *extref;
        unsigned long ptr;
        unsigned long name_ptr;
        u32 item_size;
        u32 cur_offset = 0;
        int ref_name_len;

        leaf = path->nodes[0];
        item_size = btrfs_item_size_nr(leaf, path->slots[0]);
        ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);

        /*
         * Search all extended backrefs in this item. We're only
         * looking through any collisions so most of the time this is
         * just going to compare against one buffer. If all is well,
         * we'll return success and the inode ref object.
         */
        while (cur_offset < item_size) {
                extref = (struct btrfs_inode_extref *) (ptr + cur_offset);
                name_ptr = (unsigned long)(&extref->name);
                ref_name_len = btrfs_inode_extref_name_len(leaf, extref);

                if (ref_name_len == name_len &&
                    btrfs_inode_extref_parent(leaf, extref) == ref_objectid &&
                    (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)) {
                        if (extref_ret)
                                *extref_ret = extref;
                        return 1;
                }

                cur_offset += ref_name_len + sizeof(*extref);
        }
        return 0;
}

/* Returns NULL if no extref found */
struct btrfs_inode_extref *
btrfs_lookup_inode_extref(struct btrfs_trans_handle *trans,
                          struct btrfs_root *root,
                          struct btrfs_path *path,
                          const char *name, int name_len,
                          u64 inode_objectid, u64 ref_objectid, int ins_len,
                          int cow)
{
        int ret;
        struct btrfs_key key;
        struct btrfs_inode_extref *extref;

        key.objectid = inode_objectid;
        key.type = BTRFS_INODE_EXTREF_KEY;
        key.offset = btrfs_extref_hash(ref_objectid, name, name_len);

        ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
        if (ret < 0)
                return ERR_PTR(ret);
        if (ret > 0)
                return NULL;
        if (!btrfs_find_name_in_ext_backref(path, ref_objectid, name, name_len, &extref))
                return NULL;
        return extref;
}

static int btrfs_del_inode_extref(struct btrfs_trans_handle *trans,
                                  struct btrfs_root *root,
                                  const char *name, int name_len,
                                  u64 inode_objectid, u64 ref_objectid,
                                  u64 *index)
{
        struct btrfs_path *path;
        struct btrfs_key key;
        struct btrfs_inode_extref *extref;
        struct extent_buffer *leaf;
        int ret;
        int del_len = name_len + sizeof(*extref);
        unsigned long ptr;
        unsigned long item_start;
        u32 item_size;

        key.objectid = inode_objectid;
        key.type = BTRFS_INODE_EXTREF_KEY;
        key.offset = btrfs_extref_hash(ref_objectid, name, name_len);

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

        path->leave_spinning = 1;

        ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
        if (ret > 0)
                ret = -ENOENT;
        if (ret < 0)
                goto out;

        /*
         * Sanity check - did we find the right item for this name?
         * This should always succeed so error here will make the FS
         * readonly.
         */
        if (!btrfs_find_name_in_ext_backref(path, ref_objectid,
                                            name, name_len, &extref)) {
                btrfs_std_error(root->fs_info, -ENOENT, NULL);
                ret = -EROFS;
                goto out;
        }

        leaf = path->nodes[0];
        item_size = btrfs_item_size_nr(leaf, path->slots[0]);
        if (index)
                *index = btrfs_inode_extref_index(leaf, extref);

        if (del_len == item_size) {
                /*
                 * Common case only one ref in the item, remove the
                 * whole item.
                 */
                ret = btrfs_del_item(trans, root, path);
                goto out;
        }

        ptr = (unsigned long)extref;
        item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);

        memmove_extent_buffer(leaf, ptr, ptr + del_len,
                              item_size - (ptr + del_len - item_start));

        btrfs_truncate_item(root, path, item_size - del_len, 1);

out:
        btrfs_free_path(path);

        return ret;
}

int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
                        struct btrfs_root *root,
                        const char *name, int name_len,
                        u64 inode_objectid, u64 ref_objectid, u64 *index)
{
        struct btrfs_path *path;
        struct btrfs_key key;
        struct btrfs_inode_ref *ref;
        struct extent_buffer *leaf;
        unsigned long ptr;
        unsigned long item_start;
        u32 item_size;
        u32 sub_item_len;
        int ret;
        int search_ext_refs = 0;
        int del_len = name_len + sizeof(*ref);

        key.objectid = inode_objectid;
        key.offset = ref_objectid;
        key.type = BTRFS_INODE_REF_KEY;

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

        path->leave_spinning = 1;

        ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
        if (ret > 0) {
                ret = -ENOENT;
                search_ext_refs = 1;
                goto out;
        } else if (ret < 0) {
                goto out;
        }
        if (!find_name_in_backref(path, name, name_len, &ref)) {
                ret = -ENOENT;
                search_ext_refs = 1;
                goto out;
        }
        leaf = path->nodes[0];
        item_size = btrfs_item_size_nr(leaf, path->slots[0]);

        if (index)
                *index = btrfs_inode_ref_index(leaf, ref);

        if (del_len == item_size) {
                ret = btrfs_del_item(trans, root, path);
                goto out;
        }
        ptr = (unsigned long)ref;
        sub_item_len = name_len + sizeof(*ref);
        item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
        memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
                              item_size - (ptr + sub_item_len - item_start));
        btrfs_truncate_item(root, path, item_size - sub_item_len, 1);
out:
        btrfs_free_path(path);

        if (search_ext_refs) {
                /*
                 * No refs were found, or we could not find the
                 * name in our ref array. Find and remove the extended
                 * inode ref then.
                 */
                return btrfs_del_inode_extref(trans, root, name, name_len,
                                              inode_objectid, ref_objectid, index);
        }

        return ret;
}

/*
 * btrfs_insert_inode_extref() - Inserts an extended inode ref into a tree.
 *
 * The caller must have checked against BTRFS_LINK_MAX already.
 */
static int btrfs_insert_inode_extref(struct btrfs_trans_handle *trans,
                                     struct btrfs_root *root,
                                     const char *name, int name_len,
                                     u64 inode_objectid, u64 ref_objectid, u64 index)
{
        struct btrfs_inode_extref *extref;
        int ret;
        int ins_len = name_len + sizeof(*extref);
        unsigned long ptr;
        struct btrfs_path *path;
        struct btrfs_key key;
        struct extent_buffer *leaf;
        struct btrfs_item *item;

        key.objectid = inode_objectid;
        key.type = BTRFS_INODE_EXTREF_KEY;
        key.offset = btrfs_extref_hash(ref_objectid, name, name_len);

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

        path->leave_spinning = 1;
        ret = btrfs_insert_empty_item(trans, root, path, &key,
                                      ins_len);
        if (ret == -EEXIST) {
                if (btrfs_find_name_in_ext_backref(path, ref_objectid,
                                                   name, name_len, NULL))
                        goto out;

                btrfs_extend_item(root, path, ins_len);
                ret = 0;
        }
        if (ret < 0)
                goto out;

        leaf = path->nodes[0];
        item = btrfs_item_nr(path->slots[0]);
        ptr = (unsigned long)btrfs_item_ptr(leaf, path->slots[0], char);
        ptr += btrfs_item_size(leaf, item) - ins_len;
        extref = (struct btrfs_inode_extref *)ptr;

        btrfs_set_inode_extref_name_len(path->nodes[0], extref, name_len);
        btrfs_set_inode_extref_index(path->nodes[0], extref, index);
        btrfs_set_inode_extref_parent(path->nodes[0], extref, ref_objectid);

        ptr = (unsigned long)&extref->name;
        write_extent_buffer(path->nodes[0], name, ptr, name_len);
        btrfs_mark_buffer_dirty(path->nodes[0]);

out:
        btrfs_free_path(path);
        return ret;
}

/* Will return 0, -ENOMEM, -EMLINK, or -EEXIST or anything from the CoW path */
int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
                           struct btrfs_root *root,
                           const char *name, int name_len,
                           u64 inode_objectid, u64 ref_objectid, u64 index)
{
        struct btrfs_path *path;
        struct btrfs_key key;
        struct btrfs_inode_ref *ref;
        unsigned long ptr;
        int ret;
        int ins_len = name_len + sizeof(*ref);

        key.objectid = inode_objectid;
        key.offset = ref_objectid;
        key.type = BTRFS_INODE_REF_KEY;

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

        path->leave_spinning = 1;
        path->skip_release_on_error = 1;
        ret = btrfs_insert_empty_item(trans, root, path, &key,
                                      ins_len);
        if (ret == -EEXIST) {
                u32 old_size;

                if (find_name_in_backref(path, name, name_len, &ref))
                        goto out;

                old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
                btrfs_extend_item(root, path, ins_len);
                ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
                                     struct btrfs_inode_ref);
                ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
                btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
                btrfs_set_inode_ref_index(path->nodes[0], ref, index);
                ptr = (unsigned long)(ref + 1);
                ret = 0;
        } else if (ret < 0) {
                if (ret == -EOVERFLOW) {
                        if (find_name_in_backref(path, name, name_len, &ref))
                                ret = -EEXIST;
                        else
                                ret = -EMLINK;
                }
                goto out;
        } else {
                ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
                                     struct btrfs_inode_ref);
                btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
                btrfs_set_inode_ref_index(path->nodes[0], ref, index);
                ptr = (unsigned long)(ref + 1);
        }
        write_extent_buffer(path->nodes[0], name, ptr, name_len);
        btrfs_mark_buffer_dirty(path->nodes[0]);

out:
        btrfs_free_path(path);

        if (ret == -EMLINK) {
                struct btrfs_super_block *disk_super = root->fs_info->super_copy;
                /* We ran out of space in the ref array. Need to
                 * add an extended ref. */
                if (btrfs_super_incompat_flags(disk_super)
                    & BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
                        ret = btrfs_insert_inode_extref(trans, root, name,
                                                        name_len,
                                                        inode_objectid,
                                                        ref_objectid, index);
        }

        return ret;
}

int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
                             struct btrfs_root *root,
                             struct btrfs_path *path, u64 objectid)
{
        struct btrfs_key key;
        int ret;
        key.objectid = objectid;
        key.type = BTRFS_INODE_ITEM_KEY;
        key.offset = 0;

        ret = btrfs_insert_empty_item(trans, root, path, &key,
                                      sizeof(struct btrfs_inode_item));
        return ret;
}

int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
                       *root, struct btrfs_path *path,
                       struct btrfs_key *location, int mod)
{
        int ins_len = mod < 0 ? -1 : 0;
        int cow = mod != 0;
        int ret;
        int slot;
        struct extent_buffer *leaf;
        struct btrfs_key found_key;

        ret = btrfs_search_slot(trans, root, location, path, ins_len, cow);
        if (ret > 0 && location->type == BTRFS_ROOT_ITEM_KEY &&
            location->offset == (u64)-1 && path->slots[0] != 0) {
                slot = path->slots[0] - 1;
                leaf = path->nodes[0];
                btrfs_item_key_to_cpu(leaf, &found_key, slot);
                if (found_key.objectid == location->objectid &&
                    found_key.type == location->type) {
                        path->slots[0]--;
                        return 0;
                }
        }
        return ret;
}