#include <linux/fs.h>
#include <linux/types.h>
#include "ctree.h"
#include "disk-io.h"
#include "btrfs_inode.h"
#include "print-tree.h"
#include "export.h"
#include "compat.h"

#define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
                                                 parent_objectid) / 4)
#define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
                                             parent_root_objectid) / 4)
#define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)

static int btrfs_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
                           int connectable)
{
        struct btrfs_fid *fid = (struct btrfs_fid *)fh;
        struct inode *inode = dentry->d_inode;
        int len = *max_len;
        int type;

        if ((len < BTRFS_FID_SIZE_NON_CONNECTABLE) ||
            (connectable && len < BTRFS_FID_SIZE_CONNECTABLE))
                return 255;

        len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
        type = FILEID_BTRFS_WITHOUT_PARENT;

        fid->objectid = inode->i_ino;
        fid->root_objectid = BTRFS_I(inode)->root->objectid;
        fid->gen = inode->i_generation;

        if (connectable && !S_ISDIR(inode->i_mode)) {
                struct inode *parent;
                u64 parent_root_id;

                spin_lock(&dentry->d_lock);

                parent = dentry->d_parent->d_inode;
                fid->parent_objectid = BTRFS_I(parent)->location.objectid;
                fid->parent_gen = parent->i_generation;
                parent_root_id = BTRFS_I(parent)->root->objectid;

                spin_unlock(&dentry->d_lock);

                if (parent_root_id != fid->root_objectid) {
                        fid->parent_root_objectid = parent_root_id;
                        len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
                        type = FILEID_BTRFS_WITH_PARENT_ROOT;
                } else {
                        len = BTRFS_FID_SIZE_CONNECTABLE;
                        type = FILEID_BTRFS_WITH_PARENT;
                }
        }

        *max_len = len;
        return type;
}

static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
                                       u64 root_objectid, u32 generation,
                                       int check_generation)
{
        struct btrfs_fs_info *fs_info = btrfs_sb(sb)->fs_info;
        struct btrfs_root *root;
        struct dentry *dentry;
        struct inode *inode;
        struct btrfs_key key;
        int index;
        int err = 0;

        if (objectid < BTRFS_FIRST_FREE_OBJECTID)
                return ERR_PTR(-ESTALE);

        key.objectid = root_objectid;
        btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
        key.offset = (u64)-1;

        index = srcu_read_lock(&fs_info->subvol_srcu);

        root = btrfs_read_fs_root_no_name(fs_info, &key);
        if (IS_ERR(root)) {
                err = PTR_ERR(root);
                goto fail;
        }

        if (btrfs_root_refs(&root->root_item) == 0) {
                err = -ENOENT;
                goto fail;
        }

        key.objectid = objectid;
        btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
        key.offset = 0;

        inode = btrfs_iget(sb, &key, root);
        if (IS_ERR(inode)) {
                err = PTR_ERR(inode);
                goto fail;
        }

        srcu_read_unlock(&fs_info->subvol_srcu, index);

        if (check_generation && generation != inode->i_generation) {
                iput(inode);
                return ERR_PTR(-ESTALE);
        }

        dentry = d_obtain_alias(inode);
        if (!IS_ERR(dentry))
                dentry->d_op = &btrfs_dentry_operations;
        return dentry;
fail:
        srcu_read_unlock(&fs_info->subvol_srcu, index);
        return ERR_PTR(err);
}

static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
                                         int fh_len, int fh_type)
{
        struct btrfs_fid *fid = (struct btrfs_fid *) fh;
        u64 objectid, root_objectid;
        u32 generation;

        if (fh_type == FILEID_BTRFS_WITH_PARENT) {
                if (fh_len !=  BTRFS_FID_SIZE_CONNECTABLE)
                        return NULL;
                root_objectid = fid->root_objectid;
        } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
                if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
                        return NULL;
                root_objectid = fid->parent_root_objectid;
        } else
                return NULL;

        objectid = fid->parent_objectid;
        generation = fid->parent_gen;

        return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
}

static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
                                         int fh_len, int fh_type)
{
        struct btrfs_fid *fid = (struct btrfs_fid *) fh;
        u64 objectid, root_objectid;
        u32 generation;

        if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
             fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
            (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
             fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
            (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
             fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
                return NULL;

        objectid = fid->objectid;
        root_objectid = fid->root_objectid;
        generation = fid->gen;

        return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
}

static struct dentry *btrfs_get_parent(struct dentry *child)
{
        struct inode *dir = child->d_inode;
        static struct dentry *dentry;
        struct btrfs_root *root = BTRFS_I(dir)->root;
        struct btrfs_path *path;
        struct extent_buffer *leaf;
        struct btrfs_root_ref *ref;
        struct btrfs_key key;
        struct btrfs_key found_key;
        int ret;

        path = btrfs_alloc_path();

        if (dir->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
                key.objectid = root->root_key.objectid;
                key.type = BTRFS_ROOT_BACKREF_KEY;
                key.offset = (u64)-1;
                root = root->fs_info->tree_root;
        } else {
                key.objectid = dir->i_ino;
                key.type = BTRFS_INODE_REF_KEY;
                key.offset = (u64)-1;
        }

        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
        if (ret < 0)
                goto fail;

        BUG_ON(ret == 0);
        if (path->slots[0] == 0) {
                ret = -ENOENT;
                goto fail;
        }

        path->slots[0]--;
        leaf = path->nodes[0];

        btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
        if (found_key.objectid != key.objectid || found_key.type != key.type) {
                ret = -ENOENT;
                goto fail;
        }

        if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
                ref = btrfs_item_ptr(leaf, path->slots[0],
                                     struct btrfs_root_ref);
                key.objectid = btrfs_root_ref_dirid(leaf, ref);
        } else {
                key.objectid = found_key.offset;
        }
        btrfs_free_path(path);

        if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
                return btrfs_get_dentry(root->fs_info->sb, key.objectid,
                                        found_key.offset, 0, 0);
        }

        key.type = BTRFS_INODE_ITEM_KEY;
        key.offset = 0;
        dentry = d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root));
        if (!IS_ERR(dentry))
                dentry->d_op = &btrfs_dentry_operations;
        return dentry;
fail:
        btrfs_free_path(path);
        return ERR_PTR(ret);
}

const struct export_operations btrfs_export_ops = {
        .encode_fh      = btrfs_encode_fh,
        .fh_to_dentry   = btrfs_fh_to_dentry,
        .fh_to_parent   = btrfs_fh_to_parent,
        .get_parent     = btrfs_get_parent,
};