/*
 * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
 * 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 as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 */

#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/fs.h>
#include <linux/fsnotify.h>
#include <linux/slab.h>
#include <linux/mempool.h>

#include "netfs.h"

static int pohmelfs_send_lock_trans(struct pohmelfs_inode *pi,
                u64 id, u64 start, u32 size, int type)
{
        struct inode *inode = &pi->vfs_inode;
        struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
        struct netfs_trans *t;
        struct netfs_cmd *cmd;
        int path_len, err;
        void *data;
        struct netfs_lock *l;
        int isize = (type & POHMELFS_LOCK_GRAB) ? 0 : sizeof(struct netfs_inode_info);

        err = pohmelfs_path_length(pi);
        if (err < 0)
                goto err_out_exit;

        path_len = err;

        err = -ENOMEM;
        t = netfs_trans_alloc(psb, path_len + sizeof(struct netfs_lock) + isize,
                        NETFS_TRANS_SINGLE_DST, 0);
        if (!t)
                goto err_out_exit;

        cmd = netfs_trans_current(t);
        data = cmd + 1;

        err = pohmelfs_construct_path_string(pi, data, path_len);
        if (err < 0)
                goto err_out_free;
        path_len = err;

        l = data + path_len;

        l->start = start;
        l->size = size;
        l->type = type;
        l->ino = pi->ino;

        cmd->cmd = NETFS_LOCK;
        cmd->start = 0;
        cmd->id = id;
        cmd->size = sizeof(struct netfs_lock) + path_len + isize;
        cmd->ext = path_len;
        cmd->csize = 0;

        netfs_convert_cmd(cmd);
        netfs_convert_lock(l);

        if (isize) {
                struct netfs_inode_info *info = (struct netfs_inode_info *)(l + 1);

                info->mode = inode->i_mode;
                info->nlink = inode->i_nlink;
                info->uid = inode->i_uid;
                info->gid = inode->i_gid;
                info->blocks = inode->i_blocks;
                info->rdev = inode->i_rdev;
                info->size = inode->i_size;
                info->version = inode->i_version;

                netfs_convert_inode_info(info);
        }

        netfs_trans_update(cmd, t, path_len + sizeof(struct netfs_lock) + isize);

        return netfs_trans_finish(t, psb);

err_out_free:
        netfs_trans_free(t);
err_out_exit:
        printk("%s: err: %d.\n", __func__, err);
        return err;
}

int pohmelfs_data_lock(struct pohmelfs_inode *pi, u64 start, u32 size, int type)
{
        struct pohmelfs_sb *psb = POHMELFS_SB(pi->vfs_inode.i_sb);
        struct pohmelfs_mcache *m;
        int err = -ENOMEM;
        struct iattr iattr;
        struct inode *inode = &pi->vfs_inode;

        dprintk("%s: %p: ino: %llu, start: %llu, size: %u, "
                        "type: %d, locked as: %d, owned: %d.\n",
                        __func__, &pi->vfs_inode, pi->ino,
                        start, size, type, pi->lock_type,
                        !!test_bit(NETFS_INODE_OWNED, &pi->state));

        if (!pohmelfs_need_lock(pi, type))
                return 0;

        m = pohmelfs_mcache_alloc(psb, start, size, NULL);
        if (IS_ERR(m))
                return PTR_ERR(m);

        err = pohmelfs_send_lock_trans(pi, m->gen, start, size,
                        type | POHMELFS_LOCK_GRAB);
        if (err)
                goto err_out_put;

        err = wait_for_completion_timeout(&m->complete, psb->mcache_timeout);
        if (err)
                err = m->err;
        else
                err = -ETIMEDOUT;

        if (err) {
                printk("%s: %p: ino: %llu, mgen: %llu, start: %llu, size: %u, err: %d.\n",
                        __func__, &pi->vfs_inode, pi->ino, m->gen, start, size, err);
        }

        if (err && (err != -ENOENT))
                goto err_out_put;

        if (!err) {
                netfs_convert_inode_info(&m->info);

                iattr.ia_valid = ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_SIZE | ATTR_ATIME;
                iattr.ia_mode = m->info.mode;
                iattr.ia_uid = m->info.uid;
                iattr.ia_gid = m->info.gid;
                iattr.ia_size = m->info.size;
                iattr.ia_atime = CURRENT_TIME;

                dprintk("%s: %p: ino: %llu, mgen: %llu, start: %llu, isize: %llu -> %llu.\n",
                        __func__, &pi->vfs_inode, pi->ino, m->gen, start, inode->i_size, m->info.size);

                err = pohmelfs_setattr_raw(inode, &iattr);
                if (!err) {
                        struct dentry *dentry = d_find_alias(inode);
                        if (dentry) {
                                fsnotify_change(dentry, iattr.ia_valid);
                                dput(dentry);
                        }
                }
        }

        pi->lock_type = type;
        set_bit(NETFS_INODE_OWNED, &pi->state);

        pohmelfs_mcache_put(psb, m);

        return 0;

err_out_put:
        pohmelfs_mcache_put(psb, m);
        return err;
}

int pohmelfs_data_unlock(struct pohmelfs_inode *pi, u64 start, u32 size, int type)
{
        dprintk("%s: %p: ino: %llu, start: %llu, size: %u, type: %d.\n",
                        __func__, &pi->vfs_inode, pi->ino, start, size, type);
        pi->lock_type = 0;
        clear_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &pi->state);
        clear_bit(NETFS_INODE_OWNED, &pi->state);
        return pohmelfs_send_lock_trans(pi, pi->ino, start, size, type);
}