/*
 *  Copyright (c) 2006,2007 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Andy Adamson <andros@citi.umich.edu>
 *  Fred Isaman <iisaman@umich.edu>
 *
 * permission is granted to use, copy, create derivative works and
 * redistribute this software and such derivative works for any purpose,
 * so long as the name of the university of michigan is not used in
 * any advertising or publicity pertaining to the use or distribution
 * of this software without specific, written prior authorization.  if
 * the above copyright notice or any other identification of the
 * university of michigan is included in any copy of any portion of
 * this software, then the disclaimer below must also be included.
 *
 * this software is provided as is, without representation from the
 * university of michigan as to its fitness for any purpose, and without
 * warranty by the university of michigan of any kind, either express
 * or implied, including without limitation the implied warranties of
 * merchantability and fitness for a particular purpose.  the regents
 * of the university of michigan shall not be liable for any damages,
 * including special, indirect, incidental, or consequential damages,
 * with respect to any claim arising out or in connection with the use
 * of the software, even if it has been or is hereafter advised of the
 * possibility of such damages.
 */

#include <linux/module.h>
#include <linux/blkdev.h>

#include "blocklayout.h"

#define NFSDBG_FACILITY         NFSDBG_PNFS_LD

static void
nfs4_encode_simple(__be32 *p, struct pnfs_block_volume *b)
{
        int i;

        *p++ = cpu_to_be32(1);
        *p++ = cpu_to_be32(b->type);
        *p++ = cpu_to_be32(b->simple.nr_sigs);
        for (i = 0; i < b->simple.nr_sigs; i++) {
                p = xdr_encode_hyper(p, b->simple.sigs[i].offset);
                p = xdr_encode_opaque(p, b->simple.sigs[i].sig,
                                         b->simple.sigs[i].sig_len);
        }
}

dev_t
bl_resolve_deviceid(struct nfs_server *server, struct pnfs_block_volume *b,
                gfp_t gfp_mask)
{
        struct net *net = server->nfs_client->cl_net;
        struct nfs_net *nn = net_generic(net, nfs_net_id);
        struct bl_dev_msg *reply = &nn->bl_mount_reply;
        struct bl_pipe_msg bl_pipe_msg;
        struct rpc_pipe_msg *msg = &bl_pipe_msg.msg;
        struct bl_msg_hdr *bl_msg;
        DECLARE_WAITQUEUE(wq, current);
        dev_t dev = 0;
        int rc;

        dprintk("%s CREATING PIPEFS MESSAGE\n", __func__);

        mutex_lock(&nn->bl_mutex);
        bl_pipe_msg.bl_wq = &nn->bl_wq;

        b->simple.len += 4;     /* single volume */
        if (b->simple.len > PAGE_SIZE)
                goto out_unlock;

        memset(msg, 0, sizeof(*msg));
        msg->len = sizeof(*bl_msg) + b->simple.len;
        msg->data = kzalloc(msg->len, gfp_mask);
        if (!msg->data)
                goto out_unlock;

        bl_msg = msg->data;
        bl_msg->type = BL_DEVICE_MOUNT;
        bl_msg->totallen = b->simple.len;
        nfs4_encode_simple(msg->data + sizeof(*bl_msg), b);

        dprintk("%s CALLING USERSPACE DAEMON\n", __func__);
        add_wait_queue(&nn->bl_wq, &wq);
        rc = rpc_queue_upcall(nn->bl_device_pipe, msg);
        if (rc < 0) {
                remove_wait_queue(&nn->bl_wq, &wq);
                goto out_free_data;
        }

        set_current_state(TASK_UNINTERRUPTIBLE);
        schedule();
        remove_wait_queue(&nn->bl_wq, &wq);

        if (reply->status != BL_DEVICE_REQUEST_PROC) {
                printk(KERN_WARNING "%s failed to decode device: %d\n",
                        __func__, reply->status);
                goto out_free_data;
        }

        dev = MKDEV(reply->major, reply->minor);
out_free_data:
        kfree(msg->data);
out_unlock:
        mutex_unlock(&nn->bl_mutex);
        return dev;
}

static ssize_t bl_pipe_downcall(struct file *filp, const char __user *src,
                         size_t mlen)
{
        struct nfs_net *nn = net_generic(file_inode(filp)->i_sb->s_fs_info,
                                         nfs_net_id);

        if (mlen != sizeof (struct bl_dev_msg))
                return -EINVAL;

        if (copy_from_user(&nn->bl_mount_reply, src, mlen) != 0)
                return -EFAULT;

        wake_up(&nn->bl_wq);

        return mlen;
}

static void bl_pipe_destroy_msg(struct rpc_pipe_msg *msg)
{
        struct bl_pipe_msg *bl_pipe_msg =
                container_of(msg, struct bl_pipe_msg, msg);

        if (msg->errno >= 0)
                return;
        wake_up(bl_pipe_msg->bl_wq);
}

static const struct rpc_pipe_ops bl_upcall_ops = {
        .upcall         = rpc_pipe_generic_upcall,
        .downcall       = bl_pipe_downcall,
        .destroy_msg    = bl_pipe_destroy_msg,
};

static int nfs4blocklayout_register_sb(struct super_block *sb,
                                            struct rpc_pipe *pipe)
{
        struct dentry *dir;
        int err;

        dir = rpc_d_lookup_sb(sb, NFS_PIPE_DIRNAME);
        if (dir == NULL)
                return -ENOENT;
        err = rpc_mkpipe_dentry(dir, "blocklayout", NULL, pipe);
        dput(dir);
        return err;
}

static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
                           void *ptr)
{
        struct super_block *sb = ptr;
        struct net *net = sb->s_fs_info;
        struct nfs_net *nn = net_generic(net, nfs_net_id);
        int ret = 0;

        if (!try_module_get(THIS_MODULE))
                return 0;

        if (nn->bl_device_pipe == NULL) {
                module_put(THIS_MODULE);
                return 0;
        }

        switch (event) {
        case RPC_PIPEFS_MOUNT:
                ret = nfs4blocklayout_register_sb(sb, nn->bl_device_pipe);
                break;
        case RPC_PIPEFS_UMOUNT:
                rpc_unlink(nn->bl_device_pipe);
                break;
        default:
                ret = -ENOTSUPP;
                break;
        }
        module_put(THIS_MODULE);
        return ret;
}

static struct notifier_block nfs4blocklayout_block = {
        .notifier_call = rpc_pipefs_event,
};

static int nfs4blocklayout_register_net(struct net *net, struct rpc_pipe *pipe)
{
        struct super_block *pipefs_sb;
        int ret;

        pipefs_sb = rpc_get_sb_net(net);
        if (!pipefs_sb)
                return 0;
        ret = nfs4blocklayout_register_sb(pipefs_sb, pipe);
        rpc_put_sb_net(net);
        return ret;
}

static void nfs4blocklayout_unregister_net(struct net *net,
                                           struct rpc_pipe *pipe)
{
        struct super_block *pipefs_sb;

        pipefs_sb = rpc_get_sb_net(net);
        if (pipefs_sb) {
                rpc_unlink(pipe);
                rpc_put_sb_net(net);
        }
}

static int nfs4blocklayout_net_init(struct net *net)
{
        struct nfs_net *nn = net_generic(net, nfs_net_id);
        int err;

        mutex_init(&nn->bl_mutex);
        init_waitqueue_head(&nn->bl_wq);
        nn->bl_device_pipe = rpc_mkpipe_data(&bl_upcall_ops, 0);
        if (IS_ERR(nn->bl_device_pipe))
                return PTR_ERR(nn->bl_device_pipe);
        err = nfs4blocklayout_register_net(net, nn->bl_device_pipe);
        if (unlikely(err))
                rpc_destroy_pipe_data(nn->bl_device_pipe);
        return err;
}

static void nfs4blocklayout_net_exit(struct net *net)
{
        struct nfs_net *nn = net_generic(net, nfs_net_id);

        nfs4blocklayout_unregister_net(net, nn->bl_device_pipe);
        rpc_destroy_pipe_data(nn->bl_device_pipe);
        nn->bl_device_pipe = NULL;
}

static struct pernet_operations nfs4blocklayout_net_ops = {
        .init = nfs4blocklayout_net_init,
        .exit = nfs4blocklayout_net_exit,
};

int __init bl_init_pipefs(void)
{
        int ret;

        ret = rpc_pipefs_notifier_register(&nfs4blocklayout_block);
        if (ret)
                goto out;
        ret = register_pernet_subsys(&nfs4blocklayout_net_ops);
        if (ret)
                goto out_unregister_notifier;
        return 0;

out_unregister_notifier:
        rpc_pipefs_notifier_unregister(&nfs4blocklayout_block);
out:
        return ret;
}

void bl_cleanup_pipefs(void)
{
        rpc_pipefs_notifier_unregister(&nfs4blocklayout_block);
        unregister_pernet_subsys(&nfs4blocklayout_net_ops);
}