/*

  *  Copyright (c) 2004 The Regents of the University of Michigan.

  *  Copyright (c) 2012 Jeff Layton <jlayton@redhat.com>

  *  All rights reserved.
  *
  *  Andy Adamson <andros@citi.umich.edu>
  *
  *  Redistribution and use in source and binary forms, with or without
  *  modification, are permitted provided that the following conditions
  *  are met:
  *
  *  1. Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
  *  3. Neither the name of the University nor the names of its
  *     contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
  *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
  *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  */

  #include <linux/file.h>

  #include <linux/slab.h>

  #include <linux/namei.h>

  #include <linux/crypto.h>

  #include <linux/sched.h>

  #include <linux/fs.h>

  #include <linux/module.h>

  #include <net/net_namespace.h>
  #include <linux/sunrpc/rpc_pipe_fs.h>
  #include <linux/sunrpc/clnt.h>
  #include <linux/nfsd/cld.h>

  
  #include "nfsd.h"
  #include "state.h"

  #include "vfs.h"

  #include "netns.h"

  
  #define NFSDDBG_FACILITY                NFSDDBG_PROC

  /* Declarations */
  struct nfsd4_client_tracking_ops {
  	int (*init)(struct net *);
  	void (*exit)(struct net *);
  	void (*create)(struct nfs4_client *);
  	void (*remove)(struct nfs4_client *);
  	int (*check)(struct nfs4_client *);

  	void (*grace_done)(struct nfsd_net *, time_t);

  };

  /* Globals */

  static char user_recovery_dirname[PATH_MAX] = "/var/lib/nfs/v4recovery";

  static int
  nfs4_save_creds(const struct cred **original_creds)

  {

  	struct cred *new;
  
  	new = prepare_creds();
  	if (!new)
  		return -ENOMEM;

  	new->fsuid = GLOBAL_ROOT_UID;
  	new->fsgid = GLOBAL_ROOT_GID;

  	*original_creds = override_creds(new);
  	put_cred(new);
  	return 0;

  }
  
  static void

  nfs4_reset_creds(const struct cred *original)

  {

  	revert_creds(original);

  }

  static void
  md5_to_hex(char *out, char *md5)
  {
  	int i;
  
  	for (i=0; i<16; i++) {
  		unsigned char c = md5[i];
  
  		*out++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
  		*out++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
  	}
  	*out = '\0';
  }

  static int
  nfs4_make_rec_clidname(char *dname, const struct xdr_netobj *clname)

  {
  	struct xdr_netobj cksum;

  	struct hash_desc desc;

  	struct scatterlist sg;

  	int status;

  
  	dprintk("NFSD: nfs4_make_rec_clidname for %.*s
  ",
  			clname->len, clname->data);

  	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
  	desc.tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);

  	if (IS_ERR(desc.tfm)) {
  		status = PTR_ERR(desc.tfm);

  		goto out_no_tfm;

  	}

  	cksum.len = crypto_hash_digestsize(desc.tfm);

  	cksum.data = kmalloc(cksum.len, GFP_KERNEL);

  	if (cksum.data == NULL) {
  		status = -ENOMEM;

   		goto out;

  	}

  	sg_init_one(&sg, clname->data, clname->len);

  	status = crypto_hash_digest(&desc, &sg, sg.length, cksum.data);
  	if (status)

  		goto out;

  
  	md5_to_hex(dname, cksum.data);

  	status = 0;

  out:

  	kfree(cksum.data);

  	crypto_free_hash(desc.tfm);
  out_no_tfm:

  	return status;
  }

  /*
   * If we had an error generating the recdir name for the legacy tracker
   * then warn the admin. If the error doesn't appear to be transient,
   * then disable recovery tracking.
   */
  static void

  legacy_recdir_name_error(struct nfs4_client *clp, int error)

  {
  	printk(KERN_ERR "NFSD: unable to generate recoverydir "
  			"name (%d).
  ", error);
  
  	/*
  	 * if the algorithm just doesn't exist, then disable the recovery
  	 * tracker altogether. The crypto libs will generally return this if
  	 * FIPS is enabled as well.
  	 */
  	if (error == -ENOENT) {
  		printk(KERN_ERR "NFSD: disabling legacy clientid tracking. "
  			"Reboot recovery will not function correctly!
  ");

  		nfsd4_client_tracking_exit(clp->net);

  	}
  }

  static void
  nfsd4_create_clid_dir(struct nfs4_client *clp)

  {

  	const struct cred *original_cred;

  	char dname[HEXDIR_LEN];

  	struct dentry *dir, *dentry;

  	struct nfs4_client_reclaim *crp;

  	int status;

  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

  	if (test_and_set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))

  		return;

  	if (!nn->rec_file)

  		return;

  
  	status = nfs4_make_rec_clidname(dname, &clp->cl_name);
  	if (status)

  		return legacy_recdir_name_error(clp, status);

  	status = nfs4_save_creds(&original_cred);
  	if (status < 0)

  		return;

  	status = mnt_want_write_file(nn->rec_file);

  	if (status)
  		return;

  	dir = nn->rec_file->f_path.dentry;

  	/* lock the parent */

  	mutex_lock(&dir->d_inode->i_mutex);

  	dentry = lookup_one_len(dname, dir, HEXDIR_LEN-1);

  	if (IS_ERR(dentry)) {
  		status = PTR_ERR(dentry);
  		goto out_unlock;
  	}

  	if (dentry->d_inode)

  		/*
  		 * In the 4.1 case, where we're called from
  		 * reclaim_complete(), records from the previous reboot
  		 * may still be left, so this is OK.
  		 *
  		 * In the 4.0 case, we should never get here; but we may
  		 * as well be forgiving and just succeed silently.
  		 */

  		goto out_put;

  	status = vfs_mkdir(dir->d_inode, dentry, S_IRWXU);

  out_put:
  	dput(dentry);
  out_unlock:

  	mutex_unlock(&dir->d_inode->i_mutex);

  	if (status == 0) {

  		if (nn->in_grace) {

  			crp = nfs4_client_to_reclaim(dname, nn);

  			if (crp)
  				crp->cr_clp = clp;
  		}

  		vfs_fsync(nn->rec_file, 0);

  	} else {

  		printk(KERN_ERR "NFSD: failed to write recovery record"
  				" (err %d); please check that %s exists"
  				" and is writeable", status,
  				user_recovery_dirname);

  	}

  	mnt_drop_write_file(nn->rec_file);

  	nfs4_reset_creds(original_cred);

  }

  typedef int (recdir_func)(struct dentry *, struct dentry *, struct nfsd_net *);

  struct name_list {
  	char name[HEXDIR_LEN];

  	struct list_head list;
  };

  struct nfs4_dir_ctx {
  	struct dir_context ctx;
  	struct list_head names;
  };

  static int

  nfsd4_build_namelist(void *arg, const char *name, int namlen,

  		loff_t offset, u64 ino, unsigned int d_type)

  {

  	struct nfs4_dir_ctx *ctx = arg;

  	struct name_list *entry;

  	if (namlen != HEXDIR_LEN - 1)

  		return 0;

  	entry = kmalloc(sizeof(struct name_list), GFP_KERNEL);
  	if (entry == NULL)

  		return -ENOMEM;

  	memcpy(entry->name, name, HEXDIR_LEN - 1);
  	entry->name[HEXDIR_LEN - 1] = '\0';

  	list_add(&entry->list, &ctx->names);

  	return 0;
  }
  
  static int

  nfsd4_list_rec_dir(recdir_func *f, struct nfsd_net *nn)

  {

  	const struct cred *original_cred;

  	struct dentry *dir = nn->rec_file->f_path.dentry;

  	struct nfs4_dir_ctx ctx = {
  		.ctx.actor = nfsd4_build_namelist,
  		.names = LIST_HEAD_INIT(ctx.names)
  	};

  	int status;

  	status = nfs4_save_creds(&original_cred);
  	if (status < 0)
  		return status;

  	status = vfs_llseek(nn->rec_file, 0, SEEK_SET);

  	if (status < 0) {
  		nfs4_reset_creds(original_cred);
  		return status;
  	}

  	status = iterate_dir(nn->rec_file, &ctx.ctx);

  	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);

  	while (!list_empty(&ctx.names)) {

  		struct name_list *entry;

  		entry = list_entry(ctx.names.next, struct name_list, list);

  		if (!status) {
  			struct dentry *dentry;
  			dentry = lookup_one_len(entry->name, dir, HEXDIR_LEN-1);
  			if (IS_ERR(dentry)) {
  				status = PTR_ERR(dentry);
  				break;
  			}

  			status = f(dir, dentry, nn);

  			dput(dentry);

  		}

  		list_del(&entry->list);
  		kfree(entry);

  	}

  	mutex_unlock(&dir->d_inode->i_mutex);

  	nfs4_reset_creds(original_cred);

  	return status;
  }
  
  static int

  nfsd4_unlink_clid_dir(char *name, int namlen, struct nfsd_net *nn)

  {

  	struct dentry *dir, *dentry;

  	int status;
  
  	dprintk("NFSD: nfsd4_unlink_clid_dir. name %.*s
  ", namlen, name);

  	dir = nn->rec_file->f_path.dentry;

  	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
  	dentry = lookup_one_len(name, dir, namlen);

  	if (IS_ERR(dentry)) {
  		status = PTR_ERR(dentry);

  		goto out_unlock;

  	}
  	status = -ENOENT;
  	if (!dentry->d_inode)
  		goto out;

  	status = vfs_rmdir(dir->d_inode, dentry);

  out:
  	dput(dentry);

  out_unlock:

  	mutex_unlock(&dir->d_inode->i_mutex);

  	return status;
  }

  static void

  nfsd4_remove_clid_dir(struct nfs4_client *clp)
  {

  	const struct cred *original_cred;

  	struct nfs4_client_reclaim *crp;

  	char dname[HEXDIR_LEN];

  	int status;

  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

  	if (!nn->rec_file || !test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))

  		return;

  	status = nfs4_make_rec_clidname(dname, &clp->cl_name);
  	if (status)

  		return legacy_recdir_name_error(clp, status);

  	status = mnt_want_write_file(nn->rec_file);

  	if (status)
  		goto out;

  	clear_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);

  
  	status = nfs4_save_creds(&original_cred);
  	if (status < 0)

  		goto out_drop_write;

  	status = nfsd4_unlink_clid_dir(dname, HEXDIR_LEN-1, nn);

  	nfs4_reset_creds(original_cred);

  	if (status == 0) {

  		vfs_fsync(nn->rec_file, 0);

  		if (nn->in_grace) {

  			/* remove reclaim record */

  			crp = nfsd4_find_reclaim_client(dname, nn);

  			if (crp)

  				nfs4_remove_reclaim_record(crp, nn);

  		}
  	}

  out_drop_write:

  	mnt_drop_write_file(nn->rec_file);

  out:

  	if (status)
  		printk("NFSD: Failed to remove expired client state directory"

  				" %.*s
  ", HEXDIR_LEN, dname);

  }
  
  static int

  purge_old(struct dentry *parent, struct dentry *child, struct nfsd_net *nn)

  {
  	int status;

  	if (nfs4_has_reclaimed_state(child->d_name.name, nn))

  		return 0;

  	status = vfs_rmdir(parent->d_inode, child);

  	if (status)

  		printk("failed to remove client recovery directory %pd
  ",
  				child);

  	/* Keep trying, success or failure: */

  	return 0;

  }

  static void

  nfsd4_recdir_purge_old(struct nfsd_net *nn, time_t boot_time)

  {

  	int status;

  	nn->in_grace = false;

  	if (!nn->rec_file)

  		return;

  	status = mnt_want_write_file(nn->rec_file);

  	if (status)
  		goto out;

  	status = nfsd4_list_rec_dir(purge_old, nn);

  	if (status == 0)

  		vfs_fsync(nn->rec_file, 0);
  	mnt_drop_write_file(nn->rec_file);

  out:

  	nfs4_release_reclaim(nn);

  	if (status)
  		printk("nfsd4: failed to purge old clients from recovery"

  			" directory %pD
  ", nn->rec_file);

  }
  
  static int

  load_recdir(struct dentry *parent, struct dentry *child, struct nfsd_net *nn)

  {
  	if (child->d_name.len != HEXDIR_LEN - 1) {

  		printk("nfsd4: illegal name %pd in recovery directory
  ",
  				child);

  		/* Keep trying; maybe the others are OK: */

  		return 0;

  	}

  	nfs4_client_to_reclaim(child->d_name.name, nn);

  	return 0;

  }

  static int

  nfsd4_recdir_load(struct net *net) {

  	int status;

  	struct nfsd_net *nn =  net_generic(net, nfsd_net_id);

  	if (!nn->rec_file)

  		return 0;

  	status = nfsd4_list_rec_dir(load_recdir, nn);

  	if (status)
  		printk("nfsd4: failed loading clients from recovery"

  			" directory %pD
  ", nn->rec_file);

  	return status;
  }
  
  /*
   * Hold reference to the recovery directory.
   */

  static int

  nfsd4_init_recdir(struct net *net)

  {

  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

  	const struct cred *original_cred;
  	int status;

  
  	printk("NFSD: Using %s as the NFSv4 state recovery directory
  ",

  			user_recovery_dirname);

  	BUG_ON(nn->rec_file);

  	status = nfs4_save_creds(&original_cred);
  	if (status < 0) {
  		printk("NFSD: Unable to change credentials to find recovery"
  		       " directory: error %d
  ",
  		       status);

  		return status;

  	}

  	nn->rec_file = filp_open(user_recovery_dirname, O_RDONLY | O_DIRECTORY, 0);
  	if (IS_ERR(nn->rec_file)) {

  		printk("NFSD: unable to find recovery directory %s
  ",

  				user_recovery_dirname);

  		status = PTR_ERR(nn->rec_file);
  		nn->rec_file = NULL;

  	}

  	nfs4_reset_creds(original_cred);

  	if (!status)

  		nn->in_grace = true;

  	return status;

  }

  
  static int
  nfs4_legacy_state_init(struct net *net)
  {
  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  	int i;
  
  	nn->reclaim_str_hashtbl = kmalloc(sizeof(struct list_head) *
  					  CLIENT_HASH_SIZE, GFP_KERNEL);
  	if (!nn->reclaim_str_hashtbl)
  		return -ENOMEM;
  
  	for (i = 0; i < CLIENT_HASH_SIZE; i++)
  		INIT_LIST_HEAD(&nn->reclaim_str_hashtbl[i]);
  	nn->reclaim_str_hashtbl_size = 0;
  
  	return 0;
  }
  
  static void
  nfs4_legacy_state_shutdown(struct net *net)
  {
  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  
  	kfree(nn->reclaim_str_hashtbl);
  }

  static int
  nfsd4_load_reboot_recovery_data(struct net *net)
  {
  	int status;

  	status = nfsd4_init_recdir(net);

  	if (!status)
  		status = nfsd4_recdir_load(net);

  	if (status)
  		printk(KERN_ERR "NFSD: Failure reading reboot recovery data
  ");
  	return status;
  }
  
  static int
  nfsd4_legacy_tracking_init(struct net *net)
  {
  	int status;

  	/* XXX: The legacy code won't work in a container */
  	if (net != &init_net) {
  		WARN(1, KERN_ERR "NFSD: attempt to initialize legacy client "
  			"tracking in a container!
  ");
  		return -EINVAL;
  	}

  	status = nfs4_legacy_state_init(net);

  	if (status)

  		return status;
  
  	status = nfsd4_load_reboot_recovery_data(net);
  	if (status)
  		goto err;
  	return 0;
  
  err:
  	nfs4_legacy_state_shutdown(net);

  	return status;
  }
  
  static void

  nfsd4_shutdown_recdir(struct nfsd_net *nn)

  {

  	if (!nn->rec_file)

  		return;

  	fput(nn->rec_file);
  	nn->rec_file = NULL;

  }

  static void
  nfsd4_legacy_tracking_exit(struct net *net)
  {

  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  
  	nfs4_release_reclaim(nn);

  	nfsd4_shutdown_recdir(nn);

  	nfs4_legacy_state_shutdown(net);

  }

  /*
   * Change the NFSv4 recovery directory to recdir.
   */
  int
  nfs4_reset_recoverydir(char *recdir)
  {
  	int status;
  	struct path path;
  
  	status = kern_path(recdir, LOOKUP_FOLLOW, &path);
  	if (status)
  		return status;
  	status = -ENOTDIR;
  	if (S_ISDIR(path.dentry->d_inode->i_mode)) {
  		strcpy(user_recovery_dirname, recdir);
  		status = 0;
  	}
  	path_put(&path);
  	return status;
  }
  
  char *
  nfs4_recoverydir(void)
  {
  	return user_recovery_dirname;
  }

  
  static int
  nfsd4_check_legacy_client(struct nfs4_client *clp)
  {

  	int status;
  	char dname[HEXDIR_LEN];

  	struct nfs4_client_reclaim *crp;

  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

  	/* did we already find that this client is stable? */
  	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
  		return 0;

  	status = nfs4_make_rec_clidname(dname, &clp->cl_name);
  	if (status) {

  		legacy_recdir_name_error(clp, status);

  		return status;
  	}

  	/* look for it in the reclaim hashtable otherwise */

  	crp = nfsd4_find_reclaim_client(dname, nn);

  	if (crp) {

  		set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);

  		crp->cr_clp = clp;

  		return 0;
  	}
  
  	return -ENOENT;
  }
  
  static struct nfsd4_client_tracking_ops nfsd4_legacy_tracking_ops = {

  	.init		= nfsd4_legacy_tracking_init,

  	.exit		= nfsd4_legacy_tracking_exit,
  	.create		= nfsd4_create_clid_dir,
  	.remove		= nfsd4_remove_clid_dir,
  	.check		= nfsd4_check_legacy_client,
  	.grace_done	= nfsd4_recdir_purge_old,
  };

  /* Globals */
  #define NFSD_PIPE_DIR		"nfsd"
  #define NFSD_CLD_PIPE		"cld"
  
  /* per-net-ns structure for holding cld upcall info */
  struct cld_net {
  	struct rpc_pipe		*cn_pipe;
  	spinlock_t		 cn_lock;
  	struct list_head	 cn_list;
  	unsigned int		 cn_xid;
  };
  
  struct cld_upcall {
  	struct list_head	 cu_list;
  	struct cld_net		*cu_net;
  	struct task_struct	*cu_task;
  	struct cld_msg		 cu_msg;
  };
  
  static int
  __cld_pipe_upcall(struct rpc_pipe *pipe, struct cld_msg *cmsg)
  {
  	int ret;
  	struct rpc_pipe_msg msg;
  
  	memset(&msg, 0, sizeof(msg));
  	msg.data = cmsg;
  	msg.len = sizeof(*cmsg);
  
  	/*
  	 * Set task state before we queue the upcall. That prevents
  	 * wake_up_process in the downcall from racing with schedule.
  	 */
  	set_current_state(TASK_UNINTERRUPTIBLE);
  	ret = rpc_queue_upcall(pipe, &msg);
  	if (ret < 0) {
  		set_current_state(TASK_RUNNING);
  		goto out;
  	}
  
  	schedule();
  	set_current_state(TASK_RUNNING);
  
  	if (msg.errno < 0)
  		ret = msg.errno;
  out:
  	return ret;
  }
  
  static int
  cld_pipe_upcall(struct rpc_pipe *pipe, struct cld_msg *cmsg)
  {
  	int ret;
  
  	/*
  	 * -EAGAIN occurs when pipe is closed and reopened while there are
  	 *  upcalls queued.
  	 */
  	do {
  		ret = __cld_pipe_upcall(pipe, cmsg);
  	} while (ret == -EAGAIN);
  
  	return ret;
  }
  
  static ssize_t
  cld_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
  {
  	struct cld_upcall *tmp, *cup;

  	struct cld_msg __user *cmsg = (struct cld_msg __user *)src;

  	uint32_t xid;
  	struct nfsd_net *nn = net_generic(filp->f_dentry->d_sb->s_fs_info,
  						nfsd_net_id);
  	struct cld_net *cn = nn->cld_net;
  
  	if (mlen != sizeof(*cmsg)) {

  		dprintk("%s: got %zu bytes, expected %zu
  ", __func__, mlen,

  			sizeof(*cmsg));
  		return -EINVAL;
  	}
  
  	/* copy just the xid so we can try to find that */
  	if (copy_from_user(&xid, &cmsg->cm_xid, sizeof(xid)) != 0) {
  		dprintk("%s: error when copying xid from userspace", __func__);
  		return -EFAULT;
  	}
  
  	/* walk the list and find corresponding xid */
  	cup = NULL;
  	spin_lock(&cn->cn_lock);
  	list_for_each_entry(tmp, &cn->cn_list, cu_list) {
  		if (get_unaligned(&tmp->cu_msg.cm_xid) == xid) {
  			cup = tmp;
  			list_del_init(&cup->cu_list);
  			break;
  		}
  	}
  	spin_unlock(&cn->cn_lock);
  
  	/* couldn't find upcall? */
  	if (!cup) {

  		dprintk("%s: couldn't find upcall -- xid=%u
  ", __func__, xid);

  		return -EINVAL;
  	}
  
  	if (copy_from_user(&cup->cu_msg, src, mlen) != 0)
  		return -EFAULT;
  
  	wake_up_process(cup->cu_task);
  	return mlen;
  }
  
  static void
  cld_pipe_destroy_msg(struct rpc_pipe_msg *msg)
  {
  	struct cld_msg *cmsg = msg->data;
  	struct cld_upcall *cup = container_of(cmsg, struct cld_upcall,
  						 cu_msg);
  
  	/* errno >= 0 means we got a downcall */
  	if (msg->errno >= 0)
  		return;
  
  	wake_up_process(cup->cu_task);
  }
  
  static const struct rpc_pipe_ops cld_upcall_ops = {
  	.upcall		= rpc_pipe_generic_upcall,
  	.downcall	= cld_pipe_downcall,
  	.destroy_msg	= cld_pipe_destroy_msg,
  };
  
  static struct dentry *
  nfsd4_cld_register_sb(struct super_block *sb, struct rpc_pipe *pipe)
  {
  	struct dentry *dir, *dentry;
  
  	dir = rpc_d_lookup_sb(sb, NFSD_PIPE_DIR);
  	if (dir == NULL)
  		return ERR_PTR(-ENOENT);
  	dentry = rpc_mkpipe_dentry(dir, NFSD_CLD_PIPE, NULL, pipe);
  	dput(dir);
  	return dentry;
  }
  
  static void
  nfsd4_cld_unregister_sb(struct rpc_pipe *pipe)
  {
  	if (pipe->dentry)
  		rpc_unlink(pipe->dentry);
  }
  
  static struct dentry *
  nfsd4_cld_register_net(struct net *net, struct rpc_pipe *pipe)
  {
  	struct super_block *sb;
  	struct dentry *dentry;
  
  	sb = rpc_get_sb_net(net);
  	if (!sb)
  		return NULL;
  	dentry = nfsd4_cld_register_sb(sb, pipe);
  	rpc_put_sb_net(net);
  	return dentry;
  }
  
  static void
  nfsd4_cld_unregister_net(struct net *net, struct rpc_pipe *pipe)
  {
  	struct super_block *sb;
  
  	sb = rpc_get_sb_net(net);
  	if (sb) {
  		nfsd4_cld_unregister_sb(pipe);
  		rpc_put_sb_net(net);
  	}
  }
  
  /* Initialize rpc_pipefs pipe for communication with client tracking daemon */
  static int
  nfsd4_init_cld_pipe(struct net *net)
  {
  	int ret;
  	struct dentry *dentry;
  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  	struct cld_net *cn;
  
  	if (nn->cld_net)
  		return 0;
  
  	cn = kzalloc(sizeof(*cn), GFP_KERNEL);
  	if (!cn) {
  		ret = -ENOMEM;
  		goto err;
  	}
  
  	cn->cn_pipe = rpc_mkpipe_data(&cld_upcall_ops, RPC_PIPE_WAIT_FOR_OPEN);
  	if (IS_ERR(cn->cn_pipe)) {
  		ret = PTR_ERR(cn->cn_pipe);
  		goto err;
  	}
  	spin_lock_init(&cn->cn_lock);
  	INIT_LIST_HEAD(&cn->cn_list);
  
  	dentry = nfsd4_cld_register_net(net, cn->cn_pipe);
  	if (IS_ERR(dentry)) {
  		ret = PTR_ERR(dentry);
  		goto err_destroy_data;
  	}
  
  	cn->cn_pipe->dentry = dentry;
  	nn->cld_net = cn;
  	return 0;
  
  err_destroy_data:
  	rpc_destroy_pipe_data(cn->cn_pipe);
  err:
  	kfree(cn);
  	printk(KERN_ERR "NFSD: unable to create nfsdcld upcall pipe (%d)
  ",
  			ret);
  	return ret;
  }
  
  static void
  nfsd4_remove_cld_pipe(struct net *net)
  {
  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  	struct cld_net *cn = nn->cld_net;
  
  	nfsd4_cld_unregister_net(net, cn->cn_pipe);
  	rpc_destroy_pipe_data(cn->cn_pipe);
  	kfree(nn->cld_net);
  	nn->cld_net = NULL;
  }
  
  static struct cld_upcall *
  alloc_cld_upcall(struct cld_net *cn)
  {
  	struct cld_upcall *new, *tmp;
  
  	new = kzalloc(sizeof(*new), GFP_KERNEL);
  	if (!new)
  		return new;
  
  	/* FIXME: hard cap on number in flight? */
  restart_search:
  	spin_lock(&cn->cn_lock);
  	list_for_each_entry(tmp, &cn->cn_list, cu_list) {
  		if (tmp->cu_msg.cm_xid == cn->cn_xid) {
  			cn->cn_xid++;
  			spin_unlock(&cn->cn_lock);
  			goto restart_search;
  		}
  	}
  	new->cu_task = current;
  	new->cu_msg.cm_vers = CLD_UPCALL_VERSION;
  	put_unaligned(cn->cn_xid++, &new->cu_msg.cm_xid);
  	new->cu_net = cn;
  	list_add(&new->cu_list, &cn->cn_list);
  	spin_unlock(&cn->cn_lock);
  
  	dprintk("%s: allocated xid %u
  ", __func__, new->cu_msg.cm_xid);
  
  	return new;
  }
  
  static void
  free_cld_upcall(struct cld_upcall *victim)
  {
  	struct cld_net *cn = victim->cu_net;
  
  	spin_lock(&cn->cn_lock);
  	list_del(&victim->cu_list);
  	spin_unlock(&cn->cn_lock);
  	kfree(victim);
  }
  
  /* Ask daemon to create a new record */
  static void
  nfsd4_cld_create(struct nfs4_client *clp)
  {
  	int ret;
  	struct cld_upcall *cup;

  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

  	struct cld_net *cn = nn->cld_net;
  
  	/* Don't upcall if it's already stored */
  	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
  		return;
  
  	cup = alloc_cld_upcall(cn);
  	if (!cup) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  
  	cup->cu_msg.cm_cmd = Cld_Create;
  	cup->cu_msg.cm_u.cm_name.cn_len = clp->cl_name.len;
  	memcpy(cup->cu_msg.cm_u.cm_name.cn_id, clp->cl_name.data,
  			clp->cl_name.len);
  
  	ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_msg);
  	if (!ret) {
  		ret = cup->cu_msg.cm_status;
  		set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
  	}
  
  	free_cld_upcall(cup);
  out_err:
  	if (ret)
  		printk(KERN_ERR "NFSD: Unable to create client "
  				"record on stable storage: %d
  ", ret);
  }
  
  /* Ask daemon to create a new record */
  static void
  nfsd4_cld_remove(struct nfs4_client *clp)
  {
  	int ret;
  	struct cld_upcall *cup;

  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

  	struct cld_net *cn = nn->cld_net;
  
  	/* Don't upcall if it's already removed */
  	if (!test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
  		return;
  
  	cup = alloc_cld_upcall(cn);
  	if (!cup) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  
  	cup->cu_msg.cm_cmd = Cld_Remove;
  	cup->cu_msg.cm_u.cm_name.cn_len = clp->cl_name.len;
  	memcpy(cup->cu_msg.cm_u.cm_name.cn_id, clp->cl_name.data,
  			clp->cl_name.len);
  
  	ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_msg);
  	if (!ret) {
  		ret = cup->cu_msg.cm_status;
  		clear_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
  	}
  
  	free_cld_upcall(cup);
  out_err:
  	if (ret)
  		printk(KERN_ERR "NFSD: Unable to remove client "
  				"record from stable storage: %d
  ", ret);
  }
  
  /* Check for presence of a record, and update its timestamp */
  static int
  nfsd4_cld_check(struct nfs4_client *clp)
  {
  	int ret;
  	struct cld_upcall *cup;

  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

  	struct cld_net *cn = nn->cld_net;
  
  	/* Don't upcall if one was already stored during this grace pd */
  	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
  		return 0;
  
  	cup = alloc_cld_upcall(cn);
  	if (!cup) {
  		printk(KERN_ERR "NFSD: Unable to check client record on "
  				"stable storage: %d
  ", -ENOMEM);
  		return -ENOMEM;
  	}
  
  	cup->cu_msg.cm_cmd = Cld_Check;
  	cup->cu_msg.cm_u.cm_name.cn_len = clp->cl_name.len;
  	memcpy(cup->cu_msg.cm_u.cm_name.cn_id, clp->cl_name.data,
  			clp->cl_name.len);
  
  	ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_msg);
  	if (!ret) {
  		ret = cup->cu_msg.cm_status;
  		set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
  	}
  
  	free_cld_upcall(cup);
  	return ret;
  }
  
  static void

  nfsd4_cld_grace_done(struct nfsd_net *nn, time_t boot_time)

  {
  	int ret;
  	struct cld_upcall *cup;

  	struct cld_net *cn = nn->cld_net;
  
  	cup = alloc_cld_upcall(cn);
  	if (!cup) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  
  	cup->cu_msg.cm_cmd = Cld_GraceDone;
  	cup->cu_msg.cm_u.cm_gracetime = (int64_t)boot_time;
  	ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_msg);
  	if (!ret)
  		ret = cup->cu_msg.cm_status;
  
  	free_cld_upcall(cup);
  out_err:
  	if (ret)
  		printk(KERN_ERR "NFSD: Unable to end grace period: %d
  ", ret);
  }
  
  static struct nfsd4_client_tracking_ops nfsd4_cld_tracking_ops = {
  	.init		= nfsd4_init_cld_pipe,
  	.exit		= nfsd4_remove_cld_pipe,
  	.create		= nfsd4_cld_create,
  	.remove		= nfsd4_cld_remove,
  	.check		= nfsd4_cld_check,
  	.grace_done	= nfsd4_cld_grace_done,
  };

  /* upcall via usermodehelper */
  static char cltrack_prog[PATH_MAX] = "/sbin/nfsdcltrack";
  module_param_string(cltrack_prog, cltrack_prog, sizeof(cltrack_prog),
  			S_IRUGO|S_IWUSR);
  MODULE_PARM_DESC(cltrack_prog, "Path to the nfsdcltrack upcall program");

  static bool cltrack_legacy_disable;
  module_param(cltrack_legacy_disable, bool, S_IRUGO|S_IWUSR);
  MODULE_PARM_DESC(cltrack_legacy_disable,
  		"Disable legacy recoverydir conversion. Default: false");
  
  #define LEGACY_TOPDIR_ENV_PREFIX "NFSDCLTRACK_LEGACY_TOPDIR="
  #define LEGACY_RECDIR_ENV_PREFIX "NFSDCLTRACK_LEGACY_RECDIR="
  
  static char *
  nfsd4_cltrack_legacy_topdir(void)
  {
  	int copied;
  	size_t len;
  	char *result;
  
  	if (cltrack_legacy_disable)
  		return NULL;
  
  	len = strlen(LEGACY_TOPDIR_ENV_PREFIX) +
  		strlen(nfs4_recoverydir()) + 1;
  
  	result = kmalloc(len, GFP_KERNEL);
  	if (!result)
  		return result;
  
  	copied = snprintf(result, len, LEGACY_TOPDIR_ENV_PREFIX "%s",
  				nfs4_recoverydir());
  	if (copied >= len) {
  		/* just return nothing if output was truncated */
  		kfree(result);
  		return NULL;
  	}
  
  	return result;
  }
  
  static char *

  nfsd4_cltrack_legacy_recdir(const struct xdr_netobj *name)

  {
  	int copied;
  	size_t len;
  	char *result;
  
  	if (cltrack_legacy_disable)
  		return NULL;
  
  	/* +1 is for '/' between "topdir" and "recdir" */
  	len = strlen(LEGACY_RECDIR_ENV_PREFIX) +
  		strlen(nfs4_recoverydir()) + 1 + HEXDIR_LEN;
  
  	result = kmalloc(len, GFP_KERNEL);
  	if (!result)
  		return result;

  	copied = snprintf(result, len, LEGACY_RECDIR_ENV_PREFIX "%s/",
  				nfs4_recoverydir());
  	if (copied > (len - HEXDIR_LEN)) {
  		/* just return nothing if output will be truncated */
  		kfree(result);
  		return NULL;
  	}
  
  	copied = nfs4_make_rec_clidname(result + copied, name);
  	if (copied) {

  		kfree(result);
  		return NULL;
  	}
  
  	return result;
  }

  static int

  nfsd4_umh_cltrack_upcall(char *cmd, char *arg, char *legacy)

  {

  	char *envp[2];

  	char *argv[4];
  	int ret;
  
  	if (unlikely(!cltrack_prog[0])) {
  		dprintk("%s: cltrack_prog is disabled
  ", __func__);
  		return -EACCES;
  	}
  
  	dprintk("%s: cmd: %s
  ", __func__, cmd);
  	dprintk("%s: arg: %s
  ", __func__, arg ? arg : "(null)");

  	dprintk("%s: legacy: %s
  ", __func__, legacy ? legacy : "(null)");
  
  	envp[0] = legacy;
  	envp[1] = NULL;

  
  	argv[0] = (char *)cltrack_prog;
  	argv[1] = cmd;
  	argv[2] = arg;
  	argv[3] = NULL;
  
  	ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
  	/*
  	 * Disable the upcall mechanism if we're getting an ENOENT or EACCES
  	 * error. The admin can re-enable it on the fly by using sysfs
  	 * once the problem has been fixed.
  	 */
  	if (ret == -ENOENT || ret == -EACCES) {
  		dprintk("NFSD: %s was not found or isn't executable (%d). "
  			"Setting cltrack_prog to blank string!",
  			cltrack_prog, ret);
  		cltrack_prog[0] = '\0';
  	}
  	dprintk("%s: %s return value: %d
  ", __func__, cltrack_prog, ret);
  
  	return ret;
  }
  
  static char *
  bin_to_hex_dup(const unsigned char *src, int srclen)
  {
  	int i;
  	char *buf, *hex;
  
  	/* +1 for terminating NULL */
  	buf = kmalloc((srclen * 2) + 1, GFP_KERNEL);
  	if (!buf)
  		return buf;
  
  	hex = buf;
  	for (i = 0; i < srclen; i++) {
  		sprintf(hex, "%2.2x", *src++);
  		hex += 2;
  	}
  	return buf;
  }
  
  static int
  nfsd4_umh_cltrack_init(struct net __attribute__((unused)) *net)
  {

  	/* XXX: The usermode helper s not working in container yet. */
  	if (net != &init_net) {
  		WARN(1, KERN_ERR "NFSD: attempt to initialize umh client "
  			"tracking in a container!
  ");
  		return -EINVAL;
  	}

  	return nfsd4_umh_cltrack_upcall("init", NULL, NULL);

  }
  
  static void
  nfsd4_umh_cltrack_create(struct nfs4_client *clp)
  {
  	char *hexid;
  
  	hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);
  	if (!hexid) {
  		dprintk("%s: can't allocate memory for upcall!
  ", __func__);
  		return;
  	}

  	nfsd4_umh_cltrack_upcall("create", hexid, NULL);

  	kfree(hexid);
  }
  
  static void
  nfsd4_umh_cltrack_remove(struct nfs4_client *clp)
  {
  	char *hexid;
  
  	hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);
  	if (!hexid) {
  		dprintk("%s: can't allocate memory for upcall!
  ", __func__);
  		return;
  	}

  	nfsd4_umh_cltrack_upcall("remove", hexid, NULL);

  	kfree(hexid);
  }
  
  static int
  nfsd4_umh_cltrack_check(struct nfs4_client *clp)
  {
  	int ret;

  	char *hexid, *legacy;

  
  	hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);
  	if (!hexid) {
  		dprintk("%s: can't allocate memory for upcall!
  ", __func__);
  		return -ENOMEM;
  	}

  	legacy = nfsd4_cltrack_legacy_recdir(&clp->cl_name);

  	ret = nfsd4_umh_cltrack_upcall("check", hexid, legacy);
  	kfree(legacy);

  	kfree(hexid);
  	return ret;
  }
  
  static void

  nfsd4_umh_cltrack_grace_done(struct nfsd_net __attribute__((unused)) *nn,

  				time_t boot_time)
  {

  	char *legacy;

  	char timestr[22]; /* FIXME: better way to determine max size? */
  
  	sprintf(timestr, "%ld", boot_time);

  	legacy = nfsd4_cltrack_legacy_topdir();
  	nfsd4_umh_cltrack_upcall("gracedone", timestr, legacy);
  	kfree(legacy);

  }
  
  static struct nfsd4_client_tracking_ops nfsd4_umh_tracking_ops = {
  	.init		= nfsd4_umh_cltrack_init,
  	.exit		= NULL,
  	.create		= nfsd4_umh_cltrack_create,
  	.remove		= nfsd4_umh_cltrack_remove,
  	.check		= nfsd4_umh_cltrack_check,
  	.grace_done	= nfsd4_umh_cltrack_grace_done,
  };

  int
  nfsd4_client_tracking_init(struct net *net)
  {
  	int status;

  	struct path path;

  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

  	/* just run the init if it the method is already decided */

  	if (nn->client_tracking_ops)

  		goto do_init;
  
  	/*
  	 * First, try a UMH upcall. It should succeed or fail quickly, so
  	 * there's little harm in trying that first.
  	 */

  	nn->client_tracking_ops = &nfsd4_umh_tracking_ops;
  	status = nn->client_tracking_ops->init(net);

  	if (!status)
  		return status;
  
  	/*
  	 * See if the recoverydir exists and is a directory. If it is,
  	 * then use the legacy ops.
  	 */

  	nn->client_tracking_ops = &nfsd4_legacy_tracking_ops;

  	status = kern_path(nfs4_recoverydir(), LOOKUP_FOLLOW, &path);
  	if (!status) {
  		status = S_ISDIR(path.dentry->d_inode->i_mode);
  		path_put(&path);
  		if (status)
  			goto do_init;

  	}

  	/* Finally, try to use nfsdcld */

  	nn->client_tracking_ops = &nfsd4_cld_tracking_ops;

  	printk(KERN_WARNING "NFSD: the nfsdcld client tracking upcall will be "
  			"removed in 3.10. Please transition to using "
  			"nfsdcltrack.
  ");

  do_init:

  	status = nn->client_tracking_ops->init(net);

  	if (status) {
  		printk(KERN_WARNING "NFSD: Unable to initialize client "
  				    "recovery tracking! (%d)
  ", status);

  		nn->client_tracking_ops = NULL;

  	}
  	return status;
  }
  
  void
  nfsd4_client_tracking_exit(struct net *net)
  {

  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  
  	if (nn->client_tracking_ops) {
  		if (nn->client_tracking_ops->exit)
  			nn->client_tracking_ops->exit(net);
  		nn->client_tracking_ops = NULL;

  	}
  }
  
  void
  nfsd4_client_record_create(struct nfs4_client *clp)
  {

  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
  
  	if (nn->client_tracking_ops)
  		nn->client_tracking_ops->create(clp);

  }
  
  void
  nfsd4_client_record_remove(struct nfs4_client *clp)
  {

  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
  
  	if (nn->client_tracking_ops)
  		nn->client_tracking_ops->remove(clp);

  }
  
  int
  nfsd4_client_record_check(struct nfs4_client *clp)
  {

  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
  
  	if (nn->client_tracking_ops)
  		return nn->client_tracking_ops->check(clp);

  
  	return -EOPNOTSUPP;
  }
  
  void

  nfsd4_record_grace_done(struct nfsd_net *nn, time_t boot_time)

  {

  	if (nn->client_tracking_ops)
  		nn->client_tracking_ops->grace_done(nn, boot_time);

  }

  
  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 nfsd_net *nn = net_generic(net, nfsd_net_id);
  	struct cld_net *cn = nn->cld_net;
  	struct dentry *dentry;
  	int ret = 0;
  
  	if (!try_module_get(THIS_MODULE))
  		return 0;
  
  	if (!cn) {
  		module_put(THIS_MODULE);
  		return 0;
  	}
  
  	switch (event) {
  	case RPC_PIPEFS_MOUNT:
  		dentry = nfsd4_cld_register_sb(sb, cn->cn_pipe);
  		if (IS_ERR(dentry)) {
  			ret = PTR_ERR(dentry);
  			break;
  		}
  		cn->cn_pipe->dentry = dentry;
  		break;
  	case RPC_PIPEFS_UMOUNT:
  		if (cn->cn_pipe->dentry)
  			nfsd4_cld_unregister_sb(cn->cn_pipe);
  		break;
  	default:
  		ret = -ENOTSUPP;
  		break;
  	}
  	module_put(THIS_MODULE);
  	return ret;
  }

  static struct notifier_block nfsd4_cld_block = {

  	.notifier_call = rpc_pipefs_event,
  };

  
  int
  register_cld_notifier(void)
  {
  	return rpc_pipefs_notifier_register(&nfsd4_cld_block);
  }
  
  void
  unregister_cld_notifier(void)
  {
  	rpc_pipefs_notifier_unregister(&nfsd4_cld_block);
  }