text: /*
  *  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 <crypto/hash.h>
  #include <linux/file.h>
  #include <linux/slab.h>
  #include <linux/namei.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 *);
  	uint8_t version;
  	size_t msglen;
  };
  
  static const struct nfsd4_client_tracking_ops nfsd4_cld_tracking_ops;
  static const struct nfsd4_client_tracking_ops nfsd4_cld_tracking_ops_v2;
  
  /* 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 crypto_shash *tfm;
  	int status;
  
  	dprintk("NFSD: nfs4_make_rec_clidname for %.*s\n",
  			clname->len, clname->data);
  	tfm = crypto_alloc_shash("md5", 0, 0);
  	if (IS_ERR(tfm)) {
  		status = PTR_ERR(tfm);
  		goto out_no_tfm;
  	}
  
  	cksum.len = crypto_shash_digestsize(tfm);
  	cksum.data = kmalloc(cksum.len, GFP_KERNEL);
  	if (cksum.data == NULL) {
  		status = -ENOMEM;
   		goto out;
  	}
  
  	{
  		SHASH_DESC_ON_STACK(desc, tfm);
  
  		desc->tfm = tfm;
  
  		status = crypto_shash_digest(desc, clname->data, clname->len,
  					     cksum.data);
  		shash_desc_zero(desc);
  	}
  
  	if (status)
  		goto out;
  
  	md5_to_hex(dname, cksum.data);
  
  	status = 0;
  out:
  	kfree(cksum.data);
  	crypto_free_shash(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).\n", 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!\n");
  		nfsd4_client_tracking_exit(clp->net);
  	}
  }
  
  static void
  __nfsd4_create_reclaim_record_grace(struct nfs4_client *clp,
  		const char *dname, int len, struct nfsd_net *nn)
  {
  	struct xdr_netobj name;
  	struct xdr_netobj princhash = { .len = 0, .data = NULL };
  	struct nfs4_client_reclaim *crp;
  
  	name.data = kmemdup(dname, len, GFP_KERNEL);
  	if (!name.data) {
  		dprintk("%s: failed to allocate memory for name.data!\n",
  			__func__);
  		return;
  	}
  	name.len = len;
  	crp = nfs4_client_to_reclaim(name, princhash, nn);
  	if (!crp) {
  		kfree(name.data);
  		return;
  	}
  	crp->cr_clp = clp;
  }
  
  static void
  nfsd4_create_clid_dir(struct nfs4_client *clp)
  {
  	const struct cred *original_cred;
  	char dname[HEXDIR_LEN];
  	struct dentry *dir, *dentry;
  	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)
  		goto out_creds;
  
  	dir = nn->rec_file->f_path.dentry;
  	/* lock the parent */
  	inode_lock(d_inode(dir));
  
  	dentry = lookup_one_len(dname, dir, HEXDIR_LEN-1);
  	if (IS_ERR(dentry)) {
  		status = PTR_ERR(dentry);
  		goto out_unlock;
  	}
  	if (d_really_is_positive(dentry))
  		/*
  		 * 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(d_inode(dir), dentry, S_IRWXU);
  out_put:
  	dput(dentry);
  out_unlock:
  	inode_unlock(d_inode(dir));
  	if (status == 0) {
  		if (nn->in_grace)
  			__nfsd4_create_reclaim_record_grace(clp, dname,
  					HEXDIR_LEN, nn);
  		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);
  out_creds:
  	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(struct dir_context *__ctx, const char *name, int namlen,
  		loff_t offset, u64 ino, unsigned int d_type)
  {
  	struct nfs4_dir_ctx *ctx =
  		container_of(__ctx, struct nfs4_dir_ctx, ctx);
  	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)
  	};
  	struct name_list *entry, *tmp;
  	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);
  	inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
  
  	list_for_each_entry_safe(entry, tmp, &ctx.names, 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);
  	}
  	inode_unlock(d_inode(dir));
  	nfs4_reset_creds(original_cred);
  
  	list_for_each_entry_safe(entry, tmp, &ctx.names, list) {
  		dprintk("NFSD: %s. Left entry %s\n", __func__, entry->name);
  		list_del(&entry->list);
  		kfree(entry);
  	}
  	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\n", namlen, name);
  
  	dir = nn->rec_file->f_path.dentry;
  	inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
  	dentry = lookup_one_len(name, dir, namlen);
  	if (IS_ERR(dentry)) {
  		status = PTR_ERR(dentry);
  		goto out_unlock;
  	}
  	status = -ENOENT;
  	if (d_really_is_negative(dentry))
  		goto out;
  	status = vfs_rmdir(d_inode(dir), dentry);
  out:
  	dput(dentry);
  out_unlock:
  	inode_unlock(d_inode(dir));
  	return status;
  }
  
  static void
  __nfsd4_remove_reclaim_record_grace(const char *dname, int len,
  		struct nfsd_net *nn)
  {
  	struct xdr_netobj name;
  	struct nfs4_client_reclaim *crp;
  
  	name.data = kmemdup(dname, len, GFP_KERNEL);
  	if (!name.data) {
  		dprintk("%s: failed to allocate memory for name.data!\n",
  			__func__);
  		return;
  	}
  	name.len = len;
  	crp = nfsd4_find_reclaim_client(name, nn);
  	kfree(name.data);
  	if (crp)
  		nfs4_remove_reclaim_record(crp, nn);
  }
  
  static void
  nfsd4_remove_clid_dir(struct nfs4_client *clp)
  {
  	const struct cred *original_cred;
  	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)
  			__nfsd4_remove_reclaim_record_grace(dname,
  					HEXDIR_LEN, nn);
  	}
  out_drop_write:
  	mnt_drop_write_file(nn->rec_file);
  out:
  	if (status)
  		printk("NFSD: Failed to remove expired client state directory"
  				" %.*s\n", HEXDIR_LEN, dname);
  }
  
  static int
  purge_old(struct dentry *parent, struct dentry *child, struct nfsd_net *nn)
  {
  	int status;
  	struct xdr_netobj name;
  
  	if (child->d_name.len != HEXDIR_LEN - 1) {
  		printk("%s: illegal name %pd in recovery directory\n",
  				__func__, child);
  		/* Keep trying; maybe the others are OK: */
  		return 0;
  	}
  	name.data = kmemdup_nul(child->d_name.name, child->d_name.len, GFP_KERNEL);
  	if (!name.data) {
  		dprintk("%s: failed to allocate memory for name.data!\n",
  			__func__);
  		goto out;
  	}
  	name.len = HEXDIR_LEN;
  	if (nfs4_has_reclaimed_state(name, nn))
  		goto out_free;
  
  	status = vfs_rmdir(d_inode(parent), child);
  	if (status)
  		printk("failed to remove client recovery directory %pd\n",
  				child);
  out_free:
  	kfree(name.data);
  out:
  	/* Keep trying, success or failure: */
  	return 0;
  }
  
  static void
  nfsd4_recdir_purge_old(struct nfsd_net *nn)
  {
  	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\n", nn->rec_file);
  }
  
  static int
  load_recdir(struct dentry *parent, struct dentry *child, struct nfsd_net *nn)
  {
  	struct xdr_netobj name;
  	struct xdr_netobj princhash = { .len = 0, .data = NULL };
  
  	if (child->d_name.len != HEXDIR_LEN - 1) {
  		printk("%s: illegal name %pd in recovery directory\n",
  				__func__, child);
  		/* Keep trying; maybe the others are OK: */
  		return 0;
  	}
  	name.data = kmemdup_nul(child->d_name.name, child->d_name.len, GFP_KERNEL);
  	if (!name.data) {
  		dprintk("%s: failed to allocate memory for name.data!\n",
  			__func__);
  		goto out;
  	}
  	name.len = HEXDIR_LEN;
  	if (!nfs4_client_to_reclaim(name, princhash, nn))
  		kfree(name.data);
  out:
  	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\n", 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\n",
  			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\n",
  		       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\n",
  				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 void
  nfsd4_shutdown_recdir(struct net *net)
  {
  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  
  	if (!nn->rec_file)
  		return;
  	fput(nn->rec_file);
  	nn->rec_file = NULL;
  }
  
  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_array(CLIENT_HASH_SIZE,
  						sizeof(struct list_head),
  						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)
  		return status;
  
  	status = nfsd4_recdir_load(net);
  	if (status)
  		nfsd4_shutdown_recdir(net);
  
  	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) {
  		pr_warn("NFSD: attempt to initialize legacy client tracking in a container ignored.\n");
  		return -EINVAL;
  	}
  
  	status = nfs4_legacy_state_init(net);
  	if (status)
  		return status;
  
  	status = nfsd4_load_reboot_recovery_data(net);
  	if (status)
  		goto err;
  	printk("NFSD: Using legacy client tracking operations.\n");
  	return 0;
  
  err:
  	nfs4_legacy_state_shutdown(net);
  	return status;
  }
  
  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(net);
  	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 (d_is_dir(path.dentry)) {
  		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);
  	struct xdr_netobj name;
  
  	/* 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 */
  	name.data = kmemdup(dname, HEXDIR_LEN, GFP_KERNEL);
  	if (!name.data) {
  		dprintk("%s: failed to allocate memory for name.data!\n",
  			__func__);
  		goto out_enoent;
  	}
  	name.len = HEXDIR_LEN;
  	crp = nfsd4_find_reclaim_client(name, nn);
  	kfree(name.data);
  	if (crp) {
  		set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
  		crp->cr_clp = clp;
  		return 0;
  	}
  
  out_enoent:
  	return -ENOENT;
  }
  
  static const 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,
  	.version	= 1,
  	.msglen		= 0,
  };
  
  /* 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;
  	bool			 cn_has_legacy;
  	struct crypto_shash	*cn_tfm;
  };
  
  struct cld_upcall {
  	struct list_head	 cu_list;
  	struct cld_net		*cu_net;
  	struct completion	 cu_done;
  	union {
  		struct cld_msg_hdr	 cu_hdr;
  		struct cld_msg		 cu_msg;
  		struct cld_msg_v2	 cu_msg_v2;
  	} cu_u;
  };
  
  static int
  __cld_pipe_upcall(struct rpc_pipe *pipe, void *cmsg)
  {
  	int ret;
  	struct rpc_pipe_msg msg;
  	struct cld_upcall *cup = container_of(cmsg, struct cld_upcall, cu_u);
  	struct nfsd_net *nn = net_generic(pipe->dentry->d_sb->s_fs_info,
  					  nfsd_net_id);
  
  	memset(&msg, 0, sizeof(msg));
  	msg.data = cmsg;
  	msg.len = nn->client_tracking_ops->msglen;
  
  	ret = rpc_queue_upcall(pipe, &msg);
  	if (ret < 0) {
  		goto out;
  	}
  
  	wait_for_completion(&cup->cu_done);
  
  	if (msg.errno < 0)
  		ret = msg.errno;
  out:
  	return ret;
  }
  
  static int
  cld_pipe_upcall(struct rpc_pipe *pipe, void *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_inprogress_downcall(const struct cld_msg_v2 __user *cmsg,
  		struct nfsd_net *nn)
  {
  	uint8_t cmd, princhashlen;
  	struct xdr_netobj name, princhash = { .len = 0, .data = NULL };
  	uint16_t namelen;
  	struct cld_net *cn = nn->cld_net;
  
  	if (get_user(cmd, &cmsg->cm_cmd)) {
  		dprintk("%s: error when copying cmd from userspace", __func__);
  		return -EFAULT;
  	}
  	if (cmd == Cld_GraceStart) {
  		if (nn->client_tracking_ops->version >= 2) {
  			const struct cld_clntinfo __user *ci;
  
  			ci = &cmsg->cm_u.cm_clntinfo;
  			if (get_user(namelen, &ci->cc_name.cn_len))
  				return -EFAULT;
  			name.data = memdup_user(&ci->cc_name.cn_id, namelen);
  			if (IS_ERR_OR_NULL(name.data))
  				return -EFAULT;
  			name.len = namelen;
  			get_user(princhashlen, &ci->cc_princhash.cp_len);
  			if (princhashlen > 0) {
  				princhash.data = memdup_user(
  						&ci->cc_princhash.cp_data,
  						princhashlen);
  				if (IS_ERR_OR_NULL(princhash.data))
  					return -EFAULT;
  				princhash.len = princhashlen;
  			} else
  				princhash.len = 0;
  		} else {
  			const struct cld_name __user *cnm;
  
  			cnm = &cmsg->cm_u.cm_name;
  			if (get_user(namelen, &cnm->cn_len))
  				return -EFAULT;
  			name.data = memdup_user(&cnm->cn_id, namelen);
  			if (IS_ERR_OR_NULL(name.data))
  				return -EFAULT;
  			name.len = namelen;
  		}
  		if (name.len > 5 && memcmp(name.data, "hash:", 5) == 0) {
  			name.len = name.len - 5;
  			memmove(name.data, name.data + 5, name.len);
  			cn->cn_has_legacy = true;
  		}
  		if (!nfs4_client_to_reclaim(name, princhash, nn)) {
  			kfree(name.data);
  			kfree(princhash.data);
  			return -EFAULT;
  		}
  		return nn->client_tracking_ops->msglen;
  	}
  	return -EFAULT;
  }
  
  static ssize_t
  cld_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
  {
  	struct cld_upcall *tmp, *cup;
  	struct cld_msg_hdr __user *hdr = (struct cld_msg_hdr __user *)src;
  	struct cld_msg_v2 __user *cmsg = (struct cld_msg_v2 __user *)src;
  	uint32_t xid;
  	struct nfsd_net *nn = net_generic(file_inode(filp)->i_sb->s_fs_info,
  						nfsd_net_id);
  	struct cld_net *cn = nn->cld_net;
  	int16_t status;
  
  	if (mlen != nn->client_tracking_ops->msglen) {
  		dprintk("%s: got %zu bytes, expected %zu\n", __func__, mlen,
  			nn->client_tracking_ops->msglen);
  		return -EINVAL;
  	}
  
  	/* copy just the xid so we can try to find that */
  	if (copy_from_user(&xid, &hdr->cm_xid, sizeof(xid)) != 0) {
  		dprintk("%s: error when copying xid from userspace", __func__);
  		return -EFAULT;
  	}
  
  	/*
  	 * copy the status so we know whether to remove the upcall from the
  	 * list (for -EINPROGRESS, we just want to make sure the xid is
  	 * valid, not remove the upcall from the list)
  	 */
  	if (get_user(status, &hdr->cm_status)) {
  		dprintk("%s: error when copying status 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_u.cu_hdr.cm_xid) == xid) {
  			cup = tmp;
  			if (status != -EINPROGRESS)
  				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\n", __func__, xid);
  		return -EINVAL;
  	}
  
  	if (status == -EINPROGRESS)
  		return __cld_pipe_inprogress_downcall(cmsg, nn);
  
  	if (copy_from_user(&cup->cu_u.cu_msg_v2, src, mlen) != 0)
  		return -EFAULT;
  
  	complete(&cup->cu_done);
  	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_u.cu_msg);
  
  	/* errno >= 0 means we got a downcall */
  	if (msg->errno >= 0)
  		return;
  
  	complete(&cup->cu_done);
  }
  
  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;
  	cn->cn_has_legacy = false;
  	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)\n",
  			ret);
  	return ret;
  }
  
  static int
  nfsd4_init_cld_pipe(struct net *net)
  {
  	int status;
  
  	status = __nfsd4_init_cld_pipe(net);
  	if (!status)
  		printk("NFSD: Using old nfsdcld client tracking operations.\n");
  	return status;
  }
  
  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);
  	if (cn->cn_tfm)
  		crypto_free_shash(cn->cn_tfm);
  	kfree(nn->cld_net);
  	nn->cld_net = NULL;
  }
  
  static struct cld_upcall *
  alloc_cld_upcall(struct nfsd_net *nn)
  {
  	struct cld_upcall *new, *tmp;
  	struct cld_net *cn = nn->cld_net;
  
  	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_u.cu_msg.cm_xid == cn->cn_xid) {
  			cn->cn_xid++;
  			spin_unlock(&cn->cn_lock);
  			goto restart_search;
  		}
  	}
  	init_completion(&new->cu_done);
  	new->cu_u.cu_msg.cm_vers = nn->client_tracking_ops->version;
  	put_unaligned(cn->cn_xid++, &new->cu_u.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\n", __func__, new->cu_u.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(nn);
  	if (!cup) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  
  	cup->cu_u.cu_msg.cm_cmd = Cld_Create;
  	cup->cu_u.cu_msg.cm_u.cm_name.cn_len = clp->cl_name.len;
  	memcpy(cup->cu_u.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_u.cu_msg);
  	if (!ret) {
  		ret = cup->cu_u.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\n", ret);
  }
  
  /* Ask daemon to create a new record */
  static void
  nfsd4_cld_create_v2(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;
  	struct cld_msg_v2 *cmsg;
  	struct crypto_shash *tfm = cn->cn_tfm;
  	struct xdr_netobj cksum;
  	char *principal = NULL;
  	SHASH_DESC_ON_STACK(desc, tfm);
  
  	/* Don't upcall if it's already stored */
  	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
  		return;
  
  	cup = alloc_cld_upcall(nn);
  	if (!cup) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  
  	cmsg = &cup->cu_u.cu_msg_v2;
  	cmsg->cm_cmd = Cld_Create;
  	cmsg->cm_u.cm_clntinfo.cc_name.cn_len = clp->cl_name.len;
  	memcpy(cmsg->cm_u.cm_clntinfo.cc_name.cn_id, clp->cl_name.data,
  			clp->cl_name.len);
  	if (clp->cl_cred.cr_raw_principal)
  		principal = clp->cl_cred.cr_raw_principal;
  	else if (clp->cl_cred.cr_principal)
  		principal = clp->cl_cred.cr_principal;
  	if (principal) {
  		desc->tfm = tfm;
  		cksum.len = crypto_shash_digestsize(tfm);
  		cksum.data = kmalloc(cksum.len, GFP_KERNEL);
  		if (cksum.data == NULL) {
  			ret = -ENOMEM;
  			goto out;
  		}
  		ret = crypto_shash_digest(desc, principal, strlen(principal),
  					  cksum.data);
  		shash_desc_zero(desc);
  		if (ret) {
  			kfree(cksum.data);
  			goto out;
  		}
  		cmsg->cm_u.cm_clntinfo.cc_princhash.cp_len = cksum.len;
  		memcpy(cmsg->cm_u.cm_clntinfo.cc_princhash.cp_data,
  		       cksum.data, cksum.len);
  		kfree(cksum.data);
  	} else
  		cmsg->cm_u.cm_clntinfo.cc_princhash.cp_len = 0;
  
  	ret = cld_pipe_upcall(cn->cn_pipe, cmsg);
  	if (!ret) {
  		ret = cmsg->cm_status;
  		set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
  	}
  
  out:
  	free_cld_upcall(cup);
  out_err:
  	if (ret)
  		pr_err("NFSD: Unable to create client record on stable storage: %d\n",
  				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(nn);
  	if (!cup) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  
  	cup->cu_u.cu_msg.cm_cmd = Cld_Remove;
  	cup->cu_u.cu_msg.cm_u.cm_name.cn_len = clp->cl_name.len;
  	memcpy(cup->cu_u.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_u.cu_msg);
  	if (!ret) {
  		ret = cup->cu_u.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\n", ret);
  }
  
  /*
   * For older nfsdcld's that do not allow us to "slurp" the clients
   * from the tracking database during startup.
   *
   * Check for presence of a record, and update its timestamp
   */
  static int
  nfsd4_cld_check_v0(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(nn);
  	if (!cup) {
  		printk(KERN_ERR "NFSD: Unable to check client record on "
  				"stable storage: %d\n", -ENOMEM);
  		return -ENOMEM;
  	}
  
  	cup->cu_u.cu_msg.cm_cmd = Cld_Check;
  	cup->cu_u.cu_msg.cm_u.cm_name.cn_len = clp->cl_name.len;
  	memcpy(cup->cu_u.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_u.cu_msg);
  	if (!ret) {
  		ret = cup->cu_u.cu_msg.cm_status;
  		set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
  	}
  
  	free_cld_upcall(cup);
  	return ret;
  }
  
  /*
   * For newer nfsdcld's that allow us to "slurp" the clients
   * from the tracking database during startup.
   *
   * Check for presence of a record in the reclaim_str_hashtbl
   */
  static int
  nfsd4_cld_check(struct nfs4_client *clp)
  {
  	struct nfs4_client_reclaim *crp;
  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
  	struct cld_net *cn = nn->cld_net;
  	int status;
  	char dname[HEXDIR_LEN];
  	struct xdr_netobj name;
  
  	/* did we already find that this client is stable? */
  	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
  		return 0;
  
  	/* look for it in the reclaim hashtable otherwise */
  	crp = nfsd4_find_reclaim_client(clp->cl_name, nn);
  	if (crp)
  		goto found;
  
  	if (cn->cn_has_legacy) {
  		status = nfs4_make_rec_clidname(dname, &clp->cl_name);
  		if (status)
  			return -ENOENT;
  
  		name.data = kmemdup(dname, HEXDIR_LEN, GFP_KERNEL);
  		if (!name.data) {
  			dprintk("%s: failed to allocate memory for name.data!\n",
  				__func__);
  			return -ENOENT;
  		}
  		name.len = HEXDIR_LEN;
  		crp = nfsd4_find_reclaim_client(name, nn);
  		kfree(name.data);
  		if (crp)
  			goto found;
  
  	}
  	return -ENOENT;
  found:
  	crp->cr_clp = clp;
  	return 0;
  }
  
  static int
  nfsd4_cld_check_v2(struct nfs4_client *clp)
  {
  	struct nfs4_client_reclaim *crp;
  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
  	struct cld_net *cn = nn->cld_net;
  	int status;
  	char dname[HEXDIR_LEN];
  	struct xdr_netobj name;
  	struct crypto_shash *tfm = cn->cn_tfm;
  	struct xdr_netobj cksum;
  	char *principal = NULL;
  	SHASH_DESC_ON_STACK(desc, tfm);
  
  	/* did we already find that this client is stable? */
  	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
  		return 0;
  
  	/* look for it in the reclaim hashtable otherwise */
  	crp = nfsd4_find_reclaim_client(clp->cl_name, nn);
  	if (crp)
  		goto found;
  
  	if (cn->cn_has_legacy) {
  		status = nfs4_make_rec_clidname(dname, &clp->cl_name);
  		if (status)
  			return -ENOENT;
  
  		name.data = kmemdup(dname, HEXDIR_LEN, GFP_KERNEL);
  		if (!name.data) {
  			dprintk("%s: failed to allocate memory for name.data\n",
  					__func__);
  			return -ENOENT;
  		}
  		name.len = HEXDIR_LEN;
  		crp = nfsd4_find_reclaim_client(name, nn);
  		kfree(name.data);
  		if (crp)
  			goto found;
  
  	}
  	return -ENOENT;
  found:
  	if (crp->cr_princhash.len) {
  		if (clp->cl_cred.cr_raw_principal)
  			principal = clp->cl_cred.cr_raw_principal;
  		else if (clp->cl_cred.cr_principal)
  			principal = clp->cl_cred.cr_principal;
  		if (principal == NULL)
  			return -ENOENT;
  		desc->tfm = tfm;
  		cksum.len = crypto_shash_digestsize(tfm);
  		cksum.data = kmalloc(cksum.len, GFP_KERNEL);
  		if (cksum.data == NULL)
  			return -ENOENT;
  		status = crypto_shash_digest(desc, principal, strlen(principal),
  					     cksum.data);
  		shash_desc_zero(desc);
  		if (status) {
  			kfree(cksum.data);
  			return -ENOENT;
  		}
  		if (memcmp(crp->cr_princhash.data, cksum.data,
  				crp->cr_princhash.len)) {
  			kfree(cksum.data);
  			return -ENOENT;
  		}
  		kfree(cksum.data);
  	}
  	crp->cr_clp = clp;
  	return 0;
  }
  
  static int
  nfsd4_cld_grace_start(struct nfsd_net *nn)
  {
  	int ret;
  	struct cld_upcall *cup;
  	struct cld_net *cn = nn->cld_net;
  
  	cup = alloc_cld_upcall(nn);
  	if (!cup) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  
  	cup->cu_u.cu_msg.cm_cmd = Cld_GraceStart;
  	ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_u.cu_msg);
  	if (!ret)
  		ret = cup->cu_u.cu_msg.cm_status;
  
  	free_cld_upcall(cup);
  out_err:
  	if (ret)
  		dprintk("%s: Unable to get clients from userspace: %d\n",
  			__func__, ret);
  	return ret;
  }
  
  /* For older nfsdcld's that need cm_gracetime */
  static void
  nfsd4_cld_grace_done_v0(struct nfsd_net *nn)
  {
  	int ret;
  	struct cld_upcall *cup;
  	struct cld_net *cn = nn->cld_net;
  
  	cup = alloc_cld_upcall(nn);
  	if (!cup) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  
  	cup->cu_u.cu_msg.cm_cmd = Cld_GraceDone;
  	cup->cu_u.cu_msg.cm_u.cm_gracetime = (int64_t)nn->boot_time;
  	ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_u.cu_msg);
  	if (!ret)
  		ret = cup->cu_u.cu_msg.cm_status;
  
  	free_cld_upcall(cup);
  out_err:
  	if (ret)
  		printk(KERN_ERR "NFSD: Unable to end grace period: %d\n", ret);
  }
  
  /*
   * For newer nfsdcld's that do not need cm_gracetime.  We also need to call
   * nfs4_release_reclaim() to clear out the reclaim_str_hashtbl.
   */
  static void
  nfsd4_cld_grace_done(struct nfsd_net *nn)
  {
  	int ret;
  	struct cld_upcall *cup;
  	struct cld_net *cn = nn->cld_net;
  
  	cup = alloc_cld_upcall(nn);
  	if (!cup) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  
  	cup->cu_u.cu_msg.cm_cmd = Cld_GraceDone;
  	ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_u.cu_msg);
  	if (!ret)
  		ret = cup->cu_u.cu_msg.cm_status;
  
  	free_cld_upcall(cup);
  out_err:
  	nfs4_release_reclaim(nn);
  	if (ret)
  		printk(KERN_ERR "NFSD: Unable to end grace period: %d\n", ret);
  }
  
  static int
  nfs4_cld_state_init(struct net *net)
  {
  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  	int i;
  
  	nn->reclaim_str_hashtbl = kmalloc_array(CLIENT_HASH_SIZE,
  						sizeof(struct list_head),
  						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;
  	nn->track_reclaim_completes = true;
  	atomic_set(&nn->nr_reclaim_complete, 0);
  
  	return 0;
  }
  
  static void
  nfs4_cld_state_shutdown(struct net *net)
  {
  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  
  	nn->track_reclaim_completes = false;
  	kfree(nn->reclaim_str_hashtbl);
  }
  
  static bool
  cld_running(struct nfsd_net *nn)
  {
  	struct cld_net *cn = nn->cld_net;
  	struct rpc_pipe *pipe = cn->cn_pipe;
  
  	return pipe->nreaders || pipe->nwriters;
  }
  
  static int
  nfsd4_cld_get_version(struct nfsd_net *nn)
  {
  	int ret = 0;
  	struct cld_upcall *cup;
  	struct cld_net *cn = nn->cld_net;
  	uint8_t version;
  
  	cup = alloc_cld_upcall(nn);
  	if (!cup) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  	cup->cu_u.cu_msg.cm_cmd = Cld_GetVersion;
  	ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_u.cu_msg);
  	if (!ret) {
  		ret = cup->cu_u.cu_msg.cm_status;
  		if (ret)
  			goto out_free;
  		version = cup->cu_u.cu_msg.cm_u.cm_version;
  		dprintk("%s: userspace returned version %u\n",
  				__func__, version);
  		if (version < 1)
  			version = 1;
  		else if (version > CLD_UPCALL_VERSION)
  			version = CLD_UPCALL_VERSION;
  
  		switch (version) {
  		case 1:
  			nn->client_tracking_ops = &nfsd4_cld_tracking_ops;
  			break;
  		case 2:
  			nn->client_tracking_ops = &nfsd4_cld_tracking_ops_v2;
  			break;
  		default:
  			break;
  		}
  	}
  out_free:
  	free_cld_upcall(cup);
  out_err:
  	if (ret)
  		dprintk("%s: Unable to get version from userspace: %d\n",
  			__func__, ret);
  	return ret;
  }
  
  static int
  nfsd4_cld_tracking_init(struct net *net)
  {
  	int status;
  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  	bool running;
  	int retries = 10;
  
  	status = nfs4_cld_state_init(net);
  	if (status)
  		return status;
  
  	status = __nfsd4_init_cld_pipe(net);
  	if (status)
  		goto err_shutdown;
  	nn->cld_net->cn_tfm = crypto_alloc_shash("sha256", 0, 0);
  	if (IS_ERR(nn->cld_net->cn_tfm)) {
  		status = PTR_ERR(nn->cld_net->cn_tfm);
  		goto err_remove;
  	}
  
  	/*
  	 * rpc pipe upcalls take 30 seconds to time out, so we don't want to
  	 * queue an upcall unless we know that nfsdcld is running (because we
  	 * want this to fail fast so that nfsd4_client_tracking_init() can try
  	 * the next client tracking method).  nfsdcld should already be running
  	 * before nfsd is started, so the wait here is for nfsdcld to open the
  	 * pipefs file we just created.
  	 */
  	while (!(running = cld_running(nn)) && retries--)
  		msleep(100);
  
  	if (!running) {
  		status = -ETIMEDOUT;
  		goto err_remove;
  	}
  
  	status = nfsd4_cld_get_version(nn);
  	if (status == -EOPNOTSUPP)
  		pr_warn("NFSD: nfsdcld GetVersion upcall failed. Please upgrade nfsdcld.\n");
  
  	status = nfsd4_cld_grace_start(nn);
  	if (status) {
  		if (status == -EOPNOTSUPP)
  			pr_warn("NFSD: nfsdcld GraceStart upcall failed. Please upgrade nfsdcld.\n");
  		nfs4_release_reclaim(nn);
  		goto err_remove;
  	} else
  		printk("NFSD: Using nfsdcld client tracking operations.\n");
  	return 0;
  
  err_remove:
  	nfsd4_remove_cld_pipe(net);
  err_shutdown:
  	nfs4_cld_state_shutdown(net);
  	return status;
  }
  
  static void
  nfsd4_cld_tracking_exit(struct net *net)
  {
  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  
  	nfs4_release_reclaim(nn);
  	nfsd4_remove_cld_pipe(net);
  	nfs4_cld_state_shutdown(net);
  }
  
  /* For older nfsdcld's */
  static const struct nfsd4_client_tracking_ops nfsd4_cld_tracking_ops_v0 = {
  	.init		= nfsd4_init_cld_pipe,
  	.exit		= nfsd4_remove_cld_pipe,
  	.create		= nfsd4_cld_create,
  	.remove		= nfsd4_cld_remove,
  	.check		= nfsd4_cld_check_v0,
  	.grace_done	= nfsd4_cld_grace_done_v0,
  	.version	= 1,
  	.msglen		= sizeof(struct cld_msg),
  };
  
  /* For newer nfsdcld's */
  static const struct nfsd4_client_tracking_ops nfsd4_cld_tracking_ops = {
  	.init		= nfsd4_cld_tracking_init,
  	.exit		= nfsd4_cld_tracking_exit,
  	.create		= nfsd4_cld_create,
  	.remove		= nfsd4_cld_remove,
  	.check		= nfsd4_cld_check,
  	.grace_done	= nfsd4_cld_grace_done,
  	.version	= 1,
  	.msglen		= sizeof(struct cld_msg),
  };
  
  /* v2 create/check ops include the principal, if available */
  static const struct nfsd4_client_tracking_ops nfsd4_cld_tracking_ops_v2 = {
  	.init		= nfsd4_cld_tracking_init,
  	.exit		= nfsd4_cld_tracking_exit,
  	.create		= nfsd4_cld_create_v2,
  	.remove		= nfsd4_cld_remove,
  	.check		= nfsd4_cld_check_v2,
  	.grace_done	= nfsd4_cld_grace_done,
  	.version	= 2,
  	.msglen		= sizeof(struct cld_msg_v2),
  };
  
  /* 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="
  #define HAS_SESSION_ENV_PREFIX "NFSDCLTRACK_CLIENT_HAS_SESSION="
  #define GRACE_START_ENV_PREFIX "NFSDCLTRACK_GRACE_START="
  
  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 char *
  nfsd4_cltrack_client_has_session(struct nfs4_client *clp)
  {
  	int copied;
  	size_t len;
  	char *result;
  
  	/* prefix + Y/N character + terminating NULL */
  	len = strlen(HAS_SESSION_ENV_PREFIX) + 1 + 1;
  
  	result = kmalloc(len, GFP_KERNEL);
  	if (!result)
  		return result;
  
  	copied = snprintf(result, len, HAS_SESSION_ENV_PREFIX "%c",
  				clp->cl_minorversion ? 'Y' : 'N');
  	if (copied >= len) {
  		/* just return nothing if output was truncated */
  		kfree(result);
  		return NULL;
  	}
  
  	return result;
  }
  
  static char *
  nfsd4_cltrack_grace_start(time_t grace_start)
  {
  	int copied;
  	size_t len;
  	char *result;
  
  	/* prefix + max width of int64_t string + terminating NULL */
  	len = strlen(GRACE_START_ENV_PREFIX) + 22 + 1;
  
  	result = kmalloc(len, GFP_KERNEL);
  	if (!result)
  		return result;
  
  	copied = snprintf(result, len, GRACE_START_ENV_PREFIX "%ld",
  				grace_start);
  	if (copied >= len) {
  		/* just return nothing if output was truncated */
  		kfree(result);
  		return NULL;
  	}
  
  	return result;
  }
  
  static int
  nfsd4_umh_cltrack_upcall(char *cmd, char *arg, char *env0, char *env1)
  {
  	char *envp[3];
  	char *argv[4];
  	int ret;
  
  	if (unlikely(!cltrack_prog[0])) {
  		dprintk("%s: cltrack_prog is disabled\n", __func__);
  		return -EACCES;
  	}
  
  	dprintk("%s: cmd: %s\n", __func__, cmd);
  	dprintk("%s: arg: %s\n", __func__, arg ? arg : "(null)");
  	dprintk("%s: env0: %s\n", __func__, env0 ? env0 : "(null)");
  	dprintk("%s: env1: %s\n", __func__, env1 ? env1 : "(null)");
  
  	envp[0] = env0;
  	envp[1] = env1;
  	envp[2] = 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\n", __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 *net)
  {
  	int ret;
  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
  	char *grace_start = nfsd4_cltrack_grace_start(nn->boot_time);
  
  	/* XXX: The usermode helper s not working in container yet. */
  	if (net != &init_net) {
  		pr_warn("NFSD: attempt to initialize umh client tracking in a container ignored.\n");
  		kfree(grace_start);
  		return -EINVAL;
  	}
  
  	ret = nfsd4_umh_cltrack_upcall("init", NULL, grace_start, NULL);
  	kfree(grace_start);
  	if (!ret)
  		printk("NFSD: Using UMH upcall client tracking operations.\n");
  	return ret;
  }
  
  static void
  nfsd4_cltrack_upcall_lock(struct nfs4_client *clp)
  {
  	wait_on_bit_lock(&clp->cl_flags, NFSD4_CLIENT_UPCALL_LOCK,
  			 TASK_UNINTERRUPTIBLE);
  }
  
  static void
  nfsd4_cltrack_upcall_unlock(struct nfs4_client *clp)
  {
  	smp_mb__before_atomic();
  	clear_bit(NFSD4_CLIENT_UPCALL_LOCK, &clp->cl_flags);
  	smp_mb__after_atomic();
  	wake_up_bit(&clp->cl_flags, NFSD4_CLIENT_UPCALL_LOCK);
  }
  
  static void
  nfsd4_umh_cltrack_create(struct nfs4_client *clp)
  {
  	char *hexid, *has_session, *grace_start;
  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
  
  	/*
  	 * With v4.0 clients, there's little difference in outcome between a
  	 * create and check operation, and we can end up calling into this
  	 * function multiple times per client (once for each openowner). So,
  	 * for v4.0 clients skip upcalling once the client has been recorded
  	 * on stable storage.
  	 *
  	 * For v4.1+ clients, the outcome of the two operations is different,
  	 * so we must ensure that we upcall for the create operation. v4.1+
  	 * clients call this on RECLAIM_COMPLETE though, so we should only end
  	 * up doing a single create upcall per client.
  	 */
  	if (clp->cl_minorversion == 0 &&
  	    test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
  		return;
  
  	hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);
  	if (!hexid) {
  		dprintk("%s: can't allocate memory for upcall!\n", __func__);
  		return;
  	}
  
  	has_session = nfsd4_cltrack_client_has_session(clp);
  	grace_start = nfsd4_cltrack_grace_start(nn->boot_time);
  
  	nfsd4_cltrack_upcall_lock(clp);
  	if (!nfsd4_umh_cltrack_upcall("create", hexid, has_session, grace_start))
  		set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
  	nfsd4_cltrack_upcall_unlock(clp);
  
  	kfree(has_session);
  	kfree(grace_start);
  	kfree(hexid);
  }
  
  static void
  nfsd4_umh_cltrack_remove(struct nfs4_client *clp)
  {
  	char *hexid;
  
  	if (!test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
  		return;
  
  	hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);
  	if (!hexid) {
  		dprintk("%s: can't allocate memory for upcall!\n", __func__);
  		return;
  	}
  
  	nfsd4_cltrack_upcall_lock(clp);
  	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags) &&
  	    nfsd4_umh_cltrack_upcall("remove", hexid, NULL, NULL) == 0)
  		clear_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
  	nfsd4_cltrack_upcall_unlock(clp);
  
  	kfree(hexid);
  }
  
  static int
  nfsd4_umh_cltrack_check(struct nfs4_client *clp)
  {
  	int ret;
  	char *hexid, *has_session, *legacy;
  
  	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
  		return 0;
  
  	hexid = bin_to_hex_dup(clp->cl_name.data, clp->cl_name.len);
  	if (!hexid) {
  		dprintk("%s: can't allocate memory for upcall!\n", __func__);
  		return -ENOMEM;
  	}
  
  	has_session = nfsd4_cltrack_client_has_session(clp);
  	legacy = nfsd4_cltrack_legacy_recdir(&clp->cl_name);
  
  	nfsd4_cltrack_upcall_lock(clp);
  	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags)) {
  		ret = 0;
  	} else {
  		ret = nfsd4_umh_cltrack_upcall("check", hexid, has_session, legacy);
  		if (ret == 0)
  			set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
  	}
  	nfsd4_cltrack_upcall_unlock(clp);
  	kfree(has_session);
  	kfree(legacy);
  	kfree(hexid);
  
  	return ret;
  }
  
  static void
  nfsd4_umh_cltrack_grace_done(struct nfsd_net *nn)
  {
  	char *legacy;
  	char timestr[22]; /* FIXME: better way to determine max size? */
  
  	sprintf(timestr, "%ld", nn->boot_time);
  	legacy = nfsd4_cltrack_legacy_topdir();
  	nfsd4_umh_cltrack_upcall("gracedone", timestr, legacy, NULL);
  	kfree(legacy);
  }
  
  static const 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,
  	.version	= 1,
  	.msglen		= 0,
  };
  
  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 to use nfsdcld */
  	nn->client_tracking_ops = &nfsd4_cld_tracking_ops;
  	status = nn->client_tracking_ops->init(net);
  	if (!status)
  		return status;
  	if (status != -ETIMEDOUT) {
  		nn->client_tracking_ops = &nfsd4_cld_tracking_ops_v0;
  		status = nn->client_tracking_ops->init(net);
  		if (!status)
  			return status;
  	}
  
  	/*
  	 * Next, try the UMH upcall.
  	 */
  	nn->client_tracking_ops = &nfsd4_umh_tracking_ops;
  	status = nn->client_tracking_ops->init(net);
  	if (!status)
  		return status;
  
  	/*
  	 * Finally, 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 = d_is_dir(path.dentry);
  		path_put(&path);
  		if (!status) {
  			status = -EINVAL;
  			goto out;
  		}
  	}
  
  do_init:
  	status = nn->client_tracking_ops->init(net);
  out:
  	if (status) {
  		printk(KERN_WARNING "NFSD: Unable to initialize client "
  				    "recovery tracking! (%d)\n", 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)
  {
  	if (nn->client_tracking_ops)
  		nn->client_tracking_ops->grace_done(nn);
  }
  
  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);
  }
  