#define MSNFS	/* HACK HACK */
/*
 * linux/fs/nfsd/export.c
 *
 * NFS exporting and validation.
 *
 * We maintain a list of clients, each of which has a list of
 * exports. To export an fs to a given client, you first have
 * to create the client entry with NFSCTL_ADDCLIENT, which
 * creates a client control block and adds it to the hash
 * table. Then, you call NFSCTL_EXPORT for each fs.
 *
 *
 * Copyright (C) 1995, 1996 Olaf Kirch, <okir@monad.swb.de>
 */

#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/in.h>
#include <linux/seq_file.h>

#include <linux/sunrpc/svc.h>
#include <linux/nfsd/nfsd.h>
#include <linux/nfsd/nfsfh.h>
#include <linux/nfsd/syscall.h>
#include <linux/lockd/bind.h>

#define NFSDDBG_FACILITY	NFSDDBG_EXPORT
#define NFSD_PARANOIA 1

typedef struct svc_client	svc_client;
typedef struct svc_export	svc_export;

static svc_export *	exp_parent(svc_client *clp, kdev_t dev,
					struct dentry *dentry);
static svc_export *	exp_child(svc_client *clp, kdev_t dev,
					struct dentry *dentry);
static void		exp_unexport_all(svc_client *clp);
static void		exp_do_unexport(svc_export *unexp);
static svc_client *	exp_getclientbyname(char *name);
static void		exp_freeclient(svc_client *clp);
static void		exp_unhashclient(svc_client *clp);
static int		exp_verify_string(char *cp, int max);

#define CLIENT_HASHBITS		6
#define CLIENT_HASHMAX		(1 << CLIENT_HASHBITS)
#define CLIENT_HASHMASK		(CLIENT_HASHMAX - 1)
#define CLIENT_HASH(a) \
		((((a)>>24) ^ ((a)>>16) ^ ((a)>>8) ^(a)) & CLIENT_HASHMASK)
/* XXX: is this adequate for 32bit kdev_t ? */
#define EXPORT_HASH(dev)	((dev) & (NFSCLNT_EXPMAX - 1))
#define EXPORT_FSID_HASH(fsid)	((fsid) & (NFSCLNT_EXPMAX - 1))

struct svc_clnthash {
	struct svc_clnthash *	h_next;
	struct in_addr		h_addr;
	struct svc_client *	h_client;
};
static struct svc_clnthash *	clnt_hash[CLIENT_HASHMAX];
static svc_client *		clients;

static int			hash_lock;
static int			want_lock;
static int			hash_count;
static DECLARE_WAIT_QUEUE_HEAD(	hash_wait );

/*
 * Find the client's export entry matching xdev/xino.
 */
svc_export *
exp_get(svc_client *clp, kdev_t dev, ino_t ino)
{
	struct list_head *head, *p;

	if (!clp)
		return NULL;

	head = &clp->cl_export[EXPORT_HASH(dev)];
	list_for_each(p, head) {
		svc_export *exp = list_entry(p, svc_export, ex_hash);
		if (exp->ex_ino == ino && exp->ex_dev == dev)
			return exp;
	}

	return NULL;
}

/*
 * Find the client's export entry matching fsid
 */
svc_export *
exp_get_fsid(svc_client *clp, int fsid)
{
	struct list_head *head, *p;

	if (!clp)
		return NULL;

	head = &clp->cl_expfsid[EXPORT_FSID_HASH(fsid)];
	list_for_each(p, head) {
		svc_export *exp = list_entry(p, svc_export, ex_fsid_hash);
		if (exp->ex_fsid == fsid)
			return exp;
	}
	return NULL;
}

/*
 * Find the export entry for a given dentry.  <gam3@acm.org>
 */
static svc_export *
exp_parent(svc_client *clp, kdev_t dev, struct dentry *dentry)
{
	struct list_head *head = &clp->cl_export[EXPORT_HASH(dev)];
	struct list_head *p;

	list_for_each(p,head) {
		svc_export *exp = list_entry(p, svc_export, ex_hash);
		if (is_subdir(dentry, exp->ex_dentry))
			return exp;
	}
	return NULL;
}

/*
 * Find the child export entry for a given fs. This function is used
 * only by the export syscall to keep the export tree consistent.
 * <gam3@acm.org>
 */
static svc_export *
exp_child(svc_client *clp, kdev_t dev, struct dentry *dentry)
{
	struct list_head *head = &clp->cl_export[EXPORT_HASH(dev)];
	struct list_head *p;


	list_for_each(p, head) {
		svc_export *exp = list_entry(p, svc_export, ex_hash);
		struct dentry *ndentry = exp->ex_dentry;

		if (ndentry && is_subdir(ndentry->d_parent, dentry))
			return exp;
	}
	return NULL;
}

/* Update parent pointers of all exports */
static void exp_change_parents(svc_client *clp, svc_export *old, svc_export *new)
{
	struct list_head *head = &clp->cl_list;
	struct list_head *p;

	list_for_each(p, head) {
		svc_export *exp = list_entry(p, svc_export, ex_list);
		if (exp->ex_parent == old)
			exp->ex_parent = new;
	}
}

static void exp_fsid_unhash(struct svc_export *exp)
{

	if ((exp->ex_flags & NFSEXP_FSID) == 0)
		return;

	list_del_init(&exp->ex_fsid_hash);
}

static void exp_fsid_hash(struct svc_client *clp, struct svc_export *exp)
{
	struct list_head *head;

	if ((exp->ex_flags & NFSEXP_FSID) == 0)
		return;
	head = clp->cl_expfsid + EXPORT_FSID_HASH(exp->ex_fsid);
	list_add(&exp->ex_fsid_hash, head);
}

/*
 * Export a file system.
 */
int
exp_export(struct nfsctl_export *nxp)
{
	svc_client	*clp;
	svc_export	*exp = NULL, *parent;
	svc_export	*fsid_exp;
	struct nameidata nd;
	struct inode	*inode = NULL;
	int		err;
	kdev_t		dev;
	ino_t		ino;

	/* Consistency check */
	err = -EINVAL;
	if (!exp_verify_string(nxp->ex_path, NFS_MAXPATHLEN) ||
	    !exp_verify_string(nxp->ex_client, NFSCLNT_IDMAX))
		goto out;

	dprintk("exp_export called for %s:%s (%x/%ld fl %x).\n",
			nxp->ex_client, nxp->ex_path,
			nxp->ex_dev, (long) nxp->ex_ino, nxp->ex_flags);

	/* Try to lock the export table for update */
	if ((err = exp_writelock()) < 0)
		goto out;

	/* Look up client info */
	err = -EINVAL;
	if (!(clp = exp_getclientbyname(nxp->ex_client)))
		goto out_unlock;


	/* Look up the dentry */
	err = 0;
	if (path_init(nxp->ex_path, LOOKUP_POSITIVE, &nd))
		err = path_walk(nxp->ex_path, &nd);
	if (err)
		goto out_unlock;

	inode = nd.dentry->d_inode;
	dev = inode->i_dev;
	ino = inode->i_ino;
	err = -EINVAL;

	exp = exp_get(clp, dev, ino);

	/* must make sure there wont be an ex_fsid clash */
	if ((nxp->ex_flags & NFSEXP_FSID) &&
	    (fsid_exp = exp_get_fsid(clp, nxp->ex_dev)) &&
	    fsid_exp != exp)
		goto finish;

	if (exp != NULL) {
		/* just a flags/id/fsid update */

		exp_fsid_unhash(exp);
		exp->ex_flags    = nxp->ex_flags;
		exp->ex_anon_uid = nxp->ex_anon_uid;
		exp->ex_anon_gid = nxp->ex_anon_gid;
		exp->ex_fsid     = nxp->ex_dev;
		exp_fsid_hash(clp, exp);
		err = 0;
		goto finish;
	}

	/* We currently export only dirs and regular files.
	 * This is what umountd does.
	 */
	err = -ENOTDIR;
	if (!S_ISDIR(inode->i_mode) && !S_ISREG(inode->i_mode))
		goto finish;

	err = -EINVAL;
	/* There are two requirements on a filesystem to be exportable.
	 * 1:  We must be able to identify the filesystem from a number.
	 *       either a device number (so FS_REQUIRES_DEV needed)
	 *       or an FSID number (so NFSEXP_FSID needed).
	 * 2:  We must be able to find an inode from a filehandle.
	 *       either using fh_to_dentry (prefered)
	 *       or using read_inode (the hack).
	 */
	if (!((inode->i_sb->s_type->fs_flags & FS_REQUIRES_DEV)
	      || (nxp->ex_flags & NFSEXP_FSID))
	    ||
	    (inode->i_sb->s_op->read_inode == NULL
	     && inode->i_sb->s_op->fh_to_dentry == NULL)) {
		dprintk("exp_export: export of invalid fs type.\n");
		goto finish;
	}

	if ((parent = exp_child(clp, dev, nd.dentry)) != NULL) {
		dprintk("exp_export: export not valid (Rule 3).\n");
		goto finish;
	}
	/* Is this is a sub-export, must be a proper subset of FS */
	if ((parent = exp_parent(clp, dev, nd.dentry)) != NULL) {
		dprintk("exp_export: sub-export not valid (Rule 2).\n");
		goto finish;
	}

	err = -ENOMEM;
	if (!(exp = kmalloc(sizeof(*exp), GFP_USER)))
		goto finish;
	dprintk("nfsd: created export entry %p for client %p\n", exp, clp);

	strcpy(exp->ex_path, nxp->ex_path);
	exp->ex_client = clp;
	exp->ex_parent = parent;
	exp->ex_dentry = dget(nd.dentry);
	exp->ex_mnt = mntget(nd.mnt);
	exp->ex_flags = nxp->ex_flags;
	exp->ex_dev = dev;
	exp->ex_ino = ino;
	exp->ex_anon_uid = nxp->ex_anon_uid;
	exp->ex_anon_gid = nxp->ex_anon_gid;
	exp->ex_fsid = nxp->ex_dev;


	/* Update parent pointers of all exports */
	if (parent)
		exp_change_parents(clp, parent, exp);

	list_add(&exp->ex_hash, clp->cl_export + EXPORT_HASH(dev));
	list_add_tail(&exp->ex_list, &clp->cl_list);

	exp_fsid_hash(clp, exp);

	err = 0;

finish:
	path_release(&nd);
out_unlock:
	exp_unlock();
out:
	return err;
}

/*
 * Unexport a file system. The export entry has already
 * been removed from the client's list of exported fs's.
 */
static void
exp_do_unexport(svc_export *unexp)
{
	struct dentry	*dentry;
	struct vfsmount *mnt;
	struct inode	*inode;

	list_del(&unexp->ex_hash);
	list_del(&unexp->ex_list);
	exp_fsid_unhash(unexp);

	exp_change_parents(unexp->ex_client, unexp, unexp->ex_parent);

	dentry = unexp->ex_dentry;
	mnt = unexp->ex_mnt;
	inode = dentry->d_inode;
	if (unexp->ex_dev != inode->i_dev || unexp->ex_ino != inode->i_ino)
		printk(KERN_WARNING "nfsd: bad dentry in unexport!\n");
	dput(dentry);
	mntput(mnt);

	kfree(unexp);
}

/*
 * Revoke all exports for a given client.
 * This may look very awkward, but we have to do it this way in order
 * to avoid race conditions (aka mind the parent pointer).
 */
static void
exp_unexport_all(svc_client *clp)
{
	struct list_head *p = &clp->cl_list;

	dprintk("unexporting all fs's for clnt %p\n", clp);

	while (!list_empty(p)) {
		svc_export *exp = list_entry(p->next, svc_export, ex_list);
		exp_do_unexport(exp);
	}
}

/*
 * unexport syscall.
 */
int
exp_unexport(struct nfsctl_export *nxp)
{
	svc_client	*clp;
	int		err;

	/* Consistency check */
	if (!exp_verify_string(nxp->ex_client, NFSCLNT_IDMAX))
		return -EINVAL;

	if ((err = exp_writelock()) < 0)
		goto out;

	err = -EINVAL;
	clp = exp_getclientbyname(nxp->ex_client);
	if (clp) {
		svc_export *exp = exp_get(clp, nxp->ex_dev, nxp->ex_ino);
		if (exp) {
			exp_do_unexport(exp);
			err = 0;
		}
	}

	exp_unlock();
out:
	return err;
}

/*
 * Obtain the root fh on behalf of a client.
 * This could be done in user space, but I feel that it adds some safety
 * since its harder to fool a kernel module than a user space program.
 */
int
exp_rootfh(struct svc_client *clp, kdev_t dev, ino_t ino,
	   char *path, struct knfsd_fh *f, int maxsize)
{
	struct svc_export	*exp;
	struct nameidata	nd;
	struct inode		*inode;
	struct svc_fh		fh;
	int			err;

	err = -EPERM;
	if (path) {
		if (path_init(path, LOOKUP_POSITIVE, &nd) &&
		    path_walk(path, &nd)) {
			printk("nfsd: exp_rootfh path not found %s", path);
			return err;
		}
		dev = nd.dentry->d_inode->i_dev;
		ino = nd.dentry->d_inode->i_ino;
	
		dprintk("nfsd: exp_rootfh(%s [%p] %s:%x/%ld)\n",
		         path, nd.dentry, clp->cl_ident, dev, (long) ino);
		exp = exp_parent(clp, dev, nd.dentry);
	} else {
		dprintk("nfsd: exp_rootfh(%s:%x/%ld)\n",
		         clp->cl_ident, dev, (long) ino);
		if ((exp = exp_get(clp, dev, ino))) {
			nd.mnt = mntget(exp->ex_mnt);
			nd.dentry = dget(exp->ex_dentry);
		}
	}
	if (!exp) {
		dprintk("nfsd: exp_rootfh export not found.\n");
		goto out;
	}

	inode = nd.dentry->d_inode;
	if (!inode) {
		printk("exp_rootfh: Aieee, NULL d_inode\n");
		goto out;
	}
	if (inode->i_dev != dev || inode->i_ino != ino) {
		printk("exp_rootfh: Aieee, ino/dev mismatch\n");
		printk("exp_rootfh: arg[dev(%x):ino(%ld)]"
		       " inode[dev(%x):ino(%ld)]\n",
		       dev, (long) ino, inode->i_dev, (long) inode->i_ino);
	}

	/*
	 * fh must be initialized before calling fh_compose
	 */
	fh_init(&fh, maxsize);
	if (fh_compose(&fh, exp, dget(nd.dentry), NULL))
		err = -EINVAL;
	else
		err = 0;
	memcpy(f, &fh.fh_handle, sizeof(struct knfsd_fh));
	fh_put(&fh);

out:
	if (path)
		path_release(&nd);
	return err;
}

/*
 * Hashtable locking. Write locks are placed only by user processes
 * wanting to modify export information.
 */
void
exp_readlock(void)
{
	while (hash_lock || want_lock)
		sleep_on(&hash_wait);
	hash_count++;
}

int
exp_writelock(void)
{
	/* fast track */
	if (!hash_count && !hash_lock) {
	lock_it:
		hash_lock = 1;
		return 0;
	}

	current->sigpending = 0;
	want_lock++;
	while (hash_count || hash_lock) {
		interruptible_sleep_on(&hash_wait);
		if (signal_pending(current))
			break;
	}
	want_lock--;

	/* restore the task's signals */
	spin_lock_irq(&current->sigmask_lock);
	recalc_sigpending(current);
	spin_unlock_irq(&current->sigmask_lock);

	if (!hash_count && !hash_lock)
		goto lock_it;
	return -EINTR;
}

void
exp_unlock(void)
{
	if (!hash_count && !hash_lock)
		printk(KERN_WARNING "exp_unlock: not locked!\n");
	if (hash_count)
		hash_count--;
	else
		hash_lock = 0;
	wake_up(&hash_wait);
}

/*
 * Find a valid client given an inet address. We always move the most
 * recently used client to the front of the hash chain to speed up
 * future lookups.
 * Locking against other processes is the responsibility of the caller.
 */
struct svc_client *
exp_getclient(struct sockaddr_in *sin)
{
	struct svc_clnthash	**hp, **head, *tmp;
	unsigned long		addr = sin->sin_addr.s_addr;

	head = &clnt_hash[CLIENT_HASH(addr)];

	for (hp = head; (tmp = *hp) != NULL; hp = &(tmp->h_next)) {
		if (tmp->h_addr.s_addr == addr) {
			/* Move client to the front */
			if (head != hp) {
				*hp = tmp->h_next;
				tmp->h_next = *head;
				*head = tmp;
			}

			return tmp->h_client;
		}
	}

	return NULL;
}

/*
 * Find a client given its identifier.
 */
static svc_client *
exp_getclientbyname(char *ident)
{
	svc_client *	clp;

	for (clp = clients; clp; clp = clp->cl_next) {
		if (!strcmp(clp->cl_ident, ident))
			return clp;
	}
	return NULL;
}

/* Iterator */

static void *e_start(struct seq_file *m, loff_t *pos)
{
	loff_t n = *pos;
	unsigned client, export;
	svc_client *clp;
	struct list_head *p;
	
	exp_readlock();
	if (!n--)
		return (void *)1;
	client = n >> 32;
	export = n & ((1LL<<32) - 1);
	for (clp = clients; client && clp; clp = clp->cl_next, client--)
		;
	if (!clp)
		return NULL;
	list_for_each(p, &clp->cl_list)
		if (!export--)
			return list_entry(p, svc_export, ex_list);
	n &= ~((1LL<<32) - 1);
	do {
		clp = clp->cl_next;
		n += 1LL<<32;
	} while(clp && list_empty(&clp->cl_list));
	if (!clp)
		return NULL;
	*pos = n+1;
	return list_entry(clp->cl_list.next, svc_export, ex_list);
}

static void *e_next(struct seq_file *m, void *p, loff_t *pos)
{
	svc_export *exp = p;
	svc_client *clp;

	if (p == (void *)1)
		clp = clients;
	else if (exp->ex_list.next == &exp->ex_client->cl_list) {
		clp = exp->ex_client->cl_next;
		*pos += 1LL<<32;
	} else {
		++*pos;
		return list_entry(exp->ex_list.next, svc_export, ex_list);
	}
	*pos &= ~((1LL<<32) - 1);
	while (clp && list_empty(&clp->cl_list)) {
		clp = clp->cl_next;
		*pos += 1LL<<32;
	}
	if (!clp)
		return NULL;
	++*pos;
	return list_entry(clp->cl_list.next, svc_export, ex_list);
}

static void e_stop(struct seq_file *m, void *p)
{
	exp_unlock();
}

struct flags {
	int flag;
	char *name[2];
} expflags[] = {
	{ NFSEXP_READONLY, {"ro", "rw"}},
	{ NFSEXP_INSECURE_PORT, {"insecure", ""}},
	{ NFSEXP_ROOTSQUASH, {"root_squash", "no_root_squash"}},
	{ NFSEXP_ALLSQUASH, {"all_squash", ""}},
	{ NFSEXP_ASYNC, {"async", "sync"}},
	{ NFSEXP_GATHERED_WRITES, {"wdelay", "no_wdelay"}},
	{ NFSEXP_UIDMAP, {"uidmap", ""}},
	{ NFSEXP_KERBEROS, { "kerberos", ""}},
	{ NFSEXP_SUNSECURE, { "sunsecure", ""}},
	{ NFSEXP_CROSSMNT, {"nohide", ""}},
	{ NFSEXP_NOSUBTREECHECK, {"no_subtree_check", ""}},
	{ NFSEXP_NOAUTHNLM, {"insecure_locks", ""}},
#ifdef MSNFS
	{ NFSEXP_MSNFS, {"msnfs", ""}},
#endif
	{ 0, {"", ""}}
};

static void exp_flags(struct seq_file *m, int flag, int fsid)
{
	int first = 0;
	struct flags *flg;

	for (flg = expflags; flg->flag; flg++) {
		int state = (flg->flag & flag)?0:1;
		if (*flg->name[state])
			seq_printf(m, "%s%s", first++?",":"", flg->name[state]);
	}
	if (flag & NFSEXP_FSID)
		seq_printf(m, "%sfsid=%d", first++?",":"", fsid);
}

static inline void mangle(struct seq_file *m, const char *s)
{
	seq_escape(m, s, " \t\n\\");
}

static int e_show(struct seq_file *m, void *p)
{
	struct svc_export *exp = p;
	struct svc_client *clp;
	int j, first = 0;

	if (p == (void *)1) {
		seq_puts(m, "# Version 1.1\n");
		seq_puts(m, "# Path Client(Flags) # IPs\n");
		return 0;
	}

	clp = exp->ex_client;

	mangle(m, exp->ex_path);
	seq_putc(m, '\t');
	mangle(m, clp->cl_ident);
	seq_putc(m, '(');
	exp_flags(m, exp->ex_flags, exp->ex_fsid);
	seq_puts(m, ") # ");
	for (j = 0; j < clp->cl_naddr; j++) {
		struct svc_clnthash **hp, **head, *tmp;
		struct in_addr addr = clp->cl_addr[j]; 

		head = &clnt_hash[CLIENT_HASH(addr.s_addr)];
		for (hp = head; (tmp = *hp) != NULL; hp = &(tmp->h_next)) {
			if (tmp->h_addr.s_addr == addr.s_addr)
				break;
		}
		if (tmp) {
			if (first++)
				seq_putc(m, ' ');
			if (tmp->h_client != clp)
				seq_putc(m, '(');
			seq_printf(m, "%d.%d.%d.%d",
				htonl(addr.s_addr) >> 24 & 0xff,
				htonl(addr.s_addr) >> 16 & 0xff,
				htonl(addr.s_addr) >>  8 & 0xff,
				htonl(addr.s_addr) >>  0 & 0xff);
			if (tmp->h_client != clp)
				seq_putc(m, ')');
		}
	}
	seq_putc(m, '\n');
	return 0;
}

struct seq_operations nfs_exports_op = {
	start:	e_start,
	next:	e_next,
	stop:	e_stop,
	show:	e_show,
};

/*
 * Add or modify a client.
 * Change requests may involve the list of host addresses. The list of
 * exports and possibly existing uid maps are left untouched.
 */
int
exp_addclient(struct nfsctl_client *ncp)
{
	struct svc_clnthash *	ch[NFSCLNT_ADDRMAX];
	svc_client *		clp;
	int			i, err, change = 0, ilen;

	/* First, consistency check. */
	err = -EINVAL;
	if (!(ilen = exp_verify_string(ncp->cl_ident, NFSCLNT_IDMAX)))
		goto out;
	if (ncp->cl_naddr > NFSCLNT_ADDRMAX)
		goto out;

	/* Lock the hashtable */
	if ((err = exp_writelock()) < 0)
		goto out;

	/* First check if this is a change request for a client. */
	for (clp = clients; clp; clp = clp->cl_next)
		if (!strcmp(clp->cl_ident, ncp->cl_ident))
			break;

	err = -ENOMEM;
	if (clp) {
		change = 1;
	} else {
		if (!(clp = kmalloc(sizeof(*clp), GFP_KERNEL)))
			goto out_unlock;
		memset(clp, 0, sizeof(*clp));
		for (i = 0; i < NFSCLNT_EXPMAX; i++) {
			INIT_LIST_HEAD(&clp->cl_export[i]);
			INIT_LIST_HEAD(&clp->cl_expfsid[i]);
		}
		INIT_LIST_HEAD(&clp->cl_list);

		dprintk("created client %s (%p)\n", ncp->cl_ident, clp);

		strcpy(clp->cl_ident, ncp->cl_ident);
		clp->cl_idlen = ilen;
	}

	/* Allocate hash buckets */
	for (i = 0; i < ncp->cl_naddr; i++) {
		ch[i] = kmalloc(sizeof(struct svc_clnthash), GFP_KERNEL);
		if (!ch[i]) {
			while (i--)
				kfree(ch[i]);
			if (!change)
				kfree(clp);
			goto out_unlock;
		}
	}

	/* Copy addresses. */
	for (i = 0; i < ncp->cl_naddr; i++) {
		clp->cl_addr[i] = ncp->cl_addrlist[i];
	}
	clp->cl_naddr = ncp->cl_naddr;

	/* Remove old client hash entries. */
	if (change)
		exp_unhashclient(clp);

	/* Insert client into hashtable. */
	for (i = 0; i < ncp->cl_naddr; i++) {
		struct in_addr	addr = clp->cl_addr[i];
		int		hash;

		hash = CLIENT_HASH(addr.s_addr);
		ch[i]->h_client = clp;
		ch[i]->h_addr = addr;
		ch[i]->h_next = clnt_hash[hash];
		clnt_hash[hash] = ch[i];
	}

	if (!change) {
		clp->cl_next = clients;
		clients = clp;
	}
	err = 0;

out_unlock:
	exp_unlock();
out:
	return err;
}

/*
 * Delete a client given an identifier.
 */
int
exp_delclient(struct nfsctl_client *ncp)
{
	svc_client	**clpp, *clp;
	int		err;

	err = -EINVAL;
	if (!exp_verify_string(ncp->cl_ident, NFSCLNT_IDMAX))
		goto out;

	/* Lock the hashtable */
	if ((err = exp_writelock()) < 0)
		goto out;

	err = -EINVAL;
	for (clpp = &clients; (clp = *clpp); clpp = &(clp->cl_next))
		if (!strcmp(ncp->cl_ident, clp->cl_ident))
			break;

	if (clp) {
		*clpp = clp->cl_next;
		exp_freeclient(clp);
		err = 0;
	}

	exp_unlock();
out:
	return err;
}

/*
 * Free a client. The caller has already removed it from the client list.
 */
static void
exp_freeclient(svc_client *clp)
{
	exp_unhashclient(clp);

	/* umap_free(&(clp->cl_umap)); */
	exp_unexport_all(clp);
	nfsd_lockd_unexport(clp);
	kfree (clp);
}

/*
 * Remove client from hashtable. We first collect all hashtable
 * entries and free them in one go.
 * The hash table must be writelocked by the caller.
 */
static void
exp_unhashclient(svc_client *clp)
{
	struct svc_clnthash	**hpp, *hp, *ch[NFSCLNT_ADDRMAX];
	int			i, count, err;

again:
	err = 0;
	for (i = 0, count = 0; i < CLIENT_HASHMAX && !err; i++) {
		hpp = clnt_hash + i;
		while ((hp = *hpp) && !err) {
			if (hp->h_client == clp) {
				*hpp = hp->h_next;
				ch[count++] = hp;
				err = (count >= NFSCLNT_ADDRMAX);
			} else {
				hpp = &(hp->h_next);
			}
		}
	}
	if (count != clp->cl_naddr)
		printk(KERN_WARNING "nfsd: bad address count in freeclient!\n");
	if (err)
		goto again;
	for (i = 0; i < count; i++)
		kfree (ch[i]);
}

/*
 * Lockd is shutting down and tells us to unregister all clients
 */
void
exp_nlmdetach(void)
{
	struct svc_client	*clp;

	for (clp = clients; clp; clp = clp->cl_next)
		nfsd_lockd_unexport(clp);
}

/*
 * Verify that string is non-empty and does not exceed max length.
 */
static int
exp_verify_string(char *cp, int max)
{
	int	i;

	for (i = 0; i < max; i++)
		if (!cp[i])
			return i;
	cp[i] = 0;
	printk(KERN_NOTICE "nfsd: couldn't validate string %s\n", cp);
	return 0;
}

/*
 * Initialize the exports module.
 */
void
nfsd_export_init(void)
{
	int		i;

	dprintk("nfsd: initializing export module.\n");

	for (i = 0; i < CLIENT_HASHMAX; i++)
		clnt_hash[i] = NULL;
	clients = NULL;

}

/*
 * Shutdown the exports module.
 */
void
nfsd_export_shutdown(void)
{
	int	i;

	dprintk("nfsd: shutting down export module.\n");

	if (exp_writelock() < 0) {
		printk(KERN_WARNING "Weird: hashtable locked in exp_shutdown");
		return;
	}
	for (i = 0; i < CLIENT_HASHMAX; i++) {
		while (clnt_hash[i])
			exp_freeclient(clnt_hash[i]->h_client);
	}
	clients = NULL; /* we may be restarted before the module unloads */
	
	exp_unlock();
	dprintk("nfsd: export shutdown complete.\n");
}
