/*

   * 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/slab.h>

  #include <linux/namei.h>

  #include <linux/module.h>

  #include <linux/exportfs.h>

  #include <linux/sunrpc/svc_xprt.h>

  #include "nfsd.h"

  #include "nfsfh.h"

  #include "netns.h"

  #include "pnfs.h"

  #define NFSDDBG_FACILITY	NFSDDBG_EXPORT

  /*
   * We have two caches.
   * One maps client+vfsmnt+dentry to export options - the export map
   * The other maps client+filehandle-fragment to export options. - the expkey map
   *
   * The export options are actually stored in the first map, and the
   * second map contains a reference to the entry in the first map.
   */
  
  #define	EXPKEY_HASHBITS		8
  #define	EXPKEY_HASHMAX		(1 << EXPKEY_HASHBITS)
  #define	EXPKEY_HASHMASK		(EXPKEY_HASHMAX -1)

  static void expkey_put(struct kref *ref)

  {

  	struct svc_expkey *key = container_of(ref, struct svc_expkey, h.ref);
  
  	if (test_bit(CACHE_VALID, &key->h.flags) &&

  	    !test_bit(CACHE_NEGATIVE, &key->h.flags))
  		path_put(&key->ek_path);

  	auth_domain_put(key->ek_client);
  	kfree(key);

  }
  
  static void expkey_request(struct cache_detail *cd,
  			   struct cache_head *h,
  			   char **bpp, int *blen)
  {
  	/* client fsidtype \xfsid */
  	struct svc_expkey *ek = container_of(h, struct svc_expkey, h);
  	char type[5];
  
  	qword_add(bpp, blen, ek->ek_client->name);
  	snprintf(type, 5, "%d", ek->ek_fsidtype);
  	qword_add(bpp, blen, type);
  	qword_addhex(bpp, blen, (char*)ek->ek_fsid, key_len(ek->ek_fsidtype));
  	(*bpp)[-1] = '
  ';
  }

  static struct svc_expkey *svc_expkey_update(struct cache_detail *cd, struct svc_expkey *new,
  					    struct svc_expkey *old);
  static struct svc_expkey *svc_expkey_lookup(struct cache_detail *cd, struct svc_expkey *);

  static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen)
  {

  	/* client fsidtype fsid expiry [path] */

  	char *buf;
  	int len;
  	struct auth_domain *dom = NULL;
  	int err;
  	int fsidtype;
  	char *ep;
  	struct svc_expkey key;

  	struct svc_expkey *ek = NULL;

  	if (mesg[mlen - 1] != '
  ')

  		return -EINVAL;
  	mesg[mlen-1] = 0;
  
  	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
  	err = -ENOMEM;

  	if (!buf)
  		goto out;

  
  	err = -EINVAL;
  	if ((len=qword_get(&mesg, buf, PAGE_SIZE)) <= 0)
  		goto out;
  
  	err = -ENOENT;
  	dom = auth_domain_find(buf);
  	if (!dom)
  		goto out;
  	dprintk("found domain %s
  ", buf);
  
  	err = -EINVAL;
  	if ((len=qword_get(&mesg, buf, PAGE_SIZE)) <= 0)
  		goto out;
  	fsidtype = simple_strtoul(buf, &ep, 10);
  	if (*ep)
  		goto out;
  	dprintk("found fsidtype %d
  ", fsidtype);

  	if (key_len(fsidtype)==0) /* invalid type */

  		goto out;
  	if ((len=qword_get(&mesg, buf, PAGE_SIZE)) <= 0)
  		goto out;
  	dprintk("found fsid length %d
  ", len);
  	if (len != key_len(fsidtype))
  		goto out;
  
  	/* OK, we seem to have a valid key */
  	key.h.flags = 0;
  	key.h.expiry_time = get_expiry(&mesg);
  	if (key.h.expiry_time == 0)
  		goto out;
  
  	key.ek_client = dom;	
  	key.ek_fsidtype = fsidtype;
  	memcpy(key.ek_fsid, buf, len);

  	ek = svc_expkey_lookup(cd, &key);

  	err = -ENOMEM;
  	if (!ek)
  		goto out;

  	/* now we want a pathname, or empty meaning NEGATIVE  */

  	err = -EINVAL;

  	len = qword_get(&mesg, buf, PAGE_SIZE);
  	if (len < 0)

  		goto out;
  	dprintk("Path seems to be <%s>
  ", buf);
  	err = 0;
  	if (len == 0) {

  		set_bit(CACHE_NEGATIVE, &key.h.flags);

  		ek = svc_expkey_update(cd, &key, ek);

  		if (!ek)
  			err = -ENOMEM;

  	} else {

  		err = kern_path(buf, 0, &key.ek_path);

  		if (err)

  			goto out;
  
  		dprintk("Found the path %s
  ", buf);

  		ek = svc_expkey_update(cd, &key, ek);

  		if (!ek)

  			err = -ENOMEM;

  		path_put(&key.ek_path);

  	}
  	cache_flush();
   out:

  	if (ek)

  		cache_put(&ek->h, cd);

  	if (dom)
  		auth_domain_put(dom);

  	kfree(buf);

  	return err;
  }
  
  static int expkey_show(struct seq_file *m,
  		       struct cache_detail *cd,
  		       struct cache_head *h)
  {
  	struct svc_expkey *ek ;

  	int i;

  
  	if (h ==NULL) {
  		seq_puts(m, "#domain fsidtype fsid [path]
  ");
  		return 0;
  	}
  	ek = container_of(h, struct svc_expkey, h);

  	seq_printf(m, "%s %d 0x", ek->ek_client->name,
  		   ek->ek_fsidtype);
  	for (i=0; i < key_len(ek->ek_fsidtype)/4; i++)
  		seq_printf(m, "%08x", ek->ek_fsid[i]);

  	if (test_bit(CACHE_VALID, &h->flags) && 
  	    !test_bit(CACHE_NEGATIVE, &h->flags)) {
  		seq_printf(m, " ");

  		seq_path(m, &ek->ek_path, "\\ \t
  ");

  	}
  	seq_printf(m, "
  ");
  	return 0;
  }

  static inline int expkey_match (struct cache_head *a, struct cache_head *b)

  {

  	struct svc_expkey *orig = container_of(a, struct svc_expkey, h);
  	struct svc_expkey *new = container_of(b, struct svc_expkey, h);
  
  	if (orig->ek_fsidtype != new->ek_fsidtype ||
  	    orig->ek_client != new->ek_client ||
  	    memcmp(orig->ek_fsid, new->ek_fsid, key_len(orig->ek_fsidtype)) != 0)

  		return 0;
  	return 1;
  }

  static inline void expkey_init(struct cache_head *cnew,
  				   struct cache_head *citem)

  {

  	struct svc_expkey *new = container_of(cnew, struct svc_expkey, h);
  	struct svc_expkey *item = container_of(citem, struct svc_expkey, h);

  	kref_get(&item->ek_client->ref);

  	new->ek_client = item->ek_client;
  	new->ek_fsidtype = item->ek_fsidtype;

  
  	memcpy(new->ek_fsid, item->ek_fsid, sizeof(new->ek_fsid));

  }

  static inline void expkey_update(struct cache_head *cnew,
  				   struct cache_head *citem)

  {

  	struct svc_expkey *new = container_of(cnew, struct svc_expkey, h);
  	struct svc_expkey *item = container_of(citem, struct svc_expkey, h);

  	new->ek_path = item->ek_path;
  	path_get(&item->ek_path);

  }

  static struct cache_head *expkey_alloc(void)
  {
  	struct svc_expkey *i = kmalloc(sizeof(*i), GFP_KERNEL);
  	if (i)
  		return &i->h;
  	else
  		return NULL;
  }

  static struct cache_detail svc_expkey_cache_template = {

  	.owner		= THIS_MODULE,
  	.hash_size	= EXPKEY_HASHMAX,

  	.name		= "nfsd.fh",
  	.cache_put	= expkey_put,

  	.cache_request	= expkey_request,

  	.cache_parse	= expkey_parse,
  	.cache_show	= expkey_show,
  	.match		= expkey_match,
  	.init		= expkey_init,
  	.update       	= expkey_update,
  	.alloc		= expkey_alloc,
  };

  static int
  svc_expkey_hash(struct svc_expkey *item)

  {

  	int hash = item->ek_fsidtype;
  	char * cp = (char*)item->ek_fsid;
  	int len = key_len(item->ek_fsidtype);
  
  	hash ^= hash_mem(cp, len, EXPKEY_HASHBITS);
  	hash ^= hash_ptr(item->ek_client, EXPKEY_HASHBITS);
  	hash &= EXPKEY_HASHMASK;

  	return hash;
  }
  
  static struct svc_expkey *

  svc_expkey_lookup(struct cache_detail *cd, struct svc_expkey *item)

  {
  	struct cache_head *ch;
  	int hash = svc_expkey_hash(item);

  	ch = sunrpc_cache_lookup(cd, &item->h, hash);

  	if (ch)
  		return container_of(ch, struct svc_expkey, h);
  	else
  		return NULL;
  }
  
  static struct svc_expkey *

  svc_expkey_update(struct cache_detail *cd, struct svc_expkey *new,
  		  struct svc_expkey *old)

  {
  	struct cache_head *ch;

  	int hash = svc_expkey_hash(new);

  	ch = sunrpc_cache_update(cd, &new->h, &old->h, hash);

  	if (ch)
  		return container_of(ch, struct svc_expkey, h);
  	else
  		return NULL;
  }

  
  #define	EXPORT_HASHBITS		8
  #define	EXPORT_HASHMAX		(1<< EXPORT_HASHBITS)

  static void nfsd4_fslocs_free(struct nfsd4_fs_locations *fsloc)
  {

  	struct nfsd4_fs_location *locations = fsloc->locations;

  	int i;

  	if (!locations)
  		return;

  	for (i = 0; i < fsloc->locations_count; i++) {

  		kfree(locations[i].path);
  		kfree(locations[i].hosts);

  	}

  
  	kfree(locations);
  	fsloc->locations = NULL;

  }

  static void svc_export_put(struct kref *ref)

  {

  	struct svc_export *exp = container_of(ref, struct svc_export, h.ref);

  	path_put(&exp->ex_path);

  	auth_domain_put(exp->ex_client);

  	nfsd4_fslocs_free(&exp->ex_fslocs);

  	kfree(exp->ex_uuid);

  	kfree(exp);

  }
  
  static void svc_export_request(struct cache_detail *cd,
  			       struct cache_head *h,
  			       char **bpp, int *blen)
  {
  	/*  client path */
  	struct svc_export *exp = container_of(h, struct svc_export, h);
  	char *pth;
  
  	qword_add(bpp, blen, exp->ex_client->name);

  	pth = d_path(&exp->ex_path, *bpp, *blen);

  	if (IS_ERR(pth)) {
  		/* is this correct? */
  		(*bpp)[0] = '
  ';
  		return;
  	}
  	qword_add(bpp, blen, pth);
  	(*bpp)[-1] = '
  ';
  }

  static struct svc_export *svc_export_update(struct svc_export *new,
  					    struct svc_export *old);

  static struct svc_export *svc_export_lookup(struct svc_export *);

  static int check_export(struct inode *inode, int *flags, unsigned char *uuid)

  {

  	/*
  	 * We currently export only dirs, regular files, and (for v4
  	 * pseudoroot) symlinks.

  	 */
  	if (!S_ISDIR(inode->i_mode) &&

  	    !S_ISLNK(inode->i_mode) &&

  	    !S_ISREG(inode->i_mode))
  		return -ENOTDIR;

  	/*
  	 * Mountd should never pass down a writeable V4ROOT export, but,
  	 * just to make sure:
  	 */
  	if (*flags & NFSEXP_V4ROOT)
  		*flags |= NFSEXP_READONLY;

  	/* 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 or ->uuid is needed).

  	 * 2:  We must be able to find an inode from a filehandle.
  	 *       This means that s_export_op must be set.
  	 */
  	if (!(inode->i_sb->s_type->fs_flags & FS_REQUIRES_DEV) &&

  	    !(*flags & NFSEXP_FSID) &&

  	    uuid == NULL) {

  		dprintk("exp_export: export of non-dev fs without fsid
  ");

  		return -EINVAL;
  	}

  
  	if (!inode->i_sb->s_export_op ||
  	    !inode->i_sb->s_export_op->fh_to_dentry) {

  		dprintk("exp_export: export of invalid fs type.
  ");
  		return -EINVAL;
  	}

  	return 0;
  
  }

  #ifdef CONFIG_NFSD_V4
  
  static int
  fsloc_parse(char **mesg, char *buf, struct nfsd4_fs_locations *fsloc)
  {
  	int len;
  	int migrated, i, err;

  	/* more than one fsloc */
  	if (fsloc->locations)
  		return -EINVAL;

  	/* listsize */

  	err = get_uint(mesg, &fsloc->locations_count);

  	if (err)
  		return err;
  	if (fsloc->locations_count > MAX_FS_LOCATIONS)
  		return -EINVAL;
  	if (fsloc->locations_count == 0)
  		return 0;
  
  	fsloc->locations = kzalloc(fsloc->locations_count
  			* sizeof(struct nfsd4_fs_location), GFP_KERNEL);
  	if (!fsloc->locations)
  		return -ENOMEM;
  	for (i=0; i < fsloc->locations_count; i++) {
  		/* colon separated host list */
  		err = -EINVAL;
  		len = qword_get(mesg, buf, PAGE_SIZE);
  		if (len <= 0)
  			goto out_free_all;
  		err = -ENOMEM;
  		fsloc->locations[i].hosts = kstrdup(buf, GFP_KERNEL);
  		if (!fsloc->locations[i].hosts)
  			goto out_free_all;
  		err = -EINVAL;
  		/* slash separated path component list */
  		len = qword_get(mesg, buf, PAGE_SIZE);
  		if (len <= 0)
  			goto out_free_all;
  		err = -ENOMEM;
  		fsloc->locations[i].path = kstrdup(buf, GFP_KERNEL);
  		if (!fsloc->locations[i].path)
  			goto out_free_all;
  	}
  	/* migrated */
  	err = get_int(mesg, &migrated);
  	if (err)
  		goto out_free_all;
  	err = -EINVAL;
  	if (migrated < 0 || migrated > 1)
  		goto out_free_all;
  	fsloc->migrated = migrated;
  	return 0;
  out_free_all:
  	nfsd4_fslocs_free(fsloc);
  	return err;
  }

  static int secinfo_parse(char **mesg, char *buf, struct svc_export *exp)
  {

  	struct exp_flavor_info *f;

  	u32 listsize;
  	int err;

  	/* more than one secinfo */
  	if (exp->ex_nflavors)
  		return -EINVAL;

  	err = get_uint(mesg, &listsize);

  	if (err)
  		return err;

  	if (listsize > MAX_SECINFO_LIST)

  		return -EINVAL;
  
  	for (f = exp->ex_flavors; f < exp->ex_flavors + listsize; f++) {

  		err = get_uint(mesg, &f->pseudoflavor);

  		if (err)
  			return err;
  		/*

  		 * XXX: It would be nice to also check whether this
  		 * pseudoflavor is supported, so we can discover the
  		 * problem at export time instead of when a client fails
  		 * to authenticate.

  		 */

  		err = get_uint(mesg, &f->flags);

  		if (err)
  			return err;
  		/* Only some flags are allowed to differ between flavors: */
  		if (~NFSEXP_SECINFO_FLAGS & (f->flags ^ exp->ex_flags))
  			return -EINVAL;
  	}
  	exp->ex_nflavors = listsize;
  	return 0;
  }

  #else /* CONFIG_NFSD_V4 */

  static inline int
  fsloc_parse(char **mesg, char *buf, struct nfsd4_fs_locations *fsloc){return 0;}
  static inline int
  secinfo_parse(char **mesg, char *buf, struct svc_export *exp) { return 0; }

  #endif

  static inline int
  uuid_parse(char **mesg, char *buf, unsigned char **puuid)
  {
  	int len;

  	/* more than one uuid */
  	if (*puuid)
  		return -EINVAL;

  	/* expect a 16 byte uuid encoded as \xXXXX... */
  	len = qword_get(mesg, buf, PAGE_SIZE);

  	if (len != EX_UUID_LEN)

  		return -EINVAL;

  	*puuid = kmemdup(buf, EX_UUID_LEN, GFP_KERNEL);

  	if (*puuid == NULL)
  		return -ENOMEM;
  
  	return 0;
  }

  static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen)
  {
  	/* client path expiry [flags anonuid anongid fsid] */
  	char *buf;
  	int len;
  	int err;
  	struct auth_domain *dom = NULL;

  	struct svc_export exp = {}, *expp;

  	int an_int;

  	if (mesg[mlen-1] != '
  ')
  		return -EINVAL;
  	mesg[mlen-1] = 0;
  
  	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);

  	if (!buf)
  		return -ENOMEM;

  
  	/* client */

  	err = -EINVAL;

  	len = qword_get(&mesg, buf, PAGE_SIZE);
  	if (len <= 0)
  		goto out;

  
  	err = -ENOENT;
  	dom = auth_domain_find(buf);
  	if (!dom)
  		goto out;
  
  	/* path */
  	err = -EINVAL;

  	if ((len = qword_get(&mesg, buf, PAGE_SIZE)) <= 0)
  		goto out1;
  
  	err = kern_path(buf, 0, &exp.ex_path);
  	if (err)
  		goto out1;

  	exp.ex_client = dom;

  	exp.cd = cd;

  	exp.ex_devid_map = NULL;

  	/* expiry */
  	err = -EINVAL;
  	exp.h.expiry_time = get_expiry(&mesg);
  	if (exp.h.expiry_time == 0)

  		goto out3;

  
  	/* flags */
  	err = get_int(&mesg, &an_int);

  	if (err == -ENOENT) {
  		err = 0;

  		set_bit(CACHE_NEGATIVE, &exp.h.flags);

  	} else {

  		if (err || an_int < 0)
  			goto out3;

  		exp.ex_flags= an_int;
  	
  		/* anon uid */
  		err = get_int(&mesg, &an_int);

  		if (err)
  			goto out3;

  		exp.ex_anon_uid= make_kuid(&init_user_ns, an_int);

  
  		/* anon gid */
  		err = get_int(&mesg, &an_int);

  		if (err)
  			goto out3;

  		exp.ex_anon_gid= make_kgid(&init_user_ns, an_int);

  
  		/* fsid */
  		err = get_int(&mesg, &an_int);

  		if (err)
  			goto out3;

  		exp.ex_fsid = an_int;

  		while ((len = qword_get(&mesg, buf, PAGE_SIZE)) > 0) {
  			if (strcmp(buf, "fsloc") == 0)
  				err = fsloc_parse(&mesg, buf, &exp.ex_fslocs);

  			else if (strcmp(buf, "uuid") == 0)
  				err = uuid_parse(&mesg, buf, &exp.ex_uuid);
  			else if (strcmp(buf, "secinfo") == 0)

  				err = secinfo_parse(&mesg, buf, &exp);
  			else

  				/* quietly ignore unknown words and anything
  				 * following. Newer user-space can try to set
  				 * new values, then see what the result was.
  				 */
  				break;
  			if (err)

  				goto out4;

  		}

  		err = check_export(d_inode(exp.ex_path.dentry), &exp.ex_flags,

  				   exp.ex_uuid);

  		if (err)
  			goto out4;

  		/*

  		 * No point caching this if it would immediately expire.
  		 * Also, this protects exportfs's dummy export from the
  		 * anon_uid/anon_gid checks:
  		 */
  		if (exp.h.expiry_time < seconds_since_boot())
  			goto out4;
  		/*

  		 * For some reason exportfs has been passing down an
  		 * invalid (-1) uid & gid on the "dummy" export which it
  		 * uses to test export support.  To make sure exportfs
  		 * sees errors from check_export we therefore need to
  		 * delay these checks till after check_export:
  		 */

  		err = -EINVAL;

  		if (!uid_valid(exp.ex_anon_uid))
  			goto out4;
  		if (!gid_valid(exp.ex_anon_gid))
  			goto out4;

  		err = 0;

  
  		nfsd4_setup_layout_type(&exp);

  	}

  	expp = svc_export_lookup(&exp);

  	if (expp)

  		expp = svc_export_update(&exp, expp);
  	else
  		err = -ENOMEM;

  	cache_flush();

  	if (expp == NULL)
  		err = -ENOMEM;
  	else
  		exp_put(expp);

  out4:

  	nfsd4_fslocs_free(&exp.ex_fslocs);
  	kfree(exp.ex_uuid);

  out3:

  	path_put(&exp.ex_path);
  out1:
  	auth_domain_put(dom);
  out:

  	kfree(buf);

  	return err;
  }

  static void exp_flags(struct seq_file *m, int flag, int fsid,

  		kuid_t anonu, kgid_t anong, struct nfsd4_fs_locations *fslocs);

  static void show_secinfo(struct seq_file *m, struct svc_export *exp);

  
  static int svc_export_show(struct seq_file *m,
  			   struct cache_detail *cd,
  			   struct cache_head *h)
  {
  	struct svc_export *exp ;
  
  	if (h ==NULL) {
  		seq_puts(m, "#path domain(flags)
  ");
  		return 0;
  	}
  	exp = container_of(h, struct svc_export, h);

  	seq_path(m, &exp->ex_path, " \t
  \\");

  	seq_putc(m, '\t');
  	seq_escape(m, exp->ex_client->name, " \t
  \\");
  	seq_putc(m, '(');
  	if (test_bit(CACHE_VALID, &h->flags) && 

  	    !test_bit(CACHE_NEGATIVE, &h->flags)) {

  		exp_flags(m, exp->ex_flags, exp->ex_fsid,
  			  exp->ex_anon_uid, exp->ex_anon_gid, &exp->ex_fslocs);

  		if (exp->ex_uuid) {
  			int i;
  			seq_puts(m, ",uuid=");

  			for (i = 0; i < EX_UUID_LEN; i++) {

  				if ((i&3) == 0 && i)
  					seq_putc(m, ':');
  				seq_printf(m, "%02x", exp->ex_uuid[i]);
  			}
  		}

  		show_secinfo(m, exp);

  	}

  	seq_puts(m, ")
  ");
  	return 0;
  }

  static int svc_export_match(struct cache_head *a, struct cache_head *b)

  {

  	struct svc_export *orig = container_of(a, struct svc_export, h);
  	struct svc_export *new = container_of(b, struct svc_export, h);
  	return orig->ex_client == new->ex_client &&

  		path_equal(&orig->ex_path, &new->ex_path);

  }

  
  static void svc_export_init(struct cache_head *cnew, struct cache_head *citem)

  {

  	struct svc_export *new = container_of(cnew, struct svc_export, h);
  	struct svc_export *item = container_of(citem, struct svc_export, h);

  	kref_get(&item->ex_client->ref);

  	new->ex_client = item->ex_client;

  	new->ex_path = item->ex_path;
  	path_get(&item->ex_path);

  	new->ex_fslocs.locations = NULL;
  	new->ex_fslocs.locations_count = 0;
  	new->ex_fslocs.migrated = 0;

  	new->ex_layout_types = 0;

  	new->ex_uuid = NULL;

  	new->cd = item->cd;

  }

  static void export_update(struct cache_head *cnew, struct cache_head *citem)

  {

  	struct svc_export *new = container_of(cnew, struct svc_export, h);
  	struct svc_export *item = container_of(citem, struct svc_export, h);

  	int i;

  	new->ex_flags = item->ex_flags;
  	new->ex_anon_uid = item->ex_anon_uid;
  	new->ex_anon_gid = item->ex_anon_gid;
  	new->ex_fsid = item->ex_fsid;

  	new->ex_devid_map = item->ex_devid_map;
  	item->ex_devid_map = NULL;

  	new->ex_uuid = item->ex_uuid;
  	item->ex_uuid = NULL;

  	new->ex_fslocs.locations = item->ex_fslocs.locations;
  	item->ex_fslocs.locations = NULL;
  	new->ex_fslocs.locations_count = item->ex_fslocs.locations_count;
  	item->ex_fslocs.locations_count = 0;
  	new->ex_fslocs.migrated = item->ex_fslocs.migrated;
  	item->ex_fslocs.migrated = 0;

  	new->ex_layout_types = item->ex_layout_types;

  	new->ex_nflavors = item->ex_nflavors;
  	for (i = 0; i < MAX_SECINFO_LIST; i++) {
  		new->ex_flavors[i] = item->ex_flavors[i];
  	}

  }

  static struct cache_head *svc_export_alloc(void)
  {
  	struct svc_export *i = kmalloc(sizeof(*i), GFP_KERNEL);
  	if (i)
  		return &i->h;
  	else
  		return NULL;
  }

  static struct cache_detail svc_export_cache_template = {

  	.owner		= THIS_MODULE,
  	.hash_size	= EXPORT_HASHMAX,

  	.name		= "nfsd.export",
  	.cache_put	= svc_export_put,

  	.cache_request	= svc_export_request,

  	.cache_parse	= svc_export_parse,
  	.cache_show	= svc_export_show,
  	.match		= svc_export_match,
  	.init		= svc_export_init,
  	.update		= export_update,
  	.alloc		= svc_export_alloc,
  };

  static int
  svc_export_hash(struct svc_export *exp)

  {

  	int hash;

  	hash = hash_ptr(exp->ex_client, EXPORT_HASHBITS);

  	hash ^= hash_ptr(exp->ex_path.dentry, EXPORT_HASHBITS);
  	hash ^= hash_ptr(exp->ex_path.mnt, EXPORT_HASHBITS);

  	return hash;
  }
  
  static struct svc_export *
  svc_export_lookup(struct svc_export *exp)
  {
  	struct cache_head *ch;
  	int hash = svc_export_hash(exp);

  	ch = sunrpc_cache_lookup(exp->cd, &exp->h, hash);

  	if (ch)
  		return container_of(ch, struct svc_export, h);
  	else
  		return NULL;
  }

  static struct svc_export *

  svc_export_update(struct svc_export *new, struct svc_export *old)
  {
  	struct cache_head *ch;

  	int hash = svc_export_hash(old);

  	ch = sunrpc_cache_update(old->cd, &new->h, &old->h, hash);

  	if (ch)
  		return container_of(ch, struct svc_export, h);
  	else
  		return NULL;
  }

  static struct svc_expkey *

  exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type,

  	     u32 *fsidv, struct cache_req *reqp)

  {
  	struct svc_expkey key, *ek;
  	int err;
  	
  	if (!clp)

  		return ERR_PTR(-ENOENT);

  
  	key.ek_client = clp;
  	key.ek_fsidtype = fsid_type;
  	memcpy(key.ek_fsid, fsidv, key_len(fsid_type));

  	ek = svc_expkey_lookup(cd, &key);

  	if (ek == NULL)
  		return ERR_PTR(-ENOMEM);

  	err = cache_check(cd, &ek->h, reqp);

  	if (err)
  		return ERR_PTR(err);

  	return ek;
  }

  static struct svc_export *
  exp_get_by_name(struct cache_detail *cd, struct auth_domain *clp,
  		const struct path *path, struct cache_req *reqp)

  {
  	struct svc_export *exp, key;

  	int err;

  	if (!clp)

  		return ERR_PTR(-ENOENT);

  
  	key.ex_client = clp;

  	key.ex_path = *path;

  	key.cd = cd;

  	exp = svc_export_lookup(&key);

  	if (exp == NULL)
  		return ERR_PTR(-ENOMEM);

  	err = cache_check(cd, &exp->h, reqp);

  	if (err)
  		return ERR_PTR(err);

  	return exp;
  }
  
  /*
   * Find the export entry for a given dentry.
   */

  static struct svc_export *
  exp_parent(struct cache_detail *cd, struct auth_domain *clp, struct path *path)

  {

  	struct dentry *saved = dget(path->dentry);

  	struct svc_export *exp = exp_get_by_name(cd, clp, path, NULL);

  
  	while (PTR_ERR(exp) == -ENOENT && !IS_ROOT(path->dentry)) {
  		struct dentry *parent = dget_parent(path->dentry);
  		dput(path->dentry);
  		path->dentry = parent;

  		exp = exp_get_by_name(cd, clp, path, NULL);

  	}

  	dput(path->dentry);
  	path->dentry = saved;

  	return exp;
  }

  
  /*
   * 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 net *net, struct auth_domain *clp, char *name,

  	   struct knfsd_fh *f, int maxsize)

  {
  	struct svc_export	*exp;

  	struct path		path;

  	struct inode		*inode;
  	struct svc_fh		fh;
  	int			err;

  	struct nfsd_net		*nn = net_generic(net, nfsd_net_id);
  	struct cache_detail	*cd = nn->svc_export_cache;

  
  	err = -EPERM;
  	/* NB: we probably ought to check that it's NUL-terminated */

  	if (kern_path(name, 0, &path)) {
  		printk("nfsd: exp_rootfh path not found %s", name);

  		return err;
  	}

  	inode = d_inode(path.dentry);

  
  	dprintk("nfsd: exp_rootfh(%s [%p] %s:%s/%ld)
  ",

  		 name, path.dentry, clp->name,

  		 inode->i_sb->s_id, inode->i_ino);

  	exp = exp_parent(cd, clp, &path);

  	if (IS_ERR(exp)) {
  		err = PTR_ERR(exp);
  		goto out;
  	}

  
  	/*
  	 * fh must be initialized before calling fh_compose
  	 */
  	fh_init(&fh, maxsize);

  	if (fh_compose(&fh, exp, path.dentry, NULL))

  		err = -EINVAL;
  	else
  		err = 0;
  	memcpy(f, &fh.fh_handle, sizeof(struct knfsd_fh));
  	fh_put(&fh);
  	exp_put(exp);
  out:

  	path_put(&path);

  	return err;
  }

  static struct svc_export *exp_find(struct cache_detail *cd,
  				   struct auth_domain *clp, int fsid_type,

  				   u32 *fsidv, struct cache_req *reqp)

  {
  	struct svc_export *exp;

  	struct nfsd_net *nn = net_generic(cd->net, nfsd_net_id);
  	struct svc_expkey *ek = exp_find_key(nn->svc_expkey_cache, clp, fsid_type, fsidv, reqp);

  	if (IS_ERR(ek))

  		return ERR_CAST(ek);

  	exp = exp_get_by_name(cd, clp, &ek->ek_path, reqp);

  	cache_put(&ek->h, nn->svc_expkey_cache);

  	if (IS_ERR(exp))

  		return ERR_CAST(exp);

  	return exp;
  }

  __be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp)
  {
  	struct exp_flavor_info *f;
  	struct exp_flavor_info *end = exp->ex_flavors + exp->ex_nflavors;
  
  	/* legacy gss-only clients are always OK: */
  	if (exp->ex_client == rqstp->rq_gssclient)
  		return 0;
  	/* ip-address based client; check sec= export option: */
  	for (f = exp->ex_flavors; f < end; f++) {

  		if (f->pseudoflavor == rqstp->rq_cred.cr_flavor)

  			return 0;
  	}
  	/* defaults in absence of sec= options: */
  	if (exp->ex_nflavors == 0) {

  		if (rqstp->rq_cred.cr_flavor == RPC_AUTH_NULL ||
  		    rqstp->rq_cred.cr_flavor == RPC_AUTH_UNIX)

  			return 0;
  	}

  
  	/* If the compound op contains a spo_must_allowed op,
  	 * it will be sent with integrity/protection which
  	 * will have to be expressly allowed on mounts that
  	 * don't support it
  	 */
  
  	if (nfsd4_spo_must_allow(rqstp))
  		return 0;

  	return nfserr_wrongsec;
  }

  /*

   * Uses rq_client and rq_gssclient to find an export; uses rq_client (an
   * auth_unix client) if it's available and has secinfo information;
   * otherwise, will try to use rq_gssclient.
   *

   * Called from functions that handle requests; functions that do work on
   * behalf of mountd are passed a single client name to use, and should
   * use exp_get_by_name() or exp_find().
   */
  struct svc_export *

  rqst_exp_get_by_name(struct svc_rqst *rqstp, struct path *path)

  {

  	struct svc_export *gssexp, *exp = ERR_PTR(-ENOENT);

  	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

  	struct cache_detail *cd = nn->svc_export_cache;

  
  	if (rqstp->rq_client == NULL)
  		goto gss;

  	/* First try the auth_unix client: */

  	exp = exp_get_by_name(cd, rqstp->rq_client, path, &rqstp->rq_chandle);

  	if (PTR_ERR(exp) == -ENOENT)
  		goto gss;
  	if (IS_ERR(exp))
  		return exp;
  	/* If it has secinfo, assume there are no gss/... clients */
  	if (exp->ex_nflavors > 0)
  		return exp;
  gss:
  	/* Otherwise, try falling back on gss client */
  	if (rqstp->rq_gssclient == NULL)
  		return exp;

  	gssexp = exp_get_by_name(cd, rqstp->rq_gssclient, path, &rqstp->rq_chandle);

  	if (PTR_ERR(gssexp) == -ENOENT)
  		return exp;

  	if (!IS_ERR(exp))

  		exp_put(exp);
  	return gssexp;

  }
  
  struct svc_export *
  rqst_exp_find(struct svc_rqst *rqstp, int fsid_type, u32 *fsidv)
  {

  	struct svc_export *gssexp, *exp = ERR_PTR(-ENOENT);

  	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

  	struct cache_detail *cd = nn->svc_export_cache;

  
  	if (rqstp->rq_client == NULL)
  		goto gss;

  	/* First try the auth_unix client: */

  	exp = exp_find(cd, rqstp->rq_client, fsid_type,
  		       fsidv, &rqstp->rq_chandle);

  	if (PTR_ERR(exp) == -ENOENT)
  		goto gss;
  	if (IS_ERR(exp))
  		return exp;
  	/* If it has secinfo, assume there are no gss/... clients */
  	if (exp->ex_nflavors > 0)
  		return exp;
  gss:
  	/* Otherwise, try falling back on gss client */
  	if (rqstp->rq_gssclient == NULL)
  		return exp;

  	gssexp = exp_find(cd, rqstp->rq_gssclient, fsid_type, fsidv,

  						&rqstp->rq_chandle);
  	if (PTR_ERR(gssexp) == -ENOENT)
  		return exp;

  	if (!IS_ERR(exp))

  		exp_put(exp);
  	return gssexp;

  }
  
  struct svc_export *

  rqst_exp_parent(struct svc_rqst *rqstp, struct path *path)

  {

  	struct dentry *saved = dget(path->dentry);
  	struct svc_export *exp = rqst_exp_get_by_name(rqstp, path);

  	while (PTR_ERR(exp) == -ENOENT && !IS_ROOT(path->dentry)) {
  		struct dentry *parent = dget_parent(path->dentry);
  		dput(path->dentry);
  		path->dentry = parent;
  		exp = rqst_exp_get_by_name(rqstp, path);

  	}

  	dput(path->dentry);
  	path->dentry = saved;

  	return exp;

  }

  struct svc_export *rqst_find_fsidzero_export(struct svc_rqst *rqstp)

  {

  	u32 fsidv[2];
  
  	mk_fsid(FSID_NUM, fsidv, 0, 0, 0, NULL);

  	return rqst_exp_find(rqstp, FSID_NUM, fsidv);

  }

  /*
   * Called when we need the filehandle for the root of the pseudofs,
   * for a given NFSv4 client.   The root is defined to be the
   * export point with fsid==0
   */

  __be32

  exp_pseudoroot(struct svc_rqst *rqstp, struct svc_fh *fhp)

  {

  	struct svc_export *exp;

  	__be32 rv;

  	exp = rqst_find_fsidzero_export(rqstp);

  	if (IS_ERR(exp))
  		return nfserrno(PTR_ERR(exp));

  	rv = fh_compose(fhp, exp, exp->ex_path.dentry, NULL);

  	exp_put(exp);

  	return rv;
  }

  static 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_NOREADDIRPLUS, {"nordirplus", ""}},

  	{ NFSEXP_NOHIDE, {"nohide", ""}},
  	{ NFSEXP_CROSSMOUNT, {"crossmnt", ""}},
  	{ NFSEXP_NOSUBTREECHECK, {"no_subtree_check", ""}},
  	{ NFSEXP_NOAUTHNLM, {"insecure_locks", ""}},

  	{ NFSEXP_V4ROOT, {"v4root", ""}},

  	{ NFSEXP_PNFS, {"pnfs", ""}},

  	{ 0, {"", ""}}
  };

  static void show_expflags(struct seq_file *m, int flags, int mask)

  {

  	struct flags *flg;

  	int state, first = 0;

  
  	for (flg = expflags; flg->flag; flg++) {

  		if (flg->flag & ~mask)
  			continue;
  		state = (flg->flag & flags) ? 0 : 1;

  		if (*flg->name[state])
  			seq_printf(m, "%s%s", first++?",":"", flg->name[state]);
  	}

  }

  static void show_secinfo_flags(struct seq_file *m, int flags)
  {
  	seq_printf(m, ",");
  	show_expflags(m, flags, NFSEXP_SECINFO_FLAGS);
  }

  static bool secinfo_flags_equal(int f, int g)
  {
  	f &= NFSEXP_SECINFO_FLAGS;
  	g &= NFSEXP_SECINFO_FLAGS;
  	return f == g;
  }
  
  static int show_secinfo_run(struct seq_file *m, struct exp_flavor_info **fp, struct exp_flavor_info *end)
  {
  	int flags;
  
  	flags = (*fp)->flags;
  	seq_printf(m, ",sec=%d", (*fp)->pseudoflavor);
  	(*fp)++;
  	while (*fp != end && secinfo_flags_equal(flags, (*fp)->flags)) {
  		seq_printf(m, ":%d", (*fp)->pseudoflavor);
  		(*fp)++;
  	}
  	return flags;
  }

  static void show_secinfo(struct seq_file *m, struct svc_export *exp)
  {
  	struct exp_flavor_info *f;
  	struct exp_flavor_info *end = exp->ex_flavors + exp->ex_nflavors;

  	int flags;

  
  	if (exp->ex_nflavors == 0)
  		return;

  	f = exp->ex_flavors;
  	flags = show_secinfo_run(m, &f, end);
  	if (!secinfo_flags_equal(flags, exp->ex_flags))
  		show_secinfo_flags(m, flags);
  	while (f != end) {
  		flags = show_secinfo_run(m, &f, end);
  		show_secinfo_flags(m, flags);

  	}

  }

  static void exp_flags(struct seq_file *m, int flag, int fsid,

  		kuid_t anonu, kgid_t anong, struct nfsd4_fs_locations *fsloc)

  {
  	show_expflags(m, flag, NFSEXP_ALLFLAGS);

  	if (flag & NFSEXP_FSID)

  		seq_printf(m, ",fsid=%d", fsid);

  	if (!uid_eq(anonu, make_kuid(&init_user_ns, (uid_t)-2)) &&
  	    !uid_eq(anonu, make_kuid(&init_user_ns, 0x10000-2)))
  		seq_printf(m, ",anonuid=%u", from_kuid(&init_user_ns, anonu));
  	if (!gid_eq(anong, make_kgid(&init_user_ns, (gid_t)-2)) &&
  	    !gid_eq(anong, make_kgid(&init_user_ns, 0x10000-2)))
  		seq_printf(m, ",anongid=%u", from_kgid(&init_user_ns, anong));

  	if (fsloc && fsloc->locations_count > 0) {
  		char *loctype = (fsloc->migrated) ? "refer" : "replicas";
  		int i;

  		seq_printf(m, ",%s=", loctype);

  		seq_escape(m, fsloc->locations[0].path, ",;@ \t
  \\");
  		seq_putc(m, '@');
  		seq_escape(m, fsloc->locations[0].hosts, ",;@ \t
  \\");
  		for (i = 1; i < fsloc->locations_count; i++) {
  			seq_putc(m, ';');
  			seq_escape(m, fsloc->locations[i].path, ",;@ \t
  \\");
  			seq_putc(m, '@');
  			seq_escape(m, fsloc->locations[i].hosts, ",;@ \t
  \\");
  		}
  	}

  }
  
  static int e_show(struct seq_file *m, void *p)
  {
  	struct cache_head *cp = p;
  	struct svc_export *exp = container_of(cp, struct svc_export, h);

  	struct cache_detail *cd = m->private;

  	if (p == SEQ_START_TOKEN) {

  		seq_puts(m, "# Version 1.1
  ");
  		seq_puts(m, "# Path Client(Flags) # IPs
  ");
  		return 0;
  	}

  	exp_get(exp);

  	if (cache_check(cd, &exp->h, NULL))

  		return 0;

  	exp_put(exp);

  	return svc_export_show(m, cd, cp);

  }

  const struct seq_operations nfs_exports_op = {

  	.start	= cache_seq_start,
  	.next	= cache_seq_next,
  	.stop	= cache_seq_stop,

  	.show	= e_show,
  };

  /*
   * Initialize the exports module.
   */

  int

  nfsd_export_init(struct net *net)

  {

  	int rv;

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

  	dprintk("nfsd: initializing export module (net: %p).
  ", net);

  	nn->svc_export_cache = cache_create_net(&svc_export_cache_template, net);
  	if (IS_ERR(nn->svc_export_cache))
  		return PTR_ERR(nn->svc_export_cache);
  	rv = cache_register_net(nn->svc_export_cache, net);

  	if (rv)

  		goto destroy_export_cache;

  	nn->svc_expkey_cache = cache_create_net(&svc_expkey_cache_template, net);
  	if (IS_ERR(nn->svc_expkey_cache)) {
  		rv = PTR_ERR(nn->svc_expkey_cache);

  		goto unregister_export_cache;

  	}
  	rv = cache_register_net(nn->svc_expkey_cache, net);
  	if (rv)
  		goto destroy_expkey_cache;

  	return 0;

  destroy_expkey_cache:
  	cache_destroy_net(nn->svc_expkey_cache, net);

  unregister_export_cache:
  	cache_unregister_net(nn->svc_export_cache, net);
  destroy_export_cache:
  	cache_destroy_net(nn->svc_export_cache, net);
  	return rv;

  }
  
  /*
   * Flush exports table - called when last nfsd thread is killed
   */
  void

  nfsd_export_flush(struct net *net)

  {

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

  	cache_purge(nn->svc_expkey_cache);

  	cache_purge(nn->svc_export_cache);

  }
  
  /*
   * Shutdown the exports module.
   */
  void

  nfsd_export_shutdown(struct net *net)

  {

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

  	dprintk("nfsd: shutting down export module (net: %p).
  ", net);

  	cache_unregister_net(nn->svc_expkey_cache, net);

  	cache_unregister_net(nn->svc_export_cache, net);

  	cache_destroy_net(nn->svc_expkey_cache, net);

  	cache_destroy_net(nn->svc_export_cache, net);

  	svcauth_unix_purge(net);

  	dprintk("nfsd: export shutdown complete (net: %p).
  ", net);

  }