text: /*	$NetBSD: null_vfsops.c,v 1.36 2001/11/10 13:33:42 lukem Exp $	*/
  
  /*
   * Copyright (c) 1999 National Aeronautics & Space Administration
   * All rights reserved.
   *
   * This software was written by William Studenmund of the
   * Numerical Aerospace Simulation Facility, NASA Ames Research Center.
   *
   * 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 National Aeronautics & Space Administration
   *    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 BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION
   * ``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 ADMINISTRATION OR CONTRIB-
   * UTORS 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.
   */
  /*
   * Copyright (c) 1992, 1993, 1995
   *	The Regents of the University of California.  All rights reserved.
   *
   * This code is derived from software donated to Berkeley by
   * Jan-Simon Pendry.
   *
   * 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. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This product includes software developed by the University of
   *	California, Berkeley and its contributors.
   * 4. 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 BY THE REGENTS AND CONTRIBUTORS ``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.
   *
   *	from: Id: lofs_vfsops.c,v 1.9 1992/05/30 10:26:24 jsp Exp
   *	from: @(#)lofs_vfsops.c	1.2 (Berkeley) 6/18/92
   *	@(#)null_vfsops.c	8.7 (Berkeley) 5/14/95
   */
  
  /*
   * Null Layer
   * (See null_vnops.c for a description of what this does.)
   */
  
  #include <sys/cdefs.h>
  __KERNEL_RCSID(0, "$NetBSD: null_vfsops.c,v 1.36 2001/11/10 13:33:42 lukem Exp $");
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/time.h>
  #include <sys/proc.h>
  #include <sys/vnode.h>
  #include <sys/mount.h>
  #include <sys/namei.h>
  #include <sys/malloc.h>
  
  #include <miscfs/nullfs/null.h>
  #include <miscfs/genfs/layer_extern.h>
  
  int	nullfs_mount __P((struct mount *, const char *, void *,
  	    struct nameidata *, struct proc *));
  int	nullfs_unmount __P((struct mount *, int, struct proc *));
  
  /*
   * Mount null layer
   */
  int
  nullfs_mount(mp, path, data, ndp, p)
  	struct mount *mp;
  	const char *path;
  	void *data;
  	struct nameidata *ndp;
  	struct proc *p;
  {
  	struct null_args args;
  	struct vnode *lowerrootvp, *vp;
  	struct null_mount *nmp;
  	struct layer_mount *lmp;
  	size_t size;
  	int error = 0;
  
  #ifdef NULLFS_DIAGNOSTIC
  	printf("nullfs_mount(mp = %p)\n", mp);
  #endif
  
  	/*
  	 * Get argument
  	 */
  	error = copyin(data, (caddr_t)&args, sizeof(struct null_args));
  	if (error)
  		return (error);
  
  	/*
  	 * Update only does export updating.
  	 */
  	if (mp->mnt_flag & MNT_UPDATE) {
  		lmp = MOUNTTOLAYERMOUNT(mp);
  		if (args.nulla_target == NULL)
  			return (vfs_export(mp, &lmp->layerm_export,
  			    &args.la.export));
  		else
  			return (EOPNOTSUPP);
  	}
  
  	/*
  	 * Find lower node
  	 */
  	NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF,
  		UIO_USERSPACE, args.la.target, p);
  	if ((error = namei(ndp)) != 0)
  		return (error);
  
  	/*
  	 * Sanity check on lower vnode
  	 */
  	lowerrootvp = ndp->ni_vp;
  
  	/*
  	 * First cut at fixing up upper mount point
  	 */
  	nmp = (struct null_mount *) malloc(sizeof(struct null_mount),
  	    M_UFSMNT, M_WAITOK);		/* XXX */
  	memset((caddr_t)nmp, 0, sizeof(struct null_mount));
  
  	mp->mnt_data = (qaddr_t) nmp;
  	nmp->nullm_vfs = lowerrootvp->v_mount;
  	if (nmp->nullm_vfs->mnt_flag & MNT_LOCAL)
  		mp->mnt_flag |= MNT_LOCAL;
  
  	/*
  	 * Make sure that the mount point is sufficiently initialized
  	 * that the node create call will work.
  	 */
  	vfs_getnewfsid(mp);
  
  	nmp->nullm_size = sizeof(struct null_node);
  	nmp->nullm_tag = VT_NULL;
  	nmp->nullm_bypass = layer_bypass;
  	nmp->nullm_alloc = layer_node_alloc;	/* the default alloc is fine */
  	nmp->nullm_vnodeop_p = null_vnodeop_p;
  	simple_lock_init(&nmp->nullm_hashlock);
  	nmp->nullm_node_hashtbl = hashinit(desiredvnodes, HASH_LIST, M_CACHE,
  	    M_WAITOK, &nmp->nullm_node_hash);
  
  	/*
  	 * Fix up null node for root vnode
  	 */
  	error = layer_node_create(mp, lowerrootvp, &vp);
  	/*
  	 * Make sure the fixup worked
  	 */
  	if (error) {
  		vput(lowerrootvp);
  		hashdone(nmp->nullm_node_hashtbl, M_CACHE);
  		free(nmp, M_UFSMNT);	/* XXX */
  		return (error);
  	}
  	/*
  	 * Unlock the node
  	 */
  	VOP_UNLOCK(vp, 0);
  
  	/*
  	 * Keep a held reference to the root vnode.
  	 * It is vrele'd in nullfs_unmount.
  	 */
  	vp->v_flag |= VROOT;
  	nmp->nullm_rootvp = vp;
  
  	(void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
  	memset(mp->mnt_stat.f_mntonname + size, 0, MNAMELEN - size);
  	(void) copyinstr(args.la.target, mp->mnt_stat.f_mntfromname,
  	    MNAMELEN - 1, &size);
  	memset(mp->mnt_stat.f_mntfromname + size, 0, MNAMELEN - size);
  #ifdef NULLFS_DIAGNOSTIC
  	printf("nullfs_mount: lower %s, alias at %s\n",
  	    mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
  #endif
  	return (0);
  }
  
  /*
   * Free reference to null layer
   */
  int
  nullfs_unmount(mp, mntflags, p)
  	struct mount *mp;
  	int mntflags;
  	struct proc *p;
  {
  	struct null_mount *nmp = MOUNTTONULLMOUNT(mp);
  	struct vnode *null_rootvp = nmp->nullm_rootvp;
  	int error;
  	int flags = 0;
  
  #ifdef NULLFS_DIAGNOSTIC
  	printf("nullfs_unmount(mp = %p)\n", mp);
  #endif
  
  	if (mntflags & MNT_FORCE)
  		flags |= FORCECLOSE;
  
  	/*
  	 * Clear out buffer cache.  I don't think we
  	 * ever get anything cached at this level at the
  	 * moment, but who knows...
  	 */
  #if 0
  	mntflushbuf(mp, 0);
  	if (mntinvalbuf(mp, 1))
  		return (EBUSY);
  #endif
  	if (null_rootvp->v_usecount > 1)
  		return (EBUSY);
  	if ((error = vflush(mp, null_rootvp, flags)) != 0)
  		return (error);
  
  #ifdef NULLFS_DIAGNOSTIC
  	vprint("alias root of lower", null_rootvp);
  #endif
  	/*
  	 * Release reference on underlying root vnode
  	 */
  	vrele(null_rootvp);
  
  	/*
  	 * And blow it away for future re-use
  	 */
  	vgone(null_rootvp);
  
  	/*
  	 * Finally, throw away the null_mount structure
  	 */
  	hashdone(nmp->nullm_node_hashtbl, M_CACHE);
  	free(mp->mnt_data, M_UFSMNT);	/* XXX */
  	mp->mnt_data = NULL;
  	return (0);
  }
  
  extern const struct vnodeopv_desc null_vnodeop_opv_desc;
  
  const struct vnodeopv_desc * const nullfs_vnodeopv_descs[] = {
  	&null_vnodeop_opv_desc,
  	NULL,
  };
  
  struct vfsops nullfs_vfsops = {
  	MOUNT_NULL,
  	nullfs_mount,
  	layerfs_start,
  	nullfs_unmount,
  	layerfs_root,
  	layerfs_quotactl,
  	layerfs_statfs,
  	layerfs_sync,
  	layerfs_vget,
  	layerfs_fhtovp,
  	layerfs_vptofh,
  	layerfs_init,
  	NULL,
  	layerfs_done,
  	layerfs_sysctl,
  	NULL,				/* vfs_mountroot */
  	layerfs_checkexp,
  	nullfs_vnodeopv_descs,
  };
  