text: /*
   * Copyright (c) 1992, 1993
   *	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.
   *
   *	@(#)null_vfsops.c	8.2 (Berkeley) 1/21/94
   *
   * @(#)lofs_vfsops.c	1.2 (Berkeley) 6/18/92
   * $Id: null_vfsops.c,v 1.9 1995/12/11 09:24:35 phk Exp $
   */
  
  /*
   * Null Layer
   * (See null_vnops.c for a description of what this does.)
   */
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/kernel.h>
  #include <sys/time.h>
  #include <sys/types.h>
  #include <sys/vnode.h>
  #include <sys/mount.h>
  #include <sys/namei.h>
  #include <sys/malloc.h>
  #include <miscfs/nullfs/null.h>
  
  extern int	nullfs_init __P((void));
  
  static int	nullfs_fhtovp __P((struct mount *mp, struct fid *fidp,
  				   struct mbuf *nam, struct vnode **vpp,
  				   int *exflagsp, struct ucred **credanonp));
  static int	nullfs_mount __P((struct mount *mp, char *path, caddr_t data,
  				  struct nameidata *ndp, struct proc *p));
  static int	nullfs_quotactl __P((struct mount *mp, int cmd, uid_t uid,
  				     caddr_t arg, struct proc *p));
  static int	nullfs_root __P((struct mount *mp, struct vnode **vpp));
  static int	nullfs_start __P((struct mount *mp, int flags, struct proc *p));
  static int	nullfs_statfs __P((struct mount *mp, struct statfs *sbp,
  				   struct proc *p));
  static int	nullfs_sync __P((struct mount *mp, int waitfor,
  				 struct ucred *cred, struct proc *p));
  static int	nullfs_unmount __P((struct mount *mp, int mntflags,
  				    struct proc *p));
  static int	nullfs_vget __P((struct mount *mp, ino_t ino,
  				 struct vnode **vpp));
  static int	nullfs_vptofh __P((struct vnode *vp, struct fid *fhp));
  
  /*
   * Mount null layer
   */
  static int
  nullfs_mount(mp, path, data, ndp, p)
  	struct mount *mp;
  	char *path;
  	caddr_t data;
  	struct nameidata *ndp;
  	struct proc *p;
  {
  	int error = 0;
  	struct null_args args;
  	struct vnode *lowerrootvp, *vp;
  	struct vnode *nullm_rootvp;
  	struct null_mount *xmp;
  	u_int size;
  
  #ifdef NULLFS_DIAGNOSTIC
  	printf("nullfs_mount(mp = %x)\n", mp);
  #endif
  
  	/*
  	 * Update is a no-op
  	 */
  	if (mp->mnt_flag & MNT_UPDATE) {
  		return (EOPNOTSUPP);
  		/* return VFS_MOUNT(MOUNTTONULLMOUNT(mp)->nullm_vfs, path, data, ndp, p);*/
  	}
  
  	/*
  	 * Get argument
  	 */
  	error = copyin(data, (caddr_t)&args, sizeof(struct null_args));
  	if (error)
  		return (error);
  
  	/*
  	 * Find lower node
  	 */
  	NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT|LOCKLEAF,
  		UIO_USERSPACE, args.target, p);
  	error = namei(ndp);
  	if (error)
  		return (error);
  
  	/*
  	 * Sanity check on lower vnode
  	 */
  	lowerrootvp = ndp->ni_vp;
  
  	vrele(ndp->ni_dvp);
  	ndp->ni_dvp = NULL;
  
  	xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
  				M_UFSMNT, M_WAITOK);	/* XXX */
  
  	/*
  	 * Save reference to underlying FS
  	 */
  	xmp->nullm_vfs = lowerrootvp->v_mount;
  
  	/*
  	 * Save reference.  Each mount also holds
  	 * a reference on the root vnode.
  	 */
  	error = null_node_create(mp, lowerrootvp, &vp);
  	/*
  	 * Unlock the node (either the lower or the alias)
  	 */
  	VOP_UNLOCK(vp);
  	/*
  	 * Make sure the node alias worked
  	 */
  	if (error) {
  		vrele(lowerrootvp);
  		free(xmp, M_UFSMNT);	/* XXX */
  		return (error);
  	}
  
  	/*
  	 * Keep a held reference to the root vnode.
  	 * It is vrele'd in nullfs_unmount.
  	 */
  	nullm_rootvp = vp;
  	nullm_rootvp->v_flag |= VROOT;
  	xmp->nullm_rootvp = nullm_rootvp;
  	if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL)
  		mp->mnt_flag |= MNT_LOCAL;
  	mp->mnt_data = (qaddr_t) xmp;
  	getnewfsid(mp, MOUNT_LOFS);
  
  	(void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
  	bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size);
  	(void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1,
  	    &size);
  	bzero(mp->mnt_stat.f_mntfromname + size, 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);
  }
  
  /*
   * VFS start.  Nothing needed here - the start routine
   * on the underlying filesystem will have been called
   * when that filesystem was mounted.
   */
  static int
  nullfs_start(mp, flags, p)
  	struct mount *mp;
  	int flags;
  	struct proc *p;
  {
  	return (0);
  	/* return VFS_START(MOUNTTONULLMOUNT(mp)->nullm_vfs, flags, p); */
  }
  
  /*
   * Free reference to null layer
   */
  static int
  nullfs_unmount(mp, mntflags, p)
  	struct mount *mp;
  	int mntflags;
  	struct proc *p;
  {
  	struct vnode *nullm_rootvp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
  	int error;
  	int flags = 0;
  
  #ifdef NULLFS_DIAGNOSTIC
  	printf("nullfs_unmount(mp = %x)\n", mp);
  #endif
  
  	if (mntflags & MNT_FORCE) {
  		/* lofs can never be rootfs so don't check for it */
  		if (!doforce)
  			return (EINVAL);
  		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 (nullm_rootvp->v_usecount > 1)
  		return (EBUSY);
  	error = vflush(mp, nullm_rootvp, flags);
  	if (error)
  		return (error);
  
  #ifdef NULLFS_DIAGNOSTIC
  	vprint("alias root of lower", nullm_rootvp);
  #endif
  	/*
  	 * Release reference on underlying root vnode
  	 */
  	vrele(nullm_rootvp);
  	/*
  	 * And blow it away for future re-use
  	 */
  	vgone(nullm_rootvp);
  	/*
  	 * Finally, throw away the null_mount structure
  	 */
  	free(mp->mnt_data, M_UFSMNT);	/* XXX */
  	mp->mnt_data = 0;
  	return 0;
  }
  
  static int
  nullfs_root(mp, vpp)
  	struct mount *mp;
  	struct vnode **vpp;
  {
  	struct vnode *vp;
  
  #ifdef NULLFS_DIAGNOSTIC
  	printf("nullfs_root(mp = %x, vp = %x->%x)\n", mp,
  			MOUNTTONULLMOUNT(mp)->nullm_rootvp,
  			NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)
  			);
  #endif
  
  	/*
  	 * Return locked reference to root.
  	 */
  	vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
  	VREF(vp);
  	VOP_LOCK(vp);
  	*vpp = vp;
  	return 0;
  }
  
  static int
  nullfs_quotactl(mp, cmd, uid, arg, p)
  	struct mount *mp;
  	int cmd;
  	uid_t uid;
  	caddr_t arg;
  	struct proc *p;
  {
  	return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, p);
  }
  
  static int
  nullfs_statfs(mp, sbp, p)
  	struct mount *mp;
  	struct statfs *sbp;
  	struct proc *p;
  {
  	int error;
  	struct statfs mstat;
  
  #ifdef NULLFS_DIAGNOSTIC
  	printf("nullfs_statfs(mp = %x, vp = %x->%x)\n", mp,
  			MOUNTTONULLMOUNT(mp)->nullm_rootvp,
  			NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)
  			);
  #endif
  
  	bzero(&mstat, sizeof(mstat));
  
  	error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, p);
  	if (error)
  		return (error);
  
  	/* now copy across the "interesting" information and fake the rest */
  	sbp->f_type = mstat.f_type;
  	sbp->f_flags = mstat.f_flags;
  	sbp->f_bsize = mstat.f_bsize;
  	sbp->f_iosize = mstat.f_iosize;
  	sbp->f_blocks = mstat.f_blocks;
  	sbp->f_bfree = mstat.f_bfree;
  	sbp->f_bavail = mstat.f_bavail;
  	sbp->f_files = mstat.f_files;
  	sbp->f_ffree = mstat.f_ffree;
  	if (sbp != &mp->mnt_stat) {
  		bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
  		bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
  		bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
  	}
  	return (0);
  }
  
  static int
  nullfs_sync(mp, waitfor, cred, p)
  	struct mount *mp;
  	int waitfor;
  	struct ucred *cred;
  	struct proc *p;
  {
  	/*
  	 * XXX - Assumes no data cached at null layer.
  	 */
  	return (0);
  }
  
  static int
  nullfs_vget(mp, ino, vpp)
  	struct mount *mp;
  	ino_t ino;
  	struct vnode **vpp;
  {
  
  	return VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, vpp);
  }
  
  static int
  nullfs_fhtovp(mp, fidp, nam, vpp, exflagsp, credanonp)
  	struct mount *mp;
  	struct fid *fidp;
  	struct mbuf *nam;
  	struct vnode **vpp;
  	int *exflagsp;
  	struct ucred**credanonp;
  {
  
  	return VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, nam, vpp, exflagsp,credanonp);
  }
  
  static int
  nullfs_vptofh(vp, fhp)
  	struct vnode *vp;
  	struct fid *fhp;
  {
  	return VFS_VPTOFH(NULLVPTOLOWERVP(vp), fhp);
  }
  
  static struct vfsops null_vfsops = {
  	nullfs_mount,
  	nullfs_start,
  	nullfs_unmount,
  	nullfs_root,
  	nullfs_quotactl,
  	nullfs_statfs,
  	nullfs_sync,
  	nullfs_vget,
  	nullfs_fhtovp,
  	nullfs_vptofh,
  	nullfs_init,
  };
  
  VFS_SET(null_vfsops, null, MOUNT_NULL, VFCF_LOOPBACK);
  