subr.c

Solaris操作系统下的过滤驱动程序, C源码程序.

/*
 * Copyright (c) 1997-2003 Erez Zadok
 * Copyright (c) 2001-2003 Stony Brook University
 * Copyright (c) 1997-2000 Columbia University
 *
 * For specific licensing information, see the COPYING file distributed with
 * this package, or get one from ftp://ftp.filesystems.org/pub/fist/COPYING.
 *
 * This Copyright notice must be kept intact and distributed with all
 * fistgen sources INCLUDING sources generated by fistgen.
 */
/*
 * 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.
 *
 *      @(#)wrapfs_subr.c       8.7 (Berkeley) 5/14/95
 *
 * $Id: subr.c,v 1.4 2002/12/27 20:18:53 ezk Exp $
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif /* HAVE_CONFIG_H */
#ifdef FISTGEN
# include "fist_wrapfs.h"
#endif /* FISTGEN */
#include <fist.h>
#include <wrapfs.h>

#if 0
#include "opt_debug.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/namei.h>
#include <vm/vm_zone.h>
#include <wrapfs.h>
#endif

#define LOG2_SIZEVNODE 7	/* log2(sizeof struct vnode) */
#define	NWRAPFSNODECACHE 16

/*
 * Cryptfs layer cache:
 * Each cache entry holds a reference to the lower vnode
 * along with a pointer to the alias vnode.  When an
 * entry is added the lower vnode is VREF'd.  When the
 * alias is removed the lower vnode is vrele'd.
 */

#define	WRAPFS_NHASH(vp) \
	(&wrapfs_node_hashtbl[(((uintptr_t)vp)>>LOG2_SIZEVNODE) & wrapfs_node_hash])
static
LIST_HEAD(wrapfs_node_hashhead, wrapfs_node) * wrapfs_node_hashtbl;
     static u_long wrapfs_node_hash;

     static int wrapfs_node_alloc __P((struct mount *mp, struct vnode * lowervp,
				       struct vnode ** vpp));
     static struct vnode *
       wrapfs_node_find __P((struct mount *mp, struct vnode * lowervp));

/*
 * Initialise cache headers
 */
int
wrapfs_init(vfsp)
     struct vfsconf *vfsp;
{

  fist_dprint(4, "FXN=%s FILE=%s LINE=%d\n",__FUNCTION__,__FILE__,__LINE__);

#ifdef DIAGNOSTIC
  printf("wrapfs_init\n");	/* printed during system boot */
#endif
  wrapfs_node_hashtbl = hashinit(NWRAPFSNODECACHE, M_CACHE, &wrapfs_node_hash);
  return (0);
}

/*
 * Return a VREF'ed alias for lower vnode if already exists, else 0.
 */
static struct vnode *
wrapfs_node_find(mp, lowervp)
     struct mount *mp;
     struct vnode *lowervp;
{
  struct proc *p = curproc;	/* XXX */
  struct wrapfs_node_hashhead *hd;
  struct wrapfs_node *a;
  struct vnode *vp;

  fist_dprint(4, "FXN=%s FILE=%s LINE=%d\n",__FUNCTION__,__FILE__,__LINE__);

  /*
   * Find hash base, and then search the (two-way) linked
   * list looking for a wrapfs_node structure which is referencing
   * the lower vnode.  If found, the increment the wrapfs_node
   * reference count (but NOT the lower vnode's VREF counter).
   */
  hd = WRAPFS_NHASH(lowervp);
loop:
  for (a = hd->lh_first; a != 0; a = a->wrapfs_hash.le_next) {
    if (a->wrapfs_lowervp == lowervp && WRAPFS_TO_VP(a)->v_mount == mp) {
      vp = WRAPFS_TO_VP(a);
      /*
       * We need vget for the VXLOCK
       * stuff, but we don't want to lock
       * the lower node.
       */
      if (vget(vp, 0, p)) {
	printf("wrapfs_node_find: vget failed.\n");
	goto loop;
      };
      return (vp);
    }
  }

  return NULLVP;
}

/*
 * Make a new wrapfs_node node.
 * Vp is the alias vnode, lofsvp is the lower vnode.
 * Maintain a reference to (lowervp).
 */
static int
wrapfs_node_alloc(mp, lowervp, vpp)
     struct mount *mp;
     struct vnode *lowervp;
     struct vnode **vpp;
{
  struct wrapfs_node_hashhead *hd;
  struct wrapfs_node *xp;
  struct vnode *othervp, *vp;
  int error;

  fist_dprint(4, "FXN=%s FILE=%s LINE=%d\n",__FUNCTION__,__FILE__,__LINE__);

  /*
   * Do the MALLOC before the getnewvnode since doing so afterward
   * might cause a bogus v_data pointer to get dereferenced
   * elsewhere if MALLOC should block.
   */
  MALLOC(xp, struct wrapfs_node *, sizeof(struct wrapfs_node), M_TEMP, M_WAITOK);
  error = getnewvnode(VT_WRAPFS, mp, wrapfs_vnodeop_p, vpp);
  if (error) {
    FREE(xp, M_TEMP);
    return (error);
  }
  vp = *vpp;

  vp->v_type = lowervp->v_type;
  xp->wrapfs_vnode = vp;
  vp->v_data = xp;
  xp->wrapfs_lowervp = lowervp;
  /*
   * Before we insert our new node onto the hash chains,
   * check to see if someone else has beaten us to it.
   * (We could have slept in MALLOC.)
   */
  othervp = wrapfs_node_find(mp, lowervp);
  if (othervp) {
    FREE(xp, M_TEMP);
    vp->v_type = VBAD;		/* node is discarded */
    vp->v_usecount = 0;		/* XXX */
    *vpp = othervp;
    return 0;
  };
  VREF(lowervp);		/* Extra VREF will be vrele'd in
				 * wrapfs_node_create */
  hd = WRAPFS_NHASH(lowervp);
  LIST_INSERT_HEAD(hd, xp, wrapfs_hash);
  return 0;
}

/*
 * Try to find an existing wrapfs_node vnode refering
 * to it, otherwise make a new wrapfs_node vnode which
 * contains a reference to the lower vnode.
 */
int
wrapfs_node_create(mp, lowervp, newvpp)
     struct mount *mp;
     struct vnode *lowervp;
     struct vnode **newvpp;
{
  struct vnode *aliasvp;

  fist_dprint(4, "FXN=%s FILE=%s LINE=%d\n",__FUNCTION__,__FILE__,__LINE__);

  aliasvp = wrapfs_node_find(mp, lowervp);
  if (aliasvp) {
    /*
     * wrapfs_node_find has taken another reference
     * to the alias vnode.
     */
#ifdef DIAGNOSTIC
    vprint("wrapfs_node_create: exists", aliasvp);
#endif
    /* VREF(aliasvp); --- done in wrapfs_node_find */
  } else {
    int error;

    /*
     * Get new vnode.
     */
#ifdef DIAGNOSTIC
    printf("wrapfs_node_create: create new alias vnode\n");
#endif

    /*
     * Make new vnode reference the wrapfs_node.
     */
    error = wrapfs_node_alloc(mp, lowervp, &aliasvp);
    if (error)
      return error;

    /*
     * aliasvp is already VREF'd by getnewvnode()
     */
  }

  vrele(lowervp);

#ifdef DIAGNOSTIC
  if (lowervp->v_usecount < 1) {
    /* Should never happen... */
    vprint("wrapfs_node_create: alias ", aliasvp);
    vprint("wrapfs_node_create: lower ", lowervp);
    panic("wrapfs_node_create: lower has 0 usecount.");
  };
#endif

#ifdef DIAGNOSTIC
  vprint("wrapfs_node_create: alias", aliasvp);
  vprint("wrapfs_node_create: lower", lowervp);
#endif

  *newvpp = aliasvp;
  return (0);
}

#ifdef DIAGNOSTIC
#include "opt_ddb.h"

#ifdef DDB
#define	wrapfs_checkvp_barrier	1
#else
#define	wrapfs_checkvp_barrier	0
#endif

struct vnode *
wrapfs_checkvp(vp, fil, lno)
     struct vnode *vp;
     char *fil;
     int lno;
{
  struct wrapfs_node *a = VP_TO_WRAPFS(vp);
  fist_dprint(4, "FXN=%s FILE=%s LINE=%d\n",__FUNCTION__,__FILE__,__LINE__);

#ifdef notyet
  /*
   * Can't do this check because vop_reclaim runs
   * with a funny vop vector.
   */
  if (vp->v_op != wrapfs_vnodeop_p) {
    printf("wrapfs_checkvp: on non-wrapfs-node\n");
    while (wrapfs_checkvp_barrier)	/* WAIT */
      ;
    panic("wrapfs_checkvp");
  };
#endif
  if (a->wrapfs_lowervp == NULLVP) {
    /* Should never happen */
    int i;
    u_long *p;
    printf("vp = %p, ZERO ptr\n", vp);
    for (p = (u_long *) a, i = 0; i < 8; i++)
      printf(" %lx", p[i]);
    printf("\n");
    /* wait for debugger */
    while (wrapfs_checkvp_barrier)	/* WAIT */
      ;
    panic("wrapfs_checkvp");
  }
  if (a->wrapfs_lowervp->v_usecount < 1) {
    int i;
    u_long *p;
    printf("vp = %p, unref'ed lowervp\n", vp);
    for (p = (u_long *) a, i = 0; i < 8; i++)
      printf(" %lx", p[i]);
    printf("\n");
    /* wait for debugger */
    while (wrapfs_checkvp_barrier)	/* WAIT */
      ;
    panic("wrapfs with unref'ed lowervp");
  };
#ifdef notyet