usr/src/sys/miscfs/specfs/specdev.h

/*
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)specdev.h   7.2 (Berkeley) %G%
 */

/*
 * This structure defines the information maintained about
 * special devices. It is allocated in checkalias and freed
 * in vgone.
 */
struct specinfo {
        struct  vnode **si_hashchain;
        struct  vnode *si_specnext;
        long    si_flags;
        dev_t   si_rdev;
};
/*
 * Exported shorthand
 */
#define v_rdev v_specinfo->si_rdev
#define v_hashchain v_specinfo->si_hashchain
#define v_specnext v_specinfo->si_specnext
#define v_specflags v_specinfo->si_flags

/*
 * Flags for specinfo
 */
#define SI_MOUNTEDON    0x0001  /* block special device is mounted on */

/*
 * Special device management
 */
#define SPECHSZ 64
#if     ((SPECHSZ&(SPECHSZ-1)) == 0)
#define SPECHASH(rdev)  (((rdev>>5)+(rdev))&(SPECHSZ-1))
#else
#define SPECHASH(rdev)  (((unsigned)((rdev>>5)+(rdev)))%SPECHSZ)
#endif

struct vnode *speclisth[SPECHSZ];