More minor IPI work.

[dragonfly/vkernel-mp.git] / sys / dev / disk / ccd / ccd.c

/*
 * Copyright (c) 2007 The DragonFly Project.  All rights reserved.
 * 
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 * 
 * 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 DragonFly Project 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 COPYRIGHT HOLDERS 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
 * COPYRIGHT HOLDERS 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.
 * 
 * $DragonFly: src/sys/dev/disk/ccd/ccd.c,v 1.48 2007/06/19 19:09:46 dillon Exp $
 */
/*
 * Copyright (c) 1995 Jason R. Thorpe.
 * All rights reserved.
 *
 * 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 for the NetBSD Project
 *      by Jason R. Thorpe.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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) 1988 University of Utah.
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * 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: Utah $Hdr: cd.c 1.6 90/11/28$
 */
/*
 * @(#)cd.c     8.2 (Berkeley) 11/16/93
 * $FreeBSD: src/sys/dev/ccd/ccd.c,v 1.73.2.1 2001/09/11 09:49:52 kris Exp $
 * $NetBSD: ccd.c,v 1.22 1995/12/08 19:13:26 thorpej Exp $
 * $DragonFly: src/sys/dev/disk/ccd/ccd.c,v 1.48 2007/06/19 19:09:46 dillon Exp $
 */

/*
 * "Concatenated" disk driver.
 *
 * Original dynamic configuration support by:
 *      Jason R. Thorpe <thorpej@nas.nasa.gov>
 *      Numerical Aerodynamic Simulation Facility
 *      Mail Stop 258-6
 *      NASA Ames Research Center
 *      Moffett Field, CA 94035
 */

#include "use_ccd.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/malloc.h>
#include <sys/nlookup.h>
#include <sys/conf.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/disk.h>
#include <sys/dtype.h>
#include <sys/diskslice.h>
#include <sys/devicestat.h>
#include <sys/fcntl.h>
#include <sys/vnode.h>
#include <sys/buf2.h>
#include <sys/ccdvar.h>

#include <vm/vm_zone.h>

#include <vfs/ufs/dinode.h>     /* XXX Used only for fs.h */
#include <vfs/ufs/fs.h>         /* XXX used only to get BBSIZE and SBSIZE */

#include <sys/thread2.h>

#if defined(CCDDEBUG) && !defined(DEBUG)
#define DEBUG
#endif

#ifdef DEBUG
#define CCDB_FOLLOW     0x01
#define CCDB_INIT       0x02
#define CCDB_IO         0x04
#define CCDB_LABEL      0x08
#define CCDB_VNODE      0x10
static int ccddebug = CCDB_FOLLOW | CCDB_INIT | CCDB_IO | CCDB_LABEL |
    CCDB_VNODE;
SYSCTL_INT(_debug, OID_AUTO, ccddebug, CTLFLAG_RW, &ccddebug, 0, "");
#undef DEBUG
#endif

#define ccdunit(x)      dkunit(x)
#define ccdpart(x)      dkpart(x)

/*
   This is how mirroring works (only writes are special):

   When initiating a write, ccdbuffer() returns two "struct ccdbuf *"s
   linked together by the cb_mirror field.  "cb_pflags &
   CCDPF_MIRROR_DONE" is set to 0 on both of them.

   When a component returns to ccdiodone(), it checks if "cb_pflags &
   CCDPF_MIRROR_DONE" is set or not.  If not, it sets the partner's
   flag and returns.  If it is, it means its partner has already
   returned, so it will go to the regular cleanup.

 */

struct ccdbuf {
        struct buf      cb_buf;         /* new I/O buf */
        struct vnode    *cb_vp;         /* related vnode */
        struct bio      *cb_obio;       /* ptr. to original I/O buf */
        struct ccdbuf   *cb_freenext;   /* free list link */
        int             cb_unit;        /* target unit */
        int             cb_comp;        /* target component */
        int             cb_pflags;      /* mirror/parity status flag */
        struct ccdbuf   *cb_mirror;     /* mirror counterpart */
};

/* bits in cb_pflags */
#define CCDPF_MIRROR_DONE 1     /* if set, mirror counterpart is done */

static d_open_t ccdopen;
static d_close_t ccdclose;
static d_strategy_t ccdstrategy;
static d_ioctl_t ccdioctl;
static d_dump_t ccddump;

#define NCCDFREEHIWAT   16

#define CDEV_MAJOR 74

static struct dev_ops ccd_ops = {
        { "ccd", CDEV_MAJOR, D_DISK },
        .d_open =       ccdopen,
        .d_close =      ccdclose,
        .d_read =       physread,
        .d_write =      physwrite,
        .d_ioctl =      ccdioctl,
        .d_strategy =   ccdstrategy,
        .d_dump =       ccddump
};

/* called during module initialization */
static  void ccdattach (void);
static  int ccd_modevent (module_t, int, void *);

/* called by biodone() at interrupt time */
static  void ccdiodone (struct bio *bio);

static  void ccdstart (struct ccd_softc *, struct bio *);
static  void ccdinterleave (struct ccd_softc *, int);
static  void ccdintr (struct ccd_softc *, struct bio *);
static  int ccdinit (struct ccddevice *, char **, struct ucred *);
static  int ccdlookup (char *, struct vnode **);
static  void ccdbuffer (struct ccdbuf **ret, struct ccd_softc *,
                struct bio *, off_t, caddr_t, long);
static  int ccdlock (struct ccd_softc *);
static  void ccdunlock (struct ccd_softc *);

#ifdef DEBUG
static  void printiinfo (struct ccdiinfo *);
#endif

/* Non-private for the benefit of libkvm. */
struct  ccd_softc *ccd_softc;
struct  ccddevice *ccddevs;
struct  ccdbuf *ccdfreebufs;
static  int numccdfreebufs;
static  int numccd = 0;

/*
 * getccdbuf() -        Allocate and zero a ccd buffer.
 *
 *      This routine is called at splbio().
 */

static __inline
struct ccdbuf *
getccdbuf(void)
{
        struct ccdbuf *cbp;

        /*
         * Allocate from freelist or malloc as necessary
         */
        if ((cbp = ccdfreebufs) != NULL) {
                ccdfreebufs = cbp->cb_freenext;
                --numccdfreebufs;
                reinitbufbio(&cbp->cb_buf);
        } else {
                cbp = kmalloc(sizeof(struct ccdbuf), M_DEVBUF, M_WAITOK|M_ZERO);
                initbufbio(&cbp->cb_buf);
        }

        /*
         * independant struct buf initialization
         */
        LIST_INIT(&cbp->cb_buf.b_dep);
        BUF_LOCKINIT(&cbp->cb_buf);
        BUF_LOCK(&cbp->cb_buf, LK_EXCLUSIVE);
        BUF_KERNPROC(&cbp->cb_buf);
        cbp->cb_buf.b_flags = B_PAGING | B_BNOCLIP;

        return(cbp);
}

/*
 * putccdbuf() -        Free a ccd buffer.
 *
 *      This routine is called at splbio().
 */

static __inline
void
putccdbuf(struct ccdbuf *cbp)
{
        BUF_UNLOCK(&cbp->cb_buf);
        BUF_LOCKFREE(&cbp->cb_buf);

        if (numccdfreebufs < NCCDFREEHIWAT) {
                cbp->cb_freenext = ccdfreebufs;
                ccdfreebufs = cbp;
                ++numccdfreebufs;
        } else {
                kfree((caddr_t)cbp, M_DEVBUF);
        }
}

/*
 * Called by main() during pseudo-device attachment.  All we need
 * to do is allocate enough space for devices to be configured later, and
 * add devsw entries.
 */
static void
ccdattach(void)
{
        struct disk_info info;
        struct ccd_softc *cs;
        int i;
        int num = NCCD;

        if (num > 1)
                kprintf("ccd0-%d: Concatenated disk drivers\n", num-1);
        else
                kprintf("ccd0: Concatenated disk driver\n");

        ccd_softc = kmalloc(num * sizeof(struct ccd_softc), M_DEVBUF, 
                            M_WAITOK | M_ZERO);
        ccddevs = kmalloc(num * sizeof(struct ccddevice), M_DEVBUF,
                            M_WAITOK | M_ZERO);
        numccd = num;

        /*
         * With normal disk devices the open simply fails if the media
         * is not present.  With CCD we have to be able to open the
         * raw disk to use the ioctl's to set it up, so create a dummy
         * disk info structure so dscheck() doesn't blow up.
         */
        bzero(&info, sizeof(info));
        info.d_media_blksize = DEV_BSIZE;

        for (i = 0; i < numccd; ++i) {
                cs = &ccd_softc[i];
                cs->sc_dev = disk_create(i, &cs->sc_disk, &ccd_ops);
                cs->sc_dev->si_drv1 = cs;
                cs->sc_dev->si_iosize_max = 256 * 512;  /* XXX */
                disk_setdiskinfo(&cs->sc_disk, &info);
        }
}

static int
ccd_modevent(module_t mod, int type, void *data)
{
        int error = 0;

        switch (type) {
        case MOD_LOAD:
                ccdattach();
                break;

        case MOD_UNLOAD:
                kprintf("ccd0: Unload not supported!\n");
                error = EOPNOTSUPP;
                break;

        default:        /* MOD_SHUTDOWN etc */
                break;
        }
        return (error);
}

DEV_MODULE(ccd, ccd_modevent, NULL);

static int
ccdinit(struct ccddevice *ccd, char **cpaths, struct ucred *cred)
{
        struct ccd_softc *cs = &ccd_softc[ccd->ccd_unit];
        struct ccdcinfo *ci = NULL;     /* XXX */
        int ix;
        struct vnode *vp;
        u_int64_t skip;
        u_int64_t size;
        u_int64_t minsize;
        int maxsecsize;
        struct partinfo dpart;
        struct ccdgeom *ccg = &cs->sc_geom;
        char tmppath[MAXPATHLEN];
        int error = 0;

#ifdef DEBUG
        if (ccddebug & (CCDB_FOLLOW|CCDB_INIT))
                kprintf("ccdinit: unit %d\n", ccd->ccd_unit);
#endif

        cs->sc_size = 0;
        cs->sc_ileave = ccd->ccd_interleave;
        cs->sc_nccdisks = ccd->ccd_ndev;

        /* Allocate space for the component info. */
        cs->sc_cinfo = kmalloc(cs->sc_nccdisks * sizeof(struct ccdcinfo),
                                M_DEVBUF, M_WAITOK);

        /*
         * Verify that each component piece exists and record
         * relevant information about it.
         */
        maxsecsize = 0;
        minsize = 0;
        for (ix = 0; ix < cs->sc_nccdisks; ix++) {
                vp = ccd->ccd_vpp[ix];
                ci = &cs->sc_cinfo[ix];
                ci->ci_vp = vp;

                /*
                 * Copy in the pathname of the component.
                 */
                bzero(tmppath, sizeof(tmppath));        /* sanity */
                if ((error = copyinstr(cpaths[ix], tmppath,
                    MAXPATHLEN, &ci->ci_pathlen)) != 0) {
#ifdef DEBUG
                        if (ccddebug & (CCDB_FOLLOW|CCDB_INIT))
                                kprintf("ccd%d: can't copy path, error = %d\n",
                                    ccd->ccd_unit, error);
#endif
                        goto fail;
                }
                ci->ci_path = kmalloc(ci->ci_pathlen, M_DEVBUF, M_WAITOK);
                bcopy(tmppath, ci->ci_path, ci->ci_pathlen);

                ci->ci_dev = vn_todev(vp);

                /*
                 * Get partition information for the component.
                 */
                error = VOP_IOCTL(vp, DIOCGPART, (caddr_t)&dpart, FREAD, cred);
                if (error) {
#ifdef DEBUG
                        if (ccddebug & (CCDB_FOLLOW|CCDB_INIT))
                                 kprintf("ccd%d: %s: ioctl failed, error = %d\n",
                                     ccd->ccd_unit, ci->ci_path, error);
#endif
                        goto fail;
                }
                if (dpart.fstype != FS_CCD && 
                    !kuuid_is_ccd(&dpart.fstype_uuid)) {
                        kprintf("ccd%d: %s: filesystem type must be 'ccd'\n",
                                ccd->ccd_unit, ci->ci_path);
                        error = EFTYPE;
                        goto fail;
                }
                if (maxsecsize < dpart.media_blksize)
                        maxsecsize = dpart.media_blksize;

                /*
                 * Skip a certain amount of storage at the beginning of
                 * the component to make sure we don't infringe on any
                 * reserved sectors.  This is handled entirely by
                 * dpart.reserved_blocks but we also impose a minimum
                 * of 16 sectors for backwards compatibility.
                 */
                skip = 16;
                if (skip < dpart.reserved_blocks)
                        skip = dpart.reserved_blocks;
                size = dpart.media_blocks - skip;

                /*
                 * Calculate the size, truncating to an interleave
                 * boundary if necessary.
                 */
                if (cs->sc_ileave > 1)
                        size -= size % cs->sc_ileave;

                if ((int64_t)size <= 0) {
#ifdef DEBUG
                        if (ccddebug & (CCDB_FOLLOW|CCDB_INIT))
                                kprintf("ccd%d: %s: size == 0\n",
                                    ccd->ccd_unit, ci->ci_path);
#endif
                        error = ENODEV;
                        goto fail;
                }

                /*
                 * Calculate the smallest uniform component, used
                 * elsewhere.
                 */
                if (minsize == 0 || minsize > size)
                        minsize = size;
                ci->ci_skip = skip;
                ci->ci_size = size;
                cs->sc_size += size;
        }

        /*
         * Don't allow the interleave to be smaller than
         * the biggest component sector.
         */
        if ((cs->sc_ileave > 0) &&
            (cs->sc_ileave % (maxsecsize / DEV_BSIZE))) {
#ifdef DEBUG
                if (ccddebug & (CCDB_FOLLOW|CCDB_INIT))
                        kprintf("ccd%d: interleave must be at least %d\n",
                            ccd->ccd_unit, (maxsecsize / DEV_BSIZE));
#endif
                error = EINVAL;
                goto fail;
        }

        /*
         * If uniform interleave is desired set all sizes to that of
         * the smallest component.  This will guarentee that a single
         * interleave table is generated.
         *
         * Lost space must be taken into account when calculating the
         * overall size.  Half the space is lost when CCDF_MIRROR is
         * specified.  One disk is lost when CCDF_PARITY is specified.
         */
        if (ccd->ccd_flags & CCDF_UNIFORM) {
                for (ci = cs->sc_cinfo;
                     ci < &cs->sc_cinfo[cs->sc_nccdisks]; ci++) {
                        ci->ci_size = minsize;
                }
                if (ccd->ccd_flags & CCDF_MIRROR) {
                        /*
                         * Check to see if an even number of components
                         * have been specified.  The interleave must also
                         * be non-zero in order for us to be able to 
                         * guarentee the topology.
                         */
                        if (cs->sc_nccdisks % 2) {
                                kprintf("ccd%d: mirroring requires an even number of disks\n", ccd->ccd_unit );
                                error = EINVAL;
                                goto fail;
                        }
                        if (cs->sc_ileave == 0) {
                                kprintf("ccd%d: an interleave must be specified when mirroring\n", ccd->ccd_unit);
                                error = EINVAL;
                                goto fail;
                        }
                        cs->sc_size = (cs->sc_nccdisks/2) * minsize;
                } else if (ccd->ccd_flags & CCDF_PARITY) {
                        cs->sc_size = (cs->sc_nccdisks-1) * minsize;
                } else {
                        if (cs->sc_ileave == 0) {
                                kprintf("ccd%d: an interleave must be specified when using parity\n", ccd->ccd_unit);
                                error = EINVAL;
                                goto fail;
                        }
                        cs->sc_size = cs->sc_nccdisks * minsize;
                }
        }

        /*
         * Construct the interleave table.
         */
        ccdinterleave(cs, ccd->ccd_unit);

        /*
         * Create pseudo-geometry based on 1MB cylinders.  It's
         * pretty close.
         */
        ccg->ccg_secsize = maxsecsize;
        ccg->ccg_ntracks = 1;
        ccg->ccg_nsectors = 1024 * 1024 / ccg->ccg_secsize;
        ccg->ccg_ncylinders = cs->sc_size / ccg->ccg_nsectors;

        /*
         * Add an devstat entry for this device.
         */
        devstat_add_entry(&cs->device_stats, "ccd", ccd->ccd_unit,
                          ccg->ccg_secsize, DEVSTAT_ALL_SUPPORTED,
                          DEVSTAT_TYPE_STORARRAY |DEVSTAT_TYPE_IF_OTHER,
                          DEVSTAT_PRIORITY_ARRAY);

        cs->sc_flags |= CCDF_INITED;
        cs->sc_cflags = ccd->ccd_flags; /* So we can find out later... */
        cs->sc_unit = ccd->ccd_unit;
        return (0);
fail:
        while (ci > cs->sc_cinfo) {
                ci--;
                kfree(ci->ci_path, M_DEVBUF);
        }
        kfree(cs->sc_cinfo, M_DEVBUF);
        cs->sc_cinfo = NULL;
        return (error);
}

static void
ccdinterleave(struct ccd_softc *cs, int unit)
{
        struct ccdcinfo *ci, *smallci;
        struct ccdiinfo *ii;
        u_int64_t bn;
        u_int64_t lbn;
        u_int64_t size;
        int icount;
        int ix;

#ifdef DEBUG
        if (ccddebug & CCDB_INIT)
                kprintf("ccdinterleave(%x): ileave %d\n", cs, cs->sc_ileave);
#endif

        /*
         * Allocate an interleave table.  The worst case occurs when each
         * of N disks is of a different size, resulting in N interleave
         * tables.
         *
         * Chances are this is too big, but we don't care.
         */
        icount = cs->sc_nccdisks + 1;
        cs->sc_itable = kmalloc(icount * sizeof(struct ccdiinfo),
                                M_DEVBUF, M_WAITOK|M_ZERO);

        /*
         * Trivial case: no interleave (actually interleave of disk size).
         * Each table entry represents a single component in its entirety.
         *
         * An interleave of 0 may not be used with a mirror or parity setup.
         */
        if (cs->sc_ileave == 0) {
                bn = 0;
                ii = cs->sc_itable;

                for (ix = 0; ix < cs->sc_nccdisks; ix++) {
                        /* Allocate space for ii_index. */
                        ii->ii_index = kmalloc(sizeof(int), M_DEVBUF, M_WAITOK);
                        ii->ii_ndisk = 1;
                        ii->ii_startblk = bn;
                        ii->ii_startoff = 0;
                        ii->ii_index[0] = ix;
                        bn += cs->sc_cinfo[ix].ci_size;
                        ii++;
                }
                ii->ii_ndisk = 0;
#ifdef DEBUG
                if (ccddebug & CCDB_INIT)
                        printiinfo(cs->sc_itable);
#endif
                return;
        }

        /*
         * The following isn't fast or pretty; it doesn't have to be.
         */
        size = 0;
        bn = lbn = 0;
        for (ii = cs->sc_itable; ii < &cs->sc_itable[icount]; ++ii) {
                /*
                 * Allocate space for ii_index.  We might allocate more then
                 * we use.
                 */
                ii->ii_index = kmalloc((sizeof(int) * cs->sc_nccdisks),
                                        M_DEVBUF, M_WAITOK);

                /*
                 * Locate the smallest of the remaining components
                 */
                smallci = NULL;
                ci = cs->sc_cinfo;
                while (ci < &cs->sc_cinfo[cs->sc_nccdisks]) {
                        if (ci->ci_size > size &&
                            (smallci == NULL ||
                             ci->ci_size < smallci->ci_size)) {
                                smallci = ci;
                        }
                        ++ci;
                }

                /*
                 * Nobody left, all done
                 */
                if (smallci == NULL) {
                        ii->ii_ndisk = 0;
                        break;
                }

                /*
                 * Record starting logical block using an sc_ileave blocksize.
                 */
                ii->ii_startblk = bn / cs->sc_ileave;

                /*
                 * Record starting component block using an sc_ileave 
                 * blocksize.  This value is relative to the beginning of
                 * a component disk.
                 */
                ii->ii_startoff = lbn;

                /*
                 * Determine how many disks take part in this interleave
                 * and record their indices.
                 */
                ix = 0;
                for (ci = cs->sc_cinfo; 
                    ci < &cs->sc_cinfo[cs->sc_nccdisks]; ci++) {
                        if (ci->ci_size >= smallci->ci_size) {
                                ii->ii_index[ix++] = ci - cs->sc_cinfo;
                        }
                }
                ii->ii_ndisk = ix;

                /*
                 * Adjust for loop
                 */
                bn += ix * (smallci->ci_size - size);
                lbn = smallci->ci_size / cs->sc_ileave;
                size = smallci->ci_size;
        }
        if (ii == &cs->sc_itable[icount])
                panic("ccdinterlave software bug!  table exhausted");
#ifdef DEBUG
        if (ccddebug & CCDB_INIT)
                printiinfo(cs->sc_itable);
#endif
}

/* ARGSUSED */
static int
ccdopen(struct dev_open_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        int unit = ccdunit(dev);
        struct ccd_softc *cs;
        int error = 0;

#ifdef DEBUG
        if (ccddebug & CCDB_FOLLOW)
                kprintf("ccdopen(%x, %x)\n", dev, flags);
#endif
        if (unit >= numccd)
                return (ENXIO);
        cs = &ccd_softc[unit];

        if ((error = ccdlock(cs)) == 0) {
                ccdunlock(cs);
        }
        return (error);
}

/* ARGSUSED */
static int
ccdclose(struct dev_close_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        int unit = ccdunit(dev);
        struct ccd_softc *cs;
        int error = 0;

#ifdef DEBUG
        if (ccddebug & CCDB_FOLLOW)
                kprintf("ccdclose(%x, %x)\n", dev, flags);
#endif

        if (unit >= numccd)
                return (ENXIO);
        cs = &ccd_softc[unit];
        if ((error = ccdlock(cs)) == 0) {
                ccdunlock(cs);
        }
        return (error);
}

static int
ccdstrategy(struct dev_strategy_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        struct bio *bio = ap->a_bio;
        int unit = ccdunit(dev);
        struct bio *nbio;
        struct buf *bp = bio->bio_buf;
        struct ccd_softc *cs = &ccd_softc[unit];
        u_int64_t pbn;  /* in sc_secsize chunks */
        u_int32_t sz;   /* in sc_secsize chunks */

#ifdef DEBUG
        if (ccddebug & CCDB_FOLLOW)
                kprintf("ccdstrategy(%x): unit %d\n", bp, unit);
#endif
        if ((cs->sc_flags & CCDF_INITED) == 0) {
                bp->b_error = ENXIO;
                goto error;
        }

        /* If it's a nil transfer, wake up the top half now. */
        if (bp->b_bcount == 0) {
                bp->b_resid = 0;
                goto done;
        }

        /*
         * Do bounds checking and adjust transfer.  If there's an
         * error, the bounds check will flag that for us.
         */

        pbn = bio->bio_offset / cs->sc_geom.ccg_secsize;
        sz = howmany(bp->b_bcount, cs->sc_geom.ccg_secsize);

        /*
         * If out of bounds return an error.  If the request goes
         * past EOF, clip the request as appropriate.  If exactly
         * at EOF, return success (don't clip), but with 0 bytes
         * of I/O.
         *
         * Mark EOF B_INVAL (just like bad), indicating that the
         * contents of the buffer, if any, is invalid.
         */
        if ((int64_t)pbn < 0)
                goto bad;
        if (pbn + sz > cs->sc_size) {
                if (pbn > cs->sc_size || (bp->b_flags & B_BNOCLIP))
                        goto bad;
                if (pbn == cs->sc_size) {
                        bp->b_resid = bp->b_bcount;
                        bp->b_flags |= B_INVAL;
                        goto done;
                }
                sz = (long)(cs->sc_size - pbn);
                bp->b_bcount = sz * cs->sc_geom.ccg_secsize;
        }
        nbio = bio;

        bp->b_resid = bp->b_bcount;
        nbio->bio_driver_info = dev;

        /*
         * "Start" the unit.
         */
        crit_enter();
        ccdstart(cs, nbio);
        crit_exit();
        return(0);

        /*
         * note: bio, not nbio, is valid at the done label.
         */
bad:
        bp->b_error = EINVAL;
error:
        bp->b_resid = bp->b_bcount;
        bp->b_flags |= B_ERROR | B_INVAL;
done:
        biodone(bio);
        return(0);
}

static void
ccdstart(struct ccd_softc *cs, struct bio *bio)
{
        long bcount, rcount;
        struct ccdbuf *cbp[4];
        struct buf *bp = bio->bio_buf;
        /* XXX! : 2 reads and 2 writes for RAID 4/5 */
        caddr_t addr;
        off_t doffset;

#ifdef DEBUG
        if (ccddebug & CCDB_FOLLOW)
                kprintf("ccdstart(%x, %x)\n", cs, bp);
#endif

        /* Record the transaction start  */
        devstat_start_transaction(&cs->device_stats);

        /*
         * Allocate component buffers and fire off the requests
         */
        doffset = bio->bio_offset;
        addr = bp->b_data;

        for (bcount = bp->b_bcount; bcount > 0; bcount -= rcount) {
                ccdbuffer(cbp, cs, bio, doffset, addr, bcount);
                rcount = cbp[0]->cb_buf.b_bcount;

                if (cs->sc_cflags & CCDF_MIRROR) {
                        /*
                         * Mirroring.  Writes go to both disks, reads are
                         * taken from whichever disk seems most appropriate.
                         *
                         * We attempt to localize reads to the disk whos arm
                         * is nearest the read request.  We ignore seeks due
                         * to writes when making this determination and we
                         * also try to avoid hogging.
                         */
                        if (cbp[0]->cb_buf.b_cmd != BUF_CMD_READ) {
                                vn_strategy(cbp[0]->cb_vp, 
                                            &cbp[0]->cb_buf.b_bio1);
                                vn_strategy(cbp[1]->cb_vp, 
                                            &cbp[1]->cb_buf.b_bio1);
                        } else {
                                int pick = cs->sc_pick;
                                daddr_t range = cs->sc_size / 16 * cs->sc_geom.ccg_secsize;
                                if (doffset < cs->sc_blk[pick] - range ||
                                    doffset > cs->sc_blk[pick] + range
                                ) {
                                        cs->sc_pick = pick = 1 - pick;
                                }
                                cs->sc_blk[pick] = doffset + rcount;
                                vn_strategy(cbp[pick]->cb_vp, 
                                            &cbp[pick]->cb_buf.b_bio1);
                        }
                } else {
                        /*
                         * Not mirroring
                         */
                        vn_strategy(cbp[0]->cb_vp,
                                     &cbp[0]->cb_buf.b_bio1);
                }
                doffset += rcount;
                addr += rcount;
        }
}

/*
 * Build a component buffer header.
 */
static void
ccdbuffer(struct ccdbuf **cb, struct ccd_softc *cs, struct bio *bio,
          off_t doffset, caddr_t addr, long bcount)
{
        struct ccdcinfo *ci, *ci2 = NULL;       /* XXX */
        struct ccdbuf *cbp;
        u_int64_t bn;
        u_int64_t cbn;
        u_int64_t cboff;
        off_t cbc;

#ifdef DEBUG
        if (ccddebug & CCDB_IO)
                kprintf("ccdbuffer(%x, %x, %d, %x, %d)\n",
                       cs, bp, bn, addr, bcount);
#endif
        /*
         * Determine which component bn falls in.
         */
        bn = doffset / cs->sc_geom.ccg_secsize;
        cbn = bn;
        cboff = 0;

        if (cs->sc_ileave == 0) {
                /*
                 * Serially concatenated and neither a mirror nor a parity
                 * config.  This is a special case.
                 */
                daddr_t sblk;

                sblk = 0;
                for (ci = cs->sc_cinfo; cbn >= sblk + ci->ci_size; ci++)
                        sblk += ci->ci_size;
                cbn -= sblk;
        } else {
                struct ccdiinfo *ii;
                int ccdisk, off;

                /*
                 * Calculate cbn, the logical superblock (sc_ileave chunks),
                 * and cboff, a normal block offset (DEV_BSIZE chunks) relative
                 * to cbn.
                 */
                cboff = cbn % cs->sc_ileave;    /* DEV_BSIZE gran */
                cbn = cbn / cs->sc_ileave;      /* DEV_BSIZE * ileave gran */

                /*
                 * Figure out which interleave table to use.
                 */
                for (ii = cs->sc_itable; ii->ii_ndisk; ii++) {
                        if (ii->ii_startblk > cbn)
                                break;
                }
                ii--;

                /*
                 * off is the logical superblock relative to the beginning 
                 * of this interleave block.  
                 */
                off = cbn - ii->ii_startblk;

                /*
                 * We must calculate which disk component to use (ccdisk),
                 * and recalculate cbn to be the superblock relative to
                 * the beginning of the component.  This is typically done by
                 * adding 'off' and ii->ii_startoff together.  However, 'off'
                 * must typically be divided by the number of components in
                 * this interleave array to be properly convert it from a
                 * CCD-relative logical superblock number to a 
                 * component-relative superblock number.
                 */
                if (ii->ii_ndisk == 1) {
                        /*
                         * When we have just one disk, it can't be a mirror
                         * or a parity config.
                         */
                        ccdisk = ii->ii_index[0];
                        cbn = ii->ii_startoff + off;
                } else {
                        if (cs->sc_cflags & CCDF_MIRROR) {
                                /*
                                 * We have forced a uniform mapping, resulting
                                 * in a single interleave array.  We double
                                 * up on the first half of the available
                                 * components and our mirror is in the second
                                 * half.  This only works with a single 
                                 * interleave array because doubling up
                                 * doubles the number of sectors, so there
                                 * cannot be another interleave array because
                                 * the next interleave array's calculations
                                 * would be off.
                                 */
                                int ndisk2 = ii->ii_ndisk / 2;
                                ccdisk = ii->ii_index[off % ndisk2];
                                cbn = ii->ii_startoff + off / ndisk2;
                                ci2 = &cs->sc_cinfo[ccdisk + ndisk2];
                        } else if (cs->sc_cflags & CCDF_PARITY) {
                                /* 
                                 * XXX not implemented yet
                                 */
                                int ndisk2 = ii->ii_ndisk - 1;
                                ccdisk = ii->ii_index[off % ndisk2];
                                cbn = ii->ii_startoff + off / ndisk2;
                                if (cbn % ii->ii_ndisk <= ccdisk)
                                        ccdisk++;
                        } else {
                                ccdisk = ii->ii_index[off % ii->ii_ndisk];
                                cbn = ii->ii_startoff + off / ii->ii_ndisk;
                        }
                }

                ci = &cs->sc_cinfo[ccdisk];

                /*
                 * Convert cbn from a superblock to a normal block so it
                 * can be used to calculate (along with cboff) the normal
                 * block index into this particular disk.
                 */
                cbn *= cs->sc_ileave;
        }

        /*
         * Fill in the component buf structure.
         *
         * NOTE: devices do not use b_bufsize, only b_bcount, but b_bcount
         * will be truncated on device EOF so we use b_bufsize to detect
         * the case.
         */
        cbp = getccdbuf();
        cbp->cb_buf.b_cmd = bio->bio_buf->b_cmd;
        cbp->cb_buf.b_flags |= bio->bio_buf->b_flags;
        cbp->cb_buf.b_data = addr;
        cbp->cb_vp = ci->ci_vp;
        if (cs->sc_ileave == 0)
              cbc = dbtob((off_t)(ci->ci_size - cbn));
        else
              cbc = dbtob((off_t)(cs->sc_ileave - cboff));
        cbp->cb_buf.b_bcount = (cbc < bcount) ? cbc : bcount;
        cbp->cb_buf.b_bufsize = cbp->cb_buf.b_bcount;

        cbp->cb_buf.b_bio1.bio_done = ccdiodone;
        cbp->cb_buf.b_bio1.bio_caller_info1.ptr = cbp;
        cbp->cb_buf.b_bio1.bio_offset = dbtob(cbn + cboff + ci->ci_skip);

        /*
         * context for ccdiodone
         */
        cbp->cb_obio = bio;
        cbp->cb_unit = cs - ccd_softc;
        cbp->cb_comp = ci - cs->sc_cinfo;

#ifdef DEBUG
        if (ccddebug & CCDB_IO)
                kprintf(" dev %x(u%d): cbp %x off %lld addr %x bcnt %d\n",
                       ci->ci_dev, ci-cs->sc_cinfo, cbp,
                       cbp->cb_buf.b_bio1.bio_offset,
                       cbp->cb_buf.b_data, cbp->cb_buf.b_bcount);
#endif
        cb[0] = cbp;

        /*
         * Note: both I/O's setup when reading from mirror, but only one
         * will be executed.
         */
        if (cs->sc_cflags & CCDF_MIRROR) {
                /* mirror, setup second I/O */
                cbp = getccdbuf();

                cbp->cb_buf.b_cmd = bio->bio_buf->b_cmd;
                cbp->cb_buf.b_flags |= bio->bio_buf->b_flags;
                cbp->cb_buf.b_data = addr;
                cbp->cb_vp = ci2->ci_vp;
                if (cs->sc_ileave == 0)
                      cbc = dbtob((off_t)(ci->ci_size - cbn));
                else
                      cbc = dbtob((off_t)(cs->sc_ileave - cboff));
                cbp->cb_buf.b_bcount = (cbc < bcount) ? cbc : bcount;
                cbp->cb_buf.b_bufsize = cbp->cb_buf.b_bcount;

                cbp->cb_buf.b_bio1.bio_done = ccdiodone;
                cbp->cb_buf.b_bio1.bio_caller_info1.ptr = cbp;
                cbp->cb_buf.b_bio1.bio_offset = dbtob(cbn + cboff + ci2->ci_skip);

                /*
                 * context for ccdiodone
                 */
                cbp->cb_obio = bio;
                cbp->cb_unit = cs - ccd_softc;
                cbp->cb_comp = ci2 - cs->sc_cinfo;
                cb[1] = cbp;
                /* link together the ccdbuf's and clear "mirror done" flag */
                cb[0]->cb_mirror = cb[1];
                cb[1]->cb_mirror = cb[0];
                cb[0]->cb_pflags &= ~CCDPF_MIRROR_DONE;
                cb[1]->cb_pflags &= ~CCDPF_MIRROR_DONE;
        }
}

static void
ccdintr(struct ccd_softc *cs, struct bio *bio)
{
        struct buf *bp = bio->bio_buf;

#ifdef DEBUG
        if (ccddebug & CCDB_FOLLOW)
                kprintf("ccdintr(%x, %x)\n", cs, bp);
#endif
        /*
         * Request is done for better or worse, wakeup the top half.
         */
        if (bp->b_flags & B_ERROR)
                bp->b_resid = bp->b_bcount;
        devstat_end_transaction_buf(&cs->device_stats, bp);
        biodone(bio);
}

/*
 * Called at interrupt time.
 * Mark the component as done and if all components are done,
 * take a ccd interrupt.
 */
static void
ccdiodone(struct bio *bio)
{
        struct ccdbuf *cbp = bio->bio_caller_info1.ptr;
        struct bio *obio = cbp->cb_obio;
        struct buf *obp = obio->bio_buf;
        int unit = cbp->cb_unit;
        int count;

        /*
         * Since we do not have exclusive access to underlying devices,
         * we can't keep cache translations around.
         */
        clearbiocache(bio->bio_next);

        crit_enter();
#ifdef DEBUG
        if (ccddebug & CCDB_FOLLOW)
                kprintf("ccdiodone(%x)\n", cbp);
        if (ccddebug & CCDB_IO) {
                kprintf("ccdiodone: bp %x bcount %d resid %d\n",
                       obp, obp->b_bcount, obp->b_resid);
                kprintf(" dev %x(u%d), cbp %x off %lld addr %x bcnt %d\n",
                       cbp->cb_buf.b_dev, cbp->cb_comp, cbp,
                       cbp->cb_buf.b_loffset, cbp->cb_buf.b_data,
                       cbp->cb_buf.b_bcount);
        }
#endif

        /*
         * If an error occured, report it.  If this is a mirrored 
         * configuration and the first of two possible reads, do not
         * set the error in the bp yet because the second read may
         * succeed.
         */
        if (cbp->cb_buf.b_flags & B_ERROR) {
                const char *msg = "";

                if ((ccd_softc[unit].sc_cflags & CCDF_MIRROR) &&
                    (cbp->cb_buf.b_cmd == BUF_CMD_READ) &&
                    (cbp->cb_pflags & CCDPF_MIRROR_DONE) == 0) {
                        /*
                         * We will try our read on the other disk down
                         * below, also reverse the default pick so if we 
                         * are doing a scan we do not keep hitting the
                         * bad disk first.
                         */
                        struct ccd_softc *cs = &ccd_softc[unit];

                        msg = ", trying other disk";
                        cs->sc_pick = 1 - cs->sc_pick;
                        cs->sc_blk[cs->sc_pick] = obio->bio_offset;
                } else {
                        obp->b_flags |= B_ERROR;
                        obp->b_error = cbp->cb_buf.b_error ? 
                            cbp->cb_buf.b_error : EIO;
                }
                kprintf("ccd%d: error %d on component %d offset %lld (ccd offset %lld)%s\n",
                       unit, obp->b_error, cbp->cb_comp, 
                       cbp->cb_buf.b_bio2.bio_offset, 
                       obio->bio_offset, msg);
        }

        /*
         * Process mirror.  If we are writing, I/O has been initiated on both
         * buffers and we fall through only after both are finished.
         *
         * If we are reading only one I/O is initiated at a time.  If an
         * error occurs we initiate the second I/O and return, otherwise 
         * we free the second I/O without initiating it.
         */

        if (ccd_softc[unit].sc_cflags & CCDF_MIRROR) {
                if (cbp->cb_buf.b_cmd != BUF_CMD_READ) {
                        /*
                         * When writing, handshake with the second buffer
                         * to determine when both are done.  If both are not
                         * done, return here.
                         */
                        if ((cbp->cb_pflags & CCDPF_MIRROR_DONE) == 0) {
                                cbp->cb_mirror->cb_pflags |= CCDPF_MIRROR_DONE;
                                putccdbuf(cbp);
                                crit_exit();
                                return;
                        }
                } else {
                        /*
                         * When reading, either dispose of the second buffer
                         * or initiate I/O on the second buffer if an error 
                         * occured with this one.
                         */
                        if ((cbp->cb_pflags & CCDPF_MIRROR_DONE) == 0) {
                                if (cbp->cb_buf.b_flags & B_ERROR) {
                                        cbp->cb_mirror->cb_pflags |= 
                                            CCDPF_MIRROR_DONE;
                                        vn_strategy(
                                            cbp->cb_mirror->cb_vp, 
                                            &cbp->cb_mirror->cb_buf.b_bio1
                                        );
                                        putccdbuf(cbp);
                                        crit_exit();
                                        return;
                                } else {
                                        putccdbuf(cbp->cb_mirror);
                                        /* fall through */
                                }
                        }
                }
        }

        /*
         * Use our saved b_bufsize to determine if an unexpected EOF occured.
         */
        count = cbp->cb_buf.b_bufsize;
        putccdbuf(cbp);

        /*
         * If all done, "interrupt".
         */
        obp->b_resid -= count;
        if (obp->b_resid < 0)
                panic("ccdiodone: count");
        if (obp->b_resid == 0)
                ccdintr(&ccd_softc[unit], obio);
        crit_exit();
}

static int
ccdioctl(struct dev_ioctl_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        int unit = ccdunit(dev);
        int i, j, lookedup = 0, error = 0;
        struct ccd_softc *cs;
        struct ccd_ioctl *ccio = (struct ccd_ioctl *)ap->a_data;
        struct ccddevice ccd;
        struct disk_info info;
        char **cpp;
        struct vnode **vpp;

        if (unit >= numccd)
                return (ENXIO);
        cs = &ccd_softc[unit];

        bzero(&ccd, sizeof(ccd));

        switch (ap->a_cmd) {
        case CCDIOCSET:
                if (cs->sc_flags & CCDF_INITED)
                        return (EBUSY);

                if ((ap->a_fflag & FWRITE) == 0)
                        return (EBADF);

                if ((error = ccdlock(cs)) != 0)
                        return (error);

                if (ccio->ccio_ndisks > CCD_MAXNDISKS) {
                        ccdunlock(cs);
                        return (EINVAL);
                }
 
                /* Fill in some important bits. */
                ccd.ccd_unit = unit;
                ccd.ccd_interleave = ccio->ccio_ileave;
                if (ccd.ccd_interleave == 0 &&
                    ((ccio->ccio_flags & CCDF_MIRROR) ||
                     (ccio->ccio_flags & CCDF_PARITY))) {
                        kprintf("ccd%d: disabling mirror/parity, interleave is 0\n", unit);
                        ccio->ccio_flags &= ~(CCDF_MIRROR | CCDF_PARITY);
                }
                if ((ccio->ccio_flags & CCDF_MIRROR) &&
                    (ccio->ccio_flags & CCDF_PARITY)) {
                        kprintf("ccd%d: can't specify both mirror and parity, using mirror\n", unit);
                        ccio->ccio_flags &= ~CCDF_PARITY;
                }
                if ((ccio->ccio_flags & (CCDF_MIRROR | CCDF_PARITY)) &&
                    !(ccio->ccio_flags & CCDF_UNIFORM)) {
                        kprintf("ccd%d: mirror/parity forces uniform flag\n",
                               unit);
                        ccio->ccio_flags |= CCDF_UNIFORM;
                }
                ccd.ccd_flags = ccio->ccio_flags & CCDF_USERMASK;

                /*
                 * Allocate space for and copy in the array of
                 * componet pathnames and device numbers.
                 */
                cpp = kmalloc(ccio->ccio_ndisks * sizeof(char *),
                    M_DEVBUF, M_WAITOK);
                vpp = kmalloc(ccio->ccio_ndisks * sizeof(struct vnode *),
                    M_DEVBUF, M_WAITOK);

                error = copyin((caddr_t)ccio->ccio_disks, (caddr_t)cpp,
                                ccio->ccio_ndisks * sizeof(char **));
                if (error) {
                        kfree(vpp, M_DEVBUF);
                        kfree(cpp, M_DEVBUF);
                        ccdunlock(cs);
                        return (error);
                }

#ifdef DEBUG
                if (ccddebug & CCDB_INIT) {
                        for (i = 0; i < ccio->ccio_ndisks; ++i)
                                kprintf("ccdioctl: component %d: 0x%x\n",
                                    i, cpp[i]);
                }
#endif

                for (i = 0; i < ccio->ccio_ndisks; ++i) {
#ifdef DEBUG
                        if (ccddebug & CCDB_INIT)
                                kprintf("ccdioctl: lookedup = %d\n", lookedup);
#endif
                        if ((error = ccdlookup(cpp[i], &vpp[i])) != 0) {
                                for (j = 0; j < lookedup; ++j)
                                        (void)vn_close(vpp[j], FREAD|FWRITE);
                                kfree(vpp, M_DEVBUF);
                                kfree(cpp, M_DEVBUF);
                                ccdunlock(cs);
                                return (error);
                        }
                        ++lookedup;
                }
                ccd.ccd_cpp = cpp;
                ccd.ccd_vpp = vpp;
                ccd.ccd_ndev = ccio->ccio_ndisks;

                /*
                 * Initialize the ccd.  Fills in the softc for us.
                 */
                if ((error = ccdinit(&ccd, cpp, ap->a_cred)) != 0) {
                        for (j = 0; j < lookedup; ++j)
                                (void)vn_close(vpp[j], FREAD|FWRITE);
                        kfree(vpp, M_DEVBUF);
                        kfree(cpp, M_DEVBUF);
                        ccdunlock(cs);
                        return (error);
                }

                /*
                 * The ccd has been successfully initialized, so
                 * we can place it into the array and read the disklabel.
                 */
                bcopy(&ccd, &ccddevs[unit], sizeof(ccd));
                ccio->ccio_unit = unit;
                ccio->ccio_size = cs->sc_size;

                bzero(&info, sizeof(info));
                info.d_media_blksize = cs->sc_geom.ccg_secsize;
                info.d_media_blocks  = cs->sc_size;
                info.d_nheads        = cs->sc_geom.ccg_ntracks;
                info.d_secpertrack   = cs->sc_geom.ccg_nsectors;
                info.d_ncylinders    = cs->sc_geom.ccg_ncylinders;
                info.d_secpercyl     = info.d_nheads * info.d_secpertrack;

                /*
                 * For cases where a label is directly applied to the ccd,
                 * without slices, DSO_COMPATMBR forces one sector be 
                 * reserved for backwards compatibility.
                 */
                info.d_dsflags       = DSO_COMPATMBR;
                disk_setdiskinfo(&cs->sc_disk, &info);

                ccdunlock(cs);

                break;

        case CCDIOCCLR:
                if ((cs->sc_flags & CCDF_INITED) == 0)
                        return (ENXIO);

                if ((ap->a_fflag & FWRITE) == 0)
                        return (EBADF);

                if ((error = ccdlock(cs)) != 0)
                        return (error);

                if (dev_drefs(cs->sc_dev) > 1) {
                        ccdunlock(cs);
                        return (EBUSY);
                }

                /*
                 * Free ccd_softc information and clear entry.
                 */

                /* Close the components and free their pathnames. */
                for (i = 0; i < cs->sc_nccdisks; ++i) {
                        /*
                         * XXX: this close could potentially fail and
                         * cause Bad Things.  Maybe we need to force
                         * the close to happen?
                         */
#ifdef DEBUG
                        if (ccddebug & CCDB_VNODE)
                                vprint("CCDIOCCLR: vnode info",
                                    cs->sc_cinfo[i].ci_vp);
#endif
                        (void)vn_close(cs->sc_cinfo[i].ci_vp, FREAD|FWRITE);
                        kfree(cs->sc_cinfo[i].ci_path, M_DEVBUF);
                }

                /* Free interleave index. */
                for (i = 0; cs->sc_itable[i].ii_ndisk; ++i)
                        kfree(cs->sc_itable[i].ii_index, M_DEVBUF);

                /* Free component info and interleave table. */
                kfree(cs->sc_cinfo, M_DEVBUF);
                kfree(cs->sc_itable, M_DEVBUF);
                cs->sc_cinfo = NULL;
                cs->sc_itable = NULL;
                cs->sc_flags &= ~CCDF_INITED;

                /*
                 * Free ccddevice information and clear entry.
                 */
                kfree(ccddevs[unit].ccd_cpp, M_DEVBUF);
                kfree(ccddevs[unit].ccd_vpp, M_DEVBUF);
                bcopy(&ccd, &ccddevs[unit], sizeof(ccd));

                /*
                 * And remove the devstat entry.
                 */
                devstat_remove_entry(&cs->device_stats);

                /* This must be atomic. */
                crit_enter();
                ccdunlock(cs);
                crit_exit();

                break;

        default:
                return (ENOTTY);
        }

        return (0);
}

static int
ccddump(struct dev_dump_args *ap)
{
        /* Not implemented. */
        return ENXIO;
}

/*
 * Lookup the provided name in the filesystem.  If the file exists,
 * is a valid block device, and isn't being used by anyone else,
 * set *vpp to the file's vnode.
 */
static int
ccdlookup(char *path, struct vnode **vpp)
{
        struct nlookupdata nd;
        struct vnode *vp;
        int error;

        *vpp = NULL;

        error = nlookup_init(&nd, path, UIO_USERSPACE, NLC_FOLLOW|NLC_LOCKVP);
        if (error)
                return (error);
        if ((error = vn_open(&nd, NULL, FREAD|FWRITE, 0)) != 0) {
#ifdef DEBUG
                if (ccddebug & CCDB_FOLLOW|CCDB_INIT)
                        kprintf("ccdlookup: vn_open error = %d\n", error);
#endif
                goto done;
        }
        vp = nd.nl_open_vp;

        if (vp->v_opencount > 1) {
                error = EBUSY;
                goto done;
        }

        if (!vn_isdisk(vp, &error)) 
                goto done;

#ifdef DEBUG
        if (ccddebug & CCDB_VNODE)
                vprint("ccdlookup: vnode info", vp);
#endif

        vn_unlock(vp);
        nd.nl_open_vp = NULL;
        nlookup_done(&nd);
        *vpp = vp;                              /* leave ref intact  */
        return (0);
done:
        nlookup_done(&nd);
        return (error);
}

/*
 * Wait interruptibly for an exclusive lock.
 *
 * XXX
 * Several drivers do this; it should be abstracted and made MP-safe.
 */
static int
ccdlock(struct ccd_softc *cs)
{
        int error;

        while ((cs->sc_flags & CCDF_LOCKED) != 0) {
                cs->sc_flags |= CCDF_WANTED;
                if ((error = tsleep(cs, PCATCH, "ccdlck", 0)) != 0)
                        return (error);
        }
        cs->sc_flags |= CCDF_LOCKED;
        return (0);
}

/*
 * Unlock and wake up any waiters.
 */
static void
ccdunlock(struct ccd_softc *cs)
{

        cs->sc_flags &= ~CCDF_LOCKED;
        if ((cs->sc_flags & CCDF_WANTED) != 0) {
                cs->sc_flags &= ~CCDF_WANTED;
                wakeup(cs);
        }
}

#ifdef DEBUG
static void
printiinfo(struct ccdiinfo *ii)
{
        int ix, i;

        for (ix = 0; ii->ii_ndisk; ix++, ii++) {
                kprintf(" itab[%d]: #dk %d sblk %d soff %d",
                       ix, ii->ii_ndisk, ii->ii_startblk, ii->ii_startoff);
                for (i = 0; i < ii->ii_ndisk; i++)
                        kprintf(" %d", ii->ii_index[i]);
                kprintf("\n");
        }
}
#endif

\f
/* Local Variables: */
/* c-argdecl-indent: 8 */
/* c-continued-statement-offset: 8 */
/* c-indent-level: 8 */
/* End: */