Continue untangling the disklabel. Add sector index reservation fields

[dragonfly/port-amd64.git] / sys / kern / subr_diskslice.c

/*-
 * Copyright (c) 1994 Bruce D. Evans.
 * All rights reserved.
 *
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * William Jolitz.
 *
 * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
 * 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 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: @(#)wd.c  7.2 (Berkeley) 5/9/91
 *      from: wd.c,v 1.55 1994/10/22 01:57:12 phk Exp $
 *      from: @(#)ufs_disksubr.c        7.16 (Berkeley) 5/4/91
 *      from: ufs_disksubr.c,v 1.8 1994/06/07 01:21:39 phk Exp $
 * $FreeBSD: src/sys/kern/subr_diskslice.c,v 1.82.2.6 2001/07/24 09:49:41 dd Exp $
 * $DragonFly: src/sys/kern/subr_diskslice.c,v 1.32 2007/05/16 05:20:23 dillon Exp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/conf.h>
#include <sys/disklabel.h>
#include <sys/diskslice.h>
#include <sys/disk.h>
#include <sys/diskmbr.h>
#include <sys/fcntl.h>
#include <sys/malloc.h>
#include <sys/stat.h>
#include <sys/syslog.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/device.h>
#include <sys/thread2.h>

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

#define TRACE(str)      do { if (ds_debug) kprintf str; } while (0)

typedef u_char  bool_t;

static volatile bool_t ds_debug;

static struct disklabel *clone_label (struct disk_info *info,
                                        struct diskslice *sp);
static void dsiodone (struct bio *bio);
static char *fixlabel (char *sname, struct diskslice *sp,
                           struct disklabel *lp, int writeflag);
static void free_ds_label (struct diskslices *ssp, int slice);
static void partition_info (char *sname, int part, struct partition *pp);
static void slice_info (char *sname, struct diskslice *sp);
static void set_ds_label (struct diskslices *ssp, int slice,
                              struct disklabel *lp);
static void set_ds_wlabel (struct diskslices *ssp, int slice, int wlabel);

/*
 * Create a disklabel based on a disk_info structure, initializing
 * the appropriate fields and creating a raw partition that covers the
 * whole disk.
 *
 * If a diskslice is passed, the label is truncated to the slice
 */
static struct disklabel *
clone_label(struct disk_info *info, struct diskslice *sp)
{
        struct disklabel *lp1;

        lp1 = kmalloc(sizeof *lp1, M_DEVBUF, M_WAITOK | M_ZERO);
        lp1->d_nsectors = info->d_secpertrack;
        lp1->d_ntracks = info->d_nheads;
        lp1->d_secpercyl = info->d_secpercyl;
        lp1->d_secsize = info->d_media_blksize;

        if (sp) {
                lp1->d_secperunit = (u_int)sp->ds_size;
                lp1->d_partitions[RAW_PART].p_size = lp1->d_secperunit;
        } else {
                lp1->d_secperunit = (u_int)info->d_media_blocks;
                lp1->d_partitions[RAW_PART].p_size = lp1->d_secperunit;
        }

        /*
         * Used by the CD driver to create a compatibility slice which
         * allows us to mount root from the CD.
         */
        if (info->d_dsflags & DSO_COMPATPARTA) {
                lp1->d_partitions[0].p_size = lp1->d_secperunit;
                lp1->d_partitions[0].p_fstype = FS_OTHER;
        }

        if (lp1->d_typename[0] == '\0')
                strncpy(lp1->d_typename, "amnesiac", sizeof(lp1->d_typename));
        if (lp1->d_packname[0] == '\0')
                strncpy(lp1->d_packname, "fictitious", sizeof(lp1->d_packname));
        if (lp1->d_nsectors == 0)
                lp1->d_nsectors = 32;
        if (lp1->d_ntracks == 0)
                lp1->d_ntracks = 64;
        lp1->d_secpercyl = lp1->d_nsectors * lp1->d_ntracks;
        lp1->d_ncylinders = lp1->d_secperunit / lp1->d_secpercyl;
        if (lp1->d_rpm == 0)
                lp1->d_rpm = 3600;
        if (lp1->d_interleave == 0)
                lp1->d_interleave = 1;
        if (lp1->d_npartitions < RAW_PART + 1)
                lp1->d_npartitions = MAXPARTITIONS;
        if (lp1->d_bbsize == 0)
                lp1->d_bbsize = BBSIZE;
        if (lp1->d_sbsize == 0)
                lp1->d_sbsize = SBSIZE;
        lp1->d_partitions[RAW_PART].p_size = lp1->d_secperunit;
        lp1->d_magic = DISKMAGIC;
        lp1->d_magic2 = DISKMAGIC;
        lp1->d_checksum = dkcksum(lp1);
        return (lp1);
}

/*
 * Determine the size of the transfer, and make sure it is
 * within the boundaries of the partition. Adjust transfer
 * if needed, and signal errors or early completion.
 *
 * XXX TODO:
 *      o Split buffers that are too big for the device.
 *      o Check for overflow.
 *      o Finish cleaning this up.
 *
 * This function returns 1 on success, 0 if transfer equates
 * to EOF (end of disk) or -1 on failure.  The appropriate 
 * 'errno' value is also set in bp->b_error and bp->b_flags
 * is marked with B_ERROR.
 */
struct bio *
dscheck(cdev_t dev, struct bio *bio, struct diskslices *ssp)
{
        struct buf *bp = bio->bio_buf;
        struct bio *nbio;
        struct disklabel *lp;
        char *msg;
        long nsec;
        struct partition *pp;
        u_int64_t secno;
        u_int64_t endsecno;
        u_int64_t labelsect;
        u_int64_t slicerel_secno;
        struct diskslice *sp;
        int shift;
        int mask;

        if (bio->bio_offset < 0) {
                kprintf("dscheck(%s): negative bio_offset %lld\n", 
                    devtoname(dev), bio->bio_offset);
                goto bad;
        }
        sp = &ssp->dss_slices[dkslice(dev)];
        lp = sp->ds_label;

        if (ssp->dss_secmult == 1) {
                shift = DEV_BSHIFT;
                goto doshift;
        } else if (ssp->dss_secshift != -1) {
                shift = DEV_BSHIFT + ssp->dss_secshift;
doshift:
                mask = (1 << shift) - 1;
                if ((int)bp->b_bcount & mask)
                        goto bad_bcount;
                if ((int)bio->bio_offset & mask)
                        goto bad_blkno;
                secno = bio->bio_offset >> shift;
                nsec = bp->b_bcount >> shift;
        } else {
                if (bp->b_bcount % ssp->dss_secsize)
                        goto bad_bcount;
                if (bio->bio_offset % ssp->dss_secsize)
                        goto bad_blkno;
                secno = bio->bio_offset / ssp->dss_secsize;
                nsec = bp->b_bcount / ssp->dss_secsize;
        }
        if (lp == NULL) {
                labelsect = -LABELSECTOR - 1;
                endsecno = sp->ds_size;
                slicerel_secno = secno;
        } else {
                labelsect = lp->d_partitions[LABEL_PART].p_offset;
                if (labelsect != 0)
                        Debugger("labelsect != 0 in dscheck()");
                pp = &lp->d_partitions[dkpart(dev)];
                endsecno = pp->p_size;
                slicerel_secno = pp->p_offset + secno;
        }

        /* overwriting disk label ? */
        /* XXX should also protect bootstrap in first 8K */
        if (slicerel_secno <= LABELSECTOR + labelsect &&
#if LABELSECTOR != 0
            slicerel_secno + nsec > LABELSECTOR + labelsect &&
#endif
            bp->b_cmd != BUF_CMD_READ && sp->ds_wlabel == 0) {
                bp->b_error = EROFS;
                goto error;
        }

#if defined(DOSBBSECTOR) && defined(notyet)
        /* overwriting master boot record? */
        if (slicerel_secno <= DOSBBSECTOR && bp->b_cmd != BUF_CMD_READ &&
            sp->ds_wlabel == 0) {
                bp->b_error = EROFS;
                goto error;
        }
#endif

        /*
         * EOF handling
         */
        if (secno + nsec > endsecno) {
                /*
                 * Return an error if beyond the end of the disk, or
                 * if B_BNOCLIP is set.  Tell the system that we do not
                 * need to keep the buffer around.
                 */
                if (secno > endsecno || (bp->b_flags & B_BNOCLIP))
                        goto bad;

                /*
                 * If exactly at end of disk, return an EOF.  Throw away
                 * the buffer contents, if any, by setting B_INVAL.
                 */
                if (secno == endsecno) {
                        bp->b_resid = bp->b_bcount;
                        bp->b_flags |= B_INVAL;
                        goto done;
                }

                /*
                 * Else truncate
                 */
                nsec = endsecno - secno;
                bp->b_bcount = nsec * ssp->dss_secsize;
        }

        nbio = push_bio(bio);
        nbio->bio_offset = (off_t)(sp->ds_offset + slicerel_secno) * 
                           ssp->dss_secsize;

        /*
         * Snoop on label accesses if the slice offset is nonzero.  Fudge
         * offsets in the label to keep the in-core label coherent with
         * the on-disk one.
         */
        if (slicerel_secno <= LABELSECTOR + labelsect
#if LABELSECTOR != 0
            && slicerel_secno + nsec > LABELSECTOR + labelsect
#endif
            && sp->ds_offset != 0) {
                nbio->bio_done = dsiodone;
                nbio->bio_caller_info1.ptr = sp;
                nbio->bio_caller_info2.offset = 
                        (off_t)(LABELSECTOR + labelsect - slicerel_secno) *
                        ssp->dss_secsize;
                if (bp->b_cmd != BUF_CMD_READ) {
                        /*
                         * XXX even disklabel(8) writes directly so we need
                         * to adjust writes.  Perhaps we should drop support
                         * for DIOCWLABEL (always write protect labels) and
                         * require the use of DIOCWDINFO.
                         *
                         * XXX probably need to copy the data to avoid even
                         * temporarily corrupting the in-core copy.
                         */
                        /* XXX need name here. */
                        msg = fixlabel(
                                NULL, sp,
                               (struct disklabel *)
                               (bp->b_data + (int)nbio->bio_caller_info2.offset),
                               TRUE);
                        if (msg != NULL) {
                                kprintf("dscheck(%s): %s\n", 
                                    devtoname(dev), msg);
                                bp->b_error = EROFS;
                                pop_bio(nbio);
                                goto error;
                        }
                }
        }
        return (nbio);

bad_bcount:
        kprintf(
        "dscheck(%s): b_bcount %d is not on a sector boundary (ssize %d)\n",
            devtoname(dev), bp->b_bcount, ssp->dss_secsize);
        goto bad;

bad_blkno:
        kprintf(
        "dscheck(%s): bio_offset %lld is not on a sector boundary (ssize %d)\n",
            devtoname(dev), bio->bio_offset, ssp->dss_secsize);
bad:
        bp->b_error = EINVAL;
        /* fall through */
error:
        /*
         * Terminate the I/O with a ranging error.  Since the buffer is
         * either illegal or beyond the file EOF, mark it B_INVAL as well.
         */
        bp->b_resid = bp->b_bcount;
        bp->b_flags |= B_ERROR | B_INVAL;
done:
        /*
         * Caller must biodone() the originally passed bio if NULL is
         * returned.
         */
        return (NULL);
}

void
dsclose(cdev_t dev, int mode, struct diskslices *ssp)
{
        u_char mask;
        struct diskslice *sp;

        sp = &ssp->dss_slices[dkslice(dev)];
        mask = 1 << dkpart(dev);
        sp->ds_openmask &= ~mask;
}

void
dsgone(struct diskslices **sspp)
{
        int slice;
        struct diskslice *sp;
        struct diskslices *ssp;

        for (slice = 0, ssp = *sspp; slice < ssp->dss_nslices; slice++) {
                sp = &ssp->dss_slices[slice];
                free_ds_label(ssp, slice);
        }
        kfree(ssp, M_DEVBUF);
        *sspp = NULL;
}

/*
 * For the "write" commands (DIOCSDINFO and DIOCWDINFO), this
 * is subject to the same restriction as dsopen().
 */
int
dsioctl(cdev_t dev, u_long cmd, caddr_t data, int flags,
        struct diskslices **sspp, struct disk_info *info)
{
        int error;
        struct disklabel *lp;
        int old_wlabel;
        u_char openmask;
        int part;
        int slice;
        struct diskslice *sp;
        struct diskslices *ssp;
        struct partition *pp;

        slice = dkslice(dev);
        ssp = *sspp;
        sp = &ssp->dss_slices[slice];
        lp = sp->ds_label;
        switch (cmd) {

        case DIOCGDVIRGIN:
                lp = (struct disklabel *)data;
                if (ssp->dss_slices[WHOLE_DISK_SLICE].ds_label) {
                        *lp = *ssp->dss_slices[WHOLE_DISK_SLICE].ds_label;
                } else {
                        bzero(lp, sizeof(struct disklabel));
                }

                lp->d_magic = DISKMAGIC;
                lp->d_magic2 = DISKMAGIC;
                pp = &lp->d_partitions[RAW_PART];
                pp->p_offset = 0;
                pp->p_size = sp->ds_size;

                lp->d_npartitions = MAXPARTITIONS;
                if (lp->d_interleave == 0)
                        lp->d_interleave = 1;
                if (lp->d_rpm == 0)
                        lp->d_rpm = 3600;
                if (lp->d_nsectors == 0)
                        lp->d_nsectors = 32;
                if (lp->d_ntracks == 0)
                        lp->d_ntracks = 64;

                lp->d_bbsize = BBSIZE;
                lp->d_sbsize = SBSIZE;
                lp->d_secpercyl = lp->d_nsectors * lp->d_ntracks;
                lp->d_ncylinders = sp->ds_size / lp->d_secpercyl;
                lp->d_secperunit = sp->ds_size;
                lp->d_checksum = 0;
                lp->d_checksum = dkcksum(lp);
                return (0);

        case DIOCGDINFO:
                if (lp == NULL)
                        return (EINVAL);
                *(struct disklabel *)data = *lp;
                return (0);

#ifdef notyet
        case DIOCGDINFOP:
                if (lp == NULL)
                        return (EINVAL);
                *(struct disklabel **)data = lp;
                return (0);
#endif

        case DIOCGPART:
                {
                        struct partinfo *dpart = (void *)data;

                        bzero(dpart, sizeof(*dpart));
                        dpart->media_offset   = (u_int64_t)sp->ds_offset *
                                                info->d_media_blksize;
                        dpart->media_size     = (u_int64_t)sp->ds_size *
                                                info->d_media_blksize;
                        dpart->media_blocks   = sp->ds_size;
                        dpart->media_blksize  = info->d_media_blksize;
                        dpart->skip_platform = sp->ds_skip_platform;
                        dpart->skip_bsdlabel = sp->ds_skip_bsdlabel;
                        if (lp && slice != WHOLE_DISK_SLICE) {
                                struct partition *p;

                                p = &lp->d_partitions[dkpart(dev)];
                                dpart->fstype = p->p_fstype;
                                dpart->media_offset += (u_int64_t)p->p_offset *
                                                       info->d_media_blksize;
                                dpart->media_size = (u_int64_t)p->p_size *
                                                    info->d_media_blksize;

                                /*
                                 * partition starting sector (p_offset)
                                 * requires slice's reserved areas to be
                                 * adjusted.
                                 */
                                if (dpart->skip_platform > p->p_offset)
                                        dpart->skip_platform -= p->p_offset;
                                else
                                        dpart->skip_platform = 0;
                                if (dpart->skip_bsdlabel > p->p_offset)
                                        dpart->skip_bsdlabel -= p->p_offset;
                                else
                                        dpart->skip_bsdlabel = 0;
                        }
                }
                return (0);

        case DIOCGSLICEINFO:
                bcopy(ssp, data, (char *)&ssp->dss_slices[ssp->dss_nslices] -
                                 (char *)ssp);
                return (0);

        case DIOCSDINFO:
                if (slice == WHOLE_DISK_SLICE)
                        return (ENODEV);
                if (!(flags & FWRITE))
                        return (EBADF);
                lp = kmalloc(sizeof *lp, M_DEVBUF, M_WAITOK);
                if (sp->ds_label == NULL)
                        bzero(lp, sizeof *lp);
                else
                        bcopy(sp->ds_label, lp, sizeof *lp);
                if (sp->ds_label == NULL) {
                        openmask = 0;
                } else {
                        openmask = sp->ds_openmask;
                        if (slice == COMPATIBILITY_SLICE) {
                                openmask |= ssp->dss_slices[
                                    ssp->dss_first_bsd_slice].ds_openmask;
                        } else if (slice == ssp->dss_first_bsd_slice) {
                                openmask |= ssp->dss_slices[
                                    COMPATIBILITY_SLICE].ds_openmask;
                        }
                }
                error = setdisklabel(lp, (struct disklabel *)data,
                                     (u_long)openmask);
                /* XXX why doesn't setdisklabel() check this? */
                if (error == 0 && lp->d_partitions[RAW_PART].p_offset != 0)
                        error = EXDEV;
                if (error == 0) {
                        if (lp->d_secperunit > sp->ds_size)
                                error = ENOSPC;
                        for (part = 0; part < lp->d_npartitions; part++)
                                if (lp->d_partitions[part].p_size > sp->ds_size)
                                        error = ENOSPC;
                }
                if (error != 0) {
                        kfree(lp, M_DEVBUF);
                        return (error);
                }
                free_ds_label(ssp, slice);
                set_ds_label(ssp, slice, lp);
                return (0);

        case DIOCSYNCSLICEINFO:
                if (slice != WHOLE_DISK_SLICE || dkpart(dev) != RAW_PART)
                        return (EINVAL);
                if (*(int *)data == 0) {
                        for (slice = 0; slice < ssp->dss_nslices; slice++) {
                                openmask = ssp->dss_slices[slice].ds_openmask;
                                if (openmask &&
                                    (slice != WHOLE_DISK_SLICE || 
                                     openmask & ~(1 << RAW_PART))) {
                                        return (EBUSY);
                                }
                        }
                }

                /*
                 * Temporarily forget the current slices struct and read
                 * the current one.
                 *
                 * NOTE:
                 *
                 * XXX should wait for current accesses on this disk to
                 * complete, then lock out future accesses and opens.
                 */
                *sspp = NULL;
                lp = kmalloc(sizeof *lp, M_DEVBUF, M_WAITOK);
                *lp = *ssp->dss_slices[WHOLE_DISK_SLICE].ds_label;
                error = dsopen(dev, S_IFCHR, ssp->dss_oflags, sspp, info);
                if (error != 0) {
                        kfree(lp, M_DEVBUF);
                        *sspp = ssp;
                        return (error);
                }

                /*
                 * Reopen everything.  This is a no-op except in the "force"
                 * case and when the raw bdev and cdev are both open.  Abort
                 * if anything fails.
                 */
                for (slice = 0; slice < ssp->dss_nslices; slice++) {
                        for (openmask = ssp->dss_slices[slice].ds_openmask,
                             part = 0; openmask; openmask >>= 1, part++) {
                                if (!(openmask & 1))
                                        continue;
                                error = dsopen(dkmodslice(dkmodpart(dev, part),
                                                          slice),
                                               S_IFCHR, ssp->dss_oflags, sspp,
                                               info);
                                if (error != 0) {
                                        kfree(lp, M_DEVBUF);
                                        *sspp = ssp;
                                        return (EBUSY);
                                }
                        }
                }

                kfree(lp, M_DEVBUF);
                dsgone(&ssp);
                return (0);

        case DIOCWDINFO:
                error = dsioctl(dev, DIOCSDINFO, data, flags, &ssp, info);
                if (error != 0)
                        return (error);
                /*
                 * XXX this used to hack on dk_openpart to fake opening
                 * partition 0 in case that is used instead of dkpart(dev).
                 */
                old_wlabel = sp->ds_wlabel;
                set_ds_wlabel(ssp, slice, TRUE);
                error = writedisklabel(dev, sp->ds_label);
                /* XXX should invalidate in-core label if write failed. */
                set_ds_wlabel(ssp, slice, old_wlabel);
                return (error);

        case DIOCWLABEL:
                if (slice == WHOLE_DISK_SLICE)
                        return (ENODEV);
                if (!(flags & FWRITE))
                        return (EBADF);
                set_ds_wlabel(ssp, slice, *(int *)data != 0);
                return (0);

        default:
                return (ENOIOCTL);
        }
}

/*
 * Chain the bio_done.  b_cmd remains valid through such chaining.
 */
static void
dsiodone(struct bio *bio)
{
        struct buf *bp = bio->bio_buf;
        char *msg;

        if (bp->b_cmd != BUF_CMD_READ
            || (!(bp->b_flags & B_ERROR) && bp->b_error == 0)) {
                msg = fixlabel(NULL, bio->bio_caller_info1.ptr,
                               (struct disklabel *)
                               (bp->b_data + (int)bio->bio_caller_info2.offset),
                               FALSE);
                if (msg != NULL)
                        kprintf("%s\n", msg);
        }
        biodone(bio->bio_prev);
}

int
dsisopen(struct diskslices *ssp)
{
        int slice;

        if (ssp == NULL)
                return (0);
        for (slice = 0; slice < ssp->dss_nslices; slice++) {
                if (ssp->dss_slices[slice].ds_openmask)
                        return (1);
        }
        return (0);
}

/*
 * Allocate a slices "struct" and initialize it to contain only an empty
 * compatibility slice (pointing to itself), a whole disk slice (covering
 * the disk as described by the label), and (nslices - BASE_SLICES) empty
 * slices beginning at BASE_SLICE.
 */
struct diskslices *
dsmakeslicestruct(int nslices, struct disk_info *info)
{
        struct diskslice *sp;
        struct diskslices *ssp;

        ssp = kmalloc(offsetof(struct diskslices, dss_slices) +
                     nslices * sizeof *sp, M_DEVBUF, M_WAITOK);
        ssp->dss_first_bsd_slice = COMPATIBILITY_SLICE;
        ssp->dss_nslices = nslices;
        ssp->dss_oflags = 0;
        ssp->dss_secmult = info->d_media_blksize / DEV_BSIZE;
        if (ssp->dss_secmult & (ssp->dss_secmult - 1))
                ssp->dss_secshift = -1;
        else
                ssp->dss_secshift = ffs(ssp->dss_secmult) - 1;
        ssp->dss_secsize = info->d_media_blksize;
        sp = &ssp->dss_slices[0];
        bzero(sp, nslices * sizeof *sp);
        sp[WHOLE_DISK_SLICE].ds_size = info->d_media_blocks;
        return (ssp);
}

char *
dsname(cdev_t dev, int unit, int slice, int part, char *partname)
{
        static char name[32];
        const char *dname;

        dname = dev_dname(dev);
        if (strlen(dname) > 16)
                dname = "nametoolong";
        ksnprintf(name, sizeof(name), "%s%d", dname, unit);
        partname[0] = '\0';
        if (slice != WHOLE_DISK_SLICE || part != RAW_PART) {
                partname[0] = 'a' + part;
                partname[1] = '\0';
                if (slice != COMPATIBILITY_SLICE) {
                        ksnprintf(name + strlen(name),
                            sizeof(name) - strlen(name), "s%d", slice - 1);
                }
        }
        return (name);
}

/*
 * This should only be called when the unit is inactive and the strategy
 * routine should not allow it to become active unless we call it.  Our
 * strategy routine must be special to allow activity.
 */
int
dsopen(cdev_t dev, int mode, u_int flags, 
        struct diskslices **sspp, struct disk_info *info)
{
        cdev_t dev1;
        int error;
        struct disklabel *lp1;
        char *msg;
        u_char mask;
        bool_t need_init;
        int part;
        char partname[2];
        int slice;
        char *sname;
        struct diskslice *sp;
        struct diskslices *ssp;
        int unit;

        dev->si_bsize_phys = info->d_media_blksize;

        unit = dkunit(dev);
        if (info->d_media_blksize % DEV_BSIZE) {
                kprintf("%s: invalid sector size %lu\n", devtoname(dev),
                    (u_long)info->d_media_blksize);
                return (EINVAL);
        }

        /*
         * Do not attempt to read the slice table or disk label when
         * accessing the raw disk.
         */
        if (dkslice(dev) == WHOLE_DISK_SLICE && dkpart(dev) == RAW_PART) {
                flags |= DSO_ONESLICE | DSO_NOLABELS;
        }

        /*
         * XXX reinitialize the slice table unless there is an open device
         * on the unit.  This should only be done if the media has changed.
         */
        ssp = *sspp;
        need_init = !dsisopen(ssp);
        if (ssp != NULL && need_init)
                dsgone(sspp);
        if (need_init) {
                /*
                 * Allocate a minimal slices "struct".  This will become
                 * the final slices "struct" if we don't want real slices
                 * or if we can't find any real slices.
                 *
                 * Then scan the disk
                 */
                *sspp = dsmakeslicestruct(BASE_SLICE, info);

                if (!(flags & DSO_ONESLICE)) {
                        TRACE(("mbrinit\n"));
                        error = mbrinit(dev, info, sspp);
                        if (error != 0) {
                                dsgone(sspp);
                                return (error);
                        }
                }
                ssp = *sspp;
                ssp->dss_oflags = flags;

                /*
                 * If there are no real slices, then make the compatiblity
                 * slice cover the whole disk.
                 *
                 * no sectors are reserved for the platform (ds_skip_platform
                 * will be 0) in this case.  This means that if a disklabel
                 * is installed it will be directly installed in sector 0.
                 */
                if (ssp->dss_nslices == BASE_SLICE) {
                        ssp->dss_slices[COMPATIBILITY_SLICE].ds_size
                                = info->d_media_blocks;
                }

                /*
                 * Point the compatibility slice at the BSD slice, if any. 
                 */
                for (slice = BASE_SLICE; slice < ssp->dss_nslices; slice++) {
                        sp = &ssp->dss_slices[slice];
                        if (sp->ds_type == DOSPTYP_386BSD /* XXX */) {
                                struct diskslice *csp;

                                csp = &ssp->dss_slices[COMPATIBILITY_SLICE];
                                ssp->dss_first_bsd_slice = slice;
                                csp->ds_offset = sp->ds_offset;
                                csp->ds_size = sp->ds_size;
                                csp->ds_type = sp->ds_type;
                                csp->ds_skip_platform = sp->ds_skip_platform;
                                csp->ds_skip_bsdlabel = sp->ds_skip_bsdlabel;
                                break;
                        }
                }

                /*
                 * By definition accesses via the whole-disk device do not
                 * specify any reserved areas.  The whole disk may be read
                 * or written by the whole-disk device.
                 *
                 * XXX do not set a label for the whole disk slice, the
                 * code should be able to operate without one once we
                 * fix the virgin label code.
                 */
                sp = &ssp->dss_slices[WHOLE_DISK_SLICE];
                sp->ds_label = clone_label(info, NULL);
                sp->ds_wlabel = TRUE;
                sp->ds_skip_platform = 0;
                sp->ds_skip_bsdlabel = 0;
        }

        /*
         * Initialize secondary info for all slices.  It is needed for more
         * than the current slice in the DEVFS case.  XXX DEVFS is no more.
         *
         * Attempt to read the disklabel for each slice, creating a virgin
         * label if a slice does not have one.
         */
        for (slice = 0; slice < ssp->dss_nslices; slice++) {
                sp = &ssp->dss_slices[slice];
                if (sp->ds_label != NULL)
                        continue;
                dev1 = dkmodslice(dkmodpart(dev, RAW_PART), slice);
                sname = dsname(dev, unit, slice, RAW_PART, partname);
                /*
                 * XXX this should probably only be done for the need_init
                 * case, but there may be a problem with DIOCSYNCSLICEINFO.
                 */
                set_ds_wlabel(ssp, slice, TRUE);        /* XXX invert */
                lp1 = clone_label(info, sp);
                TRACE(("readdisklabel\n"));
                if (flags & DSO_NOLABELS) {
                        msg = NULL;
                } else {
                        msg = readdisklabel(dev1, lp1);

                        /*
                         * readdisklabel() returns NULL for success, and an
                         * error string for failure.
                         *
                         * If there isn't a label on the disk, and if the
                         * DSO_COMPATLABEL is set, we want to use the
                         * faked-up label provided by the caller.
                         *
                         * So we set msg to NULL to indicate that there is
                         * no failure (since we have a faked-up label),
                         * free lp1, and then clone it again from lp.
                         * (In case readdisklabel() modified lp1.)
                         */
                        if (msg != NULL && (flags & DSO_COMPATLABEL)) {
                                msg = NULL;
                                kfree(lp1, M_DEVBUF);
                                lp1 = clone_label(info, sp);
                        }
                }
                if (msg == NULL)
                        msg = fixlabel(sname, sp, lp1, FALSE);
                if (msg == NULL && lp1->d_secsize != ssp->dss_secsize)
                        msg = "inconsistent sector size";
                if (msg != NULL) {
                        if (sp->ds_type == DOSPTYP_386BSD /* XXX */)
                                log(LOG_WARNING, "%s: cannot find label (%s)\n",
                                    sname, msg);
                        kfree(lp1, M_DEVBUF);
                        continue;
                }
                set_ds_label(ssp, slice, lp1);
                set_ds_wlabel(ssp, slice, FALSE);
        }

        slice = dkslice(dev);
        if (slice >= ssp->dss_nslices)
                return (ENXIO);
        sp = &ssp->dss_slices[slice];
        part = dkpart(dev);
        if (part != RAW_PART
            && (sp->ds_label == NULL || part >= sp->ds_label->d_npartitions))
                return (EINVAL);        /* XXX needs translation */
        mask = 1 << part;
        sp->ds_openmask |= mask;
        return (0);
}

int64_t
dssize(cdev_t dev, struct diskslices **sspp)
{
        struct disklabel *lp;
        int part;
        int slice;
        struct diskslices *ssp;

        slice = dkslice(dev);
        part = dkpart(dev);
        ssp = *sspp;
        if (ssp == NULL || slice >= ssp->dss_nslices
            || !(ssp->dss_slices[slice].ds_openmask & (1 << part))) {
                if (dev_dopen(dev, FREAD, S_IFCHR, proc0.p_ucred) != 0)
                        return (-1);
                dev_dclose(dev, FREAD, S_IFCHR);
                ssp = *sspp;
        }
        lp = ssp->dss_slices[slice].ds_label;
        if (lp == NULL)
                return (-1);
        return ((int64_t)lp->d_partitions[part].p_size);
}

static void
free_ds_label(struct diskslices *ssp, int slice)
{
        struct disklabel *lp;
        struct diskslice *sp;

        sp = &ssp->dss_slices[slice];
        lp = sp->ds_label;
        if (lp == NULL)
                return;
        kfree(lp, M_DEVBUF);
        set_ds_label(ssp, slice, (struct disklabel *)NULL);
}

static char *
fixlabel(char *sname, struct diskslice *sp, struct disklabel *lp, int writeflag)
{
        u_int64_t start;
        u_int64_t end;
        u_int64_t offset;
        int part;
        struct partition *pp;
        bool_t warned;

        /* These errors "can't happen" so don't bother reporting details. */
        if (lp->d_magic != DISKMAGIC || lp->d_magic2 != DISKMAGIC)
                return ("fixlabel: invalid magic");
        if (dkcksum(lp) != 0)
                return ("fixlabel: invalid checksum");

        pp = &lp->d_partitions[RAW_PART];
        if (writeflag) {
                start = 0;
                offset = sp->ds_offset;
        } else {
                start = sp->ds_offset;
                offset = -sp->ds_offset;
        }
        if (pp->p_offset != start) {
                if (sname != NULL) {
                        kprintf(
"%s: rejecting BSD label: raw partition offset != slice offset\n",
                               sname);
                        slice_info(sname, sp);
                        partition_info(sname, RAW_PART, pp);
                }
                return ("fixlabel: raw partition offset != slice offset");
        }
        if (pp->p_size != sp->ds_size) {
                if (sname != NULL) {
                        kprintf("%s: raw partition size != slice size\n", sname);
                        slice_info(sname, sp);
                        partition_info(sname, RAW_PART, pp);
                }
                if (pp->p_size > sp->ds_size) {
                        if (sname == NULL)
                                return ("fixlabel: raw partition size > slice size");
                        kprintf("%s: truncating raw partition\n", sname);
                        pp->p_size = sp->ds_size;
                }
        }
        end = start + sp->ds_size;
        if (start > end)
                return ("fixlabel: slice wraps");
        if (lp->d_secpercyl <= 0)
                return ("fixlabel: d_secpercyl <= 0");
        pp -= RAW_PART;
        warned = FALSE;
        for (part = 0; part < lp->d_npartitions; part++, pp++) {
                if (pp->p_offset != 0 || pp->p_size != 0) {
                        if (pp->p_offset < start
                            || pp->p_offset + pp->p_size > end
                            || pp->p_offset + pp->p_size < pp->p_offset) {
                                if (sname != NULL) {
                                        kprintf(
"%s: rejecting partition in BSD label: it isn't entirely within the slice\n",
                                               sname);
                                        if (!warned) {
                                                slice_info(sname, sp);
                                                warned = TRUE;
                                        }
                                        partition_info(sname, part, pp);
                                }
                                /* XXX else silently discard junk. */
                                bzero(pp, sizeof *pp);
                        } else
                                pp->p_offset += offset;
                }
        }
        lp->d_ncylinders = sp->ds_size / lp->d_secpercyl;
        lp->d_secperunit = sp->ds_size;
        lp->d_checksum = 0;
        lp->d_checksum = dkcksum(lp);
        return (NULL);
}

static void
partition_info(char *sname, int part, struct partition *pp)
{
        kprintf("%s%c: start %lu, end %lu, size %lu\n", sname, 'a' + part,
               (u_long)pp->p_offset, (u_long)(pp->p_offset + pp->p_size - 1),
               (u_long)pp->p_size);
}

static void
slice_info(char *sname, struct diskslice *sp)
{
        kprintf("%s: start %llu, end %llu, size %llu\n", sname,
               sp->ds_offset, sp->ds_offset + sp->ds_size - 1, sp->ds_size);
}

static void
set_ds_label(struct diskslices *ssp, int slice, struct disklabel *lp)
{
        struct diskslice *sp1 = &ssp->dss_slices[slice];
        struct diskslice *sp2;

        if (slice == COMPATIBILITY_SLICE)
                sp2 = &ssp->dss_slices[ssp->dss_first_bsd_slice];
        else if (slice == ssp->dss_first_bsd_slice)
                sp2 = &ssp->dss_slices[COMPATIBILITY_SLICE];
        else
                sp2 = NULL;
        sp1->ds_label = lp;
        if (sp2)
                sp2->ds_label = lp;

        /*
         * If the slice is not the whole-disk slice, setup the reserved
         * area(s).
         *
         * The reserved area for the original bsd disklabel, inclusive of
         * the label and space for boot2, is 15 sectors.  If you've
         * noticed people traditionally skipping 16 sectors its because
         * the sector numbers start at the beginning of the slice rather
         * then the beginning of the disklabel and traditional dos slices
         * reserve a sector at the beginning for the boot code.
         *
         * NOTE! With the traditional bsdlabel, the first N bytes of boot2
         * overlap with the disklabel.  The disklabel program checks that
         * they are 0.
         */
        if (slice != WHOLE_DISK_SLICE) {
                sp1->ds_skip_bsdlabel = sp1->ds_skip_platform + 15;
                if (sp2)
                        sp2->ds_skip_bsdlabel = sp1->ds_skip_bsdlabel;
        }
}

static void
set_ds_wlabel(struct diskslices *ssp, int slice, int wlabel)
{
        ssp->dss_slices[slice].ds_wlabel = wlabel;
        if (slice == COMPATIBILITY_SLICE)
                ssp->dss_slices[ssp->dss_first_bsd_slice].ds_wlabel = wlabel;
        else if (slice == ssp->dss_first_bsd_slice)
                ssp->dss_slices[COMPATIBILITY_SLICE].ds_wlabel = wlabel;
}