FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_disk.c

     /*      $NetBSD: subr_disk.c,v 1.134 2022/03/28 12:33:59 riastradh Exp $        */
     
     /*-
      * Copyright (c) 1996, 1997, 1999, 2000, 2009 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
      * NASA Ames Research Center.
     *
     * 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.
     *
     * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
     */
    
    /*
     * Copyright (c) 1982, 1986, 1988, 1993
     *      The Regents of the University of California.  All rights reserved.
     * (c) UNIX System Laboratories, Inc.
     * All or some portions of this file are derived from material licensed
     * to the University of California by American Telephone and Telegraph
     * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     * the permission of UNIX System Laboratories, Inc.
     *
     * 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 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.
     *
     *      @(#)ufs_disksubr.c      8.5 (Berkeley) 1/21/94
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: subr_disk.c,v 1.134 2022/03/28 12:33:59 riastradh Exp $");
    
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/kmem.h>
    #include <sys/buf.h>
    #include <sys/fcntl.h>
    #include <sys/syslog.h>
    #include <sys/disklabel.h>
    #include <sys/disk.h>
    #include <sys/sysctl.h>
    #include <lib/libkern/libkern.h>
    
    /*
     * Disk error is the preface to plaintive error messages
     * about failing disk transfers.  It prints messages of the form
    
    hp0g: hard error reading fsbn 12345 of 12344-12347 (hp0 bn %d cn %d tn %d sn %d)
    
     * if the offset of the error in the transfer and a disk label
     * are both available.  blkdone should be -1 if the position of the error
     * is unknown; the disklabel pointer may be null from drivers that have not
     * been converted to use them.  The message is printed with printf
     * if pri is LOG_PRINTF, otherwise it uses log at the specified priority.
     * The message should be completed (with at least a newline) with printf
     * or addlog, respectively.  There is no trailing space.
     */
    #ifndef PRIdaddr
    #define PRIdaddr PRId64
    #endif
   void
   diskerr(const struct buf *bp, const char *dname, const char *what, int pri,
       int blkdone, const struct disklabel *lp)
   {
           int unit = DISKUNIT(bp->b_dev), part = DISKPART(bp->b_dev);
           void (*pr)(const char *, ...) __printflike(1, 2);
           char partname = 'a' + part;
           daddr_t sn;
   
           if (/*CONSTCOND*/0)
                   /* Compiler will error this if the format is wrong... */
                   printf("%" PRIdaddr, bp->b_blkno);
   
           if (pri != LOG_PRINTF) {
                   static const char fmt[] = "";
                   log(pri, fmt);
                   pr = addlog;
           } else
                   pr = printf;
           (*pr)("%s%d%c: %s %sing fsbn ", dname, unit, partname, what,
               bp->b_flags & B_READ ? "read" : "writ");
           sn = bp->b_blkno;
           if (bp->b_bcount <= DEV_BSIZE)
                   (*pr)("%" PRIdaddr, sn);
           else {
                   if (blkdone >= 0) {
                           sn += blkdone;
                           (*pr)("%" PRIdaddr " of ", sn);
                   }
                   (*pr)("%" PRIdaddr "-%" PRIdaddr "", bp->b_blkno,
                       bp->b_blkno + (bp->b_bcount - 1) / DEV_BSIZE);
           }
           if (lp && (blkdone >= 0 || bp->b_bcount <= lp->d_secsize)) {
                   sn += lp->d_partitions[part].p_offset;
                   (*pr)(" (%s%d bn %" PRIdaddr "; cn %" PRIdaddr "",
                       dname, unit, sn, sn / lp->d_secpercyl);
                   sn %= lp->d_secpercyl;
                   (*pr)(" tn %" PRIdaddr " sn %" PRIdaddr ")",
                       sn / lp->d_nsectors, sn % lp->d_nsectors);
           }
   }
   
   /*
    * Searches the iostatlist for the disk corresponding to the
    * name provided.
    */
   struct disk *
   disk_find(const char *name)
   {
           struct io_stats *stat;
   
           stat = iostat_find(name);
   
           if ((stat != NULL) && (stat->io_type == IOSTAT_DISK))
                   return stat->io_parent;
   
           return (NULL);
   }
   
   void
   disk_init(struct disk *diskp, const char *name, const struct dkdriver *driver)
   {
           u_int blocksize = DEV_BSIZE;
   
           /*
            * Initialize the wedge-related locks and other fields.
            */
           mutex_init(&diskp->dk_rawlock, MUTEX_DEFAULT, IPL_NONE);
           mutex_init(&diskp->dk_openlock, MUTEX_DEFAULT, IPL_NONE);
           LIST_INIT(&diskp->dk_wedges);
           diskp->dk_nwedges = 0;
           diskp->dk_labelsector = LABELSECTOR;
           diskp->dk_blkshift = DK_BSIZE2BLKSHIFT(blocksize);
           diskp->dk_byteshift = DK_BSIZE2BYTESHIFT(blocksize);
           diskp->dk_name = name;
           diskp->dk_driver = driver;
   }
   
   /*
    * Rename a disk.
    */
   void
   disk_rename(struct disk *diskp, const char *name)
   {
   
           diskp->dk_name = name;
           iostat_rename(diskp->dk_stats, diskp->dk_name);
   }
   
   /*
    * Attach a disk.
    */
   void
   disk_attach(struct disk *diskp)
   {
   
           /*
            * Allocate and initialize the disklabel structures.
            */
           diskp->dk_label = kmem_zalloc(sizeof(struct disklabel), KM_SLEEP);
           diskp->dk_cpulabel = kmem_zalloc(sizeof(struct cpu_disklabel),
               KM_SLEEP);
   
           /*
            * Set up the stats collection.
            */
           diskp->dk_stats = iostat_alloc(IOSTAT_DISK, diskp, diskp->dk_name);
   }
   
   int
   disk_begindetach(struct disk *dk, int (*lastclose)(device_t),
       device_t self, int flags)
   {
           int rc;
   
           rc = 0;
           mutex_enter(&dk->dk_openlock);
           if (dk->dk_openmask == 0)
                   ;       /* nothing to do */
           else if ((flags & DETACH_FORCE) == 0)
                   rc = EBUSY;
           else if (lastclose != NULL)
                   rc = (*lastclose)(self);
           mutex_exit(&dk->dk_openlock);
   
           return rc;
   }
   
   /*
    * Detach a disk.
    */
   void
   disk_detach(struct disk *diskp)
   {
   
           /*
            * Remove from the drivelist.
            */
           iostat_free(diskp->dk_stats);
   
           /*
            * Release the disk-info dictionary.
            */
           if (diskp->dk_info) {
                   prop_object_release(diskp->dk_info);
                   diskp->dk_info = NULL;
           }
   
           /*
            * Free the space used by the disklabel structures.
            */
           kmem_free(diskp->dk_label, sizeof(*diskp->dk_label));
           kmem_free(diskp->dk_cpulabel, sizeof(*diskp->dk_cpulabel));
   }
   
   void
   disk_destroy(struct disk *diskp)
   {
   
           mutex_destroy(&diskp->dk_openlock);
           mutex_destroy(&diskp->dk_rawlock);
   }
   
   /*
    * Mark the disk as having work queued for metrics collection.
    */
   void
   disk_wait(struct disk *diskp)
   {
   
           iostat_wait(diskp->dk_stats);
   }
   
   /*
    * Mark the disk as busy for metrics collection.
    */
   void
   disk_busy(struct disk *diskp)
   {
   
           iostat_busy(diskp->dk_stats);
   }
   
   /*
    * Finished disk operations, gather metrics.
    */
   void
   disk_unbusy(struct disk *diskp, long bcount, int read)
   {
   
           iostat_unbusy(diskp->dk_stats, bcount, read);
   }
   
   /*
    * Return true if disk has an I/O operation in flight.
    */
   bool
   disk_isbusy(struct disk *diskp)
   {
   
           return iostat_isbusy(diskp->dk_stats);
   }
   
   /*
    * Bounds checking against the media size, used for the raw partition.
    * secsize, mediasize and b_blkno must all be the same units.
    * Possibly this has to be DEV_BSIZE (512).
    */
   int
   bounds_check_with_mediasize(struct buf *bp, int secsize, uint64_t mediasize)
   {
           int64_t sz;
   
           if (bp->b_blkno < 0) {
                   /* Reject negative offsets immediately. */
                   bp->b_error = EINVAL;
                   return 0;
           }
   
           sz = howmany((int64_t)bp->b_bcount, secsize);
   
           /*
            * bp->b_bcount is a 32-bit value, and we rejected a negative
            * bp->b_blkno already, so "bp->b_blkno + sz" cannot overflow.
            */
   
           if (bp->b_blkno + sz > mediasize) {
                   sz = mediasize - bp->b_blkno;
                   if (sz == 0) {
                           /* If exactly at end of disk, return EOF. */
                           bp->b_resid = bp->b_bcount;
                           return 0;
                   }
                   if (sz < 0) {
                           /* If past end of disk, return EINVAL. */
                           bp->b_error = EINVAL;
                           return 0;
                   }
                   /* Otherwise, truncate request. */
                   bp->b_bcount = sz * secsize;
           }
   
           return 1;
   }
   
   /*
    * 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.
    */
   int
   bounds_check_with_label(struct disk *dk, struct buf *bp, int wlabel)
   {
           struct disklabel *lp = dk->dk_label;
           struct partition *p = lp->d_partitions + DISKPART(bp->b_dev);
           uint64_t p_size, p_offset, labelsector;
           int64_t sz;
   
           if (bp->b_blkno < 0) {
                   /* Reject negative offsets immediately. */
                   bp->b_error = EINVAL;
                   return -1;
           }
   
           /* Protect against division by zero. XXX: Should never happen?!?! */
           if ((lp->d_secsize / DEV_BSIZE) == 0 || lp->d_secpercyl == 0) {
                   bp->b_error = EINVAL;
                   return -1;
           }
   
           p_size = (uint64_t)p->p_size << dk->dk_blkshift;
           p_offset = (uint64_t)p->p_offset << dk->dk_blkshift;
   #if RAW_PART == 3
           labelsector = lp->d_partitions[2].p_offset;
   #else
           labelsector = lp->d_partitions[RAW_PART].p_offset;
   #endif
           labelsector = (labelsector + dk->dk_labelsector) << dk->dk_blkshift;
   
           sz = howmany((int64_t)bp->b_bcount, DEV_BSIZE);
   
           /*
            * bp->b_bcount is a 32-bit value, and we rejected a negative
            * bp->b_blkno already, so "bp->b_blkno + sz" cannot overflow.
            */
   
           if (bp->b_blkno + sz > p_size) {
                   sz = p_size - bp->b_blkno;
                   if (sz == 0) {
                           /* If exactly at end of disk, return EOF. */
                           bp->b_resid = bp->b_bcount;
                           return 0;
                   }
                   if (sz < 0) {
                           /* If past end of disk, return EINVAL. */
                           bp->b_error = EINVAL;
                           return -1;
                   }
                   /* Otherwise, truncate request. */
                   bp->b_bcount = sz << DEV_BSHIFT;
           }
   
           /* Overwriting disk label? */
           if (bp->b_blkno + p_offset <= labelsector &&
               bp->b_blkno + p_offset + sz > labelsector &&
               (bp->b_flags & B_READ) == 0 && !wlabel) {
                   bp->b_error = EROFS;
                   return -1;
           }
   
           /* calculate cylinder for disksort to order transfers with */
           bp->b_cylinder = (bp->b_blkno + p->p_offset) /
               (lp->d_secsize / DEV_BSIZE) / lp->d_secpercyl;
           return 1;
   }
   
   int
   disk_read_sectors(void (*strat)(struct buf *), const struct disklabel *lp,
       struct buf *bp, unsigned int sector, int count)
   {
   
           if ((lp->d_secsize / DEV_BSIZE) == 0 || lp->d_secpercyl == 0)
                   return EINVAL;
   
           bp->b_blkno = btodb((off_t)sector * lp->d_secsize);
           bp->b_bcount = count * lp->d_secsize;
           bp->b_flags = (bp->b_flags & ~B_WRITE) | B_READ;
           bp->b_oflags &= ~BO_DONE;
           bp->b_cylinder = sector / lp->d_secpercyl;
           (*strat)(bp);
           return biowait(bp);
   }
   
   const char *
   convertdisklabel(struct disklabel *lp, void (*strat)(struct buf *),
       struct buf *bp, uint32_t secperunit)
   {
           struct partition rp, *altp, *p;
           int geom_ok;
           const char *str;
   
           memset(&rp, 0, sizeof(rp));
           rp.p_size = secperunit;
           rp.p_fstype = FS_UNUSED;
   
           /* If we can seek to d_secperunit - 1, believe the disk geometry. */
           if (secperunit != 0 &&
               disk_read_sectors(strat, lp, bp, secperunit - 1, 1) == 0)
                   geom_ok = 1;
           else
                   geom_ok = 0;
   
   #if 0
           printf("%s: secperunit (%" PRIu32 ") %s\n", __func__,
               secperunit, geom_ok ? "ok" : "not ok");
   #endif
   
           p = &lp->d_partitions[RAW_PART];
           if (RAW_PART == 'c' - 'a')
                   altp = &lp->d_partitions['d' - 'a'];
           else
                   altp = &lp->d_partitions['c' - 'a'];
   
           if (lp->d_npartitions > RAW_PART && p->p_offset == 0 && p->p_size != 0)
                   return NULL;    /* already a raw partition */
           else if (lp->d_npartitions > MAX('c', 'd') - 'a' &&
                    altp->p_offset == 0 && altp->p_size != 0) {
                   /* alternate partition ('c' or 'd') is suitable for raw slot,
                    * swap with 'd' or 'c'.
                    */
                   rp = *p;
                   *p = *altp;
                   *altp = rp;
                   return NULL;
           } else if (lp->d_npartitions <= RAW_PART &&
                      lp->d_npartitions > 'c' - 'a') {
                   /* No raw partition is present, but the alternate is present.
                    * Copy alternate to raw partition.
                    */
                   lp->d_npartitions = RAW_PART + 1;
                   *p = *altp;
                   return NULL;
           } else if (!geom_ok)
                   str = "no raw partition and disk reports bad geometry";
           else if (lp->d_npartitions <= RAW_PART) {
                   memset(&lp->d_partitions[lp->d_npartitions], 0,
                       sizeof(struct partition) * (RAW_PART - lp->d_npartitions));
                   *p = rp;
                   lp->d_npartitions = RAW_PART + 1;
                   return NULL;
           } else if (lp->d_npartitions < MAXPARTITIONS) {
                   memmove(p + 1, p,
                       sizeof(struct partition) * (lp->d_npartitions - RAW_PART));
                   *p = rp;
                   lp->d_npartitions++;
                   return NULL;
           } else
                   str = "no raw partition and partition table is full";
   #ifdef DIAGNOSTIC
           printf("Bad partition: %s\n", str);
           printf("type = %u, subtype = %u, typename = %s\n",
               lp->d_type, lp->d_subtype, lp->d_typename);
           printf("secsize = %u, nsectors = %u, ntracks = %u\n",
               lp->d_secsize, lp->d_nsectors, lp->d_ntracks);
           printf("ncylinders = %u, secpercyl = %u, secperunit = %u\n",
               lp->d_ncylinders, lp->d_secpercyl, lp->d_secperunit);
           printf("npartitions = %u\n", lp->d_npartitions);
   
           for (size_t i = 0; i < MIN(lp->d_npartitions, MAXPARTITIONS); i++) {
                   p = &lp->d_partitions[i];
                   printf("\t%c: offset = %u size = %u fstype = %u\n",
                       (char)(i + 'a'), p->p_offset, p->p_size, p->p_fstype);
           }
   #endif                  
           return str;
   }
   
   /*
    * disk_ioctl --
    *      Generic disk ioctl handling.
    */
   int
   disk_ioctl(struct disk *dk, dev_t dev, u_long cmd, void *data, int flag,
       struct lwp *l)
   {
           struct dkwedge_info *dkw;
           struct partinfo *pi;
           struct partition *dp;
   #ifdef __HAVE_OLD_DISKLABEL
           struct disklabel newlabel;
   #endif
   
           switch (cmd) {
           case DIOCGDISKINFO:
                   if (dk->dk_info == NULL)
                           return ENOTSUP;
                   return prop_dictionary_copyout_ioctl(data, cmd, dk->dk_info);
   
           case DIOCGSECTORSIZE:
                   *(u_int *)data = dk->dk_geom.dg_secsize;
                   return 0;
   
           case DIOCGMEDIASIZE:
                   *(off_t *)data = (off_t)dk->dk_geom.dg_secsize *
                       dk->dk_geom.dg_secperunit;
                   return 0;
           default:
                   break;
           }
   
           if (dev == NODEV)
                   return EPASSTHROUGH;
   
           /* The following should be moved to dk_ioctl */
           switch (cmd) {
           case DIOCGDINFO:
                   if (dk->dk_label == NULL)
                           return EBUSY;
                   memcpy(data, dk->dk_label, sizeof (*dk->dk_label));
                   return 0;
   
   #ifdef __HAVE_OLD_DISKLABEL
           case ODIOCGDINFO:
                   if (dk->dk_label == NULL)
                           return EBUSY;
                   memcpy(&newlabel, dk->dk_label, sizeof(newlabel));
                   if (newlabel.d_npartitions > OLDMAXPARTITIONS)
                           return ENOTTY;
                   memcpy(data, &newlabel, sizeof(struct olddisklabel));
                   return 0;
   #endif
   
           case DIOCGPARTINFO:
                   pi = data;
                   memset(pi, 0, sizeof(*pi));
                   pi->pi_secsize = dk->dk_geom.dg_secsize;
                   pi->pi_bsize = MAX(BLKDEV_IOSIZE, pi->pi_secsize);
   
                   if (DISKPART(dev) == RAW_PART) {
                           pi->pi_size = dk->dk_geom.dg_secperunit;
                           return 0;
                   }
   
                   if (dk->dk_label == NULL)
                           return EBUSY;
   
                   dp = &dk->dk_label->d_partitions[DISKPART(dev)];
                   pi->pi_offset = dp->p_offset;
                   pi->pi_size = dp->p_size;
   
                   pi->pi_fstype = dp->p_fstype;
                   pi->pi_frag = dp->p_frag;
                   pi->pi_fsize = dp->p_fsize;
                   pi->pi_cpg = dp->p_cpg;
                   
                   /*
                    * dholland 20130616: XXX this logic should not be
                    * here. It is here because the old buffer cache
                    * demands that all accesses to the same blocks need
                    * to be the same size; but it only works for FFS and
                    * nowadays I think it'll fail silently if the size
                    * info in the disklabel is wrong. (Or missing.) The
                    * buffer cache needs to be smarter; or failing that
                    * we need a reliable way here to get the right block
                    * size; or a reliable way to guarantee that (a) the
                    * fs is not mounted when we get here and (b) any
                    * buffers generated here will get purged when the fs
                    * does get mounted.
                    */
                   if (dp->p_fstype == FS_BSDFFS &&
                       dp->p_frag != 0 && dp->p_fsize != 0)
                           pi->pi_bsize = dp->p_frag * dp->p_fsize;
                   return 0;
   
           case DIOCAWEDGE:
                   if ((flag & FWRITE) == 0)
                           return EBADF;
   
                   dkw = data;
                   strlcpy(dkw->dkw_parent, dk->dk_name, sizeof(dkw->dkw_parent));
                   return dkwedge_add(dkw);
   
           case DIOCDWEDGE:
                   if ((flag & FWRITE) == 0)
                           return EBADF;
   
                   dkw = data;
                   strlcpy(dkw->dkw_parent, dk->dk_name, sizeof(dkw->dkw_parent));
                   return dkwedge_del(dkw);
   
           case DIOCLWEDGES:
                   return dkwedge_list(dk, data, l);
   
           case DIOCMWEDGES:
                   if ((flag & FWRITE) == 0)
                           return EBADF;
   
                   dkwedge_discover(dk);
                   return 0;
   
           case DIOCRMWEDGES:
                   if ((flag & FWRITE) == 0)
                           return EBADF;
   
                   dkwedge_delall(dk);
                   return 0;
   
           default:
                   return EPASSTHROUGH;
           }
   }
   
   void
   disk_set_info(device_t dev, struct disk *dk, const char *type)
   {
           struct disk_geom *dg = &dk->dk_geom;
   
           if (dg->dg_secsize == 0) {
   #ifdef DIAGNOSTIC
                   printf("%s: fixing 0 sector size\n", dk->dk_name);
   #endif
                   dg->dg_secsize = DEV_BSIZE;
           }
   
           dk->dk_blkshift = DK_BSIZE2BLKSHIFT(dg->dg_secsize);
           dk->dk_byteshift = DK_BSIZE2BYTESHIFT(dg->dg_secsize);
   
           if (dg->dg_secperunit == 0) {
   #ifdef DIAGNOSTIC
                   if (dg->dg_ncylinders == 0) {
                           printf("%s: secperunit and ncylinders are zero\n",
                               dk->dk_name);
                   }
                   if (dg->dg_nsectors == 0 || dg->dg_ntracks == 0) {
                           printf("%s: secperunit and (sectors or tracks) "
                               "are zero\n", dk->dk_name);
                   }
   #endif
                   dg->dg_secperunit = (int64_t) dg->dg_nsectors *
                       dg->dg_ntracks * dg->dg_ncylinders;
           }
   
           if (dg->dg_ncylinders == 0) {
                   if (dg->dg_ntracks && dg->dg_nsectors)
                           dg->dg_ncylinders = dg->dg_secperunit /
                               (dg->dg_ntracks * dg->dg_nsectors);
           }
   
           prop_dictionary_t disk_info, odisk_info, geom;
   
           disk_info = prop_dictionary_create();
           geom = prop_dictionary_create();
   
           prop_dictionary_set_uint64(geom, "sectors-per-unit",
               dg->dg_secperunit);
   
           prop_dictionary_set_uint32(geom, "sector-size", dg->dg_secsize);
   
           if (dg->dg_nsectors)
                   prop_dictionary_set_uint16(geom, "sectors-per-track",
                       dg->dg_nsectors);
   
           if (dg->dg_ntracks)
                   prop_dictionary_set_uint16(geom, "tracks-per-cylinder",
                       dg->dg_ntracks);
   
           if (dg->dg_ncylinders)
                   prop_dictionary_set_uint64(geom, "cylinders-per-unit",
                       dg->dg_ncylinders);
   
           prop_dictionary_set(disk_info, "geometry", geom);
   
           if (type)
                   prop_dictionary_set_string_nocopy(disk_info, "type", type);
   
           prop_object_release(geom);
   
           odisk_info = dk->dk_info;
           dk->dk_info = disk_info;
   
           if (dev)
                   prop_dictionary_set(device_properties(dev), "disk-info",
                       disk_info);
   
           /*
            * Don't release disk_info here; we keep a reference to it.
            * disk_detach() will release it when we go away.
            */
           if (odisk_info)
                   prop_object_release(odisk_info);
   }
   
   int
   disklabel_dev_unit(dev_t dev)
   {
   
           return DISKUNIT(dev);
   }

Cache object: b192cfda00fe2ebddaeb5dfa5defd790