The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/geom/geom_bsd.c

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    1 /*-
    2  * Copyright (c) 2002 Poul-Henning Kamp
    3  * Copyright (c) 2002 Networks Associates Technology, Inc.
    4  * All rights reserved.
    5  *
    6  * This software was developed for the FreeBSD Project by Poul-Henning Kamp
    7  * and NAI Labs, the Security Research Division of Network Associates, Inc.
    8  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
    9  * DARPA CHATS research program.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 3. The names of the authors may not be used to endorse or promote
   20  *    products derived from this software without specific prior written
   21  *    permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   33  * SUCH DAMAGE.
   34  */
   35 
   36 /*
   37  * This is the method for dealing with BSD disklabels.  It has been
   38  * extensively (by my standards at least) commented, in the vain hope that
   39  * it will serve as the source in future copy&paste operations.
   40  */
   41 
   42 #include <sys/cdefs.h>
   43 __FBSDID("$FreeBSD$");
   44 
   45 #include <sys/param.h>
   46 #include <sys/endian.h>
   47 #include <sys/systm.h>
   48 #include <sys/kernel.h>
   49 #include <sys/fcntl.h>
   50 #include <sys/conf.h>
   51 #include <sys/bio.h>
   52 #include <sys/malloc.h>
   53 #include <sys/lock.h>
   54 #include <sys/mutex.h>
   55 #include <sys/md5.h>
   56 #include <sys/errno.h>
   57 #include <sys/disklabel.h>
   58 #include <geom/geom.h>
   59 #include <geom/geom_slice.h>
   60 
   61 #define BSD_CLASS_NAME "BSD"
   62 
   63 #define ALPHA_LABEL_OFFSET      64
   64 
   65 #define LABELSIZE (148 + 16 * MAXPARTITIONS)
   66 
   67 static void g_bsd_hotwrite(void *arg, int flag);
   68 /*
   69  * Our private data about one instance.  All the rest is handled by the
   70  * slice code and stored in its softc, so this is just the stuff
   71  * specific to BSD disklabels.
   72  */
   73 struct g_bsd_softc {
   74         off_t   labeloffset;
   75         off_t   mbroffset;
   76         off_t   rawoffset;
   77         struct disklabel ondisk;
   78         u_char  label[LABELSIZE];
   79         u_char  labelsum[16];
   80 };
   81 
   82 /*
   83  * Modify our slicer to match proposed disklabel, if possible.
   84  * This is where we make sure we don't do something stupid.
   85  */
   86 static int
   87 g_bsd_modify(struct g_geom *gp, u_char *label)
   88 {
   89         int i, error;
   90         struct partition *ppp;
   91         struct g_slicer *gsp;
   92         struct g_consumer *cp;
   93         struct g_bsd_softc *ms;
   94         u_int secsize, u;
   95         off_t rawoffset, o;
   96         struct disklabel dl;
   97         MD5_CTX md5sum;
   98 
   99         g_topology_assert();
  100         gsp = gp->softc;
  101         ms = gsp->softc;
  102 
  103         error = bsd_disklabel_le_dec(label, &dl, MAXPARTITIONS);
  104         if (error) {
  105                 return (error);
  106         }
  107 
  108         /* Get dimensions of our device. */
  109         cp = LIST_FIRST(&gp->consumer);
  110         secsize = cp->provider->sectorsize;
  111 
  112         /* ... or a smaller sector size. */
  113         if (dl.d_secsize < secsize) {
  114                 return (EINVAL);
  115         }
  116 
  117         /* ... or a non-multiple sector size. */
  118         if (dl.d_secsize % secsize != 0) {
  119                 return (EINVAL);
  120         }
  121 
  122         /* Historical braindamage... */
  123         rawoffset = (off_t)dl.d_partitions[RAW_PART].p_offset * dl.d_secsize;
  124 
  125         for (i = 0; i < dl.d_npartitions; i++) {
  126                 ppp = &dl.d_partitions[i];
  127                 if (ppp->p_size == 0)
  128                         continue;
  129                 o = (off_t)ppp->p_offset * dl.d_secsize;
  130 
  131                 if (o < rawoffset)
  132                         rawoffset = 0;
  133         }
  134         
  135         if (rawoffset != 0 && (off_t)rawoffset != ms->mbroffset)
  136                 printf("WARNING: Expected rawoffset %jd, found %jd\n",
  137                     (intmax_t)ms->mbroffset/dl.d_secsize,
  138                     (intmax_t)rawoffset/dl.d_secsize);
  139 
  140         /* Don't munge open partitions. */
  141         for (i = 0; i < dl.d_npartitions; i++) {
  142                 ppp = &dl.d_partitions[i];
  143 
  144                 o = (off_t)ppp->p_offset * dl.d_secsize;
  145                 if (o == 0)
  146                         o = rawoffset;
  147                 error = g_slice_config(gp, i, G_SLICE_CONFIG_CHECK,
  148                     o - rawoffset,
  149                     (off_t)ppp->p_size * dl.d_secsize,
  150                      dl.d_secsize,
  151                     "%s%c", gp->name, 'a' + i);
  152                 if (error)
  153                         return (error);
  154         }
  155 
  156         /* Look good, go for it... */
  157         for (u = 0; u < gsp->nslice; u++) {
  158                 ppp = &dl.d_partitions[u];
  159                 o = (off_t)ppp->p_offset * dl.d_secsize;
  160                 if (o == 0)
  161                         o = rawoffset;
  162                 g_slice_config(gp, u, G_SLICE_CONFIG_SET,
  163                     o - rawoffset,
  164                     (off_t)ppp->p_size * dl.d_secsize,
  165                      dl.d_secsize,
  166                     "%s%c", gp->name, 'a' + u);
  167         }
  168 
  169         /* Update our softc */
  170         ms->ondisk = dl;
  171         if (label != ms->label)
  172                 bcopy(label, ms->label, LABELSIZE);
  173         ms->rawoffset = rawoffset;
  174 
  175         /*
  176          * In order to avoid recursively attaching to the same
  177          * on-disk label (it's usually visible through the 'c'
  178          * partition) we calculate an MD5 and ask if other BSD's
  179          * below us love that label.  If they do, we don't.
  180          */
  181         MD5Init(&md5sum);
  182         MD5Update(&md5sum, ms->label, sizeof(ms->label));
  183         MD5Final(ms->labelsum, &md5sum);
  184 
  185         return (0);
  186 }
  187 
  188 /*
  189  * This is an internal helper function, called multiple times from the taste
  190  * function to try to locate a disklabel on the disk.  More civilized formats
  191  * will not need this, as there is only one possible place on disk to look
  192  * for the magic spot.
  193  */
  194 
  195 static int
  196 g_bsd_try(struct g_geom *gp, struct g_slicer *gsp, struct g_consumer *cp, int secsize, struct g_bsd_softc *ms, off_t offset)
  197 {
  198         int error;
  199         u_char *buf;
  200         struct disklabel *dl;
  201         off_t secoff;
  202 
  203         /*
  204          * We need to read entire aligned sectors, and we assume that the
  205          * disklabel does not span sectors, so one sector is enough.
  206          */
  207         error = 0;
  208         secoff = offset % secsize;
  209         buf = g_read_data(cp, offset - secoff, secsize, &error);
  210         if (buf == NULL || error != 0)
  211                 return (ENOENT);
  212 
  213         /* Decode into our native format. */
  214         dl = &ms->ondisk;
  215         error = bsd_disklabel_le_dec(buf + secoff, dl, MAXPARTITIONS);
  216         if (!error)
  217                 bcopy(buf + secoff, ms->label, LABELSIZE);
  218 
  219         /* Remember to free the buffer g_read_data() gave us. */
  220         g_free(buf);
  221 
  222         ms->labeloffset = offset;
  223         return (error);
  224 }
  225 
  226 /*
  227  * This function writes the current label to disk, possibly updating
  228  * the alpha SRM checksum.
  229  */
  230 
  231 static int
  232 g_bsd_writelabel(struct g_geom *gp, u_char *bootcode)
  233 {
  234         off_t secoff;
  235         u_int secsize;
  236         struct g_consumer *cp;
  237         struct g_slicer *gsp;
  238         struct g_bsd_softc *ms;
  239         u_char *buf;
  240         uint64_t sum;
  241         int error, i;
  242 
  243         gsp = gp->softc;
  244         ms = gsp->softc;
  245         cp = LIST_FIRST(&gp->consumer);
  246         /* Get sector size, we need it to read data. */
  247         secsize = cp->provider->sectorsize;
  248         secoff = ms->labeloffset % secsize;
  249         if (bootcode == NULL) {
  250                 buf = g_read_data(cp, ms->labeloffset - secoff, secsize, &error);
  251                 if (buf == NULL || error != 0)
  252                         return (error);
  253                 bcopy(ms->label, buf + secoff, sizeof(ms->label));
  254         } else {
  255                 buf = bootcode;
  256                 bcopy(ms->label, buf + ms->labeloffset, sizeof(ms->label));
  257         }
  258         if (ms->labeloffset == ALPHA_LABEL_OFFSET) {
  259                 sum = 0;
  260                 for (i = 0; i < 63; i++)
  261                         sum += le64dec(buf + i * 8);
  262                 le64enc(buf + 504, sum);
  263         }
  264         if (bootcode == NULL) {
  265                 error = g_write_data(cp, ms->labeloffset - secoff, buf, secsize);
  266                 g_free(buf);
  267         } else {
  268                 error = g_write_data(cp, 0, bootcode, BBSIZE);
  269         }
  270         return(error);
  271 }
  272 
  273 /*
  274  * If the user tries to overwrite our disklabel through an open partition
  275  * or via a magicwrite config call, we end up here and try to prevent
  276  * footshooting as best we can.
  277  */
  278 static void
  279 g_bsd_hotwrite(void *arg, int flag)
  280 {
  281         struct bio *bp;
  282         struct g_geom *gp;
  283         struct g_slicer *gsp;
  284         struct g_slice *gsl;
  285         struct g_bsd_softc *ms;
  286         u_char *p;
  287         int error;
  288         
  289         g_topology_assert();
  290         /*
  291          * We should never get canceled, because that would amount to a removal
  292          * of the geom while there was outstanding I/O requests.
  293          */
  294         KASSERT(flag != EV_CANCEL, ("g_bsd_hotwrite cancelled"));
  295         bp = arg;
  296         gp = bp->bio_to->geom;
  297         gsp = gp->softc;
  298         ms = gsp->softc;
  299         gsl = &gsp->slices[bp->bio_to->index];
  300         p = (u_char*)bp->bio_data + ms->labeloffset 
  301             - (bp->bio_offset + gsl->offset);
  302         error = g_bsd_modify(gp, p);
  303         if (error) {
  304                 g_io_deliver(bp, EPERM);
  305                 return;
  306         }
  307         g_slice_finish_hot(bp);
  308 }
  309 
  310 /*-
  311  * This start routine is only called for non-trivial requests, all the
  312  * trivial ones are handled autonomously by the slice code.
  313  * For requests we handle here, we must call the g_io_deliver() on the
  314  * bio, and return non-zero to indicate to the slice code that we did so.
  315  * This code executes in the "DOWN" I/O path, this means:
  316  *    * No sleeping.
  317  *    * Don't grab the topology lock.
  318  *    * Don't call biowait, g_getattr(), g_setattr() or g_read_data()
  319  */
  320 static int
  321 g_bsd_ioctl(struct g_provider *pp, u_long cmd, void * data, int fflag, struct thread *td)
  322 {
  323         struct g_geom *gp;
  324         struct g_bsd_softc *ms;
  325         struct g_slicer *gsp;
  326         u_char *label;
  327         int error;
  328 
  329         gp = pp->geom;
  330         gsp = gp->softc;
  331         ms = gsp->softc;
  332 
  333         switch(cmd) {
  334         case DIOCGDINFO:
  335                 /* Return a copy of the disklabel to userland. */
  336                 bsd_disklabel_le_dec(ms->label, data, MAXPARTITIONS);
  337                 return(0);
  338         case DIOCBSDBB: {
  339                 struct g_consumer *cp;
  340                 u_char *buf;
  341                 void *p;
  342                 int error, i;
  343                 uint64_t sum;
  344 
  345                 if (!(fflag & FWRITE))
  346                         return (EPERM);
  347                 /* The disklabel to set is the ioctl argument. */
  348                 buf = g_malloc(BBSIZE, M_WAITOK);
  349                 p = *(void **)data;
  350                 error = copyin(p, buf, BBSIZE);
  351                 if (!error) {
  352                         /* XXX: Rude, but supposedly safe */
  353                         DROP_GIANT();
  354                         g_topology_lock();
  355                         /* Validate and modify our slice instance to match. */
  356                         error = g_bsd_modify(gp, buf + ms->labeloffset);
  357                         if (!error) {
  358                                 cp = LIST_FIRST(&gp->consumer);
  359                                 if (ms->labeloffset == ALPHA_LABEL_OFFSET) {
  360                                         sum = 0;
  361                                         for (i = 0; i < 63; i++)
  362                                                 sum += le64dec(buf + i * 8);
  363                                         le64enc(buf + 504, sum);
  364                                 }
  365                                 error = g_write_data(cp, 0, buf, BBSIZE);
  366                         }
  367                         g_topology_unlock();
  368                         PICKUP_GIANT();
  369                 }
  370                 g_free(buf);
  371                 return (error);
  372         }
  373         case DIOCSDINFO:
  374         case DIOCWDINFO: {
  375                 if (!(fflag & FWRITE))
  376                         return (EPERM);
  377                 label = g_malloc(LABELSIZE, M_WAITOK);
  378                 /* The disklabel to set is the ioctl argument. */
  379                 bsd_disklabel_le_enc(label, data);
  380 
  381                 DROP_GIANT();
  382                 g_topology_lock();
  383                 /* Validate and modify our slice instance to match. */
  384                 error = g_bsd_modify(gp, label);
  385                 if (error == 0 && cmd == DIOCWDINFO)
  386                         error = g_bsd_writelabel(gp, NULL);
  387                 g_topology_unlock();
  388                 PICKUP_GIANT();
  389                 g_free(label);
  390                 return(error);
  391         }
  392         default:
  393                 return (ENOIOCTL);
  394         }
  395 }
  396 
  397 static int
  398 g_bsd_start(struct bio *bp)
  399 {
  400         struct g_geom *gp;
  401         struct g_bsd_softc *ms;
  402         struct g_slicer *gsp;
  403 
  404         gp = bp->bio_to->geom;
  405         gsp = gp->softc;
  406         ms = gsp->softc;
  407         if (bp->bio_cmd == BIO_GETATTR) {
  408                 if (g_handleattr(bp, "BSD::labelsum", ms->labelsum,
  409                     sizeof(ms->labelsum)))
  410                         return (1);
  411         }
  412         return (0);
  413 }
  414 
  415 /*
  416  * Dump configuration information in XML format.
  417  * Notice that the function is called once for the geom and once for each
  418  * consumer and provider.  We let g_slice_dumpconf() do most of the work.
  419  */
  420 static void
  421 g_bsd_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp, struct g_consumer *cp, struct g_provider *pp)
  422 {
  423         struct g_bsd_softc *ms;
  424         struct g_slicer *gsp;
  425 
  426         gsp = gp->softc;
  427         ms = gsp->softc;
  428         g_slice_dumpconf(sb, indent, gp, cp, pp);
  429         if (indent != NULL && pp == NULL && cp == NULL) {
  430                 sbuf_printf(sb, "%s<labeloffset>%jd</labeloffset>\n",
  431                     indent, (intmax_t)ms->labeloffset);
  432                 sbuf_printf(sb, "%s<rawoffset>%jd</rawoffset>\n",
  433                     indent, (intmax_t)ms->rawoffset);
  434                 sbuf_printf(sb, "%s<mbroffset>%jd</mbroffset>\n",
  435                     indent, (intmax_t)ms->mbroffset);
  436         } else if (pp != NULL) {
  437                 if (indent == NULL)
  438                         sbuf_printf(sb, " ty %d",
  439                             ms->ondisk.d_partitions[pp->index].p_fstype);
  440                 else
  441                         sbuf_printf(sb, "%s<type>%d</type>\n", indent,
  442                             ms->ondisk.d_partitions[pp->index].p_fstype);
  443         }
  444 }
  445 
  446 /*
  447  * The taste function is called from the event-handler, with the topology
  448  * lock already held and a provider to examine.  The flags are unused.
  449  *
  450  * If flags == G_TF_NORMAL, the idea is to take a bite of the provider and
  451  * if we find valid, consistent magic on it, build a geom on it.
  452  * any magic bits which indicate that we should automatically put a BSD
  453  * geom on it.
  454  *
  455  * There may be cases where the operator would like to put a BSD-geom on
  456  * providers which do not meet all of the requirements.  This can be done
  457  * by instead passing the G_TF_INSIST flag, which will override these
  458  * checks.
  459  *
  460  * The final flags value is G_TF_TRANSPARENT, which instructs the method
  461  * to put a geom on top of the provider and configure it to be as transparent
  462  * as possible.  This is not really relevant to the BSD method and therefore
  463  * not implemented here.
  464  */
  465 
  466 static struct g_geom *
  467 g_bsd_taste(struct g_class *mp, struct g_provider *pp, int flags)
  468 {
  469         struct g_geom *gp;
  470         struct g_consumer *cp;
  471         int error, i;
  472         struct g_bsd_softc *ms;
  473         u_int secsize;
  474         struct g_slicer *gsp;
  475         u_char hash[16];
  476         MD5_CTX md5sum;
  477 
  478         g_trace(G_T_TOPOLOGY, "bsd_taste(%s,%s)", mp->name, pp->name);
  479         g_topology_assert();
  480 
  481         /* We don't implement transparent inserts. */
  482         if (flags == G_TF_TRANSPARENT)
  483                 return (NULL);
  484 
  485         /*
  486          * BSD labels are a subclass of the general "slicing" topology so
  487          * a lot of the work can be done by the common "slice" code.
  488          * Create a geom with space for MAXPARTITIONS providers, one consumer
  489          * and a softc structure for us.  Specify the provider to attach
  490          * the consumer to and our "start" routine for special requests.
  491          * The provider is opened with mode (1,0,0) so we can do reads
  492          * from it.
  493          */
  494         gp = g_slice_new(mp, MAXPARTITIONS, pp, &cp, &ms,
  495              sizeof(*ms), g_bsd_start);
  496         if (gp == NULL)
  497                 return (NULL);
  498 
  499         /* Get the geom_slicer softc from the geom. */
  500         gsp = gp->softc;
  501 
  502         /*
  503          * The do...while loop here allows us to have multiple escapes
  504          * using a simple "break".  This improves code clarity without
  505          * ending up in deep nesting and without using goto or come from.
  506          */
  507         do {
  508                 /*
  509                  * If the provider is an MBR we will only auto attach
  510                  * to type 165 slices in the G_TF_NORMAL case.  We will
  511                  * attach to any other type.
  512                  */
  513                 error = g_getattr("MBR::type", cp, &i);
  514                 if (!error) {
  515                         if (i != 165 && flags == G_TF_NORMAL)
  516                                 break;
  517                         error = g_getattr("MBR::offset", cp, &ms->mbroffset);
  518                         if (error)
  519                                 break;
  520                 }
  521 
  522                 /* Same thing if we are inside a PC98 */
  523                 error = g_getattr("PC98::type", cp, &i);
  524                 if (!error) {
  525                         if (i != 0xc494 && flags == G_TF_NORMAL)
  526                                 break;
  527                         error = g_getattr("PC98::offset", cp, &ms->mbroffset);
  528                         if (error)
  529                                 break;
  530                 }
  531 
  532                 /* Get sector size, we need it to read data. */
  533                 secsize = cp->provider->sectorsize;
  534                 if (secsize < 512)
  535                         break;
  536 
  537                 /* First look for a label at the start of the second sector. */
  538                 error = g_bsd_try(gp, gsp, cp, secsize, ms, secsize);
  539 
  540                 /* Next, look for alpha labels */
  541                 if (error)
  542                         error = g_bsd_try(gp, gsp, cp, secsize, ms,
  543                             ALPHA_LABEL_OFFSET);
  544 
  545                 /* If we didn't find a label, punt. */
  546                 if (error)
  547                         break;
  548 
  549                 /*
  550                  * In order to avoid recursively attaching to the same
  551                  * on-disk label (it's usually visible through the 'c'
  552                  * partition) we calculate an MD5 and ask if other BSD's
  553                  * below us love that label.  If they do, we don't.
  554                  */
  555                 MD5Init(&md5sum);
  556                 MD5Update(&md5sum, ms->label, sizeof(ms->label));
  557                 MD5Final(ms->labelsum, &md5sum);
  558 
  559                 error = g_getattr("BSD::labelsum", cp, &hash);
  560                 if (!error && !bcmp(ms->labelsum, hash, sizeof(hash)))
  561                         break;
  562 
  563                 /*
  564                  * Process the found disklabel, and modify our "slice"
  565                  * instance to match it, if possible.
  566                  */
  567                 error = g_bsd_modify(gp, ms->label);
  568         } while (0);
  569 
  570         /* Success or failure, we can close our provider now. */
  571         g_access(cp, -1, 0, 0);
  572 
  573         /* If we have configured any providers, return the new geom. */
  574         if (gsp->nprovider > 0) {
  575                 g_slice_conf_hot(gp, 0, ms->labeloffset, LABELSIZE,
  576                     G_SLICE_HOT_ALLOW, G_SLICE_HOT_DENY, G_SLICE_HOT_CALL);
  577                 gsp->hot = g_bsd_hotwrite;
  578                 return (gp);
  579         }
  580         /*
  581          * ...else push the "self-destruct" button, by spoiling our own
  582          * consumer.  This triggers a call to g_slice_spoiled which will
  583          * dismantle what was setup.
  584          */
  585         g_slice_spoiled(cp);
  586         return (NULL);
  587 }
  588 
  589 struct h0h0 {
  590         struct g_geom *gp;
  591         struct g_bsd_softc *ms;
  592         u_char *label;
  593         int error;
  594 };
  595 
  596 static void
  597 g_bsd_callconfig(void *arg, int flag)
  598 {
  599         struct h0h0 *hp;
  600 
  601         hp = arg;
  602         hp->error = g_bsd_modify(hp->gp, hp->label);
  603         if (!hp->error)
  604                 hp->error = g_bsd_writelabel(hp->gp, NULL);
  605 }
  606 
  607 /*
  608  * NB! curthread is user process which GCTL'ed.
  609  */
  610 static void
  611 g_bsd_config(struct gctl_req *req, struct g_class *mp, char const *verb)
  612 {
  613         u_char *label;
  614         int error;
  615         struct h0h0 h0h0;
  616         struct g_geom *gp;
  617         struct g_slicer *gsp;
  618         struct g_consumer *cp;
  619         struct g_bsd_softc *ms;
  620 
  621         g_topology_assert();
  622         gp = gctl_get_geom(req, mp, "geom");
  623         if (gp == NULL)
  624                 return;
  625         cp = LIST_FIRST(&gp->consumer);
  626         gsp = gp->softc;
  627         ms = gsp->softc;
  628         if (!strcmp(verb, "read mbroffset")) {
  629                 gctl_set_param(req, "mbroffset",
  630                     &ms->mbroffset, sizeof(ms->mbroffset));
  631                 return;
  632         } else if (!strcmp(verb, "write label")) {
  633                 label = gctl_get_paraml(req, "label", LABELSIZE);
  634                 if (label == NULL)
  635                         return;
  636                 h0h0.gp = gp;
  637                 h0h0.ms = gsp->softc;
  638                 h0h0.label = label;
  639                 h0h0.error = -1;
  640                 /* XXX: Does this reference register with our selfdestruct code ? */
  641                 error = g_access(cp, 1, 1, 1);
  642                 if (error) {
  643                         gctl_error(req, "could not access consumer");
  644                         return;
  645                 }
  646                 g_bsd_callconfig(&h0h0, 0);
  647                 error = h0h0.error;
  648                 g_access(cp, -1, -1, -1);
  649         } else if (!strcmp(verb, "write bootcode")) {
  650                 label = gctl_get_paraml(req, "bootcode", BBSIZE);
  651                 if (label == NULL)
  652                         return;
  653                 /* XXX: Does this reference register with our selfdestruct code ? */
  654                 error = g_access(cp, 1, 1, 1);
  655                 if (error) {
  656                         gctl_error(req, "could not access consumer");
  657                         return;
  658                 }
  659                 error = g_bsd_writelabel(gp, label);
  660                 g_access(cp, -1, -1, -1);
  661         } else {
  662                 gctl_error(req, "Unknown verb parameter");
  663         }
  664 
  665         return;
  666 }
  667 
  668 /* Finally, register with GEOM infrastructure. */
  669 static struct g_class g_bsd_class = {
  670         .name = BSD_CLASS_NAME,
  671         .version = G_VERSION,
  672         .taste = g_bsd_taste,
  673         .ctlreq = g_bsd_config,
  674         .dumpconf = g_bsd_dumpconf,
  675         .ioctl = g_bsd_ioctl,
  676 };
  677 
  678 DECLARE_GEOM_CLASS(g_bsd_class, g_bsd);

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