The Design and Implementation of the FreeBSD Operating System, Second Edition
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sys/geom/geom_subr.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 #include <sys/cdefs.h>
   37 __FBSDID("$FreeBSD$");
   38 
   39 #include <sys/param.h>
   40 #include <sys/systm.h>
   41 #include <sys/devicestat.h>
   42 #include <sys/kernel.h>
   43 #include <sys/malloc.h>
   44 #include <sys/bio.h>
   45 #include <sys/sysctl.h>
   46 #include <sys/proc.h>
   47 #include <sys/kthread.h>
   48 #include <sys/lock.h>
   49 #include <sys/mutex.h>
   50 #include <sys/errno.h>
   51 #include <sys/sbuf.h>
   52 #include <geom/geom.h>
   53 #include <geom/geom_int.h>
   54 #include <machine/stdarg.h>
   55 
   56 struct class_list_head g_classes = LIST_HEAD_INITIALIZER(g_classes);
   57 static struct g_tailq_head geoms = TAILQ_HEAD_INITIALIZER(geoms);
   58 char *g_wait_event, *g_wait_up, *g_wait_down, *g_wait_sim;
   59 
   60 struct g_hh00 {
   61         struct g_class  *mp;
   62         int             error;
   63         int             post;
   64 };
   65 
   66 /*
   67  * This event offers a new class a chance to taste all preexisting providers.
   68  */
   69 static void
   70 g_load_class(void *arg, int flag)
   71 {
   72         struct g_hh00 *hh;
   73         struct g_class *mp2, *mp;
   74         struct g_geom *gp;
   75         struct g_provider *pp;
   76 
   77         g_topology_assert();
   78         if (flag == EV_CANCEL)  /* XXX: can't happen ? */
   79                 return;
   80         if (g_shutdown)
   81                 return;
   82 
   83         hh = arg;
   84         mp = hh->mp;
   85         hh->error = 0;
   86         if (hh->post) {
   87                 g_free(hh);
   88                 hh = NULL;
   89         }
   90         g_trace(G_T_TOPOLOGY, "g_load_class(%s)", mp->name);
   91         KASSERT(mp->name != NULL && *mp->name != '\0',
   92             ("GEOM class has no name"));
   93         LIST_FOREACH(mp2, &g_classes, class) {
   94                 if (mp2 == mp) {
   95                         printf("The GEOM class %s is already loaded.\n",
   96                             mp2->name);
   97                         if (hh != NULL)
   98                                 hh->error = EEXIST;
   99                         return;
  100                 } else if (strcmp(mp2->name, mp->name) == 0) {
  101                         printf("A GEOM class %s is already loaded.\n",
  102                             mp2->name);
  103                         if (hh != NULL)
  104                                 hh->error = EEXIST;
  105                         return;
  106                 }
  107         }
  108 
  109         LIST_INIT(&mp->geom);
  110         LIST_INSERT_HEAD(&g_classes, mp, class);
  111         if (mp->init != NULL)
  112                 mp->init(mp);
  113         if (mp->taste == NULL)
  114                 return;
  115         LIST_FOREACH(mp2, &g_classes, class) {
  116                 if (mp == mp2)
  117                         continue;
  118                 LIST_FOREACH(gp, &mp2->geom, geom) {
  119                         LIST_FOREACH(pp, &gp->provider, provider) {
  120                                 mp->taste(mp, pp, 0);
  121                                 g_topology_assert();
  122                         }
  123                 }
  124         }
  125 }
  126 
  127 static void
  128 g_unload_class(void *arg, int flag)
  129 {
  130         struct g_hh00 *hh;
  131         struct g_class *mp;
  132         struct g_geom *gp;
  133         struct g_provider *pp;
  134         struct g_consumer *cp;
  135         int error;
  136 
  137         g_topology_assert();
  138         hh = arg;
  139         mp = hh->mp;
  140         G_VALID_CLASS(mp);
  141         g_trace(G_T_TOPOLOGY, "g_unload_class(%s)", mp->name);
  142 
  143         /*
  144          * We allow unloading if we have no geoms, or a class
  145          * method we can use to get rid of them.
  146          */
  147         if (!LIST_EMPTY(&mp->geom) && mp->destroy_geom == NULL) {
  148                 hh->error = EOPNOTSUPP;
  149                 return;
  150         }
  151 
  152         /* We refuse to unload if anything is open */
  153         LIST_FOREACH(gp, &mp->geom, geom) {
  154                 LIST_FOREACH(pp, &gp->provider, provider)
  155                         if (pp->acr || pp->acw || pp->ace) {
  156                                 hh->error = EBUSY;
  157                                 return;
  158                         }
  159                 LIST_FOREACH(cp, &gp->consumer, consumer)
  160                         if (cp->acr || cp->acw || cp->ace) {
  161                                 hh->error = EBUSY;
  162                                 return;
  163                         }
  164         }
  165 
  166         /* Bar new entries */
  167         mp->taste = NULL;
  168         mp->config = NULL;
  169 
  170         error = 0;
  171         for (;;) {
  172                 gp = LIST_FIRST(&mp->geom);
  173                 if (gp == NULL)
  174                         break;
  175                 error = mp->destroy_geom(NULL, mp, gp);
  176                 if (error != 0)
  177                         break;
  178         }
  179         if (error == 0) {
  180                 if (mp->fini != NULL)
  181                         mp->fini(mp);
  182                 LIST_REMOVE(mp, class);
  183         }
  184         hh->error = error;
  185         return;
  186 }
  187 
  188 int
  189 g_modevent(module_t mod, int type, void *data)
  190 {
  191         struct g_hh00 *hh;
  192         int error;
  193         static int g_ignition;
  194         struct g_class *mp;
  195 
  196         mp = data;
  197         if (mp->version != G_VERSION) {
  198                 printf("GEOM class %s has Wrong version %x\n",
  199                     mp->name, mp->version);
  200                 return (EINVAL);
  201         }
  202         if (!g_ignition) {
  203                 g_ignition++;
  204                 g_init();
  205         }
  206         hh = g_malloc(sizeof *hh, M_WAITOK | M_ZERO);
  207         hh->mp = data;
  208         error = EOPNOTSUPP;
  209         switch (type) {
  210         case MOD_LOAD:
  211                 g_trace(G_T_TOPOLOGY, "g_modevent(%s, LOAD)", hh->mp->name);
  212                 /*
  213                  * Once the system is not cold, MOD_LOAD calls will be
  214                  * from the userland and the g_event thread will be able
  215                  * to acknowledge their completion.
  216                  */
  217                 if (cold) {
  218                         hh->post = 1;
  219                         error = g_post_event(g_load_class, hh, M_WAITOK, NULL);
  220                 } else {
  221                         error = g_waitfor_event(g_load_class, hh, M_WAITOK,
  222                             NULL);
  223                         if (error == 0)
  224                                 error = hh->error;
  225                         g_free(hh);
  226                 }
  227                 break;
  228         case MOD_UNLOAD:
  229                 g_trace(G_T_TOPOLOGY, "g_modevent(%s, UNLOAD)", hh->mp->name);
  230                 error = g_waitfor_event(g_unload_class, hh, M_WAITOK, NULL);
  231                 if (error == 0)
  232                         error = hh->error;
  233                 if (error == 0) {
  234                         KASSERT(LIST_EMPTY(&hh->mp->geom),
  235                             ("Unloaded class (%s) still has geom", hh->mp->name));
  236                 }
  237                 g_free(hh);
  238                 break;
  239         default:
  240                 g_free(hh);
  241                 break;
  242         }
  243         return (error);
  244 }
  245 
  246 struct g_geom *
  247 g_new_geomf(struct g_class *mp, const char *fmt, ...)
  248 {
  249         struct g_geom *gp;
  250         va_list ap;
  251         struct sbuf *sb;
  252 
  253         g_topology_assert();
  254         G_VALID_CLASS(mp);
  255         sb = sbuf_new(NULL, NULL, 0, SBUF_AUTOEXTEND);
  256         va_start(ap, fmt);
  257         sbuf_vprintf(sb, fmt, ap);
  258         va_end(ap);
  259         sbuf_finish(sb);
  260         gp = g_malloc(sizeof *gp, M_WAITOK | M_ZERO);
  261         gp->name = g_malloc(sbuf_len(sb) + 1, M_WAITOK | M_ZERO);
  262         gp->class = mp;
  263         gp->rank = 1;
  264         LIST_INIT(&gp->consumer);
  265         LIST_INIT(&gp->provider);
  266         LIST_INSERT_HEAD(&mp->geom, gp, geom);
  267         TAILQ_INSERT_HEAD(&geoms, gp, geoms);
  268         strcpy(gp->name, sbuf_data(sb));
  269         sbuf_delete(sb);
  270         /* Fill in defaults from class */
  271         gp->start = mp->start;
  272         gp->spoiled = mp->spoiled;
  273         gp->dumpconf = mp->dumpconf;
  274         gp->access = mp->access;
  275         gp->orphan = mp->orphan;
  276         gp->ioctl = mp->ioctl;
  277         return (gp);
  278 }
  279 
  280 void
  281 g_destroy_geom(struct g_geom *gp)
  282 {
  283 
  284         g_topology_assert();
  285         G_VALID_GEOM(gp);
  286         g_trace(G_T_TOPOLOGY, "g_destroy_geom(%p(%s))", gp, gp->name);
  287         KASSERT(LIST_EMPTY(&gp->consumer),
  288             ("g_destroy_geom(%s) with consumer(s) [%p]",
  289             gp->name, LIST_FIRST(&gp->consumer)));
  290         KASSERT(LIST_EMPTY(&gp->provider),
  291             ("g_destroy_geom(%s) with provider(s) [%p]",
  292             gp->name, LIST_FIRST(&gp->provider)));
  293         g_cancel_event(gp);
  294         LIST_REMOVE(gp, geom);
  295         TAILQ_REMOVE(&geoms, gp, geoms);
  296         g_free(gp->name);
  297         g_free(gp);
  298 }
  299 
  300 /*
  301  * This function is called (repeatedly) until the has withered away.
  302  */
  303 void
  304 g_wither_geom(struct g_geom *gp, int error)
  305 {
  306         struct g_provider *pp;
  307 
  308         g_topology_assert();
  309         G_VALID_GEOM(gp);
  310         g_trace(G_T_TOPOLOGY, "g_wither_geom(%p(%s))", gp, gp->name);
  311         if (!(gp->flags & G_GEOM_WITHER)) {
  312                 gp->flags |= G_GEOM_WITHER;
  313                 LIST_FOREACH(pp, &gp->provider, provider)
  314                         if (!(pp->flags & G_PF_ORPHAN))
  315                                 g_orphan_provider(pp, error);
  316         }
  317         g_do_wither();
  318 }
  319 
  320 /*
  321  * This function is called (repeatedly) until the has withered away.
  322  */
  323 void
  324 g_wither_geom_close(struct g_geom *gp, int error)
  325 {
  326         struct g_consumer *cp;
  327 
  328         g_topology_assert();
  329         G_VALID_GEOM(gp);
  330         g_trace(G_T_TOPOLOGY, "g_wither_geom_close(%p(%s))", gp, gp->name);
  331         LIST_FOREACH(cp, &gp->consumer, consumer)
  332                 if (cp->acr || cp->acw || cp->ace)
  333                         g_access(cp, -cp->acr, -cp->acw, -cp->ace);
  334         g_wither_geom(gp, error);
  335 }
  336 
  337 /*
  338  * This function is called (repeatedly) until we cant wash away more
  339  * withered bits at present.  Return value contains two bits.  Bit 0
  340  * set means "withering stuff we can't wash now", bit 1 means "call
  341  * me again, there may be stuff I didn't get the first time around.
  342  */
  343 int
  344 g_wither_washer()
  345 {
  346         struct g_class *mp;
  347         struct g_geom *gp, *gp2;
  348         struct g_provider *pp, *pp2;
  349         struct g_consumer *cp, *cp2;
  350         int result;
  351 
  352         result = 0;
  353         g_topology_assert();
  354         LIST_FOREACH(mp, &g_classes, class) {
  355                 LIST_FOREACH_SAFE(gp, &mp->geom, geom, gp2) {
  356                         LIST_FOREACH_SAFE(pp, &gp->provider, provider, pp2) {
  357                                 if (!(pp->flags & G_PF_WITHER))
  358                                         continue;
  359                                 if (LIST_EMPTY(&pp->consumers))
  360                                         g_destroy_provider(pp);
  361                                 else
  362                                         result |= 1;
  363                         }
  364                         if (!(gp->flags & G_GEOM_WITHER))
  365                                 continue;
  366                         LIST_FOREACH_SAFE(pp, &gp->provider, provider, pp2) {
  367                                 if (LIST_EMPTY(&pp->consumers))
  368                                         g_destroy_provider(pp);
  369                                 else
  370                                         result |= 1;
  371                         }
  372                         LIST_FOREACH_SAFE(cp, &gp->consumer, consumer, cp2) {
  373                                 if (cp->acr || cp->acw || cp->ace) {
  374                                         result |= 1;
  375                                         continue;
  376                                 }
  377                                 if (cp->provider != NULL)
  378                                         g_detach(cp);
  379                                 g_destroy_consumer(cp);
  380                                 result |= 2;
  381                         }
  382                         if (LIST_EMPTY(&gp->provider) &&
  383                             LIST_EMPTY(&gp->consumer))
  384                                 g_destroy_geom(gp);
  385                         else
  386                                 result |= 1;
  387                 }
  388         }
  389         return (result);
  390 }
  391 
  392 struct g_consumer *
  393 g_new_consumer(struct g_geom *gp)
  394 {
  395         struct g_consumer *cp;
  396 
  397         g_topology_assert();
  398         G_VALID_GEOM(gp);
  399         KASSERT(!(gp->flags & G_GEOM_WITHER),
  400             ("g_new_consumer on WITHERing geom(%s) (class %s)",
  401             gp->name, gp->class->name));
  402         KASSERT(gp->orphan != NULL,
  403             ("g_new_consumer on geom(%s) (class %s) without orphan",
  404             gp->name, gp->class->name));
  405 
  406         cp = g_malloc(sizeof *cp, M_WAITOK | M_ZERO);
  407         cp->geom = gp;
  408         cp->stat = devstat_new_entry(cp, -1, 0, DEVSTAT_ALL_SUPPORTED,
  409             DEVSTAT_TYPE_DIRECT, DEVSTAT_PRIORITY_MAX);
  410         LIST_INSERT_HEAD(&gp->consumer, cp, consumer);
  411         return(cp);
  412 }
  413 
  414 void
  415 g_destroy_consumer(struct g_consumer *cp)
  416 {
  417         struct g_geom *gp;
  418 
  419         g_topology_assert();
  420         G_VALID_CONSUMER(cp);
  421         g_trace(G_T_TOPOLOGY, "g_destroy_consumer(%p)", cp);
  422         KASSERT (cp->provider == NULL, ("g_destroy_consumer but attached"));
  423         KASSERT (cp->acr == 0, ("g_destroy_consumer with acr"));
  424         KASSERT (cp->acw == 0, ("g_destroy_consumer with acw"));
  425         KASSERT (cp->ace == 0, ("g_destroy_consumer with ace"));
  426         g_cancel_event(cp);
  427         gp = cp->geom;
  428         LIST_REMOVE(cp, consumer);
  429         devstat_remove_entry(cp->stat);
  430         g_free(cp);
  431         if (gp->flags & G_GEOM_WITHER)
  432                 g_do_wither();
  433 }
  434 
  435 static void
  436 g_new_provider_event(void *arg, int flag)
  437 {
  438         struct g_class *mp;
  439         struct g_provider *pp;
  440         struct g_consumer *cp;
  441         int i;
  442 
  443         g_topology_assert();
  444         if (flag == EV_CANCEL)
  445                 return;
  446         if (g_shutdown)
  447                 return;
  448         pp = arg;
  449         G_VALID_PROVIDER(pp);
  450         LIST_FOREACH(mp, &g_classes, class) {
  451                 if (mp->taste == NULL)
  452                         continue;
  453                 i = 1;
  454                 LIST_FOREACH(cp, &pp->consumers, consumers)
  455                         if (cp->geom->class == mp)
  456                                 i = 0;
  457                 if (!i)
  458                         continue;
  459                 mp->taste(mp, pp, 0);
  460                 g_topology_assert();
  461         }
  462 }
  463 
  464 
  465 struct g_provider *
  466 g_new_providerf(struct g_geom *gp, const char *fmt, ...)
  467 {
  468         struct g_provider *pp;
  469         struct sbuf *sb;
  470         va_list ap;
  471 
  472         g_topology_assert();
  473         G_VALID_GEOM(gp);
  474         KASSERT(gp->access != NULL,
  475             ("new provider on geom(%s) without ->access (class %s)",
  476             gp->name, gp->class->name));
  477         KASSERT(gp->start != NULL,
  478             ("new provider on geom(%s) without ->start (class %s)",
  479             gp->name, gp->class->name));
  480         KASSERT(!(gp->flags & G_GEOM_WITHER),
  481             ("new provider on WITHERing geom(%s) (class %s)",
  482             gp->name, gp->class->name));
  483         sb = sbuf_new(NULL, NULL, 0, SBUF_AUTOEXTEND);
  484         va_start(ap, fmt);
  485         sbuf_vprintf(sb, fmt, ap);
  486         va_end(ap);
  487         sbuf_finish(sb);
  488         pp = g_malloc(sizeof *pp + sbuf_len(sb) + 1, M_WAITOK | M_ZERO);
  489         pp->name = (char *)(pp + 1);
  490         strcpy(pp->name, sbuf_data(sb));
  491         sbuf_delete(sb);
  492         LIST_INIT(&pp->consumers);
  493         pp->error = ENXIO;
  494         pp->geom = gp;
  495         pp->stat = devstat_new_entry(pp, -1, 0, DEVSTAT_ALL_SUPPORTED,
  496             DEVSTAT_TYPE_DIRECT, DEVSTAT_PRIORITY_MAX);
  497         LIST_INSERT_HEAD(&gp->provider, pp, provider);
  498         g_post_event(g_new_provider_event, pp, M_WAITOK, pp, gp, NULL);
  499         return (pp);
  500 }
  501 
  502 void
  503 g_error_provider(struct g_provider *pp, int error)
  504 {
  505 
  506         /* G_VALID_PROVIDER(pp);  We may not have g_topology */
  507         pp->error = error;
  508 }
  509 
  510 struct g_provider *
  511 g_provider_by_name(char const *arg)
  512 {
  513         struct g_class *cp;
  514         struct g_geom *gp;
  515         struct g_provider *pp;
  516 
  517         LIST_FOREACH(cp, &g_classes, class) {
  518                 LIST_FOREACH(gp, &cp->geom, geom) {
  519                         LIST_FOREACH(pp, &gp->provider, provider) {
  520                                 if (!strcmp(arg, pp->name))
  521                                         return (pp);
  522                         }
  523                 }
  524         }
  525         return (NULL);
  526 }
  527 
  528 void
  529 g_destroy_provider(struct g_provider *pp)
  530 {
  531         struct g_geom *gp;
  532 
  533         g_topology_assert();
  534         G_VALID_PROVIDER(pp);
  535         KASSERT(LIST_EMPTY(&pp->consumers),
  536             ("g_destroy_provider but attached"));
  537         KASSERT (pp->acr == 0, ("g_destroy_provider with acr"));
  538         KASSERT (pp->acw == 0, ("g_destroy_provider with acw"));
  539         KASSERT (pp->acw == 0, ("g_destroy_provider with ace"));
  540         g_cancel_event(pp);
  541         LIST_REMOVE(pp, provider);
  542         gp = pp->geom;
  543         devstat_remove_entry(pp->stat);
  544         g_free(pp);
  545         if ((gp->flags & G_GEOM_WITHER))
  546                 g_do_wither();
  547 }
  548 
  549 /*
  550  * We keep the "geoms" list sorted by topological order (== increasing
  551  * numerical rank) at all times.
  552  * When an attach is done, the attaching geoms rank is invalidated
  553  * and it is moved to the tail of the list.
  554  * All geoms later in the sequence has their ranks reevaluated in
  555  * sequence.  If we cannot assign rank to a geom because it's
  556  * prerequisites do not have rank, we move that element to the tail
  557  * of the sequence with invalid rank as well.
  558  * At some point we encounter our original geom and if we stil fail
  559  * to assign it a rank, there must be a loop and we fail back to
  560  * g_attach() which detach again and calls redo_rank again
  561  * to fix up the damage.
  562  * It would be much simpler code wise to do it recursively, but we
  563  * can't risk that on the kernel stack.
  564  */
  565 
  566 static int
  567 redo_rank(struct g_geom *gp)
  568 {
  569         struct g_consumer *cp;
  570         struct g_geom *gp1, *gp2;
  571         int n, m;
  572 
  573         g_topology_assert();
  574         G_VALID_GEOM(gp);
  575 
  576         /* Invalidate this geoms rank and move it to the tail */
  577         gp1 = TAILQ_NEXT(gp, geoms);
  578         if (gp1 != NULL) {
  579                 gp->rank = 0;
  580                 TAILQ_REMOVE(&geoms, gp, geoms);
  581                 TAILQ_INSERT_TAIL(&geoms, gp, geoms);
  582         } else {
  583                 gp1 = gp;
  584         }
  585 
  586         /* re-rank the rest of the sequence */
  587         for (; gp1 != NULL; gp1 = gp2) {
  588                 gp1->rank = 0;
  589                 m = 1;
  590                 LIST_FOREACH(cp, &gp1->consumer, consumer) {
  591                         if (cp->provider == NULL)
  592                                 continue;
  593                         n = cp->provider->geom->rank;
  594                         if (n == 0) {
  595                                 m = 0;
  596                                 break;
  597                         } else if (n >= m)
  598                                 m = n + 1;
  599                 }
  600                 gp1->rank = m;
  601                 gp2 = TAILQ_NEXT(gp1, geoms);
  602 
  603                 /* got a rank, moving on */
  604                 if (m != 0)
  605                         continue;
  606 
  607                 /* no rank to original geom means loop */
  608                 if (gp == gp1) 
  609                         return (ELOOP);
  610 
  611                 /* no rank, put it at the end move on */
  612                 TAILQ_REMOVE(&geoms, gp1, geoms);
  613                 TAILQ_INSERT_TAIL(&geoms, gp1, geoms);
  614         }
  615         return (0);
  616 }
  617 
  618 int
  619 g_attach(struct g_consumer *cp, struct g_provider *pp)
  620 {
  621         int error;
  622 
  623         g_topology_assert();
  624         G_VALID_CONSUMER(cp);
  625         G_VALID_PROVIDER(pp);
  626         KASSERT(cp->provider == NULL, ("attach but attached"));
  627         cp->provider = pp;
  628         LIST_INSERT_HEAD(&pp->consumers, cp, consumers);
  629         error = redo_rank(cp->geom);
  630         if (error) {
  631                 LIST_REMOVE(cp, consumers);
  632                 cp->provider = NULL;
  633                 redo_rank(cp->geom);
  634         }
  635         return (error);
  636 }
  637 
  638 void
  639 g_detach(struct g_consumer *cp)
  640 {
  641         struct g_provider *pp;
  642 
  643         g_topology_assert();
  644         G_VALID_CONSUMER(cp);
  645         g_trace(G_T_TOPOLOGY, "g_detach(%p)", cp);
  646         KASSERT(cp->provider != NULL, ("detach but not attached"));
  647         KASSERT(cp->acr == 0, ("detach but nonzero acr"));
  648         KASSERT(cp->acw == 0, ("detach but nonzero acw"));
  649         KASSERT(cp->ace == 0, ("detach but nonzero ace"));
  650         KASSERT(cp->nstart == cp->nend,
  651             ("detach with active requests"));
  652         pp = cp->provider;
  653         LIST_REMOVE(cp, consumers);
  654         cp->provider = NULL;
  655         if (pp->geom->flags & G_GEOM_WITHER)
  656                 g_do_wither();
  657         else if (pp->flags & G_PF_WITHER)
  658                 g_do_wither();
  659         redo_rank(cp->geom);
  660 }
  661 
  662 /*
  663  * g_access()
  664  *
  665  * Access-check with delta values.  The question asked is "can provider
  666  * "cp" change the access counters by the relative amounts dc[rwe] ?"
  667  */
  668 
  669 int
  670 g_access(struct g_consumer *cp, int dcr, int dcw, int dce)
  671 {
  672         struct g_provider *pp;
  673         int pr,pw,pe;
  674         int error;
  675 
  676         g_topology_assert();
  677         G_VALID_CONSUMER(cp);
  678         pp = cp->provider;
  679         KASSERT(pp != NULL, ("access but not attached"));
  680         G_VALID_PROVIDER(pp);
  681 
  682         g_trace(G_T_ACCESS, "g_access(%p(%s), %d, %d, %d)",
  683             cp, pp->name, dcr, dcw, dce);
  684 
  685         KASSERT(cp->acr + dcr >= 0, ("access resulting in negative acr"));
  686         KASSERT(cp->acw + dcw >= 0, ("access resulting in negative acw"));
  687         KASSERT(cp->ace + dce >= 0, ("access resulting in negative ace"));
  688         KASSERT(dcr != 0 || dcw != 0 || dce != 0, ("NOP access request"));
  689         KASSERT(pp->geom->access != NULL, ("NULL geom->access"));
  690 
  691         /*
  692          * If our class cares about being spoiled, and we have been, we
  693          * are probably just ahead of the event telling us that.  Fail
  694          * now rather than having to unravel this later.
  695          */
  696         if (cp->geom->spoiled != NULL && cp->spoiled &&
  697             (dcr > 0 || dcw > 0 || dce > 0))
  698                 return (ENXIO);
  699 
  700         /*
  701          * Figure out what counts the provider would have had, if this
  702          * consumer had (r0w0e0) at this time.
  703          */
  704         pr = pp->acr - cp->acr;
  705         pw = pp->acw - cp->acw;
  706         pe = pp->ace - cp->ace;
  707 
  708         g_trace(G_T_ACCESS,
  709     "open delta:[r%dw%de%d] old:[r%dw%de%d] provider:[r%dw%de%d] %p(%s)",
  710             dcr, dcw, dce,
  711             cp->acr, cp->acw, cp->ace,
  712             pp->acr, pp->acw, pp->ace,
  713             pp, pp->name);
  714 
  715         /* If foot-shooting is enabled, any open on rank#1 is OK */
  716         if ((g_debugflags & 16) && pp->geom->rank == 1)
  717                 ;
  718         /* If we try exclusive but already write: fail */
  719         else if (dce > 0 && pw > 0)
  720                 return (EPERM);
  721         /* If we try write but already exclusive: fail */
  722         else if (dcw > 0 && pe > 0)
  723                 return (EPERM);
  724         /* If we try to open more but provider is error'ed: fail */
  725         else if ((dcr > 0 || dcw > 0 || dce > 0) && pp->error != 0)
  726                 return (pp->error);
  727 
  728         /* Ok then... */
  729 
  730         error = pp->geom->access(pp, dcr, dcw, dce);
  731         KASSERT(dcr > 0 || dcw > 0 || dce > 0 || error == 0,
  732             ("Geom provider %s::%s failed closing ->access()",
  733             pp->geom->class->name, pp->name));
  734         if (!error) {
  735                 /*
  736                  * If we open first write, spoil any partner consumers.
  737                  * If we close last write and provider is not errored,
  738                  * trigger re-taste.
  739                  */
  740                 if (pp->acw == 0 && dcw != 0)
  741                         g_spoil(pp, cp);
  742                 else if (pp->acw != 0 && pp->acw == -dcw && pp->error == 0 &&
  743                     !(pp->geom->flags & G_GEOM_WITHER))
  744                         g_post_event(g_new_provider_event, pp, M_WAITOK, 
  745                             pp, NULL);
  746 
  747                 pp->acr += dcr;
  748                 pp->acw += dcw;
  749                 pp->ace += dce;
  750                 cp->acr += dcr;
  751                 cp->acw += dcw;
  752                 cp->ace += dce;
  753                 if (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)
  754                         KASSERT(pp->sectorsize > 0,
  755                             ("Provider %s lacks sectorsize", pp->name));
  756         }
  757         return (error);
  758 }
  759 
  760 int
  761 g_handleattr_int(struct bio *bp, const char *attribute, int val)
  762 {
  763 
  764         return (g_handleattr(bp, attribute, &val, sizeof val));
  765 }
  766 
  767 int
  768 g_handleattr_off_t(struct bio *bp, const char *attribute, off_t val)
  769 {
  770 
  771         return (g_handleattr(bp, attribute, &val, sizeof val));
  772 }
  773 
  774 int
  775 g_handleattr(struct bio *bp, const char *attribute, void *val, int len)
  776 {
  777         int error;
  778 
  779         if (strcmp(bp->bio_attribute, attribute))
  780                 return (0);
  781         if (bp->bio_length != len) {
  782                 printf("bio_length %jd len %d -> EFAULT\n",
  783                     (intmax_t)bp->bio_length, len);
  784                 error = EFAULT;
  785         } else {
  786                 error = 0;
  787                 bcopy(val, bp->bio_data, len);
  788                 bp->bio_completed = len;
  789         }
  790         g_io_deliver(bp, error);
  791         return (1);
  792 }
  793 
  794 int
  795 g_std_access(struct g_provider *pp,
  796         int dr __unused, int dw __unused, int de __unused)
  797 {
  798 
  799         g_topology_assert();
  800         G_VALID_PROVIDER(pp);
  801         return (0);
  802 }
  803 
  804 void
  805 g_std_done(struct bio *bp)
  806 {
  807         struct bio *bp2;
  808 
  809         bp2 = bp->bio_parent;
  810         if (bp2->bio_error == 0)
  811                 bp2->bio_error = bp->bio_error;
  812         bp2->bio_completed += bp->bio_completed;
  813         g_destroy_bio(bp);
  814         bp2->bio_inbed++;
  815         if (bp2->bio_children == bp2->bio_inbed)
  816                 g_io_deliver(bp2, bp2->bio_error);
  817 }
  818 
  819 /* XXX: maybe this is only g_slice_spoiled */
  820 
  821 void
  822 g_std_spoiled(struct g_consumer *cp)
  823 {
  824         struct g_geom *gp;
  825         struct g_provider *pp;
  826 
  827         g_topology_assert();
  828         G_VALID_CONSUMER(cp);
  829         g_trace(G_T_TOPOLOGY, "g_std_spoiled(%p)", cp);
  830         g_detach(cp);
  831         gp = cp->geom;
  832         LIST_FOREACH(pp, &gp->provider, provider)
  833                 g_orphan_provider(pp, ENXIO);
  834         g_destroy_consumer(cp);
  835         if (LIST_EMPTY(&gp->provider) && LIST_EMPTY(&gp->consumer))
  836                 g_destroy_geom(gp);
  837         else
  838                 gp->flags |= G_GEOM_WITHER;
  839 }
  840 
  841 /*
  842  * Spoiling happens when a provider is opened for writing, but consumers
  843  * which are configured by in-band data are attached (slicers for instance).
  844  * Since the write might potentially change the in-band data, such consumers
  845  * need to re-evaluate their existence after the writing session closes.
  846  * We do this by (offering to) tear them down when the open for write happens
  847  * in return for a re-taste when it closes again.
  848  * Together with the fact that such consumers grab an 'e' bit whenever they
  849  * are open, regardless of mode, this ends up DTRT.
  850  */
  851 
  852 static void
  853 g_spoil_event(void *arg, int flag)
  854 {
  855         struct g_provider *pp;
  856         struct g_consumer *cp, *cp2;
  857 
  858         g_topology_assert();
  859         if (flag == EV_CANCEL)
  860                 return;
  861         pp = arg;
  862         G_VALID_PROVIDER(pp);
  863         for (cp = LIST_FIRST(&pp->consumers); cp != NULL; cp = cp2) {
  864                 cp2 = LIST_NEXT(cp, consumers);
  865                 if (!cp->spoiled)
  866                         continue;
  867                 cp->spoiled = 0;
  868                 if (cp->geom->spoiled == NULL)
  869                         continue;
  870                 cp->geom->spoiled(cp);
  871                 g_topology_assert();
  872         }
  873 }
  874 
  875 void
  876 g_spoil(struct g_provider *pp, struct g_consumer *cp)
  877 {
  878         struct g_consumer *cp2;
  879 
  880         g_topology_assert();
  881         G_VALID_PROVIDER(pp);
  882         G_VALID_CONSUMER(cp);
  883 
  884         LIST_FOREACH(cp2, &pp->consumers, consumers) {
  885                 if (cp2 == cp)
  886                         continue;
  887 /*
  888                 KASSERT(cp2->acr == 0, ("spoiling cp->acr = %d", cp2->acr));
  889                 KASSERT(cp2->acw == 0, ("spoiling cp->acw = %d", cp2->acw));
  890 */
  891                 KASSERT(cp2->ace == 0, ("spoiling cp->ace = %d", cp2->ace));
  892                 cp2->spoiled++;
  893         }
  894         g_post_event(g_spoil_event, pp, M_WAITOK, pp, NULL);
  895 }
  896 
  897 int
  898 g_getattr__(const char *attr, struct g_consumer *cp, void *var, int len)
  899 {
  900         int error, i;
  901 
  902         i = len;
  903         error = g_io_getattr(attr, cp, &i, var);
  904         if (error)
  905                 return (error);
  906         if (i != len)
  907                 return (EINVAL);
  908         return (0);
  909 }
  910 
  911 #ifdef DIAGNOSTIC
  912 /*
  913  * This function walks (topologically unsafely) the mesh and return a
  914  * non-zero integer if it finds the argument pointer is an object.
  915  * The return value indicates which type of object it is belived to be.
  916  * If topology is not locked, this function is potentially dangerous,
  917  * but since it is for debugging purposes and can be useful for instance
  918  * from DDB, we do not assert topology lock is held.
  919  */
  920 int
  921 g_valid_obj(void const *ptr)
  922 {
  923         struct g_class *mp;
  924         struct g_geom *gp;
  925         struct g_consumer *cp;
  926         struct g_provider *pp;
  927 
  928         LIST_FOREACH(mp, &g_classes, class) {
  929                 if (ptr == mp)
  930                         return (1);
  931                 LIST_FOREACH(gp, &mp->geom, geom) {
  932                         if (ptr == gp)
  933                                 return (2);
  934                         LIST_FOREACH(cp, &gp->consumer, consumer)
  935                                 if (ptr == cp)
  936                                         return (3);
  937                         LIST_FOREACH(pp, &gp->provider, provider)
  938                                 if (ptr == pp)
  939                                         return (4);
  940                 }
  941         }
  942         return(0);
  943 }
  944 #endif

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