The Design and Implementation of the FreeBSD Operating System, Second Edition
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sys/geom/geom_io.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 2002 Poul-Henning Kamp
    5  * Copyright (c) 2002 Networks Associates Technology, Inc.
    6  * Copyright (c) 2013 The FreeBSD Foundation
    7  * All rights reserved.
    8  *
    9  * This software was developed for the FreeBSD Project by Poul-Henning Kamp
   10  * and NAI Labs, the Security Research Division of Network Associates, Inc.
   11  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
   12  * DARPA CHATS research program.
   13  *
   14  * Portions of this software were developed by Konstantin Belousov
   15  * under sponsorship from the FreeBSD Foundation.
   16  *
   17  * Redistribution and use in source and binary forms, with or without
   18  * modification, are permitted provided that the following conditions
   19  * are met:
   20  * 1. Redistributions of source code must retain the above copyright
   21  *    notice, this list of conditions and the following disclaimer.
   22  * 2. Redistributions in binary form must reproduce the above copyright
   23  *    notice, this list of conditions and the following disclaimer in the
   24  *    documentation and/or other materials provided with the distribution.
   25  * 3. The names of the authors may not be used to endorse or promote
   26  *    products derived from this software without specific prior written
   27  *    permission.
   28  *
   29  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   39  * SUCH DAMAGE.
   40  */
   41 
   42 #include <sys/cdefs.h>
   43 __FBSDID("$FreeBSD: releng/12.0/sys/geom/geom_io.c 330264 2018-03-02 04:34:53Z mckusick $");
   44 
   45 #include <sys/param.h>
   46 #include <sys/systm.h>
   47 #include <sys/kernel.h>
   48 #include <sys/malloc.h>
   49 #include <sys/bio.h>
   50 #include <sys/ktr.h>
   51 #include <sys/proc.h>
   52 #include <sys/stack.h>
   53 #include <sys/sysctl.h>
   54 #include <sys/vmem.h>
   55 
   56 #include <sys/errno.h>
   57 #include <geom/geom.h>
   58 #include <geom/geom_int.h>
   59 #include <sys/devicestat.h>
   60 
   61 #include <vm/uma.h>
   62 #include <vm/vm.h>
   63 #include <vm/vm_param.h>
   64 #include <vm/vm_kern.h>
   65 #include <vm/vm_page.h>
   66 #include <vm/vm_object.h>
   67 #include <vm/vm_extern.h>
   68 #include <vm/vm_map.h>
   69 
   70 static int      g_io_transient_map_bio(struct bio *bp);
   71 
   72 static struct g_bioq g_bio_run_down;
   73 static struct g_bioq g_bio_run_up;
   74 
   75 /*
   76  * Pace is a hint that we've had some trouble recently allocating
   77  * bios, so we should back off trying to send I/O down the stack
   78  * a bit to let the problem resolve. When pacing, we also turn
   79  * off direct dispatch to also reduce memory pressure from I/Os
   80  * there, at the expxense of some added latency while the memory
   81  * pressures exist. See g_io_schedule_down() for more details
   82  * and limitations.
   83  */
   84 static volatile u_int pace;
   85 
   86 static uma_zone_t       biozone;
   87 
   88 /*
   89  * The head of the list of classifiers used in g_io_request.
   90  * Use g_register_classifier() and g_unregister_classifier()
   91  * to add/remove entries to the list.
   92  * Classifiers are invoked in registration order.
   93  */
   94 static TAILQ_HEAD(g_classifier_tailq, g_classifier_hook)
   95     g_classifier_tailq = TAILQ_HEAD_INITIALIZER(g_classifier_tailq);
   96 
   97 #include <machine/atomic.h>
   98 
   99 static void
  100 g_bioq_lock(struct g_bioq *bq)
  101 {
  102 
  103         mtx_lock(&bq->bio_queue_lock);
  104 }
  105 
  106 static void
  107 g_bioq_unlock(struct g_bioq *bq)
  108 {
  109 
  110         mtx_unlock(&bq->bio_queue_lock);
  111 }
  112 
  113 #if 0
  114 static void
  115 g_bioq_destroy(struct g_bioq *bq)
  116 {
  117 
  118         mtx_destroy(&bq->bio_queue_lock);
  119 }
  120 #endif
  121 
  122 static void
  123 g_bioq_init(struct g_bioq *bq)
  124 {
  125 
  126         TAILQ_INIT(&bq->bio_queue);
  127         mtx_init(&bq->bio_queue_lock, "bio queue", NULL, MTX_DEF);
  128 }
  129 
  130 static struct bio *
  131 g_bioq_first(struct g_bioq *bq)
  132 {
  133         struct bio *bp;
  134 
  135         bp = TAILQ_FIRST(&bq->bio_queue);
  136         if (bp != NULL) {
  137                 KASSERT((bp->bio_flags & BIO_ONQUEUE),
  138                     ("Bio not on queue bp=%p target %p", bp, bq));
  139                 bp->bio_flags &= ~BIO_ONQUEUE;
  140                 TAILQ_REMOVE(&bq->bio_queue, bp, bio_queue);
  141                 bq->bio_queue_length--;
  142         }
  143         return (bp);
  144 }
  145 
  146 struct bio *
  147 g_new_bio(void)
  148 {
  149         struct bio *bp;
  150 
  151         bp = uma_zalloc(biozone, M_NOWAIT | M_ZERO);
  152 #ifdef KTR
  153         if ((KTR_COMPILE & KTR_GEOM) && (ktr_mask & KTR_GEOM)) {
  154                 struct stack st;
  155 
  156                 CTR1(KTR_GEOM, "g_new_bio(): %p", bp);
  157                 stack_save(&st);
  158                 CTRSTACK(KTR_GEOM, &st, 3, 0);
  159         }
  160 #endif
  161         return (bp);
  162 }
  163 
  164 struct bio *
  165 g_alloc_bio(void)
  166 {
  167         struct bio *bp;
  168 
  169         bp = uma_zalloc(biozone, M_WAITOK | M_ZERO);
  170 #ifdef KTR
  171         if ((KTR_COMPILE & KTR_GEOM) && (ktr_mask & KTR_GEOM)) {
  172                 struct stack st;
  173 
  174                 CTR1(KTR_GEOM, "g_alloc_bio(): %p", bp);
  175                 stack_save(&st);
  176                 CTRSTACK(KTR_GEOM, &st, 3, 0);
  177         }
  178 #endif
  179         return (bp);
  180 }
  181 
  182 void
  183 g_destroy_bio(struct bio *bp)
  184 {
  185 #ifdef KTR
  186         if ((KTR_COMPILE & KTR_GEOM) && (ktr_mask & KTR_GEOM)) {
  187                 struct stack st;
  188 
  189                 CTR1(KTR_GEOM, "g_destroy_bio(): %p", bp);
  190                 stack_save(&st);
  191                 CTRSTACK(KTR_GEOM, &st, 3, 0);
  192         }
  193 #endif
  194         uma_zfree(biozone, bp);
  195 }
  196 
  197 struct bio *
  198 g_clone_bio(struct bio *bp)
  199 {
  200         struct bio *bp2;
  201 
  202         bp2 = uma_zalloc(biozone, M_NOWAIT | M_ZERO);
  203         if (bp2 != NULL) {
  204                 bp2->bio_parent = bp;
  205                 bp2->bio_cmd = bp->bio_cmd;
  206                 /*
  207                  *  BIO_ORDERED flag may be used by disk drivers to enforce
  208                  *  ordering restrictions, so this flag needs to be cloned.
  209                  *  BIO_UNMAPPED and BIO_VLIST should be inherited, to properly
  210                  *  indicate which way the buffer is passed.
  211                  *  Other bio flags are not suitable for cloning.
  212                  */
  213                 bp2->bio_flags = bp->bio_flags &
  214                     (BIO_ORDERED | BIO_UNMAPPED | BIO_VLIST);
  215                 bp2->bio_length = bp->bio_length;
  216                 bp2->bio_offset = bp->bio_offset;
  217                 bp2->bio_data = bp->bio_data;
  218                 bp2->bio_ma = bp->bio_ma;
  219                 bp2->bio_ma_n = bp->bio_ma_n;
  220                 bp2->bio_ma_offset = bp->bio_ma_offset;
  221                 bp2->bio_attribute = bp->bio_attribute;
  222                 if (bp->bio_cmd == BIO_ZONE)
  223                         bcopy(&bp->bio_zone, &bp2->bio_zone,
  224                             sizeof(bp->bio_zone));
  225                 /* Inherit classification info from the parent */
  226                 bp2->bio_classifier1 = bp->bio_classifier1;
  227                 bp2->bio_classifier2 = bp->bio_classifier2;
  228 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
  229                 bp2->bio_track_bp = bp->bio_track_bp;
  230 #endif
  231                 bp->bio_children++;
  232         }
  233 #ifdef KTR
  234         if ((KTR_COMPILE & KTR_GEOM) && (ktr_mask & KTR_GEOM)) {
  235                 struct stack st;
  236 
  237                 CTR2(KTR_GEOM, "g_clone_bio(%p): %p", bp, bp2);
  238                 stack_save(&st);
  239                 CTRSTACK(KTR_GEOM, &st, 3, 0);
  240         }
  241 #endif
  242         return(bp2);
  243 }
  244 
  245 struct bio *
  246 g_duplicate_bio(struct bio *bp)
  247 {
  248         struct bio *bp2;
  249 
  250         bp2 = uma_zalloc(biozone, M_WAITOK | M_ZERO);
  251         bp2->bio_flags = bp->bio_flags & (BIO_UNMAPPED | BIO_VLIST);
  252         bp2->bio_parent = bp;
  253         bp2->bio_cmd = bp->bio_cmd;
  254         bp2->bio_length = bp->bio_length;
  255         bp2->bio_offset = bp->bio_offset;
  256         bp2->bio_data = bp->bio_data;
  257         bp2->bio_ma = bp->bio_ma;
  258         bp2->bio_ma_n = bp->bio_ma_n;
  259         bp2->bio_ma_offset = bp->bio_ma_offset;
  260         bp2->bio_attribute = bp->bio_attribute;
  261         bp->bio_children++;
  262 #ifdef KTR
  263         if ((KTR_COMPILE & KTR_GEOM) && (ktr_mask & KTR_GEOM)) {
  264                 struct stack st;
  265 
  266                 CTR2(KTR_GEOM, "g_duplicate_bio(%p): %p", bp, bp2);
  267                 stack_save(&st);
  268                 CTRSTACK(KTR_GEOM, &st, 3, 0);
  269         }
  270 #endif
  271         return(bp2);
  272 }
  273 
  274 void
  275 g_reset_bio(struct bio *bp)
  276 {
  277 
  278         bzero(bp, sizeof(*bp));
  279 }
  280 
  281 void
  282 g_io_init()
  283 {
  284 
  285         g_bioq_init(&g_bio_run_down);
  286         g_bioq_init(&g_bio_run_up);
  287         biozone = uma_zcreate("g_bio", sizeof (struct bio),
  288             NULL, NULL,
  289             NULL, NULL,
  290             0, 0);
  291 }
  292 
  293 int
  294 g_io_getattr(const char *attr, struct g_consumer *cp, int *len, void *ptr)
  295 {
  296         struct bio *bp;
  297         int error;
  298 
  299         g_trace(G_T_BIO, "bio_getattr(%s)", attr);
  300         bp = g_alloc_bio();
  301         bp->bio_cmd = BIO_GETATTR;
  302         bp->bio_done = NULL;
  303         bp->bio_attribute = attr;
  304         bp->bio_length = *len;
  305         bp->bio_data = ptr;
  306         g_io_request(bp, cp);
  307         error = biowait(bp, "ggetattr");
  308         *len = bp->bio_completed;
  309         g_destroy_bio(bp);
  310         return (error);
  311 }
  312 
  313 int
  314 g_io_zonecmd(struct disk_zone_args *zone_args, struct g_consumer *cp)
  315 {
  316         struct bio *bp;
  317         int error;
  318         
  319         g_trace(G_T_BIO, "bio_zone(%d)", zone_args->zone_cmd);
  320         bp = g_alloc_bio();
  321         bp->bio_cmd = BIO_ZONE;
  322         bp->bio_done = NULL;
  323         /*
  324          * XXX KDM need to handle report zone data.
  325          */
  326         bcopy(zone_args, &bp->bio_zone, sizeof(*zone_args));
  327         if (zone_args->zone_cmd == DISK_ZONE_REPORT_ZONES)
  328                 bp->bio_length =
  329                     zone_args->zone_params.report.entries_allocated *
  330                     sizeof(struct disk_zone_rep_entry);
  331         else
  332                 bp->bio_length = 0;
  333 
  334         g_io_request(bp, cp);
  335         error = biowait(bp, "gzone");
  336         bcopy(&bp->bio_zone, zone_args, sizeof(*zone_args));
  337         g_destroy_bio(bp);
  338         return (error);
  339 }
  340 
  341 int
  342 g_io_flush(struct g_consumer *cp)
  343 {
  344         struct bio *bp;
  345         int error;
  346 
  347         g_trace(G_T_BIO, "bio_flush(%s)", cp->provider->name);
  348         bp = g_alloc_bio();
  349         bp->bio_cmd = BIO_FLUSH;
  350         bp->bio_flags |= BIO_ORDERED;
  351         bp->bio_done = NULL;
  352         bp->bio_attribute = NULL;
  353         bp->bio_offset = cp->provider->mediasize;
  354         bp->bio_length = 0;
  355         bp->bio_data = NULL;
  356         g_io_request(bp, cp);
  357         error = biowait(bp, "gflush");
  358         g_destroy_bio(bp);
  359         return (error);
  360 }
  361 
  362 static int
  363 g_io_check(struct bio *bp)
  364 {
  365         struct g_consumer *cp;
  366         struct g_provider *pp;
  367         off_t excess;
  368         int error;
  369 
  370         biotrack(bp, __func__);
  371 
  372         cp = bp->bio_from;
  373         pp = bp->bio_to;
  374 
  375         /* Fail if access counters dont allow the operation */
  376         switch(bp->bio_cmd) {
  377         case BIO_READ:
  378         case BIO_GETATTR:
  379                 if (cp->acr == 0)
  380                         return (EPERM);
  381                 break;
  382         case BIO_WRITE:
  383         case BIO_DELETE:
  384         case BIO_FLUSH:
  385                 if (cp->acw == 0)
  386                         return (EPERM);
  387                 break;
  388         case BIO_ZONE:
  389                 if ((bp->bio_zone.zone_cmd == DISK_ZONE_REPORT_ZONES) ||
  390                     (bp->bio_zone.zone_cmd == DISK_ZONE_GET_PARAMS)) {
  391                         if (cp->acr == 0)
  392                                 return (EPERM);
  393                 } else if (cp->acw == 0)
  394                         return (EPERM);
  395                 break;
  396         default:
  397                 return (EPERM);
  398         }
  399         /* if provider is marked for error, don't disturb. */
  400         if (pp->error)
  401                 return (pp->error);
  402         if (cp->flags & G_CF_ORPHAN)
  403                 return (ENXIO);
  404 
  405         switch(bp->bio_cmd) {
  406         case BIO_READ:
  407         case BIO_WRITE:
  408         case BIO_DELETE:
  409                 /* Zero sectorsize or mediasize is probably a lack of media. */
  410                 if (pp->sectorsize == 0 || pp->mediasize == 0)
  411                         return (ENXIO);
  412                 /* Reject I/O not on sector boundary */
  413                 if (bp->bio_offset % pp->sectorsize)
  414                         return (EINVAL);
  415                 /* Reject I/O not integral sector long */
  416                 if (bp->bio_length % pp->sectorsize)
  417                         return (EINVAL);
  418                 /* Reject requests before or past the end of media. */
  419                 if (bp->bio_offset < 0)
  420                         return (EIO);
  421                 if (bp->bio_offset > pp->mediasize)
  422                         return (EIO);
  423 
  424                 /* Truncate requests to the end of providers media. */
  425                 excess = bp->bio_offset + bp->bio_length;
  426                 if (excess > bp->bio_to->mediasize) {
  427                         KASSERT((bp->bio_flags & BIO_UNMAPPED) == 0 ||
  428                             round_page(bp->bio_ma_offset +
  429                             bp->bio_length) / PAGE_SIZE == bp->bio_ma_n,
  430                             ("excess bio %p too short", bp));
  431                         excess -= bp->bio_to->mediasize;
  432                         bp->bio_length -= excess;
  433                         if ((bp->bio_flags & BIO_UNMAPPED) != 0) {
  434                                 bp->bio_ma_n = round_page(bp->bio_ma_offset +
  435                                     bp->bio_length) / PAGE_SIZE;
  436                         }
  437                         if (excess > 0)
  438                                 CTR3(KTR_GEOM, "g_down truncated bio "
  439                                     "%p provider %s by %d", bp,
  440                                     bp->bio_to->name, excess);
  441                 }
  442 
  443                 /* Deliver zero length transfers right here. */
  444                 if (bp->bio_length == 0) {
  445                         CTR2(KTR_GEOM, "g_down terminated 0-length "
  446                             "bp %p provider %s", bp, bp->bio_to->name);
  447                         return (0);
  448                 }
  449 
  450                 if ((bp->bio_flags & BIO_UNMAPPED) != 0 &&
  451                     (bp->bio_to->flags & G_PF_ACCEPT_UNMAPPED) == 0 &&
  452                     (bp->bio_cmd == BIO_READ || bp->bio_cmd == BIO_WRITE)) {
  453                         if ((error = g_io_transient_map_bio(bp)) >= 0)
  454                                 return (error);
  455                 }
  456                 break;
  457         default:
  458                 break;
  459         }
  460         return (EJUSTRETURN);
  461 }
  462 
  463 /*
  464  * bio classification support.
  465  *
  466  * g_register_classifier() and g_unregister_classifier()
  467  * are used to add/remove a classifier from the list.
  468  * The list is protected using the g_bio_run_down lock,
  469  * because the classifiers are called in this path.
  470  *
  471  * g_io_request() passes bio's that are not already classified
  472  * (i.e. those with bio_classifier1 == NULL) to g_run_classifiers().
  473  * Classifiers can store their result in the two fields
  474  * bio_classifier1 and bio_classifier2.
  475  * A classifier that updates one of the fields should
  476  * return a non-zero value.
  477  * If no classifier updates the field, g_run_classifiers() sets
  478  * bio_classifier1 = BIO_NOTCLASSIFIED to avoid further calls.
  479  */
  480 
  481 int
  482 g_register_classifier(struct g_classifier_hook *hook)
  483 {
  484 
  485         g_bioq_lock(&g_bio_run_down);
  486         TAILQ_INSERT_TAIL(&g_classifier_tailq, hook, link);
  487         g_bioq_unlock(&g_bio_run_down);
  488 
  489         return (0);
  490 }
  491 
  492 void
  493 g_unregister_classifier(struct g_classifier_hook *hook)
  494 {
  495         struct g_classifier_hook *entry;
  496 
  497         g_bioq_lock(&g_bio_run_down);
  498         TAILQ_FOREACH(entry, &g_classifier_tailq, link) {
  499                 if (entry == hook) {
  500                         TAILQ_REMOVE(&g_classifier_tailq, hook, link);
  501                         break;
  502                 }
  503         }
  504         g_bioq_unlock(&g_bio_run_down);
  505 }
  506 
  507 static void
  508 g_run_classifiers(struct bio *bp)
  509 {
  510         struct g_classifier_hook *hook;
  511         int classified = 0;
  512 
  513         biotrack(bp, __func__);
  514 
  515         TAILQ_FOREACH(hook, &g_classifier_tailq, link)
  516                 classified |= hook->func(hook->arg, bp);
  517 
  518         if (!classified)
  519                 bp->bio_classifier1 = BIO_NOTCLASSIFIED;
  520 }
  521 
  522 void
  523 g_io_request(struct bio *bp, struct g_consumer *cp)
  524 {
  525         struct g_provider *pp;
  526         struct mtx *mtxp;
  527         int direct, error, first;
  528         uint8_t cmd;
  529 
  530         biotrack(bp, __func__);
  531 
  532         KASSERT(cp != NULL, ("NULL cp in g_io_request"));
  533         KASSERT(bp != NULL, ("NULL bp in g_io_request"));
  534         pp = cp->provider;
  535         KASSERT(pp != NULL, ("consumer not attached in g_io_request"));
  536 #ifdef DIAGNOSTIC
  537         KASSERT(bp->bio_driver1 == NULL,
  538             ("bio_driver1 used by the consumer (geom %s)", cp->geom->name));
  539         KASSERT(bp->bio_driver2 == NULL,
  540             ("bio_driver2 used by the consumer (geom %s)", cp->geom->name));
  541         KASSERT(bp->bio_pflags == 0,
  542             ("bio_pflags used by the consumer (geom %s)", cp->geom->name));
  543         /*
  544          * Remember consumer's private fields, so we can detect if they were
  545          * modified by the provider.
  546          */
  547         bp->_bio_caller1 = bp->bio_caller1;
  548         bp->_bio_caller2 = bp->bio_caller2;
  549         bp->_bio_cflags = bp->bio_cflags;
  550 #endif
  551 
  552         cmd = bp->bio_cmd;
  553         if (cmd == BIO_READ || cmd == BIO_WRITE || cmd == BIO_GETATTR) {
  554                 KASSERT(bp->bio_data != NULL,
  555                     ("NULL bp->data in g_io_request(cmd=%hu)", bp->bio_cmd));
  556         }
  557         if (cmd == BIO_DELETE || cmd == BIO_FLUSH) {
  558                 KASSERT(bp->bio_data == NULL,
  559                     ("non-NULL bp->data in g_io_request(cmd=%hu)",
  560                     bp->bio_cmd));
  561         }
  562         if (cmd == BIO_READ || cmd == BIO_WRITE || cmd == BIO_DELETE) {
  563                 KASSERT(bp->bio_offset % cp->provider->sectorsize == 0,
  564                     ("wrong offset %jd for sectorsize %u",
  565                     bp->bio_offset, cp->provider->sectorsize));
  566                 KASSERT(bp->bio_length % cp->provider->sectorsize == 0,
  567                     ("wrong length %jd for sectorsize %u",
  568                     bp->bio_length, cp->provider->sectorsize));
  569         }
  570 
  571         g_trace(G_T_BIO, "bio_request(%p) from %p(%s) to %p(%s) cmd %d",
  572             bp, cp, cp->geom->name, pp, pp->name, bp->bio_cmd);
  573 
  574         bp->bio_from = cp;
  575         bp->bio_to = pp;
  576         bp->bio_error = 0;
  577         bp->bio_completed = 0;
  578 
  579         KASSERT(!(bp->bio_flags & BIO_ONQUEUE),
  580             ("Bio already on queue bp=%p", bp));
  581         if ((g_collectstats & G_STATS_CONSUMERS) != 0 ||
  582             ((g_collectstats & G_STATS_PROVIDERS) != 0 && pp->stat != NULL))
  583                 binuptime(&bp->bio_t0);
  584         else
  585                 getbinuptime(&bp->bio_t0);
  586 
  587 #ifdef GET_STACK_USAGE
  588         direct = (cp->flags & G_CF_DIRECT_SEND) != 0 &&
  589             (pp->flags & G_PF_DIRECT_RECEIVE) != 0 &&
  590             !g_is_geom_thread(curthread) &&
  591             ((pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ||
  592             (bp->bio_flags & BIO_UNMAPPED) == 0 || THREAD_CAN_SLEEP()) &&
  593             pace == 0;
  594         if (direct) {
  595                 /* Block direct execution if less then half of stack left. */
  596                 size_t  st, su;
  597                 GET_STACK_USAGE(st, su);
  598                 if (su * 2 > st)
  599                         direct = 0;
  600         }
  601 #else
  602         direct = 0;
  603 #endif
  604 
  605         if (!TAILQ_EMPTY(&g_classifier_tailq) && !bp->bio_classifier1) {
  606                 g_bioq_lock(&g_bio_run_down);
  607                 g_run_classifiers(bp);
  608                 g_bioq_unlock(&g_bio_run_down);
  609         }
  610 
  611         /*
  612          * The statistics collection is lockless, as such, but we
  613          * can not update one instance of the statistics from more
  614          * than one thread at a time, so grab the lock first.
  615          */
  616         mtxp = mtx_pool_find(mtxpool_sleep, pp);
  617         mtx_lock(mtxp);
  618         if (g_collectstats & G_STATS_PROVIDERS)
  619                 devstat_start_transaction(pp->stat, &bp->bio_t0);
  620         if (g_collectstats & G_STATS_CONSUMERS)
  621                 devstat_start_transaction(cp->stat, &bp->bio_t0);
  622         pp->nstart++;
  623         cp->nstart++;
  624         mtx_unlock(mtxp);
  625 
  626         if (direct) {
  627                 error = g_io_check(bp);
  628                 if (error >= 0) {
  629                         CTR3(KTR_GEOM, "g_io_request g_io_check on bp %p "
  630                             "provider %s returned %d", bp, bp->bio_to->name,
  631                             error);
  632                         g_io_deliver(bp, error);
  633                         return;
  634                 }
  635                 bp->bio_to->geom->start(bp);
  636         } else {
  637                 g_bioq_lock(&g_bio_run_down);
  638                 first = TAILQ_EMPTY(&g_bio_run_down.bio_queue);
  639                 TAILQ_INSERT_TAIL(&g_bio_run_down.bio_queue, bp, bio_queue);
  640                 bp->bio_flags |= BIO_ONQUEUE;
  641                 g_bio_run_down.bio_queue_length++;
  642                 g_bioq_unlock(&g_bio_run_down);
  643                 /* Pass it on down. */
  644                 if (first)
  645                         wakeup(&g_wait_down);
  646         }
  647 }
  648 
  649 void
  650 g_io_deliver(struct bio *bp, int error)
  651 {
  652         struct bintime now;
  653         struct g_consumer *cp;
  654         struct g_provider *pp;
  655         struct mtx *mtxp;
  656         int direct, first;
  657 
  658         biotrack(bp, __func__);
  659 
  660         KASSERT(bp != NULL, ("NULL bp in g_io_deliver"));
  661         pp = bp->bio_to;
  662         KASSERT(pp != NULL, ("NULL bio_to in g_io_deliver"));
  663         cp = bp->bio_from;
  664         if (cp == NULL) {
  665                 bp->bio_error = error;
  666                 bp->bio_done(bp);
  667                 return;
  668         }
  669         KASSERT(cp != NULL, ("NULL bio_from in g_io_deliver"));
  670         KASSERT(cp->geom != NULL, ("NULL bio_from->geom in g_io_deliver"));
  671 #ifdef DIAGNOSTIC
  672         /*
  673          * Some classes - GJournal in particular - can modify bio's
  674          * private fields while the bio is in transit; G_GEOM_VOLATILE_BIO
  675          * flag means it's an expected behaviour for that particular geom.
  676          */
  677         if ((cp->geom->flags & G_GEOM_VOLATILE_BIO) == 0) {
  678                 KASSERT(bp->bio_caller1 == bp->_bio_caller1,
  679                     ("bio_caller1 used by the provider %s", pp->name));
  680                 KASSERT(bp->bio_caller2 == bp->_bio_caller2,
  681                     ("bio_caller2 used by the provider %s", pp->name));
  682                 KASSERT(bp->bio_cflags == bp->_bio_cflags,
  683                     ("bio_cflags used by the provider %s", pp->name));
  684         }
  685 #endif
  686         KASSERT(bp->bio_completed >= 0, ("bio_completed can't be less than 0"));
  687         KASSERT(bp->bio_completed <= bp->bio_length,
  688             ("bio_completed can't be greater than bio_length"));
  689 
  690         g_trace(G_T_BIO,
  691 "g_io_deliver(%p) from %p(%s) to %p(%s) cmd %d error %d off %jd len %jd",
  692             bp, cp, cp->geom->name, pp, pp->name, bp->bio_cmd, error,
  693             (intmax_t)bp->bio_offset, (intmax_t)bp->bio_length);
  694 
  695         KASSERT(!(bp->bio_flags & BIO_ONQUEUE),
  696             ("Bio already on queue bp=%p", bp));
  697 
  698         /*
  699          * XXX: next two doesn't belong here
  700          */
  701         bp->bio_bcount = bp->bio_length;
  702         bp->bio_resid = bp->bio_bcount - bp->bio_completed;
  703 
  704 #ifdef GET_STACK_USAGE
  705         direct = (pp->flags & G_PF_DIRECT_SEND) &&
  706                  (cp->flags & G_CF_DIRECT_RECEIVE) &&
  707                  !g_is_geom_thread(curthread);
  708         if (direct) {
  709                 /* Block direct execution if less then half of stack left. */
  710                 size_t  st, su;
  711                 GET_STACK_USAGE(st, su);
  712                 if (su * 2 > st)
  713                         direct = 0;
  714         }
  715 #else
  716         direct = 0;
  717 #endif
  718 
  719         /*
  720          * The statistics collection is lockless, as such, but we
  721          * can not update one instance of the statistics from more
  722          * than one thread at a time, so grab the lock first.
  723          */
  724         if ((g_collectstats & G_STATS_CONSUMERS) != 0 ||
  725             ((g_collectstats & G_STATS_PROVIDERS) != 0 && pp->stat != NULL))
  726                 binuptime(&now);
  727         mtxp = mtx_pool_find(mtxpool_sleep, cp);
  728         mtx_lock(mtxp);
  729         if (g_collectstats & G_STATS_PROVIDERS)
  730                 devstat_end_transaction_bio_bt(pp->stat, bp, &now);
  731         if (g_collectstats & G_STATS_CONSUMERS)
  732                 devstat_end_transaction_bio_bt(cp->stat, bp, &now);
  733         cp->nend++;
  734         pp->nend++;
  735         mtx_unlock(mtxp);
  736 
  737         if (error != ENOMEM) {
  738                 bp->bio_error = error;
  739                 if (direct) {
  740                         biodone(bp);
  741                 } else {
  742                         g_bioq_lock(&g_bio_run_up);
  743                         first = TAILQ_EMPTY(&g_bio_run_up.bio_queue);
  744                         TAILQ_INSERT_TAIL(&g_bio_run_up.bio_queue, bp, bio_queue);
  745                         bp->bio_flags |= BIO_ONQUEUE;
  746                         g_bio_run_up.bio_queue_length++;
  747                         g_bioq_unlock(&g_bio_run_up);
  748                         if (first)
  749                                 wakeup(&g_wait_up);
  750                 }
  751                 return;
  752         }
  753 
  754         if (bootverbose)
  755                 printf("ENOMEM %p on %p(%s)\n", bp, pp, pp->name);
  756         bp->bio_children = 0;
  757         bp->bio_inbed = 0;
  758         bp->bio_driver1 = NULL;
  759         bp->bio_driver2 = NULL;
  760         bp->bio_pflags = 0;
  761         g_io_request(bp, cp);
  762         pace = 1;
  763         return;
  764 }
  765 
  766 SYSCTL_DECL(_kern_geom);
  767 
  768 static long transient_maps;
  769 SYSCTL_LONG(_kern_geom, OID_AUTO, transient_maps, CTLFLAG_RD,
  770     &transient_maps, 0,
  771     "Total count of the transient mapping requests");
  772 u_int transient_map_retries = 10;
  773 SYSCTL_UINT(_kern_geom, OID_AUTO, transient_map_retries, CTLFLAG_RW,
  774     &transient_map_retries, 0,
  775     "Max count of retries used before giving up on creating transient map");
  776 int transient_map_hard_failures;
  777 SYSCTL_INT(_kern_geom, OID_AUTO, transient_map_hard_failures, CTLFLAG_RD,
  778     &transient_map_hard_failures, 0,
  779     "Failures to establish the transient mapping due to retry attempts "
  780     "exhausted");
  781 int transient_map_soft_failures;
  782 SYSCTL_INT(_kern_geom, OID_AUTO, transient_map_soft_failures, CTLFLAG_RD,
  783     &transient_map_soft_failures, 0,
  784     "Count of retried failures to establish the transient mapping");
  785 int inflight_transient_maps;
  786 SYSCTL_INT(_kern_geom, OID_AUTO, inflight_transient_maps, CTLFLAG_RD,
  787     &inflight_transient_maps, 0,
  788     "Current count of the active transient maps");
  789 
  790 static int
  791 g_io_transient_map_bio(struct bio *bp)
  792 {
  793         vm_offset_t addr;
  794         long size;
  795         u_int retried;
  796 
  797         KASSERT(unmapped_buf_allowed, ("unmapped disabled"));
  798 
  799         size = round_page(bp->bio_ma_offset + bp->bio_length);
  800         KASSERT(size / PAGE_SIZE == bp->bio_ma_n, ("Bio too short %p", bp));
  801         addr = 0;
  802         retried = 0;
  803         atomic_add_long(&transient_maps, 1);
  804 retry:
  805         if (vmem_alloc(transient_arena, size, M_BESTFIT | M_NOWAIT, &addr)) {
  806                 if (transient_map_retries != 0 &&
  807                     retried >= transient_map_retries) {
  808                         CTR2(KTR_GEOM, "g_down cannot map bp %p provider %s",
  809                             bp, bp->bio_to->name);
  810                         atomic_add_int(&transient_map_hard_failures, 1);
  811                         return (EDEADLK/* XXXKIB */);
  812                 } else {
  813                         /*
  814                          * Naive attempt to quisce the I/O to get more
  815                          * in-flight requests completed and defragment
  816                          * the transient_arena.
  817                          */
  818                         CTR3(KTR_GEOM, "g_down retrymap bp %p provider %s r %d",
  819                             bp, bp->bio_to->name, retried);
  820                         pause("g_d_tra", hz / 10);
  821                         retried++;
  822                         atomic_add_int(&transient_map_soft_failures, 1);
  823                         goto retry;
  824                 }
  825         }
  826         atomic_add_int(&inflight_transient_maps, 1);
  827         pmap_qenter((vm_offset_t)addr, bp->bio_ma, OFF_TO_IDX(size));
  828         bp->bio_data = (caddr_t)addr + bp->bio_ma_offset;
  829         bp->bio_flags |= BIO_TRANSIENT_MAPPING;
  830         bp->bio_flags &= ~BIO_UNMAPPED;
  831         return (EJUSTRETURN);
  832 }
  833 
  834 void
  835 g_io_schedule_down(struct thread *tp __unused)
  836 {
  837         struct bio *bp;
  838         int error;
  839 
  840         for(;;) {
  841                 g_bioq_lock(&g_bio_run_down);
  842                 bp = g_bioq_first(&g_bio_run_down);
  843                 if (bp == NULL) {
  844                         CTR0(KTR_GEOM, "g_down going to sleep");
  845                         msleep(&g_wait_down, &g_bio_run_down.bio_queue_lock,
  846                             PRIBIO | PDROP, "-", 0);
  847                         continue;
  848                 }
  849                 CTR0(KTR_GEOM, "g_down has work to do");
  850                 g_bioq_unlock(&g_bio_run_down);
  851                 biotrack(bp, __func__);
  852                 if (pace != 0) {
  853                         /*
  854                          * There has been at least one memory allocation
  855                          * failure since the last I/O completed. Pause 1ms to
  856                          * give the system a chance to free up memory. We only
  857                          * do this once because a large number of allocations
  858                          * can fail in the direct dispatch case and there's no
  859                          * relationship between the number of these failures and
  860                          * the length of the outage. If there's still an outage,
  861                          * we'll pause again and again until it's
  862                          * resolved. Older versions paused longer and once per
  863                          * allocation failure. This was OK for a single threaded
  864                          * g_down, but with direct dispatch would lead to max of
  865                          * 10 IOPs for minutes at a time when transient memory
  866                          * issues prevented allocation for a batch of requests
  867                          * from the upper layers.
  868                          *
  869                          * XXX This pacing is really lame. It needs to be solved
  870                          * by other methods. This is OK only because the worst
  871                          * case scenario is so rare. In the worst case scenario
  872                          * all memory is tied up waiting for I/O to complete
  873                          * which can never happen since we can't allocate bios
  874                          * for that I/O.
  875                          */
  876                         CTR0(KTR_GEOM, "g_down pacing self");
  877                         pause("g_down", min(hz/1000, 1));
  878                         pace = 0;
  879                 }
  880                 CTR2(KTR_GEOM, "g_down processing bp %p provider %s", bp,
  881                     bp->bio_to->name);
  882                 error = g_io_check(bp);
  883                 if (error >= 0) {
  884                         CTR3(KTR_GEOM, "g_down g_io_check on bp %p provider "
  885                             "%s returned %d", bp, bp->bio_to->name, error);
  886                         g_io_deliver(bp, error);
  887                         continue;
  888                 }
  889                 THREAD_NO_SLEEPING();
  890                 CTR4(KTR_GEOM, "g_down starting bp %p provider %s off %ld "
  891                     "len %ld", bp, bp->bio_to->name, bp->bio_offset,
  892                     bp->bio_length);
  893                 bp->bio_to->geom->start(bp);
  894                 THREAD_SLEEPING_OK();
  895         }
  896 }
  897 
  898 void
  899 g_io_schedule_up(struct thread *tp __unused)
  900 {
  901         struct bio *bp;
  902 
  903         for(;;) {
  904                 g_bioq_lock(&g_bio_run_up);
  905                 bp = g_bioq_first(&g_bio_run_up);
  906                 if (bp == NULL) {
  907                         CTR0(KTR_GEOM, "g_up going to sleep");
  908                         msleep(&g_wait_up, &g_bio_run_up.bio_queue_lock,
  909                             PRIBIO | PDROP, "-", 0);
  910                         continue;
  911                 }
  912                 g_bioq_unlock(&g_bio_run_up);
  913                 THREAD_NO_SLEEPING();
  914                 CTR4(KTR_GEOM, "g_up biodone bp %p provider %s off "
  915                     "%jd len %ld", bp, bp->bio_to->name,
  916                     bp->bio_offset, bp->bio_length);
  917                 biodone(bp);
  918                 THREAD_SLEEPING_OK();
  919         }
  920 }
  921 
  922 void *
  923 g_read_data(struct g_consumer *cp, off_t offset, off_t length, int *error)
  924 {
  925         struct bio *bp;
  926         void *ptr;
  927         int errorc;
  928 
  929         KASSERT(length > 0 && length >= cp->provider->sectorsize &&
  930             length <= MAXPHYS, ("g_read_data(): invalid length %jd",
  931             (intmax_t)length));
  932 
  933         bp = g_alloc_bio();
  934         bp->bio_cmd = BIO_READ;
  935         bp->bio_done = NULL;
  936         bp->bio_offset = offset;
  937         bp->bio_length = length;
  938         ptr = g_malloc(length, M_WAITOK);
  939         bp->bio_data = ptr;
  940         g_io_request(bp, cp);
  941         errorc = biowait(bp, "gread");
  942         if (error != NULL)
  943                 *error = errorc;
  944         g_destroy_bio(bp);
  945         if (errorc) {
  946                 g_free(ptr);
  947                 ptr = NULL;
  948         }
  949         return (ptr);
  950 }
  951 
  952 /*
  953  * A read function for use by ffs_sbget when used by GEOM-layer routines.
  954  */
  955 int
  956 g_use_g_read_data(void *devfd, off_t loc, void **bufp, int size)
  957 {
  958         struct g_consumer *cp;
  959 
  960         KASSERT(*bufp == NULL,
  961             ("g_use_g_read_data: non-NULL *bufp %p\n", *bufp));
  962 
  963         cp = (struct g_consumer *)devfd;
  964         /*
  965          * Take care not to issue an invalid I/O request. The offset of
  966          * the superblock candidate must be multiples of the provider's
  967          * sector size, otherwise an FFS can't exist on the provider
  968          * anyway.
  969          */
  970         if (loc % cp->provider->sectorsize != 0)
  971                 return (ENOENT);
  972         *bufp = g_read_data(cp, loc, size, NULL);
  973         if (*bufp == NULL)
  974                 return (ENOENT);
  975         return (0);
  976 }
  977 
  978 int
  979 g_write_data(struct g_consumer *cp, off_t offset, void *ptr, off_t length)
  980 {
  981         struct bio *bp;
  982         int error;
  983 
  984         KASSERT(length > 0 && length >= cp->provider->sectorsize &&
  985             length <= MAXPHYS, ("g_write_data(): invalid length %jd",
  986             (intmax_t)length));
  987 
  988         bp = g_alloc_bio();
  989         bp->bio_cmd = BIO_WRITE;
  990         bp->bio_done = NULL;
  991         bp->bio_offset = offset;
  992         bp->bio_length = length;
  993         bp->bio_data = ptr;
  994         g_io_request(bp, cp);
  995         error = biowait(bp, "gwrite");
  996         g_destroy_bio(bp);
  997         return (error);
  998 }
  999 
 1000 /*
 1001  * A write function for use by ffs_sbput when used by GEOM-layer routines.
 1002  */
 1003 int
 1004 g_use_g_write_data(void *devfd, off_t loc, void *buf, int size)
 1005 {
 1006 
 1007         return (g_write_data((struct g_consumer *)devfd, loc, buf, size));
 1008 }
 1009 
 1010 int
 1011 g_delete_data(struct g_consumer *cp, off_t offset, off_t length)
 1012 {
 1013         struct bio *bp;
 1014         int error;
 1015 
 1016         KASSERT(length > 0 && length >= cp->provider->sectorsize,
 1017             ("g_delete_data(): invalid length %jd", (intmax_t)length));
 1018 
 1019         bp = g_alloc_bio();
 1020         bp->bio_cmd = BIO_DELETE;
 1021         bp->bio_done = NULL;
 1022         bp->bio_offset = offset;
 1023         bp->bio_length = length;
 1024         bp->bio_data = NULL;
 1025         g_io_request(bp, cp);
 1026         error = biowait(bp, "gdelete");
 1027         g_destroy_bio(bp);
 1028         return (error);
 1029 }
 1030 
 1031 void
 1032 g_print_bio(struct bio *bp)
 1033 {
 1034         const char *pname, *cmd = NULL;
 1035 
 1036         if (bp->bio_to != NULL)
 1037                 pname = bp->bio_to->name;
 1038         else
 1039                 pname = "[unknown]";
 1040 
 1041         switch (bp->bio_cmd) {
 1042         case BIO_GETATTR:
 1043                 cmd = "GETATTR";
 1044                 printf("%s[%s(attr=%s)]", pname, cmd, bp->bio_attribute);
 1045                 return;
 1046         case BIO_FLUSH:
 1047                 cmd = "FLUSH";
 1048                 printf("%s[%s]", pname, cmd);
 1049                 return;
 1050         case BIO_ZONE: {
 1051                 char *subcmd = NULL;
 1052                 cmd = "ZONE";
 1053                 switch (bp->bio_zone.zone_cmd) {
 1054                 case DISK_ZONE_OPEN:
 1055                         subcmd = "OPEN";
 1056                         break;
 1057                 case DISK_ZONE_CLOSE:
 1058                         subcmd = "CLOSE";
 1059                         break;
 1060                 case DISK_ZONE_FINISH:
 1061                         subcmd = "FINISH";
 1062                         break;
 1063                 case DISK_ZONE_RWP:
 1064                         subcmd = "RWP";
 1065                         break;
 1066                 case DISK_ZONE_REPORT_ZONES:
 1067                         subcmd = "REPORT ZONES";
 1068                         break;
 1069                 case DISK_ZONE_GET_PARAMS:
 1070                         subcmd = "GET PARAMS";
 1071                         break;
 1072                 default:
 1073                         subcmd = "UNKNOWN";
 1074                         break;
 1075                 }
 1076                 printf("%s[%s,%s]", pname, cmd, subcmd);
 1077                 return;
 1078         }
 1079         case BIO_READ:
 1080                 cmd = "READ";
 1081                 break;
 1082         case BIO_WRITE:
 1083                 cmd = "WRITE";
 1084                 break;
 1085         case BIO_DELETE:
 1086                 cmd = "DELETE";
 1087                 break;
 1088         default:
 1089                 cmd = "UNKNOWN";
 1090                 printf("%s[%s()]", pname, cmd);
 1091                 return;
 1092         }
 1093         printf("%s[%s(offset=%jd, length=%jd)]", pname, cmd,
 1094             (intmax_t)bp->bio_offset, (intmax_t)bp->bio_length);
 1095 }

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