sys/geom/geom_fox.c

   1 /*-
   2  * Copyright (c) 2003 Poul-Henning Kamp
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. The names of the authors may not be used to endorse or promote
  14  *    products derived from this software without specific prior written
  15  *    permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD$
  30  */
  31
  32 /* This is a GEOM module for handling path selection for multi-path
  33  * storage devices.  It is named "fox" because it, like they, prefer
  34  * to have multiple exits to choose from.
  35  *
  36  */
  37
  38 #include <sys/param.h>
  39 #include <sys/systm.h>
  40 #include <sys/sysctl.h>
  41 #include <sys/kernel.h>
  42 #include <sys/conf.h>
  43 #include <sys/bio.h>
  44 #include <sys/malloc.h>
  45 #include <sys/lock.h>
  46 #include <sys/mutex.h>
  47 #include <sys/libkern.h>
  48 #include <sys/endian.h>
  49 #include <sys/md5.h>
  50 #include <sys/errno.h>
  51 #include <geom/geom.h>
  52
  53 #define FOX_CLASS_NAME "FOX"
  54 #define FOX_MAGIC       "GEOM::FOX"
  55
  56 FEATURE(geom_fox, "GEOM FOX redundant path mitigation support");
  57
  58 struct g_fox_softc {
  59         off_t                   mediasize;
  60         u_int                   sectorsize;
  61         TAILQ_HEAD(, bio)       queue;
  62         struct mtx              lock;
  63         u_char                  magic[16];
  64         struct g_consumer       *path;
  65         struct g_consumer       *opath;
  66         int                     waiting;
  67         int                     cr, cw, ce;
  68 };
  69
  70 /*
  71  * This function is called whenever we need to select a new path.
  72  */
  73 static void
  74 g_fox_select_path(void *arg, int flag)
  75 {
  76         struct g_geom *gp;
  77         struct g_fox_softc *sc;
  78         struct g_consumer *cp1;
  79         struct bio *bp;
  80         int error;
  81
  82         g_topology_assert();
  83         if (flag == EV_CANCEL)
  84                 return;
  85         gp = arg;
  86         sc = gp->softc;
  87
  88         if (sc->opath != NULL) {
  89                 /*
  90                  * First, close the old path entirely.
  91                  */
  92                 printf("Closing old path (%s) on fox (%s)\n",
  93                         sc->opath->provider->name, gp->name);
  94
  95                 cp1 = LIST_NEXT(sc->opath, consumer);
  96
  97                 g_access(sc->opath, -sc->cr, -sc->cw, -(sc->ce + 1));
  98
  99                 /*
 100                  * The attempt to reopen it with a exclusive count
 101                  */
 102                 error = g_access(sc->opath, 0, 0, 1);
 103                 if (error) {
 104                         /*
 105                          * Ok, ditch this consumer, we can't use it.
 106                          */
 107                         printf("Drop old path (%s) on fox (%s)\n",
 108                                 sc->opath->provider->name, gp->name);
 109                         g_detach(sc->opath);
 110                         g_destroy_consumer(sc->opath);
 111                         if (LIST_EMPTY(&gp->consumer)) {
 112                                 /* No consumers left */
 113                                 g_wither_geom(gp, ENXIO);
 114                                 for (;;) {
 115                                         bp = TAILQ_FIRST(&sc->queue);
 116                                         if (bp == NULL)
 117                                                 break;
 118                                         TAILQ_REMOVE(&sc->queue, bp, bio_queue);
 119                                         bp->bio_error = ENXIO;
 120                                         g_std_done(bp);
 121                                 }
 122                                 return;
 123                         }
 124                 } else {
 125                         printf("Got e-bit on old path (%s) on fox (%s)\n",
 126                                 sc->opath->provider->name, gp->name);
 127                 }
 128                 sc->opath = NULL;
 129         } else {
 130                 cp1 = LIST_FIRST(&gp->consumer);
 131         }
 132         if (cp1 == NULL)
 133                 cp1 = LIST_FIRST(&gp->consumer);
 134         printf("Open new path (%s) on fox (%s)\n",
 135                 cp1->provider->name, gp->name);
 136         error = g_access(cp1, sc->cr, sc->cw, sc->ce);
 137         if (error) {
 138                 /*
 139                  * If we failed, we take another trip through here
 140                  */
 141                 printf("Open new path (%s) on fox (%s) failed, reselect.\n",
 142                         cp1->provider->name, gp->name);
 143                 sc->opath = cp1;
 144                 g_post_event(g_fox_select_path, gp, M_WAITOK, gp, NULL);
 145         } else {
 146                 printf("Open new path (%s) on fox (%s) succeeded\n",
 147                         cp1->provider->name, gp->name);
 148                 mtx_lock(&sc->lock);
 149                 sc->path = cp1;
 150                 sc->waiting = 0;
 151                 for (;;) {
 152                         bp = TAILQ_FIRST(&sc->queue);
 153                         if (bp == NULL)
 154                                 break;
 155                         TAILQ_REMOVE(&sc->queue, bp, bio_queue);
 156                         g_io_request(bp, sc->path);
 157                 }
 158                 mtx_unlock(&sc->lock);
 159         }
 160 }
 161
 162 static void
 163 g_fox_orphan(struct g_consumer *cp)
 164 {
 165         struct g_geom *gp;
 166         struct g_fox_softc *sc;
 167         int error, mark;
 168
 169         g_topology_assert();
 170         gp = cp->geom;
 171         sc = gp->softc;
 172         printf("Removing path (%s) from fox (%s)\n",
 173             cp->provider->name, gp->name);
 174         mtx_lock(&sc->lock);
 175         if (cp == sc->path) {
 176                 sc->opath = NULL;
 177                 sc->path = NULL;
 178                 sc->waiting = 1;
 179                 mark = 1;
 180         } else {
 181                 mark = 0;
 182         }
 183         mtx_unlock(&sc->lock);
 184
 185         g_access(cp, -cp->acr, -cp->acw, -cp->ace);
 186         error = cp->provider->error;
 187         g_detach(cp);
 188         g_destroy_consumer(cp);
 189         if (!LIST_EMPTY(&gp->consumer)) {
 190                 if (mark)
 191                         g_post_event(g_fox_select_path, gp, M_WAITOK, gp, NULL);
 192                 return;
 193         }
 194
 195         mtx_destroy(&sc->lock);
 196         g_free(gp->softc);
 197         gp->softc = NULL;
 198         g_wither_geom(gp, ENXIO);
 199 }
 200
 201 static void
 202 g_fox_done(struct bio *bp)
 203 {
 204         struct g_geom *gp;
 205         struct g_fox_softc *sc;
 206         int error;
 207
 208         if (bp->bio_error == 0) {
 209                 g_std_done(bp);
 210                 return;
 211         }
 212         gp = bp->bio_from->geom;
 213         sc = gp->softc;
 214         if (bp->bio_from != sc->path) {
 215                 g_io_request(bp, sc->path);
 216                 return;
 217         }
 218         mtx_lock(&sc->lock);
 219         sc->opath = sc->path;
 220         sc->path = NULL;
 221         error = g_post_event(g_fox_select_path, gp, M_NOWAIT, gp, NULL);
 222         if (error) {
 223                 bp->bio_error = ENOMEM;
 224                 g_std_done(bp);
 225         } else {
 226                 sc->waiting = 1;
 227                 TAILQ_INSERT_TAIL(&sc->queue, bp, bio_queue);
 228         }
 229         mtx_unlock(&sc->lock);
 230 }
 231
 232 static void
 233 g_fox_start(struct bio *bp)
 234 {
 235         struct g_geom *gp;
 236         struct bio *bp2;
 237         struct g_fox_softc *sc;
 238         int error;
 239
 240         gp = bp->bio_to->geom;
 241         sc = gp->softc;
 242         if (sc == NULL) {
 243                 g_io_deliver(bp, ENXIO);
 244                 return;
 245         }
 246         switch(bp->bio_cmd) {
 247         case BIO_READ:
 248         case BIO_WRITE:
 249         case BIO_DELETE:
 250                 bp2 = g_clone_bio(bp);
 251                 if (bp2 == NULL) {
 252                         g_io_deliver(bp, ENOMEM);
 253                         break;
 254                 }
 255                 bp2->bio_offset += sc->sectorsize;
 256                 bp2->bio_done = g_fox_done;
 257                 mtx_lock(&sc->lock);
 258                 if (sc->path == NULL || !TAILQ_EMPTY(&sc->queue)) {
 259                         if (sc->waiting == 0) {
 260                                 error = g_post_event(g_fox_select_path, gp,
 261                                     M_NOWAIT, gp, NULL);
 262                                 if (error) {
 263                                         g_destroy_bio(bp2);
 264                                         bp2 = NULL;
 265                                         g_io_deliver(bp, error);
 266                                 } else {
 267                                         sc->waiting = 1;
 268                                 }
 269                         }
 270                         if (bp2 != NULL)
 271                                 TAILQ_INSERT_TAIL(&sc->queue, bp2,
 272                                     bio_queue);
 273                 } else {
 274                         g_io_request(bp2, sc->path);
 275                 }
 276                 mtx_unlock(&sc->lock);
 277                 break;
 278         default:
 279                 g_io_deliver(bp, EOPNOTSUPP);
 280                 break;
 281         }
 282         return;
 283 }
 284
 285 static int
 286 g_fox_access(struct g_provider *pp, int dr, int dw, int de)
 287 {
 288         struct g_geom *gp;
 289         struct g_fox_softc *sc;
 290         struct g_consumer *cp1;
 291         int error;
 292
 293         g_topology_assert();
 294         gp = pp->geom;
 295         sc = gp->softc;
 296         if (sc == NULL) {
 297                 if (dr <= 0 && dw <= 0 && de <= 0)
 298                         return (0);
 299                 else
 300                         return (ENXIO);
 301         }
 302
 303         if (sc->cr == 0 && sc->cw == 0 && sc->ce == 0) {
 304                 /*
 305                  * First open, open all consumers with an exclusive bit
 306                  */
 307                 error = 0;
 308                 LIST_FOREACH(cp1, &gp->consumer, consumer) {
 309                         error = g_access(cp1, 0, 0, 1);
 310                         if (error) {
 311                                 printf("FOX: access(%s,0,0,1) = %d\n",
 312                                     cp1->provider->name, error);
 313                                 break;
 314                         }
 315                 }
 316                 if (error) {
 317                         LIST_FOREACH(cp1, &gp->consumer, consumer) {
 318                                 if (cp1->ace)
 319                                         g_access(cp1, 0, 0, -1);
 320                         }
 321                         return (error);
 322                 }
 323         }
 324         if (sc->path == NULL)
 325                 g_fox_select_path(gp, 0);
 326         if (sc->path == NULL)
 327                 error = ENXIO;
 328         else
 329                 error = g_access(sc->path, dr, dw, de);
 330         if (error == 0) {
 331                 sc->cr += dr;
 332                 sc->cw += dw;
 333                 sc->ce += de;
 334                 if (sc->cr == 0 && sc->cw == 0 && sc->ce == 0) {
 335                         /*
 336                          * Last close, remove e-bit on all consumers
 337                          */
 338                         LIST_FOREACH(cp1, &gp->consumer, consumer)
 339                                 g_access(cp1, 0, 0, -1);
 340                 }
 341         }
 342         return (error);
 343 }
 344
 345 static struct g_geom *
 346 g_fox_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
 347 {
 348         struct g_geom *gp, *gp2;
 349         struct g_provider *pp2;
 350         struct g_consumer *cp, *cp2;
 351         struct g_fox_softc *sc, *sc2;
 352         int error;
 353         u_int sectorsize;
 354         u_char *buf;
 355
 356         g_trace(G_T_TOPOLOGY, "fox_taste(%s, %s)", mp->name, pp->name);
 357         g_topology_assert();
 358         if (!strcmp(pp->geom->class->name, mp->name))
 359                 return (NULL);
 360         gp = g_new_geomf(mp, "%s.fox", pp->name);
 361         gp->softc = g_malloc(sizeof(struct g_fox_softc), M_WAITOK | M_ZERO);
 362         sc = gp->softc;
 363
 364         cp = g_new_consumer(gp);
 365         g_attach(cp, pp);
 366         error = g_access(cp, 1, 0, 0);
 367         if (error) {
 368                 g_free(sc);
 369                 g_detach(cp);
 370                 g_destroy_consumer(cp);
 371                 g_destroy_geom(gp);
 372                 return(NULL);
 373         }
 374         do {
 375                 sectorsize = cp->provider->sectorsize;
 376                 g_topology_unlock();
 377                 buf = g_read_data(cp, 0, sectorsize, NULL);
 378                 g_topology_lock();
 379                 if (buf == NULL)
 380                         break;
 381                 if (memcmp(buf, FOX_MAGIC, strlen(FOX_MAGIC)))
 382                         break;
 383
 384                 /*
 385                  * First we need to see if this a new path for an existing fox.
 386                  */
 387                 LIST_FOREACH(gp2, &mp->geom, geom) {
 388                         sc2 = gp2->softc;
 389                         if (sc2 == NULL)
 390                                 continue;
 391                         if (memcmp(buf + 16, sc2->magic, sizeof sc2->magic))
 392                                 continue;
 393                         break;
 394                 }
 395                 if (gp2 != NULL) {
 396                         /*
 397                          * It was.  Create a new consumer for that fox,
 398                          * attach it, and if the fox is open, open this
 399                          * path with an exclusive count of one.
 400                          */
 401                         printf("Adding path (%s) to fox (%s)\n",
 402                             pp->name, gp2->name);
 403                         cp2 = g_new_consumer(gp2);
 404                         g_attach(cp2, pp);
 405                         pp2 = LIST_FIRST(&gp2->provider);
 406                         if (pp2->acr > 0 || pp2->acw > 0 || pp2->ace > 0) {
 407                                 error = g_access(cp2, 0, 0, 1);
 408                                 if (error) {
 409                                         /*
 410                                          * This is bad, or more likely,
 411                                          * the user is doing something stupid
 412                                          */
 413                                         printf(
 414         "WARNING: New path (%s) to fox(%s) not added: %s\n%s",
 415                                             cp2->provider->name, gp2->name,
 416         "Could not get exclusive bit.",
 417         "WARNING: This indicates a risk of data inconsistency."
 418                                         );
 419                                         g_detach(cp2);
 420                                         g_destroy_consumer(cp2);
 421                                 }
 422                         }
 423                         break;
 424                 }
 425                 printf("Creating new fox (%s)\n", pp->name);
 426                 sc->path = cp;
 427                 memcpy(sc->magic, buf + 16, sizeof sc->magic);
 428                 pp2 = g_new_providerf(gp, "%s", gp->name);
 429                 pp2->mediasize = sc->mediasize = pp->mediasize - pp->sectorsize;
 430                 pp2->sectorsize = sc->sectorsize = pp->sectorsize;
 431 printf("fox %s lock %p\n", gp->name, &sc->lock);
 432
 433                 mtx_init(&sc->lock, "fox queue", NULL, MTX_DEF);
 434                 TAILQ_INIT(&sc->queue);
 435                 g_error_provider(pp2, 0);
 436         } while (0);
 437         if (buf != NULL)
 438                 g_free(buf);
 439         g_access(cp, -1, 0, 0);
 440
 441         if (!LIST_EMPTY(&gp->provider))
 442                 return (gp);
 443
 444         g_free(gp->softc);
 445         g_detach(cp);
 446         g_destroy_consumer(cp);
 447         g_destroy_geom(gp);
 448         return (NULL);
 449 }
 450
 451 static int
 452 g_fox_destroy_geom(struct gctl_req *req, struct g_class *mp, struct g_geom *gp)
 453 {
 454         struct g_fox_softc *sc;
 455
 456         g_topology_assert();
 457         sc = gp->softc;
 458         mtx_destroy(&sc->lock);
 459         g_free(gp->softc);
 460         gp->softc = NULL;
 461         g_wither_geom(gp, ENXIO);
 462         return (0);
 463 }
 464
 465 static struct g_class g_fox_class       = {
 466         .name = FOX_CLASS_NAME,
 467         .version = G_VERSION,
 468         .taste = g_fox_taste,
 469         .destroy_geom = g_fox_destroy_geom,
 470         .start = g_fox_start,
 471         .spoiled = g_fox_orphan,
 472         .orphan = g_fox_orphan,
 473         .access= g_fox_access,
 474 };
 475
 476 DECLARE_GEOM_CLASS(g_fox_class, g_fox);