Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/geom/geom_fox.c
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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: releng/11.2/sys/geom/geom_fox.c 332640 2018-04-17 02:18:04Z kevans $ 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 static int g_fox_once; 57 58 FEATURE(geom_fox, "GEOM FOX redundant path mitigation support"); 59 60 struct g_fox_softc { 61 off_t mediasize; 62 u_int sectorsize; 63 TAILQ_HEAD(, bio) queue; 64 struct mtx lock; 65 u_char magic[16]; 66 struct g_consumer *path; 67 struct g_consumer *opath; 68 int waiting; 69 int cr, cw, ce; 70 }; 71 72 /* 73 * This function is called whenever we need to select a new path. 74 */ 75 static void 76 g_fox_select_path(void *arg, int flag) 77 { 78 struct g_geom *gp; 79 struct g_fox_softc *sc; 80 struct g_consumer *cp1; 81 struct bio *bp; 82 int error; 83 84 g_topology_assert(); 85 if (flag == EV_CANCEL) 86 return; 87 gp = arg; 88 sc = gp->softc; 89 90 if (sc->opath != NULL) { 91 /* 92 * First, close the old path entirely. 93 */ 94 printf("Closing old path (%s) on fox (%s)\n", 95 sc->opath->provider->name, gp->name); 96 97 cp1 = LIST_NEXT(sc->opath, consumer); 98 99 g_access(sc->opath, -sc->cr, -sc->cw, -(sc->ce + 1)); 100 101 /* 102 * The attempt to reopen it with a exclusive count 103 */ 104 error = g_access(sc->opath, 0, 0, 1); 105 if (error) { 106 /* 107 * Ok, ditch this consumer, we can't use it. 108 */ 109 printf("Drop old path (%s) on fox (%s)\n", 110 sc->opath->provider->name, gp->name); 111 g_detach(sc->opath); 112 g_destroy_consumer(sc->opath); 113 if (LIST_EMPTY(&gp->consumer)) { 114 /* No consumers left */ 115 g_wither_geom(gp, ENXIO); 116 for (;;) { 117 bp = TAILQ_FIRST(&sc->queue); 118 if (bp == NULL) 119 break; 120 TAILQ_REMOVE(&sc->queue, bp, bio_queue); 121 bp->bio_error = ENXIO; 122 g_std_done(bp); 123 } 124 return; 125 } 126 } else { 127 printf("Got e-bit on old path (%s) on fox (%s)\n", 128 sc->opath->provider->name, gp->name); 129 } 130 sc->opath = NULL; 131 } else { 132 cp1 = LIST_FIRST(&gp->consumer); 133 } 134 if (cp1 == NULL) 135 cp1 = LIST_FIRST(&gp->consumer); 136 printf("Open new path (%s) on fox (%s)\n", 137 cp1->provider->name, gp->name); 138 error = g_access(cp1, sc->cr, sc->cw, sc->ce); 139 if (error) { 140 /* 141 * If we failed, we take another trip through here 142 */ 143 printf("Open new path (%s) on fox (%s) failed, reselect.\n", 144 cp1->provider->name, gp->name); 145 sc->opath = cp1; 146 g_post_event(g_fox_select_path, gp, M_WAITOK, gp, NULL); 147 } else { 148 printf("Open new path (%s) on fox (%s) succeeded\n", 149 cp1->provider->name, gp->name); 150 mtx_lock(&sc->lock); 151 sc->path = cp1; 152 sc->waiting = 0; 153 for (;;) { 154 bp = TAILQ_FIRST(&sc->queue); 155 if (bp == NULL) 156 break; 157 TAILQ_REMOVE(&sc->queue, bp, bio_queue); 158 g_io_request(bp, sc->path); 159 } 160 mtx_unlock(&sc->lock); 161 } 162 } 163 164 static void 165 g_fox_orphan(struct g_consumer *cp) 166 { 167 struct g_geom *gp; 168 struct g_fox_softc *sc; 169 int error, mark; 170 171 g_topology_assert(); 172 gp = cp->geom; 173 sc = gp->softc; 174 printf("Removing path (%s) from fox (%s)\n", 175 cp->provider->name, gp->name); 176 mtx_lock(&sc->lock); 177 if (cp == sc->path) { 178 sc->opath = NULL; 179 sc->path = NULL; 180 sc->waiting = 1; 181 mark = 1; 182 } else { 183 mark = 0; 184 } 185 mtx_unlock(&sc->lock); 186 187 g_access(cp, -cp->acr, -cp->acw, -cp->ace); 188 error = cp->provider->error; 189 g_detach(cp); 190 g_destroy_consumer(cp); 191 if (!LIST_EMPTY(&gp->consumer)) { 192 if (mark) 193 g_post_event(g_fox_select_path, gp, M_WAITOK, gp, NULL); 194 return; 195 } 196 197 mtx_destroy(&sc->lock); 198 g_free(gp->softc); 199 gp->softc = NULL; 200 g_wither_geom(gp, ENXIO); 201 } 202 203 static void 204 g_fox_done(struct bio *bp) 205 { 206 struct g_geom *gp; 207 struct g_fox_softc *sc; 208 int error; 209 210 if (bp->bio_error == 0) { 211 g_std_done(bp); 212 return; 213 } 214 gp = bp->bio_from->geom; 215 sc = gp->softc; 216 if (bp->bio_from != sc->path) { 217 g_io_request(bp, sc->path); 218 return; 219 } 220 mtx_lock(&sc->lock); 221 sc->opath = sc->path; 222 sc->path = NULL; 223 error = g_post_event(g_fox_select_path, gp, M_NOWAIT, gp, NULL); 224 if (error) { 225 bp->bio_error = ENOMEM; 226 g_std_done(bp); 227 } else { 228 sc->waiting = 1; 229 TAILQ_INSERT_TAIL(&sc->queue, bp, bio_queue); 230 } 231 mtx_unlock(&sc->lock); 232 } 233 234 static void 235 g_fox_start(struct bio *bp) 236 { 237 struct g_geom *gp; 238 struct bio *bp2; 239 struct g_fox_softc *sc; 240 int error; 241 242 gp = bp->bio_to->geom; 243 sc = gp->softc; 244 if (sc == NULL) { 245 g_io_deliver(bp, ENXIO); 246 return; 247 } 248 switch(bp->bio_cmd) { 249 case BIO_READ: 250 case BIO_WRITE: 251 case BIO_DELETE: 252 bp2 = g_clone_bio(bp); 253 if (bp2 == NULL) { 254 g_io_deliver(bp, ENOMEM); 255 break; 256 } 257 bp2->bio_offset += sc->sectorsize; 258 bp2->bio_done = g_fox_done; 259 mtx_lock(&sc->lock); 260 if (sc->path == NULL || !TAILQ_EMPTY(&sc->queue)) { 261 if (sc->waiting == 0) { 262 error = g_post_event(g_fox_select_path, gp, 263 M_NOWAIT, gp, NULL); 264 if (error) { 265 g_destroy_bio(bp2); 266 bp2 = NULL; 267 g_io_deliver(bp, error); 268 } else { 269 sc->waiting = 1; 270 } 271 } 272 if (bp2 != NULL) 273 TAILQ_INSERT_TAIL(&sc->queue, bp2, 274 bio_queue); 275 } else { 276 g_io_request(bp2, sc->path); 277 } 278 mtx_unlock(&sc->lock); 279 break; 280 default: 281 g_io_deliver(bp, EOPNOTSUPP); 282 break; 283 } 284 return; 285 } 286 287 static int 288 g_fox_access(struct g_provider *pp, int dr, int dw, int de) 289 { 290 struct g_geom *gp; 291 struct g_fox_softc *sc; 292 struct g_consumer *cp1; 293 int error; 294 295 g_topology_assert(); 296 gp = pp->geom; 297 sc = gp->softc; 298 if (sc == NULL) { 299 if (dr <= 0 && dw <= 0 && de <= 0) 300 return (0); 301 else 302 return (ENXIO); 303 } 304 305 if (sc->cr == 0 && sc->cw == 0 && sc->ce == 0) { 306 /* 307 * First open, open all consumers with an exclusive bit 308 */ 309 error = 0; 310 LIST_FOREACH(cp1, &gp->consumer, consumer) { 311 error = g_access(cp1, 0, 0, 1); 312 if (error) { 313 printf("FOX: access(%s,0,0,1) = %d\n", 314 cp1->provider->name, error); 315 break; 316 } 317 } 318 if (error) { 319 LIST_FOREACH(cp1, &gp->consumer, consumer) { 320 if (cp1->ace) 321 g_access(cp1, 0, 0, -1); 322 } 323 return (error); 324 } 325 } 326 if (sc->path == NULL) 327 g_fox_select_path(gp, 0); 328 if (sc->path == NULL) 329 error = ENXIO; 330 else 331 error = g_access(sc->path, dr, dw, de); 332 if (error == 0) { 333 sc->cr += dr; 334 sc->cw += dw; 335 sc->ce += de; 336 if (sc->cr == 0 && sc->cw == 0 && sc->ce == 0) { 337 /* 338 * Last close, remove e-bit on all consumers 339 */ 340 LIST_FOREACH(cp1, &gp->consumer, consumer) 341 g_access(cp1, 0, 0, -1); 342 } 343 } 344 return (error); 345 } 346 347 static struct g_geom * 348 g_fox_taste(struct g_class *mp, struct g_provider *pp, int flags __unused) 349 { 350 struct g_geom *gp, *gp2; 351 struct g_provider *pp2; 352 struct g_consumer *cp, *cp2; 353 struct g_fox_softc *sc, *sc2; 354 int error; 355 u_int sectorsize; 356 u_char *buf; 357 358 g_trace(G_T_TOPOLOGY, "fox_taste(%s, %s)", mp->name, pp->name); 359 g_topology_assert(); 360 if (!strcmp(pp->geom->class->name, mp->name)) 361 return (NULL); 362 gp = g_new_geomf(mp, "%s.fox", pp->name); 363 gp->softc = g_malloc(sizeof(struct g_fox_softc), M_WAITOK | M_ZERO); 364 sc = gp->softc; 365 366 cp = g_new_consumer(gp); 367 g_attach(cp, pp); 368 error = g_access(cp, 1, 0, 0); 369 if (error) { 370 g_free(sc); 371 g_detach(cp); 372 g_destroy_consumer(cp); 373 g_destroy_geom(gp); 374 return(NULL); 375 } 376 do { 377 sectorsize = cp->provider->sectorsize; 378 g_topology_unlock(); 379 buf = g_read_data(cp, 0, sectorsize, NULL); 380 g_topology_lock(); 381 if (buf == NULL) 382 break; 383 if (memcmp(buf, FOX_MAGIC, strlen(FOX_MAGIC))) 384 break; 385 386 /* 387 * First we need to see if this a new path for an existing fox. 388 */ 389 LIST_FOREACH(gp2, &mp->geom, geom) { 390 sc2 = gp2->softc; 391 if (sc2 == NULL) 392 continue; 393 if (memcmp(buf + 16, sc2->magic, sizeof sc2->magic)) 394 continue; 395 break; 396 } 397 if (gp2 != NULL) { 398 /* 399 * It was. Create a new consumer for that fox, 400 * attach it, and if the fox is open, open this 401 * path with an exclusive count of one. 402 */ 403 printf("Adding path (%s) to fox (%s)\n", 404 pp->name, gp2->name); 405 cp2 = g_new_consumer(gp2); 406 g_attach(cp2, pp); 407 pp2 = LIST_FIRST(&gp2->provider); 408 if (pp2->acr > 0 || pp2->acw > 0 || pp2->ace > 0) { 409 error = g_access(cp2, 0, 0, 1); 410 if (error) { 411 /* 412 * This is bad, or more likely, 413 * the user is doing something stupid 414 */ 415 printf( 416 "WARNING: New path (%s) to fox(%s) not added: %s\n%s", 417 cp2->provider->name, gp2->name, 418 "Could not get exclusive bit.", 419 "WARNING: This indicates a risk of data inconsistency." 420 ); 421 g_detach(cp2); 422 g_destroy_consumer(cp2); 423 } 424 } 425 break; 426 } 427 printf("Creating new fox (%s)\n", pp->name); 428 sc->path = cp; 429 memcpy(sc->magic, buf + 16, sizeof sc->magic); 430 pp2 = g_new_providerf(gp, "%s", gp->name); 431 pp2->mediasize = sc->mediasize = pp->mediasize - pp->sectorsize; 432 pp2->sectorsize = sc->sectorsize = pp->sectorsize; 433 printf("fox %s lock %p\n", gp->name, &sc->lock); 434 435 mtx_init(&sc->lock, "fox queue", NULL, MTX_DEF); 436 TAILQ_INIT(&sc->queue); 437 g_error_provider(pp2, 0); 438 } while (0); 439 if (buf != NULL) 440 g_free(buf); 441 g_access(cp, -1, 0, 0); 442 443 if (!LIST_EMPTY(&gp->provider)) { 444 if (!g_fox_once) { 445 g_fox_once = 1; 446 printf( 447 "WARNING: geom_fox (geom %s) is deprecated, " 448 "use gmultipath instead.\n", gp->name); 449 } 450 return (gp); 451 } 452 453 g_free(gp->softc); 454 g_detach(cp); 455 g_destroy_consumer(cp); 456 g_destroy_geom(gp); 457 return (NULL); 458 } 459 460 static int 461 g_fox_destroy_geom(struct gctl_req *req, struct g_class *mp, struct g_geom *gp) 462 { 463 struct g_fox_softc *sc; 464 465 g_topology_assert(); 466 sc = gp->softc; 467 mtx_destroy(&sc->lock); 468 g_free(gp->softc); 469 gp->softc = NULL; 470 g_wither_geom(gp, ENXIO); 471 return (0); 472 } 473 474 static struct g_class g_fox_class = { 475 .name = FOX_CLASS_NAME, 476 .version = G_VERSION, 477 .taste = g_fox_taste, 478 .destroy_geom = g_fox_destroy_geom, 479 .start = g_fox_start, 480 .spoiled = g_fox_orphan, 481 .orphan = g_fox_orphan, 482 .access= g_fox_access, 483 }; 484 485 DECLARE_GEOM_CLASS(g_fox_class, g_fox); 486 MODULE_VERSION(geom_fox, 0);
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