FreeBSD/Linux Kernel Cross Reference
sys/geom/geom_fox.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 2003 Poul-Henning Kamp
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. The names of the authors may not be used to endorse or promote
16 * products derived from this software without specific prior written
17 * permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * $FreeBSD$
32 */
33
34 /* This is a GEOM module for handling path selection for multi-path
35 * storage devices. It is named "fox" because it, like they, prefer
36 * to have multiple exits to choose from.
37 *
38 */
39
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/sysctl.h>
43 #include <sys/kernel.h>
44 #include <sys/conf.h>
45 #include <sys/bio.h>
46 #include <sys/malloc.h>
47 #include <sys/lock.h>
48 #include <sys/mutex.h>
49 #include <sys/libkern.h>
50 #include <sys/endian.h>
51 #include <sys/md5.h>
52 #include <sys/errno.h>
53 #include <geom/geom.h>
54
55 #define FOX_CLASS_NAME "FOX"
56 #define FOX_MAGIC "GEOM::FOX"
57
58 static int g_fox_once;
59
60 FEATURE(geom_fox, "GEOM FOX redundant path mitigation support");
61
62 struct g_fox_softc {
63 off_t mediasize;
64 u_int sectorsize;
65 TAILQ_HEAD(, bio) queue;
66 struct mtx lock;
67 u_char magic[16];
68 struct g_consumer *path;
69 struct g_consumer *opath;
70 int waiting;
71 int cr, cw, ce;
72 };
73
74 /*
75 * This function is called whenever we need to select a new path.
76 */
77 static void
78 g_fox_select_path(void *arg, int flag)
79 {
80 struct g_geom *gp;
81 struct g_fox_softc *sc;
82 struct g_consumer *cp1;
83 struct bio *bp;
84 int error;
85
86 g_topology_assert();
87 if (flag == EV_CANCEL)
88 return;
89 gp = arg;
90 sc = gp->softc;
91
92 if (sc->opath != NULL) {
93 /*
94 * First, close the old path entirely.
95 */
96 printf("Closing old path (%s) on fox (%s)\n",
97 sc->opath->provider->name, gp->name);
98
99 cp1 = LIST_NEXT(sc->opath, consumer);
100
101 g_access(sc->opath, -sc->cr, -sc->cw, -(sc->ce + 1));
102
103 /*
104 * The attempt to reopen it with a exclusive count
105 */
106 error = g_access(sc->opath, 0, 0, 1);
107 if (error) {
108 /*
109 * Ok, ditch this consumer, we can't use it.
110 */
111 printf("Drop old path (%s) on fox (%s)\n",
112 sc->opath->provider->name, gp->name);
113 g_detach(sc->opath);
114 g_destroy_consumer(sc->opath);
115 if (LIST_EMPTY(&gp->consumer)) {
116 /* No consumers left */
117 g_wither_geom(gp, ENXIO);
118 for (;;) {
119 bp = TAILQ_FIRST(&sc->queue);
120 if (bp == NULL)
121 break;
122 TAILQ_REMOVE(&sc->queue, bp, bio_queue);
123 bp->bio_error = ENXIO;
124 g_std_done(bp);
125 }
126 return;
127 }
128 } else {
129 printf("Got e-bit on old path (%s) on fox (%s)\n",
130 sc->opath->provider->name, gp->name);
131 }
132 sc->opath = NULL;
133 } else {
134 cp1 = LIST_FIRST(&gp->consumer);
135 }
136 if (cp1 == NULL)
137 cp1 = LIST_FIRST(&gp->consumer);
138 printf("Open new path (%s) on fox (%s)\n",
139 cp1->provider->name, gp->name);
140 error = g_access(cp1, sc->cr, sc->cw, sc->ce);
141 if (error) {
142 /*
143 * If we failed, we take another trip through here
144 */
145 printf("Open new path (%s) on fox (%s) failed, reselect.\n",
146 cp1->provider->name, gp->name);
147 sc->opath = cp1;
148 g_post_event(g_fox_select_path, gp, M_WAITOK, gp, NULL);
149 } else {
150 printf("Open new path (%s) on fox (%s) succeeded\n",
151 cp1->provider->name, gp->name);
152 mtx_lock(&sc->lock);
153 sc->path = cp1;
154 sc->waiting = 0;
155 for (;;) {
156 bp = TAILQ_FIRST(&sc->queue);
157 if (bp == NULL)
158 break;
159 TAILQ_REMOVE(&sc->queue, bp, bio_queue);
160 g_io_request(bp, sc->path);
161 }
162 mtx_unlock(&sc->lock);
163 }
164 }
165
166 static void
167 g_fox_orphan(struct g_consumer *cp)
168 {
169 struct g_geom *gp;
170 struct g_fox_softc *sc;
171 int error, mark;
172
173 g_topology_assert();
174 gp = cp->geom;
175 sc = gp->softc;
176 printf("Removing path (%s) from fox (%s)\n",
177 cp->provider->name, gp->name);
178 mtx_lock(&sc->lock);
179 if (cp == sc->path) {
180 sc->opath = NULL;
181 sc->path = NULL;
182 sc->waiting = 1;
183 mark = 1;
184 } else {
185 mark = 0;
186 }
187 mtx_unlock(&sc->lock);
188
189 g_access(cp, -cp->acr, -cp->acw, -cp->ace);
190 error = cp->provider->error;
191 g_detach(cp);
192 g_destroy_consumer(cp);
193 if (!LIST_EMPTY(&gp->consumer)) {
194 if (mark)
195 g_post_event(g_fox_select_path, gp, M_WAITOK, gp, NULL);
196 return;
197 }
198
199 mtx_destroy(&sc->lock);
200 g_free(gp->softc);
201 gp->softc = NULL;
202 g_wither_geom(gp, ENXIO);
203 }
204
205 static void
206 g_fox_done(struct bio *bp)
207 {
208 struct g_geom *gp;
209 struct g_fox_softc *sc;
210 int error;
211
212 if (bp->bio_error == 0) {
213 g_std_done(bp);
214 return;
215 }
216 gp = bp->bio_from->geom;
217 sc = gp->softc;
218 if (bp->bio_from != sc->path) {
219 g_io_request(bp, sc->path);
220 return;
221 }
222 mtx_lock(&sc->lock);
223 sc->opath = sc->path;
224 sc->path = NULL;
225 error = g_post_event(g_fox_select_path, gp, M_NOWAIT, gp, NULL);
226 if (error) {
227 bp->bio_error = ENOMEM;
228 g_std_done(bp);
229 } else {
230 sc->waiting = 1;
231 TAILQ_INSERT_TAIL(&sc->queue, bp, bio_queue);
232 }
233 mtx_unlock(&sc->lock);
234 }
235
236 static void
237 g_fox_start(struct bio *bp)
238 {
239 struct g_geom *gp;
240 struct bio *bp2;
241 struct g_fox_softc *sc;
242 int error;
243
244 gp = bp->bio_to->geom;
245 sc = gp->softc;
246 if (sc == NULL) {
247 g_io_deliver(bp, ENXIO);
248 return;
249 }
250 switch(bp->bio_cmd) {
251 case BIO_READ:
252 case BIO_WRITE:
253 case BIO_DELETE:
254 bp2 = g_clone_bio(bp);
255 if (bp2 == NULL) {
256 g_io_deliver(bp, ENOMEM);
257 break;
258 }
259 bp2->bio_offset += sc->sectorsize;
260 bp2->bio_done = g_fox_done;
261 mtx_lock(&sc->lock);
262 if (sc->path == NULL || !TAILQ_EMPTY(&sc->queue)) {
263 if (sc->waiting == 0) {
264 error = g_post_event(g_fox_select_path, gp,
265 M_NOWAIT, gp, NULL);
266 if (error) {
267 g_destroy_bio(bp2);
268 bp2 = NULL;
269 g_io_deliver(bp, error);
270 } else {
271 sc->waiting = 1;
272 }
273 }
274 if (bp2 != NULL)
275 TAILQ_INSERT_TAIL(&sc->queue, bp2,
276 bio_queue);
277 } else {
278 g_io_request(bp2, sc->path);
279 }
280 mtx_unlock(&sc->lock);
281 break;
282 default:
283 g_io_deliver(bp, EOPNOTSUPP);
284 break;
285 }
286 return;
287 }
288
289 static int
290 g_fox_access(struct g_provider *pp, int dr, int dw, int de)
291 {
292 struct g_geom *gp;
293 struct g_fox_softc *sc;
294 struct g_consumer *cp1;
295 int error;
296
297 g_topology_assert();
298 gp = pp->geom;
299 sc = gp->softc;
300 if (sc == NULL) {
301 if (dr <= 0 && dw <= 0 && de <= 0)
302 return (0);
303 else
304 return (ENXIO);
305 }
306
307 if (sc->cr == 0 && sc->cw == 0 && sc->ce == 0) {
308 /*
309 * First open, open all consumers with an exclusive bit
310 */
311 error = 0;
312 LIST_FOREACH(cp1, &gp->consumer, consumer) {
313 error = g_access(cp1, 0, 0, 1);
314 if (error) {
315 printf("FOX: access(%s,0,0,1) = %d\n",
316 cp1->provider->name, error);
317 break;
318 }
319 }
320 if (error) {
321 LIST_FOREACH(cp1, &gp->consumer, consumer) {
322 if (cp1->ace)
323 g_access(cp1, 0, 0, -1);
324 }
325 return (error);
326 }
327 }
328 if (sc->path == NULL)
329 g_fox_select_path(gp, 0);
330 if (sc->path == NULL)
331 error = ENXIO;
332 else
333 error = g_access(sc->path, dr, dw, de);
334 if (error == 0) {
335 sc->cr += dr;
336 sc->cw += dw;
337 sc->ce += de;
338 if (sc->cr == 0 && sc->cw == 0 && sc->ce == 0) {
339 /*
340 * Last close, remove e-bit on all consumers
341 */
342 LIST_FOREACH(cp1, &gp->consumer, consumer)
343 g_access(cp1, 0, 0, -1);
344 }
345 }
346 return (error);
347 }
348
349 static struct g_geom *
350 g_fox_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
351 {
352 struct g_geom *gp, *gp2;
353 struct g_provider *pp2;
354 struct g_consumer *cp, *cp2;
355 struct g_fox_softc *sc, *sc2;
356 int error;
357 u_int sectorsize;
358 u_char *buf;
359
360 g_trace(G_T_TOPOLOGY, "fox_taste(%s, %s)", mp->name, pp->name);
361 g_topology_assert();
362 if (!strcmp(pp->geom->class->name, mp->name))
363 return (NULL);
364 gp = g_new_geomf(mp, "%s.fox", pp->name);
365 gp->softc = g_malloc(sizeof(struct g_fox_softc), M_WAITOK | M_ZERO);
366 sc = gp->softc;
367
368 cp = g_new_consumer(gp);
369 g_attach(cp, pp);
370 error = g_access(cp, 1, 0, 0);
371 if (error) {
372 g_free(sc);
373 g_detach(cp);
374 g_destroy_consumer(cp);
375 g_destroy_geom(gp);
376 return(NULL);
377 }
378 do {
379 sectorsize = cp->provider->sectorsize;
380 g_topology_unlock();
381 buf = g_read_data(cp, 0, sectorsize, NULL);
382 g_topology_lock();
383 if (buf == NULL)
384 break;
385 if (memcmp(buf, FOX_MAGIC, strlen(FOX_MAGIC)))
386 break;
387
388 /*
389 * First we need to see if this a new path for an existing fox.
390 */
391 LIST_FOREACH(gp2, &mp->geom, geom) {
392 sc2 = gp2->softc;
393 if (sc2 == NULL)
394 continue;
395 if (memcmp(buf + 16, sc2->magic, sizeof sc2->magic))
396 continue;
397 break;
398 }
399 if (gp2 != NULL) {
400 /*
401 * It was. Create a new consumer for that fox,
402 * attach it, and if the fox is open, open this
403 * path with an exclusive count of one.
404 */
405 printf("Adding path (%s) to fox (%s)\n",
406 pp->name, gp2->name);
407 cp2 = g_new_consumer(gp2);
408 g_attach(cp2, pp);
409 pp2 = LIST_FIRST(&gp2->provider);
410 if (pp2->acr > 0 || pp2->acw > 0 || pp2->ace > 0) {
411 error = g_access(cp2, 0, 0, 1);
412 if (error) {
413 /*
414 * This is bad, or more likely,
415 * the user is doing something stupid
416 */
417 printf(
418 "WARNING: New path (%s) to fox(%s) not added: %s\n%s",
419 cp2->provider->name, gp2->name,
420 "Could not get exclusive bit.",
421 "WARNING: This indicates a risk of data inconsistency."
422 );
423 g_detach(cp2);
424 g_destroy_consumer(cp2);
425 }
426 }
427 break;
428 }
429 printf("Creating new fox (%s)\n", pp->name);
430 sc->path = cp;
431 memcpy(sc->magic, buf + 16, sizeof sc->magic);
432 pp2 = g_new_providerf(gp, "%s", gp->name);
433 pp2->mediasize = sc->mediasize = pp->mediasize - pp->sectorsize;
434 pp2->sectorsize = sc->sectorsize = pp->sectorsize;
435 printf("fox %s lock %p\n", gp->name, &sc->lock);
436
437 mtx_init(&sc->lock, "fox queue", NULL, MTX_DEF);
438 TAILQ_INIT(&sc->queue);
439 g_error_provider(pp2, 0);
440 } while (0);
441 if (buf != NULL)
442 g_free(buf);
443 g_access(cp, -1, 0, 0);
444
445 if (!LIST_EMPTY(&gp->provider)) {
446 if (!g_fox_once) {
447 g_fox_once = 1;
448 printf(
449 "WARNING: geom_fox (geom %s) is deprecated, "
450 "use gmultipath instead.\n", gp->name);
451 }
452 return (gp);
453 }
454
455 g_free(gp->softc);
456 g_detach(cp);
457 g_destroy_consumer(cp);
458 g_destroy_geom(gp);
459 return (NULL);
460 }
461
462 static int
463 g_fox_destroy_geom(struct gctl_req *req, struct g_class *mp, struct g_geom *gp)
464 {
465 struct g_fox_softc *sc;
466
467 g_topology_assert();
468 sc = gp->softc;
469 mtx_destroy(&sc->lock);
470 g_free(gp->softc);
471 gp->softc = NULL;
472 g_wither_geom(gp, ENXIO);
473 return (0);
474 }
475
476 static struct g_class g_fox_class = {
477 .name = FOX_CLASS_NAME,
478 .version = G_VERSION,
479 .taste = g_fox_taste,
480 .destroy_geom = g_fox_destroy_geom,
481 .start = g_fox_start,
482 .spoiled = g_fox_orphan,
483 .orphan = g_fox_orphan,
484 .access= g_fox_access,
485 };
486
487 DECLARE_GEOM_CLASS(g_fox_class, g_fox);
488 MODULE_VERSION(geom_fox, 0);
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