FreeBSD/Linux Kernel Cross Reference
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: releng/8.3/sys/geom/geom_fox.c 199583 2009-11-20 15:27:52Z jhb $
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/kernel.h>
41 #include <sys/conf.h>
42 #include <sys/bio.h>
43 #include <sys/malloc.h>
44 #include <sys/lock.h>
45 #include <sys/mutex.h>
46 #include <sys/libkern.h>
47 #include <sys/endian.h>
48 #include <sys/md5.h>
49 #include <sys/errno.h>
50 #include <geom/geom.h>
51
52 #define FOX_CLASS_NAME "FOX"
53 #define FOX_MAGIC "GEOM::FOX"
54
55 struct g_fox_softc {
56 off_t mediasize;
57 u_int sectorsize;
58 TAILQ_HEAD(, bio) queue;
59 struct mtx lock;
60 u_char magic[16];
61 struct g_consumer *path;
62 struct g_consumer *opath;
63 int waiting;
64 int cr, cw, ce;
65 };
66
67 /*
68 * This function is called whenever we need to select a new path.
69 */
70 static void
71 g_fox_select_path(void *arg, int flag)
72 {
73 struct g_geom *gp;
74 struct g_fox_softc *sc;
75 struct g_consumer *cp1;
76 struct bio *bp;
77 int error;
78
79 g_topology_assert();
80 if (flag == EV_CANCEL)
81 return;
82 gp = arg;
83 sc = gp->softc;
84
85 if (sc->opath != NULL) {
86 /*
87 * First, close the old path entirely.
88 */
89 printf("Closing old path (%s) on fox (%s)\n",
90 sc->opath->provider->name, gp->name);
91
92 cp1 = LIST_NEXT(sc->opath, consumer);
93
94 g_access(sc->opath, -sc->cr, -sc->cw, -(sc->ce + 1));
95
96 /*
97 * The attempt to reopen it with a exclusive count
98 */
99 error = g_access(sc->opath, 0, 0, 1);
100 if (error) {
101 /*
102 * Ok, ditch this consumer, we can't use it.
103 */
104 printf("Drop old path (%s) on fox (%s)\n",
105 sc->opath->provider->name, gp->name);
106 g_detach(sc->opath);
107 g_destroy_consumer(sc->opath);
108 if (LIST_EMPTY(&gp->consumer)) {
109 /* No consumers left */
110 g_wither_geom(gp, ENXIO);
111 for (;;) {
112 bp = TAILQ_FIRST(&sc->queue);
113 if (bp == NULL)
114 break;
115 TAILQ_REMOVE(&sc->queue, bp, bio_queue);
116 bp->bio_error = ENXIO;
117 g_std_done(bp);
118 }
119 return;
120 }
121 } else {
122 printf("Got e-bit on old path (%s) on fox (%s)\n",
123 sc->opath->provider->name, gp->name);
124 }
125 sc->opath = NULL;
126 } else {
127 cp1 = LIST_FIRST(&gp->consumer);
128 }
129 if (cp1 == NULL)
130 cp1 = LIST_FIRST(&gp->consumer);
131 printf("Open new path (%s) on fox (%s)\n",
132 cp1->provider->name, gp->name);
133 error = g_access(cp1, sc->cr, sc->cw, sc->ce);
134 if (error) {
135 /*
136 * If we failed, we take another trip through here
137 */
138 printf("Open new path (%s) on fox (%s) failed, reselect.\n",
139 cp1->provider->name, gp->name);
140 sc->opath = cp1;
141 g_post_event(g_fox_select_path, gp, M_WAITOK, gp, NULL);
142 } else {
143 printf("Open new path (%s) on fox (%s) succeeded\n",
144 cp1->provider->name, gp->name);
145 mtx_lock(&sc->lock);
146 sc->path = cp1;
147 sc->waiting = 0;
148 for (;;) {
149 bp = TAILQ_FIRST(&sc->queue);
150 if (bp == NULL)
151 break;
152 TAILQ_REMOVE(&sc->queue, bp, bio_queue);
153 g_io_request(bp, sc->path);
154 }
155 mtx_unlock(&sc->lock);
156 }
157 }
158
159 static void
160 g_fox_orphan(struct g_consumer *cp)
161 {
162 struct g_geom *gp;
163 struct g_fox_softc *sc;
164 int error, mark;
165
166 g_topology_assert();
167 gp = cp->geom;
168 sc = gp->softc;
169 printf("Removing path (%s) from fox (%s)\n",
170 cp->provider->name, gp->name);
171 mtx_lock(&sc->lock);
172 if (cp == sc->path) {
173 sc->opath = NULL;
174 sc->path = NULL;
175 sc->waiting = 1;
176 mark = 1;
177 } else {
178 mark = 0;
179 }
180 mtx_unlock(&sc->lock);
181
182 g_access(cp, -cp->acr, -cp->acw, -cp->ace);
183 error = cp->provider->error;
184 g_detach(cp);
185 g_destroy_consumer(cp);
186 if (!LIST_EMPTY(&gp->consumer)) {
187 if (mark)
188 g_post_event(g_fox_select_path, gp, M_WAITOK, gp, NULL);
189 return;
190 }
191
192 mtx_destroy(&sc->lock);
193 g_free(gp->softc);
194 gp->softc = NULL;
195 g_wither_geom(gp, ENXIO);
196 }
197
198 static void
199 g_fox_done(struct bio *bp)
200 {
201 struct g_geom *gp;
202 struct g_fox_softc *sc;
203 int error;
204
205 if (bp->bio_error == 0) {
206 g_std_done(bp);
207 return;
208 }
209 gp = bp->bio_from->geom;
210 sc = gp->softc;
211 if (bp->bio_from != sc->path) {
212 g_io_request(bp, sc->path);
213 return;
214 }
215 mtx_lock(&sc->lock);
216 sc->opath = sc->path;
217 sc->path = NULL;
218 error = g_post_event(g_fox_select_path, gp, M_NOWAIT, gp, NULL);
219 if (error) {
220 bp->bio_error = ENOMEM;
221 g_std_done(bp);
222 } else {
223 sc->waiting = 1;
224 TAILQ_INSERT_TAIL(&sc->queue, bp, bio_queue);
225 }
226 mtx_unlock(&sc->lock);
227 }
228
229 static void
230 g_fox_start(struct bio *bp)
231 {
232 struct g_geom *gp;
233 struct bio *bp2;
234 struct g_fox_softc *sc;
235 int error;
236
237 gp = bp->bio_to->geom;
238 sc = gp->softc;
239 if (sc == NULL) {
240 g_io_deliver(bp, ENXIO);
241 return;
242 }
243 switch(bp->bio_cmd) {
244 case BIO_READ:
245 case BIO_WRITE:
246 case BIO_DELETE:
247 bp2 = g_clone_bio(bp);
248 if (bp2 == NULL) {
249 g_io_deliver(bp, ENOMEM);
250 break;
251 }
252 bp2->bio_offset += sc->sectorsize;
253 bp2->bio_done = g_fox_done;
254 mtx_lock(&sc->lock);
255 if (sc->path == NULL || !TAILQ_EMPTY(&sc->queue)) {
256 if (sc->waiting == 0) {
257 error = g_post_event(g_fox_select_path, gp,
258 M_NOWAIT, gp, NULL);
259 if (error) {
260 g_destroy_bio(bp2);
261 bp2 = NULL;
262 g_io_deliver(bp, error);
263 } else {
264 sc->waiting = 1;
265 }
266 }
267 if (bp2 != NULL)
268 TAILQ_INSERT_TAIL(&sc->queue, bp2,
269 bio_queue);
270 } else {
271 g_io_request(bp2, sc->path);
272 }
273 mtx_unlock(&sc->lock);
274 break;
275 default:
276 g_io_deliver(bp, EOPNOTSUPP);
277 break;
278 }
279 return;
280 }
281
282 static int
283 g_fox_access(struct g_provider *pp, int dr, int dw, int de)
284 {
285 struct g_geom *gp;
286 struct g_fox_softc *sc;
287 struct g_consumer *cp1;
288 int error;
289
290 g_topology_assert();
291 gp = pp->geom;
292 sc = gp->softc;
293 if (sc == NULL) {
294 if (dr <= 0 && dw <= 0 && de <= 0)
295 return (0);
296 else
297 return (ENXIO);
298 }
299
300 if (sc->cr == 0 && sc->cw == 0 && sc->ce == 0) {
301 /*
302 * First open, open all consumers with an exclusive bit
303 */
304 error = 0;
305 LIST_FOREACH(cp1, &gp->consumer, consumer) {
306 error = g_access(cp1, 0, 0, 1);
307 if (error) {
308 printf("FOX: access(%s,0,0,1) = %d\n",
309 cp1->provider->name, error);
310 break;
311 }
312 }
313 if (error) {
314 LIST_FOREACH(cp1, &gp->consumer, consumer) {
315 if (cp1->ace)
316 g_access(cp1, 0, 0, -1);
317 }
318 return (error);
319 }
320 }
321 if (sc->path == NULL)
322 g_fox_select_path(gp, 0);
323 if (sc->path == NULL)
324 error = ENXIO;
325 else
326 error = g_access(sc->path, dr, dw, de);
327 if (error == 0) {
328 sc->cr += dr;
329 sc->cw += dw;
330 sc->ce += de;
331 if (sc->cr == 0 && sc->cw == 0 && sc->ce == 0) {
332 /*
333 * Last close, remove e-bit on all consumers
334 */
335 LIST_FOREACH(cp1, &gp->consumer, consumer)
336 g_access(cp1, 0, 0, -1);
337 }
338 }
339 return (error);
340 }
341
342 static struct g_geom *
343 g_fox_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
344 {
345 struct g_geom *gp, *gp2;
346 struct g_provider *pp2;
347 struct g_consumer *cp, *cp2;
348 struct g_fox_softc *sc, *sc2;
349 int error;
350 u_int sectorsize;
351 u_char *buf;
352
353 g_trace(G_T_TOPOLOGY, "fox_taste(%s, %s)", mp->name, pp->name);
354 g_topology_assert();
355 if (!strcmp(pp->geom->class->name, mp->name))
356 return (NULL);
357 gp = g_new_geomf(mp, "%s.fox", pp->name);
358 gp->softc = g_malloc(sizeof(struct g_fox_softc), M_WAITOK | M_ZERO);
359 sc = gp->softc;
360
361 cp = g_new_consumer(gp);
362 g_attach(cp, pp);
363 error = g_access(cp, 1, 0, 0);
364 if (error) {
365 g_free(sc);
366 g_detach(cp);
367 g_destroy_consumer(cp);
368 g_destroy_geom(gp);
369 return(NULL);
370 }
371 do {
372 sectorsize = cp->provider->sectorsize;
373 g_topology_unlock();
374 buf = g_read_data(cp, 0, sectorsize, NULL);
375 g_topology_lock();
376 if (buf == NULL)
377 break;
378 if (memcmp(buf, FOX_MAGIC, strlen(FOX_MAGIC)))
379 break;
380
381 /*
382 * First we need to see if this a new path for an existing fox.
383 */
384 LIST_FOREACH(gp2, &mp->geom, geom) {
385 sc2 = gp2->softc;
386 if (sc2 == NULL)
387 continue;
388 if (memcmp(buf + 16, sc2->magic, sizeof sc2->magic))
389 continue;
390 break;
391 }
392 if (gp2 != NULL) {
393 /*
394 * It was. Create a new consumer for that fox,
395 * attach it, and if the fox is open, open this
396 * path with an exclusive count of one.
397 */
398 printf("Adding path (%s) to fox (%s)\n",
399 pp->name, gp2->name);
400 cp2 = g_new_consumer(gp2);
401 g_attach(cp2, pp);
402 pp2 = LIST_FIRST(&gp2->provider);
403 if (pp2->acr > 0 || pp2->acw > 0 || pp2->ace > 0) {
404 error = g_access(cp2, 0, 0, 1);
405 if (error) {
406 /*
407 * This is bad, or more likely,
408 * the user is doing something stupid
409 */
410 printf(
411 "WARNING: New path (%s) to fox(%s) not added: %s\n%s",
412 cp2->provider->name, gp2->name,
413 "Could not get exclusive bit.",
414 "WARNING: This indicates a risk of data inconsistency."
415 );
416 g_detach(cp2);
417 g_destroy_consumer(cp2);
418 }
419 }
420 break;
421 }
422 printf("Creating new fox (%s)\n", pp->name);
423 sc->path = cp;
424 memcpy(sc->magic, buf + 16, sizeof sc->magic);
425 pp2 = g_new_providerf(gp, "%s", gp->name);
426 pp2->mediasize = sc->mediasize = pp->mediasize - pp->sectorsize;
427 pp2->sectorsize = sc->sectorsize = pp->sectorsize;
428 printf("fox %s lock %p\n", gp->name, &sc->lock);
429
430 mtx_init(&sc->lock, "fox queue", NULL, MTX_DEF);
431 TAILQ_INIT(&sc->queue);
432 g_error_provider(pp2, 0);
433 } while (0);
434 if (buf != NULL)
435 g_free(buf);
436 g_access(cp, -1, 0, 0);
437
438 if (!LIST_EMPTY(&gp->provider))
439 return (gp);
440
441 g_free(gp->softc);
442 g_detach(cp);
443 g_destroy_consumer(cp);
444 g_destroy_geom(gp);
445 return (NULL);
446 }
447
448 static int
449 g_fox_destroy_geom(struct gctl_req *req, struct g_class *mp, struct g_geom *gp)
450 {
451 struct g_fox_softc *sc;
452
453 g_topology_assert();
454 sc = gp->softc;
455 mtx_destroy(&sc->lock);
456 g_free(gp->softc);
457 gp->softc = NULL;
458 g_wither_geom(gp, ENXIO);
459 return (0);
460 }
461
462 static struct g_class g_fox_class = {
463 .name = FOX_CLASS_NAME,
464 .version = G_VERSION,
465 .taste = g_fox_taste,
466 .destroy_geom = g_fox_destroy_geom,
467 .start = g_fox_start,
468 .spoiled = g_fox_orphan,
469 .orphan = g_fox_orphan,
470 .access= g_fox_access,
471 };
472
473 DECLARE_GEOM_CLASS(g_fox_class, g_fox);
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