xref: /freebsd/sbin/hastd/primary.c (revision aa64588d28258aef88cc33b8043112e8856948d0)
1 /*-
2  * Copyright (c) 2009 The FreeBSD Foundation
3  * All rights reserved.
4  *
5  * This software was developed by Pawel Jakub Dawidek under sponsorship from
6  * the FreeBSD Foundation.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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 
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32 
33 #include <sys/types.h>
34 #include <sys/time.h>
35 #include <sys/bio.h>
36 #include <sys/disk.h>
37 #include <sys/refcount.h>
38 #include <sys/stat.h>
39 
40 #include <geom/gate/g_gate.h>
41 
42 #include <assert.h>
43 #include <err.h>
44 #include <errno.h>
45 #include <fcntl.h>
46 #include <libgeom.h>
47 #include <pthread.h>
48 #include <stdint.h>
49 #include <stdio.h>
50 #include <string.h>
51 #include <sysexits.h>
52 #include <unistd.h>
53 
54 #include <activemap.h>
55 #include <nv.h>
56 #include <rangelock.h>
57 
58 #include "control.h"
59 #include "hast.h"
60 #include "hast_proto.h"
61 #include "hastd.h"
62 #include "metadata.h"
63 #include "proto.h"
64 #include "pjdlog.h"
65 #include "subr.h"
66 #include "synch.h"
67 
68 struct hio {
69 	/*
70 	 * Number of components we are still waiting for.
71 	 * When this field goes to 0, we can send the request back to the
72 	 * kernel. Each component has to decrease this counter by one
73 	 * even on failure.
74 	 */
75 	unsigned int		 hio_countdown;
76 	/*
77 	 * Each component has a place to store its own error.
78 	 * Once the request is handled by all components we can decide if the
79 	 * request overall is successful or not.
80 	 */
81 	int			*hio_errors;
82 	/*
83 	 * Structure used to comunicate with GEOM Gate class.
84 	 */
85 	struct g_gate_ctl_io	 hio_ggio;
86 	TAILQ_ENTRY(hio)	*hio_next;
87 };
88 #define	hio_free_next	hio_next[0]
89 #define	hio_done_next	hio_next[0]
90 
91 /*
92  * Free list holds unused structures. When free list is empty, we have to wait
93  * until some in-progress requests are freed.
94  */
95 static TAILQ_HEAD(, hio) hio_free_list;
96 static pthread_mutex_t hio_free_list_lock;
97 static pthread_cond_t hio_free_list_cond;
98 /*
99  * There is one send list for every component. One requests is placed on all
100  * send lists - each component gets the same request, but each component is
101  * responsible for managing his own send list.
102  */
103 static TAILQ_HEAD(, hio) *hio_send_list;
104 static pthread_mutex_t *hio_send_list_lock;
105 static pthread_cond_t *hio_send_list_cond;
106 /*
107  * There is one recv list for every component, although local components don't
108  * use recv lists as local requests are done synchronously.
109  */
110 static TAILQ_HEAD(, hio) *hio_recv_list;
111 static pthread_mutex_t *hio_recv_list_lock;
112 static pthread_cond_t *hio_recv_list_cond;
113 /*
114  * Request is placed on done list by the slowest component (the one that
115  * decreased hio_countdown from 1 to 0).
116  */
117 static TAILQ_HEAD(, hio) hio_done_list;
118 static pthread_mutex_t hio_done_list_lock;
119 static pthread_cond_t hio_done_list_cond;
120 /*
121  * Structure below are for interaction with sync thread.
122  */
123 static bool sync_inprogress;
124 static pthread_mutex_t sync_lock;
125 static pthread_cond_t sync_cond;
126 /*
127  * The lock below allows to synchornize access to remote connections.
128  */
129 static pthread_rwlock_t *hio_remote_lock;
130 static pthread_mutex_t hio_guard_lock;
131 static pthread_cond_t hio_guard_cond;
132 
133 /*
134  * Lock to synchronize metadata updates. Also synchronize access to
135  * hr_primary_localcnt and hr_primary_remotecnt fields.
136  */
137 static pthread_mutex_t metadata_lock;
138 
139 /*
140  * Maximum number of outstanding I/O requests.
141  */
142 #define	HAST_HIO_MAX	256
143 /*
144  * Number of components. At this point there are only two components: local
145  * and remote, but in the future it might be possible to use multiple local
146  * and remote components.
147  */
148 #define	HAST_NCOMPONENTS	2
149 /*
150  * Number of seconds to sleep before next reconnect try.
151  */
152 #define	RECONNECT_SLEEP		5
153 
154 #define	ISCONNECTED(res, no)	\
155 	((res)->hr_remotein != NULL && (res)->hr_remoteout != NULL)
156 
157 #define	QUEUE_INSERT1(hio, name, ncomp)	do {				\
158 	bool _wakeup;							\
159 									\
160 	mtx_lock(&hio_##name##_list_lock[(ncomp)]);			\
161 	_wakeup = TAILQ_EMPTY(&hio_##name##_list[(ncomp)]);		\
162 	TAILQ_INSERT_TAIL(&hio_##name##_list[(ncomp)], (hio),		\
163 	    hio_next[(ncomp)]);						\
164 	mtx_unlock(&hio_##name##_list_lock[ncomp]);			\
165 	if (_wakeup)							\
166 		cv_signal(&hio_##name##_list_cond[(ncomp)]);		\
167 } while (0)
168 #define	QUEUE_INSERT2(hio, name)	do {				\
169 	bool _wakeup;							\
170 									\
171 	mtx_lock(&hio_##name##_list_lock);				\
172 	_wakeup = TAILQ_EMPTY(&hio_##name##_list);			\
173 	TAILQ_INSERT_TAIL(&hio_##name##_list, (hio), hio_##name##_next);\
174 	mtx_unlock(&hio_##name##_list_lock);				\
175 	if (_wakeup)							\
176 		cv_signal(&hio_##name##_list_cond);			\
177 } while (0)
178 #define	QUEUE_TAKE1(hio, name, ncomp)	do {				\
179 	mtx_lock(&hio_##name##_list_lock[(ncomp)]);			\
180 	while (((hio) = TAILQ_FIRST(&hio_##name##_list[(ncomp)])) == NULL) { \
181 		cv_wait(&hio_##name##_list_cond[(ncomp)],		\
182 		    &hio_##name##_list_lock[(ncomp)]);			\
183 	}								\
184 	TAILQ_REMOVE(&hio_##name##_list[(ncomp)], (hio),		\
185 	    hio_next[(ncomp)]);						\
186 	mtx_unlock(&hio_##name##_list_lock[(ncomp)]);			\
187 } while (0)
188 #define	QUEUE_TAKE2(hio, name)	do {					\
189 	mtx_lock(&hio_##name##_list_lock);				\
190 	while (((hio) = TAILQ_FIRST(&hio_##name##_list)) == NULL) {	\
191 		cv_wait(&hio_##name##_list_cond,			\
192 		    &hio_##name##_list_lock);				\
193 	}								\
194 	TAILQ_REMOVE(&hio_##name##_list, (hio), hio_##name##_next);	\
195 	mtx_unlock(&hio_##name##_list_lock);				\
196 } while (0)
197 
198 #define	SYNCREQ(hio)		do { (hio)->hio_ggio.gctl_unit = -1; } while (0)
199 #define	ISSYNCREQ(hio)		((hio)->hio_ggio.gctl_unit == -1)
200 #define	SYNCREQDONE(hio)	do { (hio)->hio_ggio.gctl_unit = -2; } while (0)
201 #define	ISSYNCREQDONE(hio)	((hio)->hio_ggio.gctl_unit == -2)
202 
203 static struct hast_resource *gres;
204 
205 static pthread_mutex_t range_lock;
206 static struct rangelocks *range_regular;
207 static bool range_regular_wait;
208 static pthread_cond_t range_regular_cond;
209 static struct rangelocks *range_sync;
210 static bool range_sync_wait;
211 static pthread_cond_t range_sync_cond;
212 
213 static void *ggate_recv_thread(void *arg);
214 static void *local_send_thread(void *arg);
215 static void *remote_send_thread(void *arg);
216 static void *remote_recv_thread(void *arg);
217 static void *ggate_send_thread(void *arg);
218 static void *sync_thread(void *arg);
219 static void *guard_thread(void *arg);
220 
221 static void sighandler(int sig);
222 
223 static void
224 cleanup(struct hast_resource *res)
225 {
226 	int rerrno;
227 
228 	/* Remember errno. */
229 	rerrno = errno;
230 
231 	/*
232 	 * Close descriptor to /dev/hast/<name>
233 	 * to work-around race in the kernel.
234 	 */
235 	close(res->hr_localfd);
236 
237 	/* Destroy ggate provider if we created one. */
238 	if (res->hr_ggateunit >= 0) {
239 		struct g_gate_ctl_destroy ggiod;
240 
241 		ggiod.gctl_version = G_GATE_VERSION;
242 		ggiod.gctl_unit = res->hr_ggateunit;
243 		ggiod.gctl_force = 1;
244 		if (ioctl(res->hr_ggatefd, G_GATE_CMD_DESTROY, &ggiod) < 0) {
245 			pjdlog_warning("Unable to destroy hast/%s device",
246 			    res->hr_provname);
247 		}
248 		res->hr_ggateunit = -1;
249 	}
250 
251 	/* Restore errno. */
252 	errno = rerrno;
253 }
254 
255 static void
256 primary_exit(int exitcode, const char *fmt, ...)
257 {
258 	va_list ap;
259 
260 	assert(exitcode != EX_OK);
261 	va_start(ap, fmt);
262 	pjdlogv_errno(LOG_ERR, fmt, ap);
263 	va_end(ap);
264 	cleanup(gres);
265 	exit(exitcode);
266 }
267 
268 static void
269 primary_exitx(int exitcode, const char *fmt, ...)
270 {
271 	va_list ap;
272 
273 	va_start(ap, fmt);
274 	pjdlogv(exitcode == EX_OK ? LOG_INFO : LOG_ERR, fmt, ap);
275 	va_end(ap);
276 	cleanup(gres);
277 	exit(exitcode);
278 }
279 
280 static int
281 hast_activemap_flush(struct hast_resource *res)
282 {
283 	const unsigned char *buf;
284 	size_t size;
285 
286 	buf = activemap_bitmap(res->hr_amp, &size);
287 	assert(buf != NULL);
288 	assert((size % res->hr_local_sectorsize) == 0);
289 	if (pwrite(res->hr_localfd, buf, size, METADATA_SIZE) !=
290 	    (ssize_t)size) {
291 		KEEP_ERRNO(pjdlog_errno(LOG_ERR,
292 		    "Unable to flush activemap to disk"));
293 		return (-1);
294 	}
295 	return (0);
296 }
297 
298 static void
299 init_environment(struct hast_resource *res __unused)
300 {
301 	struct hio *hio;
302 	unsigned int ii, ncomps;
303 
304 	/*
305 	 * In the future it might be per-resource value.
306 	 */
307 	ncomps = HAST_NCOMPONENTS;
308 
309 	/*
310 	 * Allocate memory needed by lists.
311 	 */
312 	hio_send_list = malloc(sizeof(hio_send_list[0]) * ncomps);
313 	if (hio_send_list == NULL) {
314 		primary_exitx(EX_TEMPFAIL,
315 		    "Unable to allocate %zu bytes of memory for send lists.",
316 		    sizeof(hio_send_list[0]) * ncomps);
317 	}
318 	hio_send_list_lock = malloc(sizeof(hio_send_list_lock[0]) * ncomps);
319 	if (hio_send_list_lock == NULL) {
320 		primary_exitx(EX_TEMPFAIL,
321 		    "Unable to allocate %zu bytes of memory for send list locks.",
322 		    sizeof(hio_send_list_lock[0]) * ncomps);
323 	}
324 	hio_send_list_cond = malloc(sizeof(hio_send_list_cond[0]) * ncomps);
325 	if (hio_send_list_cond == NULL) {
326 		primary_exitx(EX_TEMPFAIL,
327 		    "Unable to allocate %zu bytes of memory for send list condition variables.",
328 		    sizeof(hio_send_list_cond[0]) * ncomps);
329 	}
330 	hio_recv_list = malloc(sizeof(hio_recv_list[0]) * ncomps);
331 	if (hio_recv_list == NULL) {
332 		primary_exitx(EX_TEMPFAIL,
333 		    "Unable to allocate %zu bytes of memory for recv lists.",
334 		    sizeof(hio_recv_list[0]) * ncomps);
335 	}
336 	hio_recv_list_lock = malloc(sizeof(hio_recv_list_lock[0]) * ncomps);
337 	if (hio_recv_list_lock == NULL) {
338 		primary_exitx(EX_TEMPFAIL,
339 		    "Unable to allocate %zu bytes of memory for recv list locks.",
340 		    sizeof(hio_recv_list_lock[0]) * ncomps);
341 	}
342 	hio_recv_list_cond = malloc(sizeof(hio_recv_list_cond[0]) * ncomps);
343 	if (hio_recv_list_cond == NULL) {
344 		primary_exitx(EX_TEMPFAIL,
345 		    "Unable to allocate %zu bytes of memory for recv list condition variables.",
346 		    sizeof(hio_recv_list_cond[0]) * ncomps);
347 	}
348 	hio_remote_lock = malloc(sizeof(hio_remote_lock[0]) * ncomps);
349 	if (hio_remote_lock == NULL) {
350 		primary_exitx(EX_TEMPFAIL,
351 		    "Unable to allocate %zu bytes of memory for remote connections locks.",
352 		    sizeof(hio_remote_lock[0]) * ncomps);
353 	}
354 
355 	/*
356 	 * Initialize lists, their locks and theirs condition variables.
357 	 */
358 	TAILQ_INIT(&hio_free_list);
359 	mtx_init(&hio_free_list_lock);
360 	cv_init(&hio_free_list_cond);
361 	for (ii = 0; ii < HAST_NCOMPONENTS; ii++) {
362 		TAILQ_INIT(&hio_send_list[ii]);
363 		mtx_init(&hio_send_list_lock[ii]);
364 		cv_init(&hio_send_list_cond[ii]);
365 		TAILQ_INIT(&hio_recv_list[ii]);
366 		mtx_init(&hio_recv_list_lock[ii]);
367 		cv_init(&hio_recv_list_cond[ii]);
368 		rw_init(&hio_remote_lock[ii]);
369 	}
370 	TAILQ_INIT(&hio_done_list);
371 	mtx_init(&hio_done_list_lock);
372 	cv_init(&hio_done_list_cond);
373 	mtx_init(&hio_guard_lock);
374 	cv_init(&hio_guard_cond);
375 	mtx_init(&metadata_lock);
376 
377 	/*
378 	 * Allocate requests pool and initialize requests.
379 	 */
380 	for (ii = 0; ii < HAST_HIO_MAX; ii++) {
381 		hio = malloc(sizeof(*hio));
382 		if (hio == NULL) {
383 			primary_exitx(EX_TEMPFAIL,
384 			    "Unable to allocate %zu bytes of memory for hio request.",
385 			    sizeof(*hio));
386 		}
387 		hio->hio_countdown = 0;
388 		hio->hio_errors = malloc(sizeof(hio->hio_errors[0]) * ncomps);
389 		if (hio->hio_errors == NULL) {
390 			primary_exitx(EX_TEMPFAIL,
391 			    "Unable allocate %zu bytes of memory for hio errors.",
392 			    sizeof(hio->hio_errors[0]) * ncomps);
393 		}
394 		hio->hio_next = malloc(sizeof(hio->hio_next[0]) * ncomps);
395 		if (hio->hio_next == NULL) {
396 			primary_exitx(EX_TEMPFAIL,
397 			    "Unable allocate %zu bytes of memory for hio_next field.",
398 			    sizeof(hio->hio_next[0]) * ncomps);
399 		}
400 		hio->hio_ggio.gctl_version = G_GATE_VERSION;
401 		hio->hio_ggio.gctl_data = malloc(MAXPHYS);
402 		if (hio->hio_ggio.gctl_data == NULL) {
403 			primary_exitx(EX_TEMPFAIL,
404 			    "Unable to allocate %zu bytes of memory for gctl_data.",
405 			    MAXPHYS);
406 		}
407 		hio->hio_ggio.gctl_length = MAXPHYS;
408 		hio->hio_ggio.gctl_error = 0;
409 		TAILQ_INSERT_HEAD(&hio_free_list, hio, hio_free_next);
410 	}
411 
412 	/*
413 	 * Turn on signals handling.
414 	 */
415 	signal(SIGINT, sighandler);
416 	signal(SIGTERM, sighandler);
417 }
418 
419 static void
420 init_local(struct hast_resource *res)
421 {
422 	unsigned char *buf;
423 	size_t mapsize;
424 
425 	if (metadata_read(res, true) < 0)
426 		exit(EX_NOINPUT);
427 	mtx_init(&res->hr_amp_lock);
428 	if (activemap_init(&res->hr_amp, res->hr_datasize, res->hr_extentsize,
429 	    res->hr_local_sectorsize, res->hr_keepdirty) < 0) {
430 		primary_exit(EX_TEMPFAIL, "Unable to create activemap");
431 	}
432 	mtx_init(&range_lock);
433 	cv_init(&range_regular_cond);
434 	if (rangelock_init(&range_regular) < 0)
435 		primary_exit(EX_TEMPFAIL, "Unable to create regular range lock");
436 	cv_init(&range_sync_cond);
437 	if (rangelock_init(&range_sync) < 0)
438 		primary_exit(EX_TEMPFAIL, "Unable to create sync range lock");
439 	mapsize = activemap_ondisk_size(res->hr_amp);
440 	buf = calloc(1, mapsize);
441 	if (buf == NULL) {
442 		primary_exitx(EX_TEMPFAIL,
443 		    "Unable to allocate buffer for activemap.");
444 	}
445 	if (pread(res->hr_localfd, buf, mapsize, METADATA_SIZE) !=
446 	    (ssize_t)mapsize) {
447 		primary_exit(EX_NOINPUT, "Unable to read activemap");
448 	}
449 	activemap_copyin(res->hr_amp, buf, mapsize);
450 	if (res->hr_resuid != 0)
451 		return;
452 	/*
453 	 * We're using provider for the first time, so we have to generate
454 	 * resource unique identifier and initialize local and remote counts.
455 	 */
456 	arc4random_buf(&res->hr_resuid, sizeof(res->hr_resuid));
457 	res->hr_primary_localcnt = 1;
458 	res->hr_primary_remotecnt = 0;
459 	if (metadata_write(res) < 0)
460 		exit(EX_NOINPUT);
461 }
462 
463 static bool
464 init_remote(struct hast_resource *res, struct proto_conn **inp,
465     struct proto_conn **outp)
466 {
467 	struct proto_conn *in, *out;
468 	struct nv *nvout, *nvin;
469 	const unsigned char *token;
470 	unsigned char *map;
471 	const char *errmsg;
472 	int32_t extentsize;
473 	int64_t datasize;
474 	uint32_t mapsize;
475 	size_t size;
476 
477 	assert((inp == NULL && outp == NULL) || (inp != NULL && outp != NULL));
478 
479 	in = out = NULL;
480 
481 	/* Prepare outgoing connection with remote node. */
482 	if (proto_client(res->hr_remoteaddr, &out) < 0) {
483 		primary_exit(EX_TEMPFAIL, "Unable to create connection to %s",
484 		    res->hr_remoteaddr);
485 	}
486 	/* Try to connect, but accept failure. */
487 	if (proto_connect(out) < 0) {
488 		pjdlog_errno(LOG_WARNING, "Unable to connect to %s",
489 		    res->hr_remoteaddr);
490 		goto close;
491 	}
492 	/* Error in setting timeout is not critical, but why should it fail? */
493 	if (proto_timeout(out, res->hr_timeout) < 0)
494 		pjdlog_errno(LOG_WARNING, "Unable to set connection timeout");
495 	/*
496 	 * First handshake step.
497 	 * Setup outgoing connection with remote node.
498 	 */
499 	nvout = nv_alloc();
500 	nv_add_string(nvout, res->hr_name, "resource");
501 	if (nv_error(nvout) != 0) {
502 		pjdlog_common(LOG_WARNING, 0, nv_error(nvout),
503 		    "Unable to allocate header for connection with %s",
504 		    res->hr_remoteaddr);
505 		nv_free(nvout);
506 		goto close;
507 	}
508 	if (hast_proto_send(res, out, nvout, NULL, 0) < 0) {
509 		pjdlog_errno(LOG_WARNING,
510 		    "Unable to send handshake header to %s",
511 		    res->hr_remoteaddr);
512 		nv_free(nvout);
513 		goto close;
514 	}
515 	nv_free(nvout);
516 	if (hast_proto_recv_hdr(out, &nvin) < 0) {
517 		pjdlog_errno(LOG_WARNING,
518 		    "Unable to receive handshake header from %s",
519 		    res->hr_remoteaddr);
520 		goto close;
521 	}
522 	errmsg = nv_get_string(nvin, "errmsg");
523 	if (errmsg != NULL) {
524 		pjdlog_warning("%s", errmsg);
525 		nv_free(nvin);
526 		goto close;
527 	}
528 	token = nv_get_uint8_array(nvin, &size, "token");
529 	if (token == NULL) {
530 		pjdlog_warning("Handshake header from %s has no 'token' field.",
531 		    res->hr_remoteaddr);
532 		nv_free(nvin);
533 		goto close;
534 	}
535 	if (size != sizeof(res->hr_token)) {
536 		pjdlog_warning("Handshake header from %s contains 'token' of wrong size (got %zu, expected %zu).",
537 		    res->hr_remoteaddr, size, sizeof(res->hr_token));
538 		nv_free(nvin);
539 		goto close;
540 	}
541 	bcopy(token, res->hr_token, sizeof(res->hr_token));
542 	nv_free(nvin);
543 
544 	/*
545 	 * Second handshake step.
546 	 * Setup incoming connection with remote node.
547 	 */
548 	if (proto_client(res->hr_remoteaddr, &in) < 0) {
549 		pjdlog_errno(LOG_WARNING, "Unable to create connection to %s",
550 		    res->hr_remoteaddr);
551 	}
552 	/* Try to connect, but accept failure. */
553 	if (proto_connect(in) < 0) {
554 		pjdlog_errno(LOG_WARNING, "Unable to connect to %s",
555 		    res->hr_remoteaddr);
556 		goto close;
557 	}
558 	/* Error in setting timeout is not critical, but why should it fail? */
559 	if (proto_timeout(in, res->hr_timeout) < 0)
560 		pjdlog_errno(LOG_WARNING, "Unable to set connection timeout");
561 	nvout = nv_alloc();
562 	nv_add_string(nvout, res->hr_name, "resource");
563 	nv_add_uint8_array(nvout, res->hr_token, sizeof(res->hr_token),
564 	    "token");
565 	nv_add_uint64(nvout, res->hr_resuid, "resuid");
566 	nv_add_uint64(nvout, res->hr_primary_localcnt, "localcnt");
567 	nv_add_uint64(nvout, res->hr_primary_remotecnt, "remotecnt");
568 	if (nv_error(nvout) != 0) {
569 		pjdlog_common(LOG_WARNING, 0, nv_error(nvout),
570 		    "Unable to allocate header for connection with %s",
571 		    res->hr_remoteaddr);
572 		nv_free(nvout);
573 		goto close;
574 	}
575 	if (hast_proto_send(res, in, nvout, NULL, 0) < 0) {
576 		pjdlog_errno(LOG_WARNING,
577 		    "Unable to send handshake header to %s",
578 		    res->hr_remoteaddr);
579 		nv_free(nvout);
580 		goto close;
581 	}
582 	nv_free(nvout);
583 	if (hast_proto_recv_hdr(out, &nvin) < 0) {
584 		pjdlog_errno(LOG_WARNING,
585 		    "Unable to receive handshake header from %s",
586 		    res->hr_remoteaddr);
587 		goto close;
588 	}
589 	errmsg = nv_get_string(nvin, "errmsg");
590 	if (errmsg != NULL) {
591 		pjdlog_warning("%s", errmsg);
592 		nv_free(nvin);
593 		goto close;
594 	}
595 	datasize = nv_get_int64(nvin, "datasize");
596 	if (datasize != res->hr_datasize) {
597 		pjdlog_warning("Data size differs between nodes (local=%jd, remote=%jd).",
598 		    (intmax_t)res->hr_datasize, (intmax_t)datasize);
599 		nv_free(nvin);
600 		goto close;
601 	}
602 	extentsize = nv_get_int32(nvin, "extentsize");
603 	if (extentsize != res->hr_extentsize) {
604 		pjdlog_warning("Extent size differs between nodes (local=%zd, remote=%zd).",
605 		    (ssize_t)res->hr_extentsize, (ssize_t)extentsize);
606 		nv_free(nvin);
607 		goto close;
608 	}
609 	res->hr_secondary_localcnt = nv_get_uint64(nvin, "localcnt");
610 	res->hr_secondary_remotecnt = nv_get_uint64(nvin, "remotecnt");
611 	res->hr_syncsrc = nv_get_uint8(nvin, "syncsrc");
612 	map = NULL;
613 	mapsize = nv_get_uint32(nvin, "mapsize");
614 	if (mapsize > 0) {
615 		map = malloc(mapsize);
616 		if (map == NULL) {
617 			pjdlog_error("Unable to allocate memory for remote activemap (mapsize=%ju).",
618 			    (uintmax_t)mapsize);
619 			nv_free(nvin);
620 			goto close;
621 		}
622 		/*
623 		 * Remote node have some dirty extents on its own, lets
624 		 * download its activemap.
625 		 */
626 		if (hast_proto_recv_data(res, out, nvin, map,
627 		    mapsize) < 0) {
628 			pjdlog_errno(LOG_ERR,
629 			    "Unable to receive remote activemap");
630 			nv_free(nvin);
631 			free(map);
632 			goto close;
633 		}
634 		/*
635 		 * Merge local and remote bitmaps.
636 		 */
637 		activemap_merge(res->hr_amp, map, mapsize);
638 		free(map);
639 		/*
640 		 * Now that we merged bitmaps from both nodes, flush it to the
641 		 * disk before we start to synchronize.
642 		 */
643 		(void)hast_activemap_flush(res);
644 	}
645 	pjdlog_info("Connected to %s.", res->hr_remoteaddr);
646 	if (inp != NULL && outp != NULL) {
647 		*inp = in;
648 		*outp = out;
649 	} else {
650 		res->hr_remotein = in;
651 		res->hr_remoteout = out;
652 	}
653 	return (true);
654 close:
655 	proto_close(out);
656 	if (in != NULL)
657 		proto_close(in);
658 	return (false);
659 }
660 
661 static void
662 sync_start(void)
663 {
664 
665 	mtx_lock(&sync_lock);
666 	sync_inprogress = true;
667 	mtx_unlock(&sync_lock);
668 	cv_signal(&sync_cond);
669 }
670 
671 static void
672 init_ggate(struct hast_resource *res)
673 {
674 	struct g_gate_ctl_create ggiocreate;
675 	struct g_gate_ctl_cancel ggiocancel;
676 
677 	/*
678 	 * We communicate with ggate via /dev/ggctl. Open it.
679 	 */
680 	res->hr_ggatefd = open("/dev/" G_GATE_CTL_NAME, O_RDWR);
681 	if (res->hr_ggatefd < 0)
682 		primary_exit(EX_OSFILE, "Unable to open /dev/" G_GATE_CTL_NAME);
683 	/*
684 	 * Create provider before trying to connect, as connection failure
685 	 * is not critical, but may take some time.
686 	 */
687 	ggiocreate.gctl_version = G_GATE_VERSION;
688 	ggiocreate.gctl_mediasize = res->hr_datasize;
689 	ggiocreate.gctl_sectorsize = res->hr_local_sectorsize;
690 	ggiocreate.gctl_flags = 0;
691 	ggiocreate.gctl_maxcount = G_GATE_MAX_QUEUE_SIZE;
692 	ggiocreate.gctl_timeout = 0;
693 	ggiocreate.gctl_unit = G_GATE_NAME_GIVEN;
694 	snprintf(ggiocreate.gctl_name, sizeof(ggiocreate.gctl_name), "hast/%s",
695 	    res->hr_provname);
696 	bzero(ggiocreate.gctl_info, sizeof(ggiocreate.gctl_info));
697 	if (ioctl(res->hr_ggatefd, G_GATE_CMD_CREATE, &ggiocreate) == 0) {
698 		pjdlog_info("Device hast/%s created.", res->hr_provname);
699 		res->hr_ggateunit = ggiocreate.gctl_unit;
700 		return;
701 	}
702 	if (errno != EEXIST) {
703 		primary_exit(EX_OSERR, "Unable to create hast/%s device",
704 		    res->hr_provname);
705 	}
706 	pjdlog_debug(1,
707 	    "Device hast/%s already exists, we will try to take it over.",
708 	    res->hr_provname);
709 	/*
710 	 * If we received EEXIST, we assume that the process who created the
711 	 * provider died and didn't clean up. In that case we will start from
712 	 * where he left of.
713 	 */
714 	ggiocancel.gctl_version = G_GATE_VERSION;
715 	ggiocancel.gctl_unit = G_GATE_NAME_GIVEN;
716 	snprintf(ggiocancel.gctl_name, sizeof(ggiocancel.gctl_name), "hast/%s",
717 	    res->hr_provname);
718 	if (ioctl(res->hr_ggatefd, G_GATE_CMD_CANCEL, &ggiocancel) == 0) {
719 		pjdlog_info("Device hast/%s recovered.", res->hr_provname);
720 		res->hr_ggateunit = ggiocancel.gctl_unit;
721 		return;
722 	}
723 	primary_exit(EX_OSERR, "Unable to take over hast/%s device",
724 	    res->hr_provname);
725 }
726 
727 void
728 hastd_primary(struct hast_resource *res)
729 {
730 	pthread_t td;
731 	pid_t pid;
732 	int error;
733 
734 	gres = res;
735 
736 	/*
737 	 * Create communication channel between parent and child.
738 	 */
739 	if (proto_client("socketpair://", &res->hr_ctrl) < 0) {
740 		KEEP_ERRNO((void)pidfile_remove(pfh));
741 		primary_exit(EX_OSERR,
742 		    "Unable to create control sockets between parent and child");
743 	}
744 
745 	pid = fork();
746 	if (pid < 0) {
747 		KEEP_ERRNO((void)pidfile_remove(pfh));
748 		primary_exit(EX_TEMPFAIL, "Unable to fork");
749 	}
750 
751 	if (pid > 0) {
752 		/* This is parent. */
753 		res->hr_workerpid = pid;
754 		return;
755 	}
756 	(void)pidfile_close(pfh);
757 
758 	setproctitle("%s (primary)", res->hr_name);
759 
760 	init_local(res);
761 	if (init_remote(res, NULL, NULL))
762 		sync_start();
763 	init_ggate(res);
764 	init_environment(res);
765 	error = pthread_create(&td, NULL, ggate_recv_thread, res);
766 	assert(error == 0);
767 	error = pthread_create(&td, NULL, local_send_thread, res);
768 	assert(error == 0);
769 	error = pthread_create(&td, NULL, remote_send_thread, res);
770 	assert(error == 0);
771 	error = pthread_create(&td, NULL, remote_recv_thread, res);
772 	assert(error == 0);
773 	error = pthread_create(&td, NULL, ggate_send_thread, res);
774 	assert(error == 0);
775 	error = pthread_create(&td, NULL, sync_thread, res);
776 	assert(error == 0);
777 	error = pthread_create(&td, NULL, ctrl_thread, res);
778 	assert(error == 0);
779 	(void)guard_thread(res);
780 }
781 
782 static void
783 reqlog(int loglevel, int debuglevel, struct g_gate_ctl_io *ggio, const char *fmt, ...)
784 {
785 	char msg[1024];
786 	va_list ap;
787 	int len;
788 
789 	va_start(ap, fmt);
790 	len = vsnprintf(msg, sizeof(msg), fmt, ap);
791 	va_end(ap);
792 	if ((size_t)len < sizeof(msg)) {
793 		switch (ggio->gctl_cmd) {
794 		case BIO_READ:
795 			(void)snprintf(msg + len, sizeof(msg) - len,
796 			    "READ(%ju, %ju).", (uintmax_t)ggio->gctl_offset,
797 			    (uintmax_t)ggio->gctl_length);
798 			break;
799 		case BIO_DELETE:
800 			(void)snprintf(msg + len, sizeof(msg) - len,
801 			    "DELETE(%ju, %ju).", (uintmax_t)ggio->gctl_offset,
802 			    (uintmax_t)ggio->gctl_length);
803 			break;
804 		case BIO_FLUSH:
805 			(void)snprintf(msg + len, sizeof(msg) - len, "FLUSH.");
806 			break;
807 		case BIO_WRITE:
808 			(void)snprintf(msg + len, sizeof(msg) - len,
809 			    "WRITE(%ju, %ju).", (uintmax_t)ggio->gctl_offset,
810 			    (uintmax_t)ggio->gctl_length);
811 			break;
812 		default:
813 			(void)snprintf(msg + len, sizeof(msg) - len,
814 			    "UNKNOWN(%u).", (unsigned int)ggio->gctl_cmd);
815 			break;
816 		}
817 	}
818 	pjdlog_common(loglevel, debuglevel, -1, "%s", msg);
819 }
820 
821 static void
822 remote_close(struct hast_resource *res, int ncomp)
823 {
824 
825 	rw_wlock(&hio_remote_lock[ncomp]);
826 	/*
827 	 * A race is possible between dropping rlock and acquiring wlock -
828 	 * another thread can close connection in-between.
829 	 */
830 	if (!ISCONNECTED(res, ncomp)) {
831 		assert(res->hr_remotein == NULL);
832 		assert(res->hr_remoteout == NULL);
833 		rw_unlock(&hio_remote_lock[ncomp]);
834 		return;
835 	}
836 
837 	assert(res->hr_remotein != NULL);
838 	assert(res->hr_remoteout != NULL);
839 
840 	pjdlog_debug(2, "Closing old incoming connection to %s.",
841 	    res->hr_remoteaddr);
842 	proto_close(res->hr_remotein);
843 	res->hr_remotein = NULL;
844 	pjdlog_debug(2, "Closing old outgoing connection to %s.",
845 	    res->hr_remoteaddr);
846 	proto_close(res->hr_remoteout);
847 	res->hr_remoteout = NULL;
848 
849 	rw_unlock(&hio_remote_lock[ncomp]);
850 
851 	/*
852 	 * Stop synchronization if in-progress.
853 	 */
854 	mtx_lock(&sync_lock);
855 	if (sync_inprogress)
856 		sync_inprogress = false;
857 	mtx_unlock(&sync_lock);
858 
859 	/*
860 	 * Wake up guard thread, so it can immediately start reconnect.
861 	 */
862 	mtx_lock(&hio_guard_lock);
863 	cv_signal(&hio_guard_cond);
864 	mtx_unlock(&hio_guard_lock);
865 }
866 
867 /*
868  * Thread receives ggate I/O requests from the kernel and passes them to
869  * appropriate threads:
870  * WRITE - always goes to both local_send and remote_send threads
871  * READ (when the block is up-to-date on local component) -
872  *	only local_send thread
873  * READ (when the block isn't up-to-date on local component) -
874  *	only remote_send thread
875  * DELETE - always goes to both local_send and remote_send threads
876  * FLUSH - always goes to both local_send and remote_send threads
877  */
878 static void *
879 ggate_recv_thread(void *arg)
880 {
881 	struct hast_resource *res = arg;
882 	struct g_gate_ctl_io *ggio;
883 	struct hio *hio;
884 	unsigned int ii, ncomp, ncomps;
885 	int error;
886 
887 	ncomps = HAST_NCOMPONENTS;
888 
889 	for (;;) {
890 		pjdlog_debug(2, "ggate_recv: Taking free request.");
891 		QUEUE_TAKE2(hio, free);
892 		pjdlog_debug(2, "ggate_recv: (%p) Got free request.", hio);
893 		ggio = &hio->hio_ggio;
894 		ggio->gctl_unit = res->hr_ggateunit;
895 		ggio->gctl_length = MAXPHYS;
896 		ggio->gctl_error = 0;
897 		pjdlog_debug(2,
898 		    "ggate_recv: (%p) Waiting for request from the kernel.",
899 		    hio);
900 		if (ioctl(res->hr_ggatefd, G_GATE_CMD_START, ggio) < 0) {
901 			if (sigexit_received)
902 				pthread_exit(NULL);
903 			primary_exit(EX_OSERR, "G_GATE_CMD_START failed");
904 		}
905 		error = ggio->gctl_error;
906 		switch (error) {
907 		case 0:
908 			break;
909 		case ECANCELED:
910 			/* Exit gracefully. */
911 			if (!sigexit_received) {
912 				pjdlog_debug(2,
913 				    "ggate_recv: (%p) Received cancel from the kernel.",
914 				    hio);
915 				pjdlog_info("Received cancel from the kernel, exiting.");
916 			}
917 			pthread_exit(NULL);
918 		case ENOMEM:
919 			/*
920 			 * Buffer too small? Impossible, we allocate MAXPHYS
921 			 * bytes - request can't be bigger than that.
922 			 */
923 			/* FALLTHROUGH */
924 		case ENXIO:
925 		default:
926 			primary_exitx(EX_OSERR, "G_GATE_CMD_START failed: %s.",
927 			    strerror(error));
928 		}
929 		for (ii = 0; ii < ncomps; ii++)
930 			hio->hio_errors[ii] = EINVAL;
931 		reqlog(LOG_DEBUG, 2, ggio,
932 		    "ggate_recv: (%p) Request received from the kernel: ",
933 		    hio);
934 		/*
935 		 * Inform all components about new write request.
936 		 * For read request prefer local component unless the given
937 		 * range is out-of-date, then use remote component.
938 		 */
939 		switch (ggio->gctl_cmd) {
940 		case BIO_READ:
941 			pjdlog_debug(2,
942 			    "ggate_recv: (%p) Moving request to the send queue.",
943 			    hio);
944 			refcount_init(&hio->hio_countdown, 1);
945 			mtx_lock(&metadata_lock);
946 			if (res->hr_syncsrc == HAST_SYNCSRC_UNDEF ||
947 			    res->hr_syncsrc == HAST_SYNCSRC_PRIMARY) {
948 				/*
949 				 * This range is up-to-date on local component,
950 				 * so handle request locally.
951 				 */
952 				 /* Local component is 0 for now. */
953 				ncomp = 0;
954 			} else /* if (res->hr_syncsrc ==
955 			    HAST_SYNCSRC_SECONDARY) */ {
956 				assert(res->hr_syncsrc ==
957 				    HAST_SYNCSRC_SECONDARY);
958 				/*
959 				 * This range is out-of-date on local component,
960 				 * so send request to the remote node.
961 				 */
962 				 /* Remote component is 1 for now. */
963 				ncomp = 1;
964 			}
965 			mtx_unlock(&metadata_lock);
966 			QUEUE_INSERT1(hio, send, ncomp);
967 			break;
968 		case BIO_WRITE:
969 			for (;;) {
970 				mtx_lock(&range_lock);
971 				if (rangelock_islocked(range_sync,
972 				    ggio->gctl_offset, ggio->gctl_length)) {
973 					pjdlog_debug(2,
974 					    "regular: Range offset=%jd length=%zu locked.",
975 					    (intmax_t)ggio->gctl_offset,
976 					    (size_t)ggio->gctl_length);
977 					range_regular_wait = true;
978 					cv_wait(&range_regular_cond, &range_lock);
979 					range_regular_wait = false;
980 					mtx_unlock(&range_lock);
981 					continue;
982 				}
983 				if (rangelock_add(range_regular,
984 				    ggio->gctl_offset, ggio->gctl_length) < 0) {
985 					mtx_unlock(&range_lock);
986 					pjdlog_debug(2,
987 					    "regular: Range offset=%jd length=%zu is already locked, waiting.",
988 					    (intmax_t)ggio->gctl_offset,
989 					    (size_t)ggio->gctl_length);
990 					sleep(1);
991 					continue;
992 				}
993 				mtx_unlock(&range_lock);
994 				break;
995 			}
996 			mtx_lock(&res->hr_amp_lock);
997 			if (activemap_write_start(res->hr_amp,
998 			    ggio->gctl_offset, ggio->gctl_length)) {
999 				(void)hast_activemap_flush(res);
1000 			}
1001 			mtx_unlock(&res->hr_amp_lock);
1002 			/* FALLTHROUGH */
1003 		case BIO_DELETE:
1004 		case BIO_FLUSH:
1005 			pjdlog_debug(2,
1006 			    "ggate_recv: (%p) Moving request to the send queues.",
1007 			    hio);
1008 			refcount_init(&hio->hio_countdown, ncomps);
1009 			for (ii = 0; ii < ncomps; ii++)
1010 				QUEUE_INSERT1(hio, send, ii);
1011 			break;
1012 		}
1013 	}
1014 	/* NOTREACHED */
1015 	return (NULL);
1016 }
1017 
1018 /*
1019  * Thread reads from or writes to local component.
1020  * If local read fails, it redirects it to remote_send thread.
1021  */
1022 static void *
1023 local_send_thread(void *arg)
1024 {
1025 	struct hast_resource *res = arg;
1026 	struct g_gate_ctl_io *ggio;
1027 	struct hio *hio;
1028 	unsigned int ncomp, rncomp;
1029 	ssize_t ret;
1030 
1031 	/* Local component is 0 for now. */
1032 	ncomp = 0;
1033 	/* Remote component is 1 for now. */
1034 	rncomp = 1;
1035 
1036 	for (;;) {
1037 		pjdlog_debug(2, "local_send: Taking request.");
1038 		QUEUE_TAKE1(hio, send, ncomp);
1039 		pjdlog_debug(2, "local_send: (%p) Got request.", hio);
1040 		ggio = &hio->hio_ggio;
1041 		switch (ggio->gctl_cmd) {
1042 		case BIO_READ:
1043 			ret = pread(res->hr_localfd, ggio->gctl_data,
1044 			    ggio->gctl_length,
1045 			    ggio->gctl_offset + res->hr_localoff);
1046 			if (ret == ggio->gctl_length)
1047 				hio->hio_errors[ncomp] = 0;
1048 			else {
1049 				/*
1050 				 * If READ failed, try to read from remote node.
1051 				 */
1052 				QUEUE_INSERT1(hio, send, rncomp);
1053 				continue;
1054 			}
1055 			break;
1056 		case BIO_WRITE:
1057 			ret = pwrite(res->hr_localfd, ggio->gctl_data,
1058 			    ggio->gctl_length,
1059 			    ggio->gctl_offset + res->hr_localoff);
1060 			if (ret < 0)
1061 				hio->hio_errors[ncomp] = errno;
1062 			else if (ret != ggio->gctl_length)
1063 				hio->hio_errors[ncomp] = EIO;
1064 			else
1065 				hio->hio_errors[ncomp] = 0;
1066 			break;
1067 		case BIO_DELETE:
1068 			ret = g_delete(res->hr_localfd,
1069 			    ggio->gctl_offset + res->hr_localoff,
1070 			    ggio->gctl_length);
1071 			if (ret < 0)
1072 				hio->hio_errors[ncomp] = errno;
1073 			else
1074 				hio->hio_errors[ncomp] = 0;
1075 			break;
1076 		case BIO_FLUSH:
1077 			ret = g_flush(res->hr_localfd);
1078 			if (ret < 0)
1079 				hio->hio_errors[ncomp] = errno;
1080 			else
1081 				hio->hio_errors[ncomp] = 0;
1082 			break;
1083 		}
1084 		if (refcount_release(&hio->hio_countdown)) {
1085 			if (ISSYNCREQ(hio)) {
1086 				mtx_lock(&sync_lock);
1087 				SYNCREQDONE(hio);
1088 				mtx_unlock(&sync_lock);
1089 				cv_signal(&sync_cond);
1090 			} else {
1091 				pjdlog_debug(2,
1092 				    "local_send: (%p) Moving request to the done queue.",
1093 				    hio);
1094 				QUEUE_INSERT2(hio, done);
1095 			}
1096 		}
1097 	}
1098 	/* NOTREACHED */
1099 	return (NULL);
1100 }
1101 
1102 /*
1103  * Thread sends request to secondary node.
1104  */
1105 static void *
1106 remote_send_thread(void *arg)
1107 {
1108 	struct hast_resource *res = arg;
1109 	struct g_gate_ctl_io *ggio;
1110 	struct hio *hio;
1111 	struct nv *nv;
1112 	unsigned int ncomp;
1113 	bool wakeup;
1114 	uint64_t offset, length;
1115 	uint8_t cmd;
1116 	void *data;
1117 
1118 	/* Remote component is 1 for now. */
1119 	ncomp = 1;
1120 
1121 	for (;;) {
1122 		pjdlog_debug(2, "remote_send: Taking request.");
1123 		QUEUE_TAKE1(hio, send, ncomp);
1124 		pjdlog_debug(2, "remote_send: (%p) Got request.", hio);
1125 		ggio = &hio->hio_ggio;
1126 		switch (ggio->gctl_cmd) {
1127 		case BIO_READ:
1128 			cmd = HIO_READ;
1129 			data = NULL;
1130 			offset = ggio->gctl_offset;
1131 			length = ggio->gctl_length;
1132 			break;
1133 		case BIO_WRITE:
1134 			cmd = HIO_WRITE;
1135 			data = ggio->gctl_data;
1136 			offset = ggio->gctl_offset;
1137 			length = ggio->gctl_length;
1138 			break;
1139 		case BIO_DELETE:
1140 			cmd = HIO_DELETE;
1141 			data = NULL;
1142 			offset = ggio->gctl_offset;
1143 			length = ggio->gctl_length;
1144 			break;
1145 		case BIO_FLUSH:
1146 			cmd = HIO_FLUSH;
1147 			data = NULL;
1148 			offset = 0;
1149 			length = 0;
1150 			break;
1151 		default:
1152 			assert(!"invalid condition");
1153 			abort();
1154 		}
1155 		nv = nv_alloc();
1156 		nv_add_uint8(nv, cmd, "cmd");
1157 		nv_add_uint64(nv, (uint64_t)ggio->gctl_seq, "seq");
1158 		nv_add_uint64(nv, offset, "offset");
1159 		nv_add_uint64(nv, length, "length");
1160 		if (nv_error(nv) != 0) {
1161 			hio->hio_errors[ncomp] = nv_error(nv);
1162 			pjdlog_debug(2,
1163 			    "remote_send: (%p) Unable to prepare header to send.",
1164 			    hio);
1165 			reqlog(LOG_ERR, 0, ggio,
1166 			    "Unable to prepare header to send (%s): ",
1167 			    strerror(nv_error(nv)));
1168 			/* Move failed request immediately to the done queue. */
1169 			goto done_queue;
1170 		}
1171 		pjdlog_debug(2,
1172 		    "remote_send: (%p) Moving request to the recv queue.",
1173 		    hio);
1174 		/*
1175 		 * Protect connection from disappearing.
1176 		 */
1177 		rw_rlock(&hio_remote_lock[ncomp]);
1178 		if (!ISCONNECTED(res, ncomp)) {
1179 			rw_unlock(&hio_remote_lock[ncomp]);
1180 			hio->hio_errors[ncomp] = ENOTCONN;
1181 			goto done_queue;
1182 		}
1183 		/*
1184 		 * Move the request to recv queue before sending it, because
1185 		 * in different order we can get reply before we move request
1186 		 * to recv queue.
1187 		 */
1188 		mtx_lock(&hio_recv_list_lock[ncomp]);
1189 		wakeup = TAILQ_EMPTY(&hio_recv_list[ncomp]);
1190 		TAILQ_INSERT_TAIL(&hio_recv_list[ncomp], hio, hio_next[ncomp]);
1191 		mtx_unlock(&hio_recv_list_lock[ncomp]);
1192 		if (hast_proto_send(res, res->hr_remoteout, nv, data,
1193 		    data != NULL ? length : 0) < 0) {
1194 			hio->hio_errors[ncomp] = errno;
1195 			rw_unlock(&hio_remote_lock[ncomp]);
1196 			remote_close(res, ncomp);
1197 			pjdlog_debug(2,
1198 			    "remote_send: (%p) Unable to send request.", hio);
1199 			reqlog(LOG_ERR, 0, ggio,
1200 			    "Unable to send request (%s): ",
1201 			    strerror(hio->hio_errors[ncomp]));
1202 			/*
1203 			 * Take request back from the receive queue and move
1204 			 * it immediately to the done queue.
1205 			 */
1206 			mtx_lock(&hio_recv_list_lock[ncomp]);
1207 			TAILQ_REMOVE(&hio_recv_list[ncomp], hio, hio_next[ncomp]);
1208 			mtx_unlock(&hio_recv_list_lock[ncomp]);
1209 			goto done_queue;
1210 		}
1211 		rw_unlock(&hio_remote_lock[ncomp]);
1212 		nv_free(nv);
1213 		if (wakeup)
1214 			cv_signal(&hio_recv_list_cond[ncomp]);
1215 		continue;
1216 done_queue:
1217 		nv_free(nv);
1218 		if (ISSYNCREQ(hio)) {
1219 			if (!refcount_release(&hio->hio_countdown))
1220 				continue;
1221 			mtx_lock(&sync_lock);
1222 			SYNCREQDONE(hio);
1223 			mtx_unlock(&sync_lock);
1224 			cv_signal(&sync_cond);
1225 			continue;
1226 		}
1227 		if (ggio->gctl_cmd == BIO_WRITE) {
1228 			mtx_lock(&res->hr_amp_lock);
1229 			if (activemap_need_sync(res->hr_amp, ggio->gctl_offset,
1230 			    ggio->gctl_length)) {
1231 				(void)hast_activemap_flush(res);
1232 			}
1233 			mtx_unlock(&res->hr_amp_lock);
1234 		}
1235 		if (!refcount_release(&hio->hio_countdown))
1236 			continue;
1237 		pjdlog_debug(2,
1238 		    "remote_send: (%p) Moving request to the done queue.",
1239 		    hio);
1240 		QUEUE_INSERT2(hio, done);
1241 	}
1242 	/* NOTREACHED */
1243 	return (NULL);
1244 }
1245 
1246 /*
1247  * Thread receives answer from secondary node and passes it to ggate_send
1248  * thread.
1249  */
1250 static void *
1251 remote_recv_thread(void *arg)
1252 {
1253 	struct hast_resource *res = arg;
1254 	struct g_gate_ctl_io *ggio;
1255 	struct hio *hio;
1256 	struct nv *nv;
1257 	unsigned int ncomp;
1258 	uint64_t seq;
1259 	int error;
1260 
1261 	/* Remote component is 1 for now. */
1262 	ncomp = 1;
1263 
1264 	for (;;) {
1265 		/* Wait until there is anything to receive. */
1266 		mtx_lock(&hio_recv_list_lock[ncomp]);
1267 		while (TAILQ_EMPTY(&hio_recv_list[ncomp])) {
1268 			pjdlog_debug(2, "remote_recv: No requests, waiting.");
1269 			cv_wait(&hio_recv_list_cond[ncomp],
1270 			    &hio_recv_list_lock[ncomp]);
1271 		}
1272 		mtx_unlock(&hio_recv_list_lock[ncomp]);
1273 		rw_rlock(&hio_remote_lock[ncomp]);
1274 		if (!ISCONNECTED(res, ncomp)) {
1275 			rw_unlock(&hio_remote_lock[ncomp]);
1276 			/*
1277 			 * Connection is dead, so move all pending requests to
1278 			 * the done queue (one-by-one).
1279 			 */
1280 			mtx_lock(&hio_recv_list_lock[ncomp]);
1281 			hio = TAILQ_FIRST(&hio_recv_list[ncomp]);
1282 			assert(hio != NULL);
1283 			TAILQ_REMOVE(&hio_recv_list[ncomp], hio,
1284 			    hio_next[ncomp]);
1285 			mtx_unlock(&hio_recv_list_lock[ncomp]);
1286 			goto done_queue;
1287 		}
1288 		if (hast_proto_recv_hdr(res->hr_remotein, &nv) < 0) {
1289 			pjdlog_errno(LOG_ERR,
1290 			    "Unable to receive reply header");
1291 			rw_unlock(&hio_remote_lock[ncomp]);
1292 			remote_close(res, ncomp);
1293 			continue;
1294 		}
1295 		rw_unlock(&hio_remote_lock[ncomp]);
1296 		seq = nv_get_uint64(nv, "seq");
1297 		if (seq == 0) {
1298 			pjdlog_error("Header contains no 'seq' field.");
1299 			nv_free(nv);
1300 			continue;
1301 		}
1302 		mtx_lock(&hio_recv_list_lock[ncomp]);
1303 		TAILQ_FOREACH(hio, &hio_recv_list[ncomp], hio_next[ncomp]) {
1304 			if (hio->hio_ggio.gctl_seq == seq) {
1305 				TAILQ_REMOVE(&hio_recv_list[ncomp], hio,
1306 				    hio_next[ncomp]);
1307 				break;
1308 			}
1309 		}
1310 		mtx_unlock(&hio_recv_list_lock[ncomp]);
1311 		if (hio == NULL) {
1312 			pjdlog_error("Found no request matching received 'seq' field (%ju).",
1313 			    (uintmax_t)seq);
1314 			nv_free(nv);
1315 			continue;
1316 		}
1317 		error = nv_get_int16(nv, "error");
1318 		if (error != 0) {
1319 			/* Request failed on remote side. */
1320 			hio->hio_errors[ncomp] = 0;
1321 			nv_free(nv);
1322 			goto done_queue;
1323 		}
1324 		ggio = &hio->hio_ggio;
1325 		switch (ggio->gctl_cmd) {
1326 		case BIO_READ:
1327 			rw_rlock(&hio_remote_lock[ncomp]);
1328 			if (!ISCONNECTED(res, ncomp)) {
1329 				rw_unlock(&hio_remote_lock[ncomp]);
1330 				nv_free(nv);
1331 				goto done_queue;
1332 			}
1333 			if (hast_proto_recv_data(res, res->hr_remotein, nv,
1334 			    ggio->gctl_data, ggio->gctl_length) < 0) {
1335 				hio->hio_errors[ncomp] = errno;
1336 				pjdlog_errno(LOG_ERR,
1337 				    "Unable to receive reply data");
1338 				rw_unlock(&hio_remote_lock[ncomp]);
1339 				nv_free(nv);
1340 				remote_close(res, ncomp);
1341 				goto done_queue;
1342 			}
1343 			rw_unlock(&hio_remote_lock[ncomp]);
1344 			break;
1345 		case BIO_WRITE:
1346 		case BIO_DELETE:
1347 		case BIO_FLUSH:
1348 			break;
1349 		default:
1350 			assert(!"invalid condition");
1351 			abort();
1352 		}
1353 		hio->hio_errors[ncomp] = 0;
1354 		nv_free(nv);
1355 done_queue:
1356 		if (refcount_release(&hio->hio_countdown)) {
1357 			if (ISSYNCREQ(hio)) {
1358 				mtx_lock(&sync_lock);
1359 				SYNCREQDONE(hio);
1360 				mtx_unlock(&sync_lock);
1361 				cv_signal(&sync_cond);
1362 			} else {
1363 				pjdlog_debug(2,
1364 				    "remote_recv: (%p) Moving request to the done queue.",
1365 				    hio);
1366 				QUEUE_INSERT2(hio, done);
1367 			}
1368 		}
1369 	}
1370 	/* NOTREACHED */
1371 	return (NULL);
1372 }
1373 
1374 /*
1375  * Thread sends answer to the kernel.
1376  */
1377 static void *
1378 ggate_send_thread(void *arg)
1379 {
1380 	struct hast_resource *res = arg;
1381 	struct g_gate_ctl_io *ggio;
1382 	struct hio *hio;
1383 	unsigned int ii, ncomp, ncomps;
1384 
1385 	ncomps = HAST_NCOMPONENTS;
1386 
1387 	for (;;) {
1388 		pjdlog_debug(2, "ggate_send: Taking request.");
1389 		QUEUE_TAKE2(hio, done);
1390 		pjdlog_debug(2, "ggate_send: (%p) Got request.", hio);
1391 		ggio = &hio->hio_ggio;
1392 		for (ii = 0; ii < ncomps; ii++) {
1393 			if (hio->hio_errors[ii] == 0) {
1394 				/*
1395 				 * One successful request is enough to declare
1396 				 * success.
1397 				 */
1398 				ggio->gctl_error = 0;
1399 				break;
1400 			}
1401 		}
1402 		if (ii == ncomps) {
1403 			/*
1404 			 * None of the requests were successful.
1405 			 * Use first error.
1406 			 */
1407 			ggio->gctl_error = hio->hio_errors[0];
1408 		}
1409 		if (ggio->gctl_error == 0 && ggio->gctl_cmd == BIO_WRITE) {
1410 			mtx_lock(&res->hr_amp_lock);
1411 			activemap_write_complete(res->hr_amp,
1412 			    ggio->gctl_offset, ggio->gctl_length);
1413 			mtx_unlock(&res->hr_amp_lock);
1414 		}
1415 		if (ggio->gctl_cmd == BIO_WRITE) {
1416 			/*
1417 			 * Unlock range we locked.
1418 			 */
1419 			mtx_lock(&range_lock);
1420 			rangelock_del(range_regular, ggio->gctl_offset,
1421 			    ggio->gctl_length);
1422 			if (range_sync_wait)
1423 				cv_signal(&range_sync_cond);
1424 			mtx_unlock(&range_lock);
1425 			/*
1426 			 * Bump local count if this is first write after
1427 			 * connection failure with remote node.
1428 			 */
1429 			ncomp = 1;
1430 			rw_rlock(&hio_remote_lock[ncomp]);
1431 			if (!ISCONNECTED(res, ncomp)) {
1432 				mtx_lock(&metadata_lock);
1433 				if (res->hr_primary_localcnt ==
1434 				    res->hr_secondary_remotecnt) {
1435 					res->hr_primary_localcnt++;
1436 					pjdlog_debug(1,
1437 					    "Increasing localcnt to %ju.",
1438 					    (uintmax_t)res->hr_primary_localcnt);
1439 					(void)metadata_write(res);
1440 				}
1441 				mtx_unlock(&metadata_lock);
1442 			}
1443 			rw_unlock(&hio_remote_lock[ncomp]);
1444 		}
1445 		if (ioctl(res->hr_ggatefd, G_GATE_CMD_DONE, ggio) < 0)
1446 			primary_exit(EX_OSERR, "G_GATE_CMD_DONE failed");
1447 		pjdlog_debug(2,
1448 		    "ggate_send: (%p) Moving request to the free queue.", hio);
1449 		QUEUE_INSERT2(hio, free);
1450 	}
1451 	/* NOTREACHED */
1452 	return (NULL);
1453 }
1454 
1455 /*
1456  * Thread synchronize local and remote components.
1457  */
1458 static void *
1459 sync_thread(void *arg __unused)
1460 {
1461 	struct hast_resource *res = arg;
1462 	struct hio *hio;
1463 	struct g_gate_ctl_io *ggio;
1464 	unsigned int ii, ncomp, ncomps;
1465 	off_t offset, length, synced;
1466 	bool dorewind;
1467 	int syncext;
1468 
1469 	ncomps = HAST_NCOMPONENTS;
1470 	dorewind = true;
1471 	synced = 0;
1472 
1473 	for (;;) {
1474 		mtx_lock(&sync_lock);
1475 		while (!sync_inprogress) {
1476 			dorewind = true;
1477 			synced = 0;
1478 			cv_wait(&sync_cond, &sync_lock);
1479 		}
1480 		mtx_unlock(&sync_lock);
1481 		/*
1482 		 * Obtain offset at which we should synchronize.
1483 		 * Rewind synchronization if needed.
1484 		 */
1485 		mtx_lock(&res->hr_amp_lock);
1486 		if (dorewind)
1487 			activemap_sync_rewind(res->hr_amp);
1488 		offset = activemap_sync_offset(res->hr_amp, &length, &syncext);
1489 		if (syncext != -1) {
1490 			/*
1491 			 * We synchronized entire syncext extent, we can mark
1492 			 * it as clean now.
1493 			 */
1494 			if (activemap_extent_complete(res->hr_amp, syncext))
1495 				(void)hast_activemap_flush(res);
1496 		}
1497 		mtx_unlock(&res->hr_amp_lock);
1498 		if (dorewind) {
1499 			dorewind = false;
1500 			if (offset < 0)
1501 				pjdlog_info("Nodes are in sync.");
1502 			else {
1503 				pjdlog_info("Synchronization started. %ju bytes to go.",
1504 				    (uintmax_t)(res->hr_extentsize *
1505 				    activemap_ndirty(res->hr_amp)));
1506 			}
1507 		}
1508 		if (offset < 0) {
1509 			mtx_lock(&sync_lock);
1510 			sync_inprogress = false;
1511 			mtx_unlock(&sync_lock);
1512 			pjdlog_debug(1, "Nothing to synchronize.");
1513 			/*
1514 			 * Synchronization complete, make both localcnt and
1515 			 * remotecnt equal.
1516 			 */
1517 			ncomp = 1;
1518 			rw_rlock(&hio_remote_lock[ncomp]);
1519 			if (ISCONNECTED(res, ncomp)) {
1520 				if (synced > 0) {
1521 					pjdlog_info("Synchronization complete. "
1522 					    "%jd bytes synchronized.",
1523 					    (intmax_t)synced);
1524 				}
1525 				mtx_lock(&metadata_lock);
1526 				res->hr_syncsrc = HAST_SYNCSRC_UNDEF;
1527 				res->hr_primary_localcnt =
1528 				    res->hr_secondary_localcnt;
1529 				res->hr_primary_remotecnt =
1530 				    res->hr_secondary_remotecnt;
1531 				pjdlog_debug(1,
1532 				    "Setting localcnt to %ju and remotecnt to %ju.",
1533 				    (uintmax_t)res->hr_primary_localcnt,
1534 				    (uintmax_t)res->hr_secondary_localcnt);
1535 				(void)metadata_write(res);
1536 				mtx_unlock(&metadata_lock);
1537 			} else if (synced > 0) {
1538 				pjdlog_info("Synchronization interrupted. "
1539 				    "%jd bytes synchronized so far.",
1540 				    (intmax_t)synced);
1541 			}
1542 			rw_unlock(&hio_remote_lock[ncomp]);
1543 			continue;
1544 		}
1545 		pjdlog_debug(2, "sync: Taking free request.");
1546 		QUEUE_TAKE2(hio, free);
1547 		pjdlog_debug(2, "sync: (%p) Got free request.", hio);
1548 		/*
1549 		 * Lock the range we are going to synchronize. We don't want
1550 		 * race where someone writes between our read and write.
1551 		 */
1552 		for (;;) {
1553 			mtx_lock(&range_lock);
1554 			if (rangelock_islocked(range_regular, offset, length)) {
1555 				pjdlog_debug(2,
1556 				    "sync: Range offset=%jd length=%jd locked.",
1557 				    (intmax_t)offset, (intmax_t)length);
1558 				range_sync_wait = true;
1559 				cv_wait(&range_sync_cond, &range_lock);
1560 				range_sync_wait = false;
1561 				mtx_unlock(&range_lock);
1562 				continue;
1563 			}
1564 			if (rangelock_add(range_sync, offset, length) < 0) {
1565 				mtx_unlock(&range_lock);
1566 				pjdlog_debug(2,
1567 				    "sync: Range offset=%jd length=%jd is already locked, waiting.",
1568 				    (intmax_t)offset, (intmax_t)length);
1569 				sleep(1);
1570 				continue;
1571 			}
1572 			mtx_unlock(&range_lock);
1573 			break;
1574 		}
1575 		/*
1576 		 * First read the data from synchronization source.
1577 		 */
1578 		SYNCREQ(hio);
1579 		ggio = &hio->hio_ggio;
1580 		ggio->gctl_cmd = BIO_READ;
1581 		ggio->gctl_offset = offset;
1582 		ggio->gctl_length = length;
1583 		ggio->gctl_error = 0;
1584 		for (ii = 0; ii < ncomps; ii++)
1585 			hio->hio_errors[ii] = EINVAL;
1586 		reqlog(LOG_DEBUG, 2, ggio, "sync: (%p) Sending sync request: ",
1587 		    hio);
1588 		pjdlog_debug(2, "sync: (%p) Moving request to the send queue.",
1589 		    hio);
1590 		mtx_lock(&metadata_lock);
1591 		if (res->hr_syncsrc == HAST_SYNCSRC_PRIMARY) {
1592 			/*
1593 			 * This range is up-to-date on local component,
1594 			 * so handle request locally.
1595 			 */
1596 			 /* Local component is 0 for now. */
1597 			ncomp = 0;
1598 		} else /* if (res->hr_syncsrc == HAST_SYNCSRC_SECONDARY) */ {
1599 			assert(res->hr_syncsrc == HAST_SYNCSRC_SECONDARY);
1600 			/*
1601 			 * This range is out-of-date on local component,
1602 			 * so send request to the remote node.
1603 			 */
1604 			 /* Remote component is 1 for now. */
1605 			ncomp = 1;
1606 		}
1607 		mtx_unlock(&metadata_lock);
1608 		refcount_init(&hio->hio_countdown, 1);
1609 		QUEUE_INSERT1(hio, send, ncomp);
1610 
1611 		/*
1612 		 * Let's wait for READ to finish.
1613 		 */
1614 		mtx_lock(&sync_lock);
1615 		while (!ISSYNCREQDONE(hio))
1616 			cv_wait(&sync_cond, &sync_lock);
1617 		mtx_unlock(&sync_lock);
1618 
1619 		if (hio->hio_errors[ncomp] != 0) {
1620 			pjdlog_error("Unable to read synchronization data: %s.",
1621 			    strerror(hio->hio_errors[ncomp]));
1622 			goto free_queue;
1623 		}
1624 
1625 		/*
1626 		 * We read the data from synchronization source, now write it
1627 		 * to synchronization target.
1628 		 */
1629 		SYNCREQ(hio);
1630 		ggio->gctl_cmd = BIO_WRITE;
1631 		for (ii = 0; ii < ncomps; ii++)
1632 			hio->hio_errors[ii] = EINVAL;
1633 		reqlog(LOG_DEBUG, 2, ggio, "sync: (%p) Sending sync request: ",
1634 		    hio);
1635 		pjdlog_debug(2, "sync: (%p) Moving request to the send queue.",
1636 		    hio);
1637 		mtx_lock(&metadata_lock);
1638 		if (res->hr_syncsrc == HAST_SYNCSRC_PRIMARY) {
1639 			/*
1640 			 * This range is up-to-date on local component,
1641 			 * so we update remote component.
1642 			 */
1643 			 /* Remote component is 1 for now. */
1644 			ncomp = 1;
1645 		} else /* if (res->hr_syncsrc == HAST_SYNCSRC_SECONDARY) */ {
1646 			assert(res->hr_syncsrc == HAST_SYNCSRC_SECONDARY);
1647 			/*
1648 			 * This range is out-of-date on local component,
1649 			 * so we update it.
1650 			 */
1651 			 /* Local component is 0 for now. */
1652 			ncomp = 0;
1653 		}
1654 		mtx_unlock(&metadata_lock);
1655 
1656 		pjdlog_debug(2, "sync: (%p) Moving request to the send queues.",
1657 		    hio);
1658 		refcount_init(&hio->hio_countdown, 1);
1659 		QUEUE_INSERT1(hio, send, ncomp);
1660 
1661 		/*
1662 		 * Let's wait for WRITE to finish.
1663 		 */
1664 		mtx_lock(&sync_lock);
1665 		while (!ISSYNCREQDONE(hio))
1666 			cv_wait(&sync_cond, &sync_lock);
1667 		mtx_unlock(&sync_lock);
1668 
1669 		if (hio->hio_errors[ncomp] != 0) {
1670 			pjdlog_error("Unable to write synchronization data: %s.",
1671 			    strerror(hio->hio_errors[ncomp]));
1672 			goto free_queue;
1673 		}
1674 free_queue:
1675 		mtx_lock(&range_lock);
1676 		rangelock_del(range_sync, offset, length);
1677 		if (range_regular_wait)
1678 			cv_signal(&range_regular_cond);
1679 		mtx_unlock(&range_lock);
1680 
1681 		synced += length;
1682 
1683 		pjdlog_debug(2, "sync: (%p) Moving request to the free queue.",
1684 		    hio);
1685 		QUEUE_INSERT2(hio, free);
1686 	}
1687 	/* NOTREACHED */
1688 	return (NULL);
1689 }
1690 
1691 static void
1692 sighandler(int sig)
1693 {
1694 	bool unlock;
1695 
1696 	switch (sig) {
1697 	case SIGINT:
1698 	case SIGTERM:
1699 		sigexit_received = true;
1700 		break;
1701 	default:
1702 		assert(!"invalid condition");
1703 	}
1704 	/*
1705 	 * XXX: Racy, but if we cannot obtain hio_guard_lock here, we don't
1706 	 * want to risk deadlock.
1707 	 */
1708 	unlock = mtx_trylock(&hio_guard_lock);
1709 	cv_signal(&hio_guard_cond);
1710 	if (unlock)
1711 		mtx_unlock(&hio_guard_lock);
1712 }
1713 
1714 /*
1715  * Thread guards remote connections and reconnects when needed, handles
1716  * signals, etc.
1717  */
1718 static void *
1719 guard_thread(void *arg)
1720 {
1721 	struct hast_resource *res = arg;
1722 	struct proto_conn *in, *out;
1723 	unsigned int ii, ncomps;
1724 	int timeout;
1725 
1726 	ncomps = HAST_NCOMPONENTS;
1727 	/* The is only one remote component for now. */
1728 #define	ISREMOTE(no)	((no) == 1)
1729 
1730 	for (;;) {
1731 		if (sigexit_received) {
1732 			primary_exitx(EX_OK,
1733 			    "Termination signal received, exiting.");
1734 		}
1735 		/*
1736 		 * If all the connection will be fine, we will sleep until
1737 		 * someone wakes us up.
1738 		 * If any of the connections will be broken and we won't be
1739 		 * able to connect, we will sleep only for RECONNECT_SLEEP
1740 		 * seconds so we can retry soon.
1741 		 */
1742 		timeout = 0;
1743 		pjdlog_debug(2, "remote_guard: Checking connections.");
1744 		mtx_lock(&hio_guard_lock);
1745 		for (ii = 0; ii < ncomps; ii++) {
1746 			if (!ISREMOTE(ii))
1747 				continue;
1748 			rw_rlock(&hio_remote_lock[ii]);
1749 			if (ISCONNECTED(res, ii)) {
1750 				assert(res->hr_remotein != NULL);
1751 				assert(res->hr_remoteout != NULL);
1752 				rw_unlock(&hio_remote_lock[ii]);
1753 				pjdlog_debug(2,
1754 				    "remote_guard: Connection to %s is ok.",
1755 				    res->hr_remoteaddr);
1756 			} else {
1757 				assert(res->hr_remotein == NULL);
1758 				assert(res->hr_remoteout == NULL);
1759 				/*
1760 				 * Upgrade the lock. It doesn't have to be
1761 				 * atomic as no other thread can change
1762 				 * connection status from disconnected to
1763 				 * connected.
1764 				 */
1765 				rw_unlock(&hio_remote_lock[ii]);
1766 				pjdlog_debug(2,
1767 				    "remote_guard: Reconnecting to %s.",
1768 				    res->hr_remoteaddr);
1769 				in = out = NULL;
1770 				if (init_remote(res, &in, &out)) {
1771 					rw_wlock(&hio_remote_lock[ii]);
1772 					assert(res->hr_remotein == NULL);
1773 					assert(res->hr_remoteout == NULL);
1774 					assert(in != NULL && out != NULL);
1775 					res->hr_remotein = in;
1776 					res->hr_remoteout = out;
1777 					rw_unlock(&hio_remote_lock[ii]);
1778 					pjdlog_info("Successfully reconnected to %s.",
1779 					    res->hr_remoteaddr);
1780 					sync_start();
1781 				} else {
1782 					/* Both connections should be NULL. */
1783 					assert(res->hr_remotein == NULL);
1784 					assert(res->hr_remoteout == NULL);
1785 					assert(in == NULL && out == NULL);
1786 					pjdlog_debug(2,
1787 					    "remote_guard: Reconnect to %s failed.",
1788 					    res->hr_remoteaddr);
1789 					timeout = RECONNECT_SLEEP;
1790 				}
1791 			}
1792 		}
1793 		(void)cv_timedwait(&hio_guard_cond, &hio_guard_lock, timeout);
1794 		mtx_unlock(&hio_guard_lock);
1795 	}
1796 #undef	ISREMOTE
1797 	/* NOTREACHED */
1798 	return (NULL);
1799 }
1800