xref: /freebsd/sys/geom/journal/g_journal.c (revision 8657387683946d0c03e09fe77029edfe309eeb20)
1 /*-
2  * Copyright (c) 2005-2006 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <sys/param.h>
31 #include <sys/systm.h>
32 #include <sys/kernel.h>
33 #include <sys/module.h>
34 #include <sys/limits.h>
35 #include <sys/lock.h>
36 #include <sys/mutex.h>
37 #include <sys/bio.h>
38 #include <sys/sysctl.h>
39 #include <sys/malloc.h>
40 #include <sys/mount.h>
41 #include <sys/eventhandler.h>
42 #include <sys/proc.h>
43 #include <sys/kthread.h>
44 #include <sys/sched.h>
45 #include <sys/taskqueue.h>
46 #include <sys/vnode.h>
47 #include <sys/sbuf.h>
48 #ifdef GJ_MEMDEBUG
49 #include <sys/stack.h>
50 #include <sys/kdb.h>
51 #endif
52 #include <vm/vm.h>
53 #include <vm/vm_kern.h>
54 #include <geom/geom.h>
55 
56 #include <geom/journal/g_journal.h>
57 
58 FEATURE(geom_journal, "GEOM journaling support");
59 
60 /*
61  * On-disk journal format:
62  *
63  * JH - Journal header
64  * RH - Record header
65  *
66  * %%%%%% ****** +------+ +------+     ****** +------+     %%%%%%
67  * % JH % * RH * | Data | | Data | ... * RH * | Data | ... % JH % ...
68  * %%%%%% ****** +------+ +------+     ****** +------+     %%%%%%
69  *
70  */
71 
72 CTASSERT(sizeof(struct g_journal_header) <= 512);
73 CTASSERT(sizeof(struct g_journal_record_header) <= 512);
74 
75 static MALLOC_DEFINE(M_JOURNAL, "journal_data", "GEOM_JOURNAL Data");
76 static struct mtx g_journal_cache_mtx;
77 MTX_SYSINIT(g_journal_cache, &g_journal_cache_mtx, "cache usage", MTX_DEF);
78 
79 const struct g_journal_desc *g_journal_filesystems[] = {
80 	&g_journal_ufs,
81 	NULL
82 };
83 
84 SYSCTL_DECL(_kern_geom);
85 
86 int g_journal_debug = 0;
87 static u_int g_journal_switch_time = 10;
88 static u_int g_journal_force_switch = 70;
89 static u_int g_journal_parallel_flushes = 16;
90 static u_int g_journal_parallel_copies = 16;
91 static u_int g_journal_accept_immediately = 64;
92 static u_int g_journal_record_entries = GJ_RECORD_HEADER_NENTRIES;
93 static u_int g_journal_do_optimize = 1;
94 
95 static SYSCTL_NODE(_kern_geom, OID_AUTO, journal, CTLFLAG_RW, 0,
96     "GEOM_JOURNAL stuff");
97 SYSCTL_INT(_kern_geom_journal, OID_AUTO, debug, CTLFLAG_RWTUN, &g_journal_debug, 0,
98     "Debug level");
99 SYSCTL_UINT(_kern_geom_journal, OID_AUTO, switch_time, CTLFLAG_RW,
100     &g_journal_switch_time, 0, "Switch journals every N seconds");
101 SYSCTL_UINT(_kern_geom_journal, OID_AUTO, force_switch, CTLFLAG_RW,
102     &g_journal_force_switch, 0, "Force switch when journal is N% full");
103 SYSCTL_UINT(_kern_geom_journal, OID_AUTO, parallel_flushes, CTLFLAG_RW,
104     &g_journal_parallel_flushes, 0,
105     "Number of flush I/O requests to send in parallel");
106 SYSCTL_UINT(_kern_geom_journal, OID_AUTO, accept_immediately, CTLFLAG_RW,
107     &g_journal_accept_immediately, 0,
108     "Number of I/O requests accepted immediately");
109 SYSCTL_UINT(_kern_geom_journal, OID_AUTO, parallel_copies, CTLFLAG_RW,
110     &g_journal_parallel_copies, 0,
111     "Number of copy I/O requests to send in parallel");
112 static int
113 g_journal_record_entries_sysctl(SYSCTL_HANDLER_ARGS)
114 {
115 	u_int entries;
116 	int error;
117 
118 	entries = g_journal_record_entries;
119 	error = sysctl_handle_int(oidp, &entries, 0, req);
120 	if (error != 0 || req->newptr == NULL)
121 		return (error);
122 	if (entries < 1 || entries > GJ_RECORD_HEADER_NENTRIES)
123 		return (EINVAL);
124 	g_journal_record_entries = entries;
125 	return (0);
126 }
127 SYSCTL_PROC(_kern_geom_journal, OID_AUTO, record_entries,
128     CTLTYPE_UINT | CTLFLAG_RW, NULL, 0, g_journal_record_entries_sysctl, "I",
129     "Maximum number of entires in one journal record");
130 SYSCTL_UINT(_kern_geom_journal, OID_AUTO, optimize, CTLFLAG_RW,
131     &g_journal_do_optimize, 0, "Try to combine bios on flush and copy");
132 
133 static u_long g_journal_cache_used = 0;
134 static u_long g_journal_cache_limit = 64 * 1024 * 1024;
135 static u_int g_journal_cache_divisor = 2;
136 static u_int g_journal_cache_switch = 90;
137 static u_int g_journal_cache_misses = 0;
138 static u_int g_journal_cache_alloc_failures = 0;
139 static u_long g_journal_cache_low = 0;
140 
141 static SYSCTL_NODE(_kern_geom_journal, OID_AUTO, cache, CTLFLAG_RW, 0,
142     "GEOM_JOURNAL cache");
143 SYSCTL_ULONG(_kern_geom_journal_cache, OID_AUTO, used, CTLFLAG_RD,
144     &g_journal_cache_used, 0, "Number of allocated bytes");
145 static int
146 g_journal_cache_limit_sysctl(SYSCTL_HANDLER_ARGS)
147 {
148 	u_long limit;
149 	int error;
150 
151 	limit = g_journal_cache_limit;
152 	error = sysctl_handle_long(oidp, &limit, 0, req);
153 	if (error != 0 || req->newptr == NULL)
154 		return (error);
155 	g_journal_cache_limit = limit;
156 	g_journal_cache_low = (limit / 100) * g_journal_cache_switch;
157 	return (0);
158 }
159 SYSCTL_PROC(_kern_geom_journal_cache, OID_AUTO, limit,
160     CTLTYPE_ULONG | CTLFLAG_RWTUN, NULL, 0, g_journal_cache_limit_sysctl, "I",
161     "Maximum number of allocated bytes");
162 SYSCTL_UINT(_kern_geom_journal_cache, OID_AUTO, divisor, CTLFLAG_RDTUN,
163     &g_journal_cache_divisor, 0,
164     "(kmem_size / kern.geom.journal.cache.divisor) == cache size");
165 static int
166 g_journal_cache_switch_sysctl(SYSCTL_HANDLER_ARGS)
167 {
168 	u_int cswitch;
169 	int error;
170 
171 	cswitch = g_journal_cache_switch;
172 	error = sysctl_handle_int(oidp, &cswitch, 0, req);
173 	if (error != 0 || req->newptr == NULL)
174 		return (error);
175 	if (cswitch > 100)
176 		return (EINVAL);
177 	g_journal_cache_switch = cswitch;
178 	g_journal_cache_low = (g_journal_cache_limit / 100) * cswitch;
179 	return (0);
180 }
181 SYSCTL_PROC(_kern_geom_journal_cache, OID_AUTO, switch,
182     CTLTYPE_UINT | CTLFLAG_RW, NULL, 0, g_journal_cache_switch_sysctl, "I",
183     "Force switch when we hit this percent of cache use");
184 SYSCTL_UINT(_kern_geom_journal_cache, OID_AUTO, misses, CTLFLAG_RW,
185     &g_journal_cache_misses, 0, "Number of cache misses");
186 SYSCTL_UINT(_kern_geom_journal_cache, OID_AUTO, alloc_failures, CTLFLAG_RW,
187     &g_journal_cache_alloc_failures, 0, "Memory allocation failures");
188 
189 static u_long g_journal_stats_bytes_skipped = 0;
190 static u_long g_journal_stats_combined_ios = 0;
191 static u_long g_journal_stats_switches = 0;
192 static u_long g_journal_stats_wait_for_copy = 0;
193 static u_long g_journal_stats_journal_full = 0;
194 static u_long g_journal_stats_low_mem = 0;
195 
196 static SYSCTL_NODE(_kern_geom_journal, OID_AUTO, stats, CTLFLAG_RW, 0,
197     "GEOM_JOURNAL statistics");
198 SYSCTL_ULONG(_kern_geom_journal_stats, OID_AUTO, skipped_bytes, CTLFLAG_RW,
199     &g_journal_stats_bytes_skipped, 0, "Number of skipped bytes");
200 SYSCTL_ULONG(_kern_geom_journal_stats, OID_AUTO, combined_ios, CTLFLAG_RW,
201     &g_journal_stats_combined_ios, 0, "Number of combined I/O requests");
202 SYSCTL_ULONG(_kern_geom_journal_stats, OID_AUTO, switches, CTLFLAG_RW,
203     &g_journal_stats_switches, 0, "Number of journal switches");
204 SYSCTL_ULONG(_kern_geom_journal_stats, OID_AUTO, wait_for_copy, CTLFLAG_RW,
205     &g_journal_stats_wait_for_copy, 0, "Wait for journal copy on switch");
206 SYSCTL_ULONG(_kern_geom_journal_stats, OID_AUTO, journal_full, CTLFLAG_RW,
207     &g_journal_stats_journal_full, 0,
208     "Number of times journal was almost full.");
209 SYSCTL_ULONG(_kern_geom_journal_stats, OID_AUTO, low_mem, CTLFLAG_RW,
210     &g_journal_stats_low_mem, 0, "Number of times low_mem hook was called.");
211 
212 static g_taste_t g_journal_taste;
213 static g_ctl_req_t g_journal_config;
214 static g_dumpconf_t g_journal_dumpconf;
215 static g_init_t g_journal_init;
216 static g_fini_t g_journal_fini;
217 
218 struct g_class g_journal_class = {
219 	.name = G_JOURNAL_CLASS_NAME,
220 	.version = G_VERSION,
221 	.taste = g_journal_taste,
222 	.ctlreq = g_journal_config,
223 	.dumpconf = g_journal_dumpconf,
224 	.init = g_journal_init,
225 	.fini = g_journal_fini
226 };
227 
228 static int g_journal_destroy(struct g_journal_softc *sc);
229 static void g_journal_metadata_update(struct g_journal_softc *sc);
230 static void g_journal_start_switcher(struct g_class *mp);
231 static void g_journal_stop_switcher(void);
232 static void g_journal_switch_wait(struct g_journal_softc *sc);
233 
234 #define	GJ_SWITCHER_WORKING	0
235 #define	GJ_SWITCHER_DIE		1
236 #define	GJ_SWITCHER_DIED	2
237 static struct proc *g_journal_switcher_proc = NULL;
238 static int g_journal_switcher_state = GJ_SWITCHER_WORKING;
239 static int g_journal_switcher_wokenup = 0;
240 static int g_journal_sync_requested = 0;
241 
242 #ifdef GJ_MEMDEBUG
243 struct meminfo {
244 	size_t		mi_size;
245 	struct stack	mi_stack;
246 };
247 #endif
248 
249 /*
250  * We use our own malloc/realloc/free funtions, so we can collect statistics
251  * and force journal switch when we're running out of cache.
252  */
253 static void *
254 gj_malloc(size_t size, int flags)
255 {
256 	void *p;
257 #ifdef GJ_MEMDEBUG
258 	struct meminfo *mi;
259 #endif
260 
261 	mtx_lock(&g_journal_cache_mtx);
262 	if (g_journal_cache_limit > 0 && !g_journal_switcher_wokenup &&
263 	    g_journal_cache_used + size > g_journal_cache_low) {
264 		GJ_DEBUG(1, "No cache, waking up the switcher.");
265 		g_journal_switcher_wokenup = 1;
266 		wakeup(&g_journal_switcher_state);
267 	}
268 	if ((flags & M_NOWAIT) && g_journal_cache_limit > 0 &&
269 	    g_journal_cache_used + size > g_journal_cache_limit) {
270 		mtx_unlock(&g_journal_cache_mtx);
271 		g_journal_cache_alloc_failures++;
272 		return (NULL);
273 	}
274 	g_journal_cache_used += size;
275 	mtx_unlock(&g_journal_cache_mtx);
276 	flags &= ~M_NOWAIT;
277 #ifndef GJ_MEMDEBUG
278 	p = malloc(size, M_JOURNAL, flags | M_WAITOK);
279 #else
280 	mi = malloc(sizeof(*mi) + size, M_JOURNAL, flags | M_WAITOK);
281 	p = (u_char *)mi + sizeof(*mi);
282 	mi->mi_size = size;
283 	stack_save(&mi->mi_stack);
284 #endif
285 	return (p);
286 }
287 
288 static void
289 gj_free(void *p, size_t size)
290 {
291 #ifdef GJ_MEMDEBUG
292 	struct meminfo *mi;
293 #endif
294 
295 	KASSERT(p != NULL, ("p=NULL"));
296 	KASSERT(size > 0, ("size=0"));
297 	mtx_lock(&g_journal_cache_mtx);
298 	KASSERT(g_journal_cache_used >= size, ("Freeing too much?"));
299 	g_journal_cache_used -= size;
300 	mtx_unlock(&g_journal_cache_mtx);
301 #ifdef GJ_MEMDEBUG
302 	mi = p = (void *)((u_char *)p - sizeof(*mi));
303 	if (mi->mi_size != size) {
304 		printf("GJOURNAL: Size mismatch! %zu != %zu\n", size,
305 		    mi->mi_size);
306 		printf("GJOURNAL: Alloc backtrace:\n");
307 		stack_print(&mi->mi_stack);
308 		printf("GJOURNAL: Free backtrace:\n");
309 		kdb_backtrace();
310 	}
311 #endif
312 	free(p, M_JOURNAL);
313 }
314 
315 static void *
316 gj_realloc(void *p, size_t size, size_t oldsize)
317 {
318 	void *np;
319 
320 #ifndef GJ_MEMDEBUG
321 	mtx_lock(&g_journal_cache_mtx);
322 	g_journal_cache_used -= oldsize;
323 	g_journal_cache_used += size;
324 	mtx_unlock(&g_journal_cache_mtx);
325 	np = realloc(p, size, M_JOURNAL, M_WAITOK);
326 #else
327 	np = gj_malloc(size, M_WAITOK);
328 	bcopy(p, np, MIN(oldsize, size));
329 	gj_free(p, oldsize);
330 #endif
331 	return (np);
332 }
333 
334 static void
335 g_journal_check_overflow(struct g_journal_softc *sc)
336 {
337 	off_t length, used;
338 
339 	if ((sc->sc_active.jj_offset < sc->sc_inactive.jj_offset &&
340 	     sc->sc_journal_offset >= sc->sc_inactive.jj_offset) ||
341 	    (sc->sc_active.jj_offset > sc->sc_inactive.jj_offset &&
342 	     sc->sc_journal_offset >= sc->sc_inactive.jj_offset &&
343 	     sc->sc_journal_offset < sc->sc_active.jj_offset)) {
344 		panic("Journal overflow "
345 		    "(id = %u joffset=%jd active=%jd inactive=%jd)",
346 		    (unsigned)sc->sc_id,
347 		    (intmax_t)sc->sc_journal_offset,
348 		    (intmax_t)sc->sc_active.jj_offset,
349 		    (intmax_t)sc->sc_inactive.jj_offset);
350 	}
351 	if (sc->sc_active.jj_offset < sc->sc_inactive.jj_offset) {
352 		length = sc->sc_inactive.jj_offset - sc->sc_active.jj_offset;
353 		used = sc->sc_journal_offset - sc->sc_active.jj_offset;
354 	} else {
355 		length = sc->sc_jend - sc->sc_active.jj_offset;
356 		length += sc->sc_inactive.jj_offset - sc->sc_jstart;
357 		if (sc->sc_journal_offset >= sc->sc_active.jj_offset)
358 			used = sc->sc_journal_offset - sc->sc_active.jj_offset;
359 		else {
360 			used = sc->sc_jend - sc->sc_active.jj_offset;
361 			used += sc->sc_journal_offset - sc->sc_jstart;
362 		}
363 	}
364 	/* Already woken up? */
365 	if (g_journal_switcher_wokenup)
366 		return;
367 	/*
368 	 * If the active journal takes more than g_journal_force_switch precent
369 	 * of free journal space, we force journal switch.
370 	 */
371 	KASSERT(length > 0,
372 	    ("length=%jd used=%jd active=%jd inactive=%jd joffset=%jd",
373 	    (intmax_t)length, (intmax_t)used,
374 	    (intmax_t)sc->sc_active.jj_offset,
375 	    (intmax_t)sc->sc_inactive.jj_offset,
376 	    (intmax_t)sc->sc_journal_offset));
377 	if ((used * 100) / length > g_journal_force_switch) {
378 		g_journal_stats_journal_full++;
379 		GJ_DEBUG(1, "Journal %s %jd%% full, forcing journal switch.",
380 		    sc->sc_name, (used * 100) / length);
381 		mtx_lock(&g_journal_cache_mtx);
382 		g_journal_switcher_wokenup = 1;
383 		wakeup(&g_journal_switcher_state);
384 		mtx_unlock(&g_journal_cache_mtx);
385 	}
386 }
387 
388 static void
389 g_journal_orphan(struct g_consumer *cp)
390 {
391 	struct g_journal_softc *sc;
392 	char name[256];
393 	int error;
394 
395 	g_topology_assert();
396 	sc = cp->geom->softc;
397 	strlcpy(name, cp->provider->name, sizeof(name));
398 	GJ_DEBUG(0, "Lost provider %s.", name);
399 	if (sc == NULL)
400 		return;
401 	error = g_journal_destroy(sc);
402 	if (error == 0)
403 		GJ_DEBUG(0, "Journal %s destroyed.", name);
404 	else {
405 		GJ_DEBUG(0, "Cannot destroy journal %s (error=%d). "
406 		    "Destroy it manually after last close.", sc->sc_name,
407 		    error);
408 	}
409 }
410 
411 static int
412 g_journal_access(struct g_provider *pp, int acr, int acw, int ace)
413 {
414 	struct g_journal_softc *sc;
415 	int dcr, dcw, dce;
416 
417 	g_topology_assert();
418 	GJ_DEBUG(2, "Access request for %s: r%dw%de%d.", pp->name,
419 	    acr, acw, ace);
420 
421 	dcr = pp->acr + acr;
422 	dcw = pp->acw + acw;
423 	dce = pp->ace + ace;
424 
425 	sc = pp->geom->softc;
426 	if (sc == NULL || (sc->sc_flags & GJF_DEVICE_DESTROY)) {
427 		if (acr <= 0 && acw <= 0 && ace <= 0)
428 			return (0);
429 		else
430 			return (ENXIO);
431 	}
432 	if (pp->acw == 0 && dcw > 0) {
433 		GJ_DEBUG(1, "Marking %s as dirty.", sc->sc_name);
434 		sc->sc_flags &= ~GJF_DEVICE_CLEAN;
435 		g_topology_unlock();
436 		g_journal_metadata_update(sc);
437 		g_topology_lock();
438 	} /* else if (pp->acw == 0 && dcw > 0 && JEMPTY(sc)) {
439 		GJ_DEBUG(1, "Marking %s as clean.", sc->sc_name);
440 		sc->sc_flags |= GJF_DEVICE_CLEAN;
441 		g_topology_unlock();
442 		g_journal_metadata_update(sc);
443 		g_topology_lock();
444 	} */
445 	return (0);
446 }
447 
448 static void
449 g_journal_header_encode(struct g_journal_header *hdr, u_char *data)
450 {
451 
452 	bcopy(GJ_HEADER_MAGIC, data, sizeof(GJ_HEADER_MAGIC));
453 	data += sizeof(GJ_HEADER_MAGIC);
454 	le32enc(data, hdr->jh_journal_id);
455 	data += 4;
456 	le32enc(data, hdr->jh_journal_next_id);
457 }
458 
459 static int
460 g_journal_header_decode(const u_char *data, struct g_journal_header *hdr)
461 {
462 
463 	bcopy(data, hdr->jh_magic, sizeof(hdr->jh_magic));
464 	data += sizeof(hdr->jh_magic);
465 	if (bcmp(hdr->jh_magic, GJ_HEADER_MAGIC, sizeof(GJ_HEADER_MAGIC)) != 0)
466 		return (EINVAL);
467 	hdr->jh_journal_id = le32dec(data);
468 	data += 4;
469 	hdr->jh_journal_next_id = le32dec(data);
470 	return (0);
471 }
472 
473 static void
474 g_journal_flush_cache(struct g_journal_softc *sc)
475 {
476 	struct bintime bt;
477 	int error;
478 
479 	if (sc->sc_bio_flush == 0)
480 		return;
481 	GJ_TIMER_START(1, &bt);
482 	if (sc->sc_bio_flush & GJ_FLUSH_JOURNAL) {
483 		error = g_io_flush(sc->sc_jconsumer);
484 		GJ_DEBUG(error == 0 ? 2 : 0, "Flush cache of %s: error=%d.",
485 		    sc->sc_jconsumer->provider->name, error);
486 	}
487 	if (sc->sc_bio_flush & GJ_FLUSH_DATA) {
488 		/*
489 		 * TODO: This could be called in parallel with the
490 		 *       previous call.
491 		 */
492 		error = g_io_flush(sc->sc_dconsumer);
493 		GJ_DEBUG(error == 0 ? 2 : 0, "Flush cache of %s: error=%d.",
494 		    sc->sc_dconsumer->provider->name, error);
495 	}
496 	GJ_TIMER_STOP(1, &bt, "Cache flush time");
497 }
498 
499 static int
500 g_journal_write_header(struct g_journal_softc *sc)
501 {
502 	struct g_journal_header hdr;
503 	struct g_consumer *cp;
504 	u_char *buf;
505 	int error;
506 
507 	cp = sc->sc_jconsumer;
508 	buf = gj_malloc(cp->provider->sectorsize, M_WAITOK);
509 
510 	strlcpy(hdr.jh_magic, GJ_HEADER_MAGIC, sizeof(hdr.jh_magic));
511 	hdr.jh_journal_id = sc->sc_journal_id;
512 	hdr.jh_journal_next_id = sc->sc_journal_next_id;
513 	g_journal_header_encode(&hdr, buf);
514 	error = g_write_data(cp, sc->sc_journal_offset, buf,
515 	    cp->provider->sectorsize);
516 	/* if (error == 0) */
517 	sc->sc_journal_offset += cp->provider->sectorsize;
518 
519 	gj_free(buf, cp->provider->sectorsize);
520 	return (error);
521 }
522 
523 /*
524  * Every journal record has a header and data following it.
525  * Functions below are used to decode the header before storing it to
526  * little endian and to encode it after reading to system endianness.
527  */
528 static void
529 g_journal_record_header_encode(struct g_journal_record_header *hdr,
530     u_char *data)
531 {
532 	struct g_journal_entry *ent;
533 	u_int i;
534 
535 	bcopy(GJ_RECORD_HEADER_MAGIC, data, sizeof(GJ_RECORD_HEADER_MAGIC));
536 	data += sizeof(GJ_RECORD_HEADER_MAGIC);
537 	le32enc(data, hdr->jrh_journal_id);
538 	data += 8;
539 	le16enc(data, hdr->jrh_nentries);
540 	data += 2;
541 	bcopy(hdr->jrh_sum, data, sizeof(hdr->jrh_sum));
542 	data += 8;
543 	for (i = 0; i < hdr->jrh_nentries; i++) {
544 		ent = &hdr->jrh_entries[i];
545 		le64enc(data, ent->je_joffset);
546 		data += 8;
547 		le64enc(data, ent->je_offset);
548 		data += 8;
549 		le64enc(data, ent->je_length);
550 		data += 8;
551 	}
552 }
553 
554 static int
555 g_journal_record_header_decode(const u_char *data,
556     struct g_journal_record_header *hdr)
557 {
558 	struct g_journal_entry *ent;
559 	u_int i;
560 
561 	bcopy(data, hdr->jrh_magic, sizeof(hdr->jrh_magic));
562 	data += sizeof(hdr->jrh_magic);
563 	if (strcmp(hdr->jrh_magic, GJ_RECORD_HEADER_MAGIC) != 0)
564 		return (EINVAL);
565 	hdr->jrh_journal_id = le32dec(data);
566 	data += 8;
567 	hdr->jrh_nentries = le16dec(data);
568 	data += 2;
569 	if (hdr->jrh_nentries > GJ_RECORD_HEADER_NENTRIES)
570 		return (EINVAL);
571 	bcopy(data, hdr->jrh_sum, sizeof(hdr->jrh_sum));
572 	data += 8;
573 	for (i = 0; i < hdr->jrh_nentries; i++) {
574 		ent = &hdr->jrh_entries[i];
575 		ent->je_joffset = le64dec(data);
576 		data += 8;
577 		ent->je_offset = le64dec(data);
578 		data += 8;
579 		ent->je_length = le64dec(data);
580 		data += 8;
581 	}
582 	return (0);
583 }
584 
585 /*
586  * Function reads metadata from a provider (via the given consumer), decodes
587  * it to system endianness and verifies its correctness.
588  */
589 static int
590 g_journal_metadata_read(struct g_consumer *cp, struct g_journal_metadata *md)
591 {
592 	struct g_provider *pp;
593 	u_char *buf;
594 	int error;
595 
596 	g_topology_assert();
597 
598 	error = g_access(cp, 1, 0, 0);
599 	if (error != 0)
600 		return (error);
601 	pp = cp->provider;
602 	g_topology_unlock();
603 	/* Metadata is stored in last sector. */
604 	buf = g_read_data(cp, pp->mediasize - pp->sectorsize, pp->sectorsize,
605 	    &error);
606 	g_topology_lock();
607 	g_access(cp, -1, 0, 0);
608 	if (buf == NULL) {
609 		GJ_DEBUG(1, "Cannot read metadata from %s (error=%d).",
610 		    cp->provider->name, error);
611 		return (error);
612 	}
613 
614 	/* Decode metadata. */
615 	error = journal_metadata_decode(buf, md);
616 	g_free(buf);
617 	/* Is this is gjournal provider at all? */
618 	if (strcmp(md->md_magic, G_JOURNAL_MAGIC) != 0)
619 		return (EINVAL);
620 	/*
621 	 * Are we able to handle this version of metadata?
622 	 * We only maintain backward compatibility.
623 	 */
624 	if (md->md_version > G_JOURNAL_VERSION) {
625 		GJ_DEBUG(0,
626 		    "Kernel module is too old to handle metadata from %s.",
627 		    cp->provider->name);
628 		return (EINVAL);
629 	}
630 	/* Is checksum correct? */
631 	if (error != 0) {
632 		GJ_DEBUG(0, "MD5 metadata hash mismatch for provider %s.",
633 		    cp->provider->name);
634 		return (error);
635 	}
636 	return (0);
637 }
638 
639 /*
640  * Two functions below are responsible for updating metadata.
641  * Only metadata on the data provider is updated (we need to update
642  * information about active journal in there).
643  */
644 static void
645 g_journal_metadata_done(struct bio *bp)
646 {
647 
648 	/*
649 	 * There is not much we can do on error except informing about it.
650 	 */
651 	if (bp->bio_error != 0) {
652 		GJ_LOGREQ(0, bp, "Cannot update metadata (error=%d).",
653 		    bp->bio_error);
654 	} else {
655 		GJ_LOGREQ(2, bp, "Metadata updated.");
656 	}
657 	gj_free(bp->bio_data, bp->bio_length);
658 	g_destroy_bio(bp);
659 }
660 
661 static void
662 g_journal_metadata_update(struct g_journal_softc *sc)
663 {
664 	struct g_journal_metadata md;
665 	struct g_consumer *cp;
666 	struct bio *bp;
667 	u_char *sector;
668 
669 	cp = sc->sc_dconsumer;
670 	sector = gj_malloc(cp->provider->sectorsize, M_WAITOK);
671 	strlcpy(md.md_magic, G_JOURNAL_MAGIC, sizeof(md.md_magic));
672 	md.md_version = G_JOURNAL_VERSION;
673 	md.md_id = sc->sc_id;
674 	md.md_type = sc->sc_orig_type;
675 	md.md_jstart = sc->sc_jstart;
676 	md.md_jend = sc->sc_jend;
677 	md.md_joffset = sc->sc_inactive.jj_offset;
678 	md.md_jid = sc->sc_journal_previous_id;
679 	md.md_flags = 0;
680 	if (sc->sc_flags & GJF_DEVICE_CLEAN)
681 		md.md_flags |= GJ_FLAG_CLEAN;
682 
683 	if (sc->sc_flags & GJF_DEVICE_HARDCODED)
684 		strlcpy(md.md_provider, sc->sc_name, sizeof(md.md_provider));
685 	else
686 		bzero(md.md_provider, sizeof(md.md_provider));
687 	md.md_provsize = cp->provider->mediasize;
688 	journal_metadata_encode(&md, sector);
689 
690 	/*
691 	 * Flush the cache, so we know all data are on disk.
692 	 * We write here informations like "journal is consistent", so we need
693 	 * to be sure it is. Without BIO_FLUSH here, we can end up in situation
694 	 * where metadata is stored on disk, but not all data.
695 	 */
696 	g_journal_flush_cache(sc);
697 
698 	bp = g_alloc_bio();
699 	bp->bio_offset = cp->provider->mediasize - cp->provider->sectorsize;
700 	bp->bio_length = cp->provider->sectorsize;
701 	bp->bio_data = sector;
702 	bp->bio_cmd = BIO_WRITE;
703 	if (!(sc->sc_flags & GJF_DEVICE_DESTROY)) {
704 		bp->bio_done = g_journal_metadata_done;
705 		g_io_request(bp, cp);
706 	} else {
707 		bp->bio_done = NULL;
708 		g_io_request(bp, cp);
709 		biowait(bp, "gjmdu");
710 		g_journal_metadata_done(bp);
711 	}
712 
713 	/*
714 	 * Be sure metadata reached the disk.
715 	 */
716 	g_journal_flush_cache(sc);
717 }
718 
719 /*
720  * This is where the I/O request comes from the GEOM.
721  */
722 static void
723 g_journal_start(struct bio *bp)
724 {
725 	struct g_journal_softc *sc;
726 
727 	sc = bp->bio_to->geom->softc;
728 	GJ_LOGREQ(3, bp, "Request received.");
729 
730 	switch (bp->bio_cmd) {
731 	case BIO_READ:
732 	case BIO_WRITE:
733 		mtx_lock(&sc->sc_mtx);
734 		bioq_insert_tail(&sc->sc_regular_queue, bp);
735 		wakeup(sc);
736 		mtx_unlock(&sc->sc_mtx);
737 		return;
738 	case BIO_GETATTR:
739 		if (strcmp(bp->bio_attribute, "GJOURNAL::provider") == 0) {
740 			strlcpy(bp->bio_data, bp->bio_to->name, bp->bio_length);
741 			bp->bio_completed = strlen(bp->bio_to->name) + 1;
742 			g_io_deliver(bp, 0);
743 			return;
744 		}
745 		/* FALLTHROUGH */
746 	case BIO_DELETE:
747 	default:
748 		g_io_deliver(bp, EOPNOTSUPP);
749 		return;
750 	}
751 }
752 
753 static void
754 g_journal_std_done(struct bio *bp)
755 {
756 	struct g_journal_softc *sc;
757 
758 	sc = bp->bio_from->geom->softc;
759 	mtx_lock(&sc->sc_mtx);
760 	bioq_insert_tail(&sc->sc_back_queue, bp);
761 	wakeup(sc);
762 	mtx_unlock(&sc->sc_mtx);
763 }
764 
765 static struct bio *
766 g_journal_new_bio(off_t start, off_t end, off_t joffset, u_char *data,
767     int flags)
768 {
769 	struct bio *bp;
770 
771 	bp = g_alloc_bio();
772 	bp->bio_offset = start;
773 	bp->bio_joffset = joffset;
774 	bp->bio_length = end - start;
775 	bp->bio_cmd = BIO_WRITE;
776 	bp->bio_done = g_journal_std_done;
777 	if (data == NULL)
778 		bp->bio_data = NULL;
779 	else {
780 		bp->bio_data = gj_malloc(bp->bio_length, flags);
781 		if (bp->bio_data != NULL)
782 			bcopy(data, bp->bio_data, bp->bio_length);
783 	}
784 	return (bp);
785 }
786 
787 #define	g_journal_insert_bio(head, bp, flags)				\
788 	g_journal_insert((head), (bp)->bio_offset,			\
789 		(bp)->bio_offset + (bp)->bio_length, (bp)->bio_joffset,	\
790 		(bp)->bio_data, flags)
791 /*
792  * The function below does a lot more than just inserting bio to the queue.
793  * It keeps the queue sorted by offset and ensures that there are no doubled
794  * data (it combines bios where ranges overlap).
795  *
796  * The function returns the number of bios inserted (as bio can be splitted).
797  */
798 static int
799 g_journal_insert(struct bio **head, off_t nstart, off_t nend, off_t joffset,
800     u_char *data, int flags)
801 {
802 	struct bio *nbp, *cbp, *pbp;
803 	off_t cstart, cend;
804 	u_char *tmpdata;
805 	int n;
806 
807 	GJ_DEBUG(3, "INSERT(%p): (%jd, %jd, %jd)", *head, nstart, nend,
808 	    joffset);
809 	n = 0;
810 	pbp = NULL;
811 	GJQ_FOREACH(*head, cbp) {
812 		cstart = cbp->bio_offset;
813 		cend = cbp->bio_offset + cbp->bio_length;
814 
815 		if (nstart >= cend) {
816 			/*
817 			 *  +-------------+
818 			 *  |             |
819 			 *  |   current   |  +-------------+
820 			 *  |     bio     |  |             |
821 			 *  |             |  |     new     |
822 			 *  +-------------+  |     bio     |
823 			 *                   |             |
824 			 *                   +-------------+
825 			 */
826 			GJ_DEBUG(3, "INSERT(%p): 1", *head);
827 		} else if (nend <= cstart) {
828 			/*
829 			 *                   +-------------+
830 			 *                   |             |
831 			 *  +-------------+  |   current   |
832 			 *  |             |  |     bio     |
833 			 *  |     new     |  |             |
834 			 *  |     bio     |  +-------------+
835 			 *  |             |
836 			 *  +-------------+
837 			 */
838 			nbp = g_journal_new_bio(nstart, nend, joffset, data,
839 			    flags);
840 			if (pbp == NULL)
841 				*head = nbp;
842 			else
843 				pbp->bio_next = nbp;
844 			nbp->bio_next = cbp;
845 			n++;
846 			GJ_DEBUG(3, "INSERT(%p): 2 (nbp=%p pbp=%p)", *head, nbp,
847 			    pbp);
848 			goto end;
849 		} else if (nstart <= cstart && nend >= cend) {
850 			/*
851 			 *      +-------------+      +-------------+
852 			 *      | current bio |      | current bio |
853 			 *  +---+-------------+---+  +-------------+---+
854 			 *  |   |             |   |  |             |   |
855 			 *  |   |             |   |  |             |   |
856 			 *  |   +-------------+   |  +-------------+   |
857 			 *  |       new bio       |  |     new bio     |
858 			 *  +---------------------+  +-----------------+
859 			 *
860 			 *      +-------------+  +-------------+
861 			 *      | current bio |  | current bio |
862 			 *  +---+-------------+  +-------------+
863 			 *  |   |             |  |             |
864 			 *  |   |             |  |             |
865 			 *  |   +-------------+  +-------------+
866 			 *  |     new bio     |  |   new bio   |
867 			 *  +-----------------+  +-------------+
868 			 */
869 			g_journal_stats_bytes_skipped += cbp->bio_length;
870 			cbp->bio_offset = nstart;
871 			cbp->bio_joffset = joffset;
872 			cbp->bio_length = cend - nstart;
873 			if (cbp->bio_data != NULL) {
874 				gj_free(cbp->bio_data, cend - cstart);
875 				cbp->bio_data = NULL;
876 			}
877 			if (data != NULL) {
878 				cbp->bio_data = gj_malloc(cbp->bio_length,
879 				    flags);
880 				if (cbp->bio_data != NULL) {
881 					bcopy(data, cbp->bio_data,
882 					    cbp->bio_length);
883 				}
884 				data += cend - nstart;
885 			}
886 			joffset += cend - nstart;
887 			nstart = cend;
888 			GJ_DEBUG(3, "INSERT(%p): 3 (cbp=%p)", *head, cbp);
889 		} else if (nstart > cstart && nend >= cend) {
890 			/*
891 			 *  +-----------------+  +-------------+
892 			 *  |   current bio   |  | current bio |
893 			 *  |   +-------------+  |   +---------+---+
894 			 *  |   |             |  |   |         |   |
895 			 *  |   |             |  |   |         |   |
896 			 *  +---+-------------+  +---+---------+   |
897 			 *      |   new bio   |      |   new bio   |
898 			 *      +-------------+      +-------------+
899 			 */
900 			g_journal_stats_bytes_skipped += cend - nstart;
901 			nbp = g_journal_new_bio(nstart, cend, joffset, data,
902 			    flags);
903 			nbp->bio_next = cbp->bio_next;
904 			cbp->bio_next = nbp;
905 			cbp->bio_length = nstart - cstart;
906 			if (cbp->bio_data != NULL) {
907 				cbp->bio_data = gj_realloc(cbp->bio_data,
908 				    cbp->bio_length, cend - cstart);
909 			}
910 			if (data != NULL)
911 				data += cend - nstart;
912 			joffset += cend - nstart;
913 			nstart = cend;
914 			n++;
915 			GJ_DEBUG(3, "INSERT(%p): 4 (cbp=%p)", *head, cbp);
916 		} else if (nstart > cstart && nend < cend) {
917 			/*
918 			 *  +---------------------+
919 			 *  |     current bio     |
920 			 *  |   +-------------+   |
921 			 *  |   |             |   |
922 			 *  |   |             |   |
923 			 *  +---+-------------+---+
924 			 *      |   new bio   |
925 			 *      +-------------+
926 			 */
927 			g_journal_stats_bytes_skipped += nend - nstart;
928 			nbp = g_journal_new_bio(nstart, nend, joffset, data,
929 			    flags);
930 			nbp->bio_next = cbp->bio_next;
931 			cbp->bio_next = nbp;
932 			if (cbp->bio_data == NULL)
933 				tmpdata = NULL;
934 			else
935 				tmpdata = cbp->bio_data + nend - cstart;
936 			nbp = g_journal_new_bio(nend, cend,
937 			    cbp->bio_joffset + nend - cstart, tmpdata, flags);
938 			nbp->bio_next = ((struct bio *)cbp->bio_next)->bio_next;
939 			((struct bio *)cbp->bio_next)->bio_next = nbp;
940 			cbp->bio_length = nstart - cstart;
941 			if (cbp->bio_data != NULL) {
942 				cbp->bio_data = gj_realloc(cbp->bio_data,
943 				    cbp->bio_length, cend - cstart);
944 			}
945 			n += 2;
946 			GJ_DEBUG(3, "INSERT(%p): 5 (cbp=%p)", *head, cbp);
947 			goto end;
948 		} else if (nstart <= cstart && nend < cend) {
949 			/*
950 			 *  +-----------------+      +-------------+
951 			 *  |   current bio   |      | current bio |
952 			 *  +-------------+   |  +---+---------+   |
953 			 *  |             |   |  |   |         |   |
954 			 *  |             |   |  |   |         |   |
955 			 *  +-------------+---+  |   +---------+---+
956 			 *  |   new bio   |      |   new bio   |
957 			 *  +-------------+      +-------------+
958 			 */
959 			g_journal_stats_bytes_skipped += nend - nstart;
960 			nbp = g_journal_new_bio(nstart, nend, joffset, data,
961 			    flags);
962 			if (pbp == NULL)
963 				*head = nbp;
964 			else
965 				pbp->bio_next = nbp;
966 			nbp->bio_next = cbp;
967 			cbp->bio_offset = nend;
968 			cbp->bio_length = cend - nend;
969 			cbp->bio_joffset += nend - cstart;
970 			tmpdata = cbp->bio_data;
971 			if (tmpdata != NULL) {
972 				cbp->bio_data = gj_malloc(cbp->bio_length,
973 				    flags);
974 				if (cbp->bio_data != NULL) {
975 					bcopy(tmpdata + nend - cstart,
976 					    cbp->bio_data, cbp->bio_length);
977 				}
978 				gj_free(tmpdata, cend - cstart);
979 			}
980 			n++;
981 			GJ_DEBUG(3, "INSERT(%p): 6 (cbp=%p)", *head, cbp);
982 			goto end;
983 		}
984 		if (nstart == nend)
985 			goto end;
986 		pbp = cbp;
987 	}
988 	nbp = g_journal_new_bio(nstart, nend, joffset, data, flags);
989 	if (pbp == NULL)
990 		*head = nbp;
991 	else
992 		pbp->bio_next = nbp;
993 	nbp->bio_next = NULL;
994 	n++;
995 	GJ_DEBUG(3, "INSERT(%p): 8 (nbp=%p pbp=%p)", *head, nbp, pbp);
996 end:
997 	if (g_journal_debug >= 3) {
998 		GJQ_FOREACH(*head, cbp) {
999 			GJ_DEBUG(3, "ELEMENT: %p (%jd, %jd, %jd, %p)", cbp,
1000 			    (intmax_t)cbp->bio_offset,
1001 			    (intmax_t)cbp->bio_length,
1002 			    (intmax_t)cbp->bio_joffset, cbp->bio_data);
1003 		}
1004 		GJ_DEBUG(3, "INSERT(%p): DONE %d", *head, n);
1005 	}
1006 	return (n);
1007 }
1008 
1009 /*
1010  * The function combines neighbour bios trying to squeeze as much data as
1011  * possible into one bio.
1012  *
1013  * The function returns the number of bios combined (negative value).
1014  */
1015 static int
1016 g_journal_optimize(struct bio *head)
1017 {
1018 	struct bio *cbp, *pbp;
1019 	int n;
1020 
1021 	n = 0;
1022 	pbp = NULL;
1023 	GJQ_FOREACH(head, cbp) {
1024 		/* Skip bios which has to be read first. */
1025 		if (cbp->bio_data == NULL) {
1026 			pbp = NULL;
1027 			continue;
1028 		}
1029 		/* There is no previous bio yet. */
1030 		if (pbp == NULL) {
1031 			pbp = cbp;
1032 			continue;
1033 		}
1034 		/* Is this a neighbour bio? */
1035 		if (pbp->bio_offset + pbp->bio_length != cbp->bio_offset) {
1036 			/* Be sure that bios queue is sorted. */
1037 			KASSERT(pbp->bio_offset + pbp->bio_length < cbp->bio_offset,
1038 			    ("poffset=%jd plength=%jd coffset=%jd",
1039 			    (intmax_t)pbp->bio_offset,
1040 			    (intmax_t)pbp->bio_length,
1041 			    (intmax_t)cbp->bio_offset));
1042 			pbp = cbp;
1043 			continue;
1044 		}
1045 		/* Be sure we don't end up with too big bio. */
1046 		if (pbp->bio_length + cbp->bio_length > MAXPHYS) {
1047 			pbp = cbp;
1048 			continue;
1049 		}
1050 		/* Ok, we can join bios. */
1051 		GJ_LOGREQ(4, pbp, "Join: ");
1052 		GJ_LOGREQ(4, cbp, "and: ");
1053 		pbp->bio_data = gj_realloc(pbp->bio_data,
1054 		    pbp->bio_length + cbp->bio_length, pbp->bio_length);
1055 		bcopy(cbp->bio_data, pbp->bio_data + pbp->bio_length,
1056 		    cbp->bio_length);
1057 		gj_free(cbp->bio_data, cbp->bio_length);
1058 		pbp->bio_length += cbp->bio_length;
1059 		pbp->bio_next = cbp->bio_next;
1060 		g_destroy_bio(cbp);
1061 		cbp = pbp;
1062 		g_journal_stats_combined_ios++;
1063 		n--;
1064 		GJ_LOGREQ(4, pbp, "Got: ");
1065 	}
1066 	return (n);
1067 }
1068 
1069 /*
1070  * TODO: Update comment.
1071  * These are functions responsible for copying one portion of data from journal
1072  * to the destination provider.
1073  * The order goes like this:
1074  * 1. Read the header, which contains informations about data blocks
1075  *    following it.
1076  * 2. Read the data blocks from the journal.
1077  * 3. Write the data blocks on the data provider.
1078  *
1079  * g_journal_copy_start()
1080  * g_journal_copy_done() - got finished write request, logs potential errors.
1081  */
1082 
1083 /*
1084  * When there is no data in cache, this function is used to read it.
1085  */
1086 static void
1087 g_journal_read_first(struct g_journal_softc *sc, struct bio *bp)
1088 {
1089 	struct bio *cbp;
1090 
1091 	/*
1092 	 * We were short in memory, so data was freed.
1093 	 * In that case we need to read it back from journal.
1094 	 */
1095 	cbp = g_alloc_bio();
1096 	cbp->bio_cflags = bp->bio_cflags;
1097 	cbp->bio_parent = bp;
1098 	cbp->bio_offset = bp->bio_joffset;
1099 	cbp->bio_length = bp->bio_length;
1100 	cbp->bio_data = gj_malloc(bp->bio_length, M_WAITOK);
1101 	cbp->bio_cmd = BIO_READ;
1102 	cbp->bio_done = g_journal_std_done;
1103 	GJ_LOGREQ(4, cbp, "READ FIRST");
1104 	g_io_request(cbp, sc->sc_jconsumer);
1105 	g_journal_cache_misses++;
1106 }
1107 
1108 static void
1109 g_journal_copy_send(struct g_journal_softc *sc)
1110 {
1111 	struct bio *bioq, *bp, *lbp;
1112 
1113 	bioq = lbp = NULL;
1114 	mtx_lock(&sc->sc_mtx);
1115 	for (; sc->sc_copy_in_progress < g_journal_parallel_copies;) {
1116 		bp = GJQ_FIRST(sc->sc_inactive.jj_queue);
1117 		if (bp == NULL)
1118 			break;
1119 		GJQ_REMOVE(sc->sc_inactive.jj_queue, bp);
1120 		sc->sc_copy_in_progress++;
1121 		GJQ_INSERT_AFTER(bioq, bp, lbp);
1122 		lbp = bp;
1123 	}
1124 	mtx_unlock(&sc->sc_mtx);
1125 	if (g_journal_do_optimize)
1126 		sc->sc_copy_in_progress += g_journal_optimize(bioq);
1127 	while ((bp = GJQ_FIRST(bioq)) != NULL) {
1128 		GJQ_REMOVE(bioq, bp);
1129 		GJQ_INSERT_HEAD(sc->sc_copy_queue, bp);
1130 		bp->bio_cflags = GJ_BIO_COPY;
1131 		if (bp->bio_data == NULL)
1132 			g_journal_read_first(sc, bp);
1133 		else {
1134 			bp->bio_joffset = 0;
1135 			GJ_LOGREQ(4, bp, "SEND");
1136 			g_io_request(bp, sc->sc_dconsumer);
1137 		}
1138 	}
1139 }
1140 
1141 static void
1142 g_journal_copy_start(struct g_journal_softc *sc)
1143 {
1144 
1145 	/*
1146 	 * Remember in metadata that we're starting to copy journaled data
1147 	 * to the data provider.
1148 	 * In case of power failure, we will copy these data once again on boot.
1149 	 */
1150 	if (!sc->sc_journal_copying) {
1151 		sc->sc_journal_copying = 1;
1152 		GJ_DEBUG(1, "Starting copy of journal.");
1153 		g_journal_metadata_update(sc);
1154 	}
1155 	g_journal_copy_send(sc);
1156 }
1157 
1158 /*
1159  * Data block has been read from the journal provider.
1160  */
1161 static int
1162 g_journal_copy_read_done(struct bio *bp)
1163 {
1164 	struct g_journal_softc *sc;
1165 	struct g_consumer *cp;
1166 	struct bio *pbp;
1167 
1168 	KASSERT(bp->bio_cflags == GJ_BIO_COPY,
1169 	    ("Invalid bio (%d != %d).", bp->bio_cflags, GJ_BIO_COPY));
1170 
1171 	sc = bp->bio_from->geom->softc;
1172 	pbp = bp->bio_parent;
1173 
1174 	if (bp->bio_error != 0) {
1175 		GJ_DEBUG(0, "Error while reading data from %s (error=%d).",
1176 		    bp->bio_to->name, bp->bio_error);
1177 		/*
1178 		 * We will not be able to deliver WRITE request as well.
1179 		 */
1180 		gj_free(bp->bio_data, bp->bio_length);
1181 		g_destroy_bio(pbp);
1182 		g_destroy_bio(bp);
1183 		sc->sc_copy_in_progress--;
1184 		return (1);
1185 	}
1186 	pbp->bio_data = bp->bio_data;
1187 	cp = sc->sc_dconsumer;
1188 	g_io_request(pbp, cp);
1189 	GJ_LOGREQ(4, bp, "READ DONE");
1190 	g_destroy_bio(bp);
1191 	return (0);
1192 }
1193 
1194 /*
1195  * Data block has been written to the data provider.
1196  */
1197 static void
1198 g_journal_copy_write_done(struct bio *bp)
1199 {
1200 	struct g_journal_softc *sc;
1201 
1202 	KASSERT(bp->bio_cflags == GJ_BIO_COPY,
1203 	    ("Invalid bio (%d != %d).", bp->bio_cflags, GJ_BIO_COPY));
1204 
1205 	sc = bp->bio_from->geom->softc;
1206 	sc->sc_copy_in_progress--;
1207 
1208 	if (bp->bio_error != 0) {
1209 		GJ_LOGREQ(0, bp, "[copy] Error while writing data (error=%d)",
1210 		    bp->bio_error);
1211 	}
1212 	GJQ_REMOVE(sc->sc_copy_queue, bp);
1213 	gj_free(bp->bio_data, bp->bio_length);
1214 	GJ_LOGREQ(4, bp, "DONE");
1215 	g_destroy_bio(bp);
1216 
1217 	if (sc->sc_copy_in_progress == 0) {
1218 		/*
1219 		 * This was the last write request for this journal.
1220 		 */
1221 		GJ_DEBUG(1, "Data has been copied.");
1222 		sc->sc_journal_copying = 0;
1223 	}
1224 }
1225 
1226 static void g_journal_flush_done(struct bio *bp);
1227 
1228 /*
1229  * Flush one record onto active journal provider.
1230  */
1231 static void
1232 g_journal_flush(struct g_journal_softc *sc)
1233 {
1234 	struct g_journal_record_header hdr;
1235 	struct g_journal_entry *ent;
1236 	struct g_provider *pp;
1237 	struct bio **bioq;
1238 	struct bio *bp, *fbp, *pbp;
1239 	off_t joffset;
1240 	u_char *data, hash[16];
1241 	MD5_CTX ctx;
1242 	u_int i;
1243 
1244 	if (sc->sc_current_count == 0)
1245 		return;
1246 
1247 	pp = sc->sc_jprovider;
1248 	GJ_VALIDATE_OFFSET(sc->sc_journal_offset, sc);
1249 	joffset = sc->sc_journal_offset;
1250 
1251 	GJ_DEBUG(2, "Storing %d journal entries on %s at %jd.",
1252 	    sc->sc_current_count, pp->name, (intmax_t)joffset);
1253 
1254 	/*
1255 	 * Store 'journal id', so we know to which journal this record belongs.
1256 	 */
1257 	hdr.jrh_journal_id = sc->sc_journal_id;
1258 	/* Could be less than g_journal_record_entries if called due timeout. */
1259 	hdr.jrh_nentries = MIN(sc->sc_current_count, g_journal_record_entries);
1260 	strlcpy(hdr.jrh_magic, GJ_RECORD_HEADER_MAGIC, sizeof(hdr.jrh_magic));
1261 
1262 	bioq = &sc->sc_active.jj_queue;
1263 	GJQ_LAST(sc->sc_flush_queue, pbp);
1264 
1265 	fbp = g_alloc_bio();
1266 	fbp->bio_parent = NULL;
1267 	fbp->bio_cflags = GJ_BIO_JOURNAL;
1268 	fbp->bio_offset = -1;
1269 	fbp->bio_joffset = joffset;
1270 	fbp->bio_length = pp->sectorsize;
1271 	fbp->bio_cmd = BIO_WRITE;
1272 	fbp->bio_done = g_journal_std_done;
1273 	GJQ_INSERT_AFTER(sc->sc_flush_queue, fbp, pbp);
1274 	pbp = fbp;
1275 	fbp->bio_to = pp;
1276 	GJ_LOGREQ(4, fbp, "FLUSH_OUT");
1277 	joffset += pp->sectorsize;
1278 	sc->sc_flush_count++;
1279 	if (sc->sc_flags & GJF_DEVICE_CHECKSUM)
1280 		MD5Init(&ctx);
1281 
1282 	for (i = 0; i < hdr.jrh_nentries; i++) {
1283 		bp = sc->sc_current_queue;
1284 		KASSERT(bp != NULL, ("NULL bp"));
1285 		bp->bio_to = pp;
1286 		GJ_LOGREQ(4, bp, "FLUSHED");
1287 		sc->sc_current_queue = bp->bio_next;
1288 		bp->bio_next = NULL;
1289 		sc->sc_current_count--;
1290 
1291 		/* Add to the header. */
1292 		ent = &hdr.jrh_entries[i];
1293 		ent->je_offset = bp->bio_offset;
1294 		ent->je_joffset = joffset;
1295 		ent->je_length = bp->bio_length;
1296 
1297 		data = bp->bio_data;
1298 		if (sc->sc_flags & GJF_DEVICE_CHECKSUM)
1299 			MD5Update(&ctx, data, ent->je_length);
1300 		g_reset_bio(bp);
1301 		bp->bio_cflags = GJ_BIO_JOURNAL;
1302 		bp->bio_offset = ent->je_offset;
1303 		bp->bio_joffset = ent->je_joffset;
1304 		bp->bio_length = ent->je_length;
1305 		bp->bio_data = data;
1306 		bp->bio_cmd = BIO_WRITE;
1307 		bp->bio_done = g_journal_std_done;
1308 		GJQ_INSERT_AFTER(sc->sc_flush_queue, bp, pbp);
1309 		pbp = bp;
1310 		bp->bio_to = pp;
1311 		GJ_LOGREQ(4, bp, "FLUSH_OUT");
1312 		joffset += bp->bio_length;
1313 		sc->sc_flush_count++;
1314 
1315 		/*
1316 		 * Add request to the active sc_journal_queue queue.
1317 		 * This is our cache. After journal switch we don't have to
1318 		 * read the data from the inactive journal, because we keep
1319 		 * it in memory.
1320 		 */
1321 		g_journal_insert(bioq, ent->je_offset,
1322 		    ent->je_offset + ent->je_length, ent->je_joffset, data,
1323 		    M_NOWAIT);
1324 	}
1325 
1326 	/*
1327 	 * After all requests, store valid header.
1328 	 */
1329 	data = gj_malloc(pp->sectorsize, M_WAITOK);
1330 	if (sc->sc_flags & GJF_DEVICE_CHECKSUM) {
1331 		MD5Final(hash, &ctx);
1332 		bcopy(hash, hdr.jrh_sum, sizeof(hdr.jrh_sum));
1333 	}
1334 	g_journal_record_header_encode(&hdr, data);
1335 	fbp->bio_data = data;
1336 
1337 	sc->sc_journal_offset = joffset;
1338 
1339 	g_journal_check_overflow(sc);
1340 }
1341 
1342 /*
1343  * Flush request finished.
1344  */
1345 static void
1346 g_journal_flush_done(struct bio *bp)
1347 {
1348 	struct g_journal_softc *sc;
1349 	struct g_consumer *cp;
1350 
1351 	KASSERT((bp->bio_cflags & GJ_BIO_MASK) == GJ_BIO_JOURNAL,
1352 	    ("Invalid bio (%d != %d).", bp->bio_cflags, GJ_BIO_JOURNAL));
1353 
1354 	cp = bp->bio_from;
1355 	sc = cp->geom->softc;
1356 	sc->sc_flush_in_progress--;
1357 
1358 	if (bp->bio_error != 0) {
1359 		GJ_LOGREQ(0, bp, "[flush] Error while writing data (error=%d)",
1360 		    bp->bio_error);
1361 	}
1362 	gj_free(bp->bio_data, bp->bio_length);
1363 	GJ_LOGREQ(4, bp, "DONE");
1364 	g_destroy_bio(bp);
1365 }
1366 
1367 static void g_journal_release_delayed(struct g_journal_softc *sc);
1368 
1369 static void
1370 g_journal_flush_send(struct g_journal_softc *sc)
1371 {
1372 	struct g_consumer *cp;
1373 	struct bio *bioq, *bp, *lbp;
1374 
1375 	cp = sc->sc_jconsumer;
1376 	bioq = lbp = NULL;
1377 	while (sc->sc_flush_in_progress < g_journal_parallel_flushes) {
1378 		/* Send one flush requests to the active journal. */
1379 		bp = GJQ_FIRST(sc->sc_flush_queue);
1380 		if (bp != NULL) {
1381 			GJQ_REMOVE(sc->sc_flush_queue, bp);
1382 			sc->sc_flush_count--;
1383 			bp->bio_offset = bp->bio_joffset;
1384 			bp->bio_joffset = 0;
1385 			sc->sc_flush_in_progress++;
1386 			GJQ_INSERT_AFTER(bioq, bp, lbp);
1387 			lbp = bp;
1388 		}
1389 		/* Try to release delayed requests. */
1390 		g_journal_release_delayed(sc);
1391 		/* If there are no requests to flush, leave. */
1392 		if (GJQ_FIRST(sc->sc_flush_queue) == NULL)
1393 			break;
1394 	}
1395 	if (g_journal_do_optimize)
1396 		sc->sc_flush_in_progress += g_journal_optimize(bioq);
1397 	while ((bp = GJQ_FIRST(bioq)) != NULL) {
1398 		GJQ_REMOVE(bioq, bp);
1399 		GJ_LOGREQ(3, bp, "Flush request send");
1400 		g_io_request(bp, cp);
1401 	}
1402 }
1403 
1404 static void
1405 g_journal_add_current(struct g_journal_softc *sc, struct bio *bp)
1406 {
1407 	int n;
1408 
1409 	GJ_LOGREQ(4, bp, "CURRENT %d", sc->sc_current_count);
1410 	n = g_journal_insert_bio(&sc->sc_current_queue, bp, M_WAITOK);
1411 	sc->sc_current_count += n;
1412 	n = g_journal_optimize(sc->sc_current_queue);
1413 	sc->sc_current_count += n;
1414 	/*
1415 	 * For requests which are added to the current queue we deliver
1416 	 * response immediately.
1417 	 */
1418 	bp->bio_completed = bp->bio_length;
1419 	g_io_deliver(bp, 0);
1420 	if (sc->sc_current_count >= g_journal_record_entries) {
1421 		/*
1422 		 * Let's flush one record onto active journal provider.
1423 		 */
1424 		g_journal_flush(sc);
1425 	}
1426 }
1427 
1428 static void
1429 g_journal_release_delayed(struct g_journal_softc *sc)
1430 {
1431 	struct bio *bp;
1432 
1433 	for (;;) {
1434 		/* The flush queue is full, exit. */
1435 		if (sc->sc_flush_count >= g_journal_accept_immediately)
1436 			return;
1437 		bp = bioq_takefirst(&sc->sc_delayed_queue);
1438 		if (bp == NULL)
1439 			return;
1440 		sc->sc_delayed_count--;
1441 		g_journal_add_current(sc, bp);
1442 	}
1443 }
1444 
1445 /*
1446  * Add I/O request to the current queue. If we have enough requests for one
1447  * journal record we flush them onto active journal provider.
1448  */
1449 static void
1450 g_journal_add_request(struct g_journal_softc *sc, struct bio *bp)
1451 {
1452 
1453 	/*
1454 	 * The flush queue is full, we need to delay the request.
1455 	 */
1456 	if (sc->sc_delayed_count > 0 ||
1457 	    sc->sc_flush_count >= g_journal_accept_immediately) {
1458 		GJ_LOGREQ(4, bp, "DELAYED");
1459 		bioq_insert_tail(&sc->sc_delayed_queue, bp);
1460 		sc->sc_delayed_count++;
1461 		return;
1462 	}
1463 
1464 	KASSERT(TAILQ_EMPTY(&sc->sc_delayed_queue.queue),
1465 	    ("DELAYED queue not empty."));
1466 	g_journal_add_current(sc, bp);
1467 }
1468 
1469 static void g_journal_read_done(struct bio *bp);
1470 
1471 /*
1472  * Try to find requested data in cache.
1473  */
1474 static struct bio *
1475 g_journal_read_find(struct bio *head, int sorted, struct bio *pbp, off_t ostart,
1476     off_t oend)
1477 {
1478 	off_t cstart, cend;
1479 	struct bio *bp;
1480 
1481 	GJQ_FOREACH(head, bp) {
1482 		if (bp->bio_offset == -1)
1483 			continue;
1484 		cstart = MAX(ostart, bp->bio_offset);
1485 		cend = MIN(oend, bp->bio_offset + bp->bio_length);
1486 		if (cend <= ostart)
1487 			continue;
1488 		else if (cstart >= oend) {
1489 			if (!sorted)
1490 				continue;
1491 			else {
1492 				bp = NULL;
1493 				break;
1494 			}
1495 		}
1496 		if (bp->bio_data == NULL)
1497 			break;
1498 		GJ_DEBUG(3, "READ(%p): (%jd, %jd) (bp=%p)", head, cstart, cend,
1499 		    bp);
1500 		bcopy(bp->bio_data + cstart - bp->bio_offset,
1501 		    pbp->bio_data + cstart - pbp->bio_offset, cend - cstart);
1502 		pbp->bio_completed += cend - cstart;
1503 		if (pbp->bio_completed == pbp->bio_length) {
1504 			/*
1505 			 * Cool, the whole request was in cache, deliver happy
1506 			 * message.
1507 			 */
1508 			g_io_deliver(pbp, 0);
1509 			return (pbp);
1510 		}
1511 		break;
1512 	}
1513 	return (bp);
1514 }
1515 
1516 /*
1517  * This function is used for collecting data on read.
1518  * The complexity is because parts of the data can be stored in four different
1519  * places:
1520  * - in memory - the data not yet send to the active journal provider
1521  * - in the active journal
1522  * - in the inactive journal
1523  * - in the data provider
1524  */
1525 static void
1526 g_journal_read(struct g_journal_softc *sc, struct bio *pbp, off_t ostart,
1527     off_t oend)
1528 {
1529 	struct bio *bp, *nbp, *head;
1530 	off_t cstart, cend;
1531 	u_int i, sorted = 0;
1532 
1533 	GJ_DEBUG(3, "READ: (%jd, %jd)", ostart, oend);
1534 
1535 	cstart = cend = -1;
1536 	bp = NULL;
1537 	head = NULL;
1538 	for (i = 1; i <= 5; i++) {
1539 		switch (i) {
1540 		case 1:	/* Not-yet-send data. */
1541 			head = sc->sc_current_queue;
1542 			sorted = 1;
1543 			break;
1544 		case 2: /* Skip flush queue as they are also in active queue */
1545 			continue;
1546 		case 3:	/* Active journal. */
1547 			head = sc->sc_active.jj_queue;
1548 			sorted = 1;
1549 			break;
1550 		case 4:	/* Inactive journal. */
1551 			/*
1552 			 * XXX: Here could be a race with g_journal_lowmem().
1553 			 */
1554 			head = sc->sc_inactive.jj_queue;
1555 			sorted = 1;
1556 			break;
1557 		case 5:	/* In-flight to the data provider. */
1558 			head = sc->sc_copy_queue;
1559 			sorted = 0;
1560 			break;
1561 		default:
1562 			panic("gjournal %s: i=%d", __func__, i);
1563 		}
1564 		bp = g_journal_read_find(head, sorted, pbp, ostart, oend);
1565 		if (bp == pbp) { /* Got the whole request. */
1566 			GJ_DEBUG(2, "Got the whole request from %u.", i);
1567 			return;
1568 		} else if (bp != NULL) {
1569 			cstart = MAX(ostart, bp->bio_offset);
1570 			cend = MIN(oend, bp->bio_offset + bp->bio_length);
1571 			GJ_DEBUG(2, "Got part of the request from %u (%jd-%jd).",
1572 			    i, (intmax_t)cstart, (intmax_t)cend);
1573 			break;
1574 		}
1575 	}
1576 	if (bp != NULL) {
1577 		if (bp->bio_data == NULL) {
1578 			nbp = g_duplicate_bio(pbp);
1579 			nbp->bio_cflags = GJ_BIO_READ;
1580 			nbp->bio_data =
1581 			    pbp->bio_data + cstart - pbp->bio_offset;
1582 			nbp->bio_offset =
1583 			    bp->bio_joffset + cstart - bp->bio_offset;
1584 			nbp->bio_length = cend - cstart;
1585 			nbp->bio_done = g_journal_read_done;
1586 			g_io_request(nbp, sc->sc_jconsumer);
1587 		}
1588 		/*
1589 		 * If we don't have the whole request yet, call g_journal_read()
1590 		 * recursively.
1591 		 */
1592 		if (ostart < cstart)
1593 			g_journal_read(sc, pbp, ostart, cstart);
1594 		if (oend > cend)
1595 			g_journal_read(sc, pbp, cend, oend);
1596 	} else {
1597 		/*
1598 		 * No data in memory, no data in journal.
1599 		 * Its time for asking data provider.
1600 		 */
1601 		GJ_DEBUG(3, "READ(data): (%jd, %jd)", ostart, oend);
1602 		nbp = g_duplicate_bio(pbp);
1603 		nbp->bio_cflags = GJ_BIO_READ;
1604 		nbp->bio_data = pbp->bio_data + ostart - pbp->bio_offset;
1605 		nbp->bio_offset = ostart;
1606 		nbp->bio_length = oend - ostart;
1607 		nbp->bio_done = g_journal_read_done;
1608 		g_io_request(nbp, sc->sc_dconsumer);
1609 		/* We have the whole request, return here. */
1610 		return;
1611 	}
1612 }
1613 
1614 /*
1615  * Function responsible for handling finished READ requests.
1616  * Actually, g_std_done() could be used here, the only difference is that we
1617  * log error.
1618  */
1619 static void
1620 g_journal_read_done(struct bio *bp)
1621 {
1622 	struct bio *pbp;
1623 
1624 	KASSERT(bp->bio_cflags == GJ_BIO_READ,
1625 	    ("Invalid bio (%d != %d).", bp->bio_cflags, GJ_BIO_READ));
1626 
1627 	pbp = bp->bio_parent;
1628 	pbp->bio_inbed++;
1629 	pbp->bio_completed += bp->bio_length;
1630 
1631 	if (bp->bio_error != 0) {
1632 		if (pbp->bio_error == 0)
1633 			pbp->bio_error = bp->bio_error;
1634 		GJ_DEBUG(0, "Error while reading data from %s (error=%d).",
1635 		    bp->bio_to->name, bp->bio_error);
1636 	}
1637 	g_destroy_bio(bp);
1638 	if (pbp->bio_children == pbp->bio_inbed &&
1639 	    pbp->bio_completed == pbp->bio_length) {
1640 		/* We're done. */
1641 		g_io_deliver(pbp, 0);
1642 	}
1643 }
1644 
1645 /*
1646  * Deactive current journal and active next one.
1647  */
1648 static void
1649 g_journal_switch(struct g_journal_softc *sc)
1650 {
1651 	struct g_provider *pp;
1652 
1653 	if (JEMPTY(sc)) {
1654 		GJ_DEBUG(3, "No need for %s switch.", sc->sc_name);
1655 		pp = LIST_FIRST(&sc->sc_geom->provider);
1656 		if (!(sc->sc_flags & GJF_DEVICE_CLEAN) && pp->acw == 0) {
1657 			sc->sc_flags |= GJF_DEVICE_CLEAN;
1658 			GJ_DEBUG(1, "Marking %s as clean.", sc->sc_name);
1659 			g_journal_metadata_update(sc);
1660 		}
1661 	} else {
1662 		GJ_DEBUG(3, "Switching journal %s.", sc->sc_geom->name);
1663 
1664 		pp = sc->sc_jprovider;
1665 
1666 		sc->sc_journal_previous_id = sc->sc_journal_id;
1667 
1668 		sc->sc_journal_id = sc->sc_journal_next_id;
1669 		sc->sc_journal_next_id = arc4random();
1670 
1671 		GJ_VALIDATE_OFFSET(sc->sc_journal_offset, sc);
1672 
1673 		g_journal_write_header(sc);
1674 
1675 		sc->sc_inactive.jj_offset = sc->sc_active.jj_offset;
1676 		sc->sc_inactive.jj_queue = sc->sc_active.jj_queue;
1677 
1678 		sc->sc_active.jj_offset =
1679 		    sc->sc_journal_offset - pp->sectorsize;
1680 		sc->sc_active.jj_queue = NULL;
1681 
1682 		/*
1683 		 * Switch is done, start copying data from the (now) inactive
1684 		 * journal to the data provider.
1685 		 */
1686 		g_journal_copy_start(sc);
1687 	}
1688 	mtx_lock(&sc->sc_mtx);
1689 	sc->sc_flags &= ~GJF_DEVICE_SWITCH;
1690 	mtx_unlock(&sc->sc_mtx);
1691 }
1692 
1693 static void
1694 g_journal_initialize(struct g_journal_softc *sc)
1695 {
1696 
1697 	sc->sc_journal_id = arc4random();
1698 	sc->sc_journal_next_id = arc4random();
1699 	sc->sc_journal_previous_id = sc->sc_journal_id;
1700 	sc->sc_journal_offset = sc->sc_jstart;
1701 	sc->sc_inactive.jj_offset = sc->sc_jstart;
1702 	g_journal_write_header(sc);
1703 	sc->sc_active.jj_offset = sc->sc_jstart;
1704 }
1705 
1706 static void
1707 g_journal_mark_as_dirty(struct g_journal_softc *sc)
1708 {
1709 	const struct g_journal_desc *desc;
1710 	int i;
1711 
1712 	GJ_DEBUG(1, "Marking file system %s as dirty.", sc->sc_name);
1713 	for (i = 0; (desc = g_journal_filesystems[i]) != NULL; i++)
1714 		desc->jd_dirty(sc->sc_dconsumer);
1715 }
1716 
1717 /*
1718  * Function read record header from the given journal.
1719  * It is very simlar to g_read_data(9), but it doesn't allocate memory for bio
1720  * and data on every call.
1721  */
1722 static int
1723 g_journal_sync_read(struct g_consumer *cp, struct bio *bp, off_t offset,
1724     void *data)
1725 {
1726 	int error;
1727 
1728 	g_reset_bio(bp);
1729 	bp->bio_cmd = BIO_READ;
1730 	bp->bio_done = NULL;
1731 	bp->bio_offset = offset;
1732 	bp->bio_length = cp->provider->sectorsize;
1733 	bp->bio_data = data;
1734 	g_io_request(bp, cp);
1735 	error = biowait(bp, "gjs_read");
1736 	return (error);
1737 }
1738 
1739 #if 0
1740 /*
1741  * Function is called when we start the journal device and we detect that
1742  * one of the journals was not fully copied.
1743  * The purpose of this function is to read all records headers from journal
1744  * and placed them in the inactive queue, so we can start journal
1745  * synchronization process and the journal provider itself.
1746  * Design decision was taken to not synchronize the whole journal here as it
1747  * can take too much time. Reading headers only and delaying synchronization
1748  * process until after journal provider is started should be the best choice.
1749  */
1750 #endif
1751 
1752 static void
1753 g_journal_sync(struct g_journal_softc *sc)
1754 {
1755 	struct g_journal_record_header rhdr;
1756 	struct g_journal_entry *ent;
1757 	struct g_journal_header jhdr;
1758 	struct g_consumer *cp;
1759 	struct bio *bp, *fbp, *tbp;
1760 	off_t joffset, offset;
1761 	u_char *buf, sum[16];
1762 	uint64_t id;
1763 	MD5_CTX ctx;
1764 	int error, found, i;
1765 
1766 	found = 0;
1767 	fbp = NULL;
1768 	cp = sc->sc_jconsumer;
1769 	bp = g_alloc_bio();
1770 	buf = gj_malloc(cp->provider->sectorsize, M_WAITOK);
1771 	offset = joffset = sc->sc_inactive.jj_offset = sc->sc_journal_offset;
1772 
1773 	GJ_DEBUG(2, "Looking for termination at %jd.", (intmax_t)joffset);
1774 
1775 	/*
1776 	 * Read and decode first journal header.
1777 	 */
1778 	error = g_journal_sync_read(cp, bp, offset, buf);
1779 	if (error != 0) {
1780 		GJ_DEBUG(0, "Error while reading journal header from %s.",
1781 		    cp->provider->name);
1782 		goto end;
1783 	}
1784 	error = g_journal_header_decode(buf, &jhdr);
1785 	if (error != 0) {
1786 		GJ_DEBUG(0, "Cannot decode journal header from %s.",
1787 		    cp->provider->name);
1788 		goto end;
1789 	}
1790 	id = sc->sc_journal_id;
1791 	if (jhdr.jh_journal_id != sc->sc_journal_id) {
1792 		GJ_DEBUG(1, "Journal ID mismatch at %jd (0x%08x != 0x%08x).",
1793 		    (intmax_t)offset, (u_int)jhdr.jh_journal_id, (u_int)id);
1794 		goto end;
1795 	}
1796 	offset += cp->provider->sectorsize;
1797 	id = sc->sc_journal_next_id = jhdr.jh_journal_next_id;
1798 
1799 	for (;;) {
1800 		/*
1801 		 * If the biggest record won't fit, look for a record header or
1802 		 * journal header from the beginning.
1803 		 */
1804 		GJ_VALIDATE_OFFSET(offset, sc);
1805 		error = g_journal_sync_read(cp, bp, offset, buf);
1806 		if (error != 0) {
1807 			/*
1808 			 * Not good. Having an error while reading header
1809 			 * means, that we cannot read next headers and in
1810 			 * consequence we cannot find termination.
1811 			 */
1812 			GJ_DEBUG(0,
1813 			    "Error while reading record header from %s.",
1814 			    cp->provider->name);
1815 			break;
1816 		}
1817 
1818 		error = g_journal_record_header_decode(buf, &rhdr);
1819 		if (error != 0) {
1820 			GJ_DEBUG(2, "Not a record header at %jd (error=%d).",
1821 			    (intmax_t)offset, error);
1822 			/*
1823 			 * This is not a record header.
1824 			 * If we are lucky, this is next journal header.
1825 			 */
1826 			error = g_journal_header_decode(buf, &jhdr);
1827 			if (error != 0) {
1828 				GJ_DEBUG(1, "Not a journal header at %jd (error=%d).",
1829 				    (intmax_t)offset, error);
1830 				/*
1831 				 * Nope, this is not journal header, which
1832 				 * bascially means that journal is not
1833 				 * terminated properly.
1834 				 */
1835 				error = ENOENT;
1836 				break;
1837 			}
1838 			/*
1839 			 * Ok. This is header of _some_ journal. Now we need to
1840 			 * verify if this is header of the _next_ journal.
1841 			 */
1842 			if (jhdr.jh_journal_id != id) {
1843 				GJ_DEBUG(1, "Journal ID mismatch at %jd "
1844 				    "(0x%08x != 0x%08x).", (intmax_t)offset,
1845 				    (u_int)jhdr.jh_journal_id, (u_int)id);
1846 				error = ENOENT;
1847 				break;
1848 			}
1849 
1850 			/* Found termination. */
1851 			found++;
1852 			GJ_DEBUG(1, "Found termination at %jd (id=0x%08x).",
1853 			    (intmax_t)offset, (u_int)id);
1854 			sc->sc_active.jj_offset = offset;
1855 			sc->sc_journal_offset =
1856 			    offset + cp->provider->sectorsize;
1857 			sc->sc_journal_id = id;
1858 			id = sc->sc_journal_next_id = jhdr.jh_journal_next_id;
1859 
1860 			while ((tbp = fbp) != NULL) {
1861 				fbp = tbp->bio_next;
1862 				GJ_LOGREQ(3, tbp, "Adding request.");
1863 				g_journal_insert_bio(&sc->sc_inactive.jj_queue,
1864 				    tbp, M_WAITOK);
1865 			}
1866 
1867 			/* Skip journal's header. */
1868 			offset += cp->provider->sectorsize;
1869 			continue;
1870 		}
1871 
1872 		/* Skip record's header. */
1873 		offset += cp->provider->sectorsize;
1874 
1875 		/*
1876 		 * Add information about every record entry to the inactive
1877 		 * queue.
1878 		 */
1879 		if (sc->sc_flags & GJF_DEVICE_CHECKSUM)
1880 			MD5Init(&ctx);
1881 		for (i = 0; i < rhdr.jrh_nentries; i++) {
1882 			ent = &rhdr.jrh_entries[i];
1883 			GJ_DEBUG(3, "Insert entry: %jd %jd.",
1884 			    (intmax_t)ent->je_offset, (intmax_t)ent->je_length);
1885 			g_journal_insert(&fbp, ent->je_offset,
1886 			    ent->je_offset + ent->je_length, ent->je_joffset,
1887 			    NULL, M_WAITOK);
1888 			if (sc->sc_flags & GJF_DEVICE_CHECKSUM) {
1889 				u_char *buf2;
1890 
1891 				/*
1892 				 * TODO: Should use faster function (like
1893 				 *       g_journal_sync_read()).
1894 				 */
1895 				buf2 = g_read_data(cp, offset, ent->je_length,
1896 				    NULL);
1897 				if (buf2 == NULL)
1898 					GJ_DEBUG(0, "Cannot read data at %jd.",
1899 					    (intmax_t)offset);
1900 				else {
1901 					MD5Update(&ctx, buf2, ent->je_length);
1902 					g_free(buf2);
1903 				}
1904 			}
1905 			/* Skip entry's data. */
1906 			offset += ent->je_length;
1907 		}
1908 		if (sc->sc_flags & GJF_DEVICE_CHECKSUM) {
1909 			MD5Final(sum, &ctx);
1910 			if (bcmp(sum, rhdr.jrh_sum, sizeof(rhdr.jrh_sum)) != 0) {
1911 				GJ_DEBUG(0, "MD5 hash mismatch at %jd!",
1912 				    (intmax_t)offset);
1913 			}
1914 		}
1915 	}
1916 end:
1917 	gj_free(bp->bio_data, cp->provider->sectorsize);
1918 	g_destroy_bio(bp);
1919 
1920 	/* Remove bios from unterminated journal. */
1921 	while ((tbp = fbp) != NULL) {
1922 		fbp = tbp->bio_next;
1923 		g_destroy_bio(tbp);
1924 	}
1925 
1926 	if (found < 1 && joffset > 0) {
1927 		GJ_DEBUG(0, "Journal on %s is broken/corrupted. Initializing.",
1928 		    sc->sc_name);
1929 		while ((tbp = sc->sc_inactive.jj_queue) != NULL) {
1930 			sc->sc_inactive.jj_queue = tbp->bio_next;
1931 			g_destroy_bio(tbp);
1932 		}
1933 		g_journal_initialize(sc);
1934 		g_journal_mark_as_dirty(sc);
1935 	} else {
1936 		GJ_DEBUG(0, "Journal %s consistent.", sc->sc_name);
1937 		g_journal_copy_start(sc);
1938 	}
1939 }
1940 
1941 /*
1942  * Wait for requests.
1943  * If we have requests in the current queue, flush them after 3 seconds from the
1944  * last flush. In this way we don't wait forever (or for journal switch) with
1945  * storing not full records on journal.
1946  */
1947 static void
1948 g_journal_wait(struct g_journal_softc *sc, time_t last_write)
1949 {
1950 	int error, timeout;
1951 
1952 	GJ_DEBUG(3, "%s: enter", __func__);
1953 	if (sc->sc_current_count == 0) {
1954 		if (g_journal_debug < 2)
1955 			msleep(sc, &sc->sc_mtx, PRIBIO | PDROP, "gj:work", 0);
1956 		else {
1957 			/*
1958 			 * If we have debug turned on, show number of elements
1959 			 * in various queues.
1960 			 */
1961 			for (;;) {
1962 				error = msleep(sc, &sc->sc_mtx, PRIBIO,
1963 				    "gj:work", hz * 3);
1964 				if (error == 0) {
1965 					mtx_unlock(&sc->sc_mtx);
1966 					break;
1967 				}
1968 				GJ_DEBUG(3, "Report: current count=%d",
1969 				    sc->sc_current_count);
1970 				GJ_DEBUG(3, "Report: flush count=%d",
1971 				    sc->sc_flush_count);
1972 				GJ_DEBUG(3, "Report: flush in progress=%d",
1973 				    sc->sc_flush_in_progress);
1974 				GJ_DEBUG(3, "Report: copy in progress=%d",
1975 				    sc->sc_copy_in_progress);
1976 				GJ_DEBUG(3, "Report: delayed=%d",
1977 				    sc->sc_delayed_count);
1978 			}
1979 		}
1980 		GJ_DEBUG(3, "%s: exit 1", __func__);
1981 		return;
1982 	}
1983 
1984 	/*
1985 	 * Flush even not full records every 3 seconds.
1986 	 */
1987 	timeout = (last_write + 3 - time_second) * hz;
1988 	if (timeout <= 0) {
1989 		mtx_unlock(&sc->sc_mtx);
1990 		g_journal_flush(sc);
1991 		g_journal_flush_send(sc);
1992 		GJ_DEBUG(3, "%s: exit 2", __func__);
1993 		return;
1994 	}
1995 	error = msleep(sc, &sc->sc_mtx, PRIBIO | PDROP, "gj:work", timeout);
1996 	if (error == EWOULDBLOCK)
1997 		g_journal_flush_send(sc);
1998 	GJ_DEBUG(3, "%s: exit 3", __func__);
1999 }
2000 
2001 /*
2002  * Worker thread.
2003  */
2004 static void
2005 g_journal_worker(void *arg)
2006 {
2007 	struct g_journal_softc *sc;
2008 	struct g_geom *gp;
2009 	struct g_provider *pp;
2010 	struct bio *bp;
2011 	time_t last_write;
2012 	int type;
2013 
2014 	thread_lock(curthread);
2015 	sched_prio(curthread, PRIBIO);
2016 	thread_unlock(curthread);
2017 
2018 	sc = arg;
2019 	type = 0;	/* gcc */
2020 
2021 	if (sc->sc_flags & GJF_DEVICE_CLEAN) {
2022 		GJ_DEBUG(0, "Journal %s clean.", sc->sc_name);
2023 		g_journal_initialize(sc);
2024 	} else {
2025 		g_journal_sync(sc);
2026 	}
2027 	/*
2028 	 * Check if we can use BIO_FLUSH.
2029 	 */
2030 	sc->sc_bio_flush = 0;
2031 	if (g_io_flush(sc->sc_jconsumer) == 0) {
2032 		sc->sc_bio_flush |= GJ_FLUSH_JOURNAL;
2033 		GJ_DEBUG(1, "BIO_FLUSH supported by %s.",
2034 		    sc->sc_jconsumer->provider->name);
2035 	} else {
2036 		GJ_DEBUG(0, "BIO_FLUSH not supported by %s.",
2037 		    sc->sc_jconsumer->provider->name);
2038 	}
2039 	if (sc->sc_jconsumer != sc->sc_dconsumer) {
2040 		if (g_io_flush(sc->sc_dconsumer) == 0) {
2041 			sc->sc_bio_flush |= GJ_FLUSH_DATA;
2042 			GJ_DEBUG(1, "BIO_FLUSH supported by %s.",
2043 			    sc->sc_dconsumer->provider->name);
2044 		} else {
2045 			GJ_DEBUG(0, "BIO_FLUSH not supported by %s.",
2046 			    sc->sc_dconsumer->provider->name);
2047 		}
2048 	}
2049 
2050 	gp = sc->sc_geom;
2051 	g_topology_lock();
2052 	pp = g_new_providerf(gp, "%s.journal", sc->sc_name);
2053 	pp->mediasize = sc->sc_mediasize;
2054 	/*
2055 	 * There could be a problem when data provider and journal providers
2056 	 * have different sectorsize, but such scenario is prevented on journal
2057 	 * creation.
2058 	 */
2059 	pp->sectorsize = sc->sc_sectorsize;
2060 	g_error_provider(pp, 0);
2061 	g_topology_unlock();
2062 	last_write = time_second;
2063 
2064 	if (sc->sc_rootmount != NULL) {
2065 		GJ_DEBUG(1, "root_mount_rel %p", sc->sc_rootmount);
2066 		root_mount_rel(sc->sc_rootmount);
2067 		sc->sc_rootmount = NULL;
2068 	}
2069 
2070 	for (;;) {
2071 		/* Get first request from the queue. */
2072 		mtx_lock(&sc->sc_mtx);
2073 		bp = bioq_first(&sc->sc_back_queue);
2074 		if (bp != NULL)
2075 			type = (bp->bio_cflags & GJ_BIO_MASK);
2076 		if (bp == NULL) {
2077 			bp = bioq_first(&sc->sc_regular_queue);
2078 			if (bp != NULL)
2079 				type = GJ_BIO_REGULAR;
2080 		}
2081 		if (bp == NULL) {
2082 try_switch:
2083 			if ((sc->sc_flags & GJF_DEVICE_SWITCH) ||
2084 			    (sc->sc_flags & GJF_DEVICE_DESTROY)) {
2085 				if (sc->sc_current_count > 0) {
2086 					mtx_unlock(&sc->sc_mtx);
2087 					g_journal_flush(sc);
2088 					g_journal_flush_send(sc);
2089 					continue;
2090 				}
2091 				if (sc->sc_flush_in_progress > 0)
2092 					goto sleep;
2093 				if (sc->sc_copy_in_progress > 0)
2094 					goto sleep;
2095 			}
2096 			if (sc->sc_flags & GJF_DEVICE_SWITCH) {
2097 				mtx_unlock(&sc->sc_mtx);
2098 				g_journal_switch(sc);
2099 				wakeup(&sc->sc_journal_copying);
2100 				continue;
2101 			}
2102 			if (sc->sc_flags & GJF_DEVICE_DESTROY) {
2103 				GJ_DEBUG(1, "Shutting down worker "
2104 				    "thread for %s.", gp->name);
2105 				sc->sc_worker = NULL;
2106 				wakeup(&sc->sc_worker);
2107 				mtx_unlock(&sc->sc_mtx);
2108 				kproc_exit(0);
2109 			}
2110 sleep:
2111 			g_journal_wait(sc, last_write);
2112 			continue;
2113 		}
2114 		/*
2115 		 * If we're in switch process, we need to delay all new
2116 		 * write requests until its done.
2117 		 */
2118 		if ((sc->sc_flags & GJF_DEVICE_SWITCH) &&
2119 		    type == GJ_BIO_REGULAR && bp->bio_cmd == BIO_WRITE) {
2120 			GJ_LOGREQ(2, bp, "WRITE on SWITCH");
2121 			goto try_switch;
2122 		}
2123 		if (type == GJ_BIO_REGULAR)
2124 			bioq_remove(&sc->sc_regular_queue, bp);
2125 		else
2126 			bioq_remove(&sc->sc_back_queue, bp);
2127 		mtx_unlock(&sc->sc_mtx);
2128 		switch (type) {
2129 		case GJ_BIO_REGULAR:
2130 			/* Regular request. */
2131 			switch (bp->bio_cmd) {
2132 			case BIO_READ:
2133 				g_journal_read(sc, bp, bp->bio_offset,
2134 				    bp->bio_offset + bp->bio_length);
2135 				break;
2136 			case BIO_WRITE:
2137 				last_write = time_second;
2138 				g_journal_add_request(sc, bp);
2139 				g_journal_flush_send(sc);
2140 				break;
2141 			default:
2142 				panic("Invalid bio_cmd (%d).", bp->bio_cmd);
2143 			}
2144 			break;
2145 		case GJ_BIO_COPY:
2146 			switch (bp->bio_cmd) {
2147 			case BIO_READ:
2148 				if (g_journal_copy_read_done(bp))
2149 					g_journal_copy_send(sc);
2150 				break;
2151 			case BIO_WRITE:
2152 				g_journal_copy_write_done(bp);
2153 				g_journal_copy_send(sc);
2154 				break;
2155 			default:
2156 				panic("Invalid bio_cmd (%d).", bp->bio_cmd);
2157 			}
2158 			break;
2159 		case GJ_BIO_JOURNAL:
2160 			g_journal_flush_done(bp);
2161 			g_journal_flush_send(sc);
2162 			break;
2163 		case GJ_BIO_READ:
2164 		default:
2165 			panic("Invalid bio (%d).", type);
2166 		}
2167 	}
2168 }
2169 
2170 static void
2171 g_journal_destroy_event(void *arg, int flags __unused)
2172 {
2173 	struct g_journal_softc *sc;
2174 
2175 	g_topology_assert();
2176 	sc = arg;
2177 	g_journal_destroy(sc);
2178 }
2179 
2180 static void
2181 g_journal_timeout(void *arg)
2182 {
2183 	struct g_journal_softc *sc;
2184 
2185 	sc = arg;
2186 	GJ_DEBUG(0, "Timeout. Journal %s cannot be completed.",
2187 	    sc->sc_geom->name);
2188 	g_post_event(g_journal_destroy_event, sc, M_NOWAIT, NULL);
2189 }
2190 
2191 static struct g_geom *
2192 g_journal_create(struct g_class *mp, struct g_provider *pp,
2193     const struct g_journal_metadata *md)
2194 {
2195 	struct g_journal_softc *sc;
2196 	struct g_geom *gp;
2197 	struct g_consumer *cp;
2198 	int error;
2199 
2200 	sc = NULL;	/* gcc */
2201 
2202 	g_topology_assert();
2203 	/*
2204 	 * There are two possibilities:
2205 	 * 1. Data and both journals are on the same provider.
2206 	 * 2. Data and journals are all on separated providers.
2207 	 */
2208 	/* Look for journal device with the same ID. */
2209 	LIST_FOREACH(gp, &mp->geom, geom) {
2210 		sc = gp->softc;
2211 		if (sc == NULL)
2212 			continue;
2213 		if (sc->sc_id == md->md_id)
2214 			break;
2215 	}
2216 	if (gp == NULL)
2217 		sc = NULL;
2218 	else if (sc != NULL && (sc->sc_type & md->md_type) != 0) {
2219 		GJ_DEBUG(1, "Journal device %u already configured.", sc->sc_id);
2220 		return (NULL);
2221 	}
2222 	if (md->md_type == 0 || (md->md_type & ~GJ_TYPE_COMPLETE) != 0) {
2223 		GJ_DEBUG(0, "Invalid type on %s.", pp->name);
2224 		return (NULL);
2225 	}
2226 	if (md->md_type & GJ_TYPE_DATA) {
2227 		GJ_DEBUG(0, "Journal %u: %s contains data.", md->md_id,
2228 		    pp->name);
2229 	}
2230 	if (md->md_type & GJ_TYPE_JOURNAL) {
2231 		GJ_DEBUG(0, "Journal %u: %s contains journal.", md->md_id,
2232 		    pp->name);
2233 	}
2234 
2235 	if (sc == NULL) {
2236 		/* Action geom. */
2237 		sc = malloc(sizeof(*sc), M_JOURNAL, M_WAITOK | M_ZERO);
2238 		sc->sc_id = md->md_id;
2239 		sc->sc_type = 0;
2240 		sc->sc_flags = 0;
2241 		sc->sc_worker = NULL;
2242 
2243 		gp = g_new_geomf(mp, "gjournal %u", sc->sc_id);
2244 		gp->start = g_journal_start;
2245 		gp->orphan = g_journal_orphan;
2246 		gp->access = g_journal_access;
2247 		gp->softc = sc;
2248 		gp->flags |= G_GEOM_VOLATILE_BIO;
2249 		sc->sc_geom = gp;
2250 
2251 		mtx_init(&sc->sc_mtx, "gjournal", NULL, MTX_DEF);
2252 
2253 		bioq_init(&sc->sc_back_queue);
2254 		bioq_init(&sc->sc_regular_queue);
2255 		bioq_init(&sc->sc_delayed_queue);
2256 		sc->sc_delayed_count = 0;
2257 		sc->sc_current_queue = NULL;
2258 		sc->sc_current_count = 0;
2259 		sc->sc_flush_queue = NULL;
2260 		sc->sc_flush_count = 0;
2261 		sc->sc_flush_in_progress = 0;
2262 		sc->sc_copy_queue = NULL;
2263 		sc->sc_copy_in_progress = 0;
2264 		sc->sc_inactive.jj_queue = NULL;
2265 		sc->sc_active.jj_queue = NULL;
2266 
2267 		sc->sc_rootmount = root_mount_hold("GJOURNAL");
2268 		GJ_DEBUG(1, "root_mount_hold %p", sc->sc_rootmount);
2269 
2270 		callout_init(&sc->sc_callout, 1);
2271 		if (md->md_type != GJ_TYPE_COMPLETE) {
2272 			/*
2273 			 * Journal and data are on separate providers.
2274 			 * At this point we have only one of them.
2275 			 * We setup a timeout in case the other part will not
2276 			 * appear, so we won't wait forever.
2277 			 */
2278 			callout_reset(&sc->sc_callout, 5 * hz,
2279 			    g_journal_timeout, sc);
2280 		}
2281 	}
2282 
2283 	/* Remember type of the data provider. */
2284 	if (md->md_type & GJ_TYPE_DATA)
2285 		sc->sc_orig_type = md->md_type;
2286 	sc->sc_type |= md->md_type;
2287 	cp = NULL;
2288 
2289 	if (md->md_type & GJ_TYPE_DATA) {
2290 		if (md->md_flags & GJ_FLAG_CLEAN)
2291 			sc->sc_flags |= GJF_DEVICE_CLEAN;
2292 		if (md->md_flags & GJ_FLAG_CHECKSUM)
2293 			sc->sc_flags |= GJF_DEVICE_CHECKSUM;
2294 		cp = g_new_consumer(gp);
2295 		error = g_attach(cp, pp);
2296 		KASSERT(error == 0, ("Cannot attach to %s (error=%d).",
2297 		    pp->name, error));
2298 		error = g_access(cp, 1, 1, 1);
2299 		if (error != 0) {
2300 			GJ_DEBUG(0, "Cannot access %s (error=%d).", pp->name,
2301 			    error);
2302 			g_journal_destroy(sc);
2303 			return (NULL);
2304 		}
2305 		sc->sc_dconsumer = cp;
2306 		sc->sc_mediasize = pp->mediasize - pp->sectorsize;
2307 		sc->sc_sectorsize = pp->sectorsize;
2308 		sc->sc_jstart = md->md_jstart;
2309 		sc->sc_jend = md->md_jend;
2310 		if (md->md_provider[0] != '\0')
2311 			sc->sc_flags |= GJF_DEVICE_HARDCODED;
2312 		sc->sc_journal_offset = md->md_joffset;
2313 		sc->sc_journal_id = md->md_jid;
2314 		sc->sc_journal_previous_id = md->md_jid;
2315 	}
2316 	if (md->md_type & GJ_TYPE_JOURNAL) {
2317 		if (cp == NULL) {
2318 			cp = g_new_consumer(gp);
2319 			error = g_attach(cp, pp);
2320 			KASSERT(error == 0, ("Cannot attach to %s (error=%d).",
2321 			    pp->name, error));
2322 			error = g_access(cp, 1, 1, 1);
2323 			if (error != 0) {
2324 				GJ_DEBUG(0, "Cannot access %s (error=%d).",
2325 				    pp->name, error);
2326 				g_journal_destroy(sc);
2327 				return (NULL);
2328 			}
2329 		} else {
2330 			/*
2331 			 * Journal is on the same provider as data, which means
2332 			 * that data provider ends where journal starts.
2333 			 */
2334 			sc->sc_mediasize = md->md_jstart;
2335 		}
2336 		sc->sc_jconsumer = cp;
2337 	}
2338 
2339 	/* Start switcher kproc if needed. */
2340 	if (g_journal_switcher_proc == NULL)
2341 		g_journal_start_switcher(mp);
2342 
2343 	if ((sc->sc_type & GJ_TYPE_COMPLETE) != GJ_TYPE_COMPLETE) {
2344 		/* Journal is not complete yet. */
2345 		return (gp);
2346 	} else {
2347 		/* Journal complete, cancel timeout. */
2348 		callout_drain(&sc->sc_callout);
2349 	}
2350 
2351 	error = kproc_create(g_journal_worker, sc, &sc->sc_worker, 0, 0,
2352 	    "g_journal %s", sc->sc_name);
2353 	if (error != 0) {
2354 		GJ_DEBUG(0, "Cannot create worker thread for %s.journal.",
2355 		    sc->sc_name);
2356 		g_journal_destroy(sc);
2357 		return (NULL);
2358 	}
2359 
2360 	return (gp);
2361 }
2362 
2363 static void
2364 g_journal_destroy_consumer(void *arg, int flags __unused)
2365 {
2366 	struct g_consumer *cp;
2367 
2368 	g_topology_assert();
2369 	cp = arg;
2370 	g_detach(cp);
2371 	g_destroy_consumer(cp);
2372 }
2373 
2374 static int
2375 g_journal_destroy(struct g_journal_softc *sc)
2376 {
2377 	struct g_geom *gp;
2378 	struct g_provider *pp;
2379 	struct g_consumer *cp;
2380 
2381 	g_topology_assert();
2382 
2383 	if (sc == NULL)
2384 		return (ENXIO);
2385 
2386 	gp = sc->sc_geom;
2387 	pp = LIST_FIRST(&gp->provider);
2388 	if (pp != NULL) {
2389 		if (pp->acr != 0 || pp->acw != 0 || pp->ace != 0) {
2390 			GJ_DEBUG(1, "Device %s is still open (r%dw%de%d).",
2391 			    pp->name, pp->acr, pp->acw, pp->ace);
2392 			return (EBUSY);
2393 		}
2394 		g_error_provider(pp, ENXIO);
2395 
2396 		g_journal_flush(sc);
2397 		g_journal_flush_send(sc);
2398 		g_journal_switch(sc);
2399 	}
2400 
2401 	sc->sc_flags |= (GJF_DEVICE_DESTROY | GJF_DEVICE_CLEAN);
2402 
2403 	g_topology_unlock();
2404 
2405 	if (sc->sc_rootmount != NULL) {
2406 		GJ_DEBUG(1, "root_mount_rel %p", sc->sc_rootmount);
2407 		root_mount_rel(sc->sc_rootmount);
2408 		sc->sc_rootmount = NULL;
2409 	}
2410 
2411 	callout_drain(&sc->sc_callout);
2412 	mtx_lock(&sc->sc_mtx);
2413 	wakeup(sc);
2414 	while (sc->sc_worker != NULL)
2415 		msleep(&sc->sc_worker, &sc->sc_mtx, PRIBIO, "gj:destroy", 0);
2416 	mtx_unlock(&sc->sc_mtx);
2417 
2418 	if (pp != NULL) {
2419 		GJ_DEBUG(1, "Marking %s as clean.", sc->sc_name);
2420 		g_journal_metadata_update(sc);
2421 		g_topology_lock();
2422 		g_wither_provider(pp, ENXIO);
2423 	} else {
2424 		g_topology_lock();
2425 	}
2426 	mtx_destroy(&sc->sc_mtx);
2427 
2428 	if (sc->sc_current_count != 0) {
2429 		GJ_DEBUG(0, "Warning! Number of current requests %d.",
2430 		    sc->sc_current_count);
2431 	}
2432 
2433 	LIST_FOREACH(cp, &gp->consumer, consumer) {
2434 		if (cp->acr + cp->acw + cp->ace > 0)
2435 			g_access(cp, -1, -1, -1);
2436 		/*
2437 		 * We keep all consumers open for writting, so if I'll detach
2438 		 * and destroy consumer here, I'll get providers for taste, so
2439 		 * journal will be started again.
2440 		 * Sending an event here, prevents this from happening.
2441 		 */
2442 		g_post_event(g_journal_destroy_consumer, cp, M_WAITOK, NULL);
2443 	}
2444 	gp->softc = NULL;
2445 	g_wither_geom(gp, ENXIO);
2446 	free(sc, M_JOURNAL);
2447 	return (0);
2448 }
2449 
2450 static void
2451 g_journal_taste_orphan(struct g_consumer *cp)
2452 {
2453 
2454 	KASSERT(1 == 0, ("%s called while tasting %s.", __func__,
2455 	    cp->provider->name));
2456 }
2457 
2458 static struct g_geom *
2459 g_journal_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
2460 {
2461 	struct g_journal_metadata md;
2462 	struct g_consumer *cp;
2463 	struct g_geom *gp;
2464 	int error;
2465 
2466 	g_topology_assert();
2467 	g_trace(G_T_TOPOLOGY, "%s(%s, %s)", __func__, mp->name, pp->name);
2468 	GJ_DEBUG(2, "Tasting %s.", pp->name);
2469 	if (pp->geom->class == mp)
2470 		return (NULL);
2471 
2472 	gp = g_new_geomf(mp, "journal:taste");
2473 	/* This orphan function should be never called. */
2474 	gp->orphan = g_journal_taste_orphan;
2475 	cp = g_new_consumer(gp);
2476 	g_attach(cp, pp);
2477 	error = g_journal_metadata_read(cp, &md);
2478 	g_detach(cp);
2479 	g_destroy_consumer(cp);
2480 	g_destroy_geom(gp);
2481 	if (error != 0)
2482 		return (NULL);
2483 	gp = NULL;
2484 
2485 	if (md.md_provider[0] != '\0' &&
2486 	    !g_compare_names(md.md_provider, pp->name))
2487 		return (NULL);
2488 	if (md.md_provsize != 0 && md.md_provsize != pp->mediasize)
2489 		return (NULL);
2490 	if (g_journal_debug >= 2)
2491 		journal_metadata_dump(&md);
2492 
2493 	gp = g_journal_create(mp, pp, &md);
2494 	return (gp);
2495 }
2496 
2497 static struct g_journal_softc *
2498 g_journal_find_device(struct g_class *mp, const char *name)
2499 {
2500 	struct g_journal_softc *sc;
2501 	struct g_geom *gp;
2502 	struct g_provider *pp;
2503 
2504 	if (strncmp(name, "/dev/", 5) == 0)
2505 		name += 5;
2506 	LIST_FOREACH(gp, &mp->geom, geom) {
2507 		sc = gp->softc;
2508 		if (sc == NULL)
2509 			continue;
2510 		if (sc->sc_flags & GJF_DEVICE_DESTROY)
2511 			continue;
2512 		if ((sc->sc_type & GJ_TYPE_COMPLETE) != GJ_TYPE_COMPLETE)
2513 			continue;
2514 		pp = LIST_FIRST(&gp->provider);
2515 		if (strcmp(sc->sc_name, name) == 0)
2516 			return (sc);
2517 		if (pp != NULL && strcmp(pp->name, name) == 0)
2518 			return (sc);
2519 	}
2520 	return (NULL);
2521 }
2522 
2523 static void
2524 g_journal_ctl_destroy(struct gctl_req *req, struct g_class *mp)
2525 {
2526 	struct g_journal_softc *sc;
2527 	const char *name;
2528 	char param[16];
2529 	int *nargs;
2530 	int error, i;
2531 
2532 	g_topology_assert();
2533 
2534 	nargs = gctl_get_paraml(req, "nargs", sizeof(*nargs));
2535 	if (nargs == NULL) {
2536 		gctl_error(req, "No '%s' argument.", "nargs");
2537 		return;
2538 	}
2539 	if (*nargs <= 0) {
2540 		gctl_error(req, "Missing device(s).");
2541 		return;
2542 	}
2543 
2544 	for (i = 0; i < *nargs; i++) {
2545 		snprintf(param, sizeof(param), "arg%d", i);
2546 		name = gctl_get_asciiparam(req, param);
2547 		if (name == NULL) {
2548 			gctl_error(req, "No 'arg%d' argument.", i);
2549 			return;
2550 		}
2551 		sc = g_journal_find_device(mp, name);
2552 		if (sc == NULL) {
2553 			gctl_error(req, "No such device: %s.", name);
2554 			return;
2555 		}
2556 		error = g_journal_destroy(sc);
2557 		if (error != 0) {
2558 			gctl_error(req, "Cannot destroy device %s (error=%d).",
2559 			    LIST_FIRST(&sc->sc_geom->provider)->name, error);
2560 			return;
2561 		}
2562 	}
2563 }
2564 
2565 static void
2566 g_journal_ctl_sync(struct gctl_req *req __unused, struct g_class *mp __unused)
2567 {
2568 
2569 	g_topology_assert();
2570 	g_topology_unlock();
2571 	g_journal_sync_requested++;
2572 	wakeup(&g_journal_switcher_state);
2573 	while (g_journal_sync_requested > 0)
2574 		tsleep(&g_journal_sync_requested, PRIBIO, "j:sreq", hz / 2);
2575 	g_topology_lock();
2576 }
2577 
2578 static void
2579 g_journal_config(struct gctl_req *req, struct g_class *mp, const char *verb)
2580 {
2581 	uint32_t *version;
2582 
2583 	g_topology_assert();
2584 
2585 	version = gctl_get_paraml(req, "version", sizeof(*version));
2586 	if (version == NULL) {
2587 		gctl_error(req, "No '%s' argument.", "version");
2588 		return;
2589 	}
2590 	if (*version != G_JOURNAL_VERSION) {
2591 		gctl_error(req, "Userland and kernel parts are out of sync.");
2592 		return;
2593 	}
2594 
2595 	if (strcmp(verb, "destroy") == 0 || strcmp(verb, "stop") == 0) {
2596 		g_journal_ctl_destroy(req, mp);
2597 		return;
2598 	} else if (strcmp(verb, "sync") == 0) {
2599 		g_journal_ctl_sync(req, mp);
2600 		return;
2601 	}
2602 
2603 	gctl_error(req, "Unknown verb.");
2604 }
2605 
2606 static void
2607 g_journal_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
2608     struct g_consumer *cp, struct g_provider *pp)
2609 {
2610 	struct g_journal_softc *sc;
2611 
2612 	g_topology_assert();
2613 
2614 	sc = gp->softc;
2615 	if (sc == NULL)
2616 		return;
2617 	if (pp != NULL) {
2618 		/* Nothing here. */
2619 	} else if (cp != NULL) {
2620 		int first = 1;
2621 
2622 		sbuf_printf(sb, "%s<Role>", indent);
2623 		if (cp == sc->sc_dconsumer) {
2624 			sbuf_printf(sb, "Data");
2625 			first = 0;
2626 		}
2627 		if (cp == sc->sc_jconsumer) {
2628 			if (!first)
2629 				sbuf_printf(sb, ",");
2630 			sbuf_printf(sb, "Journal");
2631 		}
2632 		sbuf_printf(sb, "</Role>\n");
2633 		if (cp == sc->sc_jconsumer) {
2634 			sbuf_printf(sb, "<Jstart>%jd</Jstart>\n",
2635 			    (intmax_t)sc->sc_jstart);
2636 			sbuf_printf(sb, "<Jend>%jd</Jend>\n",
2637 			    (intmax_t)sc->sc_jend);
2638 		}
2639 	} else {
2640 		sbuf_printf(sb, "%s<ID>%u</ID>\n", indent, (u_int)sc->sc_id);
2641 	}
2642 }
2643 
2644 static eventhandler_tag g_journal_event_shutdown = NULL;
2645 static eventhandler_tag g_journal_event_lowmem = NULL;
2646 
2647 static void
2648 g_journal_shutdown(void *arg, int howto __unused)
2649 {
2650 	struct g_class *mp;
2651 	struct g_geom *gp, *gp2;
2652 
2653 	if (panicstr != NULL)
2654 		return;
2655 	mp = arg;
2656 	g_topology_lock();
2657 	LIST_FOREACH_SAFE(gp, &mp->geom, geom, gp2) {
2658 		if (gp->softc == NULL)
2659 			continue;
2660 		GJ_DEBUG(0, "Shutting down geom %s.", gp->name);
2661 		g_journal_destroy(gp->softc);
2662 	}
2663 	g_topology_unlock();
2664 }
2665 
2666 /*
2667  * Free cached requests from inactive queue in case of low memory.
2668  * We free GJ_FREE_AT_ONCE elements at once.
2669  */
2670 #define	GJ_FREE_AT_ONCE	4
2671 static void
2672 g_journal_lowmem(void *arg, int howto __unused)
2673 {
2674 	struct g_journal_softc *sc;
2675 	struct g_class *mp;
2676 	struct g_geom *gp;
2677 	struct bio *bp;
2678 	u_int nfree = GJ_FREE_AT_ONCE;
2679 
2680 	g_journal_stats_low_mem++;
2681 	mp = arg;
2682 	g_topology_lock();
2683 	LIST_FOREACH(gp, &mp->geom, geom) {
2684 		sc = gp->softc;
2685 		if (sc == NULL || (sc->sc_flags & GJF_DEVICE_DESTROY))
2686 			continue;
2687 		mtx_lock(&sc->sc_mtx);
2688 		for (bp = sc->sc_inactive.jj_queue; nfree > 0 && bp != NULL;
2689 		    nfree--, bp = bp->bio_next) {
2690 			/*
2691 			 * This is safe to free the bio_data, because:
2692 			 * 1. If bio_data is NULL it will be read from the
2693 			 *    inactive journal.
2694 			 * 2. If bp is sent down, it is first removed from the
2695 			 *    inactive queue, so it's impossible to free the
2696 			 *    data from under in-flight bio.
2697 			 * On the other hand, freeing elements from the active
2698 			 * queue, is not safe.
2699 			 */
2700 			if (bp->bio_data != NULL) {
2701 				GJ_DEBUG(2, "Freeing data from %s.",
2702 				    sc->sc_name);
2703 				gj_free(bp->bio_data, bp->bio_length);
2704 				bp->bio_data = NULL;
2705 			}
2706 		}
2707 		mtx_unlock(&sc->sc_mtx);
2708 		if (nfree == 0)
2709 			break;
2710 	}
2711 	g_topology_unlock();
2712 }
2713 
2714 static void g_journal_switcher(void *arg);
2715 
2716 static void
2717 g_journal_init(struct g_class *mp)
2718 {
2719 
2720 	/* Pick a conservative value if provided value sucks. */
2721 	if (g_journal_cache_divisor <= 0 ||
2722 	    (vm_kmem_size / g_journal_cache_divisor == 0)) {
2723 		g_journal_cache_divisor = 5;
2724 	}
2725 	if (g_journal_cache_limit > 0) {
2726 		g_journal_cache_limit = vm_kmem_size / g_journal_cache_divisor;
2727 		g_journal_cache_low =
2728 		    (g_journal_cache_limit / 100) * g_journal_cache_switch;
2729 	}
2730 	g_journal_event_shutdown = EVENTHANDLER_REGISTER(shutdown_post_sync,
2731 	    g_journal_shutdown, mp, EVENTHANDLER_PRI_FIRST);
2732 	if (g_journal_event_shutdown == NULL)
2733 		GJ_DEBUG(0, "Warning! Cannot register shutdown event.");
2734 	g_journal_event_lowmem = EVENTHANDLER_REGISTER(vm_lowmem,
2735 	    g_journal_lowmem, mp, EVENTHANDLER_PRI_FIRST);
2736 	if (g_journal_event_lowmem == NULL)
2737 		GJ_DEBUG(0, "Warning! Cannot register lowmem event.");
2738 }
2739 
2740 static void
2741 g_journal_fini(struct g_class *mp)
2742 {
2743 
2744 	if (g_journal_event_shutdown != NULL) {
2745 		EVENTHANDLER_DEREGISTER(shutdown_post_sync,
2746 		    g_journal_event_shutdown);
2747 	}
2748 	if (g_journal_event_lowmem != NULL)
2749 		EVENTHANDLER_DEREGISTER(vm_lowmem, g_journal_event_lowmem);
2750 	g_journal_stop_switcher();
2751 }
2752 
2753 DECLARE_GEOM_CLASS(g_journal_class, g_journal);
2754 
2755 static const struct g_journal_desc *
2756 g_journal_find_desc(const char *fstype)
2757 {
2758 	const struct g_journal_desc *desc;
2759 	int i;
2760 
2761 	for (desc = g_journal_filesystems[i = 0]; desc != NULL;
2762 	     desc = g_journal_filesystems[++i]) {
2763 		if (strcmp(desc->jd_fstype, fstype) == 0)
2764 			break;
2765 	}
2766 	return (desc);
2767 }
2768 
2769 static void
2770 g_journal_switch_wait(struct g_journal_softc *sc)
2771 {
2772 	struct bintime bt;
2773 
2774 	mtx_assert(&sc->sc_mtx, MA_OWNED);
2775 	if (g_journal_debug >= 2) {
2776 		if (sc->sc_flush_in_progress > 0) {
2777 			GJ_DEBUG(2, "%d requests flushing.",
2778 			    sc->sc_flush_in_progress);
2779 		}
2780 		if (sc->sc_copy_in_progress > 0) {
2781 			GJ_DEBUG(2, "%d requests copying.",
2782 			    sc->sc_copy_in_progress);
2783 		}
2784 		if (sc->sc_flush_count > 0) {
2785 			GJ_DEBUG(2, "%d requests to flush.",
2786 			    sc->sc_flush_count);
2787 		}
2788 		if (sc->sc_delayed_count > 0) {
2789 			GJ_DEBUG(2, "%d requests delayed.",
2790 			    sc->sc_delayed_count);
2791 		}
2792 	}
2793 	g_journal_stats_switches++;
2794 	if (sc->sc_copy_in_progress > 0)
2795 		g_journal_stats_wait_for_copy++;
2796 	GJ_TIMER_START(1, &bt);
2797 	sc->sc_flags &= ~GJF_DEVICE_BEFORE_SWITCH;
2798 	sc->sc_flags |= GJF_DEVICE_SWITCH;
2799 	wakeup(sc);
2800 	while (sc->sc_flags & GJF_DEVICE_SWITCH) {
2801 		msleep(&sc->sc_journal_copying, &sc->sc_mtx, PRIBIO,
2802 		    "gj:switch", 0);
2803 	}
2804 	GJ_TIMER_STOP(1, &bt, "Switch time of %s", sc->sc_name);
2805 }
2806 
2807 static void
2808 g_journal_do_switch(struct g_class *classp)
2809 {
2810 	struct g_journal_softc *sc;
2811 	const struct g_journal_desc *desc;
2812 	struct g_geom *gp;
2813 	struct mount *mp;
2814 	struct bintime bt;
2815 	char *mountpoint;
2816 	int error, save;
2817 
2818 	g_topology_lock();
2819 	LIST_FOREACH(gp, &classp->geom, geom) {
2820 		sc = gp->softc;
2821 		if (sc == NULL)
2822 			continue;
2823 		if (sc->sc_flags & GJF_DEVICE_DESTROY)
2824 			continue;
2825 		if ((sc->sc_type & GJ_TYPE_COMPLETE) != GJ_TYPE_COMPLETE)
2826 			continue;
2827 		mtx_lock(&sc->sc_mtx);
2828 		sc->sc_flags |= GJF_DEVICE_BEFORE_SWITCH;
2829 		mtx_unlock(&sc->sc_mtx);
2830 	}
2831 	g_topology_unlock();
2832 
2833 	mtx_lock(&mountlist_mtx);
2834 	TAILQ_FOREACH(mp, &mountlist, mnt_list) {
2835 		if (mp->mnt_gjprovider == NULL)
2836 			continue;
2837 		if (mp->mnt_flag & MNT_RDONLY)
2838 			continue;
2839 		desc = g_journal_find_desc(mp->mnt_stat.f_fstypename);
2840 		if (desc == NULL)
2841 			continue;
2842 		if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK))
2843 			continue;
2844 		/* mtx_unlock(&mountlist_mtx) was done inside vfs_busy() */
2845 
2846 		g_topology_lock();
2847 		sc = g_journal_find_device(classp, mp->mnt_gjprovider);
2848 		g_topology_unlock();
2849 
2850 		if (sc == NULL) {
2851 			GJ_DEBUG(0, "Cannot find journal geom for %s.",
2852 			    mp->mnt_gjprovider);
2853 			goto next;
2854 		} else if (JEMPTY(sc)) {
2855 			mtx_lock(&sc->sc_mtx);
2856 			sc->sc_flags &= ~GJF_DEVICE_BEFORE_SWITCH;
2857 			mtx_unlock(&sc->sc_mtx);
2858 			GJ_DEBUG(3, "No need for %s switch.", sc->sc_name);
2859 			goto next;
2860 		}
2861 
2862 		mountpoint = mp->mnt_stat.f_mntonname;
2863 
2864 		error = vn_start_write(NULL, &mp, V_WAIT);
2865 		if (error != 0) {
2866 			GJ_DEBUG(0, "vn_start_write(%s) failed (error=%d).",
2867 			    mountpoint, error);
2868 			goto next;
2869 		}
2870 
2871 		save = curthread_pflags_set(TDP_SYNCIO);
2872 
2873 		GJ_TIMER_START(1, &bt);
2874 		vfs_msync(mp, MNT_NOWAIT);
2875 		GJ_TIMER_STOP(1, &bt, "Msync time of %s", mountpoint);
2876 
2877 		GJ_TIMER_START(1, &bt);
2878 		error = VFS_SYNC(mp, MNT_NOWAIT);
2879 		if (error == 0)
2880 			GJ_TIMER_STOP(1, &bt, "Sync time of %s", mountpoint);
2881 		else {
2882 			GJ_DEBUG(0, "Cannot sync file system %s (error=%d).",
2883 			    mountpoint, error);
2884 		}
2885 
2886 		curthread_pflags_restore(save);
2887 
2888 		vn_finished_write(mp);
2889 
2890 		if (error != 0)
2891 			goto next;
2892 
2893 		/*
2894 		 * Send BIO_FLUSH before freezing the file system, so it can be
2895 		 * faster after the freeze.
2896 		 */
2897 		GJ_TIMER_START(1, &bt);
2898 		g_journal_flush_cache(sc);
2899 		GJ_TIMER_STOP(1, &bt, "BIO_FLUSH time of %s", sc->sc_name);
2900 
2901 		GJ_TIMER_START(1, &bt);
2902 		error = vfs_write_suspend(mp, VS_SKIP_UNMOUNT);
2903 		GJ_TIMER_STOP(1, &bt, "Suspend time of %s", mountpoint);
2904 		if (error != 0) {
2905 			GJ_DEBUG(0, "Cannot suspend file system %s (error=%d).",
2906 			    mountpoint, error);
2907 			goto next;
2908 		}
2909 
2910 		error = desc->jd_clean(mp);
2911 		if (error != 0)
2912 			goto next;
2913 
2914 		mtx_lock(&sc->sc_mtx);
2915 		g_journal_switch_wait(sc);
2916 		mtx_unlock(&sc->sc_mtx);
2917 
2918 		vfs_write_resume(mp, 0);
2919 next:
2920 		mtx_lock(&mountlist_mtx);
2921 		vfs_unbusy(mp);
2922 	}
2923 	mtx_unlock(&mountlist_mtx);
2924 
2925 	sc = NULL;
2926 	for (;;) {
2927 		g_topology_lock();
2928 		LIST_FOREACH(gp, &g_journal_class.geom, geom) {
2929 			sc = gp->softc;
2930 			if (sc == NULL)
2931 				continue;
2932 			mtx_lock(&sc->sc_mtx);
2933 			if ((sc->sc_type & GJ_TYPE_COMPLETE) == GJ_TYPE_COMPLETE &&
2934 			    !(sc->sc_flags & GJF_DEVICE_DESTROY) &&
2935 			    (sc->sc_flags & GJF_DEVICE_BEFORE_SWITCH)) {
2936 				break;
2937 			}
2938 			mtx_unlock(&sc->sc_mtx);
2939 			sc = NULL;
2940 		}
2941 		g_topology_unlock();
2942 		if (sc == NULL)
2943 			break;
2944 		mtx_assert(&sc->sc_mtx, MA_OWNED);
2945 		g_journal_switch_wait(sc);
2946 		mtx_unlock(&sc->sc_mtx);
2947 	}
2948 }
2949 
2950 static void
2951 g_journal_start_switcher(struct g_class *mp)
2952 {
2953 	int error;
2954 
2955 	g_topology_assert();
2956 	MPASS(g_journal_switcher_proc == NULL);
2957 	g_journal_switcher_state = GJ_SWITCHER_WORKING;
2958 	error = kproc_create(g_journal_switcher, mp, &g_journal_switcher_proc,
2959 	    0, 0, "g_journal switcher");
2960 	KASSERT(error == 0, ("Cannot create switcher thread."));
2961 }
2962 
2963 static void
2964 g_journal_stop_switcher(void)
2965 {
2966 	g_topology_assert();
2967 	MPASS(g_journal_switcher_proc != NULL);
2968 	g_journal_switcher_state = GJ_SWITCHER_DIE;
2969 	wakeup(&g_journal_switcher_state);
2970 	while (g_journal_switcher_state != GJ_SWITCHER_DIED)
2971 		tsleep(&g_journal_switcher_state, PRIBIO, "jfini:wait", hz / 5);
2972 	GJ_DEBUG(1, "Switcher died.");
2973 	g_journal_switcher_proc = NULL;
2974 }
2975 
2976 /*
2977  * TODO: Kill switcher thread on last geom destruction?
2978  */
2979 static void
2980 g_journal_switcher(void *arg)
2981 {
2982 	struct g_class *mp;
2983 	struct bintime bt;
2984 	int error;
2985 
2986 	mp = arg;
2987 	curthread->td_pflags |= TDP_NORUNNINGBUF;
2988 	for (;;) {
2989 		g_journal_switcher_wokenup = 0;
2990 		error = tsleep(&g_journal_switcher_state, PRIBIO, "jsw:wait",
2991 		    g_journal_switch_time * hz);
2992 		if (g_journal_switcher_state == GJ_SWITCHER_DIE) {
2993 			g_journal_switcher_state = GJ_SWITCHER_DIED;
2994 			GJ_DEBUG(1, "Switcher exiting.");
2995 			wakeup(&g_journal_switcher_state);
2996 			kproc_exit(0);
2997 		}
2998 		if (error == 0 && g_journal_sync_requested == 0) {
2999 			GJ_DEBUG(1, "Out of cache, force switch (used=%jd "
3000 			    "limit=%jd).", (intmax_t)g_journal_cache_used,
3001 			    (intmax_t)g_journal_cache_limit);
3002 		}
3003 		GJ_TIMER_START(1, &bt);
3004 		g_journal_do_switch(mp);
3005 		GJ_TIMER_STOP(1, &bt, "Entire switch time");
3006 		if (g_journal_sync_requested > 0) {
3007 			g_journal_sync_requested = 0;
3008 			wakeup(&g_journal_sync_requested);
3009 		}
3010 	}
3011 }
3012