space_map.c revision a234c3c9d43545879dbc055e14b73c147cc93aff
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
23 * Use is subject to license terms.
24 */
25
26#include <sys/zfs_context.h>
27#include <sys/spa.h>
28#include <sys/dmu.h>
29#include <sys/zio.h>
30#include <sys/space_map.h>
31
32/*
33 * Space map routines.
34 * NOTE: caller is responsible for all locking.
35 */
36static int
37space_map_seg_compare(const void *x1, const void *x2)
38{
39	const space_seg_t *s1 = x1;
40	const space_seg_t *s2 = x2;
41
42	if (s1->ss_start < s2->ss_start) {
43		if (s1->ss_end > s2->ss_start)
44			return (0);
45		return (-1);
46	}
47	if (s1->ss_start > s2->ss_start) {
48		if (s1->ss_start < s2->ss_end)
49			return (0);
50		return (1);
51	}
52	return (0);
53}
54
55void
56space_map_create(space_map_t *sm, uint64_t start, uint64_t size, uint8_t shift,
57	kmutex_t *lp)
58{
59	bzero(sm, sizeof (*sm));
60
61	cv_init(&sm->sm_load_cv, NULL, CV_DEFAULT, NULL);
62
63	avl_create(&sm->sm_root, space_map_seg_compare,
64	    sizeof (space_seg_t), offsetof(struct space_seg, ss_node));
65
66	sm->sm_start = start;
67	sm->sm_size = size;
68	sm->sm_shift = shift;
69	sm->sm_lock = lp;
70}
71
72void
73space_map_destroy(space_map_t *sm)
74{
75	ASSERT(!sm->sm_loaded && !sm->sm_loading);
76	VERIFY3U(sm->sm_space, ==, 0);
77	avl_destroy(&sm->sm_root);
78	cv_destroy(&sm->sm_load_cv);
79}
80
81void
82space_map_add(space_map_t *sm, uint64_t start, uint64_t size)
83{
84	avl_index_t where;
85	space_seg_t ssearch, *ss_before, *ss_after, *ss;
86	uint64_t end = start + size;
87	int merge_before, merge_after;
88
89	ASSERT(MUTEX_HELD(sm->sm_lock));
90	VERIFY(size != 0);
91	VERIFY3U(start, >=, sm->sm_start);
92	VERIFY3U(end, <=, sm->sm_start + sm->sm_size);
93	VERIFY(sm->sm_space + size <= sm->sm_size);
94	VERIFY(P2PHASE(start, 1ULL << sm->sm_shift) == 0);
95	VERIFY(P2PHASE(size, 1ULL << sm->sm_shift) == 0);
96
97	ssearch.ss_start = start;
98	ssearch.ss_end = end;
99	ss = avl_find(&sm->sm_root, &ssearch, &where);
100
101	if (ss != NULL && ss->ss_start <= start && ss->ss_end >= end) {
102		zfs_panic_recover("zfs: allocating allocated segment"
103		    "(offset=%llu size=%llu)\n",
104		    (longlong_t)start, (longlong_t)size);
105		return;
106	}
107
108	/* Make sure we don't overlap with either of our neighbors */
109	VERIFY(ss == NULL);
110
111	ss_before = avl_nearest(&sm->sm_root, where, AVL_BEFORE);
112	ss_after = avl_nearest(&sm->sm_root, where, AVL_AFTER);
113
114	merge_before = (ss_before != NULL && ss_before->ss_end == start);
115	merge_after = (ss_after != NULL && ss_after->ss_start == end);
116
117	if (merge_before && merge_after) {
118		avl_remove(&sm->sm_root, ss_before);
119		if (sm->sm_pp_root) {
120			avl_remove(sm->sm_pp_root, ss_before);
121			avl_remove(sm->sm_pp_root, ss_after);
122		}
123		ss_after->ss_start = ss_before->ss_start;
124		kmem_free(ss_before, sizeof (*ss_before));
125		ss = ss_after;
126	} else if (merge_before) {
127		ss_before->ss_end = end;
128		if (sm->sm_pp_root)
129			avl_remove(sm->sm_pp_root, ss_before);
130		ss = ss_before;
131	} else if (merge_after) {
132		ss_after->ss_start = start;
133		if (sm->sm_pp_root)
134			avl_remove(sm->sm_pp_root, ss_after);
135		ss = ss_after;
136	} else {
137		ss = kmem_alloc(sizeof (*ss), KM_SLEEP);
138		ss->ss_start = start;
139		ss->ss_end = end;
140		avl_insert(&sm->sm_root, ss, where);
141	}
142
143	if (sm->sm_pp_root)
144		avl_add(sm->sm_pp_root, ss);
145
146	sm->sm_space += size;
147}
148
149void
150space_map_remove(space_map_t *sm, uint64_t start, uint64_t size)
151{
152	avl_index_t where;
153	space_seg_t ssearch, *ss, *newseg;
154	uint64_t end = start + size;
155	int left_over, right_over;
156
157	ASSERT(MUTEX_HELD(sm->sm_lock));
158	VERIFY(size != 0);
159	VERIFY(P2PHASE(start, 1ULL << sm->sm_shift) == 0);
160	VERIFY(P2PHASE(size, 1ULL << sm->sm_shift) == 0);
161
162	ssearch.ss_start = start;
163	ssearch.ss_end = end;
164	ss = avl_find(&sm->sm_root, &ssearch, &where);
165
166	/* Make sure we completely overlap with someone */
167	if (ss == NULL) {
168		zfs_panic_recover("zfs: freeing free segment "
169		    "(offset=%llu size=%llu)",
170		    (longlong_t)start, (longlong_t)size);
171		return;
172	}
173	VERIFY3U(ss->ss_start, <=, start);
174	VERIFY3U(ss->ss_end, >=, end);
175	VERIFY(sm->sm_space - size <= sm->sm_size);
176
177	left_over = (ss->ss_start != start);
178	right_over = (ss->ss_end != end);
179
180	if (sm->sm_pp_root)
181		avl_remove(sm->sm_pp_root, ss);
182
183	if (left_over && right_over) {
184		newseg = kmem_alloc(sizeof (*newseg), KM_SLEEP);
185		newseg->ss_start = end;
186		newseg->ss_end = ss->ss_end;
187		ss->ss_end = start;
188		avl_insert_here(&sm->sm_root, newseg, ss, AVL_AFTER);
189		if (sm->sm_pp_root)
190			avl_add(sm->sm_pp_root, newseg);
191	} else if (left_over) {
192		ss->ss_end = start;
193	} else if (right_over) {
194		ss->ss_start = end;
195	} else {
196		avl_remove(&sm->sm_root, ss);
197		kmem_free(ss, sizeof (*ss));
198		ss = NULL;
199	}
200
201	if (sm->sm_pp_root && ss != NULL)
202		avl_add(sm->sm_pp_root, ss);
203
204	sm->sm_space -= size;
205}
206
207boolean_t
208space_map_contains(space_map_t *sm, uint64_t start, uint64_t size)
209{
210	avl_index_t where;
211	space_seg_t ssearch, *ss;
212	uint64_t end = start + size;
213
214	ASSERT(MUTEX_HELD(sm->sm_lock));
215	VERIFY(size != 0);
216	VERIFY(P2PHASE(start, 1ULL << sm->sm_shift) == 0);
217	VERIFY(P2PHASE(size, 1ULL << sm->sm_shift) == 0);
218
219	ssearch.ss_start = start;
220	ssearch.ss_end = end;
221	ss = avl_find(&sm->sm_root, &ssearch, &where);
222
223	return (ss != NULL && ss->ss_start <= start && ss->ss_end >= end);
224}
225
226void
227space_map_vacate(space_map_t *sm, space_map_func_t *func, space_map_t *mdest)
228{
229	space_seg_t *ss;
230	void *cookie = NULL;
231
232	ASSERT(MUTEX_HELD(sm->sm_lock));
233
234	while ((ss = avl_destroy_nodes(&sm->sm_root, &cookie)) != NULL) {
235		if (func != NULL)
236			func(mdest, ss->ss_start, ss->ss_end - ss->ss_start);
237		kmem_free(ss, sizeof (*ss));
238	}
239	sm->sm_space = 0;
240}
241
242void
243space_map_walk(space_map_t *sm, space_map_func_t *func, space_map_t *mdest)
244{
245	space_seg_t *ss;
246
247	ASSERT(MUTEX_HELD(sm->sm_lock));
248
249	for (ss = avl_first(&sm->sm_root); ss; ss = AVL_NEXT(&sm->sm_root, ss))
250		func(mdest, ss->ss_start, ss->ss_end - ss->ss_start);
251}
252
253/*
254 * Wait for any in-progress space_map_load() to complete.
255 */
256void
257space_map_load_wait(space_map_t *sm)
258{
259	ASSERT(MUTEX_HELD(sm->sm_lock));
260
261	while (sm->sm_loading)
262		cv_wait(&sm->sm_load_cv, sm->sm_lock);
263}
264
265/*
266 * Note: space_map_load() will drop sm_lock across dmu_read() calls.
267 * The caller must be OK with this.
268 */
269int
270space_map_load(space_map_t *sm, space_map_ops_t *ops, uint8_t maptype,
271	space_map_obj_t *smo, objset_t *os)
272{
273	uint64_t *entry, *entry_map, *entry_map_end;
274	uint64_t bufsize, size, offset, end, space;
275	uint64_t mapstart = sm->sm_start;
276	int error = 0;
277
278	ASSERT(MUTEX_HELD(sm->sm_lock));
279
280	space_map_load_wait(sm);
281
282	if (sm->sm_loaded)
283		return (0);
284
285	sm->sm_loading = B_TRUE;
286	end = smo->smo_objsize;
287	space = smo->smo_alloc;
288
289	ASSERT(sm->sm_ops == NULL);
290	VERIFY3U(sm->sm_space, ==, 0);
291
292	if (maptype == SM_FREE) {
293		space_map_add(sm, sm->sm_start, sm->sm_size);
294		space = sm->sm_size - space;
295	}
296
297	bufsize = 1ULL << SPACE_MAP_BLOCKSHIFT;
298	entry_map = zio_buf_alloc(bufsize);
299
300	mutex_exit(sm->sm_lock);
301	if (end > bufsize)
302		dmu_prefetch(os, smo->smo_object, bufsize, end - bufsize);
303	mutex_enter(sm->sm_lock);
304
305	for (offset = 0; offset < end; offset += bufsize) {
306		size = MIN(end - offset, bufsize);
307		VERIFY(P2PHASE(size, sizeof (uint64_t)) == 0);
308		VERIFY(size != 0);
309
310		dprintf("object=%llu  offset=%llx  size=%llx\n",
311		    smo->smo_object, offset, size);
312
313		mutex_exit(sm->sm_lock);
314		error = dmu_read(os, smo->smo_object, offset, size, entry_map,
315		    DMU_READ_PREFETCH);
316		mutex_enter(sm->sm_lock);
317		if (error != 0)
318			break;
319
320		entry_map_end = entry_map + (size / sizeof (uint64_t));
321		for (entry = entry_map; entry < entry_map_end; entry++) {
322			uint64_t e = *entry;
323
324			if (SM_DEBUG_DECODE(e))		/* Skip debug entries */
325				continue;
326
327			(SM_TYPE_DECODE(e) == maptype ?
328			    space_map_add : space_map_remove)(sm,
329			    (SM_OFFSET_DECODE(e) << sm->sm_shift) + mapstart,
330			    SM_RUN_DECODE(e) << sm->sm_shift);
331		}
332	}
333
334	if (error == 0) {
335		VERIFY3U(sm->sm_space, ==, space);
336
337		sm->sm_loaded = B_TRUE;
338		sm->sm_ops = ops;
339		if (ops != NULL)
340			ops->smop_load(sm);
341	} else {
342		space_map_vacate(sm, NULL, NULL);
343	}
344
345	zio_buf_free(entry_map, bufsize);
346
347	sm->sm_loading = B_FALSE;
348
349	cv_broadcast(&sm->sm_load_cv);
350
351	return (error);
352}
353
354void
355space_map_unload(space_map_t *sm)
356{
357	ASSERT(MUTEX_HELD(sm->sm_lock));
358
359	if (sm->sm_loaded && sm->sm_ops != NULL)
360		sm->sm_ops->smop_unload(sm);
361
362	sm->sm_loaded = B_FALSE;
363	sm->sm_ops = NULL;
364
365	space_map_vacate(sm, NULL, NULL);
366}
367
368uint64_t
369space_map_maxsize(space_map_t *sm)
370{
371	if (sm->sm_loaded && sm->sm_ops != NULL)
372		return (sm->sm_ops->smop_max(sm));
373	else
374		return (-1ULL);
375}
376
377uint64_t
378space_map_alloc(space_map_t *sm, uint64_t size)
379{
380	uint64_t start;
381
382	start = sm->sm_ops->smop_alloc(sm, size);
383	if (start != -1ULL)
384		space_map_remove(sm, start, size);
385	return (start);
386}
387
388void
389space_map_claim(space_map_t *sm, uint64_t start, uint64_t size)
390{
391	sm->sm_ops->smop_claim(sm, start, size);
392	space_map_remove(sm, start, size);
393}
394
395void
396space_map_free(space_map_t *sm, uint64_t start, uint64_t size)
397{
398	space_map_add(sm, start, size);
399	sm->sm_ops->smop_free(sm, start, size);
400}
401
402/*
403 * Note: space_map_sync() will drop sm_lock across dmu_write() calls.
404 */
405void
406space_map_sync(space_map_t *sm, uint8_t maptype,
407	space_map_obj_t *smo, objset_t *os, dmu_tx_t *tx)
408{
409	spa_t *spa = dmu_objset_spa(os);
410	void *cookie = NULL;
411	space_seg_t *ss;
412	uint64_t bufsize, start, size, run_len;
413	uint64_t *entry, *entry_map, *entry_map_end;
414
415	ASSERT(MUTEX_HELD(sm->sm_lock));
416
417	if (sm->sm_space == 0)
418		return;
419
420	dprintf("object %4llu, txg %llu, pass %d, %c, count %lu, space %llx\n",
421	    smo->smo_object, dmu_tx_get_txg(tx), spa_sync_pass(spa),
422	    maptype == SM_ALLOC ? 'A' : 'F', avl_numnodes(&sm->sm_root),
423	    sm->sm_space);
424
425	if (maptype == SM_ALLOC)
426		smo->smo_alloc += sm->sm_space;
427	else
428		smo->smo_alloc -= sm->sm_space;
429
430	bufsize = (8 + avl_numnodes(&sm->sm_root)) * sizeof (uint64_t);
431	bufsize = MIN(bufsize, 1ULL << SPACE_MAP_BLOCKSHIFT);
432	entry_map = zio_buf_alloc(bufsize);
433	entry_map_end = entry_map + (bufsize / sizeof (uint64_t));
434	entry = entry_map;
435
436	*entry++ = SM_DEBUG_ENCODE(1) |
437	    SM_DEBUG_ACTION_ENCODE(maptype) |
438	    SM_DEBUG_SYNCPASS_ENCODE(spa_sync_pass(spa)) |
439	    SM_DEBUG_TXG_ENCODE(dmu_tx_get_txg(tx));
440
441	while ((ss = avl_destroy_nodes(&sm->sm_root, &cookie)) != NULL) {
442		size = ss->ss_end - ss->ss_start;
443		start = (ss->ss_start - sm->sm_start) >> sm->sm_shift;
444
445		sm->sm_space -= size;
446		size >>= sm->sm_shift;
447
448		while (size) {
449			run_len = MIN(size, SM_RUN_MAX);
450
451			if (entry == entry_map_end) {
452				mutex_exit(sm->sm_lock);
453				dmu_write(os, smo->smo_object, smo->smo_objsize,
454				    bufsize, entry_map, tx);
455				mutex_enter(sm->sm_lock);
456				smo->smo_objsize += bufsize;
457				entry = entry_map;
458			}
459
460			*entry++ = SM_OFFSET_ENCODE(start) |
461			    SM_TYPE_ENCODE(maptype) |
462			    SM_RUN_ENCODE(run_len);
463
464			start += run_len;
465			size -= run_len;
466		}
467		kmem_free(ss, sizeof (*ss));
468	}
469
470	if (entry != entry_map) {
471		size = (entry - entry_map) * sizeof (uint64_t);
472		mutex_exit(sm->sm_lock);
473		dmu_write(os, smo->smo_object, smo->smo_objsize,
474		    size, entry_map, tx);
475		mutex_enter(sm->sm_lock);
476		smo->smo_objsize += size;
477	}
478
479	zio_buf_free(entry_map, bufsize);
480
481	VERIFY3U(sm->sm_space, ==, 0);
482}
483
484void
485space_map_truncate(space_map_obj_t *smo, objset_t *os, dmu_tx_t *tx)
486{
487	VERIFY(dmu_free_range(os, smo->smo_object, 0, -1ULL, tx) == 0);
488
489	smo->smo_objsize = 0;
490	smo->smo_alloc = 0;
491}
492
493/*
494 * Space map reference trees.
495 *
496 * A space map is a collection of integers.  Every integer is either
497 * in the map, or it's not.  A space map reference tree generalizes
498 * the idea: it allows its members to have arbitrary reference counts,
499 * as opposed to the implicit reference count of 0 or 1 in a space map.
500 * This representation comes in handy when computing the union or
501 * intersection of multiple space maps.  For example, the union of
502 * N space maps is the subset of the reference tree with refcnt >= 1.
503 * The intersection of N space maps is the subset with refcnt >= N.
504 *
505 * [It's very much like a Fourier transform.  Unions and intersections
506 * are hard to perform in the 'space map domain', so we convert the maps
507 * into the 'reference count domain', where it's trivial, then invert.]
508 *
509 * vdev_dtl_reassess() uses computations of this form to determine
510 * DTL_MISSING and DTL_OUTAGE for interior vdevs -- e.g. a RAID-Z vdev
511 * has an outage wherever refcnt >= vdev_nparity + 1, and a mirror vdev
512 * has an outage wherever refcnt >= vdev_children.
513 */
514static int
515space_map_ref_compare(const void *x1, const void *x2)
516{
517	const space_ref_t *sr1 = x1;
518	const space_ref_t *sr2 = x2;
519
520	if (sr1->sr_offset < sr2->sr_offset)
521		return (-1);
522	if (sr1->sr_offset > sr2->sr_offset)
523		return (1);
524
525	if (sr1 < sr2)
526		return (-1);
527	if (sr1 > sr2)
528		return (1);
529
530	return (0);
531}
532
533void
534space_map_ref_create(avl_tree_t *t)
535{
536	avl_create(t, space_map_ref_compare,
537	    sizeof (space_ref_t), offsetof(space_ref_t, sr_node));
538}
539
540void
541space_map_ref_destroy(avl_tree_t *t)
542{
543	space_ref_t *sr;
544	void *cookie = NULL;
545
546	while ((sr = avl_destroy_nodes(t, &cookie)) != NULL)
547		kmem_free(sr, sizeof (*sr));
548
549	avl_destroy(t);
550}
551
552static void
553space_map_ref_add_node(avl_tree_t *t, uint64_t offset, int64_t refcnt)
554{
555	space_ref_t *sr;
556
557	sr = kmem_alloc(sizeof (*sr), KM_SLEEP);
558	sr->sr_offset = offset;
559	sr->sr_refcnt = refcnt;
560
561	avl_add(t, sr);
562}
563
564void
565space_map_ref_add_seg(avl_tree_t *t, uint64_t start, uint64_t end,
566	int64_t refcnt)
567{
568	space_map_ref_add_node(t, start, refcnt);
569	space_map_ref_add_node(t, end, -refcnt);
570}
571
572/*
573 * Convert (or add) a space map into a reference tree.
574 */
575void
576space_map_ref_add_map(avl_tree_t *t, space_map_t *sm, int64_t refcnt)
577{
578	space_seg_t *ss;
579
580	ASSERT(MUTEX_HELD(sm->sm_lock));
581
582	for (ss = avl_first(&sm->sm_root); ss; ss = AVL_NEXT(&sm->sm_root, ss))
583		space_map_ref_add_seg(t, ss->ss_start, ss->ss_end, refcnt);
584}
585
586/*
587 * Convert a reference tree into a space map.  The space map will contain
588 * all members of the reference tree for which refcnt >= minref.
589 */
590void
591space_map_ref_generate_map(avl_tree_t *t, space_map_t *sm, int64_t minref)
592{
593	uint64_t start = -1ULL;
594	int64_t refcnt = 0;
595	space_ref_t *sr;
596
597	ASSERT(MUTEX_HELD(sm->sm_lock));
598
599	space_map_vacate(sm, NULL, NULL);
600
601	for (sr = avl_first(t); sr != NULL; sr = AVL_NEXT(t, sr)) {
602		refcnt += sr->sr_refcnt;
603		if (refcnt >= minref) {
604			if (start == -1ULL) {
605				start = sr->sr_offset;
606			}
607		} else {
608			if (start != -1ULL) {
609				uint64_t end = sr->sr_offset;
610				ASSERT(start <= end);
611				if (end > start)
612					space_map_add(sm, start, end - start);
613				start = -1ULL;
614			}
615		}
616	}
617	ASSERT(refcnt == 0);
618	ASSERT(start == -1ULL);
619}
620