xref: /trueos/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_traverse.c (revision 5868f7205430cd67aa3b655419d3f15f83b70119)
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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23  * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
24  * Copyright (c) 2015 Chunwei Chen. All rights reserved.
25  */
26 
27 #include <sys/zfs_context.h>
28 #include <sys/dmu_objset.h>
29 #include <sys/dmu_traverse.h>
30 #include <sys/dsl_dataset.h>
31 #include <sys/dsl_dir.h>
32 #include <sys/dsl_pool.h>
33 #include <sys/dnode.h>
34 #include <sys/spa.h>
35 #include <sys/zio.h>
36 #include <sys/dmu_impl.h>
37 #include <sys/sa.h>
38 #include <sys/sa_impl.h>
39 #include <sys/callb.h>
40 #include <sys/zfeature.h>
41 
42 int zfs_pd_blks_max = 100;
43 
44 typedef struct prefetch_data {
45 	kmutex_t pd_mtx;
46 	kcondvar_t pd_cv;
47 	int pd_blks_max;
48 	int pd_blks_fetched;
49 	int pd_flags;
50 	boolean_t pd_cancel;
51 	boolean_t pd_exited;
52 } prefetch_data_t;
53 
54 typedef struct traverse_data {
55 	spa_t *td_spa;
56 	uint64_t td_objset;
57 	blkptr_t *td_rootbp;
58 	uint64_t td_min_txg;
59 	zbookmark_phys_t *td_resume;
60 	int td_flags;
61 	prefetch_data_t *td_pfd;
62 	boolean_t td_paused;
63 	uint64_t td_hole_birth_enabled_txg;
64 	blkptr_cb_t *td_func;
65 	void *td_arg;
66 } traverse_data_t;
67 
68 static int traverse_dnode(traverse_data_t *td, const dnode_phys_t *dnp,
69     uint64_t objset, uint64_t object);
70 static void prefetch_dnode_metadata(traverse_data_t *td, const dnode_phys_t *,
71     uint64_t objset, uint64_t object);
72 
73 static int
traverse_zil_block(zilog_t * zilog,blkptr_t * bp,void * arg,uint64_t claim_txg)74 traverse_zil_block(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg)
75 {
76 	traverse_data_t *td = arg;
77 	zbookmark_phys_t zb;
78 
79 	if (BP_IS_HOLE(bp))
80 		return (0);
81 
82 	if (claim_txg == 0 && bp->blk_birth >= spa_first_txg(td->td_spa))
83 		return (0);
84 
85 	SET_BOOKMARK(&zb, td->td_objset, ZB_ZIL_OBJECT, ZB_ZIL_LEVEL,
86 	    bp->blk_cksum.zc_word[ZIL_ZC_SEQ]);
87 
88 	(void) td->td_func(td->td_spa, zilog, bp, &zb, NULL, td->td_arg);
89 
90 	return (0);
91 }
92 
93 static int
traverse_zil_record(zilog_t * zilog,lr_t * lrc,void * arg,uint64_t claim_txg)94 traverse_zil_record(zilog_t *zilog, lr_t *lrc, void *arg, uint64_t claim_txg)
95 {
96 	traverse_data_t *td = arg;
97 
98 	if (lrc->lrc_txtype == TX_WRITE) {
99 		lr_write_t *lr = (lr_write_t *)lrc;
100 		blkptr_t *bp = &lr->lr_blkptr;
101 		zbookmark_phys_t zb;
102 
103 		if (BP_IS_HOLE(bp))
104 			return (0);
105 
106 		if (claim_txg == 0 || bp->blk_birth < claim_txg)
107 			return (0);
108 
109 		SET_BOOKMARK(&zb, td->td_objset, lr->lr_foid,
110 		    ZB_ZIL_LEVEL, lr->lr_offset / BP_GET_LSIZE(bp));
111 
112 		(void) td->td_func(td->td_spa, zilog, bp, &zb, NULL,
113 		    td->td_arg);
114 	}
115 	return (0);
116 }
117 
118 static void
traverse_zil(traverse_data_t * td,zil_header_t * zh)119 traverse_zil(traverse_data_t *td, zil_header_t *zh)
120 {
121 	uint64_t claim_txg = zh->zh_claim_txg;
122 	zilog_t *zilog;
123 
124 	/*
125 	 * We only want to visit blocks that have been claimed but not yet
126 	 * replayed; plus, in read-only mode, blocks that are already stable.
127 	 */
128 	if (claim_txg == 0 && spa_writeable(td->td_spa))
129 		return;
130 
131 	zilog = zil_alloc(spa_get_dsl(td->td_spa)->dp_meta_objset, zh);
132 
133 	(void) zil_parse(zilog, traverse_zil_block, traverse_zil_record, td,
134 	    claim_txg);
135 
136 	zil_free(zilog);
137 }
138 
139 typedef enum resume_skip {
140 	RESUME_SKIP_ALL,
141 	RESUME_SKIP_NONE,
142 	RESUME_SKIP_CHILDREN
143 } resume_skip_t;
144 
145 /*
146  * Returns RESUME_SKIP_ALL if td indicates that we are resuming a traversal and
147  * the block indicated by zb does not need to be visited at all. Returns
148  * RESUME_SKIP_CHILDREN if we are resuming a post traversal and we reach the
149  * resume point. This indicates that this block should be visited but not its
150  * children (since they must have been visited in a previous traversal).
151  * Otherwise returns RESUME_SKIP_NONE.
152  */
153 static resume_skip_t
resume_skip_check(traverse_data_t * td,const dnode_phys_t * dnp,const zbookmark_phys_t * zb)154 resume_skip_check(traverse_data_t *td, const dnode_phys_t *dnp,
155     const zbookmark_phys_t *zb)
156 {
157 	if (td->td_resume != NULL && !ZB_IS_ZERO(td->td_resume)) {
158 		/*
159 		 * If we already visited this bp & everything below,
160 		 * don't bother doing it again.
161 		 */
162 		if (zbookmark_is_before(dnp, zb, td->td_resume))
163 			return (RESUME_SKIP_ALL);
164 
165 		/*
166 		 * If we found the block we're trying to resume from, zero
167 		 * the bookmark out to indicate that we have resumed.
168 		 */
169 		if (bcmp(zb, td->td_resume, sizeof (*zb)) == 0) {
170 			bzero(td->td_resume, sizeof (*zb));
171 			if (td->td_flags & TRAVERSE_POST)
172 				return (RESUME_SKIP_CHILDREN);
173 		}
174 	}
175 	return (RESUME_SKIP_NONE);
176 }
177 
178 static void
traverse_prefetch_metadata(traverse_data_t * td,const blkptr_t * bp,const zbookmark_phys_t * zb)179 traverse_prefetch_metadata(traverse_data_t *td,
180     const blkptr_t *bp, const zbookmark_phys_t *zb)
181 {
182 	arc_flags_t flags = ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH;
183 
184 	if (!(td->td_flags & TRAVERSE_PREFETCH_METADATA))
185 		return;
186 	/*
187 	 * If we are in the process of resuming, don't prefetch, because
188 	 * some children will not be needed (and in fact may have already
189 	 * been freed).
190 	 */
191 	if (td->td_resume != NULL && !ZB_IS_ZERO(td->td_resume))
192 		return;
193 	if (BP_IS_HOLE(bp) || bp->blk_birth <= td->td_min_txg)
194 		return;
195 	if (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_DNODE)
196 		return;
197 
198 	(void) arc_read(NULL, td->td_spa, bp, NULL, NULL,
199 	    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
200 }
201 
202 static boolean_t
prefetch_needed(prefetch_data_t * pfd,const blkptr_t * bp)203 prefetch_needed(prefetch_data_t *pfd, const blkptr_t *bp)
204 {
205 	ASSERT(pfd->pd_flags & TRAVERSE_PREFETCH_DATA);
206 	if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp) ||
207 	    BP_GET_TYPE(bp) == DMU_OT_INTENT_LOG)
208 		return (B_FALSE);
209 	return (B_TRUE);
210 }
211 
212 static int
traverse_visitbp(traverse_data_t * td,const dnode_phys_t * dnp,const blkptr_t * bp,const zbookmark_phys_t * zb)213 traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp,
214     const blkptr_t *bp, const zbookmark_phys_t *zb)
215 {
216 	zbookmark_phys_t czb;
217 	int err = 0;
218 	arc_buf_t *buf = NULL;
219 	prefetch_data_t *pd = td->td_pfd;
220 	boolean_t hard = td->td_flags & TRAVERSE_HARD;
221 
222 	switch (resume_skip_check(td, dnp, zb)) {
223 	case RESUME_SKIP_ALL:
224 		return (0);
225 	case RESUME_SKIP_CHILDREN:
226 		goto post;
227 	case RESUME_SKIP_NONE:
228 		break;
229 	default:
230 		ASSERT(0);
231 	}
232 
233 	if (bp->blk_birth == 0) {
234 		/*
235 		 * Since this block has a birth time of 0 it must be a
236 		 * hole created before the SPA_FEATURE_HOLE_BIRTH
237 		 * feature was enabled.  If SPA_FEATURE_HOLE_BIRTH
238 		 * was enabled before the min_txg for this traveral we
239 		 * know the hole must have been created before the
240 		 * min_txg for this traveral, so we can skip it. If
241 		 * SPA_FEATURE_HOLE_BIRTH was enabled after the min_txg
242 		 * for this traveral we cannot tell if the hole was
243 		 * created before or after the min_txg for this
244 		 * traversal, so we cannot skip it.
245 		 */
246 		if (td->td_hole_birth_enabled_txg < td->td_min_txg)
247 			return (0);
248 	} else if (bp->blk_birth <= td->td_min_txg) {
249 		return (0);
250 	}
251 
252 	if (pd != NULL && !pd->pd_exited && prefetch_needed(pd, bp)) {
253 		mutex_enter(&pd->pd_mtx);
254 		ASSERT(pd->pd_blks_fetched >= 0);
255 		while (pd->pd_blks_fetched == 0 && !pd->pd_exited)
256 			cv_wait(&pd->pd_cv, &pd->pd_mtx);
257 		pd->pd_blks_fetched--;
258 		cv_broadcast(&pd->pd_cv);
259 		mutex_exit(&pd->pd_mtx);
260 	}
261 
262 	if (BP_IS_HOLE(bp)) {
263 		err = td->td_func(td->td_spa, NULL, bp, zb, dnp, td->td_arg);
264 		if (err != 0)
265 			goto post;
266 		return (0);
267 	}
268 
269 	if (td->td_flags & TRAVERSE_PRE) {
270 		err = td->td_func(td->td_spa, NULL, bp, zb, dnp,
271 		    td->td_arg);
272 		if (err == TRAVERSE_VISIT_NO_CHILDREN)
273 			return (0);
274 		if (err != 0)
275 			goto post;
276 	}
277 
278 	if (BP_GET_LEVEL(bp) > 0) {
279 		arc_flags_t flags = ARC_FLAG_WAIT;
280 		int i;
281 		blkptr_t *cbp;
282 		int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;
283 
284 		err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf,
285 		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
286 		if (err != 0)
287 			goto post;
288 		cbp = buf->b_data;
289 
290 		for (i = 0; i < epb; i++) {
291 			SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
292 			    zb->zb_level - 1,
293 			    zb->zb_blkid * epb + i);
294 			traverse_prefetch_metadata(td, &cbp[i], &czb);
295 		}
296 
297 		/* recursively visitbp() blocks below this */
298 		for (i = 0; i < epb; i++) {
299 			SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
300 			    zb->zb_level - 1,
301 			    zb->zb_blkid * epb + i);
302 			err = traverse_visitbp(td, dnp, &cbp[i], &czb);
303 			if (err != 0)
304 				break;
305 		}
306 	} else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
307 		arc_flags_t flags = ARC_FLAG_WAIT;
308 		int i;
309 		int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
310 		dnode_phys_t *cdnp;
311 
312 		err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf,
313 		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
314 		if (err != 0)
315 			goto post;
316 		cdnp = buf->b_data;
317 
318 		for (i = 0; i < epb; i++) {
319 			prefetch_dnode_metadata(td, &cdnp[i], zb->zb_objset,
320 			    zb->zb_blkid * epb + i);
321 		}
322 
323 		/* recursively visitbp() blocks below this */
324 		for (i = 0; i < epb; i++) {
325 			err = traverse_dnode(td, &cdnp[i], zb->zb_objset,
326 			    zb->zb_blkid * epb + i);
327 			if (err != 0)
328 				break;
329 		}
330 	} else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
331 		arc_flags_t flags = ARC_FLAG_WAIT;
332 		objset_phys_t *osp;
333 		dnode_phys_t *mdnp, *gdnp, *udnp;
334 
335 		err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf,
336 		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
337 		if (err != 0)
338 			goto post;
339 
340 		osp = buf->b_data;
341 		mdnp = &osp->os_meta_dnode;
342 		gdnp = &osp->os_groupused_dnode;
343 		udnp = &osp->os_userused_dnode;
344 
345 		prefetch_dnode_metadata(td, mdnp, zb->zb_objset,
346 		    DMU_META_DNODE_OBJECT);
347 		if (arc_buf_size(buf) >= sizeof (objset_phys_t)) {
348 			prefetch_dnode_metadata(td, gdnp, zb->zb_objset,
349 			    DMU_GROUPUSED_OBJECT);
350 			prefetch_dnode_metadata(td, udnp, zb->zb_objset,
351 			    DMU_USERUSED_OBJECT);
352 		}
353 
354 		err = traverse_dnode(td, mdnp, zb->zb_objset,
355 		    DMU_META_DNODE_OBJECT);
356 		if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) {
357 			err = traverse_dnode(td, gdnp, zb->zb_objset,
358 			    DMU_GROUPUSED_OBJECT);
359 		}
360 		if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) {
361 			err = traverse_dnode(td, udnp, zb->zb_objset,
362 			    DMU_USERUSED_OBJECT);
363 		}
364 	}
365 
366 	if (buf)
367 		(void) arc_buf_remove_ref(buf, &buf);
368 
369 post:
370 	if (err == 0 && (td->td_flags & TRAVERSE_POST))
371 		err = td->td_func(td->td_spa, NULL, bp, zb, dnp, td->td_arg);
372 
373 	if (hard && (err == EIO || err == ECKSUM)) {
374 		/*
375 		 * Ignore this disk error as requested by the HARD flag,
376 		 * and continue traversal.
377 		 */
378 		err = 0;
379 	}
380 
381 	/*
382 	 * If we are stopping here, set td_resume.
383 	 */
384 	if (td->td_resume != NULL && err != 0 && !td->td_paused) {
385 		td->td_resume->zb_objset = zb->zb_objset;
386 		td->td_resume->zb_object = zb->zb_object;
387 		td->td_resume->zb_level = 0;
388 		/*
389 		 * If we have stopped on an indirect block (e.g. due to
390 		 * i/o error), we have not visited anything below it.
391 		 * Set the bookmark to the first level-0 block that we need
392 		 * to visit.  This way, the resuming code does not need to
393 		 * deal with resuming from indirect blocks.
394 		 */
395 		td->td_resume->zb_blkid = zb->zb_blkid <<
396 		    (zb->zb_level * (dnp->dn_indblkshift - SPA_BLKPTRSHIFT));
397 		td->td_paused = B_TRUE;
398 	}
399 
400 	return (err);
401 }
402 
403 static void
prefetch_dnode_metadata(traverse_data_t * td,const dnode_phys_t * dnp,uint64_t objset,uint64_t object)404 prefetch_dnode_metadata(traverse_data_t *td, const dnode_phys_t *dnp,
405     uint64_t objset, uint64_t object)
406 {
407 	int j;
408 	zbookmark_phys_t czb;
409 
410 	for (j = 0; j < dnp->dn_nblkptr; j++) {
411 		SET_BOOKMARK(&czb, objset, object, dnp->dn_nlevels - 1, j);
412 		traverse_prefetch_metadata(td, &dnp->dn_blkptr[j], &czb);
413 	}
414 
415 	if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
416 		SET_BOOKMARK(&czb, objset, object, 0, DMU_SPILL_BLKID);
417 		traverse_prefetch_metadata(td, &dnp->dn_spill, &czb);
418 	}
419 }
420 
421 static int
traverse_dnode(traverse_data_t * td,const dnode_phys_t * dnp,uint64_t objset,uint64_t object)422 traverse_dnode(traverse_data_t *td, const dnode_phys_t *dnp,
423     uint64_t objset, uint64_t object)
424 {
425 	int j, err = 0;
426 	zbookmark_phys_t czb;
427 
428 	for (j = 0; j < dnp->dn_nblkptr; j++) {
429 		SET_BOOKMARK(&czb, objset, object, dnp->dn_nlevels - 1, j);
430 		err = traverse_visitbp(td, dnp, &dnp->dn_blkptr[j], &czb);
431 		if (err != 0)
432 			break;
433 	}
434 
435 	if (err == 0 && dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
436 		SET_BOOKMARK(&czb, objset, object, 0, DMU_SPILL_BLKID);
437 		err = traverse_visitbp(td, dnp, &dnp->dn_spill, &czb);
438 	}
439 	return (err);
440 }
441 
442 /* ARGSUSED */
443 static int
traverse_prefetcher(spa_t * spa,zilog_t * zilog,const blkptr_t * bp,const zbookmark_phys_t * zb,const dnode_phys_t * dnp,void * arg)444 traverse_prefetcher(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
445     const zbookmark_phys_t *zb, const dnode_phys_t *dnp, void *arg)
446 {
447 	prefetch_data_t *pfd = arg;
448 	arc_flags_t aflags = ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH;
449 
450 	ASSERT(pfd->pd_blks_fetched >= 0);
451 	if (pfd->pd_cancel)
452 		return (SET_ERROR(EINTR));
453 
454 	if (!prefetch_needed(pfd, bp))
455 		return (0);
456 
457 	mutex_enter(&pfd->pd_mtx);
458 	while (!pfd->pd_cancel && pfd->pd_blks_fetched >= pfd->pd_blks_max)
459 		cv_wait(&pfd->pd_cv, &pfd->pd_mtx);
460 	pfd->pd_blks_fetched++;
461 	cv_broadcast(&pfd->pd_cv);
462 	mutex_exit(&pfd->pd_mtx);
463 
464 	(void) arc_read(NULL, spa, bp, NULL, NULL, ZIO_PRIORITY_ASYNC_READ,
465 	    ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE, &aflags, zb);
466 
467 	return (0);
468 }
469 
470 static void
traverse_prefetch_thread(void * arg)471 traverse_prefetch_thread(void *arg)
472 {
473 	traverse_data_t *td_main = arg;
474 	traverse_data_t td = *td_main;
475 	zbookmark_phys_t czb;
476 
477 	td.td_func = traverse_prefetcher;
478 	td.td_arg = td_main->td_pfd;
479 	td.td_pfd = NULL;
480 
481 	SET_BOOKMARK(&czb, td.td_objset,
482 	    ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
483 	(void) traverse_visitbp(&td, NULL, td.td_rootbp, &czb);
484 
485 	mutex_enter(&td_main->td_pfd->pd_mtx);
486 	td_main->td_pfd->pd_exited = B_TRUE;
487 	cv_broadcast(&td_main->td_pfd->pd_cv);
488 	mutex_exit(&td_main->td_pfd->pd_mtx);
489 }
490 
491 /*
492  * NB: dataset must not be changing on-disk (eg, is a snapshot or we are
493  * in syncing context).
494  */
495 static int
traverse_impl(spa_t * spa,dsl_dataset_t * ds,uint64_t objset,blkptr_t * rootbp,uint64_t txg_start,zbookmark_phys_t * resume,int flags,blkptr_cb_t func,void * arg)496 traverse_impl(spa_t *spa, dsl_dataset_t *ds, uint64_t objset, blkptr_t *rootbp,
497     uint64_t txg_start, zbookmark_phys_t *resume, int flags,
498     blkptr_cb_t func, void *arg)
499 {
500 	traverse_data_t td;
501 	prefetch_data_t pd = { 0 };
502 	zbookmark_phys_t czb;
503 	int err;
504 
505 	ASSERT(ds == NULL || objset == ds->ds_object);
506 	ASSERT(!(flags & TRAVERSE_PRE) || !(flags & TRAVERSE_POST));
507 
508 	/*
509 	 * The data prefetching mechanism (the prefetch thread) is incompatible
510 	 * with resuming from a bookmark.
511 	 */
512 	ASSERT(resume == NULL || !(flags & TRAVERSE_PREFETCH_DATA));
513 
514 	td.td_spa = spa;
515 	td.td_objset = objset;
516 	td.td_rootbp = rootbp;
517 	td.td_min_txg = txg_start;
518 	td.td_resume = resume;
519 	td.td_func = func;
520 	td.td_arg = arg;
521 	td.td_pfd = &pd;
522 	td.td_flags = flags;
523 	td.td_paused = B_FALSE;
524 
525 	if (spa_feature_is_active(spa, SPA_FEATURE_HOLE_BIRTH)) {
526 		VERIFY(spa_feature_enabled_txg(spa,
527 		    SPA_FEATURE_HOLE_BIRTH, &td.td_hole_birth_enabled_txg));
528 	} else {
529 		td.td_hole_birth_enabled_txg = 0;
530 	}
531 
532 	pd.pd_blks_max = zfs_pd_blks_max;
533 	pd.pd_flags = flags;
534 	mutex_init(&pd.pd_mtx, NULL, MUTEX_DEFAULT, NULL);
535 	cv_init(&pd.pd_cv, NULL, CV_DEFAULT, NULL);
536 
537 	/* See comment on ZIL traversal in dsl_scan_visitds. */
538 	if (ds != NULL && !dsl_dataset_is_snapshot(ds) && !BP_IS_HOLE(rootbp)) {
539 		arc_flags_t flags = ARC_FLAG_WAIT;
540 		objset_phys_t *osp;
541 		arc_buf_t *buf;
542 
543 		err = arc_read(NULL, td.td_spa, rootbp,
544 		    arc_getbuf_func, &buf,
545 		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, NULL);
546 		if (err != 0)
547 			return (err);
548 
549 		osp = buf->b_data;
550 		traverse_zil(&td, &osp->os_zil_header);
551 		(void) arc_buf_remove_ref(buf, &buf);
552 	}
553 
554 	if (!(flags & TRAVERSE_PREFETCH_DATA) ||
555 	    0 == taskq_dispatch(system_taskq, traverse_prefetch_thread,
556 	    &td, TQ_NOQUEUE))
557 		pd.pd_exited = B_TRUE;
558 
559 	SET_BOOKMARK(&czb, td.td_objset,
560 	    ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
561 	err = traverse_visitbp(&td, NULL, rootbp, &czb);
562 
563 	mutex_enter(&pd.pd_mtx);
564 	pd.pd_cancel = B_TRUE;
565 	cv_broadcast(&pd.pd_cv);
566 	while (!pd.pd_exited)
567 		cv_wait(&pd.pd_cv, &pd.pd_mtx);
568 	mutex_exit(&pd.pd_mtx);
569 
570 	mutex_destroy(&pd.pd_mtx);
571 	cv_destroy(&pd.pd_cv);
572 
573 	return (err);
574 }
575 
576 /*
577  * NB: dataset must not be changing on-disk (eg, is a snapshot or we are
578  * in syncing context).
579  */
580 int
traverse_dataset(dsl_dataset_t * ds,uint64_t txg_start,int flags,blkptr_cb_t func,void * arg)581 traverse_dataset(dsl_dataset_t *ds, uint64_t txg_start, int flags,
582     blkptr_cb_t func, void *arg)
583 {
584 	return (traverse_impl(ds->ds_dir->dd_pool->dp_spa, ds, ds->ds_object,
585 	    &dsl_dataset_phys(ds)->ds_bp, txg_start, NULL, flags, func, arg));
586 }
587 
588 int
traverse_dataset_destroyed(spa_t * spa,blkptr_t * blkptr,uint64_t txg_start,zbookmark_phys_t * resume,int flags,blkptr_cb_t func,void * arg)589 traverse_dataset_destroyed(spa_t *spa, blkptr_t *blkptr,
590     uint64_t txg_start, zbookmark_phys_t *resume, int flags,
591     blkptr_cb_t func, void *arg)
592 {
593 	return (traverse_impl(spa, NULL, ZB_DESTROYED_OBJSET,
594 	    blkptr, txg_start, resume, flags, func, arg));
595 }
596 
597 /*
598  * NB: pool must not be changing on-disk (eg, from zdb or sync context).
599  */
600 int
traverse_pool(spa_t * spa,uint64_t txg_start,int flags,blkptr_cb_t func,void * arg)601 traverse_pool(spa_t *spa, uint64_t txg_start, int flags,
602     blkptr_cb_t func, void *arg)
603 {
604 	int err;
605 	uint64_t obj;
606 	dsl_pool_t *dp = spa_get_dsl(spa);
607 	objset_t *mos = dp->dp_meta_objset;
608 	boolean_t hard = (flags & TRAVERSE_HARD);
609 
610 	/* visit the MOS */
611 	err = traverse_impl(spa, NULL, 0, spa_get_rootblkptr(spa),
612 	    txg_start, NULL, flags, func, arg);
613 	if (err != 0)
614 		return (err);
615 
616 	/* visit each dataset */
617 	for (obj = 1; err == 0;
618 	    err = dmu_object_next(mos, &obj, FALSE, txg_start)) {
619 		dmu_object_info_t doi;
620 
621 		err = dmu_object_info(mos, obj, &doi);
622 		if (err != 0) {
623 			if (hard)
624 				continue;
625 			break;
626 		}
627 
628 		if (doi.doi_bonus_type == DMU_OT_DSL_DATASET) {
629 			dsl_dataset_t *ds;
630 			uint64_t txg = txg_start;
631 
632 			dsl_pool_config_enter(dp, FTAG);
633 			err = dsl_dataset_hold_obj(dp, obj, FTAG, &ds);
634 			dsl_pool_config_exit(dp, FTAG);
635 			if (err != 0) {
636 				if (hard)
637 					continue;
638 				break;
639 			}
640 			if (dsl_dataset_phys(ds)->ds_prev_snap_txg > txg)
641 				txg = dsl_dataset_phys(ds)->ds_prev_snap_txg;
642 			err = traverse_dataset(ds, txg, flags, func, arg);
643 			dsl_dataset_rele(ds, FTAG);
644 			if (err != 0)
645 				break;
646 		}
647 	}
648 	if (err == ESRCH)
649 		err = 0;
650 	return (err);
651 }
652