xref: /illumos-gate/usr/src/uts/common/fs/zfs/dsl_dir.c (revision abddfefb3168362a915cd681eb5a6498ec6c9e09)
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/dmu.h>
27 #include <sys/dmu_objset.h>
28 #include <sys/dmu_tx.h>
29 #include <sys/dsl_dataset.h>
30 #include <sys/dsl_dir.h>
31 #include <sys/dsl_prop.h>
32 #include <sys/dsl_synctask.h>
33 #include <sys/dsl_deleg.h>
34 #include <sys/spa.h>
35 #include <sys/zap.h>
36 #include <sys/zio.h>
37 #include <sys/arc.h>
38 #include <sys/sunddi.h>
39 #include "zfs_namecheck.h"
40 
41 static uint64_t dsl_dir_space_towrite(dsl_dir_t *dd);
42 static void dsl_dir_set_reservation_sync(void *arg1, void *arg2,
43     cred_t *cr, dmu_tx_t *tx);
44 
45 
46 /* ARGSUSED */
47 static void
48 dsl_dir_evict(dmu_buf_t *db, void *arg)
49 {
50 	dsl_dir_t *dd = arg;
51 	dsl_pool_t *dp = dd->dd_pool;
52 	int t;
53 
54 	for (t = 0; t < TXG_SIZE; t++) {
55 		ASSERT(!txg_list_member(&dp->dp_dirty_dirs, dd, t));
56 		ASSERT(dd->dd_tempreserved[t] == 0);
57 		ASSERT(dd->dd_space_towrite[t] == 0);
58 	}
59 
60 	if (dd->dd_parent)
61 		dsl_dir_close(dd->dd_parent, dd);
62 
63 	spa_close(dd->dd_pool->dp_spa, dd);
64 
65 	/*
66 	 * The props callback list should be empty since they hold the
67 	 * dir open.
68 	 */
69 	list_destroy(&dd->dd_prop_cbs);
70 	mutex_destroy(&dd->dd_lock);
71 	kmem_free(dd, sizeof (dsl_dir_t));
72 }
73 
74 int
75 dsl_dir_open_obj(dsl_pool_t *dp, uint64_t ddobj,
76     const char *tail, void *tag, dsl_dir_t **ddp)
77 {
78 	dmu_buf_t *dbuf;
79 	dsl_dir_t *dd;
80 	int err;
81 
82 	ASSERT(RW_LOCK_HELD(&dp->dp_config_rwlock) ||
83 	    dsl_pool_sync_context(dp));
84 
85 	err = dmu_bonus_hold(dp->dp_meta_objset, ddobj, tag, &dbuf);
86 	if (err)
87 		return (err);
88 	dd = dmu_buf_get_user(dbuf);
89 #ifdef ZFS_DEBUG
90 	{
91 		dmu_object_info_t doi;
92 		dmu_object_info_from_db(dbuf, &doi);
93 		ASSERT3U(doi.doi_type, ==, DMU_OT_DSL_DIR);
94 		ASSERT3U(doi.doi_bonus_size, >=, sizeof (dsl_dir_phys_t));
95 	}
96 #endif
97 	if (dd == NULL) {
98 		dsl_dir_t *winner;
99 		int err;
100 
101 		dd = kmem_zalloc(sizeof (dsl_dir_t), KM_SLEEP);
102 		dd->dd_object = ddobj;
103 		dd->dd_dbuf = dbuf;
104 		dd->dd_pool = dp;
105 		dd->dd_phys = dbuf->db_data;
106 		mutex_init(&dd->dd_lock, NULL, MUTEX_DEFAULT, NULL);
107 
108 		list_create(&dd->dd_prop_cbs, sizeof (dsl_prop_cb_record_t),
109 		    offsetof(dsl_prop_cb_record_t, cbr_node));
110 
111 		if (dd->dd_phys->dd_parent_obj) {
112 			err = dsl_dir_open_obj(dp, dd->dd_phys->dd_parent_obj,
113 			    NULL, dd, &dd->dd_parent);
114 			if (err)
115 				goto errout;
116 			if (tail) {
117 #ifdef ZFS_DEBUG
118 				uint64_t foundobj;
119 
120 				err = zap_lookup(dp->dp_meta_objset,
121 				    dd->dd_parent->dd_phys->dd_child_dir_zapobj,
122 				    tail, sizeof (foundobj), 1, &foundobj);
123 				ASSERT(err || foundobj == ddobj);
124 #endif
125 				(void) strcpy(dd->dd_myname, tail);
126 			} else {
127 				err = zap_value_search(dp->dp_meta_objset,
128 				    dd->dd_parent->dd_phys->dd_child_dir_zapobj,
129 				    ddobj, 0, dd->dd_myname);
130 			}
131 			if (err)
132 				goto errout;
133 		} else {
134 			(void) strcpy(dd->dd_myname, spa_name(dp->dp_spa));
135 		}
136 
137 		winner = dmu_buf_set_user_ie(dbuf, dd, &dd->dd_phys,
138 		    dsl_dir_evict);
139 		if (winner) {
140 			if (dd->dd_parent)
141 				dsl_dir_close(dd->dd_parent, dd);
142 			mutex_destroy(&dd->dd_lock);
143 			kmem_free(dd, sizeof (dsl_dir_t));
144 			dd = winner;
145 		} else {
146 			spa_open_ref(dp->dp_spa, dd);
147 		}
148 	}
149 
150 	/*
151 	 * The dsl_dir_t has both open-to-close and instantiate-to-evict
152 	 * holds on the spa.  We need the open-to-close holds because
153 	 * otherwise the spa_refcnt wouldn't change when we open a
154 	 * dir which the spa also has open, so we could incorrectly
155 	 * think it was OK to unload/export/destroy the pool.  We need
156 	 * the instantiate-to-evict hold because the dsl_dir_t has a
157 	 * pointer to the dd_pool, which has a pointer to the spa_t.
158 	 */
159 	spa_open_ref(dp->dp_spa, tag);
160 	ASSERT3P(dd->dd_pool, ==, dp);
161 	ASSERT3U(dd->dd_object, ==, ddobj);
162 	ASSERT3P(dd->dd_dbuf, ==, dbuf);
163 	*ddp = dd;
164 	return (0);
165 
166 errout:
167 	if (dd->dd_parent)
168 		dsl_dir_close(dd->dd_parent, dd);
169 	mutex_destroy(&dd->dd_lock);
170 	kmem_free(dd, sizeof (dsl_dir_t));
171 	dmu_buf_rele(dbuf, tag);
172 	return (err);
173 
174 }
175 
176 void
177 dsl_dir_close(dsl_dir_t *dd, void *tag)
178 {
179 	dprintf_dd(dd, "%s\n", "");
180 	spa_close(dd->dd_pool->dp_spa, tag);
181 	dmu_buf_rele(dd->dd_dbuf, tag);
182 }
183 
184 /* buf must be long enough (MAXNAMELEN + strlen(MOS_DIR_NAME) + 1 should do) */
185 void
186 dsl_dir_name(dsl_dir_t *dd, char *buf)
187 {
188 	if (dd->dd_parent) {
189 		dsl_dir_name(dd->dd_parent, buf);
190 		(void) strcat(buf, "/");
191 	} else {
192 		buf[0] = '\0';
193 	}
194 	if (!MUTEX_HELD(&dd->dd_lock)) {
195 		/*
196 		 * recursive mutex so that we can use
197 		 * dprintf_dd() with dd_lock held
198 		 */
199 		mutex_enter(&dd->dd_lock);
200 		(void) strcat(buf, dd->dd_myname);
201 		mutex_exit(&dd->dd_lock);
202 	} else {
203 		(void) strcat(buf, dd->dd_myname);
204 	}
205 }
206 
207 /* Calculate name legnth, avoiding all the strcat calls of dsl_dir_name */
208 int
209 dsl_dir_namelen(dsl_dir_t *dd)
210 {
211 	int result = 0;
212 
213 	if (dd->dd_parent) {
214 		/* parent's name + 1 for the "/" */
215 		result = dsl_dir_namelen(dd->dd_parent) + 1;
216 	}
217 
218 	if (!MUTEX_HELD(&dd->dd_lock)) {
219 		/* see dsl_dir_name */
220 		mutex_enter(&dd->dd_lock);
221 		result += strlen(dd->dd_myname);
222 		mutex_exit(&dd->dd_lock);
223 	} else {
224 		result += strlen(dd->dd_myname);
225 	}
226 
227 	return (result);
228 }
229 
230 static int
231 getcomponent(const char *path, char *component, const char **nextp)
232 {
233 	char *p;
234 	if ((path == NULL) || (path[0] == '\0'))
235 		return (ENOENT);
236 	/* This would be a good place to reserve some namespace... */
237 	p = strpbrk(path, "/@");
238 	if (p && (p[1] == '/' || p[1] == '@')) {
239 		/* two separators in a row */
240 		return (EINVAL);
241 	}
242 	if (p == NULL || p == path) {
243 		/*
244 		 * if the first thing is an @ or /, it had better be an
245 		 * @ and it had better not have any more ats or slashes,
246 		 * and it had better have something after the @.
247 		 */
248 		if (p != NULL &&
249 		    (p[0] != '@' || strpbrk(path+1, "/@") || p[1] == '\0'))
250 			return (EINVAL);
251 		if (strlen(path) >= MAXNAMELEN)
252 			return (ENAMETOOLONG);
253 		(void) strcpy(component, path);
254 		p = NULL;
255 	} else if (p[0] == '/') {
256 		if (p-path >= MAXNAMELEN)
257 			return (ENAMETOOLONG);
258 		(void) strncpy(component, path, p - path);
259 		component[p-path] = '\0';
260 		p++;
261 	} else if (p[0] == '@') {
262 		/*
263 		 * if the next separator is an @, there better not be
264 		 * any more slashes.
265 		 */
266 		if (strchr(path, '/'))
267 			return (EINVAL);
268 		if (p-path >= MAXNAMELEN)
269 			return (ENAMETOOLONG);
270 		(void) strncpy(component, path, p - path);
271 		component[p-path] = '\0';
272 	} else {
273 		ASSERT(!"invalid p");
274 	}
275 	*nextp = p;
276 	return (0);
277 }
278 
279 /*
280  * same as dsl_open_dir, ignore the first component of name and use the
281  * spa instead
282  */
283 int
284 dsl_dir_open_spa(spa_t *spa, const char *name, void *tag,
285     dsl_dir_t **ddp, const char **tailp)
286 {
287 	char buf[MAXNAMELEN];
288 	const char *next, *nextnext = NULL;
289 	int err;
290 	dsl_dir_t *dd;
291 	dsl_pool_t *dp;
292 	uint64_t ddobj;
293 	int openedspa = FALSE;
294 
295 	dprintf("%s\n", name);
296 
297 	err = getcomponent(name, buf, &next);
298 	if (err)
299 		return (err);
300 	if (spa == NULL) {
301 		err = spa_open(buf, &spa, FTAG);
302 		if (err) {
303 			dprintf("spa_open(%s) failed\n", buf);
304 			return (err);
305 		}
306 		openedspa = TRUE;
307 
308 		/* XXX this assertion belongs in spa_open */
309 		ASSERT(!dsl_pool_sync_context(spa_get_dsl(spa)));
310 	}
311 
312 	dp = spa_get_dsl(spa);
313 
314 	rw_enter(&dp->dp_config_rwlock, RW_READER);
315 	err = dsl_dir_open_obj(dp, dp->dp_root_dir_obj, NULL, tag, &dd);
316 	if (err) {
317 		rw_exit(&dp->dp_config_rwlock);
318 		if (openedspa)
319 			spa_close(spa, FTAG);
320 		return (err);
321 	}
322 
323 	while (next != NULL) {
324 		dsl_dir_t *child_ds;
325 		err = getcomponent(next, buf, &nextnext);
326 		if (err)
327 			break;
328 		ASSERT(next[0] != '\0');
329 		if (next[0] == '@')
330 			break;
331 		dprintf("looking up %s in obj%lld\n",
332 		    buf, dd->dd_phys->dd_child_dir_zapobj);
333 
334 		err = zap_lookup(dp->dp_meta_objset,
335 		    dd->dd_phys->dd_child_dir_zapobj,
336 		    buf, sizeof (ddobj), 1, &ddobj);
337 		if (err) {
338 			if (err == ENOENT)
339 				err = 0;
340 			break;
341 		}
342 
343 		err = dsl_dir_open_obj(dp, ddobj, buf, tag, &child_ds);
344 		if (err)
345 			break;
346 		dsl_dir_close(dd, tag);
347 		dd = child_ds;
348 		next = nextnext;
349 	}
350 	rw_exit(&dp->dp_config_rwlock);
351 
352 	if (err) {
353 		dsl_dir_close(dd, tag);
354 		if (openedspa)
355 			spa_close(spa, FTAG);
356 		return (err);
357 	}
358 
359 	/*
360 	 * It's an error if there's more than one component left, or
361 	 * tailp==NULL and there's any component left.
362 	 */
363 	if (next != NULL &&
364 	    (tailp == NULL || (nextnext && nextnext[0] != '\0'))) {
365 		/* bad path name */
366 		dsl_dir_close(dd, tag);
367 		dprintf("next=%p (%s) tail=%p\n", next, next?next:"", tailp);
368 		err = ENOENT;
369 	}
370 	if (tailp)
371 		*tailp = next;
372 	if (openedspa)
373 		spa_close(spa, FTAG);
374 	*ddp = dd;
375 	return (err);
376 }
377 
378 /*
379  * Return the dsl_dir_t, and possibly the last component which couldn't
380  * be found in *tail.  Return NULL if the path is bogus, or if
381  * tail==NULL and we couldn't parse the whole name.  (*tail)[0] == '@'
382  * means that the last component is a snapshot.
383  */
384 int
385 dsl_dir_open(const char *name, void *tag, dsl_dir_t **ddp, const char **tailp)
386 {
387 	return (dsl_dir_open_spa(NULL, name, tag, ddp, tailp));
388 }
389 
390 uint64_t
391 dsl_dir_create_sync(dsl_pool_t *dp, dsl_dir_t *pds, const char *name,
392     dmu_tx_t *tx)
393 {
394 	objset_t *mos = dp->dp_meta_objset;
395 	uint64_t ddobj;
396 	dsl_dir_phys_t *dsphys;
397 	dmu_buf_t *dbuf;
398 
399 	ddobj = dmu_object_alloc(mos, DMU_OT_DSL_DIR, 0,
400 	    DMU_OT_DSL_DIR, sizeof (dsl_dir_phys_t), tx);
401 	if (pds) {
402 		VERIFY(0 == zap_add(mos, pds->dd_phys->dd_child_dir_zapobj,
403 		    name, sizeof (uint64_t), 1, &ddobj, tx));
404 	} else {
405 		/* it's the root dir */
406 		VERIFY(0 == zap_add(mos, DMU_POOL_DIRECTORY_OBJECT,
407 		    DMU_POOL_ROOT_DATASET, sizeof (uint64_t), 1, &ddobj, tx));
408 	}
409 	VERIFY(0 == dmu_bonus_hold(mos, ddobj, FTAG, &dbuf));
410 	dmu_buf_will_dirty(dbuf, tx);
411 	dsphys = dbuf->db_data;
412 
413 	dsphys->dd_creation_time = gethrestime_sec();
414 	if (pds)
415 		dsphys->dd_parent_obj = pds->dd_object;
416 	dsphys->dd_props_zapobj = zap_create(mos,
417 	    DMU_OT_DSL_PROPS, DMU_OT_NONE, 0, tx);
418 	dsphys->dd_child_dir_zapobj = zap_create(mos,
419 	    DMU_OT_DSL_DIR_CHILD_MAP, DMU_OT_NONE, 0, tx);
420 	if (spa_version(dp->dp_spa) >= SPA_VERSION_USED_BREAKDOWN)
421 		dsphys->dd_flags |= DD_FLAG_USED_BREAKDOWN;
422 	dmu_buf_rele(dbuf, FTAG);
423 
424 	return (ddobj);
425 }
426 
427 /* ARGSUSED */
428 int
429 dsl_dir_destroy_check(void *arg1, void *arg2, dmu_tx_t *tx)
430 {
431 	dsl_dir_t *dd = arg1;
432 	dsl_pool_t *dp = dd->dd_pool;
433 	objset_t *mos = dp->dp_meta_objset;
434 	int err;
435 	uint64_t count;
436 
437 	/*
438 	 * There should be exactly two holds, both from
439 	 * dsl_dataset_destroy: one on the dd directory, and one on its
440 	 * head ds.  Otherwise, someone is trying to lookup something
441 	 * inside this dir while we want to destroy it.  The
442 	 * config_rwlock ensures that nobody else opens it after we
443 	 * check.
444 	 */
445 	if (dmu_buf_refcount(dd->dd_dbuf) > 2)
446 		return (EBUSY);
447 
448 	err = zap_count(mos, dd->dd_phys->dd_child_dir_zapobj, &count);
449 	if (err)
450 		return (err);
451 	if (count != 0)
452 		return (EEXIST);
453 
454 	return (0);
455 }
456 
457 void
458 dsl_dir_destroy_sync(void *arg1, void *tag, cred_t *cr, dmu_tx_t *tx)
459 {
460 	dsl_dir_t *dd = arg1;
461 	objset_t *mos = dd->dd_pool->dp_meta_objset;
462 	uint64_t val, obj;
463 	dd_used_t t;
464 
465 	ASSERT(RW_WRITE_HELD(&dd->dd_pool->dp_config_rwlock));
466 	ASSERT(dd->dd_phys->dd_head_dataset_obj == 0);
467 
468 	/* Remove our reservation. */
469 	val = 0;
470 	dsl_dir_set_reservation_sync(dd, &val, cr, tx);
471 	ASSERT3U(dd->dd_phys->dd_used_bytes, ==, 0);
472 	ASSERT3U(dd->dd_phys->dd_reserved, ==, 0);
473 	for (t = 0; t < DD_USED_NUM; t++)
474 		ASSERT3U(dd->dd_phys->dd_used_breakdown[t], ==, 0);
475 
476 	VERIFY(0 == zap_destroy(mos, dd->dd_phys->dd_child_dir_zapobj, tx));
477 	VERIFY(0 == zap_destroy(mos, dd->dd_phys->dd_props_zapobj, tx));
478 	VERIFY(0 == dsl_deleg_destroy(mos, dd->dd_phys->dd_deleg_zapobj, tx));
479 	VERIFY(0 == zap_remove(mos,
480 	    dd->dd_parent->dd_phys->dd_child_dir_zapobj, dd->dd_myname, tx));
481 
482 	obj = dd->dd_object;
483 	dsl_dir_close(dd, tag);
484 	VERIFY(0 == dmu_object_free(mos, obj, tx));
485 }
486 
487 boolean_t
488 dsl_dir_is_clone(dsl_dir_t *dd)
489 {
490 	return (dd->dd_phys->dd_origin_obj &&
491 	    (dd->dd_pool->dp_origin_snap == NULL ||
492 	    dd->dd_phys->dd_origin_obj !=
493 	    dd->dd_pool->dp_origin_snap->ds_object));
494 }
495 
496 void
497 dsl_dir_stats(dsl_dir_t *dd, nvlist_t *nv)
498 {
499 	mutex_enter(&dd->dd_lock);
500 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USED,
501 	    dd->dd_phys->dd_used_bytes);
502 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_QUOTA, dd->dd_phys->dd_quota);
503 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_RESERVATION,
504 	    dd->dd_phys->dd_reserved);
505 	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_COMPRESSRATIO,
506 	    dd->dd_phys->dd_compressed_bytes == 0 ? 100 :
507 	    (dd->dd_phys->dd_uncompressed_bytes * 100 /
508 	    dd->dd_phys->dd_compressed_bytes));
509 	if (dd->dd_phys->dd_flags & DD_FLAG_USED_BREAKDOWN) {
510 		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDSNAP,
511 		    dd->dd_phys->dd_used_breakdown[DD_USED_SNAP]);
512 		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDDS,
513 		    dd->dd_phys->dd_used_breakdown[DD_USED_HEAD]);
514 		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDREFRESERV,
515 		    dd->dd_phys->dd_used_breakdown[DD_USED_REFRSRV]);
516 		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDCHILD,
517 		    dd->dd_phys->dd_used_breakdown[DD_USED_CHILD] +
518 		    dd->dd_phys->dd_used_breakdown[DD_USED_CHILD_RSRV]);
519 	}
520 	mutex_exit(&dd->dd_lock);
521 
522 	rw_enter(&dd->dd_pool->dp_config_rwlock, RW_READER);
523 	if (dsl_dir_is_clone(dd)) {
524 		dsl_dataset_t *ds;
525 		char buf[MAXNAMELEN];
526 
527 		VERIFY(0 == dsl_dataset_hold_obj(dd->dd_pool,
528 		    dd->dd_phys->dd_origin_obj, FTAG, &ds));
529 		dsl_dataset_name(ds, buf);
530 		dsl_dataset_rele(ds, FTAG);
531 		dsl_prop_nvlist_add_string(nv, ZFS_PROP_ORIGIN, buf);
532 	}
533 	rw_exit(&dd->dd_pool->dp_config_rwlock);
534 }
535 
536 void
537 dsl_dir_dirty(dsl_dir_t *dd, dmu_tx_t *tx)
538 {
539 	dsl_pool_t *dp = dd->dd_pool;
540 
541 	ASSERT(dd->dd_phys);
542 
543 	if (txg_list_add(&dp->dp_dirty_dirs, dd, tx->tx_txg) == 0) {
544 		/* up the hold count until we can be written out */
545 		dmu_buf_add_ref(dd->dd_dbuf, dd);
546 	}
547 }
548 
549 static int64_t
550 parent_delta(dsl_dir_t *dd, uint64_t used, int64_t delta)
551 {
552 	uint64_t old_accounted = MAX(used, dd->dd_phys->dd_reserved);
553 	uint64_t new_accounted = MAX(used + delta, dd->dd_phys->dd_reserved);
554 	return (new_accounted - old_accounted);
555 }
556 
557 void
558 dsl_dir_sync(dsl_dir_t *dd, dmu_tx_t *tx)
559 {
560 	ASSERT(dmu_tx_is_syncing(tx));
561 
562 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
563 
564 	mutex_enter(&dd->dd_lock);
565 	ASSERT3U(dd->dd_tempreserved[tx->tx_txg&TXG_MASK], ==, 0);
566 	dprintf_dd(dd, "txg=%llu towrite=%lluK\n", tx->tx_txg,
567 	    dd->dd_space_towrite[tx->tx_txg&TXG_MASK] / 1024);
568 	dd->dd_space_towrite[tx->tx_txg&TXG_MASK] = 0;
569 	mutex_exit(&dd->dd_lock);
570 
571 	/* release the hold from dsl_dir_dirty */
572 	dmu_buf_rele(dd->dd_dbuf, dd);
573 }
574 
575 static uint64_t
576 dsl_dir_space_towrite(dsl_dir_t *dd)
577 {
578 	uint64_t space = 0;
579 	int i;
580 
581 	ASSERT(MUTEX_HELD(&dd->dd_lock));
582 
583 	for (i = 0; i < TXG_SIZE; i++) {
584 		space += dd->dd_space_towrite[i&TXG_MASK];
585 		ASSERT3U(dd->dd_space_towrite[i&TXG_MASK], >=, 0);
586 	}
587 	return (space);
588 }
589 
590 /*
591  * How much space would dd have available if ancestor had delta applied
592  * to it?  If ondiskonly is set, we're only interested in what's
593  * on-disk, not estimated pending changes.
594  */
595 uint64_t
596 dsl_dir_space_available(dsl_dir_t *dd,
597     dsl_dir_t *ancestor, int64_t delta, int ondiskonly)
598 {
599 	uint64_t parentspace, myspace, quota, used;
600 
601 	/*
602 	 * If there are no restrictions otherwise, assume we have
603 	 * unlimited space available.
604 	 */
605 	quota = UINT64_MAX;
606 	parentspace = UINT64_MAX;
607 
608 	if (dd->dd_parent != NULL) {
609 		parentspace = dsl_dir_space_available(dd->dd_parent,
610 		    ancestor, delta, ondiskonly);
611 	}
612 
613 	mutex_enter(&dd->dd_lock);
614 	if (dd->dd_phys->dd_quota != 0)
615 		quota = dd->dd_phys->dd_quota;
616 	used = dd->dd_phys->dd_used_bytes;
617 	if (!ondiskonly)
618 		used += dsl_dir_space_towrite(dd);
619 
620 	if (dd->dd_parent == NULL) {
621 		uint64_t poolsize = dsl_pool_adjustedsize(dd->dd_pool, FALSE);
622 		quota = MIN(quota, poolsize);
623 	}
624 
625 	if (dd->dd_phys->dd_reserved > used && parentspace != UINT64_MAX) {
626 		/*
627 		 * We have some space reserved, in addition to what our
628 		 * parent gave us.
629 		 */
630 		parentspace += dd->dd_phys->dd_reserved - used;
631 	}
632 
633 	if (dd == ancestor) {
634 		ASSERT(delta <= 0);
635 		ASSERT(used >= -delta);
636 		used += delta;
637 		if (parentspace != UINT64_MAX)
638 			parentspace -= delta;
639 	}
640 
641 	if (used > quota) {
642 		/* over quota */
643 		myspace = 0;
644 
645 		/*
646 		 * While it's OK to be a little over quota, if
647 		 * we think we are using more space than there
648 		 * is in the pool (which is already 1.6% more than
649 		 * dsl_pool_adjustedsize()), something is very
650 		 * wrong.
651 		 */
652 		ASSERT3U(used, <=, spa_get_space(dd->dd_pool->dp_spa));
653 	} else {
654 		/*
655 		 * the lesser of the space provided by our parent and
656 		 * the space left in our quota
657 		 */
658 		myspace = MIN(parentspace, quota - used);
659 	}
660 
661 	mutex_exit(&dd->dd_lock);
662 
663 	return (myspace);
664 }
665 
666 struct tempreserve {
667 	list_node_t tr_node;
668 	dsl_pool_t *tr_dp;
669 	dsl_dir_t *tr_ds;
670 	uint64_t tr_size;
671 };
672 
673 static int
674 dsl_dir_tempreserve_impl(dsl_dir_t *dd, uint64_t asize, boolean_t netfree,
675     boolean_t ignorequota, boolean_t checkrefquota, list_t *tr_list,
676     dmu_tx_t *tx, boolean_t first)
677 {
678 	uint64_t txg = tx->tx_txg;
679 	uint64_t est_inflight, used_on_disk, quota, parent_rsrv;
680 	struct tempreserve *tr;
681 	int enospc = EDQUOT;
682 	int txgidx = txg & TXG_MASK;
683 	int i;
684 	uint64_t ref_rsrv = 0;
685 
686 	ASSERT3U(txg, !=, 0);
687 	ASSERT3S(asize, >, 0);
688 
689 	mutex_enter(&dd->dd_lock);
690 
691 	/*
692 	 * Check against the dsl_dir's quota.  We don't add in the delta
693 	 * when checking for over-quota because they get one free hit.
694 	 */
695 	est_inflight = dsl_dir_space_towrite(dd);
696 	for (i = 0; i < TXG_SIZE; i++)
697 		est_inflight += dd->dd_tempreserved[i];
698 	used_on_disk = dd->dd_phys->dd_used_bytes;
699 
700 	/*
701 	 * On the first iteration, fetch the dataset's used-on-disk and
702 	 * refreservation values. Also, if checkrefquota is set, test if
703 	 * allocating this space would exceed the dataset's refquota.
704 	 */
705 	if (first && tx->tx_objset) {
706 		int error;
707 		dsl_dataset_t *ds = tx->tx_objset->os->os_dsl_dataset;
708 
709 		error = dsl_dataset_check_quota(ds, checkrefquota,
710 		    asize, est_inflight, &used_on_disk, &ref_rsrv);
711 		if (error) {
712 			mutex_exit(&dd->dd_lock);
713 			return (error);
714 		}
715 	}
716 
717 	/*
718 	 * If this transaction will result in a net free of space,
719 	 * we want to let it through.
720 	 */
721 	if (ignorequota || netfree || dd->dd_phys->dd_quota == 0)
722 		quota = UINT64_MAX;
723 	else
724 		quota = dd->dd_phys->dd_quota;
725 
726 	/*
727 	 * Adjust the quota against the actual pool size at the root.
728 	 * To ensure that it's possible to remove files from a full
729 	 * pool without inducing transient overcommits, we throttle
730 	 * netfree transactions against a quota that is slightly larger,
731 	 * but still within the pool's allocation slop.  In cases where
732 	 * we're very close to full, this will allow a steady trickle of
733 	 * removes to get through.
734 	 */
735 	if (dd->dd_parent == NULL) {
736 		uint64_t poolsize = dsl_pool_adjustedsize(dd->dd_pool, netfree);
737 		if (poolsize < quota) {
738 			quota = poolsize;
739 			enospc = ENOSPC;
740 		}
741 	}
742 
743 	/*
744 	 * If they are requesting more space, and our current estimate
745 	 * is over quota, they get to try again unless the actual
746 	 * on-disk is over quota and there are no pending changes (which
747 	 * may free up space for us).
748 	 */
749 	if (used_on_disk + est_inflight > quota) {
750 		if (est_inflight > 0 || used_on_disk < quota)
751 			enospc = ERESTART;
752 		dprintf_dd(dd, "failing: used=%lluK inflight = %lluK "
753 		    "quota=%lluK tr=%lluK err=%d\n",
754 		    used_on_disk>>10, est_inflight>>10,
755 		    quota>>10, asize>>10, enospc);
756 		mutex_exit(&dd->dd_lock);
757 		return (enospc);
758 	}
759 
760 	/* We need to up our estimated delta before dropping dd_lock */
761 	dd->dd_tempreserved[txgidx] += asize;
762 
763 	parent_rsrv = parent_delta(dd, used_on_disk + est_inflight,
764 	    asize - ref_rsrv);
765 	mutex_exit(&dd->dd_lock);
766 
767 	tr = kmem_zalloc(sizeof (struct tempreserve), KM_SLEEP);
768 	tr->tr_ds = dd;
769 	tr->tr_size = asize;
770 	list_insert_tail(tr_list, tr);
771 
772 	/* see if it's OK with our parent */
773 	if (dd->dd_parent && parent_rsrv) {
774 		boolean_t ismos = (dd->dd_phys->dd_head_dataset_obj == 0);
775 
776 		return (dsl_dir_tempreserve_impl(dd->dd_parent,
777 		    parent_rsrv, netfree, ismos, TRUE, tr_list, tx, FALSE));
778 	} else {
779 		return (0);
780 	}
781 }
782 
783 /*
784  * Reserve space in this dsl_dir, to be used in this tx's txg.
785  * After the space has been dirtied (and dsl_dir_willuse_space()
786  * has been called), the reservation should be canceled, using
787  * dsl_dir_tempreserve_clear().
788  */
789 int
790 dsl_dir_tempreserve_space(dsl_dir_t *dd, uint64_t lsize, uint64_t asize,
791     uint64_t fsize, uint64_t usize, void **tr_cookiep, dmu_tx_t *tx)
792 {
793 	int err;
794 	list_t *tr_list;
795 
796 	if (asize == 0) {
797 		*tr_cookiep = NULL;
798 		return (0);
799 	}
800 
801 	tr_list = kmem_alloc(sizeof (list_t), KM_SLEEP);
802 	list_create(tr_list, sizeof (struct tempreserve),
803 	    offsetof(struct tempreserve, tr_node));
804 	ASSERT3S(asize, >, 0);
805 	ASSERT3S(fsize, >=, 0);
806 
807 	err = arc_tempreserve_space(lsize, tx->tx_txg);
808 	if (err == 0) {
809 		struct tempreserve *tr;
810 
811 		tr = kmem_zalloc(sizeof (struct tempreserve), KM_SLEEP);
812 		tr->tr_size = lsize;
813 		list_insert_tail(tr_list, tr);
814 
815 		err = dsl_pool_tempreserve_space(dd->dd_pool, asize, tx);
816 	} else {
817 		if (err == EAGAIN) {
818 			txg_delay(dd->dd_pool, tx->tx_txg, 1);
819 			err = ERESTART;
820 		}
821 		dsl_pool_memory_pressure(dd->dd_pool);
822 	}
823 
824 	if (err == 0) {
825 		struct tempreserve *tr;
826 
827 		tr = kmem_zalloc(sizeof (struct tempreserve), KM_SLEEP);
828 		tr->tr_dp = dd->dd_pool;
829 		tr->tr_size = asize;
830 		list_insert_tail(tr_list, tr);
831 
832 		err = dsl_dir_tempreserve_impl(dd, asize, fsize >= asize,
833 		    FALSE, asize > usize, tr_list, tx, TRUE);
834 	}
835 
836 	if (err)
837 		dsl_dir_tempreserve_clear(tr_list, tx);
838 	else
839 		*tr_cookiep = tr_list;
840 
841 	return (err);
842 }
843 
844 /*
845  * Clear a temporary reservation that we previously made with
846  * dsl_dir_tempreserve_space().
847  */
848 void
849 dsl_dir_tempreserve_clear(void *tr_cookie, dmu_tx_t *tx)
850 {
851 	int txgidx = tx->tx_txg & TXG_MASK;
852 	list_t *tr_list = tr_cookie;
853 	struct tempreserve *tr;
854 
855 	ASSERT3U(tx->tx_txg, !=, 0);
856 
857 	if (tr_cookie == NULL)
858 		return;
859 
860 	while (tr = list_head(tr_list)) {
861 		if (tr->tr_dp) {
862 			dsl_pool_tempreserve_clear(tr->tr_dp, tr->tr_size, tx);
863 		} else if (tr->tr_ds) {
864 			mutex_enter(&tr->tr_ds->dd_lock);
865 			ASSERT3U(tr->tr_ds->dd_tempreserved[txgidx], >=,
866 			    tr->tr_size);
867 			tr->tr_ds->dd_tempreserved[txgidx] -= tr->tr_size;
868 			mutex_exit(&tr->tr_ds->dd_lock);
869 		} else {
870 			arc_tempreserve_clear(tr->tr_size);
871 		}
872 		list_remove(tr_list, tr);
873 		kmem_free(tr, sizeof (struct tempreserve));
874 	}
875 
876 	kmem_free(tr_list, sizeof (list_t));
877 }
878 
879 static void
880 dsl_dir_willuse_space_impl(dsl_dir_t *dd, int64_t space, dmu_tx_t *tx)
881 {
882 	int64_t parent_space;
883 	uint64_t est_used;
884 
885 	mutex_enter(&dd->dd_lock);
886 	if (space > 0)
887 		dd->dd_space_towrite[tx->tx_txg & TXG_MASK] += space;
888 
889 	est_used = dsl_dir_space_towrite(dd) + dd->dd_phys->dd_used_bytes;
890 	parent_space = parent_delta(dd, est_used, space);
891 	mutex_exit(&dd->dd_lock);
892 
893 	/* Make sure that we clean up dd_space_to* */
894 	dsl_dir_dirty(dd, tx);
895 
896 	/* XXX this is potentially expensive and unnecessary... */
897 	if (parent_space && dd->dd_parent)
898 		dsl_dir_willuse_space_impl(dd->dd_parent, parent_space, tx);
899 }
900 
901 /*
902  * Call in open context when we think we're going to write/free space,
903  * eg. when dirtying data.  Be conservative (ie. OK to write less than
904  * this or free more than this, but don't write more or free less).
905  */
906 void
907 dsl_dir_willuse_space(dsl_dir_t *dd, int64_t space, dmu_tx_t *tx)
908 {
909 	dsl_pool_willuse_space(dd->dd_pool, space, tx);
910 	dsl_dir_willuse_space_impl(dd, space, tx);
911 }
912 
913 /* call from syncing context when we actually write/free space for this dd */
914 void
915 dsl_dir_diduse_space(dsl_dir_t *dd, dd_used_t type,
916     int64_t used, int64_t compressed, int64_t uncompressed, dmu_tx_t *tx)
917 {
918 	int64_t accounted_delta;
919 	boolean_t needlock = !MUTEX_HELD(&dd->dd_lock);
920 
921 	ASSERT(dmu_tx_is_syncing(tx));
922 	ASSERT(type < DD_USED_NUM);
923 
924 	dsl_dir_dirty(dd, tx);
925 
926 	if (needlock)
927 		mutex_enter(&dd->dd_lock);
928 	accounted_delta = parent_delta(dd, dd->dd_phys->dd_used_bytes, used);
929 	ASSERT(used >= 0 || dd->dd_phys->dd_used_bytes >= -used);
930 	ASSERT(compressed >= 0 ||
931 	    dd->dd_phys->dd_compressed_bytes >= -compressed);
932 	ASSERT(uncompressed >= 0 ||
933 	    dd->dd_phys->dd_uncompressed_bytes >= -uncompressed);
934 	dd->dd_phys->dd_used_bytes += used;
935 	dd->dd_phys->dd_uncompressed_bytes += uncompressed;
936 	dd->dd_phys->dd_compressed_bytes += compressed;
937 
938 	if (dd->dd_phys->dd_flags & DD_FLAG_USED_BREAKDOWN) {
939 		ASSERT(used > 0 ||
940 		    dd->dd_phys->dd_used_breakdown[type] >= -used);
941 		dd->dd_phys->dd_used_breakdown[type] += used;
942 #ifdef DEBUG
943 		dd_used_t t;
944 		uint64_t u = 0;
945 		for (t = 0; t < DD_USED_NUM; t++)
946 			u += dd->dd_phys->dd_used_breakdown[t];
947 		ASSERT3U(u, ==, dd->dd_phys->dd_used_bytes);
948 #endif
949 	}
950 	if (needlock)
951 		mutex_exit(&dd->dd_lock);
952 
953 	if (dd->dd_parent != NULL) {
954 		dsl_dir_diduse_space(dd->dd_parent, DD_USED_CHILD,
955 		    accounted_delta, compressed, uncompressed, tx);
956 		dsl_dir_transfer_space(dd->dd_parent,
957 		    used - accounted_delta,
958 		    DD_USED_CHILD_RSRV, DD_USED_CHILD, tx);
959 	}
960 }
961 
962 void
963 dsl_dir_transfer_space(dsl_dir_t *dd, int64_t delta,
964     dd_used_t oldtype, dd_used_t newtype, dmu_tx_t *tx)
965 {
966 	boolean_t needlock = !MUTEX_HELD(&dd->dd_lock);
967 
968 	ASSERT(dmu_tx_is_syncing(tx));
969 	ASSERT(oldtype < DD_USED_NUM);
970 	ASSERT(newtype < DD_USED_NUM);
971 
972 	if (delta == 0 || !(dd->dd_phys->dd_flags & DD_FLAG_USED_BREAKDOWN))
973 		return;
974 
975 	dsl_dir_dirty(dd, tx);
976 	if (needlock)
977 		mutex_enter(&dd->dd_lock);
978 	ASSERT(delta > 0 ?
979 	    dd->dd_phys->dd_used_breakdown[oldtype] >= delta :
980 	    dd->dd_phys->dd_used_breakdown[newtype] >= -delta);
981 	ASSERT(dd->dd_phys->dd_used_bytes >= ABS(delta));
982 	dd->dd_phys->dd_used_breakdown[oldtype] -= delta;
983 	dd->dd_phys->dd_used_breakdown[newtype] += delta;
984 	if (needlock)
985 		mutex_exit(&dd->dd_lock);
986 }
987 
988 static int
989 dsl_dir_set_quota_check(void *arg1, void *arg2, dmu_tx_t *tx)
990 {
991 	dsl_dir_t *dd = arg1;
992 	uint64_t *quotap = arg2;
993 	uint64_t new_quota = *quotap;
994 	int err = 0;
995 	uint64_t towrite;
996 
997 	if (new_quota == 0)
998 		return (0);
999 
1000 	mutex_enter(&dd->dd_lock);
1001 	/*
1002 	 * If we are doing the preliminary check in open context, and
1003 	 * there are pending changes, then don't fail it, since the
1004 	 * pending changes could under-estimate the amount of space to be
1005 	 * freed up.
1006 	 */
1007 	towrite = dsl_dir_space_towrite(dd);
1008 	if ((dmu_tx_is_syncing(tx) || towrite == 0) &&
1009 	    (new_quota < dd->dd_phys->dd_reserved ||
1010 	    new_quota < dd->dd_phys->dd_used_bytes + towrite)) {
1011 		err = ENOSPC;
1012 	}
1013 	mutex_exit(&dd->dd_lock);
1014 	return (err);
1015 }
1016 
1017 /* ARGSUSED */
1018 static void
1019 dsl_dir_set_quota_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
1020 {
1021 	dsl_dir_t *dd = arg1;
1022 	uint64_t *quotap = arg2;
1023 	uint64_t new_quota = *quotap;
1024 
1025 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
1026 
1027 	mutex_enter(&dd->dd_lock);
1028 	dd->dd_phys->dd_quota = new_quota;
1029 	mutex_exit(&dd->dd_lock);
1030 
1031 	spa_history_internal_log(LOG_DS_QUOTA, dd->dd_pool->dp_spa,
1032 	    tx, cr, "%lld dataset = %llu ",
1033 	    (longlong_t)new_quota, dd->dd_phys->dd_head_dataset_obj);
1034 }
1035 
1036 int
1037 dsl_dir_set_quota(const char *ddname, uint64_t quota)
1038 {
1039 	dsl_dir_t *dd;
1040 	int err;
1041 
1042 	err = dsl_dir_open(ddname, FTAG, &dd, NULL);
1043 	if (err)
1044 		return (err);
1045 
1046 	if (quota != dd->dd_phys->dd_quota) {
1047 		/*
1048 		 * If someone removes a file, then tries to set the quota, we
1049 		 * want to make sure the file freeing takes effect.
1050 		 */
1051 		txg_wait_open(dd->dd_pool, 0);
1052 
1053 		err = dsl_sync_task_do(dd->dd_pool, dsl_dir_set_quota_check,
1054 		    dsl_dir_set_quota_sync, dd, &quota, 0);
1055 	}
1056 	dsl_dir_close(dd, FTAG);
1057 	return (err);
1058 }
1059 
1060 int
1061 dsl_dir_set_reservation_check(void *arg1, void *arg2, dmu_tx_t *tx)
1062 {
1063 	dsl_dir_t *dd = arg1;
1064 	uint64_t *reservationp = arg2;
1065 	uint64_t new_reservation = *reservationp;
1066 	uint64_t used, avail;
1067 
1068 	/*
1069 	 * If we are doing the preliminary check in open context, the
1070 	 * space estimates may be inaccurate.
1071 	 */
1072 	if (!dmu_tx_is_syncing(tx))
1073 		return (0);
1074 
1075 	mutex_enter(&dd->dd_lock);
1076 	used = dd->dd_phys->dd_used_bytes;
1077 	mutex_exit(&dd->dd_lock);
1078 
1079 	if (dd->dd_parent) {
1080 		avail = dsl_dir_space_available(dd->dd_parent,
1081 		    NULL, 0, FALSE);
1082 	} else {
1083 		avail = dsl_pool_adjustedsize(dd->dd_pool, B_FALSE) - used;
1084 	}
1085 
1086 	if (MAX(used, new_reservation) > MAX(used, dd->dd_phys->dd_reserved)) {
1087 		uint64_t delta = MAX(used, new_reservation) -
1088 		    MAX(used, dd->dd_phys->dd_reserved);
1089 
1090 		if (delta > avail)
1091 			return (ENOSPC);
1092 		if (dd->dd_phys->dd_quota > 0 &&
1093 		    new_reservation > dd->dd_phys->dd_quota)
1094 			return (ENOSPC);
1095 	}
1096 
1097 	return (0);
1098 }
1099 
1100 /* ARGSUSED */
1101 static void
1102 dsl_dir_set_reservation_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
1103 {
1104 	dsl_dir_t *dd = arg1;
1105 	uint64_t *reservationp = arg2;
1106 	uint64_t new_reservation = *reservationp;
1107 	uint64_t used;
1108 	int64_t delta;
1109 
1110 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
1111 
1112 	mutex_enter(&dd->dd_lock);
1113 	used = dd->dd_phys->dd_used_bytes;
1114 	delta = MAX(used, new_reservation) -
1115 	    MAX(used, dd->dd_phys->dd_reserved);
1116 	dd->dd_phys->dd_reserved = new_reservation;
1117 
1118 	if (dd->dd_parent != NULL) {
1119 		/* Roll up this additional usage into our ancestors */
1120 		dsl_dir_diduse_space(dd->dd_parent, DD_USED_CHILD_RSRV,
1121 		    delta, 0, 0, tx);
1122 	}
1123 	mutex_exit(&dd->dd_lock);
1124 
1125 	spa_history_internal_log(LOG_DS_RESERVATION, dd->dd_pool->dp_spa,
1126 	    tx, cr, "%lld dataset = %llu",
1127 	    (longlong_t)new_reservation, dd->dd_phys->dd_head_dataset_obj);
1128 }
1129 
1130 int
1131 dsl_dir_set_reservation(const char *ddname, uint64_t reservation)
1132 {
1133 	dsl_dir_t *dd;
1134 	int err;
1135 
1136 	err = dsl_dir_open(ddname, FTAG, &dd, NULL);
1137 	if (err)
1138 		return (err);
1139 	err = dsl_sync_task_do(dd->dd_pool, dsl_dir_set_reservation_check,
1140 	    dsl_dir_set_reservation_sync, dd, &reservation, 0);
1141 	dsl_dir_close(dd, FTAG);
1142 	return (err);
1143 }
1144 
1145 static dsl_dir_t *
1146 closest_common_ancestor(dsl_dir_t *ds1, dsl_dir_t *ds2)
1147 {
1148 	for (; ds1; ds1 = ds1->dd_parent) {
1149 		dsl_dir_t *dd;
1150 		for (dd = ds2; dd; dd = dd->dd_parent) {
1151 			if (ds1 == dd)
1152 				return (dd);
1153 		}
1154 	}
1155 	return (NULL);
1156 }
1157 
1158 /*
1159  * If delta is applied to dd, how much of that delta would be applied to
1160  * ancestor?  Syncing context only.
1161  */
1162 static int64_t
1163 would_change(dsl_dir_t *dd, int64_t delta, dsl_dir_t *ancestor)
1164 {
1165 	if (dd == ancestor)
1166 		return (delta);
1167 
1168 	mutex_enter(&dd->dd_lock);
1169 	delta = parent_delta(dd, dd->dd_phys->dd_used_bytes, delta);
1170 	mutex_exit(&dd->dd_lock);
1171 	return (would_change(dd->dd_parent, delta, ancestor));
1172 }
1173 
1174 struct renamearg {
1175 	dsl_dir_t *newparent;
1176 	const char *mynewname;
1177 };
1178 
1179 /*ARGSUSED*/
1180 static int
1181 dsl_dir_rename_check(void *arg1, void *arg2, dmu_tx_t *tx)
1182 {
1183 	dsl_dir_t *dd = arg1;
1184 	struct renamearg *ra = arg2;
1185 	dsl_pool_t *dp = dd->dd_pool;
1186 	objset_t *mos = dp->dp_meta_objset;
1187 	int err;
1188 	uint64_t val;
1189 
1190 	/* There should be 2 references: the open and the dirty */
1191 	if (dmu_buf_refcount(dd->dd_dbuf) > 2)
1192 		return (EBUSY);
1193 
1194 	/* check for existing name */
1195 	err = zap_lookup(mos, ra->newparent->dd_phys->dd_child_dir_zapobj,
1196 	    ra->mynewname, 8, 1, &val);
1197 	if (err == 0)
1198 		return (EEXIST);
1199 	if (err != ENOENT)
1200 		return (err);
1201 
1202 	if (ra->newparent != dd->dd_parent) {
1203 		/* is there enough space? */
1204 		uint64_t myspace =
1205 		    MAX(dd->dd_phys->dd_used_bytes, dd->dd_phys->dd_reserved);
1206 
1207 		/* no rename into our descendant */
1208 		if (closest_common_ancestor(dd, ra->newparent) == dd)
1209 			return (EINVAL);
1210 
1211 		if (err = dsl_dir_transfer_possible(dd->dd_parent,
1212 		    ra->newparent, myspace))
1213 			return (err);
1214 	}
1215 
1216 	return (0);
1217 }
1218 
1219 static void
1220 dsl_dir_rename_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
1221 {
1222 	dsl_dir_t *dd = arg1;
1223 	struct renamearg *ra = arg2;
1224 	dsl_pool_t *dp = dd->dd_pool;
1225 	objset_t *mos = dp->dp_meta_objset;
1226 	int err;
1227 
1228 	ASSERT(dmu_buf_refcount(dd->dd_dbuf) <= 2);
1229 
1230 	if (ra->newparent != dd->dd_parent) {
1231 		dsl_dir_diduse_space(dd->dd_parent, DD_USED_CHILD,
1232 		    -dd->dd_phys->dd_used_bytes,
1233 		    -dd->dd_phys->dd_compressed_bytes,
1234 		    -dd->dd_phys->dd_uncompressed_bytes, tx);
1235 		dsl_dir_diduse_space(ra->newparent, DD_USED_CHILD,
1236 		    dd->dd_phys->dd_used_bytes,
1237 		    dd->dd_phys->dd_compressed_bytes,
1238 		    dd->dd_phys->dd_uncompressed_bytes, tx);
1239 
1240 		if (dd->dd_phys->dd_reserved > dd->dd_phys->dd_used_bytes) {
1241 			uint64_t unused_rsrv = dd->dd_phys->dd_reserved -
1242 			    dd->dd_phys->dd_used_bytes;
1243 
1244 			dsl_dir_diduse_space(dd->dd_parent, DD_USED_CHILD_RSRV,
1245 			    -unused_rsrv, 0, 0, tx);
1246 			dsl_dir_diduse_space(ra->newparent, DD_USED_CHILD_RSRV,
1247 			    unused_rsrv, 0, 0, tx);
1248 		}
1249 	}
1250 
1251 	dmu_buf_will_dirty(dd->dd_dbuf, tx);
1252 
1253 	/* remove from old parent zapobj */
1254 	err = zap_remove(mos, dd->dd_parent->dd_phys->dd_child_dir_zapobj,
1255 	    dd->dd_myname, tx);
1256 	ASSERT3U(err, ==, 0);
1257 
1258 	(void) strcpy(dd->dd_myname, ra->mynewname);
1259 	dsl_dir_close(dd->dd_parent, dd);
1260 	dd->dd_phys->dd_parent_obj = ra->newparent->dd_object;
1261 	VERIFY(0 == dsl_dir_open_obj(dd->dd_pool,
1262 	    ra->newparent->dd_object, NULL, dd, &dd->dd_parent));
1263 
1264 	/* add to new parent zapobj */
1265 	err = zap_add(mos, ra->newparent->dd_phys->dd_child_dir_zapobj,
1266 	    dd->dd_myname, 8, 1, &dd->dd_object, tx);
1267 	ASSERT3U(err, ==, 0);
1268 
1269 	spa_history_internal_log(LOG_DS_RENAME, dd->dd_pool->dp_spa,
1270 	    tx, cr, "dataset = %llu", dd->dd_phys->dd_head_dataset_obj);
1271 }
1272 
1273 int
1274 dsl_dir_rename(dsl_dir_t *dd, const char *newname)
1275 {
1276 	struct renamearg ra;
1277 	int err;
1278 
1279 	/* new parent should exist */
1280 	err = dsl_dir_open(newname, FTAG, &ra.newparent, &ra.mynewname);
1281 	if (err)
1282 		return (err);
1283 
1284 	/* can't rename to different pool */
1285 	if (dd->dd_pool != ra.newparent->dd_pool) {
1286 		err = ENXIO;
1287 		goto out;
1288 	}
1289 
1290 	/* new name should not already exist */
1291 	if (ra.mynewname == NULL) {
1292 		err = EEXIST;
1293 		goto out;
1294 	}
1295 
1296 	err = dsl_sync_task_do(dd->dd_pool,
1297 	    dsl_dir_rename_check, dsl_dir_rename_sync, dd, &ra, 3);
1298 
1299 out:
1300 	dsl_dir_close(ra.newparent, FTAG);
1301 	return (err);
1302 }
1303 
1304 int
1305 dsl_dir_transfer_possible(dsl_dir_t *sdd, dsl_dir_t *tdd, uint64_t space)
1306 {
1307 	dsl_dir_t *ancestor;
1308 	int64_t adelta;
1309 	uint64_t avail;
1310 
1311 	ancestor = closest_common_ancestor(sdd, tdd);
1312 	adelta = would_change(sdd, -space, ancestor);
1313 	avail = dsl_dir_space_available(tdd, ancestor, adelta, FALSE);
1314 	if (avail < space)
1315 		return (ENOSPC);
1316 
1317 	return (0);
1318 }
1319