xref: /freebsd/sys/contrib/openzfs/lib/libzfs/libzfs_changelist.c (revision d9497217456002b0ddad3cd319570d0b098daa29)
1 // SPDX-License-Identifier: CDDL-1.0
2 /*
3  * CDDL HEADER START
4  *
5  * The contents of this file are subject to the terms of the
6  * Common Development and Distribution License (the "License").
7  * You may not use this file except in compliance with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or https://opensource.org/licenses/CDDL-1.0.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 
23 /*
24  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
25  * Use is subject to license terms.
26  *
27  * Portions Copyright 2007 Ramprakash Jelari
28  * Copyright (c) 2014, 2020 by Delphix. All rights reserved.
29  * Copyright 2016 Igor Kozhukhov <ikozhukhov@gmail.com>
30  * Copyright (c) 2018 Datto Inc.
31  */
32 
33 #include <libintl.h>
34 #include <stddef.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <unistd.h>
38 #include <zone.h>
39 #include <sys/avl.h>
40 
41 #include <libzfs.h>
42 
43 #include "libzfs_impl.h"
44 
45 /*
46  * Structure to keep track of dataset state.  Before changing the 'sharenfs' or
47  * 'mountpoint' property, we record whether the filesystem was previously
48  * mounted/shared.  This prior state dictates whether we remount/reshare the
49  * dataset after the property has been changed.
50  *
51  * The interface consists of the following sequence of functions:
52  *
53  * 	changelist_gather()
54  * 	changelist_prefix()
55  * 	< change property >
56  * 	changelist_postfix()
57  * 	changelist_free()
58  *
59  * Other interfaces:
60  *
61  * changelist_remove() - remove a node from a gathered list
62  * changelist_rename() - renames all datasets appropriately when doing a rename
63  * changelist_unshare() - unshares all the nodes in a given changelist
64  * changelist_haszonedchild() - check if there is any child exported to
65  *				a local zone
66  */
67 typedef struct prop_changenode {
68 	zfs_handle_t		*cn_handle;
69 	int			cn_shared;
70 	int			cn_mounted;
71 	int			cn_zoned;
72 	boolean_t		cn_needpost;	/* is postfix() needed? */
73 	avl_node_t		cn_treenode;
74 } prop_changenode_t;
75 
76 struct prop_changelist {
77 	zfs_prop_t		cl_prop;
78 	zfs_prop_t		cl_realprop;
79 	zfs_prop_t		cl_shareprop;  /* used with sharenfs/sharesmb */
80 	avl_tree_t		cl_tree;
81 	boolean_t		cl_waslegacy;
82 	boolean_t		cl_allchildren;
83 	boolean_t		cl_alldependents;
84 	int			cl_mflags;	/* Mount flags */
85 	int			cl_gflags;	/* Gather request flags */
86 	boolean_t		cl_haszonedchild;
87 };
88 
89 /*
90  * If the property is 'mountpoint', go through and unmount filesystems as
91  * necessary.  We don't do the same for 'sharenfs', because we can just re-share
92  * with different options without interrupting service. We do handle 'sharesmb'
93  * since there may be old resource names that need to be removed.
94  */
95 int
changelist_prefix(prop_changelist_t * clp)96 changelist_prefix(prop_changelist_t *clp)
97 {
98 	prop_changenode_t *cn;
99 	int ret = 0;
100 	const enum sa_protocol smb[] = {SA_PROTOCOL_SMB, SA_NO_PROTOCOL};
101 	boolean_t commit_smb_shares = B_FALSE;
102 
103 	if (clp->cl_prop != ZFS_PROP_MOUNTPOINT &&
104 	    clp->cl_prop != ZFS_PROP_SHARESMB)
105 		return (0);
106 
107 	/*
108 	 * If CL_GATHER_DONT_UNMOUNT is set, don't want to unmount/unshare and
109 	 * later (re)mount/(re)share the filesystem in postfix phase, so we
110 	 * return from here. If filesystem is mounted or unmounted, leave it
111 	 * as it is.
112 	 */
113 	if (clp->cl_gflags & CL_GATHER_DONT_UNMOUNT)
114 		return (0);
115 
116 	for (cn = avl_first(&clp->cl_tree); cn != NULL;
117 	    cn = AVL_NEXT(&clp->cl_tree, cn)) {
118 
119 		/* if a previous loop failed, set the remaining to false */
120 		if (ret == -1) {
121 			cn->cn_needpost = B_FALSE;
122 			continue;
123 		}
124 
125 		/*
126 		 * If we are in the global zone, but this dataset is exported
127 		 * to a local zone, do nothing.
128 		 */
129 		if (getzoneid() == GLOBAL_ZONEID && cn->cn_zoned)
130 			continue;
131 
132 		if (!ZFS_IS_VOLUME(cn->cn_handle)) {
133 			/*
134 			 * Do the property specific processing.
135 			 */
136 			switch (clp->cl_prop) {
137 			case ZFS_PROP_MOUNTPOINT:
138 				if (zfs_unmount(cn->cn_handle, NULL,
139 				    clp->cl_mflags) != 0) {
140 					ret = -1;
141 					cn->cn_needpost = B_FALSE;
142 				}
143 				break;
144 			case ZFS_PROP_SHARESMB:
145 				(void) zfs_unshare(cn->cn_handle, NULL,
146 				    smb);
147 				commit_smb_shares = B_TRUE;
148 				break;
149 
150 			default:
151 				break;
152 			}
153 		}
154 	}
155 
156 	if (commit_smb_shares)
157 		zfs_commit_shares(smb);
158 
159 	if (ret == -1)
160 		(void) changelist_postfix(clp);
161 
162 	return (ret);
163 }
164 
165 /*
166  * If the property is 'mountpoint' or 'sharenfs', go through and remount and/or
167  * reshare the filesystems as necessary.  In changelist_gather() we recorded
168  * whether the filesystem was previously shared or mounted.  The action we take
169  * depends on the previous state, and whether the value was previously 'legacy'.
170  * For non-legacy properties, we always remount/reshare the filesystem,
171  * if CL_GATHER_DONT_UNMOUNT is not set.
172  */
173 int
changelist_postfix(prop_changelist_t * clp)174 changelist_postfix(prop_changelist_t *clp)
175 {
176 	prop_changenode_t *cn;
177 	char shareopts[ZFS_MAXPROPLEN];
178 	boolean_t commit_smb_shares = B_FALSE;
179 	boolean_t commit_nfs_shares = B_FALSE;
180 	int rc = 0;
181 
182 	/*
183 	 * If CL_GATHER_DONT_UNMOUNT is set, it means we don't want to (un)mount
184 	 * or (re/un)share the filesystem, so we return from here. If filesystem
185 	 * is mounted or unmounted, leave it as it is.
186 	 */
187 	if (clp->cl_gflags & CL_GATHER_DONT_UNMOUNT)
188 		return (0);
189 
190 	/*
191 	 * If we're changing the mountpoint, attempt to destroy the underlying
192 	 * mountpoint.  All other datasets will have inherited from this dataset
193 	 * (in which case their mountpoints exist in the filesystem in the new
194 	 * location), or have explicit mountpoints set (in which case they won't
195 	 * be in the changelist).
196 	 */
197 	if ((cn = avl_last(&clp->cl_tree)) == NULL)
198 		return (0);
199 
200 	if (clp->cl_prop == ZFS_PROP_MOUNTPOINT &&
201 	    !(clp->cl_gflags & CL_GATHER_DONT_UNMOUNT))
202 		remove_mountpoint(cn->cn_handle);
203 
204 	/*
205 	 * We walk the datasets in reverse, because we want to mount any parent
206 	 * datasets before mounting the children.  We walk all datasets even if
207 	 * there are errors.
208 	 */
209 	for (cn = avl_last(&clp->cl_tree); cn != NULL;
210 	    cn = AVL_PREV(&clp->cl_tree, cn)) {
211 
212 		boolean_t sharenfs;
213 		boolean_t sharesmb;
214 		boolean_t mounted;
215 		boolean_t needs_key;
216 
217 		/*
218 		 * If we are in the global zone, but this dataset is exported
219 		 * to a local zone, do nothing.
220 		 */
221 		if (getzoneid() == GLOBAL_ZONEID && cn->cn_zoned)
222 			continue;
223 
224 		/* Only do post-processing if it's required */
225 		if (!cn->cn_needpost)
226 			continue;
227 		cn->cn_needpost = B_FALSE;
228 
229 		zfs_refresh_properties(cn->cn_handle);
230 
231 		if (ZFS_IS_VOLUME(cn->cn_handle))
232 			continue;
233 
234 		/*
235 		 * Remount if previously mounted or mountpoint was legacy,
236 		 * or sharenfs or sharesmb  property is set.
237 		 */
238 		sharenfs = ((zfs_prop_get(cn->cn_handle, ZFS_PROP_SHARENFS,
239 		    shareopts, sizeof (shareopts), NULL, NULL, 0,
240 		    B_FALSE) == 0) && (strcmp(shareopts, "off") != 0));
241 
242 		sharesmb = ((zfs_prop_get(cn->cn_handle, ZFS_PROP_SHARESMB,
243 		    shareopts, sizeof (shareopts), NULL, NULL, 0,
244 		    B_FALSE) == 0) && (strcmp(shareopts, "off") != 0));
245 
246 		needs_key = (zfs_prop_get_int(cn->cn_handle,
247 		    ZFS_PROP_KEYSTATUS) == ZFS_KEYSTATUS_UNAVAILABLE);
248 
249 		mounted = zfs_is_mounted(cn->cn_handle, NULL);
250 
251 		if (!mounted && !needs_key && (cn->cn_mounted ||
252 		    (((clp->cl_prop == ZFS_PROP_MOUNTPOINT &&
253 		    clp->cl_prop == clp->cl_realprop) ||
254 		    sharenfs || sharesmb || clp->cl_waslegacy) &&
255 		    (zfs_prop_get_int(cn->cn_handle,
256 		    ZFS_PROP_CANMOUNT) == ZFS_CANMOUNT_ON)))) {
257 
258 			if (zfs_mount(cn->cn_handle, NULL, 0) == 0)
259 				mounted = TRUE;
260 		}
261 
262 		/*
263 		 * If the file system is mounted we always re-share even
264 		 * if the filesystem is currently shared, so that we can
265 		 * adopt any new options.
266 		 */
267 		const enum sa_protocol nfs[] =
268 		    {SA_PROTOCOL_NFS, SA_NO_PROTOCOL};
269 		if (sharenfs && mounted) {
270 			rc = zfs_share(cn->cn_handle, nfs);
271 			commit_nfs_shares = B_TRUE;
272 		} else if (cn->cn_shared || clp->cl_waslegacy) {
273 			zfs_unshare(cn->cn_handle, NULL, nfs);
274 			commit_nfs_shares = B_TRUE;
275 		}
276 		const enum sa_protocol smb[] =
277 		    {SA_PROTOCOL_SMB, SA_NO_PROTOCOL};
278 		if (sharesmb && mounted) {
279 			rc = zfs_share(cn->cn_handle, smb);
280 			commit_smb_shares = B_TRUE;
281 		} else if (cn->cn_shared || clp->cl_waslegacy) {
282 			zfs_unshare(cn->cn_handle, NULL, smb);
283 			commit_smb_shares = B_TRUE;
284 		}
285 	}
286 
287 	enum sa_protocol proto[SA_PROTOCOL_COUNT + 1], *p = proto;
288 	if (commit_nfs_shares)
289 		*p++ = SA_PROTOCOL_NFS;
290 	if (commit_smb_shares)
291 		*p++ = SA_PROTOCOL_SMB;
292 	*p++ = SA_NO_PROTOCOL;
293 	zfs_commit_shares(proto);
294 
295 	/*
296 	 * It's possible rc != 0 since we set a mountpoint or option while
297 	 * SMB/NFS was not running.  This is fine, and we should not return
298 	 * an error up the stack.
299 	 *
300 	 * At this point we only want to report mountpoint/shareops parsing
301 	 * errors.
302 	 */
303 	return (rc == SA_SYNTAX_ERR ? rc : 0);
304 }
305 
306 /*
307  * Is this "dataset" a child of "parent"?
308  */
309 static boolean_t
isa_child_of(const char * dataset,const char * parent)310 isa_child_of(const char *dataset, const char *parent)
311 {
312 	int len;
313 
314 	len = strlen(parent);
315 
316 	if (strncmp(dataset, parent, len) == 0 &&
317 	    (dataset[len] == '@' || dataset[len] == '/' ||
318 	    dataset[len] == '\0'))
319 		return (B_TRUE);
320 	else
321 		return (B_FALSE);
322 
323 }
324 
325 /*
326  * If we rename a filesystem, child filesystem handles are no longer valid
327  * since we identify each dataset by its name in the ZFS namespace.  As a
328  * result, we have to go through and fix up all the names appropriately.  We
329  * could do this automatically if libzfs kept track of all open handles, but
330  * this is a lot less work.
331  */
332 void
changelist_rename(prop_changelist_t * clp,const char * src,const char * dst)333 changelist_rename(prop_changelist_t *clp, const char *src, const char *dst)
334 {
335 	prop_changenode_t *cn;
336 	char newname[ZFS_MAX_DATASET_NAME_LEN];
337 
338 	for (cn = avl_first(&clp->cl_tree); cn != NULL;
339 	    cn = AVL_NEXT(&clp->cl_tree, cn)) {
340 		/*
341 		 * Do not rename a clone that's not in the source hierarchy.
342 		 */
343 		if (!isa_child_of(cn->cn_handle->zfs_name, src))
344 			continue;
345 
346 		/*
347 		 * Destroy the previous mountpoint if needed.
348 		 */
349 		remove_mountpoint(cn->cn_handle);
350 
351 		(void) strlcpy(newname, dst, sizeof (newname));
352 		(void) strlcat(newname, cn->cn_handle->zfs_name + strlen(src),
353 		    sizeof (newname));
354 
355 		(void) strlcpy(cn->cn_handle->zfs_name, newname,
356 		    sizeof (cn->cn_handle->zfs_name));
357 	}
358 }
359 
360 /*
361  * Given a gathered changelist for the 'sharenfs' or 'sharesmb' property,
362  * unshare all the datasets in the list.
363  */
364 int
changelist_unshare(prop_changelist_t * clp,const enum sa_protocol * proto)365 changelist_unshare(prop_changelist_t *clp, const enum sa_protocol *proto)
366 {
367 	prop_changenode_t *cn;
368 	int ret = 0;
369 
370 	if (clp->cl_prop != ZFS_PROP_SHARENFS &&
371 	    clp->cl_prop != ZFS_PROP_SHARESMB)
372 		return (0);
373 
374 	for (cn = avl_first(&clp->cl_tree); cn != NULL;
375 	    cn = AVL_NEXT(&clp->cl_tree, cn)) {
376 		if (zfs_unshare(cn->cn_handle, NULL, proto) != 0)
377 			ret = -1;
378 	}
379 
380 	for (const enum sa_protocol *p = proto; *p != SA_NO_PROTOCOL; ++p)
381 		sa_commit_shares(*p);
382 
383 	return (ret);
384 }
385 
386 /*
387  * Check if there is any child exported to a local zone in a given changelist.
388  * This information has already been recorded while gathering the changelist
389  * via changelist_gather().
390  */
391 int
changelist_haszonedchild(prop_changelist_t * clp)392 changelist_haszonedchild(prop_changelist_t *clp)
393 {
394 	return (clp->cl_haszonedchild);
395 }
396 
397 /*
398  * Remove a node from a gathered list.
399  */
400 void
changelist_remove(prop_changelist_t * clp,const char * name)401 changelist_remove(prop_changelist_t *clp, const char *name)
402 {
403 	prop_changenode_t *cn;
404 
405 	for (cn = avl_first(&clp->cl_tree); cn != NULL;
406 	    cn = AVL_NEXT(&clp->cl_tree, cn)) {
407 		if (strcmp(cn->cn_handle->zfs_name, name) == 0) {
408 			avl_remove(&clp->cl_tree, cn);
409 			zfs_close(cn->cn_handle);
410 			free(cn);
411 			return;
412 		}
413 	}
414 }
415 
416 /*
417  * Release any memory associated with a changelist.
418  */
419 void
changelist_free(prop_changelist_t * clp)420 changelist_free(prop_changelist_t *clp)
421 {
422 	prop_changenode_t *cn;
423 	void *cookie = NULL;
424 
425 	while ((cn = avl_destroy_nodes(&clp->cl_tree, &cookie)) != NULL) {
426 		zfs_close(cn->cn_handle);
427 		free(cn);
428 	}
429 
430 	avl_destroy(&clp->cl_tree);
431 	free(clp);
432 }
433 
434 /*
435  * Add one dataset to changelist
436  */
437 static int
changelist_add_mounted(zfs_handle_t * zhp,void * data)438 changelist_add_mounted(zfs_handle_t *zhp, void *data)
439 {
440 	prop_changelist_t *clp = data;
441 	prop_changenode_t *cn;
442 	avl_index_t idx;
443 
444 	ASSERT3U(clp->cl_prop, ==, ZFS_PROP_MOUNTPOINT);
445 
446 	cn = zfs_alloc(zfs_get_handle(zhp), sizeof (prop_changenode_t));
447 	cn->cn_handle = zhp;
448 	cn->cn_mounted = zfs_is_mounted(zhp, NULL);
449 	ASSERT3U(cn->cn_mounted, ==, B_TRUE);
450 	cn->cn_shared = zfs_is_shared(zhp, NULL, NULL);
451 	cn->cn_zoned = zfs_prop_get_int(zhp, ZFS_PROP_ZONED);
452 	cn->cn_needpost = B_TRUE;
453 
454 	/* Indicate if any child is exported to a local zone. */
455 	if (getzoneid() == GLOBAL_ZONEID && cn->cn_zoned)
456 		clp->cl_haszonedchild = B_TRUE;
457 
458 	if (avl_find(&clp->cl_tree, cn, &idx) == NULL) {
459 		avl_insert(&clp->cl_tree, cn, idx);
460 	} else {
461 		free(cn);
462 		zfs_close(zhp);
463 	}
464 
465 	return (0);
466 }
467 
468 static int
change_one(zfs_handle_t * zhp,void * data)469 change_one(zfs_handle_t *zhp, void *data)
470 {
471 	prop_changelist_t *clp = data;
472 	char property[ZFS_MAXPROPLEN];
473 	char where[64];
474 	prop_changenode_t *cn = NULL;
475 	zprop_source_t sourcetype = ZPROP_SRC_NONE;
476 	zprop_source_t share_sourcetype = ZPROP_SRC_NONE;
477 	int ret = 0;
478 
479 	/*
480 	 * We only want to unmount/unshare those filesystems that may inherit
481 	 * from the target filesystem.  If we find any filesystem with a
482 	 * locally set mountpoint, we ignore any children since changing the
483 	 * property will not affect them.  If this is a rename, we iterate
484 	 * over all children regardless, since we need them unmounted in
485 	 * order to do the rename.  Also, if this is a volume and we're doing
486 	 * a rename, then always add it to the changelist.
487 	 */
488 
489 	if (!(ZFS_IS_VOLUME(zhp) && clp->cl_realprop == ZFS_PROP_NAME) &&
490 	    zfs_prop_get(zhp, clp->cl_prop, property,
491 	    sizeof (property), &sourcetype, where, sizeof (where),
492 	    B_FALSE) != 0) {
493 		goto out;
494 	}
495 
496 	/*
497 	 * If we are "watching" sharenfs or sharesmb
498 	 * then check out the companion property which is tracked
499 	 * in cl_shareprop
500 	 */
501 	if (clp->cl_shareprop != ZPROP_INVAL &&
502 	    zfs_prop_get(zhp, clp->cl_shareprop, property,
503 	    sizeof (property), &share_sourcetype, where, sizeof (where),
504 	    B_FALSE) != 0) {
505 		goto out;
506 	}
507 
508 	if (clp->cl_alldependents || clp->cl_allchildren ||
509 	    sourcetype == ZPROP_SRC_DEFAULT ||
510 	    sourcetype == ZPROP_SRC_INHERITED ||
511 	    (clp->cl_shareprop != ZPROP_INVAL &&
512 	    (share_sourcetype == ZPROP_SRC_DEFAULT ||
513 	    share_sourcetype == ZPROP_SRC_INHERITED))) {
514 		cn = zfs_alloc(zfs_get_handle(zhp), sizeof (prop_changenode_t));
515 		cn->cn_handle = zhp;
516 		cn->cn_mounted = (clp->cl_gflags & CL_GATHER_MOUNT_ALWAYS) ||
517 		    zfs_is_mounted(zhp, NULL);
518 		cn->cn_shared = zfs_is_shared(zhp, NULL, NULL);
519 		cn->cn_zoned = zfs_prop_get_int(zhp, ZFS_PROP_ZONED);
520 		cn->cn_needpost = B_TRUE;
521 
522 		/* Indicate if any child is exported to a local zone. */
523 		if (getzoneid() == GLOBAL_ZONEID && cn->cn_zoned)
524 			clp->cl_haszonedchild = B_TRUE;
525 
526 		avl_index_t idx;
527 		if (avl_find(&clp->cl_tree, cn, &idx) == NULL) {
528 			avl_insert(&clp->cl_tree, cn, idx);
529 		} else {
530 			free(cn);
531 			cn = NULL;
532 		}
533 
534 		if (!clp->cl_alldependents) {
535 			if (clp->cl_prop != ZFS_PROP_MOUNTPOINT) {
536 				ret = zfs_iter_filesystems_v2(zhp, 0,
537 				    change_one, data);
538 			} else {
539 				ret = zfs_iter_children_v2(zhp, 0, change_one,
540 				    data);
541 			}
542 		}
543 
544 		/*
545 		 * If we added the handle to the changelist, we will re-use it
546 		 * later so return without closing it.
547 		 */
548 		if (cn != NULL)
549 			return (ret);
550 	}
551 
552 out:
553 	zfs_close(zhp);
554 	return (ret);
555 }
556 
557 static int
compare_props(const void * a,const void * b,zfs_prop_t prop)558 compare_props(const void *a, const void *b, zfs_prop_t prop)
559 {
560 	const prop_changenode_t *ca = a;
561 	const prop_changenode_t *cb = b;
562 
563 	char propa[MAXPATHLEN];
564 	char propb[MAXPATHLEN];
565 
566 	boolean_t haspropa, haspropb;
567 
568 	haspropa = (zfs_prop_get(ca->cn_handle, prop, propa, sizeof (propa),
569 	    NULL, NULL, 0, B_FALSE) == 0);
570 	haspropb = (zfs_prop_get(cb->cn_handle, prop, propb, sizeof (propb),
571 	    NULL, NULL, 0, B_FALSE) == 0);
572 
573 	if (!haspropa && haspropb)
574 		return (-1);
575 	else if (haspropa && !haspropb)
576 		return (1);
577 	else if (!haspropa && !haspropb)
578 		return (0);
579 	else
580 		return (TREE_ISIGN(strcmp(propb, propa)));
581 }
582 
583 static int
compare_mountpoints(const void * a,const void * b)584 compare_mountpoints(const void *a, const void *b)
585 {
586 	/*
587 	 * When unsharing or unmounting filesystems, we need to do it in
588 	 * mountpoint order.  This allows the user to have a mountpoint
589 	 * hierarchy that is different from the dataset hierarchy, and still
590 	 * allow it to be changed.
591 	 */
592 	return (compare_props(a, b, ZFS_PROP_MOUNTPOINT));
593 }
594 
595 static int
compare_dataset_names(const void * a,const void * b)596 compare_dataset_names(const void *a, const void *b)
597 {
598 	return (compare_props(a, b, ZFS_PROP_NAME));
599 }
600 
601 /*
602  * Given a ZFS handle and a property, construct a complete list of datasets
603  * that need to be modified as part of this process.  For anything but the
604  * 'mountpoint' and 'sharenfs' properties, this just returns an empty list.
605  * Otherwise, we iterate over all children and look for any datasets that
606  * inherit the property.  For each such dataset, we add it to the list and
607  * mark whether it was shared beforehand.
608  */
609 prop_changelist_t *
changelist_gather(zfs_handle_t * zhp,zfs_prop_t prop,int gather_flags,int mnt_flags)610 changelist_gather(zfs_handle_t *zhp, zfs_prop_t prop, int gather_flags,
611     int mnt_flags)
612 {
613 	prop_changelist_t *clp;
614 	prop_changenode_t *cn;
615 	zfs_handle_t *temp;
616 	char property[ZFS_MAXPROPLEN];
617 	boolean_t legacy = B_FALSE;
618 
619 	clp = zfs_alloc(zhp->zfs_hdl, sizeof (prop_changelist_t));
620 
621 	/*
622 	 * For mountpoint-related tasks, we want to sort everything by
623 	 * mountpoint, so that we mount and unmount them in the appropriate
624 	 * order, regardless of their position in the hierarchy.
625 	 */
626 	if (prop == ZFS_PROP_NAME || prop == ZFS_PROP_ZONED ||
627 	    prop == ZFS_PROP_MOUNTPOINT || prop == ZFS_PROP_SHARENFS ||
628 	    prop == ZFS_PROP_SHARESMB) {
629 
630 		if (zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT,
631 		    property, sizeof (property),
632 		    NULL, NULL, 0, B_FALSE) == 0 &&
633 		    (strcmp(property, "legacy") == 0 ||
634 		    strcmp(property, "none") == 0)) {
635 			legacy = B_TRUE;
636 		}
637 	}
638 
639 	avl_create(&clp->cl_tree,
640 	    legacy ? compare_dataset_names : compare_mountpoints,
641 	    sizeof (prop_changenode_t),
642 	    offsetof(prop_changenode_t, cn_treenode));
643 
644 	clp->cl_gflags = gather_flags;
645 	clp->cl_mflags = mnt_flags;
646 
647 	/*
648 	 * If this is a rename or the 'zoned' property, we pretend we're
649 	 * changing the mountpoint and flag it so we can catch all children in
650 	 * change_one().
651 	 *
652 	 * Flag cl_alldependents to catch all children plus the dependents
653 	 * (clones) that are not in the hierarchy.
654 	 */
655 	if (prop == ZFS_PROP_NAME) {
656 		clp->cl_prop = ZFS_PROP_MOUNTPOINT;
657 		clp->cl_alldependents = B_TRUE;
658 	} else if (prop == ZFS_PROP_ZONED) {
659 		clp->cl_prop = ZFS_PROP_MOUNTPOINT;
660 		clp->cl_allchildren = B_TRUE;
661 	} else if (prop == ZFS_PROP_CANMOUNT) {
662 		clp->cl_prop = ZFS_PROP_MOUNTPOINT;
663 	} else if (prop == ZFS_PROP_VOLSIZE) {
664 		clp->cl_prop = ZFS_PROP_MOUNTPOINT;
665 	} else {
666 		clp->cl_prop = prop;
667 	}
668 	clp->cl_realprop = prop;
669 
670 	if (clp->cl_prop != ZFS_PROP_MOUNTPOINT &&
671 	    clp->cl_prop != ZFS_PROP_SHARENFS &&
672 	    clp->cl_prop != ZFS_PROP_SHARESMB)
673 		return (clp);
674 
675 	/*
676 	 * If watching SHARENFS or SHARESMB then
677 	 * also watch its companion property.
678 	 */
679 	if (clp->cl_prop == ZFS_PROP_SHARENFS)
680 		clp->cl_shareprop = ZFS_PROP_SHARESMB;
681 	else if (clp->cl_prop == ZFS_PROP_SHARESMB)
682 		clp->cl_shareprop = ZFS_PROP_SHARENFS;
683 
684 	if (clp->cl_prop == ZFS_PROP_MOUNTPOINT &&
685 	    (clp->cl_gflags & CL_GATHER_ITER_MOUNTED)) {
686 		/*
687 		 * Instead of iterating through all of the dataset children we
688 		 * gather mounted dataset children from MNTTAB
689 		 */
690 		if (zfs_iter_mounted(zhp, changelist_add_mounted, clp) != 0) {
691 			changelist_free(clp);
692 			return (NULL);
693 		}
694 	} else if (clp->cl_alldependents) {
695 		if (zfs_iter_dependents_v2(zhp, 0, B_TRUE, change_one,
696 		    clp) != 0) {
697 			changelist_free(clp);
698 			return (NULL);
699 		}
700 	} else if (clp->cl_prop != ZFS_PROP_MOUNTPOINT) {
701 		if (zfs_iter_filesystems_v2(zhp, 0, change_one, clp) != 0) {
702 			changelist_free(clp);
703 			return (NULL);
704 		}
705 	} else if (zfs_iter_children_v2(zhp, 0, change_one, clp) != 0) {
706 		changelist_free(clp);
707 		return (NULL);
708 	}
709 
710 	/*
711 	 * We have to re-open ourselves because we auto-close all the handles
712 	 * and can't tell the difference.
713 	 */
714 	if ((temp = zfs_open(zhp->zfs_hdl, zfs_get_name(zhp),
715 	    ZFS_TYPE_DATASET)) == NULL) {
716 		changelist_free(clp);
717 		return (NULL);
718 	}
719 
720 	/*
721 	 * Always add ourself to the list.  We add ourselves to the end so that
722 	 * we're the last to be unmounted.
723 	 */
724 	cn = zfs_alloc(zhp->zfs_hdl, sizeof (prop_changenode_t));
725 	cn->cn_handle = temp;
726 	cn->cn_mounted = (clp->cl_gflags & CL_GATHER_MOUNT_ALWAYS) ||
727 	    zfs_is_mounted(temp, NULL);
728 	cn->cn_shared = zfs_is_shared(temp, NULL, NULL);
729 	cn->cn_zoned = zfs_prop_get_int(zhp, ZFS_PROP_ZONED);
730 	cn->cn_needpost = B_TRUE;
731 
732 	avl_index_t idx;
733 	if (avl_find(&clp->cl_tree, cn, &idx) == NULL) {
734 		avl_insert(&clp->cl_tree, cn, idx);
735 	} else {
736 		free(cn);
737 		zfs_close(temp);
738 	}
739 
740 	/*
741 	 * If the mountpoint property was previously 'legacy', or 'none',
742 	 * record it as the behavior of changelist_postfix() will be different.
743 	 */
744 	if ((clp->cl_prop == ZFS_PROP_MOUNTPOINT) && legacy) {
745 		/*
746 		 * do not automatically mount ex-legacy datasets if
747 		 * we specifically set canmount to noauto
748 		 */
749 		if (zfs_prop_get_int(zhp, ZFS_PROP_CANMOUNT) !=
750 		    ZFS_CANMOUNT_NOAUTO)
751 			clp->cl_waslegacy = B_TRUE;
752 	}
753 
754 	return (clp);
755 }
756