xref: /freebsd/sys/contrib/openzfs/module/zfs/vdev_label.c (revision b59a0cde6a5253f94494397ce5b18dbfa071e08c)
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 https://opensource.org/licenses/CDDL-1.0.
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 /*
23  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
24  * Copyright (c) 2012, 2020 by Delphix. All rights reserved.
25  * Copyright (c) 2017, Intel Corporation.
26  */
27 
28 /*
29  * Virtual Device Labels
30  * ---------------------
31  *
32  * The vdev label serves several distinct purposes:
33  *
34  *	1. Uniquely identify this device as part of a ZFS pool and confirm its
35  *	   identity within the pool.
36  *
37  *	2. Verify that all the devices given in a configuration are present
38  *         within the pool.
39  *
40  *	3. Determine the uberblock for the pool.
41  *
42  *	4. In case of an import operation, determine the configuration of the
43  *         toplevel vdev of which it is a part.
44  *
45  *	5. If an import operation cannot find all the devices in the pool,
46  *         provide enough information to the administrator to determine which
47  *         devices are missing.
48  *
49  * It is important to note that while the kernel is responsible for writing the
50  * label, it only consumes the information in the first three cases.  The
51  * latter information is only consumed in userland when determining the
52  * configuration to import a pool.
53  *
54  *
55  * Label Organization
56  * ------------------
57  *
58  * Before describing the contents of the label, it's important to understand how
59  * the labels are written and updated with respect to the uberblock.
60  *
61  * When the pool configuration is altered, either because it was newly created
62  * or a device was added, we want to update all the labels such that we can deal
63  * with fatal failure at any point.  To this end, each disk has two labels which
64  * are updated before and after the uberblock is synced.  Assuming we have
65  * labels and an uberblock with the following transaction groups:
66  *
67  *              L1          UB          L2
68  *           +------+    +------+    +------+
69  *           |      |    |      |    |      |
70  *           | t10  |    | t10  |    | t10  |
71  *           |      |    |      |    |      |
72  *           +------+    +------+    +------+
73  *
74  * In this stable state, the labels and the uberblock were all updated within
75  * the same transaction group (10).  Each label is mirrored and checksummed, so
76  * that we can detect when we fail partway through writing the label.
77  *
78  * In order to identify which labels are valid, the labels are written in the
79  * following manner:
80  *
81  *	1. For each vdev, update 'L1' to the new label
82  *	2. Update the uberblock
83  *	3. For each vdev, update 'L2' to the new label
84  *
85  * Given arbitrary failure, we can determine the correct label to use based on
86  * the transaction group.  If we fail after updating L1 but before updating the
87  * UB, we will notice that L1's transaction group is greater than the uberblock,
88  * so L2 must be valid.  If we fail after writing the uberblock but before
89  * writing L2, we will notice that L2's transaction group is less than L1, and
90  * therefore L1 is valid.
91  *
92  * Another added complexity is that not every label is updated when the config
93  * is synced.  If we add a single device, we do not want to have to re-write
94  * every label for every device in the pool.  This means that both L1 and L2 may
95  * be older than the pool uberblock, because the necessary information is stored
96  * on another vdev.
97  *
98  *
99  * On-disk Format
100  * --------------
101  *
102  * The vdev label consists of two distinct parts, and is wrapped within the
103  * vdev_label_t structure.  The label includes 8k of padding to permit legacy
104  * VTOC disk labels, but is otherwise ignored.
105  *
106  * The first half of the label is a packed nvlist which contains pool wide
107  * properties, per-vdev properties, and configuration information.  It is
108  * described in more detail below.
109  *
110  * The latter half of the label consists of a redundant array of uberblocks.
111  * These uberblocks are updated whenever a transaction group is committed,
112  * or when the configuration is updated.  When a pool is loaded, we scan each
113  * vdev for the 'best' uberblock.
114  *
115  *
116  * Configuration Information
117  * -------------------------
118  *
119  * The nvlist describing the pool and vdev contains the following elements:
120  *
121  *	version		ZFS on-disk version
122  *	name		Pool name
123  *	state		Pool state
124  *	txg		Transaction group in which this label was written
125  *	pool_guid	Unique identifier for this pool
126  *	vdev_tree	An nvlist describing vdev tree.
127  *	features_for_read
128  *			An nvlist of the features necessary for reading the MOS.
129  *
130  * Each leaf device label also contains the following:
131  *
132  *	top_guid	Unique ID for top-level vdev in which this is contained
133  *	guid		Unique ID for the leaf vdev
134  *
135  * The 'vs' configuration follows the format described in 'spa_config.c'.
136  */
137 
138 #include <sys/zfs_context.h>
139 #include <sys/spa.h>
140 #include <sys/spa_impl.h>
141 #include <sys/dmu.h>
142 #include <sys/zap.h>
143 #include <sys/vdev.h>
144 #include <sys/vdev_impl.h>
145 #include <sys/vdev_raidz.h>
146 #include <sys/vdev_draid.h>
147 #include <sys/uberblock_impl.h>
148 #include <sys/metaslab.h>
149 #include <sys/metaslab_impl.h>
150 #include <sys/zio.h>
151 #include <sys/dsl_scan.h>
152 #include <sys/abd.h>
153 #include <sys/fs/zfs.h>
154 #include <sys/byteorder.h>
155 #include <sys/zfs_bootenv.h>
156 
157 /*
158  * Basic routines to read and write from a vdev label.
159  * Used throughout the rest of this file.
160  */
161 uint64_t
vdev_label_offset(uint64_t psize,int l,uint64_t offset)162 vdev_label_offset(uint64_t psize, int l, uint64_t offset)
163 {
164 	ASSERT(offset < sizeof (vdev_label_t));
165 	ASSERT(P2PHASE_TYPED(psize, sizeof (vdev_label_t), uint64_t) == 0);
166 
167 	return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ?
168 	    0 : psize - VDEV_LABELS * sizeof (vdev_label_t)));
169 }
170 
171 /*
172  * Returns back the vdev label associated with the passed in offset.
173  */
174 int
vdev_label_number(uint64_t psize,uint64_t offset)175 vdev_label_number(uint64_t psize, uint64_t offset)
176 {
177 	int l;
178 
179 	if (offset >= psize - VDEV_LABEL_END_SIZE) {
180 		offset -= psize - VDEV_LABEL_END_SIZE;
181 		offset += (VDEV_LABELS / 2) * sizeof (vdev_label_t);
182 	}
183 	l = offset / sizeof (vdev_label_t);
184 	return (l < VDEV_LABELS ? l : -1);
185 }
186 
187 static void
vdev_label_read(zio_t * zio,vdev_t * vd,int l,abd_t * buf,uint64_t offset,uint64_t size,zio_done_func_t * done,void * private,int flags)188 vdev_label_read(zio_t *zio, vdev_t *vd, int l, abd_t *buf, uint64_t offset,
189     uint64_t size, zio_done_func_t *done, void *private, int flags)
190 {
191 	ASSERT(
192 	    spa_config_held(zio->io_spa, SCL_STATE, RW_READER) == SCL_STATE ||
193 	    spa_config_held(zio->io_spa, SCL_STATE, RW_WRITER) == SCL_STATE);
194 	ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
195 
196 	zio_nowait(zio_read_phys(zio, vd,
197 	    vdev_label_offset(vd->vdev_psize, l, offset),
198 	    size, buf, ZIO_CHECKSUM_LABEL, done, private,
199 	    ZIO_PRIORITY_SYNC_READ, flags, B_TRUE));
200 }
201 
202 void
vdev_label_write(zio_t * zio,vdev_t * vd,int l,abd_t * buf,uint64_t offset,uint64_t size,zio_done_func_t * done,void * private,int flags)203 vdev_label_write(zio_t *zio, vdev_t *vd, int l, abd_t *buf, uint64_t offset,
204     uint64_t size, zio_done_func_t *done, void *private, int flags)
205 {
206 	ASSERT(
207 	    spa_config_held(zio->io_spa, SCL_STATE, RW_READER) == SCL_STATE ||
208 	    spa_config_held(zio->io_spa, SCL_STATE, RW_WRITER) == SCL_STATE);
209 	ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
210 
211 	zio_nowait(zio_write_phys(zio, vd,
212 	    vdev_label_offset(vd->vdev_psize, l, offset),
213 	    size, buf, ZIO_CHECKSUM_LABEL, done, private,
214 	    ZIO_PRIORITY_SYNC_WRITE, flags, B_TRUE));
215 }
216 
217 /*
218  * Generate the nvlist representing this vdev's stats
219  */
220 void
vdev_config_generate_stats(vdev_t * vd,nvlist_t * nv)221 vdev_config_generate_stats(vdev_t *vd, nvlist_t *nv)
222 {
223 	nvlist_t *nvx;
224 	vdev_stat_t *vs;
225 	vdev_stat_ex_t *vsx;
226 
227 	vs = kmem_alloc(sizeof (*vs), KM_SLEEP);
228 	vsx = kmem_alloc(sizeof (*vsx), KM_SLEEP);
229 
230 	vdev_get_stats_ex(vd, vs, vsx);
231 	fnvlist_add_uint64_array(nv, ZPOOL_CONFIG_VDEV_STATS,
232 	    (uint64_t *)vs, sizeof (*vs) / sizeof (uint64_t));
233 
234 	/*
235 	 * Add extended stats into a special extended stats nvlist.  This keeps
236 	 * all the extended stats nicely grouped together.  The extended stats
237 	 * nvlist is then added to the main nvlist.
238 	 */
239 	nvx = fnvlist_alloc();
240 
241 	/* ZIOs in flight to disk */
242 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SYNC_R_ACTIVE_QUEUE,
243 	    vsx->vsx_active_queue[ZIO_PRIORITY_SYNC_READ]);
244 
245 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SYNC_W_ACTIVE_QUEUE,
246 	    vsx->vsx_active_queue[ZIO_PRIORITY_SYNC_WRITE]);
247 
248 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_ASYNC_R_ACTIVE_QUEUE,
249 	    vsx->vsx_active_queue[ZIO_PRIORITY_ASYNC_READ]);
250 
251 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_ASYNC_W_ACTIVE_QUEUE,
252 	    vsx->vsx_active_queue[ZIO_PRIORITY_ASYNC_WRITE]);
253 
254 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SCRUB_ACTIVE_QUEUE,
255 	    vsx->vsx_active_queue[ZIO_PRIORITY_SCRUB]);
256 
257 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_TRIM_ACTIVE_QUEUE,
258 	    vsx->vsx_active_queue[ZIO_PRIORITY_TRIM]);
259 
260 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_REBUILD_ACTIVE_QUEUE,
261 	    vsx->vsx_active_queue[ZIO_PRIORITY_REBUILD]);
262 
263 	/* ZIOs pending */
264 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SYNC_R_PEND_QUEUE,
265 	    vsx->vsx_pend_queue[ZIO_PRIORITY_SYNC_READ]);
266 
267 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SYNC_W_PEND_QUEUE,
268 	    vsx->vsx_pend_queue[ZIO_PRIORITY_SYNC_WRITE]);
269 
270 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_ASYNC_R_PEND_QUEUE,
271 	    vsx->vsx_pend_queue[ZIO_PRIORITY_ASYNC_READ]);
272 
273 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_ASYNC_W_PEND_QUEUE,
274 	    vsx->vsx_pend_queue[ZIO_PRIORITY_ASYNC_WRITE]);
275 
276 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SCRUB_PEND_QUEUE,
277 	    vsx->vsx_pend_queue[ZIO_PRIORITY_SCRUB]);
278 
279 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_TRIM_PEND_QUEUE,
280 	    vsx->vsx_pend_queue[ZIO_PRIORITY_TRIM]);
281 
282 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_REBUILD_PEND_QUEUE,
283 	    vsx->vsx_pend_queue[ZIO_PRIORITY_REBUILD]);
284 
285 	/* Histograms */
286 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_TOT_R_LAT_HISTO,
287 	    vsx->vsx_total_histo[ZIO_TYPE_READ],
288 	    ARRAY_SIZE(vsx->vsx_total_histo[ZIO_TYPE_READ]));
289 
290 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_TOT_W_LAT_HISTO,
291 	    vsx->vsx_total_histo[ZIO_TYPE_WRITE],
292 	    ARRAY_SIZE(vsx->vsx_total_histo[ZIO_TYPE_WRITE]));
293 
294 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_DISK_R_LAT_HISTO,
295 	    vsx->vsx_disk_histo[ZIO_TYPE_READ],
296 	    ARRAY_SIZE(vsx->vsx_disk_histo[ZIO_TYPE_READ]));
297 
298 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_DISK_W_LAT_HISTO,
299 	    vsx->vsx_disk_histo[ZIO_TYPE_WRITE],
300 	    ARRAY_SIZE(vsx->vsx_disk_histo[ZIO_TYPE_WRITE]));
301 
302 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_R_LAT_HISTO,
303 	    vsx->vsx_queue_histo[ZIO_PRIORITY_SYNC_READ],
304 	    ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_SYNC_READ]));
305 
306 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_W_LAT_HISTO,
307 	    vsx->vsx_queue_histo[ZIO_PRIORITY_SYNC_WRITE],
308 	    ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_SYNC_WRITE]));
309 
310 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_R_LAT_HISTO,
311 	    vsx->vsx_queue_histo[ZIO_PRIORITY_ASYNC_READ],
312 	    ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_ASYNC_READ]));
313 
314 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_W_LAT_HISTO,
315 	    vsx->vsx_queue_histo[ZIO_PRIORITY_ASYNC_WRITE],
316 	    ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_ASYNC_WRITE]));
317 
318 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SCRUB_LAT_HISTO,
319 	    vsx->vsx_queue_histo[ZIO_PRIORITY_SCRUB],
320 	    ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_SCRUB]));
321 
322 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_TRIM_LAT_HISTO,
323 	    vsx->vsx_queue_histo[ZIO_PRIORITY_TRIM],
324 	    ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_TRIM]));
325 
326 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_REBUILD_LAT_HISTO,
327 	    vsx->vsx_queue_histo[ZIO_PRIORITY_REBUILD],
328 	    ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_REBUILD]));
329 
330 	/* Request sizes */
331 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_IND_R_HISTO,
332 	    vsx->vsx_ind_histo[ZIO_PRIORITY_SYNC_READ],
333 	    ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_SYNC_READ]));
334 
335 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_IND_W_HISTO,
336 	    vsx->vsx_ind_histo[ZIO_PRIORITY_SYNC_WRITE],
337 	    ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_SYNC_WRITE]));
338 
339 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_IND_R_HISTO,
340 	    vsx->vsx_ind_histo[ZIO_PRIORITY_ASYNC_READ],
341 	    ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_ASYNC_READ]));
342 
343 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_IND_W_HISTO,
344 	    vsx->vsx_ind_histo[ZIO_PRIORITY_ASYNC_WRITE],
345 	    ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_ASYNC_WRITE]));
346 
347 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_IND_SCRUB_HISTO,
348 	    vsx->vsx_ind_histo[ZIO_PRIORITY_SCRUB],
349 	    ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_SCRUB]));
350 
351 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_IND_TRIM_HISTO,
352 	    vsx->vsx_ind_histo[ZIO_PRIORITY_TRIM],
353 	    ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_TRIM]));
354 
355 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_IND_REBUILD_HISTO,
356 	    vsx->vsx_ind_histo[ZIO_PRIORITY_REBUILD],
357 	    ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_REBUILD]));
358 
359 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_AGG_R_HISTO,
360 	    vsx->vsx_agg_histo[ZIO_PRIORITY_SYNC_READ],
361 	    ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_SYNC_READ]));
362 
363 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_AGG_W_HISTO,
364 	    vsx->vsx_agg_histo[ZIO_PRIORITY_SYNC_WRITE],
365 	    ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_SYNC_WRITE]));
366 
367 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_AGG_R_HISTO,
368 	    vsx->vsx_agg_histo[ZIO_PRIORITY_ASYNC_READ],
369 	    ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_ASYNC_READ]));
370 
371 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_AGG_W_HISTO,
372 	    vsx->vsx_agg_histo[ZIO_PRIORITY_ASYNC_WRITE],
373 	    ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_ASYNC_WRITE]));
374 
375 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_AGG_SCRUB_HISTO,
376 	    vsx->vsx_agg_histo[ZIO_PRIORITY_SCRUB],
377 	    ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_SCRUB]));
378 
379 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_AGG_TRIM_HISTO,
380 	    vsx->vsx_agg_histo[ZIO_PRIORITY_TRIM],
381 	    ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_TRIM]));
382 
383 	fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_AGG_REBUILD_HISTO,
384 	    vsx->vsx_agg_histo[ZIO_PRIORITY_REBUILD],
385 	    ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_REBUILD]));
386 
387 	/* IO delays */
388 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SLOW_IOS, vs->vs_slow_ios);
389 
390 	/* Direct I/O write verify errors */
391 	fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_DIO_VERIFY_ERRORS,
392 	    vs->vs_dio_verify_errors);
393 
394 	/* Add extended stats nvlist to main nvlist */
395 	fnvlist_add_nvlist(nv, ZPOOL_CONFIG_VDEV_STATS_EX, nvx);
396 
397 	fnvlist_free(nvx);
398 	kmem_free(vs, sizeof (*vs));
399 	kmem_free(vsx, sizeof (*vsx));
400 }
401 
402 static void
root_vdev_actions_getprogress(vdev_t * vd,nvlist_t * nvl)403 root_vdev_actions_getprogress(vdev_t *vd, nvlist_t *nvl)
404 {
405 	spa_t *spa = vd->vdev_spa;
406 
407 	if (vd != spa->spa_root_vdev)
408 		return;
409 
410 	/* provide either current or previous scan information */
411 	pool_scan_stat_t ps;
412 	if (spa_scan_get_stats(spa, &ps) == 0) {
413 		fnvlist_add_uint64_array(nvl,
414 		    ZPOOL_CONFIG_SCAN_STATS, (uint64_t *)&ps,
415 		    sizeof (pool_scan_stat_t) / sizeof (uint64_t));
416 	}
417 
418 	pool_removal_stat_t prs;
419 	if (spa_removal_get_stats(spa, &prs) == 0) {
420 		fnvlist_add_uint64_array(nvl,
421 		    ZPOOL_CONFIG_REMOVAL_STATS, (uint64_t *)&prs,
422 		    sizeof (prs) / sizeof (uint64_t));
423 	}
424 
425 	pool_checkpoint_stat_t pcs;
426 	if (spa_checkpoint_get_stats(spa, &pcs) == 0) {
427 		fnvlist_add_uint64_array(nvl,
428 		    ZPOOL_CONFIG_CHECKPOINT_STATS, (uint64_t *)&pcs,
429 		    sizeof (pcs) / sizeof (uint64_t));
430 	}
431 
432 	pool_raidz_expand_stat_t pres;
433 	if (spa_raidz_expand_get_stats(spa, &pres) == 0) {
434 		fnvlist_add_uint64_array(nvl,
435 		    ZPOOL_CONFIG_RAIDZ_EXPAND_STATS, (uint64_t *)&pres,
436 		    sizeof (pres) / sizeof (uint64_t));
437 	}
438 }
439 
440 static void
top_vdev_actions_getprogress(vdev_t * vd,nvlist_t * nvl)441 top_vdev_actions_getprogress(vdev_t *vd, nvlist_t *nvl)
442 {
443 	if (vd == vd->vdev_top) {
444 		vdev_rebuild_stat_t vrs;
445 		if (vdev_rebuild_get_stats(vd, &vrs) == 0) {
446 			fnvlist_add_uint64_array(nvl,
447 			    ZPOOL_CONFIG_REBUILD_STATS, (uint64_t *)&vrs,
448 			    sizeof (vrs) / sizeof (uint64_t));
449 		}
450 	}
451 }
452 
453 /*
454  * Generate the nvlist representing this vdev's config.
455  */
456 nvlist_t *
vdev_config_generate(spa_t * spa,vdev_t * vd,boolean_t getstats,vdev_config_flag_t flags)457 vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats,
458     vdev_config_flag_t flags)
459 {
460 	nvlist_t *nv = NULL;
461 	vdev_indirect_config_t *vic = &vd->vdev_indirect_config;
462 
463 	nv = fnvlist_alloc();
464 
465 	fnvlist_add_string(nv, ZPOOL_CONFIG_TYPE, vd->vdev_ops->vdev_op_type);
466 	if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)))
467 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_ID, vd->vdev_id);
468 	fnvlist_add_uint64(nv, ZPOOL_CONFIG_GUID, vd->vdev_guid);
469 
470 	if (vd->vdev_path != NULL)
471 		fnvlist_add_string(nv, ZPOOL_CONFIG_PATH, vd->vdev_path);
472 
473 	if (vd->vdev_devid != NULL)
474 		fnvlist_add_string(nv, ZPOOL_CONFIG_DEVID, vd->vdev_devid);
475 
476 	if (vd->vdev_physpath != NULL)
477 		fnvlist_add_string(nv, ZPOOL_CONFIG_PHYS_PATH,
478 		    vd->vdev_physpath);
479 
480 	if (vd->vdev_enc_sysfs_path != NULL)
481 		fnvlist_add_string(nv, ZPOOL_CONFIG_VDEV_ENC_SYSFS_PATH,
482 		    vd->vdev_enc_sysfs_path);
483 
484 	if (vd->vdev_fru != NULL)
485 		fnvlist_add_string(nv, ZPOOL_CONFIG_FRU, vd->vdev_fru);
486 
487 	if (vd->vdev_ops->vdev_op_config_generate != NULL)
488 		vd->vdev_ops->vdev_op_config_generate(vd, nv);
489 
490 	if (vd->vdev_wholedisk != -1ULL) {
491 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
492 		    vd->vdev_wholedisk);
493 	}
494 
495 	if (vd->vdev_not_present && !(flags & VDEV_CONFIG_MISSING))
496 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT, 1);
497 
498 	if (vd->vdev_isspare)
499 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_SPARE, 1);
500 
501 	if (flags & VDEV_CONFIG_L2CACHE)
502 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_ASHIFT, vd->vdev_ashift);
503 
504 	if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)) &&
505 	    vd == vd->vdev_top) {
506 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
507 		    vd->vdev_ms_array);
508 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT,
509 		    vd->vdev_ms_shift);
510 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_ASHIFT, vd->vdev_ashift);
511 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_ASIZE,
512 		    vd->vdev_asize);
513 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_LOG, vd->vdev_islog);
514 		if (vd->vdev_noalloc) {
515 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_NONALLOCATING,
516 			    vd->vdev_noalloc);
517 		}
518 
519 		/*
520 		 * Slog devices are removed synchronously so don't
521 		 * persist the vdev_removing flag to the label.
522 		 */
523 		if (vd->vdev_removing && !vd->vdev_islog) {
524 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVING,
525 			    vd->vdev_removing);
526 		}
527 
528 		/* zpool command expects alloc class data */
529 		if (getstats && vd->vdev_alloc_bias != VDEV_BIAS_NONE) {
530 			const char *bias = NULL;
531 
532 			switch (vd->vdev_alloc_bias) {
533 			case VDEV_BIAS_LOG:
534 				bias = VDEV_ALLOC_BIAS_LOG;
535 				break;
536 			case VDEV_BIAS_SPECIAL:
537 				bias = VDEV_ALLOC_BIAS_SPECIAL;
538 				break;
539 			case VDEV_BIAS_DEDUP:
540 				bias = VDEV_ALLOC_BIAS_DEDUP;
541 				break;
542 			default:
543 				ASSERT3U(vd->vdev_alloc_bias, ==,
544 				    VDEV_BIAS_NONE);
545 			}
546 			fnvlist_add_string(nv, ZPOOL_CONFIG_ALLOCATION_BIAS,
547 			    bias);
548 		}
549 	}
550 
551 	if (vd->vdev_dtl_sm != NULL) {
552 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_DTL,
553 		    space_map_object(vd->vdev_dtl_sm));
554 	}
555 
556 	if (vic->vic_mapping_object != 0) {
557 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_INDIRECT_OBJECT,
558 		    vic->vic_mapping_object);
559 	}
560 
561 	if (vic->vic_births_object != 0) {
562 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_INDIRECT_BIRTHS,
563 		    vic->vic_births_object);
564 	}
565 
566 	if (vic->vic_prev_indirect_vdev != UINT64_MAX) {
567 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_PREV_INDIRECT_VDEV,
568 		    vic->vic_prev_indirect_vdev);
569 	}
570 
571 	if (vd->vdev_crtxg)
572 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_CREATE_TXG, vd->vdev_crtxg);
573 
574 	if (vd->vdev_expansion_time)
575 		fnvlist_add_uint64(nv, ZPOOL_CONFIG_EXPANSION_TIME,
576 		    vd->vdev_expansion_time);
577 
578 	if (flags & VDEV_CONFIG_MOS) {
579 		if (vd->vdev_leaf_zap != 0) {
580 			ASSERT(vd->vdev_ops->vdev_op_leaf);
581 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_VDEV_LEAF_ZAP,
582 			    vd->vdev_leaf_zap);
583 		}
584 
585 		if (vd->vdev_top_zap != 0) {
586 			ASSERT(vd == vd->vdev_top);
587 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_VDEV_TOP_ZAP,
588 			    vd->vdev_top_zap);
589 		}
590 
591 		if (vd->vdev_ops == &vdev_root_ops && vd->vdev_root_zap != 0 &&
592 		    spa_feature_is_active(vd->vdev_spa, SPA_FEATURE_AVZ_V2)) {
593 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_VDEV_ROOT_ZAP,
594 			    vd->vdev_root_zap);
595 		}
596 
597 		if (vd->vdev_resilver_deferred) {
598 			ASSERT(vd->vdev_ops->vdev_op_leaf);
599 			ASSERT(spa->spa_resilver_deferred);
600 			fnvlist_add_boolean(nv, ZPOOL_CONFIG_RESILVER_DEFER);
601 		}
602 	}
603 
604 	if (getstats) {
605 		vdev_config_generate_stats(vd, nv);
606 
607 		root_vdev_actions_getprogress(vd, nv);
608 		top_vdev_actions_getprogress(vd, nv);
609 
610 		/*
611 		 * Note: this can be called from open context
612 		 * (spa_get_stats()), so we need the rwlock to prevent
613 		 * the mapping from being changed by condensing.
614 		 */
615 		rw_enter(&vd->vdev_indirect_rwlock, RW_READER);
616 		if (vd->vdev_indirect_mapping != NULL) {
617 			ASSERT(vd->vdev_indirect_births != NULL);
618 			vdev_indirect_mapping_t *vim =
619 			    vd->vdev_indirect_mapping;
620 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_INDIRECT_SIZE,
621 			    vdev_indirect_mapping_size(vim));
622 		}
623 		rw_exit(&vd->vdev_indirect_rwlock);
624 		if (vd->vdev_mg != NULL &&
625 		    vd->vdev_mg->mg_fragmentation != ZFS_FRAG_INVALID) {
626 			/*
627 			 * Compute approximately how much memory would be used
628 			 * for the indirect mapping if this device were to
629 			 * be removed.
630 			 *
631 			 * Note: If the frag metric is invalid, then not
632 			 * enough metaslabs have been converted to have
633 			 * histograms.
634 			 */
635 			uint64_t seg_count = 0;
636 			uint64_t to_alloc = vd->vdev_stat.vs_alloc;
637 
638 			/*
639 			 * There are the same number of allocated segments
640 			 * as free segments, so we will have at least one
641 			 * entry per free segment.  However, small free
642 			 * segments (smaller than vdev_removal_max_span)
643 			 * will be combined with adjacent allocated segments
644 			 * as a single mapping.
645 			 */
646 			for (int i = 0; i < ZFS_RANGE_TREE_HISTOGRAM_SIZE;
647 			    i++) {
648 				if (i + 1 < highbit64(vdev_removal_max_span)
649 				    - 1) {
650 					to_alloc +=
651 					    vd->vdev_mg->mg_histogram[i] <<
652 					    (i + 1);
653 				} else {
654 					seg_count +=
655 					    vd->vdev_mg->mg_histogram[i];
656 				}
657 			}
658 
659 			/*
660 			 * The maximum length of a mapping is
661 			 * zfs_remove_max_segment, so we need at least one entry
662 			 * per zfs_remove_max_segment of allocated data.
663 			 */
664 			seg_count += to_alloc / spa_remove_max_segment(spa);
665 
666 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_INDIRECT_SIZE,
667 			    seg_count *
668 			    sizeof (vdev_indirect_mapping_entry_phys_t));
669 		}
670 	}
671 
672 	if (!vd->vdev_ops->vdev_op_leaf) {
673 		nvlist_t **child;
674 		uint64_t c;
675 
676 		ASSERT(!vd->vdev_ishole);
677 
678 		child = kmem_alloc(vd->vdev_children * sizeof (nvlist_t *),
679 		    KM_SLEEP);
680 
681 		for (c = 0; c < vd->vdev_children; c++) {
682 			child[c] = vdev_config_generate(spa, vd->vdev_child[c],
683 			    getstats, flags);
684 		}
685 
686 		fnvlist_add_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
687 		    (const nvlist_t * const *)child, vd->vdev_children);
688 
689 		for (c = 0; c < vd->vdev_children; c++)
690 			nvlist_free(child[c]);
691 
692 		kmem_free(child, vd->vdev_children * sizeof (nvlist_t *));
693 
694 	} else {
695 		const char *aux = NULL;
696 
697 		if (vd->vdev_offline && !vd->vdev_tmpoffline)
698 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_OFFLINE, B_TRUE);
699 		if (vd->vdev_resilver_txg != 0)
700 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_RESILVER_TXG,
701 			    vd->vdev_resilver_txg);
702 		if (vd->vdev_rebuild_txg != 0)
703 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_REBUILD_TXG,
704 			    vd->vdev_rebuild_txg);
705 		if (vd->vdev_faulted)
706 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_FAULTED, B_TRUE);
707 		if (vd->vdev_degraded)
708 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_DEGRADED, B_TRUE);
709 		if (vd->vdev_removed)
710 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVED, B_TRUE);
711 		if (vd->vdev_unspare)
712 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_UNSPARE, B_TRUE);
713 		if (vd->vdev_ishole)
714 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_HOLE, B_TRUE);
715 
716 		/* Set the reason why we're FAULTED/DEGRADED. */
717 		switch (vd->vdev_stat.vs_aux) {
718 		case VDEV_AUX_ERR_EXCEEDED:
719 			aux = "err_exceeded";
720 			break;
721 
722 		case VDEV_AUX_EXTERNAL:
723 			aux = "external";
724 			break;
725 		}
726 
727 		if (aux != NULL && !vd->vdev_tmpoffline) {
728 			fnvlist_add_string(nv, ZPOOL_CONFIG_AUX_STATE, aux);
729 		} else {
730 			/*
731 			 * We're healthy - clear any previous AUX_STATE values.
732 			 */
733 			if (nvlist_exists(nv, ZPOOL_CONFIG_AUX_STATE))
734 				nvlist_remove_all(nv, ZPOOL_CONFIG_AUX_STATE);
735 		}
736 
737 		if (vd->vdev_splitting && vd->vdev_orig_guid != 0LL) {
738 			fnvlist_add_uint64(nv, ZPOOL_CONFIG_ORIG_GUID,
739 			    vd->vdev_orig_guid);
740 		}
741 	}
742 
743 	return (nv);
744 }
745 
746 /*
747  * Generate a view of the top-level vdevs.  If we currently have holes
748  * in the namespace, then generate an array which contains a list of holey
749  * vdevs.  Additionally, add the number of top-level children that currently
750  * exist.
751  */
752 void
vdev_top_config_generate(spa_t * spa,nvlist_t * config)753 vdev_top_config_generate(spa_t *spa, nvlist_t *config)
754 {
755 	vdev_t *rvd = spa->spa_root_vdev;
756 	uint64_t *array;
757 	uint_t c, idx;
758 
759 	array = kmem_alloc(rvd->vdev_children * sizeof (uint64_t), KM_SLEEP);
760 
761 	for (c = 0, idx = 0; c < rvd->vdev_children; c++) {
762 		vdev_t *tvd = rvd->vdev_child[c];
763 
764 		if (tvd->vdev_ishole) {
765 			array[idx++] = c;
766 		}
767 	}
768 
769 	if (idx) {
770 		VERIFY(nvlist_add_uint64_array(config, ZPOOL_CONFIG_HOLE_ARRAY,
771 		    array, idx) == 0);
772 	}
773 
774 	VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_VDEV_CHILDREN,
775 	    rvd->vdev_children) == 0);
776 
777 	kmem_free(array, rvd->vdev_children * sizeof (uint64_t));
778 }
779 
780 /*
781  * Returns the configuration from the label of the given vdev. For vdevs
782  * which don't have a txg value stored on their label (i.e. spares/cache)
783  * or have not been completely initialized (txg = 0) just return
784  * the configuration from the first valid label we find. Otherwise,
785  * find the most up-to-date label that does not exceed the specified
786  * 'txg' value.
787  */
788 nvlist_t *
vdev_label_read_config(vdev_t * vd,uint64_t txg)789 vdev_label_read_config(vdev_t *vd, uint64_t txg)
790 {
791 	spa_t *spa = vd->vdev_spa;
792 	nvlist_t *config = NULL;
793 	vdev_phys_t *vp[VDEV_LABELS];
794 	abd_t *vp_abd[VDEV_LABELS];
795 	zio_t *zio[VDEV_LABELS];
796 	uint64_t best_txg = 0;
797 	uint64_t label_txg = 0;
798 	int error = 0;
799 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
800 	    ZIO_FLAG_SPECULATIVE;
801 
802 	ASSERT(vd->vdev_validate_thread == curthread ||
803 	    spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
804 
805 	if (!vdev_readable(vd))
806 		return (NULL);
807 
808 	/*
809 	 * The label for a dRAID distributed spare is not stored on disk.
810 	 * Instead it is generated when needed which allows us to bypass
811 	 * the pipeline when reading the config from the label.
812 	 */
813 	if (vd->vdev_ops == &vdev_draid_spare_ops)
814 		return (vdev_draid_read_config_spare(vd));
815 
816 	for (int l = 0; l < VDEV_LABELS; l++) {
817 		vp_abd[l] = abd_alloc_linear(sizeof (vdev_phys_t), B_TRUE);
818 		vp[l] = abd_to_buf(vp_abd[l]);
819 	}
820 
821 retry:
822 	for (int l = 0; l < VDEV_LABELS; l++) {
823 		zio[l] = zio_root(spa, NULL, NULL, flags);
824 
825 		vdev_label_read(zio[l], vd, l, vp_abd[l],
826 		    offsetof(vdev_label_t, vl_vdev_phys), sizeof (vdev_phys_t),
827 		    NULL, NULL, flags);
828 	}
829 	for (int l = 0; l < VDEV_LABELS; l++) {
830 		nvlist_t *label = NULL;
831 
832 		if (zio_wait(zio[l]) == 0 &&
833 		    nvlist_unpack(vp[l]->vp_nvlist, sizeof (vp[l]->vp_nvlist),
834 		    &label, 0) == 0) {
835 			/*
836 			 * Auxiliary vdevs won't have txg values in their
837 			 * labels and newly added vdevs may not have been
838 			 * completely initialized so just return the
839 			 * configuration from the first valid label we
840 			 * encounter.
841 			 */
842 			error = nvlist_lookup_uint64(label,
843 			    ZPOOL_CONFIG_POOL_TXG, &label_txg);
844 			if ((error || label_txg == 0) && !config) {
845 				config = label;
846 				for (l++; l < VDEV_LABELS; l++)
847 					zio_wait(zio[l]);
848 				break;
849 			} else if (label_txg <= txg && label_txg > best_txg) {
850 				best_txg = label_txg;
851 				nvlist_free(config);
852 				config = fnvlist_dup(label);
853 			}
854 		}
855 
856 		if (label != NULL) {
857 			nvlist_free(label);
858 			label = NULL;
859 		}
860 	}
861 
862 	if (config == NULL && !(flags & ZIO_FLAG_TRYHARD)) {
863 		flags |= ZIO_FLAG_TRYHARD;
864 		goto retry;
865 	}
866 
867 	/*
868 	 * We found a valid label but it didn't pass txg restrictions.
869 	 */
870 	if (config == NULL && label_txg != 0) {
871 		vdev_dbgmsg(vd, "label discarded as txg is too large "
872 		    "(%llu > %llu)", (u_longlong_t)label_txg,
873 		    (u_longlong_t)txg);
874 	}
875 
876 	for (int l = 0; l < VDEV_LABELS; l++) {
877 		abd_free(vp_abd[l]);
878 	}
879 
880 	return (config);
881 }
882 
883 /*
884  * Determine if a device is in use.  The 'spare_guid' parameter will be filled
885  * in with the device guid if this spare is active elsewhere on the system.
886  */
887 static boolean_t
vdev_inuse(vdev_t * vd,uint64_t crtxg,vdev_labeltype_t reason,uint64_t * spare_guid,uint64_t * l2cache_guid)888 vdev_inuse(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason,
889     uint64_t *spare_guid, uint64_t *l2cache_guid)
890 {
891 	spa_t *spa = vd->vdev_spa;
892 	uint64_t state, pool_guid, device_guid, txg, spare_pool;
893 	uint64_t vdtxg = 0;
894 	nvlist_t *label;
895 
896 	if (spare_guid)
897 		*spare_guid = 0ULL;
898 	if (l2cache_guid)
899 		*l2cache_guid = 0ULL;
900 
901 	/*
902 	 * Read the label, if any, and perform some basic sanity checks.
903 	 */
904 	if ((label = vdev_label_read_config(vd, -1ULL)) == NULL)
905 		return (B_FALSE);
906 
907 	(void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
908 	    &vdtxg);
909 
910 	if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
911 	    &state) != 0 ||
912 	    nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID,
913 	    &device_guid) != 0) {
914 		nvlist_free(label);
915 		return (B_FALSE);
916 	}
917 
918 	if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
919 	    (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID,
920 	    &pool_guid) != 0 ||
921 	    nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG,
922 	    &txg) != 0)) {
923 		nvlist_free(label);
924 		return (B_FALSE);
925 	}
926 
927 	nvlist_free(label);
928 
929 	/*
930 	 * Check to see if this device indeed belongs to the pool it claims to
931 	 * be a part of.  The only way this is allowed is if the device is a hot
932 	 * spare (which we check for later on).
933 	 */
934 	if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
935 	    !spa_guid_exists(pool_guid, device_guid) &&
936 	    !spa_spare_exists(device_guid, NULL, NULL) &&
937 	    !spa_l2cache_exists(device_guid, NULL))
938 		return (B_FALSE);
939 
940 	/*
941 	 * If the transaction group is zero, then this an initialized (but
942 	 * unused) label.  This is only an error if the create transaction
943 	 * on-disk is the same as the one we're using now, in which case the
944 	 * user has attempted to add the same vdev multiple times in the same
945 	 * transaction.
946 	 */
947 	if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
948 	    txg == 0 && vdtxg == crtxg)
949 		return (B_TRUE);
950 
951 	/*
952 	 * Check to see if this is a spare device.  We do an explicit check for
953 	 * spa_has_spare() here because it may be on our pending list of spares
954 	 * to add.
955 	 */
956 	if (spa_spare_exists(device_guid, &spare_pool, NULL) ||
957 	    spa_has_spare(spa, device_guid)) {
958 		if (spare_guid)
959 			*spare_guid = device_guid;
960 
961 		switch (reason) {
962 		case VDEV_LABEL_CREATE:
963 			return (B_TRUE);
964 
965 		case VDEV_LABEL_REPLACE:
966 			return (!spa_has_spare(spa, device_guid) ||
967 			    spare_pool != 0ULL);
968 
969 		case VDEV_LABEL_SPARE:
970 			return (spa_has_spare(spa, device_guid));
971 		default:
972 			break;
973 		}
974 	}
975 
976 	/*
977 	 * Check to see if this is an l2cache device.
978 	 */
979 	if (spa_l2cache_exists(device_guid, NULL) ||
980 	    spa_has_l2cache(spa, device_guid)) {
981 		if (l2cache_guid)
982 			*l2cache_guid = device_guid;
983 
984 		switch (reason) {
985 		case VDEV_LABEL_CREATE:
986 			return (B_TRUE);
987 
988 		case VDEV_LABEL_REPLACE:
989 			return (!spa_has_l2cache(spa, device_guid));
990 
991 		case VDEV_LABEL_L2CACHE:
992 			return (spa_has_l2cache(spa, device_guid));
993 		default:
994 			break;
995 		}
996 	}
997 
998 	/*
999 	 * We can't rely on a pool's state if it's been imported
1000 	 * read-only.  Instead we look to see if the pools is marked
1001 	 * read-only in the namespace and set the state to active.
1002 	 */
1003 	if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
1004 	    (spa = spa_by_guid(pool_guid, device_guid)) != NULL &&
1005 	    spa_mode(spa) == SPA_MODE_READ)
1006 		state = POOL_STATE_ACTIVE;
1007 
1008 	/*
1009 	 * If the device is marked ACTIVE, then this device is in use by another
1010 	 * pool on the system.
1011 	 */
1012 	return (state == POOL_STATE_ACTIVE);
1013 }
1014 
1015 static nvlist_t *
vdev_aux_label_generate(vdev_t * vd,boolean_t reason_spare)1016 vdev_aux_label_generate(vdev_t *vd, boolean_t reason_spare)
1017 {
1018 	/*
1019 	 * For inactive hot spares and level 2 ARC devices, we generate
1020 	 * a special label that identifies as a mutually shared hot
1021 	 * spare or l2cache device. We write the label in case of
1022 	 * addition or removal of hot spare or l2cache vdev (in which
1023 	 * case we want to revert the labels).
1024 	 */
1025 	nvlist_t *label = fnvlist_alloc();
1026 	fnvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
1027 	    spa_version(vd->vdev_spa));
1028 	fnvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE, reason_spare ?
1029 	    POOL_STATE_SPARE : POOL_STATE_L2CACHE);
1030 	fnvlist_add_uint64(label, ZPOOL_CONFIG_GUID, vd->vdev_guid);
1031 
1032 	/*
1033 	 * This is merely to facilitate reporting the ashift of the
1034 	 * cache device through zdb. The actual retrieval of the
1035 	 * ashift (in vdev_alloc()) uses the nvlist
1036 	 * spa->spa_l2cache->sav_config (populated in
1037 	 * spa_ld_open_aux_vdevs()).
1038 	 */
1039 	if (!reason_spare)
1040 		fnvlist_add_uint64(label, ZPOOL_CONFIG_ASHIFT, vd->vdev_ashift);
1041 
1042 	/*
1043 	 * Add path information to help find it during pool import
1044 	 */
1045 	if (vd->vdev_path != NULL)
1046 		fnvlist_add_string(label, ZPOOL_CONFIG_PATH, vd->vdev_path);
1047 	if (vd->vdev_devid != NULL)
1048 		fnvlist_add_string(label, ZPOOL_CONFIG_DEVID, vd->vdev_devid);
1049 	if (vd->vdev_physpath != NULL) {
1050 		fnvlist_add_string(label, ZPOOL_CONFIG_PHYS_PATH,
1051 		    vd->vdev_physpath);
1052 	}
1053 	return (label);
1054 }
1055 
1056 /*
1057  * Initialize a vdev label.  We check to make sure each leaf device is not in
1058  * use, and writable.  We put down an initial label which we will later
1059  * overwrite with a complete label.  Note that it's important to do this
1060  * sequentially, not in parallel, so that we catch cases of multiple use of the
1061  * same leaf vdev in the vdev we're creating -- e.g. mirroring a disk with
1062  * itself.
1063  */
1064 int
vdev_label_init(vdev_t * vd,uint64_t crtxg,vdev_labeltype_t reason)1065 vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
1066 {
1067 	spa_t *spa = vd->vdev_spa;
1068 	nvlist_t *label;
1069 	vdev_phys_t *vp;
1070 	abd_t *vp_abd;
1071 	abd_t *bootenv;
1072 	uberblock_t *ub;
1073 	abd_t *ub_abd;
1074 	zio_t *zio;
1075 	char *buf;
1076 	size_t buflen;
1077 	int error;
1078 	uint64_t spare_guid = 0, l2cache_guid = 0;
1079 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
1080 	boolean_t reason_spare = (reason == VDEV_LABEL_SPARE || (reason ==
1081 	    VDEV_LABEL_REMOVE && vd->vdev_isspare));
1082 	boolean_t reason_l2cache = (reason == VDEV_LABEL_L2CACHE || (reason ==
1083 	    VDEV_LABEL_REMOVE && vd->vdev_isl2cache));
1084 
1085 	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
1086 
1087 	for (int c = 0; c < vd->vdev_children; c++)
1088 		if ((error = vdev_label_init(vd->vdev_child[c],
1089 		    crtxg, reason)) != 0)
1090 			return (error);
1091 
1092 	/* Track the creation time for this vdev */
1093 	vd->vdev_crtxg = crtxg;
1094 
1095 	if (!vd->vdev_ops->vdev_op_leaf || !spa_writeable(spa))
1096 		return (0);
1097 
1098 	/*
1099 	 * Dead vdevs cannot be initialized.
1100 	 */
1101 	if (vdev_is_dead(vd))
1102 		return (SET_ERROR(EIO));
1103 
1104 	/*
1105 	 * Determine if the vdev is in use.
1106 	 */
1107 	if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPLIT &&
1108 	    vdev_inuse(vd, crtxg, reason, &spare_guid, &l2cache_guid))
1109 		return (SET_ERROR(EBUSY));
1110 
1111 	/*
1112 	 * If this is a request to add or replace a spare or l2cache device
1113 	 * that is in use elsewhere on the system, then we must update the
1114 	 * guid (which was initialized to a random value) to reflect the
1115 	 * actual GUID (which is shared between multiple pools).
1116 	 */
1117 	if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_L2CACHE &&
1118 	    spare_guid != 0ULL) {
1119 		uint64_t guid_delta = spare_guid - vd->vdev_guid;
1120 
1121 		vd->vdev_guid += guid_delta;
1122 
1123 		for (vdev_t *pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
1124 			pvd->vdev_guid_sum += guid_delta;
1125 
1126 		/*
1127 		 * If this is a replacement, then we want to fallthrough to the
1128 		 * rest of the code.  If we're adding a spare, then it's already
1129 		 * labeled appropriately and we can just return.
1130 		 */
1131 		if (reason == VDEV_LABEL_SPARE)
1132 			return (0);
1133 		ASSERT(reason == VDEV_LABEL_REPLACE ||
1134 		    reason == VDEV_LABEL_SPLIT);
1135 	}
1136 
1137 	if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPARE &&
1138 	    l2cache_guid != 0ULL) {
1139 		uint64_t guid_delta = l2cache_guid - vd->vdev_guid;
1140 
1141 		vd->vdev_guid += guid_delta;
1142 
1143 		for (vdev_t *pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
1144 			pvd->vdev_guid_sum += guid_delta;
1145 
1146 		/*
1147 		 * If this is a replacement, then we want to fallthrough to the
1148 		 * rest of the code.  If we're adding an l2cache, then it's
1149 		 * already labeled appropriately and we can just return.
1150 		 */
1151 		if (reason == VDEV_LABEL_L2CACHE)
1152 			return (0);
1153 		ASSERT(reason == VDEV_LABEL_REPLACE);
1154 	}
1155 
1156 	/*
1157 	 * Initialize its label.
1158 	 */
1159 	vp_abd = abd_alloc_linear(sizeof (vdev_phys_t), B_TRUE);
1160 	abd_zero(vp_abd, sizeof (vdev_phys_t));
1161 	vp = abd_to_buf(vp_abd);
1162 
1163 	/*
1164 	 * Generate a label describing the pool and our top-level vdev.
1165 	 * We mark it as being from txg 0 to indicate that it's not
1166 	 * really part of an active pool just yet.  The labels will
1167 	 * be written again with a meaningful txg by spa_sync().
1168 	 */
1169 	if (reason_spare || reason_l2cache) {
1170 		label = vdev_aux_label_generate(vd, reason_spare);
1171 
1172 		/*
1173 		 * When spare or l2cache (aux) vdev is added during pool
1174 		 * creation, spa->spa_uberblock is not written until this
1175 		 * point. Write it on next config sync.
1176 		 */
1177 		if (uberblock_verify(&spa->spa_uberblock))
1178 			spa->spa_aux_sync_uber = B_TRUE;
1179 	} else {
1180 		uint64_t txg = 0ULL;
1181 
1182 		if (reason == VDEV_LABEL_SPLIT)
1183 			txg = spa->spa_uberblock.ub_txg;
1184 		label = spa_config_generate(spa, vd, txg, B_FALSE);
1185 
1186 		/*
1187 		 * Add our creation time.  This allows us to detect multiple
1188 		 * vdev uses as described above, and automatically expires if we
1189 		 * fail.
1190 		 */
1191 		VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
1192 		    crtxg) == 0);
1193 	}
1194 
1195 	buf = vp->vp_nvlist;
1196 	buflen = sizeof (vp->vp_nvlist);
1197 
1198 	error = nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP);
1199 	if (error != 0) {
1200 		nvlist_free(label);
1201 		abd_free(vp_abd);
1202 		/* EFAULT means nvlist_pack ran out of room */
1203 		return (SET_ERROR(error == EFAULT ? ENAMETOOLONG : EINVAL));
1204 	}
1205 
1206 	/*
1207 	 * Initialize uberblock template.
1208 	 */
1209 	ub_abd = abd_alloc_linear(VDEV_UBERBLOCK_RING, B_TRUE);
1210 	abd_copy_from_buf(ub_abd, &spa->spa_uberblock, sizeof (uberblock_t));
1211 	abd_zero_off(ub_abd, sizeof (uberblock_t),
1212 	    VDEV_UBERBLOCK_RING - sizeof (uberblock_t));
1213 	ub = abd_to_buf(ub_abd);
1214 	ub->ub_txg = 0;
1215 
1216 	/* Initialize the 2nd padding area. */
1217 	bootenv = abd_alloc_for_io(VDEV_PAD_SIZE, B_TRUE);
1218 	abd_zero(bootenv, VDEV_PAD_SIZE);
1219 
1220 	/*
1221 	 * Write everything in parallel.
1222 	 */
1223 retry:
1224 	zio = zio_root(spa, NULL, NULL, flags);
1225 
1226 	for (int l = 0; l < VDEV_LABELS; l++) {
1227 
1228 		vdev_label_write(zio, vd, l, vp_abd,
1229 		    offsetof(vdev_label_t, vl_vdev_phys),
1230 		    sizeof (vdev_phys_t), NULL, NULL, flags);
1231 
1232 		/*
1233 		 * Skip the 1st padding area.
1234 		 * Zero out the 2nd padding area where it might have
1235 		 * left over data from previous filesystem format.
1236 		 */
1237 		vdev_label_write(zio, vd, l, bootenv,
1238 		    offsetof(vdev_label_t, vl_be),
1239 		    VDEV_PAD_SIZE, NULL, NULL, flags);
1240 
1241 		vdev_label_write(zio, vd, l, ub_abd,
1242 		    offsetof(vdev_label_t, vl_uberblock),
1243 		    VDEV_UBERBLOCK_RING, NULL, NULL, flags);
1244 	}
1245 
1246 	error = zio_wait(zio);
1247 
1248 	if (error != 0 && !(flags & ZIO_FLAG_TRYHARD)) {
1249 		flags |= ZIO_FLAG_TRYHARD;
1250 		goto retry;
1251 	}
1252 
1253 	nvlist_free(label);
1254 	abd_free(bootenv);
1255 	abd_free(ub_abd);
1256 	abd_free(vp_abd);
1257 
1258 	/*
1259 	 * If this vdev hasn't been previously identified as a spare, then we
1260 	 * mark it as such only if a) we are labeling it as a spare, or b) it
1261 	 * exists as a spare elsewhere in the system.  Do the same for
1262 	 * level 2 ARC devices.
1263 	 */
1264 	if (error == 0 && !vd->vdev_isspare &&
1265 	    (reason == VDEV_LABEL_SPARE ||
1266 	    spa_spare_exists(vd->vdev_guid, NULL, NULL)))
1267 		spa_spare_add(vd);
1268 
1269 	if (error == 0 && !vd->vdev_isl2cache &&
1270 	    (reason == VDEV_LABEL_L2CACHE ||
1271 	    spa_l2cache_exists(vd->vdev_guid, NULL)))
1272 		spa_l2cache_add(vd);
1273 
1274 	return (error);
1275 }
1276 
1277 /*
1278  * Done callback for vdev_label_read_bootenv_impl. If this is the first
1279  * callback to finish, store our abd in the callback pointer. Otherwise, we
1280  * just free our abd and return.
1281  */
1282 static void
vdev_label_read_bootenv_done(zio_t * zio)1283 vdev_label_read_bootenv_done(zio_t *zio)
1284 {
1285 	zio_t *rio = zio->io_private;
1286 	abd_t **cbp = rio->io_private;
1287 
1288 	ASSERT3U(zio->io_size, ==, VDEV_PAD_SIZE);
1289 
1290 	if (zio->io_error == 0) {
1291 		mutex_enter(&rio->io_lock);
1292 		if (*cbp == NULL) {
1293 			/* Will free this buffer in vdev_label_read_bootenv. */
1294 			*cbp = zio->io_abd;
1295 		} else {
1296 			abd_free(zio->io_abd);
1297 		}
1298 		mutex_exit(&rio->io_lock);
1299 	} else {
1300 		abd_free(zio->io_abd);
1301 	}
1302 }
1303 
1304 static void
vdev_label_read_bootenv_impl(zio_t * zio,vdev_t * vd,int flags)1305 vdev_label_read_bootenv_impl(zio_t *zio, vdev_t *vd, int flags)
1306 {
1307 	for (int c = 0; c < vd->vdev_children; c++)
1308 		vdev_label_read_bootenv_impl(zio, vd->vdev_child[c], flags);
1309 
1310 	/*
1311 	 * We just use the first label that has a correct checksum; the
1312 	 * bootloader should have rewritten them all to be the same on boot,
1313 	 * and any changes we made since boot have been the same across all
1314 	 * labels.
1315 	 */
1316 	if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) {
1317 		for (int l = 0; l < VDEV_LABELS; l++) {
1318 			vdev_label_read(zio, vd, l,
1319 			    abd_alloc_linear(VDEV_PAD_SIZE, B_FALSE),
1320 			    offsetof(vdev_label_t, vl_be), VDEV_PAD_SIZE,
1321 			    vdev_label_read_bootenv_done, zio, flags);
1322 		}
1323 	}
1324 }
1325 
1326 int
vdev_label_read_bootenv(vdev_t * rvd,nvlist_t * bootenv)1327 vdev_label_read_bootenv(vdev_t *rvd, nvlist_t *bootenv)
1328 {
1329 	nvlist_t *config;
1330 	spa_t *spa = rvd->vdev_spa;
1331 	abd_t *abd = NULL;
1332 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
1333 	    ZIO_FLAG_SPECULATIVE | ZIO_FLAG_TRYHARD;
1334 
1335 	ASSERT(bootenv);
1336 	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
1337 
1338 	zio_t *zio = zio_root(spa, NULL, &abd, flags);
1339 	vdev_label_read_bootenv_impl(zio, rvd, flags);
1340 	int err = zio_wait(zio);
1341 
1342 	if (abd != NULL) {
1343 		char *buf;
1344 		vdev_boot_envblock_t *vbe = abd_to_buf(abd);
1345 
1346 		vbe->vbe_version = ntohll(vbe->vbe_version);
1347 		switch (vbe->vbe_version) {
1348 		case VB_RAW:
1349 			/*
1350 			 * if we have textual data in vbe_bootenv, create nvlist
1351 			 * with key "envmap".
1352 			 */
1353 			fnvlist_add_uint64(bootenv, BOOTENV_VERSION, VB_RAW);
1354 			vbe->vbe_bootenv[sizeof (vbe->vbe_bootenv) - 1] = '\0';
1355 			fnvlist_add_string(bootenv, GRUB_ENVMAP,
1356 			    vbe->vbe_bootenv);
1357 			break;
1358 
1359 		case VB_NVLIST:
1360 			err = nvlist_unpack(vbe->vbe_bootenv,
1361 			    sizeof (vbe->vbe_bootenv), &config, 0);
1362 			if (err == 0) {
1363 				fnvlist_merge(bootenv, config);
1364 				nvlist_free(config);
1365 				break;
1366 			}
1367 			zfs_fallthrough;
1368 		default:
1369 			/* Check for FreeBSD zfs bootonce command string */
1370 			buf = abd_to_buf(abd);
1371 			if (*buf == '\0') {
1372 				fnvlist_add_uint64(bootenv, BOOTENV_VERSION,
1373 				    VB_NVLIST);
1374 				break;
1375 			}
1376 			fnvlist_add_string(bootenv, FREEBSD_BOOTONCE, buf);
1377 		}
1378 
1379 		/*
1380 		 * abd was allocated in vdev_label_read_bootenv_impl()
1381 		 */
1382 		abd_free(abd);
1383 		/*
1384 		 * If we managed to read any successfully,
1385 		 * return success.
1386 		 */
1387 		return (0);
1388 	}
1389 	return (err);
1390 }
1391 
1392 int
vdev_label_write_bootenv(vdev_t * vd,nvlist_t * env)1393 vdev_label_write_bootenv(vdev_t *vd, nvlist_t *env)
1394 {
1395 	zio_t *zio;
1396 	spa_t *spa = vd->vdev_spa;
1397 	vdev_boot_envblock_t *bootenv;
1398 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
1399 	int error;
1400 	size_t nvsize;
1401 	char *nvbuf;
1402 	const char *tmp;
1403 
1404 	error = nvlist_size(env, &nvsize, NV_ENCODE_XDR);
1405 	if (error != 0)
1406 		return (SET_ERROR(error));
1407 
1408 	if (nvsize >= sizeof (bootenv->vbe_bootenv)) {
1409 		return (SET_ERROR(E2BIG));
1410 	}
1411 
1412 	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
1413 
1414 	error = ENXIO;
1415 	for (int c = 0; c < vd->vdev_children; c++) {
1416 		int child_err;
1417 
1418 		child_err = vdev_label_write_bootenv(vd->vdev_child[c], env);
1419 		/*
1420 		 * As long as any of the disks managed to write all of their
1421 		 * labels successfully, return success.
1422 		 */
1423 		if (child_err == 0)
1424 			error = child_err;
1425 	}
1426 
1427 	if (!vd->vdev_ops->vdev_op_leaf || vdev_is_dead(vd) ||
1428 	    !vdev_writeable(vd)) {
1429 		return (error);
1430 	}
1431 	ASSERT3U(sizeof (*bootenv), ==, VDEV_PAD_SIZE);
1432 	abd_t *abd = abd_alloc_for_io(VDEV_PAD_SIZE, B_TRUE);
1433 	abd_zero(abd, VDEV_PAD_SIZE);
1434 
1435 	bootenv = abd_borrow_buf_copy(abd, VDEV_PAD_SIZE);
1436 	nvbuf = bootenv->vbe_bootenv;
1437 	nvsize = sizeof (bootenv->vbe_bootenv);
1438 
1439 	bootenv->vbe_version = fnvlist_lookup_uint64(env, BOOTENV_VERSION);
1440 	switch (bootenv->vbe_version) {
1441 	case VB_RAW:
1442 		if (nvlist_lookup_string(env, GRUB_ENVMAP, &tmp) == 0) {
1443 			(void) strlcpy(bootenv->vbe_bootenv, tmp, nvsize);
1444 		}
1445 		error = 0;
1446 		break;
1447 
1448 	case VB_NVLIST:
1449 		error = nvlist_pack(env, &nvbuf, &nvsize, NV_ENCODE_XDR,
1450 		    KM_SLEEP);
1451 		break;
1452 
1453 	default:
1454 		error = EINVAL;
1455 		break;
1456 	}
1457 
1458 	if (error == 0) {
1459 		bootenv->vbe_version = htonll(bootenv->vbe_version);
1460 		abd_return_buf_copy(abd, bootenv, VDEV_PAD_SIZE);
1461 	} else {
1462 		abd_free(abd);
1463 		return (SET_ERROR(error));
1464 	}
1465 
1466 retry:
1467 	zio = zio_root(spa, NULL, NULL, flags);
1468 	for (int l = 0; l < VDEV_LABELS; l++) {
1469 		vdev_label_write(zio, vd, l, abd,
1470 		    offsetof(vdev_label_t, vl_be),
1471 		    VDEV_PAD_SIZE, NULL, NULL, flags);
1472 	}
1473 
1474 	error = zio_wait(zio);
1475 	if (error != 0 && !(flags & ZIO_FLAG_TRYHARD)) {
1476 		flags |= ZIO_FLAG_TRYHARD;
1477 		goto retry;
1478 	}
1479 
1480 	abd_free(abd);
1481 	return (error);
1482 }
1483 
1484 /*
1485  * ==========================================================================
1486  * uberblock load/sync
1487  * ==========================================================================
1488  */
1489 
1490 /*
1491  * Consider the following situation: txg is safely synced to disk.  We've
1492  * written the first uberblock for txg + 1, and then we lose power.  When we
1493  * come back up, we fail to see the uberblock for txg + 1 because, say,
1494  * it was on a mirrored device and the replica to which we wrote txg + 1
1495  * is now offline.  If we then make some changes and sync txg + 1, and then
1496  * the missing replica comes back, then for a few seconds we'll have two
1497  * conflicting uberblocks on disk with the same txg.  The solution is simple:
1498  * among uberblocks with equal txg, choose the one with the latest timestamp.
1499  */
1500 static int
vdev_uberblock_compare(const uberblock_t * ub1,const uberblock_t * ub2)1501 vdev_uberblock_compare(const uberblock_t *ub1, const uberblock_t *ub2)
1502 {
1503 	int cmp = TREE_CMP(ub1->ub_txg, ub2->ub_txg);
1504 
1505 	if (likely(cmp))
1506 		return (cmp);
1507 
1508 	cmp = TREE_CMP(ub1->ub_timestamp, ub2->ub_timestamp);
1509 	if (likely(cmp))
1510 		return (cmp);
1511 
1512 	/*
1513 	 * If MMP_VALID(ub) && MMP_SEQ_VALID(ub) then the host has an MMP-aware
1514 	 * ZFS, e.g. OpenZFS >= 0.7.
1515 	 *
1516 	 * If one ub has MMP and the other does not, they were written by
1517 	 * different hosts, which matters for MMP.  So we treat no MMP/no SEQ as
1518 	 * a 0 value.
1519 	 *
1520 	 * Since timestamp and txg are the same if we get this far, either is
1521 	 * acceptable for importing the pool.
1522 	 */
1523 	unsigned int seq1 = 0;
1524 	unsigned int seq2 = 0;
1525 
1526 	if (MMP_VALID(ub1) && MMP_SEQ_VALID(ub1))
1527 		seq1 = MMP_SEQ(ub1);
1528 
1529 	if (MMP_VALID(ub2) && MMP_SEQ_VALID(ub2))
1530 		seq2 = MMP_SEQ(ub2);
1531 
1532 	return (TREE_CMP(seq1, seq2));
1533 }
1534 
1535 struct ubl_cbdata {
1536 	uberblock_t	ubl_latest;	/* Most recent uberblock */
1537 	uberblock_t	*ubl_ubbest;	/* Best uberblock (w/r/t max_txg) */
1538 	vdev_t		*ubl_vd;	/* vdev associated with the above */
1539 };
1540 
1541 static void
vdev_uberblock_load_done(zio_t * zio)1542 vdev_uberblock_load_done(zio_t *zio)
1543 {
1544 	vdev_t *vd = zio->io_vd;
1545 	spa_t *spa = zio->io_spa;
1546 	zio_t *rio = zio->io_private;
1547 	uberblock_t *ub = abd_to_buf(zio->io_abd);
1548 	struct ubl_cbdata *cbp = rio->io_private;
1549 
1550 	ASSERT3U(zio->io_size, ==, VDEV_UBERBLOCK_SIZE(vd));
1551 
1552 	if (zio->io_error == 0 && uberblock_verify(ub) == 0) {
1553 		mutex_enter(&rio->io_lock);
1554 		if (vdev_uberblock_compare(ub, &cbp->ubl_latest) > 0) {
1555 			cbp->ubl_latest = *ub;
1556 		}
1557 		if (ub->ub_txg <= spa->spa_load_max_txg &&
1558 		    vdev_uberblock_compare(ub, cbp->ubl_ubbest) > 0) {
1559 			/*
1560 			 * Keep track of the vdev in which this uberblock
1561 			 * was found. We will use this information later
1562 			 * to obtain the config nvlist associated with
1563 			 * this uberblock.
1564 			 */
1565 			*cbp->ubl_ubbest = *ub;
1566 			cbp->ubl_vd = vd;
1567 		}
1568 		mutex_exit(&rio->io_lock);
1569 	}
1570 
1571 	abd_free(zio->io_abd);
1572 }
1573 
1574 static void
vdev_uberblock_load_impl(zio_t * zio,vdev_t * vd,int flags,struct ubl_cbdata * cbp)1575 vdev_uberblock_load_impl(zio_t *zio, vdev_t *vd, int flags,
1576     struct ubl_cbdata *cbp)
1577 {
1578 	for (int c = 0; c < vd->vdev_children; c++)
1579 		vdev_uberblock_load_impl(zio, vd->vdev_child[c], flags, cbp);
1580 
1581 	if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd) &&
1582 	    vd->vdev_ops != &vdev_draid_spare_ops) {
1583 		for (int l = 0; l < VDEV_LABELS; l++) {
1584 			for (int n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
1585 				vdev_label_read(zio, vd, l,
1586 				    abd_alloc_linear(VDEV_UBERBLOCK_SIZE(vd),
1587 				    B_TRUE), VDEV_UBERBLOCK_OFFSET(vd, n),
1588 				    VDEV_UBERBLOCK_SIZE(vd),
1589 				    vdev_uberblock_load_done, zio, flags);
1590 			}
1591 		}
1592 	}
1593 }
1594 
1595 /*
1596  * Reads the 'best' uberblock from disk along with its associated
1597  * configuration. First, we read the uberblock array of each label of each
1598  * vdev, keeping track of the uberblock with the highest txg in each array.
1599  * Then, we read the configuration from the same vdev as the best uberblock.
1600  */
1601 void
vdev_uberblock_load(vdev_t * rvd,uberblock_t * ub,nvlist_t ** config)1602 vdev_uberblock_load(vdev_t *rvd, uberblock_t *ub, nvlist_t **config)
1603 {
1604 	zio_t *zio;
1605 	spa_t *spa = rvd->vdev_spa;
1606 	struct ubl_cbdata cb;
1607 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
1608 	    ZIO_FLAG_SPECULATIVE | ZIO_FLAG_TRYHARD;
1609 
1610 	ASSERT(ub);
1611 	ASSERT(config);
1612 
1613 	memset(ub, 0, sizeof (uberblock_t));
1614 	memset(&cb, 0, sizeof (cb));
1615 	*config = NULL;
1616 
1617 	cb.ubl_ubbest = ub;
1618 
1619 	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
1620 	zio = zio_root(spa, NULL, &cb, flags);
1621 	vdev_uberblock_load_impl(zio, rvd, flags, &cb);
1622 	(void) zio_wait(zio);
1623 
1624 	/*
1625 	 * It's possible that the best uberblock was discovered on a label
1626 	 * that has a configuration which was written in a future txg.
1627 	 * Search all labels on this vdev to find the configuration that
1628 	 * matches the txg for our uberblock.
1629 	 */
1630 	if (cb.ubl_vd != NULL) {
1631 		vdev_dbgmsg(cb.ubl_vd, "best uberblock found for spa %s. "
1632 		    "txg %llu", spa->spa_name, (u_longlong_t)ub->ub_txg);
1633 
1634 		if (ub->ub_raidz_reflow_info !=
1635 		    cb.ubl_latest.ub_raidz_reflow_info) {
1636 			vdev_dbgmsg(cb.ubl_vd,
1637 			    "spa=%s best uberblock (txg=%llu info=0x%llx) "
1638 			    "has different raidz_reflow_info than latest "
1639 			    "uberblock (txg=%llu info=0x%llx)",
1640 			    spa->spa_name,
1641 			    (u_longlong_t)ub->ub_txg,
1642 			    (u_longlong_t)ub->ub_raidz_reflow_info,
1643 			    (u_longlong_t)cb.ubl_latest.ub_txg,
1644 			    (u_longlong_t)cb.ubl_latest.ub_raidz_reflow_info);
1645 			memset(ub, 0, sizeof (uberblock_t));
1646 			spa_config_exit(spa, SCL_ALL, FTAG);
1647 			return;
1648 		}
1649 
1650 		*config = vdev_label_read_config(cb.ubl_vd, ub->ub_txg);
1651 		if (*config == NULL && spa->spa_extreme_rewind) {
1652 			vdev_dbgmsg(cb.ubl_vd, "failed to read label config. "
1653 			    "Trying again without txg restrictions.");
1654 			*config = vdev_label_read_config(cb.ubl_vd, UINT64_MAX);
1655 		}
1656 		if (*config == NULL) {
1657 			vdev_dbgmsg(cb.ubl_vd, "failed to read label config");
1658 		}
1659 	}
1660 	spa_config_exit(spa, SCL_ALL, FTAG);
1661 }
1662 
1663 /*
1664  * For use when a leaf vdev is expanded.
1665  * The location of labels 2 and 3 changed, and at the new location the
1666  * uberblock rings are either empty or contain garbage.  The sync will write
1667  * new configs there because the vdev is dirty, but expansion also needs the
1668  * uberblock rings copied.  Read them from label 0 which did not move.
1669  *
1670  * Since the point is to populate labels {2,3} with valid uberblocks,
1671  * we zero uberblocks we fail to read or which are not valid.
1672  */
1673 
1674 static void
vdev_copy_uberblocks(vdev_t * vd)1675 vdev_copy_uberblocks(vdev_t *vd)
1676 {
1677 	abd_t *ub_abd;
1678 	zio_t *write_zio;
1679 	int locks = (SCL_L2ARC | SCL_ZIO);
1680 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
1681 	    ZIO_FLAG_SPECULATIVE;
1682 
1683 	ASSERT(spa_config_held(vd->vdev_spa, SCL_STATE, RW_READER) ==
1684 	    SCL_STATE);
1685 	ASSERT(vd->vdev_ops->vdev_op_leaf);
1686 
1687 	/*
1688 	 * No uberblocks are stored on distributed spares, they may be
1689 	 * safely skipped when expanding a leaf vdev.
1690 	 */
1691 	if (vd->vdev_ops == &vdev_draid_spare_ops)
1692 		return;
1693 
1694 	spa_config_enter(vd->vdev_spa, locks, FTAG, RW_READER);
1695 
1696 	ub_abd = abd_alloc_linear(VDEV_UBERBLOCK_SIZE(vd), B_TRUE);
1697 
1698 	write_zio = zio_root(vd->vdev_spa, NULL, NULL, flags);
1699 	for (int n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
1700 		const int src_label = 0;
1701 		zio_t *zio;
1702 
1703 		zio = zio_root(vd->vdev_spa, NULL, NULL, flags);
1704 		vdev_label_read(zio, vd, src_label, ub_abd,
1705 		    VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd),
1706 		    NULL, NULL, flags);
1707 
1708 		if (zio_wait(zio) || uberblock_verify(abd_to_buf(ub_abd)))
1709 			abd_zero(ub_abd, VDEV_UBERBLOCK_SIZE(vd));
1710 
1711 		for (int l = 2; l < VDEV_LABELS; l++)
1712 			vdev_label_write(write_zio, vd, l, ub_abd,
1713 			    VDEV_UBERBLOCK_OFFSET(vd, n),
1714 			    VDEV_UBERBLOCK_SIZE(vd), NULL, NULL,
1715 			    flags | ZIO_FLAG_DONT_PROPAGATE);
1716 	}
1717 	(void) zio_wait(write_zio);
1718 
1719 	spa_config_exit(vd->vdev_spa, locks, FTAG);
1720 
1721 	abd_free(ub_abd);
1722 }
1723 
1724 /*
1725  * On success, increment root zio's count of good writes.
1726  * We only get credit for writes to known-visible vdevs; see spa_vdev_add().
1727  */
1728 static void
vdev_uberblock_sync_done(zio_t * zio)1729 vdev_uberblock_sync_done(zio_t *zio)
1730 {
1731 	uint64_t *good_writes = zio->io_private;
1732 
1733 	if (zio->io_error == 0 && zio->io_vd->vdev_top->vdev_ms_array != 0)
1734 		atomic_inc_64(good_writes);
1735 }
1736 
1737 /*
1738  * Write the uberblock to all labels of all leaves of the specified vdev.
1739  */
1740 static void
vdev_uberblock_sync(zio_t * zio,uint64_t * good_writes,uberblock_t * ub,vdev_t * vd,int flags)1741 vdev_uberblock_sync(zio_t *zio, uint64_t *good_writes,
1742     uberblock_t *ub, vdev_t *vd, int flags)
1743 {
1744 	for (uint64_t c = 0; c < vd->vdev_children; c++) {
1745 		vdev_uberblock_sync(zio, good_writes,
1746 		    ub, vd->vdev_child[c], flags);
1747 	}
1748 
1749 	if (!vd->vdev_ops->vdev_op_leaf)
1750 		return;
1751 
1752 	if (!vdev_writeable(vd))
1753 		return;
1754 
1755 	/*
1756 	 * There's no need to write uberblocks to a distributed spare, they
1757 	 * are already stored on all the leaves of the parent dRAID.  For
1758 	 * this same reason vdev_uberblock_load_impl() skips distributed
1759 	 * spares when reading uberblocks.
1760 	 */
1761 	if (vd->vdev_ops == &vdev_draid_spare_ops)
1762 		return;
1763 
1764 	/* If the vdev was expanded, need to copy uberblock rings. */
1765 	if (vd->vdev_state == VDEV_STATE_HEALTHY &&
1766 	    vd->vdev_copy_uberblocks == B_TRUE) {
1767 		vdev_copy_uberblocks(vd);
1768 		vd->vdev_copy_uberblocks = B_FALSE;
1769 	}
1770 
1771 	/*
1772 	 * We chose a slot based on the txg.  If this uberblock has a special
1773 	 * RAIDZ expansion state, then it is essentially an update of the
1774 	 * current uberblock (it has the same txg).  However, the current
1775 	 * state is committed, so we want to write it to a different slot. If
1776 	 * we overwrote the same slot, and we lose power during the uberblock
1777 	 * write, and the disk does not do single-sector overwrites
1778 	 * atomically (even though it is required to - i.e. we should see
1779 	 * either the old or the new uberblock), then we could lose this
1780 	 * txg's uberblock. Rewinding to the previous txg's uberblock may not
1781 	 * be possible because RAIDZ expansion may have already overwritten
1782 	 * some of the data, so we need the progress indicator in the
1783 	 * uberblock.
1784 	 */
1785 	int m = spa_multihost(vd->vdev_spa) ? MMP_BLOCKS_PER_LABEL : 0;
1786 	int n = (ub->ub_txg - (RRSS_GET_STATE(ub) == RRSS_SCRATCH_VALID)) %
1787 	    (VDEV_UBERBLOCK_COUNT(vd) - m);
1788 
1789 	/* Copy the uberblock_t into the ABD */
1790 	abd_t *ub_abd = abd_alloc_for_io(VDEV_UBERBLOCK_SIZE(vd), B_TRUE);
1791 	abd_copy_from_buf(ub_abd, ub, sizeof (uberblock_t));
1792 	abd_zero_off(ub_abd, sizeof (uberblock_t),
1793 	    VDEV_UBERBLOCK_SIZE(vd) - sizeof (uberblock_t));
1794 
1795 	for (int l = 0; l < VDEV_LABELS; l++)
1796 		vdev_label_write(zio, vd, l, ub_abd,
1797 		    VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd),
1798 		    vdev_uberblock_sync_done, good_writes,
1799 		    flags | ZIO_FLAG_DONT_PROPAGATE);
1800 
1801 	abd_free(ub_abd);
1802 }
1803 
1804 /* Sync the uberblocks to all vdevs in svd[] */
1805 int
vdev_uberblock_sync_list(vdev_t ** svd,int svdcount,uberblock_t * ub,int flags)1806 vdev_uberblock_sync_list(vdev_t **svd, int svdcount, uberblock_t *ub, int flags)
1807 {
1808 	spa_t *spa = svd[0]->vdev_spa;
1809 	zio_t *zio;
1810 	uint64_t good_writes = 0;
1811 
1812 	zio = zio_root(spa, NULL, NULL, flags);
1813 
1814 	for (int v = 0; v < svdcount; v++)
1815 		vdev_uberblock_sync(zio, &good_writes, ub, svd[v], flags);
1816 
1817 	if (spa->spa_aux_sync_uber) {
1818 		for (int v = 0; v < spa->spa_spares.sav_count; v++) {
1819 			vdev_uberblock_sync(zio, &good_writes, ub,
1820 			    spa->spa_spares.sav_vdevs[v], flags);
1821 		}
1822 		for (int v = 0; v < spa->spa_l2cache.sav_count; v++) {
1823 			vdev_uberblock_sync(zio, &good_writes, ub,
1824 			    spa->spa_l2cache.sav_vdevs[v], flags);
1825 		}
1826 	}
1827 	(void) zio_wait(zio);
1828 
1829 	/*
1830 	 * Flush the uberblocks to disk.  This ensures that the odd labels
1831 	 * are no longer needed (because the new uberblocks and the even
1832 	 * labels are safely on disk), so it is safe to overwrite them.
1833 	 */
1834 	zio = zio_root(spa, NULL, NULL, flags);
1835 
1836 	for (int v = 0; v < svdcount; v++) {
1837 		if (vdev_writeable(svd[v])) {
1838 			zio_flush(zio, svd[v]);
1839 		}
1840 	}
1841 	if (spa->spa_aux_sync_uber) {
1842 		spa->spa_aux_sync_uber = B_FALSE;
1843 		for (int v = 0; v < spa->spa_spares.sav_count; v++) {
1844 			if (vdev_writeable(spa->spa_spares.sav_vdevs[v])) {
1845 				zio_flush(zio, spa->spa_spares.sav_vdevs[v]);
1846 			}
1847 		}
1848 		for (int v = 0; v < spa->spa_l2cache.sav_count; v++) {
1849 			if (vdev_writeable(spa->spa_l2cache.sav_vdevs[v])) {
1850 				zio_flush(zio, spa->spa_l2cache.sav_vdevs[v]);
1851 			}
1852 		}
1853 	}
1854 
1855 	(void) zio_wait(zio);
1856 
1857 	return (good_writes >= 1 ? 0 : EIO);
1858 }
1859 
1860 /*
1861  * On success, increment the count of good writes for our top-level vdev.
1862  */
1863 static void
vdev_label_sync_done(zio_t * zio)1864 vdev_label_sync_done(zio_t *zio)
1865 {
1866 	uint64_t *good_writes = zio->io_private;
1867 
1868 	if (zio->io_error == 0)
1869 		atomic_inc_64(good_writes);
1870 }
1871 
1872 /*
1873  * If there weren't enough good writes, indicate failure to the parent.
1874  */
1875 static void
vdev_label_sync_top_done(zio_t * zio)1876 vdev_label_sync_top_done(zio_t *zio)
1877 {
1878 	uint64_t *good_writes = zio->io_private;
1879 
1880 	if (*good_writes == 0)
1881 		zio->io_error = SET_ERROR(EIO);
1882 
1883 	kmem_free(good_writes, sizeof (uint64_t));
1884 }
1885 
1886 /*
1887  * We ignore errors for log and cache devices, simply free the private data.
1888  */
1889 static void
vdev_label_sync_ignore_done(zio_t * zio)1890 vdev_label_sync_ignore_done(zio_t *zio)
1891 {
1892 	kmem_free(zio->io_private, sizeof (uint64_t));
1893 }
1894 
1895 /*
1896  * Write all even or odd labels to all leaves of the specified vdev.
1897  */
1898 static void
vdev_label_sync(zio_t * zio,uint64_t * good_writes,vdev_t * vd,int l,uint64_t txg,int flags)1899 vdev_label_sync(zio_t *zio, uint64_t *good_writes,
1900     vdev_t *vd, int l, uint64_t txg, int flags)
1901 {
1902 	nvlist_t *label;
1903 	vdev_phys_t *vp;
1904 	abd_t *vp_abd;
1905 	char *buf;
1906 	size_t buflen;
1907 	vdev_t *pvd = vd->vdev_parent;
1908 	boolean_t spare_in_use = B_FALSE;
1909 
1910 	for (int c = 0; c < vd->vdev_children; c++) {
1911 		vdev_label_sync(zio, good_writes,
1912 		    vd->vdev_child[c], l, txg, flags);
1913 	}
1914 
1915 	if (!vd->vdev_ops->vdev_op_leaf)
1916 		return;
1917 
1918 	if (!vdev_writeable(vd))
1919 		return;
1920 
1921 	/*
1922 	 * The top-level config never needs to be written to a distributed
1923 	 * spare.  When read vdev_dspare_label_read_config() will generate
1924 	 * the config for the vdev_label_read_config().
1925 	 */
1926 	if (vd->vdev_ops == &vdev_draid_spare_ops)
1927 		return;
1928 
1929 	if (pvd && pvd->vdev_ops == &vdev_spare_ops)
1930 		spare_in_use = B_TRUE;
1931 
1932 	/*
1933 	 * Generate a label describing the top-level config to which we belong.
1934 	 */
1935 	if ((vd->vdev_isspare && !spare_in_use) || vd->vdev_isl2cache) {
1936 		label = vdev_aux_label_generate(vd, vd->vdev_isspare);
1937 	} else {
1938 		label = spa_config_generate(vd->vdev_spa, vd, txg, B_FALSE);
1939 	}
1940 
1941 	vp_abd = abd_alloc_linear(sizeof (vdev_phys_t), B_TRUE);
1942 	abd_zero(vp_abd, sizeof (vdev_phys_t));
1943 	vp = abd_to_buf(vp_abd);
1944 
1945 	buf = vp->vp_nvlist;
1946 	buflen = sizeof (vp->vp_nvlist);
1947 
1948 	if (!nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP)) {
1949 		for (; l < VDEV_LABELS; l += 2) {
1950 			vdev_label_write(zio, vd, l, vp_abd,
1951 			    offsetof(vdev_label_t, vl_vdev_phys),
1952 			    sizeof (vdev_phys_t),
1953 			    vdev_label_sync_done, good_writes,
1954 			    flags | ZIO_FLAG_DONT_PROPAGATE);
1955 		}
1956 	}
1957 
1958 	abd_free(vp_abd);
1959 	nvlist_free(label);
1960 }
1961 
1962 static int
vdev_label_sync_list(spa_t * spa,int l,uint64_t txg,int flags)1963 vdev_label_sync_list(spa_t *spa, int l, uint64_t txg, int flags)
1964 {
1965 	list_t *dl = &spa->spa_config_dirty_list;
1966 	vdev_t *vd;
1967 	zio_t *zio;
1968 	int error;
1969 
1970 	/*
1971 	 * Write the new labels to disk.
1972 	 */
1973 	zio = zio_root(spa, NULL, NULL, flags);
1974 
1975 	for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) {
1976 		uint64_t *good_writes;
1977 
1978 		ASSERT(!vd->vdev_ishole);
1979 
1980 		good_writes = kmem_zalloc(sizeof (uint64_t), KM_SLEEP);
1981 		zio_t *vio = zio_null(zio, spa, NULL,
1982 		    (vd->vdev_islog || vd->vdev_aux != NULL) ?
1983 		    vdev_label_sync_ignore_done : vdev_label_sync_top_done,
1984 		    good_writes, flags);
1985 		vdev_label_sync(vio, good_writes, vd, l, txg, flags);
1986 		zio_nowait(vio);
1987 	}
1988 
1989 	/*
1990 	 * AUX path may have changed during import
1991 	 */
1992 	spa_aux_vdev_t *sav[2] = {&spa->spa_spares, &spa->spa_l2cache};
1993 	for (int i = 0; i < 2; i++) {
1994 		for (int v = 0; v < sav[i]->sav_count; v++) {
1995 			uint64_t *good_writes;
1996 			if (!sav[i]->sav_label_sync)
1997 				continue;
1998 			good_writes = kmem_zalloc(sizeof (uint64_t), KM_SLEEP);
1999 			zio_t *vio = zio_null(zio, spa, NULL,
2000 			    vdev_label_sync_ignore_done, good_writes, flags);
2001 			vdev_label_sync(vio, good_writes, sav[i]->sav_vdevs[v],
2002 			    l, txg, flags);
2003 			zio_nowait(vio);
2004 		}
2005 	}
2006 
2007 	error = zio_wait(zio);
2008 
2009 	/*
2010 	 * Flush the new labels to disk.
2011 	 */
2012 	zio = zio_root(spa, NULL, NULL, flags);
2013 
2014 	for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd))
2015 		zio_flush(zio, vd);
2016 
2017 	for (int i = 0; i < 2; i++) {
2018 		if (!sav[i]->sav_label_sync)
2019 			continue;
2020 		for (int v = 0; v < sav[i]->sav_count; v++)
2021 			zio_flush(zio, sav[i]->sav_vdevs[v]);
2022 		if (l == 1)
2023 			sav[i]->sav_label_sync = B_FALSE;
2024 	}
2025 
2026 	(void) zio_wait(zio);
2027 
2028 	return (error);
2029 }
2030 
2031 /*
2032  * Sync the uberblock and any changes to the vdev configuration.
2033  *
2034  * The order of operations is carefully crafted to ensure that
2035  * if the system panics or loses power at any time, the state on disk
2036  * is still transactionally consistent.  The in-line comments below
2037  * describe the failure semantics at each stage.
2038  *
2039  * Moreover, vdev_config_sync() is designed to be idempotent: if it fails
2040  * at any time, you can just call it again, and it will resume its work.
2041  */
2042 int
vdev_config_sync(vdev_t ** svd,int svdcount,uint64_t txg)2043 vdev_config_sync(vdev_t **svd, int svdcount, uint64_t txg)
2044 {
2045 	spa_t *spa = svd[0]->vdev_spa;
2046 	uberblock_t *ub = &spa->spa_uberblock;
2047 	int error = 0;
2048 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
2049 
2050 	ASSERT(svdcount != 0);
2051 retry:
2052 	/*
2053 	 * Normally, we don't want to try too hard to write every label and
2054 	 * uberblock.  If there is a flaky disk, we don't want the rest of the
2055 	 * sync process to block while we retry.  But if we can't write a
2056 	 * single label out, we should retry with ZIO_FLAG_TRYHARD before
2057 	 * bailing out and declaring the pool faulted.
2058 	 */
2059 	if (error != 0) {
2060 		if ((flags & ZIO_FLAG_TRYHARD) != 0)
2061 			return (error);
2062 		flags |= ZIO_FLAG_TRYHARD;
2063 	}
2064 
2065 	ASSERT(ub->ub_txg <= txg);
2066 
2067 	/*
2068 	 * If this isn't a resync due to I/O errors,
2069 	 * and nothing changed in this transaction group,
2070 	 * and multihost protection isn't enabled,
2071 	 * and the vdev configuration hasn't changed,
2072 	 * then there's nothing to do.
2073 	 */
2074 	if (ub->ub_txg < txg) {
2075 		boolean_t changed = uberblock_update(ub, spa->spa_root_vdev,
2076 		    txg, spa->spa_mmp.mmp_delay);
2077 
2078 		if (!changed && list_is_empty(&spa->spa_config_dirty_list) &&
2079 		    !spa_multihost(spa))
2080 			return (0);
2081 	}
2082 
2083 	if (txg > spa_freeze_txg(spa))
2084 		return (0);
2085 
2086 	ASSERT(txg <= spa->spa_final_txg);
2087 
2088 	/*
2089 	 * Flush the write cache of every disk that's been written to
2090 	 * in this transaction group.  This ensures that all blocks
2091 	 * written in this txg will be committed to stable storage
2092 	 * before any uberblock that references them.
2093 	 */
2094 	zio_t *zio = zio_root(spa, NULL, NULL, flags);
2095 
2096 	for (vdev_t *vd =
2097 	    txg_list_head(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)); vd != NULL;
2098 	    vd = txg_list_next(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg)))
2099 		zio_flush(zio, vd);
2100 
2101 	(void) zio_wait(zio);
2102 
2103 	/*
2104 	 * Sync out the even labels (L0, L2) for every dirty vdev.  If the
2105 	 * system dies in the middle of this process, that's OK: all of the
2106 	 * even labels that made it to disk will be newer than any uberblock,
2107 	 * and will therefore be considered invalid.  The odd labels (L1, L3),
2108 	 * which have not yet been touched, will still be valid.  We flush
2109 	 * the new labels to disk to ensure that all even-label updates
2110 	 * are committed to stable storage before the uberblock update.
2111 	 */
2112 	if ((error = vdev_label_sync_list(spa, 0, txg, flags)) != 0) {
2113 		if ((flags & ZIO_FLAG_TRYHARD) != 0) {
2114 			zfs_dbgmsg("vdev_label_sync_list() returned error %d "
2115 			    "for pool '%s' when syncing out the even labels "
2116 			    "of dirty vdevs", error, spa_name(spa));
2117 		}
2118 		goto retry;
2119 	}
2120 
2121 	/*
2122 	 * Sync the uberblocks to all vdevs in svd[].
2123 	 * If the system dies in the middle of this step, there are two cases
2124 	 * to consider, and the on-disk state is consistent either way:
2125 	 *
2126 	 * (1)	If none of the new uberblocks made it to disk, then the
2127 	 *	previous uberblock will be the newest, and the odd labels
2128 	 *	(which had not yet been touched) will be valid with respect
2129 	 *	to that uberblock.
2130 	 *
2131 	 * (2)	If one or more new uberblocks made it to disk, then they
2132 	 *	will be the newest, and the even labels (which had all
2133 	 *	been successfully committed) will be valid with respect
2134 	 *	to the new uberblocks.
2135 	 */
2136 	if ((error = vdev_uberblock_sync_list(svd, svdcount, ub, flags)) != 0) {
2137 		if ((flags & ZIO_FLAG_TRYHARD) != 0) {
2138 			zfs_dbgmsg("vdev_uberblock_sync_list() returned error "
2139 			    "%d for pool '%s'", error, spa_name(spa));
2140 		}
2141 		goto retry;
2142 	}
2143 
2144 	if (spa_multihost(spa))
2145 		mmp_update_uberblock(spa, ub);
2146 
2147 	/*
2148 	 * Sync out odd labels for every dirty vdev.  If the system dies
2149 	 * in the middle of this process, the even labels and the new
2150 	 * uberblocks will suffice to open the pool.  The next time
2151 	 * the pool is opened, the first thing we'll do -- before any
2152 	 * user data is modified -- is mark every vdev dirty so that
2153 	 * all labels will be brought up to date.  We flush the new labels
2154 	 * to disk to ensure that all odd-label updates are committed to
2155 	 * stable storage before the next transaction group begins.
2156 	 */
2157 	if ((error = vdev_label_sync_list(spa, 1, txg, flags)) != 0) {
2158 		if ((flags & ZIO_FLAG_TRYHARD) != 0) {
2159 			zfs_dbgmsg("vdev_label_sync_list() returned error %d "
2160 			    "for pool '%s' when syncing out the odd labels of "
2161 			    "dirty vdevs", error, spa_name(spa));
2162 		}
2163 		goto retry;
2164 	}
2165 
2166 	return (0);
2167 }
2168