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