xref: /illumos-gate/usr/src/uts/common/fs/zfs/vdev_label.c (revision f94275ce205810a201404c5f35f4cc96057022b1)
1fa9e4066Sahrens /*
2fa9e4066Sahrens  * CDDL HEADER START
3fa9e4066Sahrens  *
4fa9e4066Sahrens  * The contents of this file are subject to the terms of the
5441d80aaSlling  * Common Development and Distribution License (the "License").
6441d80aaSlling  * You may not use this file except in compliance with the License.
7fa9e4066Sahrens  *
8fa9e4066Sahrens  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9fa9e4066Sahrens  * or http://www.opensolaris.org/os/licensing.
10fa9e4066Sahrens  * See the License for the specific language governing permissions
11fa9e4066Sahrens  * and limitations under the License.
12fa9e4066Sahrens  *
13fa9e4066Sahrens  * When distributing Covered Code, include this CDDL HEADER in each
14fa9e4066Sahrens  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15fa9e4066Sahrens  * If applicable, add the following below this CDDL HEADER, with the
16fa9e4066Sahrens  * fields enclosed by brackets "[]" replaced with your own identifying
17fa9e4066Sahrens  * information: Portions Copyright [yyyy] [name of copyright owner]
18fa9e4066Sahrens  *
19fa9e4066Sahrens  * CDDL HEADER END
20fa9e4066Sahrens  */
21fa9e4066Sahrens /*
22a3f829aeSBill Moore  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
23fa9e4066Sahrens  * Use is subject to license terms.
24fa9e4066Sahrens  */
25fa9e4066Sahrens 
26fa9e4066Sahrens /*
27fa9e4066Sahrens  * Virtual Device Labels
28fa9e4066Sahrens  * ---------------------
29fa9e4066Sahrens  *
30fa9e4066Sahrens  * The vdev label serves several distinct purposes:
31fa9e4066Sahrens  *
32fa9e4066Sahrens  *	1. Uniquely identify this device as part of a ZFS pool and confirm its
33fa9e4066Sahrens  *	   identity within the pool.
34fa9e4066Sahrens  *
35fa9e4066Sahrens  * 	2. Verify that all the devices given in a configuration are present
36fa9e4066Sahrens  *         within the pool.
37fa9e4066Sahrens  *
38fa9e4066Sahrens  * 	3. Determine the uberblock for the pool.
39fa9e4066Sahrens  *
40fa9e4066Sahrens  * 	4. In case of an import operation, determine the configuration of the
41fa9e4066Sahrens  *         toplevel vdev of which it is a part.
42fa9e4066Sahrens  *
43fa9e4066Sahrens  * 	5. If an import operation cannot find all the devices in the pool,
44fa9e4066Sahrens  *         provide enough information to the administrator to determine which
45fa9e4066Sahrens  *         devices are missing.
46fa9e4066Sahrens  *
47fa9e4066Sahrens  * It is important to note that while the kernel is responsible for writing the
48fa9e4066Sahrens  * label, it only consumes the information in the first three cases.  The
49fa9e4066Sahrens  * latter information is only consumed in userland when determining the
50fa9e4066Sahrens  * configuration to import a pool.
51fa9e4066Sahrens  *
52fa9e4066Sahrens  *
53fa9e4066Sahrens  * Label Organization
54fa9e4066Sahrens  * ------------------
55fa9e4066Sahrens  *
56fa9e4066Sahrens  * Before describing the contents of the label, it's important to understand how
57fa9e4066Sahrens  * the labels are written and updated with respect to the uberblock.
58fa9e4066Sahrens  *
59fa9e4066Sahrens  * When the pool configuration is altered, either because it was newly created
60fa9e4066Sahrens  * or a device was added, we want to update all the labels such that we can deal
61fa9e4066Sahrens  * with fatal failure at any point.  To this end, each disk has two labels which
62fa9e4066Sahrens  * are updated before and after the uberblock is synced.  Assuming we have
633d7072f8Seschrock  * labels and an uberblock with the following transaction groups:
64fa9e4066Sahrens  *
65fa9e4066Sahrens  *              L1          UB          L2
66fa9e4066Sahrens  *           +------+    +------+    +------+
67fa9e4066Sahrens  *           |      |    |      |    |      |
68fa9e4066Sahrens  *           | t10  |    | t10  |    | t10  |
69fa9e4066Sahrens  *           |      |    |      |    |      |
70fa9e4066Sahrens  *           +------+    +------+    +------+
71fa9e4066Sahrens  *
72fa9e4066Sahrens  * In this stable state, the labels and the uberblock were all updated within
73fa9e4066Sahrens  * the same transaction group (10).  Each label is mirrored and checksummed, so
74fa9e4066Sahrens  * that we can detect when we fail partway through writing the label.
75fa9e4066Sahrens  *
76fa9e4066Sahrens  * In order to identify which labels are valid, the labels are written in the
77fa9e4066Sahrens  * following manner:
78fa9e4066Sahrens  *
79fa9e4066Sahrens  * 	1. For each vdev, update 'L1' to the new label
80fa9e4066Sahrens  * 	2. Update the uberblock
81fa9e4066Sahrens  * 	3. For each vdev, update 'L2' to the new label
82fa9e4066Sahrens  *
83fa9e4066Sahrens  * Given arbitrary failure, we can determine the correct label to use based on
84fa9e4066Sahrens  * the transaction group.  If we fail after updating L1 but before updating the
85fa9e4066Sahrens  * UB, we will notice that L1's transaction group is greater than the uberblock,
86fa9e4066Sahrens  * so L2 must be valid.  If we fail after writing the uberblock but before
87fa9e4066Sahrens  * writing L2, we will notice that L2's transaction group is less than L1, and
88fa9e4066Sahrens  * therefore L1 is valid.
89fa9e4066Sahrens  *
90fa9e4066Sahrens  * Another added complexity is that not every label is updated when the config
91fa9e4066Sahrens  * is synced.  If we add a single device, we do not want to have to re-write
92fa9e4066Sahrens  * every label for every device in the pool.  This means that both L1 and L2 may
93fa9e4066Sahrens  * be older than the pool uberblock, because the necessary information is stored
94fa9e4066Sahrens  * on another vdev.
95fa9e4066Sahrens  *
96fa9e4066Sahrens  *
97fa9e4066Sahrens  * On-disk Format
98fa9e4066Sahrens  * --------------
99fa9e4066Sahrens  *
100fa9e4066Sahrens  * The vdev label consists of two distinct parts, and is wrapped within the
101fa9e4066Sahrens  * vdev_label_t structure.  The label includes 8k of padding to permit legacy
102fa9e4066Sahrens  * VTOC disk labels, but is otherwise ignored.
103fa9e4066Sahrens  *
104fa9e4066Sahrens  * The first half of the label is a packed nvlist which contains pool wide
105fa9e4066Sahrens  * properties, per-vdev properties, and configuration information.  It is
106fa9e4066Sahrens  * described in more detail below.
107fa9e4066Sahrens  *
108fa9e4066Sahrens  * The latter half of the label consists of a redundant array of uberblocks.
109fa9e4066Sahrens  * These uberblocks are updated whenever a transaction group is committed,
110fa9e4066Sahrens  * or when the configuration is updated.  When a pool is loaded, we scan each
111fa9e4066Sahrens  * vdev for the 'best' uberblock.
112fa9e4066Sahrens  *
113fa9e4066Sahrens  *
114fa9e4066Sahrens  * Configuration Information
115fa9e4066Sahrens  * -------------------------
116fa9e4066Sahrens  *
117fa9e4066Sahrens  * The nvlist describing the pool and vdev contains the following elements:
118fa9e4066Sahrens  *
119fa9e4066Sahrens  * 	version		ZFS on-disk version
120fa9e4066Sahrens  * 	name		Pool name
121fa9e4066Sahrens  * 	state		Pool state
122fa9e4066Sahrens  * 	txg		Transaction group in which this label was written
123fa9e4066Sahrens  * 	pool_guid	Unique identifier for this pool
124fa9e4066Sahrens  * 	vdev_tree	An nvlist describing vdev tree.
125fa9e4066Sahrens  *
126fa9e4066Sahrens  * Each leaf device label also contains the following:
127fa9e4066Sahrens  *
128fa9e4066Sahrens  * 	top_guid	Unique ID for top-level vdev in which this is contained
129fa9e4066Sahrens  * 	guid		Unique ID for the leaf vdev
130fa9e4066Sahrens  *
131fa9e4066Sahrens  * The 'vs' configuration follows the format described in 'spa_config.c'.
132fa9e4066Sahrens  */
133fa9e4066Sahrens 
134fa9e4066Sahrens #include <sys/zfs_context.h>
135fa9e4066Sahrens #include <sys/spa.h>
136fa9e4066Sahrens #include <sys/spa_impl.h>
137fa9e4066Sahrens #include <sys/dmu.h>
138fa9e4066Sahrens #include <sys/zap.h>
139fa9e4066Sahrens #include <sys/vdev.h>
140fa9e4066Sahrens #include <sys/vdev_impl.h>
141fa9e4066Sahrens #include <sys/uberblock_impl.h>
142fa9e4066Sahrens #include <sys/metaslab.h>
143fa9e4066Sahrens #include <sys/zio.h>
144fa9e4066Sahrens #include <sys/fs/zfs.h>
145fa9e4066Sahrens 
146fa9e4066Sahrens /*
147fa9e4066Sahrens  * Basic routines to read and write from a vdev label.
148fa9e4066Sahrens  * Used throughout the rest of this file.
149fa9e4066Sahrens  */
150fa9e4066Sahrens uint64_t
151fa9e4066Sahrens vdev_label_offset(uint64_t psize, int l, uint64_t offset)
152fa9e4066Sahrens {
153ecc2d604Sbonwick 	ASSERT(offset < sizeof (vdev_label_t));
154e7437265Sahrens 	ASSERT(P2PHASE_TYPED(psize, sizeof (vdev_label_t), uint64_t) == 0);
155ecc2d604Sbonwick 
156fa9e4066Sahrens 	return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ?
157fa9e4066Sahrens 	    0 : psize - VDEV_LABELS * sizeof (vdev_label_t)));
158fa9e4066Sahrens }
159fa9e4066Sahrens 
16021bf64a7Sgw /*
16121bf64a7Sgw  * Returns back the vdev label associated with the passed in offset.
16221bf64a7Sgw  */
16321bf64a7Sgw int
16421bf64a7Sgw vdev_label_number(uint64_t psize, uint64_t offset)
16521bf64a7Sgw {
16621bf64a7Sgw 	int l;
16721bf64a7Sgw 
16821bf64a7Sgw 	if (offset >= psize - VDEV_LABEL_END_SIZE) {
16921bf64a7Sgw 		offset -= psize - VDEV_LABEL_END_SIZE;
17021bf64a7Sgw 		offset += (VDEV_LABELS / 2) * sizeof (vdev_label_t);
17121bf64a7Sgw 	}
17221bf64a7Sgw 	l = offset / sizeof (vdev_label_t);
17321bf64a7Sgw 	return (l < VDEV_LABELS ? l : -1);
17421bf64a7Sgw }
17521bf64a7Sgw 
176fa9e4066Sahrens static void
177fa9e4066Sahrens vdev_label_read(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
178e14bb325SJeff Bonwick 	uint64_t size, zio_done_func_t *done, void *private, int flags)
179fa9e4066Sahrens {
180e14bb325SJeff Bonwick 	ASSERT(spa_config_held(zio->io_spa, SCL_STATE_ALL, RW_WRITER) ==
181e14bb325SJeff Bonwick 	    SCL_STATE_ALL);
182e14bb325SJeff Bonwick 	ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
183fa9e4066Sahrens 
184fa9e4066Sahrens 	zio_nowait(zio_read_phys(zio, vd,
185fa9e4066Sahrens 	    vdev_label_offset(vd->vdev_psize, l, offset),
186fa9e4066Sahrens 	    size, buf, ZIO_CHECKSUM_LABEL, done, private,
187e14bb325SJeff Bonwick 	    ZIO_PRIORITY_SYNC_READ, flags, B_TRUE));
188fa9e4066Sahrens }
189fa9e4066Sahrens 
190fa9e4066Sahrens static void
191fa9e4066Sahrens vdev_label_write(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
19217f17c2dSbonwick 	uint64_t size, zio_done_func_t *done, void *private, int flags)
193fa9e4066Sahrens {
194e14bb325SJeff Bonwick 	ASSERT(spa_config_held(zio->io_spa, SCL_ALL, RW_WRITER) == SCL_ALL ||
195e14bb325SJeff Bonwick 	    (spa_config_held(zio->io_spa, SCL_CONFIG | SCL_STATE, RW_READER) ==
196e14bb325SJeff Bonwick 	    (SCL_CONFIG | SCL_STATE) &&
197e14bb325SJeff Bonwick 	    dsl_pool_sync_context(spa_get_dsl(zio->io_spa))));
198e14bb325SJeff Bonwick 	ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
199fa9e4066Sahrens 
200fa9e4066Sahrens 	zio_nowait(zio_write_phys(zio, vd,
201fa9e4066Sahrens 	    vdev_label_offset(vd->vdev_psize, l, offset),
202fa9e4066Sahrens 	    size, buf, ZIO_CHECKSUM_LABEL, done, private,
20317f17c2dSbonwick 	    ZIO_PRIORITY_SYNC_WRITE, flags, B_TRUE));
204fa9e4066Sahrens }
205fa9e4066Sahrens 
206fa9e4066Sahrens /*
207fa9e4066Sahrens  * Generate the nvlist representing this vdev's config.
208fa9e4066Sahrens  */
209fa9e4066Sahrens nvlist_t *
21099653d4eSeschrock vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats,
211fa94a07fSbrendan     boolean_t isspare, boolean_t isl2cache)
212fa9e4066Sahrens {
213fa9e4066Sahrens 	nvlist_t *nv = NULL;
214fa9e4066Sahrens 
215ea8dc4b6Seschrock 	VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0);
216fa9e4066Sahrens 
217fa9e4066Sahrens 	VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_TYPE,
218fa9e4066Sahrens 	    vd->vdev_ops->vdev_op_type) == 0);
219fa94a07fSbrendan 	if (!isspare && !isl2cache)
22099653d4eSeschrock 		VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ID, vd->vdev_id)
22199653d4eSeschrock 		    == 0);
222fa9e4066Sahrens 	VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_GUID, vd->vdev_guid) == 0);
223fa9e4066Sahrens 
224fa9e4066Sahrens 	if (vd->vdev_path != NULL)
225fa9e4066Sahrens 		VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PATH,
226fa9e4066Sahrens 		    vd->vdev_path) == 0);
227fa9e4066Sahrens 
228fa9e4066Sahrens 	if (vd->vdev_devid != NULL)
229fa9e4066Sahrens 		VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_DEVID,
230fa9e4066Sahrens 		    vd->vdev_devid) == 0);
231fa9e4066Sahrens 
2323d7072f8Seschrock 	if (vd->vdev_physpath != NULL)
2333d7072f8Seschrock 		VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PHYS_PATH,
2343d7072f8Seschrock 		    vd->vdev_physpath) == 0);
2353d7072f8Seschrock 
2366809eb4eSEric Schrock 	if (vd->vdev_fru != NULL)
2376809eb4eSEric Schrock 		VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_FRU,
2386809eb4eSEric Schrock 		    vd->vdev_fru) == 0);
2396809eb4eSEric Schrock 
24099653d4eSeschrock 	if (vd->vdev_nparity != 0) {
24199653d4eSeschrock 		ASSERT(strcmp(vd->vdev_ops->vdev_op_type,
24299653d4eSeschrock 		    VDEV_TYPE_RAIDZ) == 0);
24399653d4eSeschrock 
24499653d4eSeschrock 		/*
24599653d4eSeschrock 		 * Make sure someone hasn't managed to sneak a fancy new vdev
24699653d4eSeschrock 		 * into a crufty old storage pool.
24799653d4eSeschrock 		 */
24899653d4eSeschrock 		ASSERT(vd->vdev_nparity == 1 ||
249*f94275ceSAdam Leventhal 		    (vd->vdev_nparity <= 2 &&
250*f94275ceSAdam Leventhal 		    spa_version(spa) >= SPA_VERSION_RAIDZ2) ||
251*f94275ceSAdam Leventhal 		    (vd->vdev_nparity <= 3 &&
252*f94275ceSAdam Leventhal 		    spa_version(spa) >= SPA_VERSION_RAIDZ3));
25399653d4eSeschrock 
25499653d4eSeschrock 		/*
25599653d4eSeschrock 		 * Note that we'll add the nparity tag even on storage pools
25699653d4eSeschrock 		 * that only support a single parity device -- older software
25799653d4eSeschrock 		 * will just ignore it.
25899653d4eSeschrock 		 */
25999653d4eSeschrock 		VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY,
26099653d4eSeschrock 		    vd->vdev_nparity) == 0);
26199653d4eSeschrock 	}
26299653d4eSeschrock 
263afefbcddSeschrock 	if (vd->vdev_wholedisk != -1ULL)
264afefbcddSeschrock 		VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
265afefbcddSeschrock 		    vd->vdev_wholedisk) == 0);
266afefbcddSeschrock 
267ea8dc4b6Seschrock 	if (vd->vdev_not_present)
268ea8dc4b6Seschrock 		VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT, 1) == 0);
269ea8dc4b6Seschrock 
27099653d4eSeschrock 	if (vd->vdev_isspare)
27199653d4eSeschrock 		VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_SPARE, 1) == 0);
27299653d4eSeschrock 
273fa94a07fSbrendan 	if (!isspare && !isl2cache && vd == vd->vdev_top) {
274fa9e4066Sahrens 		VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
275fa9e4066Sahrens 		    vd->vdev_ms_array) == 0);
276fa9e4066Sahrens 		VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT,
277fa9e4066Sahrens 		    vd->vdev_ms_shift) == 0);
278fa9e4066Sahrens 		VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASHIFT,
279fa9e4066Sahrens 		    vd->vdev_ashift) == 0);
280fa9e4066Sahrens 		VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASIZE,
281fa9e4066Sahrens 		    vd->vdev_asize) == 0);
2828654d025Sperrin 		VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_LOG,
2838654d025Sperrin 		    vd->vdev_islog) == 0);
284fa9e4066Sahrens 	}
285fa9e4066Sahrens 
2868ad4d6ddSJeff Bonwick 	if (vd->vdev_dtl_smo.smo_object != 0)
287fa9e4066Sahrens 		VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DTL,
2888ad4d6ddSJeff Bonwick 		    vd->vdev_dtl_smo.smo_object) == 0);
289fa9e4066Sahrens 
290fa9e4066Sahrens 	if (getstats) {
291fa9e4066Sahrens 		vdev_stat_t vs;
292fa9e4066Sahrens 		vdev_get_stats(vd, &vs);
293fa9e4066Sahrens 		VERIFY(nvlist_add_uint64_array(nv, ZPOOL_CONFIG_STATS,
294fa9e4066Sahrens 		    (uint64_t *)&vs, sizeof (vs) / sizeof (uint64_t)) == 0);
295fa9e4066Sahrens 	}
296fa9e4066Sahrens 
297fa9e4066Sahrens 	if (!vd->vdev_ops->vdev_op_leaf) {
298fa9e4066Sahrens 		nvlist_t **child;
299fa9e4066Sahrens 		int c;
300fa9e4066Sahrens 
301fa9e4066Sahrens 		child = kmem_alloc(vd->vdev_children * sizeof (nvlist_t *),
302fa9e4066Sahrens 		    KM_SLEEP);
303fa9e4066Sahrens 
304fa9e4066Sahrens 		for (c = 0; c < vd->vdev_children; c++)
30599653d4eSeschrock 			child[c] = vdev_config_generate(spa, vd->vdev_child[c],
306fa94a07fSbrendan 			    getstats, isspare, isl2cache);
307fa9e4066Sahrens 
308fa9e4066Sahrens 		VERIFY(nvlist_add_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
309fa9e4066Sahrens 		    child, vd->vdev_children) == 0);
310fa9e4066Sahrens 
311fa9e4066Sahrens 		for (c = 0; c < vd->vdev_children; c++)
312fa9e4066Sahrens 			nvlist_free(child[c]);
313fa9e4066Sahrens 
314fa9e4066Sahrens 		kmem_free(child, vd->vdev_children * sizeof (nvlist_t *));
315441d80aaSlling 
316441d80aaSlling 	} else {
317ecc2d604Sbonwick 		if (vd->vdev_offline && !vd->vdev_tmpoffline)
318441d80aaSlling 			VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_OFFLINE,
319ecc2d604Sbonwick 			    B_TRUE) == 0);
3203d7072f8Seschrock 		if (vd->vdev_faulted)
3213d7072f8Seschrock 			VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_FAULTED,
3223d7072f8Seschrock 			    B_TRUE) == 0);
3233d7072f8Seschrock 		if (vd->vdev_degraded)
3243d7072f8Seschrock 			VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DEGRADED,
3253d7072f8Seschrock 			    B_TRUE) == 0);
3263d7072f8Seschrock 		if (vd->vdev_removed)
3273d7072f8Seschrock 			VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVED,
3283d7072f8Seschrock 			    B_TRUE) == 0);
3293d7072f8Seschrock 		if (vd->vdev_unspare)
3303d7072f8Seschrock 			VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_UNSPARE,
3313d7072f8Seschrock 			    B_TRUE) == 0);
332fa9e4066Sahrens 	}
333fa9e4066Sahrens 
334fa9e4066Sahrens 	return (nv);
335fa9e4066Sahrens }
336fa9e4066Sahrens 
337fa9e4066Sahrens nvlist_t *
338fa9e4066Sahrens vdev_label_read_config(vdev_t *vd)
339fa9e4066Sahrens {
3400373e76bSbonwick 	spa_t *spa = vd->vdev_spa;
341fa9e4066Sahrens 	nvlist_t *config = NULL;
342fa9e4066Sahrens 	vdev_phys_t *vp;
343fa9e4066Sahrens 	zio_t *zio;
3448956713aSEric Schrock 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
3458956713aSEric Schrock 	    ZIO_FLAG_SPECULATIVE;
346fa9e4066Sahrens 
347e14bb325SJeff Bonwick 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
3480373e76bSbonwick 
3490a4e9518Sgw 	if (!vdev_readable(vd))
350fa9e4066Sahrens 		return (NULL);
351fa9e4066Sahrens 
352fa9e4066Sahrens 	vp = zio_buf_alloc(sizeof (vdev_phys_t));
353fa9e4066Sahrens 
3548956713aSEric Schrock retry:
355e14bb325SJeff Bonwick 	for (int l = 0; l < VDEV_LABELS; l++) {
356fa9e4066Sahrens 
357e14bb325SJeff Bonwick 		zio = zio_root(spa, NULL, NULL, flags);
358fa9e4066Sahrens 
359fa9e4066Sahrens 		vdev_label_read(zio, vd, l, vp,
360fa9e4066Sahrens 		    offsetof(vdev_label_t, vl_vdev_phys),
361e14bb325SJeff Bonwick 		    sizeof (vdev_phys_t), NULL, NULL, flags);
362fa9e4066Sahrens 
363fa9e4066Sahrens 		if (zio_wait(zio) == 0 &&
364fa9e4066Sahrens 		    nvlist_unpack(vp->vp_nvlist, sizeof (vp->vp_nvlist),
365ea8dc4b6Seschrock 		    &config, 0) == 0)
366fa9e4066Sahrens 			break;
367fa9e4066Sahrens 
368fa9e4066Sahrens 		if (config != NULL) {
369fa9e4066Sahrens 			nvlist_free(config);
370fa9e4066Sahrens 			config = NULL;
371fa9e4066Sahrens 		}
372fa9e4066Sahrens 	}
373fa9e4066Sahrens 
3748956713aSEric Schrock 	if (config == NULL && !(flags & ZIO_FLAG_TRYHARD)) {
3758956713aSEric Schrock 		flags |= ZIO_FLAG_TRYHARD;
3768956713aSEric Schrock 		goto retry;
3778956713aSEric Schrock 	}
3788956713aSEric Schrock 
379fa9e4066Sahrens 	zio_buf_free(vp, sizeof (vdev_phys_t));
380fa9e4066Sahrens 
381fa9e4066Sahrens 	return (config);
382fa9e4066Sahrens }
383fa9e4066Sahrens 
38439c23413Seschrock /*
38539c23413Seschrock  * Determine if a device is in use.  The 'spare_guid' parameter will be filled
38639c23413Seschrock  * in with the device guid if this spare is active elsewhere on the system.
38739c23413Seschrock  */
38839c23413Seschrock static boolean_t
38939c23413Seschrock vdev_inuse(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason,
390fa94a07fSbrendan     uint64_t *spare_guid, uint64_t *l2cache_guid)
39139c23413Seschrock {
39239c23413Seschrock 	spa_t *spa = vd->vdev_spa;
39339c23413Seschrock 	uint64_t state, pool_guid, device_guid, txg, spare_pool;
39439c23413Seschrock 	uint64_t vdtxg = 0;
39539c23413Seschrock 	nvlist_t *label;
39639c23413Seschrock 
39739c23413Seschrock 	if (spare_guid)
39839c23413Seschrock 		*spare_guid = 0ULL;
399fa94a07fSbrendan 	if (l2cache_guid)
400fa94a07fSbrendan 		*l2cache_guid = 0ULL;
40139c23413Seschrock 
40239c23413Seschrock 	/*
40339c23413Seschrock 	 * Read the label, if any, and perform some basic sanity checks.
40439c23413Seschrock 	 */
40539c23413Seschrock 	if ((label = vdev_label_read_config(vd)) == NULL)
40639c23413Seschrock 		return (B_FALSE);
40739c23413Seschrock 
40839c23413Seschrock 	(void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
40939c23413Seschrock 	    &vdtxg);
41039c23413Seschrock 
41139c23413Seschrock 	if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
41239c23413Seschrock 	    &state) != 0 ||
41339c23413Seschrock 	    nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID,
41439c23413Seschrock 	    &device_guid) != 0) {
41539c23413Seschrock 		nvlist_free(label);
41639c23413Seschrock 		return (B_FALSE);
41739c23413Seschrock 	}
41839c23413Seschrock 
419fa94a07fSbrendan 	if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
42039c23413Seschrock 	    (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID,
42139c23413Seschrock 	    &pool_guid) != 0 ||
42239c23413Seschrock 	    nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG,
42339c23413Seschrock 	    &txg) != 0)) {
42439c23413Seschrock 		nvlist_free(label);
42539c23413Seschrock 		return (B_FALSE);
42639c23413Seschrock 	}
42739c23413Seschrock 
42839c23413Seschrock 	nvlist_free(label);
42939c23413Seschrock 
43039c23413Seschrock 	/*
43139c23413Seschrock 	 * Check to see if this device indeed belongs to the pool it claims to
43239c23413Seschrock 	 * be a part of.  The only way this is allowed is if the device is a hot
43339c23413Seschrock 	 * spare (which we check for later on).
43439c23413Seschrock 	 */
435fa94a07fSbrendan 	if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
43639c23413Seschrock 	    !spa_guid_exists(pool_guid, device_guid) &&
43789a89ebfSlling 	    !spa_spare_exists(device_guid, NULL, NULL) &&
438fa94a07fSbrendan 	    !spa_l2cache_exists(device_guid, NULL))
43939c23413Seschrock 		return (B_FALSE);
44039c23413Seschrock 
44139c23413Seschrock 	/*
44239c23413Seschrock 	 * If the transaction group is zero, then this an initialized (but
44339c23413Seschrock 	 * unused) label.  This is only an error if the create transaction
44439c23413Seschrock 	 * on-disk is the same as the one we're using now, in which case the
44539c23413Seschrock 	 * user has attempted to add the same vdev multiple times in the same
44639c23413Seschrock 	 * transaction.
44739c23413Seschrock 	 */
448fa94a07fSbrendan 	if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
449fa94a07fSbrendan 	    txg == 0 && vdtxg == crtxg)
45039c23413Seschrock 		return (B_TRUE);
45139c23413Seschrock 
45239c23413Seschrock 	/*
45339c23413Seschrock 	 * Check to see if this is a spare device.  We do an explicit check for
45439c23413Seschrock 	 * spa_has_spare() here because it may be on our pending list of spares
455fa94a07fSbrendan 	 * to add.  We also check if it is an l2cache device.
45639c23413Seschrock 	 */
45789a89ebfSlling 	if (spa_spare_exists(device_guid, &spare_pool, NULL) ||
45839c23413Seschrock 	    spa_has_spare(spa, device_guid)) {
45939c23413Seschrock 		if (spare_guid)
46039c23413Seschrock 			*spare_guid = device_guid;
46139c23413Seschrock 
46239c23413Seschrock 		switch (reason) {
46339c23413Seschrock 		case VDEV_LABEL_CREATE:
464fa94a07fSbrendan 		case VDEV_LABEL_L2CACHE:
46539c23413Seschrock 			return (B_TRUE);
46639c23413Seschrock 
46739c23413Seschrock 		case VDEV_LABEL_REPLACE:
46839c23413Seschrock 			return (!spa_has_spare(spa, device_guid) ||
46939c23413Seschrock 			    spare_pool != 0ULL);
47039c23413Seschrock 
47139c23413Seschrock 		case VDEV_LABEL_SPARE:
47239c23413Seschrock 			return (spa_has_spare(spa, device_guid));
47339c23413Seschrock 		}
47439c23413Seschrock 	}
47539c23413Seschrock 
476fa94a07fSbrendan 	/*
477fa94a07fSbrendan 	 * Check to see if this is an l2cache device.
478fa94a07fSbrendan 	 */
479fa94a07fSbrendan 	if (spa_l2cache_exists(device_guid, NULL))
480fa94a07fSbrendan 		return (B_TRUE);
481fa94a07fSbrendan 
48239c23413Seschrock 	/*
48339c23413Seschrock 	 * If the device is marked ACTIVE, then this device is in use by another
48439c23413Seschrock 	 * pool on the system.
48539c23413Seschrock 	 */
48639c23413Seschrock 	return (state == POOL_STATE_ACTIVE);
48739c23413Seschrock }
48839c23413Seschrock 
48939c23413Seschrock /*
49039c23413Seschrock  * Initialize a vdev label.  We check to make sure each leaf device is not in
49139c23413Seschrock  * use, and writable.  We put down an initial label which we will later
49239c23413Seschrock  * overwrite with a complete label.  Note that it's important to do this
49339c23413Seschrock  * sequentially, not in parallel, so that we catch cases of multiple use of the
49439c23413Seschrock  * same leaf vdev in the vdev we're creating -- e.g. mirroring a disk with
49539c23413Seschrock  * itself.
49639c23413Seschrock  */
49739c23413Seschrock int
49839c23413Seschrock vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
499fa9e4066Sahrens {
500fa9e4066Sahrens 	spa_t *spa = vd->vdev_spa;
501fa9e4066Sahrens 	nvlist_t *label;
502fa9e4066Sahrens 	vdev_phys_t *vp;
503f83ffe1aSLin Ling 	char *pad2;
504ecc2d604Sbonwick 	uberblock_t *ub;
505fa9e4066Sahrens 	zio_t *zio;
506fa9e4066Sahrens 	char *buf;
507fa9e4066Sahrens 	size_t buflen;
508fa9e4066Sahrens 	int error;
509fa94a07fSbrendan 	uint64_t spare_guid, l2cache_guid;
510e14bb325SJeff Bonwick 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
511fa9e4066Sahrens 
512e14bb325SJeff Bonwick 	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
5130373e76bSbonwick 
514e14bb325SJeff Bonwick 	for (int c = 0; c < vd->vdev_children; c++)
51539c23413Seschrock 		if ((error = vdev_label_init(vd->vdev_child[c],
51639c23413Seschrock 		    crtxg, reason)) != 0)
517fa9e4066Sahrens 			return (error);
518fa9e4066Sahrens 
519fa9e4066Sahrens 	if (!vd->vdev_ops->vdev_op_leaf)
520fa9e4066Sahrens 		return (0);
521fa9e4066Sahrens 
522fa9e4066Sahrens 	/*
52339c23413Seschrock 	 * Dead vdevs cannot be initialized.
524fa9e4066Sahrens 	 */
525fa9e4066Sahrens 	if (vdev_is_dead(vd))
526fa9e4066Sahrens 		return (EIO);
527fa9e4066Sahrens 
528fa9e4066Sahrens 	/*
52939c23413Seschrock 	 * Determine if the vdev is in use.
530fa9e4066Sahrens 	 */
53139c23413Seschrock 	if (reason != VDEV_LABEL_REMOVE &&
532fa94a07fSbrendan 	    vdev_inuse(vd, crtxg, reason, &spare_guid, &l2cache_guid))
53339c23413Seschrock 		return (EBUSY);
53439c23413Seschrock 
53539c23413Seschrock 	/*
536fa94a07fSbrendan 	 * If this is a request to add or replace a spare or l2cache device
537fa94a07fSbrendan 	 * that is in use elsewhere on the system, then we must update the
538fa94a07fSbrendan 	 * guid (which was initialized to a random value) to reflect the
539fa94a07fSbrendan 	 * actual GUID (which is shared between multiple pools).
54039c23413Seschrock 	 */
541fa94a07fSbrendan 	if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_L2CACHE &&
542fa94a07fSbrendan 	    spare_guid != 0ULL) {
54331157203SJeff Bonwick 		uint64_t guid_delta = spare_guid - vd->vdev_guid;
54499653d4eSeschrock 
54531157203SJeff Bonwick 		vd->vdev_guid += guid_delta;
54631157203SJeff Bonwick 
54731157203SJeff Bonwick 		for (vdev_t *pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
54831157203SJeff Bonwick 			pvd->vdev_guid_sum += guid_delta;
54939c23413Seschrock 
55099653d4eSeschrock 		/*
55139c23413Seschrock 		 * If this is a replacement, then we want to fallthrough to the
55239c23413Seschrock 		 * rest of the code.  If we're adding a spare, then it's already
5533d7072f8Seschrock 		 * labeled appropriately and we can just return.
55499653d4eSeschrock 		 */
55539c23413Seschrock 		if (reason == VDEV_LABEL_SPARE)
55639c23413Seschrock 			return (0);
55739c23413Seschrock 		ASSERT(reason == VDEV_LABEL_REPLACE);
558fa9e4066Sahrens 	}
559fa9e4066Sahrens 
560fa94a07fSbrendan 	if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPARE &&
561fa94a07fSbrendan 	    l2cache_guid != 0ULL) {
56231157203SJeff Bonwick 		uint64_t guid_delta = l2cache_guid - vd->vdev_guid;
56331157203SJeff Bonwick 
56431157203SJeff Bonwick 		vd->vdev_guid += guid_delta;
565fa94a07fSbrendan 
56631157203SJeff Bonwick 		for (vdev_t *pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
56731157203SJeff Bonwick 			pvd->vdev_guid_sum += guid_delta;
568fa94a07fSbrendan 
569fa94a07fSbrendan 		/*
570fa94a07fSbrendan 		 * If this is a replacement, then we want to fallthrough to the
571fa94a07fSbrendan 		 * rest of the code.  If we're adding an l2cache, then it's
572fa94a07fSbrendan 		 * already labeled appropriately and we can just return.
573fa94a07fSbrendan 		 */
574fa94a07fSbrendan 		if (reason == VDEV_LABEL_L2CACHE)
575fa94a07fSbrendan 			return (0);
576fa94a07fSbrendan 		ASSERT(reason == VDEV_LABEL_REPLACE);
577fa94a07fSbrendan 	}
578fa94a07fSbrendan 
579fa9e4066Sahrens 	/*
58039c23413Seschrock 	 * Initialize its label.
581fa9e4066Sahrens 	 */
582fa9e4066Sahrens 	vp = zio_buf_alloc(sizeof (vdev_phys_t));
583fa9e4066Sahrens 	bzero(vp, sizeof (vdev_phys_t));
584fa9e4066Sahrens 
585fa9e4066Sahrens 	/*
586fa9e4066Sahrens 	 * Generate a label describing the pool and our top-level vdev.
587fa9e4066Sahrens 	 * We mark it as being from txg 0 to indicate that it's not
588fa9e4066Sahrens 	 * really part of an active pool just yet.  The labels will
589fa9e4066Sahrens 	 * be written again with a meaningful txg by spa_sync().
590fa9e4066Sahrens 	 */
59139c23413Seschrock 	if (reason == VDEV_LABEL_SPARE ||
59239c23413Seschrock 	    (reason == VDEV_LABEL_REMOVE && vd->vdev_isspare)) {
59339c23413Seschrock 		/*
59439c23413Seschrock 		 * For inactive hot spares, we generate a special label that
59539c23413Seschrock 		 * identifies as a mutually shared hot spare.  We write the
59639c23413Seschrock 		 * label if we are adding a hot spare, or if we are removing an
59739c23413Seschrock 		 * active hot spare (in which case we want to revert the
59839c23413Seschrock 		 * labels).
59939c23413Seschrock 		 */
60099653d4eSeschrock 		VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0);
60199653d4eSeschrock 
60299653d4eSeschrock 		VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
60399653d4eSeschrock 		    spa_version(spa)) == 0);
60499653d4eSeschrock 		VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
60599653d4eSeschrock 		    POOL_STATE_SPARE) == 0);
60699653d4eSeschrock 		VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
60799653d4eSeschrock 		    vd->vdev_guid) == 0);
608fa94a07fSbrendan 	} else if (reason == VDEV_LABEL_L2CACHE ||
609fa94a07fSbrendan 	    (reason == VDEV_LABEL_REMOVE && vd->vdev_isl2cache)) {
610fa94a07fSbrendan 		/*
611fa94a07fSbrendan 		 * For level 2 ARC devices, add a special label.
612fa94a07fSbrendan 		 */
613fa94a07fSbrendan 		VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0);
614fa94a07fSbrendan 
615fa94a07fSbrendan 		VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
616fa94a07fSbrendan 		    spa_version(spa)) == 0);
617fa94a07fSbrendan 		VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
618fa94a07fSbrendan 		    POOL_STATE_L2CACHE) == 0);
619fa94a07fSbrendan 		VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
620fa94a07fSbrendan 		    vd->vdev_guid) == 0);
62199653d4eSeschrock 	} else {
62299653d4eSeschrock 		label = spa_config_generate(spa, vd, 0ULL, B_FALSE);
62399653d4eSeschrock 
62499653d4eSeschrock 		/*
62599653d4eSeschrock 		 * Add our creation time.  This allows us to detect multiple
62699653d4eSeschrock 		 * vdev uses as described above, and automatically expires if we
62799653d4eSeschrock 		 * fail.
62899653d4eSeschrock 		 */
62999653d4eSeschrock 		VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
63099653d4eSeschrock 		    crtxg) == 0);
63199653d4eSeschrock 	}
632fa9e4066Sahrens 
633fa9e4066Sahrens 	buf = vp->vp_nvlist;
634fa9e4066Sahrens 	buflen = sizeof (vp->vp_nvlist);
635fa9e4066Sahrens 
636a75573b6Smmusante 	error = nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP);
637a75573b6Smmusante 	if (error != 0) {
638fa9e4066Sahrens 		nvlist_free(label);
639fa9e4066Sahrens 		zio_buf_free(vp, sizeof (vdev_phys_t));
640a75573b6Smmusante 		/* EFAULT means nvlist_pack ran out of room */
641a75573b6Smmusante 		return (error == EFAULT ? ENAMETOOLONG : EINVAL);
642fa9e4066Sahrens 	}
643fa9e4066Sahrens 
644fa9e4066Sahrens 	/*
645fa9e4066Sahrens 	 * Initialize uberblock template.
646fa9e4066Sahrens 	 */
647f64c0e34SEric Taylor 	ub = zio_buf_alloc(VDEV_UBERBLOCK_RING);
648f64c0e34SEric Taylor 	bzero(ub, VDEV_UBERBLOCK_RING);
649ecc2d604Sbonwick 	*ub = spa->spa_uberblock;
650ecc2d604Sbonwick 	ub->ub_txg = 0;
651fa9e4066Sahrens 
652f83ffe1aSLin Ling 	/* Initialize the 2nd padding area. */
653f83ffe1aSLin Ling 	pad2 = zio_buf_alloc(VDEV_PAD_SIZE);
654f83ffe1aSLin Ling 	bzero(pad2, VDEV_PAD_SIZE);
655f83ffe1aSLin Ling 
656fa9e4066Sahrens 	/*
657fa9e4066Sahrens 	 * Write everything in parallel.
658fa9e4066Sahrens 	 */
6598956713aSEric Schrock retry:
66017f17c2dSbonwick 	zio = zio_root(spa, NULL, NULL, flags);
661fa9e4066Sahrens 
662e14bb325SJeff Bonwick 	for (int l = 0; l < VDEV_LABELS; l++) {
663fa9e4066Sahrens 
664fa9e4066Sahrens 		vdev_label_write(zio, vd, l, vp,
665fa9e4066Sahrens 		    offsetof(vdev_label_t, vl_vdev_phys),
66617f17c2dSbonwick 		    sizeof (vdev_phys_t), NULL, NULL, flags);
667fa9e4066Sahrens 
668f83ffe1aSLin Ling 		/*
669f83ffe1aSLin Ling 		 * Skip the 1st padding area.
670f83ffe1aSLin Ling 		 * Zero out the 2nd padding area where it might have
671f83ffe1aSLin Ling 		 * left over data from previous filesystem format.
672f83ffe1aSLin Ling 		 */
673f83ffe1aSLin Ling 		vdev_label_write(zio, vd, l, pad2,
674f83ffe1aSLin Ling 		    offsetof(vdev_label_t, vl_pad2),
675f83ffe1aSLin Ling 		    VDEV_PAD_SIZE, NULL, NULL, flags);
676f83ffe1aSLin Ling 
677f64c0e34SEric Taylor 		vdev_label_write(zio, vd, l, ub,
678f64c0e34SEric Taylor 		    offsetof(vdev_label_t, vl_uberblock),
679f64c0e34SEric Taylor 		    VDEV_UBERBLOCK_RING, NULL, NULL, flags);
680fa9e4066Sahrens 	}
681fa9e4066Sahrens 
682fa9e4066Sahrens 	error = zio_wait(zio);
683fa9e4066Sahrens 
6848956713aSEric Schrock 	if (error != 0 && !(flags & ZIO_FLAG_TRYHARD)) {
6858956713aSEric Schrock 		flags |= ZIO_FLAG_TRYHARD;
6868956713aSEric Schrock 		goto retry;
6878956713aSEric Schrock 	}
6888956713aSEric Schrock 
689fa9e4066Sahrens 	nvlist_free(label);
690f83ffe1aSLin Ling 	zio_buf_free(pad2, VDEV_PAD_SIZE);
691f64c0e34SEric Taylor 	zio_buf_free(ub, VDEV_UBERBLOCK_RING);
692fa9e4066Sahrens 	zio_buf_free(vp, sizeof (vdev_phys_t));
693fa9e4066Sahrens 
69439c23413Seschrock 	/*
69539c23413Seschrock 	 * If this vdev hasn't been previously identified as a spare, then we
6963d7072f8Seschrock 	 * mark it as such only if a) we are labeling it as a spare, or b) it
697fa94a07fSbrendan 	 * exists as a spare elsewhere in the system.  Do the same for
698fa94a07fSbrendan 	 * level 2 ARC devices.
69939c23413Seschrock 	 */
70039c23413Seschrock 	if (error == 0 && !vd->vdev_isspare &&
70139c23413Seschrock 	    (reason == VDEV_LABEL_SPARE ||
70289a89ebfSlling 	    spa_spare_exists(vd->vdev_guid, NULL, NULL)))
70339c23413Seschrock 		spa_spare_add(vd);
70499653d4eSeschrock 
705fa94a07fSbrendan 	if (error == 0 && !vd->vdev_isl2cache &&
706fa94a07fSbrendan 	    (reason == VDEV_LABEL_L2CACHE ||
707fa94a07fSbrendan 	    spa_l2cache_exists(vd->vdev_guid, NULL)))
708fa94a07fSbrendan 		spa_l2cache_add(vd);
709fa94a07fSbrendan 
71039c23413Seschrock 	return (error);
71199653d4eSeschrock }
71299653d4eSeschrock 
713fa9e4066Sahrens /*
714fa9e4066Sahrens  * ==========================================================================
715fa9e4066Sahrens  * uberblock load/sync
716fa9e4066Sahrens  * ==========================================================================
717fa9e4066Sahrens  */
718fa9e4066Sahrens 
7192e551927SVictor Latushkin /*
7202e551927SVictor Latushkin  * For use by zdb and debugging purposes only
7212e551927SVictor Latushkin  */
7222e551927SVictor Latushkin uint64_t ub_max_txg = UINT64_MAX;
7232e551927SVictor Latushkin 
724fa9e4066Sahrens /*
725fa9e4066Sahrens  * Consider the following situation: txg is safely synced to disk.  We've
726fa9e4066Sahrens  * written the first uberblock for txg + 1, and then we lose power.  When we
727fa9e4066Sahrens  * come back up, we fail to see the uberblock for txg + 1 because, say,
728fa9e4066Sahrens  * it was on a mirrored device and the replica to which we wrote txg + 1
729fa9e4066Sahrens  * is now offline.  If we then make some changes and sync txg + 1, and then
730fa9e4066Sahrens  * the missing replica comes back, then for a new seconds we'll have two
731fa9e4066Sahrens  * conflicting uberblocks on disk with the same txg.  The solution is simple:
732fa9e4066Sahrens  * among uberblocks with equal txg, choose the one with the latest timestamp.
733fa9e4066Sahrens  */
734fa9e4066Sahrens static int
735fa9e4066Sahrens vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2)
736fa9e4066Sahrens {
737fa9e4066Sahrens 	if (ub1->ub_txg < ub2->ub_txg)
738fa9e4066Sahrens 		return (-1);
739fa9e4066Sahrens 	if (ub1->ub_txg > ub2->ub_txg)
740fa9e4066Sahrens 		return (1);
741fa9e4066Sahrens 
742fa9e4066Sahrens 	if (ub1->ub_timestamp < ub2->ub_timestamp)
743fa9e4066Sahrens 		return (-1);
744fa9e4066Sahrens 	if (ub1->ub_timestamp > ub2->ub_timestamp)
745fa9e4066Sahrens 		return (1);
746fa9e4066Sahrens 
747fa9e4066Sahrens 	return (0);
748fa9e4066Sahrens }
749fa9e4066Sahrens 
750fa9e4066Sahrens static void
751fa9e4066Sahrens vdev_uberblock_load_done(zio_t *zio)
752fa9e4066Sahrens {
753e14bb325SJeff Bonwick 	zio_t *rio = zio->io_private;
754ecc2d604Sbonwick 	uberblock_t *ub = zio->io_data;
755e14bb325SJeff Bonwick 	uberblock_t *ubbest = rio->io_private;
756fa9e4066Sahrens 
757ecc2d604Sbonwick 	ASSERT3U(zio->io_size, ==, VDEV_UBERBLOCK_SIZE(zio->io_vd));
758fa9e4066Sahrens 
759ea8dc4b6Seschrock 	if (zio->io_error == 0 && uberblock_verify(ub) == 0) {
760e14bb325SJeff Bonwick 		mutex_enter(&rio->io_lock);
7612e551927SVictor Latushkin 		if (ub->ub_txg <= ub_max_txg &&
7622e551927SVictor Latushkin 		    vdev_uberblock_compare(ub, ubbest) > 0)
763fa9e4066Sahrens 			*ubbest = *ub;
764e14bb325SJeff Bonwick 		mutex_exit(&rio->io_lock);
765fa9e4066Sahrens 	}
766fa9e4066Sahrens 
767fa9e4066Sahrens 	zio_buf_free(zio->io_data, zio->io_size);
768fa9e4066Sahrens }
769fa9e4066Sahrens 
770fa9e4066Sahrens void
771fa9e4066Sahrens vdev_uberblock_load(zio_t *zio, vdev_t *vd, uberblock_t *ubbest)
772fa9e4066Sahrens {
773e14bb325SJeff Bonwick 	spa_t *spa = vd->vdev_spa;
774e14bb325SJeff Bonwick 	vdev_t *rvd = spa->spa_root_vdev;
7758956713aSEric Schrock 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
7768956713aSEric Schrock 	    ZIO_FLAG_SPECULATIVE | ZIO_FLAG_TRYHARD;
777e14bb325SJeff Bonwick 
778e14bb325SJeff Bonwick 	if (vd == rvd) {
779e14bb325SJeff Bonwick 		ASSERT(zio == NULL);
780e14bb325SJeff Bonwick 		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
781e14bb325SJeff Bonwick 		zio = zio_root(spa, NULL, ubbest, flags);
782e14bb325SJeff Bonwick 		bzero(ubbest, sizeof (uberblock_t));
783e14bb325SJeff Bonwick 	}
784fa9e4066Sahrens 
785e14bb325SJeff Bonwick 	ASSERT(zio != NULL);
786fa9e4066Sahrens 
787e14bb325SJeff Bonwick 	for (int c = 0; c < vd->vdev_children; c++)
788e14bb325SJeff Bonwick 		vdev_uberblock_load(zio, vd->vdev_child[c], ubbest);
789fa9e4066Sahrens 
790e14bb325SJeff Bonwick 	if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) {
791e14bb325SJeff Bonwick 		for (int l = 0; l < VDEV_LABELS; l++) {
792e14bb325SJeff Bonwick 			for (int n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
793e14bb325SJeff Bonwick 				vdev_label_read(zio, vd, l,
794e14bb325SJeff Bonwick 				    zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)),
795e14bb325SJeff Bonwick 				    VDEV_UBERBLOCK_OFFSET(vd, n),
796e14bb325SJeff Bonwick 				    VDEV_UBERBLOCK_SIZE(vd),
797e14bb325SJeff Bonwick 				    vdev_uberblock_load_done, zio, flags);
798e14bb325SJeff Bonwick 			}
799fa9e4066Sahrens 		}
800fa9e4066Sahrens 	}
801e14bb325SJeff Bonwick 
802e14bb325SJeff Bonwick 	if (vd == rvd) {
803e14bb325SJeff Bonwick 		(void) zio_wait(zio);
804e14bb325SJeff Bonwick 		spa_config_exit(spa, SCL_ALL, FTAG);
805e14bb325SJeff Bonwick 	}
806fa9e4066Sahrens }
807fa9e4066Sahrens 
808fa9e4066Sahrens /*
80917f17c2dSbonwick  * On success, increment root zio's count of good writes.
8100373e76bSbonwick  * We only get credit for writes to known-visible vdevs; see spa_vdev_add().
811fa9e4066Sahrens  */
812fa9e4066Sahrens static void
813fa9e4066Sahrens vdev_uberblock_sync_done(zio_t *zio)
814fa9e4066Sahrens {
81517f17c2dSbonwick 	uint64_t *good_writes = zio->io_private;
816fa9e4066Sahrens 
8170373e76bSbonwick 	if (zio->io_error == 0 && zio->io_vd->vdev_top->vdev_ms_array != 0)
818fa9e4066Sahrens 		atomic_add_64(good_writes, 1);
819fa9e4066Sahrens }
820fa9e4066Sahrens 
82117f17c2dSbonwick /*
82217f17c2dSbonwick  * Write the uberblock to all labels of all leaves of the specified vdev.
82317f17c2dSbonwick  */
824fa9e4066Sahrens static void
825e14bb325SJeff Bonwick vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, int flags)
826fa9e4066Sahrens {
82717f17c2dSbonwick 	uberblock_t *ubbuf;
828e14bb325SJeff Bonwick 	int n;
829fa9e4066Sahrens 
830e14bb325SJeff Bonwick 	for (int c = 0; c < vd->vdev_children; c++)
831e14bb325SJeff Bonwick 		vdev_uberblock_sync(zio, ub, vd->vdev_child[c], flags);
832fa9e4066Sahrens 
833fa9e4066Sahrens 	if (!vd->vdev_ops->vdev_op_leaf)
834fa9e4066Sahrens 		return;
835fa9e4066Sahrens 
836e14bb325SJeff Bonwick 	if (!vdev_writeable(vd))
837fa9e4066Sahrens 		return;
838fa9e4066Sahrens 
83917f17c2dSbonwick 	n = ub->ub_txg & (VDEV_UBERBLOCK_COUNT(vd) - 1);
840fa9e4066Sahrens 
84117f17c2dSbonwick 	ubbuf = zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd));
84217f17c2dSbonwick 	bzero(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
84317f17c2dSbonwick 	*ubbuf = *ub;
844fa9e4066Sahrens 
845e14bb325SJeff Bonwick 	for (int l = 0; l < VDEV_LABELS; l++)
84617f17c2dSbonwick 		vdev_label_write(zio, vd, l, ubbuf,
847e14bb325SJeff Bonwick 		    VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd),
84817f17c2dSbonwick 		    vdev_uberblock_sync_done, zio->io_private,
849e14bb325SJeff Bonwick 		    flags | ZIO_FLAG_DONT_PROPAGATE);
850fa9e4066Sahrens 
85117f17c2dSbonwick 	zio_buf_free(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
852fa9e4066Sahrens }
853fa9e4066Sahrens 
85417f17c2dSbonwick int
85517f17c2dSbonwick vdev_uberblock_sync_list(vdev_t **svd, int svdcount, uberblock_t *ub, int flags)
856fa9e4066Sahrens {
85717f17c2dSbonwick 	spa_t *spa = svd[0]->vdev_spa;
858e14bb325SJeff Bonwick 	zio_t *zio;
85917f17c2dSbonwick 	uint64_t good_writes = 0;
860fa9e4066Sahrens 
861e14bb325SJeff Bonwick 	zio = zio_root(spa, NULL, &good_writes, flags);
862e14bb325SJeff Bonwick 
863e14bb325SJeff Bonwick 	for (int v = 0; v < svdcount; v++)
864e14bb325SJeff Bonwick 		vdev_uberblock_sync(zio, ub, svd[v], flags);
865fa9e4066Sahrens 
86617f17c2dSbonwick 	(void) zio_wait(zio);
867fa9e4066Sahrens 
868fa9e4066Sahrens 	/*
86917f17c2dSbonwick 	 * Flush the uberblocks to disk.  This ensures that the odd labels
87017f17c2dSbonwick 	 * are no longer needed (because the new uberblocks and the even
87117f17c2dSbonwick 	 * labels are safely on disk), so it is safe to overwrite them.
872fa9e4066Sahrens 	 */
87317f17c2dSbonwick 	zio = zio_root(spa, NULL, NULL, flags);
874fa9e4066Sahrens 
875e14bb325SJeff Bonwick 	for (int v = 0; v < svdcount; v++)
87617f17c2dSbonwick 		zio_flush(zio, svd[v]);
877fa9e4066Sahrens 
87817f17c2dSbonwick 	(void) zio_wait(zio);
87917f17c2dSbonwick 
88017f17c2dSbonwick 	return (good_writes >= 1 ? 0 : EIO);
881fa9e4066Sahrens }
882fa9e4066Sahrens 
883fa9e4066Sahrens /*
88417f17c2dSbonwick  * On success, increment the count of good writes for our top-level vdev.
885fa9e4066Sahrens  */
886fa9e4066Sahrens static void
88717f17c2dSbonwick vdev_label_sync_done(zio_t *zio)
888fa9e4066Sahrens {
88917f17c2dSbonwick 	uint64_t *good_writes = zio->io_private;
890fa9e4066Sahrens 
891fa9e4066Sahrens 	if (zio->io_error == 0)
892fa9e4066Sahrens 		atomic_add_64(good_writes, 1);
893fa9e4066Sahrens }
894fa9e4066Sahrens 
89517f17c2dSbonwick /*
89617f17c2dSbonwick  * If there weren't enough good writes, indicate failure to the parent.
89717f17c2dSbonwick  */
898fa9e4066Sahrens static void
89917f17c2dSbonwick vdev_label_sync_top_done(zio_t *zio)
90017f17c2dSbonwick {
90117f17c2dSbonwick 	uint64_t *good_writes = zio->io_private;
90217f17c2dSbonwick 
90317f17c2dSbonwick 	if (*good_writes == 0)
90417f17c2dSbonwick 		zio->io_error = EIO;
90517f17c2dSbonwick 
90617f17c2dSbonwick 	kmem_free(good_writes, sizeof (uint64_t));
90717f17c2dSbonwick }
90817f17c2dSbonwick 
90951ece835Seschrock /*
9100430f8daSeschrock  * We ignore errors for log and cache devices, simply free the private data.
91151ece835Seschrock  */
91251ece835Seschrock static void
9130430f8daSeschrock vdev_label_sync_ignore_done(zio_t *zio)
91451ece835Seschrock {
91551ece835Seschrock 	kmem_free(zio->io_private, sizeof (uint64_t));
91651ece835Seschrock }
91751ece835Seschrock 
91817f17c2dSbonwick /*
91917f17c2dSbonwick  * Write all even or odd labels to all leaves of the specified vdev.
92017f17c2dSbonwick  */
92117f17c2dSbonwick static void
922e14bb325SJeff Bonwick vdev_label_sync(zio_t *zio, vdev_t *vd, int l, uint64_t txg, int flags)
923fa9e4066Sahrens {
924fa9e4066Sahrens 	nvlist_t *label;
925fa9e4066Sahrens 	vdev_phys_t *vp;
926fa9e4066Sahrens 	char *buf;
927fa9e4066Sahrens 	size_t buflen;
928fa9e4066Sahrens 
929e14bb325SJeff Bonwick 	for (int c = 0; c < vd->vdev_children; c++)
930e14bb325SJeff Bonwick 		vdev_label_sync(zio, vd->vdev_child[c], l, txg, flags);
931fa9e4066Sahrens 
932fa9e4066Sahrens 	if (!vd->vdev_ops->vdev_op_leaf)
933fa9e4066Sahrens 		return;
934fa9e4066Sahrens 
935e14bb325SJeff Bonwick 	if (!vdev_writeable(vd))
936fa9e4066Sahrens 		return;
937fa9e4066Sahrens 
938fa9e4066Sahrens 	/*
939fa9e4066Sahrens 	 * Generate a label describing the top-level config to which we belong.
940fa9e4066Sahrens 	 */
9410373e76bSbonwick 	label = spa_config_generate(vd->vdev_spa, vd, txg, B_FALSE);
942fa9e4066Sahrens 
943fa9e4066Sahrens 	vp = zio_buf_alloc(sizeof (vdev_phys_t));
944fa9e4066Sahrens 	bzero(vp, sizeof (vdev_phys_t));
945fa9e4066Sahrens 
946fa9e4066Sahrens 	buf = vp->vp_nvlist;
947fa9e4066Sahrens 	buflen = sizeof (vp->vp_nvlist);
948fa9e4066Sahrens 
94917f17c2dSbonwick 	if (nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP) == 0) {
95017f17c2dSbonwick 		for (; l < VDEV_LABELS; l += 2) {
95117f17c2dSbonwick 			vdev_label_write(zio, vd, l, vp,
95217f17c2dSbonwick 			    offsetof(vdev_label_t, vl_vdev_phys),
95317f17c2dSbonwick 			    sizeof (vdev_phys_t),
95417f17c2dSbonwick 			    vdev_label_sync_done, zio->io_private,
955e14bb325SJeff Bonwick 			    flags | ZIO_FLAG_DONT_PROPAGATE);
95617f17c2dSbonwick 		}
95717f17c2dSbonwick 	}
958fa9e4066Sahrens 
959fa9e4066Sahrens 	zio_buf_free(vp, sizeof (vdev_phys_t));
960fa9e4066Sahrens 	nvlist_free(label);
961fa9e4066Sahrens }
962fa9e4066Sahrens 
96317f17c2dSbonwick int
964e14bb325SJeff Bonwick vdev_label_sync_list(spa_t *spa, int l, uint64_t txg, int flags)
965fa9e4066Sahrens {
966e14bb325SJeff Bonwick 	list_t *dl = &spa->spa_config_dirty_list;
96717f17c2dSbonwick 	vdev_t *vd;
968e14bb325SJeff Bonwick 	zio_t *zio;
969fa9e4066Sahrens 	int error;
970fa9e4066Sahrens 
971fa9e4066Sahrens 	/*
972e14bb325SJeff Bonwick 	 * Write the new labels to disk.
973fa9e4066Sahrens 	 */
974e14bb325SJeff Bonwick 	zio = zio_root(spa, NULL, NULL, flags);
975fa9e4066Sahrens 
97617f17c2dSbonwick 	for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) {
97717f17c2dSbonwick 		uint64_t *good_writes = kmem_zalloc(sizeof (uint64_t),
97817f17c2dSbonwick 		    KM_SLEEP);
979a3f829aeSBill Moore 		zio_t *vio = zio_null(zio, spa, NULL,
9800430f8daSeschrock 		    (vd->vdev_islog || vd->vdev_aux != NULL) ?
9810430f8daSeschrock 		    vdev_label_sync_ignore_done : vdev_label_sync_top_done,
98217f17c2dSbonwick 		    good_writes, flags);
983e14bb325SJeff Bonwick 		vdev_label_sync(vio, vd, l, txg, flags);
98417f17c2dSbonwick 		zio_nowait(vio);
985fa9e4066Sahrens 	}
986e14bb325SJeff Bonwick 
987e14bb325SJeff Bonwick 	error = zio_wait(zio);
988fa9e4066Sahrens 
9898654d025Sperrin 	/*
99017f17c2dSbonwick 	 * Flush the new labels to disk.
9918654d025Sperrin 	 */
99217f17c2dSbonwick 	zio = zio_root(spa, NULL, NULL, flags);
9938654d025Sperrin 
99417f17c2dSbonwick 	for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd))
99517f17c2dSbonwick 		zio_flush(zio, vd);
99617f17c2dSbonwick 
99717f17c2dSbonwick 	(void) zio_wait(zio);
998fa9e4066Sahrens 
999fa9e4066Sahrens 	return (error);
1000fa9e4066Sahrens }
1001fa9e4066Sahrens 
1002fa9e4066Sahrens /*
100317f17c2dSbonwick  * Sync the uberblock and any changes to the vdev configuration.
1004fa9e4066Sahrens  *
1005fa9e4066Sahrens  * The order of operations is carefully crafted to ensure that
1006fa9e4066Sahrens  * if the system panics or loses power at any time, the state on disk
1007fa9e4066Sahrens  * is still transactionally consistent.  The in-line comments below
1008fa9e4066Sahrens  * describe the failure semantics at each stage.
1009fa9e4066Sahrens  *
101017f17c2dSbonwick  * Moreover, vdev_config_sync() is designed to be idempotent: if it fails
1011fa9e4066Sahrens  * at any time, you can just call it again, and it will resume its work.
1012fa9e4066Sahrens  */
1013e14bb325SJeff Bonwick int
10148956713aSEric Schrock vdev_config_sync(vdev_t **svd, int svdcount, uint64_t txg, boolean_t tryhard)
1015fa9e4066Sahrens {
101617f17c2dSbonwick 	spa_t *spa = svd[0]->vdev_spa;
1017fa9e4066Sahrens 	uberblock_t *ub = &spa->spa_uberblock;
10180373e76bSbonwick 	vdev_t *vd;
1019fa9e4066Sahrens 	zio_t *zio;
1020e14bb325SJeff Bonwick 	int error;
1021e14bb325SJeff Bonwick 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
1022fa9e4066Sahrens 
10238956713aSEric Schrock 	/*
10248956713aSEric Schrock 	 * Normally, we don't want to try too hard to write every label and
10258956713aSEric Schrock 	 * uberblock.  If there is a flaky disk, we don't want the rest of the
10268956713aSEric Schrock 	 * sync process to block while we retry.  But if we can't write a
10278956713aSEric Schrock 	 * single label out, we should retry with ZIO_FLAG_TRYHARD before
10288956713aSEric Schrock 	 * bailing out and declaring the pool faulted.
10298956713aSEric Schrock 	 */
10308956713aSEric Schrock 	if (tryhard)
10318956713aSEric Schrock 		flags |= ZIO_FLAG_TRYHARD;
10328956713aSEric Schrock 
1033fa9e4066Sahrens 	ASSERT(ub->ub_txg <= txg);
1034fa9e4066Sahrens 
1035fa9e4066Sahrens 	/*
103617f17c2dSbonwick 	 * If this isn't a resync due to I/O errors,
103717f17c2dSbonwick 	 * and nothing changed in this transaction group,
103817f17c2dSbonwick 	 * and the vdev configuration hasn't changed,
10390373e76bSbonwick 	 * then there's nothing to do.
1040fa9e4066Sahrens 	 */
104117f17c2dSbonwick 	if (ub->ub_txg < txg &&
104217f17c2dSbonwick 	    uberblock_update(ub, spa->spa_root_vdev, txg) == B_FALSE &&
1043e14bb325SJeff Bonwick 	    list_is_empty(&spa->spa_config_dirty_list))
1044e14bb325SJeff Bonwick 		return (0);
1045fa9e4066Sahrens 
1046fa9e4066Sahrens 	if (txg > spa_freeze_txg(spa))
1047e14bb325SJeff Bonwick 		return (0);
1048fa9e4066Sahrens 
10490373e76bSbonwick 	ASSERT(txg <= spa->spa_final_txg);
10500373e76bSbonwick 
1051fa9e4066Sahrens 	/*
1052fa9e4066Sahrens 	 * Flush the write cache of every disk that's been written to
1053fa9e4066Sahrens 	 * in this transaction group.  This ensures that all blocks
1054fa9e4066Sahrens 	 * written in this txg will be committed to stable storage
1055fa9e4066Sahrens 	 * before any uberblock that references them.
1056fa9e4066Sahrens 	 */
105717f17c2dSbonwick 	zio = zio_root(spa, NULL, NULL, flags);
105817f17c2dSbonwick 
1059fa9e4066Sahrens 	for (vd = txg_list_head(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)); vd;
106017f17c2dSbonwick 	    vd = txg_list_next(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg)))
106117f17c2dSbonwick 		zio_flush(zio, vd);
106217f17c2dSbonwick 
1063fa9e4066Sahrens 	(void) zio_wait(zio);
1064fa9e4066Sahrens 
1065fa9e4066Sahrens 	/*
1066fa9e4066Sahrens 	 * Sync out the even labels (L0, L2) for every dirty vdev.  If the
1067fa9e4066Sahrens 	 * system dies in the middle of this process, that's OK: all of the
1068fa9e4066Sahrens 	 * even labels that made it to disk will be newer than any uberblock,
1069fa9e4066Sahrens 	 * and will therefore be considered invalid.  The odd labels (L1, L3),
107017f17c2dSbonwick 	 * which have not yet been touched, will still be valid.  We flush
107117f17c2dSbonwick 	 * the new labels to disk to ensure that all even-label updates
107217f17c2dSbonwick 	 * are committed to stable storage before the uberblock update.
1073fa9e4066Sahrens 	 */
1074e14bb325SJeff Bonwick 	if ((error = vdev_label_sync_list(spa, 0, txg, flags)) != 0)
1075e14bb325SJeff Bonwick 		return (error);
1076fa9e4066Sahrens 
1077fa9e4066Sahrens 	/*
1078e14bb325SJeff Bonwick 	 * Sync the uberblocks to all vdevs in svd[].
10790373e76bSbonwick 	 * If the system dies in the middle of this step, there are two cases
10800373e76bSbonwick 	 * to consider, and the on-disk state is consistent either way:
1081fa9e4066Sahrens 	 *
1082fa9e4066Sahrens 	 * (1)	If none of the new uberblocks made it to disk, then the
1083fa9e4066Sahrens 	 *	previous uberblock will be the newest, and the odd labels
1084fa9e4066Sahrens 	 *	(which had not yet been touched) will be valid with respect
1085fa9e4066Sahrens 	 *	to that uberblock.
1086fa9e4066Sahrens 	 *
1087fa9e4066Sahrens 	 * (2)	If one or more new uberblocks made it to disk, then they
1088fa9e4066Sahrens 	 *	will be the newest, and the even labels (which had all
1089fa9e4066Sahrens 	 *	been successfully committed) will be valid with respect
1090fa9e4066Sahrens 	 *	to the new uberblocks.
1091fa9e4066Sahrens 	 */
1092e14bb325SJeff Bonwick 	if ((error = vdev_uberblock_sync_list(svd, svdcount, ub, flags)) != 0)
1093e14bb325SJeff Bonwick 		return (error);
1094fa9e4066Sahrens 
1095fa9e4066Sahrens 	/*
1096fa9e4066Sahrens 	 * Sync out odd labels for every dirty vdev.  If the system dies
1097fa9e4066Sahrens 	 * in the middle of this process, the even labels and the new
1098fa9e4066Sahrens 	 * uberblocks will suffice to open the pool.  The next time
1099fa9e4066Sahrens 	 * the pool is opened, the first thing we'll do -- before any
1100fa9e4066Sahrens 	 * user data is modified -- is mark every vdev dirty so that
110117f17c2dSbonwick 	 * all labels will be brought up to date.  We flush the new labels
110217f17c2dSbonwick 	 * to disk to ensure that all odd-label updates are committed to
110317f17c2dSbonwick 	 * stable storage before the next transaction group begins.
1104fa9e4066Sahrens 	 */
1105e14bb325SJeff Bonwick 	return (vdev_label_sync_list(spa, 1, txg, flags));
1106fa9e4066Sahrens }
1107