/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* Virtual Device Labels
* ---------------------
*
* The vdev label serves several distinct purposes:
*
* 1. Uniquely identify this device as part of a ZFS pool and confirm its
* identity within the pool.
*
* 2. Verify that all the devices given in a configuration are present
* within the pool.
*
* 3. Determine the uberblock for the pool.
*
* 4. In case of an import operation, determine the configuration of the
* toplevel vdev of which it is a part.
*
* 5. If an import operation cannot find all the devices in the pool,
* provide enough information to the administrator to determine which
* devices are missing.
*
* It is important to note that while the kernel is responsible for writing the
* label, it only consumes the information in the first three cases. The
* latter information is only consumed in userland when determining the
* configuration to import a pool.
*
*
* Label Organization
* ------------------
*
* Before describing the contents of the label, it's important to understand how
* the labels are written and updated with respect to the uberblock.
*
* When the pool configuration is altered, either because it was newly created
* or a device was added, we want to update all the labels such that we can deal
* with fatal failure at any point. To this end, each disk has two labels which
* are updated before and after the uberblock is synced. Assuming we have
* labels and an uberblock with the following transacation groups:
*
* L1 UB L2
* +------+ +------+ +------+
* | | | | | |
* | t10 | | t10 | | t10 |
* | | | | | |
* +------+ +------+ +------+
*
* In this stable state, the labels and the uberblock were all updated within
* the same transaction group (10). Each label is mirrored and checksummed, so
* that we can detect when we fail partway through writing the label.
*
* In order to identify which labels are valid, the labels are written in the
* following manner:
*
* 1. For each vdev, update 'L1' to the new label
* 2. Update the uberblock
* 3. For each vdev, update 'L2' to the new label
*
* Given arbitrary failure, we can determine the correct label to use based on
* the transaction group. If we fail after updating L1 but before updating the
* UB, we will notice that L1's transaction group is greater than the uberblock,
* so L2 must be valid. If we fail after writing the uberblock but before
* writing L2, we will notice that L2's transaction group is less than L1, and
* therefore L1 is valid.
*
* Another added complexity is that not every label is updated when the config
* is synced. If we add a single device, we do not want to have to re-write
* every label for every device in the pool. This means that both L1 and L2 may
* be older than the pool uberblock, because the necessary information is stored
* on another vdev.
*
*
* On-disk Format
* --------------
*
* The vdev label consists of two distinct parts, and is wrapped within the
* vdev_label_t structure. The label includes 8k of padding to permit legacy
* VTOC disk labels, but is otherwise ignored.
*
* The first half of the label is a packed nvlist which contains pool wide
* properties, per-vdev properties, and configuration information. It is
* described in more detail below.
*
* The latter half of the label consists of a redundant array of uberblocks.
* These uberblocks are updated whenever a transaction group is committed,
* or when the configuration is updated. When a pool is loaded, we scan each
* vdev for the 'best' uberblock.
*
*
* Configuration Information
* -------------------------
*
* The nvlist describing the pool and vdev contains the following elements:
*
* version ZFS on-disk version
* name Pool name
* state Pool state
* txg Transaction group in which this label was written
* pool_guid Unique identifier for this pool
* vdev_tree An nvlist describing vdev tree.
*
* Each leaf device label also contains the following:
*
* top_guid Unique ID for top-level vdev in which this is contained
* guid Unique ID for the leaf vdev
*
* The 'vs' configuration follows the format described in 'spa_config.c'.
*/
#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/spa_impl.h>
#include <sys/dmu.h>
#include <sys/zap.h>
#include <sys/vdev.h>
#include <sys/vdev_impl.h>
#include <sys/uberblock_impl.h>
#include <sys/metaslab.h>
#include <sys/zio.h>
#include <sys/fs/zfs.h>
/*
* Basic routines to read and write from a vdev label.
* Used throughout the rest of this file.
*/
uint64_t
vdev_label_offset(uint64_t psize, int l, uint64_t offset)
{
return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ?
0 : psize - VDEV_LABELS * sizeof (vdev_label_t)));
}
static void
vdev_label_read(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
uint64_t size, zio_done_func_t *done, void *private)
{
ASSERT(vd->vdev_children == 0);
zio_nowait(zio_read_phys(zio, vd,
vdev_label_offset(vd->vdev_psize, l, offset),
size, buf, ZIO_CHECKSUM_LABEL, done, private,
ZIO_PRIORITY_SYNC_READ, ZIO_FLAG_SPECULATIVE |
ZIO_FLAG_CANFAIL | ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_DONT_RETRY));
}
static void
vdev_label_write(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
uint64_t size, zio_done_func_t *done, void *private)
{
ASSERT(vd->vdev_children == 0);
zio_nowait(zio_write_phys(zio, vd,
vdev_label_offset(vd->vdev_psize, l, offset),
size, buf, ZIO_CHECKSUM_LABEL, done, private,
ZIO_PRIORITY_SYNC_WRITE,
ZIO_FLAG_CANFAIL | ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_DONT_RETRY));
}
/*
* Generate the nvlist representing this vdev's config.
*/
nvlist_t *
vdev_config_generate(vdev_t *vd, int getstats)
{
nvlist_t *nv = NULL;
VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, 0) == 0);
VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_TYPE,
vd->vdev_ops->vdev_op_type) == 0);
VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ID, vd->vdev_id) == 0);
VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_GUID, vd->vdev_guid) == 0);
if (vd->vdev_path != NULL)
VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PATH,
vd->vdev_path) == 0);
if (vd->vdev_devid != NULL)
VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_DEVID,
vd->vdev_devid) == 0);
if (vd->vdev_wholedisk != -1ULL)
VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
vd->vdev_wholedisk) == 0);
if (vd == vd->vdev_top) {
VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
vd->vdev_ms_array) == 0);
VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT,
vd->vdev_ms_shift) == 0);
VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASHIFT,
vd->vdev_ashift) == 0);
VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASIZE,
vd->vdev_asize) == 0);
}
if (vd->vdev_dtl.smo_object != 0)
VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DTL,
vd->vdev_dtl.smo_object) == 0);
if (getstats) {
vdev_stat_t vs;
vdev_get_stats(vd, &vs);
VERIFY(nvlist_add_uint64_array(nv, ZPOOL_CONFIG_STATS,
(uint64_t *)&vs, sizeof (vs) / sizeof (uint64_t)) == 0);
}
if (!vd->vdev_ops->vdev_op_leaf) {
nvlist_t **child;
int c;
child = kmem_alloc(vd->vdev_children * sizeof (nvlist_t *),
KM_SLEEP);
for (c = 0; c < vd->vdev_children; c++)
child[c] = vdev_config_generate(vd->vdev_child[c],
getstats);
VERIFY(nvlist_add_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
child, vd->vdev_children) == 0);
for (c = 0; c < vd->vdev_children; c++)
nvlist_free(child[c]);
kmem_free(child, vd->vdev_children * sizeof (nvlist_t *));
} else {
if (!vd->vdev_tmpoffline) {
if (vd->vdev_offline)
VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_OFFLINE,
B_TRUE) == 0);
else
(void) nvlist_remove(nv, ZPOOL_CONFIG_OFFLINE,
DATA_TYPE_UINT64);
}
}
return (nv);
}
nvlist_t *
vdev_label_read_config(vdev_t *vd)
{
nvlist_t *config = NULL;
vdev_phys_t *vp;
uint64_t version;
zio_t *zio;
int l;
if (vdev_is_dead(vd))
return (NULL);
vp = zio_buf_alloc(sizeof (vdev_phys_t));
for (l = 0; l < VDEV_LABELS; l++) {
zio = zio_root(vd->vdev_spa, NULL, NULL,
ZIO_FLAG_CANFAIL | ZIO_FLAG_CONFIG_HELD);
vdev_label_read(zio, vd, l, vp,
offsetof(vdev_label_t, vl_vdev_phys),
sizeof (vdev_phys_t), NULL, NULL);
if (zio_wait(zio) == 0 &&
nvlist_unpack(vp->vp_nvlist, sizeof (vp->vp_nvlist),
&config, 0) == 0 &&
nvlist_lookup_uint64(config, ZPOOL_CONFIG_VERSION,
&version) == 0 &&
version == UBERBLOCK_VERSION)
break;
if (config != NULL) {
nvlist_free(config);
config = NULL;
}
}
zio_buf_free(vp, sizeof (vdev_phys_t));
return (config);
}
int
vdev_label_init(vdev_t *vd, uint64_t crtxg)
{
spa_t *spa = vd->vdev_spa;
nvlist_t *label;
vdev_phys_t *vp;
vdev_boot_header_t *vb;
uberblock_phys_t *ubphys;
zio_t *zio;
int l, c, n;
char *buf;
size_t buflen;
int error;
for (c = 0; c < vd->vdev_children; c++)
if ((error = vdev_label_init(vd->vdev_child[c], crtxg)) != 0)
return (error);
if (!vd->vdev_ops->vdev_op_leaf)
return (0);
/*
* Make sure each leaf device is writable, and zero its initial content.
* Along the way, also make sure that no leaf is already in use.
* Note that it's important to do this sequentially, not in parallel,
* so that we catch cases of multiple use of the same leaf vdev in
* the vdev we're creating -- e.g. mirroring a disk with itself.
*/
if (vdev_is_dead(vd))
return (EIO);
/*
* Check whether this device is already in use.
* Ignore the check if crtxg == 0, which we use for device removal.
*/
if (crtxg != 0 && (label = vdev_label_read_config(vd)) != NULL) {
uint64_t version, state, pool_guid, device_guid, txg;
uint64_t mycrtxg = 0;
(void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
&mycrtxg);
if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_VERSION,
&version) == 0 && version == UBERBLOCK_VERSION &&
nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
&state) == 0 && state == POOL_STATE_ACTIVE &&
nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID,
&pool_guid) == 0 &&
nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID,
&device_guid) == 0 &&
spa_guid_exists(pool_guid, device_guid) &&
nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG,
&txg) == 0 && (txg != 0 || mycrtxg == crtxg)) {
dprintf("vdev %s in use, pool_state %d\n",
vdev_description(vd), state);
nvlist_free(label);
return (EBUSY);
}
nvlist_free(label);
}
/*
* The device isn't in use, so initialize its label.
*/
vp = zio_buf_alloc(sizeof (vdev_phys_t));
bzero(vp, sizeof (vdev_phys_t));
/*
* Generate a label describing the pool and our top-level vdev.
* We mark it as being from txg 0 to indicate that it's not
* really part of an active pool just yet. The labels will
* be written again with a meaningful txg by spa_sync().
*/
label = spa_config_generate(spa, vd, 0ULL, 0);
/*
* Add our creation time. This allows us to detect multiple vdev
* uses as described above, and automatically expires if we fail.
*/
VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_CREATE_TXG, crtxg) == 0);
buf = vp->vp_nvlist;
buflen = sizeof (vp->vp_nvlist);
if (nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, 0) != 0) {
nvlist_free(label);
zio_buf_free(vp, sizeof (vdev_phys_t));
return (EINVAL);
}
/*
* Initialize boot block header.
*/
vb = zio_buf_alloc(sizeof (vdev_boot_header_t));
bzero(vb, sizeof (vdev_boot_header_t));
vb->vb_magic = VDEV_BOOT_MAGIC;
vb->vb_version = VDEV_BOOT_VERSION;
vb->vb_offset = VDEV_BOOT_OFFSET;
vb->vb_size = VDEV_BOOT_SIZE;
/*
* Initialize uberblock template.
*/
ubphys = zio_buf_alloc(sizeof (uberblock_phys_t));
bzero(ubphys, sizeof (uberblock_phys_t));
ubphys->ubp_uberblock = spa->spa_uberblock;
ubphys->ubp_uberblock.ub_txg = 0;
/*
* Write everything in parallel.
*/
zio = zio_root(spa, NULL, NULL,
ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL);
for (l = 0; l < VDEV_LABELS; l++) {
vdev_label_write(zio, vd, l, vp,
offsetof(vdev_label_t, vl_vdev_phys),
sizeof (vdev_phys_t), NULL, NULL);
vdev_label_write(zio, vd, l, vb,
offsetof(vdev_label_t, vl_boot_header),
sizeof (vdev_boot_header_t), NULL, NULL);
for (n = 0; n < VDEV_UBERBLOCKS; n++) {
vdev_label_write(zio, vd, l, ubphys,
offsetof(vdev_label_t, vl_uberblock[n]),
sizeof (uberblock_phys_t), NULL, NULL);
}
}
error = zio_wait(zio);
nvlist_free(label);
zio_buf_free(ubphys, sizeof (uberblock_phys_t));
zio_buf_free(vb, sizeof (vdev_boot_header_t));
zio_buf_free(vp, sizeof (vdev_phys_t));
return (error);
}
/*
* ==========================================================================
* uberblock load/sync
* ==========================================================================
*/
/*
* Consider the following situation: txg is safely synced to disk. We've
* written the first uberblock for txg + 1, and then we lose power. When we
* come back up, we fail to see the uberblock for txg + 1 because, say,
* it was on a mirrored device and the replica to which we wrote txg + 1
* is now offline. If we then make some changes and sync txg + 1, and then
* the missing replica comes back, then for a new seconds we'll have two
* conflicting uberblocks on disk with the same txg. The solution is simple:
* among uberblocks with equal txg, choose the one with the latest timestamp.
*/
static int
vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2)
{
if (ub1->ub_txg < ub2->ub_txg)
return (-1);
if (ub1->ub_txg > ub2->ub_txg)
return (1);
if (ub1->ub_timestamp < ub2->ub_timestamp)
return (-1);
if (ub1->ub_timestamp > ub2->ub_timestamp)
return (1);
return (0);
}
static void
vdev_uberblock_load_done(zio_t *zio)
{
uberblock_phys_t *ubphys = zio->io_data;
uberblock_t *ub = &ubphys->ubp_uberblock;
uberblock_t *ubbest = zio->io_private;
spa_t *spa = zio->io_spa;
ASSERT3U(zio->io_size, ==, sizeof (uberblock_phys_t));
if (uberblock_verify(ub) == 0) {
mutex_enter(&spa->spa_uberblock_lock);
if (vdev_uberblock_compare(ub, ubbest) > 0)
*ubbest = *ub;
mutex_exit(&spa->spa_uberblock_lock);
}
zio_buf_free(zio->io_data, zio->io_size);
}
void
vdev_uberblock_load(zio_t *zio, vdev_t *vd, uberblock_t *ubbest)
{
int l, c, n;
for (c = 0; c < vd->vdev_children; c++)
vdev_uberblock_load(zio, vd->vdev_child[c], ubbest);
if (!vd->vdev_ops->vdev_op_leaf)
return;
if (vdev_is_dead(vd))
return;
for (l = 0; l < VDEV_LABELS; l++) {
for (n = 0; n < VDEV_UBERBLOCKS; n++) {
vdev_label_read(zio, vd, l,
zio_buf_alloc(sizeof (uberblock_phys_t)),
offsetof(vdev_label_t, vl_uberblock[n]),
sizeof (uberblock_phys_t),
vdev_uberblock_load_done, ubbest);
}
}
}
/*
* Write the uberblock to both labels of all leaves of the specified vdev.
*/
static void
vdev_uberblock_sync_done(zio_t *zio)
{
uint64_t *good_writes = zio->io_root->io_private;
if (zio->io_error == 0)
atomic_add_64(good_writes, 1);
}
static void
vdev_uberblock_sync(zio_t *zio, uberblock_phys_t *ubphys, vdev_t *vd,
uint64_t txg)
{
int l, c, n;
for (c = 0; c < vd->vdev_children; c++)
vdev_uberblock_sync(zio, ubphys, vd->vdev_child[c], txg);
if (!vd->vdev_ops->vdev_op_leaf)
return;
if (vdev_is_dead(vd))
return;
n = txg & (VDEV_UBERBLOCKS - 1);
ASSERT(ubphys->ubp_uberblock.ub_txg == txg);
for (l = 0; l < VDEV_LABELS; l++)
vdev_label_write(zio, vd, l, ubphys,
offsetof(vdev_label_t, vl_uberblock[n]),
sizeof (uberblock_phys_t), vdev_uberblock_sync_done, NULL);
dprintf("vdev %s in txg %llu\n", vdev_description(vd), txg);
}
static int
vdev_uberblock_sync_tree(spa_t *spa, uberblock_t *ub, vdev_t *uvd, uint64_t txg)
{
uberblock_phys_t *ubphys;
uint64_t *good_writes;
zio_t *zio;
int error;
ubphys = zio_buf_alloc(sizeof (uberblock_phys_t));
bzero(ubphys, sizeof (uberblock_phys_t));
ubphys->ubp_uberblock = *ub;
good_writes = kmem_zalloc(sizeof (uint64_t), KM_SLEEP);
zio = zio_root(spa, NULL, good_writes,
ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL);
vdev_uberblock_sync(zio, ubphys, uvd, txg);
error = zio_wait(zio);
if (error && *good_writes != 0) {
dprintf("partial success: good_writes = %llu\n", *good_writes);
error = 0;
}
/*
* It's possible to have no good writes and no error if every vdev is in
* the CANT_OPEN state.
*/
if (*good_writes == 0 && error == 0)
error = EIO;
kmem_free(good_writes, sizeof (uint64_t));
zio_buf_free(ubphys, sizeof (uberblock_phys_t));
return (error);
}
/*
* Sync out an individual vdev.
*/
static void
vdev_sync_label_done(zio_t *zio)
{
uint64_t *good_writes = zio->io_root->io_private;
if (zio->io_error == 0)
atomic_add_64(good_writes, 1);
}
static void
vdev_sync_label(zio_t *zio, vdev_t *vd, int l, uint64_t txg)
{
nvlist_t *label;
vdev_phys_t *vp;
char *buf;
size_t buflen;
int c;
for (c = 0; c < vd->vdev_children; c++)
vdev_sync_label(zio, vd->vdev_child[c], l, txg);
if (!vd->vdev_ops->vdev_op_leaf)
return;
if (vdev_is_dead(vd))
return;
/*
* Generate a label describing the top-level config to which we belong.
*/
label = spa_config_generate(vd->vdev_spa, vd, txg, 0);
vp = zio_buf_alloc(sizeof (vdev_phys_t));
bzero(vp, sizeof (vdev_phys_t));
buf = vp->vp_nvlist;
buflen = sizeof (vp->vp_nvlist);
if (nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, 0) == 0)
vdev_label_write(zio, vd, l, vp,
offsetof(vdev_label_t, vl_vdev_phys), sizeof (vdev_phys_t),
vdev_sync_label_done, NULL);
zio_buf_free(vp, sizeof (vdev_phys_t));
nvlist_free(label);
dprintf("%s label %d txg %llu\n", vdev_description(vd), l, txg);
}
static int
vdev_sync_labels(vdev_t *vd, int l, uint64_t txg)
{
uint64_t *good_writes;
zio_t *zio;
int error;
ASSERT(vd == vd->vdev_top);
good_writes = kmem_zalloc(sizeof (uint64_t), KM_SLEEP);
zio = zio_root(vd->vdev_spa, NULL, good_writes,
ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL);
/*
* Recursively kick off writes to all labels.
*/
vdev_sync_label(zio, vd, l, txg);
error = zio_wait(zio);
if (error && *good_writes != 0) {
dprintf("partial success: good_writes = %llu\n", *good_writes);
error = 0;
}
if (*good_writes == 0 && error == 0)
error = ENODEV;
kmem_free(good_writes, sizeof (uint64_t));
return (error);
}
/*
* Sync the entire vdev configuration.
*
* The order of operations is carefully crafted to ensure that
* if the system panics or loses power at any time, the state on disk
* is still transactionally consistent. The in-line comments below
* describe the failure semantics at each stage.
*
* Moreover, it is designed to be idempotent: if spa_sync_labels() fails
* at any time, you can just call it again, and it will resume its work.
*/
int
spa_sync_labels(spa_t *spa, uint64_t txg)
{
uberblock_t *ub = &spa->spa_uberblock;
vdev_t *rvd = spa->spa_root_vdev;
vdev_t *vd, *uvd;
zio_t *zio;
int c, l, error;
ASSERT(ub->ub_txg <= txg);
/*
* If this isn't a resync due to I/O errors, and nothing changed
* in this transaction group, and the vdev configuration hasn't changed,
* and this isn't an explicit sync-all, then there's nothing to do.
*/
if (ub->ub_txg < txg && uberblock_update(ub, rvd, txg) == B_FALSE &&
list_is_empty(&spa->spa_dirty_list)) {
dprintf("nothing to sync in %s in txg %llu\n",
spa_name(spa), txg);
return (0);
}
if (txg > spa_freeze_txg(spa))
return (0);
dprintf("syncing %s txg %llu\n", spa_name(spa), txg);
/*
* Flush the write cache of every disk that's been written to
* in this transaction group. This ensures that all blocks
* written in this txg will be committed to stable storage
* before any uberblock that references them.
*/
zio = zio_root(spa, NULL, NULL,
ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL);
for (vd = txg_list_head(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)); vd;
vd = txg_list_next(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg))) {
zio_nowait(zio_ioctl(zio, spa, vd, DKIOCFLUSHWRITECACHE,
NULL, NULL, ZIO_PRIORITY_NOW,
ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_RETRY));
}
(void) zio_wait(zio);
/*
* Sync out the even labels (L0, L2) for every dirty vdev. If the
* system dies in the middle of this process, that's OK: all of the
* even labels that made it to disk will be newer than any uberblock,
* and will therefore be considered invalid. The odd labels (L1, L3),
* which have not yet been touched, will still be valid.
*/
for (vd = list_head(&spa->spa_dirty_list); vd != NULL;
vd = list_next(&spa->spa_dirty_list, vd)) {
for (l = 0; l < VDEV_LABELS; l++) {
if (l & 1)
continue;
if ((error = vdev_sync_labels(vd, l, txg)) != 0)
return (error);
}
}
/*
* Flush the new labels to disk. This ensures that all even-label
* updates are committed to stable storage before the uberblock update.
*/
zio = zio_root(spa, NULL, NULL,
ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL);
for (vd = list_head(&spa->spa_dirty_list); vd != NULL;
vd = list_next(&spa->spa_dirty_list, vd)) {
zio_nowait(zio_ioctl(zio, spa, vd, DKIOCFLUSHWRITECACHE,
NULL, NULL, ZIO_PRIORITY_NOW,
ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_RETRY));
}
(void) zio_wait(zio);
/*
* If there are any dirty vdevs, sync the uberblock to all vdevs.
* Otherwise, pick one top-level vdev at random.
*/
if (!list_is_empty(&spa->spa_dirty_list))
uvd = rvd;
else
uvd = rvd->vdev_child[spa_get_random(rvd->vdev_children)];
/*
* Sync the uberblocks. If the system dies in the middle of this
* step, there are two cases to consider, and the on-disk state
* is consistent either way:
*
* (1) If none of the new uberblocks made it to disk, then the
* previous uberblock will be the newest, and the odd labels
* (which had not yet been touched) will be valid with respect
* to that uberblock.
*
* (2) If one or more new uberblocks made it to disk, then they
* will be the newest, and the even labels (which had all
* been successfully committed) will be valid with respect
* to the new uberblocks.
*/
if ((error = vdev_uberblock_sync_tree(spa, ub, uvd, txg)) != 0)
return (error);
/*
* Flush the uberblocks to disk. This ensures that the odd labels
* are no longer needed (because the new uberblocks and the even
* labels are safely on disk), so it is safe to overwrite them.
*/
(void) zio_wait(zio_ioctl(NULL, spa, uvd, DKIOCFLUSHWRITECACHE,
NULL, NULL, ZIO_PRIORITY_NOW,
ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_RETRY));
/*
* Sync out odd labels for every dirty vdev. If the system dies
* in the middle of this process, the even labels and the new
* uberblocks will suffice to open the pool. The next time
* the pool is opened, the first thing we'll do -- before any
* user data is modified -- is mark every vdev dirty so that
* all labels will be brought up to date.
*/
for (vd = list_head(&spa->spa_dirty_list); vd != NULL;
vd = list_next(&spa->spa_dirty_list, vd)) {
for (l = 0; l < VDEV_LABELS; l++) {
if ((l & 1) == 0)
continue;
if ((error = vdev_sync_labels(vd, l, txg)) != 0)
return (error);
}
}
/*
* Flush the new labels to disk. This ensures that all odd-label
* updates are committed to stable storage before the next
* transaction group begins.
*/
zio = zio_root(spa, NULL, NULL,
ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL);
for (vd = list_head(&spa->spa_dirty_list); vd != NULL;
vd = list_next(&spa->spa_dirty_list, vd)) {
zio_nowait(zio_ioctl(zio, spa, vd, DKIOCFLUSHWRITECACHE,
NULL, NULL, ZIO_PRIORITY_NOW,
ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_RETRY));
}
(void) zio_wait(zio);
/*
* Clear the dirty list.
*/
while (!list_is_empty(&spa->spa_dirty_list))
vdev_config_clean(list_head(&spa->spa_dirty_list));
#ifdef DEBUG
for (c = 0; c < rvd->vdev_children; c++) {
ASSERT(rvd->vdev_child[c]->vdev_is_dirty == 0);
}
#endif
return (0);
}