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Diffstat (limited to 'sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_label.c')
| -rw-r--r-- | sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_label.c | 1011 |
1 files changed, 1011 insertions, 0 deletions
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_label.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_label.c new file mode 100644 index 000000000000..9d9f5556fa08 --- /dev/null +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_label.c @@ -0,0 +1,1011 @@ +/* + * 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 2007 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) +{ + ASSERT(offset < sizeof (vdev_label_t)); + + 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_CONFIG_HELD | ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE)); +} + +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_CONFIG_HELD | ZIO_FLAG_CANFAIL)); +} + +/* + * Generate the nvlist representing this vdev's config. + */ +nvlist_t * +vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats, + boolean_t isspare) +{ + nvlist_t *nv = NULL; + + VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0); + + VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_TYPE, + vd->vdev_ops->vdev_op_type) == 0); + if (!isspare) + 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_nparity != 0) { + ASSERT(strcmp(vd->vdev_ops->vdev_op_type, + VDEV_TYPE_RAIDZ) == 0); + + /* + * Make sure someone hasn't managed to sneak a fancy new vdev + * into a crufty old storage pool. + */ + ASSERT(vd->vdev_nparity == 1 || + (vd->vdev_nparity == 2 && + spa_version(spa) >= ZFS_VERSION_RAID6)); + + /* + * Note that we'll add the nparity tag even on storage pools + * that only support a single parity device -- older software + * will just ignore it. + */ + VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY, + vd->vdev_nparity) == 0); + } + + if (vd->vdev_wholedisk != -1ULL) + VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK, + vd->vdev_wholedisk) == 0); + + if (vd->vdev_not_present) + VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT, 1) == 0); + + if (vd->vdev_isspare) + VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_SPARE, 1) == 0); + + if (!isspare && 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(spa, vd->vdev_child[c], + getstats, isspare); + + 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_offline && !vd->vdev_tmpoffline) + 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) +{ + spa_t *spa = vd->vdev_spa; + nvlist_t *config = NULL; + vdev_phys_t *vp; + zio_t *zio; + int l; + + ASSERT(spa_config_held(spa, RW_READER)); + + 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(spa, NULL, NULL, ZIO_FLAG_CANFAIL | + ZIO_FLAG_SPECULATIVE | 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) + break; + + if (config != NULL) { + nvlist_free(config); + config = NULL; + } + } + + zio_buf_free(vp, sizeof (vdev_phys_t)); + + return (config); +} + +/* + * Determine if a device is in use. The 'spare_guid' parameter will be filled + * in with the device guid if this spare is active elsewhere on the system. + */ +static boolean_t +vdev_inuse(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason, + uint64_t *spare_guid) +{ + spa_t *spa = vd->vdev_spa; + uint64_t state, pool_guid, device_guid, txg, spare_pool; + uint64_t vdtxg = 0; + nvlist_t *label; + + if (spare_guid) + *spare_guid = 0ULL; + + /* + * Read the label, if any, and perform some basic sanity checks. + */ + if ((label = vdev_label_read_config(vd)) == NULL) + return (B_FALSE); + + (void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG, + &vdtxg); + + if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE, + &state) != 0 || + nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID, + &device_guid) != 0) { + nvlist_free(label); + return (B_FALSE); + } + + if (state != POOL_STATE_SPARE && + (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID, + &pool_guid) != 0 || + nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG, + &txg) != 0)) { + nvlist_free(label); + return (B_FALSE); + } + + nvlist_free(label); + + /* + * Check to see if this device indeed belongs to the pool it claims to + * be a part of. The only way this is allowed is if the device is a hot + * spare (which we check for later on). + */ + if (state != POOL_STATE_SPARE && + !spa_guid_exists(pool_guid, device_guid) && + !spa_spare_exists(device_guid, NULL)) + return (B_FALSE); + + /* + * If the transaction group is zero, then this an initialized (but + * unused) label. This is only an error if the create transaction + * on-disk is the same as the one we're using now, in which case the + * user has attempted to add the same vdev multiple times in the same + * transaction. + */ + if (state != POOL_STATE_SPARE && txg == 0 && vdtxg == crtxg) + return (B_TRUE); + + /* + * Check to see if this is a spare device. We do an explicit check for + * spa_has_spare() here because it may be on our pending list of spares + * to add. + */ + if (spa_spare_exists(device_guid, &spare_pool) || + spa_has_spare(spa, device_guid)) { + if (spare_guid) + *spare_guid = device_guid; + + switch (reason) { + case VDEV_LABEL_CREATE: + return (B_TRUE); + + case VDEV_LABEL_REPLACE: + return (!spa_has_spare(spa, device_guid) || + spare_pool != 0ULL); + + case VDEV_LABEL_SPARE: + return (spa_has_spare(spa, device_guid)); + } + } + + /* + * If the device is marked ACTIVE, then this device is in use by another + * pool on the system. + */ + return (state == POOL_STATE_ACTIVE); +} + +/* + * Initialize a vdev label. We check to make sure each leaf device is not in + * use, and writable. We put down an initial label which we will later + * overwrite with a complete label. 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. + */ +int +vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason) +{ + spa_t *spa = vd->vdev_spa; + nvlist_t *label; + vdev_phys_t *vp; + vdev_boot_header_t *vb; + uberblock_t *ub; + zio_t *zio; + int l, c, n; + char *buf; + size_t buflen; + int error; + uint64_t spare_guid; + + ASSERT(spa_config_held(spa, RW_WRITER)); + + for (c = 0; c < vd->vdev_children; c++) + if ((error = vdev_label_init(vd->vdev_child[c], + crtxg, reason)) != 0) + return (error); + + if (!vd->vdev_ops->vdev_op_leaf) + return (0); + + /* + * Dead vdevs cannot be initialized. + */ + if (vdev_is_dead(vd)) + return (EIO); + + /* + * Determine if the vdev is in use. + */ + if (reason != VDEV_LABEL_REMOVE && + vdev_inuse(vd, crtxg, reason, &spare_guid)) + return (EBUSY); + + ASSERT(reason != VDEV_LABEL_REMOVE || + vdev_inuse(vd, crtxg, reason, NULL)); + + /* + * If this is a request to add or replace a spare that is in use + * elsewhere on the system, then we must update the guid (which was + * initialized to a random value) to reflect the actual GUID (which is + * shared between multiple pools). + */ + if (reason != VDEV_LABEL_REMOVE && spare_guid != 0ULL) { + vdev_t *pvd = vd->vdev_parent; + + for (; pvd != NULL; pvd = pvd->vdev_parent) { + pvd->vdev_guid_sum -= vd->vdev_guid; + pvd->vdev_guid_sum += spare_guid; + } + + vd->vdev_guid = vd->vdev_guid_sum = spare_guid; + + /* + * If this is a replacement, then we want to fallthrough to the + * rest of the code. If we're adding a spare, then it's already + * labelled appropriately and we can just return. + */ + if (reason == VDEV_LABEL_SPARE) + return (0); + ASSERT(reason == VDEV_LABEL_REPLACE); + } + + /* + * 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(). + */ + if (reason == VDEV_LABEL_SPARE || + (reason == VDEV_LABEL_REMOVE && vd->vdev_isspare)) { + /* + * For inactive hot spares, we generate a special label that + * identifies as a mutually shared hot spare. We write the + * label if we are adding a hot spare, or if we are removing an + * active hot spare (in which case we want to revert the + * labels). + */ + VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0); + + VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION, + spa_version(spa)) == 0); + VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE, + POOL_STATE_SPARE) == 0); + VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID, + vd->vdev_guid) == 0); + } else { + label = spa_config_generate(spa, vd, 0ULL, B_FALSE); + + /* + * 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); + + error = nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP); + if (error != 0) { + nvlist_free(label); + zio_buf_free(vp, sizeof (vdev_phys_t)); + /* EFAULT means nvlist_pack ran out of room */ + return (error == EFAULT ? ENAMETOOLONG : 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. + */ + ub = zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)); + bzero(ub, VDEV_UBERBLOCK_SIZE(vd)); + *ub = spa->spa_uberblock; + ub->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_UBERBLOCK_COUNT(vd); n++) { + vdev_label_write(zio, vd, l, ub, + VDEV_UBERBLOCK_OFFSET(vd, n), + VDEV_UBERBLOCK_SIZE(vd), NULL, NULL); + } + } + + error = zio_wait(zio); + + nvlist_free(label); + zio_buf_free(ub, VDEV_UBERBLOCK_SIZE(vd)); + zio_buf_free(vb, sizeof (vdev_boot_header_t)); + zio_buf_free(vp, sizeof (vdev_phys_t)); + + /* + * If this vdev hasn't been previously identified as a spare, then we + * mark it as such only if a) we are labelling it as a spare, or b) it + * exists as a spare elsewhere in the system. + */ + if (error == 0 && !vd->vdev_isspare && + (reason == VDEV_LABEL_SPARE || + spa_spare_exists(vd->vdev_guid, NULL))) + spa_spare_add(vd); + + 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_t *ub = zio->io_data; + uberblock_t *ubbest = zio->io_private; + spa_t *spa = zio->io_spa; + + ASSERT3U(zio->io_size, ==, VDEV_UBERBLOCK_SIZE(zio->io_vd)); + + if (zio->io_error == 0 && 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_UBERBLOCK_COUNT(vd); n++) { + vdev_label_read(zio, vd, l, + zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)), + VDEV_UBERBLOCK_OFFSET(vd, n), + VDEV_UBERBLOCK_SIZE(vd), + vdev_uberblock_load_done, ubbest); + } + } +} + +/* + * Write the uberblock to both labels of all leaves of the specified vdev. + * We only get credit for writes to known-visible vdevs; see spa_vdev_add(). + */ +static void +vdev_uberblock_sync_done(zio_t *zio) +{ + uint64_t *good_writes = zio->io_root->io_private; + + if (zio->io_error == 0 && zio->io_vd->vdev_top->vdev_ms_array != 0) + atomic_add_64(good_writes, 1); +} + +static void +vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, uint64_t txg) +{ + int l, c, n; + + for (c = 0; c < vd->vdev_children; c++) + vdev_uberblock_sync(zio, ub, vd->vdev_child[c], txg); + + if (!vd->vdev_ops->vdev_op_leaf) + return; + + if (vdev_is_dead(vd)) + return; + + n = txg & (VDEV_UBERBLOCK_COUNT(vd) - 1); + + ASSERT(ub->ub_txg == txg); + + for (l = 0; l < VDEV_LABELS; l++) + vdev_label_write(zio, vd, l, ub, + VDEV_UBERBLOCK_OFFSET(vd, n), + VDEV_UBERBLOCK_SIZE(vd), + 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 *vd, uint64_t txg) +{ + uberblock_t *ubbuf; + size_t size = vd->vdev_top ? VDEV_UBERBLOCK_SIZE(vd) : SPA_MAXBLOCKSIZE; + uint64_t *good_writes; + zio_t *zio; + int error; + + ubbuf = zio_buf_alloc(size); + bzero(ubbuf, size); + *ubbuf = *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, ubbuf, vd, 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(ubbuf, size); + + 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, B_FALSE); + + 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, KM_SLEEP) == 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 +vdev_config_sync(vdev_t *uvd, uint64_t txg) +{ + spa_t *spa = uvd->vdev_spa; + uberblock_t *ub = &spa->spa_uberblock; + vdev_t *rvd = spa->spa_root_vdev; + vdev_t *vd; + zio_t *zio; + int 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, + * 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); + + ASSERT(txg <= spa->spa_final_txg); + + 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); + + /* + * Sync the uberblocks to all vdevs in the tree specified by uvd. + * 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); + + return (0); +} |