/* * 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 2008 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 transaction 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 #include #include #include #include #include #include #include #include #include #include /* * 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)); ASSERT(P2PHASE_TYPED(psize, sizeof (vdev_label_t), uint64_t) == 0); return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ? 0 : psize - VDEV_LABELS * sizeof (vdev_label_t))); } /* * Returns back the vdev label associated with the passed in offset. */ int vdev_label_number(uint64_t psize, uint64_t offset) { int l; if (offset >= psize - VDEV_LABEL_END_SIZE) { offset -= psize - VDEV_LABEL_END_SIZE; offset += (VDEV_LABELS / 2) * sizeof (vdev_label_t); } l = offset / sizeof (vdev_label_t); return (l < VDEV_LABELS ? l : -1); } 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, B_TRUE)); } 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, int flags) { 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, flags, B_TRUE)); } /* * 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, boolean_t isl2cache) { 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 && !isl2cache) 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_physpath != NULL) VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PHYS_PATH, vd->vdev_physpath) == 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) >= SPA_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 && !isl2cache && 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); VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_LOG, vd->vdev_islog) == 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, isl2cache); 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); if (vd->vdev_faulted) VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_FAULTED, B_TRUE) == 0); if (vd->vdev_degraded) VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DEGRADED, B_TRUE) == 0); if (vd->vdev_removed) VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVED, B_TRUE) == 0); if (vd->vdev_unspare) VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_UNSPARE, B_TRUE) == 0); } 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) || spa_config_held(spa, RW_WRITER)); if (!vdev_readable(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, uint64_t *l2cache_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; if (l2cache_guid) *l2cache_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 && state != POOL_STATE_L2CACHE && (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 && state != POOL_STATE_L2CACHE && !spa_guid_exists(pool_guid, device_guid) && !spa_spare_exists(device_guid, NULL) && !spa_l2cache_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 && state != POOL_STATE_L2CACHE && 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. We also check if it is an l2cache device. */ 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: case VDEV_LABEL_L2CACHE: 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)); } } /* * Check to see if this is an l2cache device. */ if (spa_l2cache_exists(device_guid, NULL)) return (B_TRUE); /* * 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, l2cache_guid; int flags = ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL; 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, &l2cache_guid)) return (EBUSY); ASSERT(reason != VDEV_LABEL_REMOVE || vdev_inuse(vd, crtxg, reason, NULL, NULL)); /* * If this is a request to add or replace a spare or l2cache device * 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 && reason != VDEV_LABEL_L2CACHE && 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 * labeled appropriately and we can just return. */ if (reason == VDEV_LABEL_SPARE) return (0); ASSERT(reason == VDEV_LABEL_REPLACE); } if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPARE && l2cache_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 += l2cache_guid; } vd->vdev_guid = vd->vdev_guid_sum = l2cache_guid; /* * If this is a replacement, then we want to fallthrough to the * rest of the code. If we're adding an l2cache, then it's * already labeled appropriately and we can just return. */ if (reason == VDEV_LABEL_L2CACHE) 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 if (reason == VDEV_LABEL_L2CACHE || (reason == VDEV_LABEL_REMOVE && vd->vdev_isl2cache)) { /* * For level 2 ARC devices, add a special label. */ 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_L2CACHE) == 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, flags); 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, flags); vdev_label_write(zio, vd, l, vb, offsetof(vdev_label_t, vl_boot_header), sizeof (vdev_boot_header_t), NULL, NULL, flags); 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, flags); } } 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 labeling it as a spare, or b) it * exists as a spare elsewhere in the system. Do the same for * level 2 ARC devices. */ if (error == 0 && !vd->vdev_isspare && (reason == VDEV_LABEL_SPARE || spa_spare_exists(vd->vdev_guid, NULL))) spa_spare_add(vd); if (error == 0 && !vd->vdev_isl2cache && (reason == VDEV_LABEL_L2CACHE || spa_l2cache_exists(vd->vdev_guid, NULL))) spa_l2cache_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); } } } /* * On success, increment root zio's count of good writes. * 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_private; if (zio->io_error == 0 && zio->io_vd->vdev_top->vdev_ms_array != 0) atomic_add_64(good_writes, 1); } /* * Write the uberblock to all labels of all leaves of the specified vdev. */ static void vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd) { int l, c, n; uberblock_t *ubbuf; for (c = 0; c < vd->vdev_children; c++) vdev_uberblock_sync(zio, ub, vd->vdev_child[c]); if (!vd->vdev_ops->vdev_op_leaf) return; if (vdev_is_dead(vd)) return; n = ub->ub_txg & (VDEV_UBERBLOCK_COUNT(vd) - 1); ubbuf = zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)); bzero(ubbuf, VDEV_UBERBLOCK_SIZE(vd)); *ubbuf = *ub; for (l = 0; l < VDEV_LABELS; l++) vdev_label_write(zio, vd, l, ubbuf, VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd), vdev_uberblock_sync_done, zio->io_private, ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE); zio_buf_free(ubbuf, VDEV_UBERBLOCK_SIZE(vd)); } static void vdev_uberblock_sync_list_done(zio_t *zio) { uint64_t *good_writes = zio->io_private; if (*good_writes == 0) zio->io_error = EIO; } int vdev_uberblock_sync_list(vdev_t **svd, int svdcount, uberblock_t *ub, int flags) { spa_t *spa = svd[0]->vdev_spa; int v; zio_t *zio, *nio; uint64_t good_writes = 0; int io_flags = flags; /* * If we've been asked to update all the vdevs then we change * our flags to ZIO_FLAG_MUSTSUCCEED so that the pipeline can * handle error should all update fail. */ if (svdcount == spa->spa_root_vdev->vdev_children) io_flags &= ~ZIO_FLAG_CANFAIL; /* * We rely on the value of good_writes and the root I/O to determine * how a complete failure is handled. In the event that the root is a * ZIO_FLAG_MUSTSUCCED, then the pipeline will block this I/O if we * were unable to update any uberblock. Once the I/O is blocked the * pipeline will retry it when the error is cleared. Unfortunately, * the pipeline does not have the complete I/O tree so it will be * unable to retry the actual uberblock update. Instead we rely on * the value of good_writes to return the failed status to the caller * which will retry on error and thus resubmit the complete I/O * tree. */ zio = zio_root(spa, NULL, NULL, io_flags); nio = zio_null(zio, spa, vdev_uberblock_sync_list_done, &good_writes, flags); for (v = 0; v < svdcount; v++) vdev_uberblock_sync(nio, ub, svd[v]); zio_nowait(nio); (void) zio_wait(zio); /* * 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. */ zio = zio_root(spa, NULL, NULL, flags); for (v = 0; v < svdcount; v++) zio_flush(zio, svd[v]); (void) zio_wait(zio); return (good_writes >= 1 ? 0 : EIO); } /* * On success, increment the count of good writes for our top-level vdev. */ static void vdev_label_sync_done(zio_t *zio) { uint64_t *good_writes = zio->io_private; if (zio->io_error == 0) atomic_add_64(good_writes, 1); } /* * If there weren't enough good writes, indicate failure to the parent. */ static void vdev_label_sync_top_done(zio_t *zio) { uint64_t *good_writes = zio->io_private; if (*good_writes == 0) zio->io_error = EIO; kmem_free(good_writes, sizeof (uint64_t)); } /* * Write all even or odd labels to all leaves of the specified vdev. */ static void vdev_label_sync(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_label_sync(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) { for (; l < VDEV_LABELS; l += 2) { vdev_label_write(zio, vd, l, vp, offsetof(vdev_label_t, vl_vdev_phys), sizeof (vdev_phys_t), vdev_label_sync_done, zio->io_private, ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE); } } zio_buf_free(vp, sizeof (vdev_phys_t)); nvlist_free(label); } int vdev_label_sync_list(spa_t *spa, int l, int flags, uint64_t txg) { list_t *dl = &spa->spa_dirty_list; vdev_t *vd; zio_t *zio, *nio; int error; int io_flags = flags & ~ZIO_FLAG_CANFAIL; /* * The root I/O for all label updates must succeed and we track * the error returned back from the null I/O to determine if we * need to reissue the I/O tree from scratch. If we are unable * to update any leaf vdev associated with a dirty top-level vdev, * then the pipeline will either suspend or panic when the root I/O * is issued. If the error is cleared, then the pipleine will retry * the root I/O. Unfortunately we've lost the entire I/O tree so we * return back the original error to the caller and allow the caller * to call use again so that we can build the I/O tree from scratch. */ zio = zio_root(spa, NULL, NULL, io_flags); nio = zio_null(zio, spa, NULL, NULL, flags); for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) { uint64_t *good_writes = kmem_zalloc(sizeof (uint64_t), KM_SLEEP); zio_t *vio = zio_null(nio, spa, vdev_label_sync_top_done, good_writes, flags); vdev_label_sync(vio, vd, l, txg); zio_nowait(vio); } error = zio_wait(nio); (void) zio_wait(zio); /* * Flush the new labels to disk. */ zio = zio_root(spa, NULL, NULL, flags); for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) zio_flush(zio, vd); (void) zio_wait(zio); return (error); } /* * Sync the uberblock and any changes to the 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, vdev_config_sync() is designed to be idempotent: if it fails * at any time, you can just call it again, and it will resume its work. */ void vdev_config_sync(vdev_t **svd, int svdcount, uint64_t txg) { spa_t *spa = svd[0]->vdev_spa; uberblock_t *ub = &spa->spa_uberblock; vdev_t *vd; zio_t *zio; int flags = ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL; 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, spa->spa_root_vdev, txg) == B_FALSE && list_is_empty(&spa->spa_dirty_list)) return; if (txg > spa_freeze_txg(spa)) return; ASSERT(txg <= spa->spa_final_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, flags); 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_flush(zio, vd); (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. We flush * the new labels to disk to ensure that all even-label updates * are committed to stable storage before the uberblock update. * Failure to update any of the labels will invoke the 'failmode' * code path. Thus we must retry the entire I/O tree once the error * is cleared and we ar resumed. */ while (vdev_label_sync_list(spa, 0, flags, txg) != 0) ; /* * Sync the uberblocks to all vdevs in svd[]. If we are unable * to do so, then we attempt to sync out to all top-level vdevs. * 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. * * In addition, if we have failed to update all the uberblocks then * we will follow the 'failmode' code path. We must retry the entire * I/O tree if we are resumed. */ if (vdev_uberblock_sync_list(svd, svdcount, ub, flags) != 0) { vdev_t *rvd = spa->spa_root_vdev; while (vdev_uberblock_sync_list(rvd->vdev_child, rvd->vdev_children, ub, flags)) ; } /* * 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. We flush the new labels * to disk to ensure that all odd-label updates are committed to * stable storage before the next transaction group begins. * Failure to update any of the labels will invoke the 'failmode' * code path. Thus we must retry the entire I/O tree once the error * is cleared and we are resumed. */ while (vdev_label_sync_list(spa, 1, flags, txg) != 0) ; }