/* * 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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2012 by Delphix. All rights reserved. */ #include #include #include #include #include #include #include /* * Allow allocations to switch to gang blocks quickly. We do this to * avoid having to load lots of space_maps in a given txg. There are, * however, some cases where we want to avoid "fast" ganging and instead * we want to do an exhaustive search of all metaslabs on this device. * Currently we don't allow any gang, zil, or dump device related allocations * to "fast" gang. */ #define CAN_FASTGANG(flags) \ (!((flags) & (METASLAB_GANG_CHILD | METASLAB_GANG_HEADER | \ METASLAB_GANG_AVOID))) uint64_t metaslab_aliquot = 512ULL << 10; uint64_t metaslab_gang_bang = SPA_MAXBLOCKSIZE + 1; /* force gang blocks */ /* * This value defines the number of allowed allocation failures per vdev. * If a device reaches this threshold in a given txg then we consider skipping * allocations on that device. */ int zfs_mg_alloc_failures; /* * Metaslab debugging: when set, keeps all space maps in core to verify frees. */ static int metaslab_debug = 0; /* * Minimum size which forces the dynamic allocator to change * it's allocation strategy. Once the space map cannot satisfy * an allocation of this size then it switches to using more * aggressive strategy (i.e search by size rather than offset). */ uint64_t metaslab_df_alloc_threshold = SPA_MAXBLOCKSIZE; /* * The minimum free space, in percent, which must be available * in a space map to continue allocations in a first-fit fashion. * Once the space_map's free space drops below this level we dynamically * switch to using best-fit allocations. */ int metaslab_df_free_pct = 4; /* * A metaslab is considered "free" if it contains a contiguous * segment which is greater than metaslab_min_alloc_size. */ uint64_t metaslab_min_alloc_size = DMU_MAX_ACCESS; /* * Max number of space_maps to prefetch. */ int metaslab_prefetch_limit = SPA_DVAS_PER_BP; /* * Percentage bonus multiplier for metaslabs that are in the bonus area. */ int metaslab_smo_bonus_pct = 150; /* * ========================================================================== * Metaslab classes * ========================================================================== */ metaslab_class_t * metaslab_class_create(spa_t *spa, space_map_ops_t *ops) { metaslab_class_t *mc; mc = kmem_zalloc(sizeof (metaslab_class_t), KM_SLEEP); mc->mc_spa = spa; mc->mc_rotor = NULL; mc->mc_ops = ops; return (mc); } void metaslab_class_destroy(metaslab_class_t *mc) { ASSERT(mc->mc_rotor == NULL); ASSERT(mc->mc_alloc == 0); ASSERT(mc->mc_deferred == 0); ASSERT(mc->mc_space == 0); ASSERT(mc->mc_dspace == 0); kmem_free(mc, sizeof (metaslab_class_t)); } int metaslab_class_validate(metaslab_class_t *mc) { metaslab_group_t *mg; vdev_t *vd; /* * Must hold one of the spa_config locks. */ ASSERT(spa_config_held(mc->mc_spa, SCL_ALL, RW_READER) || spa_config_held(mc->mc_spa, SCL_ALL, RW_WRITER)); if ((mg = mc->mc_rotor) == NULL) return (0); do { vd = mg->mg_vd; ASSERT(vd->vdev_mg != NULL); ASSERT3P(vd->vdev_top, ==, vd); ASSERT3P(mg->mg_class, ==, mc); ASSERT3P(vd->vdev_ops, !=, &vdev_hole_ops); } while ((mg = mg->mg_next) != mc->mc_rotor); return (0); } void metaslab_class_space_update(metaslab_class_t *mc, int64_t alloc_delta, int64_t defer_delta, int64_t space_delta, int64_t dspace_delta) { atomic_add_64(&mc->mc_alloc, alloc_delta); atomic_add_64(&mc->mc_deferred, defer_delta); atomic_add_64(&mc->mc_space, space_delta); atomic_add_64(&mc->mc_dspace, dspace_delta); } uint64_t metaslab_class_get_alloc(metaslab_class_t *mc) { return (mc->mc_alloc); } uint64_t metaslab_class_get_deferred(metaslab_class_t *mc) { return (mc->mc_deferred); } uint64_t metaslab_class_get_space(metaslab_class_t *mc) { return (mc->mc_space); } uint64_t metaslab_class_get_dspace(metaslab_class_t *mc) { return (spa_deflate(mc->mc_spa) ? mc->mc_dspace : mc->mc_space); } /* * ========================================================================== * Metaslab groups * ========================================================================== */ static int metaslab_compare(const void *x1, const void *x2) { const metaslab_t *m1 = x1; const metaslab_t *m2 = x2; if (m1->ms_weight < m2->ms_weight) return (1); if (m1->ms_weight > m2->ms_weight) return (-1); /* * If the weights are identical, use the offset to force uniqueness. */ if (m1->ms_map.sm_start < m2->ms_map.sm_start) return (-1); if (m1->ms_map.sm_start > m2->ms_map.sm_start) return (1); ASSERT3P(m1, ==, m2); return (0); } metaslab_group_t * metaslab_group_create(metaslab_class_t *mc, vdev_t *vd) { metaslab_group_t *mg; mg = kmem_zalloc(sizeof (metaslab_group_t), KM_SLEEP); mutex_init(&mg->mg_lock, NULL, MUTEX_DEFAULT, NULL); avl_create(&mg->mg_metaslab_tree, metaslab_compare, sizeof (metaslab_t), offsetof(struct metaslab, ms_group_node)); mg->mg_vd = vd; mg->mg_class = mc; mg->mg_activation_count = 0; return (mg); } void metaslab_group_destroy(metaslab_group_t *mg) { ASSERT(mg->mg_prev == NULL); ASSERT(mg->mg_next == NULL); /* * We may have gone below zero with the activation count * either because we never activated in the first place or * because we're done, and possibly removing the vdev. */ ASSERT(mg->mg_activation_count <= 0); avl_destroy(&mg->mg_metaslab_tree); mutex_destroy(&mg->mg_lock); kmem_free(mg, sizeof (metaslab_group_t)); } void metaslab_group_activate(metaslab_group_t *mg) { metaslab_class_t *mc = mg->mg_class; metaslab_group_t *mgprev, *mgnext; ASSERT(spa_config_held(mc->mc_spa, SCL_ALLOC, RW_WRITER)); ASSERT(mc->mc_rotor != mg); ASSERT(mg->mg_prev == NULL); ASSERT(mg->mg_next == NULL); ASSERT(mg->mg_activation_count <= 0); if (++mg->mg_activation_count <= 0) return; mg->mg_aliquot = metaslab_aliquot * MAX(1, mg->mg_vd->vdev_children); if ((mgprev = mc->mc_rotor) == NULL) { mg->mg_prev = mg; mg->mg_next = mg; } else { mgnext = mgprev->mg_next; mg->mg_prev = mgprev; mg->mg_next = mgnext; mgprev->mg_next = mg; mgnext->mg_prev = mg; } mc->mc_rotor = mg; } void metaslab_group_passivate(metaslab_group_t *mg) { metaslab_class_t *mc = mg->mg_class; metaslab_group_t *mgprev, *mgnext; ASSERT(spa_config_held(mc->mc_spa, SCL_ALLOC, RW_WRITER)); if (--mg->mg_activation_count != 0) { ASSERT(mc->mc_rotor != mg); ASSERT(mg->mg_prev == NULL); ASSERT(mg->mg_next == NULL); ASSERT(mg->mg_activation_count < 0); return; } mgprev = mg->mg_prev; mgnext = mg->mg_next; if (mg == mgnext) { mc->mc_rotor = NULL; } else { mc->mc_rotor = mgnext; mgprev->mg_next = mgnext; mgnext->mg_prev = mgprev; } mg->mg_prev = NULL; mg->mg_next = NULL; } static void metaslab_group_add(metaslab_group_t *mg, metaslab_t *msp) { mutex_enter(&mg->mg_lock); ASSERT(msp->ms_group == NULL); msp->ms_group = mg; msp->ms_weight = 0; avl_add(&mg->mg_metaslab_tree, msp); mutex_exit(&mg->mg_lock); } static void metaslab_group_remove(metaslab_group_t *mg, metaslab_t *msp) { mutex_enter(&mg->mg_lock); ASSERT(msp->ms_group == mg); avl_remove(&mg->mg_metaslab_tree, msp); msp->ms_group = NULL; mutex_exit(&mg->mg_lock); } static void metaslab_group_sort(metaslab_group_t *mg, metaslab_t *msp, uint64_t weight) { /* * Although in principle the weight can be any value, in * practice we do not use values in the range [1, 510]. */ ASSERT(weight >= SPA_MINBLOCKSIZE-1 || weight == 0); ASSERT(MUTEX_HELD(&msp->ms_lock)); mutex_enter(&mg->mg_lock); ASSERT(msp->ms_group == mg); avl_remove(&mg->mg_metaslab_tree, msp); msp->ms_weight = weight; avl_add(&mg->mg_metaslab_tree, msp); mutex_exit(&mg->mg_lock); } /* * ========================================================================== * Common allocator routines * ========================================================================== */ static int metaslab_segsize_compare(const void *x1, const void *x2) { const space_seg_t *s1 = x1; const space_seg_t *s2 = x2; uint64_t ss_size1 = s1->ss_end - s1->ss_start; uint64_t ss_size2 = s2->ss_end - s2->ss_start; if (ss_size1 < ss_size2) return (-1); if (ss_size1 > ss_size2) return (1); if (s1->ss_start < s2->ss_start) return (-1); if (s1->ss_start > s2->ss_start) return (1); return (0); } /* * This is a helper function that can be used by the allocator to find * a suitable block to allocate. This will search the specified AVL * tree looking for a block that matches the specified criteria. */ static uint64_t metaslab_block_picker(avl_tree_t *t, uint64_t *cursor, uint64_t size, uint64_t align) { space_seg_t *ss, ssearch; avl_index_t where; ssearch.ss_start = *cursor; ssearch.ss_end = *cursor + size; ss = avl_find(t, &ssearch, &where); if (ss == NULL) ss = avl_nearest(t, where, AVL_AFTER); while (ss != NULL) { uint64_t offset = P2ROUNDUP(ss->ss_start, align); if (offset + size <= ss->ss_end) { *cursor = offset + size; return (offset); } ss = AVL_NEXT(t, ss); } /* * If we know we've searched the whole map (*cursor == 0), give up. * Otherwise, reset the cursor to the beginning and try again. */ if (*cursor == 0) return (-1ULL); *cursor = 0; return (metaslab_block_picker(t, cursor, size, align)); } static void metaslab_pp_load(space_map_t *sm) { space_seg_t *ss; ASSERT(sm->sm_ppd == NULL); sm->sm_ppd = kmem_zalloc(64 * sizeof (uint64_t), KM_SLEEP); sm->sm_pp_root = kmem_alloc(sizeof (avl_tree_t), KM_SLEEP); avl_create(sm->sm_pp_root, metaslab_segsize_compare, sizeof (space_seg_t), offsetof(struct space_seg, ss_pp_node)); for (ss = avl_first(&sm->sm_root); ss; ss = AVL_NEXT(&sm->sm_root, ss)) avl_add(sm->sm_pp_root, ss); } static void metaslab_pp_unload(space_map_t *sm) { void *cookie = NULL; kmem_free(sm->sm_ppd, 64 * sizeof (uint64_t)); sm->sm_ppd = NULL; while (avl_destroy_nodes(sm->sm_pp_root, &cookie) != NULL) { /* tear down the tree */ } avl_destroy(sm->sm_pp_root); kmem_free(sm->sm_pp_root, sizeof (avl_tree_t)); sm->sm_pp_root = NULL; } /* ARGSUSED */ static void metaslab_pp_claim(space_map_t *sm, uint64_t start, uint64_t size) { /* No need to update cursor */ } /* ARGSUSED */ static void metaslab_pp_free(space_map_t *sm, uint64_t start, uint64_t size) { /* No need to update cursor */ } /* * Return the maximum contiguous segment within the metaslab. */ uint64_t metaslab_pp_maxsize(space_map_t *sm) { avl_tree_t *t = sm->sm_pp_root; space_seg_t *ss; if (t == NULL || (ss = avl_last(t)) == NULL) return (0ULL); return (ss->ss_end - ss->ss_start); } /* * ========================================================================== * The first-fit block allocator * ========================================================================== */ static uint64_t metaslab_ff_alloc(space_map_t *sm, uint64_t size) { avl_tree_t *t = &sm->sm_root; uint64_t align = size & -size; uint64_t *cursor = (uint64_t *)sm->sm_ppd + highbit(align) - 1; return (metaslab_block_picker(t, cursor, size, align)); } /* ARGSUSED */ boolean_t metaslab_ff_fragmented(space_map_t *sm) { return (B_TRUE); } static space_map_ops_t metaslab_ff_ops = { metaslab_pp_load, metaslab_pp_unload, metaslab_ff_alloc, metaslab_pp_claim, metaslab_pp_free, metaslab_pp_maxsize, metaslab_ff_fragmented }; /* * ========================================================================== * Dynamic block allocator - * Uses the first fit allocation scheme until space get low and then * adjusts to a best fit allocation method. Uses metaslab_df_alloc_threshold * and metaslab_df_free_pct to determine when to switch the allocation scheme. * ========================================================================== */ static uint64_t metaslab_df_alloc(space_map_t *sm, uint64_t size) { avl_tree_t *t = &sm->sm_root; uint64_t align = size & -size; uint64_t *cursor = (uint64_t *)sm->sm_ppd + highbit(align) - 1; uint64_t max_size = metaslab_pp_maxsize(sm); int free_pct = sm->sm_space * 100 / sm->sm_size; ASSERT(MUTEX_HELD(sm->sm_lock)); ASSERT3U(avl_numnodes(&sm->sm_root), ==, avl_numnodes(sm->sm_pp_root)); if (max_size < size) return (-1ULL); /* * If we're running low on space switch to using the size * sorted AVL tree (best-fit). */ if (max_size < metaslab_df_alloc_threshold || free_pct < metaslab_df_free_pct) { t = sm->sm_pp_root; *cursor = 0; } return (metaslab_block_picker(t, cursor, size, 1ULL)); } static boolean_t metaslab_df_fragmented(space_map_t *sm) { uint64_t max_size = metaslab_pp_maxsize(sm); int free_pct = sm->sm_space * 100 / sm->sm_size; if (max_size >= metaslab_df_alloc_threshold && free_pct >= metaslab_df_free_pct) return (B_FALSE); return (B_TRUE); } static space_map_ops_t metaslab_df_ops = { metaslab_pp_load, metaslab_pp_unload, metaslab_df_alloc, metaslab_pp_claim, metaslab_pp_free, metaslab_pp_maxsize, metaslab_df_fragmented }; /* * ========================================================================== * Other experimental allocators * ========================================================================== */ static uint64_t metaslab_cdf_alloc(space_map_t *sm, uint64_t size) { avl_tree_t *t = &sm->sm_root; uint64_t *cursor = (uint64_t *)sm->sm_ppd; uint64_t *extent_end = (uint64_t *)sm->sm_ppd + 1; uint64_t max_size = metaslab_pp_maxsize(sm); uint64_t rsize = size; uint64_t offset = 0; ASSERT(MUTEX_HELD(sm->sm_lock)); ASSERT3U(avl_numnodes(&sm->sm_root), ==, avl_numnodes(sm->sm_pp_root)); if (max_size < size) return (-1ULL); ASSERT3U(*extent_end, >=, *cursor); /* * If we're running low on space switch to using the size * sorted AVL tree (best-fit). */ if ((*cursor + size) > *extent_end) { t = sm->sm_pp_root; *cursor = *extent_end = 0; if (max_size > 2 * SPA_MAXBLOCKSIZE) rsize = MIN(metaslab_min_alloc_size, max_size); offset = metaslab_block_picker(t, extent_end, rsize, 1ULL); if (offset != -1) *cursor = offset + size; } else { offset = metaslab_block_picker(t, cursor, rsize, 1ULL); } ASSERT3U(*cursor, <=, *extent_end); return (offset); } static boolean_t metaslab_cdf_fragmented(space_map_t *sm) { uint64_t max_size = metaslab_pp_maxsize(sm); if (max_size > (metaslab_min_alloc_size * 10)) return (B_FALSE); return (B_TRUE); } static space_map_ops_t metaslab_cdf_ops = { metaslab_pp_load, metaslab_pp_unload, metaslab_cdf_alloc, metaslab_pp_claim, metaslab_pp_free, metaslab_pp_maxsize, metaslab_cdf_fragmented }; uint64_t metaslab_ndf_clump_shift = 4; static uint64_t metaslab_ndf_alloc(space_map_t *sm, uint64_t size) { avl_tree_t *t = &sm->sm_root; avl_index_t where; space_seg_t *ss, ssearch; uint64_t hbit = highbit(size); uint64_t *cursor = (uint64_t *)sm->sm_ppd + hbit - 1; uint64_t max_size = metaslab_pp_maxsize(sm); ASSERT(MUTEX_HELD(sm->sm_lock)); ASSERT3U(avl_numnodes(&sm->sm_root), ==, avl_numnodes(sm->sm_pp_root)); if (max_size < size) return (-1ULL); ssearch.ss_start = *cursor; ssearch.ss_end = *cursor + size; ss = avl_find(t, &ssearch, &where); if (ss == NULL || (ss->ss_start + size > ss->ss_end)) { t = sm->sm_pp_root; ssearch.ss_start = 0; ssearch.ss_end = MIN(max_size, 1ULL << (hbit + metaslab_ndf_clump_shift)); ss = avl_find(t, &ssearch, &where); if (ss == NULL) ss = avl_nearest(t, where, AVL_AFTER); ASSERT(ss != NULL); } if (ss != NULL) { if (ss->ss_start + size <= ss->ss_end) { *cursor = ss->ss_start + size; return (ss->ss_start); } } return (-1ULL); } static boolean_t metaslab_ndf_fragmented(space_map_t *sm) { uint64_t max_size = metaslab_pp_maxsize(sm); if (max_size > (metaslab_min_alloc_size << metaslab_ndf_clump_shift)) return (B_FALSE); return (B_TRUE); } static space_map_ops_t metaslab_ndf_ops = { metaslab_pp_load, metaslab_pp_unload, metaslab_ndf_alloc, metaslab_pp_claim, metaslab_pp_free, metaslab_pp_maxsize, metaslab_ndf_fragmented }; space_map_ops_t *zfs_metaslab_ops = &metaslab_df_ops; /* * ========================================================================== * Metaslabs * ========================================================================== */ metaslab_t * metaslab_init(metaslab_group_t *mg, space_map_obj_t *smo, uint64_t start, uint64_t size, uint64_t txg) { vdev_t *vd = mg->mg_vd; metaslab_t *msp; msp = kmem_zalloc(sizeof (metaslab_t), KM_SLEEP); mutex_init(&msp->ms_lock, NULL, MUTEX_DEFAULT, NULL); msp->ms_smo_syncing = *smo; /* * We create the main space map here, but we don't create the * allocmaps and freemaps until metaslab_sync_done(). This serves * two purposes: it allows metaslab_sync_done() to detect the * addition of new space; and for debugging, it ensures that we'd * data fault on any attempt to use this metaslab before it's ready. */ space_map_create(&msp->ms_map, start, size, vd->vdev_ashift, &msp->ms_lock); metaslab_group_add(mg, msp); if (metaslab_debug && smo->smo_object != 0) { mutex_enter(&msp->ms_lock); VERIFY(space_map_load(&msp->ms_map, mg->mg_class->mc_ops, SM_FREE, smo, spa_meta_objset(vd->vdev_spa)) == 0); mutex_exit(&msp->ms_lock); } /* * If we're opening an existing pool (txg == 0) or creating * a new one (txg == TXG_INITIAL), all space is available now. * If we're adding space to an existing pool, the new space * does not become available until after this txg has synced. */ if (txg <= TXG_INITIAL) metaslab_sync_done(msp, 0); if (txg != 0) { vdev_dirty(vd, 0, NULL, txg); vdev_dirty(vd, VDD_METASLAB, msp, txg); } return (msp); } void metaslab_fini(metaslab_t *msp) { metaslab_group_t *mg = msp->ms_group; vdev_space_update(mg->mg_vd, -msp->ms_smo.smo_alloc, 0, -msp->ms_map.sm_size); metaslab_group_remove(mg, msp); mutex_enter(&msp->ms_lock); space_map_unload(&msp->ms_map); space_map_destroy(&msp->ms_map); for (int t = 0; t < TXG_SIZE; t++) { space_map_destroy(&msp->ms_allocmap[t]); space_map_destroy(&msp->ms_freemap[t]); } for (int t = 0; t < TXG_DEFER_SIZE; t++) space_map_destroy(&msp->ms_defermap[t]); ASSERT0(msp->ms_deferspace); mutex_exit(&msp->ms_lock); mutex_destroy(&msp->ms_lock); kmem_free(msp, sizeof (metaslab_t)); } #define METASLAB_WEIGHT_PRIMARY (1ULL << 63) #define METASLAB_WEIGHT_SECONDARY (1ULL << 62) #define METASLAB_ACTIVE_MASK \ (METASLAB_WEIGHT_PRIMARY | METASLAB_WEIGHT_SECONDARY) static uint64_t metaslab_weight(metaslab_t *msp) { metaslab_group_t *mg = msp->ms_group; space_map_t *sm = &msp->ms_map; space_map_obj_t *smo = &msp->ms_smo; vdev_t *vd = mg->mg_vd; uint64_t weight, space; ASSERT(MUTEX_HELD(&msp->ms_lock)); /* * The baseline weight is the metaslab's free space. */ space = sm->sm_size - smo->smo_alloc; weight = space; /* * Modern disks have uniform bit density and constant angular velocity. * Therefore, the outer recording zones are faster (higher bandwidth) * than the inner zones by the ratio of outer to inner track diameter, * which is typically around 2:1. We account for this by assigning * higher weight to lower metaslabs (multiplier ranging from 2x to 1x). * In effect, this means that we'll select the metaslab with the most * free bandwidth rather than simply the one with the most free space. */ weight = 2 * weight - ((sm->sm_start >> vd->vdev_ms_shift) * weight) / vd->vdev_ms_count; ASSERT(weight >= space && weight <= 2 * space); /* * For locality, assign higher weight to metaslabs which have * a lower offset than what we've already activated. */ if (sm->sm_start <= mg->mg_bonus_area) weight *= (metaslab_smo_bonus_pct / 100); ASSERT(weight >= space && weight <= 2 * (metaslab_smo_bonus_pct / 100) * space); if (sm->sm_loaded && !sm->sm_ops->smop_fragmented(sm)) { /* * If this metaslab is one we're actively using, adjust its * weight to make it preferable to any inactive metaslab so * we'll polish it off. */ weight |= (msp->ms_weight & METASLAB_ACTIVE_MASK); } return (weight); } static void metaslab_prefetch(metaslab_group_t *mg) { spa_t *spa = mg->mg_vd->vdev_spa; metaslab_t *msp; avl_tree_t *t = &mg->mg_metaslab_tree; int m; mutex_enter(&mg->mg_lock); /* * Prefetch the next potential metaslabs */ for (msp = avl_first(t), m = 0; msp; msp = AVL_NEXT(t, msp), m++) { space_map_t *sm = &msp->ms_map; space_map_obj_t *smo = &msp->ms_smo; /* If we have reached our prefetch limit then we're done */ if (m >= metaslab_prefetch_limit) break; if (!sm->sm_loaded && smo->smo_object != 0) { mutex_exit(&mg->mg_lock); dmu_prefetch(spa_meta_objset(spa), smo->smo_object, 0ULL, smo->smo_objsize); mutex_enter(&mg->mg_lock); } } mutex_exit(&mg->mg_lock); } static int metaslab_activate(metaslab_t *msp, uint64_t activation_weight) { metaslab_group_t *mg = msp->ms_group; space_map_t *sm = &msp->ms_map; space_map_ops_t *sm_ops = msp->ms_group->mg_class->mc_ops; ASSERT(MUTEX_HELD(&msp->ms_lock)); if ((msp->ms_weight & METASLAB_ACTIVE_MASK) == 0) { space_map_load_wait(sm); if (!sm->sm_loaded) { int error = space_map_load(sm, sm_ops, SM_FREE, &msp->ms_smo, spa_meta_objset(msp->ms_group->mg_vd->vdev_spa)); if (error) { metaslab_group_sort(msp->ms_group, msp, 0); return (error); } for (int t = 0; t < TXG_DEFER_SIZE; t++) space_map_walk(&msp->ms_defermap[t], space_map_claim, sm); } /* * Track the bonus area as we activate new metaslabs. */ if (sm->sm_start > mg->mg_bonus_area) { mutex_enter(&mg->mg_lock); mg->mg_bonus_area = sm->sm_start; mutex_exit(&mg->mg_lock); } metaslab_group_sort(msp->ms_group, msp, msp->ms_weight | activation_weight); } ASSERT(sm->sm_loaded); ASSERT(msp->ms_weight & METASLAB_ACTIVE_MASK); return (0); } static void metaslab_passivate(metaslab_t *msp, uint64_t size) { /* * If size < SPA_MINBLOCKSIZE, then we will not allocate from * this metaslab again. In that case, it had better be empty, * or we would be leaving space on the table. */ ASSERT(size >= SPA_MINBLOCKSIZE || msp->ms_map.sm_space == 0); metaslab_group_sort(msp->ms_group, msp, MIN(msp->ms_weight, size)); ASSERT((msp->ms_weight & METASLAB_ACTIVE_MASK) == 0); } /* * Write a metaslab to disk in the context of the specified transaction group. */ void metaslab_sync(metaslab_t *msp, uint64_t txg) { vdev_t *vd = msp->ms_group->mg_vd; spa_t *spa = vd->vdev_spa; objset_t *mos = spa_meta_objset(spa); space_map_t *allocmap = &msp->ms_allocmap[txg & TXG_MASK]; space_map_t *freemap = &msp->ms_freemap[txg & TXG_MASK]; space_map_t *freed_map = &msp->ms_freemap[TXG_CLEAN(txg) & TXG_MASK]; space_map_t *sm = &msp->ms_map; space_map_obj_t *smo = &msp->ms_smo_syncing; dmu_buf_t *db; dmu_tx_t *tx; ASSERT(!vd->vdev_ishole); if (allocmap->sm_space == 0 && freemap->sm_space == 0) return; /* * The only state that can actually be changing concurrently with * metaslab_sync() is the metaslab's ms_map. No other thread can * be modifying this txg's allocmap, freemap, freed_map, or smo. * Therefore, we only hold ms_lock to satify space_map ASSERTs. * We drop it whenever we call into the DMU, because the DMU * can call down to us (e.g. via zio_free()) at any time. */ tx = dmu_tx_create_assigned(spa_get_dsl(spa), txg); if (smo->smo_object == 0) { ASSERT(smo->smo_objsize == 0); ASSERT(smo->smo_alloc == 0); smo->smo_object = dmu_object_alloc(mos, DMU_OT_SPACE_MAP, 1 << SPACE_MAP_BLOCKSHIFT, DMU_OT_SPACE_MAP_HEADER, sizeof (*smo), tx); ASSERT(smo->smo_object != 0); dmu_write(mos, vd->vdev_ms_array, sizeof (uint64_t) * (sm->sm_start >> vd->vdev_ms_shift), sizeof (uint64_t), &smo->smo_object, tx); } mutex_enter(&msp->ms_lock); space_map_walk(freemap, space_map_add, freed_map); if (sm->sm_loaded && spa_sync_pass(spa) == 1 && smo->smo_objsize >= 2 * sizeof (uint64_t) * avl_numnodes(&sm->sm_root)) { /* * The in-core space map representation is twice as compact * as the on-disk one, so it's time to condense the latter * by generating a pure allocmap from first principles. * * This metaslab is 100% allocated, * minus the content of the in-core map (sm), * minus what's been freed this txg (freed_map), * minus deferred frees (ms_defermap[]), * minus allocations from txgs in the future * (because they haven't been committed yet). */ space_map_vacate(allocmap, NULL, NULL); space_map_vacate(freemap, NULL, NULL); space_map_add(allocmap, allocmap->sm_start, allocmap->sm_size); space_map_walk(sm, space_map_remove, allocmap); space_map_walk(freed_map, space_map_remove, allocmap); for (int t = 0; t < TXG_DEFER_SIZE; t++) space_map_walk(&msp->ms_defermap[t], space_map_remove, allocmap); for (int t = 1; t < TXG_CONCURRENT_STATES; t++) space_map_walk(&msp->ms_allocmap[(txg + t) & TXG_MASK], space_map_remove, allocmap); mutex_exit(&msp->ms_lock); space_map_truncate(smo, mos, tx); mutex_enter(&msp->ms_lock); } space_map_sync(allocmap, SM_ALLOC, smo, mos, tx); space_map_sync(freemap, SM_FREE, smo, mos, tx); mutex_exit(&msp->ms_lock); VERIFY(0 == dmu_bonus_hold(mos, smo->smo_object, FTAG, &db)); dmu_buf_will_dirty(db, tx); ASSERT3U(db->db_size, >=, sizeof (*smo)); bcopy(smo, db->db_data, sizeof (*smo)); dmu_buf_rele(db, FTAG); dmu_tx_commit(tx); } /* * Called after a transaction group has completely synced to mark * all of the metaslab's free space as usable. */ void metaslab_sync_done(metaslab_t *msp, uint64_t txg) { space_map_obj_t *smo = &msp->ms_smo; space_map_obj_t *smosync = &msp->ms_smo_syncing; space_map_t *sm = &msp->ms_map; space_map_t *freed_map = &msp->ms_freemap[TXG_CLEAN(txg) & TXG_MASK]; space_map_t *defer_map = &msp->ms_defermap[txg % TXG_DEFER_SIZE]; metaslab_group_t *mg = msp->ms_group; vdev_t *vd = mg->mg_vd; int64_t alloc_delta, defer_delta; ASSERT(!vd->vdev_ishole); mutex_enter(&msp->ms_lock); /* * If this metaslab is just becoming available, initialize its * allocmaps and freemaps and add its capacity to the vdev. */ if (freed_map->sm_size == 0) { for (int t = 0; t < TXG_SIZE; t++) { space_map_create(&msp->ms_allocmap[t], sm->sm_start, sm->sm_size, sm->sm_shift, sm->sm_lock); space_map_create(&msp->ms_freemap[t], sm->sm_start, sm->sm_size, sm->sm_shift, sm->sm_lock); } for (int t = 0; t < TXG_DEFER_SIZE; t++) space_map_create(&msp->ms_defermap[t], sm->sm_start, sm->sm_size, sm->sm_shift, sm->sm_lock); vdev_space_update(vd, 0, 0, sm->sm_size); } alloc_delta = smosync->smo_alloc - smo->smo_alloc; defer_delta = freed_map->sm_space - defer_map->sm_space; vdev_space_update(vd, alloc_delta + defer_delta, defer_delta, 0); ASSERT(msp->ms_allocmap[txg & TXG_MASK].sm_space == 0); ASSERT(msp->ms_freemap[txg & TXG_MASK].sm_space == 0); /* * If there's a space_map_load() in progress, wait for it to complete * so that we have a consistent view of the in-core space map. * Then, add defer_map (oldest deferred frees) to this map and * transfer freed_map (this txg's frees) to defer_map. */ space_map_load_wait(sm); space_map_vacate(defer_map, sm->sm_loaded ? space_map_free : NULL, sm); space_map_vacate(freed_map, space_map_add, defer_map); *smo = *smosync; msp->ms_deferspace += defer_delta; ASSERT3S(msp->ms_deferspace, >=, 0); ASSERT3S(msp->ms_deferspace, <=, sm->sm_size); if (msp->ms_deferspace != 0) { /* * Keep syncing this metaslab until all deferred frees * are back in circulation. */ vdev_dirty(vd, VDD_METASLAB, msp, txg + 1); } /* * If the map is loaded but no longer active, evict it as soon as all * future allocations have synced. (If we unloaded it now and then * loaded a moment later, the map wouldn't reflect those allocations.) */ if (sm->sm_loaded && (msp->ms_weight & METASLAB_ACTIVE_MASK) == 0) { int evictable = 1; for (int t = 1; t < TXG_CONCURRENT_STATES; t++) if (msp->ms_allocmap[(txg + t) & TXG_MASK].sm_space) evictable = 0; if (evictable && !metaslab_debug) space_map_unload(sm); } metaslab_group_sort(mg, msp, metaslab_weight(msp)); mutex_exit(&msp->ms_lock); } void metaslab_sync_reassess(metaslab_group_t *mg) { vdev_t *vd = mg->mg_vd; int64_t failures = mg->mg_alloc_failures; /* * Re-evaluate all metaslabs which have lower offsets than the * bonus area. */ for (int m = 0; m < vd->vdev_ms_count; m++) { metaslab_t *msp = vd->vdev_ms[m]; if (msp->ms_map.sm_start > mg->mg_bonus_area) break; mutex_enter(&msp->ms_lock); metaslab_group_sort(mg, msp, metaslab_weight(msp)); mutex_exit(&msp->ms_lock); } atomic_add_64(&mg->mg_alloc_failures, -failures); /* * Prefetch the next potential metaslabs */ metaslab_prefetch(mg); } static uint64_t metaslab_distance(metaslab_t *msp, dva_t *dva) { uint64_t ms_shift = msp->ms_group->mg_vd->vdev_ms_shift; uint64_t offset = DVA_GET_OFFSET(dva) >> ms_shift; uint64_t start = msp->ms_map.sm_start >> ms_shift; if (msp->ms_group->mg_vd->vdev_id != DVA_GET_VDEV(dva)) return (1ULL << 63); if (offset < start) return ((start - offset) << ms_shift); if (offset > start) return ((offset - start) << ms_shift); return (0); } static uint64_t metaslab_group_alloc(metaslab_group_t *mg, uint64_t psize, uint64_t asize, uint64_t txg, uint64_t min_distance, dva_t *dva, int d, int flags) { spa_t *spa = mg->mg_vd->vdev_spa; metaslab_t *msp = NULL; uint64_t offset = -1ULL; avl_tree_t *t = &mg->mg_metaslab_tree; uint64_t activation_weight; uint64_t target_distance; int i; activation_weight = METASLAB_WEIGHT_PRIMARY; for (i = 0; i < d; i++) { if (DVA_GET_VDEV(&dva[i]) == mg->mg_vd->vdev_id) { activation_weight = METASLAB_WEIGHT_SECONDARY; break; } } for (;;) { boolean_t was_active; mutex_enter(&mg->mg_lock); for (msp = avl_first(t); msp; msp = AVL_NEXT(t, msp)) { if (msp->ms_weight < asize) { spa_dbgmsg(spa, "%s: failed to meet weight " "requirement: vdev %llu, txg %llu, mg %p, " "msp %p, psize %llu, asize %llu, " "failures %llu, weight %llu", spa_name(spa), mg->mg_vd->vdev_id, txg, mg, msp, psize, asize, mg->mg_alloc_failures, msp->ms_weight); mutex_exit(&mg->mg_lock); return (-1ULL); } was_active = msp->ms_weight & METASLAB_ACTIVE_MASK; if (activation_weight == METASLAB_WEIGHT_PRIMARY) break; target_distance = min_distance + (msp->ms_smo.smo_alloc ? 0 : min_distance >> 1); for (i = 0; i < d; i++) if (metaslab_distance(msp, &dva[i]) < target_distance) break; if (i == d) break; } mutex_exit(&mg->mg_lock); if (msp == NULL) return (-1ULL); /* * If we've already reached the allowable number of failed * allocation attempts on this metaslab group then we * consider skipping it. We skip it only if we're allowed * to "fast" gang, the physical size is larger than * a gang block, and we're attempting to allocate from * the primary metaslab. */ if (mg->mg_alloc_failures > zfs_mg_alloc_failures && CAN_FASTGANG(flags) && psize > SPA_GANGBLOCKSIZE && activation_weight == METASLAB_WEIGHT_PRIMARY) { spa_dbgmsg(spa, "%s: skipping metaslab group: " "vdev %llu, txg %llu, mg %p, psize %llu, " "asize %llu, failures %llu", spa_name(spa), mg->mg_vd->vdev_id, txg, mg, psize, asize, mg->mg_alloc_failures); return (-1ULL); } mutex_enter(&msp->ms_lock); /* * Ensure that the metaslab we have selected is still * capable of handling our request. It's possible that * another thread may have changed the weight while we * were blocked on the metaslab lock. */ if (msp->ms_weight < asize || (was_active && !(msp->ms_weight & METASLAB_ACTIVE_MASK) && activation_weight == METASLAB_WEIGHT_PRIMARY)) { mutex_exit(&msp->ms_lock); continue; } if ((msp->ms_weight & METASLAB_WEIGHT_SECONDARY) && activation_weight == METASLAB_WEIGHT_PRIMARY) { metaslab_passivate(msp, msp->ms_weight & ~METASLAB_ACTIVE_MASK); mutex_exit(&msp->ms_lock); continue; } if (metaslab_activate(msp, activation_weight) != 0) { mutex_exit(&msp->ms_lock); continue; } if ((offset = space_map_alloc(&msp->ms_map, asize)) != -1ULL) break; atomic_inc_64(&mg->mg_alloc_failures); metaslab_passivate(msp, space_map_maxsize(&msp->ms_map)); mutex_exit(&msp->ms_lock); } if (msp->ms_allocmap[txg & TXG_MASK].sm_space == 0) vdev_dirty(mg->mg_vd, VDD_METASLAB, msp, txg); space_map_add(&msp->ms_allocmap[txg & TXG_MASK], offset, asize); mutex_exit(&msp->ms_lock); return (offset); } /* * Allocate a block for the specified i/o. */ static int metaslab_alloc_dva(spa_t *spa, metaslab_class_t *mc, uint64_t psize, dva_t *dva, int d, dva_t *hintdva, uint64_t txg, int flags) { metaslab_group_t *mg, *rotor; vdev_t *vd; int dshift = 3; int all_zero; int zio_lock = B_FALSE; boolean_t allocatable; uint64_t offset = -1ULL; uint64_t asize; uint64_t distance; ASSERT(!DVA_IS_VALID(&dva[d])); /* * For testing, make some blocks above a certain size be gang blocks. */ if (psize >= metaslab_gang_bang && (ddi_get_lbolt() & 3) == 0) return (ENOSPC); /* * Start at the rotor and loop through all mgs until we find something. * Note that there's no locking on mc_rotor or mc_aliquot because * nothing actually breaks if we miss a few updates -- we just won't * allocate quite as evenly. It all balances out over time. * * If we are doing ditto or log blocks, try to spread them across * consecutive vdevs. If we're forced to reuse a vdev before we've * allocated all of our ditto blocks, then try and spread them out on * that vdev as much as possible. If it turns out to not be possible, * gradually lower our standards until anything becomes acceptable. * Also, allocating on consecutive vdevs (as opposed to random vdevs) * gives us hope of containing our fault domains to something we're * able to reason about. Otherwise, any two top-level vdev failures * will guarantee the loss of data. With consecutive allocation, * only two adjacent top-level vdev failures will result in data loss. * * If we are doing gang blocks (hintdva is non-NULL), try to keep * ourselves on the same vdev as our gang block header. That * way, we can hope for locality in vdev_cache, plus it makes our * fault domains something tractable. */ if (hintdva) { vd = vdev_lookup_top(spa, DVA_GET_VDEV(&hintdva[d])); /* * It's possible the vdev we're using as the hint no * longer exists (i.e. removed). Consult the rotor when * all else fails. */ if (vd != NULL) { mg = vd->vdev_mg; if (flags & METASLAB_HINTBP_AVOID && mg->mg_next != NULL) mg = mg->mg_next; } else { mg = mc->mc_rotor; } } else if (d != 0) { vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[d - 1])); mg = vd->vdev_mg->mg_next; } else { mg = mc->mc_rotor; } /* * If the hint put us into the wrong metaslab class, or into a * metaslab group that has been passivated, just follow the rotor. */ if (mg->mg_class != mc || mg->mg_activation_count <= 0) mg = mc->mc_rotor; rotor = mg; top: all_zero = B_TRUE; do { ASSERT(mg->mg_activation_count == 1); vd = mg->mg_vd; /* * Don't allocate from faulted devices. */ if (zio_lock) { spa_config_enter(spa, SCL_ZIO, FTAG, RW_READER); allocatable = vdev_allocatable(vd); spa_config_exit(spa, SCL_ZIO, FTAG); } else { allocatable = vdev_allocatable(vd); } if (!allocatable) goto next; /* * Avoid writing single-copy data to a failing vdev */ if ((vd->vdev_stat.vs_write_errors > 0 || vd->vdev_state < VDEV_STATE_HEALTHY) && d == 0 && dshift == 3) { all_zero = B_FALSE; goto next; } ASSERT(mg->mg_class == mc); distance = vd->vdev_asize >> dshift; if (distance <= (1ULL << vd->vdev_ms_shift)) distance = 0; else all_zero = B_FALSE; asize = vdev_psize_to_asize(vd, psize); ASSERT(P2PHASE(asize, 1ULL << vd->vdev_ashift) == 0); offset = metaslab_group_alloc(mg, psize, asize, txg, distance, dva, d, flags); if (offset != -1ULL) { /* * If we've just selected this metaslab group, * figure out whether the corresponding vdev is * over- or under-used relative to the pool, * and set an allocation bias to even it out. */ if (mc->mc_aliquot == 0) { vdev_stat_t *vs = &vd->vdev_stat; int64_t vu, cu; vu = (vs->vs_alloc * 100) / (vs->vs_space + 1); cu = (mc->mc_alloc * 100) / (mc->mc_space + 1); /* * Calculate how much more or less we should * try to allocate from this device during * this iteration around the rotor. * For example, if a device is 80% full * and the pool is 20% full then we should * reduce allocations by 60% on this device. * * mg_bias = (20 - 80) * 512K / 100 = -307K * * This reduces allocations by 307K for this * iteration. */ mg->mg_bias = ((cu - vu) * (int64_t)mg->mg_aliquot) / 100; } if (atomic_add_64_nv(&mc->mc_aliquot, asize) >= mg->mg_aliquot + mg->mg_bias) { mc->mc_rotor = mg->mg_next; mc->mc_aliquot = 0; } DVA_SET_VDEV(&dva[d], vd->vdev_id); DVA_SET_OFFSET(&dva[d], offset); DVA_SET_GANG(&dva[d], !!(flags & METASLAB_GANG_HEADER)); DVA_SET_ASIZE(&dva[d], asize); return (0); } next: mc->mc_rotor = mg->mg_next; mc->mc_aliquot = 0; } while ((mg = mg->mg_next) != rotor); if (!all_zero) { dshift++; ASSERT(dshift < 64); goto top; } if (!allocatable && !zio_lock) { dshift = 3; zio_lock = B_TRUE; goto top; } bzero(&dva[d], sizeof (dva_t)); return (ENOSPC); } /* * Free the block represented by DVA in the context of the specified * transaction group. */ static void metaslab_free_dva(spa_t *spa, const dva_t *dva, uint64_t txg, boolean_t now) { uint64_t vdev = DVA_GET_VDEV(dva); uint64_t offset = DVA_GET_OFFSET(dva); uint64_t size = DVA_GET_ASIZE(dva); vdev_t *vd; metaslab_t *msp; ASSERT(DVA_IS_VALID(dva)); if (txg > spa_freeze_txg(spa)) return; if ((vd = vdev_lookup_top(spa, vdev)) == NULL || (offset >> vd->vdev_ms_shift) >= vd->vdev_ms_count) { cmn_err(CE_WARN, "metaslab_free_dva(): bad DVA %llu:%llu", (u_longlong_t)vdev, (u_longlong_t)offset); ASSERT(0); return; } msp = vd->vdev_ms[offset >> vd->vdev_ms_shift]; if (DVA_GET_GANG(dva)) size = vdev_psize_to_asize(vd, SPA_GANGBLOCKSIZE); mutex_enter(&msp->ms_lock); if (now) { space_map_remove(&msp->ms_allocmap[txg & TXG_MASK], offset, size); space_map_free(&msp->ms_map, offset, size); } else { if (msp->ms_freemap[txg & TXG_MASK].sm_space == 0) vdev_dirty(vd, VDD_METASLAB, msp, txg); space_map_add(&msp->ms_freemap[txg & TXG_MASK], offset, size); } mutex_exit(&msp->ms_lock); } /* * Intent log support: upon opening the pool after a crash, notify the SPA * of blocks that the intent log has allocated for immediate write, but * which are still considered free by the SPA because the last transaction * group didn't commit yet. */ static int metaslab_claim_dva(spa_t *spa, const dva_t *dva, uint64_t txg) { uint64_t vdev = DVA_GET_VDEV(dva); uint64_t offset = DVA_GET_OFFSET(dva); uint64_t size = DVA_GET_ASIZE(dva); vdev_t *vd; metaslab_t *msp; int error = 0; ASSERT(DVA_IS_VALID(dva)); if ((vd = vdev_lookup_top(spa, vdev)) == NULL || (offset >> vd->vdev_ms_shift) >= vd->vdev_ms_count) return (ENXIO); msp = vd->vdev_ms[offset >> vd->vdev_ms_shift]; if (DVA_GET_GANG(dva)) size = vdev_psize_to_asize(vd, SPA_GANGBLOCKSIZE); mutex_enter(&msp->ms_lock); if ((txg != 0 && spa_writeable(spa)) || !msp->ms_map.sm_loaded) error = metaslab_activate(msp, METASLAB_WEIGHT_SECONDARY); if (error == 0 && !space_map_contains(&msp->ms_map, offset, size)) error = ENOENT; if (error || txg == 0) { /* txg == 0 indicates dry run */ mutex_exit(&msp->ms_lock); return (error); } space_map_claim(&msp->ms_map, offset, size); if (spa_writeable(spa)) { /* don't dirty if we're zdb(1M) */ if (msp->ms_allocmap[txg & TXG_MASK].sm_space == 0) vdev_dirty(vd, VDD_METASLAB, msp, txg); space_map_add(&msp->ms_allocmap[txg & TXG_MASK], offset, size); } mutex_exit(&msp->ms_lock); return (0); } int metaslab_alloc(spa_t *spa, metaslab_class_t *mc, uint64_t psize, blkptr_t *bp, int ndvas, uint64_t txg, blkptr_t *hintbp, int flags) { dva_t *dva = bp->blk_dva; dva_t *hintdva = hintbp->blk_dva; int error = 0; ASSERT(bp->blk_birth == 0); ASSERT(BP_PHYSICAL_BIRTH(bp) == 0); spa_config_enter(spa, SCL_ALLOC, FTAG, RW_READER); if (mc->mc_rotor == NULL) { /* no vdevs in this class */ spa_config_exit(spa, SCL_ALLOC, FTAG); return (ENOSPC); } ASSERT(ndvas > 0 && ndvas <= spa_max_replication(spa)); ASSERT(BP_GET_NDVAS(bp) == 0); ASSERT(hintbp == NULL || ndvas <= BP_GET_NDVAS(hintbp)); for (int d = 0; d < ndvas; d++) { error = metaslab_alloc_dva(spa, mc, psize, dva, d, hintdva, txg, flags); if (error) { for (d--; d >= 0; d--) { metaslab_free_dva(spa, &dva[d], txg, B_TRUE); bzero(&dva[d], sizeof (dva_t)); } spa_config_exit(spa, SCL_ALLOC, FTAG); return (error); } } ASSERT(error == 0); ASSERT(BP_GET_NDVAS(bp) == ndvas); spa_config_exit(spa, SCL_ALLOC, FTAG); BP_SET_BIRTH(bp, txg, txg); return (0); } void metaslab_free(spa_t *spa, const blkptr_t *bp, uint64_t txg, boolean_t now) { const dva_t *dva = bp->blk_dva; int ndvas = BP_GET_NDVAS(bp); ASSERT(!BP_IS_HOLE(bp)); ASSERT(!now || bp->blk_birth >= spa_syncing_txg(spa)); spa_config_enter(spa, SCL_FREE, FTAG, RW_READER); for (int d = 0; d < ndvas; d++) metaslab_free_dva(spa, &dva[d], txg, now); spa_config_exit(spa, SCL_FREE, FTAG); } int metaslab_claim(spa_t *spa, const blkptr_t *bp, uint64_t txg) { const dva_t *dva = bp->blk_dva; int ndvas = BP_GET_NDVAS(bp); int error = 0; ASSERT(!BP_IS_HOLE(bp)); if (txg != 0) { /* * First do a dry run to make sure all DVAs are claimable, * so we don't have to unwind from partial failures below. */ if ((error = metaslab_claim(spa, bp, 0)) != 0) return (error); } spa_config_enter(spa, SCL_ALLOC, FTAG, RW_READER); for (int d = 0; d < ndvas; d++) if ((error = metaslab_claim_dva(spa, &dva[d], txg)) != 0) break; spa_config_exit(spa, SCL_ALLOC, FTAG); ASSERT(error == 0 || txg == 0); return (error); }