/* * 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) 2013 by Delphix. All rights reserved. * Copyright (c) 2013 by Saso Kiselkov. All rights reserved. */ #include #include #include #include #include #include #include #include SYSCTL_DECL(_vfs_zfs); SYSCTL_NODE(_vfs_zfs, OID_AUTO, metaslab, CTLFLAG_RW, 0, "ZFS metaslab"); /* * 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))) #define METASLAB_WEIGHT_PRIMARY (1ULL << 63) #define METASLAB_WEIGHT_SECONDARY (1ULL << 62) #define METASLAB_ACTIVE_MASK \ (METASLAB_WEIGHT_PRIMARY | METASLAB_WEIGHT_SECONDARY) uint64_t metaslab_aliquot = 512ULL << 10; uint64_t metaslab_gang_bang = SPA_MAXBLOCKSIZE + 1; /* force gang blocks */ TUNABLE_QUAD("vfs.zfs.metaslab.gang_bang", &metaslab_gang_bang); SYSCTL_QUAD(_vfs_zfs_metaslab, OID_AUTO, gang_bang, CTLFLAG_RWTUN, &metaslab_gang_bang, 0, "Force gang block allocation for blocks larger than or equal to this value"); /* * The in-core space map representation is more compact than its on-disk form. * The zfs_condense_pct determines how much more compact the in-core * space_map representation must be before we compact it on-disk. * Values should be greater than or equal to 100. */ int zfs_condense_pct = 200; TUNABLE_INT("vfs.zfs.condense_pct", &zfs_condense_pct); SYSCTL_INT(_vfs_zfs, OID_AUTO, condense_pct, CTLFLAG_RWTUN, &zfs_condense_pct, 0, "Condense on-disk spacemap when it is more than this many percents" " of in-memory counterpart"); /* * 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. The value of zfs_mg_alloc_failures is computed * in zio_init() unless it has been overridden in /etc/system. */ int zfs_mg_alloc_failures = 0; TUNABLE_INT("vfs.zfs.mg_alloc_failures", &zfs_mg_alloc_failures); SYSCTL_INT(_vfs_zfs, OID_AUTO, mg_alloc_failures, CTLFLAG_RWTUN, &zfs_mg_alloc_failures, 0, "Number of allowed allocation failures per vdev"); /* * The zfs_mg_noalloc_threshold defines which metaslab groups should * be eligible for allocation. The value is defined as a percentage of * a free space. Metaslab groups that have more free space than * zfs_mg_noalloc_threshold are always eligible for allocations. Once * a metaslab group's free space is less than or equal to the * zfs_mg_noalloc_threshold the allocator will avoid allocating to that * group unless all groups in the pool have reached zfs_mg_noalloc_threshold. * Once all groups in the pool reach zfs_mg_noalloc_threshold then all * groups are allowed to accept allocations. Gang blocks are always * eligible to allocate on any metaslab group. The default value of 0 means * no metaslab group will be excluded based on this criterion. */ int zfs_mg_noalloc_threshold = 0; TUNABLE_INT("vfs.zfs.mg_noalloc_threshold", &zfs_mg_noalloc_threshold); SYSCTL_INT(_vfs_zfs, OID_AUTO, mg_noalloc_threshold, CTLFLAG_RWTUN, &zfs_mg_noalloc_threshold, 0, "Percentage of metaslab group size that should be free" " to make it eligible for allocation"); /* * When set will load all metaslabs when pool is first opened. */ int metaslab_debug_load = 0; TUNABLE_INT("vfs.zfs.metaslab.debug_load", &metaslab_debug_load); SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, debug_load, CTLFLAG_RWTUN, &metaslab_debug_load, 0, "Load all metaslabs when pool is first opened"); /* * When set will prevent metaslabs from being unloaded. */ int metaslab_debug_unload = 0; TUNABLE_INT("vfs.zfs.metaslab.debug_unload", &metaslab_debug_unload); SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, debug_unload, CTLFLAG_RWTUN, &metaslab_debug_unload, 0, "Prevent metaslabs from being unloaded"); /* * 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; TUNABLE_QUAD("vfs.zfs.metaslab.df_alloc_threshold", &metaslab_df_alloc_threshold); SYSCTL_QUAD(_vfs_zfs_metaslab, OID_AUTO, df_alloc_threshold, CTLFLAG_RWTUN, &metaslab_df_alloc_threshold, 0, "Minimum size which forces the dynamic allocator to change it's allocation strategy"); /* * 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; TUNABLE_INT("vfs.zfs.metaslab.df_free_pct", &metaslab_df_free_pct); SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, df_free_pct, CTLFLAG_RWTUN, &metaslab_df_free_pct, 0, "The minimum free space, in percent, which must be available in a space map to continue allocations in a first-fit fashion"); /* * 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; TUNABLE_QUAD("vfs.zfs.metaslab.min_alloc_size", &metaslab_min_alloc_size); SYSCTL_QUAD(_vfs_zfs_metaslab, OID_AUTO, min_alloc_size, CTLFLAG_RWTUN, &metaslab_min_alloc_size, 0, "A metaslab is considered \"free\" if it contains a contiguous segment which is greater than vfs.zfs.metaslab.min_alloc_size"); /* * Percentage of all cpus that can be used by the metaslab taskq. */ int metaslab_load_pct = 50; TUNABLE_INT("vfs.zfs.metaslab.load_pct", &metaslab_load_pct); SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, load_pct, CTLFLAG_RWTUN, &metaslab_load_pct, 0, "Percentage of cpus that can be used by the metaslab taskq"); /* * Determines how many txgs a metaslab may remain loaded without having any * allocations from it. As long as a metaslab continues to be used we will * keep it loaded. */ int metaslab_unload_delay = TXG_SIZE * 2; TUNABLE_INT("vfs.zfs.metaslab.unload_delay", &metaslab_unload_delay); SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, unload_delay, CTLFLAG_RWTUN, &metaslab_unload_delay, 0, "Number of TXGs that an unused metaslab can be kept in memory"); /* * Should we be willing to write data to degraded vdevs? */ boolean_t zfs_write_to_degraded = B_FALSE; SYSCTL_INT(_vfs_zfs, OID_AUTO, write_to_degraded, CTLFLAG_RW, &zfs_write_to_degraded, 0, "Allow writing data to degraded vdevs"); TUNABLE_INT("vfs.zfs.write_to_degraded", &zfs_write_to_degraded); /* * Max number of metaslabs per group to preload. */ int metaslab_preload_limit = SPA_DVAS_PER_BP; TUNABLE_INT("vfs.zfs.metaslab.preload_limit", &metaslab_preload_limit); SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, preload_limit, CTLFLAG_RWTUN, &metaslab_preload_limit, 0, "Max number of metaslabs per group to preload"); /* * Enable/disable preloading of metaslab. */ boolean_t metaslab_preload_enabled = B_TRUE; TUNABLE_INT("vfs.zfs.metaslab.preload_enabled", &metaslab_preload_enabled); SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, preload_enabled, CTLFLAG_RWTUN, &metaslab_preload_enabled, 0, "Max number of metaslabs per group to preload"); /* * Enable/disable additional weight factor for each metaslab. */ boolean_t metaslab_weight_factor_enable = B_FALSE; TUNABLE_INT("vfs.zfs.metaslab.weight_factor_enable", &metaslab_weight_factor_enable); SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, weight_factor_enable, CTLFLAG_RWTUN, &metaslab_weight_factor_enable, 0, "Enable additional weight factor for each metaslab"); /* * ========================================================================== * Metaslab classes * ========================================================================== */ metaslab_class_t * metaslab_class_create(spa_t *spa, metaslab_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); } void metaslab_class_minblocksize_update(metaslab_class_t *mc) { metaslab_group_t *mg; vdev_t *vd; uint64_t minashift = UINT64_MAX; if ((mg = mc->mc_rotor) == NULL) { mc->mc_minblocksize = SPA_MINBLOCKSIZE; return; } do { vd = mg->mg_vd; if (vd->vdev_ashift < minashift) minashift = vd->vdev_ashift; } while ((mg = mg->mg_next) != mc->mc_rotor); mc->mc_minblocksize = 1ULL << minashift; } 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); } uint64_t metaslab_class_get_minblocksize(metaslab_class_t *mc) { return (mc->mc_minblocksize); } /* * ========================================================================== * 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_start < m2->ms_start) return (-1); if (m1->ms_start > m2->ms_start) return (1); ASSERT3P(m1, ==, m2); return (0); } /* * Update the allocatable flag and the metaslab group's capacity. * The allocatable flag is set to true if the capacity is below * the zfs_mg_noalloc_threshold. If a metaslab group transitions * from allocatable to non-allocatable or vice versa then the metaslab * group's class is updated to reflect the transition. */ static void metaslab_group_alloc_update(metaslab_group_t *mg) { vdev_t *vd = mg->mg_vd; metaslab_class_t *mc = mg->mg_class; vdev_stat_t *vs = &vd->vdev_stat; boolean_t was_allocatable; ASSERT(vd == vd->vdev_top); mutex_enter(&mg->mg_lock); was_allocatable = mg->mg_allocatable; mg->mg_free_capacity = ((vs->vs_space - vs->vs_alloc) * 100) / (vs->vs_space + 1); mg->mg_allocatable = (mg->mg_free_capacity > zfs_mg_noalloc_threshold); /* * The mc_alloc_groups maintains a count of the number of * groups in this metaslab class that are still above the * zfs_mg_noalloc_threshold. This is used by the allocating * threads to determine if they should avoid allocations to * a given group. The allocator will avoid allocations to a group * if that group has reached or is below the zfs_mg_noalloc_threshold * and there are still other groups that are above the threshold. * When a group transitions from allocatable to non-allocatable or * vice versa we update the metaslab class to reflect that change. * When the mc_alloc_groups value drops to 0 that means that all * groups have reached the zfs_mg_noalloc_threshold making all groups * eligible for allocations. This effectively means that all devices * are balanced again. */ if (was_allocatable && !mg->mg_allocatable) mc->mc_alloc_groups--; else if (!was_allocatable && mg->mg_allocatable) mc->mc_alloc_groups++; mutex_exit(&mg->mg_lock); } 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; mg->mg_taskq = taskq_create("metaslab_group_tasksq", metaslab_load_pct, minclsyspri, 10, INT_MAX, TASKQ_THREADS_CPU_PCT); 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); metaslab_group_alloc_update(mg); 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; metaslab_class_minblocksize_update(mc); } 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; } taskq_wait(mg->mg_taskq); 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; metaslab_class_minblocksize_update(mc); } 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); } /* * Determine if a given metaslab group should skip allocations. A metaslab * group should avoid allocations if its used capacity has crossed the * zfs_mg_noalloc_threshold and there is at least one metaslab group * that can still handle allocations. */ static boolean_t metaslab_group_allocatable(metaslab_group_t *mg) { vdev_t *vd = mg->mg_vd; spa_t *spa = vd->vdev_spa; metaslab_class_t *mc = mg->mg_class; /* * A metaslab group is considered allocatable if its free capacity * is greater than the set value of zfs_mg_noalloc_threshold, it's * associated with a slog, or there are no other metaslab groups * with free capacity greater than zfs_mg_noalloc_threshold. */ return (mg->mg_free_capacity > zfs_mg_noalloc_threshold || mc != spa_normal_class(spa) || mc->mc_alloc_groups == 0); } /* * ========================================================================== * Range tree callbacks * ========================================================================== */ /* * Comparison function for the private size-ordered tree. Tree is sorted * by size, larger sizes at the end of the tree. */ static int metaslab_rangesize_compare(const void *x1, const void *x2) { const range_seg_t *r1 = x1; const range_seg_t *r2 = x2; uint64_t rs_size1 = r1->rs_end - r1->rs_start; uint64_t rs_size2 = r2->rs_end - r2->rs_start; if (rs_size1 < rs_size2) return (-1); if (rs_size1 > rs_size2) return (1); if (r1->rs_start < r2->rs_start) return (-1); if (r1->rs_start > r2->rs_start) return (1); return (0); } /* * Create any block allocator specific components. The current allocators * rely on using both a size-ordered range_tree_t and an array of uint64_t's. */ static void metaslab_rt_create(range_tree_t *rt, void *arg) { metaslab_t *msp = arg; ASSERT3P(rt->rt_arg, ==, msp); ASSERT(msp->ms_tree == NULL); avl_create(&msp->ms_size_tree, metaslab_rangesize_compare, sizeof (range_seg_t), offsetof(range_seg_t, rs_pp_node)); } /* * Destroy the block allocator specific components. */ static void metaslab_rt_destroy(range_tree_t *rt, void *arg) { metaslab_t *msp = arg; ASSERT3P(rt->rt_arg, ==, msp); ASSERT3P(msp->ms_tree, ==, rt); ASSERT0(avl_numnodes(&msp->ms_size_tree)); avl_destroy(&msp->ms_size_tree); } static void metaslab_rt_add(range_tree_t *rt, range_seg_t *rs, void *arg) { metaslab_t *msp = arg; ASSERT3P(rt->rt_arg, ==, msp); ASSERT3P(msp->ms_tree, ==, rt); VERIFY(!msp->ms_condensing); avl_add(&msp->ms_size_tree, rs); } static void metaslab_rt_remove(range_tree_t *rt, range_seg_t *rs, void *arg) { metaslab_t *msp = arg; ASSERT3P(rt->rt_arg, ==, msp); ASSERT3P(msp->ms_tree, ==, rt); VERIFY(!msp->ms_condensing); avl_remove(&msp->ms_size_tree, rs); } static void metaslab_rt_vacate(range_tree_t *rt, void *arg) { metaslab_t *msp = arg; ASSERT3P(rt->rt_arg, ==, msp); ASSERT3P(msp->ms_tree, ==, rt); /* * Normally one would walk the tree freeing nodes along the way. * Since the nodes are shared with the range trees we can avoid * walking all nodes and just reinitialize the avl tree. The nodes * will be freed by the range tree, so we don't want to free them here. */ avl_create(&msp->ms_size_tree, metaslab_rangesize_compare, sizeof (range_seg_t), offsetof(range_seg_t, rs_pp_node)); } static range_tree_ops_t metaslab_rt_ops = { metaslab_rt_create, metaslab_rt_destroy, metaslab_rt_add, metaslab_rt_remove, metaslab_rt_vacate }; /* * ========================================================================== * Metaslab block operations * ========================================================================== */ /* * Return the maximum contiguous segment within the metaslab. */ uint64_t metaslab_block_maxsize(metaslab_t *msp) { avl_tree_t *t = &msp->ms_size_tree; range_seg_t *rs; if (t == NULL || (rs = avl_last(t)) == NULL) return (0ULL); return (rs->rs_end - rs->rs_start); } uint64_t metaslab_block_alloc(metaslab_t *msp, uint64_t size) { uint64_t start; range_tree_t *rt = msp->ms_tree; VERIFY(!msp->ms_condensing); start = msp->ms_ops->msop_alloc(msp, size); if (start != -1ULL) { vdev_t *vd = msp->ms_group->mg_vd; VERIFY0(P2PHASE(start, 1ULL << vd->vdev_ashift)); VERIFY0(P2PHASE(size, 1ULL << vd->vdev_ashift)); VERIFY3U(range_tree_space(rt) - size, <=, msp->ms_size); range_tree_remove(rt, start, size); } return (start); } /* * ========================================================================== * Common allocator routines * ========================================================================== */ /* * 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) { range_seg_t *rs, rsearch; avl_index_t where; rsearch.rs_start = *cursor; rsearch.rs_end = *cursor + size; rs = avl_find(t, &rsearch, &where); if (rs == NULL) rs = avl_nearest(t, where, AVL_AFTER); while (rs != NULL) { uint64_t offset = P2ROUNDUP(rs->rs_start, align); if (offset + size <= rs->rs_end) { *cursor = offset + size; return (offset); } rs = AVL_NEXT(t, rs); } /* * 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)); } /* * ========================================================================== * The first-fit block allocator * ========================================================================== */ static uint64_t metaslab_ff_alloc(metaslab_t *msp, uint64_t size) { /* * Find the largest power of 2 block size that evenly divides the * requested size. This is used to try to allocate blocks with similar * alignment from the same area of the metaslab (i.e. same cursor * bucket) but it does not guarantee that other allocations sizes * may exist in the same region. */ uint64_t align = size & -size; uint64_t *cursor = &msp->ms_lbas[highbit(align) - 1]; avl_tree_t *t = &msp->ms_tree->rt_root; return (metaslab_block_picker(t, cursor, size, align)); } /* ARGSUSED */ static boolean_t metaslab_ff_fragmented(metaslab_t *msp) { return (B_TRUE); } static metaslab_ops_t metaslab_ff_ops = { metaslab_ff_alloc, 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(metaslab_t *msp, uint64_t size) { /* * Find the largest power of 2 block size that evenly divides the * requested size. This is used to try to allocate blocks with similar * alignment from the same area of the metaslab (i.e. same cursor * bucket) but it does not guarantee that other allocations sizes * may exist in the same region. */ uint64_t align = size & -size; uint64_t *cursor = &msp->ms_lbas[highbit(align) - 1]; range_tree_t *rt = msp->ms_tree; avl_tree_t *t = &rt->rt_root; uint64_t max_size = metaslab_block_maxsize(msp); int free_pct = range_tree_space(rt) * 100 / msp->ms_size; ASSERT(MUTEX_HELD(&msp->ms_lock)); ASSERT3U(avl_numnodes(t), ==, avl_numnodes(&msp->ms_size_tree)); 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 = &msp->ms_size_tree; *cursor = 0; } return (metaslab_block_picker(t, cursor, size, 1ULL)); } static boolean_t metaslab_df_fragmented(metaslab_t *msp) { range_tree_t *rt = msp->ms_tree; uint64_t max_size = metaslab_block_maxsize(msp); int free_pct = range_tree_space(rt) * 100 / msp->ms_size; if (max_size >= metaslab_df_alloc_threshold && free_pct >= metaslab_df_free_pct) return (B_FALSE); return (B_TRUE); } static metaslab_ops_t metaslab_df_ops = { metaslab_df_alloc, metaslab_df_fragmented }; /* * ========================================================================== * Cursor fit block allocator - * Select the largest region in the metaslab, set the cursor to the beginning * of the range and the cursor_end to the end of the range. As allocations * are made advance the cursor. Continue allocating from the cursor until * the range is exhausted and then find a new range. * ========================================================================== */ static uint64_t metaslab_cf_alloc(metaslab_t *msp, uint64_t size) { range_tree_t *rt = msp->ms_tree; avl_tree_t *t = &msp->ms_size_tree; uint64_t *cursor = &msp->ms_lbas[0]; uint64_t *cursor_end = &msp->ms_lbas[1]; uint64_t offset = 0; ASSERT(MUTEX_HELD(&msp->ms_lock)); ASSERT3U(avl_numnodes(t), ==, avl_numnodes(&rt->rt_root)); ASSERT3U(*cursor_end, >=, *cursor); if ((*cursor + size) > *cursor_end) { range_seg_t *rs; rs = avl_last(&msp->ms_size_tree); if (rs == NULL || (rs->rs_end - rs->rs_start) < size) return (-1ULL); *cursor = rs->rs_start; *cursor_end = rs->rs_end; } offset = *cursor; *cursor += size; return (offset); } static boolean_t metaslab_cf_fragmented(metaslab_t *msp) { return (metaslab_block_maxsize(msp) < metaslab_min_alloc_size); } static metaslab_ops_t metaslab_cf_ops = { metaslab_cf_alloc, metaslab_cf_fragmented }; /* * ========================================================================== * New dynamic fit allocator - * Select a region that is large enough to allocate 2^metaslab_ndf_clump_shift * contiguous blocks. If no region is found then just use the largest segment * that remains. * ========================================================================== */ /* * Determines desired number of contiguous blocks (2^metaslab_ndf_clump_shift) * to request from the allocator. */ uint64_t metaslab_ndf_clump_shift = 4; static uint64_t metaslab_ndf_alloc(metaslab_t *msp, uint64_t size) { avl_tree_t *t = &msp->ms_tree->rt_root; avl_index_t where; range_seg_t *rs, rsearch; uint64_t hbit = highbit(size); uint64_t *cursor = &msp->ms_lbas[hbit - 1]; uint64_t max_size = metaslab_block_maxsize(msp); ASSERT(MUTEX_HELD(&msp->ms_lock)); ASSERT3U(avl_numnodes(t), ==, avl_numnodes(&msp->ms_size_tree)); if (max_size < size) return (-1ULL); rsearch.rs_start = *cursor; rsearch.rs_end = *cursor + size; rs = avl_find(t, &rsearch, &where); if (rs == NULL || (rs->rs_end - rs->rs_start) < size) { t = &msp->ms_size_tree; rsearch.rs_start = 0; rsearch.rs_end = MIN(max_size, 1ULL << (hbit + metaslab_ndf_clump_shift)); rs = avl_find(t, &rsearch, &where); if (rs == NULL) rs = avl_nearest(t, where, AVL_AFTER); ASSERT(rs != NULL); } if ((rs->rs_end - rs->rs_start) >= size) { *cursor = rs->rs_start + size; return (rs->rs_start); } return (-1ULL); } static boolean_t metaslab_ndf_fragmented(metaslab_t *msp) { return (metaslab_block_maxsize(msp) <= (metaslab_min_alloc_size << metaslab_ndf_clump_shift)); } static metaslab_ops_t metaslab_ndf_ops = { metaslab_ndf_alloc, metaslab_ndf_fragmented }; metaslab_ops_t *zfs_metaslab_ops = &metaslab_df_ops; /* * ========================================================================== * Metaslabs * ========================================================================== */ /* * Wait for any in-progress metaslab loads to complete. */ void metaslab_load_wait(metaslab_t *msp) { ASSERT(MUTEX_HELD(&msp->ms_lock)); while (msp->ms_loading) { ASSERT(!msp->ms_loaded); cv_wait(&msp->ms_load_cv, &msp->ms_lock); } } int metaslab_load(metaslab_t *msp) { int error = 0; ASSERT(MUTEX_HELD(&msp->ms_lock)); ASSERT(!msp->ms_loaded); ASSERT(!msp->ms_loading); msp->ms_loading = B_TRUE; /* * If the space map has not been allocated yet, then treat * all the space in the metaslab as free and add it to the * ms_tree. */ if (msp->ms_sm != NULL) error = space_map_load(msp->ms_sm, msp->ms_tree, SM_FREE); else range_tree_add(msp->ms_tree, msp->ms_start, msp->ms_size); msp->ms_loaded = (error == 0); msp->ms_loading = B_FALSE; if (msp->ms_loaded) { for (int t = 0; t < TXG_DEFER_SIZE; t++) { range_tree_walk(msp->ms_defertree[t], range_tree_remove, msp->ms_tree); } } cv_broadcast(&msp->ms_load_cv); return (error); } void metaslab_unload(metaslab_t *msp) { ASSERT(MUTEX_HELD(&msp->ms_lock)); range_tree_vacate(msp->ms_tree, NULL, NULL); msp->ms_loaded = B_FALSE; msp->ms_weight &= ~METASLAB_ACTIVE_MASK; } metaslab_t * metaslab_init(metaslab_group_t *mg, uint64_t id, uint64_t object, uint64_t txg) { vdev_t *vd = mg->mg_vd; objset_t *mos = vd->vdev_spa->spa_meta_objset; metaslab_t *msp; msp = kmem_zalloc(sizeof (metaslab_t), KM_SLEEP); mutex_init(&msp->ms_lock, NULL, MUTEX_DEFAULT, NULL); cv_init(&msp->ms_load_cv, NULL, CV_DEFAULT, NULL); msp->ms_id = id; msp->ms_start = id << vd->vdev_ms_shift; msp->ms_size = 1ULL << vd->vdev_ms_shift; /* * We only open space map objects that already exist. All others * will be opened when we finally allocate an object for it. */ if (object != 0) { VERIFY0(space_map_open(&msp->ms_sm, mos, object, msp->ms_start, msp->ms_size, vd->vdev_ashift, &msp->ms_lock)); ASSERT(msp->ms_sm != NULL); } /* * We create the main range tree here, but we don't create the * alloctree and freetree 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. */ msp->ms_tree = range_tree_create(&metaslab_rt_ops, msp, &msp->ms_lock); metaslab_group_add(mg, msp); msp->ms_ops = mg->mg_class->mc_ops; /* * 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 metaslab_debug_load is set and we're initializing a metaslab * that has an allocated space_map object then load the its space * map so that can verify frees. */ if (metaslab_debug_load && msp->ms_sm != NULL) { mutex_enter(&msp->ms_lock); VERIFY0(metaslab_load(msp)); mutex_exit(&msp->ms_lock); } 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; metaslab_group_remove(mg, msp); mutex_enter(&msp->ms_lock); VERIFY(msp->ms_group == NULL); vdev_space_update(mg->mg_vd, -space_map_allocated(msp->ms_sm), 0, -msp->ms_size); space_map_close(msp->ms_sm); metaslab_unload(msp); range_tree_destroy(msp->ms_tree); for (int t = 0; t < TXG_SIZE; t++) { range_tree_destroy(msp->ms_alloctree[t]); range_tree_destroy(msp->ms_freetree[t]); } for (int t = 0; t < TXG_DEFER_SIZE; t++) { range_tree_destroy(msp->ms_defertree[t]); } ASSERT0(msp->ms_deferspace); mutex_exit(&msp->ms_lock); cv_destroy(&msp->ms_load_cv); mutex_destroy(&msp->ms_lock); kmem_free(msp, sizeof (metaslab_t)); } /* * Apply a weighting factor based on the histogram information for this * metaslab. The current weighting factor is somewhat arbitrary and requires * additional investigation. The implementation provides a measure of * "weighted" free space and gives a higher weighting for larger contiguous * regions. The weighting factor is determined by counting the number of * sm_shift sectors that exist in each region represented by the histogram. * That value is then multiplied by the power of 2 exponent and the sm_shift * value. * * For example, assume the 2^21 histogram bucket has 4 2MB regions and the * metaslab has an sm_shift value of 9 (512B): * * 1) calculate the number of sm_shift sectors in the region: * 2^21 / 2^9 = 2^12 = 4096 * 4 (number of regions) = 16384 * 2) multiply by the power of 2 exponent and the sm_shift value: * 16384 * 21 * 9 = 3096576 * This value will be added to the weighting of the metaslab. */ static uint64_t metaslab_weight_factor(metaslab_t *msp) { uint64_t factor = 0; uint64_t sectors; int i; /* * A null space map means that the entire metaslab is free, * calculate a weight factor that spans the entire size of the * metaslab. */ if (msp->ms_sm == NULL) { vdev_t *vd = msp->ms_group->mg_vd; i = highbit(msp->ms_size) - 1; sectors = msp->ms_size >> vd->vdev_ashift; return (sectors * i * vd->vdev_ashift); } if (msp->ms_sm->sm_dbuf->db_size != sizeof (space_map_phys_t)) return (0); for (i = 0; i < SPACE_MAP_HISTOGRAM_SIZE(msp->ms_sm); i++) { if (msp->ms_sm->sm_phys->smp_histogram[i] == 0) continue; /* * Determine the number of sm_shift sectors in the region * indicated by the histogram. For example, given an * sm_shift value of 9 (512 bytes) and i = 4 then we know * that we're looking at an 8K region in the histogram * (i.e. 9 + 4 = 13, 2^13 = 8192). To figure out the * number of sm_shift sectors (512 bytes in this example), * we would take 8192 / 512 = 16. Since the histogram * is offset by sm_shift we can simply use the value of * of i to calculate this (i.e. 2^i = 16 where i = 4). */ sectors = msp->ms_sm->sm_phys->smp_histogram[i] << i; factor += (i + msp->ms_sm->sm_shift) * sectors; } return (factor * msp->ms_sm->sm_shift); } static uint64_t metaslab_weight(metaslab_t *msp) { metaslab_group_t *mg = msp->ms_group; vdev_t *vd = mg->mg_vd; uint64_t weight, space; ASSERT(MUTEX_HELD(&msp->ms_lock)); /* * This vdev is in the process of being removed so there is nothing * for us to do here. */ if (vd->vdev_removing) { ASSERT0(space_map_allocated(msp->ms_sm)); ASSERT0(vd->vdev_ms_shift); return (0); } /* * The baseline weight is the metaslab's free space. */ space = msp->ms_size - space_map_allocated(msp->ms_sm); 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 - (msp->ms_id * weight) / vd->vdev_ms_count; ASSERT(weight >= space && weight <= 2 * space); msp->ms_factor = metaslab_weight_factor(msp); if (metaslab_weight_factor_enable) weight += msp->ms_factor; if (msp->ms_loaded && !msp->ms_ops->msop_fragmented(msp)) { /* * 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 int metaslab_activate(metaslab_t *msp, uint64_t activation_weight) { ASSERT(MUTEX_HELD(&msp->ms_lock)); if ((msp->ms_weight & METASLAB_ACTIVE_MASK) == 0) { metaslab_load_wait(msp); if (!msp->ms_loaded) { int error = metaslab_load(msp); if (error) { metaslab_group_sort(msp->ms_group, msp, 0); return (error); } } metaslab_group_sort(msp->ms_group, msp, msp->ms_weight | activation_weight); } ASSERT(msp->ms_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 || range_tree_space(msp->ms_tree) == 0); metaslab_group_sort(msp->ms_group, msp, MIN(msp->ms_weight, size)); ASSERT((msp->ms_weight & METASLAB_ACTIVE_MASK) == 0); } static void metaslab_preload(void *arg) { metaslab_t *msp = arg; spa_t *spa = msp->ms_group->mg_vd->vdev_spa; mutex_enter(&msp->ms_lock); metaslab_load_wait(msp); if (!msp->ms_loaded) (void) metaslab_load(msp); /* * Set the ms_access_txg value so that we don't unload it right away. */ msp->ms_access_txg = spa_syncing_txg(spa) + metaslab_unload_delay + 1; mutex_exit(&msp->ms_lock); } static void metaslab_group_preload(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 = 0; if (spa_shutting_down(spa) || !metaslab_preload_enabled) { taskq_wait(mg->mg_taskq); return; } mutex_enter(&mg->mg_lock); /* * Prefetch the next potential metaslabs */ for (msp = avl_first(t); msp != NULL; msp = AVL_NEXT(t, msp)) { /* If we have reached our preload limit then we're done */ if (++m > metaslab_preload_limit) break; VERIFY(taskq_dispatch(mg->mg_taskq, metaslab_preload, msp, TQ_SLEEP) != 0); } mutex_exit(&mg->mg_lock); } /* * Determine if the space map's on-disk footprint is past our tolerance * for inefficiency. We would like to use the following criteria to make * our decision: * * 1. The size of the space map object should not dramatically increase as a * result of writing out the free space range tree. * * 2. The minimal on-disk space map representation is zfs_condense_pct/100 * times the size than the free space range tree representation * (i.e. zfs_condense_pct = 110 and in-core = 1MB, minimal = 1.1.MB). * * Checking the first condition is tricky since we don't want to walk * the entire AVL tree calculating the estimated on-disk size. Instead we * use the size-ordered range tree in the metaslab and calculate the * size required to write out the largest segment in our free tree. If the * size required to represent that segment on disk is larger than the space * map object then we avoid condensing this map. * * To determine the second criterion we use a best-case estimate and assume * each segment can be represented on-disk as a single 64-bit entry. We refer * to this best-case estimate as the space map's minimal form. */ static boolean_t metaslab_should_condense(metaslab_t *msp) { space_map_t *sm = msp->ms_sm; range_seg_t *rs; uint64_t size, entries, segsz; ASSERT(MUTEX_HELD(&msp->ms_lock)); ASSERT(msp->ms_loaded); /* * Use the ms_size_tree range tree, which is ordered by size, to * obtain the largest segment in the free tree. If the tree is empty * then we should condense the map. */ rs = avl_last(&msp->ms_size_tree); if (rs == NULL) return (B_TRUE); /* * Calculate the number of 64-bit entries this segment would * require when written to disk. If this single segment would be * larger on-disk than the entire current on-disk structure, then * clearly condensing will increase the on-disk structure size. */ size = (rs->rs_end - rs->rs_start) >> sm->sm_shift; entries = size / (MIN(size, SM_RUN_MAX)); segsz = entries * sizeof (uint64_t); return (segsz <= space_map_length(msp->ms_sm) && space_map_length(msp->ms_sm) >= (zfs_condense_pct * sizeof (uint64_t) * avl_numnodes(&msp->ms_tree->rt_root)) / 100); } /* * Condense the on-disk space map representation to its minimized form. * The minimized form consists of a small number of allocations followed by * the entries of the free range tree. */ static void metaslab_condense(metaslab_t *msp, uint64_t txg, dmu_tx_t *tx) { spa_t *spa = msp->ms_group->mg_vd->vdev_spa; range_tree_t *freetree = msp->ms_freetree[txg & TXG_MASK]; range_tree_t *condense_tree; space_map_t *sm = msp->ms_sm; ASSERT(MUTEX_HELD(&msp->ms_lock)); ASSERT3U(spa_sync_pass(spa), ==, 1); ASSERT(msp->ms_loaded); spa_dbgmsg(spa, "condensing: txg %llu, msp[%llu] %p, " "smp size %llu, segments %lu", txg, msp->ms_id, msp, space_map_length(msp->ms_sm), avl_numnodes(&msp->ms_tree->rt_root)); /* * Create an range tree that is 100% allocated. We remove segments * that have been freed in this txg, any deferred frees that exist, * and any allocation in the future. Removing segments should be * a relatively inexpensive operation since we expect these trees to * have a small number of nodes. */ condense_tree = range_tree_create(NULL, NULL, &msp->ms_lock); range_tree_add(condense_tree, msp->ms_start, msp->ms_size); /* * Remove what's been freed in this txg from the condense_tree. * Since we're in sync_pass 1, we know that all the frees from * this txg are in the freetree. */ range_tree_walk(freetree, range_tree_remove, condense_tree); for (int t = 0; t < TXG_DEFER_SIZE; t++) { range_tree_walk(msp->ms_defertree[t], range_tree_remove, condense_tree); } for (int t = 1; t < TXG_CONCURRENT_STATES; t++) { range_tree_walk(msp->ms_alloctree[(txg + t) & TXG_MASK], range_tree_remove, condense_tree); } /* * We're about to drop the metaslab's lock thus allowing * other consumers to change it's content. Set the * metaslab's ms_condensing flag to ensure that * allocations on this metaslab do not occur while we're * in the middle of committing it to disk. This is only critical * for the ms_tree as all other range trees use per txg * views of their content. */ msp->ms_condensing = B_TRUE; mutex_exit(&msp->ms_lock); space_map_truncate(sm, tx); mutex_enter(&msp->ms_lock); /* * While we would ideally like to create a space_map representation * that consists only of allocation records, doing so can be * prohibitively expensive because the in-core free tree can be * large, and therefore computationally expensive to subtract * from the condense_tree. Instead we sync out two trees, a cheap * allocation only tree followed by the in-core free tree. While not * optimal, this is typically close to optimal, and much cheaper to * compute. */ space_map_write(sm, condense_tree, SM_ALLOC, tx); range_tree_vacate(condense_tree, NULL, NULL); range_tree_destroy(condense_tree); space_map_write(sm, msp->ms_tree, SM_FREE, tx); msp->ms_condensing = B_FALSE; } /* * Write a metaslab to disk in the context of the specified transaction group. */ void metaslab_sync(metaslab_t *msp, uint64_t txg) { metaslab_group_t *mg = msp->ms_group; vdev_t *vd = mg->mg_vd; spa_t *spa = vd->vdev_spa; objset_t *mos = spa_meta_objset(spa); range_tree_t *alloctree = msp->ms_alloctree[txg & TXG_MASK]; range_tree_t **freetree = &msp->ms_freetree[txg & TXG_MASK]; range_tree_t **freed_tree = &msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK]; dmu_tx_t *tx; uint64_t object = space_map_object(msp->ms_sm); ASSERT(!vd->vdev_ishole); /* * This metaslab has just been added so there's no work to do now. */ if (*freetree == NULL) { ASSERT3P(alloctree, ==, NULL); return; } ASSERT3P(alloctree, !=, NULL); ASSERT3P(*freetree, !=, NULL); ASSERT3P(*freed_tree, !=, NULL); if (range_tree_space(alloctree) == 0 && range_tree_space(*freetree) == 0) return; /* * The only state that can actually be changing concurrently with * metaslab_sync() is the metaslab's ms_tree. No other thread can * be modifying this txg's alloctree, freetree, freed_tree, or * space_map_phys_t. 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 (msp->ms_sm == NULL) { uint64_t new_object; new_object = space_map_alloc(mos, tx); VERIFY3U(new_object, !=, 0); VERIFY0(space_map_open(&msp->ms_sm, mos, new_object, msp->ms_start, msp->ms_size, vd->vdev_ashift, &msp->ms_lock)); ASSERT(msp->ms_sm != NULL); } mutex_enter(&msp->ms_lock); if (msp->ms_loaded && spa_sync_pass(spa) == 1 && metaslab_should_condense(msp)) { metaslab_condense(msp, txg, tx); } else { space_map_write(msp->ms_sm, alloctree, SM_ALLOC, tx); space_map_write(msp->ms_sm, *freetree, SM_FREE, tx); } range_tree_vacate(alloctree, NULL, NULL); if (msp->ms_loaded) { /* * When the space map is loaded, we have an accruate * histogram in the range tree. This gives us an opportunity * to bring the space map's histogram up-to-date so we clear * it first before updating it. */ space_map_histogram_clear(msp->ms_sm); space_map_histogram_add(msp->ms_sm, msp->ms_tree, tx); } else { /* * Since the space map is not loaded we simply update the * exisiting histogram with what was freed in this txg. This * means that the on-disk histogram may not have an accurate * view of the free space but it's close enough to allow * us to make allocation decisions. */ space_map_histogram_add(msp->ms_sm, *freetree, tx); } /* * For sync pass 1, we avoid traversing this txg's free range tree * and instead will just swap the pointers for freetree and * freed_tree. We can safely do this since the freed_tree is * guaranteed to be empty on the initial pass. */ if (spa_sync_pass(spa) == 1) { range_tree_swap(freetree, freed_tree); } else { range_tree_vacate(*freetree, range_tree_add, *freed_tree); } ASSERT0(range_tree_space(msp->ms_alloctree[txg & TXG_MASK])); ASSERT0(range_tree_space(msp->ms_freetree[txg & TXG_MASK])); mutex_exit(&msp->ms_lock); if (object != space_map_object(msp->ms_sm)) { object = space_map_object(msp->ms_sm); dmu_write(mos, vd->vdev_ms_array, sizeof (uint64_t) * msp->ms_id, sizeof (uint64_t), &object, tx); } 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) { metaslab_group_t *mg = msp->ms_group; vdev_t *vd = mg->mg_vd; range_tree_t **freed_tree; range_tree_t **defer_tree; int64_t alloc_delta, defer_delta; ASSERT(!vd->vdev_ishole); mutex_enter(&msp->ms_lock); /* * If this metaslab is just becoming available, initialize its * alloctrees, freetrees, and defertree and add its capacity to * the vdev. */ if (msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK] == NULL) { for (int t = 0; t < TXG_SIZE; t++) { ASSERT(msp->ms_alloctree[t] == NULL); ASSERT(msp->ms_freetree[t] == NULL); msp->ms_alloctree[t] = range_tree_create(NULL, msp, &msp->ms_lock); msp->ms_freetree[t] = range_tree_create(NULL, msp, &msp->ms_lock); } for (int t = 0; t < TXG_DEFER_SIZE; t++) { ASSERT(msp->ms_defertree[t] == NULL); msp->ms_defertree[t] = range_tree_create(NULL, msp, &msp->ms_lock); } vdev_space_update(vd, 0, 0, msp->ms_size); } freed_tree = &msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK]; defer_tree = &msp->ms_defertree[txg % TXG_DEFER_SIZE]; alloc_delta = space_map_alloc_delta(msp->ms_sm); defer_delta = range_tree_space(*freed_tree) - range_tree_space(*defer_tree); vdev_space_update(vd, alloc_delta + defer_delta, defer_delta, 0); ASSERT0(range_tree_space(msp->ms_alloctree[txg & TXG_MASK])); ASSERT0(range_tree_space(msp->ms_freetree[txg & TXG_MASK])); /* * If there's a metaslab_load() in progress, wait for it to complete * so that we have a consistent view of the in-core space map. */ metaslab_load_wait(msp); /* * Move the frees from the defer_tree back to the free * range tree (if it's loaded). Swap the freed_tree and the * defer_tree -- this is safe to do because we've just emptied out * the defer_tree. */ range_tree_vacate(*defer_tree, msp->ms_loaded ? range_tree_add : NULL, msp->ms_tree); range_tree_swap(freed_tree, defer_tree); space_map_update(msp->ms_sm); msp->ms_deferspace += defer_delta; ASSERT3S(msp->ms_deferspace, >=, 0); ASSERT3S(msp->ms_deferspace, <=, msp->ms_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 (msp->ms_loaded && msp->ms_access_txg < txg) { for (int t = 1; t < TXG_CONCURRENT_STATES; t++) { VERIFY0(range_tree_space( msp->ms_alloctree[(txg + t) & TXG_MASK])); } if (!metaslab_debug_unload) metaslab_unload(msp); } metaslab_group_sort(mg, msp, metaslab_weight(msp)); mutex_exit(&msp->ms_lock); } void metaslab_sync_reassess(metaslab_group_t *mg) { int64_t failures = mg->mg_alloc_failures; metaslab_group_alloc_update(mg); atomic_add_64(&mg->mg_alloc_failures, -failures); /* * Preload the next potential metaslabs */ metaslab_group_preload(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_id; 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); } /* * If the selected metaslab is condensing, skip it. */ if (msp->ms_condensing) continue; was_active = msp->ms_weight & METASLAB_ACTIVE_MASK; if (activation_weight == METASLAB_WEIGHT_PRIMARY) break; target_distance = min_distance + (space_map_allocated(msp->ms_sm) != 0 ? 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); mutex_enter(&msp->ms_lock); /* * 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, msp[%llu] %p, " "psize %llu, asize %llu, failures %llu", spa_name(spa), mg->mg_vd->vdev_id, txg, mg, msp->ms_id, msp, psize, asize, mg->mg_alloc_failures); mutex_exit(&msp->ms_lock); return (-1ULL); } /* * 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 this metaslab is currently condensing then pick again as * we can't manipulate this metaslab until it's committed * to disk. */ if (msp->ms_condensing) { mutex_exit(&msp->ms_lock); continue; } if ((offset = metaslab_block_alloc(msp, asize)) != -1ULL) break; atomic_inc_64(&mg->mg_alloc_failures); metaslab_passivate(msp, metaslab_block_maxsize(msp)); mutex_exit(&msp->ms_lock); } if (range_tree_space(msp->ms_alloctree[txg & TXG_MASK]) == 0) vdev_dirty(mg->mg_vd, VDD_METASLAB, msp, txg); range_tree_add(msp->ms_alloctree[txg & TXG_MASK], offset, asize); msp->ms_access_txg = txg + metaslab_unload_delay; 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 (SET_ERROR(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); } /* * Determine if the selected metaslab group is eligible * for allocations. If we're ganging or have requested * an allocation for the smallest gang block size * then we don't want to avoid allocating to the this * metaslab group. If we're in this condition we should * try to allocate from any device possible so that we * don't inadvertently return ENOSPC and suspend the pool * even though space is still available. */ if (allocatable && CAN_FASTGANG(flags) && psize > SPA_GANGBLOCKSIZE) allocatable = metaslab_group_allocatable(mg); if (!allocatable) goto next; /* * Avoid writing single-copy data to a failing vdev * unless the user instructs us that it is okay. */ if ((vd->vdev_stat.vs_write_errors > 0 || vd->vdev_state < VDEV_STATE_HEALTHY) && d == 0 && dshift == 3 && !(zfs_write_to_degraded && vd->vdev_state == VDEV_STATE_DEGRADED)) { 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 (SET_ERROR(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) { range_tree_remove(msp->ms_alloctree[txg & TXG_MASK], offset, size); VERIFY(!msp->ms_condensing); VERIFY3U(offset, >=, msp->ms_start); VERIFY3U(offset + size, <=, msp->ms_start + msp->ms_size); VERIFY3U(range_tree_space(msp->ms_tree) + size, <=, msp->ms_size); VERIFY0(P2PHASE(offset, 1ULL << vd->vdev_ashift)); VERIFY0(P2PHASE(size, 1ULL << vd->vdev_ashift)); range_tree_add(msp->ms_tree, offset, size); } else { if (range_tree_space(msp->ms_freetree[txg & TXG_MASK]) == 0) vdev_dirty(vd, VDD_METASLAB, msp, txg); range_tree_add(msp->ms_freetree[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 (SET_ERROR(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_loaded) error = metaslab_activate(msp, METASLAB_WEIGHT_SECONDARY); if (error == 0 && !range_tree_contains(msp->ms_tree, offset, size)) error = SET_ERROR(ENOENT); if (error || txg == 0) { /* txg == 0 indicates dry run */ mutex_exit(&msp->ms_lock); return (error); } VERIFY(!msp->ms_condensing); VERIFY0(P2PHASE(offset, 1ULL << vd->vdev_ashift)); VERIFY0(P2PHASE(size, 1ULL << vd->vdev_ashift)); VERIFY3U(range_tree_space(msp->ms_tree) - size, <=, msp->ms_size); range_tree_remove(msp->ms_tree, offset, size); if (spa_writeable(spa)) { /* don't dirty if we're zdb(1M) */ if (range_tree_space(msp->ms_alloctree[txg & TXG_MASK]) == 0) vdev_dirty(vd, VDD_METASLAB, msp, txg); range_tree_add(msp->ms_alloctree[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 (SET_ERROR(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 != 0) { 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); } void metaslab_check_free(spa_t *spa, const blkptr_t *bp) { if ((zfs_flags & ZFS_DEBUG_ZIO_FREE) == 0) return; spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER); for (int i = 0; i < BP_GET_NDVAS(bp); i++) { uint64_t vdev = DVA_GET_VDEV(&bp->blk_dva[i]); vdev_t *vd = vdev_lookup_top(spa, vdev); uint64_t offset = DVA_GET_OFFSET(&bp->blk_dva[i]); uint64_t size = DVA_GET_ASIZE(&bp->blk_dva[i]); metaslab_t *msp = vd->vdev_ms[offset >> vd->vdev_ms_shift]; if (msp->ms_loaded) range_tree_verify(msp->ms_tree, offset, size); for (int j = 0; j < TXG_SIZE; j++) range_tree_verify(msp->ms_freetree[j], offset, size); for (int j = 0; j < TXG_DEFER_SIZE; j++) range_tree_verify(msp->ms_defertree[j], offset, size); } spa_config_exit(spa, SCL_VDEV, FTAG); }