Index: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c =================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c (revision 317526) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c (revision 317527) @@ -1,3494 +1,3489 @@ /* * 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) 2011, 2015 by Delphix. All rights reserved. * Copyright (c) 2013 by Saso Kiselkov. All rights reserved. * Copyright (c) 2014 Integros [integros.com] */ #include #include #include #include #include #include #include #include #include SYSCTL_DECL(_vfs_zfs); SYSCTL_NODE(_vfs_zfs, OID_AUTO, metaslab, CTLFLAG_RW, 0, "ZFS metaslab"); #define GANG_ALLOCATION(flags) \ ((flags) & (METASLAB_GANG_CHILD | METASLAB_GANG_HEADER)) uint64_t metaslab_aliquot = 512ULL << 10; uint64_t metaslab_gang_bang = SPA_MAXBLOCKSIZE + 1; /* force gang blocks */ 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; 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"); /* * Condensing a metaslab is not guaranteed to actually reduce the amount of * space used on disk. In particular, a space map uses data in increments of * MAX(1 << ashift, space_map_blksize), so a metaslab might use the * same number of blocks after condensing. Since the goal of condensing is to * reduce the number of IOPs required to read the space map, we only want to * condense when we can be sure we will reduce the number of blocks used by the * space map. Unfortunately, we cannot precisely compute whether or not this is * the case in metaslab_should_condense since we are holding ms_lock. Instead, * we apply the following heuristic: do not condense a spacemap unless the * uncondensed size consumes greater than zfs_metaslab_condense_block_threshold * blocks. */ int zfs_metaslab_condense_block_threshold = 4; /* * The zfs_mg_noalloc_threshold defines which metaslab groups should * be eligible for allocation. The value is defined as a percentage of * 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; 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"); /* * Metaslab groups are considered eligible for allocations if their * fragmenation metric (measured as a percentage) is less than or equal to * zfs_mg_fragmentation_threshold. If a metaslab group exceeds this threshold * then it will be skipped unless all metaslab groups within the metaslab * class have also crossed this threshold. */ int zfs_mg_fragmentation_threshold = 85; SYSCTL_INT(_vfs_zfs, OID_AUTO, mg_fragmentation_threshold, CTLFLAG_RWTUN, &zfs_mg_fragmentation_threshold, 0, "Percentage of metaslab group size that should be considered " "eligible for allocations unless all metaslab groups within the metaslab class " "have also crossed this threshold"); /* * Allow metaslabs to keep their active state as long as their fragmentation * percentage is less than or equal to zfs_metaslab_fragmentation_threshold. An * active metaslab that exceeds this threshold will no longer keep its active * status allowing better metaslabs to be selected. */ int zfs_metaslab_fragmentation_threshold = 70; SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, fragmentation_threshold, CTLFLAG_RWTUN, &zfs_metaslab_fragmentation_threshold, 0, "Maximum percentage of metaslab fragmentation level to keep their active state"); /* * When set will load all metaslabs when pool is first opened. */ int metaslab_debug_load = 0; 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; 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_OLD_MAXBLOCKSIZE; 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; 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; 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; 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; 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"); /* * Max number of metaslabs per group to preload. */ int metaslab_preload_limit = SPA_DVAS_PER_BP; 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; 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 fragmentation weighting on metaslabs. */ boolean_t metaslab_fragmentation_factor_enabled = B_TRUE; SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, fragmentation_factor_enabled, CTLFLAG_RWTUN, &metaslab_fragmentation_factor_enabled, 0, "Enable fragmentation weighting on metaslabs"); /* * Enable/disable lba weighting (i.e. outer tracks are given preference). */ boolean_t metaslab_lba_weighting_enabled = B_TRUE; SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, lba_weighting_enabled, CTLFLAG_RWTUN, &metaslab_lba_weighting_enabled, 0, "Enable LBA weighting (i.e. outer tracks are given preference)"); /* * Enable/disable metaslab group biasing. */ boolean_t metaslab_bias_enabled = B_TRUE; SYSCTL_INT(_vfs_zfs_metaslab, OID_AUTO, bias_enabled, CTLFLAG_RWTUN, &metaslab_bias_enabled, 0, "Enable metaslab group biasing"); /* * Enable/disable segment-based metaslab selection. */ boolean_t zfs_metaslab_segment_weight_enabled = B_TRUE; /* * When using segment-based metaslab selection, we will continue * allocating from the active metaslab until we have exhausted * zfs_metaslab_switch_threshold of its buckets. */ int zfs_metaslab_switch_threshold = 2; /* * Internal switch to enable/disable the metaslab allocation tracing * facility. */ boolean_t metaslab_trace_enabled = B_TRUE; /* * Maximum entries that the metaslab allocation tracing facility will keep * in a given list when running in non-debug mode. We limit the number * of entries in non-debug mode to prevent us from using up too much memory. * The limit should be sufficiently large that we don't expect any allocation * to every exceed this value. In debug mode, the system will panic if this * limit is ever reached allowing for further investigation. */ uint64_t metaslab_trace_max_entries = 5000; static uint64_t metaslab_weight(metaslab_t *); static void metaslab_set_fragmentation(metaslab_t *); kmem_cache_t *metaslab_alloc_trace_cache; /* * ========================================================================== * 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; mutex_init(&mc->mc_lock, NULL, MUTEX_DEFAULT, NULL); refcount_create_tracked(&mc->mc_alloc_slots); 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); refcount_destroy(&mc->mc_alloc_slots); mutex_destroy(&mc->mc_lock); 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); } void metaslab_class_histogram_verify(metaslab_class_t *mc) { vdev_t *rvd = mc->mc_spa->spa_root_vdev; uint64_t *mc_hist; int i; if ((zfs_flags & ZFS_DEBUG_HISTOGRAM_VERIFY) == 0) return; mc_hist = kmem_zalloc(sizeof (uint64_t) * RANGE_TREE_HISTOGRAM_SIZE, KM_SLEEP); for (int c = 0; c < rvd->vdev_children; c++) { vdev_t *tvd = rvd->vdev_child[c]; metaslab_group_t *mg = tvd->vdev_mg; /* * Skip any holes, uninitialized top-levels, or * vdevs that are not in this metalab class. */ if (tvd->vdev_ishole || tvd->vdev_ms_shift == 0 || mg->mg_class != mc) { continue; } for (i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++) mc_hist[i] += mg->mg_histogram[i]; } for (i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++) VERIFY3U(mc_hist[i], ==, mc->mc_histogram[i]); kmem_free(mc_hist, sizeof (uint64_t) * RANGE_TREE_HISTOGRAM_SIZE); } /* * Calculate the metaslab class's fragmentation metric. The metric * is weighted based on the space contribution of each metaslab group. * The return value will be a number between 0 and 100 (inclusive), or * ZFS_FRAG_INVALID if the metric has not been set. See comment above the * zfs_frag_table for more information about the metric. */ uint64_t metaslab_class_fragmentation(metaslab_class_t *mc) { vdev_t *rvd = mc->mc_spa->spa_root_vdev; uint64_t fragmentation = 0; spa_config_enter(mc->mc_spa, SCL_VDEV, FTAG, RW_READER); for (int c = 0; c < rvd->vdev_children; c++) { vdev_t *tvd = rvd->vdev_child[c]; metaslab_group_t *mg = tvd->vdev_mg; /* * Skip any holes, uninitialized top-levels, or * vdevs that are not in this metalab class. */ if (tvd->vdev_ishole || tvd->vdev_ms_shift == 0 || mg->mg_class != mc) { continue; } /* * If a metaslab group does not contain a fragmentation * metric then just bail out. */ if (mg->mg_fragmentation == ZFS_FRAG_INVALID) { spa_config_exit(mc->mc_spa, SCL_VDEV, FTAG); return (ZFS_FRAG_INVALID); } /* * Determine how much this metaslab_group is contributing * to the overall pool fragmentation metric. */ fragmentation += mg->mg_fragmentation * metaslab_group_get_space(mg); } fragmentation /= metaslab_class_get_space(mc); ASSERT3U(fragmentation, <=, 100); spa_config_exit(mc->mc_spa, SCL_VDEV, FTAG); return (fragmentation); } /* * Calculate the amount of expandable space that is available in * this metaslab class. If a device is expanded then its expandable * space will be the amount of allocatable space that is currently not * part of this metaslab class. */ uint64_t metaslab_class_expandable_space(metaslab_class_t *mc) { vdev_t *rvd = mc->mc_spa->spa_root_vdev; uint64_t space = 0; spa_config_enter(mc->mc_spa, SCL_VDEV, FTAG, RW_READER); for (int c = 0; c < rvd->vdev_children; c++) { vdev_t *tvd = rvd->vdev_child[c]; metaslab_group_t *mg = tvd->vdev_mg; if (tvd->vdev_ishole || tvd->vdev_ms_shift == 0 || mg->mg_class != mc) { continue; } /* * Calculate if we have enough space to add additional * metaslabs. We report the expandable space in terms * of the metaslab size since that's the unit of expansion. */ space += P2ALIGN(tvd->vdev_max_asize - tvd->vdev_asize, 1ULL << tvd->vdev_ms_shift); } spa_config_exit(mc->mc_spa, SCL_VDEV, FTAG); return (space); } 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); } /* * Verify that the space accounting on disk matches the in-core range_trees. */ void metaslab_verify_space(metaslab_t *msp, uint64_t txg) { spa_t *spa = msp->ms_group->mg_vd->vdev_spa; uint64_t allocated = 0; - uint64_t freed = 0; uint64_t sm_free_space, msp_free_space; ASSERT(MUTEX_HELD(&msp->ms_lock)); if ((zfs_flags & ZFS_DEBUG_METASLAB_VERIFY) == 0) return; /* * We can only verify the metaslab space when we're called * from syncing context with a loaded metaslab that has an allocated * space map. Calling this in non-syncing context does not * provide a consistent view of the metaslab since we're performing * allocations in the future. */ if (txg != spa_syncing_txg(spa) || msp->ms_sm == NULL || !msp->ms_loaded) return; sm_free_space = msp->ms_size - space_map_allocated(msp->ms_sm) - space_map_alloc_delta(msp->ms_sm); /* * Account for future allocations since we would have already * deducted that space from the ms_freetree. */ for (int t = 0; t < TXG_CONCURRENT_STATES; t++) { allocated += range_tree_space(msp->ms_alloctree[(txg + t) & TXG_MASK]); } - freed = range_tree_space(msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK]); msp_free_space = range_tree_space(msp->ms_tree) + allocated + - msp->ms_deferspace + freed; + msp->ms_deferspace + range_tree_space(msp->ms_freedtree); VERIFY3U(sm_free_space, ==, msp_free_space); } /* * ========================================================================== * Metaslab groups * ========================================================================== */ /* * 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 or has a fragmentation value that is * greater than zfs_mg_fragmentation_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; boolean_t was_initialized; ASSERT(vd == vd->vdev_top); mutex_enter(&mg->mg_lock); was_allocatable = mg->mg_allocatable; was_initialized = mg->mg_initialized; mg->mg_free_capacity = ((vs->vs_space - vs->vs_alloc) * 100) / (vs->vs_space + 1); mutex_enter(&mc->mc_lock); /* * If the metaslab group was just added then it won't * have any space until we finish syncing out this txg. * At that point we will consider it initialized and available * for allocations. We also don't consider non-activated * metaslab groups (e.g. vdevs that are in the middle of being removed) * to be initialized, because they can't be used for allocation. */ mg->mg_initialized = metaslab_group_initialized(mg); if (!was_initialized && mg->mg_initialized) { mc->mc_groups++; } else if (was_initialized && !mg->mg_initialized) { ASSERT3U(mc->mc_groups, >, 0); mc->mc_groups--; } if (mg->mg_initialized) mg->mg_no_free_space = B_FALSE; /* * A metaslab group is considered allocatable if it has plenty * of free space or is not heavily fragmented. We only take * fragmentation into account if the metaslab group has a valid * fragmentation metric (i.e. a value between 0 and 100). */ mg->mg_allocatable = (mg->mg_activation_count > 0 && mg->mg_free_capacity > zfs_mg_noalloc_threshold && (mg->mg_fragmentation == ZFS_FRAG_INVALID || mg->mg_fragmentation <= zfs_mg_fragmentation_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(&mc->mc_lock); 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_initialized = B_FALSE; mg->mg_no_free_space = B_TRUE; refcount_create_tracked(&mg->mg_alloc_queue_depth); mg->mg_taskq = taskq_create("metaslab_group_taskq", 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); taskq_destroy(mg->mg_taskq); avl_destroy(&mg->mg_metaslab_tree); mutex_destroy(&mg->mg_lock); refcount_destroy(&mg->mg_alloc_queue_depth); 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); metaslab_group_alloc_update(mg); 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); } boolean_t metaslab_group_initialized(metaslab_group_t *mg) { vdev_t *vd = mg->mg_vd; vdev_stat_t *vs = &vd->vdev_stat; return (vs->vs_space != 0 && mg->mg_activation_count > 0); } uint64_t metaslab_group_get_space(metaslab_group_t *mg) { return ((1ULL << mg->mg_vd->vdev_ms_shift) * mg->mg_vd->vdev_ms_count); } void metaslab_group_histogram_verify(metaslab_group_t *mg) { uint64_t *mg_hist; vdev_t *vd = mg->mg_vd; uint64_t ashift = vd->vdev_ashift; int i; if ((zfs_flags & ZFS_DEBUG_HISTOGRAM_VERIFY) == 0) return; mg_hist = kmem_zalloc(sizeof (uint64_t) * RANGE_TREE_HISTOGRAM_SIZE, KM_SLEEP); ASSERT3U(RANGE_TREE_HISTOGRAM_SIZE, >=, SPACE_MAP_HISTOGRAM_SIZE + ashift); for (int m = 0; m < vd->vdev_ms_count; m++) { metaslab_t *msp = vd->vdev_ms[m]; if (msp->ms_sm == NULL) continue; for (i = 0; i < SPACE_MAP_HISTOGRAM_SIZE; i++) mg_hist[i + ashift] += msp->ms_sm->sm_phys->smp_histogram[i]; } for (i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i ++) VERIFY3U(mg_hist[i], ==, mg->mg_histogram[i]); kmem_free(mg_hist, sizeof (uint64_t) * RANGE_TREE_HISTOGRAM_SIZE); } static void metaslab_group_histogram_add(metaslab_group_t *mg, metaslab_t *msp) { metaslab_class_t *mc = mg->mg_class; uint64_t ashift = mg->mg_vd->vdev_ashift; ASSERT(MUTEX_HELD(&msp->ms_lock)); if (msp->ms_sm == NULL) return; mutex_enter(&mg->mg_lock); for (int i = 0; i < SPACE_MAP_HISTOGRAM_SIZE; i++) { mg->mg_histogram[i + ashift] += msp->ms_sm->sm_phys->smp_histogram[i]; mc->mc_histogram[i + ashift] += msp->ms_sm->sm_phys->smp_histogram[i]; } mutex_exit(&mg->mg_lock); } void metaslab_group_histogram_remove(metaslab_group_t *mg, metaslab_t *msp) { metaslab_class_t *mc = mg->mg_class; uint64_t ashift = mg->mg_vd->vdev_ashift; ASSERT(MUTEX_HELD(&msp->ms_lock)); if (msp->ms_sm == NULL) return; mutex_enter(&mg->mg_lock); for (int i = 0; i < SPACE_MAP_HISTOGRAM_SIZE; i++) { ASSERT3U(mg->mg_histogram[i + ashift], >=, msp->ms_sm->sm_phys->smp_histogram[i]); ASSERT3U(mc->mc_histogram[i + ashift], >=, msp->ms_sm->sm_phys->smp_histogram[i]); mg->mg_histogram[i + ashift] -= msp->ms_sm->sm_phys->smp_histogram[i]; mc->mc_histogram[i + ashift] -= msp->ms_sm->sm_phys->smp_histogram[i]; } mutex_exit(&mg->mg_lock); } static void metaslab_group_add(metaslab_group_t *mg, metaslab_t *msp) { ASSERT(msp->ms_group == NULL); mutex_enter(&mg->mg_lock); msp->ms_group = mg; msp->ms_weight = 0; avl_add(&mg->mg_metaslab_tree, msp); mutex_exit(&mg->mg_lock); mutex_enter(&msp->ms_lock); metaslab_group_histogram_add(mg, msp); mutex_exit(&msp->ms_lock); } static void metaslab_group_remove(metaslab_group_t *mg, metaslab_t *msp) { mutex_enter(&msp->ms_lock); metaslab_group_histogram_remove(mg, msp); mutex_exit(&msp->ms_lock); 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, 511]. */ ASSERT(weight >= SPA_MINBLOCKSIZE || 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); } /* * Calculate the fragmentation for a given metaslab group. We can use * a simple average here since all metaslabs within the group must have * the same size. The return value will be a value between 0 and 100 * (inclusive), or ZFS_FRAG_INVALID if less than half of the metaslab in this * group have a fragmentation metric. */ uint64_t metaslab_group_fragmentation(metaslab_group_t *mg) { vdev_t *vd = mg->mg_vd; uint64_t fragmentation = 0; uint64_t valid_ms = 0; for (int m = 0; m < vd->vdev_ms_count; m++) { metaslab_t *msp = vd->vdev_ms[m]; if (msp->ms_fragmentation == ZFS_FRAG_INVALID) continue; valid_ms++; fragmentation += msp->ms_fragmentation; } if (valid_ms <= vd->vdev_ms_count / 2) return (ZFS_FRAG_INVALID); fragmentation /= valid_ms; ASSERT3U(fragmentation, <=, 100); return (fragmentation); } /* * Determine if a given metaslab group should skip allocations. A metaslab * group should avoid allocations if its free capacity is less than the * zfs_mg_noalloc_threshold or its fragmentation metric is greater than * zfs_mg_fragmentation_threshold and there is at least one metaslab group * that can still handle allocations. If the allocation throttle is enabled * then we skip allocations to devices that have reached their maximum * allocation queue depth unless the selected metaslab group is the only * eligible group remaining. */ static boolean_t metaslab_group_allocatable(metaslab_group_t *mg, metaslab_group_t *rotor, uint64_t psize) { spa_t *spa = mg->mg_vd->vdev_spa; metaslab_class_t *mc = mg->mg_class; /* * We can only consider skipping this metaslab group if it's * in the normal metaslab class and there are other metaslab * groups to select from. Otherwise, we always consider it eligible * for allocations. */ if (mc != spa_normal_class(spa) || mc->mc_groups <= 1) return (B_TRUE); /* * If the metaslab group's mg_allocatable flag is set (see comments * in metaslab_group_alloc_update() for more information) and * the allocation throttle is disabled then allow allocations to this * device. However, if the allocation throttle is enabled then * check if we have reached our allocation limit (mg_alloc_queue_depth) * to determine if we should allow allocations to this metaslab group. * If all metaslab groups are no longer considered allocatable * (mc_alloc_groups == 0) or we're trying to allocate the smallest * gang block size then we allow allocations on this metaslab group * regardless of the mg_allocatable or throttle settings. */ if (mg->mg_allocatable) { metaslab_group_t *mgp; int64_t qdepth; uint64_t qmax = mg->mg_max_alloc_queue_depth; if (!mc->mc_alloc_throttle_enabled) return (B_TRUE); /* * If this metaslab group does not have any free space, then * there is no point in looking further. */ if (mg->mg_no_free_space) return (B_FALSE); qdepth = refcount_count(&mg->mg_alloc_queue_depth); /* * If this metaslab group is below its qmax or it's * the only allocatable metasable group, then attempt * to allocate from it. */ if (qdepth < qmax || mc->mc_alloc_groups == 1) return (B_TRUE); ASSERT3U(mc->mc_alloc_groups, >, 1); /* * Since this metaslab group is at or over its qmax, we * need to determine if there are metaslab groups after this * one that might be able to handle this allocation. This is * racy since we can't hold the locks for all metaslab * groups at the same time when we make this check. */ for (mgp = mg->mg_next; mgp != rotor; mgp = mgp->mg_next) { qmax = mgp->mg_max_alloc_queue_depth; qdepth = refcount_count(&mgp->mg_alloc_queue_depth); /* * If there is another metaslab group that * might be able to handle the allocation, then * we return false so that we skip this group. */ if (qdepth < qmax && !mgp->mg_no_free_space) return (B_FALSE); } /* * We didn't find another group to handle the allocation * so we can't skip this metaslab group even though * we are at or over our qmax. */ return (B_TRUE); } else if (mc->mc_alloc_groups == 0 || psize == SPA_MINBLOCKSIZE) { return (B_TRUE); } return (B_FALSE); } /* * ========================================================================== * 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 }; /* * ========================================================================== * Common allocator routines * ========================================================================== */ /* * 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); } static range_seg_t * metaslab_block_find(avl_tree_t *t, uint64_t start, uint64_t size) { range_seg_t *rs, rsearch; avl_index_t where; rsearch.rs_start = start; rsearch.rs_end = start + size; rs = avl_find(t, &rsearch, &where); if (rs == NULL) { rs = avl_nearest(t, where, AVL_AFTER); } return (rs); } /* * 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 = metaslab_block_find(t, *cursor, size); 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[highbit64(align) - 1]; avl_tree_t *t = &msp->ms_tree->rt_root; return (metaslab_block_picker(t, cursor, size, align)); } static metaslab_ops_t metaslab_ff_ops = { metaslab_ff_alloc }; /* * ========================================================================== * 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[highbit64(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 metaslab_ops_t metaslab_df_ops = { metaslab_df_alloc }; /* * ========================================================================== * 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 metaslab_ops_t metaslab_cf_ops = { metaslab_cf_alloc }; /* * ========================================================================== * 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 = highbit64(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 metaslab_ops_t metaslab_ndf_ops = { metaslab_ndf_alloc }; 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; boolean_t success = B_FALSE; 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); success = (error == 0); msp->ms_loading = B_FALSE; if (success) { ASSERT3P(msp->ms_group, !=, NULL); msp->ms_loaded = B_TRUE; for (int t = 0; t < TXG_DEFER_SIZE; t++) { range_tree_walk(msp->ms_defertree[t], range_tree_remove, msp->ms_tree); } msp->ms_max_size = metaslab_block_maxsize(msp); } 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; msp->ms_max_size = 0; } int metaslab_init(metaslab_group_t *mg, uint64_t id, uint64_t object, uint64_t txg, metaslab_t **msp) { vdev_t *vd = mg->mg_vd; objset_t *mos = vd->vdev_spa->spa_meta_objset; metaslab_t *ms; int error; ms = kmem_zalloc(sizeof (metaslab_t), KM_SLEEP); mutex_init(&ms->ms_lock, NULL, MUTEX_DEFAULT, NULL); cv_init(&ms->ms_load_cv, NULL, CV_DEFAULT, NULL); ms->ms_id = id; ms->ms_start = id << vd->vdev_ms_shift; ms->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) { error = space_map_open(&ms->ms_sm, mos, object, ms->ms_start, ms->ms_size, vd->vdev_ashift, &ms->ms_lock); if (error != 0) { kmem_free(ms, sizeof (metaslab_t)); return (error); } ASSERT(ms->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 + * other range trees 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. */ ms->ms_tree = range_tree_create(&metaslab_rt_ops, ms, &ms->ms_lock); metaslab_group_add(mg, ms); metaslab_set_fragmentation(ms); /* * 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. * The metaslab's weight will also be initialized when we sync * out this txg. This ensures that we don't attempt to allocate * from it before we have initialized it completely. */ if (txg <= TXG_INITIAL) metaslab_sync_done(ms, 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 && ms->ms_sm != NULL) { mutex_enter(&ms->ms_lock); VERIFY0(metaslab_load(ms)); mutex_exit(&ms->ms_lock); } if (txg != 0) { vdev_dirty(vd, 0, NULL, txg); vdev_dirty(vd, VDD_METASLAB, ms, txg); } *msp = ms; return (0); } 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); + range_tree_destroy(msp->ms_freeingtree); + range_tree_destroy(msp->ms_freedtree); 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)); } #define FRAGMENTATION_TABLE_SIZE 17 /* * This table defines a segment size based fragmentation metric that will * allow each metaslab to derive its own fragmentation value. This is done * by calculating the space in each bucket of the spacemap histogram and * multiplying that by the fragmetation metric in this table. Doing * this for all buckets and dividing it by the total amount of free * space in this metaslab (i.e. the total free space in all buckets) gives * us the fragmentation metric. This means that a high fragmentation metric * equates to most of the free space being comprised of small segments. * Conversely, if the metric is low, then most of the free space is in * large segments. A 10% change in fragmentation equates to approximately * double the number of segments. * * This table defines 0% fragmented space using 16MB segments. Testing has * shown that segments that are greater than or equal to 16MB do not suffer * from drastic performance problems. Using this value, we derive the rest * of the table. Since the fragmentation value is never stored on disk, it * is possible to change these calculations in the future. */ int zfs_frag_table[FRAGMENTATION_TABLE_SIZE] = { 100, /* 512B */ 100, /* 1K */ 98, /* 2K */ 95, /* 4K */ 90, /* 8K */ 80, /* 16K */ 70, /* 32K */ 60, /* 64K */ 50, /* 128K */ 40, /* 256K */ 30, /* 512K */ 20, /* 1M */ 15, /* 2M */ 10, /* 4M */ 5, /* 8M */ 0 /* 16M */ }; /* * Calclate the metaslab's fragmentation metric. A return value * of ZFS_FRAG_INVALID means that the metaslab has not been upgraded and does * not support this metric. Otherwise, the return value should be in the * range [0, 100]. */ static void metaslab_set_fragmentation(metaslab_t *msp) { spa_t *spa = msp->ms_group->mg_vd->vdev_spa; uint64_t fragmentation = 0; uint64_t total = 0; boolean_t feature_enabled = spa_feature_is_enabled(spa, SPA_FEATURE_SPACEMAP_HISTOGRAM); if (!feature_enabled) { msp->ms_fragmentation = ZFS_FRAG_INVALID; return; } /* * A null space map means that the entire metaslab is free * and thus is not fragmented. */ if (msp->ms_sm == NULL) { msp->ms_fragmentation = 0; return; } /* * If this metaslab's space map has not been upgraded, flag it * so that we upgrade next time we encounter it. */ if (msp->ms_sm->sm_dbuf->db_size != sizeof (space_map_phys_t)) { uint64_t txg = spa_syncing_txg(spa); vdev_t *vd = msp->ms_group->mg_vd; if (spa_writeable(spa)) { msp->ms_condense_wanted = B_TRUE; vdev_dirty(vd, VDD_METASLAB, msp, txg + 1); spa_dbgmsg(spa, "txg %llu, requesting force condense: " "msp %p, vd %p", txg, msp, vd); } msp->ms_fragmentation = ZFS_FRAG_INVALID; return; } for (int i = 0; i < SPACE_MAP_HISTOGRAM_SIZE; i++) { uint64_t space = 0; uint8_t shift = msp->ms_sm->sm_shift; int idx = MIN(shift - SPA_MINBLOCKSHIFT + i, FRAGMENTATION_TABLE_SIZE - 1); if (msp->ms_sm->sm_phys->smp_histogram[i] == 0) continue; space = msp->ms_sm->sm_phys->smp_histogram[i] << (i + shift); total += space; ASSERT3U(idx, <, FRAGMENTATION_TABLE_SIZE); fragmentation += space * zfs_frag_table[idx]; } if (total > 0) fragmentation /= total; ASSERT3U(fragmentation, <=, 100); msp->ms_fragmentation = fragmentation; } /* * Compute a weight -- a selection preference value -- for the given metaslab. * This is based on the amount of free space, the level of fragmentation, * the LBA range, and whether the metaslab is loaded. */ static uint64_t metaslab_space_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)); ASSERT(!vd->vdev_removing); /* * The baseline weight is the metaslab's free space. */ space = msp->ms_size - space_map_allocated(msp->ms_sm); if (metaslab_fragmentation_factor_enabled && msp->ms_fragmentation != ZFS_FRAG_INVALID) { /* * Use the fragmentation information to inversely scale * down the baseline weight. We need to ensure that we * don't exclude this metaslab completely when it's 100% * fragmented. To avoid this we reduce the fragmented value * by 1. */ space = (space * (100 - (msp->ms_fragmentation - 1))) / 100; /* * If space < SPA_MINBLOCKSIZE, then we will not allocate from * this metaslab again. The fragmentation metric may have * decreased the space to something smaller than * SPA_MINBLOCKSIZE, so reset the space to SPA_MINBLOCKSIZE * so that we can consume any remaining space. */ if (space > 0 && space < SPA_MINBLOCKSIZE) space = SPA_MINBLOCKSIZE; } 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. */ if (metaslab_lba_weighting_enabled) { weight = 2 * weight - (msp->ms_id * weight) / vd->vdev_ms_count; ASSERT(weight >= space && weight <= 2 * space); } /* * 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. If the fragmentation on this metaslab * has exceed our threshold, then don't mark it active. */ if (msp->ms_loaded && msp->ms_fragmentation != ZFS_FRAG_INVALID && msp->ms_fragmentation <= zfs_metaslab_fragmentation_threshold) { weight |= (msp->ms_weight & METASLAB_ACTIVE_MASK); } WEIGHT_SET_SPACEBASED(weight); return (weight); } /* * Return the weight of the specified metaslab, according to the segment-based * weighting algorithm. The metaslab must be loaded. This function can * be called within a sync pass since it relies only on the metaslab's * range tree which is always accurate when the metaslab is loaded. */ static uint64_t metaslab_weight_from_range_tree(metaslab_t *msp) { uint64_t weight = 0; uint32_t segments = 0; ASSERT(msp->ms_loaded); for (int i = RANGE_TREE_HISTOGRAM_SIZE - 1; i >= SPA_MINBLOCKSHIFT; i--) { uint8_t shift = msp->ms_group->mg_vd->vdev_ashift; int max_idx = SPACE_MAP_HISTOGRAM_SIZE + shift - 1; segments <<= 1; segments += msp->ms_tree->rt_histogram[i]; /* * The range tree provides more precision than the space map * and must be downgraded so that all values fit within the * space map's histogram. This allows us to compare loaded * vs. unloaded metaslabs to determine which metaslab is * considered "best". */ if (i > max_idx) continue; if (segments != 0) { WEIGHT_SET_COUNT(weight, segments); WEIGHT_SET_INDEX(weight, i); WEIGHT_SET_ACTIVE(weight, 0); break; } } return (weight); } /* * Calculate the weight based on the on-disk histogram. This should only * be called after a sync pass has completely finished since the on-disk * information is updated in metaslab_sync(). */ static uint64_t metaslab_weight_from_spacemap(metaslab_t *msp) { uint64_t weight = 0; for (int i = SPACE_MAP_HISTOGRAM_SIZE - 1; i >= 0; i--) { if (msp->ms_sm->sm_phys->smp_histogram[i] != 0) { WEIGHT_SET_COUNT(weight, msp->ms_sm->sm_phys->smp_histogram[i]); WEIGHT_SET_INDEX(weight, i + msp->ms_sm->sm_shift); WEIGHT_SET_ACTIVE(weight, 0); break; } } return (weight); } /* * Compute a segment-based weight for the specified metaslab. The weight * is determined by highest bucket in the histogram. The information * for the highest bucket is encoded into the weight value. */ static uint64_t metaslab_segment_weight(metaslab_t *msp) { metaslab_group_t *mg = msp->ms_group; uint64_t weight = 0; uint8_t shift = mg->mg_vd->vdev_ashift; ASSERT(MUTEX_HELD(&msp->ms_lock)); /* * The metaslab is completely free. */ if (space_map_allocated(msp->ms_sm) == 0) { int idx = highbit64(msp->ms_size) - 1; int max_idx = SPACE_MAP_HISTOGRAM_SIZE + shift - 1; if (idx < max_idx) { WEIGHT_SET_COUNT(weight, 1ULL); WEIGHT_SET_INDEX(weight, idx); } else { WEIGHT_SET_COUNT(weight, 1ULL << (idx - max_idx)); WEIGHT_SET_INDEX(weight, max_idx); } WEIGHT_SET_ACTIVE(weight, 0); ASSERT(!WEIGHT_IS_SPACEBASED(weight)); return (weight); } ASSERT3U(msp->ms_sm->sm_dbuf->db_size, ==, sizeof (space_map_phys_t)); /* * If the metaslab is fully allocated then just make the weight 0. */ if (space_map_allocated(msp->ms_sm) == msp->ms_size) return (0); /* * If the metaslab is already loaded, then use the range tree to * determine the weight. Otherwise, we rely on the space map information * to generate the weight. */ if (msp->ms_loaded) { weight = metaslab_weight_from_range_tree(msp); } else { weight = metaslab_weight_from_spacemap(msp); } /* * If the metaslab was active the last time we calculated its weight * then keep it active. We want to consume the entire region that * is associated with this weight. */ if (msp->ms_activation_weight != 0 && weight != 0) WEIGHT_SET_ACTIVE(weight, WEIGHT_GET_ACTIVE(msp->ms_weight)); return (weight); } /* * Determine if we should attempt to allocate from this metaslab. If the * metaslab has a maximum size then we can quickly determine if the desired * allocation size can be satisfied. Otherwise, if we're using segment-based * weighting then we can determine the maximum allocation that this metaslab * can accommodate based on the index encoded in the weight. If we're using * space-based weights then rely on the entire weight (excluding the weight * type bit). */ boolean_t metaslab_should_allocate(metaslab_t *msp, uint64_t asize) { boolean_t should_allocate; if (msp->ms_max_size != 0) return (msp->ms_max_size >= asize); if (!WEIGHT_IS_SPACEBASED(msp->ms_weight)) { /* * The metaslab segment weight indicates segments in the * range [2^i, 2^(i+1)), where i is the index in the weight. * Since the asize might be in the middle of the range, we * should attempt the allocation if asize < 2^(i+1). */ should_allocate = (asize < 1ULL << (WEIGHT_GET_INDEX(msp->ms_weight) + 1)); } else { should_allocate = (asize <= (msp->ms_weight & ~METASLAB_WEIGHT_TYPE)); } return (should_allocate); } static uint64_t metaslab_weight(metaslab_t *msp) { vdev_t *vd = msp->ms_group->mg_vd; spa_t *spa = vd->vdev_spa; uint64_t weight; 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); } metaslab_set_fragmentation(msp); /* * Update the maximum size if the metaslab is loaded. This will * ensure that we get an accurate maximum size if newly freed space * has been added back into the free tree. */ if (msp->ms_loaded) msp->ms_max_size = metaslab_block_maxsize(msp); /* * Segment-based weighting requires space map histogram support. */ if (zfs_metaslab_segment_weight_enabled && spa_feature_is_enabled(spa, SPA_FEATURE_SPACEMAP_HISTOGRAM) && (msp->ms_sm == NULL || msp->ms_sm->sm_dbuf->db_size == sizeof (space_map_phys_t))) { weight = metaslab_segment_weight(msp); } else { weight = metaslab_space_weight(msp); } 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); } } msp->ms_activation_weight = msp->ms_weight; 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 weight) { uint64_t size = weight & ~METASLAB_WEIGHT_TYPE; /* * 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); ASSERT0(weight & METASLAB_ACTIVE_MASK); msp->ms_activation_weight = 0; metaslab_group_sort(msp->ms_group, msp, weight); ASSERT((msp->ms_weight & METASLAB_ACTIVE_MASK) == 0); } /* * Segment-based metaslabs are activated once and remain active until * we either fail an allocation attempt (similar to space-based metaslabs) * or have exhausted the free space in zfs_metaslab_switch_threshold * buckets since the metaslab was activated. This function checks to see * if we've exhaused the zfs_metaslab_switch_threshold buckets in the * metaslab and passivates it proactively. This will allow us to select a * metaslabs with larger contiguous region if any remaining within this * metaslab group. If we're in sync pass > 1, then we continue using this * metaslab so that we don't dirty more block and cause more sync passes. */ void metaslab_segment_may_passivate(metaslab_t *msp) { spa_t *spa = msp->ms_group->mg_vd->vdev_spa; if (WEIGHT_IS_SPACEBASED(msp->ms_weight) || spa_sync_pass(spa) > 1) return; /* * Since we are in the middle of a sync pass, the most accurate * information that is accessible to us is the in-core range tree * histogram; calculate the new weight based on that information. */ uint64_t weight = metaslab_weight_from_range_tree(msp); int activation_idx = WEIGHT_GET_INDEX(msp->ms_activation_weight); int current_idx = WEIGHT_GET_INDEX(weight); if (current_idx <= activation_idx - zfs_metaslab_switch_threshold) metaslab_passivate(msp, weight); } static void metaslab_preload(void *arg) { metaslab_t *msp = arg; spa_t *spa = msp->ms_group->mg_vd->vdev_spa; ASSERT(!MUTEX_HELD(&msp->ms_group->mg_lock)); mutex_enter(&msp->ms_lock); metaslab_load_wait(msp); if (!msp->ms_loaded) (void) metaslab_load(msp); msp->ms_selected_txg = spa_syncing_txg(spa); 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); /* * Load the next potential metaslabs */ for (msp = avl_first(t); msp != NULL; msp = AVL_NEXT(t, msp)) { /* * We preload only the maximum number of metaslabs specified * by metaslab_preload_limit. If a metaslab is being forced * to condense then we preload it too. This will ensure * that force condensing happens in the next txg. */ if (++m > metaslab_preload_limit && !msp->ms_condense_wanted) { continue; } 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). * * 3. The on-disk size of the space map should actually decrease. * * 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. * * Unfortunately, we cannot compute the on-disk size of the space map in this * context because we cannot accurately compute the effects of compression, etc. * Instead, we apply the heuristic described in the block comment for * zfs_metaslab_condense_block_threshold - we only condense if the space used * is greater than a threshold number of blocks. */ 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, object_size, optimal_size, record_size; dmu_object_info_t doi; uint64_t vdev_blocksize = 1 << msp->ms_group->mg_vd->vdev_ashift; 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. We always condense * metaslabs that are empty and metaslabs for which a condense * request has been made. */ rs = avl_last(&msp->ms_size_tree); if (rs == NULL || msp->ms_condense_wanted) 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); optimal_size = sizeof (uint64_t) * avl_numnodes(&msp->ms_tree->rt_root); object_size = space_map_length(msp->ms_sm); dmu_object_info_from_db(sm->sm_dbuf, &doi); record_size = MAX(doi.doi_data_block_size, vdev_blocksize); return (segsz <= object_size && object_size >= (optimal_size * zfs_condense_pct / 100) && object_size > zfs_metaslab_condense_block_threshold * record_size); } /* * 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, vdev id %llu, " "spa %s, smp size %llu, segments %lu, forcing condense=%s", txg, msp->ms_id, msp, msp->ms_group->mg_vd->vdev_id, msp->ms_group->mg_vd->vdev_spa->spa_name, space_map_length(msp->ms_sm), avl_numnodes(&msp->ms_tree->rt_root), msp->ms_condense_wanted ? "TRUE" : "FALSE"); msp->ms_condense_wanted = B_FALSE; /* * 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. + * this txg are in the freeingtree. */ - range_tree_walk(freetree, range_tree_remove, condense_tree); + range_tree_walk(msp->ms_freeingtree, 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) { + if (msp->ms_freeingtree == NULL) { ASSERT3P(alloctree, ==, NULL); return; } ASSERT3P(alloctree, !=, NULL); - ASSERT3P(*freetree, !=, NULL); - ASSERT3P(*freed_tree, !=, NULL); + ASSERT3P(msp->ms_freeingtree, !=, NULL); + ASSERT3P(msp->ms_freedtree, !=, NULL); /* * Normally, we don't want to process a metaslab if there * are no allocations or frees to perform. However, if the metaslab * is being forced to condense we need to let it through. */ if (range_tree_space(alloctree) == 0 && - range_tree_space(*freetree) == 0 && + range_tree_space(msp->ms_freeingtree) == 0 && !msp->ms_condense_wanted) 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 + * be modifying this txg's alloctree, freeingtree, freedtree, 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); /* * Note: metaslab_condense() clears the space map's histogram. * Therefore we must verify and remove this histogram before * condensing. */ metaslab_group_histogram_verify(mg); metaslab_class_histogram_verify(mg->mg_class); metaslab_group_histogram_remove(mg, msp); 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); + space_map_write(msp->ms_sm, msp->ms_freeingtree, SM_FREE, tx); } 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); /* * Since we've cleared the histogram we need to add back * any free space that has already been processed, plus * any deferred space. This allows the on-disk histogram * to accurately reflect all free space even if some space * is not yet available for allocation (i.e. deferred). */ - space_map_histogram_add(msp->ms_sm, *freed_tree, tx); + space_map_histogram_add(msp->ms_sm, msp->ms_freedtree, tx); /* * Add back any deferred free space that has not been * added back into the in-core free tree yet. This will * ensure that we don't end up with a space map histogram * that is completely empty unless the metaslab is fully * allocated. */ for (int t = 0; t < TXG_DEFER_SIZE; t++) { space_map_histogram_add(msp->ms_sm, msp->ms_defertree[t], tx); } } /* * Always add the free space from this sync pass to the space * map histogram. We want to make sure that the on-disk histogram * accounts for all free space. If the space map is not loaded, * then we will lose some accuracy but will correct it the next * time we load the space map. */ - space_map_histogram_add(msp->ms_sm, *freetree, tx); + space_map_histogram_add(msp->ms_sm, msp->ms_freeingtree, tx); metaslab_group_histogram_add(mg, msp); metaslab_group_histogram_verify(mg); metaslab_class_histogram_verify(mg->mg_class); /* * 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 + * and instead will just swap the pointers for freeingtree and + * freedtree. 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); + range_tree_swap(&msp->ms_freeingtree, &msp->ms_freedtree); } else { - range_tree_vacate(*freetree, range_tree_add, *freed_tree); + range_tree_vacate(msp->ms_freeingtree, + range_tree_add, msp->ms_freedtree); } range_tree_vacate(alloctree, NULL, NULL); ASSERT0(range_tree_space(msp->ms_alloctree[txg & TXG_MASK])); ASSERT0(range_tree_space(msp->ms_alloctree[TXG_CLEAN(txg) & TXG_MASK])); - ASSERT0(range_tree_space(msp->ms_freetree[txg & TXG_MASK])); + ASSERT0(range_tree_space(msp->ms_freeingtree)); 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; spa_t *spa = vd->vdev_spa; - range_tree_t **freed_tree; range_tree_t **defer_tree; int64_t alloc_delta, defer_delta; boolean_t defer_allowed = B_TRUE; 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. + * range trees and add its capacity to the vdev. */ - if (msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK] == NULL) { + if (msp->ms_freedtree == 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); } + ASSERT3P(msp->ms_freeingtree, ==, NULL); + msp->ms_freeingtree = range_tree_create(NULL, msp, + &msp->ms_lock); + + ASSERT3P(msp->ms_freedtree, ==, NULL); + msp->ms_freedtree = 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]; uint64_t free_space = metaslab_class_get_space(spa_normal_class(spa)) - metaslab_class_get_alloc(spa_normal_class(spa)); if (free_space <= spa_get_slop_space(spa)) { defer_allowed = B_FALSE; } defer_delta = 0; alloc_delta = space_map_alloc_delta(msp->ms_sm); if (defer_allowed) { - defer_delta = range_tree_space(*freed_tree) - + defer_delta = range_tree_space(msp->ms_freedtree) - range_tree_space(*defer_tree); } else { defer_delta -= 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); if (defer_allowed) { - range_tree_swap(freed_tree, defer_tree); + range_tree_swap(&msp->ms_freedtree, defer_tree); } else { - range_tree_vacate(*freed_tree, + range_tree_vacate(msp->ms_freedtree, msp->ms_loaded ? range_tree_add : NULL, msp->ms_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); } /* * Calculate the new weights before unloading any metaslabs. * This will give us the most accurate weighting. */ metaslab_group_sort(mg, msp, metaslab_weight(msp)); /* * If the metaslab is loaded and we've not tried to load or allocate * from it in 'metaslab_unload_delay' txgs, then unload it. */ if (msp->ms_loaded && msp->ms_selected_txg + metaslab_unload_delay < 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); } mutex_exit(&msp->ms_lock); } void metaslab_sync_reassess(metaslab_group_t *mg) { metaslab_group_alloc_update(mg); mg->mg_fragmentation = metaslab_group_fragmentation(mg); /* * 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); } /* * ========================================================================== * Metaslab allocation tracing facility * ========================================================================== */ kstat_t *metaslab_trace_ksp; kstat_named_t metaslab_trace_over_limit; void metaslab_alloc_trace_init(void) { ASSERT(metaslab_alloc_trace_cache == NULL); metaslab_alloc_trace_cache = kmem_cache_create( "metaslab_alloc_trace_cache", sizeof (metaslab_alloc_trace_t), 0, NULL, NULL, NULL, NULL, NULL, 0); metaslab_trace_ksp = kstat_create("zfs", 0, "metaslab_trace_stats", "misc", KSTAT_TYPE_NAMED, 1, KSTAT_FLAG_VIRTUAL); if (metaslab_trace_ksp != NULL) { metaslab_trace_ksp->ks_data = &metaslab_trace_over_limit; kstat_named_init(&metaslab_trace_over_limit, "metaslab_trace_over_limit", KSTAT_DATA_UINT64); kstat_install(metaslab_trace_ksp); } } void metaslab_alloc_trace_fini(void) { if (metaslab_trace_ksp != NULL) { kstat_delete(metaslab_trace_ksp); metaslab_trace_ksp = NULL; } kmem_cache_destroy(metaslab_alloc_trace_cache); metaslab_alloc_trace_cache = NULL; } /* * Add an allocation trace element to the allocation tracing list. */ static void metaslab_trace_add(zio_alloc_list_t *zal, metaslab_group_t *mg, metaslab_t *msp, uint64_t psize, uint32_t dva_id, uint64_t offset) { if (!metaslab_trace_enabled) return; /* * When the tracing list reaches its maximum we remove * the second element in the list before adding a new one. * By removing the second element we preserve the original * entry as a clue to what allocations steps have already been * performed. */ if (zal->zal_size == metaslab_trace_max_entries) { metaslab_alloc_trace_t *mat_next; #ifdef DEBUG panic("too many entries in allocation list"); #endif atomic_inc_64(&metaslab_trace_over_limit.value.ui64); zal->zal_size--; mat_next = list_next(&zal->zal_list, list_head(&zal->zal_list)); list_remove(&zal->zal_list, mat_next); kmem_cache_free(metaslab_alloc_trace_cache, mat_next); } metaslab_alloc_trace_t *mat = kmem_cache_alloc(metaslab_alloc_trace_cache, KM_SLEEP); list_link_init(&mat->mat_list_node); mat->mat_mg = mg; mat->mat_msp = msp; mat->mat_size = psize; mat->mat_dva_id = dva_id; mat->mat_offset = offset; mat->mat_weight = 0; if (msp != NULL) mat->mat_weight = msp->ms_weight; /* * The list is part of the zio so locking is not required. Only * a single thread will perform allocations for a given zio. */ list_insert_tail(&zal->zal_list, mat); zal->zal_size++; ASSERT3U(zal->zal_size, <=, metaslab_trace_max_entries); } void metaslab_trace_init(zio_alloc_list_t *zal) { list_create(&zal->zal_list, sizeof (metaslab_alloc_trace_t), offsetof(metaslab_alloc_trace_t, mat_list_node)); zal->zal_size = 0; } void metaslab_trace_fini(zio_alloc_list_t *zal) { metaslab_alloc_trace_t *mat; while ((mat = list_remove_head(&zal->zal_list)) != NULL) kmem_cache_free(metaslab_alloc_trace_cache, mat); list_destroy(&zal->zal_list); zal->zal_size = 0; } /* * ========================================================================== * Metaslab block operations * ========================================================================== */ static void metaslab_group_alloc_increment(spa_t *spa, uint64_t vdev, void *tag, int flags) { if (!(flags & METASLAB_ASYNC_ALLOC) || flags & METASLAB_DONT_THROTTLE) return; metaslab_group_t *mg = vdev_lookup_top(spa, vdev)->vdev_mg; if (!mg->mg_class->mc_alloc_throttle_enabled) return; (void) refcount_add(&mg->mg_alloc_queue_depth, tag); } void metaslab_group_alloc_decrement(spa_t *spa, uint64_t vdev, void *tag, int flags) { if (!(flags & METASLAB_ASYNC_ALLOC) || flags & METASLAB_DONT_THROTTLE) return; metaslab_group_t *mg = vdev_lookup_top(spa, vdev)->vdev_mg; if (!mg->mg_class->mc_alloc_throttle_enabled) return; (void) refcount_remove(&mg->mg_alloc_queue_depth, tag); } void metaslab_group_alloc_verify(spa_t *spa, const blkptr_t *bp, void *tag) { #ifdef ZFS_DEBUG const dva_t *dva = bp->blk_dva; int ndvas = BP_GET_NDVAS(bp); for (int d = 0; d < ndvas; d++) { uint64_t vdev = DVA_GET_VDEV(&dva[d]); metaslab_group_t *mg = vdev_lookup_top(spa, vdev)->vdev_mg; VERIFY(refcount_not_held(&mg->mg_alloc_queue_depth, tag)); } #endif } static uint64_t metaslab_block_alloc(metaslab_t *msp, uint64_t size, uint64_t txg) { uint64_t start; range_tree_t *rt = msp->ms_tree; metaslab_class_t *mc = msp->ms_group->mg_class; VERIFY(!msp->ms_condensing); start = mc->mc_ops->msop_alloc(msp, size); if (start != -1ULL) { metaslab_group_t *mg = msp->ms_group; vdev_t *vd = mg->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); 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], start, size); /* Track the last successful allocation */ msp->ms_alloc_txg = txg; metaslab_verify_space(msp, txg); } /* * Now that we've attempted the allocation we need to update the * metaslab's maximum block size since it may have changed. */ msp->ms_max_size = metaslab_block_maxsize(msp); return (start); } static uint64_t metaslab_group_alloc_normal(metaslab_group_t *mg, zio_alloc_list_t *zal, uint64_t asize, uint64_t txg, uint64_t min_distance, dva_t *dva, int d) { metaslab_t *msp = NULL; uint64_t offset = -1ULL; 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; } } metaslab_t *search = kmem_alloc(sizeof (*search), KM_SLEEP); search->ms_weight = UINT64_MAX; search->ms_start = 0; for (;;) { boolean_t was_active; avl_tree_t *t = &mg->mg_metaslab_tree; avl_index_t idx; mutex_enter(&mg->mg_lock); /* * Find the metaslab with the highest weight that is less * than what we've already tried. In the common case, this * means that we will examine each metaslab at most once. * Note that concurrent callers could reorder metaslabs * by activation/passivation once we have dropped the mg_lock. * If a metaslab is activated by another thread, and we fail * to allocate from the metaslab we have selected, we may * not try the newly-activated metaslab, and instead activate * another metaslab. This is not optimal, but generally * does not cause any problems (a possible exception being * if every metaslab is completely full except for the * the newly-activated metaslab which we fail to examine). */ msp = avl_find(t, search, &idx); if (msp == NULL) msp = avl_nearest(t, idx, AVL_AFTER); for (; msp != NULL; msp = AVL_NEXT(t, msp)) { if (!metaslab_should_allocate(msp, asize)) { metaslab_trace_add(zal, mg, msp, asize, d, TRACE_TOO_SMALL); continue; } /* * 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) { kmem_free(search, sizeof (*search)); return (-1ULL); } search->ms_weight = msp->ms_weight; search->ms_start = msp->ms_start + 1; 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. We check the * active status first to see if we need to reselect * a new metaslab. */ if (was_active && !(msp->ms_weight & METASLAB_ACTIVE_MASK)) { 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; } msp->ms_selected_txg = txg; /* * Now that we have the lock, recheck to see if we should * continue to use this metaslab for this allocation. The * the metaslab is now loaded so metaslab_should_allocate() can * accurately determine if the allocation attempt should * proceed. */ if (!metaslab_should_allocate(msp, asize)) { /* Passivate this metaslab and select a new one. */ metaslab_trace_add(zal, mg, msp, asize, d, TRACE_TOO_SMALL); goto next; } /* * 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) { metaslab_trace_add(zal, mg, msp, asize, d, TRACE_CONDENSING); mutex_exit(&msp->ms_lock); continue; } offset = metaslab_block_alloc(msp, asize, txg); metaslab_trace_add(zal, mg, msp, asize, d, offset); if (offset != -1ULL) { /* Proactively passivate the metaslab, if needed */ metaslab_segment_may_passivate(msp); break; } next: ASSERT(msp->ms_loaded); /* * We were unable to allocate from this metaslab so determine * a new weight for this metaslab. Now that we have loaded * the metaslab we can provide a better hint to the metaslab * selector. * * For space-based metaslabs, we use the maximum block size. * This information is only available when the metaslab * is loaded and is more accurate than the generic free * space weight that was calculated by metaslab_weight(). * This information allows us to quickly compare the maximum * available allocation in the metaslab to the allocation * size being requested. * * For segment-based metaslabs, determine the new weight * based on the highest bucket in the range tree. We * explicitly use the loaded segment weight (i.e. the range * tree histogram) since it contains the space that is * currently available for allocation and is accurate * even within a sync pass. */ if (WEIGHT_IS_SPACEBASED(msp->ms_weight)) { uint64_t weight = metaslab_block_maxsize(msp); WEIGHT_SET_SPACEBASED(weight); metaslab_passivate(msp, weight); } else { metaslab_passivate(msp, metaslab_weight_from_range_tree(msp)); } /* * We have just failed an allocation attempt, check * that metaslab_should_allocate() agrees. Otherwise, * we may end up in an infinite loop retrying the same * metaslab. */ ASSERT(!metaslab_should_allocate(msp, asize)); mutex_exit(&msp->ms_lock); } mutex_exit(&msp->ms_lock); kmem_free(search, sizeof (*search)); return (offset); } static uint64_t metaslab_group_alloc(metaslab_group_t *mg, zio_alloc_list_t *zal, uint64_t asize, uint64_t txg, uint64_t min_distance, dva_t *dva, int d) { uint64_t offset; ASSERT(mg->mg_initialized); offset = metaslab_group_alloc_normal(mg, zal, asize, txg, min_distance, dva, d); mutex_enter(&mg->mg_lock); if (offset == -1ULL) { mg->mg_failed_allocations++; metaslab_trace_add(zal, mg, NULL, asize, d, TRACE_GROUP_FAILURE); if (asize == SPA_GANGBLOCKSIZE) { /* * This metaslab group was unable to allocate * the minimum gang block size so it must be out of * space. We must notify the allocation throttle * to start skipping allocation attempts to this * metaslab group until more space becomes available. * Note: this failure cannot be caused by the * allocation throttle since the allocation throttle * is only responsible for skipping devices and * not failing block allocations. */ mg->mg_no_free_space = B_TRUE; } } mg->mg_allocations++; mutex_exit(&mg->mg_lock); return (offset); } /* * If we have to write a ditto block (i.e. more than one DVA for a given BP) * on the same vdev as an existing DVA of this BP, then try to allocate it * at least (vdev_asize / (2 ^ ditto_same_vdev_distance_shift)) away from the * existing DVAs. */ int ditto_same_vdev_distance_shift = 3; /* * 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, zio_alloc_list_t *zal) { metaslab_group_t *mg, *rotor; vdev_t *vd; boolean_t try_hard = B_FALSE; 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) { metaslab_trace_add(zal, NULL, NULL, psize, d, TRACE_FORCE_GANG); 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: do { boolean_t allocatable; ASSERT(mg->mg_activation_count == 1); vd = mg->mg_vd; /* * Don't allocate from faulted devices. */ if (try_hard) { 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 then don't allow * this metaslab group to skip allocations since that would * inadvertently return ENOSPC and suspend the pool * even though space is still available. */ if (allocatable && !GANG_ALLOCATION(flags) && !try_hard) { allocatable = metaslab_group_allocatable(mg, rotor, psize); } if (!allocatable) { metaslab_trace_add(zal, mg, NULL, psize, d, TRACE_NOT_ALLOCATABLE); goto next; } ASSERT(mg->mg_initialized); /* * Avoid writing single-copy data to a failing, * non-redundant vdev, unless we've already tried all * other vdevs. */ if ((vd->vdev_stat.vs_write_errors > 0 || vd->vdev_state < VDEV_STATE_HEALTHY) && d == 0 && !try_hard && vd->vdev_children == 0) { metaslab_trace_add(zal, mg, NULL, psize, d, TRACE_VDEV_ERROR); goto next; } ASSERT(mg->mg_class == mc); /* * If we don't need to try hard, then require that the * block be 1/8th of the device away from any other DVAs * in this BP. If we are trying hard, allow any offset * to be used (distance=0). */ uint64_t distance = 0; if (!try_hard) { distance = vd->vdev_asize >> ditto_same_vdev_distance_shift; if (distance <= (1ULL << vd->vdev_ms_shift)) distance = 0; } uint64_t asize = vdev_psize_to_asize(vd, psize); ASSERT(P2PHASE(asize, 1ULL << vd->vdev_ashift) == 0); uint64_t offset = metaslab_group_alloc(mg, zal, asize, txg, distance, dva, d); 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 && metaslab_bias_enabled) { 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; } else if (!metaslab_bias_enabled) { mg->mg_bias = 0; } 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 we haven't tried hard, do so now. */ if (!try_hard) { try_hard = B_TRUE; goto top; } bzero(&dva[d], sizeof (dva_t)); metaslab_trace_add(zal, rotor, NULL, psize, d, TRACE_ENOSPC); 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); msp->ms_max_size = metaslab_block_maxsize(msp); } else { - if (range_tree_space(msp->ms_freetree[txg & TXG_MASK]) == 0) + VERIFY3U(txg, ==, spa->spa_syncing_txg); + if (range_tree_space(msp->ms_freeingtree) == 0) vdev_dirty(vd, VDD_METASLAB, msp, txg); - range_tree_add(msp->ms_freetree[txg & TXG_MASK], - offset, size); + range_tree_add(msp->ms_freeingtree, 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); } /* * Reserve some allocation slots. The reservation system must be called * before we call into the allocator. If there aren't any available slots * then the I/O will be throttled until an I/O completes and its slots are * freed up. The function returns true if it was successful in placing * the reservation. */ boolean_t metaslab_class_throttle_reserve(metaslab_class_t *mc, int slots, zio_t *zio, int flags) { uint64_t available_slots = 0; boolean_t slot_reserved = B_FALSE; ASSERT(mc->mc_alloc_throttle_enabled); mutex_enter(&mc->mc_lock); uint64_t reserved_slots = refcount_count(&mc->mc_alloc_slots); if (reserved_slots < mc->mc_alloc_max_slots) available_slots = mc->mc_alloc_max_slots - reserved_slots; if (slots <= available_slots || GANG_ALLOCATION(flags)) { /* * We reserve the slots individually so that we can unreserve * them individually when an I/O completes. */ for (int d = 0; d < slots; d++) { reserved_slots = refcount_add(&mc->mc_alloc_slots, zio); } zio->io_flags |= ZIO_FLAG_IO_ALLOCATING; slot_reserved = B_TRUE; } mutex_exit(&mc->mc_lock); return (slot_reserved); } void metaslab_class_throttle_unreserve(metaslab_class_t *mc, int slots, zio_t *zio) { ASSERT(mc->mc_alloc_throttle_enabled); mutex_enter(&mc->mc_lock); for (int d = 0; d < slots; d++) { (void) refcount_remove(&mc->mc_alloc_slots, zio); } mutex_exit(&mc->mc_lock); } 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, zio_alloc_list_t *zal, zio_t *zio) { 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)); ASSERT3P(zal, !=, NULL); for (int d = 0; d < ndvas; d++) { error = metaslab_alloc_dva(spa, mc, psize, dva, d, hintdva, txg, flags, zal); if (error != 0) { for (d--; d >= 0; d--) { metaslab_free_dva(spa, &dva[d], txg, B_TRUE); metaslab_group_alloc_decrement(spa, DVA_GET_VDEV(&dva[d]), zio, flags); bzero(&dva[d], sizeof (dva_t)); } spa_config_exit(spa, SCL_ALLOC, FTAG); return (error); } else { /* * Update the metaslab group's queue depth * based on the newly allocated dva. */ metaslab_group_alloc_increment(spa, DVA_GET_VDEV(&dva[d]), zio, flags); } } 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); + range_tree_verify(msp->ms_freeingtree, offset, size); + range_tree_verify(msp->ms_freedtree, 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); } Index: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/metaslab_impl.h =================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/metaslab_impl.h (revision 317526) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/metaslab_impl.h (revision 317527) @@ -1,365 +1,376 @@ /* * 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 2009 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ /* * Copyright (c) 2011, 2015 by Delphix. All rights reserved. */ #ifndef _SYS_METASLAB_IMPL_H #define _SYS_METASLAB_IMPL_H #include #include #include #include #include #include #ifdef __cplusplus extern "C" { #endif /* * Metaslab allocation tracing record. */ typedef struct metaslab_alloc_trace { list_node_t mat_list_node; metaslab_group_t *mat_mg; metaslab_t *mat_msp; uint64_t mat_size; uint64_t mat_weight; uint32_t mat_dva_id; uint64_t mat_offset; } metaslab_alloc_trace_t; /* * Used by the metaslab allocation tracing facility to indicate * error conditions. These errors are stored to the offset member * of the metaslab_alloc_trace_t record and displayed by mdb. */ typedef enum trace_alloc_type { TRACE_ALLOC_FAILURE = -1ULL, TRACE_TOO_SMALL = -2ULL, TRACE_FORCE_GANG = -3ULL, TRACE_NOT_ALLOCATABLE = -4ULL, TRACE_GROUP_FAILURE = -5ULL, TRACE_ENOSPC = -6ULL, TRACE_CONDENSING = -7ULL, TRACE_VDEV_ERROR = -8ULL } trace_alloc_type_t; #define METASLAB_WEIGHT_PRIMARY (1ULL << 63) #define METASLAB_WEIGHT_SECONDARY (1ULL << 62) #define METASLAB_WEIGHT_TYPE (1ULL << 61) #define METASLAB_ACTIVE_MASK \ (METASLAB_WEIGHT_PRIMARY | METASLAB_WEIGHT_SECONDARY) /* * The metaslab weight is used to encode the amount of free space in a * metaslab, such that the "best" metaslab appears first when sorting the * metaslabs by weight. The weight (and therefore the "best" metaslab) can * be determined in two different ways: by computing a weighted sum of all * the free space in the metaslab (a space based weight) or by counting only * the free segments of the largest size (a segment based weight). We prefer * the segment based weight because it reflects how the free space is * comprised, but we cannot always use it -- legacy pools do not have the * space map histogram information necessary to determine the largest * contiguous regions. Pools that have the space map histogram determine * the segment weight by looking at each bucket in the histogram and * determining the free space whose size in bytes is in the range: * [2^i, 2^(i+1)) * We then encode the largest index, i, that contains regions into the * segment-weighted value. * * Space-based weight: * * 64 56 48 40 32 24 16 8 0 * +-------+-------+-------+-------+-------+-------+-------+-------+ * |PS1| weighted-free space | * +-------+-------+-------+-------+-------+-------+-------+-------+ * * PS - indicates primary and secondary activation * space - the fragmentation-weighted space * * Segment-based weight: * * 64 56 48 40 32 24 16 8 0 * +-------+-------+-------+-------+-------+-------+-------+-------+ * |PS0| idx| count of segments in region | * +-------+-------+-------+-------+-------+-------+-------+-------+ * * PS - indicates primary and secondary activation * idx - index for the highest bucket in the histogram * count - number of segments in the specified bucket */ #define WEIGHT_GET_ACTIVE(weight) BF64_GET((weight), 62, 2) #define WEIGHT_SET_ACTIVE(weight, x) BF64_SET((weight), 62, 2, x) #define WEIGHT_IS_SPACEBASED(weight) \ ((weight) == 0 || BF64_GET((weight), 61, 1)) #define WEIGHT_SET_SPACEBASED(weight) BF64_SET((weight), 61, 1, 1) /* * These macros are only applicable to segment-based weighting. */ #define WEIGHT_GET_INDEX(weight) BF64_GET((weight), 55, 6) #define WEIGHT_SET_INDEX(weight, x) BF64_SET((weight), 55, 6, x) #define WEIGHT_GET_COUNT(weight) BF64_GET((weight), 0, 55) #define WEIGHT_SET_COUNT(weight, x) BF64_SET((weight), 0, 55, x) /* * A metaslab class encompasses a category of allocatable top-level vdevs. * Each top-level vdev is associated with a metaslab group which defines * the allocatable region for that vdev. Examples of these categories include * "normal" for data block allocations (i.e. main pool allocations) or "log" * for allocations designated for intent log devices (i.e. slog devices). * When a block allocation is requested from the SPA it is associated with a * metaslab_class_t, and only top-level vdevs (i.e. metaslab groups) belonging * to the class can be used to satisfy that request. Allocations are done * by traversing the metaslab groups that are linked off of the mc_rotor field. * This rotor points to the next metaslab group where allocations will be * attempted. Allocating a block is a 3 step process -- select the metaslab * group, select the metaslab, and then allocate the block. The metaslab * class defines the low-level block allocator that will be used as the * final step in allocation. These allocators are pluggable allowing each class * to use a block allocator that best suits that class. */ struct metaslab_class { kmutex_t mc_lock; spa_t *mc_spa; metaslab_group_t *mc_rotor; metaslab_ops_t *mc_ops; uint64_t mc_aliquot; /* * Track the number of metaslab groups that have been initialized * and can accept allocations. An initialized metaslab group is * one has been completely added to the config (i.e. we have * updated the MOS config and the space has been added to the pool). */ uint64_t mc_groups; /* * Toggle to enable/disable the allocation throttle. */ boolean_t mc_alloc_throttle_enabled; /* * The allocation throttle works on a reservation system. Whenever * an asynchronous zio wants to perform an allocation it must * first reserve the number of blocks that it wants to allocate. * If there aren't sufficient slots available for the pending zio * then that I/O is throttled until more slots free up. The current * number of reserved allocations is maintained by the mc_alloc_slots * refcount. The mc_alloc_max_slots value determines the maximum * number of allocations that the system allows. Gang blocks are * allowed to reserve slots even if we've reached the maximum * number of allocations allowed. */ uint64_t mc_alloc_max_slots; refcount_t mc_alloc_slots; uint64_t mc_alloc_groups; /* # of allocatable groups */ uint64_t mc_alloc; /* total allocated space */ uint64_t mc_deferred; /* total deferred frees */ uint64_t mc_space; /* total space (alloc + free) */ uint64_t mc_dspace; /* total deflated space */ uint64_t mc_minblocksize; uint64_t mc_histogram[RANGE_TREE_HISTOGRAM_SIZE]; }; /* * Metaslab groups encapsulate all the allocatable regions (i.e. metaslabs) * of a top-level vdev. They are linked togther to form a circular linked * list and can belong to only one metaslab class. Metaslab groups may become * ineligible for allocations for a number of reasons such as limited free * space, fragmentation, or going offline. When this happens the allocator will * simply find the next metaslab group in the linked list and attempt * to allocate from that group instead. */ struct metaslab_group { kmutex_t mg_lock; avl_tree_t mg_metaslab_tree; uint64_t mg_aliquot; boolean_t mg_allocatable; /* can we allocate? */ /* * A metaslab group is considered to be initialized only after * we have updated the MOS config and added the space to the pool. * We only allow allocation attempts to a metaslab group if it * has been initialized. */ boolean_t mg_initialized; uint64_t mg_free_capacity; /* percentage free */ int64_t mg_bias; int64_t mg_activation_count; metaslab_class_t *mg_class; vdev_t *mg_vd; taskq_t *mg_taskq; metaslab_group_t *mg_prev; metaslab_group_t *mg_next; /* * Each metaslab group can handle mg_max_alloc_queue_depth allocations * which are tracked by mg_alloc_queue_depth. It's possible for a * metaslab group to handle more allocations than its max. This * can occur when gang blocks are required or when other groups * are unable to handle their share of allocations. */ uint64_t mg_max_alloc_queue_depth; refcount_t mg_alloc_queue_depth; /* * A metalab group that can no longer allocate the minimum block * size will set mg_no_free_space. Once a metaslab group is out * of space then its share of work must be distributed to other * groups. */ boolean_t mg_no_free_space; uint64_t mg_allocations; uint64_t mg_failed_allocations; uint64_t mg_fragmentation; uint64_t mg_histogram[RANGE_TREE_HISTOGRAM_SIZE]; }; /* * This value defines the number of elements in the ms_lbas array. The value * of 64 was chosen as it covers all power of 2 buckets up to UINT64_MAX. * This is the equivalent of highbit(UINT64_MAX). */ #define MAX_LBAS 64 /* - * Each metaslab maintains a set of in-core trees to track metaslab operations. - * The in-core free tree (ms_tree) contains the current list of free segments. - * As blocks are allocated, the allocated segment are removed from the ms_tree - * and added to a per txg allocation tree (ms_alloctree). As blocks are freed, - * they are added to the per txg free tree (ms_freetree). These per txg - * trees allow us to process all allocations and frees in syncing context - * where it is safe to update the on-disk space maps. One additional in-core - * tree is maintained to track deferred frees (ms_defertree). Once a block - * is freed it will move from the ms_freetree to the ms_defertree. A deferred - * free means that a block has been freed but cannot be used by the pool - * until TXG_DEFER_SIZE transactions groups later. For example, a block - * that is freed in txg 50 will not be available for reallocation until - * txg 52 (50 + TXG_DEFER_SIZE). This provides a safety net for uberblock - * rollback. A pool could be safely rolled back TXG_DEFERS_SIZE - * transactions groups and ensure that no block has been reallocated. + * Each metaslab maintains a set of in-core trees to track metaslab + * operations. The in-core free tree (ms_tree) contains the list of + * free segments which are eligible for allocation. As blocks are + * allocated, the allocated segments are removed from the ms_tree and + * added to a per txg allocation tree (ms_alloctree). This allows us to + * process all allocations in syncing context where it is safe to update + * the on-disk space maps. Frees are also processed in syncing context. + * Most frees are generated from syncing context, and those that are not + * are held in the spa_free_bplist for processing in syncing context. + * An additional set of in-core trees is maintained to track deferred + * frees (ms_defertree). Once a block is freed it will move from the + * ms_freedtree to the ms_defertree. A deferred free means that a block + * has been freed but cannot be used by the pool until TXG_DEFER_SIZE + * transactions groups later. For example, a block that is freed in txg + * 50 will not be available for reallocation until txg 52 (50 + + * TXG_DEFER_SIZE). This provides a safety net for uberblock rollback. + * A pool could be safely rolled back TXG_DEFERS_SIZE transactions + * groups and ensure that no block has been reallocated. * * The simplified transition diagram looks like this: * * * ALLOCATE * | * V - * free segment (ms_tree) --------> ms_alloctree ----> (write to space map) + * free segment (ms_tree) -----> ms_alloctree[4] ----> (write to space map) * ^ - * | - * | ms_freetree <--- FREE + * | ms_freeingtree <--- FREE * | | + * | v + * | ms_freedtree * | | - * | | - * +----------- ms_defertree <-------+---------> (write to space map) + * +-------- ms_defertree[2] <-------+---------> (write to space map) * * * Each metaslab's space is tracked in a single space map in the MOS, - * which is only updated in syncing context. Each time we sync a txg, - * we append the allocs and frees from that txg to the space map. - * The pool space is only updated once all metaslabs have finished syncing. + * which is only updated in syncing context. Each time we sync a txg, + * we append the allocs and frees from that txg to the space map. The + * pool space is only updated once all metaslabs have finished syncing. * - * To load the in-core free tree we read the space map from disk. - * This object contains a series of alloc and free records that are - * combined to make up the list of all free segments in this metaslab. These + * To load the in-core free tree we read the space map from disk. This + * object contains a series of alloc and free records that are combined + * to make up the list of all free segments in this metaslab. These * segments are represented in-core by the ms_tree and are stored in an * AVL tree. * * As the space map grows (as a result of the appends) it will - * eventually become space-inefficient. When the metaslab's in-core free tree - * is zfs_condense_pct/100 times the size of the minimal on-disk - * representation, we rewrite it in its minimized form. If a metaslab - * needs to condense then we must set the ms_condensing flag to ensure - * that allocations are not performed on the metaslab that is being written. + * eventually become space-inefficient. When the metaslab's in-core + * free tree is zfs_condense_pct/100 times the size of the minimal + * on-disk representation, we rewrite it in its minimized form. If a + * metaslab needs to condense then we must set the ms_condensing flag to + * ensure that allocations are not performed on the metaslab that is + * being written. */ struct metaslab { kmutex_t ms_lock; kcondvar_t ms_load_cv; space_map_t *ms_sm; uint64_t ms_id; uint64_t ms_start; uint64_t ms_size; uint64_t ms_fragmentation; range_tree_t *ms_alloctree[TXG_SIZE]; - range_tree_t *ms_freetree[TXG_SIZE]; - range_tree_t *ms_defertree[TXG_DEFER_SIZE]; range_tree_t *ms_tree; + + /* + * The following range trees are accessed only from syncing context. + * ms_free*tree only have entries while syncing, and are empty + * between syncs. + */ + range_tree_t *ms_freeingtree; /* to free this syncing txg */ + range_tree_t *ms_freedtree; /* already freed this syncing txg */ + range_tree_t *ms_defertree[TXG_DEFER_SIZE]; boolean_t ms_condensing; /* condensing? */ boolean_t ms_condense_wanted; /* * We must hold both ms_lock and ms_group->mg_lock in order to * modify ms_loaded. */ boolean_t ms_loaded; boolean_t ms_loading; int64_t ms_deferspace; /* sum of ms_defermap[] space */ uint64_t ms_weight; /* weight vs. others in group */ uint64_t ms_activation_weight; /* activation weight */ /* * Track of whenever a metaslab is selected for loading or allocation. * We use this value to determine how long the metaslab should * stay cached. */ uint64_t ms_selected_txg; uint64_t ms_alloc_txg; /* last successful alloc (debug only) */ uint64_t ms_max_size; /* maximum allocatable size */ /* * The metaslab block allocators can optionally use a size-ordered * range tree and/or an array of LBAs. Not all allocators use * this functionality. The ms_size_tree should always contain the * same number of segments as the ms_tree. The only difference * is that the ms_size_tree is ordered by segment sizes. */ avl_tree_t ms_size_tree; uint64_t ms_lbas[MAX_LBAS]; metaslab_group_t *ms_group; /* metaslab group */ avl_node_t ms_group_node; /* node in metaslab group tree */ txg_node_t ms_txg_node; /* per-txg dirty metaslab links */ }; #ifdef __cplusplus } #endif #endif /* _SYS_METASLAB_IMPL_H */ Index: head/sys/cddl/contrib/opensolaris =================================================================== --- head/sys/cddl/contrib/opensolaris (revision 317526) +++ head/sys/cddl/contrib/opensolaris (revision 317527) Property changes on: head/sys/cddl/contrib/opensolaris ___________________________________________________________________ Modified: svn:mergeinfo ## -0,0 +0,1 ## Merged /vendor-sys/illumos/dist:r316898