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zfs-builds-mm/zfs-0.8.5/module/zfs/metaslab.c

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add_zfs_0.8.5
2020-10-22 13:48:46 +02:00
/*
* 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, 2019 by Delphix. All rights reserved.
* Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
* Copyright (c) 2017, Intel Corporation.
*/
#include <sys/zfs_context.h>
#include <sys/dmu.h>
#include <sys/dmu_tx.h>
#include <sys/space_map.h>
#include <sys/metaslab_impl.h>
#include <sys/vdev_impl.h>
#include <sys/zio.h>
#include <sys/spa_impl.h>
#include <sys/zfeature.h>
#include <sys/vdev_indirect_mapping.h>
#include <sys/zap.h>
#define WITH_DF_BLOCK_ALLOCATOR
#define GANG_ALLOCATION(flags) \
((flags) & (METASLAB_GANG_CHILD | METASLAB_GANG_HEADER))
/*
* Metaslab granularity, in bytes. This is roughly similar to what would be
* referred to as the "stripe size" in traditional RAID arrays. In normal
* operation, we will try to write this amount of data to a top-level vdev
* before moving on to the next one.
*/
unsigned long metaslab_aliquot = 512 << 10;
/*
* For testing, make some blocks above a certain size be gang blocks.
*/
unsigned long metaslab_force_ganging = SPA_MAXBLOCKSIZE + 1;
/*
* Since we can touch multiple metaslabs (and their respective space maps)
* with each transaction group, we benefit from having a smaller space map
* block size since it allows us to issue more I/O operations scattered
* around the disk.
*/
int zfs_metaslab_sm_blksz = (1 << 12);
/*
* 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;
/*
* 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_blksz), 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;
/*
* 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.
*
* This tunable was introduced to avoid edge cases where we continue
* allocating from very fragmented disks in our pool while other, less
* fragmented disks, exists. On the other hand, if all disks in the
* pool are uniformly approaching the threshold, the threshold can
* be a speed bump in performance, where we keep switching the disks
* that we allocate from (e.g. we allocate some segments from disk A
* making it bypassing the threshold while freeing segments from disk
* B getting its fragmentation below the threshold).
*
* Empirically, we've seen that our vdev selection for allocations is
* good enough that fragmentation increases uniformly across all vdevs
* the majority of the time. Thus we set the threshold percentage high
* enough to avoid hitting the speed bump on pools that are being pushed
* to the edge.
*/
int zfs_mg_fragmentation_threshold = 95;
/*
* 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;
/*
* When set will load all metaslabs when pool is first opened.
*/
int metaslab_debug_load = 0;
/*
* When set will prevent metaslabs from being unloaded.
*/
int metaslab_debug_unload = 0;
/*
* Minimum size which forces the dynamic allocator to change
* it's allocation strategy. Once the space map cannot satisfy
* an allocation of this size then it switches to using more
* aggressive strategy (i.e search by size rather than offset).
*/
uint64_t metaslab_df_alloc_threshold = SPA_OLD_MAXBLOCKSIZE;
/*
* The minimum free space, in percent, which must be available
* in a space map to continue allocations in a first-fit fashion.
* Once the space map's free space drops below this level we dynamically
* switch to using best-fit allocations.
*/
int metaslab_df_free_pct = 4;
/*
* Maximum distance to search forward from the last offset. Without this
* limit, fragmented pools can see >100,000 iterations and
* metaslab_block_picker() becomes the performance limiting factor on
* high-performance storage.
*
* With the default setting of 16MB, we typically see less than 500
* iterations, even with very fragmented, ashift=9 pools. The maximum number
* of iterations possible is:
* metaslab_df_max_search / (2 * (1<<ashift))
* With the default setting of 16MB this is 16*1024 (with ashift=9) or
* 2048 (with ashift=12).
*/
int metaslab_df_max_search = 16 * 1024 * 1024;
/*
* If we are not searching forward (due to metaslab_df_max_search,
* metaslab_df_free_pct, or metaslab_df_alloc_threshold), this tunable
* controls what segment is used. If it is set, we will use the largest free
* segment. If it is not set, we will use a segment of exactly the requested
* size (or larger).
*/
int metaslab_df_use_largest_segment = B_FALSE;
/*
* Percentage of all cpus that can be used by the metaslab taskq.
*/
int metaslab_load_pct = 50;
/*
* 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;
/*
* Max number of metaslabs per group to preload.
*/
int metaslab_preload_limit = SPA_DVAS_PER_BP;
/*
* Enable/disable preloading of metaslab.
*/
int metaslab_preload_enabled = B_TRUE;
/*
* Enable/disable fragmentation weighting on metaslabs.
*/
int metaslab_fragmentation_factor_enabled = B_TRUE;
/*
* Enable/disable lba weighting (i.e. outer tracks are given preference).
*/
int metaslab_lba_weighting_enabled = B_TRUE;
/*
* Enable/disable metaslab group biasing.
*/
int metaslab_bias_enabled = B_TRUE;
/*
* Enable/disable remapping of indirect DVAs to their concrete vdevs.
*/
boolean_t zfs_remap_blkptr_enable = B_TRUE;
/*
* Enable/disable segment-based metaslab selection.
*/
int 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.
*/
#ifdef _METASLAB_TRACING
boolean_t metaslab_trace_enabled = B_TRUE;
#endif
/*
* 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.
*/
#ifdef _METASLAB_TRACING
uint64_t metaslab_trace_max_entries = 5000;
#endif
/*
* Maximum number of metaslabs per group that can be disabled
* simultaneously.
*/
int max_disabled_ms = 3;
static uint64_t metaslab_weight(metaslab_t *);
static void metaslab_set_fragmentation(metaslab_t *);
static void metaslab_free_impl(vdev_t *, uint64_t, uint64_t, boolean_t);
static void metaslab_check_free_impl(vdev_t *, uint64_t, uint64_t);
static void metaslab_passivate(metaslab_t *msp, uint64_t weight);
static uint64_t metaslab_weight_from_range_tree(metaslab_t *msp);
#ifdef _METASLAB_TRACING
kmem_cache_t *metaslab_alloc_trace_cache;
#endif
/*
* ==========================================================================
* 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);
mc->mc_alloc_slots = kmem_zalloc(spa->spa_alloc_count *
sizeof (zfs_refcount_t), KM_SLEEP);
mc->mc_alloc_max_slots = kmem_zalloc(spa->spa_alloc_count *
sizeof (uint64_t), KM_SLEEP);
for (int i = 0; i < spa->spa_alloc_count; i++)
zfs_refcount_create_tracked(&mc->mc_alloc_slots[i]);
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);
for (int i = 0; i < mc->mc_spa->spa_alloc_count; i++)
zfs_refcount_destroy(&mc->mc_alloc_slots[i]);
kmem_free(mc->mc_alloc_slots, mc->mc_spa->spa_alloc_count *
sizeof (zfs_refcount_t));
kmem_free(mc->mc_alloc_max_slots, mc->mc_spa->spa_alloc_count *
sizeof (uint64_t));
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);
}
static void
metaslab_class_space_update(metaslab_class_t *mc, int64_t alloc_delta,
int64_t defer_delta, int64_t space_delta, int64_t dspace_delta)
{
atomic_add_64(&mc->mc_alloc, alloc_delta);
atomic_add_64(&mc->mc_deferred, defer_delta);
atomic_add_64(&mc->mc_space, space_delta);
atomic_add_64(&mc->mc_dspace, dspace_delta);
}
uint64_t
metaslab_class_get_alloc(metaslab_class_t *mc)
{
return (mc->mc_alloc);
}
uint64_t
metaslab_class_get_deferred(metaslab_class_t *mc)
{
return (mc->mc_deferred);
}
uint64_t
metaslab_class_get_space(metaslab_class_t *mc)
{
return (mc->mc_space);
}
uint64_t
metaslab_class_get_dspace(metaslab_class_t *mc)
{
return (spa_deflate(mc->mc_spa) ? mc->mc_dspace : mc->mc_space);
}
void
metaslab_class_histogram_verify(metaslab_class_t *mc)
{
spa_t *spa = mc->mc_spa;
vdev_t *rvd = 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 (!vdev_is_concrete(tvd) || 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 (!vdev_is_concrete(tvd) || 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 (!vdev_is_concrete(tvd) || 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 = (const metaslab_t *)x1;
const metaslab_t *m2 = (const metaslab_t *)x2;
int sort1 = 0;
int sort2 = 0;
if (m1->ms_allocator != -1 && m1->ms_primary)
sort1 = 1;
else if (m1->ms_allocator != -1 && !m1->ms_primary)
sort1 = 2;
if (m2->ms_allocator != -1 && m2->ms_primary)
sort2 = 1;
else if (m2->ms_allocator != -1 && !m2->ms_primary)
sort2 = 2;
/*
* Sort inactive metaslabs first, then primaries, then secondaries. When
* selecting a metaslab to allocate from, an allocator first tries its
* primary, then secondary active metaslab. If it doesn't have active
* metaslabs, or can't allocate from them, it searches for an inactive
* metaslab to activate. If it can't find a suitable one, it will steal
* a primary or secondary metaslab from another allocator.
*/
if (sort1 < sort2)
return (-1);
if (sort1 > sort2)
return (1);
int cmp = AVL_CMP(m2->ms_weight, m1->ms_weight);
if (likely(cmp))
return (cmp);
IMPLY(AVL_CMP(m1->ms_start, m2->ms_start) == 0, m1 == m2);
return (AVL_CMP(m1->ms_start, m2->ms_start));
}
uint64_t
metaslab_allocated_space(metaslab_t *msp)
{
return (msp->ms_allocated_space);
}
/*
* Verify that the space accounting on disk matches the in-core range_trees.
*/
static void
metaslab_verify_space(metaslab_t *msp, uint64_t txg)
{
spa_t *spa = msp->ms_group->mg_vd->vdev_spa;
uint64_t allocating = 0;
uint64_t sm_free_space, msp_free_space;
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT(!msp->ms_condensing);
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;
/*
* Even though the smp_alloc field can get negative (e.g.
* see vdev_checkpoint_sm), that should never be the case
* when it come's to a metaslab's space map.
*/
ASSERT3S(space_map_allocated(msp->ms_sm), >=, 0);
sm_free_space = msp->ms_size - metaslab_allocated_space(msp);
/*
* Account for future allocations since we would have
* already deducted that space from the ms_allocatable.
*/
for (int t = 0; t < TXG_CONCURRENT_STATES; t++) {
allocating +=
range_tree_space(msp->ms_allocating[(txg + t) & TXG_MASK]);
}
ASSERT3U(msp->ms_deferspace, ==,
range_tree_space(msp->ms_defer[0]) +
range_tree_space(msp->ms_defer[1]));
msp_free_space = range_tree_space(msp->ms_allocatable) + allocating +
msp->ms_deferspace + range_tree_space(msp->ms_freed);
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);
ASSERT3U(spa_config_held(mc->mc_spa, SCL_ALLOC, RW_READER), ==,
SCL_ALLOC);
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, int allocators)
{
metaslab_group_t *mg;
mg = kmem_zalloc(sizeof (metaslab_group_t), KM_SLEEP);
mutex_init(&mg->mg_lock, NULL, MUTEX_DEFAULT, NULL);
mutex_init(&mg->mg_ms_disabled_lock, NULL, MUTEX_DEFAULT, NULL);
cv_init(&mg->mg_ms_disabled_cv, NULL, CV_DEFAULT, NULL);
mg->mg_primaries = kmem_zalloc(allocators * sizeof (metaslab_t *),
KM_SLEEP);
mg->mg_secondaries = kmem_zalloc(allocators * sizeof (metaslab_t *),
KM_SLEEP);
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;
mg->mg_allocators = allocators;
mg->mg_alloc_queue_depth = kmem_zalloc(allocators *
sizeof (zfs_refcount_t), KM_SLEEP);
mg->mg_cur_max_alloc_queue_depth = kmem_zalloc(allocators *
sizeof (uint64_t), KM_SLEEP);
for (int i = 0; i < allocators; i++) {
zfs_refcount_create_tracked(&mg->mg_alloc_queue_depth[i]);
mg->mg_cur_max_alloc_queue_depth[i] = 0;
}
mg->mg_taskq = taskq_create("metaslab_group_taskq", metaslab_load_pct,
maxclsyspri, 10, INT_MAX, TASKQ_THREADS_CPU_PCT | TASKQ_DYNAMIC);
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);
kmem_free(mg->mg_primaries, mg->mg_allocators * sizeof (metaslab_t *));
kmem_free(mg->mg_secondaries, mg->mg_allocators *
sizeof (metaslab_t *));
mutex_destroy(&mg->mg_lock);
mutex_destroy(&mg->mg_ms_disabled_lock);
cv_destroy(&mg->mg_ms_disabled_cv);
for (int i = 0; i < mg->mg_allocators; i++) {
zfs_refcount_destroy(&mg->mg_alloc_queue_depth[i]);
mg->mg_cur_max_alloc_queue_depth[i] = 0;
}
kmem_free(mg->mg_alloc_queue_depth, mg->mg_allocators *
sizeof (zfs_refcount_t));
kmem_free(mg->mg_cur_max_alloc_queue_depth, mg->mg_allocators *
sizeof (uint64_t));
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;
ASSERT3U(spa_config_held(mc->mc_spa, SCL_ALLOC, RW_WRITER), !=, 0);
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;
}
/*
* Passivate a metaslab group and remove it from the allocation rotor.
* Callers must hold both the SCL_ALLOC and SCL_ZIO lock prior to passivating
* a metaslab group. This function will momentarily drop spa_config_locks
* that are lower than the SCL_ALLOC lock (see comment below).
*/
void
metaslab_group_passivate(metaslab_group_t *mg)
{
metaslab_class_t *mc = mg->mg_class;
spa_t *spa = mc->mc_spa;
metaslab_group_t *mgprev, *mgnext;
int locks = spa_config_held(spa, SCL_ALL, RW_WRITER);
ASSERT3U(spa_config_held(spa, SCL_ALLOC | SCL_ZIO, RW_WRITER), ==,
(SCL_ALLOC | SCL_ZIO));
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;
}
/*
* The spa_config_lock is an array of rwlocks, ordered as
* follows (from highest to lowest):
* SCL_CONFIG > SCL_STATE > SCL_L2ARC > SCL_ALLOC >
* SCL_ZIO > SCL_FREE > SCL_VDEV
* (For more information about the spa_config_lock see spa_misc.c)
* The higher the lock, the broader its coverage. When we passivate
* a metaslab group, we must hold both the SCL_ALLOC and the SCL_ZIO
* config locks. However, the metaslab group's taskq might be trying
* to preload metaslabs so we must drop the SCL_ZIO lock and any
* lower locks to allow the I/O to complete. At a minimum,
* we continue to hold the SCL_ALLOC lock, which prevents any future
* allocations from taking place and any changes to the vdev tree.
*/
spa_config_exit(spa, locks & ~(SCL_ZIO - 1), spa);
taskq_wait_outstanding(mg->mg_taskq, 0);
spa_config_enter(spa, locks & ~(SCL_ZIO - 1), spa, RW_WRITER);
metaslab_group_alloc_update(mg);
for (int i = 0; i < mg->mg_allocators; i++) {
metaslab_t *msp = mg->mg_primaries[i];
if (msp != NULL) {
mutex_enter(&msp->ms_lock);
metaslab_passivate(msp,
metaslab_weight_from_range_tree(msp));
mutex_exit(&msp->ms_lock);
}
msp = mg->mg_secondaries[i];
if (msp != NULL) {
mutex_enter(&msp->ms_lock);
metaslab_passivate(msp,
metaslab_weight_from_range_tree(msp));
mutex_exit(&msp->ms_lock);
}
}
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;
}
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];
ASSERT(msp != NULL);
/* skip if not active or not a member */
if (msp->ms_sm == NULL || msp->ms_group != mg)
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_impl(metaslab_group_t *mg, metaslab_t *msp, uint64_t weight)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT(MUTEX_HELD(&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);
}
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);
metaslab_group_sort_impl(mg, msp, weight);
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;
if (msp->ms_group != mg)
continue;
valid_ms++;
fragmentation += msp->ms_fragmentation;
}
if (valid_ms <= mg->mg_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, int allocator, int d)
{
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 != spa_special_class(spa) &&
mc != spa_dedup_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_cur_max_alloc_queue_depth[allocator];
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);
/*
* Relax allocation throttling for ditto blocks. Due to
* random imbalances in allocation it tends to push copies
* to one vdev, that looks a bit better at the moment.
*/
qmax = qmax * (4 + d) / 4;
qdepth = zfs_refcount_count(
&mg->mg_alloc_queue_depth[allocator]);
/*
* 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_cur_max_alloc_queue_depth[allocator];
qmax = qmax * (4 + d) / 4;
qdepth = zfs_refcount_count(
&mgp->mg_alloc_queue_depth[allocator]);
/*
* 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;
int cmp = AVL_CMP(rs_size1, rs_size2);
if (likely(cmp))
return (cmp);
return (AVL_CMP(r1->rs_start, r2->rs_start));
}
/*
* ==========================================================================
* 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_allocatable_by_size;
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);
}
#if defined(WITH_DF_BLOCK_ALLOCATOR) || \
defined(WITH_CF_BLOCK_ALLOCATOR)
/*
* 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 max_search)
{
range_seg_t *rs = metaslab_block_find(t, *cursor, size);
uint64_t first_found;
if (rs != NULL)
first_found = rs->rs_start;
while (rs != NULL && rs->rs_start - first_found <= max_search) {
uint64_t offset = rs->rs_start;
if (offset + size <= rs->rs_end) {
*cursor = offset + size;
return (offset);
}
rs = AVL_NEXT(t, rs);
}
*cursor = 0;
return (-1ULL);
}
#endif /* WITH_DF/CF_BLOCK_ALLOCATOR */
#if defined(WITH_DF_BLOCK_ALLOCATOR)
/*
* ==========================================================================
* Dynamic Fit (df) block allocator
*
* Search for a free chunk of at least this size, starting from the last
* offset (for this alignment of block) looking for up to
* metaslab_df_max_search bytes (16MB). If a large enough free chunk is not
* found within 16MB, then return a free chunk of exactly the requested size (or
* larger).
*
* If it seems like searching from the last offset will be unproductive, skip
* that and just return a free chunk of exactly the requested size (or larger).
* This is based on metaslab_df_alloc_threshold and metaslab_df_free_pct. This
* mechanism is probably not very useful and may be removed in the future.
*
* The behavior when not searching can be changed to return the largest free
* chunk, instead of a free chunk of exactly the requested size, by setting
* metaslab_df_use_largest_segment.
* ==========================================================================
*/
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_allocatable;
int free_pct = range_tree_space(rt) * 100 / msp->ms_size;
uint64_t offset;
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT3U(avl_numnodes(&rt->rt_root), ==,
avl_numnodes(&msp->ms_allocatable_by_size));
/*
* If we're running low on space, find a segment based on size,
* rather than iterating based on offset.
*/
if (metaslab_block_maxsize(msp) < metaslab_df_alloc_threshold ||
free_pct < metaslab_df_free_pct) {
offset = -1;
} else {
offset = metaslab_block_picker(&rt->rt_root,
cursor, size, metaslab_df_max_search);
}
if (offset == -1) {
range_seg_t *rs;
if (metaslab_df_use_largest_segment) {
/* use largest free segment */
rs = avl_last(&msp->ms_allocatable_by_size);
} else {
/* use segment of this size, or next largest */
rs = metaslab_block_find(&msp->ms_allocatable_by_size,
0, size);
}
if (rs != NULL && rs->rs_start + size <= rs->rs_end) {
offset = rs->rs_start;
*cursor = offset + size;
}
}
return (offset);
}
static metaslab_ops_t metaslab_df_ops = {
metaslab_df_alloc
};
metaslab_ops_t *zfs_metaslab_ops = &metaslab_df_ops;
#endif /* WITH_DF_BLOCK_ALLOCATOR */
#if defined(WITH_CF_BLOCK_ALLOCATOR)
/*
* ==========================================================================
* 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_allocatable;
avl_tree_t *t = &msp->ms_allocatable_by_size;
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_allocatable_by_size);
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
};
metaslab_ops_t *zfs_metaslab_ops = &metaslab_cf_ops;
#endif /* WITH_CF_BLOCK_ALLOCATOR */
#if defined(WITH_NDF_BLOCK_ALLOCATOR)
/*
* ==========================================================================
* 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_allocatable->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_allocatable_by_size));
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_allocatable_by_size;
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_ndf_ops;
#endif /* WITH_NDF_BLOCK_ALLOCATOR */
/*
* ==========================================================================
* Metaslabs
* ==========================================================================
*/
static void
metaslab_aux_histograms_clear(metaslab_t *msp)
{
/*
* Auxiliary histograms are only cleared when resetting them,
* which can only happen while the metaslab is loaded.
*/
ASSERT(msp->ms_loaded);
bzero(msp->ms_synchist, sizeof (msp->ms_synchist));
for (int t = 0; t < TXG_DEFER_SIZE; t++)
bzero(msp->ms_deferhist[t], sizeof (msp->ms_deferhist[t]));
}
static void
metaslab_aux_histogram_add(uint64_t *histogram, uint64_t shift,
range_tree_t *rt)
{
/*
* This is modeled after space_map_histogram_add(), so refer to that
* function for implementation details. We want this to work like
* the space map histogram, and not the range tree histogram, as we
* are essentially constructing a delta that will be later subtracted
* from the space map histogram.
*/
int idx = 0;
for (int i = shift; i < RANGE_TREE_HISTOGRAM_SIZE; i++) {
ASSERT3U(i, >=, idx + shift);
histogram[idx] += rt->rt_histogram[i] << (i - idx - shift);
if (idx < SPACE_MAP_HISTOGRAM_SIZE - 1) {
ASSERT3U(idx + shift, ==, i);
idx++;
ASSERT3U(idx, <, SPACE_MAP_HISTOGRAM_SIZE);
}
}
}
/*
* Called at every sync pass that the metaslab gets synced.
*
* The reason is that we want our auxiliary histograms to be updated
* wherever the metaslab's space map histogram is updated. This way
* we stay consistent on which parts of the metaslab space map's
* histogram are currently not available for allocations (e.g because
* they are in the defer, freed, and freeing trees).
*/
static void
metaslab_aux_histograms_update(metaslab_t *msp)
{
space_map_t *sm = msp->ms_sm;
ASSERT(sm != NULL);
/*
* This is similar to the metaslab's space map histogram updates
* that take place in metaslab_sync(). The only difference is that
* we only care about segments that haven't made it into the
* ms_allocatable tree yet.
*/
if (msp->ms_loaded) {
metaslab_aux_histograms_clear(msp);
metaslab_aux_histogram_add(msp->ms_synchist,
sm->sm_shift, msp->ms_freed);
for (int t = 0; t < TXG_DEFER_SIZE; t++) {
metaslab_aux_histogram_add(msp->ms_deferhist[t],
sm->sm_shift, msp->ms_defer[t]);
}
}
metaslab_aux_histogram_add(msp->ms_synchist,
sm->sm_shift, msp->ms_freeing);
}
/*
* Called every time we are done syncing (writing to) the metaslab,
* i.e. at the end of each sync pass.
* [see the comment in metaslab_impl.h for ms_synchist, ms_deferhist]
*/
static void
metaslab_aux_histograms_update_done(metaslab_t *msp, boolean_t defer_allowed)
{
spa_t *spa = msp->ms_group->mg_vd->vdev_spa;
space_map_t *sm = msp->ms_sm;
if (sm == NULL) {
/*
* We came here from metaslab_init() when creating/opening a
* pool, looking at a metaslab that hasn't had any allocations
* yet.
*/
return;
}
/*
* This is similar to the actions that we take for the ms_freed
* and ms_defer trees in metaslab_sync_done().
*/
uint64_t hist_index = spa_syncing_txg(spa) % TXG_DEFER_SIZE;
if (defer_allowed) {
bcopy(msp->ms_synchist, msp->ms_deferhist[hist_index],
sizeof (msp->ms_synchist));
} else {
bzero(msp->ms_deferhist[hist_index],
sizeof (msp->ms_deferhist[hist_index]));
}
bzero(msp->ms_synchist, sizeof (msp->ms_synchist));
}
/*
* Ensure that the metaslab's weight and fragmentation are consistent
* with the contents of the histogram (either the range tree's histogram
* or the space map's depending whether the metaslab is loaded).
*/
static void
metaslab_verify_weight_and_frag(metaslab_t *msp)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
if ((zfs_flags & ZFS_DEBUG_METASLAB_VERIFY) == 0)
return;
/* see comment in metaslab_verify_unflushed_changes() */
if (msp->ms_group == NULL)
return;
/*
* Devices being removed always return a weight of 0 and leave
* fragmentation and ms_max_size as is - there is nothing for
* us to verify here.
*/
vdev_t *vd = msp->ms_group->mg_vd;
if (vd->vdev_removing)
return;
/*
* If the metaslab is dirty it probably means that we've done
* some allocations or frees that have changed our histograms
* and thus the weight.
*/
for (int t = 0; t < TXG_SIZE; t++) {
if (txg_list_member(&vd->vdev_ms_list, msp, t))
return;
}
/*
* This verification checks that our in-memory state is consistent
* with what's on disk. If the pool is read-only then there aren't
* any changes and we just have the initially-loaded state.
*/
if (!spa_writeable(msp->ms_group->mg_vd->vdev_spa))
return;
/* some extra verification for in-core tree if you can */
if (msp->ms_loaded) {
range_tree_stat_verify(msp->ms_allocatable);
VERIFY(space_map_histogram_verify(msp->ms_sm,
msp->ms_allocatable));
}
uint64_t weight = msp->ms_weight;
uint64_t was_active = msp->ms_weight & METASLAB_ACTIVE_MASK;
boolean_t space_based = WEIGHT_IS_SPACEBASED(msp->ms_weight);
uint64_t frag = msp->ms_fragmentation;
uint64_t max_segsize = msp->ms_max_size;
msp->ms_weight = 0;
msp->ms_fragmentation = 0;
msp->ms_max_size = 0;
/*
* This function is used for verification purposes. Regardless of
* whether metaslab_weight() thinks this metaslab should be active or
* not, we want to ensure that the actual weight (and therefore the
* value of ms_weight) would be the same if it was to be recalculated
* at this point.
*/
msp->ms_weight = metaslab_weight(msp) | was_active;
VERIFY3U(max_segsize, ==, msp->ms_max_size);
/*
* If the weight type changed then there is no point in doing
* verification. Revert fields to their original values.
*/
if ((space_based && !WEIGHT_IS_SPACEBASED(msp->ms_weight)) ||
(!space_based && WEIGHT_IS_SPACEBASED(msp->ms_weight))) {
msp->ms_fragmentation = frag;
msp->ms_weight = weight;
return;
}
VERIFY3U(msp->ms_fragmentation, ==, frag);
VERIFY3U(msp->ms_weight, ==, weight);
}
/*
* Wait for any in-progress metaslab loads to complete.
*/
static 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);
}
}
static int
metaslab_load_impl(metaslab_t *msp)
{
int error = 0;
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT(msp->ms_loading);
ASSERT(!msp->ms_condensing);
/*
* We temporarily drop the lock to unblock other operations while we
* are reading the space map. Therefore, metaslab_sync() and
* metaslab_sync_done() can run at the same time as we do.
*
* metaslab_sync() can append to the space map while we are loading.
* Therefore we load only entries that existed when we started the
* load. Additionally, metaslab_sync_done() has to wait for the load
* to complete because there are potential races like metaslab_load()
* loading parts of the space map that are currently being appended
* by metaslab_sync(). If we didn't, the ms_allocatable would have
* entries that metaslab_sync_done() would try to re-add later.
*
* That's why before dropping the lock we remember the synced length
* of the metaslab and read up to that point of the space map,
* ignoring entries appended by metaslab_sync() that happen after we
* drop the lock.
*/
uint64_t length = msp->ms_synced_length;
mutex_exit(&msp->ms_lock);
if (msp->ms_sm != NULL) {
error = space_map_load_length(msp->ms_sm, msp->ms_allocatable,
SM_FREE, length);
} else {
/*
* The space map has not been allocated yet, so treat
* all the space in the metaslab as free and add it to the
* ms_allocatable tree.
*/
range_tree_add(msp->ms_allocatable,
msp->ms_start, msp->ms_size);
}
/*
* We need to grab the ms_sync_lock to prevent metaslab_sync() from
* changing the ms_sm and the metaslab's range trees while we are
* about to use them and populate the ms_allocatable. The ms_lock
* is insufficient for this because metaslab_sync() doesn't hold
* the ms_lock while writing the ms_checkpointing tree to disk.
*/
mutex_enter(&msp->ms_sync_lock);
mutex_enter(&msp->ms_lock);
ASSERT(!msp->ms_condensing);
if (error != 0) {
mutex_exit(&msp->ms_sync_lock);
return (error);
}
ASSERT3P(msp->ms_group, !=, NULL);
msp->ms_loaded = B_TRUE;
/*
* The ms_allocatable contains the segments that exist in the
* ms_defer trees [see ms_synced_length]. Thus we need to remove
* them from ms_allocatable as they will be added again in
* metaslab_sync_done().
*/
for (int t = 0; t < TXG_DEFER_SIZE; t++) {
range_tree_walk(msp->ms_defer[t],
range_tree_remove, msp->ms_allocatable);
}
/*
* Call metaslab_recalculate_weight_and_sort() now that the
* metaslab is loaded so we get the metaslab's real weight.
*
* Unless this metaslab was created with older software and
* has not yet been converted to use segment-based weight, we
* expect the new weight to be better or equal to the weight
* that the metaslab had while it was not loaded. This is
* because the old weight does not take into account the
* consolidation of adjacent segments between TXGs. [see
* comment for ms_synchist and ms_deferhist[] for more info]
*/
uint64_t weight = msp->ms_weight;
metaslab_recalculate_weight_and_sort(msp);
if (!WEIGHT_IS_SPACEBASED(weight))
ASSERT3U(weight, <=, msp->ms_weight);
msp->ms_max_size = metaslab_block_maxsize(msp);
spa_t *spa = msp->ms_group->mg_vd->vdev_spa;
metaslab_verify_space(msp, spa_syncing_txg(spa));
mutex_exit(&msp->ms_sync_lock);
return (0);
}
int
metaslab_load(metaslab_t *msp)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
/*
* There may be another thread loading the same metaslab, if that's
* the case just wait until the other thread is done and return.
*/
metaslab_load_wait(msp);
if (msp->ms_loaded)
return (0);
VERIFY(!msp->ms_loading);
ASSERT(!msp->ms_condensing);
msp->ms_loading = B_TRUE;
int error = metaslab_load_impl(msp);
msp->ms_loading = B_FALSE;
cv_broadcast(&msp->ms_load_cv);
return (error);
}
void
metaslab_unload(metaslab_t *msp)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
metaslab_verify_weight_and_frag(msp);
range_tree_vacate(msp->ms_allocatable, NULL, NULL);
msp->ms_loaded = B_FALSE;
msp->ms_activation_weight = 0;
msp->ms_weight &= ~METASLAB_ACTIVE_MASK;
msp->ms_max_size = 0;
/*
* We explicitly recalculate the metaslab's weight based on its space
* map (as it is now not loaded). We want unload metaslabs to always
* have their weights calculated from the space map histograms, while
* loaded ones have it calculated from their in-core range tree
* [see metaslab_load()]. This way, the weight reflects the information
* available in-core, whether it is loaded or not
*
* If ms_group == NULL means that we came here from metaslab_fini(),
* at which point it doesn't make sense for us to do the recalculation
* and the sorting.
*/
if (msp->ms_group != NULL)
metaslab_recalculate_weight_and_sort(msp);
}
static void
metaslab_space_update(vdev_t *vd, metaslab_class_t *mc, int64_t alloc_delta,
int64_t defer_delta, int64_t space_delta)
{
vdev_space_update(vd, alloc_delta, defer_delta, space_delta);
ASSERT3P(vd->vdev_spa->spa_root_vdev, ==, vd->vdev_parent);
ASSERT(vd->vdev_ms_count != 0);
metaslab_class_space_update(mc, alloc_delta, defer_delta, space_delta,
vdev_deflated_space(vd, space_delta));
}
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;
spa_t *spa = vd->vdev_spa;
objset_t *mos = 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);
mutex_init(&ms->ms_sync_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;
ms->ms_allocator = -1;
ms->ms_new = B_TRUE;
/*
* We only open space map objects that already exist. All others
* will be opened when we finally allocate an object for it.
*
* Note:
* When called from vdev_expand(), we can't call into the DMU as
* we are holding the spa_config_lock as a writer and we would
* deadlock [see relevant comment in vdev_metaslab_init()]. in
* that case, the object parameter is zero though, so we won't
* call into the DMU.
*/
if (object != 0) {
error = space_map_open(&ms->ms_sm, mos, object, ms->ms_start,
ms->ms_size, vd->vdev_ashift);
if (error != 0) {
kmem_free(ms, sizeof (metaslab_t));
return (error);
}
ASSERT(ms->ms_sm != NULL);
ms->ms_allocated_space = space_map_allocated(ms->ms_sm);
}
/*
* We create the ms_allocatable here, but we don't create the
* 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_allocatable = range_tree_create_impl(&rt_avl_ops,
&ms->ms_allocatable_by_size, metaslab_rangesize_compare, 0);
ms->ms_trim = range_tree_create(NULL, NULL);
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);
metaslab_space_update(vd, mg->mg_class,
metaslab_allocated_space(ms), 0, 0);
}
/*
* If metaslab_debug_load is set and we're initializing a metaslab
* that has an allocated space map object then load the space map
* so that we 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;
vdev_t *vd = mg->mg_vd;
metaslab_group_remove(mg, msp);
mutex_enter(&msp->ms_lock);
VERIFY(msp->ms_group == NULL);
metaslab_space_update(vd, mg->mg_class,
-metaslab_allocated_space(msp), 0, -msp->ms_size);
space_map_close(msp->ms_sm);
metaslab_unload(msp);
range_tree_destroy(msp->ms_allocatable);
range_tree_destroy(msp->ms_freeing);
range_tree_destroy(msp->ms_freed);
for (int t = 0; t < TXG_SIZE; t++) {
range_tree_destroy(msp->ms_allocating[t]);
}
for (int t = 0; t < TXG_DEFER_SIZE; t++) {
range_tree_destroy(msp->ms_defer[t]);
}
ASSERT0(msp->ms_deferspace);
range_tree_destroy(msp->ms_checkpointing);
for (int t = 0; t < TXG_SIZE; t++)
ASSERT(!txg_list_member(&vd->vdev_ms_list, msp, t));
range_tree_vacate(msp->ms_trim, NULL, NULL);
range_tree_destroy(msp->ms_trim);
mutex_exit(&msp->ms_lock);
cv_destroy(&msp->ms_load_cv);
mutex_destroy(&msp->ms_lock);
mutex_destroy(&msp->ms_sync_lock);
ASSERT3U(msp->ms_allocator, ==, -1);
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 fragmentation 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 */
};
/*
* Calculate the metaslab's fragmentation metric and set ms_fragmentation.
* Setting this value to 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 we've reached the final dirty txg, then we must
* be shutting down the pool. We don't want to dirty
* any data past this point so skip setting the condense
* flag. We can retry this action the next time the pool
* is imported.
*/
if (spa_writeable(spa) && txg < spa_final_dirty_txg(spa)) {
msp->ms_condense_wanted = B_TRUE;
vdev_dirty(vd, VDD_METASLAB, msp, txg + 1);
zfs_dbgmsg("txg %llu, requesting force condense: "
"ms_id %llu, vdev_id %llu", txg, msp->ms_id,
vd->vdev_id);
}
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 - metaslab_allocated_space(msp);
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 (!vd->vdev_nonrot && 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_allocatable->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)
{
space_map_t *sm = msp->ms_sm;
ASSERT(!msp->ms_loaded);
ASSERT(sm != NULL);
ASSERT3U(space_map_object(sm), !=, 0);
ASSERT3U(sm->sm_dbuf->db_size, ==, sizeof (space_map_phys_t));
/*
* Create a joint histogram from all the segments that have made
* it to the metaslab's space map histogram, that are not yet
* available for allocation because they are still in the freeing
* pipeline (e.g. freeing, freed, and defer trees). Then subtract
* these segments from the space map's histogram to get a more
* accurate weight.
*/
uint64_t deferspace_histogram[SPACE_MAP_HISTOGRAM_SIZE] = {0};
for (int i = 0; i < SPACE_MAP_HISTOGRAM_SIZE; i++)
deferspace_histogram[i] += msp->ms_synchist[i];
for (int t = 0; t < TXG_DEFER_SIZE; t++) {
for (int i = 0; i < SPACE_MAP_HISTOGRAM_SIZE; i++) {
deferspace_histogram[i] += msp->ms_deferhist[t][i];
}
}
uint64_t weight = 0;
for (int i = SPACE_MAP_HISTOGRAM_SIZE - 1; i >= 0; i--) {
ASSERT3U(sm->sm_phys->smp_histogram[i], >=,
deferspace_histogram[i]);
uint64_t count =
sm->sm_phys->smp_histogram[i] - deferspace_histogram[i];
if (count != 0) {
WEIGHT_SET_COUNT(weight, count);
WEIGHT_SET_INDEX(weight, i + 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 (metaslab_allocated_space(msp) == 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 (metaslab_allocated_space(msp) == 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)
{
if (msp->ms_max_size != 0)
return (msp->ms_max_size >= asize);
boolean_t should_allocate;
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));
/*
* If this vdev is in the process of being removed, there is nothing
* for us to do here.
*/
if (vd->vdev_removing)
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);
else
ASSERT0(msp->ms_max_size);
/*
* 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);
}
void
metaslab_recalculate_weight_and_sort(metaslab_t *msp)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
/* note: we preserve the mask (e.g. indication of primary, etc..) */
uint64_t was_active = msp->ms_weight & METASLAB_ACTIVE_MASK;
metaslab_group_sort(msp->ms_group, msp,
metaslab_weight(msp) | was_active);
}
static int
metaslab_activate_allocator(metaslab_group_t *mg, metaslab_t *msp,
int allocator, uint64_t activation_weight)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
/*
* If we're activating for the claim code, we don't want to actually
* set the metaslab up for a specific allocator.
*/
if (activation_weight == METASLAB_WEIGHT_CLAIM)
return (0);
metaslab_t **arr = (activation_weight == METASLAB_WEIGHT_PRIMARY ?
mg->mg_primaries : mg->mg_secondaries);
mutex_enter(&mg->mg_lock);
if (arr[allocator] != NULL) {
mutex_exit(&mg->mg_lock);
return (EEXIST);
}
arr[allocator] = msp;
ASSERT3S(msp->ms_allocator, ==, -1);
msp->ms_allocator = allocator;
msp->ms_primary = (activation_weight == METASLAB_WEIGHT_PRIMARY);
mutex_exit(&mg->mg_lock);
return (0);
}
static int
metaslab_activate(metaslab_t *msp, int allocator, uint64_t activation_weight)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
/*
* The current metaslab is already activated for us so there
* is nothing to do. Already activated though, doesn't mean
* that this metaslab is activated for our allocator nor our
* requested activation weight. The metaslab could have started
* as an active one for our allocator but changed allocators
* while we were waiting to grab its ms_lock or we stole it
* [see find_valid_metaslab()]. This means that there is a
* possibility of passivating a metaslab of another allocator
* or from a different activation mask, from this thread.
*/
if ((msp->ms_weight & METASLAB_ACTIVE_MASK) != 0) {
ASSERT(msp->ms_loaded);
return (0);
}
int error = metaslab_load(msp);
if (error != 0) {
metaslab_group_sort(msp->ms_group, msp, 0);
return (error);
}
/*
* When entering metaslab_load() we may have dropped the
* ms_lock because we were loading this metaslab, or we
* were waiting for another thread to load it for us. In
* that scenario, we recheck the weight of the metaslab
* to see if it was activated by another thread.
*
* If the metaslab was activated for another allocator or
* it was activated with a different activation weight (e.g.
* we wanted to make it a primary but it was activated as
* secondary) we return error (EBUSY).
*
* If the metaslab was activated for the same allocator
* and requested activation mask, skip activating it.
*/
if ((msp->ms_weight & METASLAB_ACTIVE_MASK) != 0) {
if (msp->ms_allocator != allocator)
return (EBUSY);
if ((msp->ms_weight & activation_weight) == 0)
return (SET_ERROR(EBUSY));
EQUIV((activation_weight == METASLAB_WEIGHT_PRIMARY),
msp->ms_primary);
return (0);
}
/*
* If the metaslab has literally 0 space, it will have weight 0. In
* that case, don't bother activating it. This can happen if the
* metaslab had space during find_valid_metaslab, but another thread
* loaded it and used all that space while we were waiting to grab the
* lock.
*/
if (msp->ms_weight == 0) {
ASSERT0(range_tree_space(msp->ms_allocatable));
return (SET_ERROR(ENOSPC));
}
if ((error = metaslab_activate_allocator(msp->ms_group, msp,
allocator, activation_weight)) != 0) {
return (error);
}
ASSERT0(msp->ms_activation_weight);
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_allocator(metaslab_group_t *mg, metaslab_t *msp,
uint64_t weight)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT(msp->ms_loaded);
if (msp->ms_weight & METASLAB_WEIGHT_CLAIM) {
metaslab_group_sort(mg, msp, weight);
return;
}
mutex_enter(&mg->mg_lock);
ASSERT3P(msp->ms_group, ==, mg);
ASSERT3S(0, <=, msp->ms_allocator);
ASSERT3U(msp->ms_allocator, <, mg->mg_allocators);
if (msp->ms_primary) {
ASSERT3P(mg->mg_primaries[msp->ms_allocator], ==, msp);
ASSERT(msp->ms_weight & METASLAB_WEIGHT_PRIMARY);
mg->mg_primaries[msp->ms_allocator] = NULL;
} else {
ASSERT3P(mg->mg_secondaries[msp->ms_allocator], ==, msp);
ASSERT(msp->ms_weight & METASLAB_WEIGHT_SECONDARY);
mg->mg_secondaries[msp->ms_allocator] = NULL;
}
msp->ms_allocator = -1;
metaslab_group_sort_impl(mg, msp, weight);
mutex_exit(&mg->mg_lock);
}
static void
metaslab_passivate(metaslab_t *msp, uint64_t weight)
{
ASSERTV(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(!WEIGHT_IS_SPACEBASED(msp->ms_weight) ||
size >= SPA_MINBLOCKSIZE ||
range_tree_space(msp->ms_allocatable) == 0);
ASSERT0(weight & METASLAB_ACTIVE_MASK);
ASSERT(msp->ms_activation_weight != 0);
msp->ms_activation_weight = 0;
metaslab_passivate_allocator(msp->ms_group, msp, weight);
ASSERT0(msp->ms_weight & METASLAB_ACTIVE_MASK);
}
/*
* 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
* metaslab with a 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;
fstrans_cookie_t cookie = spl_fstrans_mark();
ASSERT(!MUTEX_HELD(&msp->ms_group->mg_lock));
mutex_enter(&msp->ms_lock);
(void) metaslab_load(msp);
msp->ms_selected_txg = spa_syncing_txg(spa);
mutex_exit(&msp->ms_lock);
spl_fstrans_unmark(cookie);
}
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_outstanding(mg->mg_taskq, 0);
return;
}
mutex_enter(&mg->mg_lock);
/*
* Load the next potential metaslabs
*/
for (msp = avl_first(t); msp != NULL; msp = AVL_NEXT(t, msp)) {
ASSERT3P(msp->ms_group, ==, mg);
/*
* 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) != TASKQID_INVALID);
}
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 = 1.1MB).
*
* 3. The on-disk size of the space map should actually decrease.
*
* 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;
vdev_t *vd = msp->ms_group->mg_vd;
uint64_t vdev_blocksize = 1 << vd->vdev_ashift;
uint64_t current_txg = spa_syncing_txg(vd->vdev_spa);
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT(msp->ms_loaded);
/*
* Allocations and frees in early passes are generally more space
* efficient (in terms of blocks described in space map entries)
* than the ones in later passes (e.g. we don't compress after
* sync pass 5) and condensing a metaslab multiple times in a txg
* could degrade performance.
*
* Thus we prefer condensing each metaslab at most once every txg at
* the earliest sync pass possible. If a metaslab is eligible for
* condensing again after being considered for condensing within the
* same txg, it will hopefully be dirty in the next txg where it will
* be condensed at an earlier pass.
*/
if (msp->ms_condense_checked_txg == current_txg)
return (B_FALSE);
msp->ms_condense_checked_txg = current_txg;
/*
* We always condense metaslabs that are empty and metaslabs for
* which a condense request has been made.
*/
if (avl_is_empty(&msp->ms_allocatable_by_size) ||
msp->ms_condense_wanted)
return (B_TRUE);
uint64_t object_size = space_map_length(msp->ms_sm);
uint64_t optimal_size = space_map_estimate_optimal_size(sm,
msp->ms_allocatable, SM_NO_VDEVID);
dmu_object_info_t doi;
dmu_object_info_from_db(sm->sm_dbuf, &doi);
uint64_t record_size = MAX(doi.doi_data_block_size, vdev_blocksize);
return (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)
{
range_tree_t *condense_tree;
space_map_t *sm = msp->ms_sm;
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT(msp->ms_loaded);
zfs_dbgmsg("condensing: txg %llu, msp[%llu] %px, 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_allocatable->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);
range_tree_add(condense_tree, msp->ms_start, msp->ms_size);
range_tree_walk(msp->ms_freeing, range_tree_remove, condense_tree);
range_tree_walk(msp->ms_freed, range_tree_remove, condense_tree);
for (int t = 0; t < TXG_DEFER_SIZE; t++) {
range_tree_walk(msp->ms_defer[t],
range_tree_remove, condense_tree);
}
for (int t = 1; t < TXG_CONCURRENT_STATES; t++) {
range_tree_walk(msp->ms_allocating[(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 ms_allocatable 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, zfs_metaslab_sm_blksz, tx);
/*
* 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, SM_NO_VDEVID, tx);
range_tree_vacate(condense_tree, NULL, NULL);
range_tree_destroy(condense_tree);
space_map_write(sm, msp->ms_allocatable, SM_FREE, SM_NO_VDEVID, tx);
mutex_enter(&msp->ms_lock);
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_allocating[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 (msp->ms_freeing == NULL) {
ASSERT3P(alloctree, ==, NULL);
return;
}
ASSERT3P(alloctree, !=, NULL);
ASSERT3P(msp->ms_freeing, !=, NULL);
ASSERT3P(msp->ms_freed, !=, NULL);
ASSERT3P(msp->ms_checkpointing, !=, NULL);
ASSERT3P(msp->ms_trim, !=, 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, it's loaded and we're not beyond the final
* dirty txg, we need to let it through. Not condensing beyond the
* final dirty txg prevents an issue where metaslabs that need to be
* condensed but were loaded for other reasons could cause a panic
* here. By only checking the txg in that branch of the conditional,
* we preserve the utility of the VERIFY statements in all other
* cases.
*/
if (range_tree_is_empty(alloctree) &&
range_tree_is_empty(msp->ms_freeing) &&
range_tree_is_empty(msp->ms_checkpointing) &&
!(msp->ms_loaded && msp->ms_condense_wanted &&
txg <= spa_final_dirty_txg(spa)))
return;
VERIFY(txg <= spa_final_dirty_txg(spa));
/*
* The only state that can actually be changing concurrently
* with metaslab_sync() is the metaslab's ms_allocatable. No
* other thread can be modifying this txg's alloc, freeing,
* freed, or space_map_phys_t. We drop ms_lock whenever we
* could call into the DMU, because the DMU can call down to
* us (e.g. via zio_free()) at any time.
*
* The spa_vdev_remove_thread() can be reading metaslab state
* concurrently, and it is locked out by the ms_sync_lock.
* Note that the ms_lock is insufficient for this, because it
* is dropped by space_map_write().
*/
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, zfs_metaslab_sm_blksz, tx);
VERIFY3U(new_object, !=, 0);
VERIFY0(space_map_open(&msp->ms_sm, mos, new_object,
msp->ms_start, msp->ms_size, vd->vdev_ashift));
ASSERT(msp->ms_sm != NULL);
ASSERT0(metaslab_allocated_space(msp));
}
if (!range_tree_is_empty(msp->ms_checkpointing) &&
vd->vdev_checkpoint_sm == NULL) {
ASSERT(spa_has_checkpoint(spa));
uint64_t new_object = space_map_alloc(mos,
vdev_standard_sm_blksz, tx);
VERIFY3U(new_object, !=, 0);
VERIFY0(space_map_open(&vd->vdev_checkpoint_sm,
mos, new_object, 0, vd->vdev_asize, vd->vdev_ashift));
ASSERT3P(vd->vdev_checkpoint_sm, !=, NULL);
/*
* We save the space map object as an entry in vdev_top_zap
* so it can be retrieved when the pool is reopened after an
* export or through zdb.
*/
VERIFY0(zap_add(vd->vdev_spa->spa_meta_objset,
vd->vdev_top_zap, VDEV_TOP_ZAP_POOL_CHECKPOINT_SM,
sizeof (new_object), 1, &new_object, tx));
}
mutex_enter(&msp->ms_sync_lock);
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 && metaslab_should_condense(msp)) {
metaslab_condense(msp, txg, tx);
} else {
mutex_exit(&msp->ms_lock);
space_map_write(msp->ms_sm, alloctree, SM_ALLOC,
SM_NO_VDEVID, tx);
space_map_write(msp->ms_sm, msp->ms_freeing, SM_FREE,
SM_NO_VDEVID, tx);
mutex_enter(&msp->ms_lock);
}
msp->ms_allocated_space += range_tree_space(alloctree);
ASSERT3U(msp->ms_allocated_space, >=,
range_tree_space(msp->ms_freeing));
msp->ms_allocated_space -= range_tree_space(msp->ms_freeing);
if (!range_tree_is_empty(msp->ms_checkpointing)) {
ASSERT(spa_has_checkpoint(spa));
ASSERT3P(vd->vdev_checkpoint_sm, !=, NULL);
/*
* Since we are doing writes to disk and the ms_checkpointing
* tree won't be changing during that time, we drop the
* ms_lock while writing to the checkpoint space map.
*/
mutex_exit(&msp->ms_lock);
space_map_write(vd->vdev_checkpoint_sm,
msp->ms_checkpointing, SM_FREE, SM_NO_VDEVID, tx);
mutex_enter(&msp->ms_lock);
spa->spa_checkpoint_info.sci_dspace +=
range_tree_space(msp->ms_checkpointing);
vd->vdev_stat.vs_checkpoint_space +=
range_tree_space(msp->ms_checkpointing);
ASSERT3U(vd->vdev_stat.vs_checkpoint_space, ==,
-space_map_allocated(vd->vdev_checkpoint_sm));
range_tree_vacate(msp->ms_checkpointing, NULL, NULL);
}
if (msp->ms_loaded) {
/*
* When the space map is loaded, we have an accurate
* 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_allocatable, 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, msp->ms_freed, 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_defer[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, msp->ms_freeing, tx);
metaslab_aux_histograms_update(msp);
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 freeing and freed.
* 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(&msp->ms_freeing, &msp->ms_freed);
ASSERT0(msp->ms_allocated_this_txg);
} else {
range_tree_vacate(msp->ms_freeing,
range_tree_add, msp->ms_freed);
}
msp->ms_allocated_this_txg += range_tree_space(alloctree);
range_tree_vacate(alloctree, NULL, NULL);
ASSERT0(range_tree_space(msp->ms_allocating[txg & TXG_MASK]));
ASSERT0(range_tree_space(msp->ms_allocating[TXG_CLEAN(txg)
& TXG_MASK]));
ASSERT0(range_tree_space(msp->ms_freeing));
ASSERT0(range_tree_space(msp->ms_checkpointing));
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);
}
mutex_exit(&msp->ms_sync_lock);
dmu_tx_commit(tx);
}
void
metaslab_potentially_unload(metaslab_t *msp, uint64_t txg)
{
/*
* 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_disabled == 0 &&
msp->ms_selected_txg + metaslab_unload_delay < txg) {
for (int t = 1; t < TXG_CONCURRENT_STATES; t++) {
VERIFY0(range_tree_space(
msp->ms_allocating[(txg + t) & TXG_MASK]));
}
if (msp->ms_allocator != -1) {
metaslab_passivate(msp, msp->ms_weight &
~METASLAB_ACTIVE_MASK);
}
if (!metaslab_debug_unload)
metaslab_unload(msp);
}
}
/*
* 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 **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
* range trees and add its capacity to the vdev.
*/
if (msp->ms_freed == NULL) {
for (int t = 0; t < TXG_SIZE; t++) {
ASSERT(msp->ms_allocating[t] == NULL);
msp->ms_allocating[t] = range_tree_create(NULL, NULL);
}
ASSERT3P(msp->ms_freeing, ==, NULL);
msp->ms_freeing = range_tree_create(NULL, NULL);
ASSERT3P(msp->ms_freed, ==, NULL);
msp->ms_freed = range_tree_create(NULL, NULL);
for (int t = 0; t < TXG_DEFER_SIZE; t++) {
ASSERT(msp->ms_defer[t] == NULL);
msp->ms_defer[t] = range_tree_create(NULL, NULL);
}
ASSERT3P(msp->ms_checkpointing, ==, NULL);
msp->ms_checkpointing = range_tree_create(NULL, NULL);
metaslab_space_update(vd, mg->mg_class, 0, 0, msp->ms_size);
}
ASSERT0(range_tree_space(msp->ms_freeing));
ASSERT0(range_tree_space(msp->ms_checkpointing));
defer_tree = &msp->ms_defer[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) || vd->vdev_removing) {
defer_allowed = B_FALSE;
}
defer_delta = 0;
alloc_delta = msp->ms_allocated_this_txg -
range_tree_space(msp->ms_freed);
if (defer_allowed) {
defer_delta = range_tree_space(msp->ms_freed) -
range_tree_space(*defer_tree);
} else {
defer_delta -= range_tree_space(*defer_tree);
}
metaslab_space_update(vd, mg->mg_class, alloc_delta + defer_delta,
defer_delta, 0);
/*
* 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);
/*
* When auto-trimming is enabled, free ranges which are added to
* ms_allocatable are also be added to ms_trim. The ms_trim tree is
* periodically consumed by the vdev_autotrim_thread() which issues
* trims for all ranges and then vacates the tree. The ms_trim tree
* can be discarded at any time with the sole consequence of recent
* frees not being trimmed.
*/
if (spa_get_autotrim(spa) == SPA_AUTOTRIM_ON) {
range_tree_walk(*defer_tree, range_tree_add, msp->ms_trim);
if (!defer_allowed) {
range_tree_walk(msp->ms_freed, range_tree_add,
msp->ms_trim);
}
} else {
range_tree_vacate(msp->ms_trim, NULL, NULL);
}
/*
* 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_allocatable);
if (defer_allowed) {
range_tree_swap(&msp->ms_freed, defer_tree);
} else {
range_tree_vacate(msp->ms_freed,
msp->ms_loaded ? range_tree_add : NULL,
msp->ms_allocatable);
}
msp->ms_synced_length = space_map_length(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);
}
metaslab_aux_histograms_update_done(msp, defer_allowed);
if (msp->ms_new) {
msp->ms_new = B_FALSE;
mutex_enter(&mg->mg_lock);
mg->mg_ms_ready++;
mutex_exit(&mg->mg_lock);
}
/*
* Re-sort metaslab within its group now that we've adjusted
* its allocatable space.
*/
metaslab_recalculate_weight_and_sort(msp);
ASSERT0(range_tree_space(msp->ms_allocating[txg & TXG_MASK]));
ASSERT0(range_tree_space(msp->ms_freeing));
ASSERT0(range_tree_space(msp->ms_freed));
ASSERT0(range_tree_space(msp->ms_checkpointing));
msp->ms_allocated_this_txg = 0;
mutex_exit(&msp->ms_lock);
}
void
metaslab_sync_reassess(metaslab_group_t *mg)
{
spa_t *spa = mg->mg_class->mc_spa;
spa_config_enter(spa, SCL_ALLOC, FTAG, RW_READER);
metaslab_group_alloc_update(mg);
mg->mg_fragmentation = metaslab_group_fragmentation(mg);
/*
* Preload the next potential metaslabs but only on active
* metaslab groups. We can get into a state where the metaslab
* is no longer active since we dirty metaslabs as we remove a
* a device, thus potentially making the metaslab group eligible
* for preloading.
*/
if (mg->mg_activation_count > 0) {
metaslab_group_preload(mg);
}
spa_config_exit(spa, SCL_ALLOC, FTAG);
}
/*
* When writing 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
* on a different metaslab than existing DVAs (i.e. a unique metaslab).
*/
static boolean_t
metaslab_is_unique(metaslab_t *msp, dva_t *dva)
{
uint64_t dva_ms_id;
if (DVA_GET_ASIZE(dva) == 0)
return (B_TRUE);
if (msp->ms_group->mg_vd->vdev_id != DVA_GET_VDEV(dva))
return (B_TRUE);
dva_ms_id = DVA_GET_OFFSET(dva) >> msp->ms_group->mg_vd->vdev_ms_shift;
return (msp->ms_id != dva_ms_id);
}
/*
* ==========================================================================
* Metaslab allocation tracing facility
* ==========================================================================
*/
#ifdef _METASLAB_TRACING
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,
int allocator)
{
metaslab_alloc_trace_t *mat;
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);
}
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;
mat->mat_allocator = allocator;
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;
}
#else
#define metaslab_trace_add(zal, mg, msp, psize, id, off, alloc)
void
metaslab_alloc_trace_init(void)
{
}
void
metaslab_alloc_trace_fini(void)
{
}
void
metaslab_trace_init(zio_alloc_list_t *zal)
{
}
void
metaslab_trace_fini(zio_alloc_list_t *zal)
{
}
#endif /* _METASLAB_TRACING */
/*
* ==========================================================================
* Metaslab block operations
* ==========================================================================
*/
static void
metaslab_group_alloc_increment(spa_t *spa, uint64_t vdev, void *tag, int flags,
int allocator)
{
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) zfs_refcount_add(&mg->mg_alloc_queue_depth[allocator], tag);
}
static void
metaslab_group_increment_qdepth(metaslab_group_t *mg, int allocator)
{
uint64_t max = mg->mg_max_alloc_queue_depth;
uint64_t cur = mg->mg_cur_max_alloc_queue_depth[allocator];
while (cur < max) {
if (atomic_cas_64(&mg->mg_cur_max_alloc_queue_depth[allocator],
cur, cur + 1) == cur) {
atomic_inc_64(
&mg->mg_class->mc_alloc_max_slots[allocator]);
return;
}
cur = mg->mg_cur_max_alloc_queue_depth[allocator];
}
}
void
metaslab_group_alloc_decrement(spa_t *spa, uint64_t vdev, void *tag, int flags,
int allocator, boolean_t io_complete)
{
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) zfs_refcount_remove(&mg->mg_alloc_queue_depth[allocator], tag);
if (io_complete)
metaslab_group_increment_qdepth(mg, allocator);
}
void
metaslab_group_alloc_verify(spa_t *spa, const blkptr_t *bp, void *tag,
int allocator)
{
#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(zfs_refcount_not_held(
&mg->mg_alloc_queue_depth[allocator], 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_allocatable;
metaslab_class_t *mc = msp->ms_group->mg_class;
VERIFY(!msp->ms_condensing);
VERIFY0(msp->ms_disabled);
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);
range_tree_clear(msp->ms_trim, start, size);
if (range_tree_is_empty(msp->ms_allocating[txg & TXG_MASK]))
vdev_dirty(mg->mg_vd, VDD_METASLAB, msp, txg);
range_tree_add(msp->ms_allocating[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);
}
/*
* 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).
*/
static metaslab_t *
find_valid_metaslab(metaslab_group_t *mg, uint64_t activation_weight,
dva_t *dva, int d, boolean_t want_unique, uint64_t asize, int allocator,
zio_alloc_list_t *zal, metaslab_t *search, boolean_t *was_active)
{
avl_index_t idx;
avl_tree_t *t = &mg->mg_metaslab_tree;
metaslab_t *msp = avl_find(t, search, &idx);
if (msp == NULL)
msp = avl_nearest(t, idx, AVL_AFTER);
for (; msp != NULL; msp = AVL_NEXT(t, msp)) {
int i;
if (!metaslab_should_allocate(msp, asize)) {
metaslab_trace_add(zal, mg, msp, asize, d,
TRACE_TOO_SMALL, allocator);
continue;
}
/*
* If the selected metaslab is condensing or disabled,
* skip it.
*/
if (msp->ms_condensing || msp->ms_disabled > 0)
continue;
*was_active = msp->ms_allocator != -1;
/*
* If we're activating as primary, this is our first allocation
* from this disk, so we don't need to check how close we are.
* If the metaslab under consideration was already active,
* we're getting desperate enough to steal another allocator's
* metaslab, so we still don't care about distances.
*/
if (activation_weight == METASLAB_WEIGHT_PRIMARY || *was_active)
break;
for (i = 0; i < d; i++) {
if (want_unique &&
!metaslab_is_unique(msp, &dva[i]))
break; /* try another metaslab */
}
if (i == d)
break;
}
if (msp != NULL) {
search->ms_weight = msp->ms_weight;
search->ms_start = msp->ms_start + 1;
search->ms_allocator = msp->ms_allocator;
search->ms_primary = msp->ms_primary;
}
return (msp);
}
void
metaslab_active_mask_verify(metaslab_t *msp)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
if ((zfs_flags & ZFS_DEBUG_METASLAB_VERIFY) == 0)
return;
if ((msp->ms_weight & METASLAB_ACTIVE_MASK) == 0)
return;
if (msp->ms_weight & METASLAB_WEIGHT_PRIMARY) {
VERIFY0(msp->ms_weight & METASLAB_WEIGHT_SECONDARY);
VERIFY0(msp->ms_weight & METASLAB_WEIGHT_CLAIM);
VERIFY3S(msp->ms_allocator, !=, -1);
VERIFY(msp->ms_primary);
return;
}
if (msp->ms_weight & METASLAB_WEIGHT_SECONDARY) {
VERIFY0(msp->ms_weight & METASLAB_WEIGHT_PRIMARY);
VERIFY0(msp->ms_weight & METASLAB_WEIGHT_CLAIM);
VERIFY3S(msp->ms_allocator, !=, -1);
VERIFY(!msp->ms_primary);
return;
}
if (msp->ms_weight & METASLAB_WEIGHT_CLAIM) {
VERIFY0(msp->ms_weight & METASLAB_WEIGHT_PRIMARY);
VERIFY0(msp->ms_weight & METASLAB_WEIGHT_SECONDARY);
VERIFY3S(msp->ms_allocator, ==, -1);
return;
}
}
/* ARGSUSED */
static uint64_t
metaslab_group_alloc_normal(metaslab_group_t *mg, zio_alloc_list_t *zal,
uint64_t asize, uint64_t txg, boolean_t want_unique, dva_t *dva,
int d, int allocator)
{
metaslab_t *msp = NULL;
uint64_t offset = -1ULL;
uint64_t activation_weight = METASLAB_WEIGHT_PRIMARY;
for (int i = 0; i < d; i++) {
if (activation_weight == METASLAB_WEIGHT_PRIMARY &&
DVA_GET_VDEV(&dva[i]) == mg->mg_vd->vdev_id) {
activation_weight = METASLAB_WEIGHT_SECONDARY;
} else if (activation_weight == METASLAB_WEIGHT_SECONDARY &&
DVA_GET_VDEV(&dva[i]) == mg->mg_vd->vdev_id) {
activation_weight = METASLAB_WEIGHT_CLAIM;
break;
}
}
/*
* If we don't have enough metaslabs active to fill the entire array, we
* just use the 0th slot.
*/
if (mg->mg_ms_ready < mg->mg_allocators * 3)
allocator = 0;
ASSERT3U(mg->mg_vd->vdev_ms_count, >=, 2);
metaslab_t *search = kmem_alloc(sizeof (*search), KM_SLEEP);
search->ms_weight = UINT64_MAX;
search->ms_start = 0;
/*
* At the end of the metaslab tree are the already-active metaslabs,
* first the primaries, then the secondaries. When we resume searching
* through the tree, we need to consider ms_allocator and ms_primary so
* we start in the location right after where we left off, and don't
* accidentally loop forever considering the same metaslabs.
*/
search->ms_allocator = -1;
search->ms_primary = B_TRUE;
for (;;) {
boolean_t was_active = B_FALSE;
mutex_enter(&mg->mg_lock);
if (activation_weight == METASLAB_WEIGHT_PRIMARY &&
mg->mg_primaries[allocator] != NULL) {
msp = mg->mg_primaries[allocator];
/*
* Even though we don't hold the ms_lock for the
* primary metaslab, those fields should not
* change while we hold the mg_lock. Thus is is
* safe to make assertions on them.
*/
ASSERT(msp->ms_primary);
ASSERT3S(msp->ms_allocator, ==, allocator);
ASSERT(msp->ms_loaded);
was_active = B_TRUE;
} else if (activation_weight == METASLAB_WEIGHT_SECONDARY &&
mg->mg_secondaries[allocator] != NULL) {
msp = mg->mg_secondaries[allocator];
/*
* See comment above about the similar assertions
* for the primary metaslab.
*/
ASSERT(!msp->ms_primary);
ASSERT3S(msp->ms_allocator, ==, allocator);
ASSERT(msp->ms_loaded);
was_active = B_TRUE;
} else {
msp = find_valid_metaslab(mg, activation_weight, dva, d,
want_unique, asize, allocator, zal, search,
&was_active);
}
mutex_exit(&mg->mg_lock);
if (msp == NULL) {
kmem_free(search, sizeof (*search));
return (-1ULL);
}
mutex_enter(&msp->ms_lock);
metaslab_active_mask_verify(msp);
/*
* This code is disabled out because of issues with
* tracepoints in non-gpl kernel modules.
*/
#if 0
DTRACE_PROBE3(ms__activation__attempt,
metaslab_t *, msp, uint64_t, activation_weight,
boolean_t, was_active);
#endif
/*
* 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)) {
ASSERT3S(msp->ms_allocator, ==, -1);
mutex_exit(&msp->ms_lock);
continue;
}
/*
* If the metaslab was activated for another allocator
* while we were waiting in the ms_lock above, or it's
* a primary and we're seeking a secondary (or vice versa),
* we go back and select a new metaslab.
*/
if (!was_active && (msp->ms_weight & METASLAB_ACTIVE_MASK) &&
(msp->ms_allocator != -1) &&
(msp->ms_allocator != allocator || ((activation_weight ==
METASLAB_WEIGHT_PRIMARY) != msp->ms_primary))) {
ASSERT(msp->ms_loaded);
ASSERT((msp->ms_weight & METASLAB_WEIGHT_CLAIM) ||
msp->ms_allocator != -1);
mutex_exit(&msp->ms_lock);
continue;
}
/*
* This metaslab was used for claiming regions allocated
* by the ZIL during pool import. Once these regions are
* claimed we don't need to keep the CLAIM bit set
* anymore. Passivate this metaslab to zero its activation
* mask.
*/
if (msp->ms_weight & METASLAB_WEIGHT_CLAIM &&
activation_weight != METASLAB_WEIGHT_CLAIM) {
ASSERT(msp->ms_loaded);
ASSERT3S(msp->ms_allocator, ==, -1);
metaslab_passivate(msp, msp->ms_weight &
~METASLAB_WEIGHT_CLAIM);
mutex_exit(&msp->ms_lock);
continue;
}
msp->ms_selected_txg = txg;
int activation_error =
metaslab_activate(msp, allocator, activation_weight);
metaslab_active_mask_verify(msp);
/*
* If the metaslab was activated by another thread for
* another allocator or activation_weight (EBUSY), or it
* failed because another metaslab was assigned as primary
* for this allocator (EEXIST) we continue using this
* metaslab for our allocation, rather than going on to a
* worse metaslab (we waited for that metaslab to be loaded
* after all).
*
* If the activation failed due to an I/O error or ENOSPC we
* skip to the next metaslab.
*/
boolean_t activated;
if (activation_error == 0) {
activated = B_TRUE;
} else if (activation_error == EBUSY ||
activation_error == EEXIST) {
activated = B_FALSE;
} else {
mutex_exit(&msp->ms_lock);
continue;
}
ASSERT(msp->ms_loaded);
/*
* 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, allocator);
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 this metaslab is being initialized, we shouldn't
* allocate from it since the allocated region might be
* overwritten after allocation.
*/
if (msp->ms_condensing) {
metaslab_trace_add(zal, mg, msp, asize, d,
TRACE_CONDENSING, allocator);
if (activated) {
metaslab_passivate(msp, msp->ms_weight &
~METASLAB_ACTIVE_MASK);
}
mutex_exit(&msp->ms_lock);
continue;
} else if (msp->ms_disabled > 0) {
metaslab_trace_add(zal, mg, msp, asize, d,
TRACE_DISABLED, allocator);
if (activated) {
metaslab_passivate(msp, msp->ms_weight &
~METASLAB_ACTIVE_MASK);
}
mutex_exit(&msp->ms_lock);
continue;
}
offset = metaslab_block_alloc(msp, asize, txg);
metaslab_trace_add(zal, mg, msp, asize, d, offset, allocator);
if (offset != -1ULL) {
/* Proactively passivate the metaslab, if needed */
if (activated)
metaslab_segment_may_passivate(msp);
break;
}
next:
ASSERT(msp->ms_loaded);
/*
* This code is disabled out because of issues with
* tracepoints in non-gpl kernel modules.
*/
#if 0
DTRACE_PROBE2(ms__alloc__failure, metaslab_t *, msp,
uint64_t, asize);
#endif
/*
* 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.
*/
uint64_t weight;
if (WEIGHT_IS_SPACEBASED(msp->ms_weight)) {
weight = metaslab_block_maxsize(msp);
WEIGHT_SET_SPACEBASED(weight);
} else {
weight = metaslab_weight_from_range_tree(msp);
}
if (activated) {
metaslab_passivate(msp, weight);
} else {
/*
* For the case where we use the metaslab that is
* active for another allocator we want to make
* sure that we retain the activation mask.
*
* Note that we could attempt to use something like
* metaslab_recalculate_weight_and_sort() that
* retains the activation mask here. That function
* uses metaslab_weight() to set the weight though
* which is not as accurate as the calculations
* above.
*/
weight |= msp->ms_weight & METASLAB_ACTIVE_MASK;
metaslab_group_sort(mg, msp, weight);
}
metaslab_active_mask_verify(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, boolean_t want_unique, dva_t *dva,
int d, int allocator)
{
uint64_t offset;
ASSERT(mg->mg_initialized);
offset = metaslab_group_alloc_normal(mg, zal, asize, txg, want_unique,
dva, d, allocator);
mutex_enter(&mg->mg_lock);
if (offset == -1ULL) {
mg->mg_failed_allocations++;
metaslab_trace_add(zal, mg, NULL, asize, d,
TRACE_GROUP_FAILURE, allocator);
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);
}
/*
* Allocate a block for the specified i/o.
*/
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, int allocator)
{
metaslab_group_t *mg, *fast_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.
* This will result in more split blocks when using device removal,
* and a large number of split blocks coupled with ztest-induced
* damage can result in extremely long reconstruction times. This
* will also test spilling from special to normal.
*/
if (psize >= metaslab_force_ganging && (spa_get_random(100) < 3)) {
metaslab_trace_add(zal, NULL, NULL, psize, d, TRACE_FORCE_GANG,
allocator);
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 or its mg has been closed (e.g. by
* device removal). Consult the rotor when
* all else fails.
*/
if (vd != NULL && vd->vdev_mg != 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 if (flags & METASLAB_FASTWRITE) {
mg = fast_mg = mc->mc_rotor;
do {
if (fast_mg->mg_vd->vdev_pending_fastwrite <
mg->mg_vd->vdev_pending_fastwrite)
mg = fast_mg;
} while ((fast_mg = fast_mg->mg_next) != mc->mc_rotor);
} else {
ASSERT(mc->mc_rotor != NULL);
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, allocator, d);
}
if (!allocatable) {
metaslab_trace_add(zal, mg, NULL, psize, d,
TRACE_NOT_ALLOCATABLE, allocator);
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, allocator);
goto next;
}
ASSERT(mg->mg_class == mc);
uint64_t asize = vdev_psize_to_asize(vd, psize);
ASSERT(P2PHASE(asize, 1ULL << vd->vdev_ashift) == 0);
/*
* If we don't need to try hard, then require that the
* block be on an different metaslab from any other DVAs
* in this BP (unique=true). If we are trying hard, then
* allow any metaslab to be used (unique=false).
*/
uint64_t offset = metaslab_group_alloc(mg, zal, asize, txg,
!try_hard, dva, d, allocator);
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.
*
* Bias is also used to compensate for unequally
* sized vdevs so that space is allocated fairly.
*/
if (mc->mc_aliquot == 0 && metaslab_bias_enabled) {
vdev_stat_t *vs = &vd->vdev_stat;
int64_t vs_free = vs->vs_space - vs->vs_alloc;
int64_t mc_free = mc->mc_space - mc->mc_alloc;
int64_t ratio;
/*
* Calculate how much more or less we should
* try to allocate from this device during
* this iteration around the rotor.
*
* This basically introduces a zero-centered
* bias towards the devices with the most
* free space, while compensating for vdev
* size differences.
*
* Examples:
* vdev V1 = 16M/128M
* vdev V2 = 16M/128M
* ratio(V1) = 100% ratio(V2) = 100%
*
* vdev V1 = 16M/128M
* vdev V2 = 64M/128M
* ratio(V1) = 127% ratio(V2) = 72%
*
* vdev V1 = 16M/128M
* vdev V2 = 64M/512M
* ratio(V1) = 40% ratio(V2) = 160%
*/
ratio = (vs_free * mc->mc_alloc_groups * 100) /
(mc_free + 1);
mg->mg_bias = ((ratio - 100) *
(int64_t)mg->mg_aliquot) / 100;
} else if (!metaslab_bias_enabled) {
mg->mg_bias = 0;
}
if ((flags & METASLAB_FASTWRITE) ||
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) ? 1 : 0));
DVA_SET_ASIZE(&dva[d], asize);
if (flags & METASLAB_FASTWRITE) {
atomic_add_64(&vd->vdev_pending_fastwrite,
psize);
}
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, allocator);
return (SET_ERROR(ENOSPC));
}
void
metaslab_free_concrete(vdev_t *vd, uint64_t offset, uint64_t asize,
boolean_t checkpoint)
{
metaslab_t *msp;
spa_t *spa = vd->vdev_spa;
ASSERT(vdev_is_concrete(vd));
ASSERT3U(spa_config_held(spa, SCL_ALL, RW_READER), !=, 0);
ASSERT3U(offset >> vd->vdev_ms_shift, <, vd->vdev_ms_count);
msp = vd->vdev_ms[offset >> vd->vdev_ms_shift];
VERIFY(!msp->ms_condensing);
VERIFY3U(offset, >=, msp->ms_start);
VERIFY3U(offset + asize, <=, msp->ms_start + msp->ms_size);
VERIFY0(P2PHASE(offset, 1ULL << vd->vdev_ashift));
VERIFY0(P2PHASE(asize, 1ULL << vd->vdev_ashift));
metaslab_check_free_impl(vd, offset, asize);
mutex_enter(&msp->ms_lock);
if (range_tree_is_empty(msp->ms_freeing) &&
range_tree_is_empty(msp->ms_checkpointing)) {
vdev_dirty(vd, VDD_METASLAB, msp, spa_syncing_txg(spa));
}
if (checkpoint) {
ASSERT(spa_has_checkpoint(spa));
range_tree_add(msp->ms_checkpointing, offset, asize);
} else {
range_tree_add(msp->ms_freeing, offset, asize);
}
mutex_exit(&msp->ms_lock);
}
/* ARGSUSED */
void
metaslab_free_impl_cb(uint64_t inner_offset, vdev_t *vd, uint64_t offset,
uint64_t size, void *arg)
{
boolean_t *checkpoint = arg;
ASSERT3P(checkpoint, !=, NULL);
if (vd->vdev_ops->vdev_op_remap != NULL)
vdev_indirect_mark_obsolete(vd, offset, size);
else
metaslab_free_impl(vd, offset, size, *checkpoint);
}
static void
metaslab_free_impl(vdev_t *vd, uint64_t offset, uint64_t size,
boolean_t checkpoint)
{
spa_t *spa = vd->vdev_spa;
ASSERT3U(spa_config_held(spa, SCL_ALL, RW_READER), !=, 0);
if (spa_syncing_txg(spa) > spa_freeze_txg(spa))
return;
if (spa->spa_vdev_removal != NULL &&
spa->spa_vdev_removal->svr_vdev_id == vd->vdev_id &&
vdev_is_concrete(vd)) {
/*
* Note: we check if the vdev is concrete because when
* we complete the removal, we first change the vdev to be
* an indirect vdev (in open context), and then (in syncing
* context) clear spa_vdev_removal.
*/
free_from_removing_vdev(vd, offset, size);
} else if (vd->vdev_ops->vdev_op_remap != NULL) {
vdev_indirect_mark_obsolete(vd, offset, size);
vd->vdev_ops->vdev_op_remap(vd, offset, size,
metaslab_free_impl_cb, &checkpoint);
} else {
metaslab_free_concrete(vd, offset, size, checkpoint);
}
}
typedef struct remap_blkptr_cb_arg {
blkptr_t *rbca_bp;
spa_remap_cb_t rbca_cb;
vdev_t *rbca_remap_vd;
uint64_t rbca_remap_offset;
void *rbca_cb_arg;
} remap_blkptr_cb_arg_t;
void
remap_blkptr_cb(uint64_t inner_offset, vdev_t *vd, uint64_t offset,
uint64_t size, void *arg)
{
remap_blkptr_cb_arg_t *rbca = arg;
blkptr_t *bp = rbca->rbca_bp;
/* We can not remap split blocks. */
if (size != DVA_GET_ASIZE(&bp->blk_dva[0]))
return;
ASSERT0(inner_offset);
if (rbca->rbca_cb != NULL) {
/*
* At this point we know that we are not handling split
* blocks and we invoke the callback on the previous
* vdev which must be indirect.
*/
ASSERT3P(rbca->rbca_remap_vd->vdev_ops, ==, &vdev_indirect_ops);
rbca->rbca_cb(rbca->rbca_remap_vd->vdev_id,
rbca->rbca_remap_offset, size, rbca->rbca_cb_arg);
/* set up remap_blkptr_cb_arg for the next call */
rbca->rbca_remap_vd = vd;
rbca->rbca_remap_offset = offset;
}
/*
* The phys birth time is that of dva[0]. This ensures that we know
* when each dva was written, so that resilver can determine which
* blocks need to be scrubbed (i.e. those written during the time
* the vdev was offline). It also ensures that the key used in
* the ARC hash table is unique (i.e. dva[0] + phys_birth). If
* we didn't change the phys_birth, a lookup in the ARC for a
* remapped BP could find the data that was previously stored at
* this vdev + offset.
*/
vdev_t *oldvd = vdev_lookup_top(vd->vdev_spa,
DVA_GET_VDEV(&bp->blk_dva[0]));
vdev_indirect_births_t *vib = oldvd->vdev_indirect_births;
bp->blk_phys_birth = vdev_indirect_births_physbirth(vib,
DVA_GET_OFFSET(&bp->blk_dva[0]), DVA_GET_ASIZE(&bp->blk_dva[0]));
DVA_SET_VDEV(&bp->blk_dva[0], vd->vdev_id);
DVA_SET_OFFSET(&bp->blk_dva[0], offset);
}
/*
* If the block pointer contains any indirect DVAs, modify them to refer to
* concrete DVAs. Note that this will sometimes not be possible, leaving
* the indirect DVA in place. This happens if the indirect DVA spans multiple
* segments in the mapping (i.e. it is a "split block").
*
* If the BP was remapped, calls the callback on the original dva (note the
* callback can be called multiple times if the original indirect DVA refers
* to another indirect DVA, etc).
*
* Returns TRUE if the BP was remapped.
*/
boolean_t
spa_remap_blkptr(spa_t *spa, blkptr_t *bp, spa_remap_cb_t callback, void *arg)
{
remap_blkptr_cb_arg_t rbca;
if (!zfs_remap_blkptr_enable)
return (B_FALSE);
if (!spa_feature_is_enabled(spa, SPA_FEATURE_OBSOLETE_COUNTS))
return (B_FALSE);
/*
* Dedup BP's can not be remapped, because ddt_phys_select() depends
* on DVA[0] being the same in the BP as in the DDT (dedup table).
*/
if (BP_GET_DEDUP(bp))
return (B_FALSE);
/*
* Gang blocks can not be remapped, because
* zio_checksum_gang_verifier() depends on the DVA[0] that's in
* the BP used to read the gang block header (GBH) being the same
* as the DVA[0] that we allocated for the GBH.
*/
if (BP_IS_GANG(bp))
return (B_FALSE);
/*
* Embedded BP's have no DVA to remap.
*/
if (BP_GET_NDVAS(bp) < 1)
return (B_FALSE);
/*
* Note: we only remap dva[0]. If we remapped other dvas, we
* would no longer know what their phys birth txg is.
*/
dva_t *dva = &bp->blk_dva[0];
uint64_t offset = DVA_GET_OFFSET(dva);
uint64_t size = DVA_GET_ASIZE(dva);
vdev_t *vd = vdev_lookup_top(spa, DVA_GET_VDEV(dva));
if (vd->vdev_ops->vdev_op_remap == NULL)
return (B_FALSE);
rbca.rbca_bp = bp;
rbca.rbca_cb = callback;
rbca.rbca_remap_vd = vd;
rbca.rbca_remap_offset = offset;
rbca.rbca_cb_arg = arg;
/*
* remap_blkptr_cb() will be called in order for each level of
* indirection, until a concrete vdev is reached or a split block is
* encountered. old_vd and old_offset are updated within the callback
* as we go from the one indirect vdev to the next one (either concrete
* or indirect again) in that order.
*/
vd->vdev_ops->vdev_op_remap(vd, offset, size, remap_blkptr_cb, &rbca);
/* Check if the DVA wasn't remapped because it is a split block */
if (DVA_GET_VDEV(&rbca.rbca_bp->blk_dva[0]) == vd->vdev_id)
return (B_FALSE);
return (B_TRUE);
}
/*
* Undo the allocation of a DVA which happened in the given transaction group.
*/
void
metaslab_unalloc_dva(spa_t *spa, const dva_t *dva, uint64_t txg)
{
metaslab_t *msp;
vdev_t *vd;
uint64_t vdev = DVA_GET_VDEV(dva);
uint64_t offset = DVA_GET_OFFSET(dva);
uint64_t size = DVA_GET_ASIZE(dva);
ASSERT(DVA_IS_VALID(dva));
ASSERT3U(spa_config_held(spa, SCL_ALL, RW_READER), !=, 0);
if (txg > spa_freeze_txg(spa))
return;
if ((vd = vdev_lookup_top(spa, vdev)) == NULL || !DVA_IS_VALID(dva) ||
(offset >> vd->vdev_ms_shift) >= vd->vdev_ms_count) {
zfs_panic_recover("metaslab_free_dva(): bad DVA %llu:%llu:%llu",
(u_longlong_t)vdev, (u_longlong_t)offset,
(u_longlong_t)size);
return;
}
ASSERT(!vd->vdev_removing);
ASSERT(vdev_is_concrete(vd));
ASSERT0(vd->vdev_indirect_config.vic_mapping_object);
ASSERT3P(vd->vdev_indirect_mapping, ==, NULL);
if (DVA_GET_GANG(dva))
size = vdev_psize_to_asize(vd, SPA_GANGBLOCKSIZE);
msp = vd->vdev_ms[offset >> vd->vdev_ms_shift];
mutex_enter(&msp->ms_lock);
range_tree_remove(msp->ms_allocating[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_allocatable) + size, <=,
msp->ms_size);
VERIFY0(P2PHASE(offset, 1ULL << vd->vdev_ashift));
VERIFY0(P2PHASE(size, 1ULL << vd->vdev_ashift));
range_tree_add(msp->ms_allocatable, offset, size);
mutex_exit(&msp->ms_lock);
}
/*
* Free the block represented by the given DVA.
*/
void
metaslab_free_dva(spa_t *spa, const dva_t *dva, boolean_t checkpoint)
{
uint64_t vdev = DVA_GET_VDEV(dva);
uint64_t offset = DVA_GET_OFFSET(dva);
uint64_t size = DVA_GET_ASIZE(dva);
vdev_t *vd = vdev_lookup_top(spa, vdev);
ASSERT(DVA_IS_VALID(dva));
ASSERT3U(spa_config_held(spa, SCL_ALL, RW_READER), !=, 0);
if (DVA_GET_GANG(dva)) {
size = vdev_psize_to_asize(vd, SPA_GANGBLOCKSIZE);
}
metaslab_free_impl(vd, offset, size, checkpoint);
}
/*
* 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, int allocator,
zio_t *zio, int flags)
{
uint64_t available_slots = 0;
boolean_t slot_reserved = B_FALSE;
uint64_t max = mc->mc_alloc_max_slots[allocator];
ASSERT(mc->mc_alloc_throttle_enabled);
mutex_enter(&mc->mc_lock);
uint64_t reserved_slots =
zfs_refcount_count(&mc->mc_alloc_slots[allocator]);
if (reserved_slots < max)
available_slots = max - reserved_slots;
if (slots <= available_slots || GANG_ALLOCATION(flags) ||
flags & METASLAB_MUST_RESERVE) {
/*
* 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 =
zfs_refcount_add(&mc->mc_alloc_slots[allocator],
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,
int allocator, zio_t *zio)
{
ASSERT(mc->mc_alloc_throttle_enabled);
mutex_enter(&mc->mc_lock);
for (int d = 0; d < slots; d++) {
(void) zfs_refcount_remove(&mc->mc_alloc_slots[allocator],
zio);
}
mutex_exit(&mc->mc_lock);
}
static int
metaslab_claim_concrete(vdev_t *vd, uint64_t offset, uint64_t size,
uint64_t txg)
{
metaslab_t *msp;
spa_t *spa = vd->vdev_spa;
int error = 0;
if (offset >> vd->vdev_ms_shift >= vd->vdev_ms_count)
return (SET_ERROR(ENXIO));
ASSERT3P(vd->vdev_ms, !=, NULL);
msp = vd->vdev_ms[offset >> vd->vdev_ms_shift];
mutex_enter(&msp->ms_lock);
if ((txg != 0 && spa_writeable(spa)) || !msp->ms_loaded) {
error = metaslab_activate(msp, 0, METASLAB_WEIGHT_CLAIM);
if (error == EBUSY) {
ASSERT(msp->ms_loaded);
ASSERT(msp->ms_weight & METASLAB_ACTIVE_MASK);
error = 0;
}
}
if (error == 0 &&
!range_tree_contains(msp->ms_allocatable, 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_allocatable) - size, <=,
msp->ms_size);
range_tree_remove(msp->ms_allocatable, offset, size);
range_tree_clear(msp->ms_trim, offset, size);
if (spa_writeable(spa)) { /* don't dirty if we're zdb(1M) */
if (range_tree_is_empty(msp->ms_allocating[txg & TXG_MASK]))
vdev_dirty(vd, VDD_METASLAB, msp, txg);
range_tree_add(msp->ms_allocating[txg & TXG_MASK],
offset, size);
}
mutex_exit(&msp->ms_lock);
return (0);
}
typedef struct metaslab_claim_cb_arg_t {
uint64_t mcca_txg;
int mcca_error;
} metaslab_claim_cb_arg_t;
/* ARGSUSED */
static void
metaslab_claim_impl_cb(uint64_t inner_offset, vdev_t *vd, uint64_t offset,
uint64_t size, void *arg)
{
metaslab_claim_cb_arg_t *mcca_arg = arg;
if (mcca_arg->mcca_error == 0) {
mcca_arg->mcca_error = metaslab_claim_concrete(vd, offset,
size, mcca_arg->mcca_txg);
}
}
int
metaslab_claim_impl(vdev_t *vd, uint64_t offset, uint64_t size, uint64_t txg)
{
if (vd->vdev_ops->vdev_op_remap != NULL) {
metaslab_claim_cb_arg_t arg;
/*
* Only zdb(1M) can claim on indirect vdevs. This is used
* to detect leaks of mapped space (that are not accounted
* for in the obsolete counts, spacemap, or bpobj).
*/
ASSERT(!spa_writeable(vd->vdev_spa));
arg.mcca_error = 0;
arg.mcca_txg = txg;
vd->vdev_ops->vdev_op_remap(vd, offset, size,
metaslab_claim_impl_cb, &arg);
if (arg.mcca_error == 0) {
arg.mcca_error = metaslab_claim_concrete(vd,
offset, size, txg);
}
return (arg.mcca_error);
} else {
return (metaslab_claim_concrete(vd, offset, size, txg));
}
}
/*
* 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;
if ((vd = vdev_lookup_top(spa, vdev)) == NULL) {
return (SET_ERROR(ENXIO));
}
ASSERT(DVA_IS_VALID(dva));
if (DVA_GET_GANG(dva))
size = vdev_psize_to_asize(vd, SPA_GANGBLOCKSIZE);
return (metaslab_claim_impl(vd, offset, size, txg));
}
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, int allocator)
{
dva_t *dva = bp->blk_dva;
dva_t *hintdva = (hintbp != NULL) ? hintbp->blk_dva : NULL;
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, allocator);
if (error != 0) {
for (d--; d >= 0; d--) {
metaslab_unalloc_dva(spa, &dva[d], txg);
metaslab_group_alloc_decrement(spa,
DVA_GET_VDEV(&dva[d]), zio, flags,
allocator, B_FALSE);
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, allocator);
}
}
ASSERT(error == 0);
ASSERT(BP_GET_NDVAS(bp) == ndvas);
spa_config_exit(spa, SCL_ALLOC, FTAG);
BP_SET_BIRTH(bp, txg, 0);
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));
/*
* If we have a checkpoint for the pool we need to make sure that
* the blocks that we free that are part of the checkpoint won't be
* reused until the checkpoint is discarded or we revert to it.
*
* The checkpoint flag is passed down the metaslab_free code path
* and is set whenever we want to add a block to the checkpoint's
* accounting. That is, we "checkpoint" blocks that existed at the
* time the checkpoint was created and are therefore referenced by
* the checkpointed uberblock.
*
* Note that, we don't checkpoint any blocks if the current
* syncing txg <= spa_checkpoint_txg. We want these frees to sync
* normally as they will be referenced by the checkpointed uberblock.
*/
boolean_t checkpoint = B_FALSE;
if (bp->blk_birth <= spa->spa_checkpoint_txg &&
spa_syncing_txg(spa) > spa->spa_checkpoint_txg) {
/*
* At this point, if the block is part of the checkpoint
* there is no way it was created in the current txg.
*/
ASSERT(!now);
ASSERT3U(spa_syncing_txg(spa), ==, txg);
checkpoint = B_TRUE;
}
spa_config_enter(spa, SCL_FREE, FTAG, RW_READER);
for (int d = 0; d < ndvas; d++) {
if (now) {
metaslab_unalloc_dva(spa, &dva[d], txg);
} else {
ASSERT3U(txg, ==, spa_syncing_txg(spa));
metaslab_free_dva(spa, &dva[d], checkpoint);
}
}
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++) {
error = metaslab_claim_dva(spa, &dva[d], txg);
if (error != 0)
break;
}
spa_config_exit(spa, SCL_ALLOC, FTAG);
ASSERT(error == 0 || txg == 0);
return (error);
}
void
metaslab_fastwrite_mark(spa_t *spa, const blkptr_t *bp)
{
const dva_t *dva = bp->blk_dva;
int ndvas = BP_GET_NDVAS(bp);
uint64_t psize = BP_GET_PSIZE(bp);
int d;
vdev_t *vd;
ASSERT(!BP_IS_HOLE(bp));
ASSERT(!BP_IS_EMBEDDED(bp));
ASSERT(psize > 0);
spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
for (d = 0; d < ndvas; d++) {
if ((vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[d]))) == NULL)
continue;
atomic_add_64(&vd->vdev_pending_fastwrite, psize);
}
spa_config_exit(spa, SCL_VDEV, FTAG);
}
void
metaslab_fastwrite_unmark(spa_t *spa, const blkptr_t *bp)
{
const dva_t *dva = bp->blk_dva;
int ndvas = BP_GET_NDVAS(bp);
uint64_t psize = BP_GET_PSIZE(bp);
int d;
vdev_t *vd;
ASSERT(!BP_IS_HOLE(bp));
ASSERT(!BP_IS_EMBEDDED(bp));
ASSERT(psize > 0);
spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
for (d = 0; d < ndvas; d++) {
if ((vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[d]))) == NULL)
continue;
ASSERT3U(vd->vdev_pending_fastwrite, >=, psize);
atomic_sub_64(&vd->vdev_pending_fastwrite, psize);
}
spa_config_exit(spa, SCL_VDEV, FTAG);
}
/* ARGSUSED */
static void
metaslab_check_free_impl_cb(uint64_t inner, vdev_t *vd, uint64_t offset,
uint64_t size, void *arg)
{
if (vd->vdev_ops == &vdev_indirect_ops)
return;
metaslab_check_free_impl(vd, offset, size);
}
static void
metaslab_check_free_impl(vdev_t *vd, uint64_t offset, uint64_t size)
{
metaslab_t *msp;
ASSERTV(spa_t *spa = vd->vdev_spa);
if ((zfs_flags & ZFS_DEBUG_ZIO_FREE) == 0)
return;
if (vd->vdev_ops->vdev_op_remap != NULL) {
vd->vdev_ops->vdev_op_remap(vd, offset, size,
metaslab_check_free_impl_cb, NULL);
return;
}
ASSERT(vdev_is_concrete(vd));
ASSERT3U(offset >> vd->vdev_ms_shift, <, vd->vdev_ms_count);
ASSERT3U(spa_config_held(spa, SCL_ALL, RW_READER), !=, 0);
msp = vd->vdev_ms[offset >> vd->vdev_ms_shift];
mutex_enter(&msp->ms_lock);
if (msp->ms_loaded) {
range_tree_verify_not_present(msp->ms_allocatable,
offset, size);
}
range_tree_verify_not_present(msp->ms_trim, offset, size);
range_tree_verify_not_present(msp->ms_freeing, offset, size);
range_tree_verify_not_present(msp->ms_checkpointing, offset, size);
range_tree_verify_not_present(msp->ms_freed, offset, size);
for (int j = 0; j < TXG_DEFER_SIZE; j++)
range_tree_verify_not_present(msp->ms_defer[j], offset, size);
mutex_exit(&msp->ms_lock);
}
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]);
if (DVA_GET_GANG(&bp->blk_dva[i]))
size = vdev_psize_to_asize(vd, SPA_GANGBLOCKSIZE);
ASSERT3P(vd, !=, NULL);
metaslab_check_free_impl(vd, offset, size);
}
spa_config_exit(spa, SCL_VDEV, FTAG);
}
static void
metaslab_group_disable_wait(metaslab_group_t *mg)
{
ASSERT(MUTEX_HELD(&mg->mg_ms_disabled_lock));
while (mg->mg_disabled_updating) {
cv_wait(&mg->mg_ms_disabled_cv, &mg->mg_ms_disabled_lock);
}
}
static void
metaslab_group_disabled_increment(metaslab_group_t *mg)
{
ASSERT(MUTEX_HELD(&mg->mg_ms_disabled_lock));
ASSERT(mg->mg_disabled_updating);
while (mg->mg_ms_disabled >= max_disabled_ms) {
cv_wait(&mg->mg_ms_disabled_cv, &mg->mg_ms_disabled_lock);
}
mg->mg_ms_disabled++;
ASSERT3U(mg->mg_ms_disabled, <=, max_disabled_ms);
}
/*
* Mark the metaslab as disabled to prevent any allocations on this metaslab.
* We must also track how many metaslabs are currently disabled within a
* metaslab group and limit them to prevent allocation failures from
* occurring because all metaslabs are disabled.
*/
void
metaslab_disable(metaslab_t *msp)
{
ASSERT(!MUTEX_HELD(&msp->ms_lock));
metaslab_group_t *mg = msp->ms_group;
mutex_enter(&mg->mg_ms_disabled_lock);
/*
* To keep an accurate count of how many threads have disabled
* a specific metaslab group, we only allow one thread to mark
* the metaslab group at a time. This ensures that the value of
* ms_disabled will be accurate when we decide to mark a metaslab
* group as disabled. To do this we force all other threads
* to wait till the metaslab's mg_disabled_updating flag is no
* longer set.
*/
metaslab_group_disable_wait(mg);
mg->mg_disabled_updating = B_TRUE;
if (msp->ms_disabled == 0) {
metaslab_group_disabled_increment(mg);
}
mutex_enter(&msp->ms_lock);
msp->ms_disabled++;
mutex_exit(&msp->ms_lock);
mg->mg_disabled_updating = B_FALSE;
cv_broadcast(&mg->mg_ms_disabled_cv);
mutex_exit(&mg->mg_ms_disabled_lock);
}
void
metaslab_enable(metaslab_t *msp, boolean_t sync)
{
metaslab_group_t *mg = msp->ms_group;
spa_t *spa = mg->mg_vd->vdev_spa;
/*
* Wait for the outstanding IO to be synced to prevent newly
* allocated blocks from being overwritten. This used by
* initialize and TRIM which are modifying unallocated space.
*/
if (sync)
txg_wait_synced(spa_get_dsl(spa), 0);
mutex_enter(&mg->mg_ms_disabled_lock);
mutex_enter(&msp->ms_lock);
if (--msp->ms_disabled == 0) {
mg->mg_ms_disabled--;
cv_broadcast(&mg->mg_ms_disabled_cv);
}
mutex_exit(&msp->ms_lock);
mutex_exit(&mg->mg_ms_disabled_lock);
}
#if defined(_KERNEL)
/* BEGIN CSTYLED */
module_param(metaslab_aliquot, ulong, 0644);
MODULE_PARM_DESC(metaslab_aliquot,
"allocation granularity (a.k.a. stripe size)");
module_param(metaslab_debug_load, int, 0644);
MODULE_PARM_DESC(metaslab_debug_load,
"load all metaslabs when pool is first opened");
module_param(metaslab_debug_unload, int, 0644);
MODULE_PARM_DESC(metaslab_debug_unload,
"prevent metaslabs from being unloaded");
module_param(metaslab_preload_enabled, int, 0644);
MODULE_PARM_DESC(metaslab_preload_enabled,
"preload potential metaslabs during reassessment");
module_param(zfs_mg_noalloc_threshold, int, 0644);
MODULE_PARM_DESC(zfs_mg_noalloc_threshold,
"percentage of free space for metaslab group to allow allocation");
module_param(zfs_mg_fragmentation_threshold, int, 0644);
MODULE_PARM_DESC(zfs_mg_fragmentation_threshold,
"fragmentation for metaslab group to allow allocation");
module_param(zfs_metaslab_fragmentation_threshold, int, 0644);
MODULE_PARM_DESC(zfs_metaslab_fragmentation_threshold,
"fragmentation for metaslab to allow allocation");
module_param(metaslab_fragmentation_factor_enabled, int, 0644);
MODULE_PARM_DESC(metaslab_fragmentation_factor_enabled,
"use the fragmentation metric to prefer less fragmented metaslabs");
module_param(metaslab_lba_weighting_enabled, int, 0644);
MODULE_PARM_DESC(metaslab_lba_weighting_enabled,
"prefer metaslabs with lower LBAs");
module_param(metaslab_bias_enabled, int, 0644);
MODULE_PARM_DESC(metaslab_bias_enabled,
"enable metaslab group biasing");
module_param(zfs_metaslab_segment_weight_enabled, int, 0644);
MODULE_PARM_DESC(zfs_metaslab_segment_weight_enabled,
"enable segment-based metaslab selection");
module_param(zfs_metaslab_switch_threshold, int, 0644);
MODULE_PARM_DESC(zfs_metaslab_switch_threshold,
"segment-based metaslab selection maximum buckets before switching");
module_param(metaslab_force_ganging, ulong, 0644);
MODULE_PARM_DESC(metaslab_force_ganging,
"blocks larger than this size are forced to be gang blocks");
module_param(metaslab_df_max_search, int, 0644);
MODULE_PARM_DESC(metaslab_df_max_search,
"max distance (bytes) to search forward before using size tree");
module_param(metaslab_df_use_largest_segment, int, 0644);
MODULE_PARM_DESC(metaslab_df_use_largest_segment,
"when looking in size tree, use largest segment instead of exact fit");
/* END CSTYLED */
#endif
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