freebsd-dev/module/zfs/metaslab.c
Brian Behlendorf efe7978d89 Fix gcc self-comparison warning
As of gcc 6.1.1 20160621 (Red Hat 6.1.1-3) a self-comparison is
detected by gcc in metaslab_alloc().  Resolve the warning by passing
a physical size of 0 to BP_SET_BIRTH() as it done by other callers.

  module/zfs/metaslab.c: In function ‘metaslab_alloc’:
  module/zfs/metaslab.c:2575:184: error: self-comparison always evaluates
      to true [-Werror=tautological-compare]

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Issue #4907
2016-08-02 13:14:18 -07:00

2739 lines
77 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2011, 2015 by Delphix. All rights reserved.
* Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
*/
#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>
#define WITH_DF_BLOCK_ALLOCATOR
/*
* Allow allocations to switch to gang blocks quickly. We do this to
* avoid having to load lots of space_maps in a given txg. There are,
* however, some cases where we want to avoid "fast" ganging and instead
* we want to do an exhaustive search of all metaslabs on this device.
* Currently we don't allow any gang, slog, or dump device related allocations
* to "fast" gang.
*/
#define CAN_FASTGANG(flags) \
(!((flags) & (METASLAB_GANG_CHILD | METASLAB_GANG_HEADER | \
METASLAB_GANG_AVOID)))
#define METASLAB_WEIGHT_PRIMARY (1ULL << 63)
#define METASLAB_WEIGHT_SECONDARY (1ULL << 62)
#define METASLAB_ACTIVE_MASK \
(METASLAB_WEIGHT_PRIMARY | METASLAB_WEIGHT_SECONDARY)
/*
* 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;
uint64_t metaslab_gang_bang = SPA_MAXBLOCKSIZE + 1; /* force gang blocks */
/*
* 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.
*/
int zfs_mg_fragmentation_threshold = 85;
/*
* 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_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;
/*
* 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;
static uint64_t metaslab_fragmentation(metaslab_t *);
/*
* ==========================================================================
* Metaslab classes
* ==========================================================================
*/
metaslab_class_t *
metaslab_class_create(spa_t *spa, metaslab_ops_t *ops)
{
metaslab_class_t *mc;
mc = kmem_zalloc(sizeof (metaslab_class_t), KM_SLEEP);
mc->mc_spa = spa;
mc->mc_rotor = NULL;
mc->mc_ops = ops;
return (mc);
}
void
metaslab_class_destroy(metaslab_class_t *mc)
{
ASSERT(mc->mc_rotor == NULL);
ASSERT(mc->mc_alloc == 0);
ASSERT(mc->mc_deferred == 0);
ASSERT(mc->mc_space == 0);
ASSERT(mc->mc_dspace == 0);
kmem_free(mc, sizeof (metaslab_class_t));
}
int
metaslab_class_validate(metaslab_class_t *mc)
{
metaslab_group_t *mg;
vdev_t *vd;
/*
* Must hold one of the spa_config locks.
*/
ASSERT(spa_config_held(mc->mc_spa, SCL_ALL, RW_READER) ||
spa_config_held(mc->mc_spa, SCL_ALL, RW_WRITER));
if ((mg = mc->mc_rotor) == NULL)
return (0);
do {
vd = mg->mg_vd;
ASSERT(vd->vdev_mg != NULL);
ASSERT3P(vd->vdev_top, ==, vd);
ASSERT3P(mg->mg_class, ==, mc);
ASSERT3P(vd->vdev_ops, !=, &vdev_hole_ops);
} while ((mg = mg->mg_next) != mc->mc_rotor);
return (0);
}
void
metaslab_class_space_update(metaslab_class_t *mc, int64_t alloc_delta,
int64_t defer_delta, int64_t space_delta, int64_t dspace_delta)
{
atomic_add_64(&mc->mc_alloc, alloc_delta);
atomic_add_64(&mc->mc_deferred, defer_delta);
atomic_add_64(&mc->mc_space, space_delta);
atomic_add_64(&mc->mc_dspace, dspace_delta);
}
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)
{
vdev_t *rvd = mc->mc_spa->spa_root_vdev;
uint64_t *mc_hist;
int i, c;
if ((zfs_flags & ZFS_DEBUG_HISTOGRAM_VERIFY) == 0)
return;
mc_hist = kmem_zalloc(sizeof (uint64_t) * RANGE_TREE_HISTOGRAM_SIZE,
KM_SLEEP);
for (c = 0; c < rvd->vdev_children; c++) {
vdev_t *tvd = rvd->vdev_child[c];
metaslab_group_t *mg = tvd->vdev_mg;
/*
* Skip any holes, uninitialized top-levels, or
* vdevs that are not in this metalab class.
*/
if (tvd->vdev_ishole || tvd->vdev_ms_shift == 0 ||
mg->mg_class != mc) {
continue;
}
for (i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++)
mc_hist[i] += mg->mg_histogram[i];
}
for (i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++)
VERIFY3U(mc_hist[i], ==, mc->mc_histogram[i]);
kmem_free(mc_hist, sizeof (uint64_t) * RANGE_TREE_HISTOGRAM_SIZE);
}
/*
* Calculate the metaslab class's fragmentation metric. The metric
* is weighted based on the space contribution of each metaslab group.
* The return value will be a number between 0 and 100 (inclusive), or
* ZFS_FRAG_INVALID if the metric has not been set. See comment above the
* zfs_frag_table for more information about the metric.
*/
uint64_t
metaslab_class_fragmentation(metaslab_class_t *mc)
{
vdev_t *rvd = mc->mc_spa->spa_root_vdev;
uint64_t fragmentation = 0;
int c;
spa_config_enter(mc->mc_spa, SCL_VDEV, FTAG, RW_READER);
for (c = 0; c < rvd->vdev_children; c++) {
vdev_t *tvd = rvd->vdev_child[c];
metaslab_group_t *mg = tvd->vdev_mg;
/*
* Skip any holes, uninitialized top-levels, or
* vdevs that are not in this metalab class.
*/
if (tvd->vdev_ishole || tvd->vdev_ms_shift == 0 ||
mg->mg_class != mc) {
continue;
}
/*
* If a metaslab group does not contain a fragmentation
* metric then just bail out.
*/
if (mg->mg_fragmentation == ZFS_FRAG_INVALID) {
spa_config_exit(mc->mc_spa, SCL_VDEV, FTAG);
return (ZFS_FRAG_INVALID);
}
/*
* Determine how much this metaslab_group is contributing
* to the overall pool fragmentation metric.
*/
fragmentation += mg->mg_fragmentation *
metaslab_group_get_space(mg);
}
fragmentation /= metaslab_class_get_space(mc);
ASSERT3U(fragmentation, <=, 100);
spa_config_exit(mc->mc_spa, SCL_VDEV, FTAG);
return (fragmentation);
}
/*
* Calculate the amount of expandable space that is available in
* this metaslab class. If a device is expanded then its expandable
* space will be the amount of allocatable space that is currently not
* part of this metaslab class.
*/
uint64_t
metaslab_class_expandable_space(metaslab_class_t *mc)
{
vdev_t *rvd = mc->mc_spa->spa_root_vdev;
uint64_t space = 0;
int c;
spa_config_enter(mc->mc_spa, SCL_VDEV, FTAG, RW_READER);
for (c = 0; c < rvd->vdev_children; c++) {
vdev_t *tvd = rvd->vdev_child[c];
metaslab_group_t *mg = tvd->vdev_mg;
if (tvd->vdev_ishole || tvd->vdev_ms_shift == 0 ||
mg->mg_class != mc) {
continue;
}
space += tvd->vdev_max_asize - tvd->vdev_asize;
}
spa_config_exit(mc->mc_spa, SCL_VDEV, FTAG);
return (space);
}
/*
* ==========================================================================
* Metaslab groups
* ==========================================================================
*/
static int
metaslab_compare(const void *x1, const void *x2)
{
const metaslab_t *m1 = x1;
const metaslab_t *m2 = x2;
if (m1->ms_weight < m2->ms_weight)
return (1);
if (m1->ms_weight > m2->ms_weight)
return (-1);
/*
* If the weights are identical, use the offset to force uniqueness.
*/
if (m1->ms_start < m2->ms_start)
return (-1);
if (m1->ms_start > m2->ms_start)
return (1);
ASSERT3P(m1, ==, m2);
return (0);
}
/*
* Update the allocatable flag and the metaslab group's capacity.
* The allocatable flag is set to true if the capacity is below
* the zfs_mg_noalloc_threshold. If a metaslab group transitions
* from allocatable to non-allocatable or vice versa then the metaslab
* group's class is updated to reflect the transition.
*/
static void
metaslab_group_alloc_update(metaslab_group_t *mg)
{
vdev_t *vd = mg->mg_vd;
metaslab_class_t *mc = mg->mg_class;
vdev_stat_t *vs = &vd->vdev_stat;
boolean_t was_allocatable;
ASSERT(vd == vd->vdev_top);
mutex_enter(&mg->mg_lock);
was_allocatable = mg->mg_allocatable;
mg->mg_free_capacity = ((vs->vs_space - vs->vs_alloc) * 100) /
(vs->vs_space + 1);
/*
* 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_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(&mg->mg_lock);
}
metaslab_group_t *
metaslab_group_create(metaslab_class_t *mc, vdev_t *vd)
{
metaslab_group_t *mg;
mg = kmem_zalloc(sizeof (metaslab_group_t), KM_SLEEP);
mutex_init(&mg->mg_lock, NULL, MUTEX_DEFAULT, NULL);
avl_create(&mg->mg_metaslab_tree, metaslab_compare,
sizeof (metaslab_t), offsetof(struct metaslab, ms_group_node));
mg->mg_vd = vd;
mg->mg_class = mc;
mg->mg_activation_count = 0;
mg->mg_taskq = taskq_create("metaslab_group_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);
mutex_destroy(&mg->mg_lock);
kmem_free(mg, sizeof (metaslab_group_t));
}
void
metaslab_group_activate(metaslab_group_t *mg)
{
metaslab_class_t *mc = mg->mg_class;
metaslab_group_t *mgprev, *mgnext;
ASSERT(spa_config_held(mc->mc_spa, SCL_ALLOC, RW_WRITER));
ASSERT(mc->mc_rotor != mg);
ASSERT(mg->mg_prev == NULL);
ASSERT(mg->mg_next == NULL);
ASSERT(mg->mg_activation_count <= 0);
if (++mg->mg_activation_count <= 0)
return;
mg->mg_aliquot = metaslab_aliquot * MAX(1, mg->mg_vd->vdev_children);
metaslab_group_alloc_update(mg);
if ((mgprev = mc->mc_rotor) == NULL) {
mg->mg_prev = mg;
mg->mg_next = mg;
} else {
mgnext = mgprev->mg_next;
mg->mg_prev = mgprev;
mg->mg_next = mgnext;
mgprev->mg_next = mg;
mgnext->mg_prev = mg;
}
mc->mc_rotor = mg;
}
void
metaslab_group_passivate(metaslab_group_t *mg)
{
metaslab_class_t *mc = mg->mg_class;
metaslab_group_t *mgprev, *mgnext;
ASSERT(spa_config_held(mc->mc_spa, SCL_ALLOC, RW_WRITER));
if (--mg->mg_activation_count != 0) {
ASSERT(mc->mc_rotor != mg);
ASSERT(mg->mg_prev == NULL);
ASSERT(mg->mg_next == NULL);
ASSERT(mg->mg_activation_count < 0);
return;
}
taskq_wait_outstanding(mg->mg_taskq, 0);
metaslab_group_alloc_update(mg);
mgprev = mg->mg_prev;
mgnext = mg->mg_next;
if (mg == mgnext) {
mc->mc_rotor = NULL;
} else {
mc->mc_rotor = mgnext;
mgprev->mg_next = mgnext;
mgnext->mg_prev = mgprev;
}
mg->mg_prev = NULL;
mg->mg_next = NULL;
}
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, m;
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 (m = 0; m < vd->vdev_ms_count; m++) {
metaslab_t *msp = vd->vdev_ms[m];
if (msp->ms_sm == NULL)
continue;
for (i = 0; i < SPACE_MAP_HISTOGRAM_SIZE; i++)
mg_hist[i + ashift] +=
msp->ms_sm->sm_phys->smp_histogram[i];
}
for (i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i ++)
VERIFY3U(mg_hist[i], ==, mg->mg_histogram[i]);
kmem_free(mg_hist, sizeof (uint64_t) * RANGE_TREE_HISTOGRAM_SIZE);
}
static void
metaslab_group_histogram_add(metaslab_group_t *mg, metaslab_t *msp)
{
metaslab_class_t *mc = mg->mg_class;
uint64_t ashift = mg->mg_vd->vdev_ashift;
int i;
ASSERT(MUTEX_HELD(&msp->ms_lock));
if (msp->ms_sm == NULL)
return;
mutex_enter(&mg->mg_lock);
for (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;
int i;
ASSERT(MUTEX_HELD(&msp->ms_lock));
if (msp->ms_sm == NULL)
return;
mutex_enter(&mg->mg_lock);
for (i = 0; i < SPACE_MAP_HISTOGRAM_SIZE; i++) {
ASSERT3U(mg->mg_histogram[i + ashift], >=,
msp->ms_sm->sm_phys->smp_histogram[i]);
ASSERT3U(mc->mc_histogram[i + ashift], >=,
msp->ms_sm->sm_phys->smp_histogram[i]);
mg->mg_histogram[i + ashift] -=
msp->ms_sm->sm_phys->smp_histogram[i];
mc->mc_histogram[i + ashift] -=
msp->ms_sm->sm_phys->smp_histogram[i];
}
mutex_exit(&mg->mg_lock);
}
static void
metaslab_group_add(metaslab_group_t *mg, metaslab_t *msp)
{
ASSERT(msp->ms_group == NULL);
mutex_enter(&mg->mg_lock);
msp->ms_group = mg;
msp->ms_weight = 0;
avl_add(&mg->mg_metaslab_tree, msp);
mutex_exit(&mg->mg_lock);
mutex_enter(&msp->ms_lock);
metaslab_group_histogram_add(mg, msp);
mutex_exit(&msp->ms_lock);
}
static void
metaslab_group_remove(metaslab_group_t *mg, metaslab_t *msp)
{
mutex_enter(&msp->ms_lock);
metaslab_group_histogram_remove(mg, msp);
mutex_exit(&msp->ms_lock);
mutex_enter(&mg->mg_lock);
ASSERT(msp->ms_group == mg);
avl_remove(&mg->mg_metaslab_tree, msp);
msp->ms_group = NULL;
mutex_exit(&mg->mg_lock);
}
static void
metaslab_group_sort(metaslab_group_t *mg, metaslab_t *msp, uint64_t weight)
{
/*
* Although in principle the weight can be any value, in
* practice we do not use values in the range [1, 511].
*/
ASSERT(weight >= SPA_MINBLOCKSIZE || weight == 0);
ASSERT(MUTEX_HELD(&msp->ms_lock));
mutex_enter(&mg->mg_lock);
ASSERT(msp->ms_group == mg);
avl_remove(&mg->mg_metaslab_tree, msp);
msp->ms_weight = weight;
avl_add(&mg->mg_metaslab_tree, msp);
mutex_exit(&mg->mg_lock);
}
/*
* Calculate the fragmentation for a given metaslab group. We can use
* a simple average here since all metaslabs within the group must have
* the same size. The return value will be a value between 0 and 100
* (inclusive), or ZFS_FRAG_INVALID if less than half of the metaslab in this
* group have a fragmentation metric.
*/
uint64_t
metaslab_group_fragmentation(metaslab_group_t *mg)
{
vdev_t *vd = mg->mg_vd;
uint64_t fragmentation = 0;
uint64_t valid_ms = 0;
int m;
for (m = 0; m < vd->vdev_ms_count; m++) {
metaslab_t *msp = vd->vdev_ms[m];
if (msp->ms_fragmentation == ZFS_FRAG_INVALID)
continue;
valid_ms++;
fragmentation += msp->ms_fragmentation;
}
if (valid_ms <= vd->vdev_ms_count / 2)
return (ZFS_FRAG_INVALID);
fragmentation /= valid_ms;
ASSERT3U(fragmentation, <=, 100);
return (fragmentation);
}
/*
* Determine if a given metaslab group should skip allocations. A metaslab
* group should avoid allocations if its free capacity is less than the
* zfs_mg_noalloc_threshold or its fragmentation metric is greater than
* zfs_mg_fragmentation_threshold and there is at least one metaslab group
* that can still handle allocations.
*/
static boolean_t
metaslab_group_allocatable(metaslab_group_t *mg)
{
vdev_t *vd = mg->mg_vd;
spa_t *spa = vd->vdev_spa;
metaslab_class_t *mc = mg->mg_class;
/*
* We use two key metrics to determine if a metaslab group is
* considered allocatable -- free space and fragmentation. If
* the free space is greater than the free space threshold and
* the fragmentation is less than the fragmentation threshold then
* consider the group allocatable. There are two case when we will
* not consider these key metrics. The first is if the group is
* associated with a slog device and the second is if all groups
* in this metaslab class have already been consider ineligible
* for allocations.
*/
return ((mg->mg_free_capacity > zfs_mg_noalloc_threshold &&
(mg->mg_fragmentation == ZFS_FRAG_INVALID ||
mg->mg_fragmentation <= zfs_mg_fragmentation_threshold)) ||
mc != spa_normal_class(spa) || mc->mc_alloc_groups == 0);
}
/*
* ==========================================================================
* Range tree callbacks
* ==========================================================================
*/
/*
* Comparison function for the private size-ordered tree. Tree is sorted
* by size, larger sizes at the end of the tree.
*/
static int
metaslab_rangesize_compare(const void *x1, const void *x2)
{
const range_seg_t *r1 = x1;
const range_seg_t *r2 = x2;
uint64_t rs_size1 = r1->rs_end - r1->rs_start;
uint64_t rs_size2 = r2->rs_end - r2->rs_start;
if (rs_size1 < rs_size2)
return (-1);
if (rs_size1 > rs_size2)
return (1);
if (r1->rs_start < r2->rs_start)
return (-1);
if (r1->rs_start > r2->rs_start)
return (1);
return (0);
}
/*
* Create any block allocator specific components. The current allocators
* rely on using both a size-ordered range_tree_t and an array of uint64_t's.
*/
static void
metaslab_rt_create(range_tree_t *rt, void *arg)
{
metaslab_t *msp = arg;
ASSERT3P(rt->rt_arg, ==, msp);
ASSERT(msp->ms_tree == NULL);
avl_create(&msp->ms_size_tree, metaslab_rangesize_compare,
sizeof (range_seg_t), offsetof(range_seg_t, rs_pp_node));
}
/*
* Destroy the block allocator specific components.
*/
static void
metaslab_rt_destroy(range_tree_t *rt, void *arg)
{
metaslab_t *msp = arg;
ASSERT3P(rt->rt_arg, ==, msp);
ASSERT3P(msp->ms_tree, ==, rt);
ASSERT0(avl_numnodes(&msp->ms_size_tree));
avl_destroy(&msp->ms_size_tree);
}
static void
metaslab_rt_add(range_tree_t *rt, range_seg_t *rs, void *arg)
{
metaslab_t *msp = arg;
ASSERT3P(rt->rt_arg, ==, msp);
ASSERT3P(msp->ms_tree, ==, rt);
VERIFY(!msp->ms_condensing);
avl_add(&msp->ms_size_tree, rs);
}
static void
metaslab_rt_remove(range_tree_t *rt, range_seg_t *rs, void *arg)
{
metaslab_t *msp = arg;
ASSERT3P(rt->rt_arg, ==, msp);
ASSERT3P(msp->ms_tree, ==, rt);
VERIFY(!msp->ms_condensing);
avl_remove(&msp->ms_size_tree, rs);
}
static void
metaslab_rt_vacate(range_tree_t *rt, void *arg)
{
metaslab_t *msp = arg;
ASSERT3P(rt->rt_arg, ==, msp);
ASSERT3P(msp->ms_tree, ==, rt);
/*
* Normally one would walk the tree freeing nodes along the way.
* Since the nodes are shared with the range trees we can avoid
* walking all nodes and just reinitialize the avl tree. The nodes
* will be freed by the range tree, so we don't want to free them here.
*/
avl_create(&msp->ms_size_tree, metaslab_rangesize_compare,
sizeof (range_seg_t), offsetof(range_seg_t, rs_pp_node));
}
static range_tree_ops_t metaslab_rt_ops = {
metaslab_rt_create,
metaslab_rt_destroy,
metaslab_rt_add,
metaslab_rt_remove,
metaslab_rt_vacate
};
/*
* ==========================================================================
* Metaslab block operations
* ==========================================================================
*/
/*
* Return the maximum contiguous segment within the metaslab.
*/
uint64_t
metaslab_block_maxsize(metaslab_t *msp)
{
avl_tree_t *t = &msp->ms_size_tree;
range_seg_t *rs;
if (t == NULL || (rs = avl_last(t)) == NULL)
return (0ULL);
return (rs->rs_end - rs->rs_start);
}
uint64_t
metaslab_block_alloc(metaslab_t *msp, uint64_t size)
{
uint64_t start;
range_tree_t *rt = msp->ms_tree;
VERIFY(!msp->ms_condensing);
start = msp->ms_ops->msop_alloc(msp, size);
if (start != -1ULL) {
vdev_t *vd = msp->ms_group->mg_vd;
VERIFY0(P2PHASE(start, 1ULL << vd->vdev_ashift));
VERIFY0(P2PHASE(size, 1ULL << vd->vdev_ashift));
VERIFY3U(range_tree_space(rt) - size, <=, msp->ms_size);
range_tree_remove(rt, start, size);
}
return (start);
}
/*
* ==========================================================================
* Common allocator routines
* ==========================================================================
*/
#if defined(WITH_FF_BLOCK_ALLOCATOR) || \
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 align)
{
range_seg_t *rs, rsearch;
avl_index_t where;
rsearch.rs_start = *cursor;
rsearch.rs_end = *cursor + size;
rs = avl_find(t, &rsearch, &where);
if (rs == NULL)
rs = avl_nearest(t, where, AVL_AFTER);
while (rs != NULL) {
uint64_t offset = P2ROUNDUP(rs->rs_start, align);
if (offset + size <= rs->rs_end) {
*cursor = offset + size;
return (offset);
}
rs = AVL_NEXT(t, rs);
}
/*
* If we know we've searched the whole map (*cursor == 0), give up.
* Otherwise, reset the cursor to the beginning and try again.
*/
if (*cursor == 0)
return (-1ULL);
*cursor = 0;
return (metaslab_block_picker(t, cursor, size, align));
}
#endif /* WITH_FF/DF/CF_BLOCK_ALLOCATOR */
#if defined(WITH_FF_BLOCK_ALLOCATOR)
/*
* ==========================================================================
* The first-fit block allocator
* ==========================================================================
*/
static uint64_t
metaslab_ff_alloc(metaslab_t *msp, uint64_t size)
{
/*
* Find the largest power of 2 block size that evenly divides the
* requested size. This is used to try to allocate blocks with similar
* alignment from the same area of the metaslab (i.e. same cursor
* bucket) but it does not guarantee that other allocations sizes
* may exist in the same region.
*/
uint64_t align = size & -size;
uint64_t *cursor = &msp->ms_lbas[highbit64(align) - 1];
avl_tree_t *t = &msp->ms_tree->rt_root;
return (metaslab_block_picker(t, cursor, size, align));
}
static metaslab_ops_t metaslab_ff_ops = {
metaslab_ff_alloc
};
metaslab_ops_t *zfs_metaslab_ops = &metaslab_ff_ops;
#endif /* WITH_FF_BLOCK_ALLOCATOR */
#if defined(WITH_DF_BLOCK_ALLOCATOR)
/*
* ==========================================================================
* Dynamic block allocator -
* Uses the first fit allocation scheme until space get low and then
* adjusts to a best fit allocation method. Uses metaslab_df_alloc_threshold
* and metaslab_df_free_pct to determine when to switch the allocation scheme.
* ==========================================================================
*/
static uint64_t
metaslab_df_alloc(metaslab_t *msp, uint64_t size)
{
/*
* Find the largest power of 2 block size that evenly divides the
* requested size. This is used to try to allocate blocks with similar
* alignment from the same area of the metaslab (i.e. same cursor
* bucket) but it does not guarantee that other allocations sizes
* may exist in the same region.
*/
uint64_t align = size & -size;
uint64_t *cursor = &msp->ms_lbas[highbit64(align) - 1];
range_tree_t *rt = msp->ms_tree;
avl_tree_t *t = &rt->rt_root;
uint64_t max_size = metaslab_block_maxsize(msp);
int free_pct = range_tree_space(rt) * 100 / msp->ms_size;
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT3U(avl_numnodes(t), ==, avl_numnodes(&msp->ms_size_tree));
if (max_size < size)
return (-1ULL);
/*
* If we're running low on space switch to using the size
* sorted AVL tree (best-fit).
*/
if (max_size < metaslab_df_alloc_threshold ||
free_pct < metaslab_df_free_pct) {
t = &msp->ms_size_tree;
*cursor = 0;
}
return (metaslab_block_picker(t, cursor, size, 1ULL));
}
static metaslab_ops_t metaslab_df_ops = {
metaslab_df_alloc
};
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_tree;
avl_tree_t *t = &msp->ms_size_tree;
uint64_t *cursor = &msp->ms_lbas[0];
uint64_t *cursor_end = &msp->ms_lbas[1];
uint64_t offset = 0;
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT3U(avl_numnodes(t), ==, avl_numnodes(&rt->rt_root));
ASSERT3U(*cursor_end, >=, *cursor);
if ((*cursor + size) > *cursor_end) {
range_seg_t *rs;
rs = avl_last(&msp->ms_size_tree);
if (rs == NULL || (rs->rs_end - rs->rs_start) < size)
return (-1ULL);
*cursor = rs->rs_start;
*cursor_end = rs->rs_end;
}
offset = *cursor;
*cursor += size;
return (offset);
}
static metaslab_ops_t metaslab_cf_ops = {
metaslab_cf_alloc
};
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_tree->rt_root;
avl_index_t where;
range_seg_t *rs, rsearch;
uint64_t hbit = highbit64(size);
uint64_t *cursor = &msp->ms_lbas[hbit - 1];
uint64_t max_size = metaslab_block_maxsize(msp);
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT3U(avl_numnodes(t), ==, avl_numnodes(&msp->ms_size_tree));
if (max_size < size)
return (-1ULL);
rsearch.rs_start = *cursor;
rsearch.rs_end = *cursor + size;
rs = avl_find(t, &rsearch, &where);
if (rs == NULL || (rs->rs_end - rs->rs_start) < size) {
t = &msp->ms_size_tree;
rsearch.rs_start = 0;
rsearch.rs_end = MIN(max_size,
1ULL << (hbit + metaslab_ndf_clump_shift));
rs = avl_find(t, &rsearch, &where);
if (rs == NULL)
rs = avl_nearest(t, where, AVL_AFTER);
ASSERT(rs != NULL);
}
if ((rs->rs_end - rs->rs_start) >= size) {
*cursor = rs->rs_start + size;
return (rs->rs_start);
}
return (-1ULL);
}
static metaslab_ops_t metaslab_ndf_ops = {
metaslab_ndf_alloc
};
metaslab_ops_t *zfs_metaslab_ops = &metaslab_ndf_ops;
#endif /* WITH_NDF_BLOCK_ALLOCATOR */
/*
* ==========================================================================
* Metaslabs
* ==========================================================================
*/
/*
* Wait for any in-progress metaslab loads to complete.
*/
void
metaslab_load_wait(metaslab_t *msp)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
while (msp->ms_loading) {
ASSERT(!msp->ms_loaded);
cv_wait(&msp->ms_load_cv, &msp->ms_lock);
}
}
int
metaslab_load(metaslab_t *msp)
{
int error = 0;
int t;
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT(!msp->ms_loaded);
ASSERT(!msp->ms_loading);
msp->ms_loading = B_TRUE;
/*
* If the space map has not been allocated yet, then treat
* all the space in the metaslab as free and add it to the
* ms_tree.
*/
if (msp->ms_sm != NULL)
error = space_map_load(msp->ms_sm, msp->ms_tree, SM_FREE);
else
range_tree_add(msp->ms_tree, msp->ms_start, msp->ms_size);
msp->ms_loaded = (error == 0);
msp->ms_loading = B_FALSE;
if (msp->ms_loaded) {
for (t = 0; t < TXG_DEFER_SIZE; t++) {
range_tree_walk(msp->ms_defertree[t],
range_tree_remove, msp->ms_tree);
}
}
cv_broadcast(&msp->ms_load_cv);
return (error);
}
void
metaslab_unload(metaslab_t *msp)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
range_tree_vacate(msp->ms_tree, NULL, NULL);
msp->ms_loaded = B_FALSE;
msp->ms_weight &= ~METASLAB_ACTIVE_MASK;
}
int
metaslab_init(metaslab_group_t *mg, uint64_t id, uint64_t object, uint64_t txg,
metaslab_t **msp)
{
vdev_t *vd = mg->mg_vd;
objset_t *mos = vd->vdev_spa->spa_meta_objset;
metaslab_t *ms;
int error;
ms = kmem_zalloc(sizeof (metaslab_t), KM_SLEEP);
mutex_init(&ms->ms_lock, NULL, MUTEX_DEFAULT, NULL);
cv_init(&ms->ms_load_cv, NULL, CV_DEFAULT, NULL);
ms->ms_id = id;
ms->ms_start = id << vd->vdev_ms_shift;
ms->ms_size = 1ULL << vd->vdev_ms_shift;
/*
* We only open space map objects that already exist. All others
* will be opened when we finally allocate an object for it.
*/
if (object != 0) {
error = space_map_open(&ms->ms_sm, mos, object, ms->ms_start,
ms->ms_size, vd->vdev_ashift, &ms->ms_lock);
if (error != 0) {
kmem_free(ms, sizeof (metaslab_t));
return (error);
}
ASSERT(ms->ms_sm != NULL);
}
/*
* We create the main range tree here, but we don't create the
* alloctree and freetree until metaslab_sync_done(). This serves
* two purposes: it allows metaslab_sync_done() to detect the
* addition of new space; and for debugging, it ensures that we'd
* data fault on any attempt to use this metaslab before it's ready.
*/
ms->ms_tree = range_tree_create(&metaslab_rt_ops, ms, &ms->ms_lock);
metaslab_group_add(mg, ms);
ms->ms_fragmentation = metaslab_fragmentation(ms);
ms->ms_ops = mg->mg_class->mc_ops;
/*
* If we're opening an existing pool (txg == 0) or creating
* a new one (txg == TXG_INITIAL), all space is available now.
* If we're adding space to an existing pool, the new space
* does not become available until after this txg has synced.
*/
if (txg <= TXG_INITIAL)
metaslab_sync_done(ms, 0);
/*
* If metaslab_debug_load is set and we're initializing a metaslab
* that has an allocated space_map object then load the its space
* map so that can verify frees.
*/
if (metaslab_debug_load && ms->ms_sm != NULL) {
mutex_enter(&ms->ms_lock);
VERIFY0(metaslab_load(ms));
mutex_exit(&ms->ms_lock);
}
if (txg != 0) {
vdev_dirty(vd, 0, NULL, txg);
vdev_dirty(vd, VDD_METASLAB, ms, txg);
}
*msp = ms;
return (0);
}
void
metaslab_fini(metaslab_t *msp)
{
int t;
metaslab_group_t *mg = msp->ms_group;
metaslab_group_remove(mg, msp);
mutex_enter(&msp->ms_lock);
VERIFY(msp->ms_group == NULL);
vdev_space_update(mg->mg_vd, -space_map_allocated(msp->ms_sm),
0, -msp->ms_size);
space_map_close(msp->ms_sm);
metaslab_unload(msp);
range_tree_destroy(msp->ms_tree);
for (t = 0; t < TXG_SIZE; t++) {
range_tree_destroy(msp->ms_alloctree[t]);
range_tree_destroy(msp->ms_freetree[t]);
}
for (t = 0; t < TXG_DEFER_SIZE; t++) {
range_tree_destroy(msp->ms_defertree[t]);
}
ASSERT0(msp->ms_deferspace);
mutex_exit(&msp->ms_lock);
cv_destroy(&msp->ms_load_cv);
mutex_destroy(&msp->ms_lock);
kmem_free(msp, sizeof (metaslab_t));
}
#define FRAGMENTATION_TABLE_SIZE 17
/*
* This table defines a segment size based fragmentation metric that will
* allow each metaslab to derive its own fragmentation value. This is done
* by calculating the space in each bucket of the spacemap histogram and
* multiplying that by the fragmetation metric in this table. Doing
* this for all buckets and dividing it by the total amount of free
* space in this metaslab (i.e. the total free space in all buckets) gives
* us the fragmentation metric. This means that a high fragmentation metric
* equates to most of the free space being comprised of small segments.
* Conversely, if the metric is low, then most of the free space is in
* large segments. A 10% change in fragmentation equates to approximately
* double the number of segments.
*
* This table defines 0% fragmented space using 16MB segments. Testing has
* shown that segments that are greater than or equal to 16MB do not suffer
* from drastic performance problems. Using this value, we derive the rest
* of the table. Since the fragmentation value is never stored on disk, it
* is possible to change these calculations in the future.
*/
int zfs_frag_table[FRAGMENTATION_TABLE_SIZE] = {
100, /* 512B */
100, /* 1K */
98, /* 2K */
95, /* 4K */
90, /* 8K */
80, /* 16K */
70, /* 32K */
60, /* 64K */
50, /* 128K */
40, /* 256K */
30, /* 512K */
20, /* 1M */
15, /* 2M */
10, /* 4M */
5, /* 8M */
0 /* 16M */
};
/*
* Calclate the metaslab's fragmentation metric. A return value
* of ZFS_FRAG_INVALID means that the metaslab has not been upgraded and does
* not support this metric. Otherwise, the return value should be in the
* range [0, 100].
*/
static uint64_t
metaslab_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);
int i;
if (!feature_enabled)
return (ZFS_FRAG_INVALID);
/*
* A null space map means that the entire metaslab is free
* and thus is not fragmented.
*/
if (msp->ms_sm == NULL)
return (0);
/*
* 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)) {
vdev_t *vd = msp->ms_group->mg_vd;
if (spa_writeable(vd->vdev_spa)) {
uint64_t txg = spa_syncing_txg(spa);
msp->ms_condense_wanted = B_TRUE;
vdev_dirty(vd, VDD_METASLAB, msp, txg + 1);
spa_dbgmsg(spa, "txg %llu, requesting force condense: "
"msp %p, vd %p", txg, msp, vd);
}
return (ZFS_FRAG_INVALID);
}
for (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);
return (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_weight(metaslab_t *msp)
{
metaslab_group_t *mg = msp->ms_group;
vdev_t *vd = mg->mg_vd;
uint64_t weight, space;
ASSERT(MUTEX_HELD(&msp->ms_lock));
/*
* This vdev is in the process of being removed so there is nothing
* for us to do here.
*/
if (vd->vdev_removing) {
ASSERT0(space_map_allocated(msp->ms_sm));
ASSERT0(vd->vdev_ms_shift);
return (0);
}
/*
* The baseline weight is the metaslab's free space.
*/
space = msp->ms_size - space_map_allocated(msp->ms_sm);
msp->ms_fragmentation = metaslab_fragmentation(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);
}
return (weight);
}
static int
metaslab_activate(metaslab_t *msp, uint64_t activation_weight)
{
ASSERT(MUTEX_HELD(&msp->ms_lock));
if ((msp->ms_weight & METASLAB_ACTIVE_MASK) == 0) {
metaslab_load_wait(msp);
if (!msp->ms_loaded) {
int error = metaslab_load(msp);
if (error) {
metaslab_group_sort(msp->ms_group, msp, 0);
return (error);
}
}
metaslab_group_sort(msp->ms_group, msp,
msp->ms_weight | activation_weight);
}
ASSERT(msp->ms_loaded);
ASSERT(msp->ms_weight & METASLAB_ACTIVE_MASK);
return (0);
}
static void
metaslab_passivate(metaslab_t *msp, uint64_t size)
{
/*
* If size < SPA_MINBLOCKSIZE, then we will not allocate from
* this metaslab again. In that case, it had better be empty,
* or we would be leaving space on the table.
*/
ASSERT(size >= SPA_MINBLOCKSIZE || range_tree_space(msp->ms_tree) == 0);
metaslab_group_sort(msp->ms_group, msp, MIN(msp->ms_weight, size));
ASSERT((msp->ms_weight & METASLAB_ACTIVE_MASK) == 0);
}
static void
metaslab_preload(void *arg)
{
metaslab_t *msp = arg;
spa_t *spa = msp->ms_group->mg_vd->vdev_spa;
fstrans_cookie_t cookie = spl_fstrans_mark();
ASSERT(!MUTEX_HELD(&msp->ms_group->mg_lock));
mutex_enter(&msp->ms_lock);
metaslab_load_wait(msp);
if (!msp->ms_loaded)
(void) metaslab_load(msp);
/*
* Set the ms_access_txg value so that we don't unload it right away.
*/
msp->ms_access_txg = spa_syncing_txg(spa) + metaslab_unload_delay + 1;
mutex_exit(&msp->ms_lock);
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
*/
msp = avl_first(t);
while (msp != NULL) {
metaslab_t *msp_next = AVL_NEXT(t, msp);
/*
* We preload only the maximum number of metaslabs specified
* by metaslab_preload_limit. If a metaslab is being forced
* to condense then we preload it too. This will ensure
* that force condensing happens in the next txg.
*/
if (++m > metaslab_preload_limit && !msp->ms_condense_wanted) {
msp = msp_next;
continue;
}
/*
* We must drop the metaslab group lock here to preserve
* lock ordering with the ms_lock (when grabbing both
* the mg_lock and the ms_lock, the ms_lock must be taken
* first). As a result, it is possible that the ordering
* of the metaslabs within the avl tree may change before
* we reacquire the lock. The metaslab cannot be removed from
* the tree while we're in syncing context so it is safe to
* drop the mg_lock here. If the metaslabs are reordered
* nothing will break -- we just may end up loading a
* less than optimal one.
*/
mutex_exit(&mg->mg_lock);
VERIFY(taskq_dispatch(mg->mg_taskq, metaslab_preload,
msp, TQ_SLEEP) != 0);
mutex_enter(&mg->mg_lock);
msp = msp_next;
}
mutex_exit(&mg->mg_lock);
}
/*
* Determine if the space map's on-disk footprint is past our tolerance
* for inefficiency. We would like to use the following criteria to make
* our decision:
*
* 1. The size of the space map object should not dramatically increase as a
* result of writing out the free space range tree.
*
* 2. The minimal on-disk space map representation is zfs_condense_pct/100
* times the size than the free space range tree representation
* (i.e. zfs_condense_pct = 110 and in-core = 1MB, minimal = 1.1.MB).
*
* 3. The on-disk size of the space map should actually decrease.
*
* Checking the first condition is tricky since we don't want to walk
* the entire AVL tree calculating the estimated on-disk size. Instead we
* use the size-ordered range tree in the metaslab and calculate the
* size required to write out the largest segment in our free tree. If the
* size required to represent that segment on disk is larger than the space
* map object then we avoid condensing this map.
*
* To determine the second criterion we use a best-case estimate and assume
* each segment can be represented on-disk as a single 64-bit entry. We refer
* to this best-case estimate as the space map's minimal form.
*
* Unfortunately, we cannot compute the on-disk size of the space map in this
* context because we cannot accurately compute the effects of compression, etc.
* Instead, we apply the heuristic described in the block comment for
* zfs_metaslab_condense_block_threshold - we only condense if the space used
* is greater than a threshold number of blocks.
*/
static boolean_t
metaslab_should_condense(metaslab_t *msp)
{
space_map_t *sm = msp->ms_sm;
range_seg_t *rs;
uint64_t size, entries, segsz, object_size, optimal_size, record_size;
dmu_object_info_t doi;
uint64_t vdev_blocksize = 1 << msp->ms_group->mg_vd->vdev_ashift;
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT(msp->ms_loaded);
/*
* Use the ms_size_tree range tree, which is ordered by size, to
* obtain the largest segment in the free tree. We always condense
* metaslabs that are empty and metaslabs for which a condense
* request has been made.
*/
rs = avl_last(&msp->ms_size_tree);
if (rs == NULL || msp->ms_condense_wanted)
return (B_TRUE);
/*
* Calculate the number of 64-bit entries this segment would
* require when written to disk. If this single segment would be
* larger on-disk than the entire current on-disk structure, then
* clearly condensing will increase the on-disk structure size.
*/
size = (rs->rs_end - rs->rs_start) >> sm->sm_shift;
entries = size / (MIN(size, SM_RUN_MAX));
segsz = entries * sizeof (uint64_t);
optimal_size = sizeof (uint64_t) * avl_numnodes(&msp->ms_tree->rt_root);
object_size = space_map_length(msp->ms_sm);
dmu_object_info_from_db(sm->sm_dbuf, &doi);
record_size = MAX(doi.doi_data_block_size, vdev_blocksize);
return (segsz <= object_size &&
object_size >= (optimal_size * zfs_condense_pct / 100) &&
object_size > zfs_metaslab_condense_block_threshold * record_size);
}
/*
* Condense the on-disk space map representation to its minimized form.
* The minimized form consists of a small number of allocations followed by
* the entries of the free range tree.
*/
static void
metaslab_condense(metaslab_t *msp, uint64_t txg, dmu_tx_t *tx)
{
spa_t *spa = msp->ms_group->mg_vd->vdev_spa;
range_tree_t *freetree = msp->ms_freetree[txg & TXG_MASK];
range_tree_t *condense_tree;
space_map_t *sm = msp->ms_sm;
int t;
ASSERT(MUTEX_HELD(&msp->ms_lock));
ASSERT3U(spa_sync_pass(spa), ==, 1);
ASSERT(msp->ms_loaded);
spa_dbgmsg(spa, "condensing: txg %llu, msp[%llu] %p, vdev id %llu, "
"spa %s, smp size %llu, segments %lu, forcing condense=%s", txg,
msp->ms_id, msp, msp->ms_group->mg_vd->vdev_id,
msp->ms_group->mg_vd->vdev_spa->spa_name,
space_map_length(msp->ms_sm), avl_numnodes(&msp->ms_tree->rt_root),
msp->ms_condense_wanted ? "TRUE" : "FALSE");
msp->ms_condense_wanted = B_FALSE;
/*
* Create an range tree that is 100% allocated. We remove segments
* that have been freed in this txg, any deferred frees that exist,
* and any allocation in the future. Removing segments should be
* a relatively inexpensive operation since we expect these trees to
* have a small number of nodes.
*/
condense_tree = range_tree_create(NULL, NULL, &msp->ms_lock);
range_tree_add(condense_tree, msp->ms_start, msp->ms_size);
/*
* Remove what's been freed in this txg from the condense_tree.
* Since we're in sync_pass 1, we know that all the frees from
* this txg are in the freetree.
*/
range_tree_walk(freetree, range_tree_remove, condense_tree);
for (t = 0; t < TXG_DEFER_SIZE; t++) {
range_tree_walk(msp->ms_defertree[t],
range_tree_remove, condense_tree);
}
for (t = 1; t < TXG_CONCURRENT_STATES; t++) {
range_tree_walk(msp->ms_alloctree[(txg + t) & TXG_MASK],
range_tree_remove, condense_tree);
}
/*
* We're about to drop the metaslab's lock thus allowing
* other consumers to change it's content. Set the
* metaslab's ms_condensing flag to ensure that
* allocations on this metaslab do not occur while we're
* in the middle of committing it to disk. This is only critical
* for the ms_tree as all other range trees use per txg
* views of their content.
*/
msp->ms_condensing = B_TRUE;
mutex_exit(&msp->ms_lock);
space_map_truncate(sm, tx);
mutex_enter(&msp->ms_lock);
/*
* While we would ideally like to create a space_map representation
* that consists only of allocation records, doing so can be
* prohibitively expensive because the in-core free tree can be
* large, and therefore computationally expensive to subtract
* from the condense_tree. Instead we sync out two trees, a cheap
* allocation only tree followed by the in-core free tree. While not
* optimal, this is typically close to optimal, and much cheaper to
* compute.
*/
space_map_write(sm, condense_tree, SM_ALLOC, tx);
range_tree_vacate(condense_tree, NULL, NULL);
range_tree_destroy(condense_tree);
space_map_write(sm, msp->ms_tree, SM_FREE, tx);
msp->ms_condensing = B_FALSE;
}
/*
* Write a metaslab to disk in the context of the specified transaction group.
*/
void
metaslab_sync(metaslab_t *msp, uint64_t txg)
{
metaslab_group_t *mg = msp->ms_group;
vdev_t *vd = mg->mg_vd;
spa_t *spa = vd->vdev_spa;
objset_t *mos = spa_meta_objset(spa);
range_tree_t *alloctree = msp->ms_alloctree[txg & TXG_MASK];
range_tree_t **freetree = &msp->ms_freetree[txg & TXG_MASK];
range_tree_t **freed_tree =
&msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK];
dmu_tx_t *tx;
uint64_t object = space_map_object(msp->ms_sm);
ASSERT(!vd->vdev_ishole);
/*
* This metaslab has just been added so there's no work to do now.
*/
if (*freetree == NULL) {
ASSERT3P(alloctree, ==, NULL);
return;
}
ASSERT3P(alloctree, !=, NULL);
ASSERT3P(*freetree, !=, NULL);
ASSERT3P(*freed_tree, !=, NULL);
/*
* Normally, we don't want to process a metaslab if there
* are no allocations or frees to perform. However, if the metaslab
* is being forced to condense we need to let it through.
*/
if (range_tree_space(alloctree) == 0 &&
range_tree_space(*freetree) == 0 &&
!msp->ms_condense_wanted)
return;
/*
* The only state that can actually be changing concurrently with
* metaslab_sync() is the metaslab's ms_tree. No other thread can
* be modifying this txg's alloctree, freetree, freed_tree, or
* space_map_phys_t. Therefore, we only hold ms_lock to satify
* space_map ASSERTs. We drop it whenever we call into the DMU,
* because the DMU can call down to us (e.g. via zio_free()) at
* any time.
*/
tx = dmu_tx_create_assigned(spa_get_dsl(spa), txg);
if (msp->ms_sm == NULL) {
uint64_t new_object;
new_object = space_map_alloc(mos, tx);
VERIFY3U(new_object, !=, 0);
VERIFY0(space_map_open(&msp->ms_sm, mos, new_object,
msp->ms_start, msp->ms_size, vd->vdev_ashift,
&msp->ms_lock));
ASSERT(msp->ms_sm != NULL);
}
mutex_enter(&msp->ms_lock);
/*
* Note: metaslab_condense() clears the space_map's histogram.
* Therefore we muse verify and remove this histogram before
* condensing.
*/
metaslab_group_histogram_verify(mg);
metaslab_class_histogram_verify(mg->mg_class);
metaslab_group_histogram_remove(mg, msp);
if (msp->ms_loaded && spa_sync_pass(spa) == 1 &&
metaslab_should_condense(msp)) {
metaslab_condense(msp, txg, tx);
} else {
space_map_write(msp->ms_sm, alloctree, SM_ALLOC, tx);
space_map_write(msp->ms_sm, *freetree, SM_FREE, tx);
}
if (msp->ms_loaded) {
/*
* When the space map is loaded, we have an accruate
* histogram in the range tree. This gives us an opportunity
* to bring the space map's histogram up-to-date so we clear
* it first before updating it.
*/
space_map_histogram_clear(msp->ms_sm);
space_map_histogram_add(msp->ms_sm, msp->ms_tree, tx);
} else {
/*
* Since the space map is not loaded we simply update the
* exisiting histogram with what was freed in this txg. This
* means that the on-disk histogram may not have an accurate
* view of the free space but it's close enough to allow
* us to make allocation decisions.
*/
space_map_histogram_add(msp->ms_sm, *freetree, tx);
}
metaslab_group_histogram_add(mg, msp);
metaslab_group_histogram_verify(mg);
metaslab_class_histogram_verify(mg->mg_class);
/*
* For sync pass 1, we avoid traversing this txg's free range tree
* and instead will just swap the pointers for freetree and
* freed_tree. We can safely do this since the freed_tree is
* guaranteed to be empty on the initial pass.
*/
if (spa_sync_pass(spa) == 1) {
range_tree_swap(freetree, freed_tree);
} else {
range_tree_vacate(*freetree, range_tree_add, *freed_tree);
}
range_tree_vacate(alloctree, NULL, NULL);
ASSERT0(range_tree_space(msp->ms_alloctree[txg & TXG_MASK]));
ASSERT0(range_tree_space(msp->ms_freetree[txg & TXG_MASK]));
mutex_exit(&msp->ms_lock);
if (object != space_map_object(msp->ms_sm)) {
object = space_map_object(msp->ms_sm);
dmu_write(mos, vd->vdev_ms_array, sizeof (uint64_t) *
msp->ms_id, sizeof (uint64_t), &object, tx);
}
dmu_tx_commit(tx);
}
/*
* Called after a transaction group has completely synced to mark
* all of the metaslab's free space as usable.
*/
void
metaslab_sync_done(metaslab_t *msp, uint64_t txg)
{
metaslab_group_t *mg = msp->ms_group;
vdev_t *vd = mg->mg_vd;
range_tree_t **freed_tree;
range_tree_t **defer_tree;
int64_t alloc_delta, defer_delta;
int t;
ASSERT(!vd->vdev_ishole);
mutex_enter(&msp->ms_lock);
/*
* If this metaslab is just becoming available, initialize its
* alloctrees, freetrees, and defertree and add its capacity to
* the vdev.
*/
if (msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK] == NULL) {
for (t = 0; t < TXG_SIZE; t++) {
ASSERT(msp->ms_alloctree[t] == NULL);
ASSERT(msp->ms_freetree[t] == NULL);
msp->ms_alloctree[t] = range_tree_create(NULL, msp,
&msp->ms_lock);
msp->ms_freetree[t] = range_tree_create(NULL, msp,
&msp->ms_lock);
}
for (t = 0; t < TXG_DEFER_SIZE; t++) {
ASSERT(msp->ms_defertree[t] == NULL);
msp->ms_defertree[t] = range_tree_create(NULL, msp,
&msp->ms_lock);
}
vdev_space_update(vd, 0, 0, msp->ms_size);
}
freed_tree = &msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK];
defer_tree = &msp->ms_defertree[txg % TXG_DEFER_SIZE];
alloc_delta = space_map_alloc_delta(msp->ms_sm);
defer_delta = range_tree_space(*freed_tree) -
range_tree_space(*defer_tree);
vdev_space_update(vd, alloc_delta + defer_delta, defer_delta, 0);
ASSERT0(range_tree_space(msp->ms_alloctree[txg & TXG_MASK]));
ASSERT0(range_tree_space(msp->ms_freetree[txg & TXG_MASK]));
/*
* If there's a metaslab_load() in progress, wait for it to complete
* so that we have a consistent view of the in-core space map.
*/
metaslab_load_wait(msp);
/*
* Move the frees from the defer_tree back to the free
* range tree (if it's loaded). Swap the freed_tree and the
* defer_tree -- this is safe to do because we've just emptied out
* the defer_tree.
*/
range_tree_vacate(*defer_tree,
msp->ms_loaded ? range_tree_add : NULL, msp->ms_tree);
range_tree_swap(freed_tree, defer_tree);
space_map_update(msp->ms_sm);
msp->ms_deferspace += defer_delta;
ASSERT3S(msp->ms_deferspace, >=, 0);
ASSERT3S(msp->ms_deferspace, <=, msp->ms_size);
if (msp->ms_deferspace != 0) {
/*
* Keep syncing this metaslab until all deferred frees
* are back in circulation.
*/
vdev_dirty(vd, VDD_METASLAB, msp, txg + 1);
}
if (msp->ms_loaded && msp->ms_access_txg < txg) {
for (t = 1; t < TXG_CONCURRENT_STATES; t++) {
VERIFY0(range_tree_space(
msp->ms_alloctree[(txg + t) & TXG_MASK]));
}
if (!metaslab_debug_unload)
metaslab_unload(msp);
}
metaslab_group_sort(mg, msp, metaslab_weight(msp));
mutex_exit(&msp->ms_lock);
}
void
metaslab_sync_reassess(metaslab_group_t *mg)
{
metaslab_group_alloc_update(mg);
mg->mg_fragmentation = metaslab_group_fragmentation(mg);
/*
* Preload the next potential metaslabs
*/
metaslab_group_preload(mg);
}
static uint64_t
metaslab_distance(metaslab_t *msp, dva_t *dva)
{
uint64_t ms_shift = msp->ms_group->mg_vd->vdev_ms_shift;
uint64_t offset = DVA_GET_OFFSET(dva) >> ms_shift;
uint64_t start = msp->ms_id;
if (msp->ms_group->mg_vd->vdev_id != DVA_GET_VDEV(dva))
return (1ULL << 63);
if (offset < start)
return ((start - offset) << ms_shift);
if (offset > start)
return ((offset - start) << ms_shift);
return (0);
}
static uint64_t
metaslab_group_alloc(metaslab_group_t *mg, uint64_t psize, uint64_t asize,
uint64_t txg, uint64_t min_distance, dva_t *dva, int d)
{
spa_t *spa = mg->mg_vd->vdev_spa;
metaslab_t *msp = NULL;
uint64_t offset = -1ULL;
avl_tree_t *t = &mg->mg_metaslab_tree;
uint64_t activation_weight;
uint64_t target_distance;
int i;
activation_weight = METASLAB_WEIGHT_PRIMARY;
for (i = 0; i < d; i++) {
if (DVA_GET_VDEV(&dva[i]) == mg->mg_vd->vdev_id) {
activation_weight = METASLAB_WEIGHT_SECONDARY;
break;
}
}
for (;;) {
boolean_t was_active;
mutex_enter(&mg->mg_lock);
for (msp = avl_first(t); msp; msp = AVL_NEXT(t, msp)) {
if (msp->ms_weight < asize) {
spa_dbgmsg(spa, "%s: failed to meet weight "
"requirement: vdev %llu, txg %llu, mg %p, "
"msp %p, psize %llu, asize %llu, "
"weight %llu", spa_name(spa),
mg->mg_vd->vdev_id, txg,
mg, msp, psize, asize, msp->ms_weight);
mutex_exit(&mg->mg_lock);
return (-1ULL);
}
/*
* If the selected metaslab is condensing, skip it.
*/
if (msp->ms_condensing)
continue;
was_active = msp->ms_weight & METASLAB_ACTIVE_MASK;
if (activation_weight == METASLAB_WEIGHT_PRIMARY)
break;
target_distance = min_distance +
(space_map_allocated(msp->ms_sm) != 0 ? 0 :
min_distance >> 1);
for (i = 0; i < d; i++)
if (metaslab_distance(msp, &dva[i]) <
target_distance)
break;
if (i == d)
break;
}
mutex_exit(&mg->mg_lock);
if (msp == NULL)
return (-1ULL);
mutex_enter(&msp->ms_lock);
/*
* Ensure that the metaslab we have selected is still
* capable of handling our request. It's possible that
* another thread may have changed the weight while we
* were blocked on the metaslab lock.
*/
if (msp->ms_weight < asize || (was_active &&
!(msp->ms_weight & METASLAB_ACTIVE_MASK) &&
activation_weight == METASLAB_WEIGHT_PRIMARY)) {
mutex_exit(&msp->ms_lock);
continue;
}
if ((msp->ms_weight & METASLAB_WEIGHT_SECONDARY) &&
activation_weight == METASLAB_WEIGHT_PRIMARY) {
metaslab_passivate(msp,
msp->ms_weight & ~METASLAB_ACTIVE_MASK);
mutex_exit(&msp->ms_lock);
continue;
}
if (metaslab_activate(msp, activation_weight) != 0) {
mutex_exit(&msp->ms_lock);
continue;
}
/*
* If this metaslab is currently condensing then pick again as
* we can't manipulate this metaslab until it's committed
* to disk.
*/
if (msp->ms_condensing) {
mutex_exit(&msp->ms_lock);
continue;
}
if ((offset = metaslab_block_alloc(msp, asize)) != -1ULL)
break;
metaslab_passivate(msp, metaslab_block_maxsize(msp));
mutex_exit(&msp->ms_lock);
}
if (range_tree_space(msp->ms_alloctree[txg & TXG_MASK]) == 0)
vdev_dirty(mg->mg_vd, VDD_METASLAB, msp, txg);
range_tree_add(msp->ms_alloctree[txg & TXG_MASK], offset, asize);
msp->ms_access_txg = txg + metaslab_unload_delay;
mutex_exit(&msp->ms_lock);
return (offset);
}
/*
* Allocate a block for the specified i/o.
*/
static int
metaslab_alloc_dva(spa_t *spa, metaslab_class_t *mc, uint64_t psize,
dva_t *dva, int d, dva_t *hintdva, uint64_t txg, int flags)
{
metaslab_group_t *mg, *fast_mg, *rotor;
vdev_t *vd;
int dshift = 3;
int all_zero;
int zio_lock = B_FALSE;
boolean_t allocatable;
uint64_t offset = -1ULL;
uint64_t asize;
uint64_t distance;
ASSERT(!DVA_IS_VALID(&dva[d]));
/*
* For testing, make some blocks above a certain size be gang blocks.
*/
if (psize >= metaslab_gang_bang && (ddi_get_lbolt() & 3) == 0)
return (SET_ERROR(ENOSPC));
/*
* Start at the rotor and loop through all mgs until we find something.
* Note that there's no locking on mc_rotor or mc_aliquot because
* nothing actually breaks if we miss a few updates -- we just won't
* allocate quite as evenly. It all balances out over time.
*
* If we are doing ditto or log blocks, try to spread them across
* consecutive vdevs. If we're forced to reuse a vdev before we've
* allocated all of our ditto blocks, then try and spread them out on
* that vdev as much as possible. If it turns out to not be possible,
* gradually lower our standards until anything becomes acceptable.
* Also, allocating on consecutive vdevs (as opposed to random vdevs)
* gives us hope of containing our fault domains to something we're
* able to reason about. Otherwise, any two top-level vdev failures
* will guarantee the loss of data. With consecutive allocation,
* only two adjacent top-level vdev failures will result in data loss.
*
* If we are doing gang blocks (hintdva is non-NULL), try to keep
* ourselves on the same vdev as our gang block header. That
* way, we can hope for locality in vdev_cache, plus it makes our
* fault domains something tractable.
*/
if (hintdva) {
vd = vdev_lookup_top(spa, DVA_GET_VDEV(&hintdva[d]));
/*
* It's possible the vdev we're using as the hint no
* longer exists (i.e. removed). Consult the rotor when
* all else fails.
*/
if (vd != NULL) {
mg = vd->vdev_mg;
if (flags & METASLAB_HINTBP_AVOID &&
mg->mg_next != NULL)
mg = mg->mg_next;
} else {
mg = mc->mc_rotor;
}
} else if (d != 0) {
vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[d - 1]));
mg = vd->vdev_mg->mg_next;
} else 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 {
mg = mc->mc_rotor;
}
/*
* If the hint put us into the wrong metaslab class, or into a
* metaslab group that has been passivated, just follow the rotor.
*/
if (mg->mg_class != mc || mg->mg_activation_count <= 0)
mg = mc->mc_rotor;
rotor = mg;
top:
all_zero = B_TRUE;
do {
ASSERT(mg->mg_activation_count == 1);
vd = mg->mg_vd;
/*
* Don't allocate from faulted devices.
*/
if (zio_lock) {
spa_config_enter(spa, SCL_ZIO, FTAG, RW_READER);
allocatable = vdev_allocatable(vd);
spa_config_exit(spa, SCL_ZIO, FTAG);
} else {
allocatable = vdev_allocatable(vd);
}
/*
* Determine if the selected metaslab group is eligible
* for allocations. If we're ganging or have requested
* an allocation for the smallest gang block size
* then we don't want to avoid allocating to the this
* metaslab group. If we're in this condition we should
* try to allocate from any device possible so that we
* don't inadvertently return ENOSPC and suspend the pool
* even though space is still available.
*/
if (allocatable && CAN_FASTGANG(flags) &&
psize > SPA_GANGBLOCKSIZE)
allocatable = metaslab_group_allocatable(mg);
if (!allocatable)
goto next;
/*
* Avoid writing single-copy data to a failing vdev
* unless the user instructs us that it is okay.
*/
if ((vd->vdev_stat.vs_write_errors > 0 ||
vd->vdev_state < VDEV_STATE_HEALTHY) &&
d == 0 && dshift == 3 && vd->vdev_children == 0) {
all_zero = B_FALSE;
goto next;
}
ASSERT(mg->mg_class == mc);
distance = vd->vdev_asize >> dshift;
if (distance <= (1ULL << vd->vdev_ms_shift))
distance = 0;
else
all_zero = B_FALSE;
asize = vdev_psize_to_asize(vd, psize);
ASSERT(P2PHASE(asize, 1ULL << vd->vdev_ashift) == 0);
offset = metaslab_group_alloc(mg, psize, asize, txg, distance,
dva, d);
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 (!all_zero) {
dshift++;
ASSERT(dshift < 64);
goto top;
}
if (!allocatable && !zio_lock) {
dshift = 3;
zio_lock = B_TRUE;
goto top;
}
bzero(&dva[d], sizeof (dva_t));
return (SET_ERROR(ENOSPC));
}
/*
* Free the block represented by DVA in the context of the specified
* transaction group.
*/
static void
metaslab_free_dva(spa_t *spa, const dva_t *dva, uint64_t txg, boolean_t now)
{
uint64_t vdev = DVA_GET_VDEV(dva);
uint64_t offset = DVA_GET_OFFSET(dva);
uint64_t size = DVA_GET_ASIZE(dva);
vdev_t *vd;
metaslab_t *msp;
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;
}
msp = vd->vdev_ms[offset >> vd->vdev_ms_shift];
if (DVA_GET_GANG(dva))
size = vdev_psize_to_asize(vd, SPA_GANGBLOCKSIZE);
mutex_enter(&msp->ms_lock);
if (now) {
range_tree_remove(msp->ms_alloctree[txg & TXG_MASK],
offset, size);
VERIFY(!msp->ms_condensing);
VERIFY3U(offset, >=, msp->ms_start);
VERIFY3U(offset + size, <=, msp->ms_start + msp->ms_size);
VERIFY3U(range_tree_space(msp->ms_tree) + size, <=,
msp->ms_size);
VERIFY0(P2PHASE(offset, 1ULL << vd->vdev_ashift));
VERIFY0(P2PHASE(size, 1ULL << vd->vdev_ashift));
range_tree_add(msp->ms_tree, offset, size);
} else {
if (range_tree_space(msp->ms_freetree[txg & TXG_MASK]) == 0)
vdev_dirty(vd, VDD_METASLAB, msp, txg);
range_tree_add(msp->ms_freetree[txg & TXG_MASK],
offset, size);
}
mutex_exit(&msp->ms_lock);
}
/*
* Intent log support: upon opening the pool after a crash, notify the SPA
* of blocks that the intent log has allocated for immediate write, but
* which are still considered free by the SPA because the last transaction
* group didn't commit yet.
*/
static int
metaslab_claim_dva(spa_t *spa, const dva_t *dva, uint64_t txg)
{
uint64_t vdev = DVA_GET_VDEV(dva);
uint64_t offset = DVA_GET_OFFSET(dva);
uint64_t size = DVA_GET_ASIZE(dva);
vdev_t *vd;
metaslab_t *msp;
int error = 0;
ASSERT(DVA_IS_VALID(dva));
if ((vd = vdev_lookup_top(spa, vdev)) == NULL ||
(offset >> vd->vdev_ms_shift) >= vd->vdev_ms_count)
return (SET_ERROR(ENXIO));
msp = vd->vdev_ms[offset >> vd->vdev_ms_shift];
if (DVA_GET_GANG(dva))
size = vdev_psize_to_asize(vd, SPA_GANGBLOCKSIZE);
mutex_enter(&msp->ms_lock);
if ((txg != 0 && spa_writeable(spa)) || !msp->ms_loaded)
error = metaslab_activate(msp, METASLAB_WEIGHT_SECONDARY);
if (error == 0 && !range_tree_contains(msp->ms_tree, offset, size))
error = SET_ERROR(ENOENT);
if (error || txg == 0) { /* txg == 0 indicates dry run */
mutex_exit(&msp->ms_lock);
return (error);
}
VERIFY(!msp->ms_condensing);
VERIFY0(P2PHASE(offset, 1ULL << vd->vdev_ashift));
VERIFY0(P2PHASE(size, 1ULL << vd->vdev_ashift));
VERIFY3U(range_tree_space(msp->ms_tree) - size, <=, msp->ms_size);
range_tree_remove(msp->ms_tree, offset, size);
if (spa_writeable(spa)) { /* don't dirty if we're zdb(1M) */
if (range_tree_space(msp->ms_alloctree[txg & TXG_MASK]) == 0)
vdev_dirty(vd, VDD_METASLAB, msp, txg);
range_tree_add(msp->ms_alloctree[txg & TXG_MASK], offset, size);
}
mutex_exit(&msp->ms_lock);
return (0);
}
int
metaslab_alloc(spa_t *spa, metaslab_class_t *mc, uint64_t psize, blkptr_t *bp,
int ndvas, uint64_t txg, blkptr_t *hintbp, int flags)
{
dva_t *dva = bp->blk_dva;
dva_t *hintdva = hintbp->blk_dva;
int d, error = 0;
ASSERT(bp->blk_birth == 0);
ASSERT(BP_PHYSICAL_BIRTH(bp) == 0);
spa_config_enter(spa, SCL_ALLOC, FTAG, RW_READER);
if (mc->mc_rotor == NULL) { /* no vdevs in this class */
spa_config_exit(spa, SCL_ALLOC, FTAG);
return (SET_ERROR(ENOSPC));
}
ASSERT(ndvas > 0 && ndvas <= spa_max_replication(spa));
ASSERT(BP_GET_NDVAS(bp) == 0);
ASSERT(hintbp == NULL || ndvas <= BP_GET_NDVAS(hintbp));
for (d = 0; d < ndvas; d++) {
error = metaslab_alloc_dva(spa, mc, psize, dva, d, hintdva,
txg, flags);
if (error != 0) {
for (d--; d >= 0; d--) {
metaslab_free_dva(spa, &dva[d], txg, B_TRUE);
bzero(&dva[d], sizeof (dva_t));
}
spa_config_exit(spa, SCL_ALLOC, FTAG);
return (error);
}
}
ASSERT(error == 0);
ASSERT(BP_GET_NDVAS(bp) == ndvas);
spa_config_exit(spa, SCL_ALLOC, FTAG);
BP_SET_BIRTH(bp, txg, 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 d, ndvas = BP_GET_NDVAS(bp);
ASSERT(!BP_IS_HOLE(bp));
ASSERT(!now || bp->blk_birth >= spa_syncing_txg(spa));
spa_config_enter(spa, SCL_FREE, FTAG, RW_READER);
for (d = 0; d < ndvas; d++)
metaslab_free_dva(spa, &dva[d], txg, now);
spa_config_exit(spa, SCL_FREE, FTAG);
}
int
metaslab_claim(spa_t *spa, const blkptr_t *bp, uint64_t txg)
{
const dva_t *dva = bp->blk_dva;
int ndvas = BP_GET_NDVAS(bp);
int d, 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 (d = 0; d < ndvas; d++)
if ((error = metaslab_claim_dva(spa, &dva[d], txg)) != 0)
break;
spa_config_exit(spa, SCL_ALLOC, FTAG);
ASSERT(error == 0 || txg == 0);
return (error);
}
void
metaslab_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);
}
void
metaslab_check_free(spa_t *spa, const blkptr_t *bp)
{
int i, j;
if ((zfs_flags & ZFS_DEBUG_ZIO_FREE) == 0)
return;
spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
for (i = 0; i < BP_GET_NDVAS(bp); i++) {
uint64_t vdev = DVA_GET_VDEV(&bp->blk_dva[i]);
vdev_t *vd = vdev_lookup_top(spa, vdev);
uint64_t offset = DVA_GET_OFFSET(&bp->blk_dva[i]);
uint64_t size = DVA_GET_ASIZE(&bp->blk_dva[i]);
metaslab_t *msp = vd->vdev_ms[offset >> vd->vdev_ms_shift];
if (msp->ms_loaded)
range_tree_verify(msp->ms_tree, offset, size);
for (j = 0; j < TXG_SIZE; j++)
range_tree_verify(msp->ms_freetree[j], offset, size);
for (j = 0; j < TXG_DEFER_SIZE; j++)
range_tree_verify(msp->ms_defertree[j], offset, size);
}
spa_config_exit(spa, SCL_VDEV, FTAG);
}
#if defined(_KERNEL) && defined(HAVE_SPL)
module_param(metaslab_aliquot, ulong, 0644);
module_param(metaslab_debug_load, int, 0644);
module_param(metaslab_debug_unload, int, 0644);
module_param(metaslab_preload_enabled, int, 0644);
module_param(zfs_mg_noalloc_threshold, int, 0644);
module_param(zfs_mg_fragmentation_threshold, int, 0644);
module_param(zfs_metaslab_fragmentation_threshold, int, 0644);
module_param(metaslab_fragmentation_factor_enabled, int, 0644);
module_param(metaslab_lba_weighting_enabled, int, 0644);
module_param(metaslab_bias_enabled, int, 0644);
MODULE_PARM_DESC(metaslab_aliquot,
"allocation granularity (a.k.a. stripe size)");
MODULE_PARM_DESC(metaslab_debug_load,
"load all metaslabs when pool is first opened");
MODULE_PARM_DESC(metaslab_debug_unload,
"prevent metaslabs from being unloaded");
MODULE_PARM_DESC(metaslab_preload_enabled,
"preload potential metaslabs during reassessment");
MODULE_PARM_DESC(zfs_mg_noalloc_threshold,
"percentage of free space for metaslab group to allow allocation");
MODULE_PARM_DESC(zfs_mg_fragmentation_threshold,
"fragmentation for metaslab group to allow allocation");
MODULE_PARM_DESC(zfs_metaslab_fragmentation_threshold,
"fragmentation for metaslab to allow allocation");
MODULE_PARM_DESC(metaslab_fragmentation_factor_enabled,
"use the fragmentation metric to prefer less fragmented metaslabs");
MODULE_PARM_DESC(metaslab_lba_weighting_enabled,
"prefer metaslabs with lower LBAs");
MODULE_PARM_DESC(metaslab_bias_enabled,
"enable metaslab group biasing");
#endif /* _KERNEL && HAVE_SPL */