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freebsd-nq/module/zfs/ddt.c
Paul Dagnelie ca5777793e Reduce loaded range tree memory usage 
This patch implements a new tree structure for ZFS, and uses it to 
store range trees more efficiently.

The new structure is approximately a B-tree, though there are some 
small differences from the usual characterizations. The tree has core 
nodes and leaf nodes; each contain data elements, which the elements 
in the core nodes acting as separators between its children. The 
difference between core and leaf nodes is that the core nodes have an 
array of children, while leaf nodes don't. Every node in the tree may 
be only partially full; in most cases, they are all at least 50% full 
(in terms of element count) except for the root node, which can be 
less full. Underfull nodes will steal from their neighbors or merge to 
remain full enough, while overfull nodes will split in two. The data 
elements are contained in tree-controlled buffers; they are copied 
into these on insertion, and overwritten on deletion. This means that 
the elements are not independently allocated, which reduces overhead, 
but also means they can't be shared between trees (and also that 
pointers to them are only valid until a side-effectful tree operation 
occurs). The overhead varies based on how dense the tree is, but is 
usually on the order of about 50% of the element size; the per-node 
overheads are very small, and so don't make a significant difference. 
The trees can accept arbitrary records; they accept a size and a 
comparator to allow them to be used for a variety of purposes.

The new trees replace the AVL trees used in the range trees today. 
Currently, the range_seg_t structure contains three 8 byte integers 
of payload and two 24 byte avl_tree_node_ts to handle its storage in 
both an offset-sorted tree and a size-sorted tree (total size: 64 
bytes). In the new model, the range seg structures are usually two 4 
byte integers, but a separate one needs to exist for the size-sorted 
and offset-sorted tree. Between the raw size, the 50% overhead, and 
the double storage, the new btrees are expected to use 8*1.5*2 = 24 
bytes per record, or 33.3% as much memory as the AVL trees (this is 
for the purposes of storing metaslab range trees; for other purposes, 
like scrubs, they use ~50% as much memory).

We reduced the size of the payload in the range segments by teaching 
range trees about starting offsets and shifts; since metaslabs have a 
fixed starting offset, and they all operate in terms of disk sectors, 
we can store the ranges using 4-byte integers as long as the size of 
the metaslab divided by the sector size is less than 2^32. For 512-byte
sectors, this is a 2^41 (or 2TB) metaslab, which with the default
settings corresponds to a 256PB disk. 4k sector disks can handle 
metaslabs up to 2^46 bytes, or 2^63 byte disks. Since we do not 
anticipate disks of this size in the near future, there should be 
almost no cases where metaslabs need 64-byte integers to store their 
ranges. We do still have the capability to store 64-byte integer ranges 
to account for cases where we are storing per-vdev (or per-dnode) trees, 
which could reasonably go above the limits discussed. We also do not 
store fill information in the compact version of the node, since it 
is only used for sorted scrub.

We also optimized the metaslab loading process in various other ways
to offset some inefficiencies in the btree model. While individual
operations (find, insert, remove_from) are faster for the btree than 
they are for the avl tree, remove usually requires a find operation, 
while in the AVL tree model the element itself suffices. Some clever 
changes actually caused an overall speedup in metaslab loading; we use 
approximately 40% less cpu to load metaslabs in our tests on Illumos.

Another memory and performance optimization was achieved by changing 
what is stored in the size-sorted trees. When a disk is heavily 
fragmented, the df algorithm used by default in ZFS will almost always 
find a number of small regions in its initial cursor-based search; it 
will usually only fall back to the size-sorted tree to find larger 
regions. If we increase the size of the cursor-based search slightly, 
and don't store segments that are smaller than a tunable size floor 
in the size-sorted tree, we can further cut memory usage down to 
below 20% of what the AVL trees store. This also results in further 
reductions in CPU time spent loading metaslabs.

The 16KiB size floor was chosen because it results in substantial memory 
usage reduction while not usually resulting in situations where we can't 
find an appropriate chunk with the cursor and are forced to use an 
oversized chunk from the size-sorted tree. In addition, even if we do 
have to use an oversized chunk from the size-sorted tree, the chunk 
would be too small to use for ZIL allocations, so it isn't as big of a 
loss as it might otherwise be. And often, more small allocations will 
follow the initial one, and the cursor search will now find the 
remainder of the chunk we didn't use all of and use it for subsequent 
allocations. Practical testing has shown little or no change in 
fragmentation as a result of this change.

If the size-sorted tree becomes empty while the offset sorted one still 
has entries, it will load all the entries from the offset sorted tree 
and disregard the size floor until it is unloaded again. This operation 
occurs rarely with the default setting, only on incredibly thoroughly 
fragmented pools.

There are some other small changes to zdb to teach it to handle btrees, 
but nothing major.
                                           
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Matt Ahrens <matt@delphix.com>
Reviewed by: Sebastien Roy seb@delphix.com
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Closes #9181
2019-10-09 10:36:03 -07:00

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/*
* 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) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2016 by Delphix. All rights reserved.
*/
#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/spa_impl.h>
#include <sys/zio.h>
#include <sys/ddt.h>
#include <sys/zap.h>
#include <sys/dmu_tx.h>
#include <sys/arc.h>
#include <sys/dsl_pool.h>
#include <sys/zio_checksum.h>
#include <sys/zio_compress.h>
#include <sys/dsl_scan.h>
#include <sys/abd.h>
static kmem_cache_t *ddt_cache;
static kmem_cache_t *ddt_entry_cache;
/*
* Enable/disable prefetching of dedup-ed blocks which are going to be freed.
*/
int zfs_dedup_prefetch = 0;
static const ddt_ops_t *ddt_ops[DDT_TYPES] = {
&ddt_zap_ops,
};
static const char *ddt_class_name[DDT_CLASSES] = {
"ditto",
"duplicate",
"unique",
};
static void
ddt_object_create(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
dmu_tx_t *tx)
{
spa_t *spa = ddt->ddt_spa;
objset_t *os = ddt->ddt_os;
uint64_t *objectp = &ddt->ddt_object[type][class];
boolean_t prehash = zio_checksum_table[ddt->ddt_checksum].ci_flags &
ZCHECKSUM_FLAG_DEDUP;
char name[DDT_NAMELEN];
ddt_object_name(ddt, type, class, name);
ASSERT(*objectp == 0);
VERIFY(ddt_ops[type]->ddt_op_create(os, objectp, tx, prehash) == 0);
ASSERT(*objectp != 0);
VERIFY(zap_add(os, DMU_POOL_DIRECTORY_OBJECT, name,
sizeof (uint64_t), 1, objectp, tx) == 0);
VERIFY(zap_add(os, spa->spa_ddt_stat_object, name,
sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
&ddt->ddt_histogram[type][class], tx) == 0);
}
static void
ddt_object_destroy(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
dmu_tx_t *tx)
{
spa_t *spa = ddt->ddt_spa;
objset_t *os = ddt->ddt_os;
uint64_t *objectp = &ddt->ddt_object[type][class];
uint64_t count;
char name[DDT_NAMELEN];
ddt_object_name(ddt, type, class, name);
ASSERT(*objectp != 0);
ASSERT(ddt_histogram_empty(&ddt->ddt_histogram[type][class]));
VERIFY(ddt_object_count(ddt, type, class, &count) == 0 && count == 0);
VERIFY(zap_remove(os, DMU_POOL_DIRECTORY_OBJECT, name, tx) == 0);
VERIFY(zap_remove(os, spa->spa_ddt_stat_object, name, tx) == 0);
VERIFY(ddt_ops[type]->ddt_op_destroy(os, *objectp, tx) == 0);
bzero(&ddt->ddt_object_stats[type][class], sizeof (ddt_object_t));
*objectp = 0;
}
static int
ddt_object_load(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
{
ddt_object_t *ddo = &ddt->ddt_object_stats[type][class];
dmu_object_info_t doi;
uint64_t count;
char name[DDT_NAMELEN];
int error;
ddt_object_name(ddt, type, class, name);
error = zap_lookup(ddt->ddt_os, DMU_POOL_DIRECTORY_OBJECT, name,
sizeof (uint64_t), 1, &ddt->ddt_object[type][class]);
if (error != 0)
return (error);
error = zap_lookup(ddt->ddt_os, ddt->ddt_spa->spa_ddt_stat_object, name,
sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
&ddt->ddt_histogram[type][class]);
if (error != 0)
return (error);
/*
* Seed the cached statistics.
*/
error = ddt_object_info(ddt, type, class, &doi);
if (error)
return (error);
error = ddt_object_count(ddt, type, class, &count);
if (error)
return (error);
ddo->ddo_count = count;
ddo->ddo_dspace = doi.doi_physical_blocks_512 << 9;
ddo->ddo_mspace = doi.doi_fill_count * doi.doi_data_block_size;
return (0);
}
static void
ddt_object_sync(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
dmu_tx_t *tx)
{
ddt_object_t *ddo = &ddt->ddt_object_stats[type][class];
dmu_object_info_t doi;
uint64_t count;
char name[DDT_NAMELEN];
ddt_object_name(ddt, type, class, name);
VERIFY(zap_update(ddt->ddt_os, ddt->ddt_spa->spa_ddt_stat_object, name,
sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
&ddt->ddt_histogram[type][class], tx) == 0);
/*
* Cache DDT statistics; this is the only time they'll change.
*/
VERIFY(ddt_object_info(ddt, type, class, &doi) == 0);
VERIFY(ddt_object_count(ddt, type, class, &count) == 0);
ddo->ddo_count = count;
ddo->ddo_dspace = doi.doi_physical_blocks_512 << 9;
ddo->ddo_mspace = doi.doi_fill_count * doi.doi_data_block_size;
}
static int
ddt_object_lookup(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
ddt_entry_t *dde)
{
if (!ddt_object_exists(ddt, type, class))
return (SET_ERROR(ENOENT));
return (ddt_ops[type]->ddt_op_lookup(ddt->ddt_os,
ddt->ddt_object[type][class], dde));
}
static void
ddt_object_prefetch(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
ddt_entry_t *dde)
{
if (!ddt_object_exists(ddt, type, class))
return;
ddt_ops[type]->ddt_op_prefetch(ddt->ddt_os,
ddt->ddt_object[type][class], dde);
}
int
ddt_object_update(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
ddt_entry_t *dde, dmu_tx_t *tx)
{
ASSERT(ddt_object_exists(ddt, type, class));
return (ddt_ops[type]->ddt_op_update(ddt->ddt_os,
ddt->ddt_object[type][class], dde, tx));
}
static int
ddt_object_remove(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
ddt_entry_t *dde, dmu_tx_t *tx)
{
ASSERT(ddt_object_exists(ddt, type, class));
return (ddt_ops[type]->ddt_op_remove(ddt->ddt_os,
ddt->ddt_object[type][class], dde, tx));
}
int
ddt_object_walk(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
uint64_t *walk, ddt_entry_t *dde)
{
ASSERT(ddt_object_exists(ddt, type, class));
return (ddt_ops[type]->ddt_op_walk(ddt->ddt_os,
ddt->ddt_object[type][class], dde, walk));
}
int
ddt_object_count(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
uint64_t *count)
{
ASSERT(ddt_object_exists(ddt, type, class));
return (ddt_ops[type]->ddt_op_count(ddt->ddt_os,
ddt->ddt_object[type][class], count));
}
int
ddt_object_info(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
dmu_object_info_t *doi)
{
if (!ddt_object_exists(ddt, type, class))
return (SET_ERROR(ENOENT));
return (dmu_object_info(ddt->ddt_os, ddt->ddt_object[type][class],
doi));
}
boolean_t
ddt_object_exists(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
{
return (!!ddt->ddt_object[type][class]);
}
void
ddt_object_name(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
char *name)
{
(void) sprintf(name, DMU_POOL_DDT,
zio_checksum_table[ddt->ddt_checksum].ci_name,
ddt_ops[type]->ddt_op_name, ddt_class_name[class]);
}
void
ddt_bp_fill(const ddt_phys_t *ddp, blkptr_t *bp, uint64_t txg)
{
ASSERT(txg != 0);
for (int d = 0; d < SPA_DVAS_PER_BP; d++)
bp->blk_dva[d] = ddp->ddp_dva[d];
BP_SET_BIRTH(bp, txg, ddp->ddp_phys_birth);
}
/*
* The bp created via this function may be used for repairs and scrub, but it
* will be missing the salt / IV required to do a full decrypting read.
*/
void
ddt_bp_create(enum zio_checksum checksum,
const ddt_key_t *ddk, const ddt_phys_t *ddp, blkptr_t *bp)
{
BP_ZERO(bp);
if (ddp != NULL)
ddt_bp_fill(ddp, bp, ddp->ddp_phys_birth);
bp->blk_cksum = ddk->ddk_cksum;
BP_SET_LSIZE(bp, DDK_GET_LSIZE(ddk));
BP_SET_PSIZE(bp, DDK_GET_PSIZE(ddk));
BP_SET_COMPRESS(bp, DDK_GET_COMPRESS(ddk));
BP_SET_CRYPT(bp, DDK_GET_CRYPT(ddk));
BP_SET_FILL(bp, 1);
BP_SET_CHECKSUM(bp, checksum);
BP_SET_TYPE(bp, DMU_OT_DEDUP);
BP_SET_LEVEL(bp, 0);
BP_SET_DEDUP(bp, 1);
BP_SET_BYTEORDER(bp, ZFS_HOST_BYTEORDER);
}
void
ddt_key_fill(ddt_key_t *ddk, const blkptr_t *bp)
{
ddk->ddk_cksum = bp->blk_cksum;
ddk->ddk_prop = 0;
ASSERT(BP_IS_ENCRYPTED(bp) || !BP_USES_CRYPT(bp));
DDK_SET_LSIZE(ddk, BP_GET_LSIZE(bp));
DDK_SET_PSIZE(ddk, BP_GET_PSIZE(bp));
DDK_SET_COMPRESS(ddk, BP_GET_COMPRESS(bp));
DDK_SET_CRYPT(ddk, BP_USES_CRYPT(bp));
}
void
ddt_phys_fill(ddt_phys_t *ddp, const blkptr_t *bp)
{
ASSERT(ddp->ddp_phys_birth == 0);
for (int d = 0; d < SPA_DVAS_PER_BP; d++)
ddp->ddp_dva[d] = bp->blk_dva[d];
ddp->ddp_phys_birth = BP_PHYSICAL_BIRTH(bp);
}
void
ddt_phys_clear(ddt_phys_t *ddp)
{
bzero(ddp, sizeof (*ddp));
}
void
ddt_phys_addref(ddt_phys_t *ddp)
{
ddp->ddp_refcnt++;
}
void
ddt_phys_decref(ddt_phys_t *ddp)
{
if (ddp) {
ASSERT(ddp->ddp_refcnt > 0);
ddp->ddp_refcnt--;
}
}
void
ddt_phys_free(ddt_t *ddt, ddt_key_t *ddk, ddt_phys_t *ddp, uint64_t txg)
{
blkptr_t blk;
ddt_bp_create(ddt->ddt_checksum, ddk, ddp, &blk);
/*
* We clear the dedup bit so that zio_free() will actually free the
* space, rather than just decrementing the refcount in the DDT.
*/
BP_SET_DEDUP(&blk, 0);
ddt_phys_clear(ddp);
zio_free(ddt->ddt_spa, txg, &blk);
}
ddt_phys_t *
ddt_phys_select(const ddt_entry_t *dde, const blkptr_t *bp)
{
ddt_phys_t *ddp = (ddt_phys_t *)dde->dde_phys;
for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
if (DVA_EQUAL(BP_IDENTITY(bp), &ddp->ddp_dva[0]) &&
BP_PHYSICAL_BIRTH(bp) == ddp->ddp_phys_birth)
return (ddp);
}
return (NULL);
}
uint64_t
ddt_phys_total_refcnt(const ddt_entry_t *dde)
{
uint64_t refcnt = 0;
for (int p = DDT_PHYS_SINGLE; p <= DDT_PHYS_TRIPLE; p++)
refcnt += dde->dde_phys[p].ddp_refcnt;
return (refcnt);
}
static void
ddt_stat_generate(ddt_t *ddt, ddt_entry_t *dde, ddt_stat_t *dds)
{
spa_t *spa = ddt->ddt_spa;
ddt_phys_t *ddp = dde->dde_phys;
ddt_key_t *ddk = &dde->dde_key;
uint64_t lsize = DDK_GET_LSIZE(ddk);
uint64_t psize = DDK_GET_PSIZE(ddk);
bzero(dds, sizeof (*dds));
for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
uint64_t dsize = 0;
uint64_t refcnt = ddp->ddp_refcnt;
if (ddp->ddp_phys_birth == 0)
continue;
for (int d = 0; d < DDE_GET_NDVAS(dde); d++)
dsize += dva_get_dsize_sync(spa, &ddp->ddp_dva[d]);
dds->dds_blocks += 1;
dds->dds_lsize += lsize;
dds->dds_psize += psize;
dds->dds_dsize += dsize;
dds->dds_ref_blocks += refcnt;
dds->dds_ref_lsize += lsize * refcnt;
dds->dds_ref_psize += psize * refcnt;
dds->dds_ref_dsize += dsize * refcnt;
}
}
void
ddt_stat_add(ddt_stat_t *dst, const ddt_stat_t *src, uint64_t neg)
{
const uint64_t *s = (const uint64_t *)src;
uint64_t *d = (uint64_t *)dst;
uint64_t *d_end = (uint64_t *)(dst + 1);
ASSERT(neg == 0 || neg == -1ULL); /* add or subtract */
while (d < d_end)
*d++ += (*s++ ^ neg) - neg;
}
static void
ddt_stat_update(ddt_t *ddt, ddt_entry_t *dde, uint64_t neg)
{
ddt_stat_t dds;
ddt_histogram_t *ddh;
int bucket;
ddt_stat_generate(ddt, dde, &dds);
bucket = highbit64(dds.dds_ref_blocks) - 1;
ASSERT(bucket >= 0);
ddh = &ddt->ddt_histogram[dde->dde_type][dde->dde_class];
ddt_stat_add(&ddh->ddh_stat[bucket], &dds, neg);
}
void
ddt_histogram_add(ddt_histogram_t *dst, const ddt_histogram_t *src)
{
for (int h = 0; h < 64; h++)
ddt_stat_add(&dst->ddh_stat[h], &src->ddh_stat[h], 0);
}
void
ddt_histogram_stat(ddt_stat_t *dds, const ddt_histogram_t *ddh)
{
bzero(dds, sizeof (*dds));
for (int h = 0; h < 64; h++)
ddt_stat_add(dds, &ddh->ddh_stat[h], 0);
}
boolean_t
ddt_histogram_empty(const ddt_histogram_t *ddh)
{
const uint64_t *s = (const uint64_t *)ddh;
const uint64_t *s_end = (const uint64_t *)(ddh + 1);
while (s < s_end)
if (*s++ != 0)
return (B_FALSE);
return (B_TRUE);
}
void
ddt_get_dedup_object_stats(spa_t *spa, ddt_object_t *ddo_total)
{
/* Sum the statistics we cached in ddt_object_sync(). */
for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
ddt_t *ddt = spa->spa_ddt[c];
for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
for (enum ddt_class class = 0; class < DDT_CLASSES;
class++) {
ddt_object_t *ddo =
&ddt->ddt_object_stats[type][class];
ddo_total->ddo_count += ddo->ddo_count;
ddo_total->ddo_dspace += ddo->ddo_dspace;
ddo_total->ddo_mspace += ddo->ddo_mspace;
}
}
}
/* ... and compute the averages. */
if (ddo_total->ddo_count != 0) {
ddo_total->ddo_dspace /= ddo_total->ddo_count;
ddo_total->ddo_mspace /= ddo_total->ddo_count;
}
}
void
ddt_get_dedup_histogram(spa_t *spa, ddt_histogram_t *ddh)
{
for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
ddt_t *ddt = spa->spa_ddt[c];
for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
for (enum ddt_class class = 0; class < DDT_CLASSES;
class++) {
ddt_histogram_add(ddh,
&ddt->ddt_histogram_cache[type][class]);
}
}
}
}
void
ddt_get_dedup_stats(spa_t *spa, ddt_stat_t *dds_total)
{
ddt_histogram_t *ddh_total;
ddh_total = kmem_zalloc(sizeof (ddt_histogram_t), KM_SLEEP);
ddt_get_dedup_histogram(spa, ddh_total);
ddt_histogram_stat(dds_total, ddh_total);
kmem_free(ddh_total, sizeof (ddt_histogram_t));
}
uint64_t
ddt_get_dedup_dspace(spa_t *spa)
{
ddt_stat_t dds_total;
if (spa->spa_dedup_dspace != ~0ULL)
return (spa->spa_dedup_dspace);
bzero(&dds_total, sizeof (ddt_stat_t));
/* Calculate and cache the stats */
ddt_get_dedup_stats(spa, &dds_total);
spa->spa_dedup_dspace = dds_total.dds_ref_dsize - dds_total.dds_dsize;
return (spa->spa_dedup_dspace);
}
uint64_t
ddt_get_pool_dedup_ratio(spa_t *spa)
{
ddt_stat_t dds_total = { 0 };
ddt_get_dedup_stats(spa, &dds_total);
if (dds_total.dds_dsize == 0)
return (100);
return (dds_total.dds_ref_dsize * 100 / dds_total.dds_dsize);
}
size_t
ddt_compress(void *src, uchar_t *dst, size_t s_len, size_t d_len)
{
uchar_t *version = dst++;
int cpfunc = ZIO_COMPRESS_ZLE;
zio_compress_info_t *ci = &zio_compress_table[cpfunc];
size_t c_len;
ASSERT(d_len >= s_len + 1); /* no compression plus version byte */
c_len = ci->ci_compress(src, dst, s_len, d_len - 1, ci->ci_level);
if (c_len == s_len) {
cpfunc = ZIO_COMPRESS_OFF;
bcopy(src, dst, s_len);
}
*version = cpfunc;
/* CONSTCOND */
if (ZFS_HOST_BYTEORDER)
*version |= DDT_COMPRESS_BYTEORDER_MASK;
return (c_len + 1);
}
void
ddt_decompress(uchar_t *src, void *dst, size_t s_len, size_t d_len)
{
uchar_t version = *src++;
int cpfunc = version & DDT_COMPRESS_FUNCTION_MASK;
zio_compress_info_t *ci = &zio_compress_table[cpfunc];
if (ci->ci_decompress != NULL)
(void) ci->ci_decompress(src, dst, s_len, d_len, ci->ci_level);
else
bcopy(src, dst, d_len);
if (((version & DDT_COMPRESS_BYTEORDER_MASK) != 0) !=
(ZFS_HOST_BYTEORDER != 0))
byteswap_uint64_array(dst, d_len);
}
ddt_t *
ddt_select_by_checksum(spa_t *spa, enum zio_checksum c)
{
return (spa->spa_ddt[c]);
}
ddt_t *
ddt_select(spa_t *spa, const blkptr_t *bp)
{
return (spa->spa_ddt[BP_GET_CHECKSUM(bp)]);
}
void
ddt_enter(ddt_t *ddt)
{
mutex_enter(&ddt->ddt_lock);
}
void
ddt_exit(ddt_t *ddt)
{
mutex_exit(&ddt->ddt_lock);
}
void
ddt_init(void)
{
ddt_cache = kmem_cache_create("ddt_cache",
sizeof (ddt_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
ddt_entry_cache = kmem_cache_create("ddt_entry_cache",
sizeof (ddt_entry_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
}
void
ddt_fini(void)
{
kmem_cache_destroy(ddt_entry_cache);
kmem_cache_destroy(ddt_cache);
}
static ddt_entry_t *
ddt_alloc(const ddt_key_t *ddk)
{
ddt_entry_t *dde;
dde = kmem_cache_alloc(ddt_entry_cache, KM_SLEEP);
bzero(dde, sizeof (ddt_entry_t));
cv_init(&dde->dde_cv, NULL, CV_DEFAULT, NULL);
dde->dde_key = *ddk;
return (dde);
}
static void
ddt_free(ddt_entry_t *dde)
{
ASSERT(!dde->dde_loading);
for (int p = 0; p < DDT_PHYS_TYPES; p++)
ASSERT(dde->dde_lead_zio[p] == NULL);
if (dde->dde_repair_abd != NULL)
abd_free(dde->dde_repair_abd);
cv_destroy(&dde->dde_cv);
kmem_cache_free(ddt_entry_cache, dde);
}
void
ddt_remove(ddt_t *ddt, ddt_entry_t *dde)
{
ASSERT(MUTEX_HELD(&ddt->ddt_lock));
avl_remove(&ddt->ddt_tree, dde);
ddt_free(dde);
}
ddt_entry_t *
ddt_lookup(ddt_t *ddt, const blkptr_t *bp, boolean_t add)
{
ddt_entry_t *dde, dde_search;
enum ddt_type type;
enum ddt_class class;
avl_index_t where;
int error;
ASSERT(MUTEX_HELD(&ddt->ddt_lock));
ddt_key_fill(&dde_search.dde_key, bp);
dde = avl_find(&ddt->ddt_tree, &dde_search, &where);
if (dde == NULL) {
if (!add)
return (NULL);
dde = ddt_alloc(&dde_search.dde_key);
avl_insert(&ddt->ddt_tree, dde, where);
}
while (dde->dde_loading)
cv_wait(&dde->dde_cv, &ddt->ddt_lock);
if (dde->dde_loaded)
return (dde);
dde->dde_loading = B_TRUE;
ddt_exit(ddt);
error = ENOENT;
for (type = 0; type < DDT_TYPES; type++) {
for (class = 0; class < DDT_CLASSES; class++) {
error = ddt_object_lookup(ddt, type, class, dde);
if (error != ENOENT) {
ASSERT0(error);
break;
}
}
if (error != ENOENT)
break;
}
ddt_enter(ddt);
ASSERT(dde->dde_loaded == B_FALSE);
ASSERT(dde->dde_loading == B_TRUE);
dde->dde_type = type; /* will be DDT_TYPES if no entry found */
dde->dde_class = class; /* will be DDT_CLASSES if no entry found */
dde->dde_loaded = B_TRUE;
dde->dde_loading = B_FALSE;
if (error == 0)
ddt_stat_update(ddt, dde, -1ULL);
cv_broadcast(&dde->dde_cv);
return (dde);
}
void
ddt_prefetch(spa_t *spa, const blkptr_t *bp)
{
ddt_t *ddt;
ddt_entry_t dde;
if (!zfs_dedup_prefetch || bp == NULL || !BP_GET_DEDUP(bp))
return;
/*
* We only remove the DDT once all tables are empty and only
* prefetch dedup blocks when there are entries in the DDT.
* Thus no locking is required as the DDT can't disappear on us.
*/
ddt = ddt_select(spa, bp);
ddt_key_fill(&dde.dde_key, bp);
for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
ddt_object_prefetch(ddt, type, class, &dde);
}
}
}
/*
* Opaque struct used for ddt_key comparison
*/
#define DDT_KEY_CMP_LEN (sizeof (ddt_key_t) / sizeof (uint16_t))
typedef struct ddt_key_cmp {
uint16_t u16[DDT_KEY_CMP_LEN];
} ddt_key_cmp_t;
int
ddt_entry_compare(const void *x1, const void *x2)
{
const ddt_entry_t *dde1 = x1;
const ddt_entry_t *dde2 = x2;
const ddt_key_cmp_t *k1 = (const ddt_key_cmp_t *)&dde1->dde_key;
const ddt_key_cmp_t *k2 = (const ddt_key_cmp_t *)&dde2->dde_key;
int32_t cmp = 0;
for (int i = 0; i < DDT_KEY_CMP_LEN; i++) {
cmp = (int32_t)k1->u16[i] - (int32_t)k2->u16[i];
if (likely(cmp))
break;
}
return (TREE_ISIGN(cmp));
}
static ddt_t *
ddt_table_alloc(spa_t *spa, enum zio_checksum c)
{
ddt_t *ddt;
ddt = kmem_cache_alloc(ddt_cache, KM_SLEEP);
bzero(ddt, sizeof (ddt_t));
mutex_init(&ddt->ddt_lock, NULL, MUTEX_DEFAULT, NULL);
avl_create(&ddt->ddt_tree, ddt_entry_compare,
sizeof (ddt_entry_t), offsetof(ddt_entry_t, dde_node));
avl_create(&ddt->ddt_repair_tree, ddt_entry_compare,
sizeof (ddt_entry_t), offsetof(ddt_entry_t, dde_node));
ddt->ddt_checksum = c;
ddt->ddt_spa = spa;
ddt->ddt_os = spa->spa_meta_objset;
return (ddt);
}
static void
ddt_table_free(ddt_t *ddt)
{
ASSERT(avl_numnodes(&ddt->ddt_tree) == 0);
ASSERT(avl_numnodes(&ddt->ddt_repair_tree) == 0);
avl_destroy(&ddt->ddt_tree);
avl_destroy(&ddt->ddt_repair_tree);
mutex_destroy(&ddt->ddt_lock);
kmem_cache_free(ddt_cache, ddt);
}
void
ddt_create(spa_t *spa)
{
spa->spa_dedup_checksum = ZIO_DEDUPCHECKSUM;
for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++)
spa->spa_ddt[c] = ddt_table_alloc(spa, c);
}
int
ddt_load(spa_t *spa)
{
int error;
ddt_create(spa);
error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_DDT_STATS, sizeof (uint64_t), 1,
&spa->spa_ddt_stat_object);
if (error)
return (error == ENOENT ? 0 : error);
for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
ddt_t *ddt = spa->spa_ddt[c];
for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
for (enum ddt_class class = 0; class < DDT_CLASSES;
class++) {
error = ddt_object_load(ddt, type, class);
if (error != 0 && error != ENOENT)
return (error);
}
}
/*
* Seed the cached histograms.
*/
bcopy(ddt->ddt_histogram, &ddt->ddt_histogram_cache,
sizeof (ddt->ddt_histogram));
spa->spa_dedup_dspace = ~0ULL;
}
return (0);
}
void
ddt_unload(spa_t *spa)
{
for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
if (spa->spa_ddt[c]) {
ddt_table_free(spa->spa_ddt[c]);
spa->spa_ddt[c] = NULL;
}
}
}
boolean_t
ddt_class_contains(spa_t *spa, enum ddt_class max_class, const blkptr_t *bp)
{
ddt_t *ddt;
ddt_entry_t *dde;
if (!BP_GET_DEDUP(bp))
return (B_FALSE);
if (max_class == DDT_CLASS_UNIQUE)
return (B_TRUE);
ddt = spa->spa_ddt[BP_GET_CHECKSUM(bp)];
dde = kmem_cache_alloc(ddt_entry_cache, KM_SLEEP);
ddt_key_fill(&(dde->dde_key), bp);
for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
for (enum ddt_class class = 0; class <= max_class; class++) {
if (ddt_object_lookup(ddt, type, class, dde) == 0) {
kmem_cache_free(ddt_entry_cache, dde);
return (B_TRUE);
}
}
}
kmem_cache_free(ddt_entry_cache, dde);
return (B_FALSE);
}
ddt_entry_t *
ddt_repair_start(ddt_t *ddt, const blkptr_t *bp)
{
ddt_key_t ddk;
ddt_entry_t *dde;
ddt_key_fill(&ddk, bp);
dde = ddt_alloc(&ddk);
for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
/*
* We can only do repair if there are multiple copies
* of the block. For anything in the UNIQUE class,
* there's definitely only one copy, so don't even try.
*/
if (class != DDT_CLASS_UNIQUE &&
ddt_object_lookup(ddt, type, class, dde) == 0)
return (dde);
}
}
bzero(dde->dde_phys, sizeof (dde->dde_phys));
return (dde);
}
void
ddt_repair_done(ddt_t *ddt, ddt_entry_t *dde)
{
avl_index_t where;
ddt_enter(ddt);
if (dde->dde_repair_abd != NULL && spa_writeable(ddt->ddt_spa) &&
avl_find(&ddt->ddt_repair_tree, dde, &where) == NULL)
avl_insert(&ddt->ddt_repair_tree, dde, where);
else
ddt_free(dde);
ddt_exit(ddt);
}
static void
ddt_repair_entry_done(zio_t *zio)
{
ddt_entry_t *rdde = zio->io_private;
ddt_free(rdde);
}
static void
ddt_repair_entry(ddt_t *ddt, ddt_entry_t *dde, ddt_entry_t *rdde, zio_t *rio)
{
ddt_phys_t *ddp = dde->dde_phys;
ddt_phys_t *rddp = rdde->dde_phys;
ddt_key_t *ddk = &dde->dde_key;
ddt_key_t *rddk = &rdde->dde_key;
zio_t *zio;
blkptr_t blk;
zio = zio_null(rio, rio->io_spa, NULL,
ddt_repair_entry_done, rdde, rio->io_flags);
for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++, rddp++) {
if (ddp->ddp_phys_birth == 0 ||
ddp->ddp_phys_birth != rddp->ddp_phys_birth ||
bcmp(ddp->ddp_dva, rddp->ddp_dva, sizeof (ddp->ddp_dva)))
continue;
ddt_bp_create(ddt->ddt_checksum, ddk, ddp, &blk);
zio_nowait(zio_rewrite(zio, zio->io_spa, 0, &blk,
rdde->dde_repair_abd, DDK_GET_PSIZE(rddk), NULL, NULL,
ZIO_PRIORITY_SYNC_WRITE, ZIO_DDT_CHILD_FLAGS(zio), NULL));
}
zio_nowait(zio);
}
static void
ddt_repair_table(ddt_t *ddt, zio_t *rio)
{
spa_t *spa = ddt->ddt_spa;
ddt_entry_t *dde, *rdde_next, *rdde;
avl_tree_t *t = &ddt->ddt_repair_tree;
blkptr_t blk;
if (spa_sync_pass(spa) > 1)
return;
ddt_enter(ddt);
for (rdde = avl_first(t); rdde != NULL; rdde = rdde_next) {
rdde_next = AVL_NEXT(t, rdde);
avl_remove(&ddt->ddt_repair_tree, rdde);
ddt_exit(ddt);
ddt_bp_create(ddt->ddt_checksum, &rdde->dde_key, NULL, &blk);
dde = ddt_repair_start(ddt, &blk);
ddt_repair_entry(ddt, dde, rdde, rio);
ddt_repair_done(ddt, dde);
ddt_enter(ddt);
}
ddt_exit(ddt);
}
static void
ddt_sync_entry(ddt_t *ddt, ddt_entry_t *dde, dmu_tx_t *tx, uint64_t txg)
{
dsl_pool_t *dp = ddt->ddt_spa->spa_dsl_pool;
ddt_phys_t *ddp = dde->dde_phys;
ddt_key_t *ddk = &dde->dde_key;
enum ddt_type otype = dde->dde_type;
enum ddt_type ntype = DDT_TYPE_CURRENT;
enum ddt_class oclass = dde->dde_class;
enum ddt_class nclass;
uint64_t total_refcnt = 0;
ASSERT(dde->dde_loaded);
ASSERT(!dde->dde_loading);
for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
ASSERT(dde->dde_lead_zio[p] == NULL);
if (ddp->ddp_phys_birth == 0) {
ASSERT(ddp->ddp_refcnt == 0);
continue;
}
if (p == DDT_PHYS_DITTO) {
/*
* Note, we no longer create DDT-DITTO blocks, but we
* don't want to leak any written by older software.
*/
ddt_phys_free(ddt, ddk, ddp, txg);
continue;
}
if (ddp->ddp_refcnt == 0)
ddt_phys_free(ddt, ddk, ddp, txg);
total_refcnt += ddp->ddp_refcnt;
}
/* We do not create new DDT-DITTO blocks. */
ASSERT0(dde->dde_phys[DDT_PHYS_DITTO].ddp_phys_birth);
if (total_refcnt > 1)
nclass = DDT_CLASS_DUPLICATE;
else
nclass = DDT_CLASS_UNIQUE;
if (otype != DDT_TYPES &&
(otype != ntype || oclass != nclass || total_refcnt == 0)) {
VERIFY(ddt_object_remove(ddt, otype, oclass, dde, tx) == 0);
ASSERT(ddt_object_lookup(ddt, otype, oclass, dde) == ENOENT);
}
if (total_refcnt != 0) {
dde->dde_type = ntype;
dde->dde_class = nclass;
ddt_stat_update(ddt, dde, 0);
if (!ddt_object_exists(ddt, ntype, nclass))
ddt_object_create(ddt, ntype, nclass, tx);
VERIFY(ddt_object_update(ddt, ntype, nclass, dde, tx) == 0);
/*
* If the class changes, the order that we scan this bp
* changes. If it decreases, we could miss it, so
* scan it right now. (This covers both class changing
* while we are doing ddt_walk(), and when we are
* traversing.)
*/
if (nclass < oclass) {
dsl_scan_ddt_entry(dp->dp_scan,
ddt->ddt_checksum, dde, tx);
}
}
}
static void
ddt_sync_table(ddt_t *ddt, dmu_tx_t *tx, uint64_t txg)
{
spa_t *spa = ddt->ddt_spa;
ddt_entry_t *dde;
void *cookie = NULL;
if (avl_numnodes(&ddt->ddt_tree) == 0)
return;
ASSERT(spa->spa_uberblock.ub_version >= SPA_VERSION_DEDUP);
if (spa->spa_ddt_stat_object == 0) {
spa->spa_ddt_stat_object = zap_create_link(ddt->ddt_os,
DMU_OT_DDT_STATS, DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_DDT_STATS, tx);
}
while ((dde = avl_destroy_nodes(&ddt->ddt_tree, &cookie)) != NULL) {
ddt_sync_entry(ddt, dde, tx, txg);
ddt_free(dde);
}
for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
uint64_t add, count = 0;
for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
if (ddt_object_exists(ddt, type, class)) {
ddt_object_sync(ddt, type, class, tx);
VERIFY(ddt_object_count(ddt, type, class,
&add) == 0);
count += add;
}
}
for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
if (count == 0 && ddt_object_exists(ddt, type, class))
ddt_object_destroy(ddt, type, class, tx);
}
}
bcopy(ddt->ddt_histogram, &ddt->ddt_histogram_cache,
sizeof (ddt->ddt_histogram));
spa->spa_dedup_dspace = ~0ULL;
}
void
ddt_sync(spa_t *spa, uint64_t txg)
{
dsl_scan_t *scn = spa->spa_dsl_pool->dp_scan;
dmu_tx_t *tx;
zio_t *rio;
ASSERT(spa_syncing_txg(spa) == txg);
tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
rio = zio_root(spa, NULL, NULL,
ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SELF_HEAL);
/*
* This function may cause an immediate scan of ddt blocks (see
* the comment above dsl_scan_ddt() for details). We set the
* scan's root zio here so that we can wait for any scan IOs in
* addition to the regular ddt IOs.
*/
ASSERT3P(scn->scn_zio_root, ==, NULL);
scn->scn_zio_root = rio;
for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
ddt_t *ddt = spa->spa_ddt[c];
if (ddt == NULL)
continue;
ddt_sync_table(ddt, tx, txg);
ddt_repair_table(ddt, rio);
}
(void) zio_wait(rio);
scn->scn_zio_root = NULL;
dmu_tx_commit(tx);
}
int
ddt_walk(spa_t *spa, ddt_bookmark_t *ddb, ddt_entry_t *dde)
{
do {
do {
do {
ddt_t *ddt = spa->spa_ddt[ddb->ddb_checksum];
int error = ENOENT;
if (ddt_object_exists(ddt, ddb->ddb_type,
ddb->ddb_class)) {
error = ddt_object_walk(ddt,
ddb->ddb_type, ddb->ddb_class,
&ddb->ddb_cursor, dde);
}
dde->dde_type = ddb->ddb_type;
dde->dde_class = ddb->ddb_class;
if (error == 0)
return (0);
if (error != ENOENT)
return (error);
ddb->ddb_cursor = 0;
} while (++ddb->ddb_checksum < ZIO_CHECKSUM_FUNCTIONS);
ddb->ddb_checksum = 0;
} while (++ddb->ddb_type < DDT_TYPES);
ddb->ddb_type = 0;
} while (++ddb->ddb_class < DDT_CLASSES);
return (SET_ERROR(ENOENT));
}
/* BEGIN CSTYLED */
ZFS_MODULE_PARAM(zfs, zfs_, dedup_prefetch, INT, ZMOD_RW,
"Enable prefetching dedup-ed blks");
/* END CSTYLED */
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