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freebsd-nq/module/zfs/range_tree.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 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
* Copyright (c) 2013, 2019 by Delphix. All rights reserved.
*/
#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/dmu.h>
#include <sys/dnode.h>
#include <sys/zio.h>
#include <sys/range_tree.h>
/*
* Range trees are tree-based data structures that can be used to
* track free space or generally any space allocation information.
* A range tree keeps track of individual segments and automatically
* provides facilities such as adjacent extent merging and extent
* splitting in response to range add/remove requests.
*
* A range tree starts out completely empty, with no segments in it.
* Adding an allocation via range_tree_add to the range tree can either:
* 1) create a new extent
* 2) extend an adjacent extent
* 3) merge two adjacent extents
* Conversely, removing an allocation via range_tree_remove can:
* 1) completely remove an extent
* 2) shorten an extent (if the allocation was near one of its ends)
* 3) split an extent into two extents, in effect punching a hole
*
* A range tree is also capable of 'bridging' gaps when adding
* allocations. This is useful for cases when close proximity of
* allocations is an important detail that needs to be represented
* in the range tree. See range_tree_set_gap(). The default behavior
* is not to bridge gaps (i.e. the maximum allowed gap size is 0).
*
* In order to traverse a range tree, use either the range_tree_walk()
* or range_tree_vacate() functions.
*
* To obtain more accurate information on individual segment
* operations that the range tree performs "under the hood", you can
* specify a set of callbacks by passing a range_tree_ops_t structure
* to the range_tree_create function. Any callbacks that are non-NULL
* are then called at the appropriate times.
*
* The range tree code also supports a special variant of range trees
* that can bridge small gaps between segments. This kind of tree is used
* by the dsl scanning code to group I/Os into mostly sequential chunks to
* optimize disk performance. The code here attempts to do this with as
* little memory and computational overhead as possible. One limitation of
* this implementation is that segments of range trees with gaps can only
* support removing complete segments.
*/
static inline void
rs_copy(range_seg_t *src, range_seg_t *dest, range_tree_t *rt)
{
ASSERT3U(rt->rt_type, <=, RANGE_SEG_NUM_TYPES);
size_t size = 0;
switch (rt->rt_type) {
case RANGE_SEG32:
size = sizeof (range_seg32_t);
break;
case RANGE_SEG64:
size = sizeof (range_seg64_t);
break;
case RANGE_SEG_GAP:
size = sizeof (range_seg_gap_t);
break;
default:
VERIFY(0);
}
bcopy(src, dest, size);
}
void
range_tree_stat_verify(range_tree_t *rt)
{
range_seg_t *rs;
zfs_btree_index_t where;
uint64_t hist[RANGE_TREE_HISTOGRAM_SIZE] = { 0 };
int i;
for (rs = zfs_btree_first(&rt->rt_root, &where); rs != NULL;
rs = zfs_btree_next(&rt->rt_root, &where, &where)) {
uint64_t size = rs_get_end(rs, rt) - rs_get_start(rs, rt);
int idx = highbit64(size) - 1;
hist[idx]++;
ASSERT3U(hist[idx], !=, 0);
}
for (i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++) {
if (hist[i] != rt->rt_histogram[i]) {
zfs_dbgmsg("i=%d, hist=%px, hist=%llu, rt_hist=%llu",
i, hist, hist[i], rt->rt_histogram[i]);
}
VERIFY3U(hist[i], ==, rt->rt_histogram[i]);
}
}
static void
range_tree_stat_incr(range_tree_t *rt, range_seg_t *rs)
{
uint64_t size = rs_get_end(rs, rt) - rs_get_start(rs, rt);
int idx = highbit64(size) - 1;
ASSERT(size != 0);
ASSERT3U(idx, <,
sizeof (rt->rt_histogram) / sizeof (*rt->rt_histogram));
rt->rt_histogram[idx]++;
ASSERT3U(rt->rt_histogram[idx], !=, 0);
}
static void
range_tree_stat_decr(range_tree_t *rt, range_seg_t *rs)
{
uint64_t size = rs_get_end(rs, rt) - rs_get_start(rs, rt);
int idx = highbit64(size) - 1;
ASSERT(size != 0);
ASSERT3U(idx, <,
sizeof (rt->rt_histogram) / sizeof (*rt->rt_histogram));
ASSERT3U(rt->rt_histogram[idx], !=, 0);
rt->rt_histogram[idx]--;
}
static int
range_tree_seg32_compare(const void *x1, const void *x2)
{
const range_seg32_t *r1 = x1;
const range_seg32_t *r2 = x2;
ASSERT3U(r1->rs_start, <=, r1->rs_end);
ASSERT3U(r2->rs_start, <=, r2->rs_end);
return ((r1->rs_start >= r2->rs_end) - (r1->rs_end <= r2->rs_start));
}
static int
range_tree_seg64_compare(const void *x1, const void *x2)
{
const range_seg64_t *r1 = x1;
const range_seg64_t *r2 = x2;
ASSERT3U(r1->rs_start, <=, r1->rs_end);
ASSERT3U(r2->rs_start, <=, r2->rs_end);
return ((r1->rs_start >= r2->rs_end) - (r1->rs_end <= r2->rs_start));
}
static int
range_tree_seg_gap_compare(const void *x1, const void *x2)
{
const range_seg_gap_t *r1 = x1;
const range_seg_gap_t *r2 = x2;
ASSERT3U(r1->rs_start, <=, r1->rs_end);
ASSERT3U(r2->rs_start, <=, r2->rs_end);
return ((r1->rs_start >= r2->rs_end) - (r1->rs_end <= r2->rs_start));
}
range_tree_t *
range_tree_create_impl(range_tree_ops_t *ops, range_seg_type_t type, void *arg,
uint64_t start, uint64_t shift,
int (*zfs_btree_compare) (const void *, const void *),
uint64_t gap)
{
range_tree_t *rt = kmem_zalloc(sizeof (range_tree_t), KM_SLEEP);
ASSERT3U(shift, <, 64);
ASSERT3U(type, <=, RANGE_SEG_NUM_TYPES);
size_t size;
int (*compare) (const void *, const void *);
switch (type) {
case RANGE_SEG32:
size = sizeof (range_seg32_t);
compare = range_tree_seg32_compare;
break;
case RANGE_SEG64:
size = sizeof (range_seg64_t);
compare = range_tree_seg64_compare;
break;
case RANGE_SEG_GAP:
size = sizeof (range_seg_gap_t);
compare = range_tree_seg_gap_compare;
break;
default:
panic("Invalid range seg type %d", type);
}
zfs_btree_create(&rt->rt_root, compare, size);
rt->rt_ops = ops;
rt->rt_gap = gap;
rt->rt_arg = arg;
rt->rt_type = type;
rt->rt_start = start;
rt->rt_shift = shift;
rt->rt_btree_compare = zfs_btree_compare;
if (rt->rt_ops != NULL && rt->rt_ops->rtop_create != NULL)
rt->rt_ops->rtop_create(rt, rt->rt_arg);
return (rt);
}
range_tree_t *
range_tree_create(range_tree_ops_t *ops, range_seg_type_t type,
void *arg, uint64_t start, uint64_t shift)
{
return (range_tree_create_impl(ops, type, arg, start, shift, NULL, 0));
}
void
range_tree_destroy(range_tree_t *rt)
{
VERIFY0(rt->rt_space);
if (rt->rt_ops != NULL && rt->rt_ops->rtop_destroy != NULL)
rt->rt_ops->rtop_destroy(rt, rt->rt_arg);
zfs_btree_destroy(&rt->rt_root);
kmem_free(rt, sizeof (*rt));
}
void
range_tree_adjust_fill(range_tree_t *rt, range_seg_t *rs, int64_t delta)
{
ASSERT3U(rs_get_fill(rs, rt) + delta, !=, 0);
ASSERT3U(rs_get_fill(rs, rt) + delta, <=, rs_get_end(rs, rt) -
rs_get_start(rs, rt));
if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
rt->rt_ops->rtop_remove(rt, rs, rt->rt_arg);
rs_set_fill(rs, rt, rs_get_fill(rs, rt) + delta);
if (rt->rt_ops != NULL && rt->rt_ops->rtop_add != NULL)
rt->rt_ops->rtop_add(rt, rs, rt->rt_arg);
}
static void
range_tree_add_impl(void *arg, uint64_t start, uint64_t size, uint64_t fill)
{
range_tree_t *rt = arg;
zfs_btree_index_t where;
range_seg_t *rs_before, *rs_after, *rs;
range_seg_max_t tmp, rsearch;
uint64_t end = start + size, gap = rt->rt_gap;
uint64_t bridge_size = 0;
boolean_t merge_before, merge_after;
ASSERT3U(size, !=, 0);
ASSERT3U(fill, <=, size);
ASSERT3U(start + size, >, start);
rs_set_start(&rsearch, rt, start);
rs_set_end(&rsearch, rt, end);
rs = zfs_btree_find(&rt->rt_root, &rsearch, &where);
/*
* If this is a gap-supporting range tree, it is possible that we
* are inserting into an existing segment. In this case simply
* bump the fill count and call the remove / add callbacks. If the
* new range will extend an existing segment, we remove the
* existing one, apply the new extent to it and re-insert it using
* the normal code paths.
*/
if (rs != NULL) {
ASSERT3U(rt->rt_gap, !=, 0);
uint64_t rstart = rs_get_start(rs, rt);
uint64_t rend = rs_get_end(rs, rt);
ASSERT3U(gap, !=, 0);
if (rstart <= start && rend >= end) {
range_tree_adjust_fill(rt, rs, fill);
return;
}
zfs_btree_remove(&rt->rt_root, rs);
if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
rt->rt_ops->rtop_remove(rt, rs, rt->rt_arg);
range_tree_stat_decr(rt, rs);
rt->rt_space -= rend - rstart;
fill += rs_get_fill(rs, rt);
start = MIN(start, rstart);
end = MAX(end, rend);
size = end - start;
range_tree_add_impl(rt, start, size, fill);
return;
}
ASSERT3P(rs, ==, NULL);
/*
* Determine whether or not we will have to merge with our neighbors.
* If gap != 0, we might need to merge with our neighbors even if we
* aren't directly touching.
*/
zfs_btree_index_t where_before, where_after;
rs_before = zfs_btree_prev(&rt->rt_root, &where, &where_before);
rs_after = zfs_btree_next(&rt->rt_root, &where, &where_after);
merge_before = (rs_before != NULL && rs_get_end(rs_before, rt) >=
start - gap);
merge_after = (rs_after != NULL && rs_get_start(rs_after, rt) <= end +
gap);
if (merge_before && gap != 0)
bridge_size += start - rs_get_end(rs_before, rt);
if (merge_after && gap != 0)
bridge_size += rs_get_start(rs_after, rt) - end;
if (merge_before && merge_after) {
if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL) {
rt->rt_ops->rtop_remove(rt, rs_before, rt->rt_arg);
rt->rt_ops->rtop_remove(rt, rs_after, rt->rt_arg);
}
range_tree_stat_decr(rt, rs_before);
range_tree_stat_decr(rt, rs_after);
rs_copy(rs_after, &tmp, rt);
uint64_t before_start = rs_get_start_raw(rs_before, rt);
uint64_t before_fill = rs_get_fill(rs_before, rt);
uint64_t after_fill = rs_get_fill(rs_after, rt);
zfs_btree_remove_from(&rt->rt_root, &where_before);
/*
* We have to re-find the node because our old reference is
* invalid as soon as we do any mutating btree operations.
*/
rs_after = zfs_btree_find(&rt->rt_root, &tmp, &where_after);
rs_set_start_raw(rs_after, rt, before_start);
rs_set_fill(rs_after, rt, after_fill + before_fill + fill);
rs = rs_after;
} else if (merge_before) {
if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
rt->rt_ops->rtop_remove(rt, rs_before, rt->rt_arg);
range_tree_stat_decr(rt, rs_before);
uint64_t before_fill = rs_get_fill(rs_before, rt);
rs_set_end(rs_before, rt, end);
rs_set_fill(rs_before, rt, before_fill + fill);
rs = rs_before;
} else if (merge_after) {
if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
rt->rt_ops->rtop_remove(rt, rs_after, rt->rt_arg);
range_tree_stat_decr(rt, rs_after);
uint64_t after_fill = rs_get_fill(rs_after, rt);
rs_set_start(rs_after, rt, start);
rs_set_fill(rs_after, rt, after_fill + fill);
rs = rs_after;
} else {
rs = &tmp;
rs_set_start(rs, rt, start);
rs_set_end(rs, rt, end);
rs_set_fill(rs, rt, fill);
zfs_btree_insert(&rt->rt_root, rs, &where);
}
if (gap != 0) {
ASSERT3U(rs_get_fill(rs, rt), <=, rs_get_end(rs, rt) -
rs_get_start(rs, rt));
} else {
ASSERT3U(rs_get_fill(rs, rt), ==, rs_get_end(rs, rt) -
rs_get_start(rs, rt));
}
if (rt->rt_ops != NULL && rt->rt_ops->rtop_add != NULL)
rt->rt_ops->rtop_add(rt, rs, rt->rt_arg);
range_tree_stat_incr(rt, rs);
rt->rt_space += size + bridge_size;
}
void
range_tree_add(void *arg, uint64_t start, uint64_t size)
{
range_tree_add_impl(arg, start, size, size);
}
static void
range_tree_remove_impl(range_tree_t *rt, uint64_t start, uint64_t size,
boolean_t do_fill)
{
zfs_btree_index_t where;
range_seg_t *rs;
range_seg_max_t rsearch, rs_tmp;
uint64_t end = start + size;
boolean_t left_over, right_over;
VERIFY3U(size, !=, 0);
VERIFY3U(size, <=, rt->rt_space);
if (rt->rt_type == RANGE_SEG64)
ASSERT3U(start + size, >, start);
rs_set_start(&rsearch, rt, start);
rs_set_end(&rsearch, rt, end);
rs = zfs_btree_find(&rt->rt_root, &rsearch, &where);
/* Make sure we completely overlap with someone */
if (rs == NULL) {
zfs_panic_recover("zfs: removing nonexistent segment from "
"range tree (offset=%llu size=%llu)",
(longlong_t)start, (longlong_t)size);
return;
}
/*
* Range trees with gap support must only remove complete segments
* from the tree. This allows us to maintain accurate fill accounting
* and to ensure that bridged sections are not leaked. If we need to
* remove less than the full segment, we can only adjust the fill count.
*/
if (rt->rt_gap != 0) {
if (do_fill) {
if (rs_get_fill(rs, rt) == size) {
start = rs_get_start(rs, rt);
end = rs_get_end(rs, rt);
size = end - start;
} else {
range_tree_adjust_fill(rt, rs, -size);
return;
}
} else if (rs_get_start(rs, rt) != start ||
rs_get_end(rs, rt) != end) {
zfs_panic_recover("zfs: freeing partial segment of "
"gap tree (offset=%llu size=%llu) of "
"(offset=%llu size=%llu)",
(longlong_t)start, (longlong_t)size,
(longlong_t)rs_get_start(rs, rt),
(longlong_t)rs_get_end(rs, rt) - rs_get_start(rs,
rt));
return;
}
}
VERIFY3U(rs_get_start(rs, rt), <=, start);
VERIFY3U(rs_get_end(rs, rt), >=, end);
left_over = (rs_get_start(rs, rt) != start);
right_over = (rs_get_end(rs, rt) != end);
range_tree_stat_decr(rt, rs);
if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
rt->rt_ops->rtop_remove(rt, rs, rt->rt_arg);
if (left_over && right_over) {
range_seg_max_t newseg;
rs_set_start(&newseg, rt, end);
rs_set_end_raw(&newseg, rt, rs_get_end_raw(rs, rt));
rs_set_fill(&newseg, rt, rs_get_end(rs, rt) - end);
range_tree_stat_incr(rt, &newseg);
// This modifies the buffer already inside the range tree
rs_set_end(rs, rt, start);
rs_copy(rs, &rs_tmp, rt);
if (zfs_btree_next(&rt->rt_root, &where, &where) != NULL)
zfs_btree_insert(&rt->rt_root, &newseg, &where);
else
zfs_btree_add(&rt->rt_root, &newseg);
if (rt->rt_ops != NULL && rt->rt_ops->rtop_add != NULL)
rt->rt_ops->rtop_add(rt, &newseg, rt->rt_arg);
} else if (left_over) {
// This modifies the buffer already inside the range tree
rs_set_end(rs, rt, start);
rs_copy(rs, &rs_tmp, rt);
} else if (right_over) {
// This modifies the buffer already inside the range tree
rs_set_start(rs, rt, end);
rs_copy(rs, &rs_tmp, rt);
} else {
zfs_btree_remove_from(&rt->rt_root, &where);
rs = NULL;
}
if (rs != NULL) {
/*
* The fill of the leftover segment will always be equal to
* the size, since we do not support removing partial segments
* of range trees with gaps.
*/
rs_set_fill_raw(rs, rt, rs_get_end_raw(rs, rt) -
rs_get_start_raw(rs, rt));
range_tree_stat_incr(rt, &rs_tmp);
if (rt->rt_ops != NULL && rt->rt_ops->rtop_add != NULL)
rt->rt_ops->rtop_add(rt, &rs_tmp, rt->rt_arg);
}
rt->rt_space -= size;
}
void
range_tree_remove(void *arg, uint64_t start, uint64_t size)
{
range_tree_remove_impl(arg, start, size, B_FALSE);
}
void
range_tree_remove_fill(range_tree_t *rt, uint64_t start, uint64_t size)
{
range_tree_remove_impl(rt, start, size, B_TRUE);
}
void
range_tree_resize_segment(range_tree_t *rt, range_seg_t *rs,
uint64_t newstart, uint64_t newsize)
{
int64_t delta = newsize - (rs_get_end(rs, rt) - rs_get_start(rs, rt));
range_tree_stat_decr(rt, rs);
if (rt->rt_ops != NULL && rt->rt_ops->rtop_remove != NULL)
rt->rt_ops->rtop_remove(rt, rs, rt->rt_arg);
rs_set_start(rs, rt, newstart);
rs_set_end(rs, rt, newstart + newsize);
range_tree_stat_incr(rt, rs);
if (rt->rt_ops != NULL && rt->rt_ops->rtop_add != NULL)
rt->rt_ops->rtop_add(rt, rs, rt->rt_arg);
rt->rt_space += delta;
}
static range_seg_t *
range_tree_find_impl(range_tree_t *rt, uint64_t start, uint64_t size)
{
range_seg_max_t rsearch;
uint64_t end = start + size;
VERIFY(size != 0);
rs_set_start(&rsearch, rt, start);
rs_set_end(&rsearch, rt, end);
return (zfs_btree_find(&rt->rt_root, &rsearch, NULL));
}
range_seg_t *
range_tree_find(range_tree_t *rt, uint64_t start, uint64_t size)
{
if (rt->rt_type == RANGE_SEG64)
ASSERT3U(start + size, >, start);
range_seg_t *rs = range_tree_find_impl(rt, start, size);
if (rs != NULL && rs_get_start(rs, rt) <= start &&
rs_get_end(rs, rt) >= start + size) {
return (rs);
}
return (NULL);
}
void
range_tree_verify_not_present(range_tree_t *rt, uint64_t off, uint64_t size)
{
range_seg_t *rs = range_tree_find(rt, off, size);
if (rs != NULL)
panic("segment already in tree; rs=%p", (void *)rs);
}
boolean_t
range_tree_contains(range_tree_t *rt, uint64_t start, uint64_t size)
{
return (range_tree_find(rt, start, size) != NULL);
}
/*
* Returns the first subset of the given range which overlaps with the range
* tree. Returns true if there is a segment in the range, and false if there
* isn't.
*/
boolean_t
range_tree_find_in(range_tree_t *rt, uint64_t start, uint64_t size,
uint64_t *ostart, uint64_t *osize)
{
if (rt->rt_type == RANGE_SEG64)
ASSERT3U(start + size, >, start);
range_seg_max_t rsearch;
rs_set_start(&rsearch, rt, start);
rs_set_end_raw(&rsearch, rt, rs_get_start_raw(&rsearch, rt) + 1);
zfs_btree_index_t where;
range_seg_t *rs = zfs_btree_find(&rt->rt_root, &rsearch, &where);
if (rs != NULL) {
*ostart = start;
*osize = MIN(size, rs_get_end(rs, rt) - start);
return (B_TRUE);
}
rs = zfs_btree_next(&rt->rt_root, &where, &where);
if (rs == NULL || rs_get_start(rs, rt) > start + size)
return (B_FALSE);
*ostart = rs_get_start(rs, rt);
*osize = MIN(start + size, rs_get_end(rs, rt)) -
rs_get_start(rs, rt);
return (B_TRUE);
}
/*
* Ensure that this range is not in the tree, regardless of whether
* it is currently in the tree.
*/
void
range_tree_clear(range_tree_t *rt, uint64_t start, uint64_t size)
{
range_seg_t *rs;
if (size == 0)
return;
if (rt->rt_type == RANGE_SEG64)
ASSERT3U(start + size, >, start);
while ((rs = range_tree_find_impl(rt, start, size)) != NULL) {
uint64_t free_start = MAX(rs_get_start(rs, rt), start);
uint64_t free_end = MIN(rs_get_end(rs, rt), start + size);
range_tree_remove(rt, free_start, free_end - free_start);
}
}
void
range_tree_swap(range_tree_t **rtsrc, range_tree_t **rtdst)
{
range_tree_t *rt;
ASSERT0(range_tree_space(*rtdst));
ASSERT0(zfs_btree_numnodes(&(*rtdst)->rt_root));
rt = *rtsrc;
*rtsrc = *rtdst;
*rtdst = rt;
}
void
range_tree_vacate(range_tree_t *rt, range_tree_func_t *func, void *arg)
{
if (rt->rt_ops != NULL && rt->rt_ops->rtop_vacate != NULL)
rt->rt_ops->rtop_vacate(rt, rt->rt_arg);
if (func != NULL) {
range_seg_t *rs;
zfs_btree_index_t *cookie = NULL;
while ((rs = zfs_btree_destroy_nodes(&rt->rt_root, &cookie)) !=
NULL) {
func(arg, rs_get_start(rs, rt), rs_get_end(rs, rt) -
rs_get_start(rs, rt));
}
} else {
zfs_btree_clear(&rt->rt_root);
}
bzero(rt->rt_histogram, sizeof (rt->rt_histogram));
rt->rt_space = 0;
}
void
range_tree_walk(range_tree_t *rt, range_tree_func_t *func, void *arg)
{
zfs_btree_index_t where;
for (range_seg_t *rs = zfs_btree_first(&rt->rt_root, &where);
rs != NULL; rs = zfs_btree_next(&rt->rt_root, &where, &where)) {
func(arg, rs_get_start(rs, rt), rs_get_end(rs, rt) -
rs_get_start(rs, rt));
}
}
range_seg_t *
range_tree_first(range_tree_t *rt)
{
return (zfs_btree_first(&rt->rt_root, NULL));
}
uint64_t
range_tree_space(range_tree_t *rt)
{
return (rt->rt_space);
}
uint64_t
range_tree_numsegs(range_tree_t *rt)
{
return ((rt == NULL) ? 0 : zfs_btree_numnodes(&rt->rt_root));
}
boolean_t
range_tree_is_empty(range_tree_t *rt)
{
ASSERT(rt != NULL);
return (range_tree_space(rt) == 0);
}
/* ARGSUSED */
void
rt_btree_create(range_tree_t *rt, void *arg)
{
zfs_btree_t *size_tree = arg;
size_t size;
switch (rt->rt_type) {
case RANGE_SEG32:
size = sizeof (range_seg32_t);
break;
case RANGE_SEG64:
size = sizeof (range_seg64_t);
break;
case RANGE_SEG_GAP:
size = sizeof (range_seg_gap_t);
break;
default:
panic("Invalid range seg type %d", rt->rt_type);
}
zfs_btree_create(size_tree, rt->rt_btree_compare, size);
}
/* ARGSUSED */
void
rt_btree_destroy(range_tree_t *rt, void *arg)
{
zfs_btree_t *size_tree = arg;
ASSERT0(zfs_btree_numnodes(size_tree));
zfs_btree_destroy(size_tree);
}
/* ARGSUSED */
void
rt_btree_add(range_tree_t *rt, range_seg_t *rs, void *arg)
{
zfs_btree_t *size_tree = arg;
zfs_btree_add(size_tree, rs);
}
/* ARGSUSED */
void
rt_btree_remove(range_tree_t *rt, range_seg_t *rs, void *arg)
{
zfs_btree_t *size_tree = arg;
zfs_btree_remove(size_tree, rs);
}
/* ARGSUSED */
void
rt_btree_vacate(range_tree_t *rt, void *arg)
{
zfs_btree_t *size_tree = arg;
zfs_btree_clear(size_tree);
zfs_btree_destroy(size_tree);
rt_btree_create(rt, arg);
}
range_tree_ops_t rt_btree_ops = {
.rtop_create = rt_btree_create,
.rtop_destroy = rt_btree_destroy,
.rtop_add = rt_btree_add,
.rtop_remove = rt_btree_remove,
.rtop_vacate = rt_btree_vacate
};
/*
* Remove any overlapping ranges between the given segment [start, end)
* from removefrom. Add non-overlapping leftovers to addto.
*/
void
range_tree_remove_xor_add_segment(uint64_t start, uint64_t end,
range_tree_t *removefrom, range_tree_t *addto)
{
zfs_btree_index_t where;
range_seg_max_t starting_rs;
rs_set_start(&starting_rs, removefrom, start);
rs_set_end_raw(&starting_rs, removefrom, rs_get_start_raw(&starting_rs,
removefrom) + 1);
range_seg_t *curr = zfs_btree_find(&removefrom->rt_root,
&starting_rs, &where);
if (curr == NULL)
curr = zfs_btree_next(&removefrom->rt_root, &where, &where);
range_seg_t *next;
for (; curr != NULL; curr = next) {
if (start == end)
return;
VERIFY3U(start, <, end);
/* there is no overlap */
if (end <= rs_get_start(curr, removefrom)) {
range_tree_add(addto, start, end - start);
return;
}
uint64_t overlap_start = MAX(rs_get_start(curr, removefrom),
start);
uint64_t overlap_end = MIN(rs_get_end(curr, removefrom),
end);
uint64_t overlap_size = overlap_end - overlap_start;
ASSERT3S(overlap_size, >, 0);
range_seg_max_t rs;
rs_copy(curr, &rs, removefrom);
range_tree_remove(removefrom, overlap_start, overlap_size);
if (start < overlap_start)
range_tree_add(addto, start, overlap_start - start);
start = overlap_end;
next = zfs_btree_find(&removefrom->rt_root, &rs, &where);
/*
* If we find something here, we only removed part of the
* curr segment. Either there's some left at the end
* because we've reached the end of the range we're removing,
* or there's some left at the start because we started
* partway through the range. Either way, we continue with
* the loop. If it's the former, we'll return at the start of
* the loop, and if it's the latter we'll see if there is more
* area to process.
*/
if (next != NULL) {
ASSERT(start == end || start == rs_get_end(&rs,
removefrom));
}
next = zfs_btree_next(&removefrom->rt_root, &where, &where);
}
VERIFY3P(curr, ==, NULL);
if (start != end) {
VERIFY3U(start, <, end);
range_tree_add(addto, start, end - start);
} else {
VERIFY3U(start, ==, end);
}
}
/*
* For each entry in rt, if it exists in removefrom, remove it
* from removefrom. Otherwise, add it to addto.
*/
void
range_tree_remove_xor_add(range_tree_t *rt, range_tree_t *removefrom,
range_tree_t *addto)
{
zfs_btree_index_t where;
for (range_seg_t *rs = zfs_btree_first(&rt->rt_root, &where); rs;
rs = zfs_btree_next(&rt->rt_root, &where, &where)) {
range_tree_remove_xor_add_segment(rs_get_start(rs, rt),
rs_get_end(rs, rt), removefrom, addto);
}
}
uint64_t
range_tree_min(range_tree_t *rt)
{
range_seg_t *rs = zfs_btree_first(&rt->rt_root, NULL);
return (rs != NULL ? rs_get_start(rs, rt) : 0);
}
uint64_t
range_tree_max(range_tree_t *rt)
{
range_seg_t *rs = zfs_btree_last(&rt->rt_root, NULL);
return (rs != NULL ? rs_get_end(rs, rt) : 0);
}
uint64_t
range_tree_span(range_tree_t *rt)
{
return (range_tree_max(rt) - range_tree_min(rt));
}
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