// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2011 Red Hat, Inc.
*
* This file is released under the GPL.
*/
#include "dm-btree-internal.h"
#include "dm-space-map.h"
#include "dm-transaction-manager.h"
#include <linux/export.h>
#include <linux/device-mapper.h>
#define DM_MSG_PREFIX "btree"
/*
*--------------------------------------------------------------
* Array manipulation
*--------------------------------------------------------------
*/
static void memcpy_disk(void *dest, const void *src, size_t len)
__dm_written_to_disk(src)
{
memcpy(dest, src, len);
__dm_unbless_for_disk(src);
}
static void array_insert(void *base, size_t elt_size, unsigned int nr_elts,
unsigned int index, void *elt)
__dm_written_to_disk(elt)
{
if (index < nr_elts)
memmove(base + (elt_size * (index + 1)),
base + (elt_size * index),
(nr_elts - index) * elt_size);
memcpy_disk(base + (elt_size * index), elt, elt_size);
}
/*----------------------------------------------------------------*/
/* makes the assumption that no two keys are the same. */
static int bsearch(struct btree_node *n, uint64_t key, int want_hi)
{
int lo = -1, hi = le32_to_cpu(n->header.nr_entries);
while (hi - lo > 1) {
int mid = lo + ((hi - lo) / 2);
uint64_t mid_key = le64_to_cpu(n->keys[mid]);
if (mid_key == key)
return mid;
if (mid_key < key)
lo = mid;
else
hi = mid;
}
return want_hi ? hi : lo;
}
int lower_bound(struct btree_node *n, uint64_t key)
{
return bsearch(n, key, 0);
}
static int upper_bound(struct btree_node *n, uint64_t key)
{
return bsearch(n, key, 1);
}
void inc_children(struct dm_transaction_manager *tm, struct btree_node *n,
struct dm_btree_value_type *vt)
{
uint32_t nr_entries = le32_to_cpu(n->header.nr_entries);
if (le32_to_cpu(n->header.flags) & INTERNAL_NODE)
dm_tm_with_runs(tm, value_ptr(n, 0), nr_entries, dm_tm_inc_range);
else if (vt->inc)
vt->inc(vt->context, value_ptr(n, 0), nr_entries);
}
static int insert_at(size_t value_size, struct btree_node *node, unsigned int index,
uint64_t key, void *value)
__dm_written_to_disk(value)
{
uint32_t nr_entries = le32_to_cpu(node->header.nr_entries);
uint32_t max_entries = le32_to_cpu(node->header.max_entries);
__le64 key_le = cpu_to_le64(key);
if (index > nr_entries ||
index >= max_entries ||
nr_entries >= max_entries) {
DMERR("too many entries in btree node for insert");
__dm_unbless_for_disk(value);
return -ENOMEM;
}
__dm_bless_for_disk(&key_le);
array_insert(node->keys, sizeof(*node->keys), nr_entries, index, &key_le);
array_insert(value_base(node), value_size, nr_entries, index, value);
node->header.nr_entries = cpu_to_le32(nr_entries + 1);
return 0;
}
/*----------------------------------------------------------------*/
/*
* We want 3n entries (for some n). This works more nicely for repeated
* insert remove loops than (2n + 1).
*/
static uint32_t calc_max_entries(size_t value_size, size_t block_size)
{
uint32_t total, n;
size_t elt_size = sizeof(uint64_t) + value_size; /* key + value */
block_size -= sizeof(struct node_header);
total = block_size / elt_size;
n = total / 3; /* rounds down */
return 3 * n;
}
int dm_btree_empty(struct dm_btree_info *info, dm_block_t *root)
{
int r;
struct dm_block *b;
struct btree_node *n;
size_t block_size;
uint32_t max_entries;
r = new_block(info, &b);
if (r < 0)
return r;
block_size = dm_bm_block_size(dm_tm_get_bm(info->tm));
max_entries = calc_max_entries(info->value_type.size, block_size);
n = dm_block_data(b);
memset(n, 0, block_size);
n->header.flags = cpu_to_le32(LEAF_NODE);
n->header.nr_entries = cpu_to_le32(0);
n->header.max_entries = cpu_to_le32(max_entries);
n->header.value_size = cpu_to_le32(info->value_type.size);
*root = dm_block_location(b);
unlock_block(info, b);
return 0;
}
EXPORT_SYMBOL_GPL(dm_btree_empty);
/*----------------------------------------------------------------*/
/*
* Deletion uses a recursive algorithm, since we have limited stack space
* we explicitly manage our own stack on the heap.
*/
#define MAX_SPINE_DEPTH 64
struct frame {
struct dm_block *b;
struct btree_node *n;
unsigned int level;
unsigned int nr_children;
unsigned int current_child;
};
struct del_stack {
struct dm_btree_info *info;
struct dm_transaction_manager *tm;
int top;
struct frame spine[MAX_SPINE_DEPTH];
};
static int top_frame(struct del_stack *s, struct frame **f)
{
if (s->top < 0) {
DMERR("btree deletion stack empty");
return -EINVAL;
}
*f = s->spine + s->top;
return 0;
}
static int unprocessed_frames(struct del_stack *s)
{
return s->top >= 0;
}
static void prefetch_children(struct del_stack *s, struct frame *f)
{
unsigned int i;
struct dm_block_manager *bm = dm_tm_get_bm(s->tm);
for (i = 0; i < f->nr_children; i++)
dm_bm_prefetch(bm, value64(f->n, i));
}
static bool is_internal_level(struct dm_btree_info *info, struct frame *f)
{
return f->level < (info->levels - 1);
}
static int push_frame(struct del_stack *s, dm_block_t b, unsigned int level)
{
int r;
uint32_t ref_count;
if (s->top >= MAX_SPINE_DEPTH - 1) {
DMERR("btree deletion stack out of memory");
return -ENOMEM;
}
r = dm_tm_ref(s->tm, b, &ref_count);
if (r)
return r;
if (ref_count > 1)
/*
* This is a shared node, so we can just decrement it's
* reference counter and leave the children.
*/
dm_tm_dec(s->tm, b);
else {
uint32_t flags;
struct frame *f = s->spine + ++s->top;
r = dm_tm_read_lock(s->tm, b, &btree_node_validator, &f->b);
if (r) {
s->top--;
return r;
}
f->n = dm_block_data(f->b);
f->level = level;
f->nr_children = le32_to_cpu(f->n->header.nr_entries);
f->current_child = 0;
flags = le32_to_cpu(f->n->header.flags);
if (flags & INTERNAL_NODE || is_internal_level(s->info, f))
prefetch_children(s, f);
}
return 0;
}
static void pop_frame(struct del_stack *s)
{
struct frame *f = s->spine + s->top--;
dm_tm_dec(s->tm, dm_block_location(f->b));
dm_tm_unlock(s->tm, f->b);
}
static void unlock_all_frames(struct del_stack *s)
{
struct frame *f;
while (unprocessed_frames(s)) {
f = s->spine + s->top--;
dm_tm_unlock(s->tm, f->b);
}
}
int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
{
int r;
struct del_stack *s;
/*
* dm_btree_del() is called via an ioctl, as such should be
* considered an FS op. We can't recurse back into the FS, so we
* allocate GFP_NOFS.
*/
s = kmalloc(sizeof(*s), GFP_NOFS);
if (!s)
return -ENOMEM;
s->info = info;
s->tm = info->tm;
s->top = -1;
r = push_frame(s, root, 0);
if (r)
goto out;
while (unprocessed_frames(s)) {
uint32_t flags;
struct frame *f;
dm_block_t b;
r = top_frame(s, &f);
if (r)
goto out;
if (f->current_child >= f->nr_children) {
pop_frame(s);
continue;
}
flags = le32_to_cpu(f->n->header.flags);
if (flags & INTERNAL_NODE) {
b = value64(f->n, f->current_child);
f->current_child++;
r = push_frame(s, b, f->level);
if (r)
goto out;
} else if (is_internal_level(info, f)) {
b = value64(f->n, f->current_child);
f->current_child++;
r = push_frame(s, b, f->level + 1);
if (r)
goto out;
} else {
if (info->value_type.dec)
info->value_type.dec(info->value_type.context,
value_ptr(f->n, 0), f->nr_children);
pop_frame(s);
}
}
out:
if (r) {
/* cleanup all frames of del_stack */
unlock_all_frames(s);
}
kfree(s);
return r;
}
EXPORT_SYMBOL_GPL(dm_btree_del);
/*----------------------------------------------------------------*/
static int btree_lookup_raw(struct ro_spine *s, dm_block_t block, uint64_t key,
int (*search_fn)(struct btree_node *, uint64_t),
uint64_t *result_key, void *v, size_t value_size)
{
int i, r;
uint32_t flags, nr_entries;
do {
r = ro_step(s, block);
if (r < 0)
return r;
i = search_fn(ro_node(s), key);
flags = le32_to_cpu(ro_node(s)->header.flags);
nr_entries = le32_to_cpu(ro_node(s)->header.nr_entries);
if (i < 0 || i >= nr_entries)
return -ENODATA;
if (flags & INTERNAL_NODE)
block = value64(ro_node(s), i);
} while (!(flags & LEAF_NODE));
*result_key = le64_to_cpu(ro_node(s)->keys[i]);
if (v)
memcpy(v, value_ptr(ro_node(s), i), value_size);
return 0;
}
int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
uint64_t *keys, void *value_le)
{
unsigned int level, last_level = info->levels - 1;
int r = -ENODATA;
uint64_t rkey;
__le64 internal_value_le;
struct ro_spine spine;
init_ro_spine(&spine, info);
for (level = 0; level < info->levels; level++) {
size_t size;
void *value_p;
if (level == last_level) {
value_p = value_le;
size = info->value_type.size;
} else {
value_p = &internal_value_le;
size = sizeof(uint64_t);
}
r = btree_lookup_raw(&spine, root, keys[level],
lower_bound, &rkey,
value_p, size);
if (!r) {
if (rkey != keys[level]) {
exit_ro_spine(&spine);
return -ENODATA;
}
} else {
exit_ro_spine(&spine);
return r;
}
root = le64_to_cpu(internal_value_le);
}
exit_ro_spine(&spine);
return r;
}
EXPORT_SYMBOL_GPL(dm_btree_lookup);
static int dm_btree_lookup_next_single(struct dm_btree_info *info, dm_block_t root,
uint64_t key, uint64_t *rkey, void *value_le)
{
int r, i;
uint32_t flags, nr_entries;
struct dm_block *node;
struct btree_node *n;
r = bn_read_lock(info, root, &node);
if (r)
return r;
n = dm_block_data(node);
flags = le32_to_cpu(n->header.flags);
nr_entries = le32_to_cpu(n->header.nr_entries);
if (flags & INTERNAL_NODE) {
i = lower_bound(n, key);
if (i < 0) {
/*
* avoid early -ENODATA return when all entries are
* higher than the search @key.
*/
i = 0;
}
if (i >= nr_entries) {
r = -ENODATA;
goto out;
}
r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
if (r == -ENODATA && i < (nr_entries - 1)) {
i++;
r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
}
} else {
i = upper_bound(n, key);
if (i < 0 || i >= nr_entries) {
r = -ENODATA;
goto out;
}
*rkey = le64_to_cpu(n->keys[i]);
memcpy(value_le, value_ptr(n, i), info->value_type.size);
}
out:
dm_tm_unlock(info->tm, node);
return r;
}
int dm_btree_lookup_next(struct dm_btree_info *info, dm_block_t root,
uint64_t *keys, uint64_t *rkey, void *value_le)
{
unsigned int level;
int r = -ENODATA;
__le64 internal_value_le;
struct ro_spine spine;
init_ro_spine(&spine, info);
for (level = 0; level < info->levels - 1u; level++) {
r = btree_lookup_raw(&spine, root, keys[level],
lower_bound, rkey,
&internal_value_le, sizeof(uint64_t));
if (r)
goto out;
if (*rkey != keys[level]) {
r = -ENODATA;
goto out;
}
root = le64_to_cpu(internal_value_le);
}
r = dm_btree_lookup_next_single(info, root, keys[level], rkey, value_le);
out:
exit_ro_spine(&spine);
return r;
}
EXPORT_SYMBOL_GPL(dm_btree_lookup_next);
/*----------------------------------------------------------------*/
/*
* Copies entries from one region of a btree node to another. The regions
* must not overlap.
*/
static void copy_entries(struct btree_node *dest, unsigned int dest_offset,
struct btree_node *src, unsigned int src_offset,
unsigned int count)
{
size_t value_size = le32_to_cpu(dest->header.value_size);
memcpy(dest->keys + dest_offset, src->keys + src_offset, count * sizeof(uint64_t));
memcpy(value_ptr(dest, dest_offset), value_ptr(src, src_offset), count * value_size);
}
/*
* Moves entries from one region fo a btree node to another. The regions
* may overlap.
*/
static void move_entries(struct btree_node *dest, unsigned int dest_offset,
struct btree_node *src, unsigned int src_offset,
unsigned int count)
{
size_t value_size = le32_to_cpu(dest->header.value_size);
memmove(dest->keys + dest_offset, src->keys + src_offset, count * sizeof(uint64_t));
memmove(value_ptr(dest, dest_offset), value_ptr(src, src_offset), count * value_size);
}
/*
* Erases the first 'count' entries of a btree node, shifting following
* entries down into their place.
*/
static void shift_down(struct btree_node *n, unsigned int count)
{
move_entries(n, 0, n, count, le32_to_cpu(n->header.nr_entries) - count);
}
/*
* Moves entries in a btree node up 'count' places, making space for
* new entries at the start of the node.
*/
static void shift_up(struct btree_node *n, unsigned int count)
{
move_entries(n, count, n, 0, le32_to_cpu(n->header.nr_entries));
}
/*
* Redistributes entries between two btree nodes to make them
* have similar numbers of entries.
*/
static void redistribute2(struct btree_node *left, struct btree_node *right)
{
unsigned int nr_left = le32_to_cpu(left->header.nr_entries);
unsigned int nr_right = le32_to_cpu(right->header.nr_entries);
unsigned int total = nr_left + nr_right;
unsigned int target_left = total / 2;
unsigned int target_right = total - target_left;
if (nr_left < target_left) {
unsigned int delta = target_left - nr_left;
copy_entries(left, nr_left, right, 0, delta);
shift_down(right, delta);
} else if (nr_left > target_left) {
unsigned int delta = nr_left - target_left;
if (nr_right)
shift_up(right, delta);
copy_entries(right, 0, left, target_left, delta);
}
left->header.nr_entries = cpu_to_le32(target_left);
right->header.nr_entries = cpu_to_le32(target_right);
}
/*
* Redistribute entries between three nodes. Assumes the central
* node is empty.
*/
static void redistribute3(struct btree_node *left, struct btree_node *center,
struct btree_node *right)
{
unsigned int nr_left = le32_to_cpu(left->header.nr_entries);
unsigned int nr_center = le32_to_cpu(center->header.nr_entries);
unsigned int nr_right = le32_to_cpu(right->header.nr_entries);
unsigned int total, target_left, target_center, target_right;
BUG_ON(nr_center);
total = nr_left + nr_right;
target_left = total / 3;
target_center = (total - target_left) / 2;
target_right = (total - target_left - target_center);
if (nr_left < target_left) {
unsigned int left_short = target_left - nr_left;
copy_entries(left, nr_left, right, 0, left_short);
copy_entries(center, 0, right, left_short, target_center);
shift_down(right, nr_right - target_right);
} else if (nr_left < (target_left + target_center)) {
unsigned int left_to_center = nr_left - target_left;
copy_entries(center, 0, left, target_left, left_to_center);
copy_entries(center, left_to_center, right, 0, target_center - left_to_center);
shift_down(right, nr_right - target_right);
} else {
unsigned int right_short = target_right - nr_right;
shift_up(right, right_short);
copy_entries(right, 0, left, nr_left - right_short, right_short);
copy_entries(center, 0, left, target_left, nr_left - target_left);
}
left->header.nr_entries = cpu_to_le32(target_left);
center->header.nr_entries = cpu_to_le32(target_center);
right->header.nr_entries = cpu_to_le32(target_right);
}
/*
* Splits a node by creating a sibling node and shifting half the nodes
* contents across. Assumes there is a parent node, and it has room for
* another child.
*
* Before:
* +--------+
* | Parent |
* +--------+
* |
* v
* +----------+
* | A ++++++ |
* +----------+
*
*
* After:
* +--------+
* | Parent |
* +--------+
* | |
* v +------+
* +---------+ |
* | A* +++ | v
* +---------+ +-------+
* | B +++ |
* +-------+
*
* Where A* is a shadow of A.
*/
static int split_one_into_two(struct shadow_spine *s, unsigned int parent_index,
struct dm_btree_value_type *vt, uint64_t key)
{
int r;
struct dm_block *left, *right, *parent;
struct btree_node *ln, *rn, *pn;
__le64 location;
left = shadow_current(s);
r = new_block(s->info, &right);
if (r < 0)
return r;
ln = dm_block_data(left);
rn = dm_block_data(right);
rn->header.flags = ln->header.flags;
rn->header.nr_entries = cpu_to_le32(0);
rn->header.max_entries = ln->header.max_entries;
rn->header.value_size = ln->header.value_size;
redistribute2(ln, rn);
/* patch up the parent */
parent = shadow_parent(s);
pn = dm_block_data(parent);
location = cpu_to_le64(dm_block_location(right));
__dm_bless_for_disk(&location);
r = insert_at(sizeof(__le64), pn, parent_index + 1,
le64_to_cpu(rn->keys[0]), &location);
if (r) {
unlock_block(s->info, right);
return r;
}
/* patch up the spine */
if (key < le64_to_cpu(rn->keys[0])) {
unlock_block(s->info, right);
s->nodes[1] = left;
} else {
unlock_block(s->info, left);
s->nodes[1] = right;
}
return 0;
}
/*
* We often need to modify a sibling node. This function shadows a particular
* child of the given parent node. Making sure to update the parent to point
* to the new shadow.
*/
static int shadow_child(struct dm_btree_info *info, struct dm_btree_value_type *vt,
struct btree_node *parent, unsigned int index,
struct dm_block **result)
{
int r, inc;
dm_block_t root;
struct btree_node *node;
root = value64(parent, index);
r = dm_tm_shadow_block(info->tm, root, &btree_node_validator,
result, &inc);
if (r)
return r;
node = dm_block_data(*result);
if (inc)
inc_children(info->tm, node, vt);
*((__le64 *) value_ptr(parent, index)) =
cpu_to_le64(dm_block_location(*result));
return 0;
}
/*
* Splits two nodes into three. This is more work, but results in fuller
* nodes, so saves metadata space.
*/
static int split_two_into_three(struct shadow_spine *s, unsigned int parent_index,
struct dm_btree_value_type *vt, uint64_t key)
{
int r;
unsigned int middle_index;
struct dm_block *left, *middle, *right, *parent;
struct btree_node *ln, *rn, *mn, *pn;
__le64 location;
parent = shadow_parent(s);
pn = dm_block_data(parent);
if (parent_index == 0) {
middle_index = 1;
left = shadow_current(s);
r = shadow_child(s->info, vt, pn, parent_index + 1, &right);
if (r)
return r;
} else {
middle_index = parent_index;
right = shadow_current(s);
r = shadow_child(s->info, vt, pn, parent_index - 1, &left);
if (r)
return r;
}
r = new_block(s->info, &middle);
if (r < 0)
return r;
ln = dm_block_data(left);
mn = dm_block_data(middle);
rn = dm_block_data(right);
mn->header.nr_entries = cpu_to_le32(0);
mn->header.flags = ln->header.flags;
mn->header.max_entries = ln->header.max_entries;
mn->header.value_size = ln->header.value_size;
redistribute3(ln, mn, rn);
/* patch up the parent */
pn->keys[middle_index] = rn->keys[0];
location = cpu_to_le64(dm_block_location(middle));
__dm_bless_for_disk(&location);
r = insert_at(sizeof(__le64), pn, middle_index,
le64_to_cpu(mn->keys[0]), &location);
if (r) {
if (shadow_current(s) != left)
unlock_block(s->info, left);
unlock_block(s->info, middle);
if (shadow_current(s) != right)
unlock_block(s->info, right);
return r;
}
/* patch up the spine */
if (key < le64_to_cpu(mn->keys[0])) {
unlock_block(s->info, middle);
unlock_block(s->info, right);
s->nodes[1] = left;
} else if (key < le64_to_cpu(rn->keys[0])) {
unlock_block(s->info, left);
unlock_block(s->info, right);
s->nodes[1] = middle;
} else {
unlock_block(s->info, left);
unlock_block(s->info, middle);
s->nodes[1] = right;
}
return 0;
}
/*----------------------------------------------------------------*/
/*
* Splits a node by creating two new children beneath the given node.
*
* Before:
* +----------+
* | A ++++++ |
* +----------+
*
*
* After:
* +------------+
* | A (shadow) |
* +------------+
* | |
* +------+ +----+
* | |
* v v
* +-------+ +-------+
* | B +++ | | C +++ |
* +-------+ +-------+
*/
static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
{
int r;
size_t size;
unsigned int nr_left, nr_right;
struct dm_block *left, *right, *new_parent;
struct btree_node *pn, *ln, *rn;
__le64 val;
new_parent = shadow_current(s);
pn = dm_block_data(new_parent);
size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
sizeof(__le64) : s->info->value_type.size;
/* create & init the left block */
r = new_block(s->info, &left);
if (r < 0)
return r;
ln = dm_block_data(left);
nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
ln->header.flags = pn->header.flags;
ln->header.nr_entries = cpu_to_le32(nr_left);
ln->header.max_entries = pn->header.max_entries;
ln->header.value_size = pn->header.value_size;
memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
/* create & init the right block */
r = new_block(s->info, &right);
if (r < 0) {
unlock_block(s->info, left);
return r;
}
rn = dm_block_data(right);
nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
rn->header.flags = pn->header.flags;
rn->header.nr_entries = cpu_to_le32(nr_right);
rn->header.max_entries = pn->header.max_entries;
rn->header.value_size = pn->header.value_size;
memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left),
nr_right * size);
/* new_parent should just point to l and r now */
pn->header.flags = cpu_to_le32(INTERNAL_NODE);
pn->header.nr_entries = cpu_to_le32(2);
pn->header.max_entries = cpu_to_le32(
calc_max_entries(sizeof(__le64),
dm_bm_block_size(
dm_tm_get_bm(s->info->tm))));
pn->header.value_size = cpu_to_le32(sizeof(__le64));
val = cpu_to_le64(dm_block_location(left));
__dm_bless_for_disk(&val);
pn->keys[0] = ln->keys[0];
memcpy_disk(value_ptr(pn, 0), &val, sizeof(__le64));
val = cpu_to_le64(dm_block_location(right));
__dm_bless_for_disk(&val);
pn->keys[1] = rn->keys[0];
memcpy_disk(value_ptr(pn, 1), &val, sizeof(__le64));
unlock_block(s->info, left);
unlock_block(s->info, right);
return 0;
}
/*----------------------------------------------------------------*/
/*
* Redistributes a node's entries with its left sibling.
*/
static int rebalance_left(struct shadow_spine *s, struct dm_btree_value_type *vt,
unsigned int parent_index, uint64_t key)
{
int r;
struct dm_block *sib;
struct btree_node *left, *right, *parent = dm_block_data(shadow_parent(s));
r = shadow_child(s->info, vt, parent, parent_index - 1, &sib);
if (r)
return r;
left = dm_block_data(sib);
right = dm_block_data(shadow_current(s));
redistribute2(left, right);
*key_ptr(parent, parent_index) = right->keys[0];
if (key < le64_to_cpu(right->keys[0])) {
unlock_block(s->info, s->nodes[1]);
s->nodes[1] = sib;
} else {
unlock_block(s->info, sib);
}
return 0;
}
/*
* Redistributes a nodes entries with its right sibling.
*/
static int rebalance_right(struct shadow_spine *s, struct dm_btree_value_type *vt,
unsigned int parent_index, uint64_t key)
{
int r;
struct dm_block *sib;
struct btree_node *left, *right, *parent = dm_block_data(shadow_parent(s));
r = shadow_child(s->info, vt, parent, parent_index + 1, &sib);
if (r)
return r;
left = dm_block_data(shadow_current(s));
right = dm_block_data(sib);
redistribute2(left, right);
*key_ptr(parent, parent_index + 1) = right->keys[0];
if (key < le64_to_cpu(right->keys[0])) {
unlock_block(s->info, sib);
} else {
unlock_block(s->info, s->nodes[1]);
s->nodes[1] = sib;
}
return 0;
}
/*
* Returns the number of spare entries in a node.
*/
static int get_node_free_space(struct dm_btree_info *info, dm_block_t b, unsigned int *space)
{
int r;
unsigned int nr_entries;
struct dm_block *block;
struct btree_node *node;
r = bn_read_lock(info, b, &block);
if (r)
return r;
node = dm_block_data(block);
nr_entries = le32_to_cpu(node->header.nr_entries);
*space = le32_to_cpu(node->header.max_entries) - nr_entries;
unlock_block(info, block);
return 0;
}
/*
* Make space in a node, either by moving some entries to a sibling,
* or creating a new sibling node. SPACE_THRESHOLD defines the minimum
* number of free entries that must be in the sibling to make the move
* worth while. If the siblings are shared (eg, part of a snapshot),
* then they are not touched, since this break sharing and so consume
* more space than we save.
*/
#define SPACE_THRESHOLD 8
static int rebalance_or_split(struct shadow_spine *s, struct dm_btree_value_type *vt,
unsigned int parent_index, uint64_t key)
{
int r;
struct btree_node *parent = dm_block_data(shadow_parent(s));
unsigned int nr_parent = le32_to_cpu(parent->header.nr_entries);
unsigned int free_space;
int left_shared = 0, right_shared = 0;
/* Should we move entries to the left sibling? */
if (parent_index > 0) {
dm_block_t left_b = value64(parent, parent_index - 1);
r = dm_tm_block_is_shared(s->info->tm, left_b, &left_shared);
if (r)
return r;
if (!left_shared) {
r = get_node_free_space(s->info, left_b, &free_space);
if (r)
return r;
if (free_space >= SPACE_THRESHOLD)
return rebalance_left(s, vt, parent_index, key);
}
}
/* Should we move entries to the right sibling? */
if (parent_index < (nr_parent - 1)) {
dm_block_t right_b = value64(parent, parent_index + 1);
r = dm_tm_block_is_shared(s->info->tm, right_b, &right_shared);
if (r)
return r;
if (!right_shared) {
r = get_node_free_space(s->info, right_b, &free_space);
if (r)
return r;
if (free_space >= SPACE_THRESHOLD)
return rebalance_right(s, vt, parent_index, key);
}
}
/*
* We need to split the node, normally we split two nodes
* into three. But when inserting a sequence that is either
* monotonically increasing or decreasing it's better to split
* a single node into two.
*/
if (left_shared || right_shared || (nr_parent <= 2) ||
(parent_index == 0) || (parent_index + 1 == nr_parent)) {
return split_one_into_two(s, parent_index, vt, key);
} else {
return split_two_into_three(s, parent_index, vt, key);
}
}
/*
* Does the node contain a particular key?
*/
static bool contains_key(struct btree_node *node, uint64_t key)
{
int i = lower_bound(node, key);
if (i >= 0 && le64_to_cpu(node->keys[i]) == key)
return true;
return false;
}
/*
* In general we preemptively make sure there's a free entry in every
* node on the spine when doing an insert. But we can avoid that with
* leaf nodes if we know it's an overwrite.
*/
static bool has_space_for_insert(struct btree_node *node, uint64_t key)
{
if (node->header.nr_entries == node->header.max_entries) {
if (le32_to_cpu(node->header.flags) & LEAF_NODE) {
/* we don't need space if it's an overwrite */
return contains_key(node, key);
}
return false;
}
return true;
}
static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
struct dm_btree_value_type *vt,
uint64_t key, unsigned int *index)
{
int r, i = *index, top = 1;
struct btree_node *node;
for (;;) {
r = shadow_step(s, root, vt);
if (r < 0)
return r;
node = dm_block_data(shadow_current(s));
/*
* We have to patch up the parent node, ugly, but I don't
* see a way to do this automatically as part of the spine
* op.
*/
if (shadow_has_parent(s) && i >= 0) { /* FIXME: second clause unness. */
__le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
__dm_bless_for_disk(&location);
memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
&location, sizeof(__le64));
}
node = dm_block_data(shadow_current(s));
if (!has_space_for_insert(node, key)) {
if (top)
r = btree_split_beneath(s, key);
else
r = rebalance_or_split(s, vt, i, key);
if (r < 0)
return r;
/* making space can cause the current node to change */
node = dm_block_data(shadow_current(s));
}
i = lower_bound(node, key);
if (le32_to_cpu(node->header.flags) & LEAF_NODE)
break;
if (i < 0) {
/* change the bounds on the lowest key */
node->keys[0] = cpu_to_le64(key);
i = 0;
}
root = value64(node, i);
top = 0;
}
if (i < 0 || le64_to_cpu(node->keys[i]) != key)
i++;
*index = i;
return 0;
}
static int __btree_get_overwrite_leaf(struct shadow_spine *s, dm_block_t root,
uint64_t key, int *index)
{
int r, i = -1;
struct btree_node *node;
*index = 0;
for (;;) {
r = shadow_step(s, root, &s->info->value_type);
if (r < 0)
return r;
node = dm_block_data(shadow_current(s));
/*
* We have to patch up the parent node, ugly, but I don't
* see a way to do this automatically as part of the spine
* op.
*/
if (shadow_has_parent(s) && i >= 0) {
__le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
__dm_bless_for_disk(&location);
memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
&location, sizeof(__le64));
}
node = dm_block_data(shadow_current(s));
i = lower_bound(node, key);
BUG_ON(i < 0);
BUG_ON(i >= le32_to_cpu(node->header.nr_entries));
if (le32_to_cpu(node->header.flags) & LEAF_NODE) {
if (key != le64_to_cpu(node->keys[i]))
return -EINVAL;
break;
}
root = value64(node, i);
}
*index = i;
return 0;
}
int btree_get_overwrite_leaf(struct dm_btree_info *info, dm_block_t root,
uint64_t key, int *index,
dm_block_t *new_root, struct dm_block **leaf)
{
int r;
struct shadow_spine spine;
BUG_ON(info->levels > 1);
init_shadow_spine(&spine, info);
r = __btree_get_overwrite_leaf(&spine, root, key, index);
if (!r) {
*new_root = shadow_root(&spine);
*leaf = shadow_current(&spine);
/*
* Decrement the count so exit_shadow_spine() doesn't
* unlock the leaf.
*/
spine.count--;
}
exit_shadow_spine(&spine);
return r;
}
static bool need_insert(struct btree_node *node, uint64_t *keys,
unsigned int level, unsigned int index)
{
return ((index >= le32_to_cpu(node->header.nr_entries)) ||
(le64_to_cpu(node->keys[index]) != keys[level]));
}
static int insert(struct dm_btree_info *info, dm_block_t root,
uint64_t *keys, void *value, dm_block_t *new_root,
int *inserted)
__dm_written_to_disk(value)
{
int r;
unsigned int level, index = -1, last_level = info->levels - 1;
dm_block_t block = root;
struct shadow_spine spine;
struct btree_node *n;
struct dm_btree_value_type le64_type;
init_le64_type(info->tm, &le64_type);
init_shadow_spine(&spine, info);
for (level = 0; level < (info->levels - 1); level++) {
r = btree_insert_raw(&spine, block, &le64_type, keys[level], &index);
if (r < 0)
goto bad;
n = dm_block_data(shadow_current(&spine));
if (need_insert(n, keys, level, index)) {
dm_block_t new_tree;
__le64 new_le;
r = dm_btree_empty(info, &new_tree);
if (r < 0)
goto bad;
new_le = cpu_to_le64(new_tree);
__dm_bless_for_disk(&new_le);
r = insert_at(sizeof(uint64_t), n, index,
keys[level], &new_le);
if (r)
goto bad;
}
if (level < last_level)
block = value64(n, index);
}
r = btree_insert_raw(&spine, block, &info->value_type,
keys[level], &index);
if (r < 0)
goto bad;
n = dm_block_data(shadow_current(&spine));
if (need_insert(n, keys, level, index)) {
if (inserted)
*inserted = 1;
r = insert_at(info->value_type.size, n, index,
keys[level], value);
if (r)
goto bad_unblessed;
} else {
if (inserted)
*inserted = 0;
if (info->value_type.dec &&
(!info->value_type.equal ||
!info->value_type.equal(
info->value_type.context,
value_ptr(n, index),
value))) {
info->value_type.dec(info->value_type.context,
value_ptr(n, index), 1);
}
memcpy_disk(value_ptr(n, index),
value, info->value_type.size);
}
*new_root = shadow_root(&spine);
exit_shadow_spine(&spine);
return 0;
bad:
__dm_unbless_for_disk(value);
bad_unblessed:
exit_shadow_spine(&spine);
return r;
}
int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
uint64_t *keys, void *value, dm_block_t *new_root)
__dm_written_to_disk(value)
{
return insert(info, root, keys, value, new_root, NULL);
}
EXPORT_SYMBOL_GPL(dm_btree_insert);
int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
uint64_t *keys, void *value, dm_block_t *new_root,
int *inserted)
__dm_written_to_disk(value)
{
return insert(info, root, keys, value, new_root, inserted);
}
EXPORT_SYMBOL_GPL(dm_btree_insert_notify);
/*----------------------------------------------------------------*/
static int find_key(struct ro_spine *s, dm_block_t block, bool find_highest,
uint64_t *result_key, dm_block_t *next_block)
{
int i, r;
uint32_t flags;
do {
r = ro_step(s, block);
if (r < 0)
return r;
flags = le32_to_cpu(ro_node(s)->header.flags);
i = le32_to_cpu(ro_node(s)->header.nr_entries);
if (!i)
return -ENODATA;
i--;
if (find_highest)
*result_key = le64_to_cpu(ro_node(s)->keys[i]);
else
*result_key = le64_to_cpu(ro_node(s)->keys[0]);
if (next_block || flags & INTERNAL_NODE) {
if (find_highest)
block = value64(ro_node(s), i);
else
block = value64(ro_node(s), 0);
}
} while (flags & INTERNAL_NODE);
if (next_block)
*next_block = block;
return 0;
}
static int dm_btree_find_key(struct dm_btree_info *info, dm_block_t root,
bool find_highest, uint64_t *result_keys)
{
int r = 0, count = 0, level;
struct ro_spine spine;
init_ro_spine(&spine, info);
for (level = 0; level < info->levels; level++) {
r = find_key(&spine, root, find_highest, result_keys + level,
level == info->levels - 1 ? NULL : &root);
if (r == -ENODATA) {
r = 0;
break;
} else if (r)
break;
count++;
}
exit_ro_spine(&spine);
return r ? r : count;
}
int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
uint64_t *result_keys)
{
return dm_btree_find_key(info, root, true, result_keys);
}
EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);
int dm_btree_find_lowest_key(struct dm_btree_info *info, dm_block_t root,
uint64_t *result_keys)
{
return dm_btree_find_key(info, root, false, result_keys);
}
EXPORT_SYMBOL_GPL(dm_btree_find_lowest_key);
/*----------------------------------------------------------------*/
/*
* FIXME: We shouldn't use a recursive algorithm when we have limited stack
* space. Also this only works for single level trees.
*/
static int walk_node(struct dm_btree_info *info, dm_block_t block,
int (*fn)(void *context, uint64_t *keys, void *leaf),
void *context)
{
int r;
unsigned int i, nr;
struct dm_block *node;
struct btree_node *n;
uint64_t keys;
r = bn_read_lock(info, block, &node);
if (r)
return r;
n = dm_block_data(node);
nr = le32_to_cpu(n->header.nr_entries);
for (i = 0; i < nr; i++) {
if (le32_to_cpu(n->header.flags) & INTERNAL_NODE) {
r = walk_node(info, value64(n, i), fn, context);
if (r)
goto out;
} else {
keys = le64_to_cpu(*key_ptr(n, i));
r = fn(context, &keys, value_ptr(n, i));
if (r)
goto out;
}
}
out:
dm_tm_unlock(info->tm, node);
return r;
}
int dm_btree_walk(struct dm_btree_info *info, dm_block_t root,
int (*fn)(void *context, uint64_t *keys, void *leaf),
void *context)
{
BUG_ON(info->levels > 1);
return walk_node(info, root, fn, context);
}
EXPORT_SYMBOL_GPL(dm_btree_walk);
/*----------------------------------------------------------------*/
static void prefetch_values(struct dm_btree_cursor *c)
{
unsigned int i, nr;
__le64 value_le;
struct cursor_node *n = c->nodes + c->depth - 1;
struct btree_node *bn = dm_block_data(n->b);
struct dm_block_manager *bm = dm_tm_get_bm(c->info->tm);
BUG_ON(c->info->value_type.size != sizeof(value_le));
nr = le32_to_cpu(bn->header.nr_entries);
for (i = 0; i < nr; i++) {
memcpy(&value_le, value_ptr(bn, i), sizeof(value_le));
dm_bm_prefetch(bm, le64_to_cpu(value_le));
}
}
static bool leaf_node(struct dm_btree_cursor *c)
{
struct cursor_node *n = c->nodes + c->depth - 1;
struct btree_node *bn = dm_block_data(n->b);
return le32_to_cpu(bn->header.flags) & LEAF_NODE;
}
static int push_node(struct dm_btree_cursor *c, dm_block_t b)
{
int r;
struct cursor_node *n = c->nodes + c->depth;
if (c->depth >= DM_BTREE_CURSOR_MAX_DEPTH - 1) {
DMERR("couldn't push cursor node, stack depth too high");
return -EINVAL;
}
r = bn_read_lock(c->info, b, &n->b);
if (r)
return r;
n->index = 0;
c->depth++;
if (c->prefetch_leaves || !leaf_node(c))
prefetch_values(c);
return 0;
}
static void pop_node(struct dm_btree_cursor *c)
{
c->depth--;
unlock_block(c->info, c->nodes[c->depth].b);
}
static int inc_or_backtrack(struct dm_btree_cursor *c)
{
struct cursor_node *n;
struct btree_node *bn;
for (;;) {
if (!c->depth)
return -ENODATA;
n = c->nodes + c->depth - 1;
bn = dm_block_data(n->b);
n->index++;
if (n->index < le32_to_cpu(bn->header.nr_entries))
break;
pop_node(c);
}
return 0;
}
static int find_leaf(struct dm_btree_cursor *c)
{
int r = 0;
struct cursor_node *n;
struct btree_node *bn;
__le64 value_le;
for (;;) {
n = c->nodes + c->depth - 1;
bn = dm_block_data(n->b);
if (le32_to_cpu(bn->header.flags) & LEAF_NODE)
break;
memcpy(&value_le, value_ptr(bn, n->index), sizeof(value_le));
r = push_node(c, le64_to_cpu(value_le));
if (r) {
DMERR("push_node failed");
break;
}
}
if (!r && (le32_to_cpu(bn->header.nr_entries) == 0))
return -ENODATA;
return r;
}
int dm_btree_cursor_begin(struct dm_btree_info *info, dm_block_t root,
bool prefetch_leaves, struct dm_btree_cursor *c)
{
int r;
c->info = info;
c->root = root;
c->depth = 0;
c->prefetch_leaves = prefetch_leaves;
r = push_node(c, root);
if (r)
return r;
return find_leaf(c);
}
EXPORT_SYMBOL_GPL(dm_btree_cursor_begin);
void dm_btree_cursor_end(struct dm_btree_cursor *c)
{
while (c->depth)
pop_node(c);
}
EXPORT_SYMBOL_GPL(dm_btree_cursor_end);
int dm_btree_cursor_next(struct dm_btree_cursor *c)
{
int r = inc_or_backtrack(c);
if (!r) {
r = find_leaf(c);
if (r)
DMERR("find_leaf failed");
}
return r;
}
EXPORT_SYMBOL_GPL(dm_btree_cursor_next);
int dm_btree_cursor_skip(struct dm_btree_cursor *c, uint32_t count)
{
int r = 0;
while (count-- && !r)
r = dm_btree_cursor_next(c);
return r;
}
EXPORT_SYMBOL_GPL(dm_btree_cursor_skip);
int dm_btree_cursor_get_value(struct dm_btree_cursor *c, uint64_t *key, void *value_le)
{
if (c->depth) {
struct cursor_node *n = c->nodes + c->depth - 1;
struct btree_node *bn = dm_block_data(n->b);
if (le32_to_cpu(bn->header.flags) & INTERNAL_NODE)
return -EINVAL;
*key = le64_to_cpu(*key_ptr(bn, n->index));
memcpy(value_le, value_ptr(bn, n->index), c->info->value_type.size);
return 0;
} else
return -ENODATA;
}
EXPORT_SYMBOL_GPL(dm_btree_cursor_get_value);
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