- 根目录:
- drivers
- md
- persistent-data
- dm-btree.c
/*
* 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 nr_elts,
unsigned 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);
}
void inc_children(struct dm_transaction_manager *tm, struct btree_node *n,
struct dm_btree_value_type *vt)
{
unsigned i;
uint32_t nr_entries = le32_to_cpu(n->header.nr_entries);
if (le32_to_cpu(n->header.flags) & INTERNAL_NODE)
for (i = 0; i < nr_entries; i++)
dm_tm_inc(tm, value64(n, i));
else if (vt->inc)
for (i = 0; i < nr_entries; i++)
vt->inc(vt->context, value_ptr(n, i));
}
static int insert_at(size_t value_size, struct btree_node *node, unsigned index,
uint64_t key, void *value)
__dm_written_to_disk(value)
{
uint32_t nr_entries = le32_to_cpu(node->header.nr_entries);
__le64 key_le = cpu_to_le64(key);
if (index > nr_entries ||
index >= le32_to_cpu(node->header.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);
return unlock_block(info, b);
}
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 level;
unsigned nr_children;
unsigned current_child;
};
struct del_stack {
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 int push_frame(struct del_stack *s, dm_block_t b, unsigned 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 {
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;
}
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);
}
int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
{
int r;
struct del_stack *s;
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (!s)
return -ENOMEM;
s->tm = info->tm;
s->top = -1;
r = push_frame(s, root, 1);
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 (f->level != (info->levels - 1)) {
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) {
unsigned i;
for (i = 0; i < f->nr_children; i++)
info->value_type.dec(info->value_type.context,
value_ptr(f->n, i));
}
f->current_child = f->nr_children;
}
}
out:
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]);
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 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);
/*
* 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 btree_split_sibling(struct shadow_spine *s, dm_block_t root,
unsigned parent_index, uint64_t key)
{
int r;
size_t size;
unsigned nr_left, nr_right;
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);
nr_left = le32_to_cpu(ln->header.nr_entries) / 2;
nr_right = le32_to_cpu(ln->header.nr_entries) - nr_left;
ln->header.nr_entries = cpu_to_le32(nr_left);
rn->header.flags = ln->header.flags;
rn->header.nr_entries = cpu_to_le32(nr_right);
rn->header.max_entries = ln->header.max_entries;
rn->header.value_size = ln->header.value_size;
memcpy(rn->keys, ln->keys + nr_left, nr_right * sizeof(rn->keys[0]));
size = le32_to_cpu(ln->header.flags) & INTERNAL_NODE ?
sizeof(uint64_t) : s->info->value_type.size;
memcpy(value_ptr(rn, 0), value_ptr(ln, nr_left),
size * nr_right);
/*
* Patch up the parent
*/
parent = shadow_parent(s);
pn = dm_block_data(parent);
location = cpu_to_le64(dm_block_location(left));
__dm_bless_for_disk(&location);
memcpy_disk(value_ptr(pn, parent_index),
&location, sizeof(__le64));
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)
return r;
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;
}
/*
* 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 nr_left, nr_right;
struct dm_block *left, *right, *new_parent;
struct btree_node *pn, *ln, *rn;
__le64 val;
new_parent = shadow_current(s);
r = new_block(s->info, &left);
if (r < 0)
return r;
r = new_block(s->info, &right);
if (r < 0) {
/* FIXME: put left */
return r;
}
pn = dm_block_data(new_parent);
ln = dm_block_data(left);
rn = dm_block_data(right);
nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
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;
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(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
sizeof(__le64) : s->info->value_type.size;
memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
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));
/*
* rejig the spine. This is ugly, since it knows too
* much about the spine
*/
if (s->nodes[0] != new_parent) {
unlock_block(s->info, s->nodes[0]);
s->nodes[0] = new_parent;
}
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;
}
s->count = 2;
return 0;
}
static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
struct dm_btree_value_type *vt,
uint64_t key, unsigned *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 (node->header.nr_entries == node->header.max_entries) {
if (top)
r = btree_split_beneath(s, key);
else
r = btree_split_sibling(s, root, i, key);
if (r < 0)
return r;
}
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 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, need_insert;
unsigned 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;
le64_type.context = NULL;
le64_type.size = sizeof(__le64);
le64_type.inc = NULL;
le64_type.dec = NULL;
le64_type.equal = NULL;
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));
need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) ||
(le64_to_cpu(n->keys[index]) != keys[level]));
if (need_insert) {
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));
need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) ||
(le64_to_cpu(n->keys[index]) != keys[level]));
if (need_insert) {
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));
}
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_highest_key(struct ro_spine *s, dm_block_t block,
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;
else
i--;
*result_key = le64_to_cpu(ro_node(s)->keys[i]);
if (next_block || flags & INTERNAL_NODE)
block = value64(ro_node(s), i);
} while (flags & INTERNAL_NODE);
if (next_block)
*next_block = block;
return 0;
}
int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
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_highest_key(&spine, root, 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;
}
EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);