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Commit be0e5c09 authored by Chris Mason's avatar Chris Mason Committed by David Woodhouse
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Btrfs: Initial checkin, basic working tree code 

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
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fs/btrfs/ctree.c 0 → 100644
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#include <stdio.h>
#include <stdlib.h>
#include "kerncompat.h"
#define BLOCKSIZE 4096
struct key {
u64 objectid;
u32 flags;
u64 offset;
} __attribute__ ((__packed__));
struct header {
u64 fsid[2]; /* FS specific uuid */
u64 blocknum;
u64 parentid;
u32 csum;
u32 ham;
u16 nritems;
u16 flags;
} __attribute__ ((__packed__));
#define NODEPTRS_PER_BLOCK ((BLOCKSIZE - sizeof(struct header)) / \
(sizeof(struct key) + sizeof(u64)))
#define LEVEL_BITS 3
#define MAX_LEVEL (1 << LEVEL_BITS)
#define node_level(f) ((f) & (MAX_LEVEL-1))
#define is_leaf(f) (node_level(f) == 0)
struct ctree_root {
struct node *node;
};
struct item {
struct key key;
u16 offset;
u16 size;
} __attribute__ ((__packed__));
#define LEAF_DATA_SIZE (BLOCKSIZE - sizeof(struct header))
struct leaf {
struct header header;
union {
struct item items[LEAF_DATA_SIZE/sizeof(struct item)];
u8 data[BLOCKSIZE-sizeof(struct header)];
};
} __attribute__ ((__packed__));
struct node {
struct header header;
struct key keys[NODEPTRS_PER_BLOCK];
u64 blockptrs[NODEPTRS_PER_BLOCK];
} __attribute__ ((__packed__));
struct ctree_path {
struct node *nodes[MAX_LEVEL];
int slots[MAX_LEVEL];
};
static inline void init_path(struct ctree_path *p)
{
memset(p, 0, sizeof(*p));
}
static inline unsigned int leaf_data_end(struct leaf *leaf)
{
unsigned int nr = leaf->header.nritems;
if (nr == 0)
return ARRAY_SIZE(leaf->data);
return leaf->items[nr-1].offset;
}
static inline int leaf_free_space(struct leaf *leaf)
{
int data_end = leaf_data_end(leaf);
int nritems = leaf->header.nritems;
char *items_end = (char *)(leaf->items + nritems + 1);
return (char *)(leaf->data + data_end) - (char *)items_end;
}
int comp_keys(struct key *k1, struct key *k2)
{
if (k1->objectid > k2->objectid)
return 1;
if (k1->objectid < k2->objectid)
return -1;
if (k1->flags > k2->flags)
return 1;
if (k1->flags < k2->flags)
return -1;
if (k1->offset > k2->offset)
return 1;
if (k1->offset < k2->offset)
return -1;
return 0;
}
int generic_bin_search(char *p, int item_size, struct key *key,
int max, int *slot)
{
int low = 0;
int high = max;
int mid;
int ret;
struct key *tmp;
while(low < high) {
mid = (low + high) / 2;
tmp = (struct key *)(p + mid * item_size);
ret = comp_keys(tmp, key);
if (ret < 0)
low = mid + 1;
else if (ret > 0)
high = mid;
else {
*slot = mid;
return 0;
}
}
*slot = low;
return 1;
}
int bin_search(struct node *c, struct key *key, int *slot)
{
if (is_leaf(c->header.flags)) {
struct leaf *l = (struct leaf *)c;
return generic_bin_search((void *)l->items, sizeof(struct item),
key, c->header.nritems, slot);
} else {
return generic_bin_search((void *)c->keys, sizeof(struct key),
key, c->header.nritems, slot);
}
return -1;
}
void *read_block(u64 blocknum)
{
return (void *)blocknum;
}
int search_slot(struct ctree_root *root, struct key *key, struct ctree_path *p)
{
struct node *c = root->node;
int slot;
int ret;
int level;
while (c) {
level = node_level(c->header.flags);
p->nodes[level] = c;
ret = bin_search(c, key, &slot);
if (!is_leaf(c->header.flags)) {
if (ret && slot > 0)
slot -= 1;
p->slots[level] = slot;
c = read_block(c->blockptrs[slot]);
continue;
} else {
p->slots[level] = slot;
return ret;
}
}
return -1;
}
static void fixup_low_keys(struct ctree_path *path, struct key *key,
int level)
{
int i;
/* adjust the pointers going up the tree */
for (i = level; i < MAX_LEVEL; i++) {
struct node *t = path->nodes[i];
int tslot = path->slots[i];
if (!t)
break;
memcpy(t->keys + tslot, key, sizeof(*key));
if (tslot != 0)
break;
}
}
int __insert_ptr(struct ctree_root *root,
struct ctree_path *path, struct key *key,
u64 blocknr, int slot, int level)
{
struct node *c;
struct node *lower;
struct key *lower_key;
int nritems;
/* need a new root */
if (!path->nodes[level]) {
c = malloc(sizeof(struct node));
memset(c, 0, sizeof(c));
c->header.nritems = 2;
c->header.flags = node_level(level);
lower = path->nodes[level-1];
if (is_leaf(lower->header.flags))
lower_key = &((struct leaf *)lower)->items[0].key;
else
lower_key = lower->keys;
memcpy(c->keys, lower_key, sizeof(struct key));
memcpy(c->keys + 1, key, sizeof(struct key));
c->blockptrs[0] = (u64)lower;
c->blockptrs[1] = blocknr;
root->node = c;
path->nodes[level] = c;
path->slots[level] = 0;
if (c->keys[1].objectid == 0)
BUG();
return 0;
}
lower = path->nodes[level];
nritems = lower->header.nritems;
if (slot > nritems)
BUG();
if (nritems == NODEPTRS_PER_BLOCK)
BUG();
if (slot != nritems) {
memmove(lower->keys + slot + 1, lower->keys + slot,
(nritems - slot) * sizeof(struct key));
memmove(lower->blockptrs + slot + 1, lower->blockptrs + slot,
(nritems - slot) * sizeof(u64));
}
memcpy(lower->keys + slot, key, sizeof(struct key));
lower->blockptrs[slot] = blocknr;
lower->header.nritems++;
if (lower->keys[1].objectid == 0)
BUG();
return 0;
}
int push_node_left(struct ctree_root *root, struct ctree_path *path, int level)
{
int slot;
struct node *left;
struct node *right;
int push_items = 0;
int left_nritems;
int right_nritems;
if (level == MAX_LEVEL - 1 || path->nodes[level + 1] == 0)
return 1;
slot = path->slots[level + 1];
if (slot == 0)
return 1;
left = read_block(path->nodes[level + 1]->blockptrs[slot - 1]);
right = path->nodes[level];
left_nritems = left->header.nritems;
right_nritems = right->header.nritems;
push_items = NODEPTRS_PER_BLOCK - (left_nritems + 1);
if (push_items <= 0)
return 1;
if (right_nritems < push_items)
push_items = right_nritems;
memcpy(left->keys + left_nritems, right->keys,
push_items * sizeof(struct key));
memcpy(left->blockptrs + left_nritems, right->blockptrs,
push_items * sizeof(u64));
memmove(right->keys, right->keys + push_items,
(right_nritems - push_items) * sizeof(struct key));
memmove(right->blockptrs, right->blockptrs + push_items,
(right_nritems - push_items) * sizeof(u64));
right->header.nritems -= push_items;
left->header.nritems += push_items;
/* adjust the pointers going up the tree */
fixup_low_keys(path, right->keys, level + 1);
/* then fixup the leaf pointer in the path */
if (path->slots[level] < push_items) {
path->slots[level] += left_nritems;
path->nodes[level] = (struct node*)left;
path->slots[level + 1] -= 1;
} else {
path->slots[level] -= push_items;
}
return 0;
}
int push_node_right(struct ctree_root *root, struct ctree_path *path, int level)
{
int slot;
struct node *dst;
struct node *src;
int push_items = 0;
int dst_nritems;
int src_nritems;
if (level == MAX_LEVEL - 1 || path->nodes[level + 1] == 0)
return 1;
slot = path->slots[level + 1];
if (slot == NODEPTRS_PER_BLOCK - 1)
return 1;
if (slot >= path->nodes[level + 1]->header.nritems -1)
return 1;
dst = read_block(path->nodes[level + 1]->blockptrs[slot + 1]);
src = path->nodes[level];
dst_nritems = dst->header.nritems;
src_nritems = src->header.nritems;
push_items = NODEPTRS_PER_BLOCK - (dst_nritems + 1);
if (push_items <= 0)
return 1;
if (src_nritems < push_items)
push_items = src_nritems;
memmove(dst->keys + push_items, dst->keys,
dst_nritems * sizeof(struct key));
memcpy(dst->keys, src->keys + src_nritems - push_items,
push_items * sizeof(struct key));
memmove(dst->blockptrs + push_items, dst->blockptrs,
dst_nritems * sizeof(u64));
memcpy(dst->blockptrs, src->blockptrs + src_nritems - push_items,
push_items * sizeof(u64));
src->header.nritems -= push_items;
dst->header.nritems += push_items;
/* adjust the pointers going up the tree */
memcpy(path->nodes[level + 1]->keys + path->slots[level + 1] + 1,
dst->keys, sizeof(struct key));
/* then fixup the leaf pointer in the path */
if (path->slots[level] >= src->header.nritems) {
path->slots[level] -= src->header.nritems;
path->nodes[level] = (struct node*)dst;
path->slots[level + 1] += 1;
}
return 0;
}
int insert_ptr(struct ctree_root *root,
struct ctree_path *path, struct key *key,
u64 blocknr, int level)
{
struct node *c = path->nodes[level];
struct node *b;
struct node *bal[MAX_LEVEL];
int bal_level = level;
int mid;
int bal_start = -1;
memset(bal, 0, ARRAY_SIZE(bal));
while(c && c->header.nritems == NODEPTRS_PER_BLOCK) {
if (push_node_left(root, path,
node_level(c->header.flags)) == 0)
break;
if (push_node_right(root, path,
node_level(c->header.flags)) == 0)
break;
bal_start = bal_level;
if (bal_level == MAX_LEVEL - 1)
BUG();
b = malloc(sizeof(struct node));
b->header.flags = c->header.flags;
mid = (c->header.nritems + 1) / 2;
memcpy(b->keys, c->keys + mid,
(c->header.nritems - mid) * sizeof(struct key));
memcpy(b->blockptrs, c->blockptrs + mid,
(c->header.nritems - mid) * sizeof(u64));
b->header.nritems = c->header.nritems - mid;
c->header.nritems = mid;
bal[bal_level] = b;
if (bal_level == MAX_LEVEL - 1)
break;
bal_level += 1;
c = path->nodes[bal_level];
}
while(bal_start > 0) {
b = bal[bal_start];
c = path->nodes[bal_start];
__insert_ptr(root, path, b->keys, (u64)b,
path->slots[bal_start + 1] + 1, bal_start + 1);
if (path->slots[bal_start] >= c->header.nritems) {
path->slots[bal_start] -= c->header.nritems;
path->nodes[bal_start] = b;
path->slots[bal_start + 1] += 1;
}
bal_start--;
if (!bal[bal_start])
break;
}
return __insert_ptr(root, path, key, blocknr, path->slots[level] + 1,
level);
}
int leaf_space_used(struct leaf *l, int start, int nr)
{
int data_len;
int end = start + nr - 1;
if (!nr)
return 0;
data_len = l->items[start].offset + l->items[start].size;
data_len = data_len - l->items[end].offset;
data_len += sizeof(struct item) * nr;
return data_len;
}
int push_leaf_left(struct ctree_root *root, struct ctree_path *path,
int data_size)
{
struct leaf *right = (struct leaf *)path->nodes[0];
struct leaf *left;
int slot;
int i;
int free_space;
int push_space = 0;
int push_items = 0;
struct item *item;
int old_left_nritems;
slot = path->slots[1];
if (slot == 0) {
return 1;
}
if (!path->nodes[1]) {
return 1;
}
left = read_block(path->nodes[1]->blockptrs[slot - 1]);
free_space = leaf_free_space(left);
if (free_space < data_size + sizeof(struct item)) {
return 1;
}
for (i = 0; i < right->header.nritems; i++) {
item = right->items + i;
if (path->slots[0] == i)
push_space += data_size + sizeof(*item);
if (item->size + sizeof(*item) + push_space > free_space)
break;
push_items++;
push_space += item->size + sizeof(*item);
}
if (push_items == 0) {
return 1;
}
/* push data from right to left */
memcpy(left->items + left->header.nritems,
right->items, push_items * sizeof(struct item));
push_space = LEAF_DATA_SIZE - right->items[push_items -1].offset;
memcpy(left->data + leaf_data_end(left) - push_space,
right->data + right->items[push_items - 1].offset,
push_space);
old_left_nritems = left->header.nritems;
for(i = old_left_nritems; i < old_left_nritems + push_items; i++) {
left->items[i].offset -= LEAF_DATA_SIZE -
left->items[old_left_nritems -1].offset;
}
left->header.nritems += push_items;
/* fixup right node */
push_space = right->items[push_items-1].offset - leaf_data_end(right);
memmove(right->data + LEAF_DATA_SIZE - push_space, right->data +
leaf_data_end(right), push_space);
memmove(right->items, right->items + push_items,
(right->header.nritems - push_items) * sizeof(struct item));
right->header.nritems -= push_items;
push_space = LEAF_DATA_SIZE;
for (i = 0; i < right->header.nritems; i++) {
right->items[i].offset = push_space - right->items[i].size;
push_space = right->items[i].offset;
}
fixup_low_keys(path, &right->items[0].key, 1);
/* then fixup the leaf pointer in the path */
if (path->slots[0] < push_items) {
path->slots[0] += old_left_nritems;
path->nodes[0] = (struct node*)left;
path->slots[1] -= 1;
} else {
path->slots[0] -= push_items;
}
return 0;
}
int split_leaf(struct ctree_root *root, struct ctree_path *path, int data_size)
{
struct leaf *l = (struct leaf *)path->nodes[0];
int nritems = l->header.nritems;
int mid = (nritems + 1)/ 2;
int slot = path->slots[0];
struct leaf *right;
int space_needed = data_size + sizeof(struct item);
int data_copy_size;
int rt_data_off;
int i;
int ret;
if (push_leaf_left(root, path, data_size) == 0) {
return 0;
}
right = malloc(sizeof(struct leaf));
memset(right, 0, sizeof(*right));
if (mid <= slot) {
if (leaf_space_used(l, mid, nritems - mid) + space_needed >
LEAF_DATA_SIZE)
BUG();
} else {
if (leaf_space_used(l, 0, mid + 1) + space_needed >
LEAF_DATA_SIZE)
BUG();
}
right->header.nritems = nritems - mid;
data_copy_size = l->items[mid].offset + l->items[mid].size -
leaf_data_end(l);
memcpy(right->items, l->items + mid,
(nritems - mid) * sizeof(struct item));
memcpy(right->data + LEAF_DATA_SIZE - data_copy_size,
l->data + leaf_data_end(l), data_copy_size);
rt_data_off = LEAF_DATA_SIZE -
(l->items[mid].offset + l->items[mid].size);
for (i = 0; i < right->header.nritems; i++) {
right->items[i].offset += rt_data_off;
}
l->header.nritems = mid;
ret = insert_ptr(root, path, &right->items[0].key,
(u64)right, 1);
if (mid <= slot) {
path->nodes[0] = (struct node *)right;
path->slots[0] -= mid;
path->slots[1] += 1;
}
return ret;
}
int insert_item(struct ctree_root *root, struct key *key,
void *data, int data_size)
{
int ret;
int slot;
struct leaf *leaf;
unsigned int nritems;
unsigned int data_end;
struct ctree_path path;
init_path(&path);
ret = search_slot(root, key, &path);
if (ret == 0)
return -EEXIST;
leaf = (struct leaf *)path.nodes[0];
if (leaf_free_space(leaf) < sizeof(struct item) + data_size)
split_leaf(root, &path, data_size);
leaf = (struct leaf *)path.nodes[0];
nritems = leaf->header.nritems;
data_end = leaf_data_end(leaf);
if (leaf_free_space(leaf) < sizeof(struct item) + data_size)
BUG();
slot = path.slots[0];
if (slot == 0)
fixup_low_keys(&path, key, 1);
if (slot != nritems) {
int i;
unsigned int old_data = leaf->items[slot].offset +
leaf->items[slot].size;
/*
* item0..itemN ... dataN.offset..dataN.size .. data0.size
*/
/* first correct the data pointers */
for (i = slot; i < nritems; i++)
leaf->items[i].offset -= data_size;
/* shift the items */
memmove(leaf->items + slot + 1, leaf->items + slot,
(nritems - slot) * sizeof(struct item));
/* shift the data */
memmove(leaf->data + data_end - data_size, leaf->data +
data_end, old_data - data_end);
data_end = old_data;
}
memcpy(&leaf->items[slot].key, key, sizeof(struct key));
leaf->items[slot].offset = data_end - data_size;
leaf->items[slot].size = data_size;
memcpy(leaf->data + data_end - data_size, data, data_size);
leaf->header.nritems += 1;
if (leaf_free_space(leaf) < 0)
BUG();
return 0;
}
int del_ptr(struct ctree_root *root, struct ctree_path *path, int level)
{
int slot;
struct node *node;
int nritems;
while(1) {
node = path->nodes[level];
if (!node)
break;
slot = path->slots[level];
nritems = node->header.nritems;
if (slot != nritems -1) {
memmove(node->keys + slot, node->keys + slot + 1,
sizeof(struct key) * (nritems - slot - 1));
memmove(node->blockptrs + slot,
node->blockptrs + slot + 1,
sizeof(u64) * (nritems - slot - 1));
}
node->header.nritems--;
if (node->header.nritems != 0) {
int tslot;
if (slot == 0)
fixup_low_keys(path, node->keys, level + 1);
tslot = path->slots[level+1];
push_node_left(root, path, level);
if (node->header.nritems) {
push_node_right(root, path, level);
}
path->slots[level+1] = tslot;
if (node->header.nritems)
break;
}
if (node == root->node) {
printf("root is now null!\n");
root->node = NULL;
break;
}
level++;
if (!path->nodes[level])
BUG();
free(node);
}
return 0;
}
int del_item(struct ctree_root *root, struct key *key)
{
int ret;
int slot;
struct leaf *leaf;
struct ctree_path path;
int doff;
int dsize;
init_path(&path);
ret = search_slot(root, key, &path);
if (ret != 0)
return -1;
leaf = (struct leaf *)path.nodes[0];
slot = path.slots[0];
doff = leaf->items[slot].offset;
dsize = leaf->items[slot].size;
if (slot != leaf->header.nritems - 1) {
int i;
int data_end = leaf_data_end(leaf);
memmove(leaf->data + data_end + dsize,
leaf->data + data_end,
doff - data_end);
for (i = slot + 1; i < leaf->header.nritems; i++)
leaf->items[i].offset += dsize;
memmove(leaf->items + slot, leaf->items + slot + 1,
sizeof(struct item) *
(leaf->header.nritems - slot - 1));
}
leaf->header.nritems -= 1;
if (leaf->header.nritems == 0) {
free(leaf);
del_ptr(root, &path, 1);
} else {
if (slot == 0)
fixup_low_keys(&path, &leaf->items[0].key, 1);
if (leaf_space_used(leaf, 0, leaf->header.nritems) <
LEAF_DATA_SIZE / 4) {
/* push_leaf_left fixes the path.
* make sure the path still points to our leaf
* for possible call to del_ptr below
*/
slot = path.slots[1];
push_leaf_left(root, &path, 1);
path.slots[1] = slot;
if (leaf->header.nritems == 0) {
free(leaf);
del_ptr(root, &path, 1);
}
}
}
return 0;
}
void print_leaf(struct leaf *l)
{
int i;
int nr = l->header.nritems;
struct item *item;
printf("leaf %p total ptrs %d free space %d\n", l, nr,
leaf_free_space(l));
fflush(stdout);
for (i = 0 ; i < nr ; i++) {
item = l->items + i;
printf("\titem %d key (%lu %u %lu) itemoff %d itemsize %d\n",
i,
item->key.objectid, item->key.flags, item->key.offset,
item->offset, item->size);
fflush(stdout);
printf("\t\titem data %.*s\n", item->size, l->data+item->offset);
fflush(stdout);
}
}
void print_tree(struct node *c)
{
int i;
int nr;
if (!c)
return;
nr = c->header.nritems;
if (is_leaf(c->header.flags)) {
print_leaf((struct leaf *)c);
return;
}
printf("node %p level %d total ptrs %d free spc %lu\n", c,
node_level(c->header.flags), c->header.nritems,
NODEPTRS_PER_BLOCK - c->header.nritems);
fflush(stdout);
for (i = 0; i < nr; i++) {
printf("\tkey %d (%lu %u %lu) block %lx\n",
i,
c->keys[i].objectid, c->keys[i].flags, c->keys[i].offset,
c->blockptrs[i]);
fflush(stdout);
}
for (i = 0; i < nr; i++) {
struct node *next = read_block(c->blockptrs[i]);
if (is_leaf(next->header.flags) &&
node_level(c->header.flags) != 1)
BUG();
if (node_level(next->header.flags) !=
node_level(c->header.flags) - 1)
BUG();
print_tree(next);
}
}
/* for testing only */
int next_key(int i, int max_key) {
return rand() % max_key;
// return i;
}
int main() {
struct leaf *first_node = malloc(sizeof(struct leaf));
struct ctree_root root;
struct key ins;
char *buf;
int i;
int num;
int ret;
int run_size = 10000000;
int max_key = 100000000;
int tree_size = 0;
struct ctree_path path;
srand(55);
root.node = (struct node *)first_node;
memset(first_node, 0, sizeof(*first_node));
for (i = 0; i < run_size; i++) {
buf = malloc(64);
num = next_key(i, max_key);
// num = i;
sprintf(buf, "string-%d", num);
// printf("insert %d\n", num);
ins.objectid = num;
ins.offset = 0;
ins.flags = 0;
ret = insert_item(&root, &ins, buf, strlen(buf));
if (!ret)
tree_size++;
}
srand(55);
for (i = 0; i < run_size; i++) {
num = next_key(i, max_key);
ins.objectid = num;
ins.offset = 0;
ins.flags = 0;
init_path(&path);
ret = search_slot(&root, &ins, &path);
if (ret) {
print_tree(root.node);
printf("unable to find %d\n", num);
exit(1);
}
}
printf("node %p level %d total ptrs %d free spc %lu\n", root.node,
node_level(root.node->header.flags), root.node->header.nritems,
NODEPTRS_PER_BLOCK - root.node->header.nritems);
// print_tree(root.node);
printf("all searches good\n");
i = 0;
srand(55);
for (i = 0; i < run_size; i++) {
num = next_key(i, max_key);
ins.objectid = num;
del_item(&root, &ins);
}
print_tree(root.node);
return 0;
}
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