linux/fs/btrfs/ctree.c

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C
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#include <stdio.h>
#include <stdlib.h>
#include "kerncompat.h"
#include "radix-tree.h"
#include "ctree.h"
#include "disk-io.h"
#include "print-tree.h"
int split_node(struct ctree_root *root, struct ctree_path *path, int level);
int split_leaf(struct ctree_root *root, struct ctree_path *path, int data_size);
int push_node_left(struct ctree_root *root, struct ctree_path *path, int level);
int push_node_right(struct ctree_root *root,
struct ctree_path *path, int level);
int del_ptr(struct ctree_root *root, struct ctree_path *path, int level);
inline void init_path(struct ctree_path *p)
{
memset(p, 0, sizeof(*p));
}
void release_path(struct ctree_root *root, struct ctree_path *p)
{
int i;
for (i = 0; i < MAX_LEVEL; i++) {
if (!p->nodes[i])
break;
tree_block_release(root, p->nodes[i]);
}
}
/*
* The leaf data grows from end-to-front in the node.
* this returns the address of the start of the last item,
* which is the stop of the leaf data stack
*/
static inline unsigned int leaf_data_end(struct leaf *leaf)
{
unsigned int nr = leaf->header.nritems;
if (nr == 0)
return sizeof(leaf->data);
return leaf->items[nr-1].offset;
}
/*
* The space between the end of the leaf items and
* the start of the leaf data. IOW, how much room
* the leaf has left for both items and data
*/
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;
}
/*
* compare two keys in a memcmp fashion
*/
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;
}
/*
* search for key in the array p. items p are item_size apart
* and there are 'max' items in p
* the slot in the array is returned via slot, and it points to
* the place where you would insert key if it is not found in
* the array.
*
* slot may point to max if the key is bigger than all of the keys
*/
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;
}
/*
* simple bin_search frontend that does the right thing for
* leaves vs nodes
*/
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;
}
/*
* look for key in the tree. path is filled in with nodes along the way
* if key is found, we return zero and you can find the item in the leaf
* level of the path (level 0)
*
* If the key isn't found, the path points to the slot where it should
* be inserted.
*
* if ins_len > 0, nodes and leaves will be split as we walk down the
* tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
* possible)
*/
int search_slot(struct ctree_root *root, struct key *key,
struct ctree_path *p, int ins_len)
{
struct tree_buffer *b = root->node;
struct node *c;
int slot;
int ret;
int level;
b->count++;
while (b) {
c = &b->node;
level = node_level(c->header.flags);
p->nodes[level] = b;
ret = bin_search(c, key, &slot);
if (!is_leaf(c->header.flags)) {
if (ret && slot > 0)
slot -= 1;
p->slots[level] = slot;
if (ins_len > 0 &&
c->header.nritems == NODEPTRS_PER_BLOCK) {
int sret = split_node(root, p, level);
BUG_ON(sret > 0);
if (sret)
return sret;
b = p->nodes[level];
c = &b->node;
slot = p->slots[level];
}
b = read_tree_block(root, c->blockptrs[slot]);
continue;
} else {
struct leaf *l = (struct leaf *)c;
p->slots[level] = slot;
if (ins_len > 0 && leaf_free_space(l) <
sizeof(struct item) + ins_len) {
int sret = split_leaf(root, p, ins_len);
BUG_ON(sret > 0);
if (sret)
return sret;
}
return ret;
}
}
return -1;
}
/*
* adjust the pointers going up the tree, starting at level
* making sure the right key of each node is points to 'key'.
* This is used after shifting pointers to the left, so it stops
* fixing up pointers when a given leaf/node is not in slot 0 of the
* higher levels
*/
static void fixup_low_keys(struct ctree_root *root,
struct ctree_path *path, struct key *key,
int level)
{
int i;
for (i = level; i < MAX_LEVEL; i++) {
struct node *t;
int tslot = path->slots[i];
if (!path->nodes[i])
break;
t = &path->nodes[i]->node;
memcpy(t->keys + tslot, key, sizeof(*key));
write_tree_block(root, path->nodes[i]);
if (tslot != 0)
break;
}
}
/*
* try to push data from one node into the next node left in the
* tree. The src node is found at specified level in the path.
* If some bytes were pushed, return 0, otherwise return 1.
*
* Lower nodes/leaves in the path are not touched, higher nodes may
* be modified to reflect the push.
*
* The path is altered to reflect the push.
*/
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;
struct tree_buffer *t;
struct tree_buffer *right_buf;
if (level == MAX_LEVEL - 1 || path->nodes[level + 1] == 0)
return 1;
slot = path->slots[level + 1];
if (slot == 0)
return 1;
t = read_tree_block(root,
path->nodes[level + 1]->node.blockptrs[slot - 1]);
left = &t->node;
right_buf = path->nodes[level];
right = &right_buf->node;
left_nritems = left->header.nritems;
right_nritems = right->header.nritems;
push_items = NODEPTRS_PER_BLOCK - (left_nritems + 1);
if (push_items <= 0) {
tree_block_release(root, t);
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(root, path, right->keys, level + 1);
write_tree_block(root, t);
write_tree_block(root, right_buf);
/* then fixup the leaf pointer in the path */
if (path->slots[level] < push_items) {
path->slots[level] += left_nritems;
tree_block_release(root, path->nodes[level]);
path->nodes[level] = t;
path->slots[level + 1] -= 1;
} else {
path->slots[level] -= push_items;
tree_block_release(root, t);
}
return 0;
}
/*
* try to push data from one node into the next node right in the
* tree. The src node is found at specified level in the path.
* If some bytes were pushed, return 0, otherwise return 1.
*
* Lower nodes/leaves in the path are not touched, higher nodes may
* be modified to reflect the push.
*
* The path is altered to reflect the push.
*/
int push_node_right(struct ctree_root *root, struct ctree_path *path, int level)
{
int slot;
struct tree_buffer *t;
struct tree_buffer *src_buffer;
struct node *dst;
struct node *src;
int push_items = 0;
int dst_nritems;
int src_nritems;
/* can't push from the root */
if (level == MAX_LEVEL - 1 || path->nodes[level + 1] == 0)
return 1;
/* only try to push inside the node higher up */
slot = path->slots[level + 1];
if (slot == NODEPTRS_PER_BLOCK - 1)
return 1;
if (slot >= path->nodes[level + 1]->node.header.nritems -1)
return 1;
t = read_tree_block(root,
path->nodes[level + 1]->node.blockptrs[slot + 1]);
dst = &t->node;
src_buffer = path->nodes[level];
src = &src_buffer->node;
dst_nritems = dst->header.nritems;
src_nritems = src->header.nritems;
push_items = NODEPTRS_PER_BLOCK - (dst_nritems + 1);
if (push_items <= 0) {
tree_block_release(root, t);
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]->node.keys + path->slots[level + 1] + 1,
dst->keys, sizeof(struct key));
write_tree_block(root, path->nodes[level + 1]);
write_tree_block(root, t);
write_tree_block(root, src_buffer);
/* then fixup the pointers in the path */
if (path->slots[level] >= src->header.nritems) {
path->slots[level] -= src->header.nritems;
tree_block_release(root, path->nodes[level]);
path->nodes[level] = t;
path->slots[level + 1] += 1;
} else {
tree_block_release(root, t);
}
return 0;
}
/*
* helper function to insert a new root level in the tree.
* A new node is allocated, and a single item is inserted to
* point to the existing root
*/
static int insert_new_root(struct ctree_root *root,
struct ctree_path *path, int level)
{
struct tree_buffer *t;
struct node *lower;
struct node *c;
struct key *lower_key;
BUG_ON(path->nodes[level]);
BUG_ON(path->nodes[level-1] != root->node);
t = alloc_free_block(root);
c = &t->node;
memset(c, 0, sizeof(c));
c->header.nritems = 1;
c->header.flags = node_level(level);
c->header.blocknr = t->blocknr;
c->header.parentid = root->node->node.header.parentid;
lower = &path->nodes[level-1]->node;
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));
c->blockptrs[0] = path->nodes[level-1]->blocknr;
/* the super has an extra ref to root->node */
tree_block_release(root, root->node);
root->node = t;
t->count++;
write_tree_block(root, t);
path->nodes[level] = t;
path->slots[level] = 0;
return 0;
}
/*
* worker function to insert a single pointer in a node.
* the node should have enough room for the pointer already
*
* slot and level indicate where you want the key to go, and
* blocknr is the block the key points to.
*/
int insert_ptr(struct ctree_root *root,
struct ctree_path *path, struct key *key,
u64 blocknr, int slot, int level)
{
struct node *lower;
int nritems;
BUG_ON(!path->nodes[level]);
lower = &path->nodes[level]->node;
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();
write_tree_block(root, path->nodes[level]);
return 0;
}
/*
* split the node at the specified level in path in two.
* The path is corrected to point to the appropriate node after the split
*
* Before splitting this tries to make some room in the node by pushing
* left and right, if either one works, it returns right away.
*/
int split_node(struct ctree_root *root, struct ctree_path *path, int level)
{
struct tree_buffer *t;
struct node *c;
struct tree_buffer *split_buffer;
struct node *split;
int mid;
int ret;
ret = push_node_left(root, path, level);
if (!ret)
return 0;
ret = push_node_right(root, path, level);
if (!ret)
return 0;
t = path->nodes[level];
c = &t->node;
if (t == root->node) {
/* trying to split the root, lets make a new one */
ret = insert_new_root(root, path, level + 1);
if (ret)
return ret;
}
split_buffer = alloc_free_block(root);
split = &split_buffer->node;
split->header.flags = c->header.flags;
split->header.blocknr = split_buffer->blocknr;
split->header.parentid = root->node->node.header.parentid;
mid = (c->header.nritems + 1) / 2;
memcpy(split->keys, c->keys + mid,
(c->header.nritems - mid) * sizeof(struct key));
memcpy(split->blockptrs, c->blockptrs + mid,
(c->header.nritems - mid) * sizeof(u64));
split->header.nritems = c->header.nritems - mid;
c->header.nritems = mid;
write_tree_block(root, t);
write_tree_block(root, split_buffer);
insert_ptr(root, path, split->keys, split_buffer->blocknr,
path->slots[level + 1] + 1, level + 1);
if (path->slots[level] >= mid) {
path->slots[level] -= mid;
tree_block_release(root, t);
path->nodes[level] = split_buffer;
path->slots[level + 1] += 1;
} else {
tree_block_release(root, split_buffer);
}
return 0;
}
/*
* how many bytes are required to store the items in a leaf. start
* and nr indicate which items in the leaf to check. This totals up the
* space used both by the item structs and the item data
*/
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;
}
/*
* push some data in the path leaf to the right, trying to free up at
* least data_size bytes. returns zero if the push worked, nonzero otherwise
*/
int push_leaf_right(struct ctree_root *root, struct ctree_path *path,
int data_size)
{
struct tree_buffer *left_buf = path->nodes[0];
struct leaf *left = &left_buf->leaf;
struct leaf *right;
struct tree_buffer *right_buf;
struct tree_buffer *upper;
int slot;
int i;
int free_space;
int push_space = 0;
int push_items = 0;
struct item *item;
slot = path->slots[1];
if (!path->nodes[1]) {
return 1;
}
upper = path->nodes[1];
if (slot >= upper->node.header.nritems - 1) {
return 1;
}
right_buf = read_tree_block(root, upper->node.blockptrs[slot + 1]);
right = &right_buf->leaf;
free_space = leaf_free_space(right);
if (free_space < data_size + sizeof(struct item)) {
tree_block_release(root, right_buf);
return 1;
}
for (i = left->header.nritems - 1; i >= 0; i--) {
item = left->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) {
tree_block_release(root, right_buf);
return 1;
}
/* push left to right */
push_space = left->items[left->header.nritems - push_items].offset +
left->items[left->header.nritems - push_items].size;
push_space -= leaf_data_end(left);
/* make room in the right data area */
memmove(right->data + leaf_data_end(right) - push_space,
right->data + leaf_data_end(right),
LEAF_DATA_SIZE - leaf_data_end(right));
/* copy from the left data area */
memcpy(right->data + LEAF_DATA_SIZE - push_space,
left->data + leaf_data_end(left),
push_space);
memmove(right->items + push_items, right->items,
right->header.nritems * sizeof(struct item));
/* copy the items from left to right */
memcpy(right->items, left->items + left->header.nritems - push_items,
push_items * sizeof(struct item));
/* update the item pointers */
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;
}
left->header.nritems -= push_items;
write_tree_block(root, left_buf);
write_tree_block(root, right_buf);
memcpy(upper->node.keys + slot + 1,
&right->items[0].key, sizeof(struct key));
write_tree_block(root, upper);
/* then fixup the leaf pointer in the path */
if (path->slots[0] >= left->header.nritems) {
path->slots[0] -= left->header.nritems;
tree_block_release(root, path->nodes[0]);
path->nodes[0] = right_buf;
path->slots[1] += 1;
} else {
tree_block_release(root, right_buf);
}
return 0;
}
/*
* push some data in the path leaf to the left, trying to free up at
* least data_size bytes. returns zero if the push worked, nonzero otherwise
*/
int push_leaf_left(struct ctree_root *root, struct ctree_path *path,
int data_size)
{
struct tree_buffer *right_buf = path->nodes[0];
struct leaf *right = &right_buf->leaf;
struct tree_buffer *t;
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;
}
t = read_tree_block(root, path->nodes[1]->node.blockptrs[slot - 1]);
left = &t->leaf;
free_space = leaf_free_space(left);
if (free_space < data_size + sizeof(struct item)) {
tree_block_release(root, t);
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) {
tree_block_release(root, t);
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;
BUG_ON(old_left_nritems < 0);
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;
}
write_tree_block(root, t);
write_tree_block(root, right_buf);
fixup_low_keys(root, 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;
tree_block_release(root, path->nodes[0]);
path->nodes[0] = t;
path->slots[1] -= 1;
} else {
tree_block_release(root, t);
path->slots[0] -= push_items;
}
BUG_ON(path->slots[0] < 0);
return 0;
}
/*
* split the path's leaf in two, making sure there is at least data_size
* available for the resulting leaf level of the path.
*/
int split_leaf(struct ctree_root *root, struct ctree_path *path, int data_size)
{
struct tree_buffer *l_buf = path->nodes[0];
struct leaf *l = &l_buf->leaf;
int nritems;
int mid;
int slot;
struct leaf *right;
struct tree_buffer *right_buffer;
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 ||
push_leaf_right(root, path, data_size) == 0) {
l_buf = path->nodes[0];
l = &l_buf->leaf;
if (leaf_free_space(l) >= sizeof(struct item) + data_size)
return 0;
}
if (!path->nodes[1]) {
ret = insert_new_root(root, path, 1);
if (ret)
return ret;
}
slot = path->slots[0];
nritems = l->header.nritems;
mid = (nritems + 1)/ 2;
right_buffer = alloc_free_block(root);
BUG_ON(!right_buffer);
BUG_ON(mid == nritems);
right = &right_buffer->leaf;
memset(right, 0, sizeof(*right));
if (mid <= slot) {
/* FIXME, just alloc a new leaf here */
if (leaf_space_used(l, mid, nritems - mid) + space_needed >
LEAF_DATA_SIZE)
BUG();
} else {
/* FIXME, just alloc a new leaf here */
if (leaf_space_used(l, 0, mid + 1) + space_needed >
LEAF_DATA_SIZE)
BUG();
}
right->header.nritems = nritems - mid;
right->header.blocknr = right_buffer->blocknr;
right->header.flags = node_level(0);
right->header.parentid = root->node->node.header.parentid;
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,
right_buffer->blocknr, path->slots[1] + 1, 1);
write_tree_block(root, right_buffer);
write_tree_block(root, l_buf);
BUG_ON(path->slots[0] != slot);
if (mid <= slot) {
tree_block_release(root, path->nodes[0]);
path->nodes[0] = right_buffer;
path->slots[0] -= mid;
path->slots[1] += 1;
} else
tree_block_release(root, right_buffer);
BUG_ON(path->slots[0] < 0);
return ret;
}
/*
* Given a key and some data, insert an item into the tree.
* This does all the path init required, making room in the tree if needed.
*/
int insert_item(struct ctree_root *root, struct key *key,
void *data, int data_size)
{
int ret;
int slot;
int slot_orig;
struct leaf *leaf;
struct tree_buffer *leaf_buf;
unsigned int nritems;
unsigned int data_end;
struct ctree_path path;
/* create a root if there isn't one */
if (!root->node)
BUG();
init_path(&path);
ret = search_slot(root, key, &path, data_size);
if (ret == 0) {
release_path(root, &path);
return -EEXIST;
}
slot_orig = path.slots[0];
leaf_buf = path.nodes[0];
leaf = &leaf_buf->leaf;
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];
BUG_ON(slot < 0);
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;
}
/* copy the new data in */
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;
write_tree_block(root, leaf_buf);
if (slot == 0)
fixup_low_keys(root, &path, key, 1);
if (leaf_free_space(leaf) < 0)
BUG();
release_path(root, &path);
return 0;
}
/*
* delete the pointer from a given node.
*
* If the delete empties a node, the node is removed from the tree,
* continuing all the way the root if required. The root is converted into
* a leaf if all the nodes are emptied.
*/
int del_ptr(struct ctree_root *root, struct ctree_path *path, int level)
{
int slot;
struct tree_buffer *t;
struct node *node;
int nritems;
u64 blocknr;
while(1) {
t = path->nodes[level];
if (!t)
break;
node = &t->node;
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--;
blocknr = t->blocknr;
write_tree_block(root, t);
if (node->header.nritems != 0) {
int tslot;
if (slot == 0)
fixup_low_keys(root, path, node->keys,
level + 1);
tslot = path->slots[level + 1];
t->count++;
if (push_node_left(root, path, level))
push_node_right(root, path, level);
path->slots[level + 1] = tslot;
if (node->header.nritems != 0) {
tree_block_release(root, t);
break;
}
tree_block_release(root, t);
}
if (t == root->node) {
/* just turn the root into a leaf and break */
root->node->node.header.flags = node_level(0);
write_tree_block(root, t);
break;
}
level++;
free_extent(root, blocknr, 1);
if (!path->nodes[level])
BUG();
}
return 0;
}
/*
* delete the item at the leaf level in path. If that empties
* the leaf, remove it from the tree
*/
int del_item(struct ctree_root *root, struct ctree_path *path)
{
int slot;
struct leaf *leaf;
struct tree_buffer *leaf_buf;
int doff;
int dsize;
leaf_buf = path->nodes[0];
leaf = &leaf_buf->leaf;
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;
/* delete the leaf if we've emptied it */
if (leaf->header.nritems == 0) {
if (leaf_buf == root->node) {
leaf->header.flags = node_level(0);
write_tree_block(root, leaf_buf);
} else {
del_ptr(root, path, 1);
free_extent(root, leaf_buf->blocknr, 1);
}
} else {
int used = leaf_space_used(leaf, 0, leaf->header.nritems);
if (slot == 0)
fixup_low_keys(root, path, &leaf->items[0].key, 1);
write_tree_block(root, leaf_buf);
/* delete the leaf if it is mostly empty */
if (used < LEAF_DATA_SIZE / 3) {
/* 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];
leaf_buf->count++;
push_leaf_left(root, path, 1);
if (leaf->header.nritems)
push_leaf_right(root, path, 1);
if (leaf->header.nritems == 0) {
u64 blocknr = leaf_buf->blocknr;
path->slots[1] = slot;
del_ptr(root, path, 1);
tree_block_release(root, leaf_buf);
free_extent(root, blocknr, 1);
} else {
tree_block_release(root, leaf_buf);
}
}
}
return 0;
}
/*
* walk up the tree as far as required to find the next leaf.
* returns 0 if it found something or -1 if there are no greater leaves.
*/
int next_leaf(struct ctree_root *root, struct ctree_path *path)
{
int slot;
int level = 1;
u64 blocknr;
struct tree_buffer *c;
struct tree_buffer *next = NULL;
while(level < MAX_LEVEL) {
if (!path->nodes[level])
return -1;
slot = path->slots[level] + 1;
c = path->nodes[level];
if (slot >= c->node.header.nritems) {
level++;
continue;
}
blocknr = c->node.blockptrs[slot];
if (next)
tree_block_release(root, next);
next = read_tree_block(root, blocknr);
break;
}
path->slots[level] = slot;
while(1) {
level--;
c = path->nodes[level];
tree_block_release(root, c);
path->nodes[level] = next;
path->slots[level] = 0;
if (!level)
break;
next = read_tree_block(root, next->node.blockptrs[0]);
}
return 0;
}
/* some sample code to insert,search & delete items */
#if 0
/* for testing only */
int next_key(int i, int max_key) {
return rand() % max_key;
//return i;
}
int main() {
struct key ins;
struct key last = { (u64)-1, 0, 0};
char *buf;
int i;
int num;
int ret;
int run_size = 20000000;
int max_key = 100000000;
int tree_size = 0;
struct ctree_path path;
struct ctree_super_block super;
struct ctree_root *root;
radix_tree_init();
root = open_ctree("dbfile", &super);
srand(55);
for (i = 0; i < run_size; i++) {
buf = malloc(64);
num = next_key(i, max_key);
// num = i;
sprintf(buf, "string-%d", num);
if (i % 10000 == 0)
fprintf(stderr, "insert %d:%d\n", num, i);
ins.objectid = num;
ins.offset = 0;
ins.flags = 0;
ret = insert_item(root, &ins, buf, strlen(buf));
if (!ret)
tree_size++;
free(buf);
}
write_ctree_super(root, &super);
close_ctree(root);
root = open_ctree("dbfile", &super);
printf("starting search\n");
srand(55);
for (i = 0; i < run_size; i++) {
num = next_key(i, max_key);
ins.objectid = num;
init_path(&path);
if (i % 10000 == 0)
fprintf(stderr, "search %d:%d\n", num, i);
ret = search_slot(root, &ins, &path, 0);
if (ret) {
print_tree(root, root->node);
printf("unable to find %d\n", num);
exit(1);
}
release_path(root, &path);
}
write_ctree_super(root, &super);
close_ctree(root);
root = open_ctree("dbfile", &super);
printf("node %p level %d total ptrs %d free spc %lu\n", root->node,
node_level(root->node->node.header.flags),
root->node->node.header.nritems,
NODEPTRS_PER_BLOCK - root->node->node.header.nritems);
printf("all searches good, deleting some items\n");
i = 0;
srand(55);
for (i = 0 ; i < run_size/4; i++) {
num = next_key(i, max_key);
ins.objectid = num;
init_path(&path);
ret = search_slot(root, &ins, &path, -1);
if (!ret) {
if (i % 10000 == 0)
fprintf(stderr, "del %d:%d\n", num, i);
ret = del_item(root, &path);
if (ret != 0)
BUG();
tree_size--;
}
release_path(root, &path);
}
write_ctree_super(root, &super);
close_ctree(root);
root = open_ctree("dbfile", &super);
srand(128);
for (i = 0; i < run_size; i++) {
buf = malloc(64);
num = next_key(i, max_key);
sprintf(buf, "string-%d", num);
ins.objectid = num;
if (i % 10000 == 0)
fprintf(stderr, "insert %d:%d\n", num, i);
ret = insert_item(root, &ins, buf, strlen(buf));
if (!ret)
tree_size++;
free(buf);
}
write_ctree_super(root, &super);
close_ctree(root);
root = open_ctree("dbfile", &super);
srand(128);
printf("starting search2\n");
for (i = 0; i < run_size; i++) {
num = next_key(i, max_key);
ins.objectid = num;
init_path(&path);
if (i % 10000 == 0)
fprintf(stderr, "search %d:%d\n", num, i);
ret = search_slot(root, &ins, &path, 0);
if (ret) {
print_tree(root, root->node);
printf("unable to find %d\n", num);
exit(1);
}
release_path(root, &path);
}
printf("starting big long delete run\n");
while(root->node && root->node->node.header.nritems > 0) {
struct leaf *leaf;
int slot;
ins.objectid = (u64)-1;
init_path(&path);
ret = search_slot(root, &ins, &path, -1);
if (ret == 0)
BUG();
leaf = &path.nodes[0]->leaf;
slot = path.slots[0];
if (slot != leaf->header.nritems)
BUG();
while(path.slots[0] > 0) {
path.slots[0] -= 1;
slot = path.slots[0];
leaf = &path.nodes[0]->leaf;
if (comp_keys(&last, &leaf->items[slot].key) <= 0)
BUG();
memcpy(&last, &leaf->items[slot].key, sizeof(last));
if (tree_size % 10000 == 0)
printf("big del %d:%d\n", tree_size, i);
ret = del_item(root, &path);
if (ret != 0) {
printf("del_item returned %d\n", ret);
BUG();
}
tree_size--;
}
release_path(root, &path);
}
printf("tree size is now %d\n", tree_size);
printf("map tree\n");
print_tree(root->extent_root, root->extent_root->node);
write_ctree_super(root, &super);
close_ctree(root);
return 0;
}
#endif