#include <stdio.h>
#include <stdlib.h>
#include "kerncompat.h"
#include "radix-tree.h"
#include "ctree.h"
#include "disk-io.h"
#include "print-tree.h"
static int split_node(struct ctree_root *root, struct ctree_path *path,
int level);
static int split_leaf(struct ctree_root *root, struct ctree_path *path,
int data_size);
static int push_node_left(struct ctree_root *root, struct tree_buffer *dst,
struct tree_buffer *src);
static int balance_node_right(struct ctree_root *root,
struct tree_buffer *dst_buf,
struct tree_buffer *src_buf);
static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level,
int slot);
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]);
}
memset(p, 0, sizeof(*p));
}
int btrfs_cow_block(struct ctree_root *root,
struct tree_buffer *buf,
struct tree_buffer *parent,
int parent_slot,
struct tree_buffer **cow_ret)
{
struct tree_buffer *cow;
if (!list_empty(&buf->dirty)) {
*cow_ret = buf;
return 0;
}
cow = alloc_free_block(root);
memcpy(&cow->node, &buf->node, sizeof(buf->node));
btrfs_set_header_blocknr(&cow->node.header, cow->blocknr);
*cow_ret = cow;
btrfs_inc_ref(root, buf);
if (buf == root->node) {
root->node = cow;
cow->count++;
if (buf != root->commit_root)
free_extent(root, buf->blocknr, 1);
tree_block_release(root, buf);
} else {
parent->node.blockptrs[parent_slot] = cow->blocknr;
BUG_ON(list_empty(&parent->dirty));
free_extent(root, buf->blocknr, 1);
}
tree_block_release(root, buf);
return 0;
}
/*
* 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)
{
u32 nr = btrfs_header_nritems(&leaf->header);
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 = btrfs_header_nritems(&leaf->header);
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 btrfs_disk_key *disk, struct btrfs_key *k2)
{
struct btrfs_key k1;
btrfs_disk_key_to_cpu(&k1, disk);
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 check_node(struct ctree_path *path, int level)
{
int i;
struct node *parent = NULL;
struct node *node = &path->nodes[level]->node;
int parent_slot;
u32 nritems = btrfs_header_nritems(&node->header);
if (path->nodes[level + 1])
parent = &path->nodes[level + 1]->node;
parent_slot = path->slots[level + 1];
BUG_ON(nritems == 0);
if (parent) {
struct btrfs_disk_key *parent_key;
parent_key = &parent->keys[parent_slot];
BUG_ON(memcmp(parent_key, node->keys,
sizeof(struct btrfs_disk_key)));
BUG_ON(parent->blockptrs[parent_slot] !=
btrfs_header_blocknr(&node->header));
}
BUG_ON(nritems > NODEPTRS_PER_BLOCK);
for (i = 0; nritems > 1 && i < nritems - 2; i++) {
struct btrfs_key cpukey;
btrfs_disk_key_to_cpu(&cpukey, &node->keys[i + 1]);
BUG_ON(comp_keys(&node->keys[i], &cpukey) >= 0);
}
return 0;
}
int check_leaf(struct ctree_path *path, int level)
{
int i;
struct leaf *leaf = &path->nodes[level]->leaf;
struct node *parent = NULL;
int parent_slot;
u32 nritems = btrfs_header_nritems(&leaf->header);
if (path->nodes[level + 1])
parent = &path->nodes[level + 1]->node;
parent_slot = path->slots[level + 1];
BUG_ON(leaf_free_space(leaf) < 0);
if (nritems == 0)
return 0;
if (parent) {
struct btrfs_disk_key *parent_key;
parent_key = &parent->keys[parent_slot];
BUG_ON(memcmp(parent_key, &leaf->items[0].key,
sizeof(struct btrfs_disk_key)));
BUG_ON(parent->blockptrs[parent_slot] !=
btrfs_header_blocknr(&leaf->header));
}
for (i = 0; nritems > 1 && i < nritems - 2; i++) {
struct btrfs_key cpukey;
btrfs_disk_key_to_cpu(&cpukey, &leaf->items[i + 1].key);
BUG_ON(comp_keys(&leaf->items[i].key,
&cpukey) >= 0);
BUG_ON(leaf->items[i].offset != leaf->items[i + 1].offset +
leaf->items[i + 1].size);
if (i == 0) {
BUG_ON(leaf->items[i].offset + leaf->items[i].size !=
LEAF_DATA_SIZE);
}
}
return 0;
}
int check_block(struct ctree_path *path, int level)
{
if (level == 0)
return check_leaf(path, level);
return check_node(path, level);
}
/*
* 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 btrfs_key *key,
int max, int *slot)
{
int low = 0;
int high = max;
int mid;
int ret;
struct btrfs_disk_key *tmp;
while(low < high) {
mid = (low + high) / 2;
tmp = (struct btrfs_disk_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 btrfs_key *key, int *slot)
{
if (btrfs_is_leaf(c)) {
struct leaf *l = (struct leaf *)c;
return generic_bin_search((void *)l->items, sizeof(struct item),
key, btrfs_header_nritems(&c->header),
slot);
} else {
return generic_bin_search((void *)c->keys,
sizeof(struct btrfs_disk_key),
key, btrfs_header_nritems(&c->header),
slot);
}
return -1;
}
struct tree_buffer *read_node_slot(struct ctree_root *root,
struct tree_buffer *parent_buf,
int slot)
{
struct node *node = &parent_buf->node;
if (slot < 0)
return NULL;
if (slot >= btrfs_header_nritems(&node->header))
return NULL;
return read_tree_block(root, node->blockptrs[slot]);
}
static int balance_level(struct ctree_root *root, struct ctree_path *path,
int level)
{
struct tree_buffer *right_buf;
struct tree_buffer *mid_buf;
struct tree_buffer *left_buf;
struct tree_buffer *parent_buf = NULL;
struct node *right = NULL;
struct node *mid;
struct node *left = NULL;
struct node *parent = NULL;
int ret = 0;
int wret;
int pslot;
int orig_slot = path->slots[level];
u64 orig_ptr;
if (level == 0)
return 0;
mid_buf = path->nodes[level];
mid = &mid_buf->node;
orig_ptr = mid->blockptrs[orig_slot];
if (level < MAX_LEVEL - 1)
parent_buf = path->nodes[level + 1];
pslot = path->slots[level + 1];
if (!parent_buf) {
struct tree_buffer *child;
u64 blocknr = mid_buf->blocknr;
if (btrfs_header_nritems(&mid->header) != 1)
return 0;
/* promote the child to a root */
child = read_node_slot(root, mid_buf, 0);
BUG_ON(!child);
root->node = child;
path->nodes[level] = NULL;
/* once for the path */
tree_block_release(root, mid_buf);
/* once for the root ptr */
tree_block_release(root, mid_buf);
clean_tree_block(root, mid_buf);
return free_extent(root, blocknr, 1);
}
parent = &parent_buf->node;
if (btrfs_header_nritems(&mid->header) > NODEPTRS_PER_BLOCK / 4)
return 0;
left_buf = read_node_slot(root, parent_buf, pslot - 1);
right_buf = read_node_slot(root, parent_buf, pslot + 1);
/* first, try to make some room in the middle buffer */
if (left_buf) {
btrfs_cow_block(root, left_buf, parent_buf,
pslot - 1, &left_buf);
left = &left_buf->node;
orig_slot += btrfs_header_nritems(&left->header);
wret = push_node_left(root, left_buf, mid_buf);
if (wret < 0)
ret = wret;
}
/*
* then try to empty the right most buffer into the middle
*/
if (right_buf) {
btrfs_cow_block(root, right_buf, parent_buf,
pslot + 1, &right_buf);
right = &right_buf->node;
wret = push_node_left(root, mid_buf, right_buf);
if (wret < 0)
ret = wret;
if (btrfs_header_nritems(&right->header) == 0) {
u64 blocknr = right_buf->blocknr;
tree_block_release(root, right_buf);
clean_tree_block(root, right_buf);
right_buf = NULL;
right = NULL;
wret = del_ptr(root, path, level + 1, pslot + 1);
if (wret)
ret = wret;
wret = free_extent(root, blocknr, 1);
if (wret)
ret = wret;
} else {
memcpy(parent->keys + pslot + 1, right->keys,
sizeof(struct btrfs_disk_key));
BUG_ON(list_empty(&parent_buf->dirty));
}
}
if (btrfs_header_nritems(&mid->header) == 1) {
/*
* we're not allowed to leave a node with one item in the
* tree during a delete. A deletion from lower in the tree
* could try to delete the only pointer in this node.
* So, pull some keys from the left.
* There has to be a left pointer at this point because
* otherwise we would have pulled some pointers from the
* right
*/
BUG_ON(!left_buf);
wret = balance_node_right(root, mid_buf, left_buf);
if (wret < 0)
ret = wret;
BUG_ON(wret == 1);
}
if (btrfs_header_nritems(&mid->header) == 0) {
/* we've managed to empty the middle node, drop it */
u64 blocknr = mid_buf->blocknr;
tree_block_release(root, mid_buf);
clean_tree_block(root, mid_buf);
mid_buf = NULL;
mid = NULL;
wret = del_ptr(root, path, level + 1, pslot);
if (wret)
ret = wret;
wret = free_extent(root, blocknr, 1);
if (wret)
ret = wret;
} else {
/* update the parent key to reflect our changes */
memcpy(parent->keys + pslot, mid->keys,
sizeof(struct btrfs_disk_key));
BUG_ON(list_empty(&parent_buf->dirty));
}
/* update the path */
if (left_buf) {
if (btrfs_header_nritems(&left->header) > orig_slot) {
left_buf->count++; // released below
path->nodes[level] = left_buf;
path->slots[level + 1] -= 1;
path->slots[level] = orig_slot;
if (mid_buf)
tree_block_release(root, mid_buf);
} else {
orig_slot -= btrfs_header_nritems(&left->header);
path->slots[level] = orig_slot;
}
}
/* double check we haven't messed things up */
check_block(path, level);
if (orig_ptr != path->nodes[level]->node.blockptrs[path->slots[level]])
BUG();
if (right_buf)
tree_block_release(root, right_buf);
if (left_buf)
tree_block_release(root, left_buf);
return ret;
}
/*
* 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, and 1 is returned. If there are other errors during the
* search a negative error number is returned.
*
* 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 btrfs_key *key,
struct ctree_path *p, int ins_len, int cow)
{
struct tree_buffer *b;
struct tree_buffer *cow_buf;
struct node *c;
int slot;
int ret;
int level;
again:
b = root->node;
b->count++;
while (b) {
level = btrfs_header_level(&b->node.header);
if (cow) {
int wret;
wret = btrfs_cow_block(root, b, p->nodes[level + 1],
p->slots[level + 1], &cow_buf);
b = cow_buf;
}
BUG_ON(!cow && ins_len);
c = &b->node;
p->nodes[level] = b;
ret = check_block(p, level);
if (ret)
return -1;
ret = bin_search(c, key, &slot);
if (!btrfs_is_leaf(c)) {
if (ret && slot > 0)
slot -= 1;
p->slots[level] = slot;
if (ins_len > 0 && btrfs_header_nritems(&c->header) ==
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];
} else if (ins_len < 0) {
int sret = balance_level(root, p, level);
if (sret)
return sret;
b = p->nodes[level];
if (!b)
goto again;
c = &b->node;
slot = p->slots[level];
BUG_ON(btrfs_header_nritems(&c->header) == 1);
}
b = read_tree_block(root, c->blockptrs[slot]);
} 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;
}
BUG_ON(root->node->count == 1);
return ret;
}
}
BUG_ON(root->node->count == 1);
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
*
* If this fails to write a tree block, it returns -1, but continues
* fixing up the blocks in ram so the tree is consistent.
*/
static int fixup_low_keys(struct ctree_root *root,
struct ctree_path *path, struct btrfs_disk_key *key,
int level)
{
int i;
int ret = 0;
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));
BUG_ON(list_empty(&path->nodes[i]->dirty));
if (tslot != 0)
break;
}
return ret;
}
/*
* try to push data from one node into the next node left in the
* tree.
*
* returns 0 if some ptrs were pushed left, < 0 if there was some horrible
* error, and > 0 if there was no room in the left hand block.
*/
static int push_node_left(struct ctree_root *root, struct tree_buffer *dst_buf,
struct tree_buffer *src_buf)
{
struct node *src = &src_buf->node;
struct node *dst = &dst_buf->node;
int push_items = 0;
int src_nritems;
int dst_nritems;
int ret = 0;
src_nritems = btrfs_header_nritems(&src->header);
dst_nritems = btrfs_header_nritems(&dst->header);
push_items = NODEPTRS_PER_BLOCK - dst_nritems;
if (push_items <= 0) {
return 1;
}
if (src_nritems < push_items)
push_items = src_nritems;
memcpy(dst->keys + dst_nritems, src->keys,
push_items * sizeof(struct btrfs_disk_key));
memcpy(dst->blockptrs + dst_nritems, src->blockptrs,
push_items * sizeof(u64));
if (push_items < src_nritems) {
memmove(src->keys, src->keys + push_items,
(src_nritems - push_items) *
sizeof(struct btrfs_disk_key));
memmove(src->blockptrs, src->blockptrs + push_items,
(src_nritems - push_items) * sizeof(u64));
}
btrfs_set_header_nritems(&src->header, src_nritems - push_items);
btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
BUG_ON(list_empty(&src_buf->dirty));
BUG_ON(list_empty(&dst_buf->dirty));
return ret;
}
/*
* try to push data from one node into the next node right in the
* tree.
*
* returns 0 if some ptrs were pushed, < 0 if there was some horrible
* error, and > 0 if there was no room in the right hand block.
*
* this will only push up to 1/2 the contents of the left node over
*/
static int balance_node_right(struct ctree_root *root,
struct tree_buffer *dst_buf,
struct tree_buffer *src_buf)
{
struct node *src = &src_buf->node;
struct node *dst = &dst_buf->node;
int push_items = 0;
int max_push;
int src_nritems;
int dst_nritems;
int ret = 0;
src_nritems = btrfs_header_nritems(&src->header);
dst_nritems = btrfs_header_nritems(&dst->header);
push_items = NODEPTRS_PER_BLOCK - dst_nritems;
if (push_items <= 0) {
return 1;
}
max_push = src_nritems / 2 + 1;
/* don't try to empty the node */
if (max_push > src_nritems)
return 1;
if (max_push < push_items)
push_items = max_push;
memmove(dst->keys + push_items, dst->keys,
dst_nritems * sizeof(struct btrfs_disk_key));
memmove(dst->blockptrs + push_items, dst->blockptrs,
dst_nritems * sizeof(u64));
memcpy(dst->keys, src->keys + src_nritems - push_items,
push_items * sizeof(struct btrfs_disk_key));
memcpy(dst->blockptrs, src->blockptrs + src_nritems - push_items,
push_items * sizeof(u64));
btrfs_set_header_nritems(&src->header, src_nritems - push_items);
btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
BUG_ON(list_empty(&src_buf->dirty));
BUG_ON(list_empty(&dst_buf->dirty));
return ret;
}
/*
* 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
*
* returns zero on success or < 0 on failure.
*/
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 btrfs_disk_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));
btrfs_set_header_nritems(&c->header, 1);
btrfs_set_header_level(&c->header, level);
btrfs_set_header_blocknr(&c->header, t->blocknr);
btrfs_set_header_parentid(&c->header,
btrfs_header_parentid(&root->node->node.header));
lower = &path->nodes[level-1]->node;
if (btrfs_is_leaf(lower))
lower_key = &((struct leaf *)lower)->items[0].key;
else
lower_key = lower->keys;
memcpy(c->keys, lower_key, sizeof(struct btrfs_disk_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++;
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.
*
* returns zero on success and < 0 on any error
*/
static int insert_ptr(struct ctree_root *root,
struct ctree_path *path, struct btrfs_disk_key *key,
u64 blocknr, int slot, int level)
{
struct node *lower;
int nritems;
BUG_ON(!path->nodes[level]);
lower = &path->nodes[level]->node;
nritems = btrfs_header_nritems(&lower->header);
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 btrfs_disk_key));
memmove(lower->blockptrs + slot + 1, lower->blockptrs + slot,
(nritems - slot) * sizeof(u64));
}
memcpy(lower->keys + slot, key, sizeof(struct btrfs_disk_key));
lower->blockptrs[slot] = blocknr;
btrfs_set_header_nritems(&lower->header, nritems + 1);
if (lower->keys[1].objectid == 0)
BUG();
BUG_ON(list_empty(&path->nodes[level]->dirty));
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.
*
* returns 0 on success and < 0 on failure
*/
static 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;
int wret;
u32 c_nritems;
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;
}
c_nritems = btrfs_header_nritems(&c->header);
split_buffer = alloc_free_block(root);
split = &split_buffer->node;
btrfs_set_header_flags(&split->header, btrfs_header_flags(&c->header));
btrfs_set_header_blocknr(&split->header, split_buffer->blocknr);
btrfs_set_header_parentid(&split->header,
btrfs_header_parentid(&root->node->node.header));
mid = (c_nritems + 1) / 2;
memcpy(split->keys, c->keys + mid,
(c_nritems - mid) * sizeof(struct btrfs_disk_key));
memcpy(split->blockptrs, c->blockptrs + mid,
(c_nritems - mid) * sizeof(u64));
btrfs_set_header_nritems(&split->header, c_nritems - mid);
btrfs_set_header_nritems(&c->header, mid);
ret = 0;
BUG_ON(list_empty(&t->dirty));
wret = insert_ptr(root, path, split->keys, split_buffer->blocknr,
path->slots[level + 1] + 1, level + 1);
if (wret)
ret = wret;
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 ret;
}
/*
* 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
*/
static 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
*
* returns 1 if the push failed because the other node didn't have enough
* room, 0 if everything worked out and < 0 if there were major errors.
*/
static 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;
u32 left_nritems;
u32 right_nritems;
slot = path->slots[1];
if (!path->nodes[1]) {
return 1;
}
upper = path->nodes[1];
if (slot >= btrfs_header_nritems(&upper->node.header) - 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;
}
/* cow and double check */
btrfs_cow_block(root, right_buf, upper, slot + 1, &right_buf);
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;
}
left_nritems = btrfs_header_nritems(&left->header);
for (i = left_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;
}
right_nritems = btrfs_header_nritems(&right->header);
/* push left to right */
push_space = left->items[left_nritems - push_items].offset +
left->items[left_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_nritems * sizeof(struct item));
/* copy the items from left to right */
memcpy(right->items, left->items + left_nritems - push_items,
push_items * sizeof(struct item));
/* update the item pointers */
right_nritems += push_items;
btrfs_set_header_nritems(&right->header, right_nritems);
push_space = LEAF_DATA_SIZE;
for (i = 0; i < right_nritems; i++) {
right->items[i].offset = push_space - right->items[i].size;
push_space = right->items[i].offset;
}
left_nritems -= push_items;
btrfs_set_header_nritems(&left->header, left_nritems);
BUG_ON(list_empty(&left_buf->dirty));
BUG_ON(list_empty(&right_buf->dirty));
memcpy(upper->node.keys + slot + 1,
&right->items[0].key, sizeof(struct btrfs_disk_key));
BUG_ON(list_empty(&upper->dirty));
/* then fixup the leaf pointer in the path */
if (path->slots[0] >= left_nritems) {
path->slots[0] -= left_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
*/
static 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;
u32 old_left_nritems;
int ret = 0;
int wret;
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;
}
/* cow and double check */
btrfs_cow_block(root, t, path->nodes[1], slot - 1, &t);
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 < btrfs_header_nritems(&right->header); 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 + btrfs_header_nritems(&left->header),
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 = btrfs_header_nritems(&left->header);
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;
}
btrfs_set_header_nritems(&left->header, old_left_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,
(btrfs_header_nritems(&right->header) - push_items) *
sizeof(struct item));
btrfs_set_header_nritems(&right->header,
btrfs_header_nritems(&right->header) -
push_items);
push_space = LEAF_DATA_SIZE;
for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
right->items[i].offset = push_space - right->items[i].size;
push_space = right->items[i].offset;
}
BUG_ON(list_empty(&t->dirty));
BUG_ON(list_empty(&right_buf->dirty));
wret = fixup_low_keys(root, path, &right->items[0].key, 1);
if (wret)
ret = wret;
/* 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 ret;
}
/*
* split the path's leaf in two, making sure there is at least data_size
* available for the resulting leaf level of the path.
*
* returns 0 if all went well and < 0 on failure.
*/
static int split_leaf(struct ctree_root *root, struct ctree_path *path,
int data_size)
{
struct tree_buffer *l_buf;
struct leaf *l;
u32 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;
int wret;
l_buf = path->nodes[0];
l = &l_buf->leaf;
/* did the pushes work? */
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 = btrfs_header_nritems(&l->header);
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();
}
btrfs_set_header_nritems(&right->header, nritems - mid);
btrfs_set_header_blocknr(&right->header, right_buffer->blocknr);
btrfs_set_header_level(&right->header, 0);
btrfs_set_header_parentid(&right->header,
btrfs_header_parentid(&root->node->node.header));
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 < btrfs_header_nritems(&right->header); i++)
right->items[i].offset += rt_data_off;
btrfs_set_header_nritems(&l->header, mid);
ret = 0;
wret = insert_ptr(root, path, &right->items[0].key,
right_buffer->blocknr, path->slots[1] + 1, 1);
if (wret)
ret = wret;
BUG_ON(list_empty(&right_buffer->dirty));
BUG_ON(list_empty(&l_buf->dirty));
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 btrfs_key *cpu_key,
void *data, int data_size)
{
int ret = 0;
int slot;
int slot_orig;
struct leaf *leaf;
struct tree_buffer *leaf_buf;
u32 nritems;
unsigned int data_end;
struct ctree_path path;
struct btrfs_disk_key disk_key;
btrfs_cpu_key_to_disk(&disk_key, cpu_key);
/* create a root if there isn't one */
if (!root->node)
BUG();
init_path(&path);
ret = search_slot(root, cpu_key, &path, data_size, 1);
if (ret == 0) {
release_path(root, &path);
return -EEXIST;
}
if (ret < 0)
goto out;
slot_orig = path.slots[0];
leaf_buf = path.nodes[0];
leaf = &leaf_buf->leaf;
nritems = btrfs_header_nritems(&leaf->header);
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, &disk_key,
sizeof(struct btrfs_disk_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);
btrfs_set_header_nritems(&leaf->header, nritems + 1);
ret = 0;
if (slot == 0)
ret = fixup_low_keys(root, &path, &disk_key, 1);
BUG_ON(list_empty(&leaf_buf->dirty));
if (leaf_free_space(leaf) < 0)
BUG();
check_leaf(&path, 0);
out:
release_path(root, &path);
return ret;
}
/*
* 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.
*/
static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level,
int slot)
{
struct node *node;
struct tree_buffer *parent = path->nodes[level];
u32 nritems;
int ret = 0;
int wret;
node = &parent->node;
nritems = btrfs_header_nritems(&node->header);
if (slot != nritems -1) {
memmove(node->keys + slot, node->keys + slot + 1,
sizeof(struct btrfs_disk_key) * (nritems - slot - 1));
memmove(node->blockptrs + slot,
node->blockptrs + slot + 1,
sizeof(u64) * (nritems - slot - 1));
}
nritems--;
btrfs_set_header_nritems(&node->header, nritems);
if (nritems == 0 && parent == root->node) {
BUG_ON(btrfs_header_level(&root->node->node.header) != 1);
/* just turn the root into a leaf and break */
btrfs_set_header_level(&root->node->node.header, 0);
} else if (slot == 0) {
wret = fixup_low_keys(root, path, node->keys, level + 1);
if (wret)
ret = wret;
}
BUG_ON(list_empty(&parent->dirty));
return ret;
}
/*
* 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;
int ret = 0;
int wret;
u32 nritems;
leaf_buf = path->nodes[0];
leaf = &leaf_buf->leaf;
slot = path->slots[0];
doff = leaf->items[slot].offset;
dsize = leaf->items[slot].size;
nritems = btrfs_header_nritems(&leaf->header);
if (slot != 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 < nritems; i++)
leaf->items[i].offset += dsize;
memmove(leaf->items + slot, leaf->items + slot + 1,
sizeof(struct item) *
(nritems - slot - 1));
}
btrfs_set_header_nritems(&leaf->header, nritems - 1);
nritems--;
/* delete the leaf if we've emptied it */
if (nritems == 0) {
if (leaf_buf == root->node) {
btrfs_set_header_level(&leaf->header, 0);
BUG_ON(list_empty(&leaf_buf->dirty));
} else {
clean_tree_block(root, leaf_buf);
wret = del_ptr(root, path, 1, path->slots[1]);
if (wret)
ret = wret;
wret = free_extent(root, leaf_buf->blocknr, 1);
if (wret)
ret = wret;
}
} else {
int used = leaf_space_used(leaf, 0, nritems);
if (slot == 0) {
wret = fixup_low_keys(root, path,
&leaf->items[0].key, 1);
if (wret)
ret = wret;
}
BUG_ON(list_empty(&leaf_buf->dirty));
/* 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++;
wret = push_leaf_left(root, path, 1);
if (wret < 0)
ret = wret;
if (path->nodes[0] == leaf_buf &&
btrfs_header_nritems(&leaf->header)) {
wret = push_leaf_right(root, path, 1);
if (wret < 0)
ret = wret;
}
if (btrfs_header_nritems(&leaf->header) == 0) {
u64 blocknr = leaf_buf->blocknr;
clean_tree_block(root, leaf_buf);
wret = del_ptr(root, path, 1, slot);
if (wret)
ret = wret;
tree_block_release(root, leaf_buf);
wret = free_extent(root, blocknr, 1);
if (wret)
ret = wret;
} else {
tree_block_release(root, leaf_buf);
}
}
}
return ret;
}
/*
* 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.
* returns < 0 on io errors.
*/
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 >= btrfs_header_nritems(&c->node.header)) {
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;
}
