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Btrfs: switch to early splits 

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2007-02-22 11:39:13 -05:00 committed by David Woodhouse
parent cfaa72952f
commit 5c680ed620
2 changed files with 120 additions and 146 deletions
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263
fs/btrfs/ctree.c
View File

@ -5,7 +5,12 @@
#include "ctree.h"
#include "disk-io.h"
#define SEARCH_READ 0
#define SEARCH_WRITE 1
static int refill_alloc_extent(struct ctree_root *root);
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);
static inline void init_path(struct ctree_path *p)
{
@ -125,14 +130,14 @@ int bin_search(struct node *c, struct key *key, int *slot)
* If the key isn't found, the path points to the slot where it should
* be inserted.
*/
int search_slot(struct ctree_root *root, struct key *key, struct ctree_path *p)
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;
@ -143,10 +148,26 @@ int search_slot(struct ctree_root *root, struct key *key, struct ctree_path *p)
if (ret && slot > 0)
slot -= 1;
p->slots[level] = slot;
if (ins_len && 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 && 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;
}
}
@ -331,50 +352,54 @@ int push_node_right(struct ctree_root *root, struct ctree_path *path, int level)
return 0;
}
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,
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]) {
struct tree_buffer *t;
t = alloc_free_block(root);
c = &t->node;
memset(c, 0, sizeof(c));
c->header.nritems = 2;
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));
memcpy(c->keys + 1, key, sizeof(struct key));
c->blockptrs[0] = path->nodes[level-1]->blocknr;
c->blockptrs[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;
if (c->keys[1].objectid == 0)
BUG();
return 0;
}
BUG_ON(!path->nodes[level]);
lower = &path->nodes[level]->node;
nritems = lower->header.nritems;
if (slot > nritems)
@ -396,93 +421,54 @@ int __insert_ptr(struct ctree_root *root,
return 0;
}
/*
* insert a key,blocknr pair into the tree at a given level
* If the node at that level in the path doesn't have room,
* it is split or shifted as appropriate.
*/
int insert_ptr(struct ctree_root *root,
struct ctree_path *path, struct key *key,
u64 blocknr, int level)
int split_node(struct ctree_root *root, struct ctree_path *path, int level)
{
struct tree_buffer *t = path->nodes[level];
struct node *c = &path->nodes[level]->node;
struct node *b;
struct tree_buffer *b_buffer;
struct tree_buffer *bal[MAX_LEVEL];
int bal_level = level;
struct tree_buffer *t;
struct node *c;
struct tree_buffer *split_buffer;
struct node *split;
int mid;
int bal_start = -1;
int ret;
/*
* check to see if we need to make room in the node for this
* pointer. If we do, keep walking the tree, making sure there
* is enough room in each level for the required insertions.
*
* The bal array is filled in with any nodes to be inserted
* due to splitting. Once we've done all the splitting required
* do the inserts based on the data in the bal array.
*/
memset(bal, 0, sizeof(bal));
while(t && t->node.header.nritems == NODEPTRS_PER_BLOCK) {
c = &t->node;
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_buffer = alloc_free_block(root);
b = &b_buffer->node;
b->header.flags = c->header.flags;
b->header.blocknr = b_buffer->blocknr;
b->header.parentid = root->node->node.header.parentid;
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;
write_tree_block(root, t);
write_tree_block(root, b_buffer);
bal[bal_level] = b_buffer;
if (bal_level == MAX_LEVEL - 1)
break;
bal_level += 1;
t = path->nodes[bal_level];
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;
}
/*
* bal_start tells us the first level in the tree that needed to
* be split. Go through the bal array inserting the new nodes
* as needed. The path is fixed as we go.
*/
while(bal_start > 0) {
b_buffer = bal[bal_start];
c = &path->nodes[bal_start]->node;
__insert_ptr(root, path, b_buffer->node.keys, b_buffer->blocknr,
path->slots[bal_start + 1] + 1, bal_start + 1);
if (path->slots[bal_start] >= c->header.nritems) {
path->slots[bal_start] -= c->header.nritems;
tree_block_release(root, path->nodes[bal_start]);
path->nodes[bal_start] = b_buffer;
path->slots[bal_start + 1] += 1;
} else {
tree_block_release(root, b_buffer);
}
bal_start--;
if (!bal[bal_start])
break;
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);
}
/* Now that the tree has room, insert the requested pointer */
return __insert_ptr(root, path, key, blocknr, path->slots[level] + 1,
level);
return 0;
}
/*
@ -623,6 +609,11 @@ int split_leaf(struct ctree_root *root, struct ctree_path *path, int data_size)
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;
@ -659,8 +650,7 @@ int split_leaf(struct ctree_root *root, struct ctree_path *path, int data_size)
l->header.nritems = mid;
ret = insert_ptr(root, path, &right->items[0].key,
right_buffer->blocknr, 1);
right_buffer->blocknr, path->slots[1] + 1, 1);
write_tree_block(root, right_buffer);
write_tree_block(root, l_buf);
@ -695,21 +685,10 @@ int insert_item(struct ctree_root *root, struct key *key,
refill_alloc_extent(root);
/* create a root if there isn't one */
if (!root->node) {
if (!root->node)
BUG();
#if 0
struct tree_buffer *t;
t = alloc_free_block(root);
BUG_ON(!t);
t->node.header.nritems = 0;
t->node.header.flags = node_level(0);
t->node.header.blocknr = t->blocknr;
root->node = t;
write_tree_block(root, t);
#endif
}
init_path(&path);
ret = search_slot(root, key, &path);
ret = search_slot(root, key, &path, data_size);
if (ret == 0) {
release_path(root, &path);
return -EEXIST;
@ -719,12 +698,6 @@ int insert_item(struct ctree_root *root, struct key *key,
leaf_buf = path.nodes[0];
leaf = &leaf_buf->leaf;
/* make room if needed */
if (leaf_free_space(leaf) < sizeof(struct item) + data_size) {
split_leaf(root, &path, data_size);
leaf_buf = path.nodes[0];
leaf = &path.nodes[0]->leaf;
}
nritems = leaf->header.nritems;
data_end = leaf_data_end(leaf);
@ -950,7 +923,7 @@ int alloc_extent(struct ctree_root *orig_root, u64 num_blocks, u64 search_start,
ins->offset = 0;
ins->flags = 0;
ret = search_slot(root, ins, &path);
ret = search_slot(root, ins, &path, sizeof(struct extent_item));
while (1) {
l = &path.nodes[0]->leaf;
slot = path.slots[0];
@ -1097,8 +1070,8 @@ void print_tree(struct ctree_root *root, struct tree_buffer *t)
/* for testing only */
int next_key(int i, int max_key) {
return rand() % max_key;
// return i;
// return rand() % max_key;
return i;
}
int main() {
@ -1154,7 +1127,7 @@ int main() {
num = next_key(i, max_key);
ins.objectid = num;
init_path(&path);
ret = search_slot(root, &ins, &path);
ret = search_slot(root, &ins, &path, 0);
if (ret) {
print_tree(root, root->node);
printf("unable to find %d\n", num);
@ -1176,7 +1149,7 @@ int main() {
num = next_key(i, max_key);
ins.objectid = num;
init_path(&path);
ret = search_slot(root, &ins, &path);
ret = search_slot(root, &ins, &path, 0);
if (ret)
continue;
ret = del_item(root, &path);
@ -1204,7 +1177,7 @@ int main() {
num = next_key(i, max_key);
ins.objectid = num;
init_path(&path);
ret = search_slot(root, &ins, &path);
ret = search_slot(root, &ins, &path, 0);
if (ret) {
print_tree(root, root->node);
printf("unable to find %d\n", num);
@ -1218,7 +1191,7 @@ int main() {
int slot;
ins.objectid = (u64)-1;
init_path(&path);
ret = search_slot(root, &ins, &path);
ret = search_slot(root, &ins, &path, 0);
if (ret == 0)
BUG();

3
fs/btrfs/disk-io.c
View File

@ -149,7 +149,8 @@ struct ctree_root *open_ctree(char *filename, struct ctree_super_block *super)
}
ret = pread(fp, super, sizeof(struct ctree_super_block),
CTREE_SUPER_INFO_OFFSET(CTREE_BLOCKSIZE));
if (ret == 0) {
if (ret == 0 || super->root_info.tree_root == 0) {
printf("making new FS!\n");
ret = mkfs(fp);
if (ret)
return NULL;