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Btrfs: cleanup & comment 

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2007-02-24 13:39:08 -05:00 committed by David Woodhouse
parent 00ec4c5161
commit 97571fd0c9
1 changed files with 27 additions and 1 deletions
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28
fs/btrfs/ctree.c
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@ -110,6 +110,10 @@ int generic_bin_search(char *p, int item_size, struct key *key,
return 1; 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) int bin_search(struct node *c, struct key *key, int *slot)
{ {
if (is_leaf(c->header.flags)) { if (is_leaf(c->header.flags)) {
@ -130,6 +134,10 @@ 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 * If the key isn't found, the path points to the slot where it should
* be inserted. * 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, int search_slot(struct ctree_root *root, struct key *key,
struct ctree_path *p, int ins_len) struct ctree_path *p, int ins_len)
@ -379,6 +387,11 @@ int push_node_right(struct ctree_root *root, struct ctree_path *path, int level)
return 0; 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, static int insert_new_root(struct ctree_root *root,
struct ctree_path *path, int level) struct ctree_path *path, int level)
{ {
@ -417,6 +430,7 @@ static int insert_new_root(struct ctree_root *root,
/* /*
* worker function to insert a single pointer in a node. * worker function to insert a single pointer in a node.
* the node should have enough room for the pointer already * the node should have enough room for the pointer already
*
* slot and level indicate where you want the key to go, and * slot and level indicate where you want the key to go, and
* blocknr is the block the key points to. * blocknr is the block the key points to.
*/ */
@ -449,6 +463,13 @@ int insert_ptr(struct ctree_root *root,
return 0; 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) int split_node(struct ctree_root *root, struct ctree_path *path, int level)
{ {
struct tree_buffer *t; struct tree_buffer *t;
@ -744,10 +765,12 @@ int split_leaf(struct ctree_root *root, struct ctree_path *path, int data_size)
right = &right_buffer->leaf; right = &right_buffer->leaf;
memset(right, 0, sizeof(*right)); memset(right, 0, sizeof(*right));
if (mid <= slot) { if (mid <= slot) {
/* FIXME, just alloc a new leaf here */
if (leaf_space_used(l, mid, nritems - mid) + space_needed > if (leaf_space_used(l, mid, nritems - mid) + space_needed >
LEAF_DATA_SIZE) LEAF_DATA_SIZE)
BUG(); BUG();
} else { } else {
/* FIXME, just alloc a new leaf here */
if (leaf_space_used(l, 0, mid + 1) + space_needed > if (leaf_space_used(l, 0, mid + 1) + space_needed >
LEAF_DATA_SIZE) LEAF_DATA_SIZE)
BUG(); BUG();
@ -983,6 +1006,10 @@ int del_item(struct ctree_root *root, struct ctree_path *path)
return 0; 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 next_leaf(struct ctree_root *root, struct ctree_path *path)
{ {
int slot; int slot;
@ -1044,7 +1071,6 @@ int main() {
root = open_ctree("dbfile", &super); root = open_ctree("dbfile", &super);
srand(55); srand(55);
for (i = 0; i < run_size; i++) { for (i = 0; i < run_size; i++) {
buf = malloc(64); buf = malloc(64);