*
* Dominic Giampaolo, author of "Practical File System
* Design with the Be File System", for such a helpful book.
- *
- * Marcus J. Ranum, author of the b+tree package in
+ *
+ * Marcus J. Ranum, author of the b+tree package in
* comp.sources.misc volume 10. This code is not copied from that
* work, but it is partially based on it.
*
*/
/* Befs B+tree structure:
- *
+ *
* The first thing in the tree is the tree superblock. It tells you
* all kinds of useful things about the tree, like where the rootnode
* is located, and the size of the nodes (always 1024 with current version
* of BeOS).
*
* The rest of the tree consists of a series of nodes. Nodes contain a header
- * (struct befs_btree_nodehead), the packed key data, an array of shorts
+ * (struct befs_btree_nodehead), the packed key data, an array of shorts
* containing the ending offsets for each of the keys, and an array of
- * befs_off_t values. In interior nodes, the keys are the ending keys for
- * the childnode they point to, and the values are offsets into the
- * datastream containing the tree.
+ * befs_off_t values. In interior nodes, the keys are the ending keys for
+ * the childnode they point to, and the values are offsets into the
+ * datastream containing the tree.
*/
/* Note:
- *
- * The book states 2 confusing things about befs b+trees. First,
+ *
+ * The book states 2 confusing things about befs b+trees. First,
* it states that the overflow field of node headers is used by internal nodes
* to point to another node that "effectively continues this one". Here is what
* I believe that means. Each key in internal nodes points to another node that
- * contains key values less than itself. Inspection reveals that the last key
- * in the internal node is not the last key in the index. Keys that are
- * greater than the last key in the internal node go into the overflow node.
+ * contains key values less than itself. Inspection reveals that the last key
+ * in the internal node is not the last key in the index. Keys that are
+ * greater than the last key in the internal node go into the overflow node.
* I imagine there is a performance reason for this.
*
- * Second, it states that the header of a btree node is sufficient to
- * distinguish internal nodes from leaf nodes. Without saying exactly how.
+ * Second, it states that the header of a btree node is sufficient to
+ * distinguish internal nodes from leaf nodes. Without saying exactly how.
* After figuring out the first, it becomes obvious that internal nodes have
* overflow nodes and leafnodes do not.
*/
-/*
+/*
* Currently, this code is only good for directory B+trees.
* In order to be used for other BFS indexes, it needs to be extended to handle
* duplicate keys and non-string keytypes (int32, int64, float, double).
* with @key (usually the disk block number of an inode).
*
* On failure, returns BEFS_ERR or BEFS_BT_NOT_FOUND.
- *
- * Algorithm:
+ *
+ * Algorithm:
* Read the superblock and rootnode of the b+tree.
* Drill down through the interior nodes using befs_find_key().
* Once at the correct leaf node, use befs_find_key() again to get the
*
* Here's how it works: Key_no is the index of the key/value pair to
* return in keybuf/value.
- * Bufsize is the size of keybuf (BEFS_NAME_LEN+1 is a good size). Keysize is
+ * Bufsize is the size of keybuf (BEFS_NAME_LEN+1 is a good size). Keysize is
* the number of characters in the key (just a convenience).
*
* Algorithm:
* Get the first leafnode of the tree. See if the requested key is in that
- * node. If not, follow the node->right link to the next leafnode. Repeat
+ * node. If not, follow the node->right link to the next leafnode. Repeat
* until the (key_no)th key is found or the tree is out of keys.
*/
int
* @node_off: Pointer to offset of current node within datastream. Modified
* by the function.
*
- * Helper function for btree traverse. Moves the current position to the
+ * Helper function for btree traverse. Moves the current position to the
* start of the first leaf node.
*
* Also checks for an empty tree. If there are no keys, returns BEFS_BT_EMPTY.
}
/**
- * befs_leafnode - Determine if the btree node is a leaf node or an
+ * befs_leafnode - Determine if the btree node is a leaf node or an
* interior node
* @node: Pointer to node structure to test
- *
+ *
* Return 1 if leaf, 0 if interior
*/
static int
* @node: Pointer to the node structure to find the keydata array within
*
* Returns a pointer to the start of the keydata array
- * of the node pointed to by the node header
+ * of the node pointed to by the node header
*/
static char *
befs_bt_keydata(struct befs_btree_node *node)
/**
* befs_compare_strings - compare two strings
- * @key1: pointer to the first key to be compared
+ * @key1: pointer to the first key to be compared
* @keylen1: length in bytes of key1
* @key2: pointer to the second key to be compared
* @keylen2: length in bytes of key2
projects / linux-block.git / blobdiff