#define IS_TNODE(n) ((n)->bits)
#define IS_LEAF(n) (!(n)->bits)
-#define get_shift(_kv) (KEYLENGTH - (_kv)->pos - (_kv)->bits)
-#define get_index(_key, _kv) (((_key) ^ (_kv)->key) >> get_shift(_kv))
+#define get_index(_key, _kv) (((_key) ^ (_kv)->key) >> (_kv)->pos)
struct tnode {
t_key key;
return rcu_dereference_rtnl(tn->child[i]);
}
-static inline t_key mask_pfx(t_key k, unsigned int l)
-{
- return (l == 0) ? 0 : k >> (KEYLENGTH-l) << (KEYLENGTH-l);
-}
-
-static inline t_key tkey_extract_bits(t_key a, unsigned int offset, unsigned int bits)
-{
- if (offset < KEYLENGTH)
- return ((t_key)(a << offset)) >> (KEYLENGTH - bits);
- else
- return 0;
-}
-
-/*
- To understand this stuff, an understanding of keys and all their bits is
- necessary. Every node in the trie has a key associated with it, but not
- all of the bits in that key are significant.
-
- Consider a node 'n' and its parent 'tp'.
-
- If n is a leaf, every bit in its key is significant. Its presence is
- necessitated by path compression, since during a tree traversal (when
- searching for a leaf - unless we are doing an insertion) we will completely
- ignore all skipped bits we encounter. Thus we need to verify, at the end of
- a potentially successful search, that we have indeed been walking the
- correct key path.
-
- Note that we can never "miss" the correct key in the tree if present by
- following the wrong path. Path compression ensures that segments of the key
- that are the same for all keys with a given prefix are skipped, but the
- skipped part *is* identical for each node in the subtrie below the skipped
- bit! trie_insert() in this implementation takes care of that - note the
- call to tkey_sub_equals() in trie_insert().
-
- if n is an internal node - a 'tnode' here, the various parts of its key
- have many different meanings.
-
- Example:
- _________________________________________________________________
- | i | i | i | i | i | i | i | N | N | N | S | S | S | S | S | C |
- -----------------------------------------------------------------
- 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
-
- _________________________________________________________________
- | C | C | C | u | u | u | u | u | u | u | u | u | u | u | u | u |
- -----------------------------------------------------------------
- 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
-
- tp->pos = 7
- tp->bits = 3
- n->pos = 15
- n->bits = 4
-
- First, let's just ignore the bits that come before the parent tp, that is
- the bits from 0 to (tp->pos-1). They are *known* but at this point we do
- not use them for anything.
-
- The bits from (tp->pos) to (tp->pos + tp->bits - 1) - "N", above - are the
- index into the parent's child array. That is, they will be used to find
- 'n' among tp's children.
-
- The bits from (tp->pos + tp->bits) to (n->pos - 1) - "S" - are skipped bits
- for the node n.
-
- All the bits we have seen so far are significant to the node n. The rest
- of the bits are really not needed or indeed known in n->key.
-
- The bits from (n->pos) to (n->pos + n->bits - 1) - "C" - are the index into
- n's child array, and will of course be different for each child.
-
-
- The rest of the bits, from (n->pos + n->bits) onward, are completely unknown
- at this point.
-
-*/
+/* To understand this stuff, an understanding of keys and all their bits is
+ * necessary. Every node in the trie has a key associated with it, but not
+ * all of the bits in that key are significant.
+ *
+ * Consider a node 'n' and its parent 'tp'.
+ *
+ * If n is a leaf, every bit in its key is significant. Its presence is
+ * necessitated by path compression, since during a tree traversal (when
+ * searching for a leaf - unless we are doing an insertion) we will completely
+ * ignore all skipped bits we encounter. Thus we need to verify, at the end of
+ * a potentially successful search, that we have indeed been walking the
+ * correct key path.
+ *
+ * Note that we can never "miss" the correct key in the tree if present by
+ * following the wrong path. Path compression ensures that segments of the key
+ * that are the same for all keys with a given prefix are skipped, but the
+ * skipped part *is* identical for each node in the subtrie below the skipped
+ * bit! trie_insert() in this implementation takes care of that.
+ *
+ * if n is an internal node - a 'tnode' here, the various parts of its key
+ * have many different meanings.
+ *
+ * Example:
+ * _________________________________________________________________
+ * | i | i | i | i | i | i | i | N | N | N | S | S | S | S | S | C |
+ * -----------------------------------------------------------------
+ * 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
+ *
+ * _________________________________________________________________
+ * | C | C | C | u | u | u | u | u | u | u | u | u | u | u | u | u |
+ * -----------------------------------------------------------------
+ * 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
+ *
+ * tp->pos = 22
+ * tp->bits = 3
+ * n->pos = 13
+ * n->bits = 4
+ *
+ * First, let's just ignore the bits that come before the parent tp, that is
+ * the bits from (tp->pos + tp->bits) to 31. They are *known* but at this
+ * point we do not use them for anything.
+ *
+ * The bits from (tp->pos) to (tp->pos + tp->bits - 1) - "N", above - are the
+ * index into the parent's child array. That is, they will be used to find
+ * 'n' among tp's children.
+ *
+ * The bits from (n->pos + n->bits) to (tn->pos - 1) - "S" - are skipped bits
+ * for the node n.
+ *
+ * All the bits we have seen so far are significant to the node n. The rest
+ * of the bits are really not needed or indeed known in n->key.
+ *
+ * The bits from (n->pos) to (n->pos + n->bits - 1) - "C" - are the index into
+ * n's child array, and will of course be different for each child.
+ *
+ * The rest of the bits, from 0 to (n->pos + n->bits), are completely unknown
+ * at this point.
+ */
static const int halve_threshold = 25;
static const int inflate_threshold = 50;
* as the nodes are searched
*/
l->key = key;
- l->pos = KEYLENGTH;
+ l->pos = 0;
/* set bits to 0 indicating we are not a tnode */
l->bits = 0;
tn->parent = NULL;
tn->pos = pos;
tn->bits = bits;
- tn->key = mask_pfx(key, pos);
+ tn->key = (shift < KEYLENGTH) ? (key >> shift) << shift : 0;
tn->full_children = 0;
tn->empty_children = 1<<bits;
}
return tn;
}
-/*
- * Check whether a tnode 'n' is "full", i.e. it is an internal node
+/* Check whether a tnode 'n' is "full", i.e. it is an internal node
* and no bits are skipped. See discussion in dyntree paper p. 6
*/
-
static inline int tnode_full(const struct tnode *tn, const struct tnode *n)
{
- return n && IS_TNODE(n) && (n->pos == (tn->pos + tn->bits));
+ return n && ((n->pos + n->bits) == tn->pos) && IS_TNODE(n);
}
static inline void put_child(struct tnode *tn, int i,
{
int olen = tnode_child_length(oldtnode);
struct tnode *tn;
+ t_key m;
int i;
pr_debug("In inflate\n");
- tn = tnode_new(oldtnode->key, oldtnode->pos, oldtnode->bits + 1);
+ tn = tnode_new(oldtnode->key, oldtnode->pos - 1, oldtnode->bits + 1);
if (!tn)
return ERR_PTR(-ENOMEM);
* fails. In case of failure we return the oldnode and inflate
* of tnode is ignored.
*/
+ for (i = 0, m = 1u << tn->pos; i < olen; i++) {
+ struct tnode *inode = tnode_get_child(oldtnode, i);
- for (i = 0; i < olen; i++) {
- struct tnode *inode;
-
- inode = tnode_get_child(oldtnode, i);
- if (tnode_full(oldtnode, inode) && inode->bits > 1) {
+ if (tnode_full(oldtnode, inode) && (inode->bits > 1)) {
struct tnode *left, *right;
- t_key m = ~0U << (KEYLENGTH - 1) >> inode->pos;
- left = tnode_new(inode->key&(~m), inode->pos + 1,
+ left = tnode_new(inode->key & ~m, inode->pos,
inode->bits - 1);
if (!left)
goto nomem;
- right = tnode_new(inode->key|m, inode->pos + 1,
+ right = tnode_new(inode->key | m, inode->pos,
inode->bits - 1);
if (!right) {
/* A leaf or an internal node with skipped bits */
if (!tnode_full(oldtnode, inode)) {
- put_child(tn,
- tkey_extract_bits(inode->key, tn->pos, tn->bits),
- inode);
+ put_child(tn, get_index(inode->key, tn), inode);
continue;
}
pr_debug("In halve\n");
- tn = tnode_new(oldtnode->key, oldtnode->pos, oldtnode->bits - 1);
+ tn = tnode_new(oldtnode->key, oldtnode->pos + 1, oldtnode->bits - 1);
if (!tn)
return ERR_PTR(-ENOMEM);
if (left && right) {
struct tnode *newn;
- newn = tnode_new(left->key, tn->pos + tn->bits, 1);
+ newn = tnode_new(left->key, oldtnode->pos, 1);
if (!newn)
goto nomem;
key = tn->key;
while (tn != NULL && (tp = node_parent(tn)) != NULL) {
- cindex = tkey_extract_bits(key, tp->pos, tp->bits);
+ cindex = get_index(key, tp);
wasfull = tnode_full(tp, tnode_get_child(tp, cindex));
tn = resize(t, tn);
*/
if (n) {
struct tnode *tn;
- int newpos;
-
- newpos = KEYLENGTH - __fls(n->key ^ key) - 1;
- tn = tnode_new(key, newpos, 1);
+ tn = tnode_new(key, __fls(key ^ n->key), 1);
if (!tn) {
free_leaf_info(li);
node_free(l);
static struct tnode *leaf_walk_rcu(struct tnode *p, struct tnode *c)
{
do {
- t_key idx;
-
- if (c)
- idx = tkey_extract_bits(c->key, p->pos, p->bits) + 1;
- else
- idx = 0;
+ t_key idx = c ? idx = get_index(c->key, p) + 1 : 0;
while (idx < 1u << p->bits) {
c = tnode_get_child_rcu(p, idx++);
/* Current node exhausted, pop back up */
p = node_parent_rcu(tn);
if (p) {
- cindex = tkey_extract_bits(tn->key, p->pos, p->bits)+1;
+ cindex = get_index(tn->key, p) + 1;
tn = p;
--iter->depth;
goto rescan;
if (IS_TNODE(n)) {
__be32 prf = htonl(n->key);
- seq_indent(seq, iter->depth - 1);
- seq_printf(seq, " +-- %pI4/%d %d %d %d\n",
- &prf, n->pos, n->bits, n->full_children,
- n->empty_children);
+ seq_indent(seq, iter->depth-1);
+ seq_printf(seq, " +-- %pI4/%zu %u %u %u\n",
+ &prf, KEYLENGTH - n->pos - n->bits, n->bits,
+ n->full_children, n->empty_children);
} else {
struct leaf_info *li;
__be32 val = htonl(n->key);
projects / users / hch / configfs.git / commitdiff