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nilfs2: optimize calculation of min/max number of btree node children
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nilfs_btree_node_nchildren_max() and nilfs_btree_node_nchildren_min()
functions switch return value depending on whether target node is the
root or a node block.  In most uses of these functions, however, the
node type is fixed, and moreover the same calculation is repeatedly
performed in loop.

This unfold these functions depending on context and move them outside
loops wherever possible.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
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Ryusuke Konishi committed Jul 23, 2010
1 parent 364ec2d commit ea64ab8
Showing 1 changed file with 18 additions and 18 deletions.
36 changes: 18 additions & 18 deletions fs/nilfs2/btree.c
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Original file line number Diff line number Diff line change
Expand Up @@ -473,7 +473,7 @@ static int nilfs_btree_do_lookup(const struct nilfs_bmap *btree,
{
struct nilfs_btree_node *node;
__u64 ptr;
int level, index, found, ret;
int level, index, found, ncmax, ret;

node = nilfs_btree_get_root(btree);
level = nilfs_btree_node_get_level(node);
Expand All @@ -485,6 +485,8 @@ static int nilfs_btree_do_lookup(const struct nilfs_bmap *btree,
path[level].bp_bh = NULL;
path[level].bp_index = index;

ncmax = NILFS_BTREE_NODE_NCHILDREN_MAX(nilfs_btree_node_size(btree));

for (level--; level >= minlevel; level--) {
ret = nilfs_btree_get_block(btree, ptr, &path[level].bp_bh);
if (ret < 0)
Expand All @@ -496,9 +498,9 @@ static int nilfs_btree_do_lookup(const struct nilfs_bmap *btree,
found = nilfs_btree_node_lookup(node, key, &index);
else
index = 0;
if (index < nilfs_btree_node_nchildren_max(node, btree))
if (index < ncmax) {
ptr = nilfs_btree_node_get_ptr(btree, node, index);
else {
} else {
WARN_ON(found || level != NILFS_BTREE_LEVEL_NODE_MIN);
/* insert */
ptr = NILFS_BMAP_INVALID_PTR;
Expand Down Expand Up @@ -921,7 +923,7 @@ static int nilfs_btree_prepare_insert(struct nilfs_bmap *btree,
struct buffer_head *bh;
struct nilfs_btree_node *node, *parent, *sib;
__u64 sibptr;
int pindex, level, ret;
int pindex, level, ncmax, ret;
struct inode *dat = NULL;

stats->bs_nblocks = 0;
Expand All @@ -938,12 +940,13 @@ static int nilfs_btree_prepare_insert(struct nilfs_bmap *btree,
if (ret < 0)
goto err_out_data;

ncmax = NILFS_BTREE_NODE_NCHILDREN_MAX(nilfs_btree_node_size(btree));

for (level = NILFS_BTREE_LEVEL_NODE_MIN;
level < nilfs_btree_height(btree) - 1;
level++) {
node = nilfs_btree_get_nonroot_node(path, level);
if (nilfs_btree_node_get_nchildren(node) <
nilfs_btree_node_nchildren_max(node, btree)) {
if (nilfs_btree_node_get_nchildren(node) < ncmax) {
path[level].bp_op = nilfs_btree_do_insert;
stats->bs_nblocks++;
goto out;
Expand All @@ -960,8 +963,7 @@ static int nilfs_btree_prepare_insert(struct nilfs_bmap *btree,
if (ret < 0)
goto err_out_child_node;
sib = (struct nilfs_btree_node *)bh->b_data;
if (nilfs_btree_node_get_nchildren(sib) <
nilfs_btree_node_nchildren_max(sib, btree)) {
if (nilfs_btree_node_get_nchildren(sib) < ncmax) {
path[level].bp_sib_bh = bh;
path[level].bp_op = nilfs_btree_carry_left;
stats->bs_nblocks++;
Expand All @@ -979,8 +981,7 @@ static int nilfs_btree_prepare_insert(struct nilfs_bmap *btree,
if (ret < 0)
goto err_out_child_node;
sib = (struct nilfs_btree_node *)bh->b_data;
if (nilfs_btree_node_get_nchildren(sib) <
nilfs_btree_node_nchildren_max(sib, btree)) {
if (nilfs_btree_node_get_nchildren(sib) < ncmax) {
path[level].bp_sib_bh = bh;
path[level].bp_op = nilfs_btree_carry_right;
stats->bs_nblocks++;
Expand Down Expand Up @@ -1014,7 +1015,7 @@ static int nilfs_btree_prepare_insert(struct nilfs_bmap *btree,
/* root */
node = nilfs_btree_get_root(btree);
if (nilfs_btree_node_get_nchildren(node) <
nilfs_btree_node_nchildren_max(node, btree)) {
NILFS_BTREE_ROOT_NCHILDREN_MAX) {
path[level].bp_op = nilfs_btree_do_insert;
stats->bs_nblocks++;
goto out;
Expand Down Expand Up @@ -1281,10 +1282,12 @@ static int nilfs_btree_prepare_delete(struct nilfs_bmap *btree,
struct buffer_head *bh;
struct nilfs_btree_node *node, *parent, *sib;
__u64 sibptr;
int pindex, level, ret;
int pindex, level, ncmin, ret;

ret = 0;
stats->bs_nblocks = 0;
ncmin = NILFS_BTREE_NODE_NCHILDREN_MIN(nilfs_btree_node_size(btree));

for (level = NILFS_BTREE_LEVEL_NODE_MIN;
level < nilfs_btree_height(btree) - 1;
level++) {
Expand All @@ -1297,8 +1300,7 @@ static int nilfs_btree_prepare_delete(struct nilfs_bmap *btree,
if (ret < 0)
goto err_out_child_node;

if (nilfs_btree_node_get_nchildren(node) >
nilfs_btree_node_nchildren_min(node, btree)) {
if (nilfs_btree_node_get_nchildren(node) > ncmin) {
path[level].bp_op = nilfs_btree_do_delete;
stats->bs_nblocks++;
goto out;
Expand All @@ -1315,8 +1317,7 @@ static int nilfs_btree_prepare_delete(struct nilfs_bmap *btree,
if (ret < 0)
goto err_out_curr_node;
sib = (struct nilfs_btree_node *)bh->b_data;
if (nilfs_btree_node_get_nchildren(sib) >
nilfs_btree_node_nchildren_min(sib, btree)) {
if (nilfs_btree_node_get_nchildren(sib) > ncmin) {
path[level].bp_sib_bh = bh;
path[level].bp_op = nilfs_btree_borrow_left;
stats->bs_nblocks++;
Expand All @@ -1336,8 +1337,7 @@ static int nilfs_btree_prepare_delete(struct nilfs_bmap *btree,
if (ret < 0)
goto err_out_curr_node;
sib = (struct nilfs_btree_node *)bh->b_data;
if (nilfs_btree_node_get_nchildren(sib) >
nilfs_btree_node_nchildren_min(sib, btree)) {
if (nilfs_btree_node_get_nchildren(sib) > ncmin) {
path[level].bp_sib_bh = bh;
path[level].bp_op = nilfs_btree_borrow_right;
stats->bs_nblocks++;
Expand Down

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