UBIFS: improve znode splitting rules
When inserting into a full znode it is split into two
znodes. Because data node keys are usually consecutive,
it is better to try to keep them together. This patch
does a better job of that.
Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index 66dc571..e0878a4 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -1962,7 +1962,7 @@
{
struct ubifs_znode *zn, *zi, *zp;
int i, keep, move, appending = 0;
- union ubifs_key *key = &zbr->key;
+ union ubifs_key *key = &zbr->key, *key1;
ubifs_assert(n >= 0 && n <= c->fanout);
@@ -2003,20 +2003,33 @@
zn->level = znode->level;
/* Decide where to split */
- if (znode->level == 0 && n == c->fanout &&
- key_type(c, key) == UBIFS_DATA_KEY) {
- union ubifs_key *key1;
-
- /*
- * If this is an inode which is being appended - do not split
- * it because no other zbranches can be inserted between
- * zbranches of consecutive data nodes anyway.
- */
- key1 = &znode->zbranch[n - 1].key;
- if (key_inum(c, key1) == key_inum(c, key) &&
- key_type(c, key1) == UBIFS_DATA_KEY &&
- key_block(c, key1) == key_block(c, key) - 1)
- appending = 1;
+ if (znode->level == 0 && key_type(c, key) == UBIFS_DATA_KEY) {
+ /* Try not to split consecutive data keys */
+ if (n == c->fanout) {
+ key1 = &znode->zbranch[n - 1].key;
+ if (key_inum(c, key1) == key_inum(c, key) &&
+ key_type(c, key1) == UBIFS_DATA_KEY)
+ appending = 1;
+ } else
+ goto check_split;
+ } else if (appending && n != c->fanout) {
+ /* Try not to split consecutive data keys */
+ appending = 0;
+check_split:
+ if (n >= (c->fanout + 1) / 2) {
+ key1 = &znode->zbranch[0].key;
+ if (key_inum(c, key1) == key_inum(c, key) &&
+ key_type(c, key1) == UBIFS_DATA_KEY) {
+ key1 = &znode->zbranch[n].key;
+ if (key_inum(c, key1) != key_inum(c, key) ||
+ key_type(c, key1) != UBIFS_DATA_KEY) {
+ keep = n;
+ move = c->fanout - keep;
+ zi = znode;
+ goto do_split;
+ }
+ }
+ }
}
if (appending) {
@@ -2046,6 +2059,8 @@
zbr->znode->parent = zn;
}
+do_split:
+
__set_bit(DIRTY_ZNODE, &zn->flags);
atomic_long_inc(&c->dirty_zn_cnt);
@@ -2072,14 +2087,11 @@
/* Insert new znode (produced by spitting) into the parent */
if (zp) {
- i = n;
+ if (n == 0 && zi == znode && znode->iip == 0)
+ correct_parent_keys(c, znode);
+
/* Locate insertion point */
n = znode->iip + 1;
- if (appending && n != c->fanout)
- appending = 0;
-
- if (i == 0 && zi == znode && znode->iip == 0)
- correct_parent_keys(c, znode);
/* Tail recursion */
zbr->key = zn->zbranch[0].key;