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btree: Adopted LFS3_ERR_EXIST for terminating at shrubs

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A bit of an abuse of this error code, but this is more explicit than the
previous rattr_count > 0 condition.

Forgetting to set rattr_count=0 on a normal exit has introduced bugs
before.

---

Though I'm not sure why this adds code. Somehow, _removing_ the
rattr_count=0 statements when lfs3_btree_commit_ collapses the root
added code?

           code          stack          ctx
  before: 36996           2392          652
  after:  37020 (+0.1%)   2392 (+0.0%)  652 (+0.0%)

Seriously, add bcommit->rattr_count = 0 to lfs3_btree_commit_ and the
lfs3_btree_commit_'s code cost shrinks by 8 bytes. Is the compiler
hiding stuff in bcommit?

I'm just going to chalk this up to compiler noise for now...
This commit is contained in:
Christopher Haster
2025-07-15 20:46:12 -05:00
parent 6d003543d8
commit 3e47304e9b
1 changed files with 13 additions and 17 deletions
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lfs3.c
+13 -17
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@@ -5457,8 +5457,8 @@ static inline uint32_t lfs3_rev_btree(lfs3_t *lfs3);
// core btree algorithm
//
// this commits up to the root, but stops if:
// 1. we need a new root
// 2. we have a shrub root
// 1. we need a new root => LFS3_ERR_RANGE
// 2. we have a shrub root => LFS3_ERR_EXIST
//
// ---
//
@@ -5531,7 +5531,9 @@ static int lfs3_btree_commit_(lfs3_t *lfs3,
if (!lfs3_rbyd_trunk(&child)
|| lfs3_rbyd_isshrub(btree)) {
bcommit->bid = rid;
return (!lfs3_rbyd_trunk(&child)) ? LFS3_ERR_RANGE : 0;
return (!lfs3_rbyd_trunk(&child))
? LFS3_ERR_RANGE
: LFS3_ERR_EXIST;
}
// mark btree as unerased in case of failure, our btree rbyd and
@@ -5584,8 +5586,6 @@ static int lfs3_btree_commit_(lfs3_t *lfs3,
if (!lfs3_rbyd_trunk(&parent)) {
// update the root
// (note btree_ == child_)
// no new root needed
bcommit->rattr_count = 0;
return 0;
}
@@ -5593,8 +5593,6 @@ static int lfs3_btree_commit_(lfs3_t *lfs3,
if (child.weight == btree->weight) {
// collapse the root, decreasing the height of the tree
// (note btree_ == child_)
// no new root needed
bcommit->rattr_count = 0;
return 0;
}
@@ -6066,8 +6064,6 @@ static int lfs3_btree_commit_(lfs3_t *lfs3,
if (child.weight+sibling.weight == btree->weight) {
// collapse the root, decreasing the height of the tree
// (note btree_ == child_)
// no new root needed
bcommit->rattr_count = 0;
return 0;
}
@@ -6165,13 +6161,12 @@ static int lfs3_btree_commit(lfs3_t *lfs3, lfs3_btree_t *btree,
int err = lfs3_btree_commit_(lfs3, &btree_, btree,
&bcommit);
if (err && err != LFS3_ERR_RANGE) {
LFS3_ASSERT(err != LFS3_ERR_EXIST);
return err;
}
// needs a new root?
if (err == LFS3_ERR_RANGE) {
LFS3_ASSERT(bcommit.rattr_count > 0);
err = lfs3_btree_commitroot_(lfs3, &btree_, btree, true,
bcommit.bid, bcommit.rattrs, bcommit.rattr_count);
if (err) {
@@ -6913,15 +6908,16 @@ static int lfs3_bshrub_commit(lfs3_t *lfs3, lfs3_bshrub_t *bshrub,
bcommit.rattr_count = rattr_count;
int err = lfs3_btree_commit_(lfs3, &bshrub->shrub_, &bshrub->shrub,
&bcommit);
if (err && err != LFS3_ERR_RANGE) {
if (err && err != LFS3_ERR_EXIST
&& err != LFS3_ERR_RANGE) {
return err;
}
LFS3_ASSERT(!err || bcommit.rattr_count > 0);
bool split = (err == LFS3_ERR_RANGE);
// when btree is shrubbed, lfs3_btree_commit_ stops at the root
// and returns with pending rattrs
if (bcommit.rattr_count > 0) {
if (err == LFS3_ERR_EXIST
|| err == LFS3_ERR_RANGE) {
// try to commit to shrub root
err = lfs3_bshrub_commitroot_(lfs3, bshrub, split,
bcommit.bid, bcommit.rattrs, bcommit.rattr_count);
@@ -9609,9 +9605,9 @@ static inline bool lfs3_path_isdir(const char *path) {
//
// the errors get a bit subtle here, and rely on what ends up in the
// path/mdir:
// - 0 => file found
// - 0, lfs3_path_isdir(path) => dir found
// - 0, mdir.mid=-1 => root found
// - 0 => file found
// - 0, lfs3_path_isdir(path) => dir found
// - 0, mdir.mid=-1 => root found
// - LFS3_ERR_NOENT, lfs3_path_islast(path) => file not found
// - LFS3_ERR_NOENT, !lfs3_path_islast(path) => parent not found
// - LFS3_ERR_NOTDIR => parent not a dir