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btree: Moved most btree claims into lfs3_btree_commit_

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Highlighted by the gbmap work, the need for every btree commit to claim
(mark as unfetched, forcing erased-state to be rechecked) every possible
btree snapshot is tedious and error prone.

Unfortunately we can't avoid this for in-flight/stack allocated btrees,
but we can at least automatically claim the global/tracked btrees
(mtree, gbmap, and file btrees) in lfs3_btree_commit_. This makes most
btree commits just do the right thing, and hopefully minimizes the
risk of forgetting a necessary btree claim.

It also cleans up the various btree-specific claims we were doing, and
makes the codebase a bit less of a mess.

---

Also fixed bshrubs never claiming cached leaves. We now also claim
bshrubs (not just btrees), but avoid clobbering erased-state with
is-shrub checks in lfs3_btree_claim.

Code changes minor, btree claims are at least a cheap operation:

                 code          stack          ctx
  before:       37172           2352          684
  after:        37168 (-0.0%)   2352 (+0.0%)  684 (+0.0%)

                 code          stack          ctx
  gbmap before: 38996           2456          800
  gbmap after:  39000 (+0.0%)   2456 (+0.0%)  800 (+0.0%)
This commit is contained in:
Christopher Haster
2025-10-08 22:25:02 -05:00
parent 7bb7d93c9f
commit 24d75a24c5
1 changed files with 46 additions and 37 deletions
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83
lfs3.c
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@ -5160,8 +5160,13 @@ static void lfs3_btree_init(lfs3_btree_t *btree) {
// convenience operations
#if !defined(LFS3_RDONLY) && !defined(LFS3_2BONLY)
static inline void lfs3_btree_claim(lfs3_btree_t *btree) {
lfs3_rbyd_claim(&btree->r);
lfs3_rbyd_claim(&btree->leaf.r);
// note we don't claim shrubs, as this would clobber shrub estimates
if (!lfs3_rbyd_isshrub(&btree->r)) {
lfs3_rbyd_claim(&btree->r);
}
if (!lfs3_rbyd_isshrub(&btree->leaf.r)) {
lfs3_rbyd_claim(&btree->leaf.r);
}
}
#endif
@ -5179,6 +5184,38 @@ static inline int lfs3_btree_cmp(
}
#endif
// needed in lfs3_fs_claimbtree
static inline bool lfs3_o_isbshrub(uint32_t flags);
// claim all btrees known to the system
//
// note this doesn't, and can't, include any stack allocated btrees
static void lfs3_fs_claimbtree(lfs3_t *lfs3, lfs3_btree_t *btree) {
// claim the mtree
if (&lfs3->mtree != btree
&& lfs3->mtree.r.blocks[0] == btree->r.blocks[0]) {
lfs3_btree_claim(&lfs3->mtree);
}
// claim the gbmap
#ifdef LFS3_GBMAP
if (&lfs3->gbmap.b != btree
&& lfs3->gbmap.b.r.blocks[0] == btree->r.blocks[0]) {
lfs3_btree_claim(&lfs3->gbmap.b);
}
#endif
// claim file btrees/bshrubs
for (lfs3_handle_t *h = lfs3->handles; h; h = h->next) {
if (lfs3_o_isbshrub(h->flags)
&& &((lfs3_bshrub_t*)h)->shrub != btree
&& ((lfs3_bshrub_t*)h)->shrub.r.blocks[0]
== btree->r.blocks[0]) {
lfs3_btree_claim(&((lfs3_bshrub_t*)h)->shrub);
}
}
}
// branch on-disk encoding
#if !defined(LFS3_RDONLY) && !defined(LFS3_2BONLY)
@ -5617,6 +5654,13 @@ static int lfs3_btree_commit_(lfs3_t *lfs3,
lfs3_bcommit_t *bcommit) {
LFS3_ASSERT(bcommit->bid <= btree->r.weight);
// before committing, claim any matching btrees we know about
//
// is this overkill? probably, but hey, better safe than sorry,
// claiming things here reduces the chance of forgetting to claim
// things in above layers
lfs3_fs_claimbtree(lfs3, btree);
// lookup which leaf our bid resides
lfs3_rbyd_t child = btree->r;
lfs3_srid_t rid = bcommit->bid;
@ -6622,9 +6666,6 @@ static int lfs3_data_readshrub(lfs3_t *lfs3,
return 0;
}
// needed in lfs3_shrub_estimate
static inline bool lfs3_o_isbshrub(uint32_t flags);
// these are used in mdir commit/compaction
#ifndef LFS3_RDONLY
static lfs3_ssize_t lfs3_shrub_estimate(lfs3_t *lfs3,
@ -7009,24 +7050,6 @@ static int lfs3_bshrub_commitroot_(lfs3_t *lfs3, lfs3_bshrub_t *bshrub,
static int lfs3_bshrub_commit(lfs3_t *lfs3, lfs3_bshrub_t *bshrub,
lfs3_bid_t bid, const lfs3_rattr_t *rattrs, lfs3_size_t rattr_count) {
#ifndef LFS3_2BONLY
// TODO why are we marking bshrubs as unfetched here? we should either
// be marking all btrees in lfs3_btree_commit, or move this to
// lfs3_file_commit for finer control...
//
// before we touch anything, we need to mark all other btree references
// as unfetched
if (lfs3_bshrub_isbtree(bshrub)) {
for (lfs3_handle_t *h = lfs3->handles; h; h = h->next) {
if (lfs3_o_isbshrub(h->flags)
&& h != &bshrub->h
&& ((lfs3_bshrub_t*)h)->shrub.r.blocks[0]
== bshrub->shrub.r.blocks[0]) {
// mark as unfetched
lfs3_btree_claim(&((lfs3_bshrub_t*)h)->shrub);
}
}
}
// try to commit to the btree
lfs3_bcommit_t bcommit; // do _not_ fully init this
bcommit.bid = bid;
@ -9361,9 +9384,6 @@ static int lfs3_mdir_commit_(lfs3_t *lfs3, lfs3_mdir_t *mdir,
// update our mtree
} else {
// mark as unfetched in case of failure
lfs3_btree_claim(&lfs3->mtree);
err = lfs3_mtree_commit(lfs3, &mtree_,
lfs3_mbid(lfs3, mdir->mid), LFS3_RATTRS(
LFS3_RATTR_MPTR(
@ -9400,9 +9420,6 @@ static int lfs3_mdir_commit_(lfs3_t *lfs3, lfs3_mdir_t *mdir,
// how can we drop if we have no mtree?
LFS3_ASSERT(lfs3->mtree.r.weight != 0);
// mark as unfetched in case of failure
lfs3_btree_claim(&lfs3->mtree);
// update our mtree
err = lfs3_mtree_commit(lfs3, &mtree_,
lfs3_mbid(lfs3, mdir->mid), LFS3_RATTRS(
@ -9437,9 +9454,6 @@ static int lfs3_mdir_commit_(lfs3_t *lfs3, lfs3_mdir_t *mdir,
// update our mtree
} else {
// mark as unfetched in case of failure
lfs3_btree_claim(&lfs3->mtree);
err = lfs3_mtree_commit(lfs3, &mtree_,
lfs3_mbid(lfs3, mdir->mid), LFS3_RATTRS(
LFS3_RATTR_MPTR(
@ -10829,8 +10843,6 @@ static int lfs3_gbmap_set_(lfs3_t *lfs3, lfs3_btree_t *gbmap,
// temporary copy, we definitely _don't_ want to leave this in a
// weird state on error
lfs3_btree_t gbmap_ = *gbmap;
// TODO should we mark the gbmaps as unfetched as well?
// TODO should we just claim all matching btrees in lfs3_btree_commit?
// mark as unfetched in case of error
lfs3_btree_claim(gbmap);
@ -11294,9 +11306,6 @@ static int lfs3_alloc_rebuildgbmap(lfs3_t *lfs3) {
// create a copy of the gbmap
lfs3_btree_t gbmap_ = lfs3->gbmap.b;
// TODO should we just claim all matching btrees in lfs3_btree_commit?
// mark as unfetched in case of error
lfs3_btree_claim(&lfs3->gbmap.b);
// mark any in-use blocks as free
//