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gbmap: Adopted lfs3_alloc_zerogbmap over lfs3_gbmap_remap

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These are more-or-less equivalent, but:

- Making lfs3_alloc_zerogbmap a non-gbmap function avoids awkward
  conversations about why it's not atomic.

- Making lfs3_alloc_zerogbmap alloc-specific makes room for pererased-
  specific zeroing operations that we might need when adopt bmerased
  ranges (future).

No code changes, which means const-propagation works as expected:

                 code          stack          ctx
  before:       37208           2352          688
  after:        37208 (+0.0%)   2352 (+0.0%)  688 (+0.0%)

                 code          stack          ctx
  gbmap before: 40120           2368          856
  gbmap after:  40120 (+0.0%)   2368 (+0.0%)  856 (+0.0%)
This commit is contained in:
Christopher Haster
2025-10-18 17:41:47 -05:00
parent 406fbe785e
commit 0a8ac0994c
1 changed files with 33 additions and 38 deletions
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71
lfs3.c
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@ -10613,8 +10613,7 @@ eot:;
static int lfs3_mdir_mkconsistent(lfs3_t *lfs3, lfs3_mdir_t *mdir);
static inline void lfs3_alloc_ckpoint_(lfs3_t *lfs3);
static void lfs3_alloc_adopt(lfs3_t *lfs3, lfs3_block_t known);
static int lfs3_gbmap_remap(lfs3_t *lfs3, lfs3_btree_t *gbmap,
lfs3_tag_t tag, lfs3_tag_t tag_);
static int lfs3_alloc_zerogbmap(lfs3_t *lfs3, lfs3_btree_t *gbmap);
static int lfs3_gbmap_markbptr(lfs3_t *lfs3, lfs3_btree_t *gbmap,
lfs3_tag_t tag, const lfs3_bptr_t *bptr,
lfs3_tag_t tag_);
@ -10668,9 +10667,7 @@ static lfs3_stag_t lfs3_mtree_gc(lfs3_t *lfs3, lfs3_mgc_t *mgc,
// we do this instead of creating a new gbmap to (1) preserve any
// erased/bad info and (2) try to best use any available
// erased-state
int err = lfs3_gbmap_remap(lfs3, &mgc->gbmap_,
LFS3_TAG_BMINUSE,
LFS3_TAG_BMFREE);
int err = lfs3_alloc_zerogbmap(lfs3, &mgc->gbmap_);
if (err) {
return err;
}
@ -11085,36 +11082,6 @@ static int lfs3_gbmap_markbptr(lfs3_t *lfs3, lfs3_btree_t *gbmap,
}
#endif
#if !defined(LFS3_RDONLY) && defined(LFS3_GBMAP)
// not this is not completely atomic, but worst case we just end up with
// only some ranges remapped
static int lfs3_gbmap_remap(lfs3_t *lfs3, lfs3_btree_t *gbmap,
lfs3_tag_t tag, lfs3_tag_t tag_) {
lfs3_block_t block__ = -1;
while (true) {
lfs3_block_t weight__;
lfs3_stag_t tag__ = lfs3_gbmap_lookupnext(lfs3, gbmap, block__+1,
&block__, &weight__);
if (tag__ < 0) {
if (tag__ == LFS3_ERR_NOENT) {
break;
}
return tag__;
}
if (tag__ == tag) {
int err = lfs3_gbmap_mark_(lfs3, gbmap, block__, weight__,
tag_);
if (err) {
return err;
}
}
}
return 0;
}
#endif
/// Block allocator ///
@ -11491,6 +11458,36 @@ static lfs3_sblock_t lfs3_alloc(lfs3_t *lfs3, uint32_t flags) {
}
#endif
#if !defined(LFS3_RDONLY) && defined(LFS3_GBMAP)
// note this is not completely atomic, but worst case we just end up with
// only some ranges zeroed
static int lfs3_alloc_zerogbmap(lfs3_t *lfs3, lfs3_btree_t *gbmap) {
lfs3_block_t block__ = -1;
while (true) {
lfs3_block_t weight__;
lfs3_stag_t tag__ = lfs3_gbmap_lookupnext(lfs3, gbmap, block__+1,
&block__, &weight__);
if (tag__ < 0) {
if (tag__ == LFS3_ERR_NOENT) {
break;
}
return tag__;
}
// mark in-use ranges as free
if (tag__ == LFS3_TAG_BMINUSE) {
int err = lfs3_gbmap_mark_(lfs3, gbmap, block__, weight__,
LFS3_TAG_BMFREE);
if (err) {
return err;
}
}
}
return 0;
}
#endif
#if !defined(LFS3_RDONLY) && defined(LFS3_GBMAP)
static void lfs3_alloc_adoptgbmap(lfs3_t *lfs3,
const lfs3_btree_t *gbmap, lfs3_block_t known) {
@ -11517,9 +11514,7 @@ static int lfs3_alloc_repopgbmap(lfs3_t *lfs3) {
// we do this instead of creating a new gbmap to (1) preserve any
// erased/bad info and (2) try to best use any available
// erased-state
int err = lfs3_gbmap_remap(lfs3, &gbmap_,
LFS3_TAG_BMINUSE,
LFS3_TAG_BMFREE);
int err = lfs3_alloc_zerogbmap(lfs3, &gbmap_);
if (err) {
goto failed;
}