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trv: Reduced LFS3_t_CKPOINTED + LFS3_t_MUTATED -> LFS3_t_CKPOINTED

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This drops LFS3_t_MUTATED in favor of just using LFS3_t_CKPOINTED
everywhere:

1. These meant roughly the same thing, with LFS3_t_MUTATED being a bit
   tighter at the cost of needing to be explicitly set.

2. The implicit setting of LFS3_t_CKPOINTED by lfs3_alloc_ckpoint -- a
   function that already needs to be called before mutation -- means we
   have one less thing to worry about.

   Implicit properties like LFS3_t_CKPOINTED are great for building a
   reliable system. Manual flags like LFS3_t_MUTATED, not so much.

3. Why use two flags when we can get away with one?

The only downside is we may unnecessarily clobber gc/traversal work when
we don't actually mutate the filesystem. Failed file open calls are a
good example.

However this tradeoff seems well worth it for an overall simpler +
more reliable system.

---

Saves a bit of code:

                 code          stack          ctx
  before:       37220           2352          688
  after:        37160 (-0.2%)   2352 (+0.0%)  688 (+0.0%)

                 code          stack          ctx
  gbmap before: 40184           2368          856
  gbmap after:  40132 (-0.1%)   2368 (+0.0%)  856 (+0.0%)
This commit is contained in:
Christopher Haster
2025-10-20 15:35:03 -05:00
parent 5d70e47708
commit 8a58954828
4 changed files with 22 additions and 53 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lfs3.c
+13 -45
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@@ -7476,10 +7476,6 @@ static inline bool lfs3_t_isdirty(uint32_t flags) {
return flags & LFS3_t_DIRTY;
}
static inline bool lfs3_t_ismutated(uint32_t flags) {
return flags & LFS3_t_MUTATED;
}
static inline bool lfs3_t_isckpointed(uint32_t flags) {
return flags & LFS3_t_CKPOINTED;
}
@@ -7668,27 +7664,6 @@ static void lfs3_handle_clobber(lfs3_t *lfs3, const lfs3_handle_t *h) {
}
#endif
// mark all traversals as mutated
#ifndef LFS3_RDONLY
static void lfs3_fs_mutate(lfs3_t *lfs3) {
for (lfs3_handle_t *h_ = lfs3->handles; h_; h_ = h_->next) {
if (lfs3_o_type(h_->flags) == LFS3_type_TRV) {
// mark as dirty + mutated, self-mutating traversals should
// clear the dirty bit
h_->flags |= LFS3_t_DIRTY | LFS3_t_MUTATED;
}
}
}
#endif
// mark as mutated and clobber any traversals referencing a handle
#ifndef LFS3_RDONLY
static void lfs3_handle_mutate(lfs3_t *lfs3, const lfs3_handle_t *h) {
lfs3_handle_clobber(lfs3, h);
lfs3_fs_mutate(lfs3);
}
#endif
/// Global-state things ///
@@ -9783,9 +9758,6 @@ static int lfs3_mdir_commit_(lfs3_t *lfs3, lfs3_mdir_t *mdir,
// update any gstate changes
lfs3_fs_commitgdelta(lfs3);
// mark all traversals as mutated
lfs3_fs_mutate(lfs3);
// we may have touched any number of mdirs, so assume uncompacted
// until lfs3_fs_gc can prove otherwise
lfs3->flags |= LFS3_I_COMPACTMETA;
@@ -10595,8 +10567,7 @@ eot:;
// compare gcksum with in-RAM gcksum
if ((lfs3_t_isckmeta(mtrv->b.h.flags)
|| lfs3_t_isckdata(mtrv->b.h.flags))
&& !lfs3_t_isdirty(mtrv->b.h.flags)
&& !lfs3_t_ismutated(mtrv->b.h.flags)
&& !lfs3_t_isckpointed(mtrv->b.h.flags)
&& mtrv->gcksum != lfs3->gcksum) {
LFS3_ERROR("Found gcksum mismatch, cksum %08"PRIx32" (!= %08"PRIx32")",
mtrv->gcksum,
@@ -10609,14 +10580,12 @@ eot:;
if ((lfs3_t_isckmeta(mtrv->b.h.flags)
|| lfs3_t_isckdata(mtrv->b.h.flags))
&& !lfs3_t_ismtreeonly(mtrv->b.h.flags)
&& !lfs3_t_isdirty(mtrv->b.h.flags)
&& !lfs3_t_ismutated(mtrv->b.h.flags)) {
&& !lfs3_t_isckpointed(mtrv->b.h.flags)) {
lfs3->flags &= ~LFS3_I_CKMETA;
}
if (lfs3_t_isckdata(mtrv->b.h.flags)
&& !lfs3_t_ismtreeonly(mtrv->b.h.flags)
&& !lfs3_t_isdirty(mtrv->b.h.flags)
&& !lfs3_t_ismutated(mtrv->b.h.flags)) {
&& !lfs3_t_isckpointed(mtrv->b.h.flags)) {
lfs3->flags &= ~LFS3_I_CKDATA;
}
@@ -10650,7 +10619,7 @@ static lfs3_stag_t lfs3_mtree_gc(lfs3_t *lfs3, lfs3_mgc_t *mgc,
&& !lfs3_t_isckpointed(mgc->t.b.h.flags)) {
lfs3_alloc_ckpoint_(lfs3);
// keep our own ckpointed flag clear
mgc->t.b.h.flags &= ~LFS3_t_CKPOINTED;
mgc->t.b.h.flags &= ~LFS3_t_CKPOINTED & ~LFS3_t_DIRTY;
}
#endif
@@ -10687,7 +10656,7 @@ static lfs3_stag_t lfs3_mtree_gc(lfs3_t *lfs3, lfs3_mgc_t *mgc,
}
// keep our own ckpointed flag clear
mgc->t.b.h.flags &= ~LFS3_t_CKPOINTED;
mgc->t.b.h.flags &= ~LFS3_t_CKPOINTED & ~LFS3_t_DIRTY;
}
#endif
}
@@ -10825,7 +10794,7 @@ eot:;
// was compaction successful? note we may need multiple passes if
// we want to be sure everything is compacted
if (lfs3_t_compactmeta(mgc->t.b.h.flags)
&& !lfs3_t_ismutated(mgc->t.b.h.flags)) {
&& !lfs3_t_isckpointed(mgc->t.b.h.flags)) {
lfs3->flags &= ~LFS3_I_COMPACTMETA;
}
#endif
@@ -11113,11 +11082,11 @@ static inline void lfs3_alloc_ckpoint_(lfs3_t *lfs3) {
// set ckpoint = disk size
lfs3->lookahead.ckpoint = lfs3->block_count;
// mark all traversals as ckpointed
// TODO should this be a function? non-clobbering?
// mark all traversals as ckpointed + dirty, self-mutating
// traversals should clear the dirty bit
for (lfs3_handle_t *h = lfs3->handles; h; h = h->next) {
if (lfs3_o_type(h->flags) == LFS3_type_TRV) {
h->flags |= LFS3_t_CKPOINTED;
h->flags |= LFS3_t_CKPOINTED | LFS3_t_DIRTY;
}
}
}
@@ -14395,7 +14364,7 @@ lfs3_ssize_t lfs3_file_write(lfs3_t *lfs3, lfs3_file_t *file,
}
// clobber entangled traversals
lfs3_handle_mutate(lfs3, &file->b.h);
lfs3_handle_clobber(lfs3, &file->b.h);
// mark as unsynced in case we fail
file->b.h.flags |= LFS3_o_UNSYNC;
@@ -14539,7 +14508,7 @@ int lfs3_file_flush(lfs3_t *lfs3, lfs3_file_t *file) {
#ifndef LFS3_RDONLY
// clobber entangled traversals
lfs3_handle_mutate(lfs3, &file->b.h);
lfs3_handle_clobber(lfs3, &file->b.h);
int err;
// flush our cache
@@ -15045,7 +15014,7 @@ int lfs3_file_truncate(lfs3_t *lfs3, lfs3_file_t *file, lfs3_off_t size_) {
}
// clobber entangled traversals
lfs3_handle_mutate(lfs3, &file->b.h);
lfs3_handle_clobber(lfs3, &file->b.h);
// mark as unsynced in case we fail
file->b.h.flags |= LFS3_o_UNSYNC;
@@ -15138,7 +15107,7 @@ int lfs3_file_fruncate(lfs3_t *lfs3, lfs3_file_t *file, lfs3_off_t size_) {
}
// clobber entangled traversals
lfs3_handle_mutate(lfs3, &file->b.h);
lfs3_handle_clobber(lfs3, &file->b.h);
// mark as unsynced in case we fail
file->b.h.flags |= LFS3_o_UNSYNC;
@@ -17560,7 +17529,6 @@ static int lfs3_trv_rewind_(lfs3_t *lfs3, lfs3_trv_t *trv) {
lfs3_mgc_init(&trv->gc,
trv->gc.t.b.h.flags
& ~LFS3_t_DIRTY
& ~LFS3_t_MUTATED
& ~LFS3_t_CKPOINTED
& ~LFS3_t_TSTATE);