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Simplified lfsr_mtree_t now that we don't need to represent msprouts

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We had to be a bit clever with our lfsr_mtree_t representation to
support msprouts. Now that we don't support msprouts, we can simplify
this and drop the lfsr_mtree_t type completely! which is nice for both
code cost and readability.

Saves a bit more code:

           code          stack          ctx
  before: 38344           2624          640
  after:  38284 (-0.2%)   2624 (+0.0%)  640 (+0.0%)

Which increases the total savings of dropping msprouts:

                 code          stack          ctx
  yes msprouts: 38508           2624          640
  no msprouts:  38284 (-0.6%)   2624 (+0.0%)  640 (+0.0%)
This commit is contained in:
Christopher Haster
2025-01-30 03:35:07 -06:00
parent 3f4984d33f
commit 01f2d613bd
4 changed files with 133 additions and 191 deletions
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lfs.c
+29 -74
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@@ -4756,6 +4756,7 @@ static lfs_scmp_t lfsr_rbyd_namelookup(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
// create an empty btree
static void lfsr_btree_init(lfsr_btree_t *btree) {
btree->weight = 0;
btree->blocks[0] = -1;
btree->trunk = 0;
}
@@ -7439,55 +7440,9 @@ static int lfsr_mdir_suplookup(lfs_t *lfs, const lfsr_mdir_t *mdir,
/// Metadata-tree things ///
// the mtree is the core tree of mdirs in littlefs
#define LFSR_MTREE_ISMPTR 0x80000000
// create an empty mtree
static void lfsr_mtree_init(lfsr_mtree_t *mtree) {
mtree->u.weight = LFSR_MTREE_ISMPTR | 0;
}
// create an mtree with a single mdir
static void lfsr_mtree_frommptr(lfsr_mtree_t *mtree,
const lfs_block_t mptr[static 2],
lfsr_mid_t weight) {
mtree->u.mptr.weight = LFSR_MTREE_ISMPTR | weight;
mtree->u.mptr.blocks[0] = mptr[0];
mtree->u.mptr.blocks[1] = mptr[1];
}
static inline bool lfsr_mtree_isnull(const lfsr_mtree_t *mtree) {
return mtree->u.weight == (LFSR_MTREE_ISMPTR | 0);
}
static inline bool lfsr_mtree_ismptr(const lfsr_mtree_t *mtree) {
return mtree->u.weight & LFSR_MTREE_ISMPTR;
}
static inline bool lfsr_mtree_isbtree(const lfsr_mtree_t *mtree) {
return !(mtree->u.weight & LFSR_MTREE_ISMPTR);
}
static inline lfsr_mid_t lfsr_mtree_weight_(const lfsr_mtree_t *mtree) {
return mtree->u.weight & ~LFSR_MTREE_ISMPTR;
}
static inline int lfsr_mtree_cmp(
const lfsr_mtree_t *a,
const lfsr_mtree_t *b) {
if (a->u.weight != b->u.weight) {
return a->u.weight - b->u.weight;
} else if (lfsr_mtree_isnull(a)) {
return 0;
} else {
return lfsr_btree_cmp(&a->u.btree, &b->u.btree);
}
}
static inline lfsr_mid_t lfsr_mtree_weight(lfs_t *lfs) {
return lfs_max(
lfsr_mtree_weight_(&lfs->mtree),
lfs->mtree.weight,
1 << lfs->mdir_bits);
}
@@ -7502,7 +7457,7 @@ static int lfsr_mtree_lookup(lfs_t *lfs, lfsr_smid_t mid,
}
// looking up mroot?
if (lfsr_mtree_isnull(&lfs->mtree)) {
if (lfs->mtree.weight == 0) {
mdir_->mid = mid;
lfsr_mdir_sync(mdir_, &lfs->mroot);
return 0;
@@ -7512,7 +7467,7 @@ static int lfsr_mtree_lookup(lfs_t *lfs, lfsr_smid_t mid,
lfsr_bid_t bid;
lfsr_tag_t tag;
lfsr_data_t data;
int err = lfsr_btree_lookupnext(lfs, &lfs->mtree.u.btree, mid,
int err = lfsr_btree_lookupnext(lfs, &lfs->mtree, mid,
&bid, &tag, NULL, &data);
if (err) {
LFS_ASSERT(err != LFS_ERR_NOENT);
@@ -8512,13 +8467,13 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir,
}
// handle possible mtree updates, this gets a bit messy
lfsr_mtree_t mtree_ = lfs->mtree;
lfsr_btree_t mtree_ = lfs->mtree;
lfsr_smid_t mdelta = 0;
// need to split?
if (err == LFS_ERR_RANGE) {
// this should not happen unless we can't fit our mroot's metadata
LFS_ASSERT(lfsr_mdir_cmp(mdir, &lfs->mroot) != 0
|| lfsr_mtree_isnull(&lfs->mtree));
|| lfs->mtree.weight == 0);
// if we're not the mroot, we need to consume the gstate so
// we don't lose any info during the split
@@ -8634,11 +8589,11 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir,
}
// new mtree?
if (lfsr_mtree_weight_(&lfs->mtree) == 0) {
lfsr_btree_init(&mtree_.u.btree);
if (lfs->mtree.weight == 0) {
lfsr_btree_init(&mtree_);
uint8_t mdir_buf[2*LFSR_MPTR_DSIZE];
err = lfsr_btree_commit(lfs, &mtree_.u.btree,
err = lfsr_btree_commit(lfs, &mtree_,
0, LFSR_RATS(
LFSR_RAT(
LFSR_TAG_MDIR, +(1 << lfs->mdir_bits),
@@ -8660,10 +8615,10 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir,
// update our mtree
} else {
// mark as unerased in case of failure
lfs->mtree.u.btree.eoff = -1;
lfs->mtree.eoff = -1;
uint8_t mdir_buf[2*LFSR_MPTR_DSIZE];
err = lfsr_btree_commit(lfs, &mtree_.u.btree,
err = lfsr_btree_commit(lfs, &mtree_,
lfsr_mid_bid(lfs, mdir->mid), LFSR_RATS(
LFSR_RAT(
LFSR_TAG_MDIR, 0,
@@ -8701,13 +8656,13 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir,
mdelta = -(1 << lfs->mdir_bits);
// how can we drop if we have no mtree?
LFS_ASSERT(lfsr_mtree_weight_(&lfs->mtree) != 0);
LFS_ASSERT(lfs->mtree.weight != 0);
// mark as unerased in case of failure
lfs->mtree.u.btree.eoff = -1;
lfs->mtree.eoff = -1;
// update our mtree
err = lfsr_btree_commit(lfs, &mtree_.u.btree,
err = lfsr_btree_commit(lfs, &mtree_,
lfsr_mid_bid(lfs, mdir->mid), LFSR_RATS(
LFSR_RAT(
LFSR_TAG_RM, -(1 << lfs->mdir_bits),
@@ -8727,11 +8682,11 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir,
relocated:;
// new mtree?
if (lfsr_mtree_weight_(&lfs->mtree) == 0) {
lfsr_btree_init(&mtree_.u.btree);
if (lfs->mtree.weight == 0) {
lfsr_btree_init(&mtree_);
uint8_t mdir_buf[LFSR_MPTR_DSIZE];
err = lfsr_btree_commit(lfs, &mtree_.u.btree,
err = lfsr_btree_commit(lfs, &mtree_,
0, LFSR_RATS(
LFSR_RAT(
LFSR_TAG_MDIR, +(1 << lfs->mdir_bits),
@@ -8745,10 +8700,10 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir,
// update our mtree
} else {
// mark as unerased in case of failure
lfs->mtree.u.btree.eoff = -1;
lfs->mtree.eoff = -1;
uint8_t mdir_buf[LFSR_MPTR_DSIZE];
err = lfsr_btree_commit(lfs, &mtree_.u.btree,
err = lfsr_btree_commit(lfs, &mtree_,
lfsr_mid_bid(lfs, mdir->mid), LFSR_RATS(
LFSR_RAT(
LFSR_TAG_MDIR, 0,
@@ -8777,9 +8732,9 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir,
}
// need to update mtree?
if (lfsr_mtree_cmp(&mtree_, &lfs->mtree) != 0) {
if (lfsr_btree_cmp(&mtree_, &lfs->mtree) != 0) {
// mtree should never go to zero since we always have a root bookmark
LFS_ASSERT(lfsr_mtree_weight_(&mtree_) > 0);
LFS_ASSERT(mtree_.weight > 0);
// make sure mtree/mroot changes are on-disk before committing
// metadata
@@ -8810,7 +8765,7 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir,
-1, LFSR_RATS(
LFSR_RAT(
LFSR_TAG_SUB | LFSR_TAG_MTREE, 0,
LFSR_DATA_BTREE(&mtree_.u.btree, mtree_buf)),
LFSR_DATA_BTREE(&mtree_, mtree_buf)),
// were we committing to the mroot? include any -1 rats
(mdir->mid == -1)
? LFSR_RAT_RATS(
@@ -8985,7 +8940,7 @@ static int lfsr_mdir_commit(lfs_t *lfs, lfsr_mdir_t *mdir,
// if mroot/mtree changed, clobber any mroot/mtree traversals
if (lfsr_mdir_cmp(&mroot_, &lfs->mroot) != 0
|| lfsr_mtree_cmp(&mtree_, &lfs->mtree) != 0) {
|| lfsr_btree_cmp(&mtree_, &lfs->mtree) != 0) {
for (lfsr_omdir_t *o = lfs->omdirs; o; o = o->next) {
if (lfsr_o_type(o->flags) == LFS_TYPE_TRAVERSAL
&& o->mdir.mid == -1
@@ -9126,7 +9081,7 @@ static int lfsr_mtree_namelookup(lfs_t *lfs,
lfsr_mdir_t *mdir_, lfsr_tag_t *tag_, lfsr_data_t *data_) {
// do we only have mroot?
lfsr_mdir_t mdir;
if (lfsr_mtree_isnull(&lfs->mtree)) {
if (lfs->mtree.weight == 0) {
mdir = lfs->mroot;
// treat inlined mdir as mid=0
mdir.mid = 0;
@@ -9137,7 +9092,7 @@ static int lfsr_mtree_namelookup(lfs_t *lfs,
lfsr_tag_t tag;
lfsr_bid_t weight;
lfsr_data_t data;
lfs_scmp_t cmp = lfsr_btree_namelookup(lfs, &lfs->mtree.u.btree,
lfs_scmp_t cmp = lfsr_btree_namelookup(lfs, &lfs->mtree,
did, name, name_len,
&bid, &tag, &weight, &data);
if (cmp < 0) {
@@ -14054,7 +14009,7 @@ static int lfsr_mountinited(lfs_t *lfs) {
// default to no mtree, this is allowed and implies all files are inlined
// in the mroot
lfsr_mtree_init(&lfs->mtree);
lfsr_btree_init(&lfs->mtree);
// zero gcksum/gdeltas, we'll read these from our mdirs
lfs->gcksum = 0;
@@ -14137,8 +14092,8 @@ static int lfsr_mountinited(lfs_t *lfs) {
} else if (tag == LFSR_TAG_BRANCH) {
lfsr_rbyd_t *rbyd = (lfsr_rbyd_t*)bptr.data.u.buffer;
// found the root of the mtree? keep track of this
if (lfsr_mtree_isnull(&lfs->mtree)) {
lfs->mtree.u.btree = *rbyd;
if (lfs->mtree.weight == 0) {
lfs->mtree = *rbyd;
}
} else {
@@ -14299,7 +14254,7 @@ int lfsr_mount(lfs_t *lfs, uint32_t flags,
lfs->mroot.rbyd.blocks[0],
lfs->mroot.rbyd.blocks[1],
lfsr_rbyd_trunk(&lfs->mroot.rbyd),
lfsr_mtree_weight_(&lfs->mtree) >> lfs->mdir_bits,
lfs->mtree.weight >> lfs->mdir_bits,
1 << lfs->mdir_bits,
lfs->gcksum);