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Reworked lfsr_bshrub_t, renamed file.o -> file.b

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This moves all of the shrub tracking logic from lfsr_obshrub_t into
lfsr_bshrub_t, completely drops the lfsr_obshrub_t type, and changes all
lfsr_bshrub_* functions to take lfsr_bshrub_t instead of the mdir+shrub
pair.

This makes the lfsr_bshrub_* functions <-> lfsr_bshrub_t relationship
more consistent with other APIs, such as lfsr_btree_t:

  - lfsr_bshrub_lookupnext(lfs, &file->o.o.mdir, &file->o.bshrub, ...)
  + lfsr_bshrub_lookupnext(lfs, &file->b, ...)

I think the reason why this design wasn't obvious before is because, at
least conceptually, having the lfsr_mdir_t live inside the lfsr_bshrub_t
is a bit weird. It's only thanks to lfsr_file_t invasively using the
internal lfsr_mdir_t that we can avoid duplicate lfsr_mdir_t objects.

This also reorganizes the structs in lfs.h a bit, and renames the
related file.o -> file.b fields (much needed because lfs->gc.t.o.o.mdir.
rbyd.blocks was starting to get _real_ confusing).

---

Unfortunately, reducing the number of arguments to lfsr_bshrub_*
functions did not save nearly as much code as I thought it would. It
even ended up with a net _increase_ of code, apparently due to needing
to recalculate the bshrub->shrub offset more often:

           code          stack          ctx
  before: 36476           2608          640
  after:  36484 (+0.0%)   2608 (+0.0%)  640 (+0.0%)

Strange, but this rework is still worthwhile if only for the code
readability.
This commit is contained in:
Christopher Haster
2025-02-03 03:07:30 -06:00
parent fd62ef9674
commit bc639b03f2
7 changed files with 487 additions and 506 deletions
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tests/test_gc.toml
+17 -17
View File
@@ -45,7 +45,7 @@ code = '''
struct lfs_fsinfo fsinfo;
lfsr_fs_stat(&lfs, &fsinfo) => 0;
assert(fsinfo.flags & LFS_I_LOOKAHEAD);
assert(lfs.omdirs != &lfs.gc.t.o.o);
assert(lfs.omdirs != &lfs.gc.t.b.o);
// run GC until we make progress
for (lfs_block_t i = 0;; i++) {
@@ -112,11 +112,11 @@ code = '''
struct lfs_fsinfo fsinfo;
lfsr_fs_stat(&lfs, &fsinfo) => 0;
assert(fsinfo.flags & LFS_I_LOOKAHEAD);
assert(lfs.omdirs != &lfs.gc.t.o.o);
assert(lfs.omdirs != &lfs.gc.t.b.o);
// run GC one step
lfsr_fs_gc(&lfs) => 0;
assert(lfs.omdirs == &lfs.gc.t.o.o);
assert(lfs.omdirs == &lfs.gc.t.b.o);
// mutate the filesystem
lfsr_file_open(&lfs, &file, "spider",
@@ -128,7 +128,7 @@ code = '''
lfsr_file_close(&lfs, &file) => 0;
// run GC until our traversal is done
while (lfs.omdirs == &lfs.gc.t.o.o) {
while (lfs.omdirs == &lfs.gc.t.b.o) {
lfsr_fs_gc(&lfs) => 0;
}
@@ -184,7 +184,7 @@ code = '''
// hack, don't use the internals like this
uint8_t wbuf[SIZE];
while ((file.o.o.mdir.rbyd.eoff & 0x7fffffff) <= GC_COMPACT_THRESH) {
while ((file.b.o.mdir.rbyd.eoff & 0x7fffffff) <= GC_COMPACT_THRESH) {
lfsr_file_rewind(&lfs, &file) => 0;
for (lfs_size_t j = 0; j < SIZE; j++) {
wbuf[j] = 'a' + (TEST_PRNG(&prng) % 26);
@@ -197,7 +197,7 @@ code = '''
struct lfs_fsinfo fsinfo;
lfsr_fs_stat(&lfs, &fsinfo) => 0;
assert(fsinfo.flags & LFS_I_COMPACT);
assert(lfs.omdirs != &lfs.gc.t.o.o);
assert(lfs.omdirs != &lfs.gc.t.b.o);
// run GC until we make progress
for (lfs_block_t i = 0;; i++) {
@@ -213,7 +213,7 @@ code = '''
}
// mdir should have been compacted
assert((file.o.o.mdir.rbyd.eoff & 0x7fffffff) <= GC_COMPACT_THRESH);
assert((file.b.o.mdir.rbyd.eoff & 0x7fffffff) <= GC_COMPACT_THRESH);
// check we can still read the file
for (int remount = 0; remount < 2; remount++) {
@@ -273,7 +273,7 @@ code = '''
// hack, don't use the internals like this
uint8_t wbuf[SIZE];
while ((file.o.o.mdir.rbyd.eoff & 0x7fffffff) <= GC_COMPACT_THRESH) {
while ((file.b.o.mdir.rbyd.eoff & 0x7fffffff) <= GC_COMPACT_THRESH) {
lfsr_file_rewind(&lfs, &file) => 0;
for (lfs_size_t j = 0; j < SIZE; j++) {
wbuf[j] = 'a' + (TEST_PRNG(&prng) % 26);
@@ -286,19 +286,19 @@ code = '''
struct lfs_fsinfo fsinfo;
lfsr_fs_stat(&lfs, &fsinfo) => 0;
assert(fsinfo.flags & LFS_I_COMPACT);
assert(lfs.omdirs != &lfs.gc.t.o.o);
assert(lfs.omdirs != &lfs.gc.t.b.o);
// run GC one traversal + one step
while (true) {
lfsr_fs_gc(&lfs) => 0;
// internal traversal done?
if (lfs.omdirs != &lfs.gc.t.o.o) {
if (lfs.omdirs != &lfs.gc.t.b.o) {
break;
}
}
lfsr_fs_gc(&lfs) => 0;
assert(lfs.omdirs == &lfs.gc.t.o.o);
assert(lfs.omdirs == &lfs.gc.t.b.o);
// mutate the filesystem
lfsr_file_rewind(&lfs, &file) => 0;
@@ -309,7 +309,7 @@ code = '''
lfsr_file_sync(&lfs, &file) => 0;
// run GC until our traversal is done (twice for compact)
while (lfs.omdirs == &lfs.gc.t.o.o) {
while (lfs.omdirs == &lfs.gc.t.b.o) {
lfsr_fs_gc(&lfs) => 0;
}
@@ -407,7 +407,7 @@ code = '''
struct lfs_fsinfo fsinfo;
lfsr_fs_stat(&lfs, &fsinfo) => 0;
assert(fsinfo.flags & LFS_I_MKCONSISTENT);
assert(lfs.omdirs != &lfs.gc.t.o.o);
assert(lfs.omdirs != &lfs.gc.t.b.o);
// run GC until we make progress
for (lfs_block_t i = 0;; i++) {
@@ -507,7 +507,7 @@ code = '''
lfsr_fs_stat(&lfs, &fsinfo) => 0;
assert(fsinfo.flags & LFS_I_MKCONSISTENT);
#ifdef LFS_GC
assert(lfs.omdirs != &lfs.gc.t.o.o);
assert(lfs.omdirs != &lfs.gc.t.b.o);
#endif
// call lfsr_fs_mkconsistent
@@ -605,9 +605,9 @@ code = '''
}
// run GC one step
assert(lfs.omdirs != &lfs.gc.t.o.o);
assert(lfs.omdirs != &lfs.gc.t.b.o);
lfsr_fs_gc(&lfs) => 0;
assert(lfs.omdirs == &lfs.gc.t.o.o);
assert(lfs.omdirs == &lfs.gc.t.b.o);
// create the rest of the orphans after GC has started
for (lfs_size_t i = 0; i < ORPHANS; i++) {
@@ -626,7 +626,7 @@ code = '''
assert(fsinfo.flags & LFS_I_MKCONSISTENT);
// run GC until our traversal is done
while (lfs.omdirs == &lfs.gc.t.o.o) {
while (lfs.omdirs == &lfs.gc.t.b.o) {
lfsr_fs_gc(&lfs) => 0;
}