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Dropped lfsr_mtree_seek for explicit mtree lookups

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lfsr_mtree_seek is a bit of an odd function, a hammer for too many
nails.

Using lfsr_mtree_lookup directly with manual mdir.mid manipulation gives
the internal layers more flexibility and room for optimizations.

Code changes:

           code          stack
  before: 34426           2624
  after:  34406 (-0.1%)   2624 (+0.0%)
This commit is contained in:
Christopher Haster
2024-06-21 10:58:50 -05:00
parent 4a5de70b00
commit ec44831381
2 changed files with 136 additions and 133 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lfs.c
+116 -129
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@@ -6045,38 +6045,6 @@ static int lfsr_mtree_lookup(lfs_t *lfs, lfsr_smid_t mid,
}
}
static int lfsr_mtree_seek(lfs_t *lfs, lfsr_mdir_t *mdir, lfs_off_t off) {
// upper layers should handle removed mdirs
LFS_ASSERT(mdir->mid >= 0);
while (true) {
// calculate new mid, be careful to avoid rid overflow
lfsr_bid_t bid = lfsr_mid_bid(lfs, mdir->mid);
lfsr_srid_t rid = lfsr_mid_rid(lfs, mdir->mid) + off;
// lookup mdirs until we find our rid, we need to do this because
// we don't know how many rids are in each mdir until we fetch
while (rid >= (lfsr_srid_t)mdir->rbyd.weight) {
// end of mtree?
if (bid+(1 << lfs->mdir_bits) >= lfsr_mtree_weight(lfs)) {
// if we hit the end of the mtree, park the mdir so all future
// seeks return noent
mdir->mid = bid + (1 << lfs->mdir_bits);
return LFS_ERR_NOENT;
}
bid += (1 << lfs->mdir_bits);
rid -= mdir->rbyd.weight;
int err = lfsr_mtree_lookup(lfs, bid, mdir);
if (err) {
return err;
}
}
mdir->mid = LFSR_MID(lfs, bid, rid);
return 0;
}
}
/// Mdir commit logic ///
@@ -9253,19 +9221,24 @@ static int lfsr_fs_fixorphans(lfs_t *lfs) {
//
// note this never takes longer than lfsr_mount
//
lfsr_mdir_t mdir;
int err = lfsr_mtree_lookup(lfs, 0,
&mdir);
if (err) {
LFS_ASSERT(err != LFS_ERR_NOENT);
return err;
}
lfsr_mdir_t mdir = {.mid=0, .rbyd.weight=0};
while (true) {
// is this mid opened? skip
// next mdir?
if (lfsr_mid_rid(lfs, mdir.mid) >= (lfsr_srid_t)mdir.rbyd.weight) {
int err = lfsr_mtree_lookup(lfs, lfsr_mid_bid(lfs, mdir.mid) + 1,
&mdir);
if (err) {
if (err == LFS_ERR_NOENT) {
break;
}
return err;
}
}
// is this mid open? well we're not an orphan then, skip
if (!lfsr_mid_isopen(lfs, mdir.mid)) {
// are we an orphaned file?
err = lfsr_mdir_lookup(lfs, &mdir, LFSR_TAG_ORPHAN,
// are we an orphan file?
int err = lfsr_mdir_lookup(lfs, &mdir, LFSR_TAG_ORPHAN,
NULL);
if (err && err != LFS_ERR_NOENT) {
return err;
@@ -9279,27 +9252,11 @@ static int lfsr_fs_fixorphans(lfs_t *lfs) {
return err;
}
// seek in case our mdir was dropped
err = lfsr_mtree_seek(lfs, &mdir, 0);
if (err) {
if (err == LFS_ERR_NOENT) {
break;
}
return err;
}
continue;
}
}
// lookup next entry
err = lfsr_mtree_seek(lfs, &mdir, 1);
if (err) {
if (err == LFS_ERR_NOENT) {
break;
}
return err;
}
mdir.mid += 1;
}
lfs->hasorphans = false;
@@ -9776,24 +9733,32 @@ int lfsr_remove(lfs_t *lfs, const char *path) {
lfsr_mid_t bookmark_mid = bookmark_mdir.mid;
// check that the directory is empty
err = lfsr_mtree_seek(lfs, &bookmark_mdir, 1);
if (err && err != LFS_ERR_NOENT) {
bookmark_mdir.mid += 1;
if (lfsr_mid_rid(lfs, bookmark_mdir.mid)
>= (lfsr_srid_t)bookmark_mdir.rbyd.weight) {
err = lfsr_mtree_lookup(lfs,
lfsr_mid_bid(lfs, bookmark_mdir.mid-1) + 1,
&bookmark_mdir);
if (err) {
if (err == LFS_ERR_NOENT) {
goto empty;
}
return err;
}
}
// the next mid should be another bookmark
err = lfsr_mdir_lookup(lfs,
&bookmark_mdir, LFSR_TAG_BOOKMARK,
NULL);
if (err) {
if (err == LFS_ERR_NOENT) {
return LFS_ERR_NOTEMPTY;
}
return err;
}
if (err != LFS_ERR_NOENT) {
lfsr_tag_t bookmark_tag;
err = lfsr_mdir_sublookup(lfs, &bookmark_mdir, LFSR_TAG_NAME,
&bookmark_tag, NULL);
if (err) {
return err;
}
if (bookmark_tag != LFSR_TAG_BOOKMARK) {
return LFS_ERR_NOTEMPTY;
}
}
empty:;
// create a grm to remove the bookmark entry
lfs->grm.mids[0] = bookmark_mid;
}
@@ -9947,24 +9912,32 @@ int lfsr_rename(lfs_t *lfs, const char *old_path, const char *new_path) {
lfsr_mid_t bookmark_mid = bookmark_mdir.mid;
// check that the directory is empty
err = lfsr_mtree_seek(lfs, &bookmark_mdir, 1);
if (err && err != LFS_ERR_NOENT) {
bookmark_mdir.mid += 1;
if (lfsr_mid_rid(lfs, bookmark_mdir.mid)
>= (lfsr_srid_t)bookmark_mdir.rbyd.weight) {
err = lfsr_mtree_lookup(lfs,
lfsr_mid_bid(lfs, bookmark_mdir.mid-1) + 1,
&bookmark_mdir);
if (err) {
if (err == LFS_ERR_NOENT) {
goto empty;
}
return err;
}
}
// the next mid should be another bookmark
err = lfsr_mdir_lookup(lfs,
&bookmark_mdir, LFSR_TAG_BOOKMARK,
NULL);
if (err) {
if (err == LFS_ERR_NOENT) {
return LFS_ERR_NOTEMPTY;
}
return err;
}
if (err != LFS_ERR_NOENT) {
lfsr_tag_t bookmark_tag;
err = lfsr_mdir_sublookup(lfs, &bookmark_mdir, LFSR_TAG_NAME,
&bookmark_tag, NULL);
if (err) {
return err;
}
if (bookmark_tag != LFSR_TAG_BOOKMARK) {
return LFS_ERR_NOTEMPTY;
}
}
empty:;
// mark bookmark entry for removal with a grm
lfs->grm.mids[1] = bookmark_mid;
}
@@ -10208,17 +10181,22 @@ int lfsr_dir_read(lfs_t *lfs, lfsr_dir_t *dir, struct lfs_info *info) {
return 0;
}
// seek in case our mdir was dropped
int err = lfsr_mtree_seek(lfs, &dir->o.mdir, 0);
if (err) {
return err;
}
while (true) {
// next mdir?
if (lfsr_mid_rid(lfs, dir->o.mdir.mid)
>= (lfsr_srid_t)dir->o.mdir.rbyd.weight) {
int err = lfsr_mtree_lookup(lfs,
lfsr_mid_bid(lfs, dir->o.mdir.mid-1) + 1,
&dir->o.mdir);
if (err) {
return err;
}
}
// lookup the next name tag
lfsr_tag_t tag;
lfsr_data_t data;
err = lfsr_mdir_sublookup(lfs, &dir->o.mdir, LFSR_TAG_NAME,
int err = lfsr_mdir_sublookup(lfs, &dir->o.mdir, LFSR_TAG_NAME,
&tag, &data);
if (err) {
return err;
@@ -10237,25 +10215,23 @@ int lfsr_dir_read(lfs_t *lfs, lfsr_dir_t *dir, struct lfs_info *info) {
}
// skip orphans, we pretend these don't exist
if (tag != LFSR_TAG_ORPHAN) {
// fill out our info struct
err = lfsr_stat_(lfs, &dir->o.mdir, tag, data,
info);
if (err) {
return err;
}
if (tag == LFSR_TAG_ORPHAN) {
dir->o.mdir.mid += 1;
dir->pos += 1;
continue;
}
// eagerly look up the next entry
err = lfsr_mtree_seek(lfs, &dir->o.mdir, 1);
if (err && err != LFS_ERR_NOENT) {
// fill out our info struct
err = lfsr_stat_(lfs, &dir->o.mdir, tag, data,
info);
if (err) {
return err;
}
dir->pos += 1;
if (tag != LFSR_TAG_ORPHAN) {
return 0;
}
// eagerly set to next entry
dir->o.mdir.mid += 1;
dir->pos += 1;
return 0;
}
}
@@ -10268,23 +10244,39 @@ int lfsr_dir_seek(lfs_t *lfs, lfsr_dir_t *dir, lfs_soff_t off) {
}
// first rewind
int err = lfsr_dir_rewind(lfs, dir);
int err = lfsr_dir_rewind_(lfs, dir);
if (err) {
return err;
}
// then seek to the requested offset, we leave it up to lfsr_mtree_seek
// to make this efficient
// then seek to the requested offset
//
// note the -2 to adjust for dot entries
if (off > 2) {
err = lfsr_mtree_seek(lfs, &dir->o.mdir, off - 2);
if (err && err != LFS_ERR_NOENT) {
return err;
lfs_off_t off_ = off - 2;
while (off_ > 0) {
// next mdir?
if (lfsr_mid_rid(lfs, dir->o.mdir.mid)
>= (lfsr_srid_t)dir->o.mdir.rbyd.weight) {
int err = lfsr_mtree_lookup(lfs,
lfsr_mid_bid(lfs, dir->o.mdir.mid-1) + 1,
&dir->o.mdir);
if (err) {
if (err == LFS_ERR_NOENT) {
break;
}
return err;
}
}
}
dir->pos = off;
lfs_off_t d = lfs_min(
off_,
dir->o.mdir.rbyd.weight
- lfsr_mid_rid(lfs, dir->o.mdir.mid));
dir->o.mdir.mid += d;
off_ -= d;
}
dir->pos = off;
return 0;
}
@@ -10301,9 +10293,6 @@ static int lfsr_dir_rewind_(lfs_t *lfs, lfsr_dir_t *dir) {
return 0;
}
// reset pos
dir->pos = 0;
// lookup our bookmark in the mtree
int err = lfsr_mtree_namelookup(lfs, dir->did, NULL, 0,
&dir->o.mdir, NULL, NULL);
@@ -10312,12 +10301,10 @@ static int lfsr_dir_rewind_(lfs_t *lfs, lfsr_dir_t *dir) {
return err;
}
// eagerly lookup the next entry
err = lfsr_mtree_seek(lfs, &dir->o.mdir, 1);
if (err && err != LFS_ERR_NOENT) {
return err;
}
// eagerly set to next entry
dir->o.mdir.mid += 1;
// reset pos
dir->pos = 0;
return 0;
}