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bmap: Taught littlefs how to traverse the gbmap

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Fortunately the btree traversal logic is pretty reusable, so this just
required an additional tstate (LFS3_TSTATE_BMAP).

This raises an interesting question: _when_ do we traverse the bmap? We
need to wait until at least mtree traversal completes for gstate to be
reconstructed during lfs3_mount, but I think traversing before file
btrees makes sense.
This commit is contained in:
Christopher Haster
2025-07-24 00:16:14 -05:00
parent 1537f6a430
commit 59a4ae6f61
2 changed files with 37 additions and 15 deletions
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lfs3.c
+30 -9
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@@ -9955,13 +9955,14 @@ enum lfs3_tstate {
#ifndef LFS3_2BONLY
LFS3_TSTATE_MROOTCHAIN = 1,
LFS3_TSTATE_MTREE = 2,
LFS3_TSTATE_MDIRS = 3,
LFS3_TSTATE_MDIR = 4,
LFS3_TSTATE_BTREE = 5,
LFS3_TSTATE_HANDLES = 6,
LFS3_TSTATE_HBTREE = 7,
LFS3_TSTATE_BMAP = 3,
LFS3_TSTATE_MDIRS = 4,
LFS3_TSTATE_MDIR = 5,
LFS3_TSTATE_BTREE = 6,
LFS3_TSTATE_HANDLES = 7,
LFS3_TSTATE_HBTREE = 8,
#endif
LFS3_TSTATE_DONE = 8,
LFS3_TSTATE_DONE = 9,
};
static void lfs3_trv_init(lfs3_trv_t *trv, uint32_t flags) {
@@ -10193,6 +10194,7 @@ static lfs3_stag_t lfs3_mtree_traverse_(lfs3_t *lfs3, lfs3_trv_t *trv,
// and any file btrees/bshrubs
#ifndef LFS3_2BONLY
case LFS3_TSTATE_MTREE:;
case LFS3_TSTATE_BMAP:;
case LFS3_TSTATE_BTREE:;
case LFS3_TSTATE_HBTREE:;
// traverse through our bshrub/btree
@@ -10202,9 +10204,26 @@ static lfs3_stag_t lfs3_mtree_traverse_(lfs3_t *lfs3, lfs3_trv_t *trv,
if (tag == LFS3_ERR_NOENT) {
// clear the bshrub state
lfs3_bshrub_init(&trv->b);
// end of mtree? start iterating over mdirs
if (lfs3_t_tstate(trv->b.h.flags)
== LFS3_TSTATE_MTREE) {
// end of mtree? have a bmap? not mtreeonly? start
// iterating over bmap
if (LFS3_IFDEF_BMAP(
lfs3_t_tstate(trv->b.h.flags)
== LFS3_TSTATE_MTREE
&& !lfs3_t_ismtreeonly(trv->b.h.flags),
false)) {
#ifdef LFS3_BMAP
trv->b.shrub = lfs3->gbmap.b;
trv->bid = -2;
lfs3_t_settstate(&trv->b.h.flags, LFS3_TSTATE_BMAP);
continue;
#endif
// end of mtree and bmap? start iterating over mdirs
} else if (lfs3_t_tstate(trv->b.h.flags)
== LFS3_TSTATE_MTREE
|| LFS3_IFDEF_BMAP(
lfs3_t_tstate(trv->b.h.flags)
== LFS3_TSTATE_BMAP,
false)) {
trv->b.h.mdir.mid = 0;
lfs3_t_settstate(&trv->b.h.flags, LFS3_TSTATE_MDIRS);
continue;
@@ -15430,12 +15449,14 @@ static int lfs3_mountinited(lfs3_t *lfs3) {
// decode the global block-map
//
// this one is a bit less exciting
#ifdef LFS3_BMAP
err = lfs3_data_readgbmap(lfs3,
&LFS3_DATA_BUF(lfs3->gbmap_d, LFS3_GBMAP_DSIZE));
if (err) {
// TODO switch to read-only?
return err;
}
#endif
return 0;
}