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gbmap: Added support for gbmap in lfs3_fs_grow

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In lfs3_fs_grow, we need to update any gbmaps to match the new disk
size. The actual patch to the gbmap is easy, but it does get a bit
delicate since we need to feed the gbmap with an allocator in the new
disk size.

Fortunately, the opportunistism of the gbmap allocator avoids any
catch-22 issues, as long as we make sure to not trigger any gbmap
rebuilds.

Adds a bit of code, but not much:

                 code          stack          ctx
  before:       37168           2352          684
  after:        37168 (+0.0%)   2352 (+0.0%)  684 (+0.0%)

                 code          stack          ctx
  gbmap before: 39000           2456          800
  gbmap after:  39116 (+0.3%)   2456 (+0.0%)  800 (+0.0%)
This commit is contained in:
Christopher Haster
2025-10-10 13:44:40 -05:00
parent 24d75a24c5
commit 9e45249b29
7 changed files with 196 additions and 112 deletions
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lfs3.c
+64 -15
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@@ -7875,7 +7875,7 @@ static int lfs3_rbyd_appendgdelta(lfs3_t *lfs3, lfs3_rbyd_t *rbyd) {
// TODO is this the right place?
// try to update to most recent lookahead window
lfs3->gbmap.window = (lfs3->lookahead.window + lfs3->lookahead.off)
% lfs3->cfg->block_count;
% lfs3->block_count;
lfs3->gbmap.known = lfs3->lookahead.gbmapped;
uint8_t gbmapdelta_[LFS3_GBMAP_DSIZE];
@@ -10981,6 +10981,13 @@ static int lfs3_gbmap_setbptr(lfs3_t *lfs3, lfs3_btree_t *gbmap,
/// Block allocator ///
// checkpoint only the lookahead buffer
#ifndef LFS3_RDONLY
static inline void lfs3_alloc_ckpoint_(lfs3_t *lfs3) {
lfs3->lookahead.ckpoint = lfs3->block_count;
}
#endif
// needed in lfs3_alloc_ckpoint
static int lfs3_alloc_rebuildgbmap(lfs3_t *lfs3);
@@ -10995,7 +11002,7 @@ static int lfs3_alloc_rebuildgbmap(lfs3_t *lfs3);
static inline int lfs3_alloc_ckpoint(lfs3_t *lfs3) {
#ifndef LFS3_2BONLY
// checkpoint the allocator
lfs3->lookahead.ckpoint = lfs3->block_count;
lfs3_alloc_ckpoint_(lfs3);
#ifdef LFS3_GBMAP
// do we need to rebuild the gbmap?
@@ -11009,7 +11016,7 @@ static inline int lfs3_alloc_ckpoint(lfs3_t *lfs3) {
}
// checkpoint the allocator again
lfs3->lookahead.ckpoint = lfs3->block_count;
lfs3_alloc_ckpoint_(lfs3);
}
#endif
@@ -11021,11 +11028,17 @@ static inline int lfs3_alloc_ckpoint(lfs3_t *lfs3) {
}
#endif
// discard any lookahead state, this is necessary if block_count changes
// discard any lookahead/gbmap windows, this is necessary if block_count
// changes
#if !defined(LFS3_RDONLY) && !defined(LFS3_2BONLY)
static inline void lfs3_alloc_discard(lfs3_t *lfs3) {
// discard lookahead state
lfs3->lookahead.known = 0;
lfs3_memset(lfs3->lookahead.buffer, 0, lfs3->cfg->lookahead_size);
// discard gbmap window
#ifdef LFS3_GBMAP
lfs3->lookahead.gbmapped = 0;
#endif
}
#endif
@@ -11218,7 +11231,7 @@ static lfs3_sblock_t lfs3_alloc(lfs3_t *lfs3, uint32_t flags) {
"lookahead %"PRId32"/%"PRId32,
block,
lfs3->lookahead.known,
lfs3->cfg->block_count);
lfs3->block_count);
#endif
return block;
}
@@ -11234,7 +11247,7 @@ static lfs3_sblock_t lfs3_alloc(lfs3_t *lfs3, uint32_t flags) {
LFS3_ERROR("No more free space "
"(lookahead %"PRId32"/%"PRId32")",
lfs3->lookahead.known,
lfs3->cfg->block_count);
lfs3->block_count);
return LFS3_ERR_NOSPC;
}
@@ -11298,11 +11311,11 @@ static lfs3_sblock_t lfs3_alloc(lfs3_t *lfs3, uint32_t flags) {
#if !defined(LFS3_RDONLY) && defined(LFS3_GBMAP)
static int lfs3_alloc_rebuildgbmap(lfs3_t *lfs3) {
// we should ckpoint before calling this
LFS3_ASSERT(lfs3->lookahead.ckpoint == lfs3->cfg->block_count);
LFS3_ASSERT(lfs3->lookahead.ckpoint == lfs3->block_count);
LFS3_INFO("Rebuilding gbmap "
"(gbmap %"PRId32"/%"PRId32")",
lfs3->lookahead.gbmapped,
lfs3->cfg->block_count);
lfs3->block_count);
// create a copy of the gbmap
lfs3_btree_t gbmap_ = lfs3->gbmap.b;
@@ -11378,7 +11391,7 @@ failed:;
LFS3_INFO("Not enough space for gbmap "
"(lookahead %"PRId32"/%"PRId32")",
lfs3->lookahead.known,
lfs3->cfg->block_count);
lfs3->block_count);
return 0;
}
return err;
@@ -15391,9 +15404,6 @@ static int lfs3_init(lfs3_t *lfs3, uint32_t flags,
lfs3->lookahead.off = 0;
lfs3->lookahead.known = 0;
lfs3->lookahead.ckpoint = 0;
#ifdef LFS3_GBMAP
lfs3->lookahead.gbmapped = 0;
#endif
lfs3_alloc_discard(lfs3);
#endif
@@ -16322,7 +16332,7 @@ static int lfs3_formatgbmap(lfs3_t *lfs3) {
//
// assume we can write gbmap to block 2
lfs3->gbmap.window = 3;
lfs3->gbmap.known = lfs3->cfg->block_count;
lfs3->gbmap.known = lfs3->block_count;
lfs3->gbmap.b.r.blocks[0] = 2;
lfs3->gbmap.b.r.trunk = 0;
lfs3->gbmap.b.r.weight = 0;
@@ -16346,7 +16356,9 @@ static int lfs3_formatgbmap(lfs3_t *lfs3) {
// blocks 0..3 - in-use
LFS3_RATTR(LFS3_TAG_BMINUSE, +3),
// blocks 3..block_count - free
LFS3_RATTR(LFS3_TAG_BMFREE, +(lfs3->cfg->block_count - 3))));
(lfs3->block_count > 3)
? LFS3_RATTR(LFS3_TAG_BMFREE, +(lfs3->block_count - 3))
: LFS3_RATTR_NOOP()));
if (err) {
goto failed;
}
@@ -17039,9 +17051,46 @@ int lfs3_fs_grow(lfs3_t *lfs3, lfs3_size_t block_count_) {
lfs3->block_count = block_count_;
// discard stale lookahead buffer
lfs3_alloc_discard(lfs3);
int err;
// grow the gbmap if we have one
//
// note this won't actually be committed to disk until mdir commit
#ifdef LFS3_GBMAP
if (lfs3_f_isgbmap(lfs3->flags)) {
// if the last range is free, we can extend it, otherwise we
// need a new range
lfs3_stag_t tag = lfs3_gbmap_lookupnext(lfs3, &lfs3->gbmap.b,
block_count-1,
NULL, NULL);
if (tag < 0) {
LFS3_ASSERT(tag != LFS3_ERR_NOENT);
err = tag;
goto failed;
}
// checkpoint the lookahead buffer, but _not_ the gbmap, we
// cann't rebuild the gbmap until we've resized it
lfs3_alloc_ckpoint_(lfs3);
// we don't need a copy because this is atomic, and mdir commit
// reverts to the on-disk state if it fails
err = lfs3_gbmap_commit(lfs3, &lfs3->gbmap.b,
(tag == LFS3_TAG_BMFREE) ? block_count-1 : block_count,
LFS3_RATTRS(
LFS3_RATTR(
(tag == LFS3_TAG_BMFREE)
? LFS3_TAG_GROW
: LFS3_TAG_BMFREE,
+(block_count_ - block_count))));
if (err) {
goto failed;
}
}
#endif
// update our on-disk config
int err = lfs3_mdir_commit(lfs3, &lfs3->mroot, LFS3_RATTRS(
err = lfs3_mdir_commit(lfs3, &lfs3->mroot, LFS3_RATTRS(
LFS3_RATTR_GEOMETRY(
LFS3_TAG_GEOMETRY, 0,
(&(lfs3_geometry_t){