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Added inline_max, to optionally limit the size of inlined files

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Inlined files live in metadata and decrease storage requirements, but
may be limited to improve metadata-related performance. This is
especially important given the current plague of metadata performance.

Though decreasing inline_max may make metadata more dense and increase
block usage, so it's important to benchmark if optimizing for speed.

The underlying limits of inlined files haven't changed:
1. Inlined files need to fit in RAM, so <= cache_size
2. Inlined files need to fit in a single attr, so <= attr_max
3. Inlined files need to fit in 1/8 of a block to avoid metadata
   overflow issues, this is after limiting by metadata_max,
   so <= min(metadata_max, block_size)/8

By default, the largest possible inline_max is used. This preserves
backwards compatibility and is probably a good default for most use
cases.

This does have the awkward effect of requiring inline_max=-1 to
indicate disabled inlined files, but I don't think there's a good
way around this.
This commit is contained in:
Christopher Haster
2023-12-20 22:56:26 -06:00
parent 09972a1710
commit 8b8fd14187
7 changed files with 79 additions and 25 deletions
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lfs.c
+26 -9
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@@ -3524,11 +3524,7 @@ static lfs_ssize_t lfs_file_flushedwrite(lfs_t *lfs, lfs_file_t *file,
lfs_size_t nsize = size;
if ((file->flags & LFS_F_INLINE) &&
lfs_max(file->pos+nsize, file->ctz.size) >
lfs_min(0x3fe, lfs_min(
lfs->cfg->cache_size,
(lfs->cfg->metadata_max ?
lfs->cfg->metadata_max : lfs->cfg->block_size) / 8))) {
lfs_max(file->pos+nsize, file->ctz.size) > lfs->inline_max) {
// inline file doesn't fit anymore
int err = lfs_file_outline(lfs, file);
if (err) {
@@ -3725,10 +3721,7 @@ static int lfs_file_rawtruncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size) {
lfs_off_t oldsize = lfs_file_rawsize(lfs, file);
if (size < oldsize) {
// revert to inline file?
if (size <= lfs_min(0x3fe, lfs_min(
lfs->cfg->cache_size,
(lfs->cfg->metadata_max ?
lfs->cfg->metadata_max : lfs->cfg->block_size) / 8))) {
if (size <= lfs->inline_max) {
// flush+seek to head
lfs_soff_t res = lfs_file_rawseek(lfs, file, 0, LFS_SEEK_SET);
if (res < 0) {
@@ -4259,6 +4252,27 @@ static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
LFS_ASSERT(lfs->cfg->metadata_max <= lfs->cfg->block_size);
LFS_ASSERT(lfs->cfg->inline_max == (lfs_size_t)-1
|| lfs->cfg->inline_max <= lfs->cfg->cache_size);
LFS_ASSERT(lfs->cfg->inline_max == (lfs_size_t)-1
|| lfs->cfg->inline_max <= lfs->attr_max);
LFS_ASSERT(lfs->cfg->inline_max == (lfs_size_t)-1
|| lfs->cfg->inline_max <= ((lfs->cfg->metadata_max)
? lfs->cfg->metadata_max
: lfs->cfg->block_size)/8);
lfs->inline_max = lfs->cfg->inline_max;
if (lfs->inline_max == (lfs_size_t)-1) {
lfs->inline_max = 0;
} else if (lfs->inline_max == 0) {
lfs->inline_max = lfs_min(
lfs->cfg->cache_size,
lfs_min(
lfs->attr_max,
((lfs->cfg->metadata_max)
? lfs->cfg->metadata_max
: lfs->cfg->block_size)/8));
}
// setup default state
lfs->root[0] = LFS_BLOCK_NULL;
lfs->root[1] = LFS_BLOCK_NULL;
@@ -4482,6 +4496,9 @@ static int lfs_rawmount(lfs_t *lfs, const struct lfs_config *cfg) {
}
lfs->attr_max = superblock.attr_max;
// we also need to update inline_max in case attr_max changed
lfs->inline_max = lfs_min(lfs->inline_max, lfs->attr_max);
}
// this is where we get the block_count from disk if block_count=0