Minor release: v2.9

[geky]

This release brings in some heavily requested minor features. Thanks to everyone who has contributed/provided feedback!

Bringing in:

• 886

• 909

• 912

• 913

• 914

• 915

• 916

• 917

Draft of release notes follows:

---

Itsy-bitsy teeny-tiny breaking changes:

• lfs_rename now returns LFS_ERR_NOTDIR if the source is a regular file and the destination is a directory. This better aligns with POSIX.

• Defining LFS_FILE_MAX > 2147483647 is no longer supported. It's unclear if this ever worked, and at least half the file API was unusable in this state.

What's new?

• lfs_fs_gc can now compact metadata (#913)

  This is controlled by the new optional compact_thresh configuration option. mdirs above compact_thresh will be eagerly compacted during lfs_fs_gc, making it less likely (but still possible) for compactions to occur during file writes.

  By default, compact_thresh=0, littlefs will compact mdirs > ~88% block_size. This value may change in the future.

  compact_thresh=-1 disables mdir compaction during lfs_fs_gc.

  Note that compact_thresh has no effect on mdir compaction outside of lfs_fs_gc. mdirs must compact when full.

• Added inline_max, which allows explicit user control over the size of inlined files (#914)

  Decreasing inline_max may improve some metadata-related performance around mdir traversal. But decreasing inline_max may also hurt metadata-related performance around mdir compaction and increase storage consumption. It is up to users to determine the best value per-application.

  By default, inline_max=0, uses the largest possible inline_max. This matches the previous behavior and is probably a good default for most use cases.

  inline_max=-1 disables inlined files.

• Added easier util overrides for common system functions: LFS_MALLOC, LFS_FREE, LFS_CRC (#909)

  These can now be overridden with simple defines:

  -DLFS_MALLOC=my_malloc
  -DLFS_FREE=my_free
  -DLFS_CRC=my_crc

  Note: Overriding LFS_CRC with a non-CRC32 checksum is discouraged. This is only intended for hardware acceleration, etc.

• Thanks to @tomscii, lfs_rename now returns LFS_ERR_NOTDIR if the source is a regular file and the destination is a directory, which better matches POSIX (#917)

• Thanks to @BrianPugh, defining overridable limits (LFS_FILE_MAX, LFS_NAME_MAX, LFS_ATTR_MAX) to incompatible values will now result in a compile error (#886)

• Relaxed lookahead buffer alignment to only be byte-aligned (#912)

• Relaxed lfs_malloc alignment requirements to only be byte-aligned (#912)

[geky-bot]

Tests passed ✓, Code: 16972 B (+0.9%), Stack: 1432 B (-1.1%), Structs: 812 B (+1.5%)

| | Code | Stack | Structs | | Coverage | |:--|-----:|------:|--------:|:--|---------:| | Default | 16972 B (+0.9%) | 1432 B (-1.1%) | 812 B (+1.5%) | Lines | 2387/2566 lines (-0.1%) | | Readonly | 6186 B (+0.9%) | 448 B (+0.0%) | 812 B (+1.5%) | Branches | 1239/1576 branches (-0.1%) | | Threadsafe | 17836 B (+0.8%) | 1432 B (-1.1%) | 820 B (+1.5%) | | **Benchmarks** | | Multiversion | 17036 B (+0.9%) | 1432 B (-1.1%) | 816 B (+1.5%) | Readed | 29369693876 B (+0.0%) | | Migrate | 18664 B (+0.8%) | 1736 B (-0.9%) | 816 B (+1.5%) | Proged | 1482874766 B (+0.0%) | | Error-asserts | 17660 B (+1.0%) | 1424 B (-1.1%) | 812 B (+1.5%) | Erased | 1568888832 B (+0.0%) |