[Feature] Production-Readiness Stabilization of Mnemofs

[Sumit6307]

Is your feature request related to a problem? Please describe.

Yes. The newer flash file system in NuttX, mnemofs, is a great architectural addition but is currently marked as experimental and contains several structural inefficiencies and incomplete POSIX compliance features. As noted in multiple TODO and FUTURE TODO comments across fs/mnemofs/, the current implementation suffers from:

1. Inefficient Directory Traversal: mnemofs_fsobj.c currently performs double traversals for path resolution, creating overhead.
2. Missing Timestamps: POSIX mtime, atime, and ctime are not fully implemented/updated during journal atomic commits (noted in mnemofs.c and mnemofs_journal.c).
3. Memory Leaks during Block Flush: The flush operation has known issues ("does not work properly, and causes memory [leaks]"), which is critical for flash wear-leveling and system stability in long-running embedded IoT applications.

Describe the solution you'd like

I propose a comprehensive stabilization pass over mnemofs focusing on robustness, POSIX standard compliance, and maintaining strict self-compatibility. The planned solution includes:

• Single Traversal Refactoring: Rewriting the directory lookup mechanisms to utilize a single-pass traversal, decoupling the LRU cache dependencies from Journal atomic commits to increase lookup throughput without increasing RAM footprint.
• Timestamping Integration: Properly passing POSIX time references down through the VFS inode layer into the mnemofs master nodes, updating timestamps gracefully without causing massive flash rewrite amplification.
• Flush Mechanism Overhaul: Investigating and rewriting the block flush mechanism to permanently resolve memory leaks, verifying stability under heavy multi-threaded write loads over long periods.
• Hardware Validation: Adding extensive runtime test coverage using apps/ostest and apps/fs/fstests verified on real hardware, generating complete build and runtime logs to prove zero regressions.

This work will be done iteratively through small, highly-focused, non-breaking Pull Requests to allow manageable reviews by the maintainers.

Describe alternatives you've considered

I propose a comprehensive stabilization pass over mnemofs focusing on robustness, POSIX standard compliance, and maintaining strict self-compatibility. The planned solution includes:

• Single Traversal Refactoring: Rewriting the directory lookup mechanisms to utilize a single-pass traversal, decoupling the LRU cache dependencies from Journal atomic commits to increase lookup throughput without increasing RAM footprint.
• Timestamping Integration: Properly passing POSIX time references down through the VFS inode layer into the mnemofs master nodes, updating timestamps gracefully without causing massive flash rewrite amplification.
• Flush Mechanism Overhaul: Investigating and rewriting the block flush mechanism to permanently resolve memory leaks, verifying stability under heavy multi-threaded write loads over long periods.
• Hardware Validation: Adding extensive runtime test coverage using apps/ostest and apps/fs/fstests verified on real hardware, generating complete build and runtime logs to prove zero regressions.

This work will be done iteratively through small, highly-focused, non-breaking Pull Requests to allow manageable reviews by the maintainers.

Verification

• I have verified before submitting the report.

[Sumit6307]

@acassis Please Check this Issue

[Sumit6307]

@jingfei195887 Sir, Please check this Issue