[dfs][posix] Extend Smart POSIX filesystem and syscall compatibility

[BernardXiong]

为什么提交这份PR (why to submit this PR)

RT-Smart user-space applications require more complete POSIX filesystem, procfs, locking, and syscall behavior. DFS v2 still lacks several interfaces and compatibility details required by Linux-compatible user-space components.

This PR extends Smart POSIX compatibility and updates the QEMU Smart BSP configurations used to build and validate it.

你的解决方案是什么 (what is your solution)

• Add POSIX advisory record locking and fchmod() support to DFS v2, including lock cleanup on descriptor close and replacement.
• Preserve tmpfs mode and link-count metadata, validate path component lengths, and cover the behavior with tmpfs tests.
• Provide live Linux-compatible procfs data for CPU, load, memory, mounts, system statistics, uptime, and process status files.
• Track epoll waiters per queue and fix LWP POSIX syscall user-buffer handling on error paths.
• Expose libc and musl libc as user-selectable options, limit musl libc to Smart configurations, enable the required Smart POSIX DFS configuration, and correct the VirtIO/lwIP Kconfig dependency.

The branch is based on the current upstream master and excludes the AF_UNIX implementation already merged by upstream.

请提供验证的bsp和config (provide the config and bsp)

• BSP: bsp/qemu-virt64-aarch64, bsp/qemu-virt64-riscv
• .config: RT_USING_SMART, RT_USING_LIBC, RT_USING_MUSLLIBC, RT_USING_DFS_V2, RT_USING_DFS_PROCFS, RT_USING_DFS_TMPFS, RT_USING_POSIX_EPOLL, RT_USING_SAL, SAL_USING_POSIX
• action: Local scons --pyconfig-silent passed for qemu-vexpress-a9, qemu-virt64-aarch64, and qemu-virt64-riscv; full compilation passed with arm-none-eabi, aarch64-linux-musleabi, and riscv64-linux-musleabi toolchains. The updated pkgs_test run is 32547494830 and passed.

当前拉取/合并请求的状态 Intent for your PR

必须选择一项 Choose one (Mandatory):

• 本拉取/合并请求是一个草稿版本 This PR is for a code-review and is intended to get feedback
• 本拉取/合并请求是一个成熟版本 This PR is mature, and ready to be integrated into the repo

代码质量 Code Quality：

我在这个拉取/合并请求中已经考虑了 As part of this pull request, I've considered the following:

• 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
• 代码风格正确，包括缩进空格，命名及其他风格 Style guide is adhered to, including spacing, naming and other styles
• 没有垃圾代码，代码尽量精简，不包含#if 0代码，不包含已经被注释了的代码 All redundant code is removed and cleaned up
• 所有变更均有原因及合理的，并且不会影响到其他软件组件代码或BSP All modifications are justified and not affect other components or BSP
• 对难懂代码均提供对应的注释 I've commented appropriately where code is tricky
• 代码是高质量的 Code in this PR is of high quality
• 已经使用clang-format 源码格式化工具确保格式符合RT-Thread代码规范 This PR has been formatted with clang-format and complies with RT-Thread code specification
• 如果是新增bsp, 已经添加ci检查到.github/ALL_BSP_COMPILE.json 详细请参考链接BSP自查

[github-actions]

👋 感谢您对 RT-Thread 的贡献！Thank you for your contribution to RT-Thread!

为确保代码符合 RT-Thread 的编码规范，请在你的仓库中执行以下步骤运行代码格式化工作流（如果格式化CI运行失败）。
To ensure your code complies with RT-Thread's coding style, please run the code formatting workflow by following the steps below (If the formatting of CI fails to run).

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🛠 操作步骤 | Steps

1. 前往 Actions 页面 | Go to the Actions page
   点击进入工作流 → | Click to open workflow →

2. 点击 Run workflow | Click Run workflow

• Use workflow from 保持默认分支（通常为 master）
  Keep the default branch (usually master) in Use workflow from
• 在 branch 输入框填写 PR 分支 feature/smart-posix-dfs-pr
  Enter PR branch feature/smart-posix-dfs-pr in the branch field
• 设置需排除的文件/目录（目录请以"/"结尾）
  Set files/directories to exclude (directories should end with "/")

3. 等待工作流完成 | Wait for the workflow to complete
   格式化后的代码将作为独立提交推送至你的分支。
   The formatting changes will be pushed to your branch as a separate commit.

完成后，提交将自动更新至 feature/smart-posix-dfs-pr 分支，关联的 Pull Request 也会同步更新。
Once completed, commits will be pushed to the feature/smart-posix-dfs-pr branch automatically, and the related Pull Request will be updated.

如有问题欢迎联系我们，再次感谢您的贡献！💐
If you have any questions, feel free to reach out. Thanks again for your contribution!

[github-actions]

MemBrowse Memory Report

k230

• SRAM: .eh_frame +1,016 B, .text +4,112 B (+0.5%, 1,128,131 B / 268,300,288 B, total: 0% used)

qemu-virt64-aarch64

• Code: .eh_frame +704 B, .text +6,144 B (+0.6%, 1,077,060 B)
  No memory changes detected for:
• at32f415-start
• esp32-c3
• gd32105r-start
• hc32f334
• hpmicro-hpm5301evklite
• infineon-psoc6
• loongson-ls1cdev
• nordic-nrf51822
• nuvoton-m487
• nxp-lpc1114
• raspberry-pico-rp2040
• renesas-ra2l1
• simulator
• stm32f407-rt-spark
• stm32l475-atk-pandora-llvm
• wch-ch32v208w-r0
• x86
• xuantie-e901plus

[github-actions]

📌 Code Review Assignment

🏷️ Tag: components

Reviewers: @Maihuanyi

Changed Files (Click to expand)

• components/dfs/dfs_v2/filesystems/procfs/proc_cpuinfo.c
• components/dfs/dfs_v2/filesystems/procfs/proc_loadavg.c
• components/dfs/dfs_v2/filesystems/procfs/proc_meminfo.c
• components/dfs/dfs_v2/filesystems/procfs/proc_mounts.c
• components/dfs/dfs_v2/filesystems/procfs/proc_pid.c
• components/dfs/dfs_v2/filesystems/procfs/proc_stat.c
• components/dfs/dfs_v2/filesystems/procfs/proc_uptime.c
• components/dfs/dfs_v2/filesystems/tmpfs/dfs_tmpfs.c
• components/dfs/dfs_v2/filesystems/tmpfs/dfs_tmpfs.h
• components/dfs/dfs_v2/filesystems/tmpfs/utest/tmpfs.c
• components/dfs/dfs_v2/include/dfs_file.h
• components/dfs/dfs_v2/src/dfs.c
• components/dfs/dfs_v2/src/dfs_file.c
• components/dfs/dfs_v2/src/dfs_posix.c
• components/dfs/dfs_v2/src/dfs_record_lock.c
• components/dfs/dfs_v2/src/dfs_vnode.c
• components/drivers/virtio/Kconfig
• components/libc/Kconfig
• components/libc/compilers/musl/SConscript
• components/libc/posix/io/epoll/epoll.c
• components/lwp/lwp_pid.c
• components/lwp/lwp_syscall.c

🏷️ Tag: components_libc

Reviewers: @GorrayLi @mysterywolf

Changed Files (Click to expand)

• components/libc/Kconfig
• components/libc/compilers/musl/SConscript
• components/libc/posix/io/epoll/epoll.c

🏷️ Tag: components_lwp

Reviewers: @xu18838022837

Changed Files (Click to expand)

• components/lwp/lwp_pid.c
• components/lwp/lwp_syscall.c

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📊 Current Review Status (Last Updated: 2026-08-22 15:51 CST)

• ⌛ @GorrayLi Pending Review
• ⌛ @Maihuanyi Pending Review
• ⌛ @mysterywolf Pending Review
• ⌛ @xu18838022837 Pending Review

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📝 Review Instructions

1. 维护者可以通过单击此处来刷新审查状态: 🔄 刷新状态
   Maintainers can refresh the review status by clicking here: 🔄 Refresh Status

2. 确认审核通过后评论 LGTM/lgtm
   Comment LGTM/lgtm after confirming approval

3. PR合并前需至少一位维护者确认
   PR must be confirmed by at least one maintainer before merging

ℹ️ 刷新CI状态操作需要具备仓库写入权限。
ℹ️ Refresh CI status operation requires repository Write permission.