[dfs] feat: Mark dirty on unmap for shared mapping
This patch optimizes the pcache varea management by refining the
conditions under which pages are marked dirty, specifically targeting
the unmap operations in the dfs_pcache component. These changes were
necessary to enhance the efficiency of page cache management.
Changes:
- Adjusted include statements in `dfs_pcache.c` for better organization.
- Modified `dfs_aspace_unmap` function:
- Added a check to ensure `varea` is not privately locked before marking a page as dirty.
- Updated `dfs_aspace_page_unmap` function:
- Added a similar check for `varea` lock status before marking a page as dirty.
Signed-off-by: Shell <smokewood@qq.com>