This patch introduces a remount feature for the DFS, allowing for the
modification of mount parameters without unmounting the filesystem,
the remount functionality helps modify certain mount flags (like `MS_RDONLY`) without
requiring an unmount, providing more control over mounted filesystems in the system.
The updates is essential for user space init proc to cleanup the runtime
resource, ensuring clean handling of cached data and enhancing system
robustness during power down processing.
Changes:
- Defined new constants for remount flags in `dfs_fs.h`.
- Added the `dfs_remount()` function in `dfs_fs.c` to handle remount operations.
- Introduced a check for unsupported flags and handle error conditions such as invalid paths
or non-directory targets.
- Updated the `dfs_mnt` structure in `dfs_mnt.h` to include a read-only flag (`MNT_RDONLY`).
- The `dfs_remount()` function allows changing the read-only status of a mounted filesystem.
- Added `MNT_LAZY_UMNT` and `MNT_RDONLY` flags to `dfs_mnt` structure.
- Introduced `dfs_mnt_setflags` function for dynamic flag management.
- Updated `dfs_remount` to utilize `dfs_mnt_setflags` for flag setting.
- Enhanced unmount operations with `dfs_mnt_umount_iter` and lazy unmounting.
- Added `dfs_pcache_clean` to handle cache cleanup for read-only mounts.
- Improved error reporting in `dfs_umount` for better user feedback.
- Refactored `sys_mount` to streamline parameter handling and support remounts.
- Introduced `_cp_from_usr_string` helper for user-space string operations.
- Updated internal APIs to ensure consistency in reference count management.
Signed-off-by: Shell <smokewood@qq.com>
The patch introduces support for system reboot functionality and process teardown,
allowing for a clean shutdown and unmounting of the root filesystem. This is
necessary for ensuring a proper system shutdown process, especially when dealing
with resource cleanup and ensuring that all processes have exited before system
shutdown.
Changes:
- Added `lwp_teardown()` function to handle process cleanup and system teardown.
- Introduced `lwp_pid_wait_for_empty()` to wait for process ID table emptiness
before proceeding with shutdown.
- Updated `dfs_mnt_unref()` to trigger callbacks when unmounting a filesystem.
- Added new reboot types (`RB_AUTOBOOT`, `RB_POWER_OFF`) and implemented their
corresponding actions, including cleanup of processes and unmounting root
filesystem.
- Extended `sys_reboot()` to handle reboot and power off types with appropriate
callbacks for process and filesystem teardown.
- Introduced callback mechanism for root filesystem unmount notifications.
Signed-off-by: Shell <smokewood@qq.com>
In manual, the prototype of lseek is
`off_t lseek(int fd, off_t offset, int whence);`
where the return type is `off_t` but not ssize_t.
Signed-off-by: Shell <smokewood@qq.com>
