ntfs: persist immutable in the $LINUXFLAGS EA

Add a fileattr setter for immutable and store its state in bit 0 of a
little-endian u32 in the private $LINUXFLAGS EA. Reuse the standard NTFS
EA attributes and restore the flag when loading an inode, so eviction
and unmount do not discard the setting.

Use $LINUXFLAGS to avoid the WSL-owned $LX namespace.

Preserve unknown bits and delete the entry only when the entire value is
zero. Reject malformed values with EUCLEAN. Reject direct xattr writes
and removal to avoid bypassing fileattr permissions or stale cached
state. Update the cached flags only after the EA update succeeds.

Reject clearing immutable on system metadata files and files protected
by sys_immutable, following inode-load policy. Do not persist a bit
derived solely from this policy. Preserve append state without allowing
it to be changed at this stage. Compression, encryption and mount-wide
case folding remain read-only. Document the format and its Linux-only
enforcement.

Signed-off-by: Baolin Liu <liubaolin@kylinos.cn>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

0 files changed, 0 insertions, 0 deletions