fs: add generic helper for filling statx attribute flags

The immutable and append-only properties on an inode are published on
the inode's i_flags and enforced by the VFS.

Create a helper to fill the corresponding STATX_ATTR_ flags in the kstat
structure from the inode's i_flags.

Only orange was converted to use this helper.
Other filesystems could use it in the future.

Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

include/linux/stat.h

@@ -34,6 +34,10 @@ struct kstat {
 	 STATX_ATTR_ENCRYPTED |				\
 	 STATX_ATTR_VERITY				\
 	 )/* Attrs corresponding to FS_*_FL flags */
+#define KSTAT_ATTR_VFS_FLAGS				\
+	(STATX_ATTR_IMMUTABLE |				\
+	 STATX_ATTR_APPEND				\
+	 ) /* Attrs corresponding to S_* flags that are enforced by the VFS */
 	u64		ino;
 	dev_t		dev;
 	dev_t		rdev;