On Mon, 18 Jul 2022 at 12:56, Christian Kohlschütter <christian@xxxxxxxxxxxxxxxx> wrote: > However, users of fuse that have no business with overlayfs suddenly see their ioctl return ENOTTY instead of ENOSYS. And returning ENOTTY is the correct behavior. See this comment in <asm-generic/errrno.h>: /* * This error code is special: arch syscall entry code will return * -ENOSYS if users try to call a syscall that doesn't exist. To keep * failures of syscalls that really do exist distinguishable from * failures due to attempts to use a nonexistent syscall, syscall * implementations should refrain from returning -ENOSYS. */ #define ENOSYS 38 /* Invalid system call number */ Thanks, Miklos
