qemu linux-user doesn't support OFD fcntl locks

"Open file description locks (non-POSIX)", as they are described in fcntl(2) man page, aren't supported by qemu-user  and attempting to use those results in EINVAL. I'm on Gentoo with latest QEMU version currently available (5.0.0-r2), and trying to emulate ppc64 and s390x on x86_64.

Looking at linux-user/syscall.c, I'm guessing the issue is in (at least) `target_to_host_fcntl_cmd` where switch reaches the default clause as there're no cases for F_OFD_SETLK / F_OFD_SETLKW / F_OFD_GETLK.

The attached patch fixes the issue for me.

New patch version: fix target_to_host_fcntl_cmd mapping, avoid do_fcntl code duplication.

Please check qemu-5.1.0.

This has been fixed by:

  2d92c6827ca0 ("linux-user: implement OFD locks")
  https://git.qemu.org/?p=qemu.git;a=commitdiff;h=2d92c6827ca0

perhaps you can send a patch to the qemu-devel ML to add the strace part.

Thanks, the changes in 5.1.0 seem to work indeed.

> perhaps you can send a patch to the qemu-devel ML to add the strace part

Done.