[Virtio-fs] F_SETLKW not supported

[Miklos Szeredi]

On Mon, Jul 20, 2020 at 10:01 AM Aa Aa <jimbothom at yandex.com> wrote:
>
> Hi
>
> I am trying to run some java apps via virtfs and some of the file locking (java) doesn't work. Here an exception (java) is thrown something about file locking:
>
> Here is the strace output:
>
>  3541 [pid 12461] openat(AT_FDCWD, "/mnt/<redacted> O_WRONLY|O_CREAT|O_APPEND, 0666 <unfinished ...>
>  3542 [pid 12461] <... openat resumed>)       = 180
>  3543 [pid 12461] fstat(180, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
>  3544 [pid 12461] fcntl(180, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=0} <unfinished ...>
>  3545 [pid 12461] <... fcntl resumed>)        = -1 EOPNOTSUPP (Operation not supported)

I think that's due to an incomplete implementation of POSIX locks in virtiofsd.

Try "no_posix_lock" option: that should make locks work, but only
locally (i.e. inside the guest).

Vivek, do we maybe want to turn off remote posix locks by default
until the implementation is complete?

Thanks,
Miklos