[Virtio-fs] F_SETLKW not supported

[Vivek Goyal]

On Mon, Jul 20, 2020 at 11:33:32AM +0200, Miklos Szeredi wrote:
> 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?

Hi Miklos,

Disabling it by default till we support blocking version of locks is
probably a good idea. That way it will work out of box without
having to specify no_posix_lock. Anyway, we don't support virtiofs
in shared mode yet. I will send a patch.

Thanks
Vivek