[Virtio-fs] [PATCH] fuse: make written data persistent after writing

[Liu Bo]

On Tue, Mar 10, 2020 at 08:08:49PM +0100, Miklos Szeredi wrote:
> On Tue, Mar 10, 2020 at 7:46 PM Liu Bo <bo.liu at linux.alibaba.com> wrote:
> >
> > On Tue, Mar 10, 2020 at 11:14:17AM +0100, Miklos Szeredi wrote:
> > > On Tue, Mar 3, 2020 at 10:15 PM Liu Bo <bo.liu at linux.alibaba.com> wrote:
> > > >
> > > > If this is a DSYNC write, make sure we push it to stable storage now
> > > > that we've written data.
> > >
> > > If this is direct I/O then why do we need an fysnc() call?
> > >
> > > The only thing needed should be correct setting O_DSYNC in the flags
> > > field of the WRITE request, and it appears to me that that is already
> > > being done.
> >
> > Given direct IO itself doesn't guarantee FUA or FLUSH, I think we
> > still need such a fsync() call to make sure a FUA/FLUSH is sent after
> > direct IO.
> 
> What I mean is that the server itself can call fsync(2) from the WRITE
> request if it finds that fi->flags contains O_DSYNC.

Right, I missed that with no_open FUSE_DIRECT_IO is not possible,
thanks for clarifying it.

thanks,
-liubo