Re: [PATCH] migration/multifd: Don't fsync when closing QIOChannelFile

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Mar 06, 2024 at 08:52:41AM +0800, Peter Xu wrote:
> On Tue, Mar 05, 2024 at 05:49:33PM +0000, Daniel P. Berrangé wrote:
> > I don't think you should be removing this. Calling qio_channel_close()
> > remains recommended best practice, even with fdatasync() removed, as
> > it provides a strong guarantee that the FD is released which you don't
> > get if you rely on the ref count being correctly decremented in all
> > code paths.
> 
> Hmm, I have the confusion on why ioc->fd is more special than the ioc
> itself when leaked.  It'll be a bug anyway if we leak any of them?  Leaking
> fds may also help us to find such issue easier (e.g. by seeing stale fds
> under /proc).  From that POV I tend to agree on the original proposal.

Closing the FD would cause any registered I/O handlers callbacks to
get POLLNVAL and may well trigger cleanup that will prevent the leak.

With regards,
Daniel
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