From:   "Frank Filz" <ffilzlnx@mindspring.com>
To:     "'Olga Kornievskaia'" <aglo@umich.edu>
Cc:     "'Andrew J. Romero'" <romero@fnal.gov>, <linux-nfs@vger.kernel.org>
References: <YQBPR01MB10724B629B69F7969AC6BDF9586C89@YQBPR01MB10724.CANPRD01.PROD.OUTLOOK.COM> <YQBPR01MB10724AEE306F99C844101EED086CF9@YQBPR01MB10724.CANPRD01.PROD.OUTLOOK.COM> <YQBPR01MB10724F79460F3C02361279E8686CF9@YQBPR01MB10724.CANPRD01.PROD.OUTLOOK.COM> <654e3b7d15992d191b2b2338483f29aec8b10ee1.camel@kernel.org> <YQBPR01MB10724B36E378F493B9DED3C7E86D39@YQBPR01MB10724.CANPRD01.PROD.OUTLOOK.COM> <3c02bd2df703a68093db057c51086bbf767ffeb1.camel@kernel.org> <YQBPR01MB1072428BC706EE8C5CC34341186D39@YQBPR01MB10724.CANPRD01.PROD.OUTLOOK.COM> <936efa478e786be19cb9715eba1941ebc4f94a1b.camel@kernel.org> <SA1PR09MB75521717AA00DCAD6CAB5118A7D39@SA1PR09MB7552.namprd09.prod.outlook.com> <CAN-5tyFro=naMgub9uAZ0wa20WhZwV2Rh6xv_meNice1EG+Dug@mail.gmail.com> <046e01d935a0$7b3a2d30$71ae8790$@mindspring.com> <CAN-5tyE+wKVtHWr+DF67DLN0pvO332dDajvBbeGyCFu1fyqdRQ@mail.gmail.com>
In-Reply-To: <CAN-5tyE+wKVtHWr+DF67DLN0pvO332dDajvBbeGyCFu1fyqdRQ@mail.gmail.com>
Subject: RE: Zombie / Orphan open files
Date:   Tue, 31 Jan 2023 13:31:42 -0800
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> On Tue, Jan 31, 2023 at 1:19 PM Frank Filz <ffilzlnx@mindspring.com> =
wrote:
> >
> > > On Mon, Jan 30, 2023 at 5:44 PM Andrew J. Romero <romero@fnal.gov>
> wrote:
> > > >
> > > > Hi
> > > >
> > > > This is a quick general NFS server question.
> > > >
> > > > Does the NFSv4x  specification require or recommend that:   the =
NFS
> server,
> > > after some reasonable time,
> > > > should / must close orphan / zombie open files ?
> > >
> > > Why should the server be responsible for a badly behaving client? =
It
> > > seems like you are advocating for the world where a problem is =
hidden
> rather than solved.
> > > But because bugs do occur and some customers want a quick =
solution,
> > > some storage providers do have ways of dealing with releasing
> > > resources (like open
> > > state) that the client will never ask for again.
> > >
> > > Why should we excuse bad user behaviour? For things like long
> > > running jobs users have to be educated that their credentials must
> > > stay valid for the duration of their usage.
> > >
> > > Why should we excuse poor application behaviour that doesn't close
> > > files? But in a way we do, the OS will make sure that the file is
> > > closed when the application exists without explicitly closing the
> > > file. So I'm curious how do you get in a state with zombie?
> >
> > Don't automatically assume this is bad application behavior, though =
it may be
> behavior we don't all like, sometimes it may be for a reason. =
Applications may
> be keeping a file open to protect the file (works best when share deny =
modes
> are available, i.e. most likely a Windows client). Also, won't an =
executable be
> kept open for the lifetime of the process, especially if the =
executable is large
> enough that it will be paged in/out from the file? This assures the =
same
> executable is available for the lifetime of the process even if =
deleted and
> replaced with a new version.
>=20
> Aren't you describing is a long running job (a file that needs to be =
kept opened --
> and not closed -- for a long period of time)? And it's a user's =
responsibility to
> have creds that are long enough (or a system of renewal) that covers =
the
> duration of the job. To be clear you are talking about a long running =
process that
> keeps a file opened.
> You are not talking about a process that starts, opens a file and the =
process exits
> without closing a file.  That's poor application behaviour I was =
referring too.
> Regardless in that situation OS cleans up. So I'm very curious how =
these
> zombie/orphan files are being created, how does it happens that the OS =
doesn't
> clean up.

Oh, OK, I see now I was confused, I see Andrew responded with a theory =
of what might be happening.

And yea, if the client is allowing credentials to expire while a file is =
still open, that's a problem.

Frank