linux-kernel - Re: PROBLEM: NFS client IO fails with ERESTARTSYS when another mount point with the same export is unmounted with force [NFS] [SUNRPC]

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Date: Thu, 22 Feb 2024 06:05:02 -0500
From: Jeff Layton <jlayton@...nel.org>
To: Trond Myklebust <trondmy@...merspace.com>, "chuck.lever@...cle.com"
 <chuck.lever@...cle.com>, "zhitao.li@...rtx.com" <zhitao.li@...rtx.com>, 
 "tom@...pey.com" <tom@...pey.com>, "anna@...nel.org" <anna@...nel.org>,
 "Dai.Ngo@...cle.com" <Dai.Ngo@...cle.com>, "neilb@...e.de" <neilb@...e.de>,
 "kolga@...app.com" <kolga@...app.com>
Cc: "huangping@...rtx.com" <huangping@...rtx.com>, 
	"linux-nfs@...r.kernel.org"
	 <linux-nfs@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	 <linux-kernel@...r.kernel.org>
Subject: Re: PROBLEM: NFS client IO fails with ERESTARTSYS when another
 mount point with the same export is unmounted with force [NFS] [SUNRPC]

On Wed, 2024-02-21 at 13:48 +0000, Trond Myklebust wrote:
> On Wed, 2024-02-21 at 16:20 +0800, Zhitao Li wrote:
> > [You don't often get email from zhitao.li@...rtx.com. Learn why this
> > is important at https://aka.ms/LearnAboutSenderIdentification ]
> > 
> > Hi, everyone,
> > 
> > - Facts:
> > I have a remote NFS export and I mount the same export on two
> > different directories in my OS with the same options. There is an
> > inflight IO under one mounted directory. And then I unmount another
> > mounted directory with force. The inflight IO ends up with "Unknown
> > error 512", which is ERESTARTSYS.
> > 
> 
> All of the above is well known. That's because forced umount affects
> the entire filesystem. Why are you using it here in the first place? It
> is not intended for casual use.
> 

While I agree Trond's above statement, the kernel is not supposed to
leak error codes that high into userland. Are you seeing ERESTARTSYS
being returned to system calls? If so, which ones?
-- 
Jeff Layton <jlayton@...nel.org>