From: Trond Myklebust <trondmy@hammerspace.com>
To: "rmacklem@uoguelph.ca" <rmacklem@uoguelph.ca>,
"chuck.lever@oracle.com" <chuck.lever@oracle.com>
Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: knfsd server returns writeverf of all 0 bits (but was not rebooted)
Date: Mon, 13 Dec 2021 19:54:57 +0000 [thread overview]
Message-ID: <6672752c94036f159816c19756fe4d77ca9bddd8.camel@hammerspace.com> (raw)
In-Reply-To: <E98AB758-5406-449B-96E7-C7FBD0BA98B3@oracle.com>
On Mon, 2021-12-13 at 19:42 +0000, Chuck Lever III wrote:
> Hi Rick-
>
> > On Dec 9, 2021, at 6:15 PM, Rick Macklem <rmacklem@uoguelph.ca>
> > wrote:
> >
> > Hi,
> >
> > When testing against the knfsd in a Linux 5.15.1 kernel, I received
> > a
> > write reply with FILE_SYNC and a writeverf of all 0 bytes.
> > (Previous write verifiers were not all 0 bytes.)
> >
> > The server seemed to be functioning normally and had not rebooted.
> >
> > Is this intended behaviour?
> >
> > Normally I would not expect the writeverf in a Write operation
> > reply
> > to change unless the server had rebooted, but I can see there might
> > be circumstances where the knfsd server wants all non-FILE_SYNC
> > writes to be redone by the client and would choose to change the
> > writeverf.
> > However, changing it to all 0 bytes seems particularly odd?
>
> I don't immediately see a code path for WRITE or COMMIT that would
> set the verifier to zeroes. When Linux NFSD resets its write
> verifier,
> it sets it to the current time.
>
> Do you have a reproducer you can share?
>
Rick is using FILE_SYNC, whereas nfsd_vfs_write() only actually sets
the boot verifier if the write is unstable or DATA_SYNC.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com
next prev parent reply other threads:[~2021-12-13 19:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-09 23:15 knfsd server returns writeverf of all 0 bits (but was not rebooted) Rick Macklem
2021-12-13 19:42 ` Chuck Lever III
2021-12-13 19:54 ` Trond Myklebust [this message]
2021-12-13 20:06 ` Chuck Lever III
2021-12-13 22:04 ` Rick Macklem
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