Bug#1017720: nfs-common: No such file or directory
I also see the failure with the kernels below, but the 4.19.X kernel resolves the issue without dropping caches.
linux-image-4.19.0-14-amd64 4.19.171-2 amd64 Linux 4.19 for 64-bit PCs (signed)
linux-image-4.19.0-21-amd64 4.19.249-2 amd64 Linux 4.19 for 64-bit PCs (signed)
I see the issue running the initial test, but then the issue is gone when running the test a subsequent time.
I ran several tests to verify the behavior differences between the 4.19.X and 5.X kernels.
-- Test
ls -l /mnt/dir/someOtherDir/* | grep '?'
-- Error message - the error message is showing files that have been erased via rsync --delete
ls: cannot access 'filename': No such file or directory
-????????? ? ? ? ? ? filename
> -----Original Message-----
> From: Jason Breitman
> Sent: Friday, September 2, 2022 5:17 PM
> To: Ben Hutchings <ben@decadent.org.uk>; 1017720@bugs.debian.org
> Subject: RE: Bug#1017720: nfs-common: No such file or directory
>
> I have tested with the following kernels and see this issue in each case.
>
> linux-image-5.10.0-16-amd64 5.10.127-1 amd64 Linux
> 5.10 for 64-bit PCs (signed)
> linux-image-5.15.0-0.bpo.3-amd64 5.15.15-2~bpo11+1 amd64
> Linux 5.15 for 64-bit PCs (signed)
> linux-image-5.18.0-0.deb11.3-amd64 5.18.14-1~bpo11+1 amd64
> Linux 5.18 for 64-bit PCs (signed)
>
> An interesting note is that when using the 5.18 kernel, I had to run echo 3 >
> /proc/sys/vm/drop_caches to resolve the issue.
> echo 2 > /proc/sys/vm/drop_caches did not work as it did on the 5.10 and
> 5.15 kernels.
>
> > -----Original Message-----
> > From: Jason Breitman
> > Sent: Friday, August 26, 2022 3:36 PM
> > To: 'Ben Hutchings' <ben@decadent.org.uk>; '1017720@bugs.debian.org'
> > <1017720@bugs.debian.org>
> > Subject: RE: Bug#1017720: nfs-common: No such file or directory
> >
> > I was able to identify another workaround today which may help you to
> > identify the issue.
> > The workaround is to touch the directory where the troubled files live on
> the
> > file server.
> > I believe this tells us that updating the modify time attribute is used by the
> > cache.
> > It should be noted that access time updates are disabled on the file server.
> >
> > I also wanted to restate that we use rsync to push out these application
> > updates and also use rsync to sync data files.
> > Our rsync options preserve timestamps, so it is possible that the new files
> > have an older timestamp than "now".
> > It is not the case that the new files have an older timestamp than the prior
> > version that is stuck in the cache.
> >
> > The rsync process that I describe has not changed and has been in use for
> > many years.
> >
> > > -----Original Message-----
> > > From: Jason Breitman
> > > Sent: Thursday, August 25, 2022 11:54 AM
> > > To: Ben Hutchings <ben@decadent.org.uk>; 1017720@bugs.debian.org
> > > Subject: RE: Bug#1017720: nfs-common: No such file or directory
> > >
> > > I have the same issue after adding actimeo=30 to /etc/fstab, rebooting
> and
> > > testing.
> > > I also confirmed that those settings applied via /proc/mounts which
> shows
> > > the below snippet for each mountpoint.
> > > nfs4
> > >
> >
> rw,relatime,vers=4.1,rsize=131072,wsize=131072,namlen=255,acregmin=30,a
> > >
> >
> cregmax=30,acdirmax=30,hard,noresvport,proto=tcp,timeo=600,retrans=2,s
> > >
> >
> ec=krb5,clientaddr=X.X.X.X,lookupcache=pos,local_lock=none,addr=Y.Y.Y.Y 0
> > > 0
> > >
> > > > -----Original Message-----
> > > > From: Jason Breitman
> > > > Sent: Tuesday, August 23, 2022 2:42 PM
> > > > To: Ben Hutchings <ben@decadent.org.uk>; 1017720@bugs.debian.org
> > > > Subject: RE: Bug#1017720: nfs-common: No such file or directory
> > > >
> > > > What additional information can I provide for us to move forward with
> > this
> > > > process?
> > > >
> > > > To summarize and include further details, rsync is used to sync
> > applications
> > > to
> > > > a file server which behaves like a repository.
> > > > We do preserve timestamps from the build server and also use --
> delete.
> > > We
> > > > do not run the applications from the file server. All servers use NTP.
> > > >
> > > > The application has a sub-directory that contain files with version
> > numbers.
> > > > These are libraries.
> > > > When a new build is complete, a developer pushes their updates via
> > rsync
> > > to
> > > > the file server / repository.
> > > >
> > > > I believe that the dentry cache thinks the "old" files exist and generates
> a
> > > No
> > > > such file or directory error showing question marks for that files
> > attributes.
> > > > Dropping the dentry cache via echo 2 > /proc/sys/vm/drop_caches
> > > resolves
> > > > the issue.
> > > >
> > > > This behavior is not observed in Debian 10.8 with that distributions
> > > associated
> > > > kernel and packages.
> > > >
> > > > > -----Original Message-----
> > > > > From: Jason Breitman
> > > > > Sent: Friday, August 19, 2022 9:52 PM
> > > > > To: Ben Hutchings <ben@decadent.org.uk>;
> 1017720@bugs.debian.org
> > > > > Subject: RE: Bug#1017720: nfs-common: No such file or directory
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Ben Hutchings <ben@decadent.org.uk>
> > > > > > Sent: Friday, August 19, 2022 7:27 PM
> > > > > > To: Jason Breitman <jbreitman@tildenparkcapital.com>;
> > > > > > 1017720@bugs.debian.org
> > > > > > Subject: Re: Bug#1017720: nfs-common: No such file or directory
> > > > > >
> > > > > > Control: tag -1 moreinfo
> > > > > >
> > > > > > On Fri, 2022-08-19 at 13:16 +0000, Jason Breitman wrote:
> > > > > > > Package: nfs-common
> > > > > > > Version: 1:1.3.4-6
> > > > > > > Severity: important
> > > > > > >
> > > > > > > Kernel: 5.10.0-16-amd64 #1 SMP Debian 5.10.127-1 (2022-06-30)
> > > x86_64
> > > > > > > GNU/Linux
> > > > > > >
> > > > > > > -- Description
> > > > > > > After updating and or creating new files on our file server via
> > > > > > > rsync, we see many files report the error message below from
> > NFSv4
> > > > > > > clients since upgrading from Debian 10.8 to Debian 11.4.
> > > > > > > Clearing the dentry cache resolves the issue right away.
> > > > > > > I am not sure that nfs-common is the package to blame, but
> listed
> > > > > > > it based on the bug submission recommendations.
> > > > > >
> > > > > > The NFS implementation is mostly in the kernel, so probably this
> issue
> > > > > > belongs there. But the kernel team is responsible for both
> packages.
> > > > > >
> > > > > > [...]
> > > > > > > -- Error message
> > > > > > > ls: cannot access 'filename': No such file or directory
> > > > > > > -????????? ? ? ? ? ? filename
> > > > > > [...]
> > > > > >
> > > > > > So we know the file's there but can't stat it. I think this means the
> > > > > > client has cached the handle of the old file of that name, which has
> > > > > > been deleted.
> > > > > >
> > > > > > - Are client and server clocks closely synchronised? If not, that
> > > > > > needs to be fixed.
> > > > > >
> > > > > The clocks are synchronized using NTP.
> > > > >
> > > > > > - Are clients likely to read this directory while rsync is running, or
> > > > > > shortly before? If so, it may help to reduce the attribute caching
> > > > > > timeout on the client. See the "Directory entry caching" section in
> > > > > > the nfs(5) manual page.
> > > > > >
> > > > > Clients are not likely to read this directory while rsync is running for
> the
> > > > > observed cases. That can happen in our environment, but not in this
> > > case.
> > > > > I am using the lookupcache=pos option. I tried noac, but the
> > > performance
> > > > > penalty was too much. Which option are you referring to and what
> > > setting
> > > > > do you recommend testing?
> > > > >
> > > > > > I don't know why you're only seeing this after an upgrade of the
> > > > > > clients, though. I'm not aware that there has been any big change
> to
> > > > > > attribute caching.
> > > > > >
> > > > > I appreciate you responding to my report and am happy to answer
> any
> > > > > questions.
> > > > > We have multiple monitors and log scrapers to detect "file not found"
> > > > > exceptions that would let us know if this was happening before.
> > > > > To share more, I have 2 environments mounting from the same file
> > > server.
> > > > > Each environment has several servers. The issue is only seen in the
> > > > > environment running Debian 11.4.
> > > > > I also should have mentioned that the files in question have a version
> > > > > number appended. filename-1111. When the file is updated via
> rsync,
> > it
> > > is
> > > > > called filename-1112 and the prior file is removed. The error is about
> > > > > filename-1111.
> > > > > I am not sure if this is the proper terminology, but the issue appears
> to
> > be
> > > > > the negative dentry cache.
> > > > >
> > > > > > Ben.
> > > > > >
> > > > > > --
> > > > > > Ben Hutchings
> > > > > > Beware of bugs in the above code;
> > > > > > I have only proved it correct, not tried it. - Donald Knuth
> > > > >
> > > > > Jason Breitman
> > > > Jason Breitman
> > > Jason Breitman
> > Jason Breitman
> Jason Breitman
Jason Breitman
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