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Message-ID: <c1d98e76-1b5c-4d91-a7fe-9412df7c2fab@grimberg.me>
Date: Wed, 22 May 2024 22:40:17 +0300
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Subject: Re: [PATCH rfc] nfs: propagate readlink errors in nfs_symlink_filler
From: Sagi Grimberg <sagi@grimberg.me>
To: Trond Myklebust <trondmy@hammerspace.com>,
 "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
 "jlayton@kernel.org" <jlayton@kernel.org>
Cc: "hch@lst.de" <hch@lst.de>, "dan.aloni@vastdata.com"
 <dan.aloni@vastdata.com>, "chuck.lever@oracle.com" <chuck.lever@oracle.com>
References: <20240521125840.186618-1-sagi@grimberg.me>
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Hey Trond,

>> filehandle is stale? There will have been an unlink() on the symlink at
>> some point in the recent past.
>>
>
> No reason that I can see. However given that this was observed in the 
> wild, and essentially
> a common pattern with symlinks (overwrite a config file for example), 
> I think its reasonable
> to have the vfs at least do a single retry, by simply returning ESTALE.
> However NFS cannot distinguish between first and second retries 
> afaict... Perhaps the
> vfs can help with a ESTALE->ENOENT conversion?

So what do you suggest we do here? IMO at a minimum NFS should retry 
once similar
to nfs4_file_open (it would probably address 99.9% of the use-cases 
where symlinks are
not overwritten in a high enough frequency for the client to see 2 
consecutive stale readlink
rpc rplies).

I can send a patch paired with a vfs ESTALE conversion patch? 
alternatively retry locally in NFS...
I would like to understand your position here.