linux-kernel - Re: [PATCH v2] NFSv4: try lease recovery on NFS4ERR

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Date:   Fri, 17 Jan 2020 17:24:26 +0000
From:   Trond Myklebust <trondmy@...merspace.com>
To:     "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "rmilkowski@...il.com" <rmilkowski@...il.com>
CC:     "anna.schumaker@...app.com" <anna.schumaker@...app.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "chuck.lever@...cle.com" <chuck.lever@...cle.com>
Subject: Re: [PATCH v2] NFSv4: try lease recovery on NFS4ERR_EXPIRED

On Fri, 2020-01-17 at 16:12 +0000, Robert Milkowski wrote:
> Anyone please?
> 
> 
> -----Original Message-----
> From: Robert Milkowski <rmilkowski@...il.com> 
> Sent: 08 January 2020 21:48
> To: linux-nfs@...r.kernel.org
> Cc: 'Trond Myklebust' <trondmy@...merspace.com>; 'Chuck Lever'
> <chuck.lever@...cle.com>; 'Anna Schumaker' <anna.schumaker@...app.com
> >;
> linux-kernel@...r.kernel.org
> Subject: [PATCH v2] NFSv4: try lease recovery on NFS4ERR_EXPIRED
> 
> From: Robert Milkowski <rmilkowski@...il.com>
> 
> Currently, if an nfs server returns NFS4ERR_EXPIRED to open(), etc.
> we return EIO to applications without even trying to recover.
> 
> Fixes: 272289a3df72 ("NFSv4: nfs4_do_handle_exception() handle
> revoke/expiry
> of a single stateid")
> Signed-off-by: Robert Milkowski <rmilkowski@...il.com>
> ---
>  fs/nfs/nfs4proc.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index
> 76d3716..2478405
> 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -481,6 +481,10 @@ static int nfs4_do_handle_exception(struct
> nfs_server
> *server,
>  						stateid);
>  				goto wait_on_recovery;
>  			}
> +			if (state == NULL) {
> +				nfs4_schedule_lease_recovery(clp);
> +				goto wait_on_recovery;
> +			}
>  			/* Fall through */
>  		case -NFS4ERR_OPENMODE:
>  			if (inode) {
> --
> 1.8.3.1
> 
> 

Does this apply to any case other than NFS4ERR_EXPIRED in the specific
case of nfs4_do_open()? I can't see that it does. It looks to me as if
the open recovery routines already have their own handling of this
case.

If so, why not just add it as a special case in the nfs4_do_open()
error handling? Otherwise this patch will end up overriding other
generic cases where we have an inode, but no open state.

Note that _nfs4_do_open() already waits for lease recovery, so we only
need the call to nfs_schedule_lease_recovery().

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@...merspace.com