Hi Olga,
On Wed, Sep 24, 2014 at 1:47 PM, Olga Kornievskaia <aglo@xxxxxxxxx> wrote:
> There exists a problem in the code that was easily reproducible prior
> to the commit b757144fd77cf5512f5b60179ba5ca8dcc5184b4 ("NFSv4 Be less
> aggressive about returning delegations"). The same code is used during
> delegation return and is still reproducible (with highly coordinated
> setup of triggering just the right actions).
>
> The problem lies in the call of nfs4_lock_delegation_recall(). In the
> nutshell, when the LOCK op gets an error such as ERR_GRACE, the error
> is unhanded which leaves the client in incorrect state assuming that
> it has 'successfully' acquired a lock that was locally acquired while
> holding a delegation.
>
> I believe the problem stems from the fact that
> nfs4_lock_delegation_recall(), unlike normal version of LOCK
> nfs4_proc_getlk(), lacks the do { handle_error(do_proc())} while(err)
> structure.
>
> I believe the problem should be fixed by something like the following:
>
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 6ca0c8e..78d088c 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -5936,11 +5936,12 @@ int nfs4_lock_delegation_recall(struct
> file_lock *fl, struct nfs4_state *state,
> struct nfs_server *server = NFS_SERVER(state->inode);
> int err;
>
> - err = nfs4_set_lock_state(state, fl);
> - if (err != 0)
> - return err;
> - err = _nfs4_do_setlk(state, F_SETLK, fl, NFS_LOCK_NEW);
> - return nfs4_handle_delegation_recall_error(server, state, stateid, err);
> + do {
> + err = nfs4_handle_delegation_recall_error(server, state,
> + stateid, _nfs4_do_setlk(state, F_SETLK, fl,
> + NFS_LOCK_NEW));
> + } while (err == -EAGAIN);
> + return err;
> }
>
> struct nfs_release_lockowner_data {
>
> Is this an acceptable solution?
>
In the current code, I expect the EAGAIN from
nfs4_handle_delegation_recall_error() to be propagated back to
nfs_end_delegation_return(). It should then result in the client
waiting for state recovery to complete followed by a loop back to
nfs_delegation_claim_opens().
Could you explain why that isn't working for your case?
--
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@xxxxxxxxxxxxxxx
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