On Fri, Dec 19, 2014 at 1:52 PM, Trond Myklebust
<trond.myklebust@xxxxxxxxxxxxxxx> wrote:
> Ensure that we deal correctly with the case where the server sends us a
> newer instance of the same delegation. If the stateids match, but the
> sequence numbers differ, then treat the new delegation as if it were
> an atomic upgrade.
>
> Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxxxxxxx>
> ---
> fs/nfs/delegation.c | 21 ++++++++++++++++++---
> 1 file changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
> index 7f3f60641344..02b5b2a6d557 100644
> --- a/fs/nfs/delegation.c
> +++ b/fs/nfs/delegation.c
> @@ -301,6 +301,19 @@ nfs_inode_detach_delegation(struct inode *inode)
> return nfs_detach_delegation(nfsi, delegation, server);
> }
>
> +static void
> +nfs_update_inplace_delegation(struct nfs_inode *nfsi,
> + struct nfs_delegation *delegation,
> + struct nfs_delegation *update)
> +{
> + if (nfs4_stateid_is_newer(&update->stateid, &delegation->stateid))
...and the above comparison should be reversed.
> + return;
> + delegation->stateid.seqid = update->stateid.seqid;
> + smp_wmb();
> + delegation->type = update->type;
> + nfsi->delegation_state = update->type;
> +}
> +
> /**
> * nfs_inode_set_delegation - set up a delegation on an inode
> * @inode: inode to which delegation applies
> @@ -334,9 +347,11 @@ int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct
> old_delegation = rcu_dereference_protected(nfsi->delegation,
> lockdep_is_held(&clp->cl_lock));
> if (old_delegation != NULL) {
> - if (nfs4_stateid_match(&delegation->stateid,
> - &old_delegation->stateid) &&
> - delegation->type == old_delegation->type) {
> + /* Is this an update of the existing delegation? */
> + if (nfs4_stateid_match_other(&old_delegation->stateid,
> + &delegation->stateid)) {
> + nfs_update_inplace_delegation(nfsi, old_delegation,
> + delegation);
> goto out;
> }
> /*
> --
> 2.1.0
>
--
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@xxxxxxxxxxxxxxx
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