Re: [PATCH v4 04/10] nfsd: Fix delegation revocation

[Jeff Layton <jeff.layton@primarydata.com>]

On Fri, 18 Jul 2014 12:44:17 -0400
"J. Bruce Fields" <bfields@fieldses.org> wrote:

> On Fri, Jul 18, 2014 at 11:13:30AM -0400, Jeff Layton wrote:
> > Ensure that the delegations cannot be found by the laundromat etc once
> > we add them to the various 'revoke' lists.
> 
> So if I understand right, the big mutex protects all of this right now,
> so this is all just moving the unhashing under a finer-grained lock to
> prevent that in-between state being exposed after the big lock's
> dropped.  Looks reasonable.
> 
> --b.
> 

Yes, sorry -- I forgot the obligatory "this is not a problem until the
client_mutex goes away" comment...

> > 
> > Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
> > Signed-off-by: Jeff Layton <jlayton@primarydata.com>
> > Reviewed-by: Christoph Hellwig <hch@lst.de>
> > ---
> >  fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++----------------
> >  1 file changed, 21 insertions(+), 16 deletions(-)
> > 
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index 60ae21abce00..7c5233427c9b 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -650,13 +650,13 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp)
> >  	list_add(&dp->dl_perclnt, &dp->dl_stid.sc_client->cl_delegations);
> >  }
> >  
> > -/* Called under the state lock. */
> >  static void
> > -unhash_delegation(struct nfs4_delegation *dp)
> > +unhash_delegation_locked(struct nfs4_delegation *dp)
> >  {
> >  	struct nfs4_file *fp = dp->dl_file;
> >  
> > -	spin_lock(&state_lock);
> > +	lockdep_assert_held(&state_lock);
> > +
> >  	dp->dl_stid.sc_type = NFS4_CLOSED_DELEG_STID;
> >  	spin_lock(&fp->fi_lock);
> >  	list_del_init(&dp->dl_perclnt);
> > @@ -665,7 +665,6 @@ unhash_delegation(struct nfs4_delegation *dp)
> >  	spin_unlock(&fp->fi_lock);
> >  	if (fp)
> >  		nfs4_put_deleg_lease(fp);
> > -	spin_unlock(&state_lock);
> >  }
> >  
> >  static void destroy_revoked_delegation(struct nfs4_delegation *dp)
> > @@ -676,7 +675,9 @@ static void destroy_revoked_delegation(struct nfs4_delegation *dp)
> >  
> >  static void destroy_delegation(struct nfs4_delegation *dp)
> >  {
> > -	unhash_delegation(dp);
> > +	spin_lock(&state_lock);
> > +	unhash_delegation_locked(dp);
> > +	spin_unlock(&state_lock);
> >  	nfs4_put_delegation(dp);
> >  }
> >  
> > @@ -685,11 +686,10 @@ static void revoke_delegation(struct nfs4_delegation *dp)
> >  	struct nfs4_client *clp = dp->dl_stid.sc_client;
> >  
> >  	if (clp->cl_minorversion == 0)
> > -		destroy_delegation(dp);
> > +		destroy_revoked_delegation(dp);
> >  	else {
> > -		unhash_delegation(dp);
> >  		dp->dl_stid.sc_type = NFS4_REVOKED_DELEG_STID;
> > -		list_add(&dp->dl_recall_lru, &clp->cl_revoked);
> > +		list_move(&dp->dl_recall_lru, &clp->cl_revoked);
> >  	}
> >  }
> >  
> > @@ -1447,15 +1447,16 @@ destroy_client(struct nfs4_client *clp)
> >  	spin_lock(&state_lock);
> >  	while (!list_empty(&clp->cl_delegations)) {
> >  		dp = list_entry(clp->cl_delegations.next, struct nfs4_delegation, dl_perclnt);
> > -		list_del_init(&dp->dl_perclnt);
> > +		unhash_delegation_locked(dp);
> >  		/* Ensure that deleg break won't try to requeue it */
> >  		++dp->dl_time;
> > -		list_move(&dp->dl_recall_lru, &reaplist);
> > +		list_add(&dp->dl_recall_lru, &reaplist);
> >  	}
> >  	spin_unlock(&state_lock);
> >  	while (!list_empty(&reaplist)) {
> >  		dp = list_entry(reaplist.next, struct nfs4_delegation, dl_recall_lru);
> > -		destroy_delegation(dp);
> > +		list_del_init(&dp->dl_recall_lru);
> > +		nfs4_put_delegation(dp);
> >  	}
> >  	list_splice_init(&clp->cl_revoked, &reaplist);
> >  	while (!list_empty(&reaplist)) {
> > @@ -3655,7 +3656,7 @@ nfs4_open_delegation(struct net *net, struct svc_fh *fh,
> >  	open->op_delegate_type = NFS4_OPEN_DELEGATE_READ;
> >  	return;
> >  out_free:
> > -	destroy_delegation(dp);
> > +	nfs4_put_delegation(dp);
> >  out_no_deleg:
> >  	open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE;
> >  	if (open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS &&
> > @@ -3894,7 +3895,8 @@ nfs4_laundromat(struct nfsd_net *nn)
> >  			new_timeo = min(new_timeo, t);
> >  			break;
> >  		}
> > -		list_move(&dp->dl_recall_lru, &reaplist);
> > +		unhash_delegation_locked(dp);
> > +		list_add(&dp->dl_recall_lru, &reaplist);
> >  	}
> >  	spin_unlock(&state_lock);
> >  	list_for_each_safe(pos, next, &reaplist) {
> > @@ -5369,7 +5371,8 @@ static u64 nfsd_find_all_delegations(struct nfs4_client *clp, u64 max,
> >  			 * don't monkey with it now that we are.
> >  			 */
> >  			++dp->dl_time;
> > -			list_move(&dp->dl_recall_lru, victims);
> > +			unhash_delegation_locked(dp);
> > +			list_add(&dp->dl_recall_lru, victims);
> >  		}
> >  		if (++count == max)
> >  			break;
> > @@ -5624,12 +5627,14 @@ nfs4_state_shutdown_net(struct net *net)
> >  	spin_lock(&state_lock);
> >  	list_for_each_safe(pos, next, &nn->del_recall_lru) {
> >  		dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
> > -		list_move(&dp->dl_recall_lru, &reaplist);
> > +		unhash_delegation_locked(dp);
> > +		list_add(&dp->dl_recall_lru, &reaplist);
> >  	}
> >  	spin_unlock(&state_lock);
> >  	list_for_each_safe(pos, next, &reaplist) {
> >  		dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
> > -		destroy_delegation(dp);
> > +		list_del_init(&dp->dl_recall_lru);
> > +		nfs4_put_delegation(dp);
> >  	}
> >  
> >  	nfsd4_client_tracking_exit(net);
> > -- 
> > 1.9.3
> > 


-- 
Jeff Layton <jlayton@primarydata.com>