NFSv4: Fix up another delegation related race
When we can update_open_stateid(), we need to be certain that we don't
race with a delegation return. While we could do this by grabbing the
nfs_client->cl_lock, a dedicated spin lock in the delegation structure
will scale better.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index cc563cf..e0cb4ee 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -140,13 +140,17 @@
if (delegation == NULL)
goto nomatch;
+ spin_lock(&delegation->lock);
if (stateid != NULL && memcmp(delegation->stateid.data, stateid->data,
sizeof(delegation->stateid.data)) != 0)
- goto nomatch;
+ goto nomatch_unlock;
list_del_rcu(&delegation->super_list);
nfsi->delegation_state = 0;
rcu_assign_pointer(nfsi->delegation, NULL);
+ spin_unlock(&delegation->lock);
return delegation;
+nomatch_unlock:
+ spin_unlock(&delegation->lock);
nomatch:
return NULL;
}
@@ -172,6 +176,7 @@
delegation->change_attr = nfsi->change_attr;
delegation->cred = get_rpccred(cred);
delegation->inode = inode;
+ spin_lock_init(&delegation->lock);
spin_lock(&clp->cl_lock);
if (rcu_dereference(nfsi->delegation) != NULL) {