NFSv4: Use RCU to protect delegations

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/fs/nfs/delegation.h b/fs/nfs/delegation.h
index 8f79a3135167..5874ce7fdbae 100644
--- a/fs/nfs/delegation.h
+++ b/fs/nfs/delegation.h
@@ -22,6 +22,7 @@ struct nfs_delegation {
         long flags;
         loff_t maxsize;
         __u64 change_attr;
+        struct rcu_head rcu;
 };
 
 int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res);
@@ -45,11 +46,16 @@ int nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode);
 
 static inline int nfs_have_delegation(struct inode *inode, int flags)
 {
+        struct nfs_delegation *delegation;
+        int ret = 0;
+
         flags &= FMODE_READ|FMODE_WRITE;
-        smp_rmb();
-        if ((NFS_I(inode)->delegation_state & flags) == flags)
-                return 1;
-        return 0;
+        rcu_read_lock();
+        delegation = rcu_dereference(NFS_I(inode)->delegation);
+        if (delegation != NULL && (delegation->type & flags) == flags)
+                ret = 1;
+        rcu_read_unlock();
+        return ret;
 }
 
 #else