NFS: Don't run nfs_access_cache_shrinker() when the mask is GFP_NOFS

Both iput() and put_rpccred() might allocate memory under certain
circumstances, so make sure that we don't recurse and deadlock...

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 18da8ab..58b1f74 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1703,6 +1703,8 @@
 	struct nfs_inode *nfsi;
 	struct nfs_access_entry *cache;
 
+	if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
+		return (nr_to_scan == 0) ? 0 : -1;
 restart:
 	spin_lock(&nfs_access_lru_lock);
 	list_for_each_entry(nfsi, &nfs_access_lru_list, access_cache_inode_lru) {