NFS: Fix incorrect size revalidation when holding a delegation

We should only care about checking the attributes if the page cache
is marked as dubious (using NFS_INO_REVAL_PAGECACHE) and the
NFS_INO_REVAL_FORCED flag is set.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/file.c

@@ -102,8 +102,11 @@ static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
 {
 	struct nfs_server *server = NFS_SERVER(inode);
 	struct nfs_inode *nfsi = NFS_I(inode);
+	const unsigned long force_reval = NFS_INO_REVAL_PAGECACHE|NFS_INO_REVAL_FORCED;
+	unsigned long cache_validity = nfsi->cache_validity;
 
-	if (nfs_have_delegated_attributes(inode))
+	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_READ) &&
+	    (cache_validity & force_reval) != force_reval)
 		goto out_noreval;
 
 	if (filp->f_flags & O_DIRECT)