nfsd: clarify readdir/mountpoint-crossing code

The code here is difficult to understand; attempt to clarify somewhat by
pulling out one of the more mystifying conditionals into a separate
function.

While we're here, also add lease_time to the list of attributes that we
don't really need to cross a mountpoint to fetch.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: Peter Staubach <staubach@redhat.com>

fs/nfsd/nfs4xdr.c

@@ -1867,6 +1867,15 @@ out_serverfault:
 	goto out;
 }
 
+static inline int attributes_need_mount(u32 *bmval)
+{
+	if (bmval[0] & ~(FATTR4_WORD0_RDATTR_ERROR | FATTR4_WORD0_LEASE_TIME))
+		return 1;
+	if (bmval[1] & ~FATTR4_WORD1_MOUNTED_ON_FILEID)
+		return 1;
+	return 0;
+}
+
 static __be32
 nfsd4_encode_dirent_fattr(struct nfsd4_readdir *cd,
 		const char *name, int namlen, __be32 *p, int *buflen)
@@ -1888,9 +1897,7 @@ nfsd4_encode_dirent_fattr(struct nfsd4_readdir *cd,
 	 * we will not follow the cross mount and will fill the attribtutes
 	 * directly from the mountpoint dentry.
 	 */
-	if (d_mountpoint(dentry) &&
-	    (cd->rd_bmval[0] & ~FATTR4_WORD0_RDATTR_ERROR) == 0 &&
-	    (cd->rd_bmval[1] & ~FATTR4_WORD1_MOUNTED_ON_FILEID) == 0)
+	if (d_mountpoint(dentry) && !attributes_need_mount(cd->rd_bmval))
 		ignore_crossmnt = 1;
 	else if (d_mountpoint(dentry)) {
 		int err;