setfacl removes part of ACL when setting POSIX ACLs to Samba

commit b1d93356 upstream.

setfacl over cifs mounts can remove the default ACL when setting the
(non-default part of) the ACL and vice versa (we were leaving at 0
rather than setting to -1 the count field for the unaffected
half of the ACL.  For example notice the setfacl removed
the default ACL in this sequence:

steven@steven-GA-970A-DS3:~/cifs-2.6$ getfacl /mnt/test-dir ; setfacl
-m default:user:test:rwx,user:test:rwx /mnt/test-dir
getfacl: Removing leading '/' from absolute path names
user::rwx
group::r-x
other::r-x
default:user::rwx
default:user:test:rwx
default:group::r-x
default:mask::rwx
default:other::r-x

steven@steven-GA-970A-DS3:~/cifs-2.6$ getfacl /mnt/test-dir
getfacl: Removing leading '/' from absolute path names
user::rwx
user:test:rwx
group::r-x
mask::rwx
other::r-x
Signed-off-by: Steve French <smfrench@gmail.com>
Acked-by: Jeremy Allison <jra@samba.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

fs/cifs/cifssmb.c

@@ -3437,11 +3437,13 @@ static __u16 ACL_to_cifs_posix(char *parm_data, const char *pACL,
 		return 0;
 	}
 	cifs_acl->version = cpu_to_le16(1);
-	if (acl_type == ACL_TYPE_ACCESS)
+	if (acl_type == ACL_TYPE_ACCESS) {
 		cifs_acl->access_entry_count = cpu_to_le16(count);
-	else if (acl_type == ACL_TYPE_DEFAULT)
+		cifs_acl->default_entry_count = __constant_cpu_to_le16(0xFFFF);
+	} else if (acl_type == ACL_TYPE_DEFAULT) {
 		cifs_acl->default_entry_count = cpu_to_le16(count);
-	else {
+		cifs_acl->access_entry_count = __constant_cpu_to_le16(0xFFFF);
+	} else {
 		cFYI(1, "unknown ACL type %d", acl_type);
 		return 0;
 	}