CIFS: Add rwpidforward mount option

Add rwpidforward mount option that switches on a mode when we forward
pid of a process who opened a file to any read and write operation.

This can prevent applications like WINE from failing on read or write
operation on a previously locked file region from the same netfd from
another process if we use mandatory brlock style.

It is actual for WINE because during a run of WINE program two processes
work on the same netfd - share the same file struct between several VFS
fds:
1) WINE-server does open and lock;
2) WINE-application does read and write.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 360fe2e..26981bf 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -415,12 +415,20 @@
 		seq_printf(s, ",nocase");
 	if (tcon->retry)
 		seq_printf(s, ",hard");
+	if (tcon->unix_ext)
+		seq_printf(s, ",unix");
+	else
+		seq_printf(s, ",nounix");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)
 		seq_printf(s, ",posixpaths");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID)
 		seq_printf(s, ",setuids");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)
 		seq_printf(s, ",serverino");
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
+		seq_printf(s, ",rwpidforward");
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL)
+		seq_printf(s, ",forcemand");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DIRECT_IO)
 		seq_printf(s, ",directio");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_XATTR)