[CIFS] Fix unlink oops when indirectly called in rename error path
under heavy stress.

Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index e842ce9..ca91ea38 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -569,7 +569,10 @@
 
 	xid = GetXid();
 
-	cifs_sb = CIFS_SB(inode->i_sb);
+	if(inode)
+		cifs_sb = CIFS_SB(inode->i_sb);
+	else
+		cifs_sb = CIFS_SB(dentry->d_sb);
 	pTcon = cifs_sb->tcon;
 
 	/* Unlink can be called from rename so we can not grab the sem here