Branch b1_4

b=11686
i=green, adilger

improve some error messages.

lnet/libcfs/tracefile.c

@@ -655,8 +655,9 @@ int tracefile_dump_all_pages(char *filename)
         filp = cfs_filp_open(filename,
                              O_CREAT|O_EXCL|O_WRONLY|O_LARGEFILE, 0600, &rc);
         if (!filp) {
-                printk(KERN_ERR "LustreError: can't open %s for dump: rc %d\n",
-                       filename, rc);
+                if (rc != -EEXIST)
+                        printk(KERN_ERR "LustreError: can't open %s for dump: rc %d\n",
+                               filename, rc);
                 goto out;
         }