orangefs: delay freeing slot until cancel completes

Make cancels reuse the aborted read/write op, to make sure they do not
fail on lack of memory.

Don't issue a cancel unless the daemon has seen our read/write, has not
replied and isn't being shut down.

If cancel *is* issued, don't wait for it to complete; stash the slot
in there and just have it freed when cancel is finally replied to or
purged (and delay dropping the reference until then, obviously).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

fs/orangefs/orangefs-mod.c

@@ -260,14 +260,12 @@ void purge_inprogress_ops(void)
 					 next,
 					 &htable_ops_in_progress[i],
 					 list) {
-			spin_lock(&op->lock);
 			gossip_debug(GOSSIP_INIT_DEBUG,
 				"pvfs2-client-core: purging in-progress op tag "
 				"%llu %s\n",
 				llu(op->tag),
 				get_opname_string(op));
 			set_op_state_purged(op);
-			spin_unlock(&op->lock);
 		}
 		spin_unlock(&htable_ops_in_progress_lock);
 	}