libceph: subscribe to osdmap when cluster is full

When the cluster is marked full, subscribe to subsequent map updates to
ensure we find out promptly when it is no longer full.  This will prevent
us from spewing ENOSPC for (much) longer than necessary.
Signed-off-by: Sage Weil <sage@newdream.net>

net/ceph/osd_client.c

@@ -1421,6 +1421,15 @@ void ceph_osdc_handle_map(struct ceph_osd_client *osdc, struct ceph_msg *msg)
 done:
 	downgrade_write(&osdc->map_sem);
 	ceph_monc_got_osdmap(&osdc->client->monc, osdc->osdmap->epoch);
+
+	/*
+	 * subscribe to subsequent osdmap updates if full to ensure
+	 * we find out when we are no longer full and stop returning
+	 * ENOSPC.
+	 */
+	if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL))
+		ceph_monc_request_next_osdmap(&osdc->client->monc);
+
 	send_queued(osdc);
 	up_read(&osdc->map_sem);
 	wake_up_all(&osdc->client->auth_wq);