libceph: add function to ensure notifies are complete

Without a way to flush the osd client's notify workqueue, a watch event that is unregistered could continue receiving callbacks indefinitely. Unregistering the event simply means no new notifies are added to the queue, but there may still be events in the queue that will call the watch callback for the event. If the queue is flushed after the event is unregistered, the caller can be sure no more watch callbacks will occur for the canceled watch. Signed-off-by: Josh Durgin <[email protected]> Reviewed-by: Sage Weil <[email protected]> Reviewed-by: Alex Elder <[email protected]>
cbmeeks · Sep 9, 2013 · dd935f4 · dd935f4
1 parent a8d436f
commit dd935f4
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diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
@@ -335,6 +335,8 @@ extern int ceph_osdc_wait_request(struct ceph_osd_client *osdc,
 				  struct ceph_osd_request *req);
 extern void ceph_osdc_sync(struct ceph_osd_client *osdc);
 
+extern void ceph_osdc_flush_notifies(struct ceph_osd_client *osdc);
+
 extern int ceph_osdc_readpages(struct ceph_osd_client *osdc,
 			       struct ceph_vino vino,
 			       struct ceph_file_layout *layout,

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
@@ -2215,6 +2215,17 @@ void ceph_osdc_sync(struct ceph_osd_client *osdc)
 }
 EXPORT_SYMBOL(ceph_osdc_sync);
 
+/*
+ * Call all pending notify callbacks - for use after a watch is
+ * unregistered, to make sure no more callbacks for it will be invoked
+ */
+extern void ceph_osdc_flush_notifies(struct ceph_osd_client *osdc)
+{
+	flush_workqueue(osdc->notify_wq);
+}
+EXPORT_SYMBOL(ceph_osdc_flush_notifies);
+
+
 /*
  * init, shutdown
  */