[3.11.y.z extended stable] Patch "libceph: add function to ensure notifies are complete" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    libceph: add function to ensure notifies are complete

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 466355e9190f3004de258cc07ad216f00bc45caa Mon Sep 17 00:00:00 2001
From: Josh Durgin <josh.durgin at inktank.com>
Date: Wed, 28 Aug 2013 21:43:09 -0700
Subject: libceph: add function to ensure notifies are complete

commit dd935f44a40f8fb02aff2cc0df2269c92422df1c upstream.

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 <josh.durgin at inktank.com>
Reviewed-by: Sage Weil <sage at inktank.com>
Reviewed-by: Alex Elder <elder at linaro.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 include/linux/ceph/osd_client.h |  2 ++
 net/ceph/osd_client.c           | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index ce6df39..8f47625 100644
--- 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
index 0c49ec4..1ee21cd 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -2209,6 +2209,17 @@ 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
  */
 int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
--
1.8.3.2