ceph: optimize cap flush waiting

Add a 'wake' flag to ceph_cap_flush struct, which indicates if there
is someone waiting for it to finish. When getting flush ack message,
we check the 'wake' flag in corresponding ceph_cap_flush struct to
decide if we should wake up waiters. One corner case is that the
acked cap flush has 'wake' flags is set, but it is not the first one
on the flushing list. We do not wake up waiters in this case, set
'wake' flags of preceding ceph_cap_flush struct instead

Signed-off-by: Yan, Zheng <zyan@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index fa9036a..cdc6a17 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1212,6 +1212,8 @@ static void remove_session_caps(struct ceph_mds_session *session)
 	dout("remove_session_caps on %p\n", session);
 	iterate_session_caps(session, remove_session_caps_cb, fsc);
 
+	wake_up_all(&fsc->mdsc->cap_flushing_wq);
+
 	spin_lock(&session->s_cap_lock);
 	if (session->s_nr_caps > 0) {
 		struct inode *inode;
@@ -3536,6 +3538,12 @@ void ceph_mdsc_sync(struct ceph_mds_client *mdsc)
 	ceph_flush_dirty_caps(mdsc);
 	spin_lock(&mdsc->cap_dirty_lock);
 	want_flush = mdsc->last_cap_flush_tid;
+	if (!list_empty(&mdsc->cap_flush_list)) {
+		struct ceph_cap_flush *cf =
+			list_last_entry(&mdsc->cap_flush_list,
+					struct ceph_cap_flush, g_list);
+		cf->wake = true;
+	}
 	spin_unlock(&mdsc->cap_dirty_lock);
 
 	dout("sync want tid %lld flush_seq %lld\n",