ceph: periodically trim stale dentries

Previous commit make VFS delete stale dentry when last reference is
dropped. Lease also can become invalid when corresponding dentry has
no reference. This patch make cephfs periodically scan lease list,
delete corresponding dentry if lease is invalid.

There are two types of lease, dentry lease and dir lease. dentry lease
has life time and applies to singe dentry. Dentry lease is added to tail
of a list when it's updated, leases at front of the list will expire
first. Dir lease is CEPH_CAP_FILE_SHARED on directory inode, it applies
to all dentries in the directory. Dentries have dir leases are added to
another list. Dentries in the list are periodically checked in a round
robin manner.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 34 insertions, 6 deletions

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 99d6e805668c..2095e5d038f8 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -58,6 +58,7 @@ struct ceph_reconnect_state {
 static void __wake_requests(struct ceph_mds_client *mdsc,
 			    struct list_head *head);
 static void ceph_cap_release_work(struct work_struct *work);
+static void ceph_cap_reclaim_work(struct work_struct *work);
 
 static const struct ceph_connection_operations mds_con_ops;
 
@@ -1943,6 +1944,27 @@ void __ceph_queue_cap_release(struct ceph_mds_session *session,
 		ceph_flush_cap_releases(session->s_mdsc, session);
 }
 
+static void ceph_cap_reclaim_work(struct work_struct *work)
+{
+	struct ceph_mds_client *mdsc =
+		container_of(work, struct ceph_mds_client, cap_reclaim_work);
+	int ret = ceph_trim_dentries(mdsc);
+	if (ret == -EAGAIN)
+		ceph_queue_cap_reclaim_work(mdsc);
+}
+
+void ceph_queue_cap_reclaim_work(struct ceph_mds_client *mdsc)
+{
+	if (mdsc->stopping)
+		return;
+
+        if (queue_work(mdsc->fsc->cap_wq, &mdsc->cap_reclaim_work)) {
+                dout("caps reclaim work queued\n");
+        } else {
+                dout("failed to queue caps release work\n");
+        }
+}
+
 /*
  * requests
  */
@@ -3957,9 +3979,6 @@ static void delayed_work(struct work_struct *work)
 	int renew_caps;
 
 	dout("mdsc delayed_work\n");
-	ceph_check_delayed_caps(mdsc);
-
-	ceph_trim_snapid_map(mdsc);
 
 	mutex_lock(&mdsc->mutex);
 	renew_interval = mdsc->mdsmap->m_session_timeout >> 2;
@@ -4007,6 +4026,12 @@ static void delayed_work(struct work_struct *work)
 	}
 	mutex_unlock(&mdsc->mutex);
 
+	ceph_check_delayed_caps(mdsc);
+
+	ceph_queue_cap_reclaim_work(mdsc);
+
+	ceph_trim_snapid_map(mdsc);
+
 	schedule_delayed(mdsc);
 }
 
@@ -4057,8 +4082,11 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc)
 	mdsc->num_cap_flushing = 0;
 	spin_lock_init(&mdsc->cap_dirty_lock);
 	init_waitqueue_head(&mdsc->cap_flushing_wq);
-	spin_lock_init(&mdsc->dentry_lru_lock);
-	INIT_LIST_HEAD(&mdsc->dentry_lru);
+	INIT_WORK(&mdsc->cap_reclaim_work, ceph_cap_reclaim_work);
+
+	spin_lock_init(&mdsc->dentry_list_lock);
+	INIT_LIST_HEAD(&mdsc->dentry_leases);
+	INIT_LIST_HEAD(&mdsc->dentry_dir_leases);
 
 	ceph_caps_init(mdsc);
 	ceph_adjust_min_caps(mdsc, fsc->min_caps);
@@ -4261,9 +4289,9 @@ void ceph_mdsc_close_sessions(struct ceph_mds_client *mdsc)
 	mutex_unlock(&mdsc->mutex);
 
 	ceph_cleanup_snapid_map(mdsc);
-
 	ceph_cleanup_empty_realms(mdsc);
 
+	cancel_work_sync(&mdsc->cap_reclaim_work);
 	cancel_delayed_work_sync(&mdsc->delayed_work); /* cancel timer */
 
 	dout("stopped\n");