ceph: reset requested max_size after mds reconnect

The max_size increase request to the MDS can get lost during an MDS
restart and reconnect.  Reset our requested value after the MDS recovers,
so that any blocked writes will re-request a larger max_size upon waking.

Also, explicit wake session caps after the reconnect.  Normally the cap
renewal catches this, but not in the cases where the caps didn't go stale
in the first place, which would leave writers waiting on max_size asleep.
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/mds_client.c

@@ -746,14 +746,24 @@ static void remove_session_caps(struct ceph_mds_session *session)
 static int wake_up_session_cb(struct inode *inode, struct ceph_cap *cap,
 			      void *arg)
 {
-	wake_up(&ceph_inode(inode)->i_cap_wq);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+
+	wake_up(&ci->i_cap_wq);
+	if (arg) {
+		spin_lock(&inode->i_lock);
+		ci->i_wanted_max_size = 0;
+		ci->i_requested_max_size = 0;
+		spin_unlock(&inode->i_lock);
+	}
 	return 0;
 }
 
-static void wake_up_session_caps(struct ceph_mds_session *session)
+static void wake_up_session_caps(struct ceph_mds_session *session,
+				 int reconnect)
 {
 	dout("wake_up_session_caps %p mds%d\n", session, session->s_mds);
-	iterate_session_caps(session, wake_up_session_cb, NULL);
+	iterate_session_caps(session, wake_up_session_cb,
+			     (void *)(unsigned long)reconnect);
 }
 
 /*
@@ -794,6 +804,8 @@ static int send_renew_caps(struct ceph_mds_client *mdsc,
 
 /*
  * Note new cap ttl, and any transition from stale -> not stale (fresh?).
+ *
+ * Called under session->s_mutex
  */
 static void renewed_caps(struct ceph_mds_client *mdsc,
 			 struct ceph_mds_session *session, int is_renew)
@@ -822,7 +834,7 @@ static void renewed_caps(struct ceph_mds_client *mdsc,
 	spin_unlock(&session->s_cap_lock);
 
 	if (wake)
-		wake_up_session_caps(session);
+		wake_up_session_caps(session, 0);
 }
 
 /*
@@ -2248,6 +2260,7 @@ static void check_new_map(struct ceph_mds_client *mdsc,
 			pr_info("mds%d reconnect completed\n", s->s_mds);
 			kick_requests(mdsc, i, 1);
 			ceph_kick_flushing_caps(mdsc, s);
+			wake_up_session_caps(s, 1);
 		}
 	}
 }