libceph: make ceph_con_revoke_message() a msg op

ceph_con_revoke_message() is passed both a message and a ceph
connection.  A ceph_msg allocated for incoming messages on a
connection always has a pointer to that connection, so there's no
need to provide the connection when revoking such a message.

Note that the existing logic does not preclude the message supplied
being a null/bogus message pointer.  The only user of this interface
is the OSD client, and the only value an osd client passes is a
request's r_reply field.  That is always non-null (except briefly in
an error path in ceph_osdc_alloc_request(), and that drops the
only reference so the request won't ever have a reply to revoke).
So we can safely assume the passed-in message is non-null, but add a
BUG_ON() to make it very obvious we are imposing this restriction.

Rename the function ceph_msg_revoke_incoming() to reflect that it is
really an operation on an incoming message.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

include/linux/ceph/messenger.h

@@ -241,8 +241,8 @@ extern void ceph_con_close(struct ceph_connection *con);
 extern void ceph_con_send(struct ceph_connection *con, struct ceph_msg *msg);
 
 extern void ceph_msg_revoke(struct ceph_msg *msg);
-extern void ceph_con_revoke_message(struct ceph_connection *con,
-				  struct ceph_msg *msg);
+extern void ceph_msg_revoke_incoming(struct ceph_msg *msg);
+
 extern void ceph_con_keepalive(struct ceph_connection *con);
 extern struct ceph_connection *ceph_con_get(struct ceph_connection *con);
 extern void ceph_con_put(struct ceph_connection *con);

net/ceph/messenger.c

@@ -2456,17 +2456,27 @@ void ceph_msg_revoke(struct ceph_msg *msg)
 /*
  * Revoke a message that we may be reading data into
  */
-void ceph_con_revoke_message(struct ceph_connection *con, struct ceph_msg *msg)
+void ceph_msg_revoke_incoming(struct ceph_msg *msg)
 {
+	struct ceph_connection *con;
+
+	BUG_ON(msg == NULL);
+	if (!msg->con) {
+		dout("%s msg %p null con\n", __func__, msg);
+
+		return;		/* Message not in our possession */
+	}
+
+	con = msg->con;
 	mutex_lock(&con->mutex);
-	if (con->in_msg && con->in_msg == msg) {
+	if (con->in_msg == msg) {
 		unsigned front_len = le32_to_cpu(con->in_hdr.front_len);
 		unsigned middle_len = le32_to_cpu(con->in_hdr.middle_len);
 		unsigned data_len = le32_to_cpu(con->in_hdr.data_len);
 
 		/* skip rest of message */
-		dout("con_revoke_pages %p msg %p revoked\n", con, msg);
-			con->in_base_pos = con->in_base_pos -
+		dout("%s %p msg %p revoked\n", __func__, con, msg);
+		con->in_base_pos = con->in_base_pos -
 				sizeof(struct ceph_msg_header) -
 				front_len -
 				middle_len -
@@ -2477,8 +2487,8 @@ void ceph_con_revoke_message(struct ceph_connection *con, struct ceph_msg *msg)
 		con->in_tag = CEPH_MSGR_TAG_READY;
 		con->in_seq++;
 	} else {
-		dout("con_revoke_pages %p msg %p pages %p no-op\n",
-		     con, con->in_msg, msg);
+		dout("%s %p in_msg %p msg %p no-op\n",
+		     __func__, con, con->in_msg, msg);
 	}
 	mutex_unlock(&con->mutex);
 }

net/ceph/osd_client.c

@@ -140,10 +140,9 @@ void ceph_osdc_release_request(struct kref *kref)
 	if (req->r_request)
 		ceph_msg_put(req->r_request);
 	if (req->r_con_filling_msg) {
-		dout("release_request revoking pages %p from con %p\n",
+		dout("%s revoking pages %p from con %p\n", __func__,
 		     req->r_pages, req->r_con_filling_msg);
-		ceph_con_revoke_message(req->r_con_filling_msg,
-				      req->r_reply);
+		ceph_msg_revoke_incoming(req->r_reply);
 		req->r_con_filling_msg->ops->put(req->r_con_filling_msg);
 	}
 	if (req->r_reply)
@@ -2022,9 +2021,9 @@ static struct ceph_msg *get_reply(struct ceph_connection *con,
 	}
 
 	if (req->r_con_filling_msg) {
-		dout("get_reply revoking msg %p from old con %p\n",
+		dout("%s revoking msg %p from old con %p\n", __func__,
 		     req->r_reply, req->r_con_filling_msg);
-		ceph_con_revoke_message(req->r_con_filling_msg, req->r_reply);
+		ceph_msg_revoke_incoming(req->r_reply);
 		req->r_con_filling_msg->ops->put(req->r_con_filling_msg);
 		req->r_con_filling_msg = NULL;
 	}