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>

2 files changed, 20 insertions, 11 deletions

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index d636903ad4b..3857f815c03 100644
--- a/net/ceph/messenger.c
+++ b/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);
 }
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index ad78705a4af..c178c770acb 100644
--- a/net/ceph/osd_client.c
+++ b/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;
         }