ceph: warn on allocation from msgpool with larger front_len

Pass the front_len we need when pulling a message off a msgpool,
and WARN if it is greater than the pool's size.  Then try to
allocate a new message (to continue without failing).
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/mon_client.c

@@ -639,14 +639,15 @@ static struct ceph_msg *mon_alloc_msg(struct ceph_connection *con,
 {
 	struct ceph_mon_client *monc = con->private;
 	int type = le16_to_cpu(hdr->type);
+	int front = le32_to_cpu(hdr->front_len);
 
 	switch (type) {
 	case CEPH_MSG_CLIENT_MOUNT_ACK:
-		return ceph_msgpool_get(&monc->msgpool_mount_ack);
+		return ceph_msgpool_get(&monc->msgpool_mount_ack, front);
 	case CEPH_MSG_MON_SUBSCRIBE_ACK:
-		return ceph_msgpool_get(&monc->msgpool_subscribe_ack);
+		return ceph_msgpool_get(&monc->msgpool_subscribe_ack, front);
 	case CEPH_MSG_STATFS_REPLY:
-		return ceph_msgpool_get(&monc->msgpool_statfs_reply);
+		return ceph_msgpool_get(&monc->msgpool_statfs_reply, front);
 	}
 	return ceph_alloc_msg(con, hdr);
 }

fs/ceph/msgpool.c

@@ -101,14 +101,28 @@ int ceph_msgpool_resv(struct ceph_msgpool *pool, int delta)
 	return ret;
 }
 
-struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *pool)
+struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *pool, int front_len)
 {
 	wait_queue_t wait;
 	struct ceph_msg *msg;
 
+	if (front_len && front_len > pool->front_len) {
+		pr_err("msgpool_get pool %p need front %d, pool size is %d\n",
+		       pool, front_len, pool->front_len);
+		WARN_ON(1);
+
+		/* try to alloc a fresh message */
+		msg = ceph_msg_new(0, front_len, 0, 0, NULL);
+		if (!IS_ERR(msg))
+			return msg;
+	}
+
+	if (!front_len)
+		front_len = pool->front_len;
+
 	if (pool->blocking) {
 		/* mempool_t behavior; first try to alloc */
-		msg = ceph_msg_new(0, pool->front_len, 0, 0, NULL);
+		msg = ceph_msg_new(0, front_len, 0, 0, NULL);
 		if (!IS_ERR(msg))
 			return msg;
 	}
@@ -133,7 +147,7 @@ struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *pool)
 			WARN_ON(1);
 
 			/* maybe we can allocate it now? */
-			msg = ceph_msg_new(0, pool->front_len, 0, 0, NULL);
+			msg = ceph_msg_new(0, front_len, 0, 0, NULL);
 			if (!IS_ERR(msg))
 				return msg;
 

fs/ceph/msgpool.h

@@ -20,7 +20,8 @@ extern int ceph_msgpool_init(struct ceph_msgpool *pool,
 			     int front_len, int size, bool blocking);
 extern void ceph_msgpool_destroy(struct ceph_msgpool *pool);
 extern int ceph_msgpool_resv(struct ceph_msgpool *, int delta);
-extern struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *);
+extern struct ceph_msg *ceph_msgpool_get(struct ceph_msgpool *,
+					 int front_len);
 extern void ceph_msgpool_put(struct ceph_msgpool *, struct ceph_msg *);
 
 #endif

fs/ceph/osd_client.c

@@ -161,7 +161,7 @@ struct ceph_osd_request *ceph_osdc_new_request(struct ceph_osd_client *osdc,
 	if (snapc)
 		msg_size += sizeof(u64) * snapc->num_snaps;
 	if (use_mempool)
-		msg = ceph_msgpool_get(&osdc->msgpool_op);
+		msg = ceph_msgpool_get(&osdc->msgpool_op, 0);
 	else
 		msg = ceph_msg_new(CEPH_MSG_OSD_OP, msg_size, 0, 0, NULL);
 	if (IS_ERR(msg)) {
@@ -1271,10 +1271,11 @@ static struct ceph_msg *alloc_msg(struct ceph_connection *con,
 	struct ceph_osd *osd = con->private;
 	struct ceph_osd_client *osdc = osd->o_osdc;
 	int type = le16_to_cpu(hdr->type);
+	int front = le32_to_cpu(hdr->front_len);
 
 	switch (type) {
 	case CEPH_MSG_OSD_OPREPLY:
-		return ceph_msgpool_get(&osdc->msgpool_op_reply);
+		return ceph_msgpool_get(&osdc->msgpool_op_reply, front);
 	}
 	return ceph_alloc_msg(con, hdr);
 }