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>
diff --git a/fs/ceph/msgpool.h b/fs/ceph/msgpool.h
index 07a2dec..bc834bf 100644
--- a/fs/ceph/msgpool.h
+++ b/fs/ceph/msgpool.h
@@ -20,7 +20,8 @@
 			     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