ceph: support ceph_pagelist for message payload

The ceph_pagelist is a simple list of whole pages, strung together via
their lru list_head.  It facilitates encoding to a "buffer" of unknown
size.  Allow its use in place of the ceph_msg page vector.

This will be used to fix the huge buffer preallocation woes of MDS
reconnection.

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/ceph/messenger.h b/fs/ceph/messenger.h
index 7e2aab1d3ce2..a7b684145092 100644
--- a/fs/ceph/messenger.h
+++ b/fs/ceph/messenger.h
@@ -85,6 +85,7 @@ struct ceph_msg {
         struct ceph_buffer *middle;
         struct page **pages;            /* data payload.  NOT OWNER. */
         unsigned nr_pages;              /* size of page array */
+        struct ceph_pagelist *pagelist; /* instead of pages */
         struct list_head list_head;
         struct kref kref;
         bool front_is_vmalloc;