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 7e2aab1d3ce..a7b68414509 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;