libceph: make method call data be a separate data item

Right now the data for a method call is specified via a pointer and
length, and it's copied--along with the class and method name--into
a pagelist data item to be sent to the osd.  Instead, encode the
data in a data item separate from the class and method names.

This will allow large amounts of data to be supplied to methods
without copying.  Only rbd uses the class functionality right now,
and when it really needs this it will probably need to use a page
array rather than a page list.  But this simple implementation
demonstrates the functionality on the osd client, and that's enough
for now.

This resolves:
    http://tracker.ceph.com/issues/4104

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 6f7a52cf75c7..11b7987cb75f 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1847,8 +1847,19 @@ static int rbd_obj_method_sync(struct rbd_device *rbd_dev,
 		goto out;
 
 	osd_req_op_cls_init(obj_request->osd_req, 0, CEPH_OSD_OP_CALL,
-					class_name, method_name,
-					outbound, outbound_size);
+					class_name, method_name);
+	if (outbound_size) {
+		struct ceph_pagelist *pagelist;
+
+		pagelist = kmalloc(sizeof (*pagelist), GFP_NOFS);
+		if (!pagelist)
+			goto out;
+
+		ceph_pagelist_init(pagelist);
+		ceph_pagelist_append(pagelist, outbound, outbound_size);
+		osd_req_op_cls_request_data_pagelist(obj_request->osd_req, 0,
+						pagelist);
+	}
 	osd_req_op_cls_response_data_pages(obj_request->osd_req, 0,
 					obj_request->pages, inbound_size,
 					0, false, false);