From 06d395dde23c56cf05be0ef2687df87fdb9d1ece Mon Sep 17 00:00:00 2001 From: "John L. Hammond" Date: Mon, 25 Aug 2014 11:44:48 -0500 Subject: [PATCH] LU-5502 ofd: add a high level description of the OFD layer Add a high-level description of the OFD module to lustre/ofd/ofd_dev.c. Signed-off-by: John L. Hammond Change-Id: Id46a2d24ff2e2834e80e9d0f378ef2b515268bb3 Reviewed-on: http://review.whamcloud.com/11576 Tested-by: Jenkins Reviewed-by: Ned Bass Reviewed-by: Mike Pershin Reviewed-by: Andreas Dilger Tested-by: Maloo --- lustre/ofd/ofd_dev.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/lustre/ofd/ofd_dev.c b/lustre/ofd/ofd_dev.c index 2ca33bb..b854cc7 100644 --- a/lustre/ofd/ofd_dev.c +++ b/lustre/ofd/ofd_dev.c @@ -39,6 +39,33 @@ * Author: Mike Pershin * Author: Johann Lombardi */ +/* + * The OBD Filter Device (OFD) module belongs to the Object Storage + * Server stack and connects the RPC oriented Unified Target (TGT) + * layer (see lustre/include/lu_target.h) to the storage oriented OSD + * layer (see lustre/doc/osd-api.txt). + * + * TGT + * | DT and OBD APIs + * OFD + * | DT API + * OSD + * + * OFD implements the LU and OBD device APIs and is responsible for: + * + * - Handling client requests (create, destroy, bulk IO, setattr, + * get_info, set_info, statfs) for the objects belonging to the OST + * (together with TGT). + * + * - Providing grant space management which allows clients to reserve + * disk space for data writeback. OFD tracks grants on global and + * per client levels. + * + * - Handling object precreation requests from MDTs. + * + * - Operating the LDLM service that allows clients to maintain object + * data cache coherence. + */ #define DEBUG_SUBSYSTEM S_FILTER -- 1.8.3.1