Messages in this thread | | | From | Jeremy Fitzhardinge <> | Subject | [PATCH 0/4] FLUSH/FUA updates for Xen blkfront | Date | Tue, 2 Nov 2010 12:20:43 -0400 |
| |
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Update the Xen blockfront driver to deal with the block layer's cache flush and FUA operations.
The only primitive we have for implementing these is BLKIF_OP_WRITE_BARRIER, which is a fully ordered write operation. This is much stronger than a simple cache flush which Linux requires, but it will do the job.
It can also implement FUA, since it will guarantee that the data is written to stable storage when it completes - however it also implements full ordering, which makes it equivalent to a FLUSH+FUA.
Unfortunately it appears that the actual Xen backend implementation will fail an empty BLKIF_OP_WRITE_BARRIER operation. If that happens, disable use of WRITE_BARRIER. (Daniel, I don't know if this is deliberate or not; I couldn't see where the error was coming from).
Jeremy Fitzhardinge (4): xen/blkfront: map REQ_FLUSH into a full barrier xen/blkfront: change blk_shadow.request to proper pointer xen/blkfront: Implement FUA with BLKIF_OP_WRITE_BARRIER xen/blkfront: cope with backend that fail empty BLKIF_OP_WRITE_BARRIER requests
drivers/block/xen-blkfront.c | 53 +++++++++++++++++++++++------------------ 1 files changed, 30 insertions(+), 23 deletions(-)
-- 1.7.2.3
| |