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Commit be2f8373 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge
Browse files

xen/blkfront: Implement FUA with BLKIF_OP_WRITE_BARRIER



The BLKIF_OP_WRITE_BARRIER is a full ordered barrier, so we can use it
to implement FUA as well as a plain FLUSH.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: default avatarChristoph Hellwig <hch@lst.de>
parent a945b980
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+12 −2
Original line number Diff line number Diff line
@@ -286,8 +286,18 @@ static int blkif_queue_request(struct request *req)

	ring_req->operation = rq_data_dir(req) ?
		BLKIF_OP_WRITE : BLKIF_OP_READ;
	if (req->cmd_flags & REQ_FLUSH)

	if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
		/*
		 * Ideally we could just do an unordered
		 * flush-to-disk, but all we have is a full write
		 * barrier at the moment.  However, a barrier write is
		 * a superset of FUA, so we can implement it the same
		 * way.  (It's also a FLUSH+FUA, since it is
		 * guaranteed ordered WRT previous writes.)
		 */
		ring_req->operation = BLKIF_OP_WRITE_BARRIER;
	}

	ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
	BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
@@ -1065,7 +1075,7 @@ static void blkfront_connect(struct blkfront_info *info)
	info->feature_flush = 0;

	if (!err && barrier)
		info->feature_flush = REQ_FLUSH;
		info->feature_flush = REQ_FLUSH | REQ_FUA;

	err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
	if (err) {