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Commit c64e38ea authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge
Browse files

xen/blkfront: map REQ_FLUSH into a full barrier 



Implement a flush as a full barrier, since we have nothing weaker.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: default avatarChristoph Hellwig <hch@lst.de>
parent c8ddb271

drivers/block/xen-blkfront.c

+5 −14
Original line number Diff line number Diff line
@@ -245,14 +245,11 @@ static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 
}



/*

 * blkif_queue_request

 * Generate a Xen blkfront IO request from a blk layer request.  Reads

 * and writes are handled as expected.  Since we lack a loose flush

 * request, we map flushes into a full ordered barrier.

 *

 * request block io

 *

 * id: for guest use only.

 * operation: BLKIF_OP_{READ,WRITE,PROBE}

 * buffer: buffer to read/write into. this should be a

 *   virtual address in the guest os.

 * @req: a request struct

 */

static int blkif_queue_request(struct request *req)

{
@@ -289,7 +286,7 @@ 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_HARDBARRIER)

	if (req->cmd_flags & REQ_FLUSH)

		ring_req->operation = BLKIF_OP_WRITE_BARRIER;



	ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
@@ -1069,14 +1066,8 @@ static void blkfront_connect(struct blkfront_info *info) 
	 */

	info->feature_flush = 0;



	/*

	 * The driver doesn't properly handled empty flushes, so

	 * lets disable barrier support for now.

	 */

#if 0

	if (!err && barrier)

		info->feature_flush = REQ_FLUSH;

#endif



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

	if (err) {