Commit 5cbdebe3 authored by Stefano Stabellini's avatar Stefano Stabellini Committed by Kevin Wolf
Browse files

qemu and qemu-xen: support empty write barriers in xen_disk 



This patch can be applied to both qemu-xen and qemu and adds support
for empty write barriers to xen_disk.

Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: default avatarGerd Hoffmann <kraxel@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 9fbef1ac

hw/xen_disk.c

+10 −2
Original line number Diff line number Diff line
@@ -181,6 +181,10 @@ static int ioreq_parse(struct ioreq *ioreq) 
	ioreq->prot = PROT_WRITE; /* to memory */

	break;

    case BLKIF_OP_WRITE_BARRIER:

        if (!ioreq->req.nr_segments) {

            ioreq->presync = 1;

            return 0;

        }

	if (!syncwrite)

	    ioreq->presync = ioreq->postsync = 1;

	/* fall through */
@@ -305,7 +309,7 @@ static int ioreq_runio_qemu_sync(struct ioreq *ioreq) 
    int i, rc, len = 0;

    off_t pos;



    if (ioreq_map(ioreq) == -1)

    if (ioreq->req.nr_segments && ioreq_map(ioreq) == -1)

	goto err;

    if (ioreq->presync)

	bdrv_flush(blkdev->bs);
@@ -329,6 +333,8 @@ static int ioreq_runio_qemu_sync(struct ioreq *ioreq) 
	break;

    case BLKIF_OP_WRITE:

    case BLKIF_OP_WRITE_BARRIER:

        if (!ioreq->req.nr_segments)

            break;

	pos = ioreq->start;

	for (i = 0; i < ioreq->v.niov; i++) {

	    rc = bdrv_write(blkdev->bs, pos / BLOCK_SIZE,
@@ -386,7 +392,7 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq) 
{

    struct XenBlkDev *blkdev = ioreq->blkdev;



    if (ioreq_map(ioreq) == -1)

    if (ioreq->req.nr_segments && ioreq_map(ioreq) == -1)

	goto err;



    ioreq->aio_inflight++;
@@ -403,6 +409,8 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq) 
    case BLKIF_OP_WRITE:

    case BLKIF_OP_WRITE_BARRIER:

        ioreq->aio_inflight++;

        if (!ioreq->req.nr_segments)

            break;

        bdrv_aio_writev(blkdev->bs, ioreq->start / BLOCK_SIZE,

                        &ioreq->v, ioreq->v.size / BLOCK_SIZE,

                        qemu_aio_complete, ioreq);