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

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

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefano Stabellini 2010-11-24 13:08:03 +00:00 committed by Kevin Wolf
parent 9fbef1ac7c
commit 5cbdebe39e
1 changed files with 10 additions and 2 deletions
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12
hw/xen_disk.c
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@ -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);