diff options
| -rw-r--r-- | hw/xen_disk.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/hw/xen_disk.c b/hw/xen_disk.c index 134ac3388e..85a1c85524 100644 --- a/hw/xen_disk.c +++ b/hw/xen_disk.c @@ -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); |