virtio-blk: Use bdrv_aio_multiwrite
It is quite common for virtio-blk to submit more than one write request in a row to the qemu block layer. Use bdrv_aio_multiwrite to allow block drivers to optimize its handling of the requests. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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@ -252,15 +252,40 @@ static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
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}
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#endif /* __linux__ */
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static void virtio_blk_handle_write(VirtIOBlockReq *req)
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static void do_multiwrite(BlockDriverState *bs, BlockRequest *blkreq,
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int num_writes)
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{
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BlockDriverAIOCB *acb;
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int i, ret;
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ret = bdrv_aio_multiwrite(bs, blkreq, num_writes);
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acb = bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,
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req->qiov.size / 512, virtio_blk_rw_complete, req);
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if (!acb) {
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virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
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if (ret != 0) {
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for (i = 0; i < num_writes; i++) {
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if (blkreq[i].error) {
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virtio_blk_req_complete(blkreq[i].opaque, VIRTIO_BLK_S_IOERR);
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}
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}
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}
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}
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static void virtio_blk_handle_write(BlockRequest *blkreq, int *num_writes,
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VirtIOBlockReq *req, BlockDriverState **old_bs)
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{
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if (req->dev->bs != *old_bs || *num_writes == 32) {
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if (*old_bs != NULL) {
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do_multiwrite(*old_bs, blkreq, *num_writes);
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}
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*num_writes = 0;
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*old_bs = req->dev->bs;
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}
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blkreq[*num_writes].sector = req->out->sector;
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blkreq[*num_writes].nb_sectors = req->qiov.size / 512;
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blkreq[*num_writes].qiov = &req->qiov;
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blkreq[*num_writes].cb = virtio_blk_rw_complete;
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blkreq[*num_writes].opaque = req;
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blkreq[*num_writes].error = 0;
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(*num_writes)++;
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}
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static void virtio_blk_handle_read(VirtIOBlockReq *req)
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@ -278,6 +303,9 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
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{
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VirtIOBlock *s = to_virtio_blk(vdev);
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VirtIOBlockReq *req;
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BlockRequest blkreq[32];
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int num_writes = 0;
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BlockDriverState *old_bs = NULL;
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while ((req = virtio_blk_get_request(s))) {
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if (req->elem.out_num < 1 || req->elem.in_num < 1) {
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@ -299,13 +327,18 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
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} else if (req->out->type & VIRTIO_BLK_T_OUT) {
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qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
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req->elem.out_num - 1);
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virtio_blk_handle_write(req);
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virtio_blk_handle_write(blkreq, &num_writes, req, &old_bs);
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} else {
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qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
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req->elem.in_num - 1);
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virtio_blk_handle_read(req);
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}
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}
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if (num_writes > 0) {
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do_multiwrite(old_bs, blkreq, num_writes);
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}
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/*
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* FIXME: Want to check for completions before returning to guest mode,
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* so cached reads and writes are reported as quickly as possible. But
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@ -324,7 +357,8 @@ static void virtio_blk_dma_restart_bh(void *opaque)
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s->rq = NULL;
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while (req) {
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virtio_blk_handle_write(req);
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bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,
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req->qiov.size / 512, virtio_blk_rw_complete, req);
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req = req->next;
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}
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}
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