Move the creation of the request header and response footer to __virtblk_add_req. vbr->sg only contains the data scatterlist, the header/footer are added separately using the new piecewise API for building virtqueue buffers.
With this change, virtio-blk (with use_bio) is not relying anymore on the virtio functions ignoring the end markers in a scatterlist. The next patch will do the same for the other path. Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> --- drivers/block/virtio_blk.c | 74 ++++++++++++++++++++++++++----------------- 1 files changed, 45 insertions(+), 29 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index fd8a689..4a31fcc 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -62,6 +62,7 @@ struct virtblk_req struct virtio_blk *vblk; int flags; u8 status; + int nents; struct scatterlist sg[]; }; @@ -100,24 +101,52 @@ static inline struct virtblk_req *virtblk_alloc_req(struct virtio_blk *vblk, return vbr; } -static inline int __virtblk_add_req(struct virtqueue *vq, - struct virtblk_req *vbr, - unsigned long out, - unsigned long in) +static int __virtblk_add_req(struct virtqueue *vq, + struct virtblk_req *vbr) { - return virtqueue_add_buf(vq, vbr->sg, out, in, vbr, GFP_ATOMIC); + struct scatterlist sg; + enum dma_data_direction dir; + int ret; + + unsigned int nents = 2; + unsigned int nsg = 2; + + if (vbr->nents) { + nsg++; + nents += vbr->nents; + } + + ret = virtqueue_start_buf(vq, vbr, nents, nsg, GFP_ATOMIC); + if (ret < 0) + return ret; + + dir = DMA_TO_DEVICE; + sg_init_one(&sg, &vbr->out_hdr, sizeof(vbr->out_hdr)); + virtqueue_add_sg(vq, &sg, 1, dir); + + if (vbr->nents) { + if ((vbr->out_hdr.type & VIRTIO_BLK_T_OUT) == 0) + dir = DMA_FROM_DEVICE; + + virtqueue_add_sg(vq, vbr->sg, vbr->nents, dir); + } + + dir = DMA_FROM_DEVICE; + sg_init_one(&sg, &vbr->status, sizeof(vbr->status)); + virtqueue_add_sg(vq, &sg, 1, dir); + + virtqueue_end_buf(vq); + return 0; } -static void virtblk_add_req(struct virtblk_req *vbr, - unsigned int out, unsigned int in) +static void virtblk_add_req(struct virtblk_req *vbr) { struct virtio_blk *vblk = vbr->vblk; DEFINE_WAIT(wait); int ret; spin_lock_irq(vblk->disk->queue->queue_lock); - while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr, - out, in)) < 0)) { + while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr)) < 0)) { prepare_to_wait_exclusive(&vblk->queue_wait, &wait, TASK_UNINTERRUPTIBLE); @@ -134,22 +163,18 @@ static void virtblk_add_req(struct virtblk_req *vbr, static void virtblk_bio_send_flush(struct virtblk_req *vbr) { - unsigned int out = 0, in = 0; - vbr->flags |= VBLK_IS_FLUSH; vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH; vbr->out_hdr.sector = 0; vbr->out_hdr.ioprio = 0; - sg_set_buf(&vbr->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr)); - sg_set_buf(&vbr->sg[out + in++], &vbr->status, sizeof(vbr->status)); + vbr->nents = 0; - virtblk_add_req(vbr, out, in); + virtblk_add_req(vbr); } static void virtblk_bio_send_data(struct virtblk_req *vbr) { struct virtio_blk *vblk = vbr->vblk; - unsigned int num, out = 0, in = 0; struct bio *bio = vbr->bio; vbr->flags &= ~VBLK_IS_FLUSH; @@ -157,24 +182,15 @@ static void virtblk_bio_send_data(struct virtblk_req *vbr) vbr->out_hdr.sector = bio->bi_sector; vbr->out_hdr.ioprio = bio_prio(bio); - sg_set_buf(&vbr->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr)); - - num = blk_bio_map_sg(vblk->disk->queue, bio, vbr->sg + out); - - sg_set_buf(&vbr->sg[num + out + in++], &vbr->status, - sizeof(vbr->status)); - - if (num) { - if (bio->bi_rw & REQ_WRITE) { + vbr->nents = blk_bio_map_sg(vblk->disk->queue, bio, vbr->sg); + if (vbr->nents) { + if (bio->bi_rw & REQ_WRITE) vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; - out += num; - } else { + else vbr->out_hdr.type |= VIRTIO_BLK_T_IN; - in += num; - } } - virtblk_add_req(vbr, out, in); + virtblk_add_req(vbr); } static void virtblk_bio_send_data_work(struct work_struct *work) -- 1.7.1 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization