From: Asias He <asias@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org,
Wanlong Gao <gaowanlong@cn.fujitsu.com>,
mst@redhat.com, Rusty Russell <rusty@rustcorp.com.au>,
kvm@vger.kernel.org, virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 3/9] virtio-blk: use virtqueue_start_buf on bio path
Date: Sun, 17 Feb 2013 14:39:48 +0800 [thread overview]
Message-ID: <51207B34.3050405@redhat.com> (raw)
In-Reply-To: <1360671815-2135-4-git-send-email-pbonzini@redhat.com>
On 02/12/2013 08:23 PM, Paolo Bonzini wrote:
> 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 <pbonzini@redhat.com>
Reviewed-by: Asias He <asias@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)
>
--
Asias
next prev parent reply other threads:[~2013-02-17 6:40 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-12 12:23 [PATCH 0/9] virtio: new API for addition of buffers, scatterlist changes Paolo Bonzini
2013-02-12 12:23 ` [PATCH 1/9] virtio: add functions for piecewise addition of buffers Paolo Bonzini
2013-02-12 14:56 ` Michael S. Tsirkin
2013-02-12 15:32 ` Paolo Bonzini
2013-02-12 15:43 ` Michael S. Tsirkin
2013-02-12 15:48 ` Paolo Bonzini
2013-02-12 16:13 ` Michael S. Tsirkin
2013-02-12 16:17 ` Paolo Bonzini
2013-02-12 16:35 ` Michael S. Tsirkin
2013-02-12 16:57 ` Paolo Bonzini
2013-02-12 17:34 ` Michael S. Tsirkin
2013-02-12 18:04 ` Paolo Bonzini
2013-02-12 18:23 ` Michael S. Tsirkin
2013-02-12 20:08 ` Paolo Bonzini
2013-02-12 20:49 ` Michael S. Tsirkin
2013-02-13 8:06 ` Paolo Bonzini
2013-02-13 10:33 ` Michael S. Tsirkin
2013-02-12 18:03 ` [PATCH v2 " Paolo Bonzini
2013-02-12 12:23 ` [PATCH 2/9] virtio-blk: reorganize virtblk_add_req Paolo Bonzini
2013-02-17 6:38 ` Asias He
2013-02-12 12:23 ` [PATCH 3/9] virtio-blk: use virtqueue_start_buf on bio path Paolo Bonzini
2013-02-17 6:39 ` Asias He [this message]
2013-02-12 12:23 ` [PATCH 4/9] virtio-blk: use virtqueue_start_buf on req path Paolo Bonzini
2013-02-17 6:37 ` Asias He
2013-02-18 9:05 ` Paolo Bonzini
2013-02-12 12:23 ` [PATCH 5/9] scatterlist: introduce sg_unmark_end Paolo Bonzini
2013-02-12 12:23 ` [PATCH 6/9] virtio-net: unmark scatterlist ending after virtqueue_add_buf Paolo Bonzini
2013-02-12 12:23 ` [PATCH 7/9] virtio-scsi: use virtqueue_start_buf Paolo Bonzini
2013-02-12 12:23 ` [PATCH 8/9] virtio: introduce and use virtqueue_add_buf_single Paolo Bonzini
2013-02-12 12:23 ` [PATCH 9/9] virtio: reimplement virtqueue_add_buf using new functions Paolo Bonzini
2013-02-14 6:00 ` [PATCH 0/9] virtio: new API for addition of buffers, scatterlist changes Rusty Russell
2013-02-14 9:23 ` Paolo Bonzini
2013-02-15 18:04 ` Paolo Bonzini
2013-02-19 7:49 ` Rusty Russell
2013-02-19 9:11 ` Paolo Bonzini
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