Is there any particular reason p9_fcall to have pointers to pages
instead of a scatterlist?
Thanks,
Lucho
On Tue, Aug 17, 2010 at 11:27 AM, Venkateswararao Jujjuri (JV)
<jvrao@xxxxxxxxxxxxxxxxxx> wrote:
> This patch adds necessary infrastructure for placing page addresses
> directly on the sg list for the server to consume.
>
> The newly added routine pack_sg_list_p() is just like pack_sg_list()
> except that it takes page array as an input and directly places them on
> the sg list after taking care of the first page offset.
>
> Signed-off-by: Venkateswararao Jujjuri <jvrao@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Badari Pulavarty <pbadari@xxxxxxxxxx>
> ---
> include/net/9p/9p.h | 6 ++++-
> net/9p/client.c | 4 +++
> net/9p/trans_virtio.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++--
> 3 files changed, 65 insertions(+), 4 deletions(-)
>
> diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h
> index a8de812..382ef22 100644
> --- a/include/net/9p/9p.h
> +++ b/include/net/9p/9p.h
> @@ -651,7 +651,11 @@ struct p9_fcall {
>
> size_t offset;
> size_t capacity;
> -
> + struct page **pdata;
> + uint32_t pdata_mapped_pages;
> + uint32_t pdata_off;
> + uint32_t pdata_write_len;
> + uint32_t pdata_read_len;
> uint8_t *sdata;
> };
>
> diff --git a/net/9p/client.c b/net/9p/client.c
> index 29bbbbd..5487896 100644
> --- a/net/9p/client.c
> +++ b/net/9p/client.c
> @@ -244,8 +244,12 @@ static struct p9_req_t *p9_tag_alloc(struct p9_client *c, u16 tag)
> }
> req->tc->sdata = (char *) req->tc + sizeof(struct p9_fcall);
> req->tc->capacity = c->msize;
> + req->tc->pdata_write_len = 0;
> + req->tc->pdata_read_len = 0;
> req->rc->sdata = (char *) req->rc + sizeof(struct p9_fcall);
> req->rc->capacity = c->msize;
> + req->rc->pdata_write_len = 0;
> + req->rc->pdata_read_len = 0;
> }
>
> p9pdu_reset(req->tc);
> diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
> index 762c19f..8f86cb5 100644
> --- a/net/9p/trans_virtio.c
> +++ b/net/9p/trans_virtio.c
> @@ -180,6 +180,44 @@ pack_sg_list(struct scatterlist *sg, int start, int limit, char *data,
> return index-start;
> }
>
> +/**
> + * pack_sg_list_p - Pack a scatter gather list from an array of pages.
> + * @sg: scatter/gather list to pack into
> + * @start: which segment of the sg_list to start at
> + * @limit: maximum segment to pack data to
> + * @pdu: pdu prepared to put on the wire.
> + * @count: amount of data to pack into the scatter/gather list
> + *
> + * This is just like pack_sg_list() except that it takes page array
> + * as an input and directly places them on the sg list after taking
> + * care of the first page offset.
> + */
> +
> +static int
> +pack_sg_list_p(struct scatterlist *sg, int start, int limit,
> + struct p9_fcall *pdu, int count)
> +{
> + int s;
> + int i = 0;
> + int index = start;
> +
> + if (pdu->pdata_off) {
> + s = min((int)(PAGE_SIZE - pdu->pdata_off), count);
> + sg_set_page(&sg[index++], pdu->pdata[i++], s, pdu->pdata_off);
> + count -= s;
> + }
> +
> + while (count) {
> + BUG_ON(index > limit);
> + s = min((int)PAGE_SIZE, count);
> + sg_set_page(&sg[index++], pdu->pdata[i++], s, 0);
> + count -= s;
> + }
> +
> + return index-start;
> +}
> +
> +
> /* We don't currently allow canceling of virtio requests */
> static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
> {
> @@ -196,16 +234,31 @@ static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
> static int
> p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
> {
> - int in, out;
> + int in, out, outp, inp;
> struct virtio_chan *chan = client->trans;
> char *rdata = (char *)req->rc+sizeof(struct p9_fcall);
>
> P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");
>
> out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata,
> - req->tc->size);
> - in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata,
> + req->tc->size);
> +
> + BUG_ON(req->tc->pdata_write_len && req->tc->pdata_read_len);
> +
> + if (req->tc->pdata_write_len) {
> + outp = pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
> + req->tc, req->tc->pdata_write_len);
> + out += outp;
> + }
> + if (req->tc->pdata_read_len) {
> + inp = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, rdata, 11);
> + in = pack_sg_list_p(chan->sg, out+inp, VIRTQUEUE_NUM,
> + req->tc, req->tc->pdata_read_len);
> + in += inp;
> + } else {
> + in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, rdata,
> client->msize);
> + }
>
> req->status = REQ_STATUS_SENT;
>
> --
> 1.6.5.2
>
>
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