Jevon Qiao <scaleqiao@xxxxxxxxx> writes:
> The following patch is to fix alignment issue when host filesystem block
> size
> is larger than client msize.
>
> Thanks,
> Jevon
That is not the right format to send patch. You can send them as a
series using git-send-email.
>
> From: Jevon Qiao <scaleqiao@xxxxxxxxx>
> Date: Sun, 14 Feb 2016 15:11:08 +0800
> Subject: [PATCH] hw/9pfs: fix alignment issue when host filesystem block
> size
> is larger than client msize.
>
> Per the previous implementation, iounit will be assigned to be 0 after the
> first if statement as (s->msize - P9_IOHDRSZ)/stbuf.f_bsize will be zero
> when
> host filesystem block size is larger than msize. Finally, iounit will be
> equal
> to s->msize - P9_IOHDRSZ, which is usually not aligned.
>
> Signed-off-by: Jevon Qiao <scaleqiao@xxxxxxxxx>
> ---
> hw/9pfs/virtio-9p.c | 19 ++++++++++++++++---
> 1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
> index f972731..005d3a8 100644
> --- a/hw/9pfs/virtio-9p.c
> +++ b/hw/9pfs/virtio-9p.c
> @@ -1326,7 +1326,7 @@ out_nofid:
> static int32_t get_iounit(V9fsPDU *pdu, V9fsPath *path)
> {
> struct statfs stbuf;
> - int32_t iounit = 0;
> + int32_t iounit = 0, unit = 0;
> V9fsState *s = pdu->s;
>
> /*
> @@ -1334,8 +1334,21 @@ static int32_t get_iounit(V9fsPDU *pdu, V9fsPath
> *path)
> * and as well as less than (client msize - P9_IOHDRSZ))
> */
> if (!v9fs_co_statfs(pdu, path, &stbuf)) {
> - iounit = stbuf.f_bsize;
> - iounit *= (s->msize - P9_IOHDRSZ)/stbuf.f_bsize;
> + /*
> + * If host filesystem block size is larger than client msize,
> + * we will use PAGESIZE as the unit. The reason why we choose
> + * PAGESIZE is because the data will be splitted in terms of
> + * PAGESIZE in the virtio layer. In this case, the final
> + * iounit is equal to the value of ((msize/unit) - 1) * unit.
> + */
> + if (stbuf.f_bsize > s->msize) {
> + iounit = 4096;
> + unit = 4096;
What page size it should be guest or host ?. Also why 4096 ?. ppc64 use
64K page size.
> + } else {
> + iounit = stbuf.f_bsize;
> + unit = stbuf.f_bsize;
> + }
> + iounit *= (s->msize - P9_IOHDRSZ)/unit;
> }
> if (!iounit) {
> iounit = s->msize - P9_IOHDRSZ;
> --
-aneesh
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