Re: [Qemu-devel] [PATCH v3 2/3] 9pfs: use V9fsBlob to transmit xattr

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Wei Liu <wei.liu2@citrix.com> writes:

> And make v9fs_pack static function. Now we only need to export
> v9fs_{,un}marshal to device.
>
> Signed-off-by: Wei Liu <wei.liu2@citrix.com>
> ---
> v3: fix bug discovered by Aneesh
> ---
>  fsdev/9p-iov-marshal.c |  4 ++--
>  fsdev/9p-iov-marshal.h |  3 ---
>  hw/9pfs/9p.c           | 21 +++++++++++++--------
>  3 files changed, 15 insertions(+), 13 deletions(-)
>
> diff --git a/fsdev/9p-iov-marshal.c b/fsdev/9p-iov-marshal.c
> index 1f9edf3..5c911c8 100644
> --- a/fsdev/9p-iov-marshal.c
> +++ b/fsdev/9p-iov-marshal.c
> @@ -70,8 +70,8 @@ static ssize_t v9fs_unpack(void *dst, struct iovec *out_sg, int out_num,
>      return v9fs_packunpack(dst, out_sg, out_num, offset, size, 0);
>  }
>
> -ssize_t v9fs_pack(struct iovec *in_sg, int in_num, size_t offset,
> -                  const void *src, size_t size)
> +static ssize_t v9fs_pack(struct iovec *in_sg, int in_num, size_t offset,
> +                         const void *src, size_t size)
>  {
>      return v9fs_packunpack((void *)src, in_sg, in_num, offset, size, 1);
>  }
> diff --git a/fsdev/9p-iov-marshal.h b/fsdev/9p-iov-marshal.h
> index 6bccbfb..410a1ea 100644
> --- a/fsdev/9p-iov-marshal.h
> +++ b/fsdev/9p-iov-marshal.h
> @@ -3,9 +3,6 @@
>
>  #include "9p-marshal.h"
>
> -
> -ssize_t v9fs_pack(struct iovec *in_sg, int in_num, size_t offset,
> -                  const void *src, size_t size);
>  ssize_t v9fs_iov_unmarshal(struct iovec *out_sg, int out_num, size_t offset,
>                             int bswap, const char *fmt, ...);
>  ssize_t v9fs_iov_marshal(struct iovec *in_sg, int in_num, size_t offset,
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> index a904403..84cb1d9 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -1585,6 +1585,7 @@ static int v9fs_xattr_read(V9fsState *s, V9fsPDU *pdu, V9fsFidState *fidp,
>      size_t offset = 7;
>      int read_count;
>      int64_t xattr_len;
> +    V9fsBlob blob;
>
>      xattr_len = fidp->fs.xattr.len;
>      read_count = xattr_len - off;
> @@ -1596,14 +1597,18 @@ static int v9fs_xattr_read(V9fsState *s, V9fsPDU *pdu, V9fsFidState *fidp,
>           */
>          read_count = 0;
>      }
> -    err = pdu_marshal(pdu, offset, "d", read_count);
> -    if (err < 0) {
> -        return err;
> -    }
> -    offset += err;
> -    err = v9fs_pack(pdu->elem.in_sg, pdu->elem.in_num, offset,
> -                    ((char *)fidp->fs.xattr.value) + off,
> -                    read_count);
> +
> +    v9fs_blob_init(&blob);
> +
> +    blob.data = g_malloc(read_count);
> +    memcpy(blob.data, ((char *)fidp->fs.xattr.value) + off,
> +           read_count);

Can we do this without the malloc and memcpy ? . I am sure you need this
for Xen abstraction. But for now i am inclined to drop this from the
series and add this later with Xen transport.  v9fs_xattr_read is
essentially T_READ on a xattr fid and we don't use blob ("B") in other
code path. We also want to avoid that extra malloc and memcpy.



> +    blob.size = read_count;
> +
> +    err = pdu_marshal(pdu, offset, "B", &blob);
> +
> +    v9fs_blob_free(&blob);
> +
>      if (err < 0) {
>          return err;
>      }
> -- 
> 2.1.4

-aneesh