Re: [Qemu-devel] [PATCH v2 12/27] 9pfs: use V9fsBlob to transmit xattr

[Wei Liu <wei.liu2@citrix.com>]

On Sat, Jan 09, 2016 at 12:18:40AM +0530, Aneesh Kumar K.V wrote:
> Wei Liu <wei.liu2@citrix.com> writes:
> 
> > On Fri, Jan 08, 2016 at 02:00:31PM +0530, Aneesh Kumar K.V wrote:
> >> 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>
> >> > ---
> >> >  fsdev/virtio-9p-marshal.c |  4 ++--
> >> >  fsdev/virtio-9p-marshal.h |  3 ---
> >> >  hw/9pfs/virtio-9p.c       | 21 +++++++++++++--------
> >> >  3 files changed, 15 insertions(+), 13 deletions(-)
> >> >
> >> > diff --git a/fsdev/virtio-9p-marshal.c b/fsdev/virtio-9p-marshal.c
> >> > index c3ac316..d120bd2 100644
> >> > --- a/fsdev/virtio-9p-marshal.c
> >> > +++ b/fsdev/virtio-9p-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/virtio-9p-marshal.h b/fsdev/virtio-9p-marshal.h
> >> > index 0709bcd..766a48e 100644
> >> > --- a/fsdev/virtio-9p-marshal.h
> >> > +++ b/fsdev/virtio-9p-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_unmarshal(struct iovec *out_sg, int out_num, size_t offset,
> >> >                         int bswap, const char *fmt, ...);
> >> >  ssize_t v9fs_marshal(struct iovec *in_sg, int in_num, size_t offset,
> >> > diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
> >> > index 30ff828..654c103 100644
> >> > --- a/hw/9pfs/virtio-9p.c
> >> > +++ b/hw/9pfs/virtio-9p.c
> >> > @@ -1561,6 +1561,7 @@ 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;
> >> > @@ -1572,14 +1573,18 @@ 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);
> >> > +    blob.size = read_count;
> >> > +
> >> > +    err = pdu_marshal(pdu, offset, "dB", read_count, &blob);
> >> 
> >> Is this correct ?
> >> 
> >> earlier we had read_count <data>
> >> now we have
> >> read_count, <blob> which is read_count, blob->size, data
> >> 
> >
> > Yes, you're right. There is an error.
> >
> > The new code should be
> >
> >     err = pdu_marshal(pdu, offset, "B", &blob);
> >
> > Thanks for your careful review.
> >
> 
> We would then need 'B' to encode size as int ie, 'd' instead of 'w'
> 

Ack. I will make the change.

Wei.

> -aneesh
> 
>