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

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

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'

-aneesh