Re: [Xen-devel] [PATCH 04 of 16 RFC] blktap3: change libxl__blktap_devpath prototype to return an error code

[Thanos Makatos <thanos.makatos@xxxxxxxxxx>]

> -----Original Message-----
> From: Ian Campbell
> Sent: 26 October 2012 12:22
> To: Thanos Makatos
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] [PATCH 04 of 16 RFC] blktap3: change
> libxl__blktap_devpath prototype to return an error code
> 
> On Wed, 2012-10-24 at 18:02 +0100, Thanos Makatos wrote:
> > Make libxl__blktap_devpath return an error code instead of the
> device,
> > since there is no device in dom0 any more.
> 
> Does this function eventually go away then? Or will it eventually
> return some sort of metadata which can be used to connect to the
> created tap device?

As in blktap2, it creates the tapdisk process, but doesn't return any metadata, 
so it's still required. I guess changing the name of the function would clarify 
it.

> 
> >  Amend the libxl code that uses this functions accordingly.
> >
> > diff -r 80e0bc67dcda -r bcb5a6182868 tools/libxl/libxl.c
> > --- a/tools/libxl/libxl.c   Wed Oct 24 17:24:53 2012 +0100
> > +++ b/tools/libxl/libxl.c   Wed Oct 24 17:25:02 2012 +0100
> > @@ -1844,13 +1844,14 @@ static void device_disk_add(libxl__egc *
> >                  break;
> >
> >              case LIBXL_DISK_BACKEND_TAP:
> > -                dev = libxl__blktap_devpath(gc, disk->pdev_path,
> disk->format);
> > -                if (!dev) {
> > -                    LOG(ERROR, "failed to get blktap devpath for
> %p\n",
> > -                        disk->pdev_path);
> > +                rc = libxl__blktap_devpath(gc, disk->pdev_path,
> disk->format);
> > +                if (rc) {
> > +                    LOG(ERROR, "failed to get blktap devpath for %s:
> %s\n",
> > +                        disk->pdev_path, strerror(rc));
> >                      rc = ERROR_FAIL;
> >                      goto out;
> >                  }
> > +                dev = NULL;
> >                  flexarray_append(back, "tapdisk-params");
> >                  flexarray_append(back, libxl__sprintf(gc, "%s:%s",
> >
> > libxl__device_disk_string_of_format(disk->format),
> > @@ -2277,8 +2278,13 @@ void libxl__device_disk_local_initiate_a
> >                  dev = disk->pdev_path;
> >                  break;
> >              case LIBXL_DISK_FORMAT_VHD:
> > -                dev = libxl__blktap_devpath(gc, disk->pdev_path,
> > -                                            disk->format);
> > +                rc = libxl__blktap_devpath(gc, disk->pdev_path,
> disk->format);
> > +                if (!rc) {
> > +                    LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
> > +                           "error getting tapdisk: %s",
> strerror(rc));
> > +                    rc = ERROR_FAIL;
> > +                    goto out;
> > +                }
> >                  break;
> >              case LIBXL_DISK_FORMAT_QCOW:
> >              case LIBXL_DISK_FORMAT_QCOW2:
> > diff -r 80e0bc67dcda -r bcb5a6182868 tools/libxl/libxl_blktap3.c
> > --- a/tools/libxl/libxl_blktap3.c   Wed Oct 24 17:24:53 2012 +0100
> > +++ b/tools/libxl/libxl_blktap3.c   Wed Oct 24 17:25:02 2012 +0100
> > @@ -5,9 +5,9 @@ int libxl__blktap_enabled(libxl__gc *gc)
> >      return 1;
> >  }
> >
> > -char *libxl__blktap_devpath(libxl__gc *gc, const char *disk,
> > +int libxl__blktap_devpath(libxl__gc *gc, const char *disk,
> >      libxl_disk_format format) {
> > -    return NULL;
> > +    return -ENOSYS;
> >  }
> >
> >  int libxl__device_destroy_tapdisk(libxl__gc *gc, const char
> *be_path)
> > { diff -r 80e0bc67dcda -r bcb5a6182868 tools/libxl/libxl_internal.h
> > --- a/tools/libxl/libxl_internal.h  Wed Oct 24 17:24:53 2012
> +0100
> > +++ b/tools/libxl/libxl_internal.h  Wed Oct 24 17:25:02 2012
> +0100
> > @@ -1344,10 +1344,9 @@ struct libxl__cpuid_policy {
> >  /* libxl__blktap_devpath:
> >   *    Argument: path and disk image as specified in config file.
> >   *      The type specifies whether this is aio, qcow, qcow2, etc.
> > - *    returns device path xenstore wants to have. returns NULL
> > - *      if no device corresponds to the disk.
> > + *    returns 0 on success, an error code otherwise
> >   */
> > -_hidden char *libxl__blktap_devpath(libxl__gc *gc,
> > +_hidden int libxl__blktap_devpath(libxl__gc *gc,
> >                                      const char *disk,
> >                                      libxl_disk_format format);
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxx
> > http://lists.xen.org/xen-devel
> 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel