Re: [Qemu-devel] [PATCH] block/gluster: defend on legacy ftruncate api use

[Niels de Vos <ndevos@redhat.com>]

This change looks good to me, but a commit message would have been
helpful. I suggest something like this:

  Gluster 4.0 changed the signature of glfs_ftruncate(). The function
  now has two additional arguments, namely prestat and poststat. These
  provide not benefit for QEMU, so ignoring them and passing NULL makes
  the gluster-block driver compile with the new Gluster version again.

And maybe add this too:

  Glusters libgfapi uses symbol versioning and provides backwards
  compatible functions. Binaries compiled against previous versions of
  Gluster keep on functioning with the new library.

Thanks!

Reviewed-by: Niels de Vos <ndevos@redhat.com>


On Thu, Apr 12, 2018 at 04:46:14PM +0530, Prasanna Kumar Kalever wrote:
> Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
> ---
>  block/gluster.c | 15 +++++++++++++--
>  configure       |  8 ++++++++
>  2 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/block/gluster.c b/block/gluster.c
> index 4adc1a875b..2474580ad6 100644
> --- a/block/gluster.c
> +++ b/block/gluster.c
> @@ -996,6 +996,7 @@ static int qemu_gluster_do_truncate(struct glfs_fd *fd, int64_t offset,
>                                      PreallocMode prealloc, Error **errp)
>  {
>      int64_t current_length;
> +    int ret;
>  
>      current_length = glfs_lseek(fd, 0, SEEK_END);
>      if (current_length < 0) {
> @@ -1023,7 +1024,12 @@ static int qemu_gluster_do_truncate(struct glfs_fd *fd, int64_t offset,
>  #endif /* CONFIG_GLUSTERFS_FALLOCATE */
>  #ifdef CONFIG_GLUSTERFS_ZEROFILL
>      case PREALLOC_MODE_FULL:
> -        if (glfs_ftruncate(fd, offset)) {
> +#ifdef CONFIG_GLUSTERFS_LEGACY_FTRUNCATE
> +        ret = glfs_ftruncate(fd, offset);
> +#else
> +        ret = glfs_ftruncate(fd, offset, NULL, NULL);
> +#endif
> +        if (ret) {
>              error_setg_errno(errp, errno, "Could not resize file");
>              return -errno;
>          }
> @@ -1034,7 +1040,12 @@ static int qemu_gluster_do_truncate(struct glfs_fd *fd, int64_t offset,
>          break;
>  #endif /* CONFIG_GLUSTERFS_ZEROFILL */
>      case PREALLOC_MODE_OFF:
> -        if (glfs_ftruncate(fd, offset)) {
> +#ifdef CONFIG_GLUSTERFS_LEGACY_FTRUNCATE
> +        ret = glfs_ftruncate(fd, offset);
> +#else
> +        ret = glfs_ftruncate(fd, offset, NULL, NULL);
> +#endif
> +        if (ret) {
>              error_setg_errno(errp, errno, "Could not resize file");
>              return -errno;
>          }
> diff --git a/configure b/configure
> index 0a19b033bc..69827b0098 100755
> --- a/configure
> +++ b/configure
> @@ -429,6 +429,7 @@ glusterfs_xlator_opt="no"
>  glusterfs_discard="no"
>  glusterfs_fallocate="no"
>  glusterfs_zerofill="no"
> +glusterfs_legacy_ftruncate="no"
>  gtk=""
>  gtkabi=""
>  gtk_gl="no"
> @@ -3856,6 +3857,9 @@ if test "$glusterfs" != "no" ; then
>        glusterfs_fallocate="yes"
>        glusterfs_zerofill="yes"
>      fi
> +    if ! $pkg_config --atleast-version=7.4 glusterfs-api; then
> +      glusterfs_legacy_ftruncate="yes"
> +    fi
>    else
>      if test "$glusterfs" = "yes" ; then
>        feature_not_found "GlusterFS backend support" \
> @@ -6502,6 +6506,10 @@ if test "$glusterfs_zerofill" = "yes" ; then
>    echo "CONFIG_GLUSTERFS_ZEROFILL=y" >> $config_host_mak
>  fi
>  
> +if test "$glusterfs_legacy_ftruncate" = "yes" ; then
> +  echo "CONFIG_GLUSTERFS_LEGACY_FTRUNCATE=y" >> $config_host_mak
> +fi
> +
>  if test "$libssh2" = "yes" ; then
>    echo "CONFIG_LIBSSH2=m" >> $config_host_mak
>    echo "LIBSSH2_CFLAGS=$libssh2_cflags" >> $config_host_mak
> -- 
> 2.14.3
>