Re: [Qemu-devel] [PATCH v2] block migration: Allow compile time disable

[Jeff Cody <jcody@redhat.com>]

On Mon, May 15, 2017 at 03:05:29PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Many users now prefer to use drive_mirror over NBD as an
> alternative to the older migrate -b option; drive_mirror is
> more complex to setup but gives you more options (e.g. only
> migrating some of the disks if some of them are shared).
> 
> Allow the large chunk of block migration code to be compiled
> out for those who don't use it.
> 
> Based on a downstream-patch we've had for a while by Jeff Cody.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Jeff Cody <jcody@redhat.com>

> ---
>  configure                 | 11 +++++++++++
>  include/migration/block.h | 23 +++++++++++++++++++++++
>  migration/Makefile.objs   |  2 +-
>  migration/migration.c     |  9 +++++++++
>  4 files changed, 44 insertions(+), 1 deletion(-)
> 
> v2
>   use error_append_hint, remove a '.' - Eric
>   Move ifdef's to block.h header - Juan
>   Explicitly state the blk/-b inc/-i in the message - Kashyap
> 
> diff --git a/configure b/configure
> index 39e727ef7e..29f5f626d7 100755
> --- a/configure
> +++ b/configure
> @@ -316,6 +316,7 @@ vte=""
>  virglrenderer=""
>  tpm="yes"
>  libssh2=""
> +live_block_migration="yes"
>  numa=""
>  tcmalloc="no"
>  jemalloc="no"
> @@ -1168,6 +1169,10 @@ for opt do
>    ;;
>    --enable-libssh2) libssh2="yes"
>    ;;
> +  --disable-live-block-migration) live_block_migration="no"
> +  ;;
> +  --enable-live-block-migration) live_block_migration="yes"
> +  ;;
>    --disable-numa) numa="no"
>    ;;
>    --enable-numa) numa="yes"
> @@ -1400,6 +1405,7 @@ disabled with --disable-FEATURE, default is enabled if available:
>    libnfs          nfs support
>    smartcard       smartcard support (libcacard)
>    libusb          libusb (for usb passthrough)
> +  live-block-migration   Block migration in the main migration stream
>    usb-redir       usb network redirection support
>    lzo             support of lzo compression library
>    snappy          support of snappy compression library
> @@ -5215,6 +5221,7 @@ echo "TPM support       $tpm"
>  echo "libssh2 support   $libssh2"
>  echo "TPM passthrough   $tpm_passthrough"
>  echo "QOM debugging     $qom_cast_debug"
> +echo "Live block migration $live_block_migration"
>  echo "lzo support       $lzo"
>  echo "snappy support    $snappy"
>  echo "bzip2 support     $bzip2"
> @@ -5781,6 +5788,10 @@ if test "$libssh2" = "yes" ; then
>    echo "LIBSSH2_LIBS=$libssh2_libs" >> $config_host_mak
>  fi
>  
> +if test "$live_block_migration" = "yes" ; then
> +  echo "CONFIG_LIVE_BLOCK_MIGRATION=y" >> $config_host_mak
> +fi
> +
>  # USB host support
>  if test "$libusb" = "yes"; then
>    echo "HOST_USB=libusb legacy" >> $config_host_mak
> diff --git a/include/migration/block.h b/include/migration/block.h
> index 41a1ac8f79..1a096e3978 100644
> --- a/include/migration/block.h
> +++ b/include/migration/block.h
> @@ -14,10 +14,33 @@
>  #ifndef MIGRATION_BLOCK_H
>  #define MIGRATION_BLOCK_H
>  
> +#ifdef CONFIG_LIVE_BLOCK_MIGRATION
>  void blk_mig_init(void);
>  int blk_mig_active(void);
>  uint64_t blk_mig_bytes_transferred(void);
>  uint64_t blk_mig_bytes_remaining(void);
>  uint64_t blk_mig_bytes_total(void);
>  
> +#else
> +static inline void blk_mig_init(void) { };
> +static inline int blk_mig_active(void)
> +{
> +    return false;
> +}
> +static inline uint64_t blk_mig_bytes_transferred(void)
> +{
> +    return 0;
> +}
> +
> +static inline uint64_t blk_mig_bytes_remaining(void)
> +{
> +    return 0;
> +}
> +
> +static inline uint64_t blk_mig_bytes_total(void)
> +{
> +    return 0;
> +}
> +#endif /* CONFIG_LIVE_BLOCK_MIGRATION */
> +
>  #endif /* MIGRATION_BLOCK_H */
> diff --git a/migration/Makefile.objs b/migration/Makefile.objs
> index 480dd493a9..200b5e0c67 100644
> --- a/migration/Makefile.objs
> +++ b/migration/Makefile.objs
> @@ -9,5 +9,5 @@ common-obj-y += qjson.o
>  
>  common-obj-$(CONFIG_RDMA) += rdma.o
>  
> -common-obj-y += block.o
> +common-obj-$(CONFIG_LIVE_BLOCK_MIGRATION) += block.o
>  
> diff --git a/migration/migration.c b/migration/migration.c
> index a5ade23e24..457f0b92df 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1213,6 +1213,15 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
>      params.blk = has_blk && blk;
>      params.shared = has_inc && inc;
>  
> +#ifndef CONFIG_LIVE_BLOCK_MIGRATION
> +    if (params.blk || params.shared) {
> +        error_setg(errp, "QEMU compiled without old-style (blk/-b, inc/-i) "
> +                         "block migration");
> +        error_append_hint(errp, "Use drive_mirror+NBD instead.\n");
> +        return;
> +    }
> +#endif
> +
>      if (migration_is_setup_or_active(s->state) ||
>          s->state == MIGRATION_STATUS_CANCELLING ||
>          s->state == MIGRATION_STATUS_COLO) {
> -- 
> 2.13.0
>