Re: [Qemu-devel] [PATCH 5/5] block migration: Allow compile time disable

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Juan Quintela (quintela@redhat.com) 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>
> 
> --
> 
> - When compiled out, allow seting block only with false value (eric)
> ---
>  configure                 | 11 +++++++++++
>  include/migration/block.h | 24 +++++++++++++++++++++++-
>  migration/Makefile.objs   |  2 +-
>  migration/migration.c     | 14 ++++++++++++++
>  4 files changed, 49 insertions(+), 2 deletions(-)
> 
> diff --git a/configure b/configure
> index 57b5ae6..ace1a52 100755
> --- a/configure
> +++ b/configure
> @@ -316,6 +316,7 @@ vte=""
>  virglrenderer=""
>  tpm="yes"
>  libssh2=""
> +live_block_migration="yes"
>  numa=""
>  tcmalloc="no"
>  jemalloc="no"
> @@ -1169,6 +1170,10 @@ 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"
> @@ -1401,6 +1406,7 @@ 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
> @@ -5216,6 +5222,7 @@ 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     $bzip2"
> @@ -5782,6 +5789,10 @@ if test "$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" >> $config_host_mak
> diff --git a/include/migration/block.h b/include/migration/block.h
> index 5225af9..28cff53 100644
> --- a/include/migration/block.h
> +++ b/include/migration/block.h
> @@ -14,12 +14,34 @@
>  #ifndef MIGRATION_BLOCK_H
>  #define MIGRATION_BLOCK_H
>  
> +#ifdef CONFIG_LIVE_BLOCK_MIGRATION
>  void blk_mig_init(void);
>  int blk_mig_active(void);
>  uint64_t blk_mig_bytes_transferred(void);
>  uint64_t blk_mig_bytes_remaining(void);
>  uint64_t blk_mig_bytes_total(void);
>  
> +#else
> +static inline void blk_mig_init(void) { }
> +static inline int blk_mig_active(void)
> +{
> +    return false;
> +}
> +static inline uint64_t blk_mig_bytes_transferred(void)
> +{
> +    return 0;
> +}
> +
> +static inline uint64_t blk_mig_bytes_remaining(void)
> +{
> +    return 0;
> +}
> +
> +static inline uint64_t blk_mig_bytes_total(void)
> +{
> +    return 0;
> +}
> +#endif /* CONFIG_LIVE_BLOCK_MIGRATION */
> +
>  void migrate_set_block_enabled(bool value, Error **errp);
> -
>  #endif /* MIGRATION_BLOCK_H */
> diff --git a/migration/Makefile.objs b/migration/Makefile.objs
> index c1920b6..00a3f4a 100644
> --- a/migration/Makefile.objs
> +++ b/migration/Makefile.objs
> @@ -9,5 +9,5 @@ common-obj-y += qjson.o
>  
>  common-obj-$(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 ed66158..2feeee8 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -547,6 +547,11 @@ MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
>  
>      caps = NULL; /* silence compiler warning */
>      for (i = 0; i < MIGRATION_CAPABILITY__MAX; i++) {
> +#ifndef CONFIG_LIVE_BLOCK_MIGRATION
> +        if (i == MIGRATION_CAPABILITY_BLOCK) {
> +            continue;
> +        }
> +#endif
>          if (i == MIGRATION_CAPABILITY_X_COLO && !colo_supported()) {
>              continue;
>          }
> @@ -763,6 +768,15 @@ void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
>      }
>  
>      for (cap = params; cap; cap = cap->next) {
> +#ifndef CONFIG_LIVE_BLOCK_MIGRATION
> +        if (cap->value->capability == MIGRATION_CAPABILITY_BLOCK
> +            && cap->value->state) {
> +            error_setg(errp, "QEMU compiled without old-style (blk/-b, inc/-i) "
> +                       "block migration");
> +            error_append_hint(errp, "Use drive_mirror+NBD instead.\n");
> +            continue;
> +        }
> +#endif

Yes, I think that looks OK, but you lost your S-o-b for your changes.

Dave

>          if (cap->value->capability == MIGRATION_CAPABILITY_X_COLO) {
>              if (!colo_supported()) {
>                  error_setg(errp, "COLO is not currently supported, please"
> -- 
> 2.9.3
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK