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

[Juan Quintela]

Jeff Cody  wrote:
> On Mon, May 15, 2017 at 03:05:29PM +0100, Dr. David Alan Gilbert (git) wrote:
>> From: "Dr. David Alan Gilbert" 
>> 
>> 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 
>
> Reviewed-by: Jeff Cody 

Hi

You thought it was going to be so easy O:-)

You can see that this patch is the last one of the Series:

Remove old MigrationParams

And as there has been quite a bit of changes, I would preffer the
review-by there.  (Hint, hint)

Thanks, Juan.

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

[Jeff Cody]

On Mon, May 15, 2017 at 03:05:29PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" 
> 
> 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 

Reviewed-by: Jeff Cody 

> ---
>  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
> 

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

[Juan Quintela]

"Dr. David Alan Gilbert (git)"  wrote:
> From: "Dr. David Alan Gilbert" 
>
> 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 

Reviewed-by: Juan Quintela 

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

[Eric Blake]

On 05/15/2017 09:05 AM, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" 
> 
> 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 
> ---
>  configure | 11 +++
>  include/migration/block.h | 23 +++
>  migration/Makefile.objs   |  2 +-
>  migration/migration.c |  9 +
>  4 files changed, 44 insertions(+), 1 deletion(-)
> 

> @@ -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

Bummer that the long name breaks alignment. But I don't have any
bikeshed paint handy to suggest a shorter name.

> +++ 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

Juan's pending series to simplify the representation of -b/-i may also
play a role here, particularly if we want to bite the bullet and change
the QMP command to drop the optional parameters altogether.

It may be worth documenting in the .json file (independently of whether
the configure option is used) that blk/inc are deprecated, and may be
removed in a future release, if we want to start the clock on removing them.

Reviewed-by: Eric Blake 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.   +1-919-301-3266
Virtualization:  qemu.org | libvirt.org



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