Re: [Qemu-devel] [PATCH 3/7] qcow2: add a migration blocker

[Lucas Meneghel Rodrigues <lmr@redhat.com>]

On 11/12/2011 01:57 PM, Anthony Liguori wrote:
> Now when you try to migrate with qcow2, you get:
>
> (qemu) migrate tcp:localhost:1025
> Block format 'qcow2' used by device 'ide0-hd0' does not support feature 'live migration'
> (qemu)

LGTM. From a testing perspective, it's clear and understandable, a lot 
better than throwing a generic error.

> Signed-off-by: Anthony Liguori<aliguori@us.ibm.com>
> ---
>   block/qcow2.c |    9 +++++++++
>   block/qcow2.h |    2 ++
>   qemu-tool.c   |    9 +++++++++
>   qerror.c      |    4 ++++
>   qerror.h      |    3 +++
>   5 files changed, 27 insertions(+), 0 deletions(-)
>
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 5c784ee..e4126b7 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -29,6 +29,7 @@
>   #include "block/qcow2.h"
>   #include "qemu-error.h"
>   #include "qerror.h"
> +#include "migration.h"
>
>   /*
>     Differences with QCOW:
> @@ -277,6 +278,11 @@ static int qcow2_open(BlockDriverState *bs, int flags)
>           goto fail;
>       }
>
> +    error_set(&s->migration_blocker,
> +              QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
> +              "qcow2", bs->device_name, "live migration");
> +    migrate_add_blocker(s->migration_blocker);
> +
>       /* Initialise locks */
>       qemu_co_mutex_init(&s->lock);
>
> @@ -621,6 +627,9 @@ static void qcow2_close(BlockDriverState *bs)
>       BDRVQcowState *s = bs->opaque;
>       g_free(s->l1_table);
>
> +    migrate_del_blocker(s->migration_blocker);
> +    error_free(s->migration_blocker);
> +
>       qcow2_cache_flush(bs, s->l2_table_cache);
>       qcow2_cache_flush(bs, s->refcount_block_cache);
>
> diff --git a/block/qcow2.h b/block/qcow2.h
> index 531af39..0734b23 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -125,6 +125,8 @@ typedef struct BDRVQcowState {
>       int snapshots_size;
>       int nb_snapshots;
>       QCowSnapshot *snapshots;
> +
> +    Error *migration_blocker;
>   } BDRVQcowState;
>
>   /* XXX: use std qcow open function ? */
> diff --git a/qemu-tool.c b/qemu-tool.c
> index e9f7fe1..5df7279 100644
> --- a/qemu-tool.c
> +++ b/qemu-tool.c
> @@ -15,6 +15,7 @@
>   #include "monitor.h"
>   #include "qemu-timer.h"
>   #include "qemu-log.h"
> +#include "migration.h"
>
>   #include<sys/time.h>
>
> @@ -92,3 +93,11 @@ int64_t qemu_get_clock_ns(QEMUClock *clock)
>   {
>       return 0;
>   }
> +
> +void migrate_add_blocker(Error *reason)
> +{
> +}
> +
> +void migrate_del_blocker(Error *reason)
> +{
> +}
> diff --git a/qerror.c b/qerror.c
> index 8e30e2d..fdf62b9 100644
> --- a/qerror.c
> +++ b/qerror.c
> @@ -49,6 +49,10 @@ static const QErrorStringTable qerror_table[] = {
>           .desc      = "Device '%(device)' can't go on a %(bad_bus_type) bus",
>       },
>       {
> +        .error_fmt = QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
> +        .desc      = "Block format '%(format)' used by device '%(name)' does not support feature '%(feature)'",
> +    },
> +    {
>           .error_fmt = QERR_BUS_NOT_FOUND,
>           .desc      = "Bus '%(bus)' not found",
>       },
> diff --git a/qerror.h b/qerror.h
> index 7e2eebf..2d3d43b 100644
> --- a/qerror.h
> +++ b/qerror.h
> @@ -54,6 +54,9 @@ QError *qobject_to_qerror(const QObject *obj);
>   #define QERR_BAD_BUS_FOR_DEVICE \
>       "{ 'class': 'BadBusForDevice', 'data': { 'device': %s, 'bad_bus_type': %s } }"
>
> +#define QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED \
> +    "{ 'class': 'BlockFormatFeatureNotSupported', 'data': { 'format': %s, 'name': %s, 'feature': %s } }"
> +
>   #define QERR_BUS_NOT_FOUND \
>       "{ 'class': 'BusNotFound', 'data': { 'bus': %s } }"
>