Re: [Qemu-devel] [RFC PATCH 02/10] block: add a function to set incoming live migration

[Stefan Hajnoczi <stefanha@gmail.com>]

On Tue, Mar 06, 2012 at 06:32:21PM +0100, Benoît Canet wrote:
> This function will help to inform the block layer that an incoming
> live migration is coming in order to make proper usage of the
> BDRV_O_INCOMING flag.
> 
> Signed-off-by: Benoit Canet <benoit.canet@gmail.com>
> ---
>  block.c |    8 ++++++++
>  block.h |    2 ++
>  2 files changed, 10 insertions(+), 0 deletions(-)

The block layer doesn't need to keep track of incoming migrations:

blockdev.c:drive_init() or vl.c:drive_init_func() could use
runstate_check(RUN_STATE_INMIGRATE) to check whether incoming migration
is in progress.  If so, they would pass in BDRV_O_INCOMING during image
creation.  As a result we don't need to introduce this global variable
or functions to manipulate it in the block layer.

The block layer post migration function will still need to clear
BDRV_O_INCOMING from open_flags.

Stefan