On Thu, Jul 09, 2020 at 04:26:42PM +0300, Denis V. Lunev wrote:
> Right now bdrv_fclose() is just calling bdrv_flush().
>
> The problem is that migration code is working inefficiently from block
> layer terms and are frequently called for very small pieces of
> unaligned data. Block layer is capable to work this way, but this is very
> slow.
>
> This patch is a preparation for the introduction of the intermediate
> buffer at block driver state. It would be beneficial to separate
> conventional bdrv_flush() from closing QEMU file from migration code.
>
> The patch also forces bdrv_finalize_vmstate() operation inside
> synchronous blk_save_vmstate() operation. This helper is used from
> qemu-io only.
>
> Signed-off-by: Denis V. Lunev <[email protected]>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <[email protected]>
> CC: Kevin Wolf <[email protected]>
> CC: Max Reitz <[email protected]>
> CC: Stefan Hajnoczi <[email protected]>
> CC: Fam Zheng <[email protected]>
> CC: Juan Quintela <[email protected]>
> CC: "Dr. David Alan Gilbert" <[email protected]>
> CC: Denis Plotnikov <[email protected]>
> ---
> block/block-backend.c | 6 +++++-
> block/io.c | 15 +++++++++++++++
> include/block/block.h | 5 +++++
> migration/savevm.c | 4 ++++
> 4 files changed, 29 insertions(+), 1 deletion(-)
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 45c9dd9d8a..d8a94e312c 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -150,6 +150,10 @@ static ssize_t block_get_buffer(void *opaque, uint8_t
> *buf, int64_t pos,
>
> static int bdrv_fclose(void *opaque, Error **errp)
> {
> + int err = bdrv_finalize_vmstate(opaque);
> + if (err < 0) {
> + return err;
This is returning an error without having populating 'errp' which means
the caller will be missing error diagnosis
> + }
> return bdrv_flush(opaque);
> }
Regards,
Daniel
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