On 10.08.20 12:14, Denis V. Lunev wrote:
> Latency threshold is set to 10 seconds following guest request timeout
> on legacy storage controller.
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> CC: Max Reitz <mreitz@redhat.com>
> ---
>  blockdev.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/blockdev.c b/blockdev.c
> index 66158d1292..733fdd36da 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -622,8 +622,13 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
>  
>          bs->detect_zeroes = detect_zeroes;
>  
> +        /*
> +         * Set log threshold to 10 seconds. Timeout choosen by observation

*chosen

> +         * of the guest behavior with legacy storage controllers. Linux
> +         * could remount FS read-only if journal write takes this time.
> +         */
>          block_acct_setup(blk_get_stats(blk), account_invalid, account_failed,
> -                qemu_opt_get_number(opts, "latency-log-threshold", 0));
> +                qemu_opt_get_number(opts, "latency-log-threshold", 10000));

Yeah, why not.

Reviewed-by: Max Reitz <mreitz@redhat.com>