Re: [PATCH 2/7] writeback: switch to per-bdi threads for flushing data

Christoph Hellwig
2009-03-16T10:23:14Z

On Thu, Mar 12, 2009 at 03:33:43PM +0100, Jens Axboe wrote:
> +static void bdi_kupdated(struct backing_dev_info *bdi)
> +{
> + long nr_to_write;
> + struct writeback_control wbc = {
> + .bdi = bdi,
> + .sync_mode = WB_SYNC_NONE,
> + .nr_to_write = 0,
> + .for_kupdate = 1,
> + .range_cyclic = 1,
> + };
> +
> + sync_supers();

Not directly related to your patch, but can someone explain WTF
sync_supers is doing here or in the old kupdated? We're writing back
dirty pages from the VM, and for some reason we try to also write back
superblocks. This doesn't really make any sense.