Re: [PATCH] btrfs: add test case to make sure autodefrag won't give up the whole cluster when there is a hole in it

[David Sterba <dsterba@suse.cz>]

On Fri, Jan 28, 2022 at 07:32:53AM +0800, Qu Wenruo wrote:
> On 2022/1/27 19:23, Filipe Manana wrote:
> > On Thu, Jan 27, 2022 at 01:45:43PM +0800, Qu Wenruo wrote:
> >> +get_extent_disk_sector()
> >> +{
> >> +	local file=$1
> >> +	local offset=$2
> >> +
> >> +	$XFS_IO_PROG -c "fiemap $offset" "$file" | _filter_xfs_io_fiemap |\
> >> +		head -n1 | $AWK_PROG '{print $3}'
> >> +}
> >> +
> >> +# Needs 4K sectorsize, as larger sectorsize can change the file layout.
> >> +_require_btrfs_support_sectorsize 4096
> >> +
> >> +# We need a way to trigger autodefrag
> >> +_require_btrfs_debug_cleaner_trigger
> >
> > In order to trigger the cleaner, we don't need another special purpose
> > RFC debug patch.
> >
> > Just mount the fs with "-o commit=1", and then leave the "sleep 3" as it
> > is. We do this in other tests that expect the cleaner thread to do
> > something. Every time the transaction kthread wakes up, it will wake up
> > the cleaner kthread, even if it doesn't have any transaction to commit.
> 
> Right! That's way better than the RFC patch.

Also the BTRFS_IOC_SYNC ioctl (available as "btrfs filesystem sync")
will wake the transaction kthread.