[LTP] LTP test df01.sh detected different size of loop device in v5.19

[Petr Vorel]

> On Thu, Aug 18, 2022 at 11:05:33AM -0500, Eric Sandeen wrote:
> > On 8/18/22 10:25 AM, Petr Vorel wrote:
> > > Hi Eric, all,


> > ...


> > >> IOWS, I think the test expects that free space is reflected in statfs numbers
> > >> immediately after a file is removed, and that's no longer the case here. They
> > >> change in between the df check and the statfs check.

> > >> (The test isn't just checking that the values are correct, it is checking that
> > >> the values are /immediately/ correct.)

> > >> Putting a "sleep 1" after the "rm -f" in the test seems to fix it; IIRC
> > >> the max time to wait for inodegc is 1s. This does slow the test down a bit.

> > > Sure, it looks like we can sleep just 50ms on my hw (although better might be to
> > > poll for the result [1]), I just wanted to make sure there is no bug/regression
> > > before hiding it with sleep.

> > > Thanks for your input!

> > > Kind regards,
> > > Petr

> > > [1] https://people.kernel.org/metan/why-sleep-is-almost-never-acceptable-in-tests

> > >> -Eric

> > > +++ testcases/commands/df/df01.sh
> > > @@ -63,6 +63,10 @@ df_test()
> > >  		tst_res TFAIL "'$cmd' failed."
> > >  	fi

> > > +	if [ "$DF_FS_TYPE" = xfs ]; then
> > > +		tst_sleep 50ms
> > > +	fi
> > > +

> > Probably worth at least a comment as to why ...

Sure, that was just to document possible fix. BTW even 200ms was not reliable in
the long run => not a good solution.

> > Dave / Darrick / Brian - I'm not sure how long it might take to finish inodegc?
> > A too-short sleep will let the flakiness remain ...

> A fsfreeze -f / fsfreeze -u cycle will force all the background garbage
> collection to run to completion when precise free space accounting is
> being tested.
Thanks for a hint, do you mean to put it into df_test after creating file with
dd to wrap second df_verify (calls df) and df_check (runs stat and compare values)?
Because that does not help - it fails when running in the loop (managed to break after 5th run).

Kind regards,
Petr

df_test()
{
	local cmd="$1 -P"

	df_verify $cmd
	if [ $? -ne 0 ]; then
		return
	fi

	df_check $cmd
	if [ $? -ne 0 ]; then
		tst_res TFAIL "'$cmd' failed, not expected."
		return
	fi

	ROD_SILENT dd if=/dev/zero of=mntpoint/testimg bs=1024 count=1024

	if [ "$DF_FS_TYPE" = xfs ]; then
		fsfreeze -f $TST_MNTPOINT
	fi

	df_verify $cmd

	df_check $cmd
	if [ $? -eq 0 ]; then
		tst_res TPASS "'$cmd' passed."
	else
		tst_res TFAIL "'$cmd' failed."
	fi

	if [ "$DF_FS_TYPE" = xfs ]; then
		fsfreeze -u $TST_MNTPOINT
	fi

	ROD_SILENT rm -rf mntpoint/testimg

	# flush file system buffers, then we can get the actual sizes.
	sync
}

df_verify()
{
	$@ >output 2>&1
	if [ $? -ne 0 ]; then
		grep -q -E "unrecognized option | invalid option" output
		if [ $? -eq 0 ]; then
			tst_res TCONF "'$@' not supported."
			return 32
		else
			tst_res TFAIL "'$@' failed."
			cat output
			return 1
		fi
	fi
}

df_check()
{
	if [ "$(echo $@)" = "df -i -P" ]; then
		local total=$(stat -f mntpoint --printf=%c)
		local free=$(stat -f mntpoint --printf=%d)
		local used=$((total-free))
	else
		local total=$(stat -f mntpoint --printf=%b)
		local free=$(stat -f mntpoint --printf=%f)
		local used=$((total-free))
		local bsize=$(stat -f mntpoint --printf=%s)
		total=$((($total * $bsize + 512)/ 1024))
		used=$((($used * $bsize + 512) / 1024))
	fi

	grep ${TST_DEVICE} output | grep -q "${total}.*${used}"
	if [ $? -ne 0 ]; then
		echo "total: ${total}, used: ${used}"
		echo "df saved output:"
		cat output
		echo "df output:"
		$@
		return 1
	fi
}

> --D

> > -Eric

> > >  	ROD_SILENT rm -rf mntpoint/testimg

> > >  	# flush file system buffers, then we can get the actual sizes.