Re: [PATCH] btrfs: add test case to verify the behavior with large RAID0 data chunks

[Anand Jain <anand.jain@oracle.com>]

> +for i in $SCRATCH_DEV_POOL; do
> +	devsize=$(blockdev --getsize64 "$i")
> +	if [ $devsize -lt $((2 * 1024 * 1024 * 1024)) ]; then
> +		_notrun "device $i is too small, need at least 2G"

Also, you need to check if those devices support discard.

Uneven device sizes will alter the distribution of chunk allocation.
Since the default chunk allocation is also based on the device sizes
and free spaces.


> +	fi
> +done
> +
> +_scratch_pool_mkfs -m raid1 -d raid0 >> $seqres.full 2>&1
> +_scratch_mount
> +
> +# Fill the data chunk with 5G data.
> +for (( i = 0; i < $nr_files; i++ )); do
> +	xfs_io -f -c "pwrite -i /dev/urandom 0 $filesize" $SCRATCH_MNT/file_$i > /dev/null
> +done
> +sync
> +echo "=== With initial 5G data written ===" >> $seqres.full
> +$BTRFS_UTIL_PROG filesystem df $SCRATCH_MNT >> $seqres.full
> +
> +_scratch_unmount
> +
> +# Make sure we haven't corrupted anything.
> +$BTRFS_UTIL_PROG check --check-data-csum $SCRATCH_DEV >> $seqres.full 2>&1
> +if [ $? -ne 0 ]; then
> +	_fail "data corruption detected after initial data filling"
> +fi
> +
> +_scratch_mount
> +# Delete half of the data, and do discard
> +rm -rf - "$SCRATCH_MNT/*[02468]"

Are there any specific chunks that need to be deleted to successfully
reproduce this test case?

> +sync
> +$FSTRIM_PROG $SCRATCH_MNT

Do we need fstrim if we use mount -o discard=sync instead?

Thanks, Anand