Re: [PATCH v2 2/5] generic: enable swapfile tests on Btrfs

Eryu Guan
2018-05-22T06:41:51Z

On Wed, May 16, 2018 at 01:38:46PM -0700, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
>
> Commit 8c96cfbfe530 ("generic/35[67]: disable swapfile tests on Btrfs")
> disabled the swapfile tests on Btrfs because it did not support
> swapfiles at the time. Now that we're adding support, we want these

So currently btrfs has no swapfile support yet, and tests still _notrun
with current v4.17-rc5 kernel? Just want to make sure that's expected.

> tests to run, but they don't. _require_scratch_swapfile always fails for
> Btrfs because swapfiles on Btrfs must be set to nocow. After fixing
> that, generic/356 and generic/357 fail for the same reason. After fixing
> _that_, both tests still fail because we don't allow reflinking a
> non-checksummed extent (which nocow implies) to a checksummed extent.
> Add a helper for formatting a swap file which does the chattr, and
> chattr the second file, which gets these tests running on kernels
> supporting Btrfs swapfiles.
>
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
> common/rc | 15 ++++++++++++---
> tests/generic/356 | 7 ++++---
> tests/generic/357 | 6 +++---
> 3 files changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/common/rc b/common/rc
> index ffe53236..814b8b5c 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -2222,6 +2222,17 @@ _require_odirect()
> rm -f $testfile 2>&1 > /dev/null
> }
>
> +_format_swapfile() {
> + local fname="$1"
> + local sz="$2"
> +
> + touch "$fname"

Better to remove $fname first, just in case it's an existing file with
some blocks allocated, as chattr(1) says

"Note: For btrfs, the 'C' flag should be set on new or empty files. If
it is set on a file which already has data blocks, it is undefined when
the blocks assigned to the file will be fully stable"

> + chmod 0600 "$fname"
> + $CHATTR_PROG +C "$fname" > /dev/null 2>&1

It'd be good to have some comments on this chattr +C.

> + _pwrite_byte 0x61 0 "$sz" "$fname" >> $seqres.full
> + mkswap -U 27376b42-ff65-42ca-919f-6c9b62292a5c "$fname" >> $seqres.full

Is the label really needed?

Thanks,
Eryu

> +}
> +
> # Check that the filesystem supports swapfiles
> _require_scratch_swapfile()
> {
> @@ -2231,10 +2242,8 @@ _require_scratch_swapfile()
> _scratch_mount
>
> # Minimum size for mkswap is 10 pages
> - local size=$(($(get_page_size) * 10))
> + _format_swapfile "$SCRATCH_MNT/swap" $(($(get_page_size) * 10))
>
> - _pwrite_byte 0x61 0 "$size" "$SCRATCH_MNT/swap" >/dev/null 2>&1
> - mkswap "$SCRATCH_MNT/swap" >/dev/null 2>&1
> if ! swapon "$SCRATCH_MNT/swap" >/dev/null 2>&1; then
> _scratch_unmount
> _notrun "swapfiles are not supported"
> diff --git a/tests/generic/356 b/tests/generic/356
> index 51eeb652..b4a38f84 100755
> --- a/tests/generic/356
> +++ b/tests/generic/356
> @@ -59,11 +59,12 @@ blocks=160
> blksz=65536
>
> echo "Initialize file"
> -echo >> $seqres.full
> -_pwrite_byte 0x61 0 $((blocks * blksz)) $testdir/file1 >> $seqres.full
> -mkswap -U 27376b42-ff65-42ca-919f-6c9b62292a5c $testdir/file1 >> $seqres.full
> +_format_swapfile "$testdir/file1" $((blocks * blksz))
> swapon $testdir/file1
>
> +touch "$testdir/file2"
> +$CHATTR_PROG +C "$testdir/file2" >/dev/null 2>&1
> +
> echo "Try to reflink"
> _cp_reflink $testdir/file1 $testdir/file2 2>&1 | _filter_scratch
>
> diff --git a/tests/generic/357 b/tests/generic/357
> index 0dd0c10f..9a83a283 100755
> --- a/tests/generic/357
> +++ b/tests/generic/357
> @@ -59,9 +59,9 @@ blocks=160
> blksz=65536
>
> echo "Initialize file"
> -echo >> $seqres.full
> -_pwrite_byte 0x61 0 $((blocks * blksz)) $testdir/file1 >> $seqres.full
> -mkswap -U 27376b42-ff65-42ca-919f-6c9b62292a5c $testdir/file1 >> $seqres.full
> +_format_swapfile "$testdir/file1" $((blocks * blksz))
> +touch "$testdir/file2"
> +$CHATTR_PROG +C "$testdir/file2" >/dev/null 2>&1
> _cp_reflink $testdir/file1 $testdir/file2 2>&1 | _filter_scratch
>
> echo "Try to swapon"
> --
> 2.17.0
>