Re: [PATCH v3] fstests: generic: add a test case to check fsverity reads

[Eric Biggers <ebiggers@kernel.org>]

On Mon, Oct 12, 2026 at 08:56:13AM +1030, Qu Wenruo wrote:
> +_fixed_by_fs_commit btrfs xxxxxxxxxxxx \
> +	"btrfs: fix the fsverity callback where unexpected range is verified"

Even without that commit, 'kvm-xfstests -c btrfs generic/807' still
passes.  Under what circumstances will this test fail?

> +# Read the file, unpatched btrfs will verify blocks outside the read range and
> +# trigger fs-verity warnings.
> +# But the read itself should still be fine, as the failed part will be retried.
> +cat "$SCRATCH_MNT/foobar" > /dev/null

How about using md5sum and putting the expected value in the .out file,
so the contents are validated too?

> +# Check for any kernel warnings from fs-verity on file corruption.
> +if _check_dmesg_for "FILE CORRUPTED!"; then
> +	echo "fs-verity detected corruption"
> +fi

Is there a way to use the fserror support being added by
https://lore.kernel.org/fsverity/20261002223705.2175542-2-aalbersh@kernel.org/
instead of relying on the unstable text printed to the kernel log?  If
the string is changed at all, this test will become ineffective.

- Eric