Re: [PATCH v2 2/3] generic/574: corrupt btrfs merkle tree data

From: Boris Burkov <boris@bur.io>
To: Eric Biggers <ebiggers@kernel.org>
Cc: fstests@vger.kernel.org, linux-fscrypt@vger.kernel.org,
	linux-btrfs@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH v2 2/3] generic/574: corrupt btrfs merkle tree data
Date: Thu, 8 Apr 2021 11:49:37 -0700	[thread overview]
Message-ID: <YG9QQUHzoA045Ngt@zen> (raw)
In-Reply-To: <YG9OZseq1nGv/wMk@sol.localdomain>

On Thu, Apr 08, 2021 at 11:41:42AM -0700, Eric Biggers wrote:
> On Thu, Apr 08, 2021 at 11:30:12AM -0700, Boris Burkov wrote:
> > 
> > Note that there is a bit of a kludge here: since btrfs_corrupt_block
> > doesn't handle streaming corruption bytes from stdin (I could change
> > that, but it feels like overkill for this purpose), I just read the
> > first corruption byte and duplicate it for the desired length. That is
> > how the test is using the interface in practice, anyway.
> 
> If that's the problem, couldn't you just write the data to a temporary file?

Sorry, I was a bit too vague. It doesn't have a file or stdin interface,
as far as I know.

btrfs-corrupt-block has your typical "kitchen sink of flags" interface and
doesn't currently read input from streams/files. I extended that
interface in the simplest way to support arbitrary corruption, which
didn't fit with the stream based corruption this test does.

my options seem to be:
shoehorn the "byte, length" interface into this test or
shoehorn the "stream corruption input in" interface into
btrfs-corrupt-block.

I have no problem with either, the former was just less work because I
already wrote it that way. If the junk I did here is a deal-breaker, I
don't mind modifying btrfs-corrupt-block.

> 
> - Eric

Thanks for the quick review,
Boris