Re: RFC: don't fail tests when mkfs options collide

[Christoph Hellwig <hch@lst.de>]

On Mon, Jul 22, 2024 at 11:50:16PM -0400, Theodore Ts'o wrote:
> Yeah, it's a bit of a mess.  It's not been an issue for ext4 because
> mkfs.ext4 allows options specified later in the command-line to
> override earlier ones.

At least in my case it's not really by overriding.  E.g. if I force
an allocation group (or block group in extN terms) to a specific size
and then want a log that is larger than that, changing the AG size
is generally a bad idea, and a clear warning to the user is simply the
better interface.

> There's a third possibility, which is sometimes the test might
> explicitly want the mkfs options to be merged together.  For example,
> in the ext4/4k configuration we have "-b 4096", while the ext4/1k
> confiuration option we might have "-b 1024".  And we might want to
> have that *combined* with a test which is enabling fscrypt feature, so
> we can test fscrypt with a 4k block size, as well as fsvrypt with a 1k
> blocksize.
> 
> That being said, that doesn't always make sense, and sometimes the
> combination doesn't make any sense.

Merging the options is what we're currently doing, and it works ok
most of the time.  The question is what to do when it doesn't.