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Date:   Mon, 24 Jun 2019 09:07:30 -0400
From:   "Theodore Ts'o" <tytso@mit.edu>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     "Darrick J. Wong" <darrick.wong@oracle.com>,
        Eryu Guan <guaneryu@gmail.com>,
        Gabriel Krisman Bertazi <krisman@collabora.com>,
        fstests@vger.kernel.org, linux-ext4@vger.kernel.org,
        "Lakshmipathi.G" <lakshmipathi.ganapathi@collabora.co.uk>
Subject: Re: Removing the shared class of tests
Message-ID: <20190624130730.GD1805@mit.edu>
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On Mon, Jun 24, 2019 at 12:16:10AM -0700, Christoph Hellwig wrote:
> 
> As for the higher level question?  The shared tests always confused the
> heck out of me.  generic with the right feature checks seem like a much
> better idea.

Agreed.  I've sent out a patch series to bring the number of patches
in shared down to four.  Here's what's left:

shared/002 --- needs a feature test to somehow determine whether a
	file system supports thousads of xattrs in a file (currently
	on btrfs and xfs)

shared/011 --- needs some way of determining that a file system
	supports cgroup-aware writeback (currently enabled only for
	ext4 and btrfs).  Do we consider lack of support of
	cgroup-aware writeback a bug?  If so, maybe it doesn't need a
	feature test at all?

shared/032 --- needs a feature test to determine whether or not a file
	system's mkfs supports detection of "foreign file systems".
	e.g., whether or not it warns if you try overwrite a file
	system w/o another file system.  (Currently enabled by xfs and
	btrfs; it doesn't work for ext[234] because e2fsprogs, because
	I didn't want to break existing shell scripts, only warns when
	it is used interactively.  We could a way to force it to be
	activated it points out this tests is fundamentally testing
	implementation choices of the userspace utilities of a file
	system.  Does it belong in xfstests?   : ¯\_(ツ)_/¯ )

shared/289 --- contains ext4, xfs, and btrfs mechanisms for
	determining blocks which are unallocated.  Has hard-coded
	invocations to dumpe2fs, xfs_db, and /bin/btrfs.

These don't have obvious solutions.  We could maybe add a _notrun if
adding the thousands of xattrs fails with an ENOSPC or related error
(f2fs uses something else).

Maybe we just move shared/011 and move it generic/ w/o a feature test.

Maybe we remove shared/032 altogether, since for e2fsprogs IMHO
the right place to put it is the regression test in e2fsprogs --- but
I know xfs has a different test philosophy for xfsprogs; and tha begs
the question of what to do for mkfs.btrfs.

And maybe we just split up shared/289 to three different tests in
ext4/, xfs/, and btrfs/, since it would make the test script much
simpler to understand?

What do people think?

						- Ted