linux-kernel - Re: [PATCH v4 10/11] ext4: Atomic writes test for bigalloc using fio crc verifier on multiple files

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aKbYvubsS8xUG88d@li-dc0c254c-257c-11b2-a85c-98b6c1322444.ibm.com>
Date: Thu, 21 Aug 2025 13:58:46 +0530
From: Ojaswin Mujoo <ojaswin@...ux.ibm.com>
To: John Garry <john.g.garry@...cle.com>
Cc: Zorro Lang <zlang@...hat.com>, fstests@...r.kernel.org,
        Ritesh Harjani <ritesh.list@...il.com>, djwong@...nel.org,
        tytso@....edu, linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-ext4@...r.kernel.org
Subject: Re: [PATCH v4 10/11] ext4: Atomic writes test for bigalloc using fio
 crc verifier on multiple files

On Wed, Aug 13, 2025 at 02:45:28PM +0100, John Garry wrote:
> On 10/08/2025 14:42, Ojaswin Mujoo wrote:
> > From: "Ritesh Harjani (IBM)"<ritesh.list@...il.com>
> > 
> > Brute force all possible blocksize clustersize combination on a bigalloc
> > filesystem for stressing atomic write using fio data crc verifier. We run
> > multiple threads in parallel with each job writing to its own file. The
> > parallel jobs running on a constrained filesystem size ensure that we
> > stress the ext4 allocator to allocate contiguous extents.
> > 
> > This test might do overlapping atomic writes but that should be okay
> > since overlapping parallel hardware atomic writes don't cause tearing as
> > long as io size is the same for all writes.
> > 
> > Signed-off-by: Ritesh Harjani (IBM)<ritesh.list@...il.com>
> > Reviewed-by: Darrick J. Wong<djwong@...nel.org>
> > Signed-off-by: Ojaswin Mujoo<ojaswin@...ux.ibm.com>
> > ---
> >   tests/ext4/062     | 176 +++++++++++++++++++++++++++++++++++++++++++++
> >   tests/ext4/062.out |   2 +
> >   2 files changed, 178 insertions(+)
> >   create mode 100755 tests/ext4/062
> >   create mode 100644 tests/ext4/062.out
> 
> Is the only difference to 061 that we have multiple files (and not a single
> file)?

Hey John,

Yes these 2 tests are similar however 061 uses fallocate=native +
_scratch_mkfs_ext4 to test whether atomic writes on preallocated file
via multiple threads works correctly.

The 062 uses fallocate=truncate + _scratch_mkfs_sized 360MB +
'multiple jobs each writing to a different file' to ensure we are
extensively stressing the allocation logic in low space scenarios.

Regards,
ojaswin
> 
> Thanks,
> John