Re: [regressions] ntfs3: empty file on update without forced cache drop

[Konstantin Komarov]

On 21.01.2024 12:14, Thorsten Leemhuis wrote:
> On 05.12.23 13:49, Linux regression tracking (Thorsten Leemhuis) wrote:
> > [adding a bunch of people and two lists to the recipients, as Konstantin
> > apparently hasn't sent any mail to any lists archived on lore for ~six
> > weeks; maybe someone knows what's up or is willing to help out]
> [CCing Linus now as well]
>
> JFYI for the VFS maintainers and everyone else who might care:
>
> Konstantin afaics still did not look into below regression. Neither did
> anyone else afaics.
>
> But Konstantin is still around, as he recently showed up to post a patch
> for review:
> https://lore.kernel.org/all/667a5bc4-8cb5-47ce-a7f1-749479b25bec@xxxxxxxxxxxxxxxxxxxx/
>
> I replied to it in the hope of catch his attention and make him look at
> this regression, but that did not work out.
>
> So it seems we sadly are kinda stuck here. :-/
>
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
>
> > On 27.11.23 07:18, Thorsten Leemhuis wrote:
> > > Hi, Thorsten here, the Linux kernel's regression tracker.
> > >
> > > Konstantin, I noticed a regression report in bugzilla.kernel.org.
> > > Apparently it's cause by a change of yours.
> > >
> > > As many (most?) kernel developers don't keep an eye on bugzilla, I
> > > decided to forward it by mail. Note, you have to use bugzilla to reach
> > > the reporter, as I sadly[1] can not CCed them in mails like this.
> > >
> > > Quoting from https://bugzilla.kernel.org/show_bug.cgi?id=218180 :
> > Konstantin, are you still around? Would be great if you could look into
> > this regression, as this sounds somewhat worrying.
> >
> > > > The problem I am facing is the following:
> > > > 1. I mount an NTFS partition via NTFS3
> > > > 2. I create a file
> > > > 3. I write to the file
> > > > 4. The file is empty
> > > > 5. I remount the partition
> > > > 6. The file has the changes I made before the remount
> > > >
> > > > I can avoid the remount by doing:
> > > > sudo sysctl vm.drop_caches=3
> > > See the ticket for more details. It according to the report happens
> > > still happens with 6.7-rc2, but not with 6.1.y. The reporter bisected
> > > the problem to ad26a9c84510af ("fs/ntfs3: Fixing wrong logic in
> > > attr_set_size and ntfs_fallocate") [v6.2-rc1].
> > >
> > > Side note: while briefly checking lore for existing problems caused by
> > > that change I noticed two syzbot reports about it that apparently nobody
> > > looked into:
> > >
> > > https://lore.kernel.org/all/000000000000bdf37505f1a7fc09@xxxxxxxxxx/
> > > https://lore.kernel.org/all/00000000000062174006016bc386@xxxxxxxxxx/
> > > [...]
> --
> Everything you wanna know about Linux kernel regression tracking:
> https://linux-regtracking.leemhuis.info/about/#tldr
> If I did something stupid, please tell me, as explained on that page.
>
> #regzbot poke
Hello Thorsten,

I apologize for the horrible delay in responding to the bug. I was able 
to reproduce it in a scenario involving a compressed file. The patch 
will be ready within the next few days (the response in Bugzilla will 
also follow).

Best regards,
Konstantin