linux-kernel - Re: [0/4] overlayfs: Adjustments for ovl_fill

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Date: Wed, 10 Jan 2024 15:45:37 +0200
From: Amir Goldstein <amir73il@...il.com>
To: Markus Elfring <Markus.Elfring@....de>
Cc: linux-unionfs@...r.kernel.org, kernel-janitors@...r.kernel.org, 
	Miklos Szeredi <miklos@...redi.hu>, cocci@...ia.fr, LKML <linux-kernel@...r.kernel.org>, 
	Christian Brauner <brauner@...nel.org>
Subject: Re: [0/4] overlayfs: Adjustments for ovl_fill_super()

On Wed, Jan 10, 2024 at 3:33 PM Markus Elfring <Markus.Elfring@....de> wrote:
>
> >>>> See also:
> >>>> https://lore.kernel.org/cocci/87b65f8e-abde-2aff-4da8-df6e0b464677@web.de/
> >>>> https://sympa.inria.fr/sympa/arc/cocci/2023-03/msg00115.html
> >>>
> >>> I will queue cleanup patches 1-2,
> >>
> >> Thanks for this positive feedback.
> >
> > Sorry, these patches do not apply to master branch and patch 1
> > is no longer correct in master branch and the new mount api changes.
>
> Do you want that I adapt the linked development ideas to the current situation
> a bit more?
>

No thanks.
Patch 1 just doesn't work for the new mount api.

>
> >>>                                   but I do not like patches 3/4 and 4/4.
> >>> I do not think that they make the code better to read or maintain.
> >>
> >> I would appreciate if the details for such change reluctance can be clarified better.
> >
> > patch 3:
> > I much rather a single error handling label that takes care of
> > all the cleanups - it is harder to make mistakes and jump to
> > the wrong label when adding new error conditions.
>
> There are different coding style preferences involved.
>
> See also:
> https://wiki.sei.cmu.edu/confluence/display/c/MEM12-C.+Consider+using+a+goto+chain+when+leaving+a+function+on+error+when+using+and+releasing+resources
>

As long as coding styles are not mandatory
I prefer what we have right now.

>
> > patch 4:
> > Overlayfs uses this coding style all over the place
> >
> >   err = -ENOMEM;
> >   ofs->creator_cred = cred = prepare_creds();
> >   if (!cred)
> >       goto out_free_ofs;
> >
> > I don't see the benefit in making err = -ENOMEM conditional.
> > I don't see the style after your patch as clearly better than before.
>
> Can it be nicer to set error codes only in exceptional data processing situations?
>

It's a matter of taste.
I'll stay with what we have.

Thanks,
Amir.