linux-kernel - Re: [PATCH V3] ovl: fix mount fail because the upper doesn't have space

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Date:   Wed, 2 Aug 2023 10:11:41 +0800
From:   yunlong xing <yunlongxing23@...il.com>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     Yunlong Xing <yunlong.xing@...soc.com>, amir73il@...il.com,
        linux-unionfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        zhiguo.niu@...soc.com, hongyu.jin@...soc.com
Subject: Re: [PATCH V3] ovl: fix mount fail because the upper doesn't have space

On Wed, Aug 2, 2023 at 1:43 AM Miklos Szeredi <miklos@...redi.hu> wrote:
>
> On Thu, 20 Jul 2023 at 11:15, Yunlong Xing <yunlong.xing@...soc.com> wrote:
> >
> > The current ovlfs mount flow:
> >
> > ovl_fill_super
> >  |_ovl_get_workdir
> >     |_ovl_make_workdir
> >        |_ovl_check_rename_whiteout
> >
> > In ovl_check_rename_whiteout(), a new file is attempted to create.But if
> > the upper doesn't have space to do this, it will return error -ENOSPC,
> > causing the mount fail. It means that if the upper is full, the overlayfs
> > cannot be mounted. It is not reasonable, so this patch will omit this error
> > and continue mount flow.
>
> Wouldn't mounting without upper (two or more lower layers) work in this case?
Sorry miklos， I don't understand what you mean.

The case is in  "ovl_make_workdir" flow,  "ovl_check_rename_whiteout"
will attempt to
create a temp file. The "upper" partition（e.g scratch partition）is
completely full，the
create will fail. So, the overlay mounting will failed


>
> Thanks,
> Miklos