linux-kernel - Re: [f2fs-dev] [PATCH v2] f2fs: introduce F2FS_IOC_START_ATOMIC

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Message-ID: <CACOAw_wjcFr1fg3QRYPUyOGyo-G9D9U6=qprkPUP8PzoxPQkMQ@mail.gmail.com>
Date:   Fri, 30 Sep 2022 13:01:37 -0700
From:   Daeho Jeong <daeho43@...il.com>
To:     Chao Yu <chao@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net, kernel-team@...roid.com,
        Daeho Jeong <daehojeong@...gle.com>
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: introduce F2FS_IOC_START_ATOMIC_REPLACE

On Fri, Sep 30, 2022 at 9:04 AM Daeho Jeong <daeho43@...il.com> wrote:
>
> > >>>>
> > >>>> Hi Daeho,
> > >>>>
> > >>>> isize should be updated after tagging inode as atomic_write one?
> > >>>> otherwise f2fs_mark_inode_dirty_sync() may update isize to inode page,
> > >>>> latter checkpoint may persist that change? IIUC...
> > >>>>
> > >>>> Thanks,
> > >>>
> > >>> Hi Chao,
> > >>>
> > >>> The first patch of this patchset prevents the inode page from being
> > >>> updated as dirty for atomic file cases.
> > >>> Is there any other chances for the inode page to be marked as dirty?
> > >>
> > >> I mean:
> > >>
> > >> Thread A                                Thread B
> > >> - f2fs_ioc_start_atomic_write
> > >>    - f2fs_i_size_write(inode, 0)
> > >>     - f2fs_mark_inode_dirty_sync
> > >>                                          - checkpoint
> > >>                                           - persist inode with incorrect zero isize
> > >>
> > >>    - set_inode_flag(inode, FI_ATOMIC_FILE)
> > >>
> > >> Am I missing something?
> > >>
> > >
> > > So, f2fs_mark_inode_dirty_sync() will not work for atomic files
> > > anymore, which means it doesn't make the inode dirty.
> > > Plz, refer to the first patch of this patchset. Or I might be confused
> > > with something. :(
> >
> > I mean FI_ATOMIC_FILE was set after f2fs_i_size_write(), so inode will be set
> > as dirty.
> >
> > Thanks,
> >
>
> Oh, I was confused that f2fs_update_inode() is called in
> f2fs_mark_inode_dirty_sync().
> That is called in f2fs_write_inode(). Let me fix this.

Hmm, I think the issue was already there before my patch.
So, how about making the inode flushed and clean if the inode is
already dirty when starting atomic write?

>
> Thanks,