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From:   zhou dan <zhuqiandann@gmail.com>
Date:   Wed, 11 Jan 2023 10:47:17 +0800
Message-ID: <CAHDnOD4wNVc_XKBi2qyi3oNRENidf4mSYCCTYYxCofy=iqc=Zg@mail.gmail.com>
Subject: Re: [PATCH] f2fs: don't set FI_COMPRESS_RELEASED if file is not compressed
To:     Jaegeuk Kim <jaegeuk@kernel.org>, chao@kernel.org
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, zhoudan8@xiaomi.com
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On Android S, after the app is installed, it will judge whether the file
is allowed to be compressed and release it. In the case of compress_mode=3D=
user,
the file is not compressed at this point, causing EVNAL to be returned on
subsequent executions to release.
In the method 'isCompressionAllowed', there is also such a notice:"NOTE:
The return value does not mean if the given file, or any other file on
the same file system, is actually compressed. It merely determines whether
not files <em>may</em> be compressed."

On Wed, Jan 4, 2023 at 10:29 AM Jaegeuk Kim <jaegeuk@kernel.org> wrote:
>
> On 12/16, zhou dan wrote:
> > Hi, about this patch, I haven't received any reply recently.
> > Maybe you have some new ideas to solve this problem?
>
> Could you please describe the exact flow that you're suffering from?
>
> >
> >
> > zhoudan <zhuqiandann@gmail.com> =E4=BA=8E2022=E5=B9=B412=E6=9C=8813=E6=
=97=A5=E5=91=A8=E4=BA=8C 10:21=E5=86=99=E9=81=93=EF=BC=9A
> > >
> > > However, 'f2fs_compressed_file()' only determines whether the file ca=
n
> > > be compressed, not whether the file has been compressed. As far as I
> > > know, when compress_mode is user, files marked FI_COMPRESSED_FILE
> > > will be compressed only after 'f2fs_ioc_compress_file()' is called.
> > > On Mon, Dec 12, 2022 at 03:05:08PM -0800, Jaegeuk Kim wrote:
> > > > On 12/12, zhoudan wrote:
> > > > > Maybe I'm not describing it clearly enough, but I think there is
> > > > > something wrong with the logic here.The 'f2fs_release_compress_bl=
ocks'
> > > > > method does not determine if the file is compressed, but simply a=
dds
> > > > > the FI_COMPRESS_RELEASED flag.
> > > >
> > > > I firstly lost your point since f2fs_release_compress_blocks() chec=
ked
> > > > f2fs_compressed_file().
> > > >
> > > > > In particular, in the current Android system, when the applicatio=
n is
> > > > > installed, the release interface is called by default to release =
the
> > > > > storage marked as compressed,  without checking whether the file =
is
> > > > > actually compressed. In this case, when compress_mode is set to u=
ser,
> > > > > calling the compress interface returns ENVAL and the file cannot =
be
> > > > > compressed.
> > > > > So I think the implementation of release needs to be modified, an=
d
> > > > > only set FI_COMPRESS_RELEASED when it's really compressed and the
> > > > > storage is released.
> > > > >
> > > > > On Fri, Dec 09, 2022 at 12:19:44PM -0800, Jaegeuk Kim wrote:
> > > > > > On 12/08, zhoudan8 wrote:
> > > > > > > In compress_mode=3Duser, f2fs_release_compress_blocks()
> > > > > > >  does not verify whether it has been compressed and
> > > > > > >  sets FI_COMPRESS_RELEASED directly. which will lead to
> > > > > > > return -EINVAL after calling compress.
> > > > > > > To fix it,let's do not set FI_COMPRESS_RELEASED if file
> > > > > > > is not compressed.
> > > > > >
> > > > > > Do you mean you want to avoid EINVAL on a file having FI_COMPRE=
SS_RELEASED
> > > > > > with zero i_compr_blokcs?
> > > > > >
> > > > > > I think the current logic is giving the error on a released fil=
e already.
> > > > > >
> > > > > > >
> > > > > > > Signed-off-by: zhoudan8 <zhoudan8@xiaomi.com>
> > > > > > > ---
> > > > > > >  fs/f2fs/file.c | 3 +--
> > > > > > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > > > > > >
> > > > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > > > > > > index 82cda1258227..f32910077df6 100644
> > > > > > > --- a/fs/f2fs/file.c
> > > > > > > +++ b/fs/f2fs/file.c
> > > > > > > @@ -3451,14 +3451,13 @@ static int f2fs_release_compress_bloc=
ks(struct file *filp, unsigned long arg)
> > > > > > >         ret =3D filemap_write_and_wait_range(inode->i_mapping=
, 0, LLONG_MAX);
> > > > > > >         if (ret)
> > > > > > >                 goto out;
> > > > > > > -
> > > > > > > -       set_inode_flag(inode, FI_COMPRESS_RELEASED);
> > > > > > >         inode->i_ctime =3D current_time(inode);
> > > > > > >         f2fs_mark_inode_dirty_sync(inode, true);
> > > > > > >
> > > > > > >         if (!atomic_read(&F2FS_I(inode)->i_compr_blocks))
> > > > > > >                 goto out;
> > > > > > >
> > > > > > > +       set_inode_flag(inode, FI_COMPRESS_RELEASED);
> > > > > > >         f2fs_down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> > > > > > >         filemap_invalidate_lock(inode->i_mapping);
> > > > > > >
> > > > > > > --
> > > > > > > 2.38.1