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From:   Daeho Jeong <daeho43@gmail.com>
Date:   Tue, 24 Nov 2020 08:03:47 +0900
Message-ID: <CACOAw_yCXj6UAgkAaggaDhPQ0B=y_6pKG54CFL4W8eWhjZA9+A@mail.gmail.com>
Subject: Re: [f2fs-dev] [PATCH 1/2] f2fs: add compress_mode mount option
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com,
        Daeho Jeong <daehojeong@google.com>
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Jaegeuk,

Got it.

Eric,

Yep.

2020=EB=85=84 11=EC=9B=94 24=EC=9D=BC (=ED=99=94) =EC=98=A4=EC=A0=84 3:46, =
Eric Biggers <ebiggers@kernel.org>=EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84=B1:
>
> On Mon, Nov 23, 2020 at 12:17:50PM +0900, Daeho Jeong wrote:
> > From: Daeho Jeong <daehojeong@google.com>
> >
> > We will add a new "compress_mode" mount option to control file
> > compression mode. This supports "fs-based" and "user-based".
> > In "fs-based" mode (default), f2fs does automatic compression on
> > the compression enabled files. In "user-based" mode, f2fs disables
> > the automaic compression and gives the user discretion of choosing
> > the target file and the timing. It means the user can do manual
> > compression/decompression on the compression enabled files using ioctls=
.
> >
> > Signed-off-by: Daeho Jeong <daehojeong@google.com>
> > ---
> >  Documentation/filesystems/f2fs.rst |  7 +++++++
> >  fs/f2fs/data.c                     | 10 +++++-----
> >  fs/f2fs/f2fs.h                     | 30 ++++++++++++++++++++++++++++++
> >  fs/f2fs/segment.c                  |  2 +-
> >  fs/f2fs/super.c                    | 23 +++++++++++++++++++++++
> >  5 files changed, 66 insertions(+), 6 deletions(-)
> >
> > diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesys=
tems/f2fs.rst
> > index b8ee761c9922..0679c53d5012 100644
> > --- a/Documentation/filesystems/f2fs.rst
> > +++ b/Documentation/filesystems/f2fs.rst
> > @@ -260,6 +260,13 @@ compress_extension=3D%s     Support adding specifi=
ed extension, so that f2fs can enab
> >                        For other files, we can still enable compression=
 via ioctl.
> >                        Note that, there is one reserved special extensi=
on '*', it
> >                        can be set to enable compression for all files.
> > +compress_mode=3D%s      Control file compression mode. This supports "=
fs-based" and
> > +                      "user-based". In "fs-based" mode (default), f2fs=
 does
> > +                      automatic compression on the compression enabled=
 files.
> > +                      In "user-based" mode, f2fs disables the automaic=
 compression
> > +                      and gives the user discretion of choosing the ta=
rget file and
> > +                      the timing. The user can do manual compression/d=
ecompression
> > +                      on the compression enabled files using ioctls.
>
> Please clarify in the documentation what it means for compression-enabled=
 files
> to not be compressed.  It is not obvious.
>
> - Eric