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From:   "Namjae Jeon" <namjae.jeon@samsung.com>
To:     "'Hyunchul Lee'" <hyc.lee@gmail.com>
Cc:     <linux-fsdevel@vger.kernel.org>,
        "'LKML'" <linux-kernel@vger.kernel.org>,
        "'Sungjong Seo'" <sj1557.seo@samsung.com>
In-Reply-To: <CANFS6bYm_yCLG2kKfn8wYBJ4bO+Z+2+R-gHQ6dTwiP9Ut3yy5g@mail.gmail.com>
Subject: RE: [PATCH 1/2] exfat: call sync_filesystem for read-only remount
Date:   Mon, 15 Jun 2020 11:56:05 +0900
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> Hi Namjae,
>=20
> 2020=EB=85=84=206=EC=9B=94=2015=EC=9D=BC=20(=EC=9B=94)=20=EC=98=A4=EC=A0=
=84=209:14,=20Namjae=20Jeon=20<namjae.jeon=40samsung.com>=EB=8B=98=EC=9D=B4=
=20=EC=9E=91=EC=84=B1:=0D=0A>=20>=0D=0A>=20>=20Hi=20Hyunchul,=0D=0A>=20>=20=
>=20We=20need=20to=20commit=20dirty=20metadata=20and=20pages=20to=20disk=20=
before=20remounting=20exfat=20as=20read-only.=0D=0A>=20>=20>=0D=0A>=20>=20>=
=20This=20fixes=20a=20failure=20in=20xfstests=20generic/452=0D=0A>=20>=20Co=
uld=20you=20please=20elaborate=20more=20the=20reason=20why=20generic/452=20=
in=20xfstests=20failed=20?=0D=0A>=20=0D=0A>=20xfstests=20generic/452=20does=
=20the=20following.=0D=0A>=20cp=20/bin/ls=20<exfat>/=0D=0A>=20mount=20-o=20=
remount,ro=20<exfat>=0D=0A>=20=0D=0A>=20the=20<exfat>/ls=20file=20is=20corr=
upted,=20because=20while=20exfat=20is=20remounted=20as=20read-only,=20exfat=
=20doesn't=20have=20a=0D=0A>=20chance=20to=20commit=20metadata=20and=20vfs=
=20invalidates=20page=20caches=20in=20a=20block=20device.=0D=0AGot=20it.=0D=
=0A>=20=0D=0A>=20I=20will=20put=20this=20explanation=20in=20a=20commit=20me=
ssage.=0D=0AGood.=0D=0A>=20=0D=0A>=20>=20>=0D=0A>=20>=20>=20Signed-off-by:=
=20Hyunchul=20Lee=20<hyc.lee=40gmail.com>=0D=0A>=20>=20>=20---=0D=0A>=20>=
=20>=20=20fs/exfat/super.c=20=7C=2019=20+++++++++++++++++++=0D=0A>=20>=20>=
=20=201=20file=20changed,=2019=20insertions(+)=0D=0A>=20>=20>=0D=0A>=20>=20=
>=20diff=20--git=20a/fs/exfat/super.c=20b/fs/exfat/super.c=20index=0D=0A>=
=20>=20>=20e650e65536f8..61c6cf240c19=20100644=0D=0A>=20>=20>=20---=20a/fs/=
exfat/super.c=0D=0A>=20>=20>=20+++=20b/fs/exfat/super.c=0D=0A>=20>=20>=20=
=40=40=20-693,10=20+693,29=20=40=40=20static=20void=20exfat_free(struct=20f=
s_context=20*fc)=0D=0A>=20>=20>=20=20=20=20=20=20=20=7D=0D=0A>=20>=20>=20=
=20=7D=0D=0A>=20>=20>=0D=0A>=20>=20>=20+static=20int=20exfat_reconfigure(st=
ruct=20fs_context=20*fc)=20=7B=0D=0A>=20>=20>=20+=20=20=20=20=20struct=20su=
per_block=20*sb=20=3D=20fc->root->d_sb;=0D=0A>=20>=20>=20+=20=20=20=20=20in=
t=20ret;=0D=0A>=20>=20int=20ret=20=3D=200;=0D=0A>=20>=20>=20+=20=20=20=20=
=20bool=20new_rdonly;=0D=0A>=20>=20>=20+=0D=0A>=20>=20>=20+=20=20=20=20=20n=
ew_rdonly=20=3D=20fc->sb_flags=20&=20SB_RDONLY;=0D=0A>=20>=20>=20+=20=20=20=
=20=20if=20(new_rdonly=20=21=3D=20sb_rdonly(sb))=20=7B=0D=0A>=20>=20If=20yo=
u=20modify=20it=20like=20this,=20would=20not=20we=20need=20new_rdonly?=0D=
=0A>=20>=20=20=20=20=20=20=20=20=20if=20(fc->sb_flags=20&=20SB_RDONLY=20&&=
=20=21sb_rdonly(sb))=0D=0A>=20>=0D=0A>=20This=20condition=20means=20that=20=
mount=20options=20are=20changed=20from=20=22rw=22=20to=20=22ro=22,=20or=20=
=22ro=22=20to=20=22rw=22.=0D=0A>=20=0D=0A>=20>=20>=20+=20=20=20=20=20=20=20=
=20=20=20=20=20=20if=20(new_rdonly)=20=7B=0D=0A>=20=0D=0A>=20And=20this=20c=
ondition=20means=20these=20options=20are=20changed=20from=20=22rw=22=20to=
=20=22ro=22.=0D=0A>=20It=20seems=20better=20to=20change=20two=20conditions=
=20to=20the=20one=20you=20suggested,=20or=20remove=20those.=20because=0D=0A=
>=20sync_filesystem=20returns=200=20when=20the=20filesystem=20is=20mounted=
=20as=20read-only.=0D=0AThe=20latter=20would=20be=20fine.=0D=0A>=20=0D=0A>=
=20>=20>=20+=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
/*=20volume=20flag=20will=20be=20updated=20in=20exfat_sync_fs=20*/=0D=0A>=
=20>=20>=20+=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
ret=20=3D=20sync_filesystem(sb);=0D=0A>=20>=20>=20+=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20if=20(ret=20<=200)=0D=0A>=20>=20>=20=
+=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20return=20ret;=0D=0A>=20>=20I=20think=20that=20this=20ret=20c=
heck=20can=20be=20removed=20by=20using=20return=20ret;=20below=20?=0D=0A>=
=20=0D=0A>=20Okay,=20I=20will=20apply=20this.=0D=0A>=20Thank=20you=20for=20=
your=20comments=21=0D=0AThanks=20for=20your=20patch=21=0D=0A>=20=0D=0A>=20=
=0D=0A>=20>=20>=20+=20=20=20=20=20=20=20=20=20=20=20=20=20=7D=0D=0A>=20>=20=
>=20+=20=20=20=20=20=7D=0D=0A>=20>=20>=20+=20=20=20=20=20return=200;=0D=0A>=
=20>=20return=20ret;=0D=0A>=20>=20>=20+=7D=0D=0A>=20>=20>=20+=0D=0A>=20>=20=
>=20=20static=20const=20struct=20fs_context_operations=20exfat_context_ops=
=20=3D=20=7B=0D=0A>=20>=20>=20=20=20=20=20=20=20.parse_param=20=20=20=20=3D=
=20exfat_parse_param,=0D=0A>=20>=20>=20=20=20=20=20=20=20.get_tree=20=20=20=
=20=20=20=20=3D=20exfat_get_tree,=0D=0A>=20>=20>=20=20=20=20=20=20=20.free=
=20=20=20=20=20=20=20=20=20=20=20=3D=20exfat_free,=0D=0A>=20>=20>=20+=20=20=
=20=20=20.reconfigure=20=20=20=20=3D=20exfat_reconfigure,=0D=0A>=20>=20>=20=
=20=7D;=0D=0A>=20>=20>=0D=0A>=20>=20>=20=20static=20int=20exfat_init_fs_con=
text(struct=20fs_context=20*fc)=0D=0A>=20>=20>=20--=0D=0A>=20>=20>=202.17.1=
=0D=0A>=20>=0D=0A>=20>=0D=0A=0D=0A