Date:   Fri, 26 Nov 2021 21:09:36 +0800
From:   Chengguang Xu <cgxu519@mykernel.net>
Reply-To: cgxu519@mykernel.net
To:     "Jan Kara" <jack@suse.cz>
Cc:     "miklos" <miklos@szeredi.hu>, "amir73il" <amir73il@gmail.com>,
        "linux-unionfs" <linux-unionfs@vger.kernel.org>,
        "linux-fsdevel" <linux-fsdevel@vger.kernel.org>,
        "linux-kernel" <linux-kernel@vger.kernel.org>,
        "Chengguang Xu" <charliecgxu@tencent.com>,
        "ronyjin" <ronyjin@tencent.com>
Message-ID: <17d5c5d9498.134e725b210976.7805957202314611987@mykernel.net>
In-Reply-To: <20211126091430.GC13004@quack2.suse.cz>
References: <20211122030038.1938875-1-cgxu519@mykernel.net>
 <20211122030038.1938875-4-cgxu519@mykernel.net> <20211126091430.GC13004@quack2.suse.cz>
Subject: Re: [RFC PATCH V6 3/7] ovl: implement overlayfs' own ->write_inode
 operation
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 ---- =E5=9C=A8 =E6=98=9F=E6=9C=9F=E4=BA=94, 2021-11-26 17:14:30 Jan Kara <=
jack@suse.cz> =E6=92=B0=E5=86=99 ----
 > On Mon 22-11-21 11:00:34, Chengguang Xu wrote:
 > > From: Chengguang Xu <charliecgxu@tencent.com>
 > >=20
 > > Sync dirty data and meta of upper inode in overlayfs' ->write_inode()
 > > and redirty overlayfs' inode.
 > >=20
 > > Signed-off-by: Chengguang Xu <charliecgxu@tencent.com>
 >=20
 > Looks good. I'm still not 100% convinced keeping inodes dirty all the ti=
me
 > will not fire back in excessive writeback activity (e.g. flush worker wi=
ll
 > traverse the list of all dirty inodes every 30 seconds and try to write
 > them) but I guess we can start with this and if people complain, dirtine=
ss
 > handling can be improved.=20

Hi Jan,

Thanks for the review and suggestion.


Thanks,
Chengguang


 > So feel free to add:
 >=20
 > Reviewed-by: Jan Kara <jack@suse.cz>
 >=20
 >                                 Honza
 >=20
 > > ---
 > >  fs/overlayfs/super.c | 21 +++++++++++++++++++++
 > >  1 file changed, 21 insertions(+)
 > >=20
 > > diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
 > > index 18a12088a37b..12acf0ec7395 100644
 > > --- a/fs/overlayfs/super.c
 > > +++ b/fs/overlayfs/super.c
 > > @@ -15,6 +15,7 @@
 > >  #include <linux/seq_file.h>
 > >  #include <linux/posix_acl_xattr.h>
 > >  #include <linux/exportfs.h>
 > > +#include <linux/writeback.h>
 > >  #include "overlayfs.h"
 > > =20
 > >  MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
 > > @@ -406,12 +407,32 @@ static int ovl_remount(struct super_block *sb, i=
nt *flags, char *data)
 > >      return ret;
 > >  }
 > > =20
 > > +static int ovl_write_inode(struct inode *inode,
 > > +               struct writeback_control *wbc)
 > > +{
 > > +    struct ovl_fs *ofs =3D inode->i_sb->s_fs_info;
 > > +    struct inode *upper_inode =3D ovl_inode_upper(inode);
 > > +    int ret =3D 0;
 > > +
 > > +    if (!upper_inode)
 > > +        return 0;
 > > +
 > > +    if (!ovl_should_sync(ofs))
 > > +        return 0;
 > > +
 > > +    ret =3D write_inode_now(upper_inode, wbc->sync_mode =3D=3D WB_SYN=
C_ALL);
 > > +    mark_inode_dirty(inode);
 > > +
 > > +    return ret;
 > > +}
 > > +
 > >  static const struct super_operations ovl_super_operations =3D {
 > >      .alloc_inode    =3D ovl_alloc_inode,
 > >      .free_inode    =3D ovl_free_inode,
 > >      .destroy_inode    =3D ovl_destroy_inode,
 > >      .drop_inode    =3D generic_delete_inode,
 > >      .put_super    =3D ovl_put_super,
 > > +    .write_inode    =3D ovl_write_inode,
 > >      .sync_fs    =3D ovl_sync_fs,
 > >      .statfs        =3D ovl_statfs,
 > >      .show_options    =3D ovl_show_options,
 > > --=20
 > > 2.27.0
 > >=20
 > >=20
 > --=20
 > Jan Kara <jack@suse.com>
 > SUSE Labs, CR
 >=20