---- 在 星期五, 2021-04-09 21:45:28 Miklos Szeredi <miklos@xxxxxxxxxx> 撰写 ----
> On Fri, Nov 13, 2020 at 7:57 AM Chengguang Xu <cgxu519@xxxxxxxxxxxx> wrote:
> >
> > Mark overlayfs' inode dirty on modification so that
> > we can recognize target inodes during syncfs.
> >
> > Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxxxx>
> > ---
> > fs/overlayfs/inode.c | 1 +
> > fs/overlayfs/overlayfs.h | 4 ++++
> > fs/overlayfs/util.c | 14 ++++++++++++++
> > 3 files changed, 19 insertions(+)
> >
> > diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
> > index 8cfa75e86f56..342693657ab0 100644
> > --- a/fs/overlayfs/inode.c
> > +++ b/fs/overlayfs/inode.c
> > @@ -468,6 +468,7 @@ int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags)
> > if (upperpath.dentry) {
> > touch_atime(&upperpath);
> > inode->i_atime = d_inode(upperpath.dentry)->i_atime;
> > + ovl_mark_inode_dirty(inode);
> > }
> > }
> > return 0;
> > diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> > index f8880aa2ba0e..eaf1d5b05d8e 100644
> > --- a/fs/overlayfs/overlayfs.h
> > +++ b/fs/overlayfs/overlayfs.h
> > @@ -247,6 +247,7 @@ static inline bool ovl_open_flags_need_copy_up(int flags)
> > }
> >
> > /* util.c */
> > +void ovl_mark_inode_dirty(struct inode *inode);
> > int ovl_want_write(struct dentry *dentry);
> > void ovl_drop_write(struct dentry *dentry);
> > struct dentry *ovl_workdir(struct dentry *dentry);
> > @@ -472,6 +473,9 @@ static inline void ovl_copyattr(struct inode *from, struct inode *to)
> > to->i_mtime = from->i_mtime;
> > to->i_ctime = from->i_ctime;
> > i_size_write(to, i_size_read(from));
> > +
> > + if (ovl_inode_upper(to) && from->i_state & I_DIRTY_ALL)
> > + ovl_mark_inode_dirty(to);
> > }
>
> Okay, ovl_copyattr() certainly seems a good place to copy dirtyness as well.
>
> What I'm fearing is that it does not cover all the places where
> underlying inode can be dirtied. This really needs an audit of all
> filesystem modifying operations.
You are right. Let me fix it in next version.
Thanks,
Chengguang
> >
> > static inline void ovl_copyflags(struct inode *from, struct inode *to)
> > diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
> > index 23f475627d07..a6f59df744ae 100644
> > --- a/fs/overlayfs/util.c
> > +++ b/fs/overlayfs/util.c
> > @@ -950,3 +950,17 @@ char *ovl_get_redirect_xattr(struct ovl_fs *ofs, struct dentry *dentry,
> > kfree(buf);
> > return ERR_PTR(res);
> > }
> > +
> > +/*
> > + * We intentionally add I_DIRTY_SYNC flag regardless dirty flag
> > + * of upper inode so that we have chance to invoke ->write_inode
> > + * to re-dirty overlayfs' inode during writeback process.
> > + */
> > +void ovl_mark_inode_dirty(struct inode *inode)
> > +{
> > + struct inode *upper = ovl_inode_upper(inode);
> > + unsigned long iflag = I_DIRTY_SYNC;
> > +
> > + iflag |= upper->i_state & I_DIRTY_ALL;
> > + __mark_inode_dirty(inode, iflag);
> > +}
> > --
> > 2.26.2
> >
> >
>
