On Mon, Jan 08, 2018 at 11:35:09AM +0100, Miklos Szeredi wrote:
> On Wed, Nov 29, 2017 at 4:54 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> > If it makes sense to copy up only metadata during copy up, do it. This
> > is done for regular files which are not opened for WRITE and have origin
> > being saved.
> >
> > Right now ->metacopy is set to 0 always. Last patch in the series will
> > remove the hard coded statement and enable metacopy feature.
> >
> > Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
> > Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
> > ---
> > fs/overlayfs/copy_up.c | 38 +++++++++++++++++++++++++++++++-------
> > 1 file changed, 31 insertions(+), 7 deletions(-)
> >
> > diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> > index 31711edf5bde..c5804b87f3c7 100644
> > --- a/fs/overlayfs/copy_up.c
> > +++ b/fs/overlayfs/copy_up.c
> > @@ -232,6 +232,26 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
> > return err;
> > }
> >
> > +static bool ovl_need_meta_copy_up(struct dentry *dentry, umode_t mode,
> > + int flags)
> > +{
> > + struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
> > +
> > + /* TODO: Will enable metacopy in last patch of series */
> > + return false;
> > +
> > + if (!ofs->config.metacopy)
> > + return false;
> > +
> > + if (!S_ISREG(mode))
> > + return false;
> > +
> > + if (flags && ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC)))
> > + return false;
> > +
> > + return true;
> > +}
> > +
> > struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper)
> > {
> > struct ovl_fh *fh;
> > @@ -305,11 +325,8 @@ static int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
> > return PTR_ERR(fh);
> > }
> >
> > - /*
> > - * Do not fail when upper doesn't support xattrs.
> > - */
> > err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh,
> > - fh ? fh->len : 0, 0);
> > + fh ? fh->len : 0, -EOPNOTSUPP);
> > kfree(fh);
> >
> > return err;
> > @@ -326,6 +343,7 @@ struct ovl_copy_up_ctx {
> > struct qstr destname;
> > struct dentry *workdir;
> > bool tmpfile;
> > + bool metacopy;
> > };
> >
> > static int ovl_link_up(struct ovl_copy_up_ctx *c)
> > @@ -453,10 +471,14 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
> > *
> > */
> > err = ovl_set_origin(c->dentry, c->lowerpath.dentry, temp);
> > - if (err)
> > - return err;
> > + if (err) {
> > + if (err != -EOPNOTSUPP)
> > + return err;
> > + /* Upper does not support xattr. Copy up data as well */
> > + c->metacopy = false;
>
> Isn't this supposed to be checked in ovl_get_super()?
Hi Miklos,
Right. I think I was confused by code in ovl_check_setxattr().
int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
const char *name, const void *value, size_t size,
int xerr)
{
int err;
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
if (ofs->noxattr)
return xerr;
err = ovl_do_setxattr(upperdentry, name, value, size, 0);
if (err == -EOPNOTSUPP) {
pr_warn("overlayfs: cannot set %s xattr on upper\n", name);
ofs->noxattr = true;
return xerr;
}
return err;
}
ofs->noxattr will be set at mount time. Still we check for -EOPNOTSUPP
and set ofs->noxattr again. Is there a situation where this can happen.
Is it intentional. Can we get rid of this code.
To take care of this situation, I put that code. That is at mount time
xattr was fine and hence ofs->noxattr=false. But later somehow we
encountered -EOPNOTSUPP while doing ovl_set_origin(). Current code
does not fail copy up operation and I tried to retain same behavior.
That is just disable metacopy in such case but continue.
So if we don't expect all this to happen at all, then I can get rid
of this -EOPNOTSUPP check both from ovl_check_setxattr() as well
as ovl_copy_up_inode().
Vivek
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