On Wed, Oct 18, 2017 at 08:06:19AM +0300, Amir Goldstein wrote:
> On Wed, Oct 18, 2017 at 12:05 AM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> > During lookup, check for presence of OVL_XATTR_METACOPY and if present,
> > set OVL_METACOPY bit in flags.
> >
> > Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
> > ---
> > fs/overlayfs/namei.c | 40 ++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 40 insertions(+)
> >
> > diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
> > index 88ff1daeb3d7..d32da041f4bf 100644
> > --- a/fs/overlayfs/namei.c
> > +++ b/fs/overlayfs/namei.c
> > @@ -26,6 +26,24 @@ struct ovl_lookup_data {
> > char *redirect;
> > };
> >
> > +/* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
> > +static int ovl_check_metacopy(struct dentry *dentry)
> > +{
> > + int res;
> > +
> > + res = vfs_getxattr(dentry, OVL_XATTR_METACOPY, NULL, 0);
> > + if (res < 0) {
> > + if (res == -ENODATA || res == -EOPNOTSUPP)
> > + return 0;
> > + goto out;
> > + }
> > +
> > + return 1;
> > +out:
> > + pr_warn_ratelimited("overlayfs: failed to get metacopy (%i)\n", res);
> > + return res;
> > +}
> > +
> > static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
> > size_t prelen, const char *post)
> > {
> > @@ -594,6 +612,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
> > struct dentry *this;
> > unsigned int i;
> > int err;
> > + bool metacopy = false;
> > struct ovl_lookup_data d = {
> > .name = dentry->d_name,
> > .is_dir = false,
> > @@ -634,6 +653,12 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
> > roe->numlower, &stack, &ctr);
> > if (err)
> > goto out;
> > +
> > + err = ovl_check_metacopy(upperdentry);
> > + if (err < 0)
> > + goto out;
> > + if (err == 1)
> > + metacopy = true;
>
> Miklos seems to prefer
> metacopy = err;
> if (err < 0)
> goto out;
>
> Not sure if it is just coding style or for better branch prediction code.
Ok, will change.
>
>
> > }
> >
> > if (d.redirect) {
> > @@ -719,6 +744,19 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
> > OVL_I(inode)->redirect = upperredirect;
> > if (index)
> > ovl_set_flag(OVL_INDEX, inode);
> > +
> > + if (metacopy) {
> > + /*
> > + * Found an upper with metacopy set but at the same
> > + * time there is no lower dentry. Something is not
> > + * right.
> > + */
> > + if (!ctr) {
>
> Please move this test up right after ovl_check_metacopy()
> There is no reason to wait as ctr is not going to grow for non-dir after
> that point.
Makes sense. Will do.
>
> > + err = -ESTALE;
> > + goto out_put_inode;
> > + }
> > + ovl_set_flag(OVL_METACOPY, inode);
> > + }
> > }
> >
> > revert_creds(old_cred);
> > @@ -729,6 +767,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
> >
> > return NULL;
> >
> > +out_put_inode:
> > + iput(inode);
>
> And than new goto label becomes obsolete
Sounds good.
Vivek
>
> > out_free_oe:
> > dentry->d_fsdata = NULL;
> > kfree(oe);
> > --
> > 2.13.5
> >
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