On Thu, Mar 29, 2018 at 10:38 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> When we create a hardlink to a metacopy upper file, first the redirect
> on that inode. Path based lookup will not work with newly created link
> and redirect will solve that issue.
>
> Also use absolute redirect as two hardlinks could be in different directores
> and relative redirect will not work.
>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
> ---
> fs/overlayfs/dir.c | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
> index 7c0a02d9f6bd..ccbe061fc4ba 100644
> --- a/fs/overlayfs/dir.c
> +++ b/fs/overlayfs/dir.c
> @@ -24,6 +24,8 @@ module_param_named(redirect_max, ovl_redirect_max, ushort, 0644);
> MODULE_PARM_DESC(ovl_redirect_max,
> "Maximum length of absolute redirect xattr value");
>
> +static int ovl_set_redirect(struct dentry *dentry, bool samedir);
> +
> int ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
> {
> int err;
> @@ -468,6 +470,9 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
> const struct cred *old_cred;
> struct cred *override_cred;
> struct dentry *parent = dentry->d_parent;
> + struct dentry *hardlink_upper;
> +
> + hardlink_upper = hardlink ? ovl_dentry_upper(hardlink) : NULL;
>
> err = ovl_copy_up(parent);
> if (err)
> @@ -502,12 +507,18 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
> put_cred(override_creds(override_cred));
> put_cred(override_cred);
>
> + if (hardlink && ovl_is_metacopy_dentry(hardlink)) {
> + err = ovl_set_redirect(hardlink, false);
Like with rename, redirect could be set much sooner in ovl_link()
if all the locks were contained within ovl_set_redirect().
I think code will be simpler overall, but can't say for sure...
> + if (err)
> + goto out_revert_creds;
> + }
> +
> if (!ovl_dentry_is_whiteout(dentry))
> err = ovl_create_upper(dentry, inode, attr,
> - hardlink);
> + hardlink_upper);
> else
> err = ovl_create_over_whiteout(dentry, inode, attr,
> - hardlink);
> + hardlink_upper);
> }
> out_revert_creds:
> revert_creds(old_cred);
> @@ -606,8 +617,7 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
> inode = d_inode(old);
> ihold(inode);
>
> - err = ovl_create_or_link(new, inode, NULL, ovl_dentry_upper(old),
> - ovl_type_origin(old));
> + err = ovl_create_or_link(new, inode, NULL, old, ovl_type_origin(old));
> if (err)
> iput(inode);
>
> --
> 2.13.6
>
> --
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