On Wed, 12 Apr 2023 at 15:54, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
>
> Make the code handle the case of numlower > 1 and missing lowerdata
> dentry gracefully.
>
> Missing lowerdata dentry is an indication for lazy lookup of lowerdata
> and in that case the lowerdata_redirect path is stored in ovl_inode.
>
> Following commits will defer lookup and perform the lazy lookup on
> acccess.
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/export.c | 2 +-
> fs/overlayfs/file.c | 7 +++++++
> fs/overlayfs/inode.c | 18 ++++++++++++++----
> fs/overlayfs/super.c | 3 +++
> fs/overlayfs/util.c | 2 +-
> 5 files changed, 26 insertions(+), 6 deletions(-)
>
> diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
> index 9951c504fb8d..2498fa8311e3 100644
> --- a/fs/overlayfs/export.c
> +++ b/fs/overlayfs/export.c
> @@ -343,7 +343,7 @@ static struct dentry *ovl_dentry_real_at(struct dentry *dentry, int idx)
> if (!idx)
> return ovl_dentry_upper(dentry);
>
> - for (i = 0; i < ovl_numlower(oe); i++) {
> + for (i = 0; i < ovl_numlower(oe) && lowerstack[i].layer; i++) {
Metacopy and NFS export are mutually exclusive, so this doesn't make sense.
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 3484f39a8f27..ef78abc21998 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
ovl_d_real() calls ovl_dentry_lowerdata(). If triggered from
file_dentry() it should be okay, since that is done on an open file
(lazy lookup already perfromed). But it can also be called from
d_real_inode(), the only caller of which is trace_uprobe. Is this
going to be okay?
In any case a comment is needed at least.
Thanks,
Miklos
