[PATCH 4.6 203/203] ovl: warn instead of error if d_type is not supported

Greg Kroah-Hartman
2016-07-25T22:02:04Z

From: Vivek Goyal <vgoyal@redhat.com>

commit e7c0b5991dd1be7b6f6dc2b54a15a0f47b64b007 upstream.

overlay needs underlying fs to support d_type. Recently I put in a
patch in to detect this condition and started failing mount if
underlying fs did not support d_type.

But this breaks existing configurations over kernel upgrade. Those who
are running docker (partially broken configuration) with xfs not
supporting d_type, are surprised that after kernel upgrade docker does
not run anymore.

https://github.com/docker/docker/issues/22937#issuecomment-229881315

So instead of erroring out, detect broken configuration and warn
about it. This should allow existing docker setups to continue
working after kernel upgrade.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 45aebeaf4f67 ("ovl: Ensure upper filesystem supports d_type")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/overlayfs/super.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1072,11 +1072,13 @@ static int ovl_fill_super(struct super_b
if (err < 0)
goto out_put_workdir;

- if (!err) {
- pr_err("overlayfs: upper fs needs to support d_type.\n");
- err = -EINVAL;
- goto out_put_workdir;
- }
+ /*
+ * We allowed this configuration and don't want to
+ * break users over kernel upgrade. So warn instead
+ * of erroring out.
+ */
+ if (!err)
+ pr_warn("overlayfs: upper fs needs to support d_type.\n");
}
}