On Thu, Oct 12, 2017 at 6:03 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> Commit fbaf94ee3cd5 ("ovl: don't set origin on broken lower hardlink")
> attempt to avoid the condition of non-indexed upper inode with lower
> hardlink as origin. If this condition is found, lookup returns EIO.
>
> The protection of commit mentioned above does not cover the case of lower
> that is not a hardlink when it is copied up (with either index=off/on)
> and then lower is hardlinked while overlay is offline.
>
> Changes to lower layer while overlayfs is offline should not result in
> unexpected behavior, so a permanent EIO error after creating a link in
> lower layer should not be considered as correct behavior.
>
> This fix replaces EIO error with a warning in cases where upper has
> origin but no index is found, or index is found that does not match upper
> inode. In those cases, lookup will not fail and the returned overlay
> inode will be hashed by upper inode instead of by lower origin inode.
>
> Fixes: 359f392ca53e ("ovl: lookup index entry for copy up origin")
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.13
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
>
> Miklos,
>
> Following a discussion with Vivek about metacopy feature and the option
> of setting ORIGIN for non-indexed lower hardlinks on copy up, I came to
> a conclusion that the current EIO behavior is not quite tollerant to lower
> changes as one would hope and that it should be fixed in stable kernels.
Okay, but I started wondering if we really should be writing warnings
to the kernel log if this situation is considered normal.
Is it worth warning about these?
Thanks,
Miklos