On Thu, Mar 29, 2018 at 10:38 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> If a dentry has copy up origin, we set flag OVL_PATH_ORIGIN. So far
> this decision was easy that we had to check only for oe->numlower
> and if it is non-zero, we knew there is copy up origin. (For non-dir
> we installed origin dentry in lowerstack[0]).
>
> But we don't create ORGIN xattr for broken hardlinks (index=off). And
> with metacopy feature it is possible that we will still install
> lowerstack[0]. But that's lower data dentry of metacopy upper of broken
> hardlink and not ORIGIN XATTR is not set.
>
> So two differentiate between two cases, do not set OVL_PATH_ORIGIN if
> we have a broken hardlink.
>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
> ---
> fs/overlayfs/util.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
> index 29f7336ade88..961d65bd25c9 100644
> --- a/fs/overlayfs/util.c
> +++ b/fs/overlayfs/util.c
> @@ -117,7 +117,14 @@ enum ovl_path_type ovl_path_type(struct dentry *dentry)
> * Non-dir dentry can hold lower dentry of its copy up origin.
This comment needs updating with metacopy.
> */
> if (oe->numlower) {
> - type |= __OVL_PATH_ORIGIN;
> + /*
> + * ORIGIN is created for everyting except broken
> + * hardlinks
> + */
> + if (!(d_inode(dentry)->i_nlink > 1 &&
> + !ovl_test_flag(OVL_INDEX, d_inode(dentry))))
> + type |= __OVL_PATH_ORIGIN;
> +
I don't like relying on overlay nlink. it is not reliable.
And I think you missed the directory case.
The information you need was available during lookup
and we did not keep it (was lower verified by origin fh).
Most likely what we need to do it store OVL_ORIGIN inode flag
during lookup and then use ovl_test_flag(OVL_ORIGIN)
in place of OVL_TYPE_ORIGIN(type).
If I am not mistaken, you could set flag OVL_ORIGIN in
ovl_get_inode() IFF (upperdentry && bylower), but to be honest
the rules became so complicated that I can't say for sure.
At least I concentrated all the rules in one helper ovl_hash_bylower(),
so I hope that helps.
Thanks,
Amir.
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