On Mon, Jan 08, 2018 at 01:18:05PM +0200, Amir Goldstein wrote:
> On Mon, Jan 8, 2018 at 12:16 PM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
> > On Wed, Nov 29, 2017 at 4:54 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> >> Right now my understanding is that origin xattr is created for all copied
> >> up files if index=on. And if index=off, then we create it for all type
> >> of files except hardlinks (nlink != 1).
> >>
> >> With metadata only copy up, I will still require origin xattr to copy up
> >> data later, so create it even for hardlinks even with index=off.
> >
> > This doesn't look right. Without index we can't do hard links
> > properly, doing metacopy in that case will complicate the situation
> > further and can result in weirdness (e.g. two files that have
> > different attributes but same inode number).
>
> But ovl_getattr() does not return lower st_ino for non-indexed
> upper with lowerstat.nlink != 1.
Hi Miklos,
Thanks Amir for ovl_gettr() behavior.
So there are 3 ways to deal with this.
A. Keep ORIGIN but do not report lower inode number if index=off, instead
report upper inode number.
B. Do not create ORIGIN to begin with if index=off and disable metacopy
for hardlinked files.
C. Make metacopy dependent on index=on.
currently I take approach A. That is always create ORIGIN xattr but
do not use it when we think this might be a problem. (Like for the
cases of broken hardlinks).
If you still don't like this approach, please let me know and I will
change it. And switch to say approach B?
Thanks
Vivek
>
> >
> > So I think we should either require index for metacopy, or disable
> > metacopy only for nlink != 1 files, but otherwise enable it even in
> > case of index=off.
> >
>
> IIRC, commit 6eaf011144af ("ovl: fix EIO from lookup of non-indexed
> upper") was a result of a conversation about this very patch and this
> very issue. After this commit, the situation of non-indexed upper with
> origin is handled correctly on lookup (hash by upper inode) and I
> couldn't find a reason why setting origin for metacopy with index=off
> is wrong. Or anything that could go wrong for setting origin on every
> copy up.
>
> Am I missing something?
>
> Amir.
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