Hi, I've sent a patch which is trying to acheive what Amir had
suggested. Please take a look:
[PATCH] ovl: introduce new "index=nouuid" option for inodes index feature
On 9/23/20 5:10 AM, Amir Goldstein wrote:
On Wed, Sep 23, 2020 at 12:25 AM Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
On Tue, Sep 22, 2020 at 02:15:55PM +0300, Amir Goldstein wrote:
[..]
No objection, but if I were you I wouldn't bother re-writing new ovl_fh.
If you know you don't care about matching uuid in the first place,
it is better to add a mount option to overlayfs 'index=nouuid' to relax the
uuid comparison check for ovl_fh.
So is it possible that somebody uses "nouuid" and then a different file
got same file handle (as stored in upper). I think that's one issue
you were worried about while addressing squashfs fix. IIRC, Miklos had said
with-in same filesystem it will not happen and across filesystems
sb->uuid check will ensure this does not happen. IOW, "nouuid" will
open the possibility of upper file handle matching a different file?
Well, to be accurate, I did write that when cloning a base lower fs (like with
dm-thinp) the problem reported with re-created lower squashfs still exists but
that it is a corner case [1].
But what I suggested is that index=nouuid will only be allowed for all layers
on the same fs, where this is not a problem.
Thanks,
Amir.
[1] https://lore.kernel.org/linux-unionfs/CAOQ4uxiq7hkaew4LoFZkf4R73iH_pU7OHOriycLCnnywtA0O0w@xxxxxxxxxxxxxx/
--
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.
