Hi,
to be very understandable for me, it is not only slot N which is COWed
but the *WHOLE* 1024 entries array (metadnode structure) which is COWed
because COW applies only on blocks pointed by block pointer structure am
i right???
Cheers
C Rouhassia
"Chen Zheng" <nkchenz at gmail.com>
14/11/08 03:37
To
Cyril ROUHASSIA/fr/socgen at socgen
cc
zfs-code at opensolaris.org
Subject
Re: [zfs-code] How does zfs COW deal with '..' in brother directory? [C1]
2008/11/13 Cyril ROUHASSIA <cyril.rouhassia at sgcib.com>:
>
> According
>
> 2008/11/12 Matthew Ahrens <Matthew.Ahrens at sun.com>:
>
>
>
> Yes, understood, the old A and the new A just have the same object
> number N: first alloc a new block, write new A, then modify objset's
> slot N to let it point the new A, done
>
>
> But modification of slot N cannot be done straighforward , it has also
to
> comply COW rules, I mean from my understanding , a new metadnode array
is
> created for that objectset identical to the former one except for slot N
> (where object that had been modified lie ) . And this process goes up to
the
> uberblock , Am I right??
>
Yes, you need to copy the block first which holds slot N, modify it
and any necessary upper blocks in the object number index tree rooted
at blkptr of objset dnode, then keep going up until you get the
uberblock.
--
args are passed by ref, but bindings are local, variables are in fact
just a symbol referencing an object
*************************************************************************
This message and any attachments (the "message") are confidential, intended
solely for the addressee(s), and may contain legally privileged information.
Any unauthorised use or dissemination is prohibited. E-mails are susceptible to
alteration.
Neither SOCIETE GENERALE nor any of its subsidiaries or affiliates shall be
liable for the message if altered, changed or
falsified.
************
Ce message et toutes les pieces jointes (ci-apres le "message") sont
confidentiels et susceptibles de contenir des informations couvertes
par le secret professionnel.
Ce message est etabli a l'intention exclusive de ses destinataires. Toute
utilisation ou diffusion non autorisee est interdite.
Tout message electronique est susceptible d'alteration.
La SOCIETE GENERALE et ses filiales declinent toute responsabilite au titre de
ce message s'il a ete altere, deforme ou falsifie.
*************************************************************************
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://mail.opensolaris.org/pipermail/zfs-code/attachments/20081114/d12eac0d/attachment.html>
