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From: Miklos Szeredi <miklos@szeredi.hu>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Chengguang Xu <cgxu519@mykernel.net>,
	overlayfs <linux-unionfs@vger.kernel.org>
Subject: Re: [PATCH] ovl: consistent behavior for immutable/append-only inodes
Date: Fri, 11 Jun 2021 09:55:20 +0200	[thread overview]
Message-ID: <CAJfpeguateThdqWPdF1P-OFuxYdrdgtz7dj-=ewBft-k2gDSdQ@mail.gmail.com> (raw)
In-Reply-To: <CAOQ4uxiHyd4iRxgtDGorNK8fzBJgViUXxgAtS7nfAdHMQeiAew@mail.gmail.com>

On Fri, 11 Jun 2021 at 09:31, Amir Goldstein <amir73il@gmail.com> wrote:

>
> Taking a step back.
>
> The main problem this is trying to solve is losing persistent inode flags
> on copy-up.
>
> If this was just NOATIME and SYNC the solution would have been
> simple - copy up the flags along with other metadata we copy up.
>
> We wouldn't even need to limit ourselves to the 4 vfs inode flags
> in ovl_copyflags(). We could add the the copied up flags more
> fs specific flags that we know to be safe and rational to copy
> such as NOCOW, NODUMP and DIRSYNC.
>
> The secondary problem is that copying IMMUTABLE/APPEND
> to upper inode on copy up is not an option, so the solution is to
> store those properties in an xattr.
>
> I think we should split the solution to the primary and secondary
> problems and avoid an over-designed generic future extendable
> xflags xattr feature.
>
> So I am leaning towards a more focused solution for
> IMMUTABLE/APPEND in the form of either two boolean
> xattr overlay.{immutable,appendonly} or one single bytes
> xattr overlay.protected.

Makes sense.

Not sure how you'd make it single byte and user friendly at the same
time. I.e. how'd you represent +ia?.   Otherwise I'm fine with either.

Thanks,
Miklos

  reply	other threads:[~2021-06-11  7:55 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-06 14:46 Amir Goldstein
2021-06-08 13:52 ` Miklos Szeredi
2021-06-08 14:37   ` Amir Goldstein
2021-06-08 14:49     ` Miklos Szeredi
2021-06-08 15:33       ` Amir Goldstein
2021-06-08 18:20         ` Miklos Szeredi
2021-06-09  6:08           ` Amir Goldstein
2021-06-09  7:28             ` Miklos Szeredi
2021-06-09  7:57               ` Amir Goldstein
2021-06-11  7:31                 ` Amir Goldstein
2021-06-11  7:55                   ` Miklos Szeredi [this message]
2021-06-11  8:37                     ` Amir Goldstein
2021-06-11  8:39                       ` Miklos Szeredi

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