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Re: undeletion at filesystem level or in extra filesystem?
From: |
Thomas Bushnell, BSG |
Subject: |
Re: undeletion at filesystem level or in extra filesystem? |
Date: |
04 Oct 2002 11:41:13 -0700 |
User-agent: |
Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 |
Bryan Wagstaff <bryanw@xmission.com> writes:
> >But basically, yeah, if someone opens for O_WRONLY, writes, and
> >closes, it would be nice if the old contents were cleanly saved as a
> >"version".
> >
>
> That could get really nasty when it comes to large files that are
> opened/closed frequently. It also seems to open the door to some
> security problems.
"cleanly saved" might well include saving only differences.
> It wouldn't take long for a 10MB log file to take up an entire disk
> with new versions.
I should have specified opening O_WRONLY|O_CREAT|O_TRUNC; this is the
normal modes for "writing a file", and is very different from
appending to logs.
> Also, what about frequently used directories and
> their inodes?
You can't open a directory O_WRONLY.
> How about files/directories when affected by various
> translators? What would happen with compressed files being translated
> as directories?
Translators are a separate issue, but the answer would fall naturally
out of whether "cleanly saved" involves sharing an inode somehow or
not.
> What if I change one byte in a multi-gigabyte file
> with automatic versioning?
Then one could save only the small change.
> How would versions affect quotas: could I
> create a malicious program that peforms open/edit/close on a small
> file and consume the entire disk?
A malicious program could just write a big file.
> Automagic file versioning should probably be in the domain of
> applications, not the filesystem. If the filesystem were to support
> anything, it would be creating a list of inodes to use in each file,
> sort of like copy-on-write memory, instead using a copy-on-write
> inodes. But that gets back to the original problem of undelete.
You seem to be saying "there are lots of complicated questions here".
I agree, and I think we need clear correct answers before we start
trying versioning or undelete.
Thomas
- Re: undeletion at filesystem level or in extra filesystem?, Marcus Brinkmann, 2002/10/01
- Re: undeletion at filesystem level or in extra filesystem?, Niels Möller, 2002/10/01
- Re: undeletion at filesystem level or in extra filesystem?, Thomas Bushnell, BSG, 2002/10/01
- Re: undeletion at filesystem level or in extra filesystem?, Niels Möller, 2002/10/02
- Re: undeletion at filesystem level or in extra filesystem?, Thomas Bushnell, BSG, 2002/10/02
- Re: undeletion at filesystem level or in extra filesystem?, Bryan Wagstaff, 2002/10/03
- Re: undeletion at filesystem level or in extra filesystem?, Niels Möller, 2002/10/03
- Re: undeletion at filesystem level or in extra filesystem?, Thomas Bushnell, BSG, 2002/10/04
- Re: undeletion at filesystem level or in extra filesystem?, Bryan Wagstaff, 2002/10/04
- Re: undeletion at filesystem level or in extra filesystem?, Thomas Bushnell, BSG, 2002/10/04
- Re: undeletion at filesystem level or in extra filesystem?,
Thomas Bushnell, BSG <=
- Re: undeletion at filesystem level or in extra filesystem?, Roland McGrath, 2002/10/02
Re: undeletion at filesystem level or in extra filesystem?, Thomas Bushnell, BSG, 2002/10/01