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From: Arvin Schnell <aschnell@suse.de>
To: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] [RFC] Add btrfs autosnap feature
Date: Fri, 2 Mar 2012 12:34:21 +0100	[thread overview]
Message-ID: <20120302113421.GA6214@suse.de> (raw)
In-Reply-To: <CAE5mzvjiL+81AsSspTrE1A1BBiL27zJ1qK1oqCF27oL+-CG9Mw@mail.gmail.com>

On Thu, Mar 01, 2012 at 05:54:40AM -0600, cwillu wrote:

> There doesn't appear to be any reason for the scratch file to exist a=
t
> all (one can build up the hash while reading the directories), and
> keeping a scratch file in /etc/ is poor practice in the first place
> (that's what /tmp and/or /var/run is for).  It's also a lot of io to
> stat every file in the subvolume every time you make a snapshot, and
> I'm not convinced that the walk is actually correctly implemented:
> what stops an autosnap of / from including all of /proc and /sys in
> the hash?
>=20
> Perhaps all that is unnecessary:  rather than doing the walk, why not
> make use of btrfs subvolume find-new (or rather, the syscalls it
> uses)?

While developing snapper I faced similar problems and looked at
find-new but unfortunately it is not sufficient. E.g. when a file
is deleted find-new does not report anything, see the reply to my
mail here one year ago [1]. Also for newly created empty files
find-new reports nothing, the same with metadata changes.

If I'm wrong or find-new gets extended I happy to implement it in
snapper.

Regards,
  Arvin

[1] http://www.spinics.net/lists/linux-btrfs/msg08683.html

--=20
Arvin Schnell, <aschnell@suse.de>
Senior Software Engineer, Research & Development
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imend=F6=
rffer, HRB 16746 (AG N=FCrnberg)
Maxfeldstra=DFe 5
90409 N=FCrnberg
Germany
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  reply	other threads:[~2012-03-02 11:34 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-29  2:59 [RFC] [PATCH] Add btrfs autosnap feature asj
2012-02-29  2:59 ` [PATCH] [RFC] " asj
2012-02-29  3:38   ` Anand Jain
2012-03-01 11:54   ` cwillu
2012-03-02 11:34     ` Arvin Schnell [this message]
2012-03-02 12:04       ` cwillu
2012-03-02 12:25         ` Sander
2012-03-05  6:51     ` Anand Jain
2012-03-05  7:07       ` Fajar A. Nugraha
2012-03-05  7:18         ` Arne Jansen
2012-03-05 10:21       ` Anand Jain
2012-03-05 10:28         ` cwillu
2012-03-01 13:23   ` Roman Mamedov
2012-03-06  7:56 ` [PATCH 1/2] Make find_updated_files to return value instead of printing Anand jain
2012-03-06  7:56   ` [PATCH 2/2] Use transaction id to determin if there is any change in the subvol Anand jain
2012-03-06  9:07     ` [PATCH 2/2 v2] " Anand jain

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