From: Roman Mamedov <rm@romanrm.net>
To: "Austin S. Hemmelgarn" <ahferroin7@gmail.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: Unexpected behavior involving file attributes and snapshots.
Date: Tue, 14 Feb 2017 20:55:31 +0500 [thread overview]
Message-ID: <20170214205531.15b5b2f3@natsu> (raw)
In-Reply-To: <ea92c7c6-4b98-d683-eb66-593836bcc82a@gmail.com>
On Tue, 14 Feb 2017 10:30:43 -0500
"Austin S. Hemmelgarn" <ahferroin7@gmail.com> wrote:
> I was just experimenting with snapshots on 4.9.0, and came across some
> unexpected behavior.
>
> The simple explanation is that if you snapshot a subvolume, any files in
> the subvolume that have the NOCOW attribute will not have that attribute
> in the snapshot. Some further testing indicates that this is the only
> file attribute that isn't preserved (I checked all the chattr flags that
> BTRFS supports).
>
> I'm kind of curious whether:
> 1. This is actually documented somewhere, as it's somewhat unexpected
> given that everything else is preserved when snapshotting.
> 2. This is intended behavior, or just happens to be a side effect of the
> implementation.
I don't seem to get this on 4.4.45 and 4.4.47.
$ btrfs sub create test
Create subvolume './test'
$ touch test/abc
$ chattr +C test/abc
$ echo def > test/abc
$ ls -la test/abc
-rw-r--r-- 1 rm rm 4 Feb 14 20:52 test/abc
$ lsattr test/abc
---------------C test/abc
$ btrfs sub snap test test2
Create a snapshot of 'test' in './test2'
$ ls -la test2/abc
-rw-r--r-- 1 rm rm 4 Feb 14 20:52 test2/abc
$ lsattr test2/abc
---------------C test2/abc
--
With respect,
Roman
next prev parent reply other threads:[~2017-02-14 15:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-14 15:30 Unexpected behavior involving file attributes and snapshots Austin S. Hemmelgarn
2017-02-14 15:55 ` Roman Mamedov [this message]
2017-02-14 16:07 ` Chris Murphy
2017-02-14 16:46 ` Austin S. Hemmelgarn
2017-02-14 17:52 ` Austin S. Hemmelgarn
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