From: Christoph Anton Mitterer <calestyo@scientia.net>
To: Adam Borowski <kilobyte@angband.pl>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: Does data checksumming remain for files with No_COW file attribute?
Date: Sun, 25 Sep 2016 00:52:47 +0200 [thread overview]
Message-ID: <1474757567.9766.2.camel@scientia.net> (raw)
In-Reply-To: <20160924214454.GA25183@angband.pl>
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On Sat, 2016-09-24 at 23:44 +0200, Adam Borowski wrote:
> This would require teaching btrfs that, in some cases, a csum
> mismatch is no
> big thing and it can legitimately return junk data (like most other
> filesystems) rather than complaining. Same for scrub and btrfs
> check.
Well, I see no point in returning data that is not "guaranteed" to be
valid.
In case of a crash, one must assume that the data is bogus, and that's
what the program should get.
> chattr has no knowledge of btrfs whatsoever, and has no filesystem-
> specific
> code. It comes from e2fsprogs and from its internal naming of flags,
> I see
> it believes everything to be ext* -- but it doesn't actually have
> anything
> specific to ext*, either.
>
> Thus, any other filesystem can make use of +C (FS_NOCOW_FL), and
> there's no
> reason the "+C doesn't work on non-empty files" rule needs to hold on
> btrfs
> in the future.
Well chattr must probably call some btrfs ioctl or so... and that
should simply give an error back... and chattr at least print some
generic error message.
Or this should be rather replaced with a btrfs specific tool.
Cheers,
Chris.
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prev parent reply other threads:[~2016-09-24 22:52 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-24 12:26 Does data checksumming remain for files with No_COW file attribute? Alexander Tomokhov
2016-09-24 12:37 ` Hugo Mills
2016-09-24 23:25 ` Alexander Tomokhov
2016-09-24 23:50 ` Adam Borowski
2016-09-25 5:44 ` Duncan
2016-09-26 20:41 ` Adam Borowski
2016-09-24 12:40 ` Roman Mamedov
2016-09-24 12:43 ` Hugo Mills
2016-09-24 18:11 ` Christoph Anton Mitterer
2016-09-25 13:49 ` Goffredo Baroncelli
2016-09-25 19:53 ` Christoph Anton Mitterer
2016-09-26 11:11 ` Austin S. Hemmelgarn
2016-09-24 18:09 ` Christoph Anton Mitterer
2016-09-24 21:44 ` Adam Borowski
2016-09-24 22:52 ` Christoph Anton Mitterer [this message]
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