From: Christoph Hellwig <hch@infradead.org>
To: Bill McDuck <billmcdave@gmail.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: Significantly longer fallocate times with Flag Unwritten Extents disabled
Date: Wed, 8 Mar 2017 07:56:02 -0800 [thread overview]
Message-ID: <20170308155602.GE4353@infradead.org> (raw)
In-Reply-To: <CAEOfVRnuTD0AWNSE+_-3KVL_xTcgrq5Q8+mm0mEQYua7gaGQiQ@mail.gmail.com>
On Mon, Mar 06, 2017 at 12:02:01PM +0000, Bill McDuck wrote:
> Hello.
>
> I have been testing the performance of XFS with "Flag Unwritten
> Extents" enabled and disabled.
Why do you disable it? It's been part of the defauly on feature
set for a decade, and manually disabling it will make you run into
completely untested code. There is a reason it's mandatory for v5
file systems.
>
> For security reasons I know XFS flags all unwritten extents by
> default, so that uninitialized disk space cannot be read by the user.
> In my application I actually want to have access to this uninitialized
> disk space. I have been modifying the superblocks using xfs_repair to
> enable this functionality.
Don't do that, it's not supported for a reason.
next prev parent reply other threads:[~2017-03-08 16:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-06 12:02 Significantly longer fallocate times with Flag Unwritten Extents disabled Bill McDuck
2017-03-06 13:05 ` Brian Foster
2017-03-08 15:56 ` Christoph Hellwig [this message]
2017-03-08 16:48 ` Bill
2017-03-08 21:50 ` Dave Chinner
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