linux-ext4 - Re: [PATCH] ext4: Add support for SFITRIM, an ioctl for secure FITRIM.

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Date:	Tue, 17 Jun 2014 10:35:50 -0700
From:	JP Abgrall <jpa@...gle.com>
To:	Lukáš Czerner <lczerner@...hat.com>
Cc:	"Theodore Ts'o" <tytso@....edu>,
	Dave Chinner <david@...morbit.com>,
	Eric Sandeen <sandeen@...hat.com>, linux-ext4@...r.kernel.org,
	Geremy Condra <gcondra@...gle.com>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH] ext4: Add support for SFITRIM, an ioctl for secure FITRIM.

On Tue, Jun 17, 2014 at 6:00 AM, Lukáš Czerner <lczerner@...hat.com> wrote:
>
> What is the difference between -o discard mount option ?
Android will not mount -o discard because of the overall penalty.

> I guess
> that this way you can do it selectively on certain files, but I
> wonder how useful it is going to be anyway ?
For certain files only. Useful enough.


> If they are ok with only best effort, then we can have FISTRIM ioctl
> which would use the same internal file system functionality as
> FITRIM but we would add a flag to be able to call sb_issue_discard()
> with BLKDEV_DISCARD_SECURE flag,
I think this was the idea of the original patch.

> disable the optimization to skip
> already discarded groups and call sync on the file system before we
> start doing any actuall work.
That would need adding to the original patch.

> If we do this though we should not add word "security" anywhere for
> the use to see :)
We can live with that.
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