From: "Austin S. Hemmelgarn" <ahferroin7@gmail.com>
To: Al Viro <viro@ZenIV.linux.org.uk>, Stanislav Brabec <sbrabec@suse.cz>
Cc: linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
Btrfs BTRFS <linux-btrfs@vger.kernel.org>,
David Sterba <dsterba@suse.cz>
Subject: Re: loop subsystem corrupted after mounting multiple btrfs sub-volumes
Date: Mon, 29 Feb 2016 08:11:34 -0500 [thread overview]
Message-ID: <56D44386.8080101@gmail.com> (raw)
In-Reply-To: <20160226214514.GG17997@ZenIV.linux.org.uk>
On 2016-02-26 16:45, Al Viro wrote:
> On Fri, Feb 26, 2016 at 10:36:50PM +0100, Stanislav Brabec wrote:
>
>> It should definitely report error whenever trying -oloop on top of
>> anything else than a file. Or at least a warning.
>>
>> Well, even losetup should report a warning.
>
> Keep in mind that with crypto in the game it just might be useful to have
> loop-over-loop - it might be _not_ a no-op (hell, you might have two
> layers of encryption - not the smartest thing to do, but if that's what
> got dumped on your lap, you deal with what you've got). So such warnings
> shouldn't be hard errors.
>
That and that using a loop device is one of the ways to expose
partitions on a device the kernel doesn't normally expose them from. In
general, I'm pretty certain the preferred method is to use DM based
mappings, but those aren't always available, and I've had multiple cases
where I had to use nested loop devices to get to a filesystem.
You can't protect against everything, but you very much should not be
doing something that is known to cause issues, and the current behavior
of mount(8) WRT -o loop definitely can cause issues.
prev parent reply other threads:[~2016-02-29 13:12 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-25 19:22 loop subsystem corrupted after mounting multiple btrfs sub-volumes Stanislav Brabec
2016-02-26 12:33 ` Austin S. Hemmelgarn
2016-02-26 15:50 ` Stanislav Brabec
2016-02-26 16:39 ` Austin S. Hemmelgarn
2016-02-26 17:07 ` Stanislav Brabec
2016-02-26 18:22 ` Austin S. Hemmelgarn
2016-02-26 19:31 ` Stanislav Brabec
2016-02-26 17:53 ` Al Viro
2016-02-26 19:12 ` Stanislav Brabec
2016-02-26 20:05 ` Austin S. Hemmelgarn
2016-02-26 20:30 ` Al Viro
2016-02-26 20:36 ` Austin S. Hemmelgarn
2016-02-26 21:00 ` Stanislav Brabec
2016-02-26 22:00 ` Valdis.Kletnieks
2016-02-29 14:56 ` Stanislav Brabec
2016-03-01 13:44 ` Ming Lei
2016-04-12 18:38 ` Stanislav Brabec
2016-02-26 20:37 ` Stanislav Brabec
2016-02-26 21:03 ` Al Viro
2016-02-26 21:36 ` Stanislav Brabec
2016-02-26 21:45 ` Al Viro
2016-02-29 13:11 ` Austin S. Hemmelgarn [this message]
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