From: Stanislav Brabec <sbrabec@suse.cz>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: "Austin S. Hemmelgarn" <ahferroin7@gmail.com>,
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: Fri, 26 Feb 2016 22:36:50 +0100 [thread overview]
Message-ID: <56D0C572.3050503@suse.cz> (raw)
In-Reply-To: <20160226210302.GE17997@ZenIV.linux.org.uk>
On Feb 26, 2016 at 22:03 Al Viro wrote:
And I'm not sure how
> to deal with -o loop in a sane way, TBH - automagical losetup is bloody
> hard to get right.
See another reply in this thread for the idea:
Fri, 26 Feb 2016 22:00:44 +0100
> Keep in mind that loop-over-loop is also possible...
Indeed! Let's remember that mount(8) should never do it.
# losetup /dev/loop0 /dev/sda2
# losetup /dev/loop1 /dev/loop0
# losetup -l
NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE
/dev/loop0 0 0 0 0 /dev/sda2
/dev/loop1 0 0 0 0 /dev/loop0
But it actually does, if the command line is "overlooped":
oct:~ # mount -oloop /dev/loop1 /mnt
as it does exactly that:
oct:~ # losetup -l
NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE
/dev/loop0 0 0 0 0 /dev/sda2
/dev/loop1 0 0 0 0 /dev/loop0
/dev/loop2 0 0 1 0 /dev/loop1
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.
--
Best Regards / S pozdravem,
Stanislav Brabec
software developer
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next prev parent reply other threads:[~2016-02-26 21:37 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 [this message]
2016-02-26 21:45 ` Al Viro
2016-02-29 13:11 ` Austin S. Hemmelgarn
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