From: Nigel Cunningham <ncunningham@crca.org.au>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Josef Bacik <josef@redhat.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
chris.mason@oracle.com, hch@lst.de
Subject: Re: [PATCH] Introduce freeze_super and thaw_super for the fsfreeze ioctl
Date: Wed, 24 Mar 2010 10:52:52 +1100 [thread overview]
Message-ID: <4BA95454.1080400@crca.org.au> (raw)
In-Reply-To: <20100323231802.GL30031@ZenIV.linux.org.uk>
Hi.
On 24/03/10 10:18, Al Viro wrote:
> On Wed, Mar 24, 2010 at 09:31:51AM +1100, Nigel Cunningham wrote:
>> /**
>> * freeze_filesystems - lock all filesystems and force them into a
>> consistent
>> * state
>> * @which: What combination of fuse& non-fuse to freeze.
>> */
>> void freeze_filesystems(int which)
>> {
>> struct super_block *sb;
>>
>> lockdep_off();
>>
>> /*
>> * Freeze in reverse order so filesystems dependant upon others are
>> * frozen in the right order (eg. loopback on ext3).
>> */
>
> [snip the horror]
>
> a) traversing superblock list without any locking whatsoever
> b) accessing superblock fields<....>
> c)<.........................> without making sure that it's not
> going to disappear
> d) calling freeze_bdev() without any warranties that its argument
> is not going to be freed under you
> e) layering violations all over the place
> etc.
>
> I've stayed away from TuxOnIce flamefests and I've no idea how representative
> that snippet is, but if it *does* match the general code quality in there...
> Ouch.
Locking isn't necessary because of the freezing.
Regards,
Nigel
next prev parent reply other threads:[~2010-03-23 23:52 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-23 14:22 [PATCH] Introduce freeze_super and thaw_super for the fsfreeze ioctl Josef Bacik
2010-03-23 14:28 ` Al Viro
2010-03-23 14:34 ` Josef Bacik
2010-03-23 14:48 ` Al Viro
2010-03-23 15:03 ` Josef Bacik
2010-03-23 15:09 ` Al Viro
2010-03-23 15:12 ` Al Viro
2010-03-23 15:15 ` Al Viro
2010-03-23 22:31 ` Nigel Cunningham
2010-03-23 23:18 ` Al Viro
2010-03-23 23:47 ` Al Viro
2010-03-23 23:52 ` Nigel Cunningham [this message]
2010-03-23 23:55 ` Nigel Cunningham
2010-03-24 0:21 ` Al Viro
2010-03-24 0:25 ` Nigel Cunningham
2010-03-24 0:03 ` Nigel Cunningham
2010-03-23 18:19 ` Sunil Mushran
2010-03-23 22:25 ` Nigel Cunningham
2010-03-24 1:17 ` Josef Bacik
2010-03-24 5:16 ` Nigel Cunningham
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