From: Al Viro <viro@ZenIV.linux.org.uk>
To: Theodore Ts'o <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
Tony Lindgren <tony@atomide.com>,
Eric Biggers <ebiggers@google.com>,
Andreas Dilger <adilger@dilger.ca>,
Jaegeuk Kim <jaegeuk@kernel.org>,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-omap@vger.kernel.org
Subject: Re: Regression in next with ext4 oops
Date: Tue, 4 Oct 2016 15:59:15 +0100 [thread overview]
Message-ID: <20161004145915.GZ19539@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20161004140231.fyfrc6rs2lb6z63v@thunk.org>
On Tue, Oct 04, 2016 at 10:02:31AM -0400, Theodore Ts'o wrote:
> On Tue, Oct 04, 2016 at 11:00:41AM +0200, Jan Kara wrote:
> > Never seen this but I suspect it is a fallout from Al's directory locking
> > changes. In particular ext4_htree_fill_tree() builds rb-tree of found
> > directory entries in file->private_data (and generally modifies the
> > structure stored there) but after Al's changes we don't have exclusive
> > access to struct file if I'm right so if two processes end up calling
> > getdents() for the same 'struct file' we are doomed.
>
> I haven't seen it either, and I've been doing a lot of testing on the
> ext4 test branch. So I'm guessing Tony has the only reliable repro
> for the problem at the moment. That being said, it shouldn't be that
> hard to create a test case for this and add it to xfstests.
>
> I'm pretty sure Jan is right about this, though, but it would be great
> to a get a quick confirmation from Tony if at all possible.
Jan is wrong - we do have per-struct-file serialization for getdents()
et.al. It might be a race between getdents() on *different* struct
file for the same directory, but ->private_data is not a problem.
next prev parent reply other threads:[~2016-10-04 14:59 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-03 23:30 Regression in next with ext4 oops Tony Lindgren
2016-10-04 9:00 ` Jan Kara
2016-10-04 14:02 ` Theodore Ts'o
2016-10-04 14:44 ` Tony Lindgren
2016-10-04 14:59 ` Al Viro [this message]
2016-10-04 19:07 ` Theodore Ts'o
2016-10-04 19:19 ` Tony Lindgren
2016-10-04 19:16 ` Tony Lindgren
2016-10-04 19:29 ` Tony Lindgren
2016-10-04 19:41 ` Kalle Valo
2016-10-04 20:34 ` Tony Lindgren
2016-10-05 9:51 ` Kalle Valo
2016-10-04 14:18 ` Tony Lindgren
2016-10-04 14:56 ` Al Viro
2016-10-05 5:44 ` Jan Kara
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