From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>,
LINUXFS-ML <linux-fsdevel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>,
James Bottomley <jbottomley@parallels.com>,
xemul@openvz.org
Subject: Re: [patch 0/3] A few patches for dcache
Date: Fri, 29 Jul 2011 11:50:39 +0400 [thread overview]
Message-ID: <20110729075039.GD15883@sun> (raw)
In-Reply-To: <20110729072441.GA2203@ZenIV.linux.org.uk>
On Fri, Jul 29, 2011 at 08:24:41AM +0100, Al Viro wrote:
...
> > >
> > > Thanks for comments, Dave! Still the read only lock without
> > > increasing sequence number might be useful, no? (patch 1)
> >
> > I'll defer to Al on that one - the intricacies of the rename locking
> > are way over my head.
>
> I'm not sure that's safe. Note that one use of rename_lock is that
> we allow hash lookup to race with d_move(). Which can move object
> from one hash chain to another, so hash lookup may end up jumping
> from one chain to another and getting a false negative. That's
> why __d_lookup() is not safe without read_seqretry loop (or seq_writelock,
> of course).
>
...
Thanks a lot for explanations, Al!
Cyrill
next prev parent reply other threads:[~2011-07-29 7:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-28 13:12 [patch 0/3] A few patches for dcache Cyrill Gorcunov
2011-07-28 13:12 ` [patch 1/3] vfs, dcache: Introduce lighten r/o rename_lock lockers Cyrill Gorcunov
2011-07-28 13:12 ` [patch 2/3] vfs, dcache: Factor out rename_lock locking Cyrill Gorcunov
2011-07-28 13:12 ` [patch 3/3] vfs: Make the rename_lock per-sb Cyrill Gorcunov
2011-07-29 3:25 ` [patch 0/3] A few patches for dcache Dave Chinner
2011-07-29 5:59 ` Cyrill Gorcunov
2011-07-29 6:59 ` Dave Chinner
2011-07-29 7:01 ` Cyrill Gorcunov
2011-07-29 7:24 ` Al Viro
2011-07-29 7:50 ` Cyrill Gorcunov [this message]
2011-08-15 7:42 ` Cyrill Gorcunov
2011-08-24 6:31 ` Pavel Emelyanov
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