[Cluster-devel] [GFS2 PATCH] GFS2: Adjust lock reference count
Steven Whitehouse
swhiteho at redhat.com
Wed Mar 12 14:47:40 UTC 2014
Hi,
On Wed, 2014-03-12 at 10:32 -0400, Bob Peterson wrote:
> Hi,
>
> This patch closes a small timing window whereby a request to hold the
> transaction glock can get stuck. The problem is that after the DLM has
> granted the lock, it can get into a state whereby it doesn't transition
> the glock to a held state, due to not having requeued the glock state
> machine to finish the transition.
>
> Steve: Feel free to adjust the patch description as you see fit.
> I'm not feeling very creative at the moment.
>
> Regards,
>
> Bob Peterson
> Red Hat File Systems
>
I updated the description, and also converted the atomic_inc to lockref
- I guess that you didn't compile test this one. Anyway, that should
sort it out I think, so I've added it to the tree now, since we know
that the fix is needed,
Steve.
> Signed-off-by: Bob Peterson <rpeterso at redhat.com>
> ---
> fs/gfs2/glock.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
> index 52f7478..67ac456 100644
> --- a/fs/gfs2/glock.c
> +++ b/fs/gfs2/glock.c
> @@ -1047,9 +1047,13 @@ int gfs2_glock_nq(struct gfs2_holder *gh)
>
> spin_lock(&gl->gl_spin);
> add_to_queue(gh);
> - if ((LM_FLAG_NOEXP & gh->gh_flags) &&
> - test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
> + if (unlikely((LM_FLAG_NOEXP & gh->gh_flags) &&
> + test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))) {
> set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
> + atomic_inc(&gl->gl_ref);
> + if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
> + atomic_dec(&gl->gl_ref);
> + }
> run_queue(gl, 1);
> spin_unlock(&gl->gl_spin);
>
>
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