* [Cluster-devel] [GFS2 PATCH] GFS2: Only wait for demote when last holder is dequeued
[not found] <279720953.1497814.1403271354163.JavaMail.zimbra@redhat.com>
@ 2014-06-20 13:36 ` Bob Peterson
2014-06-20 14:18 ` Steven Whitehouse
0 siblings, 1 reply; 2+ messages in thread
From: Bob Peterson @ 2014-06-20 13:36 UTC (permalink / raw)
To: cluster-devel.redhat.com
Hi,
Function gfs2_glock_dq_wait is supposed to dequeue a glock and then
wait for the lock to be demoted. The problem is, if this is a shared
lock, its demote will depend on the other holders, which means you
might end up waiting forever because the other process is blocked.
This problem is especially apparent when dealing with nested flocks.
Regards,
Bob Peterson
Red Hat File Systems
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index aec7f73..22ce2f0 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1128,7 +1128,9 @@ void gfs2_glock_dq_wait(struct gfs2_holder *gh)
struct gfs2_glock *gl = gh->gh_gl;
gfs2_glock_dq(gh);
might_sleep();
- wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
+ if (!find_first_holder(gl))
+ wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait,
+ TASK_UNINTERRUPTIBLE);
}
/**
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [Cluster-devel] [GFS2 PATCH] GFS2: Only wait for demote when last holder is dequeued
2014-06-20 13:36 ` [Cluster-devel] [GFS2 PATCH] GFS2: Only wait for demote when last holder is dequeued Bob Peterson
@ 2014-06-20 14:18 ` Steven Whitehouse
0 siblings, 0 replies; 2+ messages in thread
From: Steven Whitehouse @ 2014-06-20 14:18 UTC (permalink / raw)
To: cluster-devel.redhat.com
Hi,
Now in the -nmw tree. Thanks,
Steve.
On 20/06/14 14:36, Bob Peterson wrote:
> Hi,
>
> Function gfs2_glock_dq_wait is supposed to dequeue a glock and then
> wait for the lock to be demoted. The problem is, if this is a shared
> lock, its demote will depend on the other holders, which means you
> might end up waiting forever because the other process is blocked.
> This problem is especially apparent when dealing with nested flocks.
>
> Regards,
>
> Bob Peterson
> Red Hat File Systems
>
> Signed-off-by: Bob Peterson <rpeterso@redhat.com>
> ---
> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
> index aec7f73..22ce2f0 100644
> --- a/fs/gfs2/glock.c
> +++ b/fs/gfs2/glock.c
> @@ -1128,7 +1128,9 @@ void gfs2_glock_dq_wait(struct gfs2_holder *gh)
> struct gfs2_glock *gl = gh->gh_gl;
> gfs2_glock_dq(gh);
> might_sleep();
> - wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
> + if (!find_first_holder(gl))
> + wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait,
> + TASK_UNINTERRUPTIBLE);
> }
>
> /**
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2014-06-20 13:36 ` [Cluster-devel] [GFS2 PATCH] GFS2: Only wait for demote when last holder is dequeued Bob Peterson
2014-06-20 14:18 ` Steven Whitehouse
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