[Ocfs2-devel] [PATCH] Wakeup down-convert thread just after clearing OCFS2_LOCK_UPCONVERT_FINISHING -v3

[Sunil Mushran]

I am fine with the kick in recover from dlm error. Not so in cluster lock.
We have to be very very sure before meddling with that function. It is
a state machine with many hidden gotchas.

So is this patch for a bug encountered or just code audit. Also, what kind
testing has been done.

On 09/14/2011 08:27 PM, Wengang Wang wrote:
> When the lockres state UPCONVERT_FINISHING is cleared,
> we should wake up the downconvert thread incase that lockres
> is in the blocked queue. Currently we are not doing so and thus
> are at the mercy of another event waking up the dc thread.
>
> Signed-off-by: Wengang Wang<wen.gang.wang at oracle.com>
> ---
>   fs/ocfs2/dlmglue.c |    9 ++++++++-
>   1 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
> index 7642d7c..524bd88 100644
> --- a/fs/ocfs2/dlmglue.c
> +++ b/fs/ocfs2/dlmglue.c
> @@ -1195,6 +1195,7 @@ static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
>   						int convert)
>   {
>   	unsigned long flags;
> +	int kick_dc;
>
>   	spin_lock_irqsave(&lockres->l_lock, flags);
>   	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
> @@ -1203,9 +1204,12 @@ static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
>   		lockres->l_action = OCFS2_AST_INVALID;
>   	else
>   		lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
> +	kick_dc = (lockres->l_flags&  OCFS2_LOCK_QUEUED);
>   	spin_unlock_irqrestore(&lockres->l_lock, flags);
>
>   	wake_up(&lockres->l_event);
> +	if (kick_dc)
> +		ocfs2_wake_downconvert_thread(ocfs2_get_lockres_osb(lockres));
>   }
>
>   /* Note: If we detect another process working on the lock (i.e.,
> @@ -1373,6 +1377,7 @@ static int __ocfs2_cluster_lock(struct ocfs2_super *osb,
>   	unsigned long flags;
>   	unsigned int gen;
>   	int noqueue_attempted = 0;
> +	int kick_dc;
>
>   	ocfs2_init_mask_waiter(&mw);
>
> @@ -1500,8 +1505,10 @@ update_holders:
>   	ret = 0;
>   unlock:
>   	lockres_clear_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);
> -
> +	kick_dc = (lockres->l_flags&  OCFS2_LOCK_QUEUED);
>   	spin_unlock_irqrestore(&lockres->l_lock, flags);
> +	if (kick_dc)
> +		ocfs2_wake_downconvert_thread(osb);
>   out:
>   	/*
>   	 * This is helping work around a lock inversion between the page lock