[Ocfs2-devel] [PATCH 1/1] ocfs2 fix o2dlm dlm run purgelist

[Joel Becker <Joel.Becker@oracle.com>]

On Sat, Jun 19, 2010 at 12:56:11PM -0700, Srinivas Eeda wrote:
> There are two problems in dlm_run_purgelist
> 
> 1. If a lockres is found to be in use, dlm_run_purgelist keeps trying to purge
> the same lockres instead of trying the next lockres.
> 
> 2. When a lockres is found unused, dlm_run_purgelist releases lockres spinlock
> before setting DLM_LOCK_RES_DROPPING_REF and calls dlm_purge_lockres.
> spinlock is reacquired but in this window lockres can get reused. This leads
> to BUG.
> 
> This patch modifies dlm_run_purgelist to skip lockres if it's in use and purge
>  next lockres. It also sets DLM_LOCK_RES_DROPPING_REF before releasing the
> lockres spinlock protecting it from getting reused.
> 
> Signed-off-by: Srinivas Eeda <srinivas.eeda@oracle.com>

	I agree with everything Sunil said.  More below.

> +		/* Status of the lockres *might* change so double
> +		 * check. If the lockres is unused, holding the dlm
> +		 * spinlock will prevent people from getting and more
> +		 * refs on it -- there's no need to keep the lockres
> +		 * spinlock. */
> +		unused = __dlm_lockres_unused(lockres);

	There's no point in commenting about "no need to keep the
lockres spinlock" when you are now holding it through the operation.
You can drop everything after the '--'.

Joel

-- 

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Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127