nak
The reason is listed in yesterday's email.
Coly Li wrote:
> dlm_get_lock_resource() is supposed to return a lock resource with a proper
> master. If multiple
> concurrent threads attempt to lookup the lockres for the same lockid, one or
> more threads are likely
> to return a lockres without a proper master, if the lock mastery is underway.
>
> This patch makes the threads wait in dlm_get_lock_resource() while the
> mastery is underway, ensuring
> all threads return the lockres with a proper master.
>
> This issue is known limited to users using the flock() syscall. For all other
> fs operations, dlmglue
> should ensure that only one thread is performing dlm operations for a given
> lockid at any one time.
>
> Thank Sunil for his review and comments.
>
> Signed-off-by: Coly Li <[EMAIL PROTECTED]>
> Cc: Sunil Mushran <[EMAIL PROTECTED]>
> Cc: Mark Fasheh <[EMAIL PROTECTED]>
> Cc: Jeff Mahoney <[EMAIL PROTECTED]>
> ---
> fs/ocfs2/dlm/dlmmaster.c | 11 +++++++++++
> 1 files changed, 11 insertions(+), 0 deletions(-)
>
> diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
> index 44f87ca..dd1e754 100644
> --- a/fs/ocfs2/dlm/dlmmaster.c
> +++ b/fs/ocfs2/dlm/dlmmaster.c
> @@ -742,6 +742,17 @@ lookup:
> goto lookup;
> }
>
> + /* wait for lock resource is being mastered by another thread */
> + spin_lock(&tmpres->spinlock);
> + if (tmpres->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
> + __dlm_wait_on_lockres_flags(tmpres,
> DLM_LOCK_RES_IN_PROGRESS);
> + spin_unlock(&tmpres->spinlock);
> + dlm_lockres_put(tmpres);
> + tmpres = NULL;
> + goto lookup;
> + }
> + spin_unlock(&tmpres->spinlock);
> +
> mlog(0, "found in hash!\n");
> if (res)
> dlm_lockres_put(res);
>
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