[Ocfs2-devel] [PATCH] ocfs2/dlm: do not insert a new mle when another process is already migrating

[Junxiao Bi <junxiao.bi@oracle.com>]

On 12/25/2015 04:34 PM, xuejiufei wrote:
> When two processes are migrating the same lockres,
> dlm_add_migration_mle() return -EEXIST, but insert a new mle in
> hash list. Function dlm_migrate_lockres will detach the ole mle
> and free the new one which is already in hash list, that will
> destroy the list.
> 
> Signed-off-by: Jiufei Xue <xuejiufei@huawei.com>
> Reviewed-by: Joseph Qi <joseph.qi@huawei.com>
Looks good.
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
> ---
>  fs/ocfs2/dlm/dlmmaster.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
> index 936e11b..753dd9c 100644
> --- a/fs/ocfs2/dlm/dlmmaster.c
> +++ b/fs/ocfs2/dlm/dlmmaster.c
> @@ -2544,7 +2544,7 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm,
>  	}
> 
>  fail:
> -	if (oldmle) {
> +	if (ret != -EEXIST && oldmle) {
>  		/* master is known, detach if not already detached */
>  		dlm_mle_detach_hb_events(dlm, oldmle);
>  		dlm_put_mle(oldmle);
> @@ -3141,7 +3141,8 @@ static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
>  				mlog(0, "tried to migrate %.*s, but some "
>  				     "process beat me to it\n",
>  				     namelen, name);
> -				ret = -EEXIST;
> +				spin_unlock(&tmp->spinlock);
> +				return -EEXIST;
>  			} else {
>  				/* bad.  2 NODES are trying to migrate! */
>  				mlog(ML_ERROR, "migration error  mle: "
>