[Ocfs2-devel] [PATCH] ocfs2: old mle put and release after the function dlm_add_migration_mle called.

[Guozhonghua]

If the old mle is found after the dlm_add_migration_mle called, it should be put once.
If the return value is not - EEXIST and its type is BLOCK, it should be put again to release it to avoid memory leak, for it had been unhashed from the map.

Signed-off-by: Guozhonghua <guozhonghua at h3c.com>

--- ocfs2.orig/dlm/dlmmaster.c  2016-11-08 16:58:30.233592715 +0800
+++ ocfs2/dlm/dlmmaster.c       2016-11-08 17:37:00.157673017 +0800
@@ -2621,20 +2621,45 @@ static int dlm_migrate_lockres(struct dl
        spin_lock(&dlm->master_lock);
        ret = dlm_add_migration_mle(dlm, res, mle, &oldmle, name,
                                    namelen, target, dlm->node_num);
+       if (ret == -EEXIST) {
+               if(oldmle)
+                       __dlm_put_mle(oldmle);
+
+               spin_unlock(&dlm->master_lock);
+               spin_unlock(&dlm->spinlock);
+               mlog(0, "another process is already migrating it\n");
+               goto fail;
+       }
+
+       /* If an old one mle found, it should be put. if its type is BLOCK,
+        * it should be put again. Because it had been unhasded from the map
+        * in the function dlm_add_migration_mle.
+        * otherwise the memory will be leaked. It will not found it again from
+        * the hash map.
+        */
+       if (oldmle) {
+               /* master is known, detach if not already detached */
+               __dlm_mle_detach_hb_events(dlm, oldmle);
+               __dlm_put_mle(oldmle);
+
+               /* if the type of the mle is BLOCK, should put it once for release.
+                * otherwise memory leak may be caused because oldmle had been unhashed
+                * from the hash map, it will not be found anymore.
+                */
+               if (oldmle->type == DLM_MLE_BLOCK)
+                       __dlm_put_mle(oldmle);
+       }
+
        /* get an extra reference on the mle.
         * otherwise the assert_master from the new
         * master will destroy this.
         */
        dlm_get_mle_inuse(mle);
+       mle_added = 1;
+
        spin_unlock(&dlm->master_lock);
        spin_unlock(&dlm->spinlock);

-       if (ret == -EEXIST) {
-               mlog(0, "another process is already migrating it\n");
-               goto fail;
-       }
-       mle_added = 1;
-
        /*
         * set the MIGRATING flag and flush asts
         * if we fail after this we need to re-dirty the lockres
@@ -2651,12 +2676,6 @@ static int dlm_migrate_lockres(struct dl
        }

 fail:
-       if (ret != -EEXIST && oldmle) {
-               /* master is known, detach if not already detached */
-               dlm_mle_detach_hb_events(dlm, oldmle);
-               dlm_put_mle(oldmle);
-       }
-
        if (ret < 0) {
                if (mle_added) {
                        dlm_mle_detach_hb_events(dlm, mle);
@@ -3191,16 +3210,23 @@ int dlm_migrate_request_handler(struct o
        if (ret < 0)
                kmem_cache_free(dlm_mle_cache, mle);

+       /* If an old one mle found, it should be put. if its type is BLOCK,
+        * it should be put again. Because it had been unhasded from the map
+        * in the function dlm_add_migration_mle.
+        * otherwise the memory will be leaked. It will not found it again from
+        * the hash map.
+        */
+       if (oldmle) {
+               __dlm_mle_detach_hb_events(dlm, oldmle);
+               __dlm_put_mle(oldmle);
+               if (ret >= 0 && oldmle->type == DLM_MLE_BLOCK)
+                       __dlm_put_mle(oldmle);
+       }
+
        spin_unlock(&dlm->master_lock);
 unlock:
        spin_unlock(&dlm->spinlock);

-       if (oldmle) {
-               /* master is known, detach if not already detached */
-               dlm_mle_detach_hb_events(dlm, oldmle);
-               dlm_put_mle(oldmle);
-       }
-
        if (res)
                dlm_lockres_put(res);
 leave:
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