core: glusterfsd keeping fd open in index xlator

Problem: At the time of processing GF_EVENT_PARENT_DOWN
         at brick xlator, it forwards the event to next xlator
         only while xlator ensures no stub is in progress.
         At io-thread xlator it decreases stub_cnt before the process
         a stub and notify EVENT to next xlator

Solution: Introduce a new counter to save stub_cnt and decrease
          the counter after process the stub completely at io-thread
          xlator.
          To avoid brick crash at the time of call xlator_mem_cleanup
          move only brick xlator if detach brick name has found in
          the graph

Note: Thanks to pranith for sharing a simple reproducer to
      reproduce the same

fixes bz#1637934
Change-Id: I1a694a001f7a5417e8771e3adf92c518969b6baa
Signed-off-by: Mohit Agrawal <moagrawal@redhat.com>

2 files changed, 15 insertions, 12 deletions

diff --git a/xlators/performance/io-threads/src/io-threads.c b/xlators/performance/io-threads/src/io-threads.c
index eac834a6c33..c98d1f6ada4 100644
--- a/xlators/performance/io-threads/src/io-threads.c
+++ b/xlators/performance/io-threads/src/io-threads.c
@@ -123,7 +123,7 @@ __iot_dequeue(iot_conf_t *conf, int *pri)
     if (!stub)
         return NULL;
 
-    GF_ATOMIC_DEC(conf->queue_size);
+    conf->queue_size--;
     conf->queue_sizes[*pri]--;
 
     return stub;
@@ -155,7 +155,8 @@ __iot_enqueue(iot_conf_t *conf, call_stub_t *stub, int pri)
     }
     list_add_tail(&stub->list, &ctx->reqs);
 
-    GF_ATOMIC_INC(conf->queue_size);
+    conf->queue_size++;
+    GF_ATOMIC_INC(conf->stub_cnt);
     conf->queue_sizes[pri]++;
 }
 
@@ -183,7 +184,7 @@ iot_worker(void *data)
                 conf->ac_iot_count[pri]--;
                 pri = -1;
             }
-            while (GF_ATOMIC_GET(conf->queue_size) == 0) {
+            while (conf->queue_size == 0) {
                 if (conf->down) {
                     bye = _gf_true; /*Avoid sleep*/
                     break;
@@ -230,6 +231,7 @@ iot_worker(void *data)
             } else {
                 call_resume(stub);
             }
+            GF_ATOMIC_DEC(conf->stub_cnt);
         }
         stub = NULL;
 
@@ -837,9 +839,9 @@ __iot_workers_scale(iot_conf_t *conf)
                                thread_name);
         if (ret == 0) {
             conf->curr_count++;
-            gf_msg_debug(
-                conf->this->name, 0, "scaled threads to %d (queue_size=%ld/%d)",
-                conf->curr_count, GF_ATOMIC_GET(conf->queue_size), scale);
+            gf_msg_debug(conf->this->name, 0,
+                         "scaled threads to %d (queue_size=%d/%d)",
+                         conf->curr_count, conf->queue_size, scale);
         } else {
             break;
         }
@@ -1231,7 +1233,7 @@ init(xlator_t *this)
     GF_OPTION_INIT("pass-through", this->pass_through, bool, out);
 
     conf->this = this;
-    GF_ATOMIC_INIT(conf->queue_size, 0);
+    GF_ATOMIC_INIT(conf->stub_cnt, 0);
 
     for (i = 0; i < GF_FOP_PRI_MAX; i++) {
         INIT_LIST_HEAD(&conf->clients[i]);
@@ -1282,7 +1284,7 @@ notify(xlator_t *this, int32_t event, void *data, ...)
 {
     iot_conf_t *conf = this->private;
     xlator_t *victim = data;
-    uint64_t queue_size = 0;
+    uint64_t stub_cnt = 0;
     struct timespec sleep_till = {
         0,
     };
@@ -1292,14 +1294,14 @@ notify(xlator_t *this, int32_t event, void *data, ...)
             clock_gettime(CLOCK_REALTIME, &sleep_till);
             sleep_till.tv_sec += 1;
             /* Wait for draining stub from queue before notify PARENT_DOWN */
-            queue_size = GF_ATOMIC_GET(conf->queue_size);
+            stub_cnt = GF_ATOMIC_GET(conf->stub_cnt);
 
             pthread_mutex_lock(&conf->mutex);
             {
-                while (queue_size) {
+                while (stub_cnt) {
                     (void)pthread_cond_timedwait(&conf->cond, &conf->mutex,
                                                  &sleep_till);
-                    queue_size = GF_ATOMIC_GET(conf->queue_size);
+                    stub_cnt = GF_ATOMIC_GET(conf->stub_cnt);
                 }
             }
             pthread_mutex_unlock(&conf->mutex);
diff --git a/xlators/performance/io-threads/src/io-threads.h b/xlators/performance/io-threads/src/io-threads.h
index f80fd41c45d..2980d18e74b 100644
--- a/xlators/performance/io-threads/src/io-threads.h
+++ b/xlators/performance/io-threads/src/io-threads.h
@@ -63,7 +63,8 @@ struct iot_conf {
     int32_t ac_iot_limit[GF_FOP_PRI_MAX];
     int32_t ac_iot_count[GF_FOP_PRI_MAX];
     int queue_sizes[GF_FOP_PRI_MAX];
-    gf_atomic_t queue_size;
+    int32_t queue_size;
+    gf_atomic_t stub_cnt;
     pthread_attr_t w_attr;
     gf_boolean_t least_priority; /*Enable/Disable least-priority */