#include <pthread.h>
#include <stdlib.h>

static pthread_mutex_t i_lock = PTHREAD_MUTEX_INITIALIZER;

static int inode_get_rsv_space(void)
{
  pthread_mutex_lock(&i_lock); // (4) ERROR
  // do something
  pthread_mutex_unlock(&i_lock);
  return 0;
}

static void add_dquot_ref(void)
{
#ifdef CONFIG_QUOTA_DEBUG
  int reserved = 0;
#endif

  int i, j;
  for (i=0; i<10; i++) {
    pthread_mutex_lock(&i_lock); // (2) lock is acquired
    if (rand() % 2) { // evaluates to false
      pthread_mutex_unlock(&i_lock);
      continue;
    }

#ifdef CONFIG_QUOTA_DEBUG
    if (inode_get_rsv_space() > 0) // (3)
      reserved = 1;
#endif

    pthread_mutex_unlock(&i_lock);
  }
}

int main(int argc, char** arv) {
  add_dquot_ref(); // (1)
  return 0;
}

diff --git a/simple/d7e9711.c b/simple/d7e9711.c
--- a/simple/d7e9711.c
+++ b/simple/d7e9711.c
@@ -26,12 +26,12 @@
       continue;
     }
 
+    pthread_mutex_unlock(&i_lock);
+
 #ifdef CONFIG_QUOTA_DEBUG
     if (inode_get_rsv_space() > 0) // (3)
       reserved = 1;
 #endif
-
-    pthread_mutex_unlock(&i_lock);
   }
 }
 

#include <pthread.h>
#include <stdlib.h>

static pthread_mutex_t i_lock = PTHREAD_MUTEX_INITIALIZER;

int main(int argc, char** arv) {
//  add_dquot_ref();
#ifdef CONFIG_QUOTA_DEBUG
  int reserved = 0;
#endif

  int i, j;
  for (i=0; i<10; i++) {
    pthread_mutex_lock(&i_lock);
    if (rand() % 2) {
      pthread_mutex_unlock(&i_lock);
      continue;
    }

#ifdef CONFIG_QUOTA_DEBUG
    pthread_mutex_lock(&i_lock); // ERROR
    // do something
    pthread_mutex_unlock(&i_lock);
    int i = 0;
    if (i > 0)
      reserved = 1;
#endif

    pthread_mutex_unlock(&i_lock);
  }
  return 0;
}

. call fs/quota/dquot.c:894:add_dquot_ref()
. 903: spin_lock(&inode->i_lock);
. 911: if (unlikely(inode_get_rsv_space(inode) > 0))
.. call fs/quota/dquot.c:1517: inode_get_rsv_space()
.. ERROR 1523: spin_lock(&inode->i_lock);