locks: turn lock_flocks into a spinlock

Nothing depends on lock_flocks using the BKL
any more, so we can do the switch over to
a private spinlock.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

fs/locks.c

@@ -142,6 +142,7 @@ int lease_break_time = 45;
 
 static LIST_HEAD(file_lock_list);
 static LIST_HEAD(blocked_list);
+static DEFINE_SPINLOCK(file_lock_lock);
 
 /*
  * Protects the two list heads above, plus the inode->i_flock list
@@ -149,13 +150,13 @@ static LIST_HEAD(blocked_list);
  */
 void lock_flocks(void)
 {
-	lock_kernel();
+	spin_lock(&file_lock_lock);
 }
 EXPORT_SYMBOL_GPL(lock_flocks);
 
 void unlock_flocks(void)
 {
-	unlock_kernel();
+	spin_unlock(&file_lock_lock);
 }
 EXPORT_SYMBOL_GPL(unlock_flocks);