1 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 69118b3cb917..4e41a4a331bb 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -261,6 +261,12 @@ struct iattr {
  */
 #include <linux/quota.h>
 
+/*
+ * Maximum number of layers of fs stack.  Needs to be limited to
+ * prevent kernel stack overflow
+ */
+#define FILESYSTEM_MAX_STACK_DEPTH 2
+
 /** 
  * enum positive_aop_returns - aop return codes with specific semantics
  *
@@ -1273,6 +1279,11 @@ struct super_block {
         struct list_lru         s_dentry_lru ____cacheline_aligned_in_smp;
         struct list_lru         s_inode_lru ____cacheline_aligned_in_smp;
         struct rcu_head         rcu;
+
+        /*
+         * Indicates how deep in a filesystem stack this SB is
+         */
+        int s_stack_depth;
 };
 
 extern struct timespec current_fs_time(struct super_block *sb);