From: Erez Zadok <ezk@cs.sunysb.edu>
Date: Tue, 12 Aug 2014 02:49:44 +0000 (-0400)
Subject: Unionfs: fix d_revalidate for corner case
X-Git-Url: https://git.fsl.cs.sunysb.edu/?a=commitdiff_plain;h=0ecc29e5bd2bb889ea237ced74c3e3638b591c68;p=unionfs-2.6.18.y.git

Unionfs: fix d_revalidate for corner case

In some cases, lower_dentry may goes to NULL.  Return 0 here to mark it
as invalid dentry.

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Mengyang Li <li.mengyang@stonybrook.edu>
---

diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
index b8bdc0c6c6a..257022bfb4c 100644
--- a/fs/unionfs/dentry.c
+++ b/fs/unionfs/dentry.c
@@ -308,6 +308,11 @@ static int unionfs_d_revalidate(struct dentry *dentry,
 	parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
 	unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
 
+	if (!unionfs_lower_dentry(dentry)) {
+		err = 0;
+		goto out;
+	}
+
 	valid = __unionfs_d_revalidate(dentry, parent, false);
 	if (valid) {
 		unionfs_postcopyup_setmnt(dentry);
@@ -316,6 +321,7 @@ static int unionfs_d_revalidate(struct dentry *dentry,
 		d_drop(dentry);
 		err = valid;
 	}
+out:
 	unionfs_unlock_dentry(dentry);
 	unionfs_unlock_parent(dentry, parent);
 	unionfs_read_unlock(dentry->d_sb);