From 0222e52820d37f567ee2613d013dd3ad95c9cb6e Mon Sep 17 00:00:00 2001
From: Jaegeuk Kim <jaegeuk@kernel.org>
Date: Tue, 12 Apr 2016 16:05:36 -0700
Subject: [PATCH] ext4/fscrypto: avoid RCU lookup in d_revalidate

As Al pointed, d_revalidate should return RCU lookup before using d_inode.
This was originally introduced by:
commit 34286d666230 ("fs: rcu-walk aware d_revalidate method").

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: stable <stable@vger.kernel.org>

 Conflicts:
	fs/ext4/crypto.c
---
 fs/crypto/crypto.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 1447ea0538e4..a340a6f6f531 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -28,6 +28,7 @@
 #include <linux/ratelimit.h>
 #include <linux/bio.h>
 #include <linux/dcache.h>
+#include <linux/namei.h>
 #include <linux/fscrypto.h>
 
 static unsigned int num_prealloc_crypto_pages = 32;
@@ -352,6 +353,9 @@ static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
 	struct fscrypt_info *ci;
 	int dir_has_key, cached_with_key;
 
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
 	dir = dget_parent(dentry);
 	if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) {
 		dput(dir);