From 9050a9c9a2c0cfe61c164cacb016aaf7d0acb433 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@us.ibm.com>
Date: Sun, 29 Apr 2012 18:25:10 -0400
Subject: [PATCH] --- yaml --- r: 309932 b: refs/heads/master c:
 d25425f8e0ed01fc0167c043aee7e619fc3f6ab2 h: refs/heads/master v: v3

---
 [refs]                |  2 +-
 trunk/fs/ext4/super.c | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 1e82518e87cf..1560d0b86b8a 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e615391896064eb5a0c760d086b8e1c6ecfffeab
+refs/heads/master: d25425f8e0ed01fc0167c043aee7e619fc3f6ab2
diff --git a/trunk/fs/ext4/super.c b/trunk/fs/ext4/super.c
index e1fb1d5de58e..f489ffb3605d 100644
--- a/trunk/fs/ext4/super.c
+++ b/trunk/fs/ext4/super.c
@@ -112,6 +112,16 @@ static struct file_system_type ext3_fs_type = {
 #define IS_EXT3_SB(sb) (0)
 #endif
 
+static int ext4_verify_csum_type(struct super_block *sb,
+				 struct ext4_super_block *es)
+{
+	if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		return 1;
+
+	return es->s_checksum_type == EXT4_CRC32C_CHKSUM;
+}
+
 void *ext4_kvmalloc(size_t size, gfp_t flags)
 {
 	void *ret;
@@ -3025,6 +3035,14 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 		goto cantfind_ext4;
 	sbi->s_kbytes_written = le64_to_cpu(es->s_kbytes_written);
 
+	/* Check for a known checksum algorithm */
+	if (!ext4_verify_csum_type(sb, es)) {
+		ext4_msg(sb, KERN_ERR, "VFS: Found ext4 filesystem with "
+			 "unknown checksum algorithm.");
+		silent = 1;
+		goto cantfind_ext4;
+	}
+
 	/* Set defaults before we parse the mount options */
 	def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
 	set_opt(sb, INIT_INODE_TABLE);