ext4: avoid modifying checksum fields directly during checksum verification

[deliverable/linux.git] / fs / ext4 / namei.c

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index ec4c39952e847462c9a4a62f7d4bcc1afb74fd37..5bb46b6ed456c190be0892186a2e8b8f4967222b 100644 (file)
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -420,15 +420,14 @@ static __le32 ext4_dx_csum(struct inode *inode, struct ext4_dir_entry *dirent,
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        struct ext4_inode_info *ei = EXT4_I(inode);
        __u32 csum;
-       __le32 save_csum;
        int size;
+       __u32 dummy_csum = 0;
+       int offset = offsetof(struct dx_tail, dt_checksum);
 
        size = count_offset + (count * sizeof(struct dx_entry));
-       save_csum = t->dt_checksum;
-       t->dt_checksum = 0;
        csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)dirent, size);
-       csum = ext4_chksum(sbi, csum, (__u8 *)t, sizeof(struct dx_tail));
-       t->dt_checksum = save_csum;
+       csum = ext4_chksum(sbi, csum, (__u8 *)t, offset);
+       csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, sizeof(dummy_csum));
 
        return cpu_to_le32(csum);
 }