ext4: avoid modifying checksum fields directly during checksum verification

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

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index f7140ca66e3bf2751eb8103a37f249b49521b6ff..44ee5d933b362ac6bda994a2dbad71e68fffe134 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -51,25 +51,31 @@ static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
                              struct ext4_inode_info *ei)
 {
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-       __u16 csum_lo;
-       __u16 csum_hi = 0;
        __u32 csum;
+       __u16 dummy_csum = 0;
+       int offset = offsetof(struct ext4_inode, i_checksum_lo);
+       unsigned int csum_size = sizeof(dummy_csum);
 
-       csum_lo = le16_to_cpu(raw->i_checksum_lo);
-       raw->i_checksum_lo = 0;
-       if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
-           EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
-               csum_hi = le16_to_cpu(raw->i_checksum_hi);
-               raw->i_checksum_hi = 0;
-       }
+       csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw, offset);
+       csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, csum_size);
+       offset += csum_size;
+       csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
+                          EXT4_GOOD_OLD_INODE_SIZE - offset);
 
-       csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw,
-                          EXT4_INODE_SIZE(inode->i_sb));
-
-       raw->i_checksum_lo = cpu_to_le16(csum_lo);
-       if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
-           EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
-               raw->i_checksum_hi = cpu_to_le16(csum_hi);
+       if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
+               offset = offsetof(struct ext4_inode, i_checksum_hi);
+               csum = ext4_chksum(sbi, csum, (__u8 *)raw +
+                                  EXT4_GOOD_OLD_INODE_SIZE,
+                                  offset - EXT4_GOOD_OLD_INODE_SIZE);
+               if (EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
+                       csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum,
+                                          csum_size);
+                       offset += csum_size;
+                       csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
+                                          EXT4_INODE_SIZE(inode->i_sb) -
+                                          offset);
+               }
+       }
 
        return csum;
 }