Hi, Sorry to bother you.
> Basically, a 128-byte inode inside a filesystem that allocated 256 bytes
> for each inode. As you point out, the old code would checksum the entire
> allocated space, whether or not the inode core used it. Obviously, you
> want this since inline extended attributes live in that space:
> csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw,
> EXT4_INODE_SIZE(inode->i_sb));
> The new code, on the other hand, carefully checksums around the
> i_checksum fields and only bothers to checksum the space between the end
> of i_checksum_hi and the end of the allocated space if the inode core is
> big enough to store i_checksum_hi. Since we allocated 256 bytes for
> each inode, we checksum the first two bytes after byte 128
> (EXT4_GOOD_OLD_INODE_SIZE), but then we see that i_extra_size == 0 so we
> never bother to checksum anything after that. This is of course wrong
> since we no longer checksum the xattr space and we've deviated from the
> pre-4.7.4 (documented) on-disk format.
Oops. I had overlooked the case of that i_extra_size is less than 4.
I misunderstood the previous Darrick's codes calculating inode checksum value.
Sorry about that. :-(
> 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);
> }
>
> Can you give that a try?
Darrick, your modification looks good enough to me.
Thank you, guys.
