When a read or write operation fails on a sector found on the bad block table,

When a read or write operation fails on a sector found on the bad block table,
be sure to adjust the IOPB data pointer before redirecting the I/O for this
particular sector to the replacement location.

Otherwise, the data pointer still points to the first sector of the I/O, which
may not necessarily be the one which failed.

(This is yet another 19 years old bug, making your filesystems self-destruct
even faster than intended)