BUG/MAJOR: buffer: fix incorrect check in __b_putblk()

This function was split in two at commit f7d0447 ("MINOR: buffers:
split b_putblk() into __b_putblk()") but it's wrong, the first half's
length is not adjusted to the requested size so it copies more than
desired.

This is purely 1.9-specific, no backport is needed.
1 file changed