dm: fix request-based dm error reporting
end_clone_bio() is a endio callback for clone bio and should check
and save the clone's bi_error for error reporting. However,
4246a0b63bd8 ("block: add a bi_error field to struct bio") changed
the function to check the original bio's bi_error, which is 0.
Without this fix, clone's error is ignored and reported to the
original request as success. Thus data corruption will be observed.
Fixes:
4246a0b63bd8 ("block: add a bi_error field to struct bio")
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>